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STRATEGIES FOR VEHICLE WASTE- OIL MANAGEMENT IN PAKISTAN
A thesis submitted by
Agha Hassan Ali Khan Durrani
In accordance with the requirements for the degree of
Doctor of Philosophy
In
Mechanical Engineering
Department of Mechanical Engineering
Faculty of Engineering
Mehran University of Engineering & Technology
Jamshoro, Pakistan
2010
i
DEDICATION
THIS EFFORT OF MINE IS GRATEFULLY DEDICATED
TO
MY PARENTS
&
MY FAMILY
WHO DID THEIR BEST TO UPLIFT ME TO THE HEIGHTS OF AN IDEAL LIFE
ii
MEHRAN UNIVERSITY OF ENGINEERING & TECHNOLOGY JAMSHORO
This thesis, written by Agha Hassan Ali Khan Durrani under the direction of his
supervisors, and approved by all the members of thesis committee, has been
presented to and accepted by the Dean, Faculty of Engineering, in fulfillment of the
requirements of the degree of Doctor of Philosophy in Mechanical Engineering.
_________ __________ _______________ _______________
Supervisor Co-supervisor Internal Examiner External Examiner
_________________________ _________________________
(Director Postgraduate Studies) (Dean, Faculty of Engineering)
Date: _________________
iii
ACKNOWLEDGEMENTS
First and foremost I want to pay deep gratitude to Almightily Allah the Omnipresent,
who bestowed upon me the potential and ability to accomplish this cordial task.
It is a great honor for me to express my sincere appreciation to my thesis supervisor
Professor Dr. Rafiq Akthar Kazi for his continuous support, valuable guidance,
positive criticism, remained most generous with his precious time, provided many
useful ideas and encouragement. I shall never forget his patience to hear my problems
at every processing stage of research work and their solutions.
Gratitude is extended to my co-supervisor Professor Dr. M.I. Panhwar for his
courageous advice, guidance and helpful suggestions during my study. He is the one,
who helped lot in the progress of work and for his keen interest in write up I came to
produce this worth full draft.
I am very much grateful to Professor Dr Hafeez-ur-Rehman Memon, Director
Institute of Petroleum & Natural Gas Engineering who allowed me to carry out
laboratory experimental work in Petroleum Refinery Laboratory.
Sincere thanks to Professor Dr Ghous Bux Khaskheli Director Post Graduate Studies
for his timely response and help during my study.
I am also very much grateful to the worthy Vice Chancellor of Mehran University of
Engineering & Technology, Jamshoro and all the ASRB members for providing
financial assistant and research facilities for completing my PhD work.
iv
TABLE OF CONTENTS
Description Page
Acknowledgements iv Table of contents v List of Notations ix List of Abbreviations x List of Tables xii List of Figures xiv Abstract xvi Chapter 1 INTRODUCTION
1.1 Introduction 1 1.2 General treatment methods 2 1.3 Justification 4 1.4 Aims and Objectives 5 1.5 Research scope 5 1.6 Structure of the thesis 5
Chapter 2 LITERATURE REVIEW 2.1 General overview 6 2.2 Lubricating oil 6 2.3 Base oil 9 2.4 Used oil 10 2.5 Properties and characteristics 12 of used lubricant oil 2.5.1 Contaminants 14 2.6 Quantifying used oil 17 2.7 Waste oil management 19
2.7.1 Management options 21 2.7.2 Acid /clay treatment 23 2.7.3 Distillation /hydro-treatment 25 2.7.4 Solvent extraction re-refining 26 2.7.3.1 Single solvent as 29 extracting solvent 2.7.3.2 Composite solvent 30
an extracting solvent 2.8 SOLUBILITY 31 2.8.1 Coagulation, flocculation and aggregation 33 2.8.2 Mixing of flocculation 37 2.8.3 Addition of potassium hydroxide 38 2.8.4 Sedimentation consolidation 38 2.9 SYSTEM DESIGN 40
2.9.1 Pilot plant scale 41 2.9.2 Process mechanism 42 2.10 RE-REFINED BASE OIL QUALITY 42
v
Chapter 3. WASTE OIL MANAGEMENT 3.1 Introduction 44 3.2 Properties & Characteristics 46 of used lubricant oil 3.3 Waste crankcase oil disposal 46 practices in Pakistan 3.4 WASTE OIL MANAGEMENT OPTIONS. 48 3.4.1 Reprocessing 49 3.4.2 Reclamation 49
3.4.3 Regenerating /re-refining 49 3.4.4 Destruction 50 3.4.5 Exporting to facilities abroad 50 3.4.6 Other reuse practices 51
3.5 SUITABLE METHODS FOR WASTE OIL 51 RE-GENERATION 3.5.1 Acid/clay treatment 51 3.5.2 Solvent extraction re-refining 52 Chapter 4. EXPERIMENTAL WORK AND METHODOLOGY 4.1 Introduction 55 4.2 Quantifying vehicle waste oil 55 4.2.1 Field Survey of Principal Sources 55 4.2.2 Number of vehicles registered 56 4.2.3 Crankcase size 56 4.2.4 Engine oil change 56 4.2.5 Number of time oil change per year 56 4.2.6 Engine oil consumption 60 4.2.7 Quantification of used oil 61 4.2.8 Used oil collection and transportation 65 4.2.9 Proposed used oil re-generation 66 Locations 4.3 Materials 68 4.4 Analysis and tests methods. 68 4.5 Laboratory scale experimental work 69 4.5.1Physical properties of used lubricating oil 69 4.5.2 Dehydration of used oil experiment No. 1 69 4.5.3 Acid-clay treatment 70 4.5.3.1 Experiment No. 1 70 4.5.3.2 Experiment No. 2 72 4.5.3.3 Experiment No. 3 74 4.5.3.4 Experiment No. 4 76 4.6 Solvent extraction treatment 79 4.6.1 Solvents 79 4.6.2 Determining an effective solvent 79 extraction parameters 4.6.3 Solvent extraction process 80
4.6.3.1 Percent sludge removal 80 4.6.3.2 Percentage oil loss 81 4.6.3.3 Performance of solvent 1- 81
butanol (Experiment No.1)
vi
4.6.3.4 Performance of solvent 2-propano (Experiment No.2) 83
4.6.3.5 Performance of MEK 84 (Experiment No.3) 4.6.3.6 Solvent extraction treatment 85 (Experiment No.4) 4.6.3.7 Sedimentation 88 4.6.3.8 Solvent extraction treatment 88
(Experiment No.5) 4.6.3.9 Sedimentation 90
4.6.3.10 (Experiment No.6) 91 4.6.3.11 Sedimentation 92 4.7 EXPERIMENTAL RIG DESIGN AND 93 FABRICATION 4.7.1 Process description (Acid/ clay treatment) 97 4.7.2 Process description (Solvent 98 extraction process) 4.7.3 Pilot scale experiment Acid/clay and 99 solvent extraction 4.7.3.1(ExperimentNo.1) 99 4.7.3.2(Experiment No.2) 102
4.7.3.3 (Experiment No.3) 104 4.7.3.4 (Experiment No.4) 106 4.7.3.5 (Experiment No.5) 108
Chapter 5 RESULTS AND DISCUSSIONS 5.1 LABORATORY EXPERIMENTAL WORK ON 110 5.1.1Dehyderation 110
5.1.2 Acid clay treatment 113 5.1.3 Solvent extraction treatment 122
5.1.3.1 Determining an effective 122 solvent 5.1.3.2 Effect of solvent type 137 5.1.4 Solvent Extraction Treatment 141 5.1.4.1 Sedimentation 141 5.1.4.2 Effect on oil quality 144 5.1.4.3 Sedimentation 146
5.1.4.4 Effect on oil quality 150 5.2 PILOT SCALE EXPERIMENTAL RIG 150
DESIGN AND FABRICATION 5.2.1 Pilot scale acid clay treatment process 151 5.2.2 Pilot scale solvent extraction treatment 155
vii
Chapter 6 CONCLUSIONS AND RECOMMENDATIONS 6.1 Conclusions 161 6.2 Recommendation 163 6.3 Suggestions for future work 164
REFERENCES 165
APPENDICES 179
viii
LIST OF NOTATIONS C Cohesive energy density
∆H Heat of vaporization
T Temperature
Vm Molar volume
R Gas constant
δ Solubility parameter
CX –OH several type of alchohol
K+ Ion of Kalium / Potassium
H+ Ion of Hydrogen
Zo Initial total depth of suspension
ix
LIST OF ABBREVIATIONS
ASTM = American Society of Testing of Material
BTU = British Thermal Unit
BERC = Bartlesville Energy Research Center 0C = Celsius degree temperature
DMF = Dimethylformamide
EPA = vironmental Protection Agencies
gm = Gram
Kg = Kilogram
Km = Kilometer
KOH = Potassium hydroxide
KTI = Kinetics Technology International
LPG = Liquid Petroleum Gas
m2 = Meter square
MEK = Methyl Ethyl Ketone
Hg = Mercury
ml = Milliliter
mm = Millimeter
HNO3 = Nitric Acid
NIPER = National Institute of Petroleum and Energy Research
NTRCI = National Transport Research Centre Islamabad
NMP = N-methyl-2-pyrrolidone
ppm = Parts per million
POL = Percentage of OIL Loss
PSR = Percentage of Sludge Removal
PCBs = Polyclorinated biphnyls
PAHs = Polycyclic aromatic hydrocarbons
SOL = Solvent-oil losses
H2SO4 = Sulfuric Acid
VI = Viscosity index
Vol = Volume
x
WCO = Waste crankcase lubricant oil
Wt = Weight
Wwet = Weight of Wet Sludge
Wdry = Weight of Dry Sludge
Woil = Weight of Oil
USEPA = United State Environmental Protection Agencies
xi
LIST OF TABLES
Table 2.1: Typical composition of lubricating oil 7 Table 2.2: Types and function of lubricating oil additives 8 Table 2.3: Used oil by USEPA’S definition. 11 Table 2.4: Comparison of virgin and used oil lubricating properties 13 Table 2.5: Contaminants in used lube oil 14 Table 2.6: Composition of used oil contaminants 14 Table 2.7: Effect of solvent extraction system on used oil 32 Table 2.8: Guidelines for quality acceptance of re-refined base oil 43 Table 3.1: Principal contaminants in used oil 45 Table 3.2: Current vehicle waste-oil disposal practices in Pakistan 48 Table 3.3: Waste oil management option in Pakistan 53 Table 4.1: Motor vehicles on road 57 Table 4.2: Crankcase size 58 Table 4.3: Oil change interval 59 Table 4.4: Number of time oil change per year 60 Table 4.5: Vehicle waste oil generation 63 Table 4.6: New oil v/s waste oil generated 64 Table 4.7: Standard lubricating oil testing methods 68 Table 4.8: Process variables of acid clay treatment (Experiment No.1) 71 Table 4.9: Process variables of acid clay treatment (Experiment No.2) 73 Table 4.10: Process variables of acid clay treatment (Experiment No. 3) 75 Table 4.11: Process variables of acid clay treatment (Experiment No. 4) 78 Table 4.12: Oil losses percent using 1-butanol at 20 oC 81 Table 4.13: Oil losses percent using 1-butanol at 30 oC 82 Table 4.14: Oil losses percent using 1-butanol at 50 oC 82 Table 4.15: Oil losses percent using 2-propanol at 20 oC 83 Table 4.16: Oil losses percent using 2-propanol at 30 oC 83 Table 4.17: Oil losses percent using 2-propanol at 50 oC 84 Table 4.18: Oil losses percent using MEK at 20 oC 84 Table 4.19: Oil losses percent using MEK at 30 oC 85 Table 4.20: Oil losses percent using MEK at 50 oC 85 Table4.21: Process parameters of solvent extraction of KOH (Experiment No.5) 87 Table 4.22: Optimum solvent oil ratio and amount of KOH 88 Table 4.23: Optimum solvent oil ratio and amount of sludge removal 89 composite solvent 40% 2-propanol, 35% 1-butanol and 25% butanone and used oil (Experiment No.6) Table 4.24: Process parameters of solvent extraction of 90 solvent 40% 2-propanol, 35% 1-butanol and 25% butanone
and used oil Table 4.25: Optimum solvent oil ratio and amount of sludge removal 91 composite solvent 25% 2-propanol, 37% 1-butanol and 38% butanone and used oil (Experiment No.7) Table 4.26: Process parameters of solvent extraction (Experiment No.7) 92 Table 4.27: List of the equipments 94
xii
Table 4.28 Process parameters for acid clay treatment process pilot scale 101 (Experiment No. 1) Table 4.29: Process parameters for acid clay treatment process pilot scale 103 (Experiment No. 2) Table4.30: Process parameters for solvent extraction treatment process pilot scale 105 (Experiment No.3) Table4.31: Process parameters for solvent extraction treatment process pilot scale 107 (Experiment No.4). Table 4.32 Process parameters for solvent extraction treatment process pilot scale 109 (Experiment No.5). Table 5.1: Dehydration of used oil 112 Table 5.2: Properties of re-generated oil Acid-Clay treatment 115 Table 5.3: Regenerated base-oil properties of re-generated oil 118 Acid-Clay treatment Table 5.4: Regenerated base-oil properties Acid-clay treatment 119 Table 5.5: Regenerated base-oil properties Acid-clay treatment 121 Table 5.6: Regenerated base-oil properties of Solvent Extraction 144 Table 5.7: Regenerated base-oil properties 146 Table 5.8: Regenerated base-oil properties 148 Table 5.9:Re-generation lube oil properties Acid Clay Treatment (Pilot Scale) 153 Table 5.10: Regenerated Base-oil Properties (zeolite) 155 Table 5.11: Regenerated Base-oil Properties by Solvent Extraction Process 157
Pilot Scale Table 5.12: Regenerated Base-oil Properties by Solvent Extraction Process 158 Pilot scale Table 5.13: Regenerated Base-oil Properties by Solvent Extraction Process 160
xiii
LIST OF FIGURES
Figure 2.1: Flow diagram acid/clay treatment process 24 Figure 2.2: Flow diagram KTI – Re-refining process 26 Figure 2.3: Block diagram of solvent extraction process 27 Figure 2.4: Diagram of particle-cluster & cluster- cluster aggregation 34 Figure 2.5: Bridging flocculation 35 Figure 2.6: Aggregation via polymer bridging 36 Figure 2.7: Schematic illustration of the stages involved in flocculation 37 by polymer addition Figure 2.8: Flocculation-sedimentation-consolidation 39 Figure 2.9: Block diagram of pilot plant 41 Figure 3.1 Disposal practice of vehicle waste oil in Pakistan 47 Figure 3.2: Flow diagram of re-processing and re-refining process 54 Figure 41: New oil v/s waste oil generated in years 1990 to march 2006 62 Figure 4.2: Proposed used oil collection net work 66 Figure.4.3: Proposed Regeneration Locations 67 Figure 4.4: Waste oil re-refining process used catalyst zeolite 77 Figure 4.5: Waste oil re-refining process by solvent extraction process 80 Figure 4.6: Pilot scale flow diagram of acid clay treatment process 95 Figure 4.7: Pilot scale flow diagram of solvent extraction process 96 Figure 5.1: Regenerated oil recoveries by acid clay treatment 115 Figure 5.2: Regenerated oil recoveries by acid clay treatment 117 Figure 5.3: Regenerated oil recoveries by acid clay treatment 119 Figure 5.4: Regenerated oil recoveries by acid clay treatment 121 Figure 5.5: Effect of solvent: oil ratio on the extraction measured by 123 the percent of oil losses for 1-butanol at 20 oC Figure 5.6: Effect of solvent: oil ratio on the extraction measured by 123 the percent of oil losses for 1-butanol at 30 oC Figure 5.7: Effect of solvent: oil ratio on the extraction measured by 124 the percent of oil losses for 1-butanol at 50 oC Figure 5.8: Effect of solvent: oil ratio on the extraction measured
by the percent of oil losses for 1-butanol at 20, 30 and 50 oC 124 Figure 5.9: Effect of solvent: oil ratio on the extraction measured 125 by the percent of sludge removal for 1-butanol at 20 oC Figure 5.10:Effect of solvent: oil ratio on the extraction measured 125
by the percent of sludge removal for 1-butanol at 30 oC Figure 5.11:Effect of solvent: oil ratio on the extraction measured 126
by the percent of sludge removal for 1-butanol at 50 oC Figure: 5.12 Effect of solvent: oil ratio on the extraction measured by the 126 percent of sludge removal for 1-butanol at 20,30 and 50 oC Figure 5.13: Effect of solvent: oil ratio on the extraction measured 128
by the percent of oil losses for 2-propanol at 20 oC Figure 5.14: Effect of solvent: oil ratio on the extraction measured 128
by the percent of oil losses for 2-propanol at 30 oC Figure 5.15: Effect of solvent: oil ratio on the extraction measured 129
by the percent of oil losses for 2-propanol at 50 oC Figure 5.16: Effect of solvent: oil ratio on the extraction measured by the 129 percent of oil lossess for 2-propanol at 20,30 and 50 oC
xiv
Figure 5.17: Effect of solvent: oil ratio on the extraction measured 130 by the percent of sludge removal for 2-Propanol at 20 0C Figure 5.18: Effect of solvent: oil ratio on the extraction measured 130 by the percent of sludge removal for 2-Propanol at 30 0C Figure 5.19: Effect of solvent: oil ratio on the extraction measured 131 by the percent of sludge removal for 2-Propanol at 50 0C Figure 5.20: Effect of solvent: oil ratio on the extraction measured by the 131 percent of sludge removal for 2-Propanolat 20, 30 and 50 oC Figure 5.21: Effect of solvent: oil ratio on the extraction measured by 132 the percent of oil losses for MEK at 20 oC Figure 5.22: Effect of solvent: oil ratio on the extraction measured by 133 the percent of oil losses for MEK at 30 oC Figure 5.23: Effect of solvent: oil ratio on the extraction measured by 133 the percent of oil losses for MEK at 50 oC Figure 5.24: Effect of solvent: oil ratio on the extraction measured by the 134 percent of oil losses for MEK at 20, 30 and 50 oC Figure 5.25: Effect of solvent: oil ratio on the extraction measured by 134 the percent of sludge removal for MEK at 20 oC Figure 5.26: Effect of solvent: oil ratio on the extraction measured by 135 the percent of sludge removal for MEK at 30 oC Figure 5.27: Effect of solvent: oil ratio on the extraction measured by 135 the percent of sludge removal for MEK at 50 oC Figure 5.28:Effect of solvent: oil ratio on the extraction measured by the 136 percent of sludge removal for MEK at 20, 30 and 50 oC Figure 5.29: Effect of solvent: oil ratio on the extraction measured by the 138
percent of oil losses for 1-Butanol, 2-Propanol and MEK at 20 oC Figure 5.30: Effect of solvent: oil ratio on the extraction measured by the 138
percent of oil losses for 1-Butanol, 2-Propanol and MEK at 30 0C Figure 5.31: Effect of solvent: oil ratio on the extraction measured by the 139 percent of oil losses for 1-Butanol, 2-Propanol and MEK at 50 oC Figure 5.32: Effect of solvent: oil ratio on the extraction measured by the 139 percent of sludge removal for 1-Butanol, 2-Propanol and
MEK at 20 oC150 Figure5.33: Effect of solvent: oil ratio on the extraction measured by the 140
percent of sludge removal for 1-Butanol, 2-Propanol and MEK at 30 oC
Figure 5.34: Effect of solvent: oil ratio on the extraction measured by the 140 percent of sludge removal for 1-Butanol, 2-Propanol and MEK at 30 oC
Figure 5.35: Percent of oil losses (POL) v/s KOH 142 Figure 5.36: Percent of sludge removal 142 Figure 5.37: Used oil sedimentation 143 Figure 5.38: Percent of sludge removal 147 Figure 5.39: Percent oil losses 147 Figure 5.40: Percent sludge removal 148 Figure 5.41: Percent of oil Losses 149 Figure 5.42: Used Oil Sedimentation 149 Figure 5.43: Used Oil Sedimentation 150
xv
ABSTRACT Automotive lubricating oils play a most vital role in our great complex civilization.
To estimate the importance of its role one need only consider that every moving part
of every machine is subjected to friction and wear. Friction consumes energy; wear
causes changes in dimensions and eventual breakdown of the machine. To overcome
this problem, lubricating oil is used to reduce friction, protect against wear, carry
away heat, protect against rust and remove contaminants from the engine. This
lubricating oil is made from crude oil after refining by introducing proper additives
and its sources and reserves are limited and are not inexhaustible throughout the
world.
The used oil loses its effectiveness during operation due to the presence of
contaminants. This oil is less subject to biodegradation and does not evaporate but
becomes contaminated with substances that are hazardous to human health and the
nvironment, so before it can discharged to the environment this oil requires suitable
collection and treatment. Therefore to avoid adverse impacts, proper management of
waste oil is needed.
In this study, waste oil disposal practice in Pakistan has been identified as has the
adverse environmental impact associated with it and waste oil management options
are discussed in relation to proposed re-cycling options considering the prevailing
market price of the new virgin oil. 12 re-generation locations have been identified all
over Pakistan to create job opportunities for local people and also reduce transport
costs.
This study was carried out to evaluate the performance of different methods used to
upgrade the waste lube oil into a usable product. Acid/ clay treatment was conducted
at laboratory and small pilot scale using the sulfuric acid with different catalysts
(Dimethyl Sulfoxide, Dimethyl Formamide and Zeolite) and waste oil ratios. The
performance was evaluated against the properties of regenerated oil to the standard
base oil, 500N and 150N, and it was found that regenerated oil does not match to
standard base oil.
xvi
In the solvent-extraction process, the performance was evaluated using single and
composite solvents with catalysts at laboratory and pilot scale level. The two
dependent variables, namely the Percentage of oil loss (POL) and Percentage of
Sludge Removal (PSR) were examined as the key parameters in assessing the
performance of the extraction process. The solvents used were (70% of 2-propanol
and 30% of n-hexane) with addition of KOH, composite solvents (40% 2-propanol,
35% 1-butanol and 25% butanone) and (25% 2-propanol, 37% 1-butanol and 38%
butanone) at different solvent-oil ratio and operating variables.
In view of the practically and commercial aspect of the project, the used oil recycling
process was consecutively run for three or four times at each composition. The
physical properties of recovered/re-generated base oil were analyzed and compared.
The results from the experimental work shows the laboratory and pilot scale operation
revealed similar trends with a little higher performance from the pilot scale operation.
This is due to the mechanical mixing of acid-oil/ solvent-oil, coagulants, activated
earth clay and controlled heating (dehydration & distillation) extraction of light
hydrocarbons and solvents.
The properties of re-generated oil were matched to the standard base oil, 500N and
150N, the properties of solvent–oil ratio (25% 2-propanol, 37% Butanol and 38%
Butanone) at SOR 6:1 was observed to be the most appropriate solvent composition
and achieved about 68% oil recovery and the oil properties compared favorably to
graded virgin oil and can be used for similar purposes. Since the quality of
regenerated oil matched the virgin oil, it would reduce our dependency on imported
oil, save foreign exchange, reduce adverse environment impact and help to preserve
oil sources.
xvii
CHAPTER 1
INTRODUCTION
1.1 INTRODUCTION
Used automotive oil is generated from the transport sector when oil loses its effectiveness
during operation because contamination from the combustion chamber, metallic particles
together with water, varnish and gums result in the wear and tear of the engine parts.
Asphaltic compounds additives, light hydrocarbons, resinous material, mono and
polyaromatic compounds, carbon black and used base oil made it toxic chemicals mix
(Klaman,1983), in urban areas at filling stations and motor repair shops.
Used oil creates environmental pollution if not disposed properly; there is a possibility
that substances that it may contain enter natural cycles through the food chain via water,
soil and air. In this way, used oil pose risk to human health and impedes the growth of
plants and their ability to take up water as sometimes used oil contained hydrocarbons,
heavy metals, polyclorinated biphnyls (PCBs) and other halogenated compounds (El-
Fadel and Khouy (2001), detergents and lubrication additives. Used lubricating oil must
be disposed off properly, if burnt as a low grade fuel, harmful metals and other pollutants
may be released into air (Blundell, 1998). In 1995 it was estimated that less than 45% of
used oil was collected worldwide and the remaining 55% was either misused
(Environmental Oil Ltd. 2000) or improperly disposed by the end user severely
increasing the problem of waste discharged into the environment (Leask, 1998).
This hazardous waste oil needs proper management to maximize the amount of used oil
recovered by recycling and to minimize the quality of oil being improperly disposed off
and to reduce the waste oils environmental pollution (Dang, 2006). To convert harmful
wastes into harmless substances, it is necessary to increase the collection and re-
processing of the oils. In the case of re-refining used oil, 2.5 quarts of lube oil can be
produced from one gallon of used motor oil; the same may be obtained from refining 42
1
gallons (one barrel) of crude oil. One gallon of used oil processed for fuel contains about
140,000 BTUs (Holmes et al, 1993).
In Pakistan, until now, no used oil management systems are available and the level of
public awareness is very low in respect of environmental impacts. According to recent
studies about 274,000 tones of used oil generated each year from vehicles, is being
improperly disposed in Pakistan (Durrani et al, 2008).
In this modern age, the purification of used oil into parent base oil is a suitable way for
energy conservation and to avoid pollution. Used oil re-refining takes 50-85% less energy
to produce the same volume than by refining virgin crude (API,1997). Automotive
lubricants are generally considered to be of higher quality than industrial oils for
recycling to base lube oil. It is an important resource and a valuable petroleum base
product. The high price of crude oil and the objective of saving valuable foreign
exchange have resulted in efforts to regenerate used lube oil into clean lubricants.
1.2 GENERAL TREATMENT METHODS
Commonly used oil treatments include primarily re-processing, reclamation and
regeneration. The insoluble contaminants and oxidation products can be removed by
heating, settling, filtering, dehydrating or centrifuging to separate solids and water from
the used oils which is then used as fuel. Where the re-generation is a process to produce
base oil, pre-distillation, treatment with acid, solvent extraction, contact with activated
clay and hydro-treating is required (known as re-generation). It results in the recovery of
base oil with maximum commercial value. Waste-oil management thus provides a
suitable way of promoting energy conservation and environmental sustainability by
treatment and reuse of oils. Production of re-refined base lube also uses a combination of
physical, chemical, thermal and distillation processes, with the addition of hydro treating,
to separate water and suspended solids and other contaminants from the used oil so that
the product can be used interchangeably with virgin lube oil in lube oil applications. Re-
refined base lube is considered to be closed-loop recycled. So far the following major
regeneration methods have been in common use:
2
• Acid /clay treatment
• Vacuum distillation / clay treatment
• Vacuum distillation / catalytic hydro treatment
• Solvent extraction and clay treatment
The acid clay recycling process uses sulfuric acid of high concentration to remove the
asphaltenic materials. It is the most popular conventional method is acid /clay treatment.
However, this method creates another environmental problem due to the production of
acidic sludge. The replacement of sulphuric acid consumption with hydrogenation
process to re-refine the base oil somehow creates another problem when it requires high
temperature to operate optimally. Implementation of high temperature, however,
destructs the base oil molecular structure, which can only remain stable until 320 oC.
The introduction of the solvent extraction method eliminates the usage of high
temperature or hydrogenation process in re-refining the used lubricant oil into base oil.
This new method retains the structure of the base oil throughout the process.
Theoretically, the presence of polar solvent segregates the particles from liquid phase,
while slightly non- polar solvent stabilizes the polymeric molecules (e.g. polyolefin) and
other additives. The stable dispersion, which occurs in the presence of these two
extracting solvent, is destabilized in the presence of flocculating agent. It is then removed
in the form of sludge and may be used as a raw material in the ink industry. The best
performance of solvent extraction method is high sludge removal and minimum oil loss.
In this research, used lubricant oil is treated under both processes i.e. acid/clay treatment
and solvent extraction treatment. Oil that to undergoes the treatments called the treated
oil where the impurities were physically removed from the base oil, but the oil
appearance, which was affected by its chemical properties, can be improved by polishing
process or adsorption to remove the color and the odor for acceptance requirement.
3
This research focused on the solvent–extraction and solvent-recovery process, on
laboratory and pilot scales study. The initial stage of this study on the laboratory scale
experimental work produce the basis in up-scaling the re-refining of used lubricant oil. At
laboratory scale, the parameters of interest the potassium hydroxide (KOH) addition and
the solvent oil ratio (SOR) percentage of sludge removal (PSR), percentage of oil loss
(POL) and physical properties of the treated oil, the measurements of the effectiveness of
solvent- extraction process (Nimir et al, 1997). During solvent – recovery process,
solvents are separated from the oil, where the mixture is introduced into vacuum
distillation column.
Laboratory scale data are used as a basic pile in up-scaling into pilot plant scale
operation. Pilot scale operated under atmospheric pressure in batch process. The rig is
designed for two liter liquid capacity operated at a time, constructed with stainless steel
material. Instead of rotary evaporator, the oil solvent mixture is subjected to the solvent-
recovery system comprising the vertical jacketed heater, cyclone separator and
condenser. The effectiveness of pilot scale solvent-extraction and solvent-recovery
processes was carried out similarly to the laboratory scale operations. 1.3 JUSTIFICATION
• Waste lubricating oil constitutes a serious pollution problem. It may contaminate
water and soil if discharged into the environment.
• It causes air pollution if burnt as a low- grade fuel. • Used oil doesn’t wear out it just gets dirty.
• Waste oil can be a very valuable resource, if managed properly. It has very refined
fractions of petroleum and its recovery possibilities are extremely high.
• Average crude oils have 3-8% base oil, whereas lube crude oil have 12-16% base oil.
This compares with 65-75% recoverable base oil content in used automotive oils.
• If burnt or dumped would mean the loss of a valuable natural resource.
4
1.4 AIMS AND OBJECTIVES
Following are the aims and objectives of the project:
• To quantify the used motor oil generated in Pakistan each year and propose its
safe, efficient and economical collection and transportation.
• To optimize the performance of the existing processes or to develop new ones
• To make the waste oil useful for automobiles as valued product.
1.5 RESEARCH SCOPE
The use of waste oils after treatment can be highly energy contented, clean burning fuel
or a lube base stock comparable to highly refined virgin oil. The regeneration of used oils
is widely practiced to obtain a highly degree of contaminant removal leading to the
recovery of the oil fraction which has the maximum viable commercial value.
1.6 STRUCTURE OF THE THESIS
In this chapter, the discussion is focused on the background of the research as well as the
objective of the study and the research scope. This chapter is followed by a literature
review associated to the topic of interest, including the mechanisms involved during the
process, such as extraction, sedimentation and consolidation. Chapter three discusses the
present waste oil management system in Pakistan and proposes the suitable one. Chapter
four discusses experimental work, methodology and approach used for quantifying used
oil, its collection and transportation system and re-generation location, this chapter also
contains the experimental work on laboratory scale for both processes (acid clay and
solvent extraction), development of experimental rig and conducts experimental work
and also physical properties of the re-refined used oil. In the last used oil environmental
impact has been discussed. The results are then discussed in chapter five, comprising the
used oil quantification, collection, transportation and re-generation. Laboratory scale
study on the acid clay treatment and solvent-extraction process as well as the physical
properties of the oil and pilot scale study on similar topics. Finally, the thesis is
completed with conclusions and recommendations of this research in chapter six.
5
CHAPTER 2
LITERATURE REVIEW
2.1 GENERAL OVERVIEW
The main functions of lubricating oil include reducing friction, carrying away heat,
protecting against rust, wear and removing contaminants from the engine. The oil is used
to ensure the smooth performance and prolong the good condition of the vehicles and
machines. In order to maintain the engines in good condition, it is necessary that the
engine oil must be replaced by new oil after a certain period of service. This is because of
the changes occurred in its physical and chemical properties, such that it cannot perform
as its original performance and once replaced by new lubricants becomes a significant
management challenge. It requires proper collection and treatment before it can be
discharged into the environment, for that proper waste oil management is necessary
hence to prevent its adverse impacts.
2.2 LUBRICATING OIL
Lubricant oils are used to reduce friction and wear by interposing a film of martial
between rubbing to reduce friction and wear. The engine depends greatly on the condition
of lubricant oils. Lubricating oil, or lubricant oil, is obtained either by re-refining
distillate or as residual frictions directly from crude oil. Modern lubricating oil is made of
base stock or base oil (71.5-96.2 wt %), blended with few parts per million (ppm) of
chemical additives as per its grade and specific duty. The additives are added to fulfill the
specific requirement for lubrication.
Lim (2000) has described the roles of additives; mentioned three major roles of additives
were to impart new, useful and specific properties to lubricant oil, to enhance present
properties, and to reduce the rate of undesirable change that takes place during its service
6
life. Each lubricant oils consisted at least one type of additives, or nearly 30 percent of
weight of additives. A typical composition of lubricating oil is shown in Table 2.1.
Table 2.1: Typical composition of lubricating oil
Ingredients Weight %
Society of Automobile Engineers
(SAE) 30 or base oil stock
71.5-96.2
2.0-10.0
1.0-9.0
0.5-3.0
0.1-2.0
0.1-3.0
0.1-1.5
Metallic detergent
Ashless dispersant
Oxidation inhibitor
Antioxidant/antiwear
Friction modifier
Pour point depressant
Antifoaming agent 2-15 ppm
Source (Gergel,1992)
Lubricating oil is blended with Additives up to 3.8-28.5% by weight. Metallic detergent
is added at 2.-10. % to neutralize the deposits formation from combustion of high sulfur
fuel or acidic combustion material, which also help to prevent the deposition of lacquered
resulting from oxidation. An example of metallic detergent that usually added is
magnesium sulfonates. Dispersant (1.-9. %), is blended with base stock to disperse or
suspend sludge formation during usage, such as polymeric succinimides and polyester.
Zinc dithiophosphate is introduced into the base oil as 0.5- 3.0% of weight as the
oxidation inhibitor, where it helped the base oil to form a film layer to prevent acid from
reaching the metal surfaces (Gergel, 1992). Easters or acids (0.1-2.0 %) perform as the
antiwear to reduce the effect of wear and friction. Friction modifier and antifoaming
agent are added at 0.1-3.0% and 2-15 ppm, respectively. Antifoam collapses the small
bubbles into big bubbles, which tend to rise and collapse at the surface. Pour point
depressant (e.g. methacrylates polymers) is mixed into the oil as 0.1-1.5%. It helps to
inhabit the formation of wax crystal structure, which prevents the oil flow, during usage
at low temperature. The summery of additive’s functions is listed in Table 2.2
7
Table 2.2: Types and function of lubricating oil additives
Type Function Example Detergent Neutralise the deposits formation
from combustion of high sulfur
fuel or acidic combustion
material, helps to prevent the
deposition of lacquer resulting
from oxidation
Metallo-orgnic compounds,
calcium, magnesium sulphonates
Dispersant Disperses or suspends any
potential sludge forming material
in oil
Ash less dispersants and
polymeric succinimides
Viscosity index
improver
Increases the relative viscosity of
an oil at high temperature
Methacrylates polymers and
acrylates polymers
Oxidation
inhibitor
Forms protective film on metal to
prevent acid from reaching its
surface
Zinc dithiophosphate
Rust inhibitor Forms tenacious film by high
polar attraction towards the metal
surface
Neutral material; ethioxylated
alkyl phenils
Antifoam Attachs to air bubbles in foam,
which coalesce into larger bubbles
and rise to the foam surface and
collapse
Silicon type chemicals;
polymethyl siloxanes
Pour point
depressant
Inhibits formation of wax crystal
structure that prevent oil flow at
low temperature
Alkylaromatic polymers,
methacrylates polymers
Antiwear Reduces friction, wear scuffing/
scoring under boundary
lubrication conditions
Esters, acids
Source (Gergel 1992).
8
2.3 BASE OIL
The lubricant base oil is a complex mixture of hydrocarbons (80 to 90%) used together
with performance-enhancing additives to make crankcase oil as engine oils in particular
required high quality base oils in order to meet tight volatility specifications. Usually,
there are three types of base oil; mineral oils, modified mineral oils and synthetic oils.
Mineral oil is a selected fraction of crude oil with some components remained in order to
improve the oil performance. Virtually, the molecules in the mineral oil are the similar
molecules in the crude oil. Base oil from modified mineral oil, is made from the selected
fraction of the refining process that has gone through several treatments carrying some of
the molecules to arrange, such as hydro-cracked or hydro-treated base oil. It possessed
most of the molecules that present in the original crude oil. Lastly, synthetic base oil,
which is synthesized by chemical reaction of limited number of well-define components.
The main purpose is to meet targeted performance, such as exceptional low temperature
behavior. This is obtained by the nature of synthetic molecules or the absence of
unwanted components that usually exist in mineral oils. However, it has low anti-
oxidancy capability due to the absence of sulfur and nitrogen contents, which are
naturally present in mineral oils. Moreover, the price of synthetic base oils is higher
compare to conventional lube oil due to the complex process of manufacturing and pure
chemicals of raw material as opposed to refined oil (Petronas, 1999).
There are two types of mineral base oil; paraffinics and napthenics. Paraffinics base oil is
high in alkanes with high amount of straight chain saturated hydrocarbons, has high
viscosity index, and sufficient low temperature properties. Though, it requires an
aromatic removal and dewaxing during production process. Meanwhile, napthenics
contain high proportion of closed- ring methylene groups (Petronas, 1999), wax- free or
little- wax content, has low pour points, and more limited range in crude oil as compared
to paraffinics.
Generally, base oil is produced by simple distillation of petroleum crude oil. The quality
of the base oil can get better by the additional simple processing such as acid treatment or
9
filtration method, to remove less desirable component (e.g. wax, aromatics and asphalt).
Though, in modern refinery, the base oil was manufactured in great quantities with
interrelationship between other process streams (Weinstein, 1974). Solvent extraction is
then used in modern refinery to replace acid treatment method due to environmental
consideration, with the main purpose of improving the oil’s oxidation stability, viscosity
index and additives response. Base oil composition is identified by polar, aromatics and
saturated components. Basically, these components maintain the same amount before and
after the re-refining processes. According to (lim, 2000), the small reduction of polar
compound is due to the removal of contaminants, impurities and macromolecules using
membrane filtration method and the de-stabilization of colloidal repulsion in the solvent
solution. 2.4 USED OIL
Used oil as an oil un-suitable for its original purpose due to the presence of contaminants
or impurities, or the loss of original properties due to physical contaminants and chemical
reactions occurring during its use, the used oil either may be from industries or non-
industrial sources (Lim, 2000).
Used lubricant oil as used product of any semi solid liquid, consists of completely or
partially mineral oil or synthesized hydrocarbons (synthetic oil), loses its effectiveness
during operation due to the presence of certain contaminants from air, fuel combustion,
oxidation and additives (Mortier et al, 1992).
Mortier et al. (1992) pointed out that generally, used lubricant oil comes from two major
sources.
i) Industrial used lubricant oil (e.g. metal working oil, hydraulic lube oil, turbine and
circulating lube oil) which is easy to recycle and can be re-produced as lubricant
oil without sophisticated treatment to get the standard requirement.
10
ii) Engine oil, hydraulics and gear oil contributed to the mount of automotive used
lubricant oil, which needs specific treatment to produce re-refined base oil.
USEPA (1988) regulatory described used oil as any oil that has been refined from crude
oil or any synthetic oil that has been used as a result of such use is contaminated by
physically or chemically impurities the definition of used oil is given in Table 2.3.
Table 2.3: Used oil by USEPA’S definition
Used oil is Used oil is not
• Synthetic oil- usually derived from coal,
shale or polymer- base starting material
• Engine oil- typically includes gasoline and
diesel engine crankcase oils and piston-
engine oils for automobiles and heavy
equipments.
• Transmission fluid
• Refrigeration oil
• Compressor oils
• Metal working fluids and oils
• Laminating oils
• Industrial hydraulic fluids
• Copper and aluminum drawing solution
• Electrical insulating oil
• Industrial process oils
• Oils used as buoyants
• Waste oil that is bottom clean- out
waste from virgin fuel storage
tanks, virgin fuel oil spill cleanups,
or other oil that have not actually
been used
• Products such as kerosene and
antifreeze
• Vegetable and animal oil, even
when used as a lubricant
• Petroleum distillates used as
solvents
Source (USEPA 1988)
11
2.5 PROPERTIES AND CHARACTERISTICS OF USED LUBRICANT OIL
Colour and odor problem comes from the nitrogen and oxygen, which are produced by
the reaction of engine combustion gases with lubricating oils. Beside these impurities,
used oil also consists of unchanged base oil molecules that one intends to recover. Thus,
some treatment is essential to recover the base oil that can be used repeatedly (lim, 2000).
Used oil by its physical and chemical properties comprises viscosity, flash point, density,
specific gravity water content, ash content, and carbon residue, where as the chemical
properties of used oil are color and odour, metal content, total acid and base numbers,
saponification number, as well as the sulfur and nitrogen content (Gray,1999).
Comparison of virgin and used oil lubricating properties is given in Table 2.4.
The presence of contaminants or impurities is pointed by the difference in the values that
occur between the initial (virgin oil) values of these properties. In above Table 2.4, the
modification of specific gravity from its early condition at 0.882 to 0.910 determines the
existence of contaminants or impurities, which is also indicated by the increasing value of
water content from 0-12.3 wt%. This also shows by the increasing value of the carbon
residue (0.82 wt %) and ash content (0.94 wt %) to 3 wt% and 1.3wt%, respectively.
Metal contents (e.g. magnesium, barium, zinc, calcium and lead) are also increased;
resulting from the contaminants of wear metal and rust. Used oil is normally acidic in
nature, which indicates by the high value of total acid number.
Altering in physical and chemical properties of used oil indicates that it consists of
several possible contaminants including some chemicals and residual components of
gasoline where as water is product of the combustion of by products and rain (Mortier et
al; 1992) has described that
USEPA (1988) has mentioned that some solid contaminated the oil via the unchanged
additives (e.g. polyisobutylene and polymethacrylate), wear metal, rust and dirt.
12
Table 2.4: Comparison of virgin and used oil lubricating properties
(Gray, 1999)
Properties Virgin lube oil Used lube oil
Physical properties
Specific gravity
Dynamic viscosity SUS @ 1000C
Water , volume %
Carbon residue, wt %
Ash content, wt %
Flash point, 0F
Pour point, 0F
0.882
----
0
0.82
0.94
----
-35
0.910
324
12.3
3.00
1.30
348
-35
Chemical properties
Saponification number
Total acid number
Total base number
Nitrogen, wt %
Sulfur, wt %
Lead, ppm
Calcuim, ppm
Zinc, ppm
Phosphorous, ppm
Magnesium, ppm
Barium, ppm
Iron, ppm
Sodium, ppm
3.94
2.2
4.7
0.05
0.32
0
1210
1664
1397
675
37
3
4
12.7
4.4
1.7
0.08
0.42
7535
4468
1097
931
309
297
205
118
13
2.5.1 Contaminants
ECOFUEL Ltd (2000) reported that lubricating oils are impaired temporarily only
because of accumulation, during use, of contaminants coming from extraneous impurities
and products of oil deterioration, given the used oil contamination and their composition
shown in Tables 2.5 and 2.6.
Table 2.5: Contaminants in used lube
Source (ECOFUL Ltd 2000)
Extraneous Products of Deterioration
Surrounding impurities (dust, dirt and
moisture)
Sludge Pp deterioration
Metallic particles (wear and rust) Lacquers
Unburnt fuel (crankcase dilution) gasoline,
diesel
Oil soluble products
Fuel additives Oil insoluble produces
Untreated Acid, Carboneous particles,
Polycyclic aromatic hydrocarbons (PAHs)
Sludge and emissions
Table 2.6: Composition of used oil contaminants
Source (ECOFUL Ltd 2000)
Water content, wt %
3 – 5
Gasoline or diesel, wt % 2 – 3
2-3
Oil insoluble products, wt% 5 – 15
Metal content, ppm Ba 312 Pb 121 Na 26 Ca 2135 Fe 648 Si 42 Zn 1994 Mg 61 Cu 26
14
Noln et al. (1990) described that in larval phases of aquatic organisms that is open to
toxic substances contained in used oil that can build up plankton and other tiny organisms
due to the food chain and finally reach human beings as contaminants elevate the food
chain, consumed used-oil-contaminated water range from mild symptoms of increasing
the toxic compounds in the liver to complete impairment of body functions and in the end
death. When applied the waste lubricating oil to soil, degrades significant contamination
of the surrounding soil and groundwater. This degradation is because of bacteria and
fungi which can degrade the components of used lubricating oil.
Mueller Associates (1987) pointed out that one pint of used oil can create an acre-sized
slick on water; as little as 35 parts per million will appear as a thin film. When dumped
into water, used oil increases the high biological oxygen demand as its hydrocarbons
decompose. This removes oxygen that is necessary for healthy animal and plant life.
Brown et al. (1985) and Wakeham and Carpenter (1976) described that hydrocarbons,
such as well branched alkanes and PAHs with three or more rings, are moved in soil
runoff to surface water and inhabit out of the water column into the residue where they
may keep on for many years.
Contaminants that make used oil management more problematic are heavy metals and
chemical additives. When leaded gasoline was the predominant vehicle fuel, lead was
present at high levels in used oil because of piston blow-by. Other heavy metals
commonly present in used oil include cadmium, chromium, arsenic and zinc These may
arise from wear on the metal engine parts or from their inclusion in oil additives
(Franklin Associates,1985).
Low molecular weight PAHs and volatile compounds, such as the mono-aromatics and
various halogenated alkyl substances, comprise the largest fraction of WCOs lost by
volatilization (Metzler and Jarvis, 1985) and (Stephens et al., 1981)
Oil applied to road surfaces was lost by volatilization in the initial 15- to 30-day period
following application (Surprenant et al, 1983).
15
Baranowski (1982) reported that most common impurity in used oil is water which may
result from leaky engine seals, condensation or coolant contamination.
Brinkman, and Dennis, (1982) reported that as the EPA has gradually reduced the lead
content in gasoline, the presence of lead in used oil has decreased correspondingly, from
an average of 21,000 ppm to 500 ppm.
Canil et al. (1982) have described that dirt in the oil can result from worn seals, abrasion
and erosion in the engine and adhesive wear. These two impurities are readily separable
from the oil. Simple heating drives off the water, while mechanical filtration removes dirt
particles.
Mackenzie and Hunter (1979) reported that diaromatics are lost through natural
weathering at once when waste crankcase oil becomes adsorbed to particulate matter.
Freestone (1979), Hunter et al. (1979) and MacKenzie and Hunter (1979) described that
the sediments deposited in water in case, when particulates are washed to sewers by
storm, especially when treatment facility is bypassed combined sewers are used.
Hunter et al. (1979) reported that when applied the waste crankcase lubricating oil to
rural roads for dust suppression can be transported to the air, water, and soil by several
ways: capillary action, volatilization, runoff, adhesion to dust particles, or adhesion to
passing vehicles in the aqueous phase, metals such as copper, cadmium and zinc are in
dissolved form, although the majority hydrocarbons are associated with particulate
matter.
Neal et al. (1977) reported that when applied the waste lubricating oil to soil, degrades
significant contamination of the surrounding soil and groundwater. This degradation is
because of bacteria and fungi which can degrade the components of used lubricating oil.
16
Moore and Dwyer (1974) expressed that used crankcase oil can change marine organisms
in numerous unlike manners. These changes are categorized as deadly and dangerous
toxicity by contact, physical coating by the oil, the absorption of the oil into tissues, and
habitat changes.
Freestone (1972) reported that when applied the waste crankcase lubricating oil to rural
roads for dust suppression can be transported to the air, water, and soil by several ways:
capillary action, volatilization, runoff, adhesion to dust particles, or adhesion to passing
vehicles in the aqueous phase, metals such as copper, cadmium and zinc are in dissolved
form, although the majority hydrocarbons are associated with particulate matter
Freestone (1972) observed that oil applied to road surfaces was lost by volatilization in
the initial 15- to 30-day period following application.
2.6 QUANTIFYING USED OIL
There are many options for managing used oil once it is drained from vehicles. The U. S.
Environmental Protection Agency (EPA) has designated used oil as a significant solid
waste management problem (Guideline for Federal Procurement, 1988). This designation
reflects the potential amounts of used oil generated and the contaminating characteristics
of oil in the environment.
The volume of used oil produced from one automobile may seem insignificants perhaps a
gallon generated every three or four months. This is a small volume of waste compared
with the daily volumes of household solid waste, but when these volumes are multiplied
by the millions of automobiles and other vehicles in use, the total quantity annually
exceeds to billion gallons per year. The liquid nature of this potential waste and the lack
of coordinated education, collection and transportation programs cause used oil to be
both a local as well as a international concern.
Ssempebwa et al. (2008) worked in case study of Kampla district of Uganda on the use,
disposal and regeneration of waste oil, found that approximately 3252 garages and 156
17
fuel stations that produced 22,000 liters and 14,000 liters per week. He mentioned the
detail disposal of used oil generated. In case of garages, about 35% used oil sold and
about 16% poured on the ground, where as 18% taken by vehicle owners and around 31%
given away for free. Similarly at fuel stations around 27% sold 49% picked by private
collectors and 4% poured on the ground, 6%given away for free 2% burnt, 13% taken by
vehicle owner.
The data collected for vehicle used oil generation quantity in Pakistan based on the
average distance covered 3000 km, generated about 100,000 tones. Conducted survey,
prepared questionnaires, interviewed all actors involved in the field of vehicle waste oil
(Durrani. et al, 2008).
Used oil generated in Lebanon using vehicle registration data, generated amounts was
about 18000 tons/year (EL-Fadel and Khouy, 2001).
Milner et al. (2000) invented an apparatus for receiving, transporting, and dispersing a
viscous product from one storage tank to another. The assembly includes a housing
container, comprising a reusable fill bag and a sealable container secured within the
housing container.
Arnaout (1997) covered around 80 petrol stations and garages, workshops in limited field
survey, revealed that do-it-yourself oil changes are not a practiced technique in Lebanon,
and about 90% of oil changes occur either in gas stations or in automotive garages and
military installations.
Dar Al-Handasah (1995) described on the basis data collected and averaged that a vehicle
changes the oil 4 liters of every 4000 km and travels about 17000 km/year.
Used motor oil generated in Michigan each year. Used Delphi Technique method
determined that Michigan generated 26.5 million gallons of used motor oil. This number
is based on detailed analysis of motor vehicle registrations, mileage driven and oil change
18
frequencies and crankcase capacities are known, the amount of used oil produced by each
vehicle class can be calculated (Kakela, et al.; 1997).
Stoneman and Julie (1989) reported that about 500 million gallons of waste motor oil are
drained from crankcases each year in the United States of America and half of all vehicle
owners change their own oil. This used oil is diffused each of the hundreds of millions of
U.S. tones, suggested that this used oil must be managed in some way.
Survey (1989) revealed that an industrial tractor-trailer may drain up to 60 quarts per oil
change, which is 12 times the amount drained from a pickup.
Schmitz (1989) quantified the used oil using vehicle registration data and grouped the
vehicles according to the relative sizes of their engines and, consequently, their crankcase
capacities but reported in case of farm tractors are not required to be registered with the
state unless they travel on public roads. Amount of used oil drained by this category
considered on hourly based.
2.7 WASTE OIL MANAGEMENT
The USEPA has designated used oil as a significant solid waste management. This
designation reflects the potential amounts of used oil generated and the contaminating
characteristics of oil in the environment.
Lubricating oil may be used over and over again if it is relieved of its impurities. It
retains its lubricating properties throughout the heat and stress of engine operation. Used
oil will vary greatly in the level and types of external and internal contamination it
acquires. Some oils will contain only excess water and dirt, while others will contain
compounds that require specialized techniques to separate them from the oil (Sherman et
al, 2001).
Contaminants that make used oil management more problematic are heavy metals and
chemical additives. When leaded gasoline was the predominant vehicle fuel, lead was
19
present at high levels in used oil because of piston blow-by. As the EPA has gradually
reduced the lead content in gasoline, other heavy metals commonly present in used oil
include cadmium, chromium, arsenic and zinc, these may arise from wear on the metal
engine parts or from their inclusion in oil additives that assure good oil flow, prevent
reactions between the oil and engine parts and avoid oil breakdown at high temperatures.
However, as the additives undergo use and stress, they may produce hazardous chemicals
such as xylenes, toluene and benzene (Mortier et al, 1992).
The options for used oil disposition fall into three general categories: treatment as a
waste, limited reuse and treatment as a resource. Treating used oil as a waste should be
discouraged because of its environmental impacts as one pint of oil can make slick on an
acre-sized water; as little as 35 parts per million will appear as a thin film. When dumped
into water used oil increases the high biological oxygen demand as its hydrocarbons
decompose. This removes oxygen that is necessary for healthy animal and plant life. The
additives or contaminants in used oil can also pollute water and soil. If oil is disposed off
as a waste, it eliminates the possibility of reuse and, therefore, increases the requirement
for new lubricating oil to be refined from crude oil to meet lubrication needs.
Reprocessing is a physical process that aims to remove the large particles and water from
used oil so that it can be easily burned, this is a limited reuse of oil includes reprocessing
for eventual burning as a fuel. One technique for reprocessing is simply settling. This
takes time but requires no machinery or energy input. More sophisticated techniques can
speed up the process. These include centrifugation, mechanical filtration, vacuum
filtration and absorption. Some separation of the lighter and heavier hydrocarbons may
occur during the physical processing, but all products can be used as different grades of
fuel oil.
Although both reprocessing and then burning used oil produces energy and saves some
energy over burning fuels made from crude, it is still an environmentally less suitable
method of managing oil than re-refining. Burning destroys a high-quality base stock that
has a significant energy investment in its production. Burning also has the potential to
20
produce hazardous air pollutants such as metals and oxides from the burning of
impurities.
Treating used oil as a resource implies that it will become a raw material for a new
product. The only process that manages used oil in this way is re-refining to create new
lubricating oils. Re-refining is a chemical process that employs techniques from the crude
oil refining industry to clean and separate the components of used oil. Resulting products
include light hydrocarbons that may be used as fuel, base lubricating oil, and a heavy end
product that is often incorporated as an asphalt extender. Some waste is also produced.
The amount and degree of hazardousness of the waste depend on the re-refining process.
2.7.1 Management options
Al-Omari (2008) experimentally investigated the viability of using used lubrication oil, as
an energy source. The used oil co-fired with LPG as a dual fuel and performed in
combustion laboratory unit manufactured by P.A. HILTON LTD. The study concludes
that co-firing even a small amount of used oil with gaseous fuels such as LPG the
radiation form the gaseous fuels flames gets enhanced significantly, so used oil is a very
significant energy source and represents an energy management opportunity with great
potential.
Durrani et al. (2008) used survey instruments obtained primary data through the
questionnaires from the main actors involved in the used oil markets in Pakistan, and
assessed that 5% disposed in land fill, 10% in sewers, 25% sub-standard re-refining and
grease making and 60% burnt (Sugar mills, cement factories, furnaces and low pressure
boilers and low pressure boilers, etc) in private sectors.
Khelifi, et al. (2006) described that re-generated used oil help to protect the environment
and preserve valuable re-sources as well as to reduce its environmental impact.
21
Boughton and Horvath (2004) described used oil management strategies in their end-of-
life scenario in California. They found that re-refining and MDO impacts on air quality
are approximately equivalent and both are significantly better than burning RFO.
ETEC (1998) described the re-refining process that typically involves but is not limited to
filtration after pre-treatment by heat or, followed by either vacuum distillation with
hydrogen finishing or clay or solvent extraction with clay and chemical treatment with
hydro-heating. In case of small-scale plants of range from 10, 000 to 30,000 tons capacity
range vacuum distillation option followed by clay contacting offers a less polluting and
more economic and a less polluting solution to the re-refining process. Where as in case
re-processing process that make the used oil finished by filtration that remove coarse
solids have a low in basic sediments which can create environmental hazard or
operational problems.
Fitchner (1997) described about the disposal of resulting residual by-product of used oil
that is well compacted and baled in thick plastic sheets prior to disposal in landfills,
recommended the participation of a reputable recycling company that can play an
important role in enhancing the trust factor for the disposal of residual by-product of
used.
Manzoor et al. (1996) described the used lubricating oil collection areas in Libya through
field survey that used oil has been disposed off as worth less material. He further reported
that most suitable way to utilize it is re-refining to high quality used oil into base oil from
an economical and environment protection point of view.
Mortier et al. (1992) reported that waste oil is usually disposed of either by burning as
fuel or incineration; where as used oil is taken care under some treatment to produce re-
usable base fluids. They found during re-refining, the used oil physical and chemical
properties are enhanced to nearly similar initial condition by the selected processes
including solvent extraction, hydrogenation and adsorption. Re-refining produce new
base stocks from used oil, which can be used repeatedly.
22
Mueller Associates (1987) described that energy generated from burning used oil
averages 18,000 BTUs per pound approximately 144,000 BTUs per gallon.
Brinkman, and Dennis (1985) and Weinstein et al. (1982) reported that treating used oil
as a resource implies that it will become a raw material for a new product. The only
process that manages used oil in this way is re-refining to create new lubricating oils. Re-
refining is a chemical process that employs techniques from the crude oil refining
industry to clean and separate the components of used oil. Resulting products include
light hydrocarbons that may be used as fuel, base lubricating oil, and a heavy end product
that is often incorporated as an asphalt extender.
Horton (1982) described that treating used oil as a waste should be discouraged because
of its environmental impacts.
Baranowski (1982) described that lubricating oil may be used over and over again if it is
relieved of its impurities. It retains its lubricating properties throughout the heat and
stress of engine operation.
Brinkman, et al. (1981) reported that burning destroys a high-quality base stock that has a
significant energy investment in its production.
Weinstein, et al. (1974) described the base oil improved quality from the used oil and
further described that process by additional of very simple processing such as acid
treatment or filtration method, to remove less desirable component (e.g. wax, aromatics
and asphalt). The fundamental processes of re-refining of used oil are decanting followed
by settling and filtering due to less or no additives content, which required only settling
process to remove dirt, sludge, waste and treatment of volatile compound.
2.7.2 Acid /clay treatment
Acid /clay process was one of the successful methods in recovering the used oil for the
last three decades ago. This treatment is most dominated process in re-refining of used oil
23
as shown in Figure 2.1. It consists of five stages process, in which the oil is firstly
dehydrated in flash dehydrator. The over head product is condensed and separated from
light oil, while the bottom product is then treated in wastewater disposal system
(Weinstein, et al. 1974).
Fig. 2.1: Flow diagram Acid / clay treatment process
Sherman et al. (2001) described the method of removal of contaminants from used oil by
a process that is a batch mode or the continuous flow mode process mainly the removing
of color, polynuclear aromatic hydrocarbons, acidic compounds and removing or
converting heteroatom from used oil distillates. In case when operate in the continuous
flow mode, in used oil catalyst and the base are injected so that to pass through a heat
exchanger to increase the temperature of the mixture. Catalyst and the base mixture are
then pumped through one or more static mixtures mix with used oil. It is then passed
directly to the distillation apparatus, where additional mixing occurs and the resulting oil
and catalyst are recovered separately. The catalyst is recovered contains small quantities
of water typically less than 1 %, which is stable directly in the process and the recovered
catalyst is recovered in a form virtually free of hydrocarbon contamination.
24
Lim (2000) compared vacuum distillation with acid clay treatment, concluded that
vacuum distillation process needs high energy. However, this process removes the
additives and contaminants easily with little generation of hazardous waste. At initial
stage, the used oil is dehydrated at 300 oF at atmospheric pressure for water and light
hydrocarbons removal. The bottom product from distillation is mixed with 20% by
volume of light oil and small amount of caustic 0.2-2% to break the oil water emulsion
and precipitate solids. It is then separated by centrifugation. The centrifuged oil is heated
to 700 oF, producing the naphtha oil that can be used as fuel in the plant or treated with
activated clay as lube blending stock.
Mortier et al. (1992) the dehydrated oil is treated with 98% sulfuric acid, which results in
large quantities of acid sludge. Acid sludge is then separated, and the remaining oil is
then treated with clay and filtered. The treated oil is dark in colour with some odor, while
the acid sludge and oil-soaked clay are disposed off to environment in acceptable manner.
2.7.3 Distillation /hydro-treatment
During this process, the base oil fraction is hydro-treated under moderate condition then
followed by pre-treatment and thin-film distillation. Distillation yields a range of base oil
streams of different viscosity as well as by-products with low boiling distillate, gas oil,
and non-hazardous asphaltic residue. For example, in KTI process (Kinetics Technology
International) the oil is first distillate via a distillation column to separate water and light
ends fraction as shown in Figure 2.2. Pre-treated oil is then mixed with a hydrogen-rich
gas heated and passed through a reactor holding a fixed catalyst bed. Hydrogen is added
to the oil to saturate or “rebuilds” the oil to bring it back to specification (Saunders,
1996).
Weinstein, et al.; (1974) reported that hydrogenation process replaces the oxygen and
nitrogen containing impurities and unsaturated. Klamann (1983) claimed the yields in be
between 80-85%.
25
Fig. 2.2: Flow diagram of KTI re-refining process
.7.4 Solvent extraction re-refining
In re-refining of base oil from used oil, solvent extraction is defined as a refining process
to separate reactive components (unsaturated hydrocarbons) from lubricant in order to
improve the oil oxidation stability, viscosity index (VI), additive response and recover the
solvent use in the process as shown in Figure 2.3. Re-refining has been reported to be
well suited for re-refining multi-grade motor oils formulated with high concentration of
additives and containing large amount of residual compounds generated by heat and
friction during usage. Basically, there are two types of solvent extraction method, either
using a solvent or composite solvent.
Ricon, et al. (2005) reported that among the alternative processes, solvents extraction
process received considerable attention.
2
26
Using solvent(s) can overcome such a problem that occurs when using conventional
artin (1997) used combination of n-hexane, 2- propanol and 1-butanol as the solvents in
Royberg, et al. (1992) described the solvent extraction as the distribution of solute
between two ther.
Fig. 2.3: Bock diagram of Solvent Extraction process
methods; such as eliminating the requirement of hydrogen, reduced the production of
hazardous byproducts (acid sludge), the need of very high temperature or high pressure
operations, or need for periodic catalyst (Daspit et al. 2000).
M
addition to 3g/L potassium hydroxide to extract the base oil.
immiscible liquid phases in contact with each o
Blumberg (1988) described that solvent extraction is a process of transferring a solute
from one liquid across a boundary of another immiscible or partially miscible.
During solvent extraction process, the base oil is extracted using various selective types
of solvents, either composite or single solvent. The main purpose of using solvent as
27
extracting agent is to recover the base fluids, as well as to remove the additives and
bonaceous particles, which is the base oil
molecules but incapable to segregate and flocculate impurities. This is also observed for
inimum amount of oil
ount of sludge removal. Proper selection of composite solvent is better
o (1988) described that at an operation temperature below the room
perature, this hydrocarbon alone can be used as an extracting solvent because it is
particulate matter (Reis and Jeronimo, 1988). The solvent (s) must be
• Be miscible with the base oil contained in the used oil
• Reject the additives and disperse particles from solution
• Be stable, easy to recover and low price.
The presence of n-hexane disperses the car
complex hydrocarbon mixtures such as n-pentane, benzene, cyclopentane, cyclohexane,
and toluene. However, at an operation temperature below the room temperature this
hydrocarbon alone can be used as an extracting solvent because it is miscible with the
base oils and capable to segregate the impurities (Reis and Jeronimo, 1988).
Reis and Jeronimo (1988) used the minimum amount of hydrocarbon solvent with the
maximum amount of polar compound as the basis of composite solvent to get the best
result in extracting the base oils from used lubricant oil. The combination of alcohol and
ketone/hydrogen gave the best of extraction the base fluids with m
losses and high am
alternative than using single solvent, which needs high temperature or cooled
hydrocarbon.
Reis and Jeronim
tem
miscible with the base oils and capable to segregate the impurities. Alcohols or ketones
with more than three carbon atoms are miscible and can extract the base oil. Butanon and
butanols (1-butanol, 2-butanol, sec- butanols, and tert-butyl-alcohol) dissolve the base oil
and segregate the impurities from the solution. In order to use ethanol alone as the
extracting agent, it must be heated at above the room temperature to get the desired
result. Addition of ionization inorganic substance (e.g. potassium hydroxide) to the
solvent will increase the capability of sludge removal.
28
If the complex hydrocarbon alone is used as an extracting solvent, it will keep the
solution of macromolecular and other additives stable, at room temperature. It also
stabilizes the dispersion of carbonaceous particles; no flocculation will occur (Reis and
ronimo 1988).
rinkman and Dennis (1986) reported that Bartlesville Energy Research Center (BERC)
lecular and other additives stable,
t room temperature. It also stabilizes the dispersion of carbonaceous particles. No
Je
B
process, it was reported by, that the optimum system was achieved at combination of 2-
propanol, 1-butanol, and methyl ethyl ketone in a ratio of 1:2:1, with solvent to oil ratio
of 3:1. The yield was 71%. Water and low-boiling contaminants in the used oil were
removed by vacuum distillation, and the oil was then dissolved in a solvent of 1- butanol,
2-propanol and methylethyl ketone, which precipitated a sludge containing most of the
solid and liquid contaminants, unspent additives, and oxidation products.
Wishman, et al.(1978) used isobutanol, isopropanol and methyl-ethyl ketone as the
extracting solvent, after separating the purified oil- solvent mixture from the sludge and
recovering the solvent for recycling, the purified oil was preferably fractional vacuum-
distilled, forming lubricating oil distillate fractions followed by color and odor removal.
2.7.3.1 Single solvent as extracting solvent
Generally, hydrocarbons, alcohols and ketones are the most popular solvents that are
being used as extracting agents for base oil in solvent extraction method. These solvents
are miscible with the base oil and can segregate the impurities from the solution. Using a
single solvent like propane as an extracting agent is ineffective at eliminating polar
macromolecules, such as polymethacrylates, but very effective at flocculating polyolefin
and other nonpolar or slightly polar macromolecules. As a result, the pre-treated oil may
still contain come macromolecules. If the complex hydrocarbon alone is used as an
extracting solvent, it will keep the solution of macromo
a
flocculation will occur. The presence of n-hexane disperses the carbonaceous particles,
which is the base oil molecules but incapable to segregate and flocculate impurities (Reis
29
and Jernimo, 1988). This is also observed for complex hydrocarbon mixtures such as n-
pentane, benzene, cyclopentane, cyclohexane, and toluene (Reis and Jernimo, 1988).
However, at an operation temperature below the room temperature this hydrocarbon
lone can be used as an extracting solvent because it is miscible with the base oils and
d butanols (1-butanol, 2-
utanol, sec- butanols, and tert-butyl-alcohol) dissolve the base oil and segregate the
ne as the extracting agent, it must
e heated at above the room temperature to get the desired result. Addition of ionization
sludge.
omposite solvent must be soluble with the base oil at operation temperature preferably
perate as the extracting agent. The elementary formulation of
omposite solvent for extraction-flocculation is selecting the basic and polar component.
a
capable to segregate the impurities. Alcohols or ketones with more than three carbon
atoms are miscible and can extract the base oil. Butanone an
b
impurities from the solution. In order to use ethanol alo
b
inorganic substance (e.g. potassium hydroxide, KOH) to the solvent will increase the
capability of sludge removal (Reis and Jernimo, 1988).
Fletcher, et al. (1982) used extraction column instead of mixing the used oil directly with
tetrahydro-furfuryl alcohol, the solvent is removed from the raffinate system by steam
distillation and stripping, leaving the base oil for further treatment. Butanol is used to
precipitate and separate the impurities (e.g. polar additives and oxidation products) in the
layer form of
Brownwell, (1972) N-methyl-2-pyrrolidone (NMP) extracts the base oil from the
undesirable component using liquid-liquid extraction method.
2.7.3.2 Composite Solvent an Extracting Solvent
C
at room temperature to o
c
Basic component contributes to some flocculation action and is miscible with the base
oil, whereas the polar compound improves the solvent flocculating capability by giving a
higher amount of sludge removal. In some cases, hydrocarbon (e.g. n-hexane) is used as
the basic component, and alcohol (e.g. 2-propanol) is used as the polar compound (Reis
et al., 1988).
30
Whisman (1974) stated that there are 22 types of composite solvent as shown in Table
2.7, having the ability to remove the contaminants and with excellent reduction of
inorganic compound in the used oil. Those solvents include ketones, alcohols and
hydrocarbons in various combinations that had shown an excellent result of sludge
removal up to 10%, which corresponds roughly to the amount of additives.
ess between solutes
olecules) is called Van der Waals force and certain molecular geometries are known as
polarity result fr
ensuring the solubility between liquids or solids. Similar polarities of substances will
result in soluble mixtures. Consequently, in vaporization, certain amount of energy is
added to a system of solution in order to vaporize the liquid into vapor form. This amount
of energy is known as heat of vaporization.
According to (Burke,1984), heat of vaporization is similar to Van der Waal’s forces that
held the molecules of the liquid together since the same intermolecular attractive forces
have to be overcome to vaporize the liquid. In a case of mixing two liquid, the molecules
of the liquid are physically separated by the molecules of other liquids, similar to the
separation that happens during vaporization. Therefore, the same intermolecular Van der
Waal’s forces must be overcome in both cases. Hence, from heat of vaporization, the
cohesive energy density can be derived by the following expression;
∆H-RT)/ Vm (cal/cm3) …………… (2.1)
2.8 SOLUBILITY
Liquid substance, or the solvent, has to overcome intermolecular stickiness of the solute
molecules to be miscible and provide the similar attraction between all molecules
components (including solvent and solute molecules). Solvent becomes immiscible with
solute if attachment of the solute molecules is stronger compared to the intermolecular
stickiness between solvent and solute. The intermolecular stickin
(m
om the deviations of the electron density. These forces are responsible in
[(=c
31
Where: cohesive energy density, =c
∆ =H heat of vaporization,
=R gas constant, T = temperature
= m molar volume V
Table 2.7: Effect of solvent extraction system on used oil
Solvent System, ratio Oil recovery, %
Acetone/pentane 1:1 91
Acetone/pentane 3:1 83
Acetone/pentane 1:3 99
Acetone/toluene/pentane 1:2:1 91
Acetone/pentane 1:1 96
2-propanol/1-butanol 1:1 90
1-butanol/pentane 1:1 92
Methylethylketone(MEK)/1-butanol 1:1 89
MEK/2-propanol 1:1 92
MEK/pentane 1:1 95
MEK/acetone 1:1 66
1-butanol/ acetone 1:1 87
Methanol/1-pentanol 1:1 26
Methanol/2-methyl/1-butanol 4(2-Me-BuOH-4)1:1 17
1-pentanol/2- propanol 1:1 92
2-Me-BuOH-4/2- propanol 1:1 86
2-propanol/1-butanol 1:3 84
2-propanol/1-butanol 3:1 77
2-propanol/1-butanol 1:2 90
2-propanol/1-butanol 2:1 79
2-propanol/1-butanol 1:3* 93
2-propanol/1-butanol 2:1* 91
Source (Vaughn, 1975)
32
2.8.1 Coagulation, flocculation and aggregation
Coagulation is chemical destabilization of solution where the electrolytes are added into a
solution to reduced the charges on particles and allow a close approach to aggregation. In
coagulation, the lyphobic colloid becomes unstable and flocculated by the addition of
electrolytes. It is usually achieved by addition of chemical reagents, which by bonding or
adsorption mechanism; nullify the repulsive forces on the colloidal particles surface.
Coagulation is the initial colloid destabilization, principally by charge neutralization after
adding the coagulant, which occurs rapidly at the early phase of flocculation, while
flocculation is the subsequent aggregation of µm and sub-µm- size particles into
minimize flocs. Thus, the term coagulation–flocculation describes the first stage in
extraction-flocculation process that removes the non- settable solid particles by
sedimentation through transformation of the particles into larger and heavier settable
solid particles (Jiang, 2000).
Biggs et al. (2000) recommended the aggregation via bridging process because of the
flocs formed is very strong and rate of their formation is quickest at lower polymer
concentration Gregory (1999) in polymer complex formation of flocculation mechanism, the polymeric
flocculants interact with other particles which present naturally in the system and leads to
polymer complex formation. “Sweep flocculation” occurs when correct dosage of
hydrolyzing flocculants (e.g. aluminum, iron salts) is added to form hydrous oxide
precipitates, which destabilizes the colloidal particles).
Gregory (1997) defined flocculation as the action of polymeric materials, which form
bridges between individual particles and help these particles aggregate. Flocculation
depends on the settling rate of the individual particles, which is proportional to the size of
the particles. When the size of the particles is below a few microns, the settling rate is
low. However, for many fine suspension particles, it agglomerates with each other to
33
settle at reasonable rate so that separation can be carried out efficiently. Thus, to
accelerate the rate of particle settling, agglomeration is promoted by adding flocculating
agents, or polymeric flocculants that may be cationic, anionic, or nonionic in character,
which reduce and over come the repulsive forces between the charged particles.
Gregory (1997) describe the formation of two types of cluster during flocculation
depends on various factors, such as the different mechanism of flocs growth. The
formation of compact structure (cluster-cluster), which has a high density, implies high
sedimentation. Meanwhile, particle-cluster aggregation is an encounter of two clusters in
the first contact, which leads to a much more open structure. In cluster- cluster case,
collision between the same particles is reduced that contributes to more compact structure
as shown in Figure2.4.
Fig. 2.4: Diagram of particle-cluster and cluster-cluster aggregation
McCabe et al. (1993) described the three main types of flocculants agent or coagulants
are inorganic electrolytes (alum, lime, and ferric chloride), organic polymers and
synthetic polyelectrolytes in acidic or basic solution with anionic or cationic functional
groups, and the most effective flocculants is linear polymeric flocculants which is either
natural or synthetic polymer, with nonionic, cationic or anionic character.
34
NEESA 1993 and Gregory (1985), described that the addition of coagulants is followed
by low sheer mixing in flocculator to promote contact between the particles, allowing the
particle growth through the sedimentation phenomenon called flocculants settling.
Gregory (1985) described cluster aggregation is desired form of flocculation, which
occurs by agitation. However, open flocs structure will increase settling rates due to
reduction of drag. Four types of flocculation mechanisms are bridging flocculation,
charge neutralization, complex formation and depletion flocculation. During bridging
flocculation, the polymer flocculants can extend far enough from the particles surfaces to
attach with the other particles with sufficient free surface. Thus, excess flocculants will
promote re-stabilization of the particles as shown in Figure 2.5.
Fig. 2.5: Bridging flocculation
Although the flocs have the strongest attachment by the polymer, it is limited by the ionic
interaction. The structure forms through bridging flocculation contain large filamentous
matrices of polymer holding small inorganic particles together in an aggregate as shown
in Figure 2.6. In the solution high molecular weight of polymer will occupy a large
volume and may be able to interact with more than one particle.
35
Fig. 2.6: Aggregations via polymer bridging
This mechanism needs low molecular weight of polymers, which is less
expensive and more convenient to use
Gregory (1985) pointed out the hydroxide flocks are weak and can be inversed by
addition of small amount of a high molecular weight anionic polymer.
Gregory (1985) reported flocculation by free polymer is also known as depletion
flocculation. Non- absorbing polymer promotes flocculation of suspensions. The origin of
the effect is the extraction of large polymer molecules from the narrow zone between
closely approaching particles. The exclusion, which occurs for simple geometric reason,
leads to an osmotic pressure difference between contact zones, which pull the particles
together.
Gregory (1985) described that charge neutralization occurs when there is a strong ionic
interaction between the charged particles and the opposite charge of flocculants that is
added for effective flocculation. Initially, the charged particles are stabilized by electrical
repulsion, thus the presence of opposite charge of flocculent reduces or eliminates
repulsive forces and lead to flocculation. Excess amount of flocculent will re-stabilize the
particles.
36
2.8.2 Mixing in flocculation
Collision frequency is also increased by agitation during mixing beside higher
concentration of particles (Biggs et al, 2000).
Agitation at initial condition encourages collision of particles to form aggregates
avoiding local overdosing and re-stabilization of particles due to uneven distribution of
flocculants (Elimelech, 1995)
During addition of polymer solution addition, the following rates of flocculation process
can be achieved. The process is understood to cause bridging effects with some
possibility of charge effects; either simple charge neutralization or some form of
electrostatic patch interaction as shown in Figure 2.7. These processes that developed at
different rates, depends on various factors (Gregory, 1985).
Fig. 2.7: Schematic illustration of the stages involved in the flocculation by
polymer addition
37
There are three possibilities that affect flocculation occurrence. At the point of polymer
solution addition, a high degree of turbulence occurs, which affects the flocculation
process and leads to collision between particles and polymer. In some cases, when the
polymer is slowly added, overdosing effects
m cs size is reduced
with continuous stirring (Elim
2.8.3 Addition of po sium hydro
e of OH groups
at neutralize the electrostatic repulsion. This electrostatic repulsion exists since alcohol
additive. Addition of a solution containing ions
that neutralize those charge, break this stability (Lim, 2000). Participation of alcohol OH
tion is illustrated as below:
x
K+ is the ion of Kalium / Potassium
cles
rom a liquid stream by gravitational settling.
are reduced and therefore allow rapid growth
of flocs. At certain time of ixing or after some time of dosing, the flo
elech, 1995)
tas xide
Addition of KOH promotes a fast flocculation of the impurities, which are segregate from
the base oil by 2-propanol. The flocculation is enhanced in the presenc
th
group are linked with the ions from the
groups in ion exchange reactions with the electrolyte ions helps to neutralize the
electrostatic repulsion. The stoichiometric equa
Cx – OH + K+ Cx – OK + H+ …………… (2.2) Where; C – OH is the several type of alcohol
H+ is the ion of Hydrogen
Jiang (2000) classified metal complexes as colloidal particles that destabilized in addition
of coagulant; in this case, the coagulant is potassium hydroxide (KOH).
2.8.4 Sedimentation-consolidation
Schweitzer (1988) described sedimentation as the separation of suspended solid parti
f
38
Schiffman (1985) and Gregory (1997) define sedimentation as a process, which the
particles or systems of particles settle out of a fluid suspension under the action of
gravity.
Sedimentation can be enhanced by flocculation, Figure 2.8 describes flocculation-
sedimentation in batch system in which the setting of flocculated suspension forming
different zones as the sedimentation proceeds, basically there are five stages to complete
the sedimentation process. In the first stage (flocculation stages), the solid particles are
distributed uniformly unit the time t1, with initial total depth of suspension, zo. Shortly
after t1, the part of the solid has settled down (zone D), giving a clear zone A, the
transition layer zone C, and zone B (free setting zone) where the concentration is uniform
with the setting rate through out the zone (Geonkoplis, 1995; and Schiffman, 1985)
Fig. 2.8: Flocculation-sedimentation-consolidation
The process is then continued with the decreasing of zone B and increasing of zone D &
A, while the zone C remains constant. At the fourth stage, the accumulation of solid
particles increases gradually and is followed by compression that breaks down the flocs
39
aggregate. This is where the consolidation process starts to take place. Consolidation is
defined as a system of particles deforms under the action of imposed disturbance. The
imposed disturbance is considered as mechanical action consisting of self-weight of the
ulk system (particles and fluid) and/ or an imposed surcharge loading (Schiffman,
n, Low concentration of
uspension particle leads to an independent settlement of aggregates and particles.
pension contributes to hinder settling where other particles
fluence the settlement. The motion of the settling particles is affected by the
rates continuously. This plant treats 250 Kg of used oil daily and
onsists of five major sections. Throughout the first section, the used oil is heated at
bout 1800C to remove water and light hydrocarbons. The oil is then cooled before
entering the extraction-flocculation section,
mixture and extraction a re, the dehydrated oil is
ixed with the solvent (n-hexane and 2-propanol with addition of 3g KOH/L 2-propanol)
in ratio of 3:1.The mixture is then subjected to extraction- flocculation tank to remove the
b
1985). The settling process is stopped when the weight of the solid is balanced with the
compression strength.
One of the factors affecting sedimentation is the concentratio
s
Meanwhile, concentrated sus
in
hydrodynamic interaction with other moving particles. Small particles in the suspension
pulled down the larger ones, while the settling rate of the larger one is retarded by the
smaller particles. Nature of particles, such as size distribution, shape, specific gravity,
mineralogical and chemical properties, is also affecting the sedimentation (Geonkoplis,
1995; and Elimelech, 1995).
According to Geonkoplis (1995), particles or aggregates of spherical or agglomerates
settle more rapidly compare to non- spherical plate or needle- like particles with similar
weight. Flocculation of these non-similar particles leads to formation of fairly well-
rounded aggregates, which improves the settling characteristic.
2.9 SYSTEM DESIGN
Reis and Jeronimo (1991) designed a pilot plant of re-refining the base oil from used
lubricant oil that ope
c
a
which consists of two major equipment;
nd extraction-flocculation tank. In mixtu
m
40
sludge and to decant the raffinate. The tank is designed to have the maximum retention
time of two hours for acceptable sludge separation, and minimum retention time of 30
minutes for 0.005% of solids in effluents. The process is followed by solvent recovery
system for solvent recycling, which operates at temperature below 100C at ambient
pressure. The pre-treated oil, which is recovered from the solvent, is then further treated
via vacuum distillation and bauxite bed for macromolecules, odor and colour removal as
shown in Figure 2.9.
Fig. 2.9: Block diagram of pilot plant
2.9.1 Pilot plant scale
t scale is an intermediate operation between laboratory and industrial scale. In a
f the
ified by the equipment size and operation area. In micro units or bench- top pilot
Pilot plan
pilot plant operation, the most important thing that determines the effectiveness o
process is system design. At this stage, the process is being optimized to reduce the over
all cost of the project while allowing an investigation into most of any unexpected
problems and other opportunities. Basically, there are two types of pilot plant that can be
class
41
plant, the tubing size is 1/16 to 1/4 inch with 0.5 to 1.0m2 of operation area, whereas in
integrated pilot plant or research-scale pilot plant, the tubing size is 1/4 to 1 inch with
operation area of 2 to 14m2 (Palluzi, 1992)
2.9.2 Process Mechanism
ll be ended with consolidation. After
edimentation and consolidation, the solution of the base oil in the composite solvent is
nd of the condenser. Base oil is
en removed from solvent recovery system as the pre-treated oil, or further treated for
.10 RE-REFINED BASE OIL QUALITY
Mortier et al. (1992) described that basically, re-refined oil is manufactured oil with
minimum 25% of re-refined base stock. Re-refined lu in
ards for acceptance. ty
refined base oil as shown in T
unusual odor are two major thin they represent
yclic aromatic hydrocar arcinogenic
and re-refined base oil. However, those harmful PAHs can be removed
hydrogenation and solvent extrac 92)
Os disposed of on l , pits, fields,
landfills is related to sorbs to solid
During extraction process, the impurities are removed from the solution and will be
flocculated in the presence of potassium hydroxide (KOH). The flocculated sludge is
sedimented by the gravity action and wi
s
filtered by membrane filtration and subjected to the solvent recovery system. Composite
solvent is then separated from the base oil by transforming in to vapor from, where it is
then condenses into liquid and will be collected at the e
th
odor and colour removal.
2
bricant base oil must meet certa
specifically required stand There are some guidelines for quali
acceptance of re- able 2.8.
Dark color and gs taken into account, since
the oil quality. Polyc bons (PAHs) are the main c
agents in used oil
efficiently by tion methods (Mortier et al., 19
In general, the fate of WC and (e.g., in backyards, alleys
and drainage ways) or to the amount of WCOs that ad
42
matter, leaching via runoff percolating throug degradation
NGINEERING LTD., 1992).
have demonstrated that a vari ich are in
achates and groundw nhard et al,
Barker et al., 1986, 1988a,
re nd or in landfills, a separate liquid
phase would be generated (Villaume
Table 2.8: Guidelines for quality acceptance of re-refined base oil
Grade
h the refuse or soil, and bio
(CH2M HILL E
Several studies ety of compounds, many of wh
WCOs, are in landfill le ater (Cherry et al, 1983; Rei
1984, Barker, 1987, 1988b).
When large quantities of WCOs a disposed of on la
, 1985).
Properties 150 200
Viscosity @ 1000C (cSt) 5.0 + 0.2 11.0+0.4
Viscosity Index
Flash point (0C)b
Pour point (0C)c
Dialysis Residue (%)c
Ring analysis (%)c
ASTM Colorc
Total acid number(mg KOH)c
Noack volatility (% loss)c
IP 154 copper corrosion c
Odor
Chlorine (ppm) c
Water (ppm) c
PAHs (ppm) cd
PAHs (ppm) ce
Individual metals(ppm) c
Sulphated ash(%)c
90-100 90-100
210 230
-9 -9
0.1 0.1
12 12
3 4.5
0.1 0.1
18 18
1 1
No foreign odor in finish product
10 10
50 50
3 3
250 250
10 10
0.01 0.01
(Sources Mortier et al., 1992) bminimum, cmaximum, dby IP 346, ePAHs from fluoranthene by grimmer method
43
CHAPTER 3
WASTE OIL MANAGEMENT
3.1 INTRODUCTION
Lubricating oil, or lubricant oil, obtained either by refining distillate or by residual
fractions directly from crude oil is made up primarily a complex mixture of
hydrocarbons, 80 to 90% by volume and additives 10 to 20% by volume according to its
grade and specific duty (Petro-Canada 1987, Franklin Associates Ltd 1985, Vazquez-
Duhalt, 1989). Additives are added to fulfill the specific requirement for lubrication
performance in particular applications, to impart new, useful and specific properties to
lubricant oil, to enhance present properties and to reduce the rate of undesirable change
that take place during its service life. Summary of additives function is listed in Table
2.2. The waste crankcase oil is removed from the crankcase (engine sump) of internal
crankcase combustion engine that is generated from
vehicles) (CCME 1989a; CH2M HILL, 1992). One
automotive (light and heavy
of the sources of pollution from the
transport sector is was completely; the
major portion is being misused or discarded by the end user in the environment. In this
sense, the treatm nt or reuse treatm
manage oting energy conservation
use, crankcase oils are altered becau ination
with t ts of comb of metals wear and tear of the
engin re compos case oil varie aracterize.
CH2M 992) ge ntaminants in waste crankcase oils are
polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and other
polyc ounds r in e halogenated
hydro resulting from the chemical breakdown of the additive package also build
up in nd the addition of chlor and bromine t lead scavengers in
leaded gasoline. These components are highly toxic when released to the environment,
particularly to water courses as this causes the obstruction of sunlight and oxygen from
te crankcase oil. This oil is not being collected
e ent of oils provide a suitable way for waste-oil
ment by prom and environmental sustainability. During
se of the breakdown of the additives, contam
he produc ustion and the addition from the
e, therefo ition of waste crank s and difficult to ch
HILL (1 nerally the main co
yclic comp are produced and gathe the oil. Som
carbons
the oil a ine hat act as
44
the at water, which consequently poses harmful effects to quatic lives. On
the ba chain, toxins can accum late in plankton and other tiny organisms and
ultimately reach human beings as contam ts move up the food chain, where as from
health hazards point of view the ingested waste-oil-contaminated, waste range from mild
symp ms of accumulation of toxic compounds in the liver to complete impairment of
body functions and eventually death (Noln et al, 1990). Principal contaminants are shown
Table 3.1, but there are other potential contaminants such as alkylbenzenes,
is
ecessary that proper waste oil management at all stages of usage from generation,
mosphere to a
se of food u
inan
to
in
perchloroethylene. To minimize potential adverse impacts of these contaminants, so it
n
collection, processing and end use.
Table 3.1: Principal contaminants in used oil
Metals Chlorinated hydrocarbons Other organics
Aluminium Dichlorodifluoromethane Benzene
Antimony Trichclorotrifluorethane Toluene
Arsenic 1,1,1-Trichloroethane Xylenes
Barium Trichloroethylene Benz(a)anthracene
Cadmium Tetrachloroethylene Benzo(a)pyrene
Calcium Total chlorine Naphthalene
Chromium Polychlorinated biphenyls Other PAHs
Cobalt - Sulphur
Copper - Nitrogen
Lead - -
Magnesium - -
Manganese - -
Mercury - -
Nickel - -
Source (www.mfe.govt.nz 2000)
45
3.2 PROPERTIES AND CHARACTERISTICS OF USED LUBRICANT OIL Used oil is characterized by its physical and chemical properties. The analysis of its
the density, specific gravity, viscosity, water content, ash
are color and odour, metal content, total acid and base numbers, saponification number,
oducts and rain (Mortier et al,1992),
hile some solid contaminated the oil via the unchanged additives (e.g. polyisobutylene
nd polymethacrylate), wear metal, rust and dirt (USEPA, 1988). Colour and odour
roblem comes from the nitrogen and oxygen, which are produced by the reaction of
ngine combustion gases with lubricating oils. Beside these impurities, used oil also
onsists of unchang ase oil molecules that one intends to recover (lim, 2000). Thus,
me treatment is essential to recover the base oil that can be used repeatedly.
.3 WASTE CRANKCASE OIL DISPOSAL PRACTICES IN PAKISTAN
ehicle waste oil is transportation- relates matter as it is generated mainly in repair
orkshops, service stations, and government and military motor pools. In Pakistan there
physical properties including
content, carbon residue content and flash point, while the chemical properties of used oil
as well as the sulfur and nitrogen content. The presences of contaminants or impurities
are indicated by the difference values that occur between the initial (virgin oil) values of
these properties.
Referring to Table 2.4, the alteration of specific gravity from its initial condition at 0.882
to 0.910 reveals the existence of contaminants or impurities, indicated by the increasing
value of water content from 0-12.3 wt%. This is also showed by means of the increasing
value of the carbon residue (0.82 wt %) and ash content (0.94 wt %) to 3 wt% and
1.3wt%, respectively. Metal contents (e.g. magnesium, barium, zinc, calcium and lead)
are also increased; resulting from the contaminants of wear metal and rust. Used oil is
normally acidic in nature, which indicates by the high value of total acid number.
Changed in physical and chemical properties of used oil indicates that it consists of
several possible contaminants including some chemicals and residual components of
gasoline. Water is product of the combustion of bypr
w
a
p
e
c ed b
so
3
V
w
46
are different uses of lubricating oil mainly are in four categories: Hydraulic system,
nsmission system, engine oil and grease. The used engine oil handling and disposal of
country’s
environment. A limited field survey carried out to estimate the quantity and its disposal.
The survey instruments were used to obtain primary data sets through the questionnaires
and the main actors in the used oil markets were identified as waste generators,
collection, storage, distribution and utilization (Durrani et al, 2008). The data obtained
discovered that in Pakistan do-it-yourself oil changes are not common practiced
techniques, and about 95% of oil changes occur either in repair shops/ garages or in
service stations and 5% of waste oil goes to land fill, 10% in sewers, 25% is used in sub-
standard re-refining and grease making and 60% is burnt (Sugar mills, cement factories,
furnaces and low pressure boilers, etc) (Durrani et al, 2008) as shown in Figure 3.1 and
its environment impact are presented in Table.3.2.
Fig. 3.1: Waste crankcase oil disposal practices in Pakistan
tra
is a extensive source of environment degradation and ecological damage
0102030405060708090
100
LandDisposal
SewersDisposal
Re-refining Burning
1009080706050403020100
47
Table 3.2: Current vehicle waste-oil disposal practices in Pakistan
Disposal practices Potential environmental impact
• Dumping on land, drainage, public sewerage, rivers and streams. • Uncontrolled burning at sugar,
cement and glass factories, bakeries, power stations and metal industries.
• Low-grade recycling of limited
amounts of locally generated vehicle waste oil.
• Contamination soil, surface and ground water that is a natural resources.
• Potentially harmful atmospheric
emissions dangerous to public health as waste oil contains arsenic, chromium, cadmium, lead, sulfur and Zinc. • Pollution due to disposal of residues containing heavy metals.
Sources (Durrani et al,2008)
3.4 WASTE OIL MANAGEMENT OPTIONS
In the context of Pakistan six options have been considered as plausible, namely:
reprocessing, reclamation, regeneration, destruction, exporting to facilitate abroad and
other reuse practices. In Table 3.3, a comparative assessment of the different options is
presented.
In the waste management hierarchy, waste oil can be reused or recycled in a variety of
ways. The first option is to conserve the original properties of the oil allowing for direct
reuse and in the second option to recover its heating value. Re-refining could be seen as
first and one of the preferred methods for disposal of used oil to recycle the hydrocarbon
content of used oils. It has the beneficial effect of reducing the consumption of virgin oils
and environment affect.
Some management approach has been studied in evaluation of different waste crankcase
oil management scenarios; the boundary of the system was extended to include
environmental impacts associated with related processes and the basic treatments disposal
processes of used oil are summarized as follows:
48
3.4.1 Reprocessing
In this treatment process, oxidation products and insoluble contaminants need to be
removed from used oils by heating, settling, filtering, dehydrating and centrifuging, etc.
To bring the oil back to its original or an equivalent specification, it can be further
followed by blending with base oils and additives. The product produce by reprocessing
treatment is not comparable to virgin oil and is less demanding applications as it is
commonly used in industrial applications.
3.4.2 Reclamation
In this treatment solids and water separate from a variety of used oils. The process used
may include heating, filtering, dehydrating and centrifuging. The product quality of oil
can give a comparable quality to the original but may have different contaminants
depending on the nature of the process such as heavy metals, by-products of thermal
breakdown and substances associated with specific uses (e.g. lead, corrosion inhibitors,
PCBs). Reclaimed oil is generally used as a fuel or fuel extender.
Used oils can burn in most oil-fired domestic, commercial, industrial or utility boilers and
can lead to serious pollution of all environmental media even when combustion of used
oils not the subject of strict product specifications or under uncontrolled conditions and
also combustion plants will suffer corrosion when oils with halogen contents are burnt.
However, combustion of used oils not the subject of strict product specifications or under
uncontrolled conditions can lead to serious pollution of all environmental media.
3.4.3 Re-generation/ Re-refining
Re-generation/ Re-refining process involves removing contaminants, oxidation products
and additives produce base oils for the manufacturing of lubricating products. The
processes involved including pre-distillation, treatment with acids, solvent extraction,
contact with activated clay and hydro treating. This process is quite different then those
given under reclamation but the regeneration of used oils produce the highest degree of
49
contaminant removal leading to the recovery of the oil fraction which has the maximum
viable commercial value and is widely practiced.
The re-generation/ re-refining process typically involve, but is not limited to, pre-
treatment by heat or filtration, followed by either vacuum distillation with hydrogen
finishing or clay, or solvent extraction with clay and chemical treatment with hydro-
heating. Figure 3.2 provides a comparative illustration between the re-refining and re-
processing.
3.4.4 Destruction
The direct burning of used oils in conventional combustion devices can create serious
pollution problems as the waste oil is highly contaminated because of polychlorinated
byphenyls (PCB) and polychlorinated terphenyls (PCT). Although this can be reduced by
fitting pollution abatement equipment, this is not, in most cases, very practicable. In the
absence of hazardous waste incinerators, controlled high-temperature incineration at
cement factories is recommended as the operating temperatures ranges between 2000 and
2400°C at the flame and of rotating cement kilns.
3.4.5 Exporting to facilities abroad
Export of waste oil is one of the potential alternative disposal and environmentally sound
option for the generator and is the least costly but it may not offer a sustainable solution
as it may face difficulties in finding future outlets abroad as number of countries has
classified waste oil as hazardous waste. This option renders less attractive, besides that
the loss of valuable recoverable material, energy source and potential job creation
opportunities render this option less attractive.
50
3.4.6 Other reuse practices
There is variety of uses of waste lubricant oil other than re-refining and burning. It is
used for instance weeds killer, raw material in asphalt production, dust suppressant and
vehicle undercoating. There are number of countries that have prohibited such use of
waste oil from the heath and environment point of view.
Waste oil has been used extender in manufacturing of asphalt has constituents insoluble
in water. In the final product potential contaminants are coated with viscous asphaltic
materials. The hot coating of road stones with asphalt has given rise to environmental
problems. As a waste oil management practice this has been discouraged because it does
not reduce the volume of waste oil significantly and prohibited by a number of countries.
3.5 SUITABLE METHODS FOR WASTE OIL RE-GENERATION
The re-generating waste oil methods can be categorized into two, which are conventional
methods and new physical technological steps (Klamann, 1983). In the literature review
chapter all the methods (acid/clay treatment, distillation/clay treatment and
distillation/hydro-treatment) have been reviewed and the two methods, acid clay
treatment and solvent-extraction technique found the most suitable method of
regeneration of waste oil because it does not consume more power to run high powered
vacuum pump.
3.5.1 Acid/clay treatment
Acid/clay process was one of the successful methods in recovering the used oil for the
last three decades ago called conventional re-refining waste lubricant oil, yield is 45-
75% with good quality of the base oil depending upon the operating condition and feed
composition. The process ends up with large volume of acidic sludge as the by-product as
shown in Figure 2.1
51
3.5.2 Solvent extraction re-refining
Solvent extraction is a process to move a solute from one liquid across a boundary of
another immiscible or partially miscible liquid (Blumberg, 1988). It has been described
the solvent extraction as the distribution of solute between to immiscible liquid phases in
contact with each other (Royberg, et al, 1992). It is also defined as the distribution of a
solute between two immiscible liquid phases in contact with each other in separation of
solute mixture (Royberg, et al, 1992). It Involves separation technique of two immiscible
phases that are created by the introduction of foreign substance called the extracting
agent or extraction solvent. Solute distribution depends on its solubility to the extracting
solvent. It is described that solvent extraction is the separation of major or minor
components from solid for purification purpose and isolation of the separated
components and or their determination is chemical process of great industrial, synthetic
and analytical interest. Using solvent(s) can overcome such a problem that occurs when
using conventional methods; such as eliminating the requirement of hydrogen, reduce the
production of hazardous products (acid sludge), the need of very high temperature or high
pressure operations or need for periodic catalyst replacement and handling (Daspit et al,
2000). The recovery of oil is more than the other treatment process and is the cost
effective treatment process as the solvent (s) used can be recovered and reuse again and
again, it does not need high temperature. A flow diagram of solvent extraction is shown
in Figure 2.3.
52
Table 3.3: Waste oil management option in Pakistan
Options Advantages Disadvantages
Re-refining into lube oil
Environmentally friendly and long-term solution. Creates jobs locally Reduces the amount of Imported lubricating oil
Needs a well-developed waste-oil collection system to be established Recycled lube oil require a well-developed market needs extensive capital investment. The re-refining option needs a sound recycling company to make sure the marketability of the product. Proper disposal of end-waste residues are costly and problematic
Re-processing into fuel oil
Benefits as fuel substitute in Pakistan. Reduces the amount of imported fuel to Pakistan and creates jobs locally and controls the negative impact of uncontrolled burning of waste The quality control of the reprocessed fuel oil is monitored by the purchaser
Needs to well-developed a waste oil collection system. Requires extensive capital investment Proper disposal of end-waste residues are costly and problematic
Destruction Lower processing volumes economically feasible. Cement factories are interested to procure the waste oil Required Less capital intensive. Concentrates waste oil disposal to limited sites that can be more easily regulated and controlled
Air emissions, although minimal, will still need to be addressed may face stiff opposition by local residents and environmental NGOs
Exporting to facilities abroad
Low cost solution Least environmental impact
Not sustainable solution in the long-term and may face difficulties Finding outlets abroad in the future loss of valuable energy source that can be used locally loss of potential local job opportunities
Other reuse practices
-
Does not impact significantly on the reduction of waste
Source (Durrani et al, 2008)
53
Fig. 3.2: Flow diagrams of re-processing and re-refining processes
54
CHAPTER 4
METHODOLOGY AND EXPERIMENTAL WORK
4.1 INTRODUCTION
Experimental work and methodology of this research work is discussed in this chapter,
which is divided into five main sections. In this first section, vehicle waste oil generated
in Pakistan is discussed followed by collection, transportation and proposals with re-
generation locations. In the second section laboratory experimental work methodology is
discussed followed by raw materials and properties of the oil determined by American
Society for Testing and Materials (ASTM) test. In part three, the design and fabrication
of experimental rigs is discussed and in part four the laboratory scale data used in the
pilot scale rig for the re-refining of base oil from used lubricant oil is discussed.
4.2 QUANTIFYING VEHICLE WASTE OIL
The quantification of vehicle waste oil is based on the number of vehicles, the knowledge
of engine size, the frequency of oil changes, burn oil per service and period of oil change.
In this respect the data were collected using Delphi technique; questionnaires were
prepared and used in field survey.
4.2.1 Field survey of principle sources In used oil generation characteristics the following actors found involved in transport
section surveyed in province of Sindh a one of the industrial province of the country. A
set of questionnaires were prepared and circulated among generals and dealers of used
oil. The data collected is shown in appendix-A and B. The data collected reveals on
average that oil change practice is almost the same as all drivers of private and
commercial vehicles get the oil changed in repair shops and service stations, do-it-your
55
self is more common for farm-tractor and dealers of used oil are involved from collection
to its sale.
4.2.2 Number of vehicles registered
Registered vehicle data (GOP, 2006) released by Federal Bureau of Statistics Islamabad
prepared by National Transport Research Centre Islamabad (NTRCI) in an economic
survey of Pakistan. The data provided for the year 1991 to 2006 covered almost all
categories of vehicles is given in Table 4.1.
4.2.3 Crankcase size
Quantity of oil use in engines depends on the crankcase/chamber size of the engine and
based on this the quantity of used oil can be assessed. Data was collected through the
literature survey and from the automobile catalogues Table 4.2.
4.2.4 Engine oil change
Engine oil change data collected through a field survey from waste oil generators, repair
shops and service station as per the type of the vehicle is given in Table 4.3.
4.2.5 Number of time oil change per year
The data collected from the field survey shown in Table. 4.4 reveal the trend that almost
all light vehicles use to change the oil once in a month, where as the commercial vehicles
change the oil twice in a month. This data would help in quantifying the used oil
generated in a year.
56
Table 4.1: Motor vehicles on road in Pakistan
Tankers Others TotalYear
M.Cycle/ Scooter
Motor car Jeep Station Wagon
Tractor
Buses M.cab/Taxi
Motor Rck
D.van Trucks Pickup Ambu-lance Oil Water
1991-1992
971.80 429.10 31.60 43.60 275.30 45.00 33.50 42.40 61.40 75.80 30.20 1.70 4.00 0.60 49.50 2,095.50
1992-1993
1,165.50 465.80 35.60 48.80 353.00 51.70 40.00 46.70 69.80 48.20 39.50 2.00 4.30 0.70 52.70 2,460.00
1993-1994
1,287.30 493.70 38.00 52.70 376.60 56.40 44.50 50.50 74.00 92.00 44.10 2.30 4.70 0.70 73.60 2,690.40
1994-1995
1,482.00 561.80 41.30 56.00 399.80 60.90 47.90 53.40 78.20 98.30 47.10 2.70 5.10 0.80 60.70 2,951.60
1995-1996
1,481.90 538.40 43.50 59.00 424.80 64.50 51.40 58.70 81.30 104.20 50.50 3.30 5.60 0.90 63.70 3,000.20
1996-1997
1,576.00 564.50 45.50 62.00 439.80 68.20 54.10 65.60 84.30 110.30 50.20 3.70 6.10 1.10 66.50 3,195.80
1997-1998
1,691.40 593.00 47.80 65.00 463.30 72.50 57.30 74.60 87.60 117.10 56.10 4.30 6.80 1.30 69.70 3,405.30
1998-1999
1,833.70 731.30 16.70 60.60 489.80 84.40 68.50 56.70 51.70 121.00 56.40 1.50 6.80 0.70 74.70 3,651.70
1999-2000
2,010.00 815.70 17.00 73.90 528.40 92.80 69.80 59.90 55.50 127.40 61.60 1.70 7.00 0.70 78.80 3,997.20
2000-2001
2,218.90 928.00 18.30 93.80 579.40 86.60 79.80 72.40 72.40 132.30 68.40 1.70 7.20 0.80 89.00 4,471.00
2001-2002
2,481.10 1,040.00 43.40 122.70 630.50 96.60 96.40 80.80 116.90 145.20 78.30 4.10 7.60 0.90 71.50 5,016.80
2002-2003
2,656.20 1,110.00 44.40 126.40 663.20 98.30 104.10 80.90 120.30 146.70 80.60 4.30 7.60 0.90 71.40 5,315.00
2003-2004
2,882.50 1,193.10 47.80 132.40 722.70 100.40 112.60 81.00 121.30 149.20 84.40 4.40 7.60 0.90 71.30 5,711.20
2004-2005
3,063.00 1,264.70 51.80 140.50 778.70 102.40 120.30 81.30 121.90 151.80 87.60 4.50 7.70 0.90 69.40 6,048.30
July-March 2005-2006*
3,624.00 1,445.50 62.50 140.70 812.10 103.30 121.70 78.60 138.30 151.80 92.10 4.50 7.70 0.90 62.60 6,845.60
57
*: Estimated (000 Number) Source: National transport research center
57
Table 4.2: Crankcase size of different vehicles
Type of Vehicles Crankcase (litres )
Motor cycle 01
Motor car 4
Car 6
Jeep 6
Pickup 6
Ambulance 6
Station Wagon 6
Delivery Van 6
Motor Cabs/Taxi 6
Bus 14
Oil Tankers 13
Water Tanker 13
Trucks 13
Tractor 14
Trailer 16,20,24
Source (Automobile catalogues)
58
Table 4.3: Oil change interval
Type of vehicles Oil change interval (km)
Motor cycle 800~1000
Motor car 3000
Car 3000
Jeep 3000
Pickup 3000
Ambulance 3000
Station Wagon 3000
Delivery Van 3000
Motor Cabs/Taxi 3000
Bus 3000,5000
Oil Tankers 5000
Water Tanker 5000
Trucks 5000
Tractor 5000
Trailer 5000
Source (Field survey/Automobile catalogue)
59
Table 4.4: Number of time oil change per year
Number oil change
Vehicle category Half month
(a)
One months
(b)
Two months
(c)
One year (number
of times) (c)
Motor Cycle - - 12
Car - - 12
LCV(Motor Car) - - 12
Jeep - - 12
Pickups - - 24
Motor Cab Taxis - - 24
Ambulance - - 24
Station Wagon - - 24
Delivery Van - - 24
Bus - - 24
Oil Tanker - - 24
Water tanker - - 24
Truck - - 24
Trailer - - 24
Farm Tractors - - 24
Source (Field Survey) 4.2.6 Engine oil consumption
In automobile engines, lubricating oil is used to lubricate the engine components to
protect the load bearing and internal moving parts from wear including, pistons and
piston rings. During operation, the engine cylinder wall acquires heat from the
combustion and burns the oil reducing quantity.
60
4.2.7 Quantification of used oil
The data collected through the field survey and questionnaires results was analyzed.
Based on the results obtained, Equations (4.1-4.4) were developed to estimate the new oil
used and waste oil produced. The equations would help to forecast the vehicle waste oil if
the number of vehicles are known.
New oil use for single service axbc = (4.1)
e
(4.4)
Where,
=a Total number of vehicle, and
= Crankcase size/Chamber sizb
Total number times the waste oil replaced by new oil per year
cxde = (4.2)
Where,
=Number of new oil change per yeard
Total oil burnt in engine per year
bef /= (4.3)
Total waste oil generated in year
fe −= g
The data collected from the field survey reveals that generators of vehicle waste oils are
drivers and get the oil changed of their vehicles in repair shops and service stations, do-it-
your self is rarely in case farm tractor. All data collected through field survey and
questionnaires results were taken to analytical average consideration. Based on the results
obtained, Equations (4.1-4.4) were developed to estimate the new oil used and waste oil
produced. The level of used oil generation was quantified base on the total vehicle
61
registered in the country from June 1990 to March 2006 tabulated in Table 4.5. The total
used oil estimated in the year 2005 to 2006 is around 274,177 tones. Table 4.6 shows the
new oil v/s waste oil generated in years 1990 to march 2006 and same has been presented
in graph as shown in Figure 4.1.
0
50
100
150
200
250
300
350
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
New Oil Vs Waste Oil
Oil
in T
ones
(00
0)
Waste Oil New Oil
New Oil Vs Waste
Oil
in T
ones
(000
)
Waste Oil New Oil
Fig. 4.1: New oil v/s waste oil generated in years 1990 to march 2006
62
Table 4.5: Vehicle waste oil generation
New oil use (Liters) Status of oil in engine (Liters)
Types of vehicles
Total No. of
vehicles a
Crank case size
(Liter) b
Single service
axbc =
No. of oil
change n year
d
Oil use in year
cxde =
Oil consumed at 800 3200 KM (0.25 &
0.945 liters in year)
xb)/efconsumed
Used oil generated
in year feg −=
Motor cycle
3624000 1 3624000 12 43488000 10872000 32616000
Rickshaw 78600 Two stroke
- - - - -
Motor car 1445100 4 5780400 9 52023600 12290575 39733024 Car 755863 6 4535178 10 45351780 7142905 38208875 Jeep 62500 6 375000 9 3375000 531562 2843437 Pickup 92100 6 552600 9 4973400 783311 4190089 Ambulance 4500 6 27000 9 243000 38272 204727 Station wagon
140700 6 844200 9 7597800 1196653 6401147
D. van 138300 6 829800 9 7468200 1176241 6291959 Motor caps / taxi
121700 4 486800 12 5841600 1380078 4461522
Bus 103300 13 1342900 18 24172200 1757133 22415067 Oil Tanker 7700 13 100100 18 1801800 130977 1670823 Water Tanker
900 13 11700 18 210600 15309 195291
Truck 151800 13 1973400 18 35521200 2582118 32939082 Tractor 812100 14 11369400 12 136432800 9209214 127223586 Trailer 1109 24 26616 20 532320 20961 511359 Others 62600 - 264663 - 3063746 407859 2655877 Total 7062872 - 32143757 - 372097046 49535168 322561865
(= oil
63
Table 4.6: New oil v/s waste oil generated
S No.
Year Total vehicles on road
New oil used (liters)
New oil used
(tones)
Oil consumed in
engines (liters)
Waste oil generated
(liters)
Waste oil generated
(tones)
01. 1990 2,712,837 102,231,982 86,897 17,225,259 85,006,723 72,255
02. 1991 20,955,00 114,529,161 97,350 13,962,660 100,566,501 85,481
03. 1992 2,560,498 144,507,524 122,831 17,074,274 127,433,250 108,318
04. 1993 2,829,541 157,735,477 134,075 18,964,956 138,770,521 117,955
05. 1994 3,121,188 170,386,519 144,829 20,701,205 149,685,314 127,233
06. 1995 3,237,181 180,811,070 153,689 21,810,955 159,000,115 135,150
07. 1996 3,435,538 190,628,052 162,033 22,974,056 167,653,996 142,506
08. 1997 3,679,459 203,009,183 172,558 24,642,581 178,366,602 151,611
09. 1998 3,977,859 217,781,018 185,114 27,269,938 190,511,080 161,934
10. 1999 4,352,954 235,971,672 200,576 29,394,637 206,577,035 175,590
11. 2000 4,863,977 257,956,695 219,263 32,573,706 225,382,989 191,576
12. 2001 5,471,074 287,425,121 244,311 36,692,250 250,732,871 213,123
13. 2002 5,833,389 303,015,453 257,563 31,040,090 271,975,363 231,179
14. 2003 6,329,076 326,965,094 277,920 42,363,524 284,601,570 241,911
15. 2004 6,729,831 347,283,610 295,191 44,996,239 302,287,371 256,944
16 2005 to
March 2006
7,602,872 372,097,046 316,283 49,535,168 322,561,878 274,177
64
4.2.8 Used oil collection and transportation
The safest and most reliable ways of collection and transportation of used oil has been
proposed to maximize its economic value and minimize pollution. In this proposed oil
collection system, repair garages, workshops, commercial fleet operators, shade tree
mechanics, service stations, quick lube centers and oil dealers have been declared as a
collection points. The certified collection centers are based on population and, in case of
urban areas one certified collection center to a population of 100,000 people and it should
not near residential areas because of access for heavy trucks. In rural areas certified
collection centers shall be based on an area off 3 Km diameter. Collection centers will be
legally authorized by the Government to collect the used oil and no other private party (s)
would be allowed to collect the used oil from the collection points. The used oil
collection net work is shown in Figure 4.2. Light trucks would be suitable to pass from
thickly populated areas and the use of 55 gallons oil collection container/drum would
easily handle the oil for transportation and also prevent the used oil from the dirt, water
and other contamination. Introducing pickup vehicles for used oil collection in place of
donkey cart would speedup the oil collection system. The use of a vacuum pump oil
tanker would easily to transfer the used oil and minimize the chance of oil leakage as
shown in Appendix C.
65
Fig. 4.2: Proposed used oil collection net work.
4.2.9 Proposed used oil re-generation locations
The selection of re-generations location is shown in Figure ____made based on good
road net works connecting all major cities with potential markets, the major used oil
generators and lubricant oil consumers. Considering population, importance of the area
from a business point of view, these locations would reduce the transportation cost of
used and refined oil and also provide job opportunities to the local people. The approach
used in prosing re-generation locations in this study is a more detailed version of that
suggested by (EL-Fadel and Khouy 2001) has also reported that at least 14 used oil
reprocessing locations are operating in Michigan.
66
Prop
osed
reg
ener
atio
n L
ocat
ions
in P
akis
tan
67
4.3 MATERIALS
Spent lubricant oil was collected from a local automobile workshop and was
homogenized in a container before oil characterization and treatment where the acids,
solvents, ketones, organics hydrocarbons and fuller’s earth was purchased from Faisal
Traders kachi-galli, bunder road Karachi.
4.4 ANALYSIS AND TEST METHODS
Test methods, used for analyzing the oil samples to evaluate their properties were carried
out according to the standard methods as shown in Table 4.7.
Table 4.7: Standard lubricating oil testing methods
Test Designation Apparatus
Kinematics viscosity ASTM D-455 Saybolt Universal Viscometer
Specific gravity ASTM D-1298 Hydrometer
Density ASTM D-1298 Hydrometer
Flash point ASTM D-92 Pensky- Marten closed cup tester
Pour point ASTM D-97 Cloud & Pour Point Tester
Color ASTM D-1500 ASTM Color Scale
68
4.5 LABORATORY SCALE EXPERIMENTAL WORK The laboratory experimental work was divided into two processes acid/clay treatment and
solvent extraction treatment, both these re-refining process are used commercially.
Experimental work was carried out in petroleum refinery laboratory in Institute of
Petroleum & Natural Gas Engineering, Mehran University of Engineering &Technology
(MUET) Jamshoro.
4.5.1 Properties of used lubricating oil
The standard physical property tests of used lubricant oil sample were carried out at the
Hydrocarbon Development Institute of Pakistan laboratory at Karachi to evaluate the
nature and extent of the contaminants, the test results are shown in the test report (used
oil) Appendix E.
4.5.2 Dehydration of used oil (Experiment No. 1)
The dehydration was performed in a simple vacuum distillation where water and gasoline
fractions were separated. All laboratory scale experiments were performed in the quickfit
glassware with proper fittings with vacuum pressure to 600mmHg. In 300 ml of used oil
taken in a still pot and weighed. The weighed was oil was heated. During the heating,
water bubbles appeared indicating expulsion of water and light hydrocarbons. Distillation
was carried out until no further distillate was produced. Replicate experiments were
conducted for the dehydration of used oil using vacuum distillation. The dehydrated oil
was weighed again and its physical properties determined using ASTM standard given in
Table 5.1
69
4.5.3 Acid-clay treatment
4.5.3.1 Experiment No.1
Chemicals
• Sulphuric acid (98% concentrate)
• Fuller’s Earth
300 ml (about 270 g), the dehydrated used oil was used for each experiment. Sulphuric
acid (98% concentrate) was mixed to 3, 3.5 and 4 percent by volume of dehydrated used
oil. In addition, diesel fuel was added as per requirement to dilute the thick used oil. The
mixture was then heated to 80 oC with continuous mixing action at a vacuum pressure of
600 mm Hg., after 30 minutes mixing was discontinued and the oil was allowed to settle
for 24 hours in order to separate the extract phase (acid and dissolved oil base), from the
raffinate phase (contaminants or sludge).Separation of the two phases was carried out in a
liter separating funnel and the remaining layer of diesel and oil was collected without
disturbing a some what waxy, semisolid phase formed at the bottom of the vessel. The
collected oil (oil and diesel) was further neutralized by activated fuller’s earth absorbent
at different operating variables. Absorbent removed the residual sludge and the diesel as
removed by distillation. Oil collected was filtered (Whattman Ashless 125 mmΦ) and
weighed. This re-refining process was run three times using three different sets of process
variables to study their effects on re-generation properties. Table 4.8 lists these selected
process variables for different runs. For each run, re-generated base oil was collected and
analyzed. ASTM standard methods were used to determine various properties of the base
oil shown in Table 5.2
70
Table 4.8: Process variables of acid clay treatment
Process variables
1st Run 2nd Run 3rd Run
• Sulfuric acid to waste oil (Dehydrated) (vol %)
• Diesel for dilution of waste oil as per requirement
3 :1
3.5:1
4 :1
Stirred at 275 rpm, mixing time (min)
30 30 30
Heating temperature 0C
80 80 80
Heating time (min)
15~ 30 15~ 30 15~ 30
Distillation pressure (mm Hg) 500 550
600
Gravitational settling time (h) 24
24 24
Yield after acid action by (vol %) 55
58 61
Fuller Earth (Wt gm %) to (Vol ml%) of oil
3:1 3.5:1 4:1
Distillation temperature 0C
150 200 250
Distillation Time (h)
1.5 2 3
Distillation column pressure (mm Hg) 500 550
600
Oil Recovery % 40
41 43
71
4.5.3.2 Experiment No.2 Chemicals
• Sulphuric acid (98% concentrate)
• Nitric Acid (70%)
• Dimethyl Sulfoxide
• Fuller’s Earth
In this laboratory experimental work the same experimental setup was used as in
experiment No.1. 300 ml of dehydrated used oil was taken for each experiment and
premixed with a treating agent comprising 70 percent by volume of 70 percent nitric acid
and 30 percent by volume of 98 percent sulfuric acid. To further treat the oil, addition of
0.6 % by vol: %to pre mixed dimethyl sulfoxide was used; the mixed acid is provided in
an amount equal to 3, 3.5 and 4 percent by volume of the waste oil. In addition diesel was
added as per requirement to dilute the thick used oil. This premixed acid treating reagent
is thoroughly dispersed in the oil by a high shear mixing operation, and then heated 80 oC
with continuo mixing action at a vacuum pressure of 600 mmHg. After 30 min mixing
was discontinued and the oil was allowed to settle for 24 hours. The mix was drawn off
from the top of the reaction vessel and remaining layer of diesel and oil was collected
without disturbing a flocculent, some what waxy, semisolid phase formed at the bottom
of the vessel. The collected mixed oil (oil and diesel) was further neutralized by fuller’s
earth absorbent in the ratio (3, 3.5, and 4) % at different operating variables. The
absorbent removed residual sludge where as the diesel was removed by distillation. Oil
was filtered (Whattman Ashless filter paper 125 mmΦ) and weighed base oil recovery
was to be between 40 and 45 %. This re-refining process was run three times using three
different sets of process variables to study their effects on re-generation (Table 4.9). For
each run, re-generated base oil was collected and analyzed. ASTM standard methods
were used to determine various properties are shown in Table 5.3.
72
Table 4.9: Process variables of acid clay treatment
Process variables
1st Run 2nd Run 3 rd Run
• Pre mixed (Nitric Acid 1 part by wt with 2 parts Sulfuric acid)
• Catalyst dimethyl sulfoxide added 0.6 % by Vol: %to pre mixed
• Diesel for dilution of waste oil as per requirement
• Used oil (Dehydrated)
Acid waste oil ratio 3:1
Acid waste oil ratio 3.5:1
Acid waste oil ratio 4:1
Stirred at 275 rpm, mixing time (min)
30 30 30
Heating temperature oC
80 80 80
Heating time (min)
15~ 30 15~ 30 15~ 30
Distillation pressure (mm Hg) 500 550
600
Gravitational settling time (h) 24
24 24
Yield after acid action by (Vol %) 59
60 60
Full (Wt gm %) to (Vol ml%) of oil
3:1 3.5:1 4:1
Distillation temperature oC
150 200 250
Distillation column pressure (mm Hg) 500 550
600
Distillation Time (h)
1.5 2 3
Oil Recovery % 41
41 45
73
4.5.3. 3 Experiment No. 3
Chemicals
• Sulphuric acid (98% concentrate)
• Nitric Acid (70%)
• Dimethyl Formamide
• Fuller’s Earth
In this laboratory experimental work the same experimental setup was used as in
experiment No.3. 100 ml of dehydrated used oil was taken for each experiment and
premixed with a treating agent comprising 70 percent by volume of 70 percent nitric acid
and 30 percent by volume of 98 percent sulfuric acid. To further treat the oil, addition of
0.6 % by vol: %to pre mixed dimethyl formamide was used; the mixed acid is provided
in an amount equal to 3, 3.5 and 4 percent by volume of the waste oil. In addition diesel
was added as per requirement to dilute the thick used oil. This premixed acid treating
reagent is thoroughly dispersed in the oil by a high shear mixing operation, and then
heated 80 oC with contineuo mixing action at a vacuum pressure of 600 mmHg. After 30
min mixing was discontinued and the oil was allowed to settle for 24 hours. The mix was
drawn off from the top of the reaction vessel and remaining layer of diesel and oil was
collected without disturbing a flocculent, some what waxy, semisolid phase formed at the
bottom of the vessel. The collected mixed oil (oil and diesel) was further neutralized by
fuller’s earth absorbent in the ratio (3, 3.5, and 4) % at different operating variables. The
absorbent removed residual sludge where as the diesel was removed by distillation. Oil
was filtered (Whattman Ashless filter paper 125 mmΦ) and weighed base oil recovery
was to be between 40 and 45 %. This re-refining process was run three times using three
different sets of process variables to study their effects on re-generation (Table 4.10). For
each run, re-generated base oil was collected and analyzed. ASTM standard methods
were used to determine various properties are shown in Table 5.4
74
Table 4.10: Process variables of acid clay treatment
Process variables
1st Run 2nd Run 3rdRun
• Pre mixed (Nitric Acid 1 part by wt with 2 parts Sulfuric acid)
• Catalyst dimethyl formamide added 0.6 % by vol: %to pre mixed
• Diesel for dilution of waste oil as per requirement
Aicd waste oil ratio 3:1
Aicd waste oil ratio 3:5: 1
Aicd waste oil ratio 4:1
Stirred at 275 rpm, mixing time (min)
30 30 30
Heating temperature oC
80 80 80
Heating time (min)
15~ 30 15~ 30 15~ 30
Distillation pressure (mm Hg) 500 550
600
Gravitational settling time (h) 24
24 24
Yield after acid action by (vol %) 59
60 63
Full (Wt %) to (Vol%) of oil
3% 3.5% 4%
Distillation temperature oC
150 200 250
Distillation column pressure (mm Hg) 500 550
600
Distillation Time (h)
1.5 2 3
Oil Recovery % 41
41 45
75
4.5.3. 4 Experiment No. 4
Chemicals
• Sulphuric acid (98% concentrate)
• Zeolite
• Fuller’s earth
In this treatment process, zeolite was used as catalyst. A laboratory scale experimental
was established as shown in Figure 4.4. 100 ml (about 90g) of dehydrated used oil was
taken in 100 ml (about 90g) used for each experiment. Zeolite catalyst was used at 8g/L,
12g/L and 18g/L and mixed thoroughly with the oil by a high shear mixing operation.
The piepood waste oil was treated to different operating variables. Catalytic cracking of
waste oil took place at a temperature 180 oC, 160 oC and 140 oC with vacuum pressure of
600 mm Hg and the duration was 3 hours. The oil was then washed with water to remove
carbon particles and then heated at 140oC at 600 mmHg for 1 hour to remove residual
free and emulsified water. The dehydrated oil was then cooled to 30 oC and treated with
98 % commercial grade sulfuric acid (3, 3.5 and 4) % for 30 minutes and allowed to
settle for 24 hours for deasphalting and settling of acid sludge (Table 4.11). The decanted
oil was mixed with fuller’s clay before injection into the high temperature vessel. Oil was
then injected to a vacuum distillation unit. The Light friction was collected as re-refined
base oil and recovery found in between 44 and 49 % .This re-refining process was run
three times using three different sets of process variables. For each run, re-generated base
oil was collected and analyzed using ASTM standard methods shown in Table 5.5.
76
Fig. 4.4: Waste oil re-refining process used catalyst zeolite
77
Table 4.11: Process variables of acid clay treatment
Process variables
1st Run 2nd Run 3 rd Run
Catalyst waste oil ratio (g/l) 8.0 12.0 18.0
Stirred at 275 rpm, mixing time (min)
30 30 30
Cracking temperature oC
180 160 140
Cracking time (h) 3 3 3
Sulfuric Acid (98concentration) Vol%
4 3.5 3
Fuller’s Earth (Wt gm %) to (Vol)
5 4 3.5
Distillation temperature oC
250 250 250
Distillation column pressure(mm Hg) 500 550 600
Distillation time (h)
2 2.5 3
Oil Recovery % 45
46 49
78
4.6 SOLVENT EXTRACTION TREATMENT
In a solvent extraction process base oil is extracted using various selective solvents,
either composite or single solvent producing useful organic sludge instead of toxic acid
sludge, this process replace the classic acid-clay treatment successfully that generated
toxic acid sludge, produced by the classic acid clay treatment. This solvent extraction
process (SEP) requires the correct type of solvent (s), extraction parameters (temperature,
pressure, etc.), and solvent: oil ratio. This is one of the more efficient processes,
separating the maximum amount of sludge particles from used oil and also minimizes
base oil losses. Laboratory scale experimental work was carried out in into two parts
performance of the solvents and re-refining of the base oil from used lubricant oil.
4.6.1 Solvents
Performance of ccommercial grade solvents, (n-hexane, Methyl-Ethyl- Keton, 1-Butanol,
2- Propanol, 1- hexanol) were investigated in this study.
4.6.2 Determining an Effective Solvent Extraction Parameters
A laboratory scale (glassware) setup was made in the petroleum refinery laboratory,
Insititute of Petroleum and Natural Gas Engineering, MUET, Jamshoro as shown in
Figure 4.6. In this study, waste crankcase lubricating oil from internal combustion
engines was used as test sample and samples were collected from different service
stations and local garages from Karachi and Hyderabad and mixed in a container to
represent a mix feed stock to a re-refiney plant for recycling, therefore waste crankcase
lubricating oils were collected from different areas and locations. The used lubricating oil
mixture was kept in a closed drum of 25 l and was homogenised prior to any testing.
79
Fig. 4.5: Waste oil re-refining process by solvent extraction process
Solvent extraction process
ple 30 gm (Woil) was mixed with the solvent (Wsol) at a
C. The used oil sample was stirred at 275-
ixing in the flask with no oil losses. The
bath tem ixture under gravity.
Subsequent to settling, black sludge particles were clearly observed in the bottom of the
eters were studies from the experiment.
Percent Sludge Removal (P.S.R.)
dry
The wet sludge (Wwet) was separated from the solvent-oil mixture and then soaked in
4.6.3
In conical flask used oil sam
specified ratios given in table, to evaluate the extraction performance of these solvents at
three extraction temperatures, 20, 30 and 50 o
300 rpm for 30 min, just to ensure sufficient m
perature was maintained at left for 24 hours to settle the m
flask. The following param
4.6.3.1
The percent sludge removal represents the weight of dry sludge (W ) in gram/kilogram.
80
solvent and left for 12 h of gravity settling as suggested by (Reis and Jernimo,1988). The
solvent solution was separated and the sludge was heated at 100 oC in an oven for 30
minutes and the dry). The PSR
was calcu
xwoildryxPSR ………… (4.5)
4.6.3.2 Percentage Oil Loss (POL)
Percentage oil lo defined as the loss o the sludge during SE rocess, in mass.
Thus, POL was lated by equation (ii)
…………. (4.6)
4.6.3.3 Performance of solvent 1-butanol (Experiment No.1)
In this study, the solvent, 1- butanol was used with used lubricating oil (Reis and
Jernimo, 1988) to measure the oil losses and sludge removal percent at different
temperatures to get the study objective and the results are given in Tables 4.12, 4.13 and
4.14.
Table 4.12: Oil losses percent using 1-butanol at 20 oC
Solvent 1-utanol at 20oC
n cooled to room temperature and weighed dry sludge (W
lated as follows:
(W=
ss is f oil to P p
calcu .
%100)/
%100)/( xWoilWdryWwetPOL −=
Solvent oil ratio Percent sludge removal Percent oil losses
1:1 3.5 17.9
2:1 8.8 12.1
3:1 10.4 12
4:1 10.8 12
5:1 11.2 12
6:1 12.3 12
7:1 12.3 12
81
Table 4.13: Oil losses percent using 1-butanol at 30 oC
Solvent 1-butanol at 30oC Solvent oil ratio
Percent sludge removal Percent oil losses
1:1 4.3 15.11
2:1 9.3 11.10
3:1 10.7 10.8
4:1 11.2 10.8
5:1 11.7 10.9
6:1 12.9 10.9
7:1 12.9 10.9
Table 4.14: Oil losses percent using 1-butanol at 50 oC
Solvent 1-butanol at 50oC Solvent oil ratio
Percent sludge removal Percent oil losses
1:1 4.7 13
2:1 10.9 11
3:1 12.8 10.7
4:1 13.4 10.5
5:1 13.9 10.5
6:1 15.3 10.5
7:1 15.3 10.5
82
4.6.3.4 Performance of solvent 2-propanol (Experiment No.2)
In this study, solvent 2-propanol was used with used lubricating oil. The systematic
approach, as described by (Reis and Jeronimo, 1988) was used to measure the oil losses
and sludge removal percent at different temperatures to get the study objective and the
results tabulated in Table 4.15, 4.16 and 4.17.
Table 4.15: Oil losses percent using 2-propanol at 20 oC
Solvent 2-propanol at 20oC Solvent oil ratio
Percent sludge removal Percent oil losses
1:1 3.2 15.6
2:1 6.7 11.7
3:1 8.9 9.91
4:1 9.5 9.8
5:1 10.3 9.8
6:1 11.6 9.8
7:1 11.6 9.8
Table 4.16: Oil losses percent using 2-propanol at 30 oC
Solvent 2-propanol at 30oC Solvent oil ratio
Percent sludge removal Percent oil losses
1:1 3.8 14.5
2:1 8.6 12.4
3:1 9.8 11.5
4:1 10.7 11.3
5:1 11.4 11.3
6:1 11.9 11.3
7:1 11.9 11.3
83
Table 4.17: Oil losses percent using 2-propanol at 50 oC
Solvent 2-propanol at 50 oC Solvent oil ratio Percent sludge removal Percent oil losses
1:1 4.2 15
2:1 9.7 12
3:1 10.3 11.2
4:1 11.2 11
5:1 12.4 11
6:1 12.8 11
7:1 12.8 11
4.6.3.5 Performance of MEK (Experiment No.3)
In this study, catalyst Methyl Ethyl Ketone was used with used lubricating oil, more
systematic approach was used as ascribed by (Reis and Jeronimo, 1988) to measure the
oil losses and sludge removal percent at different temperatures to get the study objective
and results tabulated in Table 4.18, 4.19 and 4.20.
Table 4.18: Oil losses percent using MEK at 20 oC
Ketone MEK at 20oC Solvent oil ratio Percent sludge removal percent oil losses
2:1 3.2 14.5
3:1 7.2 13.2
4:1 8.7 12.4
5:1 9.4 10.2
6:1 10.6 10.2
7:1 10.6 10.2
84
Table 4.19: Oil losses percent using MEK at 30 oC
Ketone MEK at 30oC Solvent oil ratio Percent sludge removal Percent oil losses
2:1 2.9 15
3:1 6.2 13.5
4:1 7.8 12.9
5:1 8.3 9.8
6:1 9.6 9.4
7:1 9.6 9.4
Table 4.20: Oil losses percent using MEK at 50 oC
Ketone MEK at 50oC Solvent oil ratio Percent sludge removal Percent oil losses
2:1 2.5 15
3:1 5.4 11.6
4:1 7.2 10.3
5:1 7.8 9.3
6:1 8.2 8.2
7:1 8.2 8.2
4.6.3.6 Experiment No.4
Solvent
• 2- Propanol
• n-hexane
• Potassium Hydroxide (KOH)
In this study, test samples were taken from waste crankcase lubricating oil of internal
combustion engines. The oil was collected from several local garages and service stations
and mixed in a container. The experimental setup was conducted on a laboratory scale; a
sample was placed in a beaker and allowed to settle at room temperature for 24 hours.
The waste oil was collected and mixed with a composite solvent (70% of 2-propanol and
85
30% of n-hexane) with specific amount of potassium hydroxide (KOH) and stirred
thoroughly for 30 minutes. The mixture was then heated at 60 oC for 30 minutes at
atmospheric pressure to remove light hydrocarbons and left for 24 to settle
In this experimental, the solvent to oil ratio varied 2:1 to 6:1, while KOH amount was
varied from 0 to 6 g KOH/L solvent. Tables 4.21 list the selected process variables for
different runs the oil/solvent mixture was separated from the sludge and heated at 120 oC,
under vacuum to remove the solvent. Fuller’s earth was mixed with the oil and heated at
150 oC to 250 oC for 3 hours. The temperature of the oil was then reduced to 120 oC and
filtered using whattman No.41 size of 125 mm ф paper. Selected physical properties flash
point, pour point, density, and kinematics viscosity test conducted using American
Society for Testing and Material (ASTM) methods to characterize the oil properties as
shown in Table.5.6
Sludge optimization followed the procedure of as suggested by (Reis, and Jeronimo,
1988). The trapped oil in the sludge was expelled using a solution of 30% n-hexane and
70% 2-propanol heated in an oven at 100 oC left for 24 hours so that remaining solvent in
the sludge evaporated and the residual sludge was labeled as dry sludge. PSR and POL
was calculated shown in Table 4.22.
86
Table 4.21: Process parameters of solvent extraction
Process parameters 1st Run 2nd Run 3 rd Run
• Solvent (70% of 2-propanol and 30% of n-hexane)
• 3g KOH • Solvent oil mixture (6:1) (ml)
500 500 500
Fuller’s Earth (wt %) to (vol %) 3
3.5 4
Distillation temperature oC 150 200 250
Distillation pressure ( mm Hg) 500 550
600
Distillation time (h)
1.5 2 3
Gravitational settling time (h) 24
24 24
Oil Recovery % 57
61 63
87
Table 4.22: Optimum Solvent Oil Ratio and Amount of KOH
Percent of sludge removal Percent of oil loss (%)
Solvent-to-oil ratio Solvent –to-oil ratio
KOH
(g/500ml
solvent) 2:1 3:1 4:1 5:1 6:1 2:1 3:1 4:1 5:1 6:1
0 7.25 8.43 9.18 10.10 11.05 13.22 11.45 11.19 10.13 9.87
1 8.95 9.84 10.35 11.58 12.56 12.55 11.12 10.23 9.65 9.11
2 10.48 11.62 12.78 13.59 14.65 11.05 9.92 9.14 8.96 8.70
3 12.64 13.90 14.99 15.98 17.00 9.88 8.87 8.12 8.04 8.09
4 12.70 13.24 14.70 15.22 16.25 9.88 9.02 8.26 8.10 8.17
5 12.16 12.88 14.06 14.60 15.15 10.32 9.32 8.85 8.16 8.26
6 10.05 10.45 11.83 12.32 13.10 12.64 13.90 14.99 15.98 17.00
4.6.3.7 Sedimentation
Sedimentation was determined using 2cm diameter tubes. The tubes were filled with 40 g
of solvent, 10 g of waste oil and KOH in the desired proportions. The mixture was then
strongly agitated and tubes were inverted 30 times to promote flocculation by velocity
gradients. The height of the settling was measured every 30 seconds and had almost
finished within 40 minutes as shown in Figure 5.37.
4.6.3.8 Experiment No.5
Solvents
• 2-propanol
• butanol
• butanone
• Fuller’s Earth
In this experiment, the earlier laboratory experimental setup was modified as per
requirement. Used oil was collected from different local garages and service stations
from Garikhata Hyderabad and mixed in single container. The oil sample was mixed with
composite solvents contain 40% 2-propanol, 35% 1-butanol and 25% butanone.
88
The solvent-to-oil ratio was varied 2:1 to 6:1; the mixture was stirred rigorously for 15
minutes and then heated at 60 oC for 30 minutes at atmospheric pressure to remove light
hydrocarbons and left for 24 hours natural settlement. The solvent oil mixture then
removed (Table 4.23). The extracted solvent oil mixture was heated to 120 oC, under
vacuum and the solvent separated solvent from the oil. Fuller’s earth was mixed with the
recovered oil heated at different operating variables. The temperature of the oil was then
reduced to 120 oC, and the oil filtered Whitman No.41 size 125 mm ф paper (Table 4.24).
American Society for Testing and Material (ASTM) methods were used to characterize
the oil properties as shown in Table 5.7. For optimum solvent oil ratio, experimental
work was conducted with other composition (Composite solvent 25% 2-propanol, 37% 1-
butanol and 38% butanone) and the same process was applied as shown in Table 4.25 and
4.26. The physical properties of the received oil are shown in Table 5.8.
Table 4.23: Optimum solvent oil ratio and amount of sludge removal
Sludge removal
Oil loss
Extracted solvent/oil mixture
Solvent-
to-
oil ratio
Oil (g)
Solvent (g)
Extract solvent/oil
mixture (g)
Affinate (g)
Sludge (g)
Oil (g)
Solvent (g)
loss (g)
2:1 50.42
100.21 137.71 12.92 11.52 36.52
99.32 1.87
3:1
50.25 150.31 187.05 13.51 11.97 36.01
149.37
1.67
4:1
50.50 200.19 236.57 14.12 12.36 35.65
199.34
1.58
5:1
50.35 250.16 286.07 14.44 12.64 35.34
249.26
1.47
6:1
50.14 300.17 335.76 14.55 12.86 35.10
299.33
1.33
7:1
50.12 350.16 385.95 14.33 12.53 35.29
349.24
1.42
8:1
50.14 400.17 436.34 13.97 12.17 35.54 399.29 1.53
(Composite solvent 40% 2-propanol, 35% 1-butanol and 25% butanone and used oil)
89
Table 4.24: Process variables of Solvent Extraction
(Composite solvent 40% 2-propanol, 35% 1-butanol and 25% butanone and used oil)
Process variables
1st Run
2nd Run
3 rd Run
Solvent oil mixture (6:1) (ml)
500 500 500
Fuller’s Earth (wt %) to (vol %) 3
3.5 4
Distillation temperature oC 150 200 250
Distillation pressure mm Hg 500 550
600
Distillation time (h)
1.5 2 3
Gravitational settling time (h) 24
24 24
Oil Recovery % 56
61 65
4.6.3.9 Sedimentation
Sedimentation is a process where particles settle under the action of gravity. This was
determined by using 2 cm diameter tubes. The tubes are filled with solvent (40% 2-
propanol, 35% Butanol and 25% butanone) and used oil in a ratio of 6:1. The tubes were
strongly agitated and inverted 30 times to promote flocculation by velocity gradients.
Every 30 seconds the height of settling is measured and had almost finished within 40
minutes as shown in Figure 5.42.
90
4.6.3.10 Experiment No. 6
Chemicals
• 2-propanol
• butanol
• butanone
• Fuller’s Earth
In this experiment, the same treatment procedure was used that is used in experiment 5
and results tabulated in Table 4.25 and 4.26.
Table 4.25: Optimum solvent oil ratio and amount of sludge removal
Sludge
Oil
Extracted solvent/oil
Solvent-
to-
oil ratio
Oil (g)
Solvent (g)
Extract solvent/oil
mixture (g)
Affinate (g)
Sludge (g)
Oil (g)
Solvent (g)
loss (g)
2:1 50.10
100.11 131.80 18.83 12.94 35.39
99.35 1.49
3:1
50.15 150.16 181.11 19.45 13.48 34.81
149.47
1.32
4:1
50.13 200.10 228.76 21.93
13.94 34.67
199.36
1.3
5:1
50.16 250.13 275.73 24.78 14.27 34.28
249.28
1.22
6:1
50.10 300.18 323.75 26.85 14.54 33.97
299.34
1.10
7:1
50.12 350.12 379.89 20.39
14.10 34.17
349.3
1.18
8:1
50.17 400.15 430.83 19.48 13.65 34.44 399.32 1.27
(Composite solvent 25% 2-propanol, 37% 1-butanol and 38% butanone and used oil)
91
Table 4.26: Process variables of Solvent Extraction
(Composite solvent 25% 2-propanol, 37% 1-butanol and 38% butanone and used oil)
Process Variables
1st Run
2 nd Run
3 rd Run
Solvent oil mixture (6:1) (ml)
500 500 500
Fuller’s Earth (wt %) to (vol %) 3
3.5 4
Distillation temperature o C
150 200 250
Distillation pressure mm Hg 500 550
600
Distillation time (h)
1.5 2 3
Gravitational settling time (h) 24
24 24
Oil Recovery % 58
62 68
4.6.3.11 Sedimentation
The same experiment procedure was repeated for solvent (25% 2-propanol, 37% 1-
butanol and 38% butanone) oil ratio 6:1, sedimentation result shows that the complete
settlement taken place at 1 cm in 30 minutes time. When compared with previous results
it was found that more settlement taken place in a short time with a solvent (25% 2-
propanol, 37% 1-butanol and 38% butanone) at oil ratio 6:1as shown in Figure 5.43.
92
4.7 EXPERIMENTAL RIG DESIGN AND FABRICATION
The experimental pilot scale rig was designed and fabricated on batch system and its
operation was similar to laboratory work where the used lubricating oil was treated. This
pilot scale rig was installed in the Department of Mechanical Engineering, MUET,
Jamshoro. It was fabricated in stainless steel with brass and copper fittings equipped with
safety equipment and 2 liters of used oil was treated per run. Various technologies were
studies while designing and fabrication of pilot scale rig, like Meinken Technology, KTI
technology (Kinetics Technology International), Mohawk technology, BERC or NIPER
technology (Bartlesville Energy Research Center USA, renamed the National Institute of
Petroleum and Energy Research ) and PROP Technology (Phillips Petrol Company).
This pilot scale rig was developed from Mohawk Technology and KTI Technology for
acid clay treatment and BERC or NIPER technology, PROP technology, based on
treating used oil with sulphuric acid or solvent to eliminate the polluting substances and
then treatment with clay earth instead of hydrogenation to neutralize the resultant product
and improve the color and odour of the oil. Working process of this pilot rig is similar to
Mohawk and KTI process both high, efficiency re-refining technologies. In the first
stage, the process removes water from the used oil (feedstock), in second stage, the
process goes for distillation to remove light hydrocarbons and in the third stage, as
evaporation process vaporizes the base oil, so separating the base oil from the additives
and leaving behind a residue (sludge). The final processing stage is fuller’s earth
treatment that absorbs basic colors and results in high-quality base oil. This fabricated rig
work on batch operation, for longer catalyst life span, reduced corrosion and low
maintenance. Vacuum was produced mechanically to reduce the quantity of waste water.
The experimental work was repeated on a pilot scale rig shown in appendix D where the
spent lubricant oil was treated within the same manner as in the laboratory work and has
the following basic process steps:
93
• Pretreatment
• Atmospheric distillation
• Vacuum Distillation
• Earth treatment
• Filtration
The Flow sheet diagrams of the pilot scale rig designed for the study is shown in Figure
4.7 and 4.8. A complete detail of the equipment is given in Table 4.27.
Table 4.27: List of the equipment
Legends
1. Waste Oil Tank
15 Solvent Extraction
2. Diesel Accumulator
16 Feed Pump-2
3. Vacuum Pump
17 Settler
4. Measuring Tank
18 Feed Pump DC
5. Feed Pump-1
19 Distillation Column
6. Temperature Indicator
20 Circulation
7. Dehydrator
21 Furnace-2
8. Heater Circulation Pump
22 Condenser
9. Furnace
23 Treated Oil Tank
10. Vacuum Gauge
24 Filter Pump
11. Vapor Condenser
25 Filter Media
12. Cooler
26 Treated Oil Tank
13. Dehydrated Waste Oil Tank
27 Bowzer
14. Mixer Feed Pump-1 - -
94
95
Fig. 4.6: Pilot scale flow diagram of acid clay treatment process
95
Fig. 4.7: Pilot scale flow diagram of solvent extraction process
96
96
4.7.1 Process description (acid clay treatment)
The pilot scale flow diagram of the acid clay treatment process is shown in Figure 4.7
Feed stock from the waste oil tank (1) enters the measuring cylinder (2) where the mixing
homogenizes the used oil which is then left to settle naturally to remove sediments and
heavy particles. After settlement the used oil goes through the feed pump (3) and heat
exchanger (4). After absorbing heat, the used oil enters the dehydrator column (5), where
it is circulated by a heater circulation pump (6) and heat through the furnace (7). In the
dehydrator column the temperature is elevated to 180 0C and the used oil is separated
from the water and light hydrocarbons, the degree of oil separation is a function of
residence time in the column through which it is by vacuum (8), the collected vapors are
condensed by the vapor condenser (9) and stored in an accumulator tank (10), through the
vacuum pump (11) The dehydrated oil is passed through the water cooler to cool (12-13).
It is then further transferred through the mixture feed pump-1 (14) to mixture (15), where
sulphuric acid-oil are mixed together. In addition diesel was added to dilute the thick
used oil. Mixture feed pump-2 (16) transferred the acid-oil solution to the detergent/ (clay
earth) mixture (17). The solution was further transferred through feed pump-3 (18) to
distillation column (19), where the oil was heated to 250 oC. Heated oil was circulated
through circulation pump (20) to a furnace -2 (21) to continuously heat the oil for about 3
hrs. The light weight hydrocarbons moved upward and the heavy weight hydrocarbons
moved downward. The oil separated and the light hydrocarbons changed to vapor which
was transferred through the vacuum pump, condensed and collected in a accumulator
tank. The heated oil passed through a cooling water heat exchanger (22) that reduced the
temperature to 120 oC and was pumped to a treated oil tank (23) and then through a filter
pump (24) to filter assembly (25) where the oil, cleaned from impurities was collected
(26) for eventual removal or use (27).
97
4.7.2 Process description (solvent extraction treatment)
In this flow diagram right from the process 1 to 14 is similar to acid clay treatment
because the waste oil is hydro treated as shown in solvent extraction process flow
diagram Figure 4.8 In the mixer solvent-oil mixed together (15) where the desired ratio of
solvent and oil are mixed together. The mixture solvent is fed through feed pump-2 (16)
to settler tank (17), where natural gravitation for 24 hours allows the heavy particles to
sink to the bottom. The upper layer of the solvent oil mixture dawn from the settler tank
by the feed pump to a vertically long flash distillation column (19), where it is initially
heated to 60 oC at vacuum pressure 600 mmHg. Pressure within the column is maintained
by evacuation of solvent vapors by vacuum pump (11). In the distillation column solvent
separates from oil and oil separation degree is due to the function of residence time in the
column temperature and vacuum at 600 mmHg pressure and it is condensed in to liquid
and collected in a tank. Fuller’s earth is added in desired ratio to the used oil and heated
at 250 oC. Heated oil further circulated through circulation pump (20) to furnace -2 (21) to
continuously heat the oil for 3 hrs. The light weight hydrocarbons moved upward and the
heavy weight hydrocarbons moved downward. The light hydrocarbons are changed to
vapor and pass through the vacuum pump to be condensed and collected in a
accumulator. The heated oil cooled to 120 oC by a condenser (22) and pumped to the
treated oil tank (23). The oil is then from tank, pumped (24) to the filter assembly (25)
cleaned from impurities, collected, (26) for removal (27).
98
4.7.3 Pilot scale experiments Pilot scale experiments on acid clay treatment and solvent extraction treatment were
conducted in Mechanical Engineering Department of MUET, Jamshoro and physical
property tests of treated oil were performed by Hydrocarbon Development Institute of
Pakistan at Karachi shown in appendix.
4.7.3.1 Acid clay treatment No. 1
Chemicals
• Sulphuric acid (98% concentrate)
• Nitric Acid (70%)
• Dimethyl Sulfoxide
• Fuller’s Earth
The acid clay treatment process was carried out in a pilot scale of 5 liters, with similar
operating conditions to the laboratory scale study. The function of this pilot scale
experiment was to chemically react with base oil to segregate the impurities from the
sludge. Used lubricant oil was poured in a measuring cylinder and stirred thoroughly for
30 minutes and then to settle left for 24 hours to remove heavy particles. After natural
settlement, 2 liters of oil was pumped through the feed heat exchanger to absorb heat
from incoming dehydrated hot used oil to preheat the used lubricant oil. After preheating,
the oil enters the dehydration column, where it is heated to 200 oC and circulated
continuously for 3 hours. During dehydration the used oil separates from the water and
light hydrocarbons, this separation being function of residence time and a vacuum at 600
mm Hg. Collected vapors were condensed in the vapor condenser and drained from the
accumulator tank. After dehydration, used oil is pumped to dehydrate waste oil tank,
cooled to 40 oC and stored. 2 liters this oil was pumped to the acid mixture, which
comprises 70 percent by volume of 70 percent nitric acid and 30 percent by volume of 98
percent sulfuric acid, added 2 percent in volume to the used oil. This acid/oil was mixed
for 20 minutes. Since the oil was viscous, diesel fuel was added, so that the acid and oil
could easily mix together. In addition a catalyst, Dimethyl Sulfoxide 1.0 (% vol), was
99
added during the mixing of the acid solution. After acid and catalyst mixing, fuller’s earth
4 (Wt %) was added to the acid solution and mixed to gather to homogenize the solution.
The homogenized acid solution was pumped to the distillation column, where the
solution was heated at cracking temperature 250 oC and distillation pressure 600 mmHg.
The distillation heating was continued for three hours. The light weight hydrocarbons
moved upward and the heavy weight hydrocarbons moved downward. The light
hydrocarbons changed to vapor and passed through the vacuum pump and were
condensed and collected in a diesel accumulator tank. The heated oil was cooled to 120 oC by a water heat exchanger and pumped to treated oil tank and then pumped to the filter
assembly collected in a treated oil tank to await removal. The details of the experiment
process are given in Table 4.28 and the filtrate was collected and the test results shown in
Table 5.9 and Appendix F.
100
Table 4.28: Process parameters for acid clay treatment process
Process parameters
Dehydration Used oil (liters)
5
Dehydration Temperature (oC)
200
Vacuum Pressure (mm Hg)
600
Distillation Time (h)
3
Gravitational settling time (h)
24
Chemicals used oil ratio Used oil (liters) • Pre mixed (Nitric Acid 1 part by wt with 2 parts Sulfuric acid) • Catalyst Dimethyl Sulfoxide added 1.0 %
by vol: %to pre mixed • Diesel for dilution of waste oil as per
requirement
2 4% to used oil (vol)
Stirred at 275 rpm, mixing time (min)
30
Full (Wt %) to (Vol%) of oil
4%
Distillation Distillation temperature oC
250
Distillation column pressure (mm Hg)
600
Distillation Time (h)
3
Cooling temperature oC
120
101
4.7.3.2 Acid clay experiment No. 2
Chemicals
• Sulphuric acid (98% concentrate)
• Zeolite
• Fuller’s earth
In this acid clay treatment process a pilot scale setup was established for recovering used
oil. Pretreatment of used oil involved the removal of solid particles and water by gravity
settling in a measuring cylinder. In the measuring cylinder two separate layers of waste
oil and water were formed and the upper layer of waste oil was collected for further
processing. Catalyst cracking of this oil took place at the atmospheric pressure and 3
hours contact with zeolite at a the catalyst to waste oil ratio of 8g/L, 12g/L and 18g/L in
a high shear mixing operation. The operating variables are shown in Table 4.29. After
catalyst cracking the oil was washed with water to remove the carbon particles and then
pumped through a heat exchanger to the dehydration column, where it was heated at 140 oC for 1 hour at atmospheric pressure to remove residual free and emulsified water.
Dehydrated oil was cooled to 30 oC, treated with commercial grade sulfuric acid (98%)
and left for 24 hours for deasphalting and settling of acid sludge. Deasphalted oil was
then transferred to a detergent mixer, where the oil was mixed with fuller’s earth and then
injected to a vacuum distillation column. The light fraction was removed at the top and
the bottom was cooled and filtered using a series of filters (micron 1 nominal f10-2 Code)
and the filtrate was collected and the test results shown in Table 5.10 and Appendix G.
102
Table 4.29: Process parameters
Process parameters
1st Run
Catalyst waste oil ratio (g/l) 18.0
Stirred at 275 rpm, mixing time (min)
30
Cracking temperature oC
140
Cracking time (h)
3
Distillation pressure (mmHg) 600
Distillation time (h)
3
Sulfuric Acid (98concentration) Vol%
3
Fuller’s Earth (Wt gm %) to (Vol)
3.5
Distillation temperature oC
250
Distillation column pressure (mm Hg) 600
Distillation time (h)
3.5
103
4.7.3.3 Solvent extraction experiment No. 3
Solvents
• 2- Propanol
• n-hexane
• Potassium Hydroxide (KOH)
In this pilot scale solvent extraction re-refining treatment process, composite solvents
(70% of 2-propanol and 30% of n-hexane) was used with Potassium Hydroxide (KOH
g/500ml) in a same manner as carried out in case of laboratory scale experiment. Used oil
poured in a measuring cylinder mixed oil and left for 24 hours at room temperature.
Water and heavy particles settled were separated from the oil and then preheated through
heat exchanger and passed to dehydration column where dehydrated at 200 oC for 3
hours. Preheated used oil transferred to dehydrated waste oil tank passed by water cooler,
reduced temperature to 40 oC. Dehydrated oil mixed with solvent and KOH and clay
earth, stirred rigorously for 15 minutes. Solvent-oil then transferred to settler tank and left
for 24 hours. Heavy sludge separated and solvent-oil pumped to distillation column
where heated to 50 oC. Solvent was separated by vacuum pressure 600 mmHg that was
collected in accumulator tank. After distillation of oil it was passed through cooler where
temperature reduced and pumped to treated oil tank, the oil through filter-pump fed to
filter assembly where oil cleaned from impurities, filtered oil collected in a treated oil
tank for bowzer. The experiment process details are given in Table 4.30 and test results
shown in Table 5.11 and Appendix H.
104
Table 4.30: Process parameters for solvent extraction treatment process
Process variables
Dehydration Used oil (liters)
5
Dehydration Temperature oC
200
Vacuum Pressure (mm Hg)
600
Distillation Time (h)
3
Gravitational settling time (h)
24
Solvents • Solvent (70% of 2-propanol and 30% of
n-hexane) • 3g KOH/500ml • Solvent oil mixture
6:1 Distillation
Stirred at 275 rpm, mixing time (min)
30
Distillation column pressure (mmHg)
600
Oil neutralization Full (Wt %) to (Vol%) of oil
4%
Distillation temperature oC
250
Distillation column pressure (mm Hg)
600
Distillation Time (h)
3
105
4.7.3.4 Solvent extraction experiment No. 4
Solvents
• 2-propanol
• 1-butanol
• butanone
• Fuller’s Earth
In this pilot scale experiment, solvent-extraction treatment process carried out using 2
liters used oil, poured in a measuring cylinder, stirred rigorously for 30 minutes and left
for 24 hours for gravitational settlement removed heavy particles. Oil then passed to heat
exchanger absorbed heat, preheated the oil. After preheating, used lubricating oil entered
in dehydrated column, where oil heated by furnace to temperature of 200 oC,
continuously circulated for 3 hours. During dehydration used oil separated from the water
and light hydrocarbons, the oil separation degree is due to the function of residence time
in the column and drawn through a vacuum by a vacuum pump at atmospheric pressure
Collected vapors condensed the by vapor condenser and drained from the accumulator
tank. After dehydration used oil pumped to dehydrate waste oil tank, passed to water
cooler through heat pump reduced the temperature of used oil to 40 oC. Dehydrated
waste pumped to solvent mixture tank, mixed the composite solvent 40% 2-propanol,
35% 1-butanol and 25% with solvent-to-oil ratio 6:1 and stirred for 20 minutes. The
mixed solvent oil solution pumped to settler tank, where the oil-mixture settled down by
a natural gravitation for around 3 hours. The light particles remained on top and heavy
particle at bottom. The solvent oil mixture then pumped to vertically long flash
distillation column where it was heated to 60 oC for 30 minutes under vacuum pressure of
600 mmHg retained then lifted the solvent vapors upward by vacuum pressure separated
from the oil and collected in the accumulator tank, where as the impurities collided with
other moving particles and formed larger particles that settled down at the bottom of the
distillation column. Fuller’s earth was added 4 (Wt %) to oil and was heated 250 oC for 3
hours at atmospheric. The light weight hydrocarbons moved upward and the heavy
weight hydrocarbons moved downward. The oil separated the light hydrocarbons and in
106
the form of vapors transferred through the vacuum pump, condensed and collected in a
diesel accumulator tank. The heated oil passed through cooler where temperature of the
oil was reduced and pumped to treated oil tank, the oil through filter-pump feed to filter
assembly where oil cleaned from impurities, filtered oil collected in a treated oil tank for
browsing. Table 4.31 shows the experiment process and physical properties of the re-
generated oil are shown in Table 5.12 and Appendix I.
Table 4.31: Process parameters for solvent extraction treatment process
Process parameters
Dehydration Used oil (liters)
5
Dehydration Temperature oC
200
Vacuum Pressure ( mm Hg)
600
Gravitational settling time (h)
24
Solvents • Composite solvent 40% 2-propanol, • 35% 1-butanol and 25% butanone • Used oil (liters)
4% to used oil (vol) 2
Distillation
Stirred at 275 rpm, mixing time (min)
30
Distillation column pressure ( mm Hg)
600
Oil neutralization Full (Wt %) to (Vol%) of oil
4%
Distillation temperature oC
250
Distillation column pressure ( mm Hg)
600
Distillation Time (h)
3
107
4.7.3.5 Solvent extraction experiment No. 5
Solvents
• 2-propanol
• 1-butanol
• butanone
• Fuller’s Earth
In this pilot scale experiment the composite solvent used was 25% 2-propanol, 37% 1-
butanol and 38% butanone and the operating variables and procedure was fallowed
followed the previous pilot scale experiment No. 4 and Table 4.32 and the physical
properties of the re-generated oil are shown in Table 5.12 and Appendix J.
108
Table 4.32: Process parameters for solvent extraction treatment process
Process parameters
Dehydration Used oil (liters)
5
Dehydration Temperature oC
200
Vacuum Pressure ( mm Hg)
600
Gravitational settling time (h)
24
Solvents • Composite solvent 25% 2-propanol, • 37% 1-butanol and 38% butanone • Used oil (liters)
4% to used oil (vol)
2
Distillation
Stirred at 275 rpm, mixing time (min)
30
Heating time (min)
30
Distillation column pressure (mmHg)
600
Oil neutralization Full (Wt %) to (Vol%) of oil
4%
Distillation temperature oC
250
Distillation column pressure ( mm Hg)
600
Distillation Time (h)
3
109
CHAPTER 5
RESULTS AND DISCUSSIONS OF EXPERIMENTAL WORK
5.1 LABORATORY SCALE EXPERIMENTAL WORK
5.1.1 Dehydration
The results of experiment No: 1 conducted for dehydration is tabulated in Table 5.1,
which shows dehydration carried out fewer than four different variables. In the first run
the temperature was 140 oC and vacuum pressure 500 mmHg. In the 2nd run was at 180
oC and a vacuum pressure of 550 mmHg, water bubbles appeared, the weight of used oil
reduced but no fuming took place. The dehydration was continued for a 3rd run at 200 oC
and a vacuum pressure of 600 mmHg where water bubbles disappeared but no fuming
took place. In the fourth run the temperature and vacuum pressure were increased from
200 oC to 220 oC and from 600mm Hg to 650 mmHg respectively there were no water
bubbles, only oil fuming developed. A vacuum pressure of 600 mmHg is preferred to
ensure that the temperature will not rise above 250 oC, which is the oil degradation
temperature. The final dehydration temperature depends on the amount of water and
gasoline fractions in the used oil. ASTM standard methods were used to analyze the
physical properties of the dehydrated oil of all four runs. The properties of the dehydrated
oil have generally improved when compared to use oil properties. Improvement in
flashpoint reflects the de-watering and de-fueling taking place during dehydration and the
amount of fuel fraction and water removed from the used oil. This was further confirmed
by measured the oil weight loss at different temperatures. About the best temperature, oil
weight loss was co-related to physical properties of dehydrated oil at the temperature
applied, Test results show that oil properties improved with increase in oil loss i.e. at
temperature from 140 oC to 200 oC, but at a temperature of 220 oC with vacuum pressure
650 mmHg, properties remained the same but oil loss increased from 20 to 23 (wt %). So
the best dehydration temperature for waste oil dehydration is at 200 oC with vacuum
pressure 600 mm Hg. The physical properties of the dehydrated oil evaluated by using
ASTM standards are given in Table 4.7.
110
Many researchers have also worked on dehydration, water and gasoline components in
used oil distilled with different operating variables. Bishop and Arlidge (1978) carried
out dehydration, using a vacuum pressure of 600 mmHg at temperature 173 oC, Whisman
et al., (1978) used vacuum pressure of 10 mmHg at a temperature of 173 oC, Berry
(1981) used 760 mmHg at temperature of 218 oC, Scott and Hargreaves (1991) used a
vacuum pressure of 760 mmHg at a temperature of 250 oC and Gruber (1992) used a
vacuum pressure of 760 mmHg at temperature of 148 oC
111
Table 5.1: Dehydration of used oil
Crankcase waste oil properties
Dehydrated oil
Method Test Description Waste oil
At 140 oC Vacuum pressure 500 mm Hg 3 hrs
At 180 oC Vacuum pressure 550 mm Hg 3 hrs
At 200 oC Vacuum pressure 600 mm Hg 3 hrs
At 220 oC Vacuum pressure 650 mm Hg 3 hrs
ASTM D-445
Kinematic Viscosity at 100 oC cSt
18.52 18.05 17.11 15.20 15.20
ASTM D-445
Kinematic Viscosity at 40 oC cSt
145.10 142.94 140.90 137.55 137.55
ASTM D-2270
Viscosity Index 135 - - - -
ASTM D-1298
Specific gravity at 40 oC
0.8997 0.8655 0.8648 0.8643 0.8643
ASTM D-1298
Density at 15 oC
0.8992 0.8975
0.8967 0.8945 0.8945
ASTM D-92
Flash Point (COC) oC
220 220 221 222 222
ASTM D-97
Pour Point -21 -20 -20 -20 -20
ASTM D-874
Sulphated Ash Wt %
1.01 - - - -
ASTM D-1500
Colour Black 8 8 8 8
Oil weight loss (wt %)
10 13 20 23
112
5.1.2 Acid clay treatment
Experiment No: 2, was carried out using sulfuric acid (98 % H2SO4). The use of sulfuric
acid was because it oxidizes carbonaceous materials, metals in waste oil and other
oxidizable components create as acid sludge. This sludge contains impurities, additives,
contaminants as gasoline, metal components, nitrogen, sulfur etc. In this experiment
process diesel was added to make the mixing process easier.
The properties of regenerated lube oil were determined for three different sets of process
variables. The Process variables selected were acid waste to oil ratio, pressure of vacuum
distillation and temperature. Table 4.8 shows the variation in these variables for different
runs.
The effectiveness of the heating step was temperature and time dependent, the
temperature in the range 150 oC to 250 oC and time from 1.5 to 3.0 hrs. The increase in
extraction temperature from 250 oC resulted in a higher degree of extraction and lower
yield. During the process the oil was observed to be dark brown and burnt or charred in
color and to produce acidic conditions that were very corrosive. It was not feasible to use
this because of the lengthy contact of waste oil with sulfuric acid. The regenerated base
oil was collected for each run. ASTM standard methods were used to determine various
properties shown in Table 5.2. These results show that regenerated oil has a relatively
high viscosity, specific gravity, and density. These indicate that used oil has the lowest
flash point though it is the most viscous. This is because of the contaminants present in
used oil. Some of these contaminants include light hydrocarbon components and water
which in turn contribute to the low flash point. The metal, ash and other heavy
contaminants contribute towards the high viscosity of used oil. Maximum oil recovery
obtained at a third run used as acid waste oil ratio of 4:1, obtained more sludge and the
re-generated oil exhibited a better color. The larger percentage of sulfuric acid destroyed
the viscosity index improvers, used in modern motor oils. Sulfuric Acid in an amount
from about 1-2% converts the alkali metal sulfonate dispersants to free acids causing the
precipitation of additional solids.
113
Fuller’s earth (clay) was used to neutralize acid-treated oil to improve the color and make
the treated oil more suitable for re-use. As a result, the asphatene, carbon residue and ash
content were reduced more in the final product. Use of more fuller’s earth produced
lighter base oil. The best color results are obtained with a ratio of fuller earth’s (wt % to
vol %) to oil of 4:1. Figure 5.1, shows that the regenerated base oil recovery percentage is
43%; this lower recovery shows that the used oil was heavily contaminated.
The properties of all three products/ re-generated oil were compared with the virgin base
oil standards SN-150 and SN-500, found little heavy base oil because still contains some
impurities and the bas oil of this grade can’t be used as an engine oil.
Re-refining process produced sludge at every stage i.e. during pretreatment, acid
treatment and filtration. Sludge is completely combustible with net heating value
amounting around 4,000kcal/kg (Albert, 2006). On the other hand this acidic sludge
suitable as modifier for bituminous materials and can also be used for making carbon
rods as it is rich in carbon content. In case if disposed to the environment causes severe
pollution because they are concentrated forms of contaminants.
The properties of all three products/ re-generated oil were compared with the virgin base
oil standards SN-150 and SN-500, found little heavy base oil because still contains some
impurities and the base oil of this grade can’t be used as an engine oil. The results are in
closed agreement to (Hamad et al; 2000); used sulfuric acid (concentrate 98%) and
presented the test result that shows re-generated used oil has a high viscosity and the
lowest flash point, this is because of contaminants present in the re-generated oil;
recovery of re-generated oil was not measured, these results are in closed agreement with
the current research work.
Similar work reported by the (Herbert, 1977) worked on process for reclaiming spent
motor oils used sulfuric acid (concentrate 98%) obtained best result using from about 3-
6% sulfuric acids and fuller’s earth oil ratio 3:1 to 4:1 but not mentioned the recovery of
re-generated oil, but in currant research work the regeneration recovery has been
evaluated.
114
Table 5.2: Properties of re-generated oil Acid-Clay treatment
(Sulphuric acid (98% concentrate))
Acid clay treatment process
012345
39 40 41 42 43 44
Oil recovery %
Aci
d oi
l rat
io g
/L
(Sulphuric acid (98% concentrate))
Fig. 5.1: Regenerated oil recoveries by acid clay treatment
Fresh base oils Parameter Standards 1st Run 2nd Run 3rd Run
500N 150N
Kinematic Viscosity at 100 oC cSt
ASTM D-445
11.94 11.76 11.45 10.1 4.91
Kinematic Viscosity at 40 oC cSt
ASTM D-445
110.8 106.3 104.6
90.3 28.5
Specific gravity at 40 oC
ASTM D-1298
0.934 0.923 0.917 0.8861 0.8749
Density ASTM D-1298
0.943 0.935 0.911 0.8856 0.8744
Flash Point (COC) oC ASTM D-92
176 180 183 244 200
Pour Point oC ASTM D-97
-1 -1 -1 -9 -15
Colour ASTM D-1500
5.5
5.5 5.5 4.0-4.5 4.0-4.5
Oil recover
5
4
3
2
1
039 40 41 42 43 44
Aci
d oi
l rat
io (g
/I)
y (%)
115
Considering experiment No: 3, which was carried out using 35% by volume sulfuric acid
(98% H2SO4) and premixed treating agent comprises 70% by volume of 65% nitric acid a
with additional compound of dimethyl sulfoxide. Treating the used oil with an additional
compound dimethyl sulfoxide that act as catalyst accelerated the settling of the
contaminants and additives, effective in displacing air from the complex colloidal system
by which contaminants are held in suspension and dispersed in the oil. Treatment process
was observed using waste oil ratio, catalytic cracking temperature, column pressure of
vacuum distillation and distillation time was selected as listed in Table 4.9. Physical
properties of regenerated lube oil, test result were analyzed shown in Table 5.3. Result
shows that acid waste oil ratio increases, the over all properties of re-generated used oil
found improved, maximum oil recovery obtained at third run where acid waste oil ratio
4:1 at vacuum pressure 600mmg. Figure 5.2 shows that regenerated base oil recovery
percentage found 43 %. This recovery was well connected with complete settlement of
impurities and its separation of light frictions and impurities as discussed earlier. The
fuller’s earth 4:1waste oil ratio exhibits better color because of more sludge obtained.
The regenerated base oil was collected for each run. ASTM standard methods were used,
determined various properties of the base-oil regenerated shown in Table 5.5. Test result
shows that acid waste oil ratio increases, the viscosity of re-generated used oil found
improve, maximum oil recovery obtained at third run used acid waste oil ratio 4:1 and
exhibits better color because of more sludge removed but the base oil of this grade can’t
be used as an engine oil.
Gulick and Graham (1971) worked on re-refined waste crankcase oils and method used
acid, sulfuric acid (concentrate 98%) with catalyst presented the test result. Hamad et al
(2000) used sulfuric acid (concentrate 98%) presented the test result show that re-
generated used oil has a high viscosity and the lowest flash point this is due the
contaminants present in the re-generated oil; recovery of re-generated oil was not
measured. Similar work was reported by the Ivey and Herbert (1977). They worked on
process for reclaiming spent motor oils used sulfuric acid (concentrate 98%) obtained
best result using from about 3-6% sulfuric acids and fuller’s earth oil ratio 3:1 to 4:1, not
mentioned the recovery of re-generated oil
116
117
Acid clay treatment process
5
012345
40 41 42 43 44 45 46
Oil recovery %
Aci
d oi
l rat
io g
/L
Sulphuric acid (98% concentrate), Nitric Acid (70%) and Dimethyl Sulfoxide
Fig. 5.2: Regenerated oil recoveries by acid clay treatment
Oil recovery (%)
Aci
d oi
l rat
io (g
/I)
43210
40 41 42 43 44 45 46
Table 5.3: Regenerated base-oil properties of re-generated oil Acid-Clay treatment
[Sulphuric acid (98% concentrate), Nitric Acid (70%) and Dimethyl Sulfoxide]
In this laboratory experimental No: 4 work, catalyst dimethyl formamide was added to
the premixed treating agent comprises 70 % by volume of 70 % nitricacid and about 30%
by volume of 98% sulfuric acid exactly in the same manner as done in case of dimethyl
sulfoxide For this purpose catalyst waste oil ratio, catalytic, column pressure of vacuum
distillation temperature and distillation time was selected as listed in Table 4.10.
Dimethyl formamide accelerated the settling of the contaminants and additives, effective
in displacing air from the complex colloidal system by which contaminants are held in
suspension and dispersed in the oil. Oil recovery was 43% this recovery was well
connected with separation of impurities and light frictions as discussed earlier; properties
of regenerated lube oil were determined. Test result almost found same as no such major
change appeared in the regenerated oil shown in Table 5.4. Maximum oil recovery
obtained at first run where acid waste oil ratio 4:1 at vacuum pressure 600 mmHg that
exhibits dark color because of more sludge contained as shown in Figure 5.3.These test
results found substantially identical to the results obtained used dimethyl sulfoxide as a
catalyst.
Fresh base oils Parameter Standards 1st Run 2nd Run 3rd Run
500N 150N
Kinematic Viscosity at 100 oC cSt
ASTM D-445
11.22 11.05 10.98 10.1 4.91
Kinematic Viscosity at 40 oC cSt
ASTM D-445
108.11 105.21 99.35
90.3 28.5
Specific gravity at 40 oC
ASTM D-1298
0.8993 0.8976 0.8924 0.8861 0.8749
Density ASTM D-1298
0.8911 0.8893 0.8888 0.8856 0.8744
Flash Point (COC) oC
ASTM D-92
182 185
192 244 200
Pour Point oC ASTM D-97
-1 -1 -3 -9 -15
Colour ASTM D-1500
5.5
5.5 5 4.0-4.5 4.0-4.5
118
Table 5.4: Regenerated base-oil properties Acid-clay treatment
(Sulphuric acid (98% concentrate), Nitric Acid (70%) & Dimethyl Formamide)
Acid clay treatment process
012345
40 41 42 43 44 45 46
Oil recovery %
Aci
d oi
l rat
io g
/L
(Sulphuric acid (98% concentrate), Nitric Acid (70%) & Dimethyl Formamid)
Fig. 5.3: Regenerated oil recoveries by acid clay treatment
Parameter Standards 1st Run 2nd Run 3 rd Run
Kinematic Viscosity at 100 oC cSt
ASTM D-445
9.87 9.58 9.21
Kinematic Viscosity at 40 oC cSt
ASTM D-445
66.54 66.28 65.00
Specific gravity at 40 oC ASTM D-1298
0.8993 0.8970 0.8924
Density ASTM D-1298
0.8911 0.8893 0.8888
Flash Point (COC) oC ASTM D-92
181 185 191
Pour Point 0C ASTM D-97
-1 -1 -3
Colour ASTM D-1500
5.5
5.5 5
Oil recovery (%)
Aci
d oi
l rat
io (g
/I) 5
43210
40 41 42 43 44 45 46
119
Referring to experimental No: 5, in acid clay treatment catalyst zeolite was added to the
sulfuric acid (98 % H2SO4) percent, the operating variables impact on the properties of
re-refining of waste oil has been studied using four different sets. For this purpose
catalyst waste oil ratio, catalytic cracking temperature, column pressure of vacuum
distillation and distillation time was selected as listed in Table 4.11. A test sample of re-
refined waste oil was collected and various properties of re-refined oil were measured by
applying various test methods base upon ASTM standard as indicated in Table 5.5. In the
first test, catalytic cracking temperature was 180 oC where as in 2nd test with the different
catalyst waste oil ratio the temperature came out to be 160 oC. Since the properties of the
re-refined oil found improving; so for other tests at temperature 160 oC, catalyst waste oil
ratio was changed since the product viscosity increased with the increased catalyst waste
oil ratio. The main objective was to use the acid treatment as, it makes the oil free from
polar compounds like residual additives, oxidized, and acidic products related by-
products and particles in suspension, etc. this also does not modify the families of
hydrocarbon present in the oil that were not altered much during engine use. Acid
treatment was carried out at vacuum pressure 600 mm Hg and temperature kept
controlled within the range 30-40 oC by using cooling water to avoid sulphonation that
would consume hydrocarbon because of exothermal (Albert, 2006). Distillation operation
was continued until light fraction was separated and some of the light fraction escaped in
the environment during the dehydration.
The samples of collected re-refined waste oil subjected to detail analysis using ASTM
methods, physical properties test of re-refined oil was carried out in the laboratory,
Institute of Petroleum and Natural Gas Engineering, Mehran University of Engineering
and Technology. Fuller’s earth, characterized as absorbing basic colors removal and to
neutralize acid treated oil. The degree of mixing was not changed but the amount of clay
used for each test was varied. The higher amount of fuller’s earth clay produced lighter
base oil but usually re-refined base oil is expected to have ASTM color less than 2.0.
Figure 5.4 shows base oil recovery that was found to be in between 44 and 49%. This
recovery was well connected with separation of impurities and light fractions.
120
Table 5.5: Regenerated base-oil properties Acid-clay treatment
(Sulphuric acid (98% concentrate) & Zeolite)
Acid clay treatment process
0
5
10
15
43 45 47 49 51
Oil recovery %
Cat
alys
t oil
ratio
g/ 2020
Parameter Standards 1st Run 2nd Run 3rdRun
Kinematic Viscosity at 100 oC cSt
ASTM D-445
10.62 10.53 10.36
Kinematic Viscosity at 40 oC cSt
ASTM D-445
98.43 97.21 95.35
Specific gravity at 40 oC
ASTM D-1298
0.8895 0.8892 0.8883
Density ASTM D-1298
0.8884 0.8878 0.8874
Flash Point (COC) oC ASTM D-92
192 196 198
Pour Point oC ASTM D-97
-3 -5 -6
Colour ASTM D-1500
5.5
5.5 5
L
(Sulphuric acid (98% concentrate) & Zeolite)
Fig. 5.4: Regenerated oil recoveries acid clay treatment
Oil recovery (%)
Cat
alys
t oil
ratio
(g/I)
15
10
5
0
43 45 47 49 51
121
5.1.3 Solvent extraction treatment
Solvent extraction technology is the cheapest way of re-generating used oil; the product
is superior to those produced by low-temperature distillation processes and is the most
efficient and experienced re-cycling process.
5.1.3.1 Determining an effective solvent
In this research the performance of ccommercial grade hydrocarbon solvents, ketones and
alcohols (1-Butanol, 2-Propanol, 1-hexanol, Methyl Ethyl Ketone and n-hexane) were
investigated to determine the optimum solvent: oil ratio and extraction temperature based
on the solvents ability to dissolve the base oil in used motor oil.
In experiment No: 6, the effect of extraction temperatures of at 20 oC, 30 oC and 50 oC on
the percent oil losses (POL) for 1- Butanol-oil has been studied. Figure 5.5 shows that, as
the extraction temperature increases the POL decreases for the same solvent: oil ratio
(SOL). A sharp drop of POL was observed at all three extraction temperatures of SOL.
As seen in the Figures 5.5, 5.6 and 5.7, a sharp drop of POL values was found at SOR 1:1
up to 2:2 and for SOR 2:1 to 3:1, a gradual decrease in POL was observed as extraction
temperature of 20 oC as shown in Figure 5.5. Similar trends were observed at other
extraction temperatures are shown in Figures 5.6 and 5.7. So for SOR 3:1 at temperature
20 oC the maximum oil losses found 12, at temperature 30 oC it was 10.8 and at
temperature 50 oC was observed 10.5 is shown in Figure 5.8.
The effect of temperature on the percent sludge removals for same solvent at 20 oC is
shown in Figure 5.9. The rapid sludge removal found waste oil ratio (1:1-2:1) and then
gradually increasing the sludge removal percent found 12.3 using waste oil ratio (6:1).
The result at higher temperature at 30 oC and 50 oC found to be similar in trend shown in
Figures 5.10 and 5.11. As seen in the Figure 5.8 as the extraction temperature increases
the percent oil losses decreases for the same SOR. Similar trends were seen for sludge
removal in Figure 5.12. These results are in close agreement with the percent sludge
removal trend reported earlier by Elbashir et al. (1997).
122
Fig. 5.5: Effect of solvent: oil ratio on the extraction measured
by the percent of oil losses for 1-butanol at 20 oC
Solvent oil ratio
Perc
ent o
f oil
loss
es 0C
Fig. 5.6: Effect of solvent: oil ratio on the extraction measured by the percent of oil losses for 1-butanol at 30 oC
Solvent oil ratio
Perc
ent o
f oil
loss
es
0C
123
Fig. 5.7: Effect of solvent: oil ratio on the extraction measured
by the percent of oil losses for 1-butanol at 50 oC
Solvent oil
0C
C C C
Fig. 5.8: Effect of solvent: oil ratio on the extraction measured by the percent of oil losses for 1-butanol at 20,30 and 50 oC
Solvent oil ratio
Perc
ent o
il lo
sses
00
ratio
Perc
ent o
il lo
sses
0
124
Fi g. 5.9: Effect of solvent: oil ratio on the extraction measured
by the percent of sludge removal for 1-butanol at 20 oC
Fig. 5.10: Effect of solvent: oil ratio on the extraction measured
by the percent of sludge removal for 1-butanol at 30 oC
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
0C
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
0C
125
126
Fig. 5.11: Effect of solvent: oil ratio on the extraction measured
by the percent of sludge removal for 1-butanol at 50 oC
Fig. 5.12: Effect of solvent: oil ratio
percent of sludge removal for 1-butanol at 20,30 and 50 oC
on the extraction measured by the
Perc
ent o
f Slu
dge
Rem
oval
Solvent oil ratio
C
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
0
0C 0C 0C
In experiment No: 7 oil losses for solvent 2-propanol at temperatures 20, 30 and 50 oC is
shown in Figures 5.13, 5.14 and 5.15. It was observed that effect of solvent oil ratio on
the POL found decreasing by decreasing extraction temperature and similar trends was
observed for PSR at 20, 30 and 50 oC shown in Figures 5.17, 5.18 and 5.19. The effect of
temperature on POL for solvent 2-propanol was determined using different solvent oil
ratio and it was observed that at temperature 20 oC sharp drop of percent oil losses values
at lower solvent oil ratio 1.0 up to 2.0 and gradual decreased found with solvent oil 2.1 to
3, is Shown in Figure 5.13. This trend of POL was observed at other extraction
temperatures 30 oC and 50 oC shown in Figures: 5.14 and 5.15. The maximum oil losses
found 11.3 at temperature 30 oC and 50 oC with solvent oil ratio 4:1, where as with same
solvent oil ratio at 20 oC oil losses found 9.8 shown in Figure 5.16. The percent sludge
removals f erved tha
rapid sludge rem y increased,
maximum sludge removal percent found 11.6 using waste oil ratios (6:1), similarly with
same solve 11.9 and
12.8 percent is shown in Figures 5.18 and 5.19 a
5.20.
These results are in close agreement with (Elbashir et al, 1997), who reported the percent
sludge removal trend. This optimum value does not necessary correspond to maximum
PSR because an increase of the SOR beyond the optimum point can still lead to an
increase in percent sludge removal and minimum oil losses. Nimir, et al. (1997) have
also worked on the solvent 2-propanol and concluded that an increase in the SOR leads to
an increase of PSR but a decrease in POL.
or solvent 2-propanol at 20 oC is shown in Figure 5.17. It was obs t
oval found with waste oil ratio (1:1-2:1) and then graduall
nt oil ratios as at temperature 30 oC and 50 oC, maximum PSR found
nd the comparison is shown in Figure.
127
Fig. 5.13: Effect of solvent: oil ratio on the extraction measured by the percent of oil losses for 2-Propanol at20 oC
Solvent oil ratio
Perc
ent o
f oil
loss
es
0C
Solvent oil ratio
Perc
ent o
f oil
loss
es 0C
Fig. 5.14: Effect of solvent: oil ratio on the extraction measured by the percent of oil losses for 2-Propanol at 30 0C
128
Fig. 5.15: Effect of solvent: oil ratio on the extraction measured
by the percent of oil losses for 2-Propanol at 50 0C
Fig. 5.16: Effect of solvent: oil ratio on the extraction measured by the percent of oil losses for 2-Propanolat 20, 30 and 50 0C
0C 0C 0C
Perc
ent o
f oil
loss
es
0C
129
Fig. 5.17: Effect of solvent: oil ratio on the extraction measured
by the percent of sludge removal for 2-Propanol at 20 0C
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
0C
0C
Fig. 5.18: Effect of solvent: oil ratio on the extraction measured by the percent of sludge removal for 2-Propanol at 30 0C
Solvent oil ratioSolvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
130
Fig. 5.19: Effect of solvent: oil ratio on the extraction measured
by the percent of sludge removal for 2-Propanol at 50 0C
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
Perc
ent o
f Slu
dge
Rem
oval
Solvent oil ratio
0C
0C 0C 0C
Fig. 5.20: Effect of solvent: oil ratio percent of oil losses fo oC
on the extraction measured by the r 2-Propanolat 20, 30 and 50
131
In experiment No: 8, percent oil losses for Methylethyle Ketone (MEK) at temperatures
of 20 oC 30 oC and 50 oC is shown in figures 5.21, 5.22 and 5.23. It was observed that
effect of anol at
extraction temper
sludge removal (PSR) is shown Figures 5.25 and 5.26. The effect of temperatures on
increase of SOR led to decrease in POL and increase in PSR is shown in Figure 5.24 and
5.28. This is because of the solubility difference from that of oil will have higher
miscibility in oil thus lower percent oil losses. This is due to the variation between the
solubility parameters of the liquid media where the non polar or slightly polar
macromolecules are dissolved, i.e. the solution of base oil with some additives and
solvent, and the solubility parameter of those macro molecules as the temperature
increases the oil losses decreases. These results are in close agreement with the percent
sludge removal trend reported earlier by (Elbashir et al,1997; Elbashir et al, 2002), and
(Nimir et al, 1997) worked on the solvent MEK and reached to the conclusion that an
increase in the solvent to oil ratio led to an increase of PSR but a decrease in POL.
catalyst (MEK) gave the lowest POL, followed by 1-butanol and 2-prop
atures of 20 oC 30 oC and 50 oC on percent oil losses (POL) and percent
Fig. 5.21: Effect of solvent: oil ratio on the extraction measured by
the percent of oil losses for MEK at 20 oC
Solvent oil ratio
Perc
ent o
f oil
loss
es 0C
132
133
Fig. 5.22: Effect of solvent: oil ratio on the extraction measured by
the percent of oil losses for MEK at 30 oC
Fig. 5.23: Effect of solvent: oil ratio on the extraction measured by
the percent of oil losses for MEK at 50 oC
Solvent oil ratio
Perc
ent o
f oil
loss
es
Solvent oil ratio
Perc
ent o
f oil
loss
es
0C
0C
Fig. 5.24: Effect of solvent: oil ratio on the extraction measured by the
percent of oil losses for MEK at 20, 30 and 50 oC
Fig. 5.25: Effect of solvent: oil ratio on the extraction measured by
the percent of sludge removal for MEK at 20 oC
Perc
ent o
f oil
loss
e
Solvent oil ratio
s 0C 0C 0C
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
0C
134
Fig. 5.26: Effect of solvent: oil ratio on the extraction measured by
the percent of sludge removal for MEK at 30 oC
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
0C
Fig. 5.27: Effect of solvent: oil ratio on the extraction measured by the percent of sludge removal for MEK at 50 oC
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
0C
135
136
Fig. 5.28: Effect of solvent: oil ratio on the extraction measured by the
percent of sludge removal for MEK at 20, 30 and 50 oC
Solvent oil ratio
Perc
ent o
f Slu
dge
Rem
oval
0C 0C 0C
5.1.3.2 Effect of solvent type
In this experiment three different type of solvents was used determined their effect based
n the amount of oil losses and sludge produce from the used oil at different operating
temperatures and solvent oil ratio. The temperatures were 20 oC, 28 oC and 50 oC, solvent
oil ratio from 1:1 to of solvent related
the amount of sludge produced from the used oil and amount of oil losses in the sludge
phase, it was clearly observed that 1- butanol makes the highest percent sludge removal
followed by 2-propanol and MEK. On the other side MEK exhibits the oil losses lowest
followed by 2-propanol and 1-butanol.at each of the specified temperatures shown Figure
29 and 34. The best extraction performance with regard to sludge removal was found in
alcohol i.e. 1- butanol and 2-propanol produce, while ketone, i.e. MEK, posses the best
performance with regard to oil losses. The performance of the solvents determined in this
experiment that 1- butanol produced the most excellent result because of the highest
variation between the two solubility parameter, i.e. (6 (J/cm3)1/2 ), followed by 2-propanol
(7 (J/cm3)1/2 ) and MEK (4 (J/cm3))1/2 . Predicting the effective solvent at laboratory
experimental scale work was conducted with the intention that prior to go for any
extensive experimental work, it is better to know the optimum extraction conditions for
specified solvent.
The above observations can be described due to the following reasons; (1) the separation
of fine particles especiall ndent on the polarity of
the solvents used (Reis and Jernimo, 1988). The hydroxyl group (OH) belongs to alcohol
solvents that provide an electrostatic media erate
into large flakes. (2) The solubility of MEK in base oil is generally higher than that of
alcoholic solvents (Jordan ility in the base oil refers
to higher miscibility of solvent in base oil, which obviously decreases the amount of oil
losses in the sludge. However, higher miscibility of solvent in oil does not essential
means an increased in the PSR, although it could gives a good indication to the POL
according to Elias hypothesis (Elias, 1997), the lower POL obtained due to the solvent
that has a minimum solubility difference from that of oil have higher miscibility in oil.
These results are in close agreement with the percent sludge removal trend reported
o
6:1. Figure 5.24 and 5.28 shows the performance
y polymers in additives package is depe
that encourage fine particle to agglom
and Mc Donald, 1973). Higher solub
137
earlier by (Elbashir et al.; 2002), (Elbashir et al.; 1997) and (Nimri et al.; 1997) as
orked on the same solvent (2-propanol, 1-Butanol and MEK), at various temperatures
w
20 oC, 28 oC and 50 oC described in the form of PSR and POL in the extraction process
for recovering used lubricating oil These results are in close agreement though the
temperatures used were little changed.
Perc
ent o
f oil
loss
es
Fig. 5.29: Effect of so il ratio on the extraction measured by the nt of for 1-B d MEK a o
lvent: o perce oil losses utanol, 2-Propa
nol an t 20 C
f oil
loss
e
Fig. 5.30: Effect of solvent: oil ratio on the extraction measured by the percent of oil losses for 1-Butanol, 2-Propanol and MEK at 30 0C
Solvent oil ratio
Solvent oil ratio
Perc
ent o
s
138
139
Fig. 5.31: Effect of solvent: oil ratio on the extraction measured by them percent of oil losses for 1-Butanol, 2-Propanol and MEK at 50 oC
Fig. 5.32: Effect of solvent: oil ratio on the extraction measured by the
percent of sludge removal for 1-Butanol, 2-Propanol and MEK at 20 oC
Solvent oil ratio
Solvent oil ratio
Perc
ent o
f oil
loss
es
Perc
ent o
f Slu
dge
Rem
oval
Fig. 5.33: Effect of solvent: oi n the on
measured by the percent of sludge removal for 1-Butanol, 2-Propanol and MEK at 30 oC
l ratio o extracti
Solvent oil ratio
Perc
ent o
f Slu
d
Fig. 5.34: Effect of solvent: oil ratio on the extraction
measured by the percent of sludge removal for 1-Butanol, 2-Propanol and MEK at 50 oC
val
e R
emov
al
Solvent oil ratio
ge R
emo
Perc
ent o
f Slu
dg
140
5.1.4 Solvent extraction treatment In this experiment No. 9 the effective solvent to oil ratio was defined as proportion of
solvent to oil that destabilize fine micro particles (additives and contaminants) in the used
lubricant oil sample and allowed them formed large flakes which were able settled
down under gravity action after a specified period of time. As seen in Figure 5.35, that
addition 3 g KOH/ 500 ml to any alcohol used as a component of extraction flocculation
solvents significantly improved the sludge removal and decreased the oil losses. Figure
5.36 presented that the best PSR were achieved with 3 g KOH/ 500 ml, n-hexane and 2-
propanol, where the % of the oil losses decreased as the solvent to oil ratio increased. It
was further observed that as the solvent to oil ratio increased, the PSR value declined.
This indicated a poor performance of solvent–extraction process. The declined in
performance on further increased in ratio was found that the interaction between ion of
extraction-solvent (KOH/n-hexane, 2 propanol) to that of oil stabilized and due to
effective interaction the extraction performance reached to its highest value PSR-17. The
increase of SOR, the interaction of ion did not re-stabilized and remained isolate in oil
phase, hence flocculation did not shows the optimal
concentration of KOH that sludge residence time takes 40 min: for proper aging. When
compared with the result of te sition of 0.25 waste oil /0.35
n-hexane/0.4. Polar com ith 3 g KOH) used
by Martins (1997) found that base oil quality has little improved more.
5.1.4.1 Sedimentation
Sedimentation was determined used glass tubes of small diameter 2 cm made the possible
observation by watching. The tubes were filled with 40 g of solvent 10 g of waste oil and
concentration of KOH in the desired proportions. The mixture is then strongly agitated
and tubes are inverted 30 times to promote flocculation by velocity gradients. The height
of the settling is measured every 30seconds from the front scale that almost finished
within 40 minutes time. The settlement curves are shown in Figure 5.37.
improve further. Figure 5.37
rnary organic solvents compo
pound (80% 2 propanol, 20% 1- butanol, w
141
Fig. 5.36: Percent of sludge removal
Fig. 5.35: Per
c oil losses (POL) v/s KOH ent of
Solvent oil ratio
Perc
ent o
f oil
loss
es
Solvent oil ratio
Perc
ent o
f slu
dge
rem
oval
142
0123456789
101112
0 10 20 30 40 50 60
0 0.5 1 1.5 2 2.5 3
Minutes
cm
Fig. 5.37: Used oil Sedimentation
143
5.1.4.2 Effect on oil quality
Physical properties of the regenerated recovered base oil were determined by ASTM
standard method are summarizes in Table 5.6. Regenerated base-oil was collected and
analyzed, results show that viscosity test at 3rd run found quite encouraging and similarly
for flash point that is the main function of vacuum created in the distillation process. The
vacuum was operated at pressure of 600mm Hg at temperature 250 oC, similar trends was
observed for specific gravity. Similarly pour point found almost insensitive of the
changes in operating variables as shown in Table 4.21. Fuller’s earth (clay) was used but
s amount was not same because higher amount more than 3 (wt %) to solvent oil ratio
ould increases the catalytic
it
(vol %) would exhibits the oil loss and high temperature w
action of the activated clay. Recovery of the base oil was found to be in between 57 and
63%. This recovery was well connected with separation of impurities and light fraction.
Table 5.6: Regenerated base-oil properties of Solvent Extraction
Parameter Standards 1st Run 2nd Run 3rd Run
(2-propanol, n- Hexane, and KOH)
Kinematic Viscosity at 1000C cSt
ASTM D-445
9.98 9.90 9.82
Kinematic Viscosity at 00C cSt
ASTM D-445
98.11 87.56 78.79 4Specific gravity at 40 C ASTM
D-1298 0.8887 0.8882 0.8865 0
Density ASTM D-1298
0.8890 0.8873 0.8858
Flash Point (COC) C ASTM D-92
207 209 211 0
Pour Point0C ASTM D-97
-4 -7 - 9
Colour ASTM D-1500
4.0 4.0 4.0
144
In this laboratory experiment No 6 & 7 composite solvents contain 40% 2-propanol, 35%
1-butanol and 25% butanone and 25% 2-propanol, 37% 1-butanol and 38% butanone)
was used regenerated base oil from waste oil and the effect of various operating variables
on the properties of regenerated base oil was studied.
Three different sets of process variables were used to study their effects on regenerated
ent composition results, it was found that 25% 2-propanol, 37 %
-butanol and 38% butanone was the most suitable solvent produced higher percent oil
lube oil properties. Only waste oil ratio, distillation temperature, distillation vacuum
pressure and distillation time was selected for this purpose. For each run, regenerated
base oil was collected and analyzed. ASTM methods were used to characterize the
various properties of regenerated base oil. Properties of waste oil re-generated base oil
are shown in Tables 4.23 and 4.25 that represent the mass balance of respective
experiments are shown in Figures (5.38,5.39,5.40 and 5.41). Tables 4.24 and 4.26
represent process variables and Tables 5.7 and 5.8 represent physical properties for the
oil produced after solvent treatment. The regenerated base oil properties found improved
at 3rd run and the better result found with composite solvent 25% 2-propanol, 37% 1-
butanol and 38% butanone, this is because using higher percentage of butanone than
25%, produced good sludge separation and lower percent oil losses with oil percent
recovery from 65 to 68. The oil recovery percent for the solvent to oil ratio of 6:1 is
further improved because of an ash reduction means that optimum solvent to oil ratio led
the separation of some contaminants in the solvent phase especially the ash forming
martial. As a result of above mentioned facts, the solvent to oil ratio of 6:1 was
considered to be the better solvent to oil ratio used for the treatment of used lubricating
oil because it gives good ash reduction, and good oil recovery.
Wishman et al, (1978) used 25% of butanone to improve the oil recovery amount since
butanone has a lower solubility parameters value than two alcohols; 2-propanol and 1-
butanol. The solubility parameter of 2-propanol is (7.4) that is larger than 1-butanol of
(7.0) and both alcohols are much larger solubility difference than butanone of (2.8).
Comparing the two solv
1
recovery with improved quality of oil.
145
Distillation heating rate 220-250 oC temperature produced no foaming. Higher
pressure than this resulted in suction of the liquid to the vacuum lines.
Table 5.7: Regenerated base-oil properties
Parameter Standards 1st Run 2nd Run 3 rd Run
Kinematic Viscosity at 100oC cSt
ASTM D-445
9.2 8.9 8.5
Kinematic Viscosity at 40oC cSt
ASTM D-445
78.55 73.43 62.11
Specific gravity at 40oC ASTM D-1298
0.8895 0.8883 0.8853
Density ASTM D-1298
0.8893 0.8886 0.8833
Flash Point (COC) oC ASTM D-92
211 213
olour ASTM D-1500
4.0 4.0 4.0
t o i po
heat rate constant. Vacuum pressure 600 was o foaming, lower
(Composite solvent 40% 2-propanol, 35% 1-butanol and 25% butanone)
edimentation
s determi glass small dia cm m p
observation by watching. The tubes are filled with solvent (40% propanol, 35% Butanol
butanone) oil rat oportio mixture stron a
imes ote floc on by velo radients hei f
the settling is measured every 30seconds from the front scale that almost finished within
e. The settle rves are s igure . The sam roces s
ent propanol, 37% Butanol and 38% butanone) at solvent
6:1. The settlement curves are shown in Figure 5.43. When compared both the
was found that ma settlement ok place in a e time v
% propanol, 37% Butanol and 38% butanone).
emperature than 250 C caused fuming and severs foam ng, so it is im rtant to hold the
mmHg used causing n
5.1.4.3 S
Sedimentation wa ned used tubes of meter 2 ade the ossible
and 25% io 6:1 pr ns. The is then gly agit ted and
tubes are inverted 30 t to prom culati city g . The ght o
40 minutes tim ment cu hown in F 5.42 e p s wa
repeated with other solv
oil ratio
s (25 %
results it ximum to sam with sol ent (25
216
Pour PointoC ASTM D-97
-7 -9 -11
C
146
147
Fig. 5.38: Percent sludge removal
Fig. 5.39: Percent oil losses
Solvent oil ratio
Solvent oil ratio
Perc
ent o
f Slu
dPe
rcen
t of o
il lo
sses
ge
Rem
oval
Table 5.8: Regenerated base-oil properties
(Composite e)
solvent 25% 2-propanol, 37% 1-butanol and 38% butanon
Solvent oil ratio
Perc
ent S
ludg
e R
emov
al
Fig. 5.40: Percent sludge removal
Parameter Standards 1st Run 2nd Run 3 rd Run
Kinematic Viscosity at 100oC cSt
ASTM D-445
8.33 8.21 7.89
Kinematic Viscosity at 40 oC cSt
ASTM D-445
65.55 64.43 62.11
Specific gravity at 40 oC ASTM D-1298
0.8878 0.8873 0.8844
Density ASTM D-1298
0.8853 0.8846 0.8812
Flash Point (COC) oC ASTM D-92
213 214 222
Pour Point oC ASTM D-97
-8 -10 -11
Colour ASTM D-1500
4.0 4.0 4.0
148
Fig. 5.41: P f oil Losse
ercent o s
Fig. 5.42: Used Oil Sedimentation
Minutes
cm
Solvent oil ratio
Perc
ent o
f oil
loss
es
149
Fig. 5.43: Used oil sedimentation
5.1.4.4 Effect on oil quality
Physical properties of the composite solvent treated recovered base oils are summarized
in Table 5.7 and 5.8. The physical properties treated oils were determined, ASTM
standard method was used. Test results show that kinematics viscosity, specific gravity,
density, flash point and pour point found improved more at 3rd run in both the composite
solvents (40% 2-Propanol, 35% Butanol and 25% Butanone) and (25% 2-Propanol, 37%
Butanol and 38% Butanone) found improved at solvent oil ratio 6:1, but the physical
properties of regenerated base oil found more improved with composite solvent (25% 2-
Propanol, 37% Butanol and 38% Butanone) and oil recovery percent also improved
around 3%.
5.2 PILOT SCALE REREFINING EXPERIMENTS Waste lubricating oil re-refined at laboratory scales were repeated at pilot scale in a same
manner with same operating parameters. The whole treatment process was divided into
four unit i.e. Dehydration, acid/solvents treatment, vacuum distillation/solvent recovery
Minutes
cm
150
and polishing/adsorption unit. Since the pilot scale rig was designed for batch proc
therefo
ess,
re all re-refining experiments were carried out batch wise and did not need
le ehyd istillation treatment,
vacuum pump was used and the vapo e condenser and it
was easy to operate.
d s using es of vacuum distillation steps involving
t of a unique de minimize coking during operation. The main problems
ese proc plugg e lines.
Quang et al. (1976) and Snow and Delaney (1977) used the same process but did not
of uct.
5.2.1 Pilot scale acid clay treatment process
scale, the first e cted on acid treatm
dimethyl sulfoxide with 70% by volume of 70% nitric acid and about 30% by volume of
rameters were used same as used in
boratory scale and the process was run three times, to study their effects on re-
urred.
inematic viscosities and density little improved but specific gravity, flash point and
remained same, shows that experimental rig has worked properly and transferred same
frequent cleaning as made of stain ss steel. In d
r particles wer
ration and d
condensed through
Berry (1981) develope a proces a seri
equipmen sign that
encountered in th esses are ing of th
improve the dark color the prod
In pilot xperiment was condu /clay ent used catalyst
98% sulfuric acid. In this experiment the operating pa
la
generation lube oil properties shown in Table 5.9. Physical properties test of pilot scale
regenerated lube oil was conducted by Hydrocarbon Development Institute of Pakistan at
Karachi, is shown in Appendix F.
The operating performance of the pilot scale rig on acid clay treatment was measured by
the physical properties of the re-refined oil, that showed little improvement in results
found between pilot scale and laboratory scales but no any deviation occ
K
pour point remained same. Increased in viscosity and decreased in density indicate the
impurities, oxidation and polymerization products little more dissolved in the used oil. As
for as flash point is concerned, this indicated that acid-oil composition did not further
reduced the volatile compound from the used oil, that retained in the base oil but
151
heat as in case of laboratory scale. Since the improvement was so light therefore no
change occurred in the specific gravity, flash point and pour point and also color of the
il that remained same. Physical properties test result indicated that since no deviation
the low product yield (40-45%) and ising from acid treatment include
e s ith sal of d
pilot project physical test results were d o oi
th a ry test new virgin oil mu et c
y required stand r acceptance Re-refined oil observed that little
n c to La ry work but with fresh standard base oil
did not m visco d little h l, the
was lighter and secondly flash point was also low that showed regenerated oil still
d impurities. So th rated oil ca
Gulick and Graham (1971) reported that improved separation is some times obtained by
ide or dimethyl sulfoxide to the reaction. Sim or
by the Herbert and (1977). They worked on process for reclaiming spent
using from
3:1 to 4:1, not mentioned the recovery of re-
enerated oil. Wishman et al, (1978), Reis and Jeronimo (1990); Omar et al, (2008)
the re-generated oil; he did not measure the recovery of re-
(2004), have worked on acid-clay treatment process used oil
o
found in the result, therefore the effect of acid treatment remained same. This process is
problem ar
the dispo
fu re
associated w acid sludge an spent earth. The
rther compa with new virgin il base l grade
laborato results and st me ertain
ards fo
improvem ompared
nvironmental problem
shown in Table 5.9 wi
specificall
ent found whe borato
500N and 150 N atch, as specific gravity
containe is regene or the same use
(Bianco,c et al, 1993).
adding dimethyl foram
reported Ivey
sity foun eavier oi
n’t be used as virgin oil f
ilar w k was
motor oils used sulfuric acid (concentrate 98%) obtained best result
6% sulfuric acids and fuller’s earth oil ratio
Andreev and Tolmachev, (2002), and Kim et al, (2003), have worked on acid-clay
treatment process used oil with 93 to 98% sulfuric acid reported low product yield (45-
65%) and arising environmental problems related with disposal of acid sludge. Hamad et
al, (2000) used sulfuric acid (concentrate 98%) presented the test result that showed re-
generated used oil had a high viscosity and the lowest flash point that was due to the
contaminants present in
generated oil. Bhasker et al.;
about 3-
g
with 93 to 98% sulfuric acid reported low product yield (45-65%) and arising
environmental problems related with disposal of acid sludge.
152
Table 5.9: Re-generation lube oil properties Acid Clay Treatment (Pilot Scale)
Fresh base oils Physical Properties Standards Laboratory scale re-
generated oil Properties
Pilot Scale re-generated oil Properties 500N 150N
Kinematic Viscosity at 100oC cSt
ASTM D-445
10.98 10.54 10.1 4.91
Kinematic Viscosity at 40oC cSt
ASTM D-445
99.35
94.64
90.3 28.5
Specific gravity ASTM D-1298
0.8924 0.8892 0.8861 0.8749
Density ASTM
(Sulphuric acid (98% concentrate) Nitric Acid (70%) Dimethyl Sulfoxide)
In this pilot scale experiments No: 2, 98% sulfuric acid was used with catalyst zeolite.
The optimum operating parameters and methodology were followed as used in laboratory
scale. The re-generated lube oil physical properties tests were carried by Hydrocarbon
Development Institute of Pakistan at Karachi, shown in appendix G.
Re-refined oil when compared to laboratory scales found little improvement in the
properties of pilot scale regenerated oil but no any major deviation occurred. Almost all
physical properties improved like specific gravity, flash point and pour point etc.
Increased in viscosity and decreased in density indicate the impunities, oxidation and
polymerization products little more dissolved in the used oil. As for as flash point is
concerned, this indicated that acid-oil composition has little reduced the volatile
compound from the used oil, this shows that experimental rig has worked properly and
transferred same heat as in case of laboratory scale. Since the improvement was so light
Flash Point (COC) oC ASTM D-92
192 193 244 200
Pour PointoC ASTM D-97
-3 -3 -9 -15
Sulphated Ash Content (wt %)
ASTM D-874
- 0.30 0.01 0.01
Colour ASTM D-1500
5 5 4.0-4.5 4.0-4.5
D-1298 0.8888 0.8874 0.8856 0.8744
153
th
hed virgin oil 500N and 150 N observed that physical properties of r-generated
oil as viscosit
nt was agravity was lighter and h poi lso
19
ow that showed regenerated oil still
93). So this reg
erefore no change occurred in the specific gravity, flash point and pour point and also
own in Table 5.10, so that re-refined
oil must meet certain specifically required standards for acceptance. Re-refined oil when
matc oil
did not match to the virgin oil or base y found little heavier oil, the specific
s l
contained impurities (Bianco,c et al, enerated oil can’t be used as v
e propert regenerated nd matched to the test
al sed zeo sed
ressure 580 mm cracking temperature 180oC.
color of the oil that remained same. In acid treatment Fuller’s earth (clay) was used to
neutralize acid–treated oil as well as for color removal. Brighter base oil can be obtained
by the use of more fuller’s earth. However, usually regenerated base-oil is expected to
have ASTM color less than 2.0. Conventional acid-clay cannot be used to produce
brighter base-oil of brighter quality. Hydrotreating the oil can produce base-oil of bright
color. However, hydrotreatment was a high pressure catalytic process and therefore not
used. Recovery of the base-oil was found to be in between 45 and 49%. It was well
connected with separation of impunities and light fraction. These results were further
compared with new virgin oil base oil grades as sh
secondly fla
irgin
oil for the same use. Th physical ies of oil fou
result of (Siddiquee et , 2008) u lite as catalyst, the other parameters u were
vacuum p Hg and
154
Table 5.10: Regen roperties (zeolite)
(Sulph
5.2.2
n this pilot scale experiments No: 3 used lubricating oil was treated with solvents (70%
of 2 r
operati
4.30. P
that wa
append
regener en compared to laboratory scales found little improved like
ecific gravity, flash point and pour point etc. Increase in viscosity and decrease in
den y
conditi
hown in Table 5.11 and Appendix H.
resh base oils
erated Base-oil P
Ferties Standards Laboratory scale Pilot Scale Physical Propre-gener
Properties re-generated oil
Properties 500N 150N ated oil
Kinematic Viscosity at 10
ASTM 45
10.36 10.31 10.1 4.91 0oC cSt D-4
Kinematic Viscosity at 40 C cSt
ASTM D-445
95.35
94.42
90.3 28.5 o
Speci fic gravity ASTM D-1298
0.8883 0.8870 0.8861 0.8749
ASTM D-1298
0.8874 0.8863 0.8856 0.8744
int (COC) oC ASTM D-92
198 201 244 200
ntoC ASTM D-97
uric acid (8% concentrate) Zeolite)
Pilot scale solvent extraction treatment
I
nt wt %) D-874 ASTM D-1500
5 4.5 4.0-4.5 4.0-4.5
Density
Flash Po
Pour Poi -6 -7 -9 -15
Sulphated Ash Conte (
ASTM - 0.20 0.01 0.01
Colour
-p opanol and 30% of n-hexane) at SOR 6:1 with 3g KOH/500ml laboratory scale
ng parameters followed by same methodology was followed in shown in Table
erformance of the pilot scale was investigated by the physical properties of the oil
s carried by Hydrocarbon Development Institute of Pakistan at Karachi, shown in
ix H. Performance of the pilot plant was evaluated by the physical properties of
ated base oil wh
sp
sit indicated that the impurities further reduced, that brought the oil in original
on and matched to the standard base oil 500N and 150N (Bianco,c et al, 1993)
s
155
Durran
propan
virgin
Ketone
compar
lubrica
solvent
g/500m
that the
(2000)
compo sed. Bianco,C et al (1993) that
ulphated ash reduced o considerable extent and color become within the range. Physical
pro t
close a
with 3
used 3
re-gene
i et al (2010) used solvent oil ratio 6:1 of dosage of 3 g KOH/500 ml n-hexane, 2-
ol considered the best solvent oil ratio and the test result almost similar to SN-500
base oil. Jesusa Rincon et al (2005) used two single components Methyl Ethyl
(MEK) and 2-propanol mixed at a ratio 3g/g; added 2 g of (KOH) test results
ed standard virgin oil was almost similar to SN-130 virgin oil and suitable for new
nt oil. Lim Lee Ping et al (2004) used 1.5 g/500ml KOH to the alcohol in the
obtained maximum sludge removal and minimum oil losses by addition of 1.5
l KOH to the alcohol in the solvent. Nimra et al (1999) and Lim (2000) observed
optimum ratio of the same solvent to oil ratio as 4:1. Foo Chwan Yee et al.
observed that with the addition of 1.5 gram potassium hydroxide (KOH) into the
site solvent, the sludge sedimentation rate increa
s
per y tests indicate that overall properties of the re-generated oil improved and are in
greement with fresh oil. Martin (1997) used 80 % 2-propanol, 20 % 1-butanol
g/L KOH for the process and showed similar result. Alves dos Reis et al.; (1988)
g/L of potassium in solution of n-hexane and 2-propanol and the properties of the
rated oil were similar to new lubricant.
156
Tab
Scale
2-propanol, n-hexane, potassium hydroxide (KOH))
Referri
compo
comple
optimu n laboratory experiments as shown in Table 4.30. Pilot
cale treated oil sample were tested at the Pakistan Hydrocarbon Institute laboratory
Kar h
I. these
Physic opanol, 35% 1-butanol and
5% butanone reduced the maximum ash and the presence of 75% alcohol in the mixture
wit i
produc
Fresh base oils
le 5.11: Regenerated Base-oil Properties by Solvent Extraction Process Pilot
al Properties Standards Laboratory Pilot Scale Physicscale re-
generated oil re-generated oil
Properties 500N 150N Properties
Kinematic Viscosity at 100 oC cSt
ASTM D-445
9.82 9.14 10.1 4.91
Kinematic Viscosity at 40 oC cSt
ASTM D
78.79 73.95 90.3 28.5 -445
Specific gravity ASTM D-1298
0.8865 0.8853 0.8861 0.8749
Density ASTM D-1298
0.8858 0.8846 0.8856 0.8744
oint (COC) oC ASTM D-92
211
(
D-97 ed Ash Content ASTM
D-874 - 0.09 0.01 0.01
ASTM D-1500
4.0 4.0 4.0-4.5 4.0-4.5
Flash P 214 244 200
Pour Point oC ASTM - 9 -10 -9 -15
Sulphat(wt %) Colour
ng to pilot scale experiment No: 4, investigation is conducted at a solvent
sition of 40% 2-propanol, 35% 1-butanol and 25% butanone at SOR 6:1. A
te set of experiment similar to the laboratory scale study was conducted with same
m process variables used i
s
ac i, using ASTM standard methods and the physical properties is shown in appendix
properties are compared with laboratory scale and virgin oil in Table 5.12.
al properties show that a composite solvent 40% 2-pr
2
h h gher amounts of 2- propanol than 1- butanol makes the mixture very selective and
es ash reduction and oil recovery but poorly separated sludges. The percentage of
157
oil reco
the re-g
Tab
(40% 2-propanol, 35% 1-butanol and 25%)
Considering the pilot scale experiment No:5, solvent to oil ratio of composite solvent
25% 2-propanol, 37% 1-butanol and 38% butanone at SOR 6:1 was investigated. A
complete set of experiment similar to the laboratory scale study was conducted with same
optimum process variables used in laboratory scale shown in Table 4.30 and test report
shown in appendix J; these properties were compared with laboratory scale and virgin oil
shown in Table 5.13
The result of investigation indicated that percentage of oil recovery further improved,
lowered the sulphated ash content means dissolved contaminants in the solvent phase
especially the ash forming, which was considered to be undesirable. The optimum
Fresh base oils
very for a solvent to oil ratio of 6:1 is further improved with physical properties of
enerated oil as shown in Table 5.12.
le 5.12: Regenerated Base-oil Properties by Solvent Extraction Process Pilot scale
ical Properties Sta
Laboratory
Phys ndards scale re-generated oil
Properties
Pilot Scale re-generated oil Properties 500N 150N
Kinem tic Viscosity at o
ASTM 8.5 aC cSt D-445
7.8 10.1 4.91 100Kin40oC
ematic Viscosity at cSt
ASTM D-445
62.11 56.6 90.3 28.5
ASTM D-1298
0.8853 0.8782 0.8861 0.8749
sity ASTM D-1298
0.8833 0.8752 0.8856 0.8744
oC ASTM D-92
216 224 244 200
r PointoC ASTM -11 -13 -9
Specific gravity
Den
Flash Point (COC)
PouD-97
-15
Sulphated Ash Content (wt %)
ASTM D74
- 0.030 0.01 0.01
Colour ASTM D-1500
4.0 4.0 4.0-4.5 4.0-4.5
158
solvents composition provides highest oil recovery and ash reduction. The results
dicated that using the higher percentage of 2-propanol than 25% produces higher ash
reducti
nd that 25% 2-propanol, 37% 1-butanol and 38% butanone at SOR
6:1 was the most suitable solvent composition to be used with Pakistani used lubricating
oil prod
Many r
7, Elbashir et
al.; 2002, Hamad et al.; 2005). Whisman et al. (1978) introduced a composite solvents
treating
oil ratio of 8 to 1, which was considered unfeasible.
They evaluated various ratios of the ternary systems and noticed that the 2-propanol rich
system
h-forming materials.
Therefore they chose a solvent system of (1:2:1) of (2-propanol, 1-butanol, butanone)
with a
s and Jernimo (1988) studied the performance of ketone and
alcohols, which are miscible with base oil at room temperature and the flocculating action
of pola
iminary criterion to select the components of
omposite solvents. They noticed in some cases that polar solvent induce the formation of
an ele
sed oils.
in
on, higher sludge removal and poor oil recovery, while using higher percentage of
butanone above 25% produces lower ash reduction, lower sludge removal and higher oil
recovery. It was fou
uced around 68 % oil recovery and the physical properties measured on the oil
sample compared with virgin oil graded matched to the base oil standard and found in
close agreement (Bianco et al.; 1993).
esearchers investigated solvent treatment of used lubricant oil (Snow and Delaney,
1977, Whishman et al.; 1978, Reis and Jeronimo, 1988, 1990, Martins, 199
used oil using 2-propanol, 1-butanol and butanone. Their investigation showed
that the two alcohols make a binary system that was reasonably effective. However, best
results were obtained at a solvent to
s produced poorly separated sludge. While butanone rich systems produced good
sludge separation but it seemed to re-dissolve segregated as
solvent to oil ratio of 3 volumes to 1. Snow and Delay (1977) investigated the
solvent extraction systems of used oils. The solvent to oil ratio was either 4 to 1 or 8 to 1.
The solvents studied were 2-proanol / 1-butanol mixture, methyl isobutanone, butanone
and acetone solvent. Rei
r solvents in used oils. They showed that the difference in solubility parameters
between the solvent and a typical poly-olefin (polyisobutylene), which is a contaminant
in the used oil, could be used as a prel
c
ctrically stabilized dispersion and recommended the addition of potassium
hydroxide in alcoholic solution to easily destabilize the dispersion and increase sludge
removal from u
159
Reis an
not correlated with the capability of flocculation. 2-
ropanol would be a better oil-flocculating agent than 1-butanol with ethanol even better
at floc
ketones having less than four carbon atoms is miscible
with the base oil. It has been observed that by proper selection of components and
compo
Table 5.13: Regenerated Base-oil Properties by Solvent Extraction Process
d Jeronimo (1990) recommended that the capability of polar solvents to segregate
sludge from used oil is closely related to their solubility parameters. The polarity itself, as
measured by dipole moment, is
p
culating than 2-propanol. Propanone would be more efficient than butanone;
however, none of the alcohols and
sitions, formulations having a more favorable balance between miscibility with
base oil and flocculation action could be obtained.
Fresh base oils Physical Properties Standards
Laboratory scale
re-generated oil
Pilot Scale re-generated oil
Properties Properties 500N 150N
Kinematic Viscosity at 100oC cSt
ASTM 7.89 7.20 10.1 4.91 D-445
tic Viscosity at 0oC cSt
ASTM D-445
62.11 58.43 90.3 28.5
pecific gravity ASTM D-1298
0.884
Kinema4S 4 0.8753 0.8861 0.8749
Density ASTM D-1298
0.8812 0.8750 0.8856 0.8744
lash Point (COC) oC ASTM D-92
222 222 244 200
o
F
Pour Point C ASTM D-97
-11 -14 -9 -15
S at(wt %) D-874
ulph ed Ash Content ASTM - 0.021 0.01 0.01
(25% 2-propanol, 37% 1-butanol and 38% butanone) D-1500
Colour ASTM 4.0 4.0 4.0-4.5 4.0-4.5
160
CHAPTER 6
CONCLUSIONS AND RECOMMENDATIONS
6.1
es that:
•
tones of vehicle waste oil is generated every year. Most of this oil is wasted
• Used oil has an excellent heating value (13,000to 19,000 Btu/lb) and can help
oils contributing significant adverse effect to environmental air emissions
and controls may be necessary when burning. The burning of used oil is also an
tion prevention alternative.
•
loss. The establishment of re-generation setups in every district would help in
proper oil collection and reduce transport costs and produce job opportunities for
ent operating variables were used and the best
result was obtained by vacuum pressure 600 mmHg and a temperature of 2000C.
CONCLUSIONS
This study conclud
Used oil is a problem waste because its generation is ubiquitous and it can contain
hazardous liquid wastes and other contaminants; its disposal becomes
complicated and costly even when properly handled. In Pakistan about 274000,
because no suitable disposal route exists. Therefore increasing the menace of
environment pollution.
meet the growing national energy demand. However, the constituents present in
used
economical loss. A better use of used oil is re-refining back into usable base stock
oil, the energy conservation and pollu
Collection, handling and disposal of used oil are the most important elements in
minimizing used–oil mismanagement. Suitable oil pickup points, collection
centers and proper transportation would help in maximum oil collection without
the local people.
• In the dehydration process, differ
161
•
250 0C, further heating
temperature causes undue cracking in the oil and alters the chemical structure of
out at a temperature in the range of 80°-120° C., in order to reduce the oil
•
t improves the segregation
and flocculation of waste oil impurities (2-propanol). The addition of KOH to
• Solvent extraction process reduces the contaminants to levels such that no further
of 25% 2-propanol, 37% 1-
utanol and 38% butanone. The solvent extraction re-refining process produces
an asphalt component or may be mixed with liquid fuel and
burned. The best use for this sludge is to use for an offset ink component.
In the acid clay treatment process, a higher percent of sulfuric acid inclusion
would partially destruct the viscosity improvers, the best result obtained using 3-
6% and 1-2% convert the alkali metal sulfonate dispersants to free acid and left
the sludge heavy. The heating was carried out at
the hydrocarbon family . The quantity of clay used is preferably in the range of 2-
6% by weight. At less than 2% clay, the color removal is poor; at greater than 4%,
the quantity of oil lost with the clay is considerable. Filtering should be carried
viscosity and thus increase the filtration rate. Acid/ Clay treated oil yields 45-60
% lube oil of good quality. But this is difficult to obtain. The process ends up with
large volume of acidic sludge as the by-product.
The composite solvent has two single components: basic compound miscible with
base oil (n-hexane) and a flocculating compound tha
alcohol increases the capability to remove sludge from the waste oils. In all cases
studied, the addition of 3g/500ml KOH to the alcohol solvents is shown to
significantly increase sludge and additive removal from the waste oil.
operational problems were encountered on vacuum distillation. The best oil
recovery (68%) and ash reduction by extraction that were obtained using optimum
solvent to oil ratio of 6 to 1 with solvent composition
b
lube oils that compare with new virgin oils and this indicates that a commercial
process will restore vehicle waste oils to original quality for re-use. Since the
solvent extraction process produces an organic sludge after solvent recovery, it
may be used as
162
•
.2 RECOMMENDATIONS
here are some recommendations which can be made to improve the vehicle waste oil
manage
•
•
sportation
cost and provide job opportunities for local people.
owed to collect the oil. The used oil price must be fixed so as to encourage the
il generators. All taxes shall be exempted, to discourage illegal business. Any
to overcome them.
•
ility is strongly dependent on the scale
nd economics of the operation. Usually thousands of tonnes of used oil are
terial from an energy conservation point of view. Solvent
A piolt plant running on batch process was found satisfactory during operation to
remove water by dehydration. It does not need to be cleaned so frequently
because it is made of stainless steel and a vacuum pump is used.
6
T
ment in Pakistan.
Used oil collection centers should be established based in cities on population and
at least one center per 100,000 populations. In rural areas one collection center
can be established at a radius of 3 km.
All pickup points must be registered and used oil should be stored in containers
having capacity not more than 55 gallons/ 205 liters. Every District Headquarters
should have one used oil re-generation unit. This would reduce the tran
• Government shall issue licenses to the dealer and no unauthorized person may be
all
o
deficiencies related to legislation enforcement should be identified along with
ways
Re-refining is the preferred method of used oil disposal from the environment
protection point of view. However, its viab
a
required on an annual basis to sustain such operation.
• It is necessary to use modern treatment procedures and recovery technologies as it
is a valuable ma
163
extraction treatment is the most suitable option to dispose of the waste oil as the
• From environment point of view, re-refining of used oil by solvent extraction
6.3
nducted fractional distillation that is
the
fractions using a high vacuum pressure. Pilot
plant/experimental rig used in this study may be improved by installation of a
frac
sludge produced is non-acidic and can be used for ink and for other materials.
process is a suitable process and generates the sludge without acid and can be
used for print media.
SUGGESTIONS FOR FUTURE WORK
Re-refining carried out in this study has not co
separation of a mixture into its component parts, or fractions, such as in separating
chemical compounds by their boiling point by heating them to a temperature at which
several fractions of the compound will evaporate. It is a distillation that further
purifies the waste oil in
tional distillation column, so that to separate the oil into the components.
164
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Appendix -A
QUESTIONNAIRE ON THE MANAGEMENT OF VEHICLE WASTE OILS IN
PAKISTAN:
GENERATORS OF USED OILS
Dear Sir
This questionnaire is for the collection of data in respect of research work on the
management of vehicle waste oil in Pakistan. This study is mainly for academic purpose
and all information supplied will be treated with strict confidence.
Honest, clear and objective responses to the questions would be highly
appreciated.
INSTRUCTION
Please tick as appropriate.
SECTION A
INDIVIDUALS
1. Name
2. Educational Qualification [ ]
3. Age years [ ]
INDUSTRIES
1. Name of Company
________________________________________________
2. Address/Location
________________________________________________
3. Year Established
________________________________________________
SECTION B
1) What do you use virgin engine oil for?
Private vehicles [ ] Commercial Vehicles [ ] Heavy duty vehicles [ ]
Others (specify)
2) What quantity of engine oil do you use?
Liters [ ] Gallons [ ] Drums [ ] Tons [ ]
179
3) How often do you change your oil?
Monthly [ ] 3 months [ ] 6 months [ ] Specify [ ]
4) Who changes your oil?
Self [ ] Mechanics [ ] Technicians [ ] Service stations [ ] Specify [ ]
5) What quantity of used engine oil do you produce per change?
Liters [ ] Gallons [ ] Drums [ ] Tons [ ]
6) For Motor mechanic/ Service station man, how many vehicles/generators do you
service in a week [ ] what quantity of used engine oil do you generate weekly?
Liters [ ] Gallons [ ] Drums [ ] Tons [ ]
7) How do you dispose of the used engine oil? Sewers [ ] Landfills [ ] Pouring
on the ground [ ] Sale [ ] Service Station [ ] Mechanics [ ]
Specify
180
Appendix-B
QUESTIONNAIRE ON THE MANAGEMENT OF VEHICLE WASTE OILS IN
PAKISTAN:
DEALERS IN USED OILS
Dear Sir
This questionnaire is for the collection of data in respect of research work on the
management of vehicle waste oil in Pakistan. This study is mainly for academic purpose
and all information supplied will be treated with strict confidence.
Honest, clear and objective responses to the questions would be highly
appreciated.
INSTRUCTION
Please tick as appropriate.
SECTION A
INDIVIDUALS
1. Name
2. Educational Qualification [ ]
3. Age years [ ]
INDUSTRIES
1. Name of Company ________________________________________________
2. Address/Location ________________________________________________
3. Year Established ________________________________________________
SECTION B.
1) Why did you go into used oil business?
Commercial [ ] Other (specify)
2) Where do you get the used engine oil?
Mechanic garages [ ] Petrol Stations [ ] Individual suppliers [ ]
Other sources (specify)
3) Do you grade the used oil? Yes [ ] No [ ]
4) If yes, on what basis do you grade the used oil?
Grading based on quality [ ] Grading based on sources [ ] Others
(specify)
181
How much of the used engine oil do you get in a week?
Liters [ ] Gallons [ ] Drums [ ] Tons [ ]
5) How do you store the used oil?
Metal drums [ ] Plastic Kegs [ ] Plastic drums [ ]
Metal tanks [ ] Other containers (specify)
6) Do you mix new stock with old stock? Yes [ ] No [ ]
7) How much of the used engine oil do you sell in a week?
Liters [ ] Gallons [ ] Drums [ ] Tons [ ]
8) Who are the buyers of the used engine oil?
Individuals [ ] Transporters [ ] Industries [ ]
9) What in your own opinion is the used engine oil used for?
Direct re-use as engine oil in other vehicles/equipments [ ] Reuse as
boiler fuel [ ] Reuse as furnace fuel [ ]
Cement production [ ] Block making [ ] Wood preservation [
] Rust prevention [ ] Others (specify)
10) Do you know about recycling? Yes [ ] No [ ]
11) If yes, which recycling method(s) are you familiar with?
Settling [ ] Filtration [ ] Evaporation [ ]
Blending directly with other oils [ ] Re-processing [ ]
Re-refining [ ] Others (specify)
12) Do you recycle the used engine oil before selling?
Yes [ ] No [ ]
13) If yes, which recycling method do you use?
Settling [ ] Filtration [ ] Evaporation [ ]
Blending directly with other oils [ ] Re-processing [ ]
Re-refining [ ] Others (specify)
14) What quantity of the used engine oil do you recycle in a day?
Liters [ ] Gallons [ ] Drums [ ] Tons [ ]
15) Do buyers prefer the recycled oil? Yes [ ] No [ ]
16) How much does a liter of the used engine oil cost?
How much does a liter of the recycled engine oil cost?
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183
Appendix-C
Proposed used oil storage and transportation system
Appendix-D
Pilot scale experimental rig. (Designed and fabricated)
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185
Appendix-E
Used Oil Test Report
186
Appendix-F
187
Appendix-G
188
Appendix-H
189
Appendix-I
190
Appendix-J
