Cost and energy efficiency assessment of odour abatement systems 7_1_15 Action 15

Cost and energy efficiency assessment of odour abatement systems

Carbon footprint of abatement systems

Dispersion model of odours in a case study

Authors: Meehanite Technology Ltd and AX Consulting Ltd

Date: 15.9.2014

Odorless casting

Action 15 Reliable, cost and energy efficient odour abatement system


2

Table of Contents

Table of Contents ................................................................................................................................. 2

Appendixes........................................................................................................................................... 3

Abbreviations used ............................................................................................................................... 4

Pilot foundries ...................................................................................................................................... 5

1 Aim of the report .......................................................................................................................... 6

2 Pilot studies of abatement systems............................................................................................... 6

2.1 Content of pilot studies.......................................................................................................... 6

2.2 Piloted test description ........................................................................................................ 10

2.3 Results of abatement systems .............................................................................................. 11

2.3.1 RTO oxidation system ................................................................................................. 12

2.3.2 Biofilter system ............................................................................................................ 14

2.3.3 Adsorption system........................................................................................................ 17

2.3.4 Ignition system ............................................................................................................. 18

3 Cost analysis, results and conclusion ......................................................................................... 20

3.1 RTO oxidation system ......................................................................................................... 21

3.2 Biofilter system ................................................................................................................... 21

3.3 Adsorption system ............................................................................................................... 22

3.4 Ignition system .................................................................................................................... 22

3.5 Carbon footprint of abatement systems ............................................................................... 23

3.6 Conclusion, recommendation .............................................................................................. 24

4 Dispersion model of odours in the case study of iron foundry Finland ..................................... 28

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Appendixes

APPENDIX 1 Mass and energy flow calculation of thermal regenerative incinerator

system for a Finnish iron foundry

APPENDIX 2 Cost calculations of HAPs abatement systems for a Finnish iron foundry

(biofilter, thermal oxidation and adsorption)

APPENDIX 3 Mass and energy flow calculation of thermal regenerative incinerator

system for a Finnish cupola furnace melting

APPENDIX 4 Cost calculations of HAPs abatement systems for a Finnish cupola furnace

melting (biofilter, thermal oxidation and adsorption)

APPENDIX 5 Schematic diagram of Nederman adsorption design

APPENDIX 6 Schematic diagram of CTP regenerative thermal oxidation incinerator

APPENDIX 7 Schematic diagram of Reinluft biofilter

APPENDIX 8 Description of adsorption chemical used in Nederman abatement system

APPENDIX 9 Dispersion model of odours in a case study in Finland, Total odour

emissions without abatement systems

APPENDIX 10 Dispersion model of odours in a case study in Finland, Odour emissions

with abatement system Biofilter

APPENDIX 11 Dispersion model of odours in a case study in Finland, Odour emissions

with abatement system RTO

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Abbreviations used

Adsorption Adsorption is a physical phenomenon in which gaseous component, called

adsorbate, are removed from gas stream by adhering to the surface of a solid

material, and called adsorbent.

Amine Amine gases that are used to harden cores by gas injection

AX AX Consulting Ltd www.ax.fi, project partner

BAT Best available technology

Biofilter Biological cleaning method to abate odorous VOC gases and odour

compounds by micro-organisms

BTEX benzene, toluene, ethylbenzene, xylene

CO Carbon monoxide

Concentrator An additional pre-treatment method based on adsorption and desorption of

odourus VOC gas to increase the exhaust air concentration

CTP Chemisch thermische Prozesstechnik GmbH

EN European Standard

EPA Environmental Protection Agency

http://www.ctp-airpollutioncontrol.com/, project partner

FID Flame ionization detector

HAP Hazardous air pollutant

hardener = Hardeners are used to harden sand moulds to stand melt metal pouring into

bonding agent mould

IfG Insitut für Giessereitechnik gGmbH www.ifg-net.de, project partner

Meehanite Meehanite Technology Ltd, project coordinator

Nederman Nederman Filtration GmbH www.nederman.com

NOx generic term for the mono-nitrogen oxides NO and NO2

(nitric oxide and nitrogen dioxide).

ou odour unit (ouE/mg3)

ppm parts per million

Reinluft Reinluft Umwelttechnik Ingenieurgesellschaft mbH www.reinluft.de,

project partner

RCO Regenerative catalytic oxidation

Rotor rotating concentrator, wheel type

RTO Regenerative thermal oxidation

SCR selective catalytic reduction

SFS Finnish Standards Association

SWECAST Swedish foundry branch’s institute for research, development, education and

training http://www.swerea.se/

TVOC Total volatile organic compounds, Concentration of TVOCs are presented as

total mass of different compounds (gVOC/m3)

TOC Total organic carbon, Concentration of TOC presented as is presented as total

mass of carbon in compounds (gC/m3)

US United States

VOC Volatile organic compounds

http://www.ax.fi/

http://www.ctp-airpollutioncontrol.com/

http://www.ifg-net.de/

http://www.nederman.com/

http://www.reinluft.de/

http://www.swerea.se/

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Pilot foundries

Iron foundry in Sweden = Swedish iron foundry

Steel foundry (nr. 1) in Germany = German steel foundry (nr. 1)

Steel foundry (nr. 2) in Germany = German steel foundry (nr. 2)

Aluminium foundry in Sweden = Swedish aluminium foundry

Iron foundry in Germany = German iron foundry

Steel foundry in Finland = Finnish steel foundry

Aluminium foundry in the Netherlands = Netherlands aluminium foundry

Aluminium foundry in Austria = Austrian aluminium foundry

Cupola furnace iron foundry in Finland = Finnish cupola furnace iron foundry

Iron foundry in Finland = Finnish iron foundry

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1 Aim of the report

The aim of this report is to provide a summary of experience gathered during the

piloting periods of the different odourless abatement systems and to describe the

performance of foundry odour control. The report includes the description of the

abatement systems, the feasibility, the performance and the carbon footprint of

abatement systems. In addition to the report summaries, technical possibilities of

foundry odour control and the cost assessment of control action will be presented in

total costs and nominal prices (€/ton, €/a).

2 Pilot studies of abatement systems

In this chapter, the outcomes of four different piloted cases will be explained. The first

case is the regenerative thermal oxidation system and the summary conclusion report

of RTO (case 1) is explained in chapter 2.1.1. The second case is the biofilter systems

and the summary conclusion report of biofilter (case 2) is explained in chapter 2.1.2.

The third case is the adsorption system and it outcome conclusion is explained in

chapter 2.1.3.The fourth case is the ignition system and it conclusion is explained in

chapter 2.1.4. Summary table of all pilot studies can be seen in Table 1.

2.1 Content of pilot studies

Case 1: Regenerative thermal and catalyst oxidation and adsorption systems

In VOCless pulping EU Life project (LIFE09/ENV/FI/000568), we have had good

VOC emission abatement results with regenerative thermal oxidation incinerator.

The material properties for the RCO, RTO technologies were already studied in this

previous EU Life VOCless pulping project. Figure of schematic chart of RCO and

RTO systems can be seen in Figure 1. The specific pilot conditions for RTO odour

abatement technique were more or less already defined. The outcomes of the RTO

pilot results were promising in VOCless pulping project, and this is why Case 1 was

selected as one of the cases to reduce other hazardous air pollutant and odours.

The performance and testing applicability of regenerative catalytic oxidation (RCO)

and regenerative thermal oxidation (RTO) were pre-tested to study the efficiency

capacity for odour and hazardous emissions removal. Catalyst feasibility for odour

abatement was pre-tested in a Finnish steel foundry. The results gained from the

pre-piloting determined the BAT RCO and RTO abatement systems for different

foundries. The performance and feasibility of regenerative thermal oxidation CTP

(RTO) odour abatement system was tested in a Finnish iron foundry. The RTO pilot

methods were developed and manufactured by CTP.

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Figure 1. Schematic figure of RCO and RTO systems

Case 2: Biofilter technology system

The biofiltration is due to its natural principle the most energy-saving waste air

treatment technology. The method consists of a biological process which is based on

the activity of microorganisms-comparable with biological waste water treatment

plants. Therefore, the operating pressure and temperature are corresponding to

ambient conditions. The elimination of pollutants is carried out by microorganisms

inside the biofilter. This means that there is no need of additional energy. As the used

filter material is based on renewable resources (wood, compost, bark, etc.) the whole

process is CO2-neutral. All in all, the tests have shown that biofiltration is a suitable

and cost-effective technology for the waste air treatment in foundries.

This case was chosen to be part of Odorless casting project because it has proven good

VOC abatement capacity in the VOCless pulping previous EU Life project

(LIFE09/ENV/FI/000568).

The performance and feasibility of the two biofilter odour abatement systems were

tested in two German steel foundries. Schematic figure of the biofilter pilot system

can be seen in Figure 2. Both of the biofilter pilot methods were developed and

manufactured by Reinluft. The measurements were carried out by Reinluft.

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Figure 2. Schematic figure of biofilter system

Case 3: Adsorption filter system

Adsorption filtration system is based in a way on a returned adsorption material

feeding system where dust or a granulated type additive is sprayed in the exhaust flow

and thus spread on the bag filter surface to adsorb gas components with big molecules

from the off-gas. The existing filter plant already used for the purpose of dedusting the

pouring line exhaust stream can be applied. The additive adsorbent is sprayed and thus

mixed in the uncleaned raw gas.

The adsorption materials applied can be quite typical ones because of high molecular

weight substances from the degradation process on moulding lines. Activated

charcoal, limestone, brown coal, and zeolite materials can be used. The adsorption

reaction takes place in the additive layer on the filter bag material where adsorbent

lays between cleaning pulse periods. The reaction time is sufficient using a normal

bag filter loading factor of 1 m3/m

2 min corresponding to 17 mm/s face velocity

offering sufficient delay time with the layer thickness of 2 mm. By using recirculation

of once filtered adsorbent, one can easily build a sufficient adsorbent layer and, thus,

saving material cost. A recirculation rate as high as 9/10 can be applied. The pilot test

was carried out in a steel foundry. Nederman was responsible for the design and

implementation of the pilot tests and IfG carried out the efficiency measurements of

the adsorption pilot plant. Adorption system of Nederman technology can be seen in

Figure 3.

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Figure 3. Piloted adsorption system is consisting of bag filter and adsorbant

Case 4: Ignition system

IfG has developed a simple and robust system to elongate the burning phase of gas

emission of a cast flask. The invention uses the fact that the pouring gas only at the

beginning of the cooling of the cast is energetic (“fat”) enough to sustain an

auto-oxidative burning process. Most of the time, the gases are being emitted from the

mould into the surrounding atmosphere without generating a flame. By this, CO2 and

water are not the main reaction products but hydrocarbons, phenols and other

odourants. IfG found out that one has not to fatten up the pouring gas to improve the

burning but to introduce the ignition energy into the premixed gas. Doing so, the

burning can be elongated from less than 5 % to about 50 % of the whole emission

time. As a consequence, the odour emissions are remarkably diminished – more than

90% were measured under suitable conditions. The reduction is not related linearly to

the burning time as the gas emissions naturally decrease – described by an exponential

function.

The performance and feasibility of ignition odour abatement system pilot test was

carried out at a cupola and induction melted green sand moulded iron foundry. The

piloting period differs from the other systems. The assembly of the ignition system

was done by research partner staff (IfG) only. The foundry staff does not know the

detailed instructions of the ignition system. The test ignition system was assembled

and reassembled on each flask during production in a continuous row. This means that

ignition piloting took place 2-3 times in a period of one day. The cleaning efficiency,

odour balance effect and feasibility tests of the system were investigated

simultaneously during these periods. The pilot test (schematic figure can be seen in

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Figure 4) design and implementation and efficiency measurements were carried out by

IfG.

Figure 4. Schematic figure of ignition system

2.2 Piloted test description

The efficient functioning of the four pilot tests was assured by continuous monitoring,

weekly visits, and performance measurements. The technical monitoring and

performance measurements were carried out by AX Consulting, IfG, Nederman,

Reinluft, CTP and Meehanite.

The piloting periods of pilot plants were lasted from 4 weeks up to 8 weeks. In

addition to TOC, VOC and odours, the following parameters were recorded with the

help of continuous measurements: raw and clean gas flow rates, temperatures,

humidity and air flows of the industry units. Continuous monitoring of selected

parameters took place via modem connection to a PC based office recorder. In each

visits the temperature of the air and humidity of industry units, the odour

measurements samples, and pilot clean and raw gas flow were also measured and

recorded. The correct run modes of pilot plants were controlled in order to gain valid

comparable data.

Additionally, standard short-term emission measurements and other control measures

were carried out during the piloting period to insure that the cleaning efficiency of the

odour abatement systems will stay stable. These measurements periods can be found

in the measurement reports of each foundry systems in relevant Action 11-14 reports.

The measurements of the odour and odorous VOC cleaning and thermal efficiency

levels revealed that the pilot plants were functional and stable (see Table 2-5).

The outcome of the four cases odour and hazardous emission cleaning techniques will

be presented in chapter 2.1.

The odorous emission was carried out in compliance with the EN 13725:2003

standard. The TVOC concentration measurements were carried in continuous FID

measurements according to the EN 13526 and in mass concentration definition

according to the US/EPA method 25. The air flow measurements were carried out

according to the SFS 5512 standard.

Battery

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Table 1. Tested abatement systems in pilot plants in time order. The year indicates

when the measurment was carried out

Odour balance

measurement of foundries Pilot plant installations for different cleaning technologies

Pilot foundries Partner responsible Odour panel Chemical

analyses

RCO RTO C+RTO Biofilter Ignition Adsorption

Finnish Steel AX/Meehanite 2013 2013 2012*

*pre-tested

Finnish Iron AX/Meehanite 2013 2013 2013 2013 2013

German Steel IfG 2012 2012 2012 2012

German Steel Reinluft x x 2014

German Iron IfG 2013 2013 2013

Austrian

Aluminium

CTP/IfG x x 2012

Nederland

Aluminium

IfG 2014 2014

Swedish Iron AX,Swerea, Meehanite 2012 2012

Swedish

Aluminium

AX,Swerea, Meehanite 2012 2012

Finnish Cupola

furnace

AX, Meehanite (odour

balance for

cupla melting)

2014 2014

Total 7 odour emission balances

+ cupola

3 pilot tests + 1 pre-test 2 pilot

tests

1 pilot

test

1 pilot test

2.3 Results of abatement systems

The results and reports of the piloting sites are presented in Action 11-14.

The abatement techniques are explained in Action 15 Feasibility Study of Techniques

report. In this report, only conclusions and recommendations will be gathered for the

four odour abatement techniques.

Adsorption and ignition odour and hazardous emission technologies could not reach

as high cleaning efficiency as RTO and biofilter odour technologies during the test

periods. However, odour abatement efficiency was successful enough in the ignition

system to encourage furthers improvement of the technology. It is expected that the

ignition system will be further developed to improve hazardous emissions cleaning

efficiency (more about the results in chapter 2.1.4) e.g. existence of continuous flame

during all cooling stages.

Adsorption abatement efficiency was low possibly due to the low raw gas

concentration. Higher concentration improves removal efficiency as previous testing

results have shown (more about the results in chapter 2.1.3).

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Biofilter could reach about 85% sufficient odour cleaning efficiency with a pre-treated

scrubber installation. This system is a proving abatement technology in low TVOC

concentration sources (more about results in chapter 2.1.2).

The cleaning efficiency was the highest in the case of regenerative thermal oxidation.

The small pilot thermal oxidation ignition system in the pilot studies was working in a

71-95% of odour and a 91-99.5% of TVOC efficiency level. The full size RTO system

with rotor concentrator installation and the 3-bed RTO showed an effective best

available technology (BAT) solution (more about the results in chapter 2.1.1) with the

cleaning efficiency of 99.5 % and the common full size 2-bed RTO reaches efficiency

of 97-98 %.

The results of all the offers and simulations for BATs odour and hazardous air

pollutant emission controls are described in this report (Chapter 2.1.1-2.1.4). The

results illustrate the running cost of these installations (RTO oxidation, biofilter,

adsorption, ignition) giving reliable cost estimations for abatement cases in real use.

The accuracy of the results can be considered accurate enough (+/- 10 %) because of

the existence of normal running conditions for these cleaning technology applications

in the pilot tests.

2.3.1 RTO oxidation system

Regenerative catalytic and thermal oxidation (RCO, RTO) systems were pre-piloted to

abate TVOC emissions at a Finnish steel foundry (2012). The outcome of pre-piloting

showed that within the accuracy of the measurement, the catalytic activity did not

suffer during the pilot test period. This shows that it is possible to protect the catalyst

from catalyst poisons (aging phenomena) and fouling in this application by use of a

dust filter and selection of the right catalyst. It is recommended considering using

regenerative catalytic oxidization abatement system as well, but right conditions

needed to be defined with care in order to protect the catalyst system.

Regenerative thermal oxidation (RTO) system was tested to abate odour and TVOC

emissions as full size at an Austrian aluminium foundry, and a Finnish iron foundry.

Table 2 illustrates the overall cleaning and thermal efficiency of thermal oxidation

system at both sites.

The pilot thermal oxidation abatement technology reached a cleaning efficiency of

odour between 90 - 95 %. This level seems to be high enough in the case of present

odour emission levels in exhaust gases. Odour concentrations of raw gases (before

thermal oxidation) were on the level of 512-4340 ouE/m³. The odour concentrations

after thermal oxidation decreased to 51-217 ouE/m³ at the both pilot plants. This

cleaning performance provides sufficient guidelines for emission limit values that will

guide decision makers set threshold limit in the near future to improve health of

foundry staff and neighbors of foundry surroundings.

In the case of a Finnish iron foundry, the total odour cleaning efficiency remained less

efficient because of the system design was a prototype. Similar 3-bed RTO cleaning

system was offered for a Finnish iron foundry by CTP (see Figure 5) and this system

has a 95% of odour cleaning efficiency. The PI-diagram is in Appendix 6. An initial

concentrator rotor before the thermal oxidation chamber improves the efficiency

roughly with an additional 5-10 %.

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In the case of full size aluminium foundry, the odour abatement efficiency was 95%

and 99.5 % of TVOC compounds. The full size plant shows that CTP´s technology

can be applied to successfully remove odour particles from the foundry industry.

The thermal efficiency of pilot thermal incinerator was 95 - 97 % which is efficient

enough. In the pilot plant this feature was not in focus. The thermal efficiency depends

usually on the optimization of the heat recovery construction (more regenerative

mass). The higher efficiency is needed, the higher investment fan power is required.

The higher the thermal efficiency, the less heat energy is consumed in the oxidation

process. The optimal area is between 93-97 %. The thermal incinerator consumes

more energy (operating chamber temperature usually 850 oC) than catalyst

incinerators (250-350 oC).

The preheating of the raw gas is performed by a heat exchanger. In CTP pilot unit the

regenerative heat exchanger is made of ceramic honey-comb cubes so that wholes are

forming similar structure as used in ceramic catalyzers. This structure has very

effective heat transfer power offering efficiency up to 95 % depending of the whole

size and gas velocity. This type of heat exchanger could reach in our pilot tests

autothermic operation point of as low as 0.91 gVOC/Nm3. Autothermic point is a

minimum VOC concentration where incineration unit doesn’t need any additional

energy to keep the oxidation temperature on the needed level.

Continuous monitoring of process parameters and emission concentrations and

cleaning of the abatement system need to be ensured.

The pilot test approved the applicability of CTP RTO-SCR cleaning system for

foundries. The SCR phase was investigated because of high N-compound contents of

amine gases in cold box core production. The NOx reduction of almost 100 % was

achieved and NOx concentration stayed at the low level of 2.03 mg/m3 (1 ppm).

Table 2. Cleaning efficiency and thermal efficiency of piloted foundry

regenerative thermal oxidation 3-bed and 2-bed systems

Pilot site

TVOC cleaning

efficiency, %

Odour cleaning

efficiency, %

Thermal

efficiency, %

Austrian Aluminium foundry

with phenol resin and amine

hardener (3-bed)

99.5

95 95

Finnish Iron foundry

with phenol moulding

phenol+amine cores (2-bed)

95

(90…98,5)

>90

(71.5…96)*

97

(90…98.5)

*Odour samples have been neglected because of high discrepancy in typical results.

Other case measurements are evaluated as more reliable ones, instead of the piloted

iron foundry measurement results.

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Figure 5. Full size 3-bed CTP RTO system

2.3.2 Biofilter system

The function of biofilter is based on micro-organisms (bacteria), which is laid on

organic carrier material (bed material) like wood, chips, peat, bark etc. Biofiltration

consists of a sorption phase of pollutants on a carrier surface and a subsequent

degradation phase by micro-organisms, which are settled in an aqueous phase on the

carrier substance. Unlike bioscrubbing, biofiltration is performed in two

simultaneous steps (sorption and degradation). While inlet gas is led to flow slowly

through the bed, micro-organism has sufficient time to catch odorous

VOC-molecules and convert it to water and carbon dioxide. Reason of slow flow is

e.g. methane is one of the inert gas molecules that bacteria cannot destruct easily.

Organic micro fauna does not produce methane itself.

The biofilter pilots were carried out in order to find the most cost and odour efficient

technique / techniques for the exhaust gases for foundry industries.

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The overall TVOC elimination capacity of the biofilter showed an efficiency of 75 %

at an average filter space loading of 110 m³/(m³h) in a German steel foundry (nr. 1)

(2012). The odour reduction efficiency was 85% based on the results.

In spite of high area demand of biofilter, it can be constructed like a tower, see full

size biofilter construction in Figure 6. The PI-diagram of biofilter system is in

Appendix 7.

The overall elimination capacity of the biofilter showed an efficiency of 52 % at an

average filter space loading of 90 m³/(m³h) and the odour reduction efficiency is

calculated to 95% based on a German steel foundry (nr. 2) (2013) results. The overall

odorous VOC elimination capacity was not as high as expected, but this is due to the

high amount of aromatic compounds in the degradation products of cold-box moulds.

Odorous VOC concentrations of raw gas (before biofilter) were on an average

74 mgVOC/m3 in a German steel foundry (nr. 2) (2013), and on an average 9.5

mgVOC/m3 in a German steel foundry (nr. 1) (2012) raw gas. VOC concentrations

after biofilter plant in a steel foundry (nr. 1) (2012) were 11.6 mgVOC/m3

(corresponding to 9.5 mgC/m3). This was set up as the target emission level

correlated with odour emission in the project. The steel foundry cases resulted to a

higher raw exhaust concentration. This requires a better cleaning efficiency, but pilot

studies showed that most odours can be degraded and removed biologically with

high level of efficiency in steel foundries. Summary of biofilter cleaning efficiency

can be seen from Table 3.

Table 3. Cleaning efficiency of piloted biofilter systems

Pilot site

Odorous VOC

cleaning

efficiency, %

Odour

cleaning

efficiency, %

German Steel foundry (nr. 1) in 2012:

Induction melting, automatic green sand molding

furan sand cores

75 85

German Steel foundry (nr. 2) in 2013:

Induction melting, automatic green sand molding

52

(36-68)

95

(93-98)

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Figure 6. Biofilter full size plant at a German steel foundry

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2.3.3 Adsorption system

The pilot system works with the adsorption of the odours in the surface of active

materials like active carbon or other suitable adsorbents, see mineral Minisorb

analysis in Appendix 8. The powdery additive is fed with a variable dosing system

continuously in the raw gas. The adsorption takes place during the flow of the

additive in the raw gas up to the filter media. At the filter media, consisting of needle

felt, there is a growing dust cake that is online cleaned off.

The cleaning system is a pulse jet system that works online during the continuous

filtration process. For better utilization of the additive, it is recirculated. This means

the filter is cleaned of and 9 from 10 parts of the dust is brought back in the raw gas

for further reaction and for a better usage of adsorbant. The smaller part is brought to

the waste container. Without recirculation only 10% of the additive is used. With

recirculation it is increased to above 90%. A higher recirculation ratio of for example

20 to 1 does not make sense, since in large technical plants the material flows would

be very high. See the pilot plant tested in Figure 7 and the process and

instrumentation diagram in Appendix 5.

The cleaning odour efficiency was very low (see Table 4), because of the very low

raw gas concentration. With higher concentration, the removal efficiency would

increase significantly, because the clean gas values stay almost in the measured level

independent of the raw gas. This effect could be regarded as normal and has proven

normally in applications with dry sorption of raw gases.

Table 4. Cleaning efficiency of piloted adsorption system

Pilot site TVOC cleaning

efficiency, %

Odour cleaning

efficiency, %

German Steel foundry (nr. 1):

Induction melting, automatic green sand

molding, furan sand cores

46

(42-50)

37

(12-85)

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Figure 7. Full size adsorption system

2.3.4 Ignition system

The prototypal character of the IfG-ignition system has been widely described in

Action 15 Feasibility Study of Techniques report. New and innovative ignition frame

abatement system was designed to reduce odour and hazardous emissions in

foundries. Ignition frames were installed on the flasks in pouring line at once after

pouring occurred to reduce emissions right from the source of release. The odour

cleaning efficiency level was in a range of 65 %. During this method a spark initiates

an oxidation reaction of the harmful substances of the molded gases consisting HxCy

(hydrocarbons as well as hydrogen and CO). The sparks generate the ignition energy

which starts the oxidation reaction. Within this reaction the gases would be converted

into the products of water and carbon dioxide under exothermic conditions.

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The ignition pilot test was carried out at a green sand moulding steel foundry, in

Germany. The piloting period differs from the other systems. The assembly of the

ignition system was done by research partner staff (IfG) only. The test ignition

system was assembled and reassembled on each flask during production in a

continuous row. The cleaning efficiency, odour balance effect and feasibility tests of

the system were investigated simultaneously during test periods. The ignition system

is presented in Figure 8. The pilot test design and implementation and efficiency

measurements were carried out by IfG.

Results of pilot ignition system showed an overall ineffective TVOC and odour

eliminating results due to early stage of prototype development (see Table 5) but a

significant conversion of hazardous emission compounds, especially the

concentration of benzene was reduced on average of 50 % from the original

emission. The CO concentration was likewise reduced by approximately 40 % with

the aid of the pilot system. In the reality the ignition system cannot keep up the flame

in the concentration under LEL concentration. This means the “blue CO flame” of

the cooling flasks will be extinct in one-two hours after pouring which roughly

corresponds not more than half HAPs emissions during the all cooling period

(referring to emissions measurement of a closed flask in a Finnish iron foundry).

Thus only 25 % of odour emissions can be abated by the ignition systems of IfG

type.

Table 5. Cleaning efficiency of piloted ignition system

Pilot site

Odorous TVOC

cleaning

efficiency, %

Odour cleaning

efficiency, %

German Iron foundry:

induction melting, green sand

Cold box with acid scrubber cores

29

50

(34-54)

German Iron foundry: reality with 1-2

hours flaming period only in cooling

induction melting, green sand

Cold box with acid scrubber cores

15 25

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Figure 8. Pilot ignition system. The flames were in the exit of venting openings

where the high voltage ignition electrodes ignited flammable gases.

3 Cost analysis, results and conclusion

In the following conclusion the cost calculation data has been stated and compared

uniformly. The costs of the systems are based on several hundreds of inquiries, offers

and market outcomes and specified offers from CTP, Reinluft and Nederman. The

utility cost is based on actual Northern European price level. The cost, result and

conclusion are made with 3 different abatement systems (biofilter, RTO and

adsorption) for a Finnish iron foundry and the cupola furnace of a Finish iron

foundry (only for cupola emissions)

Each simulation case is defined by HAPs emission concentration and airflow.

Emission points, average air flows and HAP concentrations are presented in

Appendixes 1-4. The production takes place in 2 shifts, but in a Swedish iron

foundry in 3 shifts without weekend working. Nominal odour production can be seen

in Table 6 below.

Table 6. Nominal odour production (MouE/ton casting)

Pilot foundry

types

Odour

(ouE/m3)

Airflow

(Nm3/h)

ton/a Nominal odour

emission /production

(MouE/ton casting)

Nm3/h/ton

Steel (nr. 1) in

Germany

217 215 000 4 800 37* 45*

Steel in Finland 238 470 000 8 300 52 57

Aluminium in

Sweden

57 115 000 2 310 11 50

Iron in Germany 176 180 000 4 700 26* 38*

Iron in Finland 385 106 000 3 620 43 29

Iron in Sweden 2 366 1 700 000 20 000 1 172 86

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*results are based on assumed (not measured) ventilation rates only.

Note: not all of the pilot tests (6 out of 9) are included here due to non-available data.

Investment, energy and maintenance cost calculations based on the offers from CTP,

Reinluft and Nederman for sources of an induction melting hand moulding with

phenolic resin, cold box core. The cost calculation results of abatement systems can

be found in Appendix 2 and 4.

More detailed explanations of the RTO, Biofilter and adsorption outcomes for the

iron foundry Finland and cupola furnace melting process can be seen in Feasibility

Study of Techniques in Action 15 and emission measurement reports.

3.1 RTO oxidation system

According to the results of the RTO simulation (Appendix 1), the energy cost for a

Finnish iron foundry is about 112 000 €/a (Appendix 2). The energy cost of a thermal

oxidizer incinerator for the Cupola furnace melting was estimated to be 15 300 €/a

(Appendix 4) because of high presence of carbon monoxide. 99 % cleaning

efficiency and 96 % thermal efficiency of the thermal oxidizer incinerator has been

used in the RTO simulation following the data given by CTP offer in the iron

foundry. In cupola furnace melting process, 99.5 % cleaning efficiency and 96 %

thermal efficiency were used based on the CTP offer.

The annual cost of regenerative thermal oxidizer incinerator is based on calculations

from the investment cost, annual investment cost, maintenance and energy cost

(Appendix 2 and 4).

The annual total cost of the full-sized RTO + concentrator plant for iron foundry was

estimated to be 280 000 €/a (App. 2). The net cost annual destructed HAPs was

estimated to be 6 300 €/ton (App. 2). As a result of the cost of iron production would

increase by 77 €/ton (production net tons). It is 2.7 % increase of production cost.

The annual total cost of an RTO abatement system for the cupola furnace melting

process was estimated to be 69 000 €/a (App. 4). The net cost annual destructed

HAPs was estimated to be 39 500 €/ton (App. 4). The cost of iron production would

increase by 10 €/ton. It is 0.4 % increase of production cost.

3.2 Biofilter system

The annual costs of biofilter systems are based on calculations from the total and

annual investment, maintenance and energy costs according to the market prices of

the type of biofilters piloted and illustrated in Figure 6.

The annual total cost of the full-sized biofilter plant for the iron foundry was

estimated to be 170 000 €/a (App. 2). The net cost annual destructed HAPs was

estimated to be 4 500 €/ton (App. 2). As a result of this the cost of production of

iron would increase by 47 €/ton (production net tons). It is 1.6 % increase in

production cost.

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The annual total cost of a biofilter for the cupola furnace melting was estimated to be

45 000 €/a (App. 4). The net cost annual destructed HAPs was estimated to be

34 200 €/ton (App. 4). The cost of the production of iron would increase by 6 €/ton.

It is 0.3 % increase in production cost.

3.3 Adsorption system

The annual costs of adsorption systems are based on calculations from the total and

annual investment, maintenance and energy costs according to the market prices of

the type of adsorption piloted.

The annual total cost of the full-sized adsorption plant for induction melted hand

moulded phenolic resin cold box core iron foundry was estimated to be 688 000 €/a

(App. 2). The net cost annual destructed HAPs was estimated to be 20 000 €/ton

(App. 2). As a result of the cost of iron production would increase by 190 €/ton

(production netto tons). It is 7 % increase of production cost.

The annual total cost of an adsorption system for the Cupola furnace melting process

was estimated to be 105 000 €/a (App. 4). The net cost annual destructed HAPs was

estimated to be 79 600 €/ton (App. 4). The cost of iron production would increase

by 15 €/ton. It is 0.7 % increase of production cost.

Adsorption system odour reduction efficiency is regarded low because of low waste

gas concentration. In higher concentrations, the odour removal efficient would

increase as well. It can be concluded that the adsorption cleaning technology cannot

be considered as best available technology in the Odorless casting project due to low

odour cleaning efficiency. In principle, even with two sequential orders, the cleaning

efficiency of adsorption technology would not exceed 75 %. Therefore, costs are

considered to be out of range for foundry businesses.

3.4 Ignition system

Ignition system is not included in the cost calculation conclusion report but it is

interesting to give a summary cost calculation outcome of this system as well. This

will give a better overview for the interested parties and decision makers about all

the systems that were tested in the Odorless casting project

Ignition system cannot be regarded as a complete odour abatement system because it

does keep the oxidation flame on when flammable gases appear above ignition

concentration. That is the case in pouring and in the beginning at cooling stage

(1-2 hours after pouring). Still the cleaning efficiency is at maximum on the level of

50%.Ignition system tested can reach roughly to the cleaning rate of 25 -30 % of all

mould origin emissions during the pouring and cooling phases.

The annual total cost of the full-sized ignition plant for an iron foundry estimated to

be 69 200 €/a with the extra work of a fourth of man power and cost assumption of

ignition frames of middle size to be 2500 € each. As a result of the cost of the iron

production would increase by 16 €/ton (production net tons). It is 0.6 % increase of

production cost.

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3.5 Carbon footprint of abatement systems

The difference in CO2 equivalent emissions from abatement systems compared with

direct release can have two outcomes.

In case, the difference is negative. In this case, the negative value indicated there are

overall climate change benefits in abatement system compared with direct release of

the VOCs of these compounds in question.

In case the difference is positive. In this case, the positive value indicated there is

overall climate change harm or limitation in abatement system compared with direct

release of the VOCs of these compounds in question.

The default values of odorous VOCs spanning rage (GWP 100 year) between 0.1 and

10 for hydrocarbons if the odorous VOC of interest is not listed or referenced from

scientific data. The low value of spanning rage can be explained by the fact that most

of the VOCs atmospheric lifetimes are very short (from minutes to hours in most

cases) (Atkinson 2000 – Atmospheric Chemistry of VOCs & NOx).

Table 7. Carbon footprint GWP, 100 year of a Finnish iron foundry

Iron foundry

RTO + ROTOR

ton CO2 eq. emission of RTO system

ton CO2 eq. emission of RTO + TVOCs

Difference between RTO system and direct TVOCs CO2 eq.

570 650 510

Biofilter

ton CO2 eq. emission of biofilter system

ton CO2 eq. emission of biofilter system and TVOCs

Difference between biofilter and direct TVOCs CO2 eq.

270 360 220

Adsorption

ton CO2 eq. emission of adsorption system

ton CO2 eq. emission of adsorption system + TVOCs

Difference between adsorption system and direct TVOCs CO2 eq.

110 200 60

It can be seen from Table 7 that the difference in CO2 equivalent emissions from

abatement systems compared with direct release to the atmosphere indicated that all

cleaning systems would be more harmful to operate in order to clean odours and

odorous VOC emissions than allowing untreated emission directly to the atmosphere if

we consider environmental aspect and global warming.

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Table 8. Carbon footprint GWP, 100 year of cupola furnace in Finland

Cupola furnace

RTO

ton CO2 eq. emission of RTO system

ton CO2 eq. emission of RTO + TVOCs

Difference between RTO system and direct TVOCs CO2 eq.

60 1700 -990

Biofilter

ton CO2 eq. emission of biofilter system

ton CO2 eq. emission of biofilter system and TVOCs

Difference between biofilter and direct TVOCs CO2 eq.

50 1690 -1000

Adsorption

ton CO2 eq. emission of adsorption system

ton CO2 eq. emission of adsorption system + TVOCs

Difference between adsorption system and direct TVOCs CO2 eq.

160 1810 -890

It can be seen from Table 8 that the difference in CO2 equivalent emissions from

abatement systems compared with direct release to the atmosphere indicated that all

cleaning systems would have an overall climate change benefit to operate the systems

in order to clean odours and odorous VOC emissions than allowing untreated emission

directly to the atmosphere if we consider environmental aspect and global warming.

3.6 Conclusion, recommendation

Conclusions and recommendation are based on the outcomes of the Odorless casting

pilot tests and the outcomes of the specific offers made for an iron foundry and

cupola furnace melting in Finland. The offers are for 3 different abatement systems.

The systems are biolfiter, regenerative thermal oxidation and adsorption

technologies. In iron foundry Finland, additionally, the ignition system was listed

into the cost comparison (Chapter 3.4 and Table 9.) but it is only for representative

proposal.

Cost efficient abatement technology in whole iron foundry in Finland

The most cost-efficient abatement technology for the waste gas treatment emissions

is biofilter. It is based on the cost comparison results (Appendix 2) and the increase

cost of production due to investment (Table 9). The relatively low odorous VOC

concentration levels fits well for biofiltration. The technical odour cleaning

efficiency can be designed on the level of 80-90 % (VOC 50-70%) and it is low

compared to the RTO of 99 – 99.5 %, which can be achieved in practice with 3-bed

RTO system with concentrator. The oxidation system with two beds achieves the

cleaning efficiency of 97 % and with three beds or continuously changing bed

structure can achieve 99 % in practice. The efficient cleaning system of regenerative

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thermal oxidation is tested technology and fits for the purpose but higher investment

costs make the system 20-30 % more expensive with a rotor concentrator system. In

case the source concentration rises over the level of 500 mgHAP/m3 the RTO system

is recommended. Abatement systems cost comparison can be seen from an iron

foundry offer (Appendix 2).

Cost efficient abatement technology in Cupola furnace melting in Finland

The most cost-efficient abatement technology for the waste gas treatment emission is

RTO in case high CO concentration is present. It is based on the cost comparison

results (Appendix 4) and the increase cost of production due to investment (Table 9).

However, CO measured source concentration was 18 000 mg/m3. The concentration

threshold where CO emission is considered toxic to humans is 35 ppm (43.2 mg/m3);

therefore it is recommended to treat this high amount of CO. In principle with higher

concentration the more economical the thermal oxidation becomes than catalytic

oxidation system. Abatement systems cost comparison can be seen from the cupola

furnace melting offer (Appendix 4).

The adsorption system seems to be too expensive compared to oxidation and biofilter

because of high deposit costs. The system still needs to be further developed for

foundry odour control purposes.

Table 9 also indicates the cost level increase of the foundry production in case of

odour abatement invest are obligatory for the future operation. The cost increase is

50 – 100 €/casting tons, which corresponds at minimum to 1.5 - 3 % in production

costs. In case of one shift, the operation cost rises to double 3 - 6 % compared to

normal operation time where operation cost rises to 1.5 – 3 %.

In Europe there are more than 4 000 foundries. Most of them locate in city areas or

next to them. It has been estimated that 10 – 20 % of foundries cause severe odour

and HAP emission problems. The claims on foundry odours are often met in the

surrounding. In case of a Finnish iron foundry is regarded as medium size foundry

with odour problems to be abated and they are in Europe 600 foundries. They would

have to invest more than 700 million € which would cause with the running costs an

annually increase of production costs of 120 – 150 million €.

Table 10 reveals the system performance in cleaning efficiency. Oxidation has the

highest efficiency of 99 % (three bed or continuously revolving bed system), biofilter

up to 85 %. Oxidation and biofiltration are the two main systems compared also with

the cost of elimination of emissions. The 75 % of adsorption is still a bit imaginary

goal but technically possible. In the case where high cleaning efficiency i.e. low

emissions are needed RTO is recommended. The pilot foundry example of an

aluminium foundry pointed out that casting production can be operating in densely

populated areas.

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Table 9. Annual total cost of biofilter, RTO or adsorption cleaning systems at iron

foundry and cupola furnace melting in Finland

HAPs emission

source and

Abatement system

applied

Annual total cost

of HAPs

abatement system

Increase of the cost

of the casting/melt

due to the use of

HAPs abatement

system

Increased cost

of production

in %

Annual

production

(ton/a)

and

cost of

castings/melt

(€/ton)

Unit €/a €/ton %

Iron foundry

(castings)

3620 ton/a

2900 €/ton

Biofilter 170 000 47 1.6

Regenerative

thermal oxidation 280 000 77

2.7

Adsorption 688 000 190 7

Ignition 69 200 16 0.6*

Cupola furnace

(melt)

7200 ton

2300 €/ton

Biofilter 45 000 6 0.3

Regenerative

thermal oxidation 69 000 10

0.4

Adsorption 105 000 15 0.7

*assumption only

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Table 10. The cleaning efficiency and amount HAPs destructed of RTO, biofilter

and adsorption abatement systems at iron foundry and cupola furnace melting in

Finland.

HAPs emission

source and

Abatement system

applied

Cleaning

efficiency of

HAPs abatement

system

HAPs destructed

of abatement

system

Annual cost

per destructed

mass of HAPs

Annual

production

(ton/a)

and

cost

production

(€/ton)

Unit % ton/a €/kg HAPs a

Iron foundry 3620 ton/a

2900 €/ton

RTO 99 44 6.3

Biofilter 85 38 4.5

Adsorption 75 34 20

Ignition ~25 11 6.3*

Cupola furnace 7200 ton

2300 €/ton

RTO 99 1.8** 39

Biofilter 85 1.5** 30

Adsorption 75 1.3** 80

*assumption only **HAPs without CO

***as BAT technology for cupola emission abatement is regarded a system of

CO afterburner + rapid cooling + bag filter

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4 Dispersion model of odours in the case study of iron foundry Finland

Estimation of odour emissions was made in a case study in Finland at an iron foundry.

Calculations were made with SoundPLAN dispersion model with AUSTAL2000

interface. AUSTAL2000 is a three-dimensional Lagrangian particle dispersion model,

which uses actual metrological data and topography of calculation area. AUSTAL2000

is also mesoscale reference model for odour dispersion according to the German

guideline “GIRL”.

Odor assessment is based on the concept of the so called odor hour. An hour is marked

as odor hour if there is a clear odor perception in at least 10% of the time. The

frequency of odor hours is always expressed as percentage of the total number of

hours. The value range is 0 to 100; the unit is ’%’.

Calculations were made in three different situations. Total odour emissions without

abatement systems (APPENDIX 9), odour emissions with abatement system Biofilter

with cleaning efficiency 85 % (APPENDIX 10) and odour emissions with abatement

system RTO with cleaning efficiency 99 % (APPENDIX 11). Calculation area was

limited nearby foundry, approximately 1000 X 1300 meters.

The dispersion model, Appendix 9, illustrates the frequency percentage of odour hours

in the foundry surrounding. The existence of odour hours is below the German limit

value of 10 %, which begins to appear just behind the foundry yard. Two industrial

premises in the direction of north and east stay on the odour area. The nearest

accommodation lay further away from the 5 % frequency limit, which cannot any more

be regarded as odorous area.

The Appendices 10 and 11 are calculated in the emission cases of biofilter in use (App.

10 with the cleaning efficiency of 85 %) and RTO in use (App. 11 with the cleaning

efficiency of 99 %). The biofilter results to the frequency of odour hours less than 5 %

on the foundry yard and the cleaning efficiency of RTO is high enough to avoid all

odour perceptions to the level of less than 1 %.

It can be concluded that with the efficient odour abatement measures in foundries can

avoid odour perceptions to the level of acceptance in the surrounding population.

APPENDIX 5

AP

PE

ND

IX 6

APPENDIX 7

APPENDIX 8

Documents

Cost and energy efficiency assessment of odour abatement systems 7_1_15 Action 15