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Newsletter, Issue 2 DECEMBER 2015
ASSOCIATION OF PROFESSIONAL
ENGINEERS OF TRINIDAD & TOBAGO
APETT Chemical Engineering
ASSOCIATION OF PROFESSIONAL ENGINEERS OF
TRINIDAD & TOBAGO
Newsletter, Issue 2 DECEMBER 2015
2
TABLE OF CONTENTS
3
EDITORIAL
ENG. ANNA WARNER
It is refreshing to come across a team of young
Engineers, who have gathered together to con-
ceptualize ways of increasing efficiency of a
power plant. This initiative was led by UTT
Lecturers Dr.. Brian Aufderheide, Dr.Ejae John
and Dr. Solange Kelly, all of whom we com-
mend for guiding our Engineers.
It is equally as admirable to have PPGPL’s
Plant Engineer, Jaime-Ann Babwah, share her
knowledge and expertise on combustion air bal-
ancing and fuel efficiency of a reformer.
Both instances speak to Leadership of our Uni-
versity Lecturers as well as that of our Author-
ity figures in the Industry. Consultants Premod
Varghese and Jane Hughes explain that when
we are committed to elevating the performance
of our people, we must engage them in thinking
and acting outside any perceived limitations.
They elaborate that the more we create oppor-
tunities for others to contribute and participate
in the design and execution of an intervention,
the more ownership they will take.
As we continue on the theme of Leadership, we
look to exemplary Leaders Eng. Maurice Mas-
siah, Senior Ambassador for IChemE TTMG and Eng. Imtiaz Easahak, Chair of APETT
Chemical Division, both of whom have em-
braced the APETT / IChemE merge. Through-
out 2015, APETT / IChemE has hosted two
technical seminars, where increased interest in
our Association is evident by the noticeable in-
creased attendance.
It is no surprise that our falling oil price con-
tinues to be a topic of interest. Our LinkedIn
discussion gives different view points on the
heated topic from our Engineers within Oil &
Gas People.
Special thanks to Engineers Julio Bissessar and
Brandon Joseph, who have not only assisted in
compiling this Newsletter, but have also con-
tributed two articles focused on mathematical
modelling of an ammonia converter as well as
determining safe operating limits of a piece of
equipment.
I would personally like to take this opportunity
to wish every one of our readers a blessed and
merry Christmas and all the best that 2016 has
to offer.
APETT Chemical Engineering Division gra-
ciously welcomes its regular readers as well as
its new readers. To contribute in discussions,
join our LinkedIn group or keep updated with
activities by visiting our website at
www.apett.org
APETT’S Mission
The Association of Professional Engineers of
Trinidad and Tobago
is a learned society of professional engineers dedicated to the
development of engineers and the engineering profession.
The association promotes the highest standards of
professional practice and stimulates awareness of technology and
the role of the engineer in society.
Eng. Anna Warner is currently a Process Engineer II at WorleyParsons, seconded to Atlantic LNG, as part of the Commissioning Team. She has over three years’ experi-ence within the Oil & Gas processing industries, and holds a B.Sc. with Honors in Chemical & Process Engineering from UWI. She has worked as part of FEED, Detailed En-gineering and Commissioning for various Brownfield and Greenfield Projects ranging from offshore and onshore Oil & Gas facilities, to water treatment and LNG plants.
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Message Message Message Message from APETTfrom APETTfrom APETTfrom APETT Eng. Neil Dookie Eng. Neil Dookie Eng. Neil Dookie Eng. Neil Dookie –––– President President President President
Congratulations to the Chemical Division on the publication of their 2nd Edition
Newsletter for this year. The articles and general outlook in this newsletter, are
truly representative of the efforts of the members of this Division, as they have and
continue to show their professionalism in striving to showcase APETT, as an Or-
ganisation of choice. In keeping with APETT’s objectives in promoting the profi-
ciency, knowledge and skill of Professional Engineers, the Chemical Division has
shown through its newsletters, its ability to stimulate awareness of technology and
the role of the engineer in society.
It is therefore in high commendation that I extend to the members of the Chemical
Division, for their participation, research and publication of articles, that not only
benefit engineers, but other professional societies and the general public. It is im-
portant that the members continue to build on the successful newsletter and we an-
ticipate in 2016 and in the future that the strength of the Chemical Division as well
as the other divisions, will continue to attract the growing membership in APETT.
As I close, I extend my best wishes to all members of the Chemical Division, for a
safe, healthy and happy new year.
5
Message from the chemical division (ACE)Message from the chemical division (ACE)Message from the chemical division (ACE)Message from the chemical division (ACE) Eng. Imtiaz Easahak Eng. Imtiaz Easahak Eng. Imtiaz Easahak Eng. Imtiaz Easahak ———— Chair, Chemical DivisionChair, Chemical DivisionChair, Chemical DivisionChair, Chemical Division
I would like to thank the editing team comprising Eng. Anna Warner– our Editor,
Eng. Brandon Joseph and Eng. Julio Bissessar for once again producing a high
quality Newsletter—these young Engineers have demonstrated a tremendous
amount of commitment in ensuring that our bi-annual publication reaches our
readership.
I wish to also congratulate and thank the authors of all articles in this edition as we
continue to showcase local talent in our Chemical and Process Industries. I am
sure you would find these articles very interesting– please do take time to under-
stand the leadership section which focuses on delivering sustainable performance
through our human resource.
I would like to recognise Eng. Maurice Massiah, Senior Ambassador for IChemE–
Trinidad and Tobago and Eng. Dr. Haydn Furlonge—immediate Past President of
APETT, for leading the effort in signing a MOU marking a joint venture between
APETT Chemical Division and IChemE.
Finally, as we continue to experience deflated oil and gas prices in the world econ-
omy, I urge us all to continue to look for opportunities to increase efficiencies
within our own organization as well as continue to build our own competency level.
I would like to wish you all a safe and happy holiday season—may the New Year
2016 bring success to us all!
Imtiaz.
6
GO GREEN INITIATIVE CAPTURING CO2, PRODUCING A BIOFUEL, AND
IMPROVING EFFICIENCY OF A COMBINED
CYCLE POWER PLANT BY: DR. BRIAN AUFDERHEIDE, DR.EJAE JOHN, DR. SOLANGE KELLY, JULIO BISSESSAR A team of UTT students from Process Engineering gathered together to conceptualize ways of making an already efficient combined cycle power plant even more efficient while reducing its carbon footprint. By employing reactive absorption of carbon dioxide from its combustion exhaust, they were able to come up with a viable product for the captured carbon dioxide. The students already had a history of working on In-dustrial Design problems which included: modelling and fitting kinetic parameters for two catalysts in an ammonia converter at Point Lisas Nitrogen Ltd, mod-elling and simulating three dimensional flow in a glass forehearth for Carib Glass Ltd using Finite Dif-ference methods, and design and modelling of various plant processes. The students sought the guidance of three faculty members with expertise in carbon dioxide capture methods, process improvement using exergy analysis, and the use of new Genetically Modified strain of alga that secretes butanol.
Upon reaction with CO2, ethylenediamine forms a
stable CO2-amine gel complex. The ethylenediamine
gel had been tested previously only on a lab scale,
and has the following reversible and highly exother-
mic reaction (Samanta, 2007):
The energy released from the forward reaction was calculated by utilizing advanced methods such as Constantinou and Gani as well as Joback's methods to
firstly estimate the energy associated with the gel complex. Then a heat of reaction analysis was under-taken and the energy released was approximated as 2.3 e9 KJ/hr, making it an essential source for heating of the air entering the combustion chamber (see fig. 2). Chemical structural analysis of these gels also in-dicate that they have a more entangled structural net-work compared to more common organo-gels (Samanta, 2007), so we expect the gels to be stable until we want to reverse them and release the CO2.
The carbon dioxide utilization as a new viable prod-
uct is from Lan and Liao(2011) who genetically
modified the alga, Synechococcus elongates PCC
7942, to secrete butanol from its cells eliminating the
requirement to break down cell walls and lipids as
part of processing a biofuel as is done by non-GMO
alga. The special strain of alga had been used only in
the lab, and no commercial design for butanol pro-
duction had been published.
Every mole of butanol secreted requires four moles of
carbon dioxide (see fig. 1).
Fig. 1 Overall stoichiometry of Synechococcus
elongatus.
7
With this information in hand, the students developed and completed the engineering and financial analysis for
a design to remove CO2 from the exhaust gas which generated heat as it reacted with the ethylenediamine.
This heat was then applied to pre-heat the air entering the combustion chamber (see Fig.2). The captured car-
bon dioxide is then released by using low pressure waste steam from the power plant on the ethylenediamine-
CO2 complex, and then pumped to a butanol production plant.
The turbine and pre-heater was modelled in Aspen HYSYS, and the butanol plant along with a complete fi-
nancial operational model was done in Excel. The financial model included all operational and capital expen-
ditures to calculate a Net Present Value (NPV) and Interest Rate of Return(IRR), with an assumption of a 12
year project life with first two years in construction only. Sensitivity analysis included number of turbines to
retro-fit, conversion rate for butanol production, percent of carbon dioxide absorbed, along with other changes
in prices, etc. The final optimal design had a payback period of less than six years with an IRR in excess of
15% and an NPV greater than 280 million USD.
A complete carbon dioxide assessment was done and a reduction of 0.9 million short tons of carbon dioxide per year was realised. Furthermore, if a cap and trade system was in place, additional annual revenue (combination of reduced penalties with additional credits) of 60 million USD would be generated. Based on their work done on this idea, the students (Shameal Ali, Laura Lewis and Julio Bissessar) were the winners of BP’s Ultimate Field Trip design competition of 2014, second place to the Institution of Engineering and Technology (IET) Present around the World Competition (local finals) and special prize winners for the Prime Minister’s Awards for Scientific Ingenuity 2015. If your company is interested in doing a design project or improving plant processes, please contact Dr. Brian Aufderheide at [email protected],Dr. Ejae John at [email protected] Dr. Solange Kelly [email protected].
REFERENCES
Samanta, S. (2007). Reversible Carbon Dioxide Gels, Synthesis and Characterization of Energetic Ionic Liq-uids, Synthesis and characterization of Tetrazole Monomers and Polymers, Encapsulation of Sodium Azide for Controlled Release. Georgia Institute of Technology. Lan, E.I. and J.C. Liao, 2011, Metabolic engineering of cyanobacteria for 1-butanol production from carbon dioxide, Metab. Eng., 13(4), 353-363.
8
BROWNFIELD MODIFICATIONS THE BALANCING ACT
BY: JAIME-ANN BABWAH, CMRP, BSC. CHEMICAL & PROCESS
ENGINEERING. PLANT ENGINEER AT PHOENIX PARK GAS
PROCESSORS LIMITED.
The Steam Reformer is considered to be the heart of most downstream process plants where hydrogen is used as the synthesis gas. These gigantic units usually have a high operating cost as they typically range from 80 burner units to 260 burner units depending on the hydrogen requirement. Ensuring that your reformer is bal-anced is vital for fuel efficiency and may also identify problems that are present in the Reformer and auxiliary equipment before it impacts plant reliability.
The Steam Reformer is simply a box in which reforming reactions occur.
Methane-Steam Reaction:
CH4 + H2O ------------- CO + 3H2 ∆H= 206KJmol-1
Water-gas Shift Reaction:
CO + H2O ------------- CO2 + H2 ∆H= -41KJmol-1
It consists of reformer tubes in a Radiant box with top fired burners and a Convection and Conduction section where heat is recovered from the flue gas by the process streams. The three methods of heat transfer which take place in fired heaters and reformers are Radiation, Convection and Conduction. A Steam Reformer is balanced when the combustion air, fuel and process flows are stream lined and there is an even tube temperature spread, smooth flame pattern and a design excess oxygen level. Few units have any controls to balance the process gas on each bank of tubes however, it can be assumed to have equal process flows through each tube provided the catalyst has been loaded to give a pressure drop of ±5% throughout the Reformer.
The focus of this article is on combustion air balancing and fuel efficiency of the reformer. For efficient fur-
nace operation it is important that the air distribution to all burners except the wall burners be as close as pos-
sible. The system can be checked using pressure measurement devices to ensure even distribution of combus-
tion air through all the burners is achieved. Each row of burners has a corresponding refractory tunnel under-
neath it on the floor of the furnace. The tunnels are designed to promote uniform plug flow of hot combustion
gases down the tubes by drawing off the combustion products from the burners directly above (see Figure 1
below).
9
Figure1: Reforming Furnace Layout
Guidelines for Combustion Air Balancing:
1. Perform a visual check on the Reformer and measure and record the tube temperatures on each tube before
the Reformer balancing is initiated.
2. Print the relevant DCS screens on the plant taking note of gas charge, excess oxygen, fuel pressures and
flow rate as well as manifold temperatures on the Reformer outlet sub headers.
3. Record Pressure readings on each combustion air header of the reformer and make adjustments to ensure
that pressures are equalized throughout each row. During the combustion air adjustments the combustion
air fan should be placed on speed control since the fan speed may vary based on the downstream air pres-
sures. The flame patterns should be monitored to ensure that the flames are not licking the tubes.
4. All combustion air dampers on the individual burner wind boxes should fully opened or at design set point.
5. Ensure that the main Air dampers to reformer are open and locked into place to give the design excess oxy-
gen which may be between 1.6% to 2.0% in the Reformer coffins and at the design wind box pressure
which may be between 40mmH2O to 55mmH2O.
6. It may be desirable to minimize the closing of any air dampers before carrying out the furnace balancing.
7. Make sure that the distribution of air in each sub-header is equal by measuring the combustion air pressure.
Any irregularities are likely to be caused by blockages and should be investigated by isolation and removal
of the suspect valves for inspection during the next plant outage.
8. The combustion air pressure in the sub-headers can be read off the pressure gauges on the sub-header in
the penthouse of the Reformer or measured using a portable pressure gauge. Make sure that all gauges are
calibrated before taking readings.
9. Set the air pressures to give a variation of ±5% on pressure readings by adjusting the damper at each sub-
header. Then lock each sub-header damper securely in position to allow maximum air flow to each burner.
10. Measure the wind box air pressures on the burner boxes and make adjustments to ensure each row is re-
ceiving design wind box pressure.
11. Allow Reformer at least six to twelve hours to stabilize firing conditions.
10
12. Record oxygen readings off the Reformer coffins at the transient section of the Reformer box and Stack
using the flue gas analyzer. Monitor Carbon oxides levels as high levels of CO maybe as a result of tubes/
pigtail leaks on the Reformer or incomplete combustion. High oxygen levels on the stack and low excess
oxygen level in reformer may be due to leaks on the air-preheater coil or leaks on the dilution air duct or
open air dampers to the auxiliary burners.
13. The readings may show maximum oxygen levels at outer rows whereas inner rows may be oxygen defi-
cient.
14. Throttle the individual dampers on the rows where oxygen readings were in excess of the design of 1.65%
to 2.0% and perform visual check of flame patterns on the reformer.
15. Repeat steps 8-11 until the excess oxygen in the coffins are ±10% of the design usually between1.65to
2.0%.
16. Irregular flame patterns can be identified by visual checks on burners. Measure the wind box pressure on
the respective burner and a burner where flame patterns are normal.
17. Make adjustments to individual air damper on this burner if wind box pressure on this burner is lower than
wind box pressure on burners where flame patterns are normal.
18. Perform visual check on Reformer and record a tube temperatures.
19. Make fuel adjustments to burners in areas where the tubes temperatures are above the maximum design
tube temperature.
20. Fuel adjustments may be made to ensure that the desired temperature spread is maintained in the Reformer
and perform visual checks on Reformer after adjustments.
21. Repeat steps 15-18 until tube temperature spread is between maximum design tube temperature and re-
former outlet temperature.
22. After all fuel adjustments are completed perform a visual check on the Reformer and record excess oxy-
gen. Conduct an excess oxygen survey on the coffins. Make minor adjustments to combustion air if neces-
sary i.e. if coffin is significantly below design excess oxygen level.
23. The Air and Fuel in the Reformer should be balanced at this point. Record a complete DCS screen print of
the plant after balancing is completed.
Combustion Air balancing can significantly reduce fuel consumption as well as excess emissions such Sulphur
dioxide, nitrous oxides and carbon dioxides from the flue gas to the environment. A balanced reformer can
therefore not only reduce operating costs but can also reduce the carbon footprint of the unit thereby impacting
the rate at which Climate Change occurs. Thus, it is recommended that Combustion Air Surveys be done rou-
tinely to promote efficient plant Operations.
REFERENCES
1. 2005 Davy Process Technologies—Advice & Guidance Note 6—Combustion Air Balancing.
2. IMTOF 2003—A Complete Analysis of your Reformer by Bill Cotton, Fisher Bariy.
3. Catalyst Handbook 2nd Edition Edited by Martyn V. Twigg. Published by Wolfe Publishing Ltd, 1989.
11
NEW TECHNOLOGIES MATHEMATICALLY MODELLING AN AMMONIA CONVERTER CONFIGURATION, THE KELLOGG ADVANCED AMMONIA PROCESS (K.A.A.P.) DESIGN BY: JULIO BISSESSAR, B.A.SC., M.ENG, AMICHEME, GRADUATE TRAINEE PROCESS ENGINEERING AT ATLANTIC LNG
Ammonia synthesis and production is one of the lead-ing industries globally. Ammonia itself is a colorless gas which is produced industrially from Nitrogen (N2) and Hydrogen (H2) by combining Nitrogen from the air and Hydrogen produced from steam reforming of natural gas. In the presence of a catalyst, N2 and H2 can combine in a 1:3 ratio, to produce ammonia at elevated temperatures and pressures. The equation can be represented as follows:
N2 + 3H2⇌ 2NH3
Its use varies from Ammonium Nitrate to fertilizers and Urea, with the latter being the largest application. Fertilizer is vital because it allows farmers to produce more crops on less land; the nitrogen found in ammo-nia is essential to the growth and development of crops used for food and with the growing demand for food grown on increasingly less available land, the requirement for nitrogen derived from ammonia is ever present. Industrially, the production of ammonia is governed by the Haber-Bosch process in what is usually termed as an ammonia converter. This process presents some serious equilibrium limitations to the synthesis of am-monia. It is stated that the equilibrium concentrations of ammonia are higher at higher pressures and lower temperatures. However, according to Le Chatelier's Principle, the exothermic nature of the Haber - Bosch process results in high temperatures which drives the reaction in the reverse direction thus reducing the production of ammonia. There is an increase in the rate of reaction as one benefit of the exothermic na-ture of the reaction. The problem therefore arises in controlling the temperature such that both the optimal
rate of reaction and conversion to ammonia is achieved. In order to combat these problems, an in-depth study was conducted which involved mathematically mod-elling an ammonia converter that would be represen-tative of the Kellogg's Advanced Ammonia Process (K.A.A.P.) Design.Trinidad has eleven ammonia plants with an annual capacity of 5.2 million metric tonnes. Some of these include Yara Trinidad Limited, PCS Nitrogen, Point Lisas Nitrogen Limited (P.L.N.L.) and the Caribbean Nitrogen Company (C.N.C.); three of these implement the K.A.A.P. de-sign.
K.A.A.P. Design
Many different ammonia synthesis configurations are developed globally; one such is the K.A.A.P. Design. Its configuration aims at maximizing ammonia yields and optimizing ammonia conversion. Typically, am-monia conversion is quite low (a theoretical maxi-mum of approximately 20%) and by having these configurations of heating and cooling, it is expected that the yields of ammonia would increase. The pre-feed gas stream is split three ways upon entry into the converter configuration (see fig. 1); two streams are used to cool the exiting gases from beds 2 and 3 while the third stream flows through a pre-heater that is only utilized at start-up. The system is auto-thermally designed which means the process
fluid is used both as the heating and cooling medium.
12
As a direct result, there are no controllers on the heat exchangers between the catalyst beds. The heat exchangers are strategically placed between the catalyst beds to maximize the conversion that occurs as the temperature decreases.
Mathematical Model of Reactor System
Two mathematical models were developed by the use of MAT-LAB. Each of the models were based upon the ammonia reactor beds 1, 2 3 and 4. The other aspects of the K.A.A.P. design such as the mixing points and the heat exchangers were also modelled us-ing MATLAB and then each of the models were prompted to inter-act such as to produce a final ammonia conversion and yield. The difference between both models was based upon its complexity; one model was configured in one dimension (1-D) while the other was in two dimensions (2-D). For this article however, the discus-sion will be based around the 1-Dimensional model since the dy-namic 2-Dimensional model is complex but may be featured in an-other edition.
One-Dimensional Mathematical Model
A 1-Dimensional reactor system math model was programmed for the purpose of displaying results along the axial (z direction) of the bed but only specifically at a particular time, the end time. This time can be re-garded as a user specified function and in some ways can truly repre-
sent the residence time of the reactor system.
Some assumptions for the model were that the reactor system was not represented from startup conditions and viscosity was assumed to be constant. Some limitations were that a constant difference in nodal sizes would have been calculated (programmed into MATLAB code), thus the error to not improve its tolerance but remain at a fixed tolerance de-pending upon the number of nodes that the user has specified would be achieved. An additional limitation may be the fact that a simultaneous solution file is used to calculate a steady-state estimated profile for Ve-
locity and Pressure.
The system can be represented by the following mathematical relationships:
.................. Eqn. 1
.............................................................................. Eqn. 2
......................................................................... Eqn. 3
Fig.1. K.A.A.P. Design (Lewis, et. al., 2012)
Fig.2. Depiction of flow regime and coordinate system designation
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......................................................................... Eqn. 4
....................................................................... Eqn. 5 (Panahandeh et. al., 2003)
......................................................................... Eqn. 6 Cp data in the standard form of:
Cp = a + bT +cT2 + dT4..............................................................................................Eqn. 7
The partial differential equations (P.D.Es) were approximated via the numerical approximation of the Method of Lines (M.O.L.) approach and incorporated into the MATLAB code.
Results
A comparison was carried out on the 1-D mathematical model developed in MATLAB by the use of data ob-tained from another model developed by Qiliang et. al. (2001). The various initial conditions and kinetic pa-rameter variables were adjusted with accordance to those stated in the Qiliang et. al. (2001) paper. These re-sults were based upon ammonia concentrations (yNH3) and nitrogen conversion sensitivities.
Ammonia Concentration Sensitivity
Fig.3. yNH3 plots based upon comparison of results from Qiliang et. al. (2001).
From the yNH3 plot, it can be observed that as the residence time of the reactor increases, the trend of the MATLAB model tends to follow that of the Qiliang et. al.'s plot. This again can be rationalized since by in-creasing the length of the bed, it would be expected that the yield of ammonia would increase until a point is reached such that all of the reactants would be used up and the reverse reaction would then occur. As a result of the increasing temperature in the reactor bed as the residence time increases (a plot that was done but not included in this article), a direct result would be an increase in the yield of ammonia due to the highly exother-mic nature of the reaction.
14
Some possible reasons for the differences observed between the two models are: ♦ Uncertain as to if the Qiliang et. al. (2001) model had functions which updated specific heat capacity, den-
sity and relative molecular weight as these are some of the functions that our mathematical model pos-sessed.
♦ The method of solving the system in both cases was executed differently. In our case, we had a simultane-ous solution file that would output steady state profiles for the pressures and velocities whereas Qiliang et. al. (2001) did not have to undergo such tasks.
Conversion Sensitivity
By initial observation of the above graph, it can be observed that the conversion increases as we increase the residence time in the reactor system. This again stems from the fact that by increasing the time, there is an in-crease in the allocation of time provided for interactions of the reactants with the catalysts and thus an increase in conversion is evident. However, in this case, a point will be reached such that the backward reaction will become favored due to increased ammonia concentration and temperature. Conversion was performed on the basis of nitrogen.
Conclusions
This article served as an introduction to the K.A.A.P. design and focused upon the mathematical modelling of the ammonia reactor system. Some of the profiles generated were of ammonia concentrations and conversion and compared with a reference model. From the findings, it can be deduced that the ammonia synthesis reac-tion has higher conversions at lower temperatures and as the temperature increases, the rate of conversion de-creases.
REFERENCES:
1. Qiliang, Y.E. et. al. (2001). Simulation and Design Optimization of Ammonia Synthesis Converter. Chinese
Journal of Chemical Engineering Volume 9 Number 4 (pgs. 441-446).
2. Panahandeh, M.R. et. al. (2003). Steady state modelling and simulation of an axial-radial Ammonia Syn-
thesis Reactor. Chemical Engineering Technology Volume 26 (pgs. 666-671).
3. Lewis, L. et. al. (2012). Using CAPE to Enhance the Sustainability of Utilizing Natural Gas in Ammonia Production. IChemE European Symposium on Computer Aided Process Engineering ESCAPE 22: London
UK.
Fig.4. Sensitivity con-ducted based on changing residence time in the reactor system for conversion
profiles.
15
SAFETY SAFE OPERATING LIMITS BY: ENG. BRANDON JOSEPH, B.SC (UWI), AMICHEME & ENG. NILIA MAHARAJ-BUDHOO, B.SC (UWI), PROCESS ENGINEERS AT ATLANTIC LNG
What is a Safe Operating Limit?
The Safe Operating Limit (SOL) of a piece of equipment is the defined limit to which a process parameter can deviate from its normal operating range, without resulting in a safety issue. It is used to define the equipment’s ultimate safe operating condition. In understanding Safe Operating Limits one must understand the various envelopes for a process parameter. These are mainly the Normal Operating Envelope, Safe Operating Envelope and Safe Design Envelope. This will be discussed in the following section .
Envelopes and Limits
Safe Operating Envelope -
The Safe Operating Envelope denotes the region where a process parameter can exist without resulting in any safety consequence. It encompasses the Optimal Operating Zone, Normal Operating Envelope and defined Alarm Zones beyond the respective Alarm Points. Even though a process parameter may deviate beyond an Alarm Point, it may not pose a safety risk provided it is still within the Safe Operating Envelope. The Alarm Zone can also be referred to as the Troubleshooting Zone. In this region, an Operator’s main goal is to return the process parameter to within the Normal Operating Envelope.
Safe Design Envelope -
Safe Design Envelope encompasses all previously mentioned envelopes, inclusive of a Buffer Zone beyond the Safe Operating Envelope. Buffer Zone is the region between the Safe Operating and Safe Design Limit.
Optimal Operating Zone -
This is the desired operating region for a process parameter. Steady state operations usually occur within this region.
Normal Operating Envelope -
The Normal Operating Envelope denotes the region where a process parameter can exist without resulting in major operability (environmental, quality or commercial) conse-quences on the process. Key process parameters usually have alarms set at the upper and/or lower boundaries of the Normal Operating En-velope. This is to alert an Operator that a proc-ess parameter is deviating beyond the Normal Operating Envelope and that action is required to return the process parameter within the Nor-mal Operating Envelope.
Figure 1: Diagram showing single parameter depiction of limits and envelopes
16
The Buffer Zone should be large enough to give suffi-cient time to prevent a process parameter from reach-ing its respective equipment Design Limit, consider-ing that there may be a reaction time delay from when an SOL-mitigating-action is applied. The Safe Design Limit denotes the boundaries of the Safe Design Envelope. These may be based on the maximum or minimum limit to which the material of construction of equipment can be subjected to without equipment failure. The Safe Design Limit may also be based on the nature of the process medium in-volved, such that it limits the risk of a process safety incident from occurring due to the state of the me-dium or quantity or medium involved.
Determining Safe Operating Limits
The following examples show various approaches when determining safe operating limits.
Level:
i. Is there information based on Operator’s experi-ence?
ii. Is there a high level trip associated with the tank? iii. Is there historical data to show when there was an
upset and there was level fluctuation? iv. What is the lowest level that can be sustained in a
vessel without creating a blow-through situation?
Pressure:
i. Is there a high/low pressure interlock? This may be taken as the SOL.
ii. SOL may be set by code for the pressure vessel. iii. The SOL for Conventional/Bellows type PSVs
may be 90% the PSV set point. iv. For Pilot type PSVs, the SOL may be 95% the
PSV set point. v. In the event that the equipment is not vacuum
rated and there is uncertainty about lower pressure limit, 0barg can be chosen as the lower SOL.
Differential Pressure for Filters:
i. The Dirty DP values may be used for the SOL and the collapse DP for the Design Limit.
Temperature:
i. Is there a high/low temperature interlock associ-ated with the equipment?
ii. SOL may be defined by code for the equipment. iii. The SOL for an equipment may be influenced by
the downstream piping design limits.
Flow:
i. Is there a high/low flow interlock associated with the equipment?
ii. The SOL for high flow may be set by the capacity of the pumps. If when the pump is at maximum flow and no hazardous condition is created there may not be an SOL for the high flow scenario of the pump. In this case it is noted as “not applica-ble”.
iii. Calculations may be required for the low SOL to ensure the minimum flow rates are set so the pumps do not undergo cavitation.
Industry Standard Requirements for Safe Operat-
ing Limits
The following are some of the industry standard re-quirements for a Safe Operating Limits table: i. Operating parameter tag name. ii. Normal Operating Limit value including unit of
measure. iii. SOL value including unit of measure. iv. Expected immediate predetermined actions initi-
ated at the SOL including Operator monitoring requirements and additional actions if the process does not respond in a timely manner.
v. Worst credible unmitigated consequence of ex-ceeding the Safe Design Limit.
The SOL is the value of an operating parameter that defines the boundary (either high or low) of the safe operating envelope, where it is known to be safe to operate. SOLs should take into consideration the system dy-namics, design limits and safety factors to ensure ade-quate and realistic Buffer Zones. SOLs and Safe De-sign Limits should be reviewed periodically (at least every five years) to confirm they reflect current oper-ating conditions, information from inspection records, information from surveillance and modifications to plant and equipment.
REFERENCES
1. Application for approval of the development plan
for Parsons Lake Field Project Description, Op-erations and maintenance, Section 10.1.7, Safe
Operating Limits, August 2004.
2. Malcolm Denham, BP GDP 5.3-0001 Design and Operating Limits, 2012.
17
LEADERSHIP
DELIVERING SUSTAINABLE PERFORMANCE
INVENTIONS
BY: PREMOD VARGHESE AND JANE HUGHES
Why do many interventions designed to make a sustainable impact on performance have a limited shelf
life?
When we are committed to elevating the performance of our people, our focus can often be on changing the circumstances, for example bringing in a new process or system, or coming up with a different strategy. However when the circumstances are the focus for what needs to change, the context for that change, more often than not, is that there’s something wrong with the way things are. This will lead us to trying to do more of something, trying to do it better, or in a different way. And, any attempt to change something is based on what we’ve done before, limiting our view of what might be possible and the opportunity to be innovative.
Even if we experience short-term gains in doing some-
thing “more”, “better” or “different”, the way things have been done in the past creeps in and diminishes the
impact of the intervention. The result is that performance continues to drift in a predictable trajectory, rather
than delivering a lasting step-change. So while it is certainly useful to be informed by the past, it can be coun-
terproductive to be determined by it.
So how can we achieve a deep and lasting impact in performance? What can we do in order for some-
thing new to emerge?
While change requires a condition of “something”—more of something, better than something or different from something that already exists—creative thinking and actions require a condition of “nothing”, not limited by the past, free from fixing or changing something. “Nothing” is where we aren’t constrained by what’s hap-pened previously, where we’re able to take the learnings from what happened, but aren’t shackled by them. It demands being fully “present” and in the moment to be able to see what’s wanted and needed, and then re-spond accordingly. When we’re not devoted to fixing or changing something based on solutions that have worked previously, we are free to create new pathways to move forward.
When driven to fix problems, this approach often evolves into a “problem/solution” matrix, where the solution
to a problem becomes the next problem. One example is the invention of the automobile. The horseless car-
riage was invented to solve the problem of pollution by horse manure.
18
LEADERSHIP
DELIVERING SUSTAINABLE PERFORMANCE
INVENTIONS
BY: PREMOD VARGHESE AND JANE HUGHES
So what can we do to establish a condition of
“nothing” that allows for our interventions to have a
deep and lasting impact?
The best way to disrupt the linear thinking that has us be addicted to fixing what’s wrong is to use a non-linear approach to performance.
To be truly successful at delivering sustainable perform-
ance interventions, we must engage others in thinking
and acting outside any perceived limitations. The more
we create opportunities for others to contribute and par-
ticipate in the design and execution of an intervention,
the more ownership they will take. A good starting point
for this is to have a conversation that allows people to
express what might be on their minds about the past—
what happened, what didn’t happened, the results—
bringing closure to what’s happened to date; and what
their view of the future is—their fears, concerns, and ap-
prehensions. Until you’ve had a conversation like that,
there’s no room for authentic engagement to move for-
ward powerfully. Once people’s considerations are heard
and acknowledged, there’s often enough room to engage
in a conversation where people can start to consider that
there’s nothing ‘wrong’. In this way, you’ve introduced a
platform on which to create anything—a space where
new ideas, possibilities, actions, and outcomes can
emerge. Without this critical step, any further interven-
tion is unlikely to sustain itself.
About the Authors:
Premod Varghese
Senior Consultant
As a senior leader of JMW’s consulting prac-tice, Premod Varghese
works with executives,
managers, teams, and
organizations to develop
new and sustainable
pathways to high per-
formance and the
achievement of unprece-
dented targets.
Jane Hughes
Associate Consultant
Jane Hughes is an Associate Consultant for
JMW’s The Americas
Group. In her work
with clients, Jane
draws on a career of
more than 20 years
supporting individuals
and organizations as a
consultant, coach, and
project manager, both
in the public and pri-
vate sector.
However, when you consider the amount of pollution created by automobiles over the last century, it far ex-ceeds the pollution created by horse manure. The solution to a problem became the next problem!
19
PEOPLE & SUSTAINABILITY THE INSTITUTION OF CHEMICAL ENGINEERS OFFICIALLY LAUNCHES THE TRINIDAD AND TOBAGO MEMBER GROUP BY: ENG. MAURICE MASSIAH The IChemE Trinidad and Tobago Member Group (TTMG) held its official launch on 29th October at the Southern Academy for the Performing Arts (SAPA). The launch was attended by over 120 Chemical and Proc-ess Safety engineers from Trinidad and Tobago, and dignitaries and speakers from several prominent Compa-nies on the island. The opening address was given by the IChemE Senior Ambassador and Chairman of the Steering Committee Maurice Massiah. The speakers at the event were Ms. Caroline Sirju Ramnarine - Vice President of Corporate Operations of Atlantic LNG, Mr. Neil Atkinson Director – Qualifications and International Development IChemE, and the feature speaker Professor Emeritus David McGaw. An address was also given by the APETT President Elect Mr Fazir Khan. The Master of Ceremonies for the evening was Mr Imtiaz Easahak Chair of the APETT Chemical Division, who kept the evenings proceedings moving along on schedule whilst injecting his brand of humour. The IChemE TTMG Fellow award was given to Professor Emeritus McGaw in Recognition of Meritorious Service in the Development of Chemical Engineering in Trinidad & Tobago. He is now the first ever recipient of this award by the TTMG. Another awardee on the night was Michelle Aquing, a Process Safety Engineer at Atlantic LNG. Michelle was awarded the Young Process Safety Engineer’s award. This award is given to a young process safety engineer not yet Chartered who has been in a Process Safety role up to 3 years with the intention of becoming a Process Safety professional. Another important activity that occurred during the launch was the signing of a Memorandum of Understand-ing (MOU) between the APETT and the IChemE. This makes the TTMG the latest organization to become affiliated to APETT. The MOU is an important step towards formalising the affiliation between the two or-ganisations and provides additional benefits for APETT members. Key aspects of the MOU are listed below in the bullet points: ♦ Work with APETT to support the broader interests of Engineering and of Professional Engineers within
Trinidad and Tobago ♦ Facilitate joint membership and effectively market Member Group to attract members and for participation
in joint activities ♦ Grow the membership base of APETT and IChemE to deliver enhanced benefits within the local or e-
enabled reach of members of both organisations by capitalizing on synergies through the use of shared re-sources
♦ Coordinate Continuing Professional Development (CPD) programmes, as well as systems for award and record of CPD units for members
♦ Establish a set of annual Chemical Engineering awards for which Members shall be eligible ♦ Explore the potential for the establishment for a young member group. Maurice Massiah declared the TTMG officially launched, and then gave the vote of thanks. The event was sponsored by Worley Parsons, Atlantic LNG, and BP Trinidad and Tobago LLC.
20
Professor Emeritus David
McGaw giving the feature
address.
Michelle Aquing Process
Safety Engineer of Atlantic
LNG receiving the IChemE
Young Process Safety award
from Maurice Massiah.
Caroline Sirju Ramnarine VP Corporate
Operations Atlantic LNG during her address.
The official signing of the MOU between
APETT and IChemE. From Lto R Haydn
Furlonge, Neil Atkinson and Fazir Khan.
Imtiaz Easahak APETT Chemical
Division Chair and Master of
Ceremony for the Official TTMG
Launch
21
Following the official October 29th launch of the Trinidad and Tobago Member Group, two APETT / IChemE joint technical seminars were held.
SEMINAR #1- Asset Integrity Manage-
ment (AIM) This seminar was conducted on Thursday November 19th at the UTT- Point Lisas Campus. Seventy (70) persons were in attendance and the session was highly interactive. The presenter was Dr. Abe Nezamian of Worley Parsons. The key areas presented on this topic were: ♦ Asset Integrity Development ♦ Legal Framework and Standards of AIM ♦ Applications of the AIM Standard ♦ Benefits and potential costs of AIM ♦ Structure and Roles in AIM ♦ Optimized AIM program and key benefits. Dr. Abe Nezamian is a strategic, operational and asset management improvement leader with over 25 years of engineering, operational and consulting experi-ence. Abe is an industry adviser in the field of asset integrity management/life extension and has pub-lished over forty conference, journal and white papers on asset integrity assessment, strategy and manage-ment; decision support tools; Opex/Capex optimisa-tion and best practice in operational excellence and asset life extension.
SEMINAR #2- Corrosion Under Insulation
(CUI)
This seminar was conducted on Friday 27th Novem-ber at UTT- Point Lisas Campus. Forty-eight persons were in attendance and the session was also very in-teractive. The presenter was Mr. Kiriti Bhattacharya- an independent industrial consultant. The seminar focused on CUI as being a serious prob-lem for the power, process, oil and gas industries worldwide. It is particularly dangerous, because it occurs out-of-sight. CUI not only eats away at assets, it also exposes the environment and people to huge risks from sudden unexpected hazardous fluid release. Internationally, CUI results in millions of dollars in losses every year, release to the environment, fires and explosions and sometimes, fatalities and multiple injuries. The lecture dispelled commonly held notions about CUI and presented practical prevention methods from design, installation to inspection. Kiriti Bhattacharya B.A.Sc. (Toronto). M.I.A.M.(UK) M.Weld.I.(UK) R.Eng, is a 1972 graduate of the Uni-versity of Toronto. He is a professional metallurgical engineer with over 40 years of experience in plant design and inspection, corrosion control, welding, metallurgical failure analysis, construction and asset management. He retired from Shell in 2010 and has since been an international consultant and trainer.
Maurice Massiah of BPTT presenting a token of appreciation to Mr. Bhattacharya
22
LinkedIn DISCUSSION
THE OIL PRICE: THE OIL PRICE:
DDIFFERENTIFFERENT VIEWVIEW POINTSPOINTS ACROSSACROSS
OILOIL & & GASGAS PEOPLEPEOPLE
Oil & Gas Recruitment Date Posted: October 2015
Angus Plummer
Director at miningoilandgasjobs.com
A survey of 13 investment banks by The Wall Street Journal saw the average forecast for Brent crude, the international benchmark, cut sharply by $9 to $58.70 a barrel for next year compared to the prediction just last month. This reflects an increasingly bearish mood as the OPEC cartel has signaled it will not relent on its high-supply policy to defend mar-
ket share.
Among these averages are some pretty pessimistic estimates. Goldman Sachs, for example, said recently that it expected Brent to remain below $50 for the whole of next year as the supply glut is slowly reversed, with a worst case collapse to just $20. But producers will welcome a rejoinder from Commerzbank's head of commodity research Eugen Weinberg, who agrees oversupply will persist in the coming 12 months but argues this has already been "priced in by the market
and the current level will serve as the bottom for prices".
A bottom to the market was called before when Brent crude hit $45 in January, but after a rally came to an end in June it fell back sharply and briefly touched $42 earlier this summer. The benchmark has been rooted almost exclusively below
$50 ever since.
Oil Industry News Date Posted: 6 August 2015
OIL FIRMS FEAR DEEPER CRISIS THAN IN 1980s
After slashing spending by $180 billion to deal with one of the worst industry downturns in dec-ades, oil companies are still bleeding cash and slipping further into debt to maintain dividends to
shareholders.
Depressed crude prices - at below $50 a barrel Brent crude is half what it was a year ago - mean even more cuts are needed at new projects and existing operations. Companies trying to dispose of oilfields to raise cash could be forced to sell quickly and for less than they hoped.
23
Oil Industry News Date Posted: 6 October 2015
SHELL CEO SEES FIRST SIGNS OF OIL PRICE RECOVERY
Oil markets are beginning to recover but the scale of global oversupply means prices may rise only slowly, the chief executive of
Royal Dutch Shell Plc said on Tuesday.
“I see the first mixed signs for recovery of oil prices,” Ben van Beurden told an oil industry conference in London.
“But with U.S. shale oil being more resilient than we originally thought and a lot of oil still in stock, it will take some more time to
rebalance demand and supply,” he added.
Oil prices have collapsed over the last year in the face of heavy oversupply, with benchmark Brent crude falling to below $50 a bar-
rel from a high above $115 in June 2014.
The Organization of the Petroleum Exporting Countries led by Saudi Arabia has increased production in an attempt to build market
share, leaving some other producers, including shale companies in North America, operating below break-even costs.
Van Beurden said many U.S. oil producers would struggle to refinance while prices remained so low, leading to lower output in the
future: “Producers are now looking for new cash to survive and they will probably struggle to get it.”
Longer-term, there was a risk that low levels of global production could bring a spike in oil prices, he said.
If prices remained low for a long time and oil production outside OPEC and the United States declined due to cuts to capital expen-
diture, there was not likely to be any significant spare capacity left in the system, he said.
“This could cause prices to spike upwards, starting a new cycle of strong production growth in U.S. shale oil and subsequent volatil-
ity,” van Beurden said.
LinkedIn DISCUSSION
Oil Industry News Date Posted: 23 August 2015
LOW OIL PRICES COULD BREAK OPEC’S “FRAGILE FIVE”
Persistently low oil prices have already inflicted economic pain on oil-producing countries.
But with crude sticking near six-year lows, the risk of political turmoil is starting to rise.
There are several countries in which the risks are the greatest – Algeria, Iraq, Libya, Nigeria, and Venezuela – and RBC Capital Markets has labeled them the “Fragile Five.”
THE OIL PRICE: THE OIL PRICE:
DDIFFERENTIFFERENT VIEWVIEW POINTSPOINTS ACROSSACROSS
OILOIL & & GASGAS PEOPLEPEOPLE
24
ACE EXECUTIVE COUNCIL MEMBERS 2014—2015
ENG. IMTIAZ EASAHAK CHAIR
ENG. THERON OUSMAN VICE CHAIR
ENG. RIA MCLEOD HONARARY SECRETARY
ENG ASHLEY RAMKISSOON PUBLIC RELATIONS OFFICER
ENG. ANNA WARNER NEWSLETTER EDITOR
ENG. FARAD BOOCHOON TREASURER
ENG. BRANDON JOSEPH ORDINARY MEMBER
ENG. SHELDON BUTCHER ORDINARY MEMBER
ENG. CLAUDIUS STEWART ORDINARY MEMBER
ENG. CHRISTOPHER PEDRO ORDINARY MEMBER
