how to reduce fuel gas consumption
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How to Reduce Fuel Gas How to Reduce Fuel Gas ConsumptionConsumption
Paul NelsonPaul NelsonManager, Commercial OperationsManager, Commercial Operations
AltaGas Ltd.AltaGas Ltd.May 9, 2008May 9, 2008
BackgroundBackground Natural gas is an essential fuel used in oil Natural gas is an essential fuel used in oil
and gas productionand gas production Fuel usage in oil and gas production and Fuel usage in oil and gas production and
processing accounts for approx. 9% of all raw processing accounts for approx. 9% of all raw gas produced (44,000 e3m3/d, or 1.6 Bcf/d)gas produced (44,000 e3m3/d, or 1.6 Bcf/d)
Initial site specific studies shows potential for Initial site specific studies shows potential for reductionreduction
10% reduction in fuel gas consumption would 10% reduction in fuel gas consumption would mean addition sales of 4.4 e6m3/d or 160 mean addition sales of 4.4 e6m3/d or 160 MMcf/dMMcf/d
Economic benefit (potentially $500 Economic benefit (potentially $500 million more sales, at $9/GJ)million more sales, at $9/GJ)
Greenhouse gas reductions (3 million Greenhouse gas reductions (3 million tonnes CO2e per year)tonnes CO2e per year)
Extended life of facilities Extended life of facilities Energy efficient operations are often Energy efficient operations are often
more cost-effective operationsmore cost-effective operations
Benefits of Energy EfficiencyBenefits of Energy Efficiency
Total Fuel Use in the Upstream SectorTotal Fuel Use in the Upstream Sector(incl. straddle, bitumen and injection)(incl. straddle, bitumen and injection)
Source: ERCB
Total Fuel Use in the Upstream SectorTotal Fuel Use in the Upstream Sector(excl. straddle, bitumen and injection)(excl. straddle, bitumen and injection)
Source: ERCB
Gas Plant Fuel UsageGas Plant Fuel Usage
Source: ERCB
Gathering System Fuel Gathering System Fuel UsageUsage
Source: ERCB
Gas Battery Fuel UsageGas Battery Fuel Usage
Source: ERCB
Fuel Gas Efficiency Fuel Gas Efficiency CommitteeCommittee Formal Government/industry Formal Government/industry
committee established May 2006, committee established May 2006, chaired by Alberta Energychaired by Alberta Energy
Mission statement:Mission statement: To set direction and provide leadership To set direction and provide leadership
to improve the upstream industry’s to improve the upstream industry’s petroleum energy efficiency per unit of petroleum energy efficiency per unit of production and reduction of fuel gas use production and reduction of fuel gas use in oil and gas production, pipeline and in oil and gas production, pipeline and gas processing facilities regulated by gas processing facilities regulated by the ERCBthe ERCB
Members:Members: Alberta Department of Energy (chair)Alberta Department of Energy (chair) Gas Processing Association CanadaGas Processing Association Canada ERCBERCB CAPPCAPP SEPACSEPAC Natural Resources CanadaNatural Resources Canada Individual Producers and MidstreamersIndividual Producers and Midstreamers
Fuel Gas Efficiency Fuel Gas Efficiency CommitteeCommittee
Result:Result:Best Management PracticesBest Management Practices
Consultant has completed a series of Consultant has completed a series of documents for maximizing fuel gas documents for maximizing fuel gas efficiency in oil and gas production efficiency in oil and gas production and processing operationsand processing operations
Funding shared between government Funding shared between government and industry and industry
Final product is 17 BMP documentsFinal product is 17 BMP documents BMP’s will be publicly accessibleBMP’s will be publicly accessible
Where Fuel Gas is UsedWhere Fuel Gas is Used
Source: ERCB
Gas Plant Fuel UsageGas Plant Fuel Usage
Source: ERCB
List of BMP’sList of BMP’s
Gas Gathering Systems Dessicant DehydratorsPumpjacks Fuel Gas Measurement
Pneumatic Instruments FractionationFlaring Refrigeration
Chemical Injection Pumps AmineFired Heaters Sulphur Recovery
Engines Tail Gas IncinerationCompression Acid Gas Injection
Glycol Dehydrators
Sample: Glycol DehydratorsSample: Glycol Dehydrators
Sample: Glycol DehydratorsSample: Glycol DehydratorsContentsContents
Table of Contents
1. Applicability and Objectives ..........................................1 2. Basic Improvement Strategies.......................................2 2.1 Technology and Equipment 2.2 Efficiency Assessment 2.3 Improving Efficiency 3. Inspection, Monitoring and Record Keeping................3 4. Efficiency Assessment and Adjustments .....................4 4.1 Types of Dehydrators and Uses 4.2 Fuel Gas Consumption 4.3 Operational Optimization 5. Technical Checks and Evaluation ...............................10 5.1 Performance Evaluation 5.2 Performance Specification and Assessment Process 6. Appendices
Appendix A Glycol Dehydration Turndown Considerations Appendix B Design Considerations for Optimization Appendix C Example Calculations for Optimization Appendix D Water Content of Hydrocarbon Gas Appendix E Water Removal vs. TEG Circulation Rate Appendix F References
Tables Table 1 Operating Targets for Glycol Dehydrator
Components Table 2 Glycol Dehydrator Fuel Gas Use Table 3 Turndown Liquid Rate Reduction
Table 4 Case Study: Fuel Gas Savings from Using a Flash Tank Separator Table 5 Case Study: Potential Savings from Using an Electric Pump vs. Pneumatic Pump
Figures Figure 1 Glycol Dehydration Schematic Figure 2 Typical Fuel Gas Usage for Glycol Dehydrators Figure 3 TEG Operating Graph
Sample: Glycol DehydratorsSample: Glycol DehydratorsLogic Diagrams and GraphsLogic Diagrams and Graphs
4.4 Operational Adjustments Logic Diagram
Make changes to circulation rateslowly to m atch the optim um ratio
and dry gas dewpoint. Adjust reboilerduty according to the glycol
circulation rate in the TEG operatinggraph pg 11.
Does the current TEG/waterratio m atch the optim um TEG/waterratio as identified in the perform ance
optim ization?
No
Yes
The optim um TEG/water ratio and them axim um inlet water flow have beenspecified in perform ance optim ization
section 5.1
Based on inlet gaswater content and flow, can theglycol circulation rate be safely
reduced?
Ensure pum p isset to the
operating pressurerequired
Adjust c irculation ratesand reboiler duty
according to the TEGoperating graph usinginlet water flow, andthe optim um TEG/
water ratio(See pg 11)
No
Yes
G lycol dehydration systemis optim ized
TEG Operating Graph
0
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0 5 10 15 20 25 30
Circulation Rate (LPM)
Kg
Wat
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ay
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Reb
oil
er D
uty
(kW
)
Circulation Rate (16 L TEG/Kg H2O) Circulation Rate (25 L TEG/Kg H2O) Circulation Rate (33 L TEG/Kg H2O)
Reboiler Duty (16) Reboiler Duty (25) Reboiler Duty (33)
16 L TEG/Kg H2O 25 L TEG/Kg H2O 33 L TEG/Kg H2O
16
25
33
Sample: Glycol DehydratorsSample: Glycol DehydratorsCase StudiesCase Studies
Appendix C Case Study Calculations for Glycol Dehydrator Optimization
A TEG dehydration system is processing gas coming straight from an amine absorber. The TEG contactor has 10 bubble cap trays (2.5 theoretical stages). Gas conditions: flow is 1675 e3m3/d: Temperature = 30?C Pressure = 5000 kPa Benzene = 200 ppm A gas at 30?C and 5000 kPa has a water content of 780 mg H2O/m3. 780 mg/m3 x 1675 e3m3/d = 1306 kg of water/day The plant has a treated gas specification of 64 mg H2O/m3 of gas. Water removal efficiency needed = (W in –Wout)/Win = (780 – 64)/780 = 91.8% From the “water removal vs. TEG circulation rate” graph (See Appendix E), this efficiency can be achieved with a 98.6% strength TEG circulating at 25 L TEG/kg H2O. No stripping gas is needed in this unit:
TEG Operating Graph
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1300
1400
1500
0 5 10 15 20 25 30 35
Circulation Rate (LPM)
Kg
Wat
er/D
ay
0
25
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325
350
375
Circulation Rate (16 L TEG/Kg H2O) Circulation Rate (25 L TEG/Kg H2O) Circulation Rate (33 L TEG/Kg H2O)
Reboiler Duty (16) Reboiler Duty (25) Reboiler Duty (33)
16 L TEG/Kg H2O 25 L TEG/Kg H2O 33 L TEG/Kg H2O
1625
33
To meet the dehydration requirements, the system must circulate the glycol at 23 LPM, and run with a reboiler duty of 112 kW.
Operation Optimization Case Study
The above plant was found to be circulating at 30 LPM.
TEG Operating Graph
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
0 5 10 15 20 25 30 35
Circulation Rate (LPM)
Kg
Wat
er/D
ay
0
25
50
75
100
125
150
175
200
225
250
275
300
325
350
375
Circulation Rate (16 L TEG/Kg H2O) Circulation Rate (25 L TEG/Kg H2O) Circulation Rate (33 L TEG/Kg H2O)
Reboiler Duty (16) Reboiler Duty (25) Reboiler Duty (33)
16 L TEG/Kg H2O 25 L TEG/Kg H2O 33 L TEG/Kg H2O
1625 33
Over circulation of the glycol results in a 31.6% increase in reboiler duty, from 112 kW to 147.5 kW. The plant reduces the glycol circulation rate down to 22 LPM and can then lower the reboiler duty correspondingly. Fuel Gas Savings Reboiler Savings: Fuel gas value: $5.25/GJ Fuel gas heating value: 40 GJ/e3m3
1 kW*s = 1 kJ 1 kW*h = 0.0036 GJ
therefore, 147.5 kW*h = 0.531 GJ 0.531 GJ = $66.91/d and 318.6 m3/d of fuel gas
= $24,420.69/yr and 116,289 m3/yr of fuel gas After optimization:
112 kW*h = 0.4032 GJ
0.4032 GJ = $50.80/d and 241.9 m3/d of fuel gas = 18,543.17/yr and 88,301 m3/yr of fuel gas
Economic savings = $5,877.52/yr (24% reduction) Fuel gas volume saved = 28 e3m3/yr
How to Reduce Fuel Gas How to Reduce Fuel Gas Consumption?Consumption?
Use Best Management Practices!Use Best Management Practices!
Next Steps Next Steps
BMP’s to reside on CAPP website, BMP’s to reside on CAPP website, available for downloading available for downloading
BMP material to be incorporated into BMP material to be incorporated into industry training coursesindustry training courses
Industry and government to monitor Industry and government to monitor usage and to quantify impact of usage and to quantify impact of adoption of the BMP’s adoption of the BMP’s
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