1 Conversion of Coleson Cove Oil-Fired Unit to Natural Gas Combined Cycle Introduction: CCGS is an oil-fired electrical generating station capable of generating 1050 MW of electrical power. Conversion to a natural gas combined cycle offers several advantages over a conventional oil-fired boiler including; lower fuel cost, higher thermal efficiency, faster plant start-up times, superior cycling ability, as well as a smaller carbon footprint. As the contribution to the electrical grid supply from wind power continues to increase, it is increasingly more important for NB Power to have generating stations that are capable of starting up quickly in response to wind power fluctuations. Sara Long, Kirsten Melnyk, Alex Stocek & James Ponting Designed System: Filtered and compressed air enters the combustion chamber of the Siemens SGT6- 8000H Gas Turbine, where it is mixed with natural gas. The hot combusted gas is expanded, generating 283 MW of electricity. The hot exhaust gas is sent to the Heat Recovery Steam Generator (HRSG) where steam is produced and sent to the existing steam turbine, generating an additional 138 MW of electricity. After accounting for station service the designed system will supply 418 MW to the grid. Abstract: This project is a technical and economic feasibility study for the conversion of the Unit #1 conventional oil-fired boiler to a natural gas combined cycle (NGCC) at NB Power’s Coleson Cove Generating Station (CCGS). One of the main objectives of the project was to design a system that would reuse the existing steam turbine as well as other auxiliary equipment and infrastructure. The planned start-up is in 2020 with an expected plant life of 30 years. The total capital investment for this project is $289 million, and would require an additional investment of $50 million, at the end of year 18 to extend the life of the aging steam cycle. It would take 50 years to reach the break-even point for this project based on today’s natural gas and electricity prices. It was also found that by replacing the existing steam cycle as part of the conversion project, the payback period would be reduced from 50 to 31 years based on higher combined cycle efficiency. A brownfield project with all new equipment would eliminate the need for an expensive, mid-life, refurbishment to reach the desired 30 year plant life. The existing land, utilities and personnel could still be leveraged in a brownfield project, making this an attractive option. Economic Analysis: The basis for the economic analysis was that the NGCC would be commissioned in 2020 and would have an expected plant life of 30 years. The total capital investment is $289 million with an additional $50 million required at year 18 to extend the life of the aging steam cycle. The annual profit generated by the NGCC is $12.3 million. The payback period is 50 years based on today’s natural gas and electricity prices. To achieve payback within the 30 year plant life the price of natural gas would need to decrease by 3% , with the price of electricity remaining constant. It was also found that by replacing the existing steam cycle as part of the conversion project, the payback period would be reduced from 50 to 31 years based on higher combined cycle efficiency. Conclusion and Recommendations: • Based on the current energy market and the 50 year payback, a positive investment decision for a repowering project is not recommended. • Replacing the steam cycle as part of the conversion would improve the business case by reducing the payback period from 50 to 31 years. • If a NGCC generating station is required to meet NB Power’s mandate, then a high efficiency NGCC with all new equipment should replace Unit #1at CCGS. From left to right: Sara Long, Alex Stocek, Kirsten Melnyk & James Ponting Photo of a Siemens SGT-8000H gas turbine Photo of a vertical Heat Recovery Steam Generator that is used in the designed system Acknowledgements: We would like to thank our client, NB Power, especially Keith MacLean, Kevin Hibbert and Michael Fowler for their support and willingness to accommodate us during this project. We would also like to thank our industrial co-mentor, Robert Crawford, our academic co-mentor, Dr. Michel Couturier, and the course coordinator, Dr. Guida Bendrich for their continuous guidance and commitment to this project. Thank you. Air Filtration Gas Expansion Steam Generation Steam Expansion Steam Condensation & Pumping Ambient Air 625.7 kg/s 1.01 bar 32 °C Natural Gas from Maritime North East Pipeline 14.3 kg/s 21.5 bar Filtered Air 1.01 bar T = 32°C Electricity to Grid 283 MW (Net) Hot Exhaust Gas 640 kg/s 1.04 bar 626 °C Cooled Exhaust Gas 640 kg/s 1.01 bar 119 °C Electricity to Grid 135 MW (Net) Cooling Water for Condenser Makeup Water from Demineralized Plant Condenser Dump Steam Turbine Bypass (NC) Exhausted Steam 0.034 bar 26 °C Air Compression Combustion Electricity Generation Electricity Generation Shaft Work Shaft Work Filtered & Compressed Air 626 kg/s 19.8 bar Hot Combusted Gas 640 kg/s 19.8 bar 1353 °C HP Steam Hot Reheat Cold Reheat Station Service 3.4 MW Discharge 22°C Inlet 10°C Legend: Station Battery Limits Material Stream Shaft Work Electricity Blowdown Bypass (NC) NC – Normally Closed Feed water 101 kg/s 8 bar 26 °C
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1
Conversion of Coleson Cove Oil-Fired Unit to Natural Gas Combined Cycle
Introduction: CCGS is an oil-fired electrical generating station capable of generating 1050 MW of electrical power. Conversion to a natural gas combined cycle offers several advantages over a conventional oil-fired boiler including; lower fuel cost, higher thermal efficiency, faster plant start-up times, superior cycling ability, as well as a smaller carbon footprint. As the contribution to the electrical grid supply from wind power continues to increase, it is increasingly more important for NB Power to have generating stations that are capable of starting up quickly in response to wind power fluctuations.
Sara Long, Kirsten Melnyk, Alex Stocek & James Ponting
Designed System: Filtered and compressed air enters the combustion chamber of the Siemens SGT6-8000H Gas Turbine, where it is mixed with natural gas. The hot combusted gas is expanded, generating 283 MW of electricity. The hot exhaust gas is sent to the Heat Recovery Steam Generator (HRSG) where steam is produced and sent to the existing steam turbine, generating an additional 138 MW of electricity. After accounting for station service the designed system will supply 418 MW to the grid.
Abstract: This project is a technical and economic feasibility study for the conversion of the Unit #1 conventional oil-fired boiler to a natural gas combined cycle (NGCC) at NB Power’s Coleson Cove Generating Station (CCGS). One of the main objectives of the project was to design a system that would reuse the existing steam turbine as well as other auxiliary equipment and infrastructure. The planned start-up is in 2020 with an expected plant life of 30 years. The total capital investment for this project is $289 million, and would require an additional investment of $50 million, at the end of year 18 to extend the life of the aging steam cycle. It would take 50 years to reach the break-even point for this project based on today’s natural gas and electricity prices. It was also found that by replacing the existing steam cycle as part of the conversion project, the payback period would be reduced from 50 to 31 years based on higher combined cycle efficiency. A brownfield project with all new equipment would eliminate the need for an expensive, mid-life, refurbishment to reach the desired 30 year plant life. The existing land, utilities and personnel could still be leveraged in a brownfield project, making this an attractive option.
Economic Analysis: The basis for the economic analysis was that the NGCC would be commissioned in 2020 and would have an expected plant life of 30 years. The total capital investment is $289 million with an additional $50 million required at year 18 to extend the life of the aging steam cycle. The annual profit generated by the NGCC is $12.3 million. The payback period is 50 years based on today’s natural gas and electricity prices. To achieve payback within the 30 year plant life the price of natural gas would need to decrease by 3% , with the price of electricity remaining constant. It was also found that by replacing the existing steam cycle as part of the conversion project, the payback period would be reduced from 50 to 31 years based on higher combined cycle efficiency.
Conclusion and Recommendations: • Based on the current energy market and the 50 year payback, a positive investment decision for a repowering project is not recommended. • Replacing the steam cycle as part of the conversion would improve the business case by reducing the payback period from 50 to 31 years. • If a NGCC generating station is required to meet NB Power’s mandate, then a high efficiency NGCC with all new equipment should replace Unit #1at CCGS.
From left to right: Sara Long, Alex Stocek, Kirsten Melnyk & James Ponting
Photo of a Siemens SGT-8000H gas turbine
Photo of a vertical Heat Recovery Steam Generator that is used in the designed system
Acknowledgements: We would like to thank our client, NB Power, especially Keith MacLean, Kevin Hibbert and Michael Fowler for their support and willingness to accommodate us during this project. We would also like to thank our industrial co-mentor, Robert Crawford, our academic co-mentor, Dr. Michel Couturier, and the course coordinator, Dr. Guida Bendrich for their continuous guidance and commitment to this project. Thank you.
Air Filtration
Gas Expansion Steam Generation Steam Expansion
Steam
Condensation &
Pumping
Ambient Air
625.7 kg/s
1.01 bar
32 °C
Natural Gas from
Maritime North
East Pipeline
14.3 kg/s
21.5 bar
Filtered Air
1.01 bar
T = 32°C
Electricity to Grid
283 MW (Net)
Hot Exhaust
Gas
640 kg/s
1.04 bar
626 °C
Cooled Exhaust
Gas
640 kg/s
1.01 bar
119 °C
Electricity
to Grid
135 MW
(Net)
Cooling
Water for
Condenser
Makeup Water from
Demineralized Plant
Condenser
Dump
Steam Turbine
Bypass (NC)
Exhausted
Steam
0.034 bar
26 °C
Air Compression
Combustion
Electricity
GenerationElectricity
Generation
Shaft Work Shaft Work
Filtered &
Compressed Air
626 kg/s
19.8 bar
Hot
Combusted
Gas
640 kg/s
19.8 bar
1353 °C
HP Steam
Hot Reheat
Cold Reheat
Station
Service
3.4 MW
Discharge
22°CInlet
10°C
Legend:
Station Battery
Limits
Material
Stream
Shaft Work
Electricity
Blowdown
Bypass (NC)
NC – Normally
Closed
Feed water
101 kg/s
8 bar
26 °C
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