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Fuel Flexibility - a techno-economic review
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Fuel Flexibility - a techno-economic review


Fuel Flexibility - a techno-economic review, IIR Power Generation Conference, London 1999

Fuel Flexibility - a techno-economic review, IIR Power Generation Conference, London 1999

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  • 1. Outline ( Fuel-flexibility - Nhat benefit? c The driving factors influencing the need " Fuels issues '- Environmental factors r Technical challenges ' O&M Project decisions Conclusions and recommendations 0 National Power C National Power PLC, 1999
  • 2. Driving Factors ,. Povver purchase agreement often based on availability payments '~· Fuel purchase agreement interruptible fuel agreements ,. Merchant plant energy sales 'pool' price is often volatile for gas and electricity may want to trade gas increased plant value with 'black' start 0 National Power 0 National Power PLC. 1999
  • 3. 1 Other Important Fuel' Flexibility Issues t Over-firing for grid compliance additional capacity * - Power augmentation for additional capacity ( Operation use when the pool purchase price is high hot summer's day to maintain output 'Black' start 0 National Power C National Power PLC. 1999
  • 4. Fuel Factors f Changing fuel is not a trivial matter changing from one natural gas to another • requires care - CV, dew-point and Wobbe index may all be within specification but the gas turbine may encounter emissions or pulsation problems ( Cost implications of fuel sNitching must be assessed in terms of: capital; operational; fuel; plant output and availability 0 National Power I!:> National Power PLC. 1999
  • 5. Fuel Quality and Variability - Natural gas is not 100% methane { Gas composition will change as the well 'matures' ( Gas may be from two different sources gas A has a CH 4 content of 82 % , CV of 9,260kCal m- 3 ± 8% gas B has a CH 4 content of 84%, CV of 9,SSOkCal m-3 ± 9% but the station cannot control the source 0 National Power C National Power PLC, 1999
  • 6. Fuel Quality and Variability { Delivery pressure pressure can vary over the day and has been seen to cause combustion problems ( Relative fuel density - again this can vary on a daily basis has been seen to cause combustion problems Level of longer-chain hydrocarbons increased levels of CG+ in the gas stream has been seen to cause combustion problems 0 National Power C National Power PLC. 1999
  • 7. Environmental Issues f Liquid fuels storage - spills - contaminated water from washing of heavy fuel oil fire hazard drain oil from failed starts 0 National Power IO National Power PLC. 1999
  • 8. Environmental Issues ( It may be possible to get exceptions from the strictest emissions limits vvhile burning 'alternative' fuels, vvhere it can be shovvn that: - the fuel is being burnt in the most environmental way all efforts are being made to keep emissions to best achievable levels where local air quality is not an issue 0 National Power <O National Power PLC. 1999
  • 9. Maintenance c Need to ensure that fuel {and vvater) distribution is optimal for~ fuels c Control system must be 'intelligent' to be able to handle the range of fuels -~ adaptive? '· Regular maintenance is required on all fuel systems but especially liquid fuel systems 0 National Power ~National Power PLC, 1999
  • 10. Operations ( l It is important to regularly exercise all of the fuel systems but risk of tripping machine reduced availability ( J Fuel svvitching on gas fuel in DLN machines is not seamless emissions limits may be exceeded combustion pulsations may occur load swings the Change-over needs tO be SeamleSS C National Power PLC. 1999 0 NationalPower
  • 11. NG only - may need to renegotiate PPA NG + DFO ~t option
  • 12. Conclusions . _ Fuel flexibility can offer improved profitability ~· Fuel flexibility must include the ability to handle natural gases of differing properties The technical challenges to improve secondary fuel availability exist 0 Flexibility should also include options for povver augmentation National Power at10nal Power PLC , 1999
  • 13. Recommendations ( Take care when specifying secondary fuel handling systems if you need high availability ' Develop a methodology to identify the value and costs of a back-up fuel system to see if you really do need it Ensure that sufficient interest from both operations and maintenance is focused on the secondary fuel system O National Power ional Power PLC , 1999