1. Plant Utility System (TKK-2210) 14/15 Semester 4 Instructor: Rama Oktavian Email: rama.oktavian86@gmail.com Office Hr.: M-F 13-15

2. 2 © UNEP 2006 Training Agenda: Cogeneration Thermal Equipment/ Cogeneration Introduction Types of cogeneration systems Assessment of cogeneration systems Energy efficiency opportunities

3. 3 © UNEP 2006 Introduction Generation of multiple forms of energy in one system: heat and power Defined by its “prime movers” Reciprocating engines Combustion or gas turbines, Steam turbines Microturbines Fuel cells What’s a Cogeneration/CHP System? Thermal Equipement/ Cogeneration

4. 4 © UNEP 2006 Introduction Efficiency Advantage of CHP Thermal Equipment/ Cogeneration 100 68 24 Uni ts 34 Uni ts 6 Units (Losses) 60 40 36 Units (Losses)  = 85%  = 40% 10 Units (Losses) Conventional Generation (58% Overall Efficiency) Combined Heat & Power (85% Overall Efficiency) (UNESCAP, 2004)

5. 5 © UNEP 2006 Introduction Increased efficiency of energy conversion and use Lower emissions, especially CO2 Ability to use waste materials Large cost savings Opportunity to decentralize the electricity generation Promoting liberalization in energy markets Benefits of Cogeneration / CHP) Thermal Equipment/ Cogeneration

6. 6 © UNEP 2006 Training Agenda: Cogeneration Thermal Equipment/ Cogeneration Introduction Types of cogeneration systems Assessment of cogeneration systems Energy efficiency opportunities

7. 7 © UNEP 2006 Type of Cogeneration Systems Steam turbine Gas turbine Reciprocating engine Other classifications: - Topping cycle - Bottoming cycle Thermal Equipment/ Cogeneration

8. 8 © UNEP 2006 Type of Cogeneration Systems Widely used in CHP applications Oldest prime mover technology Capacities: 50 kW to hundreds of MWs Thermodynamic cycle is the “Rankine cycle” that uses a boiler Most common types Back pressure steam turbine Extraction condensing steam turbine Steam Turbine Cogeneration System Thermal Equipment/ Cogeneration

9. 9 © UNEP 2006 Steam exits the turbine at a higher pressure that the atmospheric Back Pressure Steam Turbine Thermal Equipment/ Cogeneration Fuel Figure: Back pressure steam turbine Advantages: -Simple configuration -Low capital cost -Low need of cooling water -High total efficiency Disadvantages: -Larger steam turbine -Electrical load and output can not be matched Boiler Turbine Process HP Steam Condensate LP Steam Type of Cogeneration Systems

10. 10 © UNEP 2006 Steam obtained by extraction from an intermediate stage Remaining steam is exhausted Relatively high capital cost, lower total efficiency Control of electrical power independent of thermal load Extraction Condensing Steam Turbine Thermal Equipment/ Cogeneration Boiler Turbine Process HP Steam LP Steam Condensate Condenser Fuel Figure: Extraction condensing steam turbine Type of Cogeneration Systems

11. 11 © UNEP 2006 Operate on thermodynamic “Brayton cycle” atmospheric air compressed, heated, expanded excess power used to produce power Natural gas is most common fuel 1MW to 100 MW range Rapid developments in recent years Two types: open and closed cycle Gas Turbine Cogeneration System Thermal Equipment/ Cogeneration Type of Cogeneration Systems

12. 12 © UNEP 2006 Open Brayton cycle: atmospheric air at increased pressure to combustor Open Cycle Gas Turbine Thermal Equipment/ Cogeneration Air G Compressor Turbine HRSG Combustor Fuel Generator Exhaust Gases Condensate from Process Steam to Process Old/small units: 15:1 New/large units: 30:1 Exhaust gas at 450- 600 o C High pressure steam produced: can drive steam turbine Figure: Open cycle gas turbine cogeneration Type of Cogeneration Systems

13. 13 © UNEP 2006 Working fluid circulates in a closed circuit and does not cause corrosion or erosion Any fuel, nuclear or solar energy can be used Thermal Equipment/ Cogeneration Closed Cycle Gas Turbine Heat Source G Compressor Turbine Generator Condensate from Process Steam to Process Heat Exchanger Figure: Closed Cycle Gas Turbine Cogeneration System Type of Cogeneration Systems

14. 14 © UNEP 2006 Used as direct mechanical drives Reciprocating Engine Cogeneration Systems Thermal Equipment/ Cogeneration Figure: Reciprocating engine cogeneration system (UNESCAP, 2000) Many advantages: operation, efficiency, fuel costs Used as direct mechanical drives Four sources of usable waste heat Type of Cogeneration Systems

15. 15 © UNEP 2006 Supplied fuel first produces power followed by thermal energy Thermal energy is a by product used for process heat or other Most popular method of cogeneration Topping Cycle Thermal Equipment/ Cogeneration Type of Cogeneration Systems

16. 16 © UNEP 2006 Topping Cycle Thermal Equipment/ Cogeneration Type of Cogeneration Systems

17. 17 © UNEP 2006 Bottoming Cycle Thermal Equipment/ Cogeneration Primary fuel produces high temperature thermal energy Rejected heat is used to generate power Suitable for manufacturing processes Type of Cogeneration Systems

18. 18 © UNEP 2006 Bottoming Cycle Thermal Equipment/ Cogeneration Type of Cogeneration Systems

19. 19 © UNEP 2006 Training Agenda: Cogeneration Thermal Equipment/ Cogeneration Introduction Types of cogeneration systems Assessment of cogeneration systems Energy efficiency opportunities

20. 20 © UNEP 2006 Assessment of Cogeneration Systems Overall Plant Heat Rate (kCal/kWh): Ms= Mass Flow Rate of Steam (kg/hr) hs= Enthalpy of Steam (kCal/kg) hw= Enthalpy of Feed Water (kCal/kg) Overall Plant Fuel Rate (kg/kWh) Performance Terms & Definitions Thermal Equipment/ Cogeneration

21. 21 © UNEP 2006 Steam turbine efficiency (%): Steam Turbine Performance Thermal Equipment/ Cogeneration Gas Turbine Performance Overall gas turbine efficiency (%) (turbine compressor): Assessment of Cogeneration Systems

22. 22 © UNEP 2006 Heat recovery steam generator efficiency (%): Ms= Steam Generated (kg/hr) hs= Enthalpy of Steam (kCal/kg) hw= Enthalpy of Feed Water (kCal/kg) Mf= Mass flow of Flue Gas (kg/hr) t-in= Inlet Temperature of Flue Gas ( 0 C) t-out= Outlet Temperature of Flue Gas ( 0 C) Maux= Auxiliary Fuel Consumption (kg/hr) Heat Recovery Steam Generator (HRSG) Performance Thermal Equipment/ Cogeneration Assessment of Cogeneration Systems

23. 23 © UNEP 2006 Training Agenda: Cogeneration Thermal Equipment/ Cogeneration Introduction Types of cogeneration systems Assessment of cogeneration systems Energy efficiency opportunities

24. 24 © UNEP 2006 Energy Efficiency Opportunities Steam turbine: Keep condenser vacuum at optimum value Keep steam temperature and pressure at optimum value Avoid part load operation and starting & stopping Steam Turbine Cogeneration System Thermal Equipment/ Cogeneration

25. 25 © UNEP 2006 Energy Efficiency Opportunities Gas Turbine Cogeneration System Thermal Equipment/ Cogeneration Gas turbine – manage the following parameters: Gas temperature and pressure Part load operation and starting & stopping Temperature of hot gas and exhaust gas Mass flow through gas turbine Air pressure