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THEME PAPER ON. SUPER-CRITICAL. AND. ULTRA SUPER-CRITICAL. POWER PLANTS. Prof. D.N. Reddy Director Centre for Energy Technology and Principal University College of Engineering Osmania University Hyderabad – 7. NEXT GENERATION POWER PLANTS. Criteria for selection Efficiency
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THEME PAPER ON SUPER-CRITICAL AND ULTRA SUPER-CRITICAL POWER PLANTS Prof. D.N. ReddyDirectorCentre for Energy Technologyand PrincipalUniversity College of EngineeringOsmania UniversityHyderabad – 7.
NEXT GENERATION POWER PLANTS Criteria for selection • Efficiency • Environmental protection • Availability of fuel • Power generation cost • Investment costs • Financing
Main advantages of Super-Critical Steam Cycle • Reduced fuel cost due to improved thermal efficiency • Reduction of CO2 emissions by 15% per unit of Power generated compared to sub-critical • Very good part load efficiencies • Plant costs are comparable with sub-critical units
Very low emissions NOx, SOx and particulate using modern Flue Gas Clean-up Equipment (FGD) Sub-critical units operating below 221.2 bar pressure and 374.15oC Super-critical units - Coal Fired Oil / Gas FBC, HRSG
Current State-of-Art Super-critical Steam Power Generation Plants Pressure - 300 bar Temperature - 600oC Efficiency - 45% (LHV Basis) Nickel based alloys allows up 650oC By the year 2005 - 620 oC By the year 2020 - 650-700 oC Cycle Efficiency - 50-55%
Steam Cycle Optimization • Improvement of Plant-auxillaries efficiency • Cycle layout • Increasing Feed water temperatures • Reducing flue gas temperature • Use of vertical furnace wall tubing Supercritical units potential Present - 5 GW 2020 - 25-40 GW/per annum
R&D in Super-Critical • Materials Limitations are major factors limiting further development, with key constraints at the furnace wall, super heater and re-heater outlets, and the first stage of the HP and IP turbines. • Other developments are under way, mostly by individual manufacturers to Optimize Cycle Design improve individual components, which are resulting in incremental heat rate improvements.
No significant opportunities for Retrofit ofSuper-Critical Technology to existing (predominantly sub-critical) plants have been identified. • FBCs using Super-Critical Steam Cycles are now being developed. A 350 MW PFBC is under construction in Japan.
The indications are that HRSGs will progressively move to Once-Through Technology and then to supercritical pressures as GTs become larger and exhaust temperatures rise. • Power Cycle Optimization taking into account such parameters as the number of reheats employed, inlet steam conditions and feedwater heater arrangement.