Prof. D.N. Reddy Director Centre for Energy Technology and Principal University College of Engineering Osmania University Hyderabad – 7. THEME PAPER ON AND

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 CO 2 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 NO x, SO x and particulate using modern Flue Gas Clean-up Equipment (FGD) Sub-critical units operating below bar pressure and o C Super-critical units-Coal Fired Oil / Gas FBC, HRSG

Current State-of-Art Super-critical Steam Power Generation Plants Pressure-300 bar Temperature-600 o C Efficiency-45% (LHV Basis) Nickel based alloys allows up 650 o C By the year o C By the year o C 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 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 of Super- 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.