2010Combined Cycle HW Q and A

# 2010Combined Cycle HW Q and A - Combined Cycle Problem Set...

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Center for Advanced Energy Systems Michael R. Muller, Director 640 Bartholomew Road, Piscataway NJ 08854 (732) 445-3655 FAX: (732) 445-0730 [email protected] http://caes.rutgers.edu Combined Cycle Problem Set Problem 1: A combined-cycle power plant consists of a topping gas turbine plant with a thermal efficiency of 0.385, an HRSG, and a bottoming steam turbine plant with a thermal efficiency of 0.31. Calculate a) the overall efficiency of the CC power plant., b) the net heat rate in kJ/kWh, and c) the heat input rate in MW and d) the GT and ST power outputs in MW and their ratio if the CC power output is 400 MW. Solution: From the picture it looks like Q Stack and Q cw should be treated separately in terms of determining the bottoming cycle efficiency. However, both are implicitly used in the calculation. When a boiler is considered in a Rankine cycle, there are losses in combustion which are not included in the first pass, but generally are included when Q in is calculated. η CC = η GT + η ST (1- η GT ) = η GT + η ST - ( η ST x η GT ) Note that the energy not put into useful work in the gas turbine cycle becomes heat input to the steam cycle {or Q in - GT (1- η GT ) = Q in-st }. η CC = 0.385+0.31-0.31*0.385 = 57.6% Units for heating rate are different than in the notes: kWh kJ HR / 6250 576 . 0 3600 3600 = = = η

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Center for Advanced Energy Systems Michael R. Muller, Director Q in = W/ η CC = 694 MW W GT = 0.385 *694 = 267 MW, W ST = 400-267 = 133; ratio = 2.0 Problem 2: Atmospheric air enters the air compressor of a simple combined gas-steam power systeam at 14.7 psia, 80
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## This note was uploaded on 02/08/2011 for the course ME 650:462 taught by Professor Muller during the Fall '10 term at Rutgers.

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2010Combined Cycle HW Q and A - Combined Cycle Problem Set...

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