Thermodynamic analysis and thermoeconomic optimization of a dual pressure combined cycle power plant with a supplementary firing unit

Abstract

In this paper, a combined cycle power plant (CCPP) with a supplementary firing system 
is first thermodynamically analyzed through energy and exergy. The optimal design of 
operating parameters of the plant is then performed by defining an objective function and 
applying a generic algorithm (GA) type optimization method. In order to optimally find the 
design parameters, a thermo-economic method is employed. An objective function representing 
the total cost of the plant in terms of dollar per second is defined as the sum of the operating 
cost related to the fuel consumption and the capital investment for equipment purchase and 
maintenance costs. Subsequently, different parts of the objective function are expressed in 
terms of decision variables. Finally, the optimal values of decision variables are obtained by 
minimizing the objective function using a GA. Moreover, the influences of changes in the demanded 
power and fuel cost are studied by considering three different output powers (i.e., 160, 180 and 
200 MW). To validate the present model, the results of the present simulation code are compared 
with the actual data. The results show that the average difference between the model results and 
the actual data is about 1.41%. Moreover, various cases are investigated to determine how to decrease 
the objective function (cost, mass flowrate, etc.) for the optimized design and operating parameters 
(fuel cost, power output, etc.). Crown Copyright (c) 2011 Published by Elsevier Ltd. All rights reserved.