Mathematical Modeling Of HRSG with Duel Pressure using Pinch Principles

Abstract

Energy is the fundamental requirement of human life and thus a driving force of civilization so it must utilize very effectively at all levels. Due to increase fuel prices and depletion of fossil fuels resources, high efficiency energy conversion systems are utmost desirable. There is a great potential for increased ~fficiency in energy converting devices by recovering waste heat to greater extent. Thus, development of n "combined cycle power plants" (CCPPs) is most efficient ~effort in this direction due to high thermal efficiency. CCPP uses low carbon content fuels that reduce greenhouse gas production. CCPP couples a Brayton cycle with a Rankine cycle. The equipment where steam production takes place is named as "Heat Recovery Steam Generator" (HRSG). In CCPP the optimization of HRSG is of particular interest in order to improve the efficiency of the heat recovery from turbine exhaust gas to maximize the power production in steam cycle. In this paper, the optimization of dual pressure HRSG is carried out with pinch point method with selection of optimum pinch points for gas and steam profile. The effect of the pinch point on the mass flow rate is also calculated. The effect of different parameters like high pressure and low pressure pinch differences, etc. on the performance of HRSG have also been considered. The results indicate that the optimized duel pressure heat combined cycle is up to 2°/C) higher in efficiency than non optimized duel pressure heat combined cycle. The optimized system also yields power output higher by about 5%.