Recovery of flue gas energy in heat integrated IGCC power plants using the contact economizer system

Abstract

In this work, the contact economizer system is used to recover low potential heat from the gas turbine exhaust (flue gas) stream of a heat integrated IGCC plant adopted from previous studies. Recovery of this heat was demonstrated to be capable of further increasing the thermal efficiency of the plant. Application of Mickley’s graphical technique for dehumidification in a contact economizer system following a slightly different procedure that allows calculation of the exact ratio between the liquid-phase heat transfer coefficient and gas-phase mass transfer coefficient demonstrated a possible increase in thermal efficiency from 54% to 55%. This method however is incapable of obtaining the optimum thermal efficiency due to the monotonous relationship between the boiler feed water temperature and the thermal efficiency of the plant.