Abstract
Coal-integrated gasification/gas turbine (CIG/GT) based power plants are well known to achieve the advantage of higher electric efficiency and lower costs than direct combustion based power plants. Since the gasification is an endothermic, thermochemical conversion process, it requires heat to proceed. In general, this heat is furnished by internal combustion taking place in the gasifier by virtue of oxygen-blown or air-blown gasification. However, the direct combustion of the solid fuel is realized to be inefficient with respect to large amount of exergy destruction posed during the combustion, especially at relatively low temperature like gasification temperature. This causes the overall performance deterioration of the CIG/GT system. Therefore, a decrease in the exergy destruction during the combustion can contribute to improvement on the overall system efficiency. In this paper, an innovative concept of energy-recuperative gasification was proposed and incorporated in the CIG/GT system. The idea is to make use of the waste heat from the gas turbine exhaust as the reaction heat for the gasification instead of the internal combustion. This type of energy recuperation is also called thermochemical recuperation. In addition, the proposed CIG/GT incorporates other effective energy recuperation, including heat and steam recuperation, in order to maximize the generation efficiency. The feasibility of the concept implementation and the system improvement were preliminarily examined and discussed.
