Integration and optimization of an air separation unit (ASU) in an IGCC plant

The integrated gasification combined cycle (IGCC) is a promising and efficient electrical power generation technology with less environmental effects than conventional coal power plant. However, improvement of its efficiency is an important task needs to be achieved. In this paper, a mathematical model of an IGCC plant is built, which includes a gasification unit, an air separation unit (ASU) and a combined cycle unit with energy and mass conversion. Gibbs free energy minimization method is used for predicting the composition of the syngas. Isentropic process calculation with efficiencies are taken into account for modelling the combined cycle. ASU is simulated mainly using bubble point method which can give rigorous prediction of the double distillation columns. Some contributions have been done to give the better strategy for supplying initial value to converge and to achieve the integration. The overall efficiency of 39.8. % can be reached considered as a base case, and simulated using Microsoft® Excel 2013. An additional case with not standard ASU is followed. The comparison between two cases shows that the Standard ASU may not the best choice of each IGCC plant. Some adjustments may be needed to fit the ASU with the whole plant to improve the overall efficiency.