Simultaneous Integration and Optimization of an IGCC Plant

Abstract

An Integrated Gasification Combined Cycle (IGCC) is a promising green technology applied for thermal power plants. It offers an efficient way to generate electricity from coal, biomass or any other suitable solid or liquid fuels with lower impact to the environment. The biggest challenge of making IGCC to become a viable technology is its high energy production cost. This creates a barrier for this green technology to enter into the stage of a highly competitive electricity market. An IGCC plant is a complex process system which involves processing units operated in very extreme conditions. Proper material and energy integration may provide a hope for cost reduction. In this paper, a mathematical model of an IGCC plant was built that includes a gasification unit, an Air Separation Unit (ASU) and a Combined Cycle unit. A modified Gibbs free energy model is used for predicting the composition of the syngas taking into account material and energy balances. The proposed gasification model results in syngas composition similar to the experimental data provided in literature. What’s more, Combined Cycle unit is simulated with isentropic assumption plus efficiency. While ASU is simulated mainly using the rigorous distillation model. Although individual processing unit optimization plays a significant role in enhancing the plant performance, an optimal integration among the three units still has significant potential to improve the efficiency, availability, and operability of a coal-fed IGCC power plant. The proposed mathematical model allows material and energy integration to be performed within and among different processing units while optimizing the IGCC plant as a whole. Different material and energy integration schemes were considered with respect to the overall thermal efficiency of the IGCC plant. The good performance is shown by about 2 % overall efficiency increment in the case study.