IGCC Process Alternatives for Simultaneous Power Generation and CO2 Capture

Abstract

Pre combustion and post combustion processes are the commercially available techniques used for power generation where pre-combustion power plants are more energy efficient if carbon capture and storage (CCS) technology is implemented on a large scale. However pre-combustion power plants tends to have higher capital and operating costs as compared to other post-combustion power plants. So in this study IGCC process which is a commercial example of pre-combustion technique has been developed in order to analyze the overall plant output with CO2 capture while discussing the economics of process. Three different schemes with consistent and transparent methodology have been proposed in order to ensure fair evaluation of analysis. First two cases use water gas shift (WGS) reactions scheme with sour shift catalysis process. The resulted syngas free of CO2 can either be combusted by using air or O2. The first case uses air as an oxidant for burning H2 and the combustor temperature is controlled by air as well. In the second case, O2 is used as an oxidizing agent for H2 combustion and combustion temperature is controlled by recycling the captured CO2. In the third case, WGS reactor and CO2 capturing unit is removed. The syngas composed of CO and H2 is sent directly for combustion with high purity O2 making it similar to an oxy-fuel combustion process and CO2 is recovered while condensing steam from the flue gas. All the results are compared in terms of power plant efficiencies and power output. Moreover an economics analysis has been performed to evaluate OPEX and CAPEX for all case studies. Simulation results showed that case 1 and 3 are the competitive options in terms of efficiency and power generation. Whereas the lowest OPEX, CAPEX and least CO2 emissions in 3rd case makes it the best option for power generation.