Performance evaluation of air-blown IGCC polygeneration plants using chemical looping hydrogen generation and methanol synthesis loop

Abstract

Three chemical processing units by the integrated intermittent chemical-looping air separation (IICLAS), the chemical-looping hydrogen generation (CLHG), and the methanol synthesis loop (MSL) are integrated to retrofit the integrated gasification combined cycle (IGCC) system configuration. Four designs are presented and their performances are evaluated according to net efficiency, energy storage ratio (ESR), water saving ratio (WSR), and carbon emission rate (CER). An oxy-fuel IGCC power plant using IICLAS (Design 1) achieves 45.19% of net (thermal) efficiency. An oxygen-blown IGCC polygeneration plant with an integration of IICLAS and CLHG (Design 2) produces electricity and pure hydrogen simultaneously, and its net efficiency is up to 54.04%. An air-blown IGCC polygeneration (power/H2) plant without Brayton cycle and IICLAS (Design 3) ensures its net efficiency with 59.43%. An air-blown IGCC polygeneration plant with an integration of CLHG and MSL (Design 4) produces electricity, hydrogen, and methanol simultaneously, and its net efficiency could be as high as 60.42%. In addition, it is verified that Design 4 not only ensures the higher ESR due to hydrogen and methanol as storable fuels, but also it has an inherently lower environmental impact due to the lower CER, the higher WSR, and very low NOx emissions.