Full Plant Scale Analysis of Natural Gas Fired Power Plants with Pre-Combustion CO2 Capture and Chemical Looping Reforming (CLR)

Abstract

In this study, first of its kind complete plant scale integration of pre-combustion CO2 capture method with Chemical Looping Reforming (CLR) of Natural Gas (NG), Water Gas Shift (WGS) process, CO2 capture and CO2 compression in a combined cycle power plant has been presented. The CLR consisted of oxidation and fuel reactor. The oxidation reactor oxidizes the metal oxygen carrier with compressed air and produces an oxygen depleted air stream (N2 stream) as by-product. The fuel reactor reforms the NG with the metal oxide in presence of steam to produce syngas. The syngas is further subjected to WGS and CO2 capture using a-MDEA, to prepare a H2-rich fuel, which is combusted in the Gas Turbine (GT) system. The heat from cooling of process streams in the pre-combustion CO2 capture method, is used to prepare saturated low pressure steam, fraction of which is used in reboiler to regenerate the amine for CO2 capture, and the remainder is expanded in Steam Turbine (ST) to generate power. The power plant is a combined cycle with two GT, two Heat Recovery Steam Generators (HRSG) and one ST. 12% of air entering the GT is used in the oxidation reactor of CLR, and equivalent amount of N2 stream is compressed and added as diluent in the GT. The overall process was integrated and analysed at full load conditions. The current process has also been compared with Natural Gas Combined Cycle (NGCC) plant without CO2 capture. The net electric efficiency of the power plant with pre-combustion CO2 capture in this study is 43.1%, which is 15.3%-points less than the NGCC plant without capture. Major energy penalty in the process comes from air compressor, the diluent N2 stream compressor and due to low degree of process integration to avoid complexity.