Efficiency evaluation of a coal-fired power plant integrated with chilled ammonia process using an absorption refrigerator

Abstract

Chilled ammonia process (CAP) is an alternative process for inhibiting ammonia escape during the CO2 capture process. In this paper, the integration of a coal-fired power plant with CAP, using an absorption refrigerator (AR) to provide the chilling load, is proposed. The thermal energy consumption of the CAP and the AR, derived from a crossover pipe between the intermediate pressure and low pressure (IP-LP) steam turbine sections and from an appropriate port of a low pressure (LP) turbine, are the basic scenarios considered for this study. A systematic evaluation of a 300-MWe coal-fired power plant is conducted and its overall process is compared with the power plant integrated with CAP using the conventional vapor compression refrigerator (VCR). An analysis of the basic scenarios reveals that the efficiency penalties reduced from 13.23% to 9.82% when the steam extractions were from the IP-LP crossover pipe and LP turbine, of which a 4.26% and 2.96% loss, respectively, was contributed by the AR. Decreasing the chilling temperature, while increasing the regenerating temperature can reduce the efficiency penalty. A comparative investigation of the lower efficiency penalties of various COPa and COPc are recommended. Better performance can be achieved by VCR integration if the COPc is higher than 2.0 and 3.5. The results from and an understanding of the two types of refrigerators can be used as the basis for system design and optimization.