Dynamic Modelling and Controllability Studies of a Commercial-Scale MEA Absorption Processes for CO2 Capture from Coal-Fired Power Plants

This paper presents a mechanistic dynamic model of an industrial-scale carbon dioxide (CO2) capture plant using Monoethanolamine (MEA) as an absorbent. In order to remove 87% of CO2 from the flue gas stream generated from a 750 MW supercritical coal-fired power plant and produce a CO2 concentration of 95% in the CO2 product stream, a post-combustion CO2 capture plant with three absorbers and two strippers are needed,. A decentralized control structure composed of 11 proportional-integral (PI) controllers was proposed to maintain the dynamic operability of this commercial-scale CO2 capture plant. The evaluation of the plant's performance in closed-loop were conducted using multiple scenarios, i.e., the loss of CO2 recovery (% CC) control loop during variation of flue gas flow rate, a positive ramp change in the flue gas flow rate under a maximum withdrawal constraint on the reboilers' heat duty, and the disturbance in the flue gas composition resulting from the variation in coal composition and air flow rate. The controllability analysis performed on the proposed industrial-scale MEA absorption plant using the control system designed in this study shows that the plant is able to recover fast from most of the disturbances considered in the analysis. The insight provided from the present study can then be used to address the integration of the present CO2 capture plant to a coal-based power plant and evaluate the dynamic feasibility of this integration under various scenarios. (C) 2014 The Authors. Published by Elsevier Ltd.