Experimental analysis of CO2 frost front behaviour in moving packed beds for cryogenic CO2 capture

Abstract

In this work, the feasibility of a novel method of cryogenic carbon capture based on carbon dioxide frost deposition onto a cold moving bed is explored. As a gas mixture including CO2 flows through a sufficiently cold packed bed, CO2 is deposited onto the bed material as a frost. As the bed is warmed by the gas stream the frost front advances through the bed. Experimental measurements of the rate of frost advance within a static packed bed are used to set up a moving bed to achieve continuous CO2 removal. Precooled and dry binary gas mixtures of CO2 and nitrogen are used to determine frost front velocity in a capture column. The frost front velocity measured in fixed bed experiments with varying CO2 concentrations and gas flow rates are in the range of 0.4–1 mm/s. The experimental results were used to design a moving bed system that would match this range of frost front velocities so that continuous capture would be possible. Experiments were conducted to investigate the behaviour of temperature profiles within the capture column under moving bed conditions. These show that frost accumulation does not occur and successfully demonstrates continuous cryogenic carbon capture.