Hydrate-based CO2 capture has been paid increasing attention, due to such advantages as the mild operating pressure and temperature, the ease of regeneration and its unique separation mechanism. Hydrate formation is an exothermic process, in which large amount of heat released must be quickly removed, otherwise the formation will slow down and finally cease. This work presents the kinetic and separation efficiency study for purifying simulated IGCC fuel gas (40 mol%CO2/H2 gas mixture) through hydrate crystallization by direct heat removal method. Synergic additives comprise gas solvent (dimethyl sulfoxide (DMSO)), traditional hydrate promoter (tetra-n-butyl ammonium bromide (TBAB)) and phase change material (PCM) n-Tetradecane were used to enhance and intensify the hydrate-based separation process. To evaluate the separation process, hydrate grow rate, gas storage capacity, gas selectivity and separation efficiency were systematically investigated. The result shows that, the hydrate growth rate obtained with the PCM particles were five to nine times larger than those achieved under indirect heat removal. The induction time was only 3-5 minutes and sometimes was even less than 1 minute. The synergic additives could promote the mixture hydrate formation process due to DMSO (acid gas solvent) could improve both rate and selectivity of CO2 during the dissolution and diffusion processes. At the temperature of 274.15 K and under driving force of 3.0 MPa, CO2 concetration in hydrate slurry phase was increased from 40 mol% to approximately 95 mol% in one stage separation. After a two stage separation, CO2 in the residual gas phase could reach a concentration as low as 10 mol%.

Intensification of capture CO2 from IGCC flue gas by hydrate formation under direct heat removal by phase change of n-tetradecane

251st National Meeting (2016)

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