CO2 capture by using hydrates: 4) From experimental evidences to economic impossibility as a post combustion process
Abstract
The post-combustion CO2 capture by using clathrates is a method which takes profit of the CO2 selectivity in gas hydrate to separate it from nitrogen, or other exhausting gases from gas combustion or coal combustion. The bottleneck is the operative pressure which still remains high and needs to be drop down to 0.5 MPa in order to compete with the reference case using Amines. After two national projects (SECOHYA, ACACIA) and an European program (iCAP), we tested different classes of thermodynamic additives, organic ones (water non soluble cyclopentane, water soluble THF) which form classical gas hydrates with structure SII, and ionic ones (Tetra-N-Butyl Ammonium Bromide, TBAB) which forms new types of structures, and mixture of promoters. In this presentation, we present a flow-sheet for a CO2 capture process, with two stages, a bulk and a finisher. After sizing, we emphasize that the volume of the bulk is similar to the volume of an Amine Process because the crystallization operates in a Gas/liquid transfer limitation regime. But, the volume of solvent to handle is much too large to be reasonable.
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