Simulation of post-combustion CO2 capture process by non-equilibrium stage hydrate-based gas separation technology

Abstract

To simulate the process of hydrate-based gas separation for post-combustion CO2 capture in non-equilibrium situation, the operational pressure of hydration reaction should be specified firstly, which was depending on the dissociation pressure and the driving force. As the main effect factor of dissociation pressure, the mole fraction of water L/(L+V) in the feed should be predicted in priori. And then the driving force could be sequentially determined based on the systematic analyses. In this work, a new computational method to predict L/(L+V) was proposed. Then based on the thermodynamic model, proposed in our previous work, CPA-SRK + Chen-Guo model, and the three-phase isothermal flash calculation method, we simulated the non-equilibrium stage hydrate-based gas separation technology (for the flue gas containing 17% CO2 and 83% N2 at the condition of 277K) with stage-by-stage calculation. For each stage, the optimized operational pressure of each stage was specified in advance, and then the rate as well as the composition of the main flows were subsequently calculated with flash calculation. Based on the obtained results, it was suggested that four stages of hydration reactions were necessary to obtain a 90% CO2 purity. Furthermore, the performances concerning on split fractions and separation factors were also assessed.