Study of CO₂ desublimation during cryogenic carbon capture using the lattice Boltzmann method

Abstract

Cryogenic carbon capture (CCC) can preferentially desublimate $\text {CO}_2$ out of the flue gas. A widespread application of CCC requires a comprehensive understanding of $\text {CO}_2$ desublimation properties. This is, however, highly challenging due to the multiphysics behind it. This study proposes a lattice Boltzmann (LB) model to study $\text {CO}_2$ desublimation on a cooled cylinder surface during CCC. In two-dimensional (2-D) simulations, various $\text {CO}_2$ desublimation and capture behaviours are produced in response to different operation conditions, namely, gas velocity (Péclet number $\textit {Pe}$ ) and cylinder temperature (subcooling degree $\Delta T_{sub}$ ). As $\textit {Pe}$ increases or $\Delta T_{sub}$ decreases, the desublimation rate gradually becomes insufficient compared with the $\text {CO}_2$ supply via convection/diffusion. Correspondingly, the desublimated solid $\text {CO}_2$ layer (SCL) transforms from a loose (i.e. cluster-like, dendritic or incomplete) structure to a dense one. Four desublimation regimes are thus classified as diffusion-controlled, joint-controlled, convection-controlled and desublimation-controlled regimes. The joint-controlled regime shows quantitatively a desirable $\text {CO}_2$ capture performance: fast desublimation rate, high capture capacity, and full cylinder utilization. Regime distributions are summarized on a $\textit {Pe}$ – $\Delta T_{sub}$ space to determine operation parameters for the joint-controlled regime. Moreover, three-dimensional simulations demonstrate four similar desublimation regimes, verifying the reliability of 2-D results. Under regimes with loose SCLs, however, the desublimation process shows an improved $\text {CO}_2$ capture performance in three dimensions. This is attributed to the enhanced availability of gas–solid interface and flow paths. This work develops a reliable LB model to study $\text {CO}_2$ desublimation, which can facilitate applications of CCC for mitigating climate change.

Cryogenic Process Optimization for Natural Gas Purification: Predictive Modeling of Methane–CO2 Solid–Vapor Phase Equilibrium Using Response Surface Methodology

“…Achieving the low temperatures necessary for efficient phase separation requires significant energy requirements, often leading to an expensive process. This energy-intensive process also escalates operational costs and complicates the economic viability of cryogenic methods . Furthermore, the cryogenic process infrastructure must endure severe thermal conditions, necessitating advanced materials and precision control mechanisms and elevating the initial capital outlay and maintenance complexity.…”

“…This energy-intensive process also escalates operational costs and complicates the economic viability of cryogenic methods. 16 Furthermore, the cryogenic process infrastructure must endure severe thermal conditions, necessitating advanced materials and precision control mechanisms and elevating the initial capital outlay and maintenance complexity. The need for precise control of thermodynamic parameters highlights the importance of strict design and operational standards.…”