Two-phase flow in a supersonic separator for carbon capture

Abstract

This work investigates a possible approach of carbon capture and two-phase flow involved. The nonequilibrium condensation, high velocity flow and shock wave in decarbonization process are described by a mathematical model. The separator is optimized through the calculations. The results show that the nonequilibrium state makes CO2 in flue gas condense spontaneously, and the system does not transfer to the equilibrium state instantly when condensation nuclei appear, but gradually turn to the equilibrium state after nucleation rate reaches the maximum. The separator with a larger separation angle is the first to condense, and the liquefied CO2 content is higher, while separator with a smaller angle produces larger droplets. Reducing the contraction ratio makes the shock wave move to the exit, and obtain higher liquid content and larger droplets. In practice, increasing the separation section length equates to a longer droplet growth time, which facilitates carbon liquefaction and separation.