Simulation and energy consumption analysis of chemical looping air separation system on Aspen Plus

Abstract

Chemical looping air separation is a new method to separate oxygen from air. In the process, oxygen carrier releases oxygen in the reduction reactor and absorbs oxygen in the oxidation reactor. The reduction is endothermic, and the oxidation is exothermic. The heat transfer from oxidation reactor to reduction reactor is essential to design the CLAS process with low energy consumption. In this paper, the optimization CLAS process of CuO/ZrO₂ oxygen carrier was established based on thermal analysis and pressure analysis. In the system, the heat can achieve self-balance with little heat supplied from outside. The effects of the technological parameters on the system energy consumption were investigated using Aspen Plus software. The results show that the energy consumption decreases with reduction temperature increasing and oxidation temperature decreasing. Moreover, the smaller the difference of temperature between the two reactors is, the lower energy consumption is. Under negative pressure, with the decreasing reduction pressure, the energy consumption decreases. Under positive pressure, with the increasing oxidation pressure, the energy consumption decreases firstly and then increases. The optimization operating parameters are obtained. The lowest energy consumption of the system is 0.132 kWh m⁻³ at the conditions of 990 °C reduction and 1000 °C oxidation temperatures and 0.5 atm. reduction and 1.7 atm. oxidation pressures.