吸附及解吸压力对快速变压吸附床内速度及循环性能的影响

快速(真空)变压吸附循环周期较短,床层压力周期性变化快,使吸附床内流动及传热传质特性变化较大,本文研究吸附及解吸压力对快速变压吸附制氧床内速度及循环性能的影响。快速变压吸附( rapid pressure swing adsorption, RPSA)循环中原料气充压阶段气流速度远大于顺流的气体流速极限值,快速真空变压吸附( rapid vacuum pressure swing adsorption, RVPSA)循环中原料气充压阶段气流速度略大于顺流的气体流速极限值,而RPSA循环和RVPSA循环中放空降压阶段气流速度均较大。在所研究的吸附和解吸压力范围内,RPSA循环和RVPSA循环中气体温度在循环周期内变化均约为10℃,而RVPSA循环中气体温度在循环周期内温度梯度更大。 RPSA循环中吸附压力越高,氧气回收率越高,床层因子越小；而RVP-SA循环中解吸压力越低,氧气回收率越高,床层因子越小。

Effect of adsorption and desorption pressure on the velocity and cycling performance of rapid pressure swing adsorption

Rapid (vacuum) pressure swing adsorption (RPSA or RVPSA) is featured by short cycle time and quick pressure change, which may lead to great variations of flow and mass and heat transfer in the adsorber. The effects of adsorption and desorption pressure on the velocity and cycling performance in an oxygen-production RPSA bed were investigated in this paper. The results show that during the feed pressurization ( PR) step in the RPSA process, the up-flow velocity is far larger than the limit value, and slightly larger than it for the rapid vacuum pressure swing adsorption ( RVPSA) process. During the blow-down step in both RPSA and RVP-SA, the down-flow velocity is greater than the limit value. In comparison to RPSA, RVPSA exhibits a similar gas temperature change around 10℃ but a larger gas temperature gradient. The bed size factor can be effectively reduced with increased oxygen recovery by increasing the adsorption pressure for RPSA, while by lowering the desorption pressure for RVPSA.