不同均压方式对PSA和VSA空分制氧过程的影响

摘要

对存在于变压吸附(PSA)和真空变压吸附(VSA)空分制氧过程中的均压步骤进行研究,应用ASPEN-ADSIM软件,模拟并比较4种不同均压方式(塔顶向塔顶均压(T-T),塔底向塔底均压(B-B),塔顶和塔底双向均压(TB),塔顶向塔底均压(T-B))对过程的影响,分析均压步骤的物流浓度、流量以及均压结束时床层轴向浓度分布.结果表明:采用T-B均压方式的PSA和VSA过程得到的产品O2纯度和收率最高.在均压步骤,均降床层塔顶出气有利于死空间中O2的回收,且减少床层吸附相中N2的脱附带出,从而得到较高的产品O2收率；均升床层塔底进气可使床层N2的质量摩尔浓度前沿陡峭,塔顶洁净,因此得到较高的产品O2纯度.%The pressure equalization step in O2 production from air of pressure swing adsorption(PSA) and vacuum swing adsorption( VSA) processes was studied. Influences of four different pressure equalization modes (the two beds connected by top to top (T-T) ,bottom to bottom(B-B) ,top and bottom both sides(TB) ,top to bottom (T-B)) on O2 production from air were simulated by ASPEN-ADSIM. Accordingly , the O2 concentration and flowrate of the stream in the pressure equalization step and the bed concentration profiles at the end of pressure equalization step were investigated. Results showed that PSA and VSA processes adopting, the pressure equalization mode of T-B had the highest O2 purity and O2 recovery. During pressure equalization step, opening the outlet end of bed 1 ( experiencing the step of de-pressurizing pressure equalization) to discharge gas benefit the increasing of O2 recovery of product, but opening the inlet end of bed 2 (experiencing the step of pressurizing pressure equalization) to let gas in from bed 1 had the benefit to increasing O2 purity of product.