密闭空间内氢气和二氧化碳甲醇化系统的非均相模型及反应特性

Numerical Study on Reaction Characteristics of Carbon Dioxide Hydrogenation to Methanol in Habitable Confined Space Based on Heterogeneous Models

在载人密闭空间内通过电解水方式为乘员供氧会产生副产物氢气(H_(2))。此外,乘员还呼出二氧化碳(CO_(2))。将H_(2)和CO_(2)催化合成甲醇(CH_(3)OH)是消除载人密闭空间内富余H_(2)和CO_(2)的最优方式之一。对其开展反应过程建模及反应特性研究有助于进行反应过程的控制,更好地维持载人密闭空间内的大气平衡。本文采用微元法建立了H_(2)和CO_(2)催化合成甲醇的物料计算模型和温度一维非均相模型,研究了不同反应压力、冷却介质温度以及入口反应气体中CO_(2)与CO比值等反应条件下的反应特性变化规律。结果显示,反应压力的增加、冷却介质的温升以及入口气体中CO_(2)与CO比值的减小均能促进各反应速率增加,进而使得H_(2)和CO_(2)消除量增加、甲醇合成率上升以及催化剂和反应气体最高温度上升。在保证反应速率增加且催化剂最高温度不超过合理反应温度区间的最大值573.15 K时需维持反应压力不大于8 MPa,冷却介质温度不高于538.15 K以及CO_(2)与CO比值不小于1。

In the habitable confined space,hydrogen(H_(2)),the by-product of water electrolysis to provide breathing oxygen to crews,and crew’s exhaled carbon dioxide(CO_(2))are the two surplus gases which should be eliminated for maintenance of atmospheric balance and protection of crew’s life safety.Catalytic synthesis of methanol(CH_(3)OH)from H_(2) and CO_(2) is one of the best ways to eliminate surplus H_(2) and CO_(2) in manned confined space.The conclusions drawn through reaction modeling and characteristic analysis can guide the control of the reaction process,which is conducive to maintaining the atmospheric balance in confined space.In this paper,based on the established material calculation model and temperature one-dimensional heterogeneous model,the reaction characteristics of catalytic synthesis of methanol from H_(2) and CO_(2) under different reaction pressures,coolant temperatures,and CO_(2) to CO ratios were studied.Results show that the increase of reaction pressure,the growth of coolant temperature,and the decrease of CO_(2) to CO ratio in inlet gas can all promote the increases of reaction rate,methanol synthesis rate,and the maximum temperatures of catalyst and reactant.Besides,in order to keep the catalyst maximum temperature within a reasonable reaction range(lower than 573.15 K),the reaction pressure should not be higher than 8 MPa,the coolant temperature is not higher than 538.15 K,and the ratio of CO_(2) to CO is not less than 1.