应用于等离子体排灰气处理的甲烷水汽重整反应的热力学分析

Tokamak装置中的等离子体反应一段时间后，需对产生的排灰气进行净化处理，以回收其中的氘氚。目前拟采用甲烷水汽重整反应将化合态的氘氚转化为单质并回收。本文运用Gibbs自由能最小化方法，对应用于等离子体排灰气处理的水汽重整反应进行热力学分析，考查反应温度、原料比例、反应压力、O₂、CO₂、H₂、CO等因素对反应平衡的影响，确定了适宜的反应条件，即反应温度范围650～700 ℃，压力1×105 Pa，水碳比1.5～2.0。此外，原料气中O₂或CO₂的存在有利于减少积碳的生成量，并获得较高的氢同位素平衡转化率；H₂的存在对重整反应的热力学平衡无明显影响；CO的存在会使积碳量增加，对反应产生不利影响，在进入重整反应器前应将其去除。

Thermodynamic Analysis of Steam Methane Reforming Reaction Applied in Tokamak Exhaust Processing

In Tokamak exhaust processing system, steam methane reforming reaction is expected to convert deuterium and tritium in the gaseous compounds to elementary gas, then the deuterium and tritium can be reclaimed. The method of Gibbs free energy minimization was employed to analyze the thermodynamic balance of steam methane reforming reaction. The effect of many factors, such as reaction temperature, reactants ratio, pressure, O₂, CO₂, H₂ and CO, was investigated. The appropriate reaction condition is as follows: The temperature is between 650 ℃ and 700 ℃, the pressure is 1×10⁵ Pa, and the ratio of water to methane is 1.5-2.0. Moreover, the presence of O₂ or CO₂ in reactants is favorable to lessen the yield of solid carbon and increase the conversion rate of hydrogen isotope. The presence of H₂ does not affect the thermodynamic balance obviously, while CO increases solid carbon yield, which is a disadvantage to the reaction, so it needs to be wiped off before reaction.