煤基合成气制SNG反应工艺的研究

Study on technical process of preparing substitute natural gas by coal-based syngas

采用2个模拟绝热反应器串联的模试装置,对自主研发的NCJ-1宽温型催化剂与NCJ-2低温型催化剂进行了活性评价,研究了煤基合成气制SNG的反应工艺。试验采用的原料气组成(φ)为:H268.4%,CO 19.6%,CO_23.0%,CH_49.0%,考察了空速、入口温度、新鲜气中CO_2体积分数、循环比、反应压力、一反入口加水量等条件对甲烷合成的影响。试验结果表明:空速上升对反应转化率和气体出口浓度的影响不太明显,但热点位置会下移;入口温度在高于250℃的前提下,随着温度的升高热点温度急剧上升;CO_2入口体积分数上升,CO_2转化率上升;通过改变循环比可以有效控制一反入口CO_x体积分数,使反应热点温度控制在催化剂允许的范围内;随着压力升高,热点温度、CH_4出口体积分数、CO转化率、CO_2转化率均上升;一反入口加水有利于控制床层温度,并有效保护催化剂,防止积炭。

The activity evaluation of NCJ - 1 wide-temperature catalyst and NCJ -2 low-temperature catalyst which are researched and developed independently is carried out on the module device combined by two series simulating adiabatic reactors,and the techni-cal process of preparing substitute natural gas （ SNG） by coal-based syngas is studied. T／ 68. 4% ,CO 19. 6% ,CO2 3. 0 % ,CH4 9. 0 % ,and the effects of space velocity,inlet temperature,volume fraction of CO2 in the fresh gas,recycle ratio, reaction pressure and water addition in the inlet of tlie first reactor on the synthesis of metliane are investiga-ted. The results show that the increase of space velocity has slight influence on the conversion asition of hot spot moves down. When the inlet temperature is higher than 250 Y ,the hot spot temperature sharply increases along withthe increase of inlet temperature. The conversion of CO2 enhances with the increase of volume fraction of CO2 in inlet. The volume frac-tion of CO2 and CO in inlet can be adjusted efectively by changing recycle ratio to control thie hot spot temperature in aiowable rangeof catalyst. The increase of pressure can result in rising of hot spot temperature,exit content of mCO. Adding water to the first reactor inlet is in favor of controlling the catalyst bed temperature, and has advantageoualyst effectively and avoiding carlDon deposit.