合成气甲烷化反应积炭过程的热力学分析

Thermodynamic analysis of carbon deposition on catalyst for the production of substitute natural gas

建立了煤制替代天然气工艺中合成气甲烷化过程的热力学计算模型,并对该反应体系的10个反应进行了分析计算,得到了各组分的平衡组成和各反应的标准化学平衡常数。研究了反应温度、操作压力、原料气组分浓度和产品气循环比等对催化剂床层积炭的影响,发现容易导致积炭的热力学条件为550～800℃的反应温度和0.1～1.5 MPa的操作压力,且温度在700℃左右、操作压力低于1.0 MPa时催化剂床层积炭量最大。本研究针对催化剂床层积炭规律提出了低温、相对高压、合理的原料气组成是有利于缓解催化剂床层积炭、提高产品收率及保持催化剂活性的优化反应操作条件。

A comprehensive thermodynamic analysis was made on the carbon deposition behavior for the production of substitute natural gas （SNG） through syngas methanation. The component concentrations and the equilibrium constants of ten reactions involved in the syngas methanation were calculated at different temperatures; the effects of temperature, pressure, and the addition of other compounds in the feed gas on the behavior of carbon deposition were investigated. The results indicated that the catalyst bed is prone to carbon deposition at 550 - 800 ℃ and 0.1 - 1.5 MPa; as a result, lower temperature, higher pressure, and a larger H2/ CO ratio are suitable for the methanation reactions. The addition of steam in the feed gas may alleviate the carbon deposition to a large extent, whilst a large amount of CO2 or CH4 in feed gas may lead to carbon deposition.