含杂环胺复合溶剂对天然气中酸性组分吸收效果实验研究

Experimental study on absorption effect of compound solvent containing heterocyclic amine on acidic components in natural gas

关键词:  羰基硫  杂环胺  吸收速率  中试  复合溶剂

Key words:  carbonyl sulfur  heterocyclic amine  absorption rate  pilot experiment  compound solvent

摘要:

目的 解决天然气脱除酸性气体过程中多数复合吸收溶剂对CO₂共吸收率过高、对部分工况条件下Claus硫磺回收单元的运行造成一定影响的问题。方法 对比不同杂环胺复合溶剂体系、不同杂环胺质量分数条件下其对天然气中CO₂和COS的吸收速率,优选了MDEA与杂环胺的复合体系在塔里木盆地某天然气净化厂进行现场侧线试验。通过考查不同气液比、不同MDEA与杂环胺配比条件下对天然气中酸性组分的吸收效果,并将MDEA、MDEA与1,8-二氮杂双环[5.4.0]十一碳-7-烯(DBU)的复合溶剂(MD)和Sulfinol-M对酸性组分的吸收性能进行对比。结果 当MD溶剂中MDEA与DBU复配质量比为5∶5、MD质量分数为40%时,相对于单一MDEA溶液,其COS、CH₃SH和CO₂脱除率分别提升43.4%、32.3%和5.5%。质量分数为40%的Sulfinol-M对CH₃SH和COS的脱除率相比MD分别高7.2%和低10.3%,但对CO₂脱除率达到92.2%。结论 使用单一的MDEA脱除酸性气体往往难以达到工业要求,而搭配不同杂环胺形成的复合溶剂体系可对酸性气体的吸收起到一定的促进作用。总结了几种不同的复合溶剂体系对酸性气体的吸收情况,可为其他天然气脱除酸性气体工艺提供参考。 

Abstract:

Objective To solve the problem that most of the composite absorption solvents have too high co-absorption rate of CO₂ in the process of natural gas deacidification, which will affect the operation of the Claus sulfur recovery unit under certain working conditions. Methods The absorption rate of CO₂ and COS was compared under the conditions of different heterocyclic amine composite solvent systems and mass fraction. The composite system of MDEA and heterocyclic amine was optimized for field sideline experiments in a natural gas purification plant in Tarim Basin. A method was adopted to examine the absorption effect of acidic components in natural gas under different gas-liquid ratios and different MDEA and heterocyclic amine ratios. The absorption performances of MDEA, MDEA and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) composite solvent (MD) and Sulfinol-M for acidic components were compared. Results When the MD solvent compound mass ratio of MDEA to DBU is 5∶5 and the mass fraction of MD was 40%, the removal rate of COS, CH₃SH and CO₂ was increased by 43.4%, 32.3% and 5.5%, respectively, compared with a single MDEA solution. The removal rate of CH₃SH and COS of Sulfinol-M with a mass fraction of 40% was 7.2% higher and 10.3% lower than that of MD, respectively, but the removal rate of CO₂ reached 92.2%. Conclusion sUsing single MDEA to absorb acid gas is often difficult to meet industrial requirements, and a composite solvent system formed with different heterocyclic amines can promote the absorption of acid gas to a certain extent. This article summarized the absorption of acid gas by several different composite solvent systems, which can provide a guidance to other similar process of removing acid gas from natural gas.