天然气脱硫装置吸收塔模拟及增产措施

Simulation of absorber in natural gas desulfurization unit and stimulation measures

关键词:  天然气净化  脱硫单元  二氧化碳  硫化氢  吸收塔  增产措施 

Key words:  natural gas purification  desulfurization unit  carbon dioxide  hydrogen sulfide  absorber  stimulation measure

摘要:

目的 某天然气净化厂已完成过程气羰基硫(COS)水解的改造工作,解决了商品气中总硫含量超标的问题,但商品气中二氧化碳(CO₂)摩尔分数过低(约0.25%),严重制约了商品气产率的有效提升,探究合适的增产措施可实现企业的降本增效。方法 利用HYSYS流程模拟软件构建了该净化厂两级吸收塔模型,分析了吸收塔塔板数、溶液循环量及脱硫剂组成对天然气净化的影响规律,重点研究了对商品气中CO₂摩尔分数的影响规律。结果 ①在不调整脱硫剂组成的前提下,减少两级吸收塔共5块塔板,同时,贫液和半富液循环量降至操作下限,商品气中硫化氢(H₂S)质量浓度不会超标,且CO₂摩尔分数可提升至0.87%；②在调整脱硫剂组成的前提下,减少两级吸收塔共5块塔板,同时,贫液和半富液循环量降至下限值运行,商品气中H₂S质量浓度仍不会超标,且CO₂摩尔分数可提升至2.47%。结论 对吸收塔模拟及增产措施的研究可指导该天然气净化厂的技改,提高商品气产率,为同类型大型高含硫天然气净化厂的技改优化提供借鉴。 

Abstract:

Objective A natural gas purification plant has completed the transformation of carbonyl sulfur(COS) hydrolysis in process gas, and the problem of excessive total sulfur content in commercial gas has been completely solved. However, the low carbon dioxide(CO₂) mole fraction in commercial gas seriously restricts the effective improvement of commercial gas yield. Exploring suitable stimulation measures can reduce cost and increase benefit of the plant. Methods The two-stage absorber model of the plant was constructed by using HYSYS process simulation software. The effects of the absorber plates numbers, the solution circulation rate, and the desulfurizer composition on natural gas purification were investigated, and the effect on the CO₂ mole fraction in commercial gas was mainly explored. Results (1) Under the premise of not adjusting the composition of the desulfurizer, a total of 5 plates in the two-stage absorber were reduced, meanwhile the flow rate of lean and semi-rich amines was decreased to the lower limit of operation, the hydrogen sulfide(H₂S) mass concentration in the commercial gas could not exceed the standard, and the CO₂ mole fraction increased to 0.87%. (2) Under the premise of adjusting the composition of the desulfurizer, a total of 5 plates in the two-stage absorbers were reduced, meanwhile the flow rate of lean and semi-rich amines was decreased to the lower limit of operation, the H₂S mass concentration in the commercial gas still could not exceed the standard, and the CO₂ mole fraction eventually increased to 2.47%. Conclusion sThe study of absorber simulation and stimulation measures can guide the technological transformation of the plant, improve the commercial gas yield, and provide a reference for the technological transformation of large-scale natural gas purification plants with high sulfur content.