天然气净化厂尾气达标排放对策

Countermeasures to satisfy the tail gas emission standard of natural gas purification plants

近年来,有关部门相继出台了严格的硫磺回收装置尾气排放控制指标,天然气净化厂硫磺回收装置尾气排放达标面临着巨大的压力和严峻的挑战。为此,对比了加拿大和美国天然气净化厂尾气SO_2排放标准,分析了我国天然气净化厂尾气SO_2排放执行标准的制订现状,以中国石油西南油气田公司(以下简称西南油气田)为例,对其现有的天然气净化厂尾气处理装置进行了技术经济性对比分析,并基于对技术先进性和经济合理性的综合考虑推荐了改造工艺。研究结果表明:①天然气净化厂硫磺回收率指标,我国明显高于欧美国家;②针对西南油气田各天然气净化厂特点,提出了升级溶剂并优化运行参数、有机胺法SO_2吸收技术改造、络合铁液相氧化还原技术改造和关停等4种改造方案,预计改造投资为5.59亿元;③对于硫磺回收规模较大(超过200 t/d)的天然气净化厂,建议选用还原吸收类工艺;④对于硫磺回收规模中等(5～200 t/d)的天然气净化厂,建议选用有机胺法和SO_2吸收工艺;⑤对于原料气中低潜硫量(不足10 t/d)的天然气处理装置,建议采用液相氧化还原工艺。结论认为,按推荐工艺改造完成后,西南油气田所有的硫磺回收装置尾气SO_2排放均能满足国家标准的规定,并且能达到国际先进水平。

In recent years,relevant authorities have successively issued strict control indicators on the tail gas emission of sulfur recovery facilities,so standard tail gas emission from the sulfur recovery facilities in natural gas purification plants is faced with enormous pressure and severe challenges.In this paper,the SO2 emission standards of natural gas purification plants in Canada and America were compared,and the formulation status of domestic SO2 emission standards was analyzed.Then,the existing tail gas processing units in natural gas purification plants were analyzed and compared technologically and economically with the PetroChina Southwest Oil&Gasfield Company as an example.Finally,the transformation process was recommended in consideration of technological advancement and economical rationality comprehensively.And the following research results were obtained.First,the domestic indicator of sulfur recovery ratio of natural gas purification plants is much higher than that in Europe and America.Second,considering the characteristics of all natural gas purification plants in this company,4 transformation schemes are proposed,including solvent upgrading&operation parameter optimization,transformation of SO2 absorption technology based on organic amine method,transformation of liquid-phase complex iron oxidation/reduction technology,and shut down.And the transformation investment is expected to be CNY 559 million.Third,as for the natural gas purification plants with higher sulfur recovery rates( >200 t/d),it is recommended to select the technologies of reduction absorption.Fourth,as for the natural gas purification plants with moderate sulfur recovery rates(5-200 t/d),it is recommended to select the SO2 absorption technology based on organic amine method.Fifth,as for the natural gas processing facilities whose potential sulfur rates of feed gas are low(<10 t/d),it is recommended to adopt the l iquid-phase oxidation/reduction technology.In conclusion,tail gas emission from all sulfur recovery facilities of this company can satisfy the national SO2 emission standard and reach the international advanced level after they are transformed by means of the recommended te chnologies.