Abstract: Compared with the existing methods of light hydrocarbon recovery from low pressure natural gas, a new modified adsorption recovery process, which can reduce consumption and increase recovery ratio, has been put forward. The process consists of two stage temperature and pressure swing adsorptions (T-PSA). Water in raw gas is removed in the first stage, and light hydrocarbon is recovered from raw gas in the second stage. When the pressure of recovered liquid light hydrocarbon is not less than 1.6MPa, the hydrocarbon dew point, storage and transportation safety can meet project requirements, then the light hydrocarbon can be deemed as products. The recovery ratio of propane and butane are both higher than 94%, which have been increased by 30%—40% compared with common cryogenic recovery process and one stage temperature swing adsorption for light hydrocarbon recovery, economic benefits are obvious. Meanwhile, compared with the cryogenic recovery process, the operating flexibility and applicability of two stage temperature and pressure swing adsorption is higher and broader. And it is particularly applicable for small scale production or mobile facility. As a consequence, the modified adsorption recovery process is good for industrial application.

Key words: natural gas, light hydrocarbon recycling, separation, simulation, optimal design

摘要： 通过对现有低压天然气(0.3～1.6MPa)轻烃回收方法比较, 提出一种新的改进吸附回收工艺, 降低生产消耗, 提高轻烃的收率。本工艺采用两段变温变压吸附(T-PSA)方法相结合, 第一段T-PSA主要脱除原料气中水分, 第二段T-PSA主要回收原料气中的轻烃, 回收的轻烃以压力不低于1.6MPa的液相混烃作为产品, 保证烃露点要求, 满足储运安全。本工艺具有较高的轻烃收率, 丙烷和丁烷收率均大于94%, 较目前常采用的深冷回收方法和一段变温吸附法的轻烃收率提高了30%～40%, 带来明显的经济效益, 同时本工艺较外冷回收方法, 操作弹性更大, 适用性更强, 特别适合小规模生产或需要经常搬迁的生产环境。因此, 改进吸附回收工艺非常值得推广应用。

关键词: 天然气, 轻烃回收, 分离, 模拟, 优化设计