天然气轻烃回收工艺设计及操作参数的优化

以廉价天然气中的乙烷和丙烷为原料的乙烯成本仅是石脑油等重质原料成本的30%,高压管输天然气进入城市门站分输需调压,调压过程中有大量压力能可利用。本文以某段高压管输天然气为原料,提出了处理量60×10⁴m³/h的轻烃分离回收工艺流程,综合考虑轻烃回收率、系统功耗、CO₂冻堵、冷箱传热温差等因素,优化操作参数,完成了系统能量的高效集成,实现了轻烃分离工艺的节能降耗。该方案C₂回收率达90%以上,可为乙烯装置提供优质的乙烷等轻烃原料50.75万吨/年,有利于解决乙烯工业发展的原料瓶颈,提高天然气、乙烯工业的整体经济效益。

Design of light hydrocarbon recovery process from natural gas and the optimization of operation parameters

While raw material changes to ethane and propane from cheap natural gas, the production cost of ethylene is only 30% of the cost when heavy oil, such as naphtha, is adopted as raw material. In addition, during the transmission of natural gas into cities, natural gas at high-pressure needs to get pressure adjustment, and the process can generate lots of pressure energy available. The paper proposes a process to separate and recover light hydrocarbon from high-pressure natural gas. The capacity is 60×10⁴m³/h. With the consideration of light hydrocarbon recovery, system consumption, CO₂ freezing and cold box heat transfer temperature difference, operating parameters are optimized to accomplish an efficient system energy integration, therefore achieve energy-saving and cost-reducing of the whole process. In this work, C₂ recovery rate can reach up to 90%, thus can provide 557500 tones of high quality ethane per year for ethylene unit, which can break the bottleneck of raw material in the development of ethylene industry, and enhance the overall economic benefits of natural gas and ethylene industry.