大型FLNG/FLPG装置上部模块二氧化碳预冷双氮膨胀液化工艺方法

Liquefaction technology of CO_2-precooled dinitrogen expansion for large FLNG/FLPG device top module

针对FLNG/FLPG装置区别于常规FPSO以及陆上LNG工厂的关键和难点技术,以南海某深水气田为研究目标,开展了FLNG/FLPG装置液化工艺方案优化分析,提出了具有自主知识产权的CO2预冷双氮膨胀的海上FLNG液化工艺。对影响该工艺流程性能的关键参数进行了优化,分析了该工艺对于海上FLNG装置的适应性。结果表明:二级制冷工艺用于海上FLNG装置的天然气预冷过程,当二氧化碳一级制冷温度在-20℃左右,二级制冷温度在-50℃左右,氮气循环压缩机出口压力取8 MPa,两级氮膨胀制冷分界温度取-98℃,海水换热温差在8℃左右,单列总功耗为6.258×104 kW,液化率为93.7%,比功耗为0.327 1 kW·h/m3。该工艺安全性高、流程简单、设备紧凑、经济性较好,具有较好的海上适应性。(图6,表4,参8)。

In view of the key and difficult technology of FLNG/FLPG device which are different from conventional FPSO and onshore LNG plant, taking the deep water gasfield in South China sea as a research object, optimization analysis of liquefaction process scheme has been carried out for the device, offshore FLNG liquefaction process of CO2- precooled dinitrogen expansion has been proposed with independent intellectual property. The key parameters affecting the performance of the process have been optimized, and the adaptability of the process to offshore FLNG device has been analyzed. The results show that when the two-stage refrigeration technology is used in the gas cooling process of the offshore FLNG device, the temperature in the first stage of CO2 refrigeration is about -20 ~C, and -50 ~C in the second stage, the outlet pressure of the nitrogen recycle compressor is set at 8 MPa, the division temperature of the two-stage nitrogen expansion refrigeration is set at -98 ℃, and the heat transfer temperature difference is about 8 ℃, then the total power consumption is 6.258-104 kW, liquidation rate is 93.7%, and the specific power consumption is 0.327 1 kW·h/m3. This process is safe, simple, with compact equipment, economical and well adaptive to offshore working conditions. （6 Figures, 4 Tables, 8 References）