液化天然气冷量利用分析及集成优化

为提高液化天然气（LNG）冷量的利用效率，文章通过建立空气分离、低温粉碎和低温冷库等用冷装置的工艺模型，对各装置单独利用LNG冷量时的节能效果和利用过程的火用损进行了计算和分析，并在此基础上将空气分离、低温粉碎和低温冷库进行集成，按照“温度对口、梯级利用”的原则利用LNG的冷量。集成方案中，约-150℃的高压LNG先经空气分离装置利用冷量，再将从中抽出的一股约-101.8℃的LNG用于低温粉碎装置和低温冷库。通过模拟计算，结果表明集成利用时各装置利用LNG冷量的火用损比单独使用降低55.7％以上，使用单位LNG的冷量节省电量最大可达349.0 kWh/t，是单独用于空气分离装置省电量的1.56倍，大大提高了LNG冷量的利用效率。

Analysis of LNG cold energy utilization and its integrated optimization

In order to utilize sufficiently the cold energy carried by imported LNG, some models of technologies utilizing LNG cold such as air separation, cryogenic comminution and cold warehouse were established in this work, and the results of exergy lost and saved power of using unit LNG cold energy in these technologies were calculated and analysised. Based on these results, a LNG cold integrated utilization system including air separation, cryogenic comminution and cold warehouse was introduced. In the system, the cold energy of LNG, approximately -150.0℃, was used by an air separation equipment firstly, and a portion of LNG was exported to cryogenic comminution setting and cold warehouse to be utilized cold energy when it was warmed to about -101.8℃ from -150.0℃ in the air separation device. Aspen Plus sofetware was used to simulate the integrated utilization system, and the results showed that the exergy lost of integrated system could be decreased at least 55.7% than that of LNG cold used in a single technology. Compared with traditional technologies which didn’t utilize LNG, the largest amount of saved power by using cold energy of one ton LNG in the integrated system could reached 349.0 kWh, and the value was 1.56 times as that of only in an air separation equipment.