空气分离与天然气液化组合循环

Combined cycle of air separation and natural gas liquefaction

提出了利用空分系统冷量液化天然气的联合流程思想,并介绍了一种采用氮气膨胀循环的空气分离与天然气液化联合方案,在得到液化天然气(LNG)的同时,也生产氮气、氧气等多种产品。通过流程模拟计算并采用有效能分析原理,确定了高、低温膨胀量比对传热温差及有效能损失的影响规律,得到了不同液化量下的优化膨胀量之比。结果表明,基于热负荷总组合曲线的有效能分析原理能够方便、有效地研究整个传热过程的温差分布及有效能损失规律,对实际低温过程系统优化有重要意义。

An integrated process for air separation and liquefaction of natural gas was presented, and based on such an original idea a novel combined-cycle using nitrogen expansion refrigeration unit and producing LNG in addition to nitrogen and oxygen was proposed. Process simulation and second law analysis were performed to reveal the influence of flow rate ratio through expanders β on heat transfer temperature difference and consequent exergy loss, and thus the optimal β under different operation conditions was obtained. Hence, the change of temperature difference distribution and exergy loss in the heat exchanger could be investigated conveniently and effectively through the principle of exergy analysis in combination with energy composite curves. Such information is valuable for optimal design of practical cryogenic systems.