利用LNG冷能的间接冷冻法海水淡化流程比较

Comparison of indirect freezing seawater desalination processes utilizing LNG cold energy

淡水资源缺乏已成为全球性问题,海水淡化方法的研究也日益引起重视。液化天然气在气化时有大量冷能可以利用,考虑到冷冻法海水淡化需要大量冷能,可以把LNG的冷能和冷冻法海水淡化结合起来,形成利用LNG能冷的冷冻法海水淡化流程。文中以间接冷冻法为例,介绍了LNG冷能在海水淡化中的利用;并针对系统中冷媒是否相变而提出了无相变流程和有相变流程,通过HYSYS软件进行模拟,比较分析了各自的优缺点。结果说明无相变流程设备简单、控制方便,但冷媒质量流量大;有相变流程冷媒质量流量小,但流程、设备与控制均较复杂,气相部分体积流量较大,使得气态管路直径较大,相应的换热器尺寸也会更大。

Lack of freshwater resources has become a global problem,and desalination methods have been studied more and more.LNG will release a lot of cold energy during its vaporization process.Considering that freezing desalination systems needs much cold energy,they can be integrated with utilization of LNG cold energy.This paper studied indirect freezing seawater desalination with LNG cold energy utilization,and presented two cycle schemes in accordance with the state of middle refrigerant,that were non-phase-change process and phase-change process.The two different cycles were simulated through HYSYS software.In the end,the advantages and disadvantages of the two processes were discussed.The results show that non-phase process can be controlled easily,but it has much larger refrigerant flow rate;for the phase-change process,the refrigerant mass flow rate is smaller,but the controlling process and equipments are more complex.The gas volumetric flow rate is so large that the diameter of gas pipeline and the size of heat exchangers will be larger.