Department of Chemical & Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576, Singapore.
Water Res. 2012 Sep 1;46(13):4037-52. doi: 10.1016/j.watres.2012.04.042. Epub 2012 May 14.
The severe global water scarcity and record-high fossil oil price have greatly stimulated the research interests on new desalination technologies which can be driven by renewable energy or waste energy. In this study, a hybrid desalination process comprising freeze desalination and membrane distillation (FD-MD) processes was developed and explored in an attempt to utilize the waste cold energy released from re-gasification of liquefied natural gas (LNG). The concept of this technology was demonstrated using indirect-contact freeze desalination (ICFD) and direct-contact membrane distillation (DCMD) configurations. By optimizing the ICFD operation parameters, namely, the usage of nucleate seeds, operation duration and feed concentration, high quality drinkable water with a low salinity ∼0.144 g/L was produced in the ICFD process. At the same time, using the optimized hollow fiber module length and packing density in the DCMD process, ultra pure water with a low salinity of 0.062 g/L was attained at a condition of high energy efficiency (EE). Overall, by combining FD and MD processes and adopting the optimized operation parameters, the hybrid FD-MD system has been successfully demonstrated. A high total water recovery of 71.5% was achieved, and the water quality obtained met the standard for drinkable water. In addition, with results from specific energy calculation, it was proven that the hybrid process is an energy-saving process and utilization of LNG cold energy could greatly reduce the total energy consumption.
严重的全球水资源短缺和创纪录的高化石石油价格极大地激发了人们对新型脱盐技术的研究兴趣，这些技术可以由可再生能源或废能源驱动。在本研究中，开发并探索了一种由冷冻脱盐（FD）和膜蒸馏（MD）过程组成的混合脱盐工艺，试图利用液化天然气（LNG）再气化过程中释放的废冷能。该技术的概念通过间接接触冷冻脱盐（ICFD）和直接接触膜蒸馏（DCMD）配置来证明。通过优化 ICFD 操作参数，即使用成核种子、操作持续时间和进料浓度，可以在 ICFD 过程中生产出高质量的可饮用低盐度水，盐度约为 0.144 g/L。同时，在 DCMD 过程中使用优化的中空纤维模块长度和填充密度，可以在高能量效率（EE）的条件下获得超低盐度的超纯水，盐度为 0.062 g/L。总的来说，通过结合 FD 和 MD 工艺并采用优化的操作参数，成功地展示了混合 FD-MD 系统。实现了 71.5%的总水回收率，并且获得的水质符合饮用水标准。此外，通过特定能量计算的结果证明，该混合工艺是一种节能工艺，并且可以充分利用 LNG 冷能，从而大大降低总能耗。
