Techno-Economic Evaluation of Cyclopentane Hydrate-Based Desalination with Liquefied Natural Gas Cold Energy Utilization

The clathrate hydrate-based desalination process coupled with liquefied natural gas (LNG) cold energy (ColdEn-HyDesal) strengthens energy-water nexus by integrating two energy-intensive processes into one. A typical HyDesal process that uses a gas as a hydrate former requires elevated pressure for hydrate formation that results in a higher specific energy consumption (SEC). The efficiency of the process improves by adopting hydrate formers with a milder hydrate formation condition, such as cyclopentane (CP). In this study, the ColdEn-HyDesal process using CP as the hydrate former is modeled and investigated. The results show that the SEC of the ColdEn-HyDesal process using CP is 0.35 kWh m(-3). The effects of water recovery rate, hydrate formation temperature and heating seawater pressure on SEC, volumetric flow rate, exergy efficiency, and fixed capital investment (FCI) are investigated. The water recovery rate is found to have a significant effect on the SEC, volumetric flow rate, exergy efficiency, and FCI, whereas, hydrate formation temperature has a pronounced impact on FCI, while small impacts on SEC, volumetric flow rate, and exergy efficiency. With a lower operating pressure and the elimination of compressor for recycle, the ColdEn-HyDesal process using CP as the hydrate former further reduces SEC by 58% when compared with gas such as propane as a hydrate-forming guest.