Single-stage freezing desalination study with slurry pressing piston and enhanced vacuum for brine extraction

Abstract

Freezing desalination has gained interest due to its potential to reduce energy use. The freezing process faces challenges that limit its wide use. Washing product ice causes a large mass loss. Most freezing processes involve crushing to generate the appropriate ice form, limiting large-scale production. A vacuum pump and pressing piston are experimentally utilized to collect brine during melting to avoid washing and crushing ice. Five brine separation processes are needed to produce 2 %-salinity water. The studies used salinity-varying feed water. From the results, utilizing a vacuum pump and piston for brine separation during melting and a relatively small number of separation steps has considerably enhanced the quality of the produced water without causing significant mass loss. It is observed that 1000 ml of 15,000 ppm feed water produces freshwater with salinity and volume equal to 114 ppm and 185 ml, respectively. Results indicate that when the COP varied from 4 to 6, the system performance ratio increased from 31.74 to 47.62 and 7.94 to 11.90, with a recovery ratio equal to 0.9 and 0.6, respectively. Compared to previously described freeze desalination, MSF, MED, and MD desalination systems, the specific energy consumption increases by 71.5 %, 66.4 %, 54.5 %, and 36.1 %.