Studies On Operating Performance Of Marine Desalination Unit With Positive-pressure Distillation

Marine desalination device is equipped to supply fresh water for ships engaged in operation or navigation. Distillation is one of the most widely used approaches to produce fresh water. Studies showed that operating parameter and structures affected relatively desalination performance. Experimental researches on distilled desalination device were carried out,relationship between desalination performance and influencing factors were analyzed,and the structures and operating parameters were optimized.Above all, different desalination approvals like distilling, flashing, and reverse osmosis were contrastingly studied, according to special demand of construction and fresh water salinity.This paper utilized the proposal combining reverse osmosis and distillation. And then, thermal calculating and construction design of evaporator, condenser, demister were conducted.Experimental facility of distilling device with positive pressure were designed and built, and the adequacy of simulation seawater with K2CO3 solution was demonstrated. From this, testes on thermal efficiency, fresh water product, product ratio, salinity were conducted, which found that initial design standards were achieved. Besides, experiments of different operating conditions of various vapor pressure, mass flow of raw seawater, seawater salinity were studied,and then the influences of these parameters on desalination performance were further analyzed.This paper has studied the flow field of demister and the two phase flow characteristic through the mathematic simulation, and calculated the separated efficiency of the first demister.And then, a new type demister was proposed, the internal flow field of the two kind of demister were contrastingly studied, which decided that the improved demister with baffles has better performance of removal efficiency about small scale water drops, and the demineralization of the device increase.Finally, the desalination device discharge polluted water consecutively, based on the known calculation and analysis of industrial boiler pollutant emission. The variations of feed-water salinity and vapor mass flow with blowdown ratio were studied. Furthermore,experimental researches on economy and demineralization of the desalination device with different conditions of blowdown ratio were conducted, and then, the blowdown ratio of the small scale device was designed as 15%.