Development Of Engineering Technology Of Aqueous Sodium Chloride Preparation For Ten-thousand-tonnage Concentrated Seawater By Ion Exchange Membrane Process

The shortage of freshwater resources has promoted the development of desalination technology.However,a large amount of concentrated seawater produced by the desalination plants is directly discharged into the sea,which results in the waste of resources and the destruction of marine ecological environment.Therefore,it is extremely urgent to utilize concentrated seawater resources.On the basis of previous work,this study carries out the technological development of aqueous sodium chloride preparation engineering by ion-exchange membrane utilizing concentrated seawater to provide technical support for engineering construction of aqueous sodium chloride preparation from concentrated seawater.In order to explore the effects of the concentration differences between concentrated and desalted chambers on the concentration process,the effects of the initial concentrations of Na Cl in the desalted chambers,different concentration in concentrated and desalted chambers,and voltages on ions migration and water migration were respectively investigated.The results show that increasing the voltages and the initial concentrations of Na Cl in the desalted chambers,and reducing the concentration differences between concentrated and desalted chambers can accelerate ion migration rate and increase water migration.In the pilot tests of aqueous sodium chloride preparation from seawater desalination brine by ion-exchange membrane,the influences of voltages,concentration differences on salt outputs and energy consumptions were investigated.The results show that when the voltage is 35 V,the concentration of aqueous sodium chloride is 180 g/L,the recovery rate is 40%,the salt output is 29.7 kg/d,the DC energy consumption is 232.62 k W?h/t(Based on100%Na Cl,the same below),and the AC energy consumption is 397.81 k W?h/t.Based on above,the engineering studies on application of concentrated seawater with 300m~3/day were carried out,in which the influences of voltages and feeding rates on concentrations of aqueous sodium chloride,recovery rates,salt outputs and energy consumptions were investigated.The results show that when the voltage is 190V and feeding rate is 12 m~3/h,recovery rate of Na Cl is 42.7%,the concentration of aqueous sodium chloride is up to 180g/L,and the energy consumption is less than 200 k W?h/t.On the basis of the engineering studies,the engineering design of aqueous sodium chloride preparation from concentrated seawater with 100,000 tons/y was carried out by ion-exchange membrane.And the engineer project of aqueous sodium chloride factory preparation by ion-exchange membrane was put forward.