Study On Clean Production Of Electrolytic Ionic Memberance Caustic Soda

Electrolysis process is the core technology for ion-exchange membrane caustic soda. The original ion-exchange membrane electrolysis technology of caustic soda was introduced from Japan. With the development of technology, an advanced ion-exchange membrane caustic soda technique sufficing the production is urgent recently in China. At present, the ion-exchange membrane caustic soda can actualize cleaning production as to remain competitive depending on raw material consumption and emission reduction. The power consumption also has to be taken into account.Taking chloralkali plant electrolytic device of huatai as an example, this project studied the existing material consumptions of electrolytic device based on the process principle of ionic membrane electrolyzer. Three main factors affecting clean production for the device have been proposed:the excess sulfate ion in salt water, the poor quality of secondary refined brine and the high cell voltage with the high power consumption. This program also put forward solutions to the difficulties in current clean production:(1)Designing membrane sulfate elimination method. Sulfate ions entrapped by nanofiltration membrane was verified. The key factors of designing the refrigeration unit were investigated. The equipment parameters were defined by whole plant material balance computation. The actual operation of membrane was studied and expected results were achieved.(2)The principle of secondary brine refining process was investigated and double-improved the process of resin tower. Focus on secondary improvement of the process design and calculation, the calcium and magnesium of secondary brine refining was set between 0.001?0.004 mg/1, which showed distinct advantages in wastewater emission comparing with other methods.(3)The influence of cell structure on power consumption mainly resides on the ionic membrane voltage drop and spacing. The slot voltage remarkably dropped 160 mv through cell membrane pole pitch modification in a monolithic electrolytic cell and a whole electric tank experiment. With the completion of the membrane polar distance project, we also improved the corresponding process control to effectively reduce the cell voltage, to increase the current efficiency, and to improve the quality of the caustic soda products.