Design Of Electrolytic Process Control System For Ion Film Blast Alkali System

Ion membrane caustic soda is produced by using solid salt as raw material.Ion membrane electrolysis is used to produce caustic soda,chlorine gas and hydrogen gas.Electrolytic process is the core of Ionic membrane caustic soda production.The production index of electrolytic process is very strict.The control requirement is the most complicated part of the whole caustic soda production.Based on the control system of 4 00000 tonnes/year Ionic membrane caustic soda?phase 2?project,this paper studies and designs the control system for the production process and actual control requirements of electrolytic process.The automatic control algorithm,control strategy,system integration and design of electrolytic process were studied by using HOLLiAS MACDCS control system in Hangzhou and Belgium.Based on a thorough understanding of the production process of the electrolytic process of4 00000 tonnes/year membrane caustic soda?phase II?project,this paper studies and designs the electrolytic process control system from the following aspects:First,the program control scheme of resin tower.The salt water entering the electrolytic cell must first pass through the resin tower to make its Ca²⁺,Mg²⁺less than the required value.The operating procedure of the resin tower is very complicated.It is operated by three cycles,two of which operate online,one is regenerated off-line,and automatically switch every 24hours.After analyzing the requirements of the resin tower control process,precise automatic switching of operation,regeneration,and washing of the resin tower was designed,and automatic adjustment control of the acid-base addition amount was designed.Different operation selection methods and alarm interlocks under abnormal conditions were designed to make The operation of the resin tower realizes complete automatic safety control,reduces the strength of manual operation,and improves the precision of the process index of refined brine.Second,the main process parameters control method design.The control points of salt flow control,acid flow control and chlorine pressure differential control have a great influence on the process index of electrolytic cell,directly affect the safe and stable operation of electrolytic cell and the service life of Ionic membrane.The automatic control of flow rate and pressure in electrolytic production were realized.Third,the electrolytic cell safety interlock control.Ion membrane caustic soda system mainly uses raw salt as raw material and ion membrane electrolysis to produce flammable,explosive and corrosive products such as H2,Cl2 and NaOH.In the production process,the process is more complex,need to control a lot of risk factors,slightly careless may cause safety accidents.Therefore,it is necessary to set up a set of security interlock control program for the electrolytic cell,to realize automatic emergency handling in abnormal situation,to ensure the safety of operators and electrolytic cell.The security interlock control program includes the single cell interlock and the common interlock in the electrolytic cell.Electrolytic process design and implementation of the control system to reduce the electrolytic process operator labor intensity,improve the process control precision of the electrolytic production,guarantee the production of caustic soda products and qualified rate,and can overcome the manual operation and automatic control of control and observation error,enhance the safety performance,to achieve a little according to the safe and stable operation of electrolysis production of ionic membrane.