Sodium hydrosulfite electrolytic cell process control system

Claim 1

A centralized controller based process control system for the operation of an electrolytic membrane cell to continuously produce an aqueous product solution in the cell which has a cathode compartment, an anode compartment, a cation exchange membrane separating the anode compartment and the cathode compartment, a porous cathode, and a separator intermediate the anode and the membrane, comprising: (a) a core process control program to control the feed of raw materials to the catholyte in the cathode compartment and to the anolyte in the anode compartment and to maintain the feed within tolerances of desired set points for the rate of feed by initiating self-correcting instructions to actuators controlling the rate of feed of the raw materials, the core process control program also monitoring the product pH to control the product within tolerance of a desired set point and sensing alarm conditions when the rate of feed of the raw materials or the product pH is out-of-tolerance; (b) an alarm monitoring program to receive sensings of alarm conditions of out-of-tolerance conditions from the core process control program, to analyze the sensings and data on the operation of the cell, and to issue instructions and commands in response thereto; (c) at least one sequencer program that is put into operation by a command from the alarm monitoring program and which sends commands to the core process control program to initiate a cell shutdown procedure when any predetermined one of the alarm conditions sensed by the core process control program persists beyond a predetermined period of time; and (d) a timer program that is initiated by the sequencer program to initiate timing an out-of-tolerance condition for the predetermined period of time and when the predetermined period of time elapses and the out-of-tolerance condition perists, activating the at least one sequencer program to initiate the cell shutdown procedure.