ES351705A1 - Manufacture of chlorine and caustic alkali in diaphragm cells - Google Patents

Abstract

A chlor-alkali cell incorporating a percolating asbestos diaphragm is operated under conditions of varying electrical load by rapidly making such change in the rate of flow of electrolyte through the diaphragm by altering the gas pressure on at least one of the anode compartment and the cathode compartment of the cell each time the current density across the diaphragm is changed, so that the rate of electrolyte flow through the diaphragm is always approximately proportional to the current density. In the form shown comprising a cell 1, diaphragm 2, anode 5, foraminous cathode 6, electrolyte inlet 7, chlorine outlet 9, caustic alkali outlet 11 and hydrogen outlet 10, the rate of flow of electrolyte through the diaphragm is changed as required by altering the gas pressure on the cathode compartment by means of a pressure-control valve 18 in the hydrogen outlet pipe. Said gas pressure may be varied e.g. by operation of valve 18 by means of a servo-system, such that the pressure differential across the diaphragm is maintained proportional to the current density, or such that the alkalinity of the caustic alkali leaving the cell remains constant, or the actual flow of electrolyte may be measured by metering the caustic liquor leaving the cell. The pressure in the cathode compartment may be measured by the difference in levels in the tubes 12 of the caustic liquor outlet system. Said tubes may be flexible so that the level of the catholyte may be varied to allow for ageing of the diaphragm.