Patent ID: 6972121

Claim:
A continuous process for the generation of chlorine dioxide at a target production rate, which comprises: reducing chlorate ions in an aqueous acid reaction medium in a reaction zone using a reducing agent selected from the group consisting of methanol and hydrogen peroxide and sulfuric acid at the boiling point of the reaction medium under a subatmospheric pressure, removing a gaseous admixture comprising water vapour and chlorine dioxide from the reaction medium, absorbing said gaseous admixture in chilled water in an absorption zone to provide a product aqueous solution of chlorine dioxide, removing a slurry of spent reaction medium and by-product crystalline sulfate from the reaction zone, separating the crystalline sulfate as a by-product from spent reaction medium, adding make-up quantities of chlorate ions, reducing agent and sulfuric acid to the spent reaction medium to form a make-up feed, evaporating water inputted to the process from all sources using steam fed to a reboiler, recycling the make-up feed to the reaction zone, and computer controlling said process on the basis of a desired target chlorine dioxide production rate as the sole input from an operator to a computer program effecting such computer control.