Advanced control strategies for chlorine dioxide generating processes
AssigneeSuperior Plus Inc.
InventorsChunmin Pu, John Brian Birks, James Johannes Hopmans
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Abstract
Chlorine dioxide generating processes of the single vessel type which produce chlorine dioxide of high purity are monitored and controlled by a computer using Advanced Control Strategies for steady, stable operation with optimum chemical usage on the basis of a desired chlorine dioxide production rate as the sole input from an operator to the computer program effecting the computer control.
Claims32
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 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.
A continuous process for the generation of chlorine dioxide at a predetermined production rate, which comprises:
- reducing sodium chlorate in an aqueous reaction medium in a reaction zone using methanol 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 absorption zone to provide a product aqueous solution of chlorine dioxide,
- removing a slurry of spent reaction medium and by-product crystalline sodium sulfate from the reaction zone,
- separating the crystalline sodium sulfate as a by-product from spent reaction medium,
- adding make-up quantities of sodium chlorate, methanol 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 to produce chlorine dioxide from the reactants with optimum chemical usage on the basis of a desired chlorine dioxide production rate as the sole input to a computer program effecting such computer control.
Dependencies are inferred from the claim text.