Erco Industries Limited

Sterling Pulp Chemicals, Ltd.

Tenneco Canada Inc.

Sterling Canada, Inc.

Superior Plus Inc.

Gerald Cowley

Marek Lipsztajn

Richard Swindells

Zbigniew Twardowski

George Joseph Ranger

David Andrew Dean

Peter David Dick

Jerry J Kaczur

Maurice C Fredette

Edward J Bechberger

Darren Francis Lawless

Dana Gourley

Ty V Tran

Ron K Schaible

Mark Kostanecki

A chlorine dioxide generator comprises a water eductor surrounded by a variable volume plenum. The plenum casing is threaded onto the venturi body, permitting the plenum volume and area to be modified depending on the capacity required. Chlorine and sodium chlorite may be fed tangentially into a conical plenum and reacted therein to form chlorine dioxide, which is discharged into water passing through the eductor at the venturi throat.

Method for generating chlorine dioxide

Chlorine dioxide generator

Alkali metal chlorite, particularly sodium chlorite, is produced with a low carbonate level by combining a chlorine dioxide generating system operating at subatmospheric pressure with a chlorite formation reactor in which the chlorine dioxide reacts with hydrogen peroxide in the presence of aqueous alkali metal hydroxide, particularly sodium hydroxide.

High purity alkali metal chlorite and method of manufacture

A process for converting in a single pass an aqueous alkaline pH, alkali metal chlorite solution into an aqueous chlorine dioxide-containing solution that involves the combination of (1) using an electrochemical acidification cell to lower the pH value of the aqueous alkali metal chlorite feed before it enters the anode compartment of an electrochemical oxidation cell where the chlorite is converted to chlorine dioxide with (2) using an anolyte flow pattern where the anolyte passes through a porous, high surface area electrode. This process results in a substantially improved conversion efficiency per pass.

Electrolytic process for producing chlorine dioxide

Chlorine dioxide is generated by electrochemical oxidation of sodium chlorite in an anode compartment of a cation-exchange membrane-divided cell in the presence of significant quantities of sodium chlorate and is recovered in a suitable recipient medium by passing the chlorine dioxide through a hydrophobic microporous membrane. Water balance in a continuous operation is maintained by removing water from the anolyte by transporting the same partly across the hydrophobic microporous membrane in vapor form and partly across the cation-exchange membrane.

Chlorine dioxide generation for water treatment

Chlorine dioxide is produced by reaction of chlorate ions, usually provided by sodium chlorate, with a persulfate in an aqueous acid reaction medium containing sulfuric acid. By-product sodium sulfate, sulfuric acid feedstock or mixture may be electrolyzed to form the persulfate for the reaction.

Process for production of chlorine dioxide

A salt solution, particularly aqueous sodium chlorate, is acidified electrolytically at a higher current efficiency than has previously been the case by employing a plurality of multiple compartment cells, in which the effluent from intermediate compartments is passed through more anodic compartments.

Electrolytic production of acid

The formation of sodium sulfate by-product in sulfuric acid-based chlorine dioxide generating processes is decreased and preferably eliminated entirely, by effecting electrochemical treatment of sodium ion-containing feed materials for the generator to remove sodium ions and to add hydrogen ions. Sodium hydroxide may be produced as a by-product. The process is generally applicable to the electrochemical treatment of alkali metal chlorates, alkali metal sulfates and mixtures thereof to produce acidified solutions useful in providing chlorate ion-containing feeds to such chlorine dioxide generating processes or for other purposes.

Electrochemical processing of aqueous solutions

The formation of sodium sulfate by-product in sulfuric acid-based chlorine dioxide generating processes is decreased and preferably eliminated entirely, by effecting electrochemical treatment of sodium ion-containing feed materials for the generator to remove sodium ions and add hydrogen ions. Sodium hydroxide is produced as a by-product. The process is generally applicable to the electrochemical treatment of alkali metal chlorates, alkali metal sulfates and mixtures thereof to produce acidified solutions useful in providing chlorate ion-containing feeds to such chlorine dioxide generating processes.

Chloric acid is produced in an electrolytic-electrodialytic process in which chlorate ions from a sodium chlorate solution are transferred through an anion-exchange membrane to combine with electrolytically-produced hydrogen ions in a compartment of a cell, from which the resulting chloric acid is recovered. The sodium ions are transferred through a cation-exchange membrane to combine with electrolytically-produced hydroxyl ions in another compartment of the cell, from which the resulting sodium hydroxide is recovered.

Production of chloric acid

Chlorine dioxide for waste water treatment is formed by reaction of sodium chlorate, sodium chloride and sulphuric acid at high acidity while the reaction zone is subjected to subatmospheric pressure and spent reaction medium overflows from the reaction zone. The subatmospheric pressure preferably is applied using a water eductor to which the water to be treated is fed, so that direct contact between the produced gases and the water to be treated is effected.

Production of chlorine dioxide on a small scale

Chlorine dioxide solution for use in waste water treatment is produced in an automated small scale plant wherein sodium chlorate solution is reacted with sulphur dioxide at subatmospheric pressure by countercurrent flow in a reaction tower. Water ejectors are used to withdraw gaseous chlorine dioxide from the upper end of the tower and form therefrom chlorine dioxide solution and also to withdraw liquid effluent from the bottom of the tower for discharge. The plant is fully automated to form chlorine dioxide solution in response to inventory requirements. The chlorine dioxide-producing reaction is only permitted to operate if each of a plurality of sensed parameters is within predetermined ranges.

Small scale chlorine dioxide plant

The entrainment of reaction medium in the vapor phase and the entrainment of gaseous phase in liquid phase are decreased in a chlorine dioxide generator (12) producing a gaseous mixture of chlorine dioxide, chlorine and steam from a boiling reaction medium (14) and wherein generator liquor is recycled with make up chemicals. These results are achieved by generator modifications, which include tangential entry (30) of recycled liquor to the generator (12) in the vapor space (16) above the liquid level in the generator (12), and the provision of a baffle (34, 50) projecting inwardly from the generator wall in the vapor space (16) and arranged to be above the trajectory of the recycled liquor as it enters the generator (12). These modifications enable the generator volume to be decreased substantially, with consequentially decreased capital costs.

Washing apparatus for the washing of by-product salts from chlorine dioxide generating processes comprising a multi-stage decantation washer.

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Mississauga, Canada

Gerald Cowley