Process for producing chlorate and chlorate cell construction

An electrolysis plant for the production of sodium chlorate solution, comprising

• a plurality of electrolysis units,
• each of said electrolysis units comprising
• a reaction tank,
• first liquid inlet means for feeding sodium chloride solution to be electrolyzed to said tank,
• first liquid outlet means for removing sodium chlorate product solution from said tank, and
• a plurality of individual electrolysis cells, each cell having a plurality of anode and cathode electrodes located therein in interleaved manner to define upwardly-directed parallel electrolysis channels therebetween extending between a lower inlet of said cell communicating with the reaction tank through second liquid outlet means of said tank and an upper outlet of said cell communicating with the reaction tank through second liquid inlet means of said tank,
• said plurality of electrolysis cells being connected in electrical series with each other by flexible electrical connectors but otherwise not being physically connected to one another,
• feed conduit means connected in parallel to said first liquid inlet means of each of said reaction tanks,
• product conduit means connected in parallel to said first liquid outlet means of each of said reaction tanks, and
• brine make-up mixing tank means having first liquid inlet means connected to said product conduit means, second liquid inlet means connected to a source of fresh sodium chloride solution, third liquid inlet means connected to a source of hydrochloric acid, first liquid outlet means for removal of product sodium chlorate solution therefrom, and second liquid outlet means connected to said feed conduit means through heat exchanger means.

An electrolysis unit for the production of sodium chlorate by electrolysis of sodium chloride solution, comprising:

• a reaction tank,
• first liquid inlet means for feeding sodium chloride solution to be electrolyzed to said tank,
• first liquid outlet means for removing sodium chlorate product solution from said tank, and
• a plurality of individual electrolysis cells, each cell having a plurality of anode and cathode electrodes located therein in interleaved manner to define upwardly-directed parallel electrolysis channels therebetween extending between a lower inlet of said cell communicating with the reaction tank through second liquid outlet means of said tank and an upper outlet of said cell communicating with the reaction tank through second liquid inlet means of said tank,
• said plurality of electrolysis cells being connected in electrical series with each other by flexible electrical connectors but otherwise not being physically connected to one another.

A cell box for the electrolysis of sodium chloride solution to form sodium chlorate, comprising

• a cathode backing plate constructed of mild steel and constituting one side wall of said cell box,
• an anode backing plate constructed of titanium and located parallel to said cathode backing plate, said anode backing plate constituting a second side wall of said cell box,
• a plurality of parallel, thin cathode electrode sheets constructed of mild steel and welded in respective parallel grooves formed in said cathode backing plate, said plurality of cathode sheets extending from said cathode backing plate towards said anode backing plate, the member of said cathode sheets each side of said cathode backing plate constituting one of the other side walls of said cell box,
• a plurality of parallel, thin anode electrode sheets constructed of titanium and having an electro-conductive surface thereon and welded in respective parallel grooves formed in said anode backing plate, said plurality of anode sheets extending from said anode backing plate towards said cathode backing plate in interleaved relationship with said cathode sheets to define a plurality of electrolysis channels therebetween,
• frame means constructed of mild steel and surrounding the outer periphery of said side wall-forming members of said plurality of cathode sheets to enclose the same within said box, said frame means having portions welded to said cathode backing plate and other portions connected to said anode backing plate in electrically-insulating relationship therewith,
• inlet means constituting one end closure of said cell box constructed of mild steel and welded to yet other portions of said frame means and to said cathode backing plate, said inlet means being located at one end of and in uninterrupted flow relationship with said plurality of electrolysis channels, and
• outlet means constituting the other end closure of said cell box constructed of mild steel and welded to additional portions of said frame means and said cathode backing plate, said inlet means being located at the other end of and in uninterrupted flow relationship with said plurality of electrolysis channels.