Severn Trent Services has significantly advanced on-site hypochlorite generation technology with the introduction of the patented (Patent No. US 6,805,787) split-flow design and process; as well as an enhanced proprietary electrode coating that provides greater efficiency. As regulations governing chlorate/chlorite become a matter of concern, the ability to actively manage disinfection byproduct concentration to less than 2% of the total disinfection production will prove to be a tremendous benefit to users.
The patented ClorTec® Split Flow arrangement provides 33% higher hypochlorite production with lower energy and salt usage. The split flow cell, with enhanced electrode coating:
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Reduces salt consumption from 3.5 to 3 lbs/lb of chlorine (3.5 to 3 kg/kg of chlorine) – operational cost reduction of 14% in salt consumption
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Reduces energy consumption from 2.5 kWh to 2.0 kWh/ lb of chlorine (5.5 to 4.4 kWh /kg of chlorine)– operational cost reduction of 20% in power
The operating cost reductions over the life of the equipment can amount to hundreds of thousands of dollars.
The ClorTec electrolytic cell consists of numerous titanium plates divided into arrays or cell packs consisting of an equal number of anodic and cathodic plates. The cell packs are configured electrically in parallel, while the overall cell is configured electrically in series.
The cell is fed DC power from a rectifier and electrolyzes the diluted brine into a sodium hypochlorite solution. In simple terms, chlorine is evolved at the anode surface, while hydrogen and hydroxide is evolved at the cathode surface. The secondary reaction of chlorine, sodium and the hydroxyl ion nets sodium hypochlorite (chlorine bleach) at a 0.8% solution. As a reference, bottled household bleach is typically delivered at a 5% to 6% solution. The process can be described as follows:
NaCl + H2O + 2e = NaOCl + H2
or
Salt + Water + Electrical Energy = Sodium Hypochlorite + Hydrogen
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The clear cylindrical cell allows full visibility and easy access to the electrode array. Cells can be removed as a single unit, eliminating the time and labor spent disassembling sandwich-type cell structures and handling electrodes individually.