1. CDB Engineering S.P.A. Experience -SODIUM HYPOCLORITE PLANT PRESENTATION

2. BackgroundSodium Hypochlorite Generation units are currentlyinstalled in several applications to definitely obtain aSafe and economical disinfection / antifouling methodfor water.Sodium Hypochlorite water solution offer a powerfulbiocide and disinfecting agent in several applicationsand provides an efficient equipments protection againstmacro and micro organic fouling growth. 3. In situ biocide generation avoid the undesirable sideeffects of commercial hypochlorite, such us:- transportation safety hazard- hard deposit alkalinity build up- handling and storage of gas chlorine.Sodium Hypochlorite production plants eliminates theheavy costs associated to the purchasing of commercialbiocide products and the dependency upon outsideSuppliers. 4. ApplicationsOnsite and offsite Sodium Hypochlorite generator units aremainly employed and installed for : Off shore platforms Large desalination plants Power stations Refrigeration plants Petro-chemical complex for the associated utilities watertreatments Sea water intakes Generally where a big mass of water need to be disinfected beforefinal using 5. Technology resultsBy electrolysis technologies of salty water itis possible to obtain a reliable, lowmaintenance, safety and CAPEX / OPEXconvenient units in lieu of the unsafe andobsolete gas chlorine dosing 6. Range of suppliesCDB Generation units can be provided in awide range of production capacity:- From 1 to 5 kg/h active Cl2 for off shoresmall applications (single skidded units)- Up to 100 / 200 kg/h active Cl2 for verylarge industrial complexes or power stations(composite skids packages) 7. Unit description1/2Equipments and materials can bedesigned tailored to the specific needs ofthe customer as well as designed inaccordance to the principal applicablecodes and norms such asASME, ANSI, BS, IEC. 8. Unit description2/2To minimise the customer activities at site and to limitthe erection time , units are delivered in completepreassembled skidded parts, mainly (see flow diagram): booster station ( if required) strainers electrolysers Dosing / shock pumps air blowers HCl cleaning facilitiesdegassing tank, transformer rectifiers, LCP arenormally provided loose for large production units 9. Principle Flow Diagram 10. Materials:Long electrodes warranty periods ispossible thanks to the strong resistantused material (ASTM B265) for electrodesand to the special stable coating for anodesParts subjected to corrosion, because ofaggressive raw water and Hypochloritesolution, arebased on FRV and PVC 11. Supply Warranty: system free from defects in workmanshipand materials for a period of 12 monthsfrom start up and 18 months from shipment generator cells for 5 years 12. Engineering and management services Units will be delivered complete of operation and maintenancemanuals as well as of the equipments dimensional drawings. During the design phase it will be produced the usual set ofdocumentation, according to the specific customer needs, and for hisdesign and review ( general arrangement, BL positions, civil worksand loads, ITP, electrical loads etc) After delivery, according to the customer request, CDB can send tosite skilled specialized personnel to supervise the erection and start upactivities and for the training of Owners operation personnel 13. Process description 1/3Seawater (or brine water) provides the feedstock for theelectrolytic cells.Though the seawater has been passed throughdrum screens with a mesh size before entering theSW pumps, it shall be passed through automatic, self-cleaning fine mesh strainers to remove any debrisremaining before being allowed to enter the electrolyticcells. Sodium hypochlorite solution output from each ofthe cell assemblies is to be channelled to the degasifier forhydrogen gas to be removed. 14. Process description 2/3The generation of Sodium hypochlorite (NaClO) solutionfrom raw sea water (or brine) is performed by an electro-chemical process doing partial electrolysis of NaClcontained in sea water once it flow through anodic and cathodicelectrodes. Electrodes are energized by DC current make available byan controlled diodes rectifier.Raw water, filtered by mesh filters, is fed the NaClO generators. Thegenerator cells are usually connected electrically and hydraulically inseries such us that sea water flow form the first electrolyser and thento the others before exiting the sodium hypochlorite degassing tank. 15. Process description3/3The hydrogen gas disengages from the liquid phase in theupper part of the tank and is diluted with air generatedby dedicated fans to keep the hydrogen concentration wellunder the explosion level .NaClO produced solution is stable enough withoutsubstantial loss in the storage / degassing tank during thetime between the shock treatments.Finally sodium hypochlorite is pumped by centrifugalpump up to the injector at the dosing points for thecontinuous and shock treatments. 16. Involved electrochemical reactions :Anode producing free chlorine2 (Na+ Cl-) 2 Na+ + Cl2 + 2 e-Cathode producing Hydrogen:2 H2O + 2 e- 2 OH- + H2Bulk reaction producing Sodium Hypochloriteiones OH- migrate from cathode and react closed to the anode as:2 NaOH + Cl2NaClO + NaCl + H2O.All the above gives the overall reaction in water :NaCl + H2O NaClO + H2 .Cations present in the raw water (mainly Magnesium and Calcium) form Carbonatesand Hydroxides coming out as suspended solid which are carried out during raw waterflowing. Nevertheless periodically (usually twice per year) deposits are removed byelectrodes by diluted acid cleaning. 17. Suplier references: CDB Engineering S.p.a. : Via L. Maggi snc, Loc. Zorlesco - 26841Casalpusterlengo (LO) Italy Tel. +39 0377 912268 / 65, Fax. +39 0377 910668 e.mail cdb@cdbengineering.com Website: www.cdbengineering.com