Reaction Plants

Calcium Hypochlorite by Sodium Way.

Aqueous suspension of milk lime is fed to the first chlorination reactor of type cooled jacket reactor with internal impeller. Temperature of reaction is kept constant by externally supplied coolant.Consumption of wet chlorine is controlled to achieve desired conversion rate of suspension. The reacted sludge is discharged from first reactor and dewatered in solid liquid separation to eliminate mother liquor rich in chlorides from concentrated suspension containing majority of Calcium Hypochlorite.  Suspension is than diluted in water and sodium hypochlorite originating from continuous conversion of concentrated caustic and chlorine to high strength sodium chlorite with low sodium chloride content.New suspension is led to the second chlorination stage reactor where the complete conversion of sludge to desired product take place. Process is again operated at low temperatures until desired conversion is reached. Due to low sodium addition high purity product can be achieved even from less pure feedstock materials.Filtered sludge is dried at low temperature end fed into dryer operated at low temperatures to avoid product decomposition. Filtrate rich in product is fed back into the first reaction to increase product recovery yield.Final product is obtained either as granulates or tablets.

Where it is installed/applied

Ca-Hypochlorite is the main active ingredient of commercial products called bleaching powder, chlorine powder, or chlorinated lime as algicide, bactericide, fungicide is employed as a disinfectant and deodorant in treating water. Is excellent oxidizing and bleaching agent.Its major advantage is high content of active chlorine in sold form, long shelf lifetime and long operating radius. Is used to disinfect waters, swimming pools or equipment. Important for this plant is availability of chlorine and high-quality calcium hydroxide (eventually CaO).

What 3V Tech offers:

  • Engineering and Procurement
  • Key Equipment Fabrication under Strict Quality Control
  • Complete Plant Assembly 
  • Automation
  • Orientation on Clients and aftersales support

Plant concept options:

  • Sodium Way uses caustic soda addition to reactor to convert majority of produced calcium chloride back into calcium hypochlorite, reducing amount of effluent while increasing conversion yield of Calcium Hypochlorite.Calcium Way uses caustic soda addition limited only to convert portion of calcium chlorite present in filtered suspension entering second rection, while majority of calcium chloride remains in filtrate and eventually can be used for produce dried calcium chloride. 
  • ZLD Evaporative Way: Effluent after dechlorination can be processed with evaporative crystallization (steam or mechanical vapour compression), where calcium chloride can be enriched to standard marketable grade (36%) or to solidified flakes (78%) or solid granules (94%). Sodium chloride can be recovered at very high technical purity.
  • ZLD Chemical Precipitation of Calcium: Relatively expensive chemicals are added to effluent to minimize calcium content in dechlorinated effluent, which is than recovered as depleted brine in upstream processes.
  • Low Sodium Chloride Content: Caustic soda addition into reacting calcium hypochlorite suspension can be performed in isolated rector and chlorination can be done in dedicated standalone reactor allowing substantial elimination of NaCl from production of calcium hypochlorite.

Main performance parameters

  • High purity of produced powder (up to 74%)
  • Low effluent production
  • ZLD concept
  • High overall efficiency

Main equipment description

Calcium Hypochlorite plant is composed of the following sections:

  1. Hydrated Lime preparation and dosing
  2. Chlorination Reaction in two stages
  3. Filtration in two stages
  4. Drying, Screening
  5. Weighting, Packing, Storing
  6. Dechlorination
  7. Effluent Recovery ZLD

    Main auxiliaries needed that we normally do not include

    • Utilities such as steam, cooling water, chilled water, natural gas, instrumentation air, storage tanks, civil works, local environmental permission, sewage system and sludge handling

    Added value of 3V Tech

    • Integrated know how for reactors producing hypochlorite, crystallizers to recover NaCl as by-product and concentrators to concentrate calcium chloride to grade preferred by client
    • .Own inhouse production of cladded jacketed reactors
    • Strong aftersales team, R&D support.
    • Completely preassembled plants
    • Reduced local efforts and delays on customer side

    Why 3V Tech offering should be chosen

    • Own Engineering & procurement
    • Own KnowhowOwn Fabrication
    • Own Assembly
    • Own Commissioning Team 

    Integration with other technologies

    • Calcium Hypochlorite is frequently integral part of chloralkali plant as ultimate shelf storage of produced chlorine
    • Depleted Brine Circuit to take back recovered NaCl, 
    • Caustic Soda Concentrator,
    • Downstream CaCl2 plant to take concentrate from effluent treatmentReferencesElecttrochimica Solfuri (Today Solvay)
    Reference:
    Electtrochimica Solfuri (Today Solvay)

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