TABLE OF CONTENTS

1. Product Description..3 2. Raw Material............3 3. Process Description..4 4. Reactor Design............7 5. Process Flow Diagram........8 6. Modifications....9 7. Economic Scenario...10 8. References.....13

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PRODUCT DESCRIPTION Calcium Hypochlorite also known as Bleaching powder is a yellowish-white powder easily soluble in water. The chlorine content of calcium hypochlorite varies from 35 40%. If temperature of lime kept between 30oC 40oC bleaching powder with available chlorine upto 40% is obtained. It is not hygroscopic, if kept under 40oC. It is mainly used as a bleaching agent and as a disinfectant. The major use of bleaching powder is in paper industry, textile industry and oil industry. It is also used in all chemical industry where bleaching is required.

RAW MATERIAL The two main raw materials required for the manufacture of bleaching powder are high-grade lime and chlorine. Chlorine is available as a by-product during the electrolysis of brine. When lime is processed with chlorine it has to be free from hydrogen to avoid explosions in the reaction chamber. The lime quality used is utmost importance. Generally lime which has a CaO content of around 95% that slakes readily to yield a large volume of slaked lime (over 3 times the volume of CaO used) is employed. It should contain less than 2% of carbonate, 0.5% of iron oxide and no cobalt or manganese. The lime after slaking should be stored for some time before use and its moisture content may be 4%. The raw materials required for the unit are as follows: Lime: 400 MT/Yr. Chlorine: 200 T/Yr.

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PROCESS DESCRIPTION STEPS: 1. The lime feeding and transporting process. 2. The chlorination, drying and cooling process. 3. Packing of the product. 4. Water regeneration system. The lime feeding and transporting process. Bucket elevators: with help of one inclined screw conveyer & one horizontal conveyer (moisture content of slaked lime 1-1.5%). From one storage hopper and one screw conveyer. Charge Hopper: Through a screw conveyer. Approximately 30-45 min. are needed to charge 4.5-4.8 MT. The charge hopper is provided with electromagnetic impact vibrator. The chlorination, drying and cooling process. Chlorination: This process consists of one specially designed, horizontally mounted, cylindrical, insulated, jacketed chlorination reactor. Reaction is batch type, reactor has scrapper assemblies (40 arms in four rows), attached motor has a capacity of 100hp with 900 rpm, which is reduced to 9 rpm for the reactor vessel, with the help of a reduction gear, a spur gear and pinion system. Before chlorination starts the reactor should be under complete vacuum. Slaked lime is fed by opening the slide gate consisting of a electromagnetic vibrator. Chlorine is fed from the longer sides of the reactor consisting of four inlets & is controlled by flow monitoring integrator. The vessel is provided with one temperature & one inlet pressure indicator. Generally a vacuum of 660-680 mm Hg is maintained. Chlorine should be fed to the reactor until the fall in vacuum is not more than 20 mm Hg.

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At Chlorine inlet, Chlorine is fed as follows: 15min @ 3MT/hr until 700kg of chlorine at 670-680mm Hg. 15min @ 2MT/hr until 1200kg of chlorine at 670-680mm Hg. 30min @ 0.8-1MT/hr until 1600kg of chlorine at 670-680mm Hg. 30min @ 0.8MT/hr until 2400kg of chlorine at 670-680mm Hg. The chlorination reaction requires about 2.5-3hrs for completion. The inside chlorine pressure is checked by pressure indicators and any loss of chlorine is identified by change of color of the absorbing 10-12% caustic solution circulating through the vacuum condenser from green to dark red.

Drying: Once the reaction is completed, steam at 1-1.5kg/m is circulated from top to bottom through four steam inlet pipes for drying of the final product after stripping off all the water in the jacket. This process needs 2-2.5hrs for completion at 78 to 80C. Condensed steam is removed from the jacket through common header for cooling water inlet. Cooling: After drying the product is cooled by circulating cooling water through the jacket for 1.5-2hrs to reduce the inlet temperature to 35-40C. Altogether, there are four steam inlet and four cooling water inlet pipes are connected respectively at the top and bottom of the jacket.

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Packing of the product. The finished product is discharged through bottle seal opening of the reactor into the chain conveyer to flow freely by gravity. The chain conveyer transfers the SBP to a SBP hopper. It is next sent to a pulverizer unit and then to a cyclone separator to separate desired sized product particles. Below the pulverizer is one motor of capacity 50hp connected for easy separation and transportation of particulate solids. The bleaching powder is packed into double inner lined HDPE bags having capacity of 25 kg each. Also there is a facility to collect the dust in a dust collector from which the dust is collected and sent back to the packing unit. Water regeneration system. The vapors along with the unabsorbed chlorine from the reactor are condensed in the barometric condenser. Firstly, the gases pass through vacuum pipe through pipe by water ring vacuum pump and is absorbed in 10-12% caustic solution. It is disposed or treated to purify the chlorinated water. Some uses of Calcium Hypochlorite 1. For water purification. 2. In carpet industry for bleaching and finishing. 3. In paper and pulp industry as bleaching agent. 4. In leather industry as disinfectant material & also for making cotton used for medical purpose. 5. For sewage disposal, mosquito and epidemics control and general hygiene.

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REACTOR DESIGN The process of manufacture of bleaching powder is as per HASEN CLEVER PROCESS of manufacturing Bleaching Powder. In this process there are cast iron cylinders operating in series with hydrated lime and chlorine being fed counter current to each other. The cylinders are provided with rotating blades and are arranged horizontally one above the other the rotating blades act both as mixed and conveyors of the inside mass. Hydrated lime is charged at one end of the top most cylinder while chlorine is introduced at the other end of bottom most cylinder with the rotation of the blades there is an intimate mixing of chlorine and lime with simultaneous movement of slaked lime counter current to chlorine gas. The chlorinated lime is discharged from the bottom cylinder and the un-reacted chlorine is recovered from the top cylinder and recycled along with the fresh chlorine. The bleaching powder discharged is stored in cast iron drums and wood barrels. To increase the storage life it is mixed with quick lime to yield tropical bleach containing 25% of available chlorine. Reactions Involved:

Ca(OH )2 +Cl2 =Ca(OCl)Cl +H2O2Ca(OH )2 + 2Cl2 =Ca(ClO)2 +CaCl2 + 2H2O

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PROCESS FLOW DIAGRAM (PFD) of a Calcium Hypochlorite plant

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MODIFICATIONS The reactor design of the process to manufacture Calcium Hypochlorite can be modified to get a higher yield and various aspects. The reactor is a vertical tower made of cast iron. The tower is provided with a hopper at the top, two inlets near the base (one for chlorine and other for hot air) and an exit for waste gases near the top. The tower is fitted with eight shelves at different heights each equipped with rotating rakes. The slaked lime is introduced through the hopper. The contacting of chlorine gas is achieved in a cross current flow mechanism. Calcium Hypochlorite is then collected in a barrel at the base. This process is also known as Bachmanns Process.

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ECONOMIC SCENARIO* Plant Capacity: The production basis for a typical tiny unit would be as under: Working hours/day: 8 (1 shift) Working days in a year: 300 Annual Production capacity: 300 MT bleaching powder. The unit has been assumed to operate at 70%, 80% and 90% of its installed capacity in the first, second and third year and onwards of its operation. Infrastructure: The basic infrastructure required is: Land: 3,000 sq.ft. Building: 1,500 sq.ft. Power: 20 KW Water: 5,000 ltr/day. Manpower: 11 Nos. (Administrative (4), Factory Staff (7)) Total Capital Requirement: The total capital requirement including fixed capital and working capital is estimated at Rs 21 lakhs. Of this, the project cost comprising fixed capital and margin money on working capital is Rs 18 lakhs.

*Based on assumptions to set up a plant.

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Operating Expenses: The annual operating expenses are estimated at Rs 21.50 lakhs (70% capacity utilization) as given below: (Rs in lakhs) 1. Raw materials 12.50 2. Utilities 0.55 3. Wages & Salaries 4.80 4. Overheads 0.40 5. Selling expenses @ 2.5% on annual sales 0.70 6. Interest on term loan (13.50%) 1.60 7. Interest on Bank Finance for Working Capital (12.75) 0.40 8. Depreciation @10% 0.65 TOTAL 21.50

Sales Realization: The basis on which average ex-factory sales realization from the sale of bleaching powder at 100% capacity utilization is as follows:

Based on this the annual sales realization is estimated to be Rs 36.00 lakhs and at 70% capacity utilization the same is Rs 25 lakhs. Profitability: Based on the sales realization and the operating expenses, the profit would be Rs 3.5 lakhs per year (70% capacity utilization). This works out to a return on investment of 26%.

Items Qty. Unit Sales Price (Rs) Annual Sales Price (Rs) Bleaching Powder 300 MT 12,000/MT 36,00,000

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REFERNCES 1. "Chlorine Oxides and Chlorine Oxygen Acids". Ullmans Encyclopedia of Industrial Chemistry. Wiley-VCH. 2. Gerald F. Connell. "KEY OPERATING STRATEGIES FOR CHLORINE DISINFECTION OPERATING SYSTEMS". 3. Chemical Products Synopsis: Calcium Hypochlorite (Technical report). 4. Practical Organic Chemistry for Advanced Students. New york: Macmillan 5. Durgapur Chemicals Ltd.- plant related reports. 6. W.L Smith, Inorganic bleaches, Production of Hypochlorite in Handbook of Detergents.