25-08-2017, 09:32 PM
Calcutta Mother Dairy
1408012607-PROJECTONMOTHERDAIRY.doc (Size: 1 MB / Downloads: 25)
INTRODUCTION:
Calcutta Mother Dairy is a leading dairy industry in financial assistance of Govt. of West Bengal which is made available by Indian Dairy Cooperation(IDC),accredited byISO-9002 & certified by HACCP.It’s main motto is to help rural milk producers & supply the needs of urban milk consumers(Operation Flood).The commissioning of the Dairy started in July 1978 & first distribution started in July 1978. Initially ,the management of Mother Dairy was looked after by the National Dairy Development Board(NDDB). On 24th March 1982, the then Honourable Chief Minister Shri. Jyoti Basu dedicated Mother Dairy Calcutta to the rural milk producers & urban milk consumers of West Bengal.Under Operation Flood III 1997, the processing capacity of the plant was increased from 400,000 litres per day to 600,000 litres per day.
It has process about 400,000 litre of milk daily of which 85,000 litre are loose milk & 250,000 litre packed milk.
It has 226 number of IT booths & 202 number of MDbooths spread over four zones namely Central Calcutta(0 zone), North & East Calcutta including Salt Lake(1 zone),South & South Suburban Calcutta(2zone), Northsuburban including Nadia(3 zone), Howrah & Hooghly(4 zone).
IMPORTENT SECTION OF MOTHER DAIRY
The most important section of Mother Dairy are listed below
• Power Supply
• Refrigeration
• Boiler House
• Cooling Towers
• Milk Processing
• Packaging Section
• De-Mineralization
POWER SUPPLY:
Power is a very vital thing. Constant supply of power is always required in a Dairy plant so that the processes taking place can go on unhampered. For that initial electrical supply is provided from Chanditola or Raghunathpur to the substation present in Mother Dairy. This steps down 33Kv to 11Kv. This is sent to 5 transformers that further steps down the supply voltage from 11Kv to 440V. This 440V is then controlled from the Control Room so that it is properly sent to the place where electrical supply is required.
• Generator:
To provide uninterrupted power supply to all the sections Mother Dairy, Kolkata has 5 DG Sets in a Generator Room that can run in parallel to provide the power. Two of the DG Sets have a power rating of 380KVA while three other DG Sets have a rated power of 200KVA. All the five 3 phase generators can be run in parallel but to do so synchronisation of the generators is required. For that all the 5 generators should generate nearly same voltage, should run at approximately the same speed, should generate current/voltage of same frequency etc.
• Capacitor Bank:
Mother Dairy has a highly improved power factor rating of nearly 0.99. This is achieved with the help of a capacitor bank which consists of a total of 14 numbers of 3 phase low loss power capacitors.
REFRIGERATION SECTION:
The refrigeration section is one of the most vital sections of Mother Dairy just like the boiler house. There are two refrigeration plants at Mother Dairy, one set up by the Voltas Company and the other by Frick Company. The one made by Voltas is old and uses Freyon-12 as refrigerant and the other is made by Frick is new and more sophisticated and it uses Ammonia as refrigerant. Both the refrigeration plants supply chilled water from their respective IBT(Ice Bank Tank) to processing section. This chilled water is used in the pasteurization process where the milk is required to be cooled from near about 80oC to less than 4oC in a short time span. Thus if there is a break down in the refrigeration section the entire milk process can come to a standstill.
The ammonia plant made by Frick India Ltd. is much more sophisticated than the Freon-12 plant made by the Voltas. The ammonia plant consists of two squirrel cage Induction Motors of 200 KW rating. Each of them runs for 12 hours a day. The compressors attached to these motors are screw type compressors, made in USA. Its performance is governed by microprocessor. A digital panel display shows the required data including the inlet and outlet pressure of gas, temperature etc. One of the motors has an autotransformer type starter while the other has a soft starter type starter. Soft-starter is a thyristor controlled motor starting device is a very modern and sophisticated machine, and is not generally found in every industry. This plant being modern and sophisticated has an economiser installed and used. The economiser is basically a PHE(plate heat exchanger) here heat exchange between refrigerant at high temp. and pressure and that at low temp. and pressure takes place thus the refrigerant without any use of energy. This makes refrigeration more economical hence the name economiser.
Voltas Plant: It works on the principle of Refrigeration. The low temperature low pressure gas is converted to high temperature high pressure by a compressor. Then this high temperature high pressure gas is converted to liquid in the condenser which enters the receiver chamber. After leaving the receiver, the liquid enters the Evaporator coil where it gets converted to low temperature low pressure gas which again enters the Compressor to become high temperature high pressure gas. In Voltas plant actually Slip- Ring Motor starter are used. Freyon-12 is used as refrigerant.
Frick Plant
The compressor converts the low temperature low pressure gas to high temperature high pressure gas. This high temperature high pressure gas enters the Oil Separator from which it is fed to Vertical Condenser which is of Sale & Tube type. The gas gets liquefied after coming in contact with water in tube. The liquid enters the Receiver tank of 3,000 kg capacity. The liquid accumulated in the Receiver tank. From tank through pump the liquid enters the Ice bank tank. By opening the Solenoid Valve it enters the Accumulator. From the accumulator it is fed to Compressor which is of Screw type. Ammonia(NHз) is used as refrigerant.
BOILER HOUSE:
Mother Dairy has two horizontal multitubular fire tube boilers of capacity of 4 ton steam per hour. Both are identical boilers. There are three passes for the hot flue gases before they are passed on to the chimney. The fuel of the boiler is known as the furnace oil. The furnace oil is pumped by a electric motor at a pressure of about 15-16 bar. The fuel burns and the remaining unburnt fuel returns at approximately 8-9 bars. There are two electric motors that drives the feed pumps to pump water into the boiler. The boiler firing takes place at a fuel temperature about 95oC. Ignition of the fuel that is sprayed through the nozzle takes place by the spark or purge produced by two electrodes that has a very high voltage difference between them. The boiler automatically shuts itself down by switching off the oil pumps when the desired pressure is reached. But it has to be manually restarted once the pressure starts falling.
Although there are two boilers only one is run at a time while the other remains under maintenance. Boiler is required for supply of the steam which is used in the process of pasteurization in heating the milk to a temperature of 78oC.
Specification of Boiler:
Type: Horizontal, Package Type, Oil fired, Fire Tube, Three pass, Economical and Automatic Boiler.
Capacity: 4 ton/hour of steam generation.
Working steam pressure: 10.5 kg/cm2
Total heating surface area: 121 m2
Manufacturer: I.A.E.C
Oil inlet pressure: 15 kg/cm2
Oil exit pressure: 9 kg/cm2
Fuel: Furnace Oil
Viscosity: 0.8
Flash Point: 80oC
COOLING TOWERS:
Cooling towers are heat removal devices for industrial processes. They are defined as any open water recirculation device that uses fans or natural draft to draw or force air to contact and cool water by
evaporation. Cooling towers minimize the thermal pollution of natural water heat sinks and allow the reuse of circulating water. When one thinks of cooling towers, the large towers associated with nuclear power plants probably come to mind. These cooling towers are an extreme case in terms of size, but all function in the same way. These and other smaller towers are used widely in industrial applications.The use of evaporation is the primary advantage of cooling towers as a type of heat removal equipment. They are used to provide significantly lower water temperatures than those achievable with air-cooled or dry heat removal processes.
MILK PROCESSING
The most important section of any dairy is the Milk Processing section. The milk that is collected from different societies and milk unions is brought to the dairy in chilled conditions sealed in milk tankers. Milk processing is required to eliminate the dirts and harmful pathogens from milk, and also make the milk a homogeneous liquid containing all the important ingredients like fat, SNF(solid not fat) etc in right proportions as may be required.
The three basic steps of milk processing are:
1. Clarification
2. Homogenisation
3. Pasteurisation
There are 3 plants in Mother Dairy to process the raw milk. Each plant consists of a Clarifier,Homogeniser and a Pasteuriser.
CONCLUSION:
This Industrial Training at Mother Dairy Calcutta was of immense importance to us. We found ample of opportunity to apply our theoretical knowledge which we gained from our college. Several Practical Concepts which were not so clear to us became clear by over viewing it’s applications in industry under the guidance of associate staffs. Besides, all this we came across several mechanical & electrical devices, its concepts, working principle, construction, application & several other phenomena & terms related to it which would have not been possible in our college. Mother Dairy Calcutta really helped us to build a wide & vivid picture of modern industries.