Gokul Final Report

KIT‟s COLLEGE OF ENGINEERING

1

An

INDUSTRIAL TRAINING REPORT

AT

“KOLHAPUR ZILLA SAHAKARI DUDH UTPADAK SANGH LTD.”

“GOKUL”

SUBMITTED TO THE

SHIVAJI UNIVERSITY, KOLHAPUR

IN PARTIAL FULLFILLMENT OF THE REQUIREMENT FOR THE

DEGREE OF

BACHELOR OF ENGINEERING (MECHANICAL ENGINEERING)

SUBMITTED BY,

Mr. Pise Saiprasad Rajendra

Mr. Saygaonkar Swanand Suhas

Mr. Kadam Rohan Shrikant

Mr. Wagavekar Vikas Rajendra

Mr. Sutar Sandip Dilip

Mr. Sutar Tejesh Balasaheb

Mr. Patil Suraj Ramchandra

Mr. Patil Pandurang Niwas

Mr. Manole Pranav Ashok

Mr. Janwadkar Giridhar Vyankatesh

UNDER THE GUIDANCE OF

Prof. S. M. Pise

Prof. P. B. Mutalik

DEPRTMENT OF MECHANICAL ENGINEERING

K.I.T's COLLEGE OF ENGINEERING,

KOLHAPUR


2

INDEX

Sr.No.

Title

Page No.

1

Introduction

03

2

Overall preview

07

3

RMRD

09

4

Boiler department

11

5

Refrigeration Department

15

6

Pasteurization department

21

7

E.T.P department

24

8

Case study

27

9

References

33


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INTRODUCTION

Kolhapur Zilla Sahakari Dudh Utpadak Sangh Ltd. well known with its

popular brand „Gokul‟ is a Cooperative Dairy Project established on 16 March 1963. Since then,

Gokul achieved many land marks in Milk Procurement, Extension, Animal Health, Breeding,

Milk Processing, Product making and Marketing. At present Gokul has modern 7 Lakh

Litres/day capacity dairy plant with 4 owned and 1 hired chilling centers having 4.25 Lakh

Liters/day milk handling capacity with modern Packing Unit at Navi Mumbai.

For milk production enhancement, in milk shed they have presently 41 Mobile

veterinary routes , 430 Cluster and 17 static A. I. Centers, Along with this new 300 MT/day

capacity Cattle Feed Plant with popular „Mahalaxmi‟ brand is operational at Kagal-

Hatkanangale Five Star MIDC. The old cattle feed plant with 200 MT/day capacity plant is

simultaneously operational.

SPECIAL FEATURES:

Quality Management and Food Safety System is under implementation at Gokul.

Union continues renewal of Export Inspection License in July 12, 2012 for Product

Exports.

Undertaken DPM Study from 1990 for Plant improvement, Refrigeration, Plant Losses

etc. with help of NDDB/FAO. First plant to start Quality Assurance Program in country

in 1992

14 times winner of National Productivity Awards from 1988/89 to 2006/07.

Gokul bags PATENT for its innovation Milk Replacer.

Gokul pay back 76 to 82% for every sale rupee generated in form of price and services to

the Milk Producer.

Turnover for financial year 2012-2013: Rs. 1205 Crores.

Plant commissioned in 1986 with 2 Lac process capacities. Average growth rate in last 24

years is 10 to 11%.

Highest handling - 11 Lakh Litre/day. Average handling in Dairy Plant - 7 Lakh Ltr. /day.


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ABOUT GOKUL:

The Kolhapur District Co-operative Milk producers Union Ltd. Kolhapur was

established on 16 March 1963 under the Co-operative Act. It made a moderate beginning by

collecting 500 liters of Milk per day from 22 societies. Most success stories have a humble

beginning & so has been with Kolhapur Zilla Sahakari Dudh Utpadak Sangh Ltd.

On 16th

March 1963 a spark stormed a fire to help the White Revolution revolt

heavily, when on this day came into being the “Kolhapur Zilla Sahakari Dudh Utpadak Sangh

Ltd” with the introduction of its popular brand of Gokul Milk & its wide range of Dairy

products into the market.


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GOKUL‟S PRESENT SETUP:

A) Milk Reception Capacity 3.2 Lakh Ltrs/Day (Raw)

3.8 Lakh Ltrs/Day Lakh(Chilled)

B) Milk Process capacity 7.0 Lakh Ltrs/Day

(Union handled 1 Million Ltr. in Flush 2001/02)

C) Powder Manufacturing 40 MT/Day

D) DesiLoni ( Desi Butter ) Manufacturing

C. B. M. M. 32 MT/Day

Top Churn 8 MT/Day

E) Ghee Manufacturing 6 MT/Day

F) Packaging Lines :

Milk Packaging 1 Lakh Ltr/day

Powder Packing-Nichrome (Pouch) 10 MT/day

Rollatainer Machine (Cartoons) 10 MT/day

Ghee Packaging (Pouch) 4.5 MT/Day

Table Butter Packaging

In 500 gm 3 MT/day

In 100 gm. 1 MT/day

Total 4 MT/day

G) Storage Capacity :

Milk (Packed Milk) 1 Lakh Ltr

DesiLoni ( Desi Butter ) 800 MT

Powder 1400 MT

Ghee 20 MT to 30 MT

Milk (Raw/Process) 9.25 Lac Ltrs.

Total Project Investment :

OF- I/II 12 Crore 1978-1986

OF-III 33 Crore 1995-1998

---------------- 45 Crore

AWARDS:

Activities at Gokul are always towards giving best quality and test to consumer by

effective resource utilization and keeping best hygiene practices.

The plant has been awarded 14 times in dairy & animal feed processing segment since

1994-95 by National Productivity Council of India.

The Union also received the license from Export Council of India to export the products.

Awarded for “Sahakar Bhushan” by Government of Maharashtra.

First prize for Energy Conservation in Dairy Vertical by Government of Maharashtra.


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Here are some details of the awards that we have won over past years.

The image on the left

denotes 1st Prize for National

Productivity Council Award. The 1st Prize was

won for the following years: 89-90, 91-92 & 93-

94(won for both Dairy & Cattle feed categories)

Above

images

denotes 2nd

Prize for Nat

ional

Productivity

Council

Award. The 2nd Prize was won for the following

years.

o 92-93 (won for both Dairy & Cattle feed categories)

o 94-95 (won for both Dairy & Cattle feed categories)


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OVERALL PREVIEW

The milk coming from various dairies is first of all collected to the dock department.

Sample is taken from milk collected from each institute to measure fat and water percentage.

Whole stock of milk is then cooled to 4°C and stored in storage containers. As per the

requirement the milk is then taken to pasteurization department where it is pasteurized and then

stored again in separate tanks. Major part of this pasteurized milk is then sent to „Thane‟ and

„Vashi‟ for packaging. Remaining part is used to produce local packaging as well as other

products like- paneer, shrikhand, milk powder, curd, flavored milk, ghee, butter.

Produced products are first stored in the Cold Storage room and then distributed to

the market according to the needs.

All the vessels, cans and truck containers are sterilized or cleaned with help of hot

water produced by boiler. Also plate heat exchanger which is located at pasteurization unit is

cleaned after every 8hr. shift by hot water and acid C.I.P. is done after every 24hrs.

All the waste water along with mixed pollutants is then drained using drainage

system to E.T.P. where it is digested aerobically and anaerobically to produce Biogas and

Fertilizer so that water is purified and then let for agricultural use.

Overall View of Gokul

Plant


8

Total layout of GOKUL PLANT

(AutoCAD Drawing)


9

RMRD

All dairies dispatch their collected milk to plant from cans or from large truck

containers (from BMC).

MILK COMING FROM

CANS: -

Cans are received and unloaded from trucks at the dock department. These

cans are let on the roller chain conveyer. Lids of these air tights cans are opened using

can opening machine while moving along the conveyer. After opening lids of cans smell

testing is done. This is the first type of testing done on the incoming raw milk. Special

persons are appointed for this kind of skilled work. The acceptance or rejection of the

whole lot of milk send by each institute depends on this test. If any foul smell is found

then whole lot is rejected to avoid anything that will hamper quality of plant. The

accepted milk cans are then emptied into the collecting vessels. The milk collected from

each institute is given separate sample number while collecting in the vessel. Total

quantity of milk poured by each institute is measured electronically and recorded into

computer. Samples of milk of each institute according to their sample number are taken

into small sample bottles automatically, while pouring into the collecting vessels. The

sample bottles are made of plastic and are used again and again for cost saving. These

samples are then sending to dock lab using belt conveyer. These sample bottles are first

kept under stirrer, for homogenisation of sample, for at least 30sec. After

homogenisation, they are checked for Fat and water percentage. The data of each milk

sample is recorded against their sample number. The prices or rate of milk depends on

their fat and water percentage. The money to be given to each institution is calculated

automatically depending upon following factors:-

Quantity of milk

Fat present in the milk

Water percentage in the milk

Market rate

After checking milk samples, the sample bottles are washed using hot

water and resend back to the belt conveyer to collect new samples.

The emptied cans are kept inverted on the Chain-Roller conveyer for

collecting the remaining milk adhered inside of cans. The path of Chain-Roller conveyer

is increased for this is intended purpose. This is the best method for optimization.


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The inverted cans kept on conveyer are then conveyed to the sterilizing

machine. In sterilizing machine hot water is pumped from below, so that it is spread

inside the inverted can kept on the roller. This hot water is supplied from the boiler. The

hot water temperature is about 70°cel, as sterilization temperature is about is 66°cel. The

waste water is send to E.T.P. via drainage system. The advantage of keeping the cans

inverted is that the hot water is drained automatically due to gravity effect. After dripping

of all the water the cans are erected vertically using ratchet arrangement, which gets

locked into mouth of cans. The erected cans are then conveyed to the dispatch unit.

While all this process is done, a simultaneous process of sterilizing of lids

takes place. These lids are washed manually by hot water and brought to dispatch unit.

Before dispatching, the lid is assembled on the can and loaded in the truck.

TRUCK CONTAINER:-

The milk in the container is first stirred using stirrer manually for about

5minutes. Then 5 to 6 samples are taken and send to Dock testing lab where it‟s fat and

water percentage is measured and accordingly the rates are fixed. Then using pump the

milk is transferred to storage container where it mixes with the milk from cans. After

empting the tank completely the truck is send for sterilisation. Hot water from overhead

tanks is spread throughout internally and all the remaining milk is washed out. Again the

waste water mixes with sewage water and flows through drainage system to ETP.

Truck

Container


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BOILER DEPARTMENT

A boiler is a closed vessel in which water or other fluid is heated. The fluid does not

necessarily boil, which is used for various purposes. Boilers manufactured by IAEC are used in

GOKUL plant. Three boilers are used for accomplishing the requirement of hot water. Capacity

of boiler is 5ton i.e. 5ton of steam can be generated per hour. The type of boiler used is „FIRE

TUBE‟ boiler. At a time two boilers can handle the requirement of steam generation, so that

maintenance of the third can be done simultaneously. The ignition time for boiler is about 30min.

The hot water generated in the boiler is used for: -

Pasteurisation.

Sterilisation.

Butter/ ghee melting.

Can washing.

Tanker washing.

Operating pressure of boiler is about 17.5Kg/cm2. Old boilers were used to have only

mechanical ON/OFF system. There was no intermediate stage in oil feeding system. Recent

boilers have a stepper motor to control the stages of boiler. The stepper motor arrangement

controls the flame in small steps so that pressure does not decrease tremendously.

Boiler Department


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FUEL SYSTEM:

Fuel used is „furnace oil‟. Flash point of this oil is 66°C burning of 1liter of fuel produces

13liter of steam under standard operating condition.

There are 3 furnace oil tanks having capacity of 35000 liters each. The oil from these

tanks is fed to the 2 service tanks provided in the boiler section. From these service tanks oil is

fed to the boiler. This oil is filtered for the 3 times: firstly while passing in tank through tanker,

then while transferring it from the main tank to the service tank and at the entry in the boiler. The

unit cost of Furnace oil is 50Rs./ltr.

Before entering into the boiler oil is preheated using air preheater. Then it is fed to the

combustion chamber. In the chamber firstly a spark is created which causes burning of oil.

WATER SYSTEM:

Water is supplied to the plant from MIDC tank. It is stored in overhead tank having

capacity of 100000 liters. Then the water is passed to the 2 day tanks placed in the boiler section.

Then it is fed to the boiler by using feed pump. Lastly outlet steam of the boiler is fed to the

process.

CHIMNEY:

A chimney is a structure which provides ventilation for hot flue gases or smoke from a

boiler, stove, furnace or fireplace to the outside atmosphere. The height of a chimney influences

its ability to transfer flue gases to the external environment via stack effect. Additionally, the

dispersion of pollutants at higher altitudes can reduce their impact on the immediate

surroundings.

CHIMNEY SPECIFICATION

Standards for emissions of Air-pollutants from a factory are given below: -

a) SPM not to exceed 150mg/Nm3.

b) SO2 not to exceed 1.3T/day.

Chimney attached to Height in meter

Boiler 1 and 2 25.50

Boiler 3 30.00

Air heater 1 and 2 30.00

DG set(250KVA×3) 3.5*

DG set(625KVA×2) 3.5*


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ACCESSORIES:-

1. WATER LEVEL INDICATOR:

Water level indicator indicates level of water in the boiler. It also has provision of

automatic operation of feed water pumps. When water level in the boiler gets reduced below a

certain level then feed water pump starts automatically and after a predetermined level is been

reached pump stops automatically.

To achieve such automation a floating valve is provided. a small balance tank is

provided besides water level indicator in which this floating valve is provided. when water level

goes down the floating valve dips along with water level and electrical contact for feed pump is

established using bell crank lever. When water level rises above certain level, electrical contact

is broken and feed pump stops automatically.

2. SAFETY VALVE:

There is one spring loaded safety valve provided on the upper side of boiler shell

which is used to regulate the pressure. If pressure in the boiler increases beyond operating

pressure safety valve acts and releases excess amount of steam into atmosphere. Operating

pressure of safety valve used for boiler is 19 bar.

3. FUSIBLE PLUG:

Fusible plug is one of the safety device used on boiler. As the boiler has large

dimensions two fusible plugs are provided. As one fusible plug cannot take care of whole boiler

another fusible plug is provided. This provision is also useful when one of the fusible does not

operates. When pressure in the boiler increases beyond certain limit, the fusible plug operates. It

has a metal having low melting point which melts when steam reaches to a particular pressure

and at the same instant water is sprayed in the boiler which reduces amount of steam resulting

in reduction in pressure. Although operating pressure of boiler is 17.5 bar fusible plug operates

at 20-21 bar. This is one of the most important accessories in order to avoid blast of the boiler.


14

4. STEAM TRAP:

Steam trap is a device which is spaced equally throughout the pipeline carrying

steam. It is used to separate water particles from the steam and to provide completely dry steam

at the point of application.

BOILER PROBLEMS:

Nozzle choke up

Burner choke up

Oil temperature increases/ decreases

Vapour formation in furnace chamber

Filter choke up

Oil pressure increases/ decreases

Fuel Tank


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REFRIGERATION

Refrigeration is reduction of temperature of the body below the surrounding temperature.

It further implies maintenance of the temperature body below the surrounding temperature. In

Gokul Dairy Refrigeration is mainly used for chilling the milk, also for storing different milk

products. As the time passes after milking, growth of bacteria increases in exponential manner.

To avoid this milk is to be cooled to 4°cel.instantly. The bacteria become inactive below this

temperature. This cooling effect is achieved by using refrigeration system.

Basic refrigeration cycle diagram

Components of basic refrigeration cycle

Compressor

Condenser

Expansion device

Evaporator

Compressor: -

The low pressure and low temperature vapour refrigerant from evaporator is drawn into

the compressor then it is compressed to high pressure and temperature then discharges to

condenser.

Following are the compressors that we had seen:

1. Screw compressors

2. Reciprocating compressors

3. Bitzer compressor

Condenser:-

Condenser is device in which high pressure and temperature vapour refrigerant is cooled

by rejecting the latent heat to cooling medium and change of phase takes place from vapour to

liquid. condenser is a type of heat exchanger. Type of condenser that we had seen in plant is

„plate type heat exchanger (PHE)‟. Plant uses 3 Plate heat exchanger.

Receiver:-

The condensed liquid from condenser is stored in a vessel known as receiver from where

it is supplied to evaporator through expansion valve.


16

Expansion valve:-

The function of expansion valve is to allow the liquid refrigerant under high pressure and

temperature to flow to evaporator by reducing it‟s pressure and temperature.

Evaporator:-

Actual refrigeration effect produced by the refrigeration cycle is at the evaporator. In this,

cold liquid refrigerant reject its latent heat and converts into a vapour form.

0°C & -10°C Vessels

PHE Condenser


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REFRIGERATION CYCLES IN GOKUL

1) MAIN AMMONIA CYCLE:

Ammonia (NH3) from storage tank is supplied to screw compressor in form of vapour. In

compressor, the pressure and temperature of ammonia increases. 3 screw compressors are used

for this purpose.


18

Then this ammonia supplied to Plate Heat Exchanger (PHE) condenser. In condenser,

vapour ammonia condensed in to liquid form. This liquid ammonia is then stored in accumulator.

In the expansion valve, pressure and temperature decreases up to -10°C. From -10°C vessel, the

ammonia is supplied to Ice Bank Tank (IBT) where it is used to cool the water. This cooled

water is used for pasteurisation purpose.

After cooling the milk, warm water is then supplied to chiller for the purpose of

precooling. From IBT, ammonia is supplied to storage tank and cycle repeats.

This particular refrigeration cycle produces refrigeration effect of 225 TR.

Specifications of screw compressor used are:

Type: OH04131

Year of fabrication: 1995

Vessel number: 97674

Design code: DS 320

Media: R717

Maximum operating pressure: 28 bar

Test pressure: 35 bar

Maximum operating temperature: 130o C

Volume: 610 lit.

Actual working condition:

Suction pressure: 2.1 bar

Discharge pressure: 10.9 bar

Suction temperature: -3.5oC

Discharge temperature: 62oC

Oil pressure: 6.5 bar


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2) CHILLER CYCLE:

Ammonia coming out of deep freezer is supplied to „Bitzer compressor‟ in the form of

vapour. In compressor, pressure and temperature of vapour NH3 is increased. This high pressure

and high temperature NH3 is passed through condenser. In condenser, vapour NH3 is condensed

to liquid NH3. This liquid ammonia is passed through expansion valve where its temperature

decreases to 0°C. This liquid ammonia is stored in 0°C vessel. Liquid ammonia is entered in

chiller, where it absorbs heat from warm water. Because of this, liquid ammonia converted into

vapour. This vapour is then supplied to NH3 storage.

In pasteurisation process, chilled water is supplied which becomes hot. This warm water

is precooled in the chiller and supplied to IBT. Due to which performance of cycle gets

improved.


20

3) DEEP FREEZER CYCLE:

Ammonia vapour from storage is supplied to screw compressor. In compressor, this

vapour is compressed to high pressure and temperature. This compressed vapour is then

condensed. Due to this vapour ammonia is converted into liquid ammonia. Liquid ammonia is

supplied to accumulator. This liquid ammonia is passed through expansion valve where its

temperature decreases up to -10°C and stored in -10°C vessel. The temperature is further reduced

to -30°C by passing through second expansion valve. This -30°C liquid is circulated in deep

freezer.

Different products like Butter, shrikhand, Ghee are stored in this deep freezer. These

products are at room temperature. Because of this, liquid ammonia gets converted into vapour

ammonia. Due to this, -26°C is actually maintained in deep freezer. This ammonia vapour again

passed to NH3 storage.


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PASTEURIZATION

Pasteurization is a process of heating food, which is usually a liquid, to a

specific temperature for a predefined length of time and then immediately cooling it after it is

removed from the heat.

„Louis Pasteur‟ was a scientist who developed this technique for

enhancing life of food. Hence to honor him this process is known as „pasteurization‟.

Unlike sterilization, pasteurization is not intended to kill all micro-

organisms in the food. Instead, it aims to reduce the number of viable pathogens so they are

unlikely to cause diseases.

In olden days after milking it was possible to store milk only for some

time, so it was to be consumed immediately. Thus milk was available for a short period only

after milking. Due to pasteurization process now it is possible to store milk for about two days

(at low temperature).

There are two processes of pasteurization:

1. LTLT: Low Temperature Long Time

In this pasteurisation process milk is heated up to 63°cel. using hot

water, then it is maintained at that temperature for about 30min. this hot milk

is then cooled to 4°cel. i.e. below the growing temperature of bacteria.

2. HTST: High Temperature Short Time

In this pasteurisation process milk is heated up to 78°cel. using hot

water, then it is maintained at that temperature for about 15sec. this hot milk is

then cooled to 4°cel.


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PASTEURISATION FLOW CHART

Pump

Duplex Filter

Regeneration 1

Regeneration 2

Regeneration 3

Heating

Holding

Balance Tank

To storage

Flow Direction

Valve (FDV)

Separator

Homonizer


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ICE BANK:-

A bulk tank using an Ice Builder or Ice Bank immerses the bottom of the inner

milk chamber in an open pool of water with copper tubes containing refrigerant suspended in the

water. Between milking, a small low-power cooling system slowly builds up a coating of ice

around the copper tubes, and prevents icing of the pool over by continuously circulating the

water in the pool. After the ice has achieved a thickness of 2-3 inches, the cooling system stops

running.

During milking, the milk entering the tank is primarily cooled by circulating the

water in the pool around the walls of the inner milk chamber, and the melting of the ice. After

the ice has melted sufficiently the cooling system restarts to assist the ice bank and restart the ice

building.

Ice bank bulk tanks are better suited for small family farm operations where only

single-phase electric power is available, and high-power cooling systems would be either too

expensive or difficult to install.

Refrigeration Plant


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Effluent Treatment Plant

The word ETP implies „Effluent Treatment Plant‟ i.e. it is an industrial structure

designed to remove biological or chemical waste products from water, so that permitting the

treated water to be used for other purposes like agriculture.

The effluent treatment plant at gokul includes the following units:-

Raw Effluent Tank or Slag removal tank.

Fat Removal Unit.

Equalisation Tanks.

UASB (Up flow anaerobic sludge blanket digestion).

Aeration Tanks.

Clarifier.

Treated Effluent Tank.

The complete ETP cycle can be shown as below:-


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1) SLAG REMOVAL TANK: - In this tank the slag or the solid particles mixed with waste water are

removed by filtration. Then slag is separated manually from water and water is send to

fat removal tank by pump. The slag is send to sludge drying bed for drying so that it can

be used as fertiliser for agriculture.

2) FAT REMOVAL TANK: - In this tank FAT from mixture of milk and water is separated so that only

water is let for further use like agriculture purpose. GOKUL plant contains two FAT

removal tanks. Some specific type of bacteria is let into the tank which carries the process

of aerobic degradation. This removes the fat in the mixture. For proper aerobic conditions

stirrer is used. Water from slag removal tank enters first FAT removal tank where the

bacteria removes some amount of fat, then it is send to second fat removal tank where the

bacteria again carries process of degradation second time. Then the water is send to

Equalisation tank by gravity.

3) EQUALISATION TANK: - Equalisation is the process of removing the waste by equalising flow.

During turbulent flow the fluid tends to carry heavy solid particles which are also a

waste. So in equalisation tank, the speed of fluid is reduced in order to settle the solid

particle. In GOKUL plant there are two equalisation tanks. The water coming from FAT

REMOVAL TANK is send to first equalisation where some of the solid particles are

separated and then it is send to second equalisation tank where the remaining solid

particles are separated. Water is then sending to USAB by pump.

4) UASB: -

UPFLOW ANAEROBIC SLUDGE BLANKET DIGESTER is an

anaerobic type of digester which mainly produces „methane‟. UASB uses an anaerobic

process whilst forming a blanket of granular sludge which suspends in the tank.

Wastewater flows upwards through the blanket and is processed (degraded) by the

anaerobic microorganisms. Biogas with a high concentration of methane is produced as a


26

by-product, and this may be captured and used as an energy source, to generate electricity

for export and to cover its own running power. The technology needs constant monitoring

when put into use to ensure that the sludge blanket is maintained, and not washed out

(thereby losing the effect). The heat produced as a by-product of electricity generation

can be reused to heat the digestion tanks. If the treatment is unsatisfactory, then it is again

send to Equalisation tank, else it is send to Aeration tank by gravity.

5) AERATION TANK: -

The main purpose of an aeration tank is to facilitate the biological

treatment of wastewater by pumping or inducing air into it. There are two aeration tanks

in the GOKUL plant. Two stirrers are used to aerate the water present in these tanks. An

aeration tank should be leak-proof, and sufficiently large to enable aeration to take place

without overflowing. A typical aeration tank comprises an aerator, a wastewater inlet, a

treated water outlet and a sludge outlet. In general, wastewater should be continuously

aerated so as to maintain a dissolved oxygen level of 1-2mg/L for 18 to 20 hours. This

should be followed by at least an hour of settling in order to achieve the required quality

for discharge. The settled sludge should be drained off to a drying unit after each aeration

cycle. It must be stressed that excessive aeration could also result in very poor treated

water quality. Then water is send to clarifier by gravity force.

6) CLARIFIER: -

Clarifiers are settling tanks built with mechanical means for continuous

removal of solids being deposited by sedimentation. A clarifier is used in waste water

treatment. It works by separating solids and water. They are large circular open air tanks.

The clarifier works by having the waste water enter through the center tower. The flow of

the water slows down allowing for solids to settle on the floor. The solids are then

directed to the center of the clarifier by using slow moving collection scrapers. The clear

water then exists the tank and is treated for use. If the treatment is unsatisfactory then the

water is again send to aeration tank, otherwise it is send to Treated effluent tank.

7) TREATED EFFLUENT TANK: -

Before leaving the processed to water to agricultural field, it is first send to

a small treated effluent tank. The size of treated effluent tank is about 4m3

. Two baffles


27

are used so that flow becomes steady and any remaining impurities are trapped so that

only clear is delivered.

CASE STUDY

BULK MILK CHILLER:-

To maintain the quality of procured milk, it must be cooled to 4 degrees within a

short time of milking. It results in limited bacterial build-up resulting in better quality of milk for

processors resulting in better prices to Dairy Farmers. BMCs mostly installed in India are of

capacity 1000L to 5000L. Off late, 10000L BMCs are also becoming popular. Sometimes, each

BMC even caters to a cluster of 15-20 Villages around it and serves the purpose of a chilling

center working at low cost of operation. Chilled Milk from these BMCs is then transported to

processing plants by Milk Tankers.

As per International Standards for Bulk Milk Coolers, ISO 5708, Bulk Milk

Cooler should be designed in such a way that for the first milking, the raw milk at temperature of

35 deg Centigrade must be cooled to 4 deg Centigrade within 4 hours when BMC is running at

ambient temperature of 38 deg Centigrade.

In dairy farming a bulk milk cooling tank is a large storage tank for cooling and

holding milk at a cold temperature until it can be picked up by a milk hauler. The bulk milk

cooling tank is an important piece of dairy farm equipment. It is usually made of stainless steel

and used every day to store the raw milk on the farm in good condition. It must be cleaned after

each milk collection. The milk cooling tank can be the property of the farmer or be rented from a

dairy plant.

TANK CONSTRUCTION:-

A milk cooling tank, also known as a bulk tank or milk cooler, consists of an

inner and an outer tank, both made of high quality stainless steel.

The space between the outer tank and the inner tank is isolated with polyurethane

foam. In case of a power failure with an outside temperature of 30°C, the content of the tank will

warm up only 1°C in 24 hours.


28

To facilitate an adequate and rapid cooling of the entire content of a tank, every

tank is equipped with at least one agitator. Stirring the milk ensures that all milk inside the tank

is of the same temperature and that the milk stays homogeneous.

On top of every closed milk cooling tank is a manhole of about 40 centimeters

diameter. This enables thorough cleaning and inspection of the inner tank if necessary. The

manhole is covered by a lid and sealed watertight with a rubber ring. Also on top are 2 or 3 small

inlets. One is covered with an air-vent; the other(s) can be used to pump milk into the tank.

A milk cooling tank usually stands on 4, 6, or 8 adjustable legs. The built-in tilt of

the inner tank ensures that even the last drop of milk will eventually flow to the outlet.

At the bottom, every milk cooling tank has a threaded outlet, usually including a

valve. All tanks have a thermometer, allowing for immediate inspection of the inner temperature.

Most tanks include an automatic cleaning system. Using hot and cold water, an

acid and/or alkaline cleaning fluid, a pump and a spray lance will clean the inner tank, ensuring a

hygienic inner environment each time the tank is emptied.

Almost every tank has a control box. It manages the cooling process by use of a

thermostat. The user can turn the system on and off, allow for extra and immediate stirring, start

the cleaning routine, and reset the entire system in case of a failure.

http://en.wikipedia.org/wiki/File:BulkMilkCoolingTankDescriptionCharriau.png


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New and bigger milk cooling tanks are now being equipped with monitoring and

alarm systems. These systems guard temperature of the milk inside the tank, check the

functioning of the agitator, the cooling unit and temperature of the cleaning water. In case of

malfunctioning of any of these functions, the alarm will activate. The monitoring system will

also keep a record of the temperature and of all malfunctions for a given period.

MANUAL SCRUBBING:-

Manual scrubbing requires the bulk tank to have large hinged covers that can be

lifted open to permit easy access to the interior surfaces of the tank. It tends to be much more

thorough than automatic methods since it permits the tank to be carefully inspected during the

washing process. If the tank is not found to be cleaned well enough, a troublesome area can be

given additional cleansing attention.

Manual Scrubbing Limitations

This job is difficult to perform for very large tanks, and becomes more difficult as

the overall cross-section or diameter of the tank increases, requiring either a longer brush or a

raised work platform around the tank to lift the cleaning worker to reach over the side of a tall

tank.

AUTOMATIC WASHING:

Automatic bulk tank washing systems are used in closed tanks and are normally

activated by the milk collection truck driver after each milk collection. The cleaning system

operates similar to a consumer dishwasher and consists of one or more free-spinning high-

pressure spray nozzles with tangential jets, with the spray nozzle mounted on the end of a

flexible whip suspended down into the center of the interior. As the cleaning solution sprays out

of the jet, the force of the expelled water causes the jet to spin around and the whip to wildly

swing back and forth, spraying the cleaning solution randomly all over the interior of the tank.


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Automatic Washing Limitations

Because no physical scrubbing occurs with automatic wash systems, the cleanser

relies on surfactants and detergents to dissolve the fats left on the interior of the tank by the

cream in the milk. However, this is not sufficient to remove milk stone buildup, and the tank may

need to be washed occasionally with milk stone remover to remove this scale buildup that can

harbor bacteria and contaminants.

Automatic scrubbing only cleans the interior of the tank. It is not capable of

cleaning the exterior of the tank, and it does not do a good job of washing around the cover seals.

While it is possible to just clean the interior and call it good enough, it does not provide the

maximum sanitation of manually washing down the exterior of the tank following or during the

automatic wash process. Also, some components that contact the milk such as the drain valve

cannot be properly cleaned automatically without disassembling the valve and retaining washer

and directly scrubbing in soapy water.

Operating costs

Substantial reductions in running costs can be made when an ice builder is used in

conjunction with off-peak electricity. Pre-cooling milk using a plate or a tube cooler supplied

with mains or well water can also reduce costs and add to the cooling capacity of the tank.

Bulk tank condenser units, which are not an integral part of the tank, should be

fitted in an adjacent, suitable and well ventilated place.

If at all possible, condenser units should not be fitted on a wall facing the sun.

They should be installed in a way which allows them to draw in and discharge adequate

quantities of air for efficient operation.

Bulk tank should be easily accessible by large bulk collection tankers and

positioned so that the tanker approaches can be kept clean and free from cow traffic at all times.

Although tanks have been calibrated when first installed, bulk tank mis-calibration is not

uncommon and in some cases it can result in significant loss of income. Milk tanks calibrated on


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the low side can cheat raw milk producers by up to 22 liters on each shipment. It is therefore

advisable to re-calibrate a bulk tank.

CHUYE:

The plant consists of dump tanks of 250lit.capacity and 3000lit.tank both for cow

milk. It also consist a 2000lit. tank for buffalo milk. Collection of cow milk on an avg. is

between 1600 to 1750lit. and of buffalo milk is about 900 to 1200lit.

VADKASHIWALE:

The plant consists of dump tanks of 200lit.capacity and 5000lit.tank both for cow

milk. It also consist a 1000lit. tank for buffalo milk. Collection of cow milk on an avg. is

between 1600 to 1750lit. and of buffalo milk is about 700 to 900lit.

Milk is collected in 2 stages at 6 a.m. and 6.30 p.m. Tanker arrives at 10 a.m.

and milk collected in both stages is transferred to it. After emptying the BMC tank it is

washed thoroughly with hot water. Water is heated with the help of electric heater or by

means of LPG gas (in situation of power failure). The temperature of hot water is about

67°c.


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First cycle of BMC starts in the evening. Samples of incoming milk are taken to measure fat and

water per cent and accordingly rates are fixed. After sampling is done, milk is poured into a

vessel from where it is send to dump tank. When the dump tank is about to be filled, it is send to

BMC tank with the help of pump. When 2-3 dump tanks are poured to BMC tank, cooling of

BMC tank is started. After about an hour or so, the milk in BMC attains required temperature of

4°c. then the cooling of BMC is stopped. In this cycle BMC is about half filled.

The second cycle is similar to first cycle only the difference is; milk is added to

the milk in the previous cycle.

Observation table for BMC tank is shown below:

CHUYE:

Sr. No. BMC ON BMC OFF Temp.(°C) Voltage(V) Current(A) Power(KW)

01 6:35 AM 8:05 AM 8.5 405 57.5 24


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02 7:15 PM 8:45 PM 11.5 489 57.5 28

03 6:55 AM 8:20 AM 10.5 406 57.5 24

04 7:20 PM 9:00 PM 11.0 394 57.5 23

VADKASHIWALE:

Sr. No. BMC ON BMC OFF Temp.(°C) Voltage(V) Current(A) Power(KW)

01 6:30 AM 8:00 AM 7.5 409 57.5 24

02 7:10 PM 8:40 PM 11.0 398 57.5 23

03 6:35 AM 8:10 AM 7.5 397 57.5 23

04 7:00 PM 8:35 PM 9.0 405 57.5 24

Suggestions:

1. Air blower can be used to take out all the adhered milk.

2. Evaporator location should be changed in order to increase heat transfer rate.

3. More local dairies should be equipped with BMC.


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REFERENCES

Kolhapur zilla sahakari dudh utpadak sangh ltd.

Gokul Dairy,

Gokul Shirgaon MIDC,

Kolhapur.

Principles of refrigeration – Roy J. Dossat

Refrigeration and Air Conditioning – Arora Domkundwar

Refrigeration and Air Conditioning – V.K.Jain

Heat & Mass Transfer – R.C.Sachdeva

Gokul Final Report

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