Shakrganj mills internship report by Imitaz.docx

7/27/2019 Shakrganj mills internship report by Imitaz.docx

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Imtiaz Ali

Najeeb ur Rehman

1

U.E.T Lahore

Imtiaz Ali 2010-Ch-7

Najeeb Ur Rehman 2010-CH-9

U.E.T Lahore

Shakarganj Mills Private limited


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Letter of Transmittal

Mr. Imtiaz Ali,

Mr. Najeeb ur Rehman,

University of Engineering and Technology

Lahore.

HOD production House,

Shakarganj Mills Jhang

Respected Sir,

Here is the report on Production department OfShakarganj sugar mill you

asked to submit on 30th July 2012.As you will see in the report, we have discussed

about the understanding of the flow of Juice, some, how juice is extracted fromsugarcane, steam production and power production plant.

We have put our best in this report to make it effective and understandable. We

hope our report will be according to your demands from us. If you need any assistance

in interpreting this report please contact us.

Yours sincerely,

Signature: Dated: 30th

July 2012


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Executive Summary:

First of all the cane is generally weighted on large platform scale in

the transport unit. Then the sugarcane is carried to the mill house for the extraction of

juice from it. After extraction juice is sent to the heaters and clarifiers for purification.When larger impurities like mud are removed then juice is carried to the evaporators

where water is removed and Syrup is transported to the Pan station where

crystallization occurs.

Then for further clarification of the liquor it is sent to the Telo station. At the end

clarified liquor is Refined at the Refined Pan station. Refined sugar is dried and packed

for commercial use.


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Acknowledgements:

My gratitude is for the well-esteemed organization Shakarganj for givingme an opportunity to enhance my practical knowledge in the field of SugarManufacturing.

This internship report could not have been completed without the help ofcapable and concerned individuals. First and foremost, I would like to thank Engr.Shahzad and Engr. Zeshan, of Production Department of Shakarganj under the kindSupervision of whom I have completed this report.

Special thanks to Mr. Ammar Hanifand Engr. Nouman for helping us in everysort of quarries during the period of our internship.

I would also like to thank the Engineers, Supervisors and In-charges ofBoiler House, Power House, Mill House and Process House who very generously let meenhance my knowledge and also made me familiar with the professional attitude,manner and skills as well.


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Contents

Introduction: ........................................................................................................................................... 7

Cane Unloaders ..................................................................................................................................... 7

Mill house tandem No.1.................................................................................................................... 8

Dumping Carrier ........................................................................................................................................ 8

Main Carrier .............................................................................................................................................. 8

Levelers ..................................................................................................................................................... 9

Pusher Drum ............................................................................................................................................. 9

Fabirizer .................................................................................................................................................... 9

Magnetic Iron Separator ........................................................................................................................... 9

Mill house Tandem No. 2 ................................................................................................................ 10

Cutters ..................................................................................................................................................... 10

Cane Shredder ......................................................................................................................................... 10

Rotary Mills ................................................................................................................................................. 11

Mill House Output ................................................................................................................................... 11

Boiler House.......................................................................................................................................... 12

Types of Boilers ....................................................................................................................................... 12

Boiler Fans ............................................................................................................................................... 14

ID Fan (Induced Draught Fan): ............................................................................................................ 14

FD Fan (Forced Draught Fan): ............................................................................................................. 14

SD Fan (Secondary Fan): ..................................................................................................................... 14

Super heater ........................................................................................................................................... 14

Air Pre-heater .......................................................................................................................................... 15

Key Factors For Boiler Efficiency Calculations ........................................................................................ 15

Boiler Water treatment Plant ....................................................................................................... 15

Why we need Water Treatment?......................................................................................................... 15

Reverse Osmosis Plant ........................................................................................................................... 16

Demineralization plant: ......................................................................................................................... 17

Deaerator ................................................................................................................................................ 17


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Power House..................................................................................................................................... 18

Back Pressure Turbine............................................................................................................................. 18

Condensed Turbines ............................................................................................................................... 18

Production House............................................................................................................................... 19

Primary Heaters ...................................................................................................................................... 19

Defication tanks ...................................................................................................................................... 20

Lime Dozer .............................................................................................................................................. 20

Retention Tanks ...................................................................................................................................... 20

Defecation Tanks: ................................................................................................................................... 21

Secondary heaters .................................................................................................................................. 21

Flash Tank ............................................................................................................................................... 21

Clarifiers .................................................................................................................................................. 21

Mud Level in Clarifiers ............................................................................................................................ 22

Mud Boot ................................................................................................................................................ 22

BD (begasse dust) Mixer ......................................................................................................................... 22

Vacuum Filter .......................................................................................................................................... 22

Preheaters: ............................................................................................................................................. 23

Evaporators........................................................................................................................................... 23

Syrup storage tank .................................................................................................................................. 26

Raw crystallization............................................................................................................................. 26

Sugar Refining ...................................................................................................................................... 30

Reaction tank .......................................................................................................................................... 31

Telo Clarifiers .......................................................................................................................................... 32

Pressure filters ........................................................................................................................................ 33

Deep Bed Filters ...................................................................................................................................... 34

Refine crystallization and centrifugation ................................................................................ 35

Packaging and storing of refined granulated sugar ........................................................... 35


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Introduction:

Steps involved in sugar manufacturing:

Cane Preparation Milling/Juice Extraction Juice Purification Evaporation Raw Sugar Crystallization Liquor Clarification Refinery Sugar Crystallization

Drying and Packing

Cane Weighing:

Cane is Brought from cane yard to Sugar Factories on the Trucks and

Trawlers .Cane weighing is take place with the help of Three Weigh Bridges. These

Weigh Bridges are Avery England Design .02 Weigh Bridges are for Gross Weight and

01 Weigh Bridges is for Tare Weight..Capacity of the Weigh Bridges is 50 Tons.

Mill House:

After weighing of the cane, sugarcane is moved to the mill station for the

extraction of the juice. There are two mills working for the extraction of the juice named

as:

Mill house Tandem No. 1

Mill house Tandem No. 2

Cane Unloaders:

There are two types of Unloaders

Mechanical type cane unloader

Hydraulic type cane unloader

The function of cane unloader is to pick the cane from the tractor and put in to thecarrier. Cane Unloading is done with the help of Electric Hoists. Three Electric Hoist are

attached to Mill Tandem .The Function of these Electric Hoists is to Lift the Cane loaded

Truck and throw it to Dumping Carrier. It can lift 40-50 ton at a time.

Lifting Speed 13-20 ft/ min

Lifting Height 20 m


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Mill house tandem No.1:

Dumping Carrier:

There are three dumping carrier in each mill tandom. In Which sliding

plates are attached which carry the cane to the Main Carrier. Idler Pulleys are used to

support the chain on which sliding plates move. These idler pulleys are coated with

some material so that to stop wear and friction. V-Belt drive used to transmit power from

motor driven shaft to gear system and from there with the chain sprocket mechanism it

drives the Dumping.

Dumping Carrier Length 42 ft

Dumping Carrier Angle 18deg

When high torque load is to be transmitted. We use chain sprocket mechanism. By the

Formula of power as torque is very high and speed is low then slippage takes place. So

belt could not be used there and chain sprocket mechanism is the better choice.

Main Carrier:

After passing out through the Dumping cane carriers, sugarcane moves

into the Main cane carrier. Mill Tandem no. 1 has main cane carriers of different lengths.

Main cane carrier in Tandem no. 2 has three cutters while main carriers of Tandom no.

1 have two levelers on it to move the cane in an organized way.


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Levelers:

As the name implies it function is to provide evenly feed to cutters. Mill

Tandem No. 1 has two Levelers. These are rotated by the motors. As they rotate theylevel the sugarcane passing through the levelers. Leveling the cane not only increases

the capacity of the Tandem but also it makes the juice extraction easy.

Leveler 1 No. Of arms 26

Leveler 2 No of arms 24

Pusher Drum:

The function of the pusher drum is to push the compact sugar cane to the

Fabiriser.

Dia of Drum 2250 mm

Length of the Drum 7200 mm

Fabirizer:

Fabirizer does the same function in Tandom #1 as Shredder in Tandom #2.In

Fabirizer it takes input feed from the top and pushes it to the bottom. It has anvil plate

on the top. Then it has feed rake bar and rake bar under carrier.It is Turbine Driven.

Magnetic Iron Separator:

Iron or other harmful metals may attach to the sugar during harvesting

or transporting. These particles must be removed otherwise they may harm the mills.

The purpose of magnetic iron separator is to separate the iron particles attached to the

sugarcane.

Power 17.7 kW


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Mill house Tandem No. 2:

Cutters:The purpose of cutters here is to cut the cane in small pieces so that they

are easily shredded and juice cane be extracted more efficiently. Ther are Three cutters

for Mill House Tandem No. 2.

Cutter #01 No. of knives 70

Cutter # 02 No. of knives 70

Cutter # 03 No. of knives 52

Cane Shredder:

The main function of the shredder is to rapture the structure in order to

open the cells of the cane .It is driven by Backpressure Impulse Turbine. This Shredder

is covered by anvil plate .It is below the Shredder. It has very low spacing in mm with


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U.E.T Lahore

hammers . Shredder has Stainless steel hammers with beadings. Shredder gets feed

from below and takes it above .that is why its anvil plate is below.

Rotary Mills:

This is the area where juice is extracted from the cane and is separated from

the Baggasse.Numbers of mills for Mill House Tendem No.1 and Tandem No. 2 is

different. Rotary Mills are run by th turbines which provide sufficient Mechanical Energy

to rotae the mills. Cane passes through these rotary mills and juice is extracted from the

cane by rotary motion of the mills leaving Baggasse behind.

No. of mills For Tandem No. 1 5

No. of Mills for Tandem no. 2 6

Mill House Output:

Screened cane juice and bagass is the output of the mill house.

The manager needs to process the cane as soon as possible if sugar losses are to be

avoided yet needs to have a sufficient supply in storage for times when cutting and

transport are stopped, whether deliberately or not. Typically, cane is processed within

24 hours of cutting;


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Cane preparation is critical to good sugar extraction, particularly with diffusion

extraction. This is achieved with rotating knives and sometimes hammer mills called

"shredders". However shredding requires extra energy and more equipment;

Imbibitions:

The extraction is actually conducted as a counter-current process using fresh hot water

at one end being pumped in the opposite direction to the cane. The more water that is

used, the more sugar is extracted but the more dilute the mixed juice is and hence the

more energy that is required to evaporate the juice;

Compositions:

A typical mixed juice from extraction will contain perhaps 15% sugar and the

residual fiber, called bagass, will contain 1 to 2% sugar, about 50% moisture and some

of the sand and grit from the field as "ash". A typical cane might contain 12 to 14% fibre

which, at 50% moisture content gives about 25 to 30 tons of bagass per 100 tons of

cane or 10 tons of sugar

Boiler House:

A boiler is a closed vessel in which water or other fluid is heated

Types of Boilers:

1.Water Tube Boiler:

In water tube Boiler a number of water tubes are arranged in and

around the furnace.Water circulates in the tubes and outside is the fire. This type

generally gives high steam production rates, but less storage capacity. water tube

boilers are also capable of high efficiencies and can generate saturated or superheated

steam


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2. Fire Tube Boiler:

In fire Tube Boiler There is a fire in the tubes and water is present

outside the tubes in the big vessel or cylinderical drum. Fire-tube boilers usually have a

comparatively low rate of steam production, but high steam storage capacity


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The type of boiler in use in Shakrganj mill is the water tube boiler. The number of boilers

are 3. These boilers use Baggasse or SUI gas as their fuel. In off season, SUI gas gas

is use for the production of the steam because no availability of the baggase. The

baggase fed to boilers is that coming from the Mill House Teandem o.1 and 2 and it

contains 50% moisture.

The working conditions of these Boilers are as followed:

Steam Temperature 325-350 C

Working Pressure 23-24 kg/ g.cm2

Boiler Fans:

ID Fan (Induced Draught Fan):

Induced draught fan draw gases out of the boiler. The gas has

already passed through the air heaters and precipitators before it has reached these

fans.

FD Fan (Forced Draught Fan):

It takes air from atmosphere and passes it through the air pre-heatertubes, which is then blown into the furnace from its base through dumping gate. This

warm air helps in combustion and spreading bagasse. Each unit has forced draught fan.The fan draws warm air from the top of the boiler house through large air heatersbecoming the primary and secondary air used for the boiler combustion process. The airheater warms the incoming air by transferring heat energy from the outgoing flue gases.

SD Fan (Secondary Fan):

Secondary Fan is also admitted turbulently to complete the combustion.

This fan supplies air to the furnace from the bottom surface to ensure complete

combustion. This fan is only used when Bagasse is used as fuel otherwise it is kept off.

Super heater:

A super heater is a device in a boiler that heats the steam generated by the

boiler again, increasing its thermal energy and decreasing the likelihood that it will

condense inside the header.


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Super heaters increase the efficiency of the boiler, and were widely adopted. Steam

which has been superheated is logically known as super heated steam.

Air Pre-heater:

This air pre-heater is used to heat the air inducted to the boiler by the hot flue

gases. Thus raising the temperature of inlet air up to 110 C.

Economizer:

Flue gases from large boilers are typically 450 - 650F.Economizers recover

some of this heat for pre-heating water. The water is most often used for boiler make-

up water or some other need that coincides with boiler operation. Economizers should

be considered as an efficiency measure when large amounts of make-up water are

used

Key Factors For Boiler Efficiency Calculations:

Flue gas temperature (Stack temperature)

Fuel specification

Excess air

Ambient air temperature

Radiation and convection losses.

Boiler Water treatment Plant:There are two plants for treatment of water that is fed to the boiler.

Reverse osmosis plant

Demineralization plant

Why we need Water Treatment?

Impure water may cause many problems in the boiler so it must be pured

someway to avoid problems in the boiler. The most common problems caused by the

impure water are as followed:

Scaling:

Total hardness in the water if not properly removed will cause in scale

formation. A layer of scale on the metal surface of the boiler will acts as an insulator and

reduce the rate of heat transfer from hot zone to water. Scaling results in


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More fuel will be used to maintain boiler output at acceptable level

Since heat transfer is retarded the metal become hotter to a point where it deforms

and even rapture with disastrous results

Corrosion:

The most common source of corrosion in boiler systems is dissolved gas: oxygen,

carbon dioxide and ammonia. Of these, oxygen is the most aggressive. The importance

of eliminating oxygen as a source of pitting and iron deposition cannot be over-

emphasized. Even small concentrations of this gas can cause serious corrosion

problems

Sludge formation:The impurities which are floating on the surface in the form of light fluffy mass are called

sludges .These are insoluble impurities that float at the surface of water at high

temperature. Treatment is as follows:

The impurities of Na , Ca , Mg ,react with ant scaling agent and form their

sulphates and phosphates which are easily removed. However due to sludge

formation the rate of water evaporation is decreased .The sludge formation starts at

40oc and maximum sludge is produced at 80

oc, at this temperature it is automatically

drained off.

Reverse Osmosis Plant:

Reverse osmosis plants have at their heart a membrane that if damaged reduces

output, increases costs and gives poor water quality so it is important to keep it clean

and operating efficiently.

Most reverse osmosis membranes are formed from hollow fibre or thin film composite

sheets with the membrane allowing passage of pure water and rejecting the dissolved

solids contained in the water.As water passes along the membrane surface the solids

concentration increases and some sparingly soluble salts start to exceed their solubility

and precipitate. When precipitated onto the membrane surface this causes fouling that

may reduce output and increase product water conductivity. The worst of these solids

being calcium carbonate and calcium sulphate and so the prevention of their

precipitation is vital if the membrane is to function efficiently.


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Demineralization plant:

A Demineralisation Plant consists of two pressure vessels

containing cation and anion exchange resins. Various types of ion exchange resins can

be used for both the cation and the anion process, depending on the type of impurities

in the water and what the final water is used for. Typically, the cation resin operates in

the hydrogen cycle. The cat ions in the water (i.e. calcium, magnesium and sodium)

pass through the cation exchange resin where they are chemically exchanged for

hydrogen ions.

The water then passes through the anion exchange resin where the anions (i.e.

chloride, sulphate, nitrate and bicarbonate) are chemically exchanged for hydroxide

ions. The final water from this process consists essentially of hydrogen ions and

hydroxide ions, which is the chemical composition of pure water.

Simple demineralisation plant consist of Composite resin vessels with charge

of strong cation and anion resin; control-panel encompassing a conductivity

measurement and alarms, etc; acid and caustic injection facility from bulk, semi-bulk or

carboy containers.

Deaerator:

purposes of deaeration are: To remove oxygen, carbon dioxide and other non-condensable Gases from feed

water.

To heat the incoming makeup water and return condensate to an optimum

temperature for:

i. Minimizing solubility of the undesirable gases

ii. Providing the highest temperature water for injection to the boiler


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Power House:

Power house use s steam produced by the boiler house to generate

electric power.In power house first heat energy of steam is converted in mechanical

energy by turbines and then mechanical energy is converted into electrical energy by

the help of generators.

In Shakarganj mills two different types of turbines are used for the creation of

mechanical energy:

Back pressure Turbines

Condensing Turbines

Back Pressure Turbine:

First three Turbines in the powerhouse are backpressure Impulse Turbines.

Backpressure means that the exhaust of these turbines is not also steam of

pressure above than atmospheric pressure. Noncondensing or backpressure

turbines are most widely used for process steam applications. The exhaust pressure

is controlled by a regulating valve to suit the needs of the process steam pressure.

These are commonly found at refineries, district heating units, pulp and paper

plants, and desalination facilities where large amounts of low pressure process

steam is available.

Advantages of Back pressure Turbines:

1- Process Heat For various Operating loads can be provided.

2- Electrical power to meet the own and for Feeding into the Public grid is available.

3- Balancing of operational Fluctuations between Power and steam requirement.

4- Avoidance of exceeding the maximum Demand limits for power imported from

the Public grid.

Condensed Turbines:

Condensing turbines are most commonly found in electrical power plants.

These turbines exhaust steam in a partially condensed state, typically of a quality near

90%, at a pressure well below atmospheric to a condenser.


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Production House

Juice that is coming from milling house has following properties;

Acidic

Opaque

Greenish color

Brix (thickness) 10 15

Soluble impurities

Insoluble impurities like proteins, waxes, gums etc.

Physical and chemical processes are required for the production of sugar. These

operations carried out in process house.

Main units in process house are:

Primary Heaters:

Juice which is coming from Tandem 1 and Tandem 2 is pumped to primary

heaters, there are three primary heaters for tandem 1 and tandem 2, two set for each

tandem. Heaters used for heating juice coming from tandem 1 is called primary heaters

set no.1 and that is used for heating juice of tandem 2 is called primary heater set no. 2.These are shell and tube heaters, heating are done by vapors coming from evaporators,

juice moves in tube side and vapors in shell side, duplex valves are used for the transfer

of juice in heaters. Heating is done for proper reaction with lime in reaction tank.

Juice heating temperature 60-770C


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Defication tanks:

Defecation is process of removal of impurities by the action of lime and

heating. Defication is carried out in following equipments

Lime Dozer:

Juice coming from primary heater set no. 1 and primary heater set no. 2

enters in lime dozer from top. Here we add lime {Ca (OH)2} to it.

CaO + H2O Ca (OH) 2

Lime is used to combine impurities that is present in juice because juice is acidic in

nature and when lime is added which is basic in nature then pH is maintained at 7.8 to

8.2.

Retention Tanks:

In retention tanks juice enters from the bottom. The object of these

tanks is to mix juice with lime and to give the reaction to lime and juice and reaction time

is provided. There are four retention tanks in SML. In retention tanks plates are

arranged in manner that one plate is below and other is above, this arrangement is

done for proper mixing and mixing is done by agitation.


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Defecation Tanks:There are two defecation tanks in SML. Juice coming from retention tanks enters in

defecation tanks separately. From defecation tanks juice is pumped to the secondary

heaters.Two centrifugal pumps are attached to each tank pumping the juice to thesecondary heaters.

Secondary heaters:

Neutralized juice coming from defecation tank no.1 and defecation tank no.2 is

heated in secondary heaters set no. 1 and secondary heaters set no.2 respectively.

These are total eight (8) in numbers and four (4) for each set. Heating media in first

three secondary heaters is vapors that is coming from evaporators and in forth one

heating is done by exhaust stream (stream that is exhausted from turbine). Exhaust

stream is used because we require high temperature to clarifier the juice and vaporscant do this job.

Juice heating temperature 100 - 1050C

Flash Tank:

Juice that is heated in secondary heaters set no.1 and secondary heater setno. 2 is now brought to flash tank with the help of duplex valves (to bypass the

juice).Flash tank is simply a conical tank where juice is entered from the side of conicalsection. There are four(4) flash tanks one for each clarifier. It helps in removing vapors

and to avoid bubbling of heated juice in Clarifier. The purpose of flash tank is to removenon condensable gases and air from juice. Now juice is transferred to next equipmentfrom bottom of flash tank.

Clarifiers:

There are four (4) clarifiers. Clarifiers are used for the clarification of juice.

Bagasse and mud are removed here.Poly electrolyte (poly acryl amide) solution is

added in clarifier from coagulation tank (tank where solution is prepared) . The stock

solution of polyelectrolyte is prepared in one tank and then diluted in two tanks. The

dose of polyelectrolyte is in ppm. The stock solution of polyelectrolyte is prepared

before 8-10 hours. There are two coagulation tanks in SML one is sufficient for two

clarifiers. Overflow Juice from clarifier is collected in juice tank at the side of clarifier

then it is passed through 80- mesh screen where particles present in juice are removed

then it sent to clear juice tank.


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In sugar industry, clarifiers are the complicated and more sensitive point. These

clarifiers are actually responsible to run an industry or shut down. It is the process

where the juice is clarified.

Mud Level in Clarifiers:

The mud level in the clarifiers is determined by dipping iron rod with

thread. When it touches the mud, the length of the thread is measured and we came to

know the level of the mud in clarifiers. Then the clear juice is passed through 60 to

80mesh plate into the clear tank. This juice must be clear. If juice is not clear, then it

increases many problems

Suspended and dissolved particles decrease brix in evaporators due to

scale formation.

More energy is required to get same level of brix of syrup. The sugar produced contains fibrous material as foreign matter

Mud Boot:

Impurities which are settle down in clarifier are collected in tank known as

mud boot placed at the bottom of the clarifier. There are four mud boots, one for each

clarifier.

BD (begasse dust) Mixer:

Mud from mud boot is pumped to BD mixer and baggasse from mill house

is added with the help of conveyer. It is simply a vessel and baggasse is added just to

increase pore size of mud so that we can easily separate juice from mud

Vacuum Filter:

Mixture of mud and baggasse is brought to vacuum filter. There are ten (10)vacuum filters in SGL.Here vacuum pressure about 30-35 cm Hg is applied by thevacuum pumps.Vacuum filters are use to remove sweetness from mud. This drumrotates at a very slow speed i.e. 0.5 rpm. When it is rotated, mud become attached withthe walls and at the same time mud is treated with hot water from the top.

Sweetness of input juice = 75%


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Sweetness in output juice = 2-2.5%

Clear juice goes to turbid juice tank and then to reaction tank for further

clarification.Mud is sent to bio-composting plant where after composting with stillage

(waste of distillery) bio-compost is prepared.

Preheaters:Clear juice after screening goes to preheaters where juice is heated up to

1050C.There are two(2) prheaters in SML.Juice is preheated before evaporation.

Juice heating temperature 100 - 1050C

Evaporators:

The clarified juice (85% water) in clear juice tank is pumped to evaporators

where it is concentrated to a heavy clear syrup. Evaporation is done in multiple effect

evaporators to achieve maximum steam economy .Each effect is arranged in series

and operated so that each succeeding one operates under high vacuum (lowpressure). This arrangement allows the juice to be drawn from one vessel to the next

and permits it to boil at low temperature.

Evaporation is done in two stages. The first in an evaporator station to

concentrate the solution and second in a vacuum pan is to crystallize the sugar from

solution. First step is done generally in multiple effect evaporators for improved thermal


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economy; and second is performed in single effect vessels e.g vacuum pans to control

the batch crystallization. The evaporator station in raw sugar manufacture typically

removes 90% of the water from the clarified juice from about 15 brix to about 65-70 brix.

There are different terms, which are used here in factory for evaporators, bodies andquads are more common. When four bodies are combined then it is called quad.The

triple, quintuple-effect evaporators are also used but quadruple-effect type is more

common. In this one pound of steam evaporates four pounds of water.

Juice from clarifiers goes to the vapor cell. Vapor cell is used before each quad for

steam economy . There are three vapors cells. The exhaust Steam is applied on vapor

cell and temperature is raised to about 110oC.Then juice goes to evaporator No.1. Its

temperature is kept at 110o

C. The Vapors of 1st body are used in 2nd

body as heating

media and hence there is no use of steam in body No.2.

The temperature of 3rd and 4th body is 85oC and 60o C respectively. Creating vacuum of

60-65 mm Hg decreases the temperature of 4th body. The 4th evaporator is attached

with condenser, which removes condensable gases through jet and condenses the

vapors by spraying the cold water. Syrup of 60 to 65 brix is obtained from the 4 th

evaporator. Then this syrup is sent to syrup tanks called syrup storage tank. The

cleaning of evaporator is necessary to maintain the brix. After 12-15 days every

evaporator has to be cleaned.


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Juice Temperature Brix Pressure

Clear juice 89 C 15 1 kg / cm

Vapour cell 104 C 22 0.33 kg / cm

Evaporator 1 103 C 35 0.29 kg / cm

Evaporator 2 93 C 38 0.11 kg / cm

Evaporator 3 89 0C 41 -28.13 kg / cm2

Evaporator 4 58 C 65 -53.63 kg / cm


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Syrup storage tank:

Syrup from syrup storage tanks is sent to syrup storage tank,from there it is

sent to raw crystallization pans.

Raw crystallization:

Syrup from evaporators is pumped to a vacuum pan in which it is

evaporated to supersaturation in order to cause sugar to crystallize .This is done in

pans which may be either Batch pan or Continuous vacuum pans

The function pan is to produce satisfactory sugar crystals from syrup. The concentration

of feed used in pans is usually 60-65 brix and may reach to 74 here.

These pans are specified for different boiling of different massecuite and seeds.

Batch Pan # 1,2 Seed for A massecuite, Continuous Pan # 1,2 for A-massecuite ,Batch

Pan # 3 seed for c-massecuite, Continuous pan # 3 for c- massecuite and Batch Pan

# 4,5,6,7,8 for B-massecuite

Massecuite = molasses + crystals

Crystallization is done through following pans that work mutually.

A pan B pan C pan


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A pan:

Syrup from syrup storage tank is taken into A pan. Through vacuum

boiling brix level is increased to 70, where crystals start to form. Vacuum boiling(pressure 76 mm Hg) is done at 60C. Now A massecuite is done by the addition of B

seed( added up to 1/4 or 1/8 of total tank volume). Here A grain (brix 90-95) is formed

that is further transfer to continuous vacuum pans continuous vacuum pans consists of

12 parts where syrup and A grain is brought in contact to each other in tubes and

steam is applied as heating media.

The product from continous pans is A massecuite and that is dropped into A

crystallizer by vacuum breakage. Sugar is formed within three to four hours.

This material is further transferred to A centrifugals where high. In centrifugals

speed is applied separate grain of sugar and molasses comes out. These machines

work mechanically, centrifugal force works when basket of the centrifugal rotates with

high speed i.e. 1600 rpm.


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There are 10 Nos. of A-centrifugals, 9 Nos. of B centrifugals, 8 Nos. of C

centrifugals. From the centrifugation of massecuite A, A melt, A heavy and A wash are

obtained. Raw melt is sent for clarification while A heavy and A wash are brought into B

pans for preparation of massecuite B.

B Pan:

There are five nos. of B pans in SML. Physical parameters are same as that

is pan A. Here B massecuite is formed which is dropped into B crystallizer.

Centrifugation of massecuite gives B seed and B heavy.


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First of all B seed that is used for A massecuite is prepared by slurry ( crystals +

isopropyl alcohol) and syrup. Isopropyl alcohol is added for proper size of grains.

C Pan:

There is a single C pan in SML. Here C massecuite is prepared from B

heavy taken from B pans and slurry. Here C grains are formed that are than dropped to

C continuous pan where syrup is added and product is than sent to vertical crystallizers(

two in numbers) then it is sent to cassettes (four in numbers)where temperature is

dropped to 40C which is best temp. For crystallization.

Then it is sent to re-heaters (four in numbers) The purpose of re-heaters is to

increase the temp. of massecuite to such a level suitable for centrifugation.

Centrifugation (single curing centrifuges) of massecuite C gives C seed along with final

molasses. This final molasses is sent to distillery for production of alcohol. C seed is

sent to double curing centrifuges from where we get C Light (purity 56 to 58) and C

seed that is used for preparation of soft sugar.


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Sugar Refining:

The raw sugar produced in industry as described in preceding section is LIGHT

BROWN in color and contains 98% sucrose .In order for it to be competitive formarketplace, it is necessary to bring about level of sucrose to 99.9% to make it white.

There are four routes for production of white sugar from sugar cane or raw cane

sugar. (1): traditional plantation white , obtained directly from sugar juice with settling

clarification and sulfitation. (2): improved plantation white with carbonation and

sulfitation. (3): refined white, from a white end refinery attached to raw sugar factory,

involving remelting raw sugar and refinery classification and decolorizing process; and

(4) refined white, refinery not incorporated into raw sugar factory.

Phosphitation Process:

A-melt which is the final product of the raw process is further transferred for melt

clarification. The process involves following steps:

Buffer tank:

Raw melt goes into buffer tank. Its purpose is to store the raw melt. The

capacity of buffer tank is 65 cubic meter.

Supply tank:

Raw melt from buffer tank comes into supply tank situated at ground flour.


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Liquor Heaters:

Liquor from supply tank is sent to liquor heaters for heating up to 80 to 85C

that is suitable for purification. Melt is heated so that it may be reacted efficiently and toget optimum Condition.Juice heating temperature 80 - 850C

Reaction tank:

After heating the product is taken into reaction tank. In reaction tank following

chemicals are added:

Phosphoric acid (300-400 ppm)

Talofloc : It is used as decolorizing agent

Talofloat: It is used to float the ppt. sludge, colloidal solution so that it can easilyremoved from the upper surface.

Lime Socrates: To maintain the pH of the raw melt.


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Telo Clarifiers:

From reaction tank the liquor comes in telo clarifiers. Due to the addition of

low molecular weight coagulants (Taloflot), the mud floats on the surface of liquor. Here

mud is collected with the help of scrappers and sent to vacuum filters. Liquor is

collected into liquor tank and sent for sulphitation.


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Sulfitation/sulfur tank:

Sulphitation is an eminent process done to decolorize the

liquor. For this purpose liquor is taken in a tank and SO2 is passed from the bottom ofthis tank. SO2 is removed from top of tower. Sulphur dioxide is passed through clearliquor to give brightness to liquor After sulphitation liquor is collected into smear tankand then passes through pressure filters with the help of pumps.

Filtration:

The liquor from phosphatation/ carbonation/ sulphitation clarifiers

contain small amount of finely dispersed particulate matter that require filtration forremoval . This process is done in the pressure filters.

Pressure filters:

There are eight pressure filters in SML, four are big and four are small. Small press.

Filters have 48 plates and 24 out let and large press. Filters have 36 plates and 24 out


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let. Here small dust particles are removed and clear liquor is obtained. Pressure upto 1-

2 kg / cm2.

Deep Bed Filters:

Liquor from vacuum filters is sent to deep bed filters where layers of different sizesof stones are applied for further filtration. Fine liquor is dropped from top and movestowards bottom. There are 4 large containers for this purpose and each contain threedifferent layers of different materials.

i. Carbonii. Sandiii. Small stones

All these three materials are so stable that even concentrated acids andbase have No effect on them. It is used to remove the dust particles as well as other

small particles In the liquor. There are layers of different sized small stones of 3mm,6mm, 12mm and 18mm.


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Decolourization:

The filtered clarified liquor is a clear, dark brown liquid having solid contents

b/w 55 to65 Brix, a pH of 6.7 to 7.2 and temperature b/w 65-----85oc. At this stage certain

decolorizing agents are added to remove colour such as charcoal ,bone char , ion

exchange resins etc and this send for refine crystallization and centrifugation in the

refine pans and centrifugals which are discussed as next topic .

Refine crystallization and centrifugation:

Clear liquor obtained after melt clarification is brought into refinery pans

for final crystallization. There are nine nos. refinery pans in SML.First of all massecuite is drawn from refinery crystallizer at 200 rpm. Then this

massecuite is washed with hot water coming from nozzles. Water comes out for few

seconds. The purpose of washing is to wash the sugar and to make it white. When hot

water stops, then steam comes from the same nozzle for few seconds. The purpose of

this steaming is to dry the sugar. Centrifugal rotates with high speed almost to 1600

rpm. Then machine starts to stop with low speed. It rotates with 50rpm. Then centrifugal

is discharged by dropping the sugar into the hopper. In refinery centrifugal we can refine

1500 kg sugar at once.

Packaging and storing of refined granulated sugar:

In recent decades, there have been significant changes in

the methods of handling refined sugar as it leaves the dryer. Bulk delivery of refined

granulated sugar to customers has made it necessary for the refiner to store finished

products in bulk rather than in bags .Granulated sugar remains free flowing for a long

period of time if it is CONDITIONED as conditioning reduces the handling ,

packaging and storing problems resulting from caking.Conditioning involves following

factors , including control of moisture contents , the temperature ,and grain size , as

well as good inventory management .


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References:

en.wikipedia.org/wiki/Cane_sugar_mill

www.essortment.com/process-making-sugar-419

kiranpalwasha.blogspot.com/.../some-videos-from- sugar-mill-process..

www.sugaraustralia.com.au/Industry.aspx?content= MillingBusiness

www05.abb.com/global/scot/...nsf/.../a-n- sugar_ph_sulfitation_a.pd

www.clarencetourism.com/media/docs/ sugarcane.pdf-Australia

http://www.acfa.com.au/index.php?option=com_k2&view=item&layout=item&id=100&Itemid=135

http://www.rudolphresearch.com/refractometers/how-to-choose/sugar.php

http://www.citehr.com/research-sugar-mill-process-page1.html?status=closed

://ethanolfacts.com.au/sugarprocess
http://www.essortment.com/process-making-sugar-419http://www.essortment.com/process-making-sugar-419http://www.essortment.com/process-making-sugar-419http://www.essortment.com/process-making-sugar-419http://www.essortment.com/process-making-sugar-419http://www.essortment.com/process-making-sugar-419http://www.sugaraustralia.com.au/Industry.aspx?content=MillingBusinesshttp://www.sugaraustralia.com.au/Industry.aspx?content=MillingBusinesshttp://www.sugaraustralia.com.au/Industry.aspx?content=MillingBusinesshttp://www.sugaraustralia.com.au/Industry.aspx?content=MillingBusinesshttp://www.sugaraustralia.com.au/Industry.aspx?content=MillingBusinesshttp://www.sugaraustralia.com.au/Industry.aspx?content=MillingBusinesshttp://www.acfa.com.au/index.php?option=com_k2&view=item&layout=item&id=100&Itemid=135http://www.rudolphresearch.com/refractometers/how-to-choose/sugar.phphttp://www.rudolphresearch.com/refractometers/how-to-choose/sugar.phphttp://www.citehr.com/research-sugar-mill-process-page1.html?status=closedhttp://www.citehr.com/research-sugar-mill-process-page1.html?status=closedhttp://ethanolfacts.com.au/sugarprocesshttp://ethanolfacts.com.au/sugarprocesshttp://www.citehr.com/research-sugar-mill-process-page1.html?status=closedhttp://www.rudolphresearch.com/refractometers/how-to-choose/sugar.phphttp://www.acfa.com.au/index.php?option=com_k2&view=item&layout=item&id=100&Itemid=135http://www.sugaraustralia.com.au/Industry.aspx?content=MillingBusinesshttp://www.essortment.com/process-making-sugar-419

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