crystal management at pan boiling station – is there room for improvement? by mian abdul shakoor...

CRYSTAL MANAGEMENT AT PAN CRYSTAL MANAGEMENT AT PAN BOILING STATION – IS THERE ROOM FOR BOILING STATION – IS THERE ROOM FOR

IMPROVEMENT?IMPROVEMENT?

ByBy

Mian Abdul ShakoorMian Abdul ShakoorProduction ManagerProduction Manager

Ranipur Sugar Mills LimitedRanipur Sugar Mills Limited

ABSTRACTABSTRACT The recommendations are addressed for molasses The recommendations are addressed for molasses

exhaustion keeping in view of equipment design and exhaustion keeping in view of equipment design and process parameters at each stage during pan boiling process parameters at each stage during pan boiling station. Equipment design focused on the flow pattern to station. Equipment design focused on the flow pattern to give the required retention time for crystal growth, mass give the required retention time for crystal growth, mass and heat transfer. Recommended process parameters for and heat transfer. Recommended process parameters for solid concentration, temperature, retention time, crystal solid concentration, temperature, retention time, crystal contents and crystal size distribution which are necessarily contents and crystal size distribution which are necessarily to improve the molasses exhaustion at each stage of the to improve the molasses exhaustion at each stage of the low grade station. Cane quality and a good performance of low grade station. Cane quality and a good performance of each process stage prior to the pan station, are each process stage prior to the pan station, are fundamentals to maximize sugar recovery. These fundamentals to maximize sugar recovery. These informations are the basis to define the required materials informations are the basis to define the required materials and methods, and to analyze the results of this and methods, and to analyze the results of this presentation.presentation.

INTRODUCTIONINTRODUCTION The art of pan boiling is difficult and requires much skill and The art of pan boiling is difficult and requires much skill and

experience. Dr. Classen and Dr.J.G Theim have no doubt given a experience. Dr. Classen and Dr.J.G Theim have no doubt given a scientific approach to the subject as a result of which, the art of pan scientific approach to the subject as a result of which, the art of pan boiling has become easier to follow more correctly. Still it requires skill boiling has become easier to follow more correctly. Still it requires skill and experience on the part of pan boiler to make crystals of required, and experience on the part of pan boiler to make crystals of required, numbers and of pre-determined size, free from false grain and numbers and of pre-determined size, free from false grain and conglomerates or twinned grains.conglomerates or twinned grains.

Besides the skill and experience of pan boiler, so many factors impart Besides the skill and experience of pan boiler, so many factors impart their effect on sugar loss in final molasses of any sugar factory. their effect on sugar loss in final molasses of any sugar factory. Amongst them one major factor is characteristics of the crystals. Amongst them one major factor is characteristics of the crystals. During sugar boiling grains should be of right numbers and of uniform During sugar boiling grains should be of right numbers and of uniform size free from false grains and conglomerates. The crystal contents or size free from false grains and conglomerates. The crystal contents or grain contents of Massecuite should be such as to give maximum grain contents of Massecuite should be such as to give maximum crystal surface for sugar adsorption from the mother liquor. The fact of crystal surface for sugar adsorption from the mother liquor. The fact of size of the crystal (fine coarse or bold) is immaterial; the important size of the crystal (fine coarse or bold) is immaterial; the important thing is the uniformity of the grains. Trouble arises when grains of thing is the uniformity of the grains. Trouble arises when grains of different dimensions (coarse and fine) occur together, as irregular different dimensions (coarse and fine) occur together, as irregular grain prevents the mother liqour to pass exterior during purging.grain prevents the mother liqour to pass exterior during purging.

HOW DO GET GOOD QUALITY CRYSTALS AT PAN HOW DO GET GOOD QUALITY CRYSTALS AT PAN STATION DURING BOILING.STATION DURING BOILING.

A.A. Compositional FactorCompositional Factor

1.1. Solubility of sucrose and Degree of super saturation.Solubility of sucrose and Degree of super saturation.2.2. ViscosityViscosity3.3. Crystal contents, Crystal surface area and Size of crystals.Crystal contents, Crystal surface area and Size of crystals.4.4. Effect of Non sugars, Reducing sugars and RS/Ash ratio on crystal Effect of Non sugars, Reducing sugars and RS/Ash ratio on crystal

formation and exhaustibility of molasses.formation and exhaustibility of molasses.

B.B. Operational factorsOperational factors

1.1. Boiling schemeBoiling scheme2.2. Cooling of C-MassecuiteCooling of C-Massecuite3.3. Re-heating of final cooled massecuiteRe-heating of final cooled massecuite4.4. Circulation in PanCirculation in Pan5.5. Selection of equipment of proper design and capacity.Selection of equipment of proper design and capacity.6.6. Temperature of Massecuite and Heating media (steam/vapour)Temperature of Massecuite and Heating media (steam/vapour)7.7. Utilization of Jigger Steam in continuous PanUtilization of Jigger Steam in continuous Pan

1.1. Solubility of sucrose and Degree of Solubility of sucrose and Degree of super saturationsuper saturation

The amount of sucrose dissolve per unit part of solvent (pure water) is The amount of sucrose dissolve per unit part of solvent (pure water) is called solubility at a given temperature.called solubility at a given temperature.

Non sugars increases the solubility of sucrose.Non sugars increases the solubility of sucrose.

The ratio of sucrose present in the supersaturated solution at a given The ratio of sucrose present in the supersaturated solution at a given temperature and the sucrose present in saturated solution at the same temperature and the sucrose present in saturated solution at the same temperature is called degree of super saturation or co-efficient of super temperature is called degree of super saturation or co-efficient of super saturation.saturation.

Co-efficient of super saturation = Co-efficient of super saturation = Sucrose % water in supersaturated solutionSucrose % water in supersaturated solution Sucrose% water in saturated solutionSucrose% water in saturated solution

For exampleFor exampleat temperature 28ºC, 100 parts water contains 72 parts of sucrose to make it at temperature 28ºC, 100 parts water contains 72 parts of sucrose to make it supersaturated, and 68 parts of sucrose to make it saturated, then the co-supersaturated, and 68 parts of sucrose to make it saturated, then the co-efficient will beefficient will beCo-efficient of super saturationCo-efficient of super saturation = 72/68 = 72/68

= 1.05= 1.05

According to Classen’s TheoryAccording to Classen’s Theory

Co-efficient of super saturation value ranges 1.10 – 1.60Co-efficient of super saturation value ranges 1.10 – 1.60

seeding high purity solution like at refinery boiling co-efficient of super saturation is seeding high purity solution like at refinery boiling co-efficient of super saturation is 1.201.20

For shock seeding value of co-efficient is 1.30 - 1.40For shock seeding value of co-efficient is 1.30 - 1.40

For spontaneous (waiting method) seed formation the required value of co-efficient For spontaneous (waiting method) seed formation the required value of co-efficient of super saturation is 1.60. of super saturation is 1.60.

Boiling zones based on degree of super saturation:-Boiling zones based on degree of super saturation:-

Metstable zoneMetstable zone nearest to super saturation, existing crystals increases in size, nearest to super saturation, existing crystals increases in size, no new crystal grows.no new crystal grows.

Intermediate zoneIntermediate zone new crystals can grow in the presence of existing crystals.new crystals can grow in the presence of existing crystals.

Labile Zone new crystals can grow in the absence of existing crystals.Labile Zone new crystals can grow in the absence of existing crystals.

2.2. ViscosityViscosity

The resistance produced by one layer of molecule of a liquid to the adjacent layer of The resistance produced by one layer of molecule of a liquid to the adjacent layer of molecules during its movement is called viscosity.molecules during its movement is called viscosity.

One poise being a force required to two parallel surface of 1 cm² having distance of 1cm, One poise being a force required to two parallel surface of 1 cm² having distance of 1cm, apart to slide past each other at a velocity of one cm/sec. apart to slide past each other at a velocity of one cm/sec.

Non sugars, gums, waxes colloidal matters enhances viscosity.Non sugars, gums, waxes colloidal matters enhances viscosity.

In general it may be stated that:-In general it may be stated that:-

For a particular Massecuite higher the brix, higher will be the viscosity.For a particular Massecuite higher the brix, higher will be the viscosity. Viscosity of molasses is doubled with the increase in total solids by 0.80%Viscosity of molasses is doubled with the increase in total solids by 0.80% Rising the temp: lower down the viscosity. Minimum viscosity observed at saturation Rising the temp: lower down the viscosity. Minimum viscosity observed at saturation

temperature that is 55Cº.temperature that is 55Cº. Viscosity of molasses reduced by 50% by the rise in temp: by 5Cº.Viscosity of molasses reduced by 50% by the rise in temp: by 5Cº.

Viscosities limit the workability of Massecuite in pans and crystallizers and influence the Viscosities limit the workability of Massecuite in pans and crystallizers and influence the formation of conglomerates, distorted grain and caking crystals.formation of conglomerates, distorted grain and caking crystals.

surface active chemicals ( visc-aid, sepran A-30, Hodage CB-6) @ 2kg/60 tons strike. surface active chemicals ( visc-aid, sepran A-30, Hodage CB-6) @ 2kg/60 tons strike.

3.3. Crystal contents, Crystal surface areaCrystal contents, Crystal surface areaand Size of crystals.and Size of crystals.

Crystal surface area is determined from crystal contents and crystal size.Crystal surface area is determined from crystal contents and crystal size.

Smaller sized crystals have greater surface area then larger sized crystals.Smaller sized crystals have greater surface area then larger sized crystals.ButBut

• Smaller sized crystal may pass through the working screens of centrifugals, causing high Smaller sized crystal may pass through the working screens of centrifugals, causing high purity of final molasses.purity of final molasses.

• Purging capacity decreased and recirculation of molasses increasedPurging capacity decreased and recirculation of molasses increased

For low grade massecuite recommended crystal sizes are:-For low grade massecuite recommended crystal sizes are:-

• for C Massecuite grains ((C Massecuite seed) are between 180 and 200 micronsfor C Massecuite grains ((C Massecuite seed) are between 180 and 200 microns • for C-massecuite leaving the pan are between 250 and 300 microns for C-massecuite leaving the pan are between 250 and 300 microns

• for C Massecuite leaving the C crystallizers are between 300 and 350 microns.for C Massecuite leaving the C crystallizers are between 300 and 350 microns. • Crystal width has to be 1.50 to 2.0 times larger than the width of screen slot.Crystal width has to be 1.50 to 2.0 times larger than the width of screen slot.

• Slot size of working liner for low grade massecuite 0.04mm – 0.06mm(40 and 60 microns).Slot size of working liner for low grade massecuite 0.04mm – 0.06mm(40 and 60 microns).

• Minimum crystal width is recommended as 120 micron Minimum crystal width is recommended as 120 micron

• Crystal size of slurry is maintained up to 5 micron. Crystal size of slurry is maintained up to 5 micron.

impact of crystal size on purity of impact of crystal size on purity of final molasses final molasses

Uniformity of CrystalUniformity of Crystal Un uniform crystals causesUn uniform crystals causes

• Reduced pore volume of crystals.Reduced pore volume of crystals.• Reduced molasses drainage during purging.Reduced molasses drainage during purging.

Uniform crystals are produced:-Uniform crystals are produced:-

• Constant production rate in case of batch pans and continuous pans.Constant production rate in case of batch pans and continuous pans.• regular injection of seed (grain) in continuous pan.regular injection of seed (grain) in continuous pan.• Seed/massecuite ratio is to be maintained by crystal size distribution (CSD) Seed/massecuite ratio is to be maintained by crystal size distribution (CSD)

analytical tool.analytical tool.• 35% - 40% grain is to be injected in continuous pan.35% - 40% grain is to be injected in continuous pan.

The crystal contents of various massecuite are to be:-The crystal contents of various massecuite are to be:-

For A-MassecuiteFor A-Massecuite == 60%60% For B-MassecuiteFor B-Massecuite == 50%50% For C-MassecuiteFor C-Massecuite == 40%40% For Refine MassecuiteFor Refine Massecuite == 62% - 65%62% - 65%

3.1 3.1 Slurry preparationSlurry preparation

Slurry /massecuite ratio is to be determined (can be done by experience)Slurry /massecuite ratio is to be determined (can be done by experience)

EXPERIENCE AT RANIPUR SUGAR MILLS.EXPERIENCE AT RANIPUR SUGAR MILLS.

• Conventional slurry machine contains porclain balls of various sizes, was Conventional slurry machine contains porclain balls of various sizes, was used up to 2008 – 2009.used up to 2008 – 2009.

• Design of slurry machine revisited.Design of slurry machine revisited.

• Porclain balls were replaced with SS rods.Porclain balls were replaced with SS rods.

• Slurry prepared in myth elated spirit.Slurry prepared in myth elated spirit.

• Slurry preparation time was maintained at 48 hours.Slurry preparation time was maintained at 48 hours.

• Slurry was injected at the rate of 2kg/6M³ footing material.Slurry was injected at the rate of 2kg/6M³ footing material.

Impact of slurry on Final Molasses PurityImpact of slurry on Final Molasses Purity

S. S. NoNo

SeasonSeason Purity Purity of FMof FM

Type of slurry machine usedType of slurry machine used

1.1. 2008 – 20092008 – 2009 33.73633.736 Conventional machine with porclain ballsConventional machine with porclain balls

2.2. 2009 – 20102009 – 2010 32.86532.865 Slurry machine with SS rodsSlurry machine with SS rods

3.3. 2010 – 20112010 – 2011 31.81131.811 -do--do-

4.4. 2011 – 20122011 – 2012 31.77931.779 -do--do-

3.2 3.2 Routine measurement of NutschRoutine measurement of Nutsch

Molasses Molasses

Routine monitoring through Nutsch pump Routine monitoring through Nutsch pump is to be conducted.is to be conducted.

60 to 75%of the purity drop is gained in 60 to 75%of the purity drop is gained in the pan.the pan.

purity rise after the re-heater must be purity rise after the re-heater must be zero and some times can be negative zero and some times can be negative

4.4. Effect of Non sugars, Reducing sugars Effect of Non sugars, Reducing sugars and RS/Ash ratio on crystal formation and RS/Ash ratio on crystal formation and exhaustibility of molasses.and exhaustibility of molasses.

4.1 4.1 Non SugarsNon Sugars Non sugar increases the solubility of of sucrose in Non sugar increases the solubility of of sucrose in

molasses.molasses.

Chlorides and carbonates decreases the rate of Chlorides and carbonates decreases the rate of crystallization.crystallization.

Sulphates slightly increases the rate of crystallization.Sulphates slightly increases the rate of crystallization.

Research shows that 5.5% crystallization rate is decreased Research shows that 5.5% crystallization rate is decreased in the presence of gummy matters and waxes with in the presence of gummy matters and waxes with concentration 0.50% concentration 0.50%

4.1.14.1.1 Sources of non sugars inSources of non sugars incane juice.cane juice.

a.a. With cane juiceWith cane juice

b.b. Mills sanitation and Process House Mills sanitation and Process House sanitationsanitation

c.c. Addition of raw water during processing Addition of raw water during processing of sugarof sugar

d.d. Usage of poor quality lime Usage of poor quality lime

4.1.1.a4.1.1.a With cane juiceWith cane juice

The constituents of normal cane juice fall with in the following limits.The constituents of normal cane juice fall with in the following limits.WaterWater 75-88%75-88%SucroseSucrose 10 – 21 %10 – 21 %Reducing sugarsReducing sugars 0.25 – 0.35%0.25 – 0.35%Organic matters other than sugarsOrganic matters other than sugars 0.5 – 1.00 %0.5 – 1.00 %Inorganic compoundsInorganic compounds 0.2 – 0.6%0.2 – 0.6%Nitrogenous bodiesNitrogenous bodies 0.5 – 1.00%0.5 – 1.00%

Immature and overripe cane contains more organic acids.Immature and overripe cane contains more organic acids.

Caused in production more scale and molasses % cane.Caused in production more scale and molasses % cane.

Staled cane or frosted cane produces juice with lower purity, less sucrose, Staled cane or frosted cane produces juice with lower purity, less sucrose, high titrateable acidity and abnormal amount of dextran or gumshigh titrateable acidity and abnormal amount of dextran or gums

• effects adversely on molasses exhaustibility.effects adversely on molasses exhaustibility.

Cultural practices, varietals differences, soil variations, planning and Cultural practices, varietals differences, soil variations, planning and harvesting periods influences on clarification and subsequent exhaustion of harvesting periods influences on clarification and subsequent exhaustion of molasses. molasses.

4.1.1.b.4.1.1.b. Mills and Process HouseMills and Process Housesanitationsanitation

Leuconostoc BacteriaLeuconostoc Bacteria enter in the cane:-enter in the cane:-

• At farm into the exposed tissues caused by mechanical harvesting.At farm into the exposed tissues caused by mechanical harvesting. • At site in prepared cane, cutting , burning, freezing and via disease and pests.At site in prepared cane, cutting , burning, freezing and via disease and pests. • Polymer of glucose “Dextran” is produced after conversion of sucrose.Polymer of glucose “Dextran” is produced after conversion of sucrose.

• Dextran has needle shaped crystals.Dextran has needle shaped crystals.

Effect of Dextran:-Effect of Dextran:-

• Increases the viscosity at various stages of process house.Increases the viscosity at various stages of process house.

• Increases the loss of sucrose in the final molasses by entangling recoverable sucrose.Increases the loss of sucrose in the final molasses by entangling recoverable sucrose.• • Slots of centrifugal screens get chocked due to its crystal shape.Slots of centrifugal screens get chocked due to its crystal shape.

• Every 300 ppm dextran in syrup increases 1% in molasses purity.Every 300 ppm dextran in syrup increases 1% in molasses purity.

• False Pol reading during analysis of juice samples in the laboratory.False Pol reading during analysis of juice samples in the laboratory.

How Dextran entangles sucrose How Dextran entangles sucrose crystals.crystals.

How to avoid dextran formation.How to avoid dextran formation.

Dextran formation can be avoided Dextran formation can be avoided

• Bleaching powder (25 Kgs/shift) at mills house.Bleaching powder (25 Kgs/shift) at mills house.

• Pencillin 4 lac in imbibition water tank @ 3.50 grams /shift.Pencillin 4 lac in imbibition water tank @ 3.50 grams /shift.

• Pencillin 4 lac in defecation retention tank @ 3.50 grams /shift.Pencillin 4 lac in defecation retention tank @ 3.50 grams /shift.

• Pencillin 4 lac in raw sugar remelter @ 3.50 grams /shift.Pencillin 4 lac in raw sugar remelter @ 3.50 grams /shift.

• Pencillin 4 lac in A-H storage tank @ 3.50 grams /shift.Pencillin 4 lac in A-H storage tank @ 3.50 grams /shift.

• Pencillin 4 lac in B-H storage tank @ 3.50 grams /shift.Pencillin 4 lac in B-H storage tank @ 3.50 grams /shift.

• Pencillin 4 lac in syrup storage tank @ 3.50 grams /shift.Pencillin 4 lac in syrup storage tank @ 3.50 grams /shift.

4.1.1.c4.1.1.c Addition of raw water during Addition of raw water during processing of sugarprocessing of sugar

Use of Raw water at mills house and at any stage Use of Raw water at mills house and at any stage of process house causes:-of process house causes:-

Increase in increase in inorganic salts in the form of TDSIncrease in increase in inorganic salts in the form of TDS

Has adverse effect on molasses exhaustibility and scale Has adverse effect on molasses exhaustibility and scale formation on heating surface area of heat changers.formation on heating surface area of heat changers.

4.1.1.d4.1.1.d Usage of poor qualityUsage of poor qualitylimelime

Good quality lime containsGood quality lime contains

CaO CaO @ 92%@ 92% Insoluble mattersInsoluble matters @ 2%@ 2%

Poor quality of lime caused:-Poor quality of lime caused:-

High percentage of silica in lime retards the settling of juice in juice clarifier, thus poor High percentage of silica in lime retards the settling of juice in juice clarifier, thus poor clarification effect is achieved.clarification effect is achieved.

High percentage of magnesia retards filtration and rate of settling again poor High percentage of magnesia retards filtration and rate of settling again poor clarification effect.clarification effect.

Darkening in juice.Darkening in juice.

Increases gummy substances.Increases gummy substances.

Increases ashes%.Increases ashes%.

Adverse effect on exhaustibility of final molasses. Adverse effect on exhaustibility of final molasses.

4.2 4.2 Reducing Sugars andReducing Sugars andRS/Ash ratioRS/Ash ratio

RS decreases solubility of sucrose in mother RS decreases solubility of sucrose in mother liqour.liqour.

Crystallization becomes easy.Crystallization becomes easy.TT RS/100gms of waterRS/100gms of water Solubility of Solubility of

sucrose/100 gms of sucrose/100 gms of waterwater

50ºC50ºC

00 260260

5050 242242

100100 222222

150150 216216

200200 208208

RS/Ash RatioRS/Ash Ratio

Higher value of ratio, lesser will be Higher value of ratio, lesser will be sucrose in final molasses.sucrose in final molasses.

Ratio varies from 0.90 to 2.50 in different Ratio varies from 0.90 to 2.50 in different regions.regions.

beet molasses contains high ashes and beet molasses contains high ashes and very low RS, thus high loss of sugar in very low RS, thus high loss of sugar in final molasses.final molasses.

B.B. Operational Parameters Operational Parameters

1.1. Boiling SchemeBoiling Scheme

Conventional Boiling scheme:-Conventional Boiling scheme:-

Sugar mills are using DRP,DCS process.Sugar mills are using DRP,DCS process.

It InvolvesIt Involves

• three boiling system on Raw side (to minimize the loss of sugar in final molasses with least three boiling system on Raw side (to minimize the loss of sugar in final molasses with least recirculation.recirculation.

• Refine boiling (To produce good quality of white refines sugar and least recirculation.) .Refine boiling (To produce good quality of white refines sugar and least recirculation.) .

Blended boiling system and version boiling at refine massecuite boiling.Blended boiling system and version boiling at refine massecuite boiling.

Rejected run off (pty:92-93) is sent back to Raw side in A-massecuite.Rejected run off (pty:92-93) is sent back to Raw side in A-massecuite.

• In version boiling scheme rejected Run Off is 0.9 – 1.10%caneIn version boiling scheme rejected Run Off is 0.9 – 1.10%cane

• In blended boiling scheme rejected run off is 3.10 – 3.50 % caneIn blended boiling scheme rejected run off is 3.10 – 3.50 % cane

Massecuite production remained as:-Massecuite production remained as:- A-MassecuiteA-Massecuite == 23% - 25% cane23% - 25% cane B-MassecuiteB-Massecuite == 14% - 15% cane14% - 15% cane C-MassecuiteC-Massecuite == 9% - 10% cane9% - 10% cane R-MassecuiteR-Massecuite == 20% - 22% cane20% - 22% cane Molasses productionMolasses production == 4.50% - 5.25% cane4.50% - 5.25% cane

S.S.

No.No. ParticularParticular

R-1 Material contribution R-1 Material contribution in Total Refine Material in Total Refine Material

R-2Material contribution R-2Material contribution in Total Refine Materialin Total Refine Material

R-3 Material contribution R-3 Material contribution in Total Refine Material in Total Refine Material

R-1R-1

Mass:Mass:

RO1RO1 R-1R-1

SugarSugar

R-2R-2

Mass:Mass:

RO2RO2 R-2R-2

SugarSugar

R-3R-3

Mass:Mass:

RO3RO3 R-3R-3

SugarSugar

1.1.

Blended Blended BoilingBoiling 44 %44 % 44 %44 % 43 %43 % 32 %32 % 31 %31 % 33 %33 % 24 %24 % 25 %25 % 24 %24 %

2.2.

Version Version BoilingBoiling 50 %50 % 54 %54 % 52 %52 % 37 %37 % 39 %39 % 37 %37 % 13 %13 % 7 %7 % 11 %11 %

Comparison of Refine Materials at Version and Blended Comparison of Refine Materials at Version and Blended boiling scheme.boiling scheme.

a.a. Version Boiling Refine Massecuite productionVersion Boiling Refine Massecuite production == 4 : 2 : 14 : 2 : 1

b.b. Blended Boiling Refine Massecuite ProductionBlended Boiling Refine Massecuite Production == 2 : 1 : 12 : 1 : 1

Experience of Ranipur Sugar MillsExperience of Ranipur Sugar Mills Version boiling scheme adopted at Refine boiling.Version boiling scheme adopted at Refine boiling.

• To produce maximum quantity of R1 sugar and to minimize the To produce maximum quantity of R1 sugar and to minimize the recirculation.recirculation.

Adopted four strike boiling system on raw side i,e besides the Adopted four strike boiling system on raw side i,e besides the conventional A,B ,C massecuite , A-1 massecuite boiling.conventional A,B ,C massecuite , A-1 massecuite boiling.

A-1 massecuite is boiled by taking 75% of B-seed and rejected run off. A-1 massecuite is boiled by taking 75% of B-seed and rejected run off. A-1 sugar is mixed with A-sugar remelt and A-Light (pty: 83- 84) is return A-1 sugar is mixed with A-sugar remelt and A-Light (pty: 83- 84) is return

back to A-Massecuite in footing.back to A-Massecuite in footing. Massecuite Production remained as underMassecuite Production remained as under

A-MassecuiteA-Massecuite == 20% - 21% (including A-1 20% - 21% (including A-1

Massecuite) Massecuite) B-MassecuiteB-Massecuite == 11% - 12%11% - 12% C-MassecuiteC-Massecuite == 7.50% - 8%7.50% - 8% Final MolassesFinal Molasses == 3.90% - 4.50% 3.90% - 4.50%

Loss of sugar in Final MolassesLoss of sugar in Final Molasses

S.NoS.No SeasonSeason Loss of Loss of sugar F.Msugar F.M

RemarksRemarks

1.1. 2008-20092008-2009 1.4521.452 Three strike Boiling scheme on raw side and Three strike Boiling scheme on raw side and cut boiling scheme at refine boiling cut boiling scheme at refine boiling

2.2. 2009-20102009-2010 1.3531.353 Four strike boiling scheme on raw side and Four strike boiling scheme on raw side and version boiling scheme on refine massecuiteversion boiling scheme on refine massecuite

3.3. 2010-20112010-2011 1.25041.2504 -do--do-

4.4. 2011-20122011-2012 1.26671.2667 -do--do-

Successful story at Pan Boiling in Ranipur Sugar Mills (A-1 and A-Massecuite Boiling Scheme)

A-1 Massecuite(Pty: 92 – 93)

A- Light(Pty: 84-85)

A- Sugar(Pty: 98 -98 .50)

RO3Pty:(93-94)

B-SeedPty:(94-95)

A- Mass: (Double)(Pty: 85-87)

A- Mass:(Pty: 84-85)

A- Mass:(Pty: 84-85)

SyrupPty:(82-84)

C-SeedPty:(93-94)

B-SeedPty:(94-95)

A- H(Pty: 62-64)

A- Sugar(Pty: +97 .50)

B-Boiling Scheme

B-Mass (Double)(Pty: 76 – 77)

B-Mass(Pty: 71-72)

B-H(Pty: 42 -44)

A-HPty:(62-64)

C-SeedPty:(93-94)

B-Mass(Pty: 71-72)

A-H(Pty: 62 -64)

B-Sugar(Pty: 94 -95)

C-Massecuite Boiling Scheme Preparation of C-Grain

C-LightPty: (61-63)

SyrupPty: (82-84)

C.G Material (Baby Pan)Pty: (68-69)

C-CutPty: (54-55)

B-H(42-44)

C-Light

Preparation of C-Mass:

C-CutPty: (54-55)

C-Mass:Pty: (49-51)

C-Mass:Pty: (49-51)

B-H(42-44)

Refine Boiling scheme

R-1 Mass: R-1 Mass: R-1 Mass: R-1 Mass:

RO-1 RO-1 RO-1 RO-1

R-2 Mass: R-2 Mass:

RO-2 RO-2

R-3 Mass:

2.2. Cooling of C-MassecuiteCooling of C-Massecuite

C-Massecuites are cooled in the crystallizers to a C-Massecuites are cooled in the crystallizers to a final temperature as low as 35ºC to 38Cº.final temperature as low as 35ºC to 38Cº.

Cooling is to be conducted steadily, (cold water is to Cooling is to be conducted steadily, (cold water is to be circulated counter current to massecuite flow in be circulated counter current to massecuite flow in vertical crystallizer) vertical crystallizer)

Recommended cooling rate is 1.50 – 2ºC/hour.Recommended cooling rate is 1.50 – 2ºC/hour.

Minimum residence time is recommended as 48 Minimum residence time is recommended as 48 hours.hours.

3.3. Re-heating of final cooled Re-heating of final cooled massecuitemassecuite

C-massecuite should be re-heated to a temperature C-massecuite should be re-heated to a temperature lower than its saturation temperature (55ºC).lower than its saturation temperature (55ºC).

Re-heating is to be conducted steadily (Counter Re-heating is to be conducted steadily (Counter current flow of hot water to flow of massecuite).current flow of hot water to flow of massecuite).

Temp: of hot water is to be kept up to 62ºC – 65ºC.Temp: of hot water is to be kept up to 62ºC – 65ºC. Re-heater areas are approximately 4.50M²/TCH for Re-heater areas are approximately 4.50M²/TCH for

a ΔT (water to massecuite temperature difference) a ΔT (water to massecuite temperature difference) of 3ºC. of 3ºC.

4.4. Circulation in the PanCirculation in the Pan

Circulation of massecuite in the pan while Circulation of massecuite in the pan while boiling play a prime role in proper growth of boiling play a prime role in proper growth of crystals and exhaustion of molasses by:-crystals and exhaustion of molasses by:-

Prevent cake formation on the heating surface, which on Prevent cake formation on the heating surface, which on further heating convert into caramel.further heating convert into caramel.

Crystals are stationary, not free to move, so circulation helps Crystals are stationary, not free to move, so circulation helps them to grow.them to grow.

Proper mixing of molasses in side the pan held, thus good Proper mixing of molasses in side the pan held, thus good exhaustion of molasses occurs. exhaustion of molasses occurs.

Reasons for poor circulation of Reasons for poor circulation of massecuite in Pan.massecuite in Pan.

Design of the pan, specially the angle of the lower Design of the pan, specially the angle of the lower cone of pan i,e it should be 19º – 20º.cone of pan i,e it should be 19º – 20º.

Defective position/arrangement of feed pipe.Defective position/arrangement of feed pipe.

High viscosity High viscosity

How to improve circulationHow to improve circulation

By inducting mechanical circulator.By inducting mechanical circulator.

By blowing low pressure steam below By blowing low pressure steam below calendria.calendria.

5.5. Selection of the equipment of proper Selection of the equipment of proper design and capacity.design and capacity.

Experience shows that a lot of problem is being faced:-Experience shows that a lot of problem is being faced:-• after the induction of new equipments (Heaters, evaporators and continuous pans). after the induction of new equipments (Heaters, evaporators and continuous pans).

• The process house becomes unbalanced, in energy point of view.The process house becomes unbalanced, in energy point of view.

• Resulting in inadequate operation of equipments.Resulting in inadequate operation of equipments.

• Impacts on the sugar boiling adversely.Impacts on the sugar boiling adversely.

• Overall losses of the factory increased not only in terms of sucrose in final molasses Overall losses of the factory increased not only in terms of sucrose in final molasses but also consumption of fuel enhanced.but also consumption of fuel enhanced.

• In the end of the day higher management makes some unpopular decisions.In the end of the day higher management makes some unpopular decisions. ThereforeTherefore :- :-

• keen study of process house (energy balance, material balance) for each stage.keen study of process house (energy balance, material balance) for each stage.

• After that equipment is to be inducted of required capacity.After that equipment is to be inducted of required capacity.

Capacity of Continuous PanCapacity of Continuous Pan

Two Designs are available 68M³, 102M³.Two Designs are available 68M³, 102M³. Table by Fletcher and Stewart LimitedTable by Fletcher and Stewart Limited

Ave: Ave: Crushing Crushing

raterate

A-MassecuiteA-Massecuite B-MassecuiteB-Massecuite C-MassecuiteC-Massecuite

Cont: Pan Size (M³)Cont: Pan Size (M³) Cont: Pan Size (M³)Cont: Pan Size (M³) Cont: Pan Size (M³)Cont: Pan Size (M³)

8080 2222 3030 2020

100100 3030 3030 3030

125125 4040 4040 3030

150150 4040 5050 4040

200200 6060 6060 5050

250250 7070 7070 6060

300300 8080 9090 7070

350350 100100 100100 8080

400400 100100 120120 100100

450450 120120 2 x 602 x 60 100100

500500 2 x 702 x 70 2 x 702 x 70 120120

Alternate method to calculate capacity of Alternate method to calculate capacity of continuous pancontinuous pan

Capacity of continuous pan can also be calculated on various positions (A,B,C) by Capacity of continuous pan can also be calculated on various positions (A,B,C) by another alternate method. Which is as under:-another alternate method. Which is as under:-

Taking the example for continuous pan 68M³Taking the example for continuous pan 68M³

Capacity of pan Capacity of pan = = 68M³68M³== 68 x 1.5068 x 1.50== 102 Tons102 Tons

Nos. of chambersNos. of chambers == 12 Nos.12 Nos.Capacity of each chamberCapacity of each chamber == 8.50 Tons8.50 Tons

a.a. 68M³ continuous pan working for A-Massecuite boiling68M³ continuous pan working for A-Massecuite boilingNo. of syrup feedsNo. of syrup feeds == 06 Nos.06 Nos.Capacity of pan on A-MassecuiteCapacity of pan on A-Massecuite == 6 x 8.506 x 8.50

== 51 Tons/Hr51 Tons/Hrb.b. 68M³ continuous pan working for B-Massecuite boiling68M³ continuous pan working for B-Massecuite boiling

No. of A-H feedsNo. of A-H feeds == 04 Nos.04 Nos.Capacity of pan on A-MassecuiteCapacity of pan on A-Massecuite == 4 x 8.504 x 8.50

== 34 Tons/Hr34 Tons/Hrc.c. 68M³ continuous pan working for C-Massecuite boiling68M³ continuous pan working for C-Massecuite boiling

No. of B-H feedsNo. of B-H feeds == 02 Nos.02 Nos.Capacity of pan on A-MassecuiteCapacity of pan on A-Massecuite == 2 x 8.502 x 8.50

== 17 Tons/Hr17 Tons/Hr

6.6. Temperature of Massecuite Temperature of Massecuite

Solubility of sucrose is directly proportional to the temperature.Solubility of sucrose is directly proportional to the temperature. Low grade massecuite contains comparatively very less amount Low grade massecuite contains comparatively very less amount

of sucrose in the mother liquor which is to be crystal out during of sucrose in the mother liquor which is to be crystal out during boiling. boiling.

low temperature is to be kept during boiling of low grade low temperature is to be kept during boiling of low grade massecuite.massecuite.

Conventionally, the boiling temp: of pan remains + 60ºC.Conventionally, the boiling temp: of pan remains + 60ºC. recommended low grade massecuite is to be boiled at recommended low grade massecuite is to be boiled at

temperature 57ºC - 58ºC. temperature 57ºC - 58ºC.

Low boiling temperature can be Low boiling temperature can be achieved by, achieved by,

Increasing the vacuum in the shell of the pan.Increasing the vacuum in the shell of the pan.

• vacuum is to be raised up to 780 mm Hg by increasing vacuum is to be raised up to 780 mm Hg by increasing injection water quantity.injection water quantity.

Decreasing temperature of calendria in case of Decreasing temperature of calendria in case of continuous pan.continuous pan.

• Temperature of calendria can be decreased by,Temperature of calendria can be decreased by,

• Creating vacuum in the calendria up to 10 mm of Hg to 12 mm of Hg. This Creating vacuum in the calendria up to 10 mm of Hg to 12 mm of Hg. This vacuum corresponds to temp: 84ºC - 85ºC.vacuum corresponds to temp: 84ºC - 85ºC.

• Low grade Massecuites are to be boiled through 2nd or 3rd. vapours.Low grade Massecuites are to be boiled through 2nd or 3rd. vapours. • If there is no possibility to bleed 2nd. Or 3rd. vapours due to heating surfaces If there is no possibility to bleed 2nd. Or 3rd. vapours due to heating surfaces

at 3rd. or 2nd. Effects, then 1st. vapours are to be used under vacuum as at 3rd. or 2nd. Effects, then 1st. vapours are to be used under vacuum as discussed in option No.i. discussed in option No.i.

7.7. Utilization of Jigger Steam in Utilization of Jigger Steam in continuous Pan continuous Pan

Jigger steam is being used in continuous pan to opening of chocked Jigger steam is being used in continuous pan to opening of chocked compartment. compartment.

Pan boiler always kept open the jigger steam valve of all the compartments Pan boiler always kept open the jigger steam valve of all the compartments to increase the circulation of massecuite.to increase the circulation of massecuite.

Practice Practice

• dissolve the crystals specially in compartment No.1,2 and 3, where the size dissolve the crystals specially in compartment No.1,2 and 3, where the size of crystals are comparatively small.of crystals are comparatively small.

• Increases the temperature of massecuite which effects adversely on the Increases the temperature of massecuite which effects adversely on the exhaustion of the molasses.exhaustion of the molasses.

Low pressure and low temperature steam is to be used at jigger steam Low pressure and low temperature steam is to be used at jigger steam

instead of 4-bar steam. instead of 4-bar steam.

CONCLUSION AND RECOMMENDATIONSCONCLUSION AND RECOMMENDATIONS

1.1. To get maximum crystal surface available for adsorption To get maximum crystal surface available for adsorption of sugar, appropriate crystal contents are to be of sugar, appropriate crystal contents are to be maintained in massecuite boiling by uniform feeding of maintained in massecuite boiling by uniform feeding of grain in continuous pans @ 35-40%.grain in continuous pans @ 35-40%.

2.2. Conventional slurry machine is to be replaced with new Conventional slurry machine is to be replaced with new design of slurry machine.design of slurry machine.

3.3. Routine analysis of mother liquor through Nutsch pump Routine analysis of mother liquor through Nutsch pump either under pressure or under vacuum to be carried for either under pressure or under vacuum to be carried for improvement of pan boiling. improvement of pan boiling.

4.4. Process house is to be boiled on high purity. Following Process house is to be boiled on high purity. Following purities are to be kept at various stages.purities are to be kept at various stages.

a.a. A-Massecuite purityA-Massecuite purity == 84 – 8584 – 85 b.b. B-Massecuite purityB-Massecuite purity == 71 – 7271 – 72 c.c. C-Massecuite PurityC-Massecuite Purity == 49 - 5149 - 51 d.d. B-Seed PurityB-Seed Purity == 94 – 9594 – 95 e.e. C-Sugar PurityC-Sugar Purity == ± 80± 80 f.f. C-Seed PurityC-Seed Purity == 93 – 9493 – 94 g.g. A-H PurityA-H Purity == 62 – 6462 – 64 h.h. B-H PurityB-H Purity == 42 – 4442 – 44 i.i. C-Light purityC-Light purity == 61 - 6361 - 63


5.5. A-1 Boiling is to be inducted in three boiling scheme to minimize the shifting of Pol A-1 Boiling is to be inducted in three boiling scheme to minimize the shifting of Pol to raw side by using 75% B-seed and rejected run off. A-light molasses is to be use to raw side by using 75% B-seed and rejected run off. A-light molasses is to be use in footing rather in massecuite.in footing rather in massecuite.

6.6. Version boiling scheme is to be adopted for the production of white refined sugar, to Version boiling scheme is to be adopted for the production of white refined sugar, to minimize the recirculation of rejected run off.minimize the recirculation of rejected run off.

7.7. In Case of Batch pans, A massecuite is to be boil on cut system, in case of In Case of Batch pans, A massecuite is to be boil on cut system, in case of continuous pan, syrup is not to be feed more than 6 chambers for proper molasses continuous pan, syrup is not to be feed more than 6 chambers for proper molasses exhaustion and to get maximum massecuite : molasses purity drop. C-seed is to be exhaustion and to get maximum massecuite : molasses purity drop. C-seed is to be melted in footing and graining is to be conducted through B-seed. melted in footing and graining is to be conducted through B-seed. B-Massecuite boiling is to be conducted in case of batch pan on cut system. In case B-Massecuite boiling is to be conducted in case of batch pan on cut system. In case of Continuous Pan, A-H molasses is to be feed not more than 4 chambers.of Continuous Pan, A-H molasses is to be feed not more than 4 chambers.

In case of C-Massecuite boiling, Purity of C-Grain is to be kept 67 – 68, Whole C-In case of C-Massecuite boiling, Purity of C-Grain is to be kept 67 – 68, Whole C-light is to be used in C-Massecuite.light is to be used in C-Massecuite.

8.8. Addition of pencilline 4lac in various stages of process house is to be conducted, as Addition of pencilline 4lac in various stages of process house is to be conducted, as it has no adverse effect on sucrose contents of cane juice.it has no adverse effect on sucrose contents of cane juice.


99 After each three days, RS are to be checked at various stages of the house.After each three days, RS are to be checked at various stages of the house.

10.10. Before purging, the temperature of massecuite is to be raised up to 52ºC, temperature of hot Before purging, the temperature of massecuite is to be raised up to 52ºC, temperature of hot water is to be kept at 62ºC - 65ºC.water is to be kept at 62ºC - 65ºC.

11.11. Thorough study is to be conducted of pans for proper circulation of massecuite.Thorough study is to be conducted of pans for proper circulation of massecuite.

12.12. Keen study is to be carried out (energy balance, material balance) for each step of the Keen study is to be carried out (energy balance, material balance) for each step of the process, then induct equipment in process stream as per requirement.process, then induct equipment in process stream as per requirement.

13.13. Temperature of low grade massecuite is to be kept at 57ºC - 58ºC, while it is boiled.Temperature of low grade massecuite is to be kept at 57ºC - 58ºC, while it is boiled.

14.14. Priority is to be given for the usage of 2nd. Or 3rd. vapour for the boiling of low grade Priority is to be given for the usage of 2nd. Or 3rd. vapour for the boiling of low grade massecuite.massecuite.

15.15. Use 1st. vapour for boiling of low grade massecuite under vacuum, if necessary.Use 1st. vapour for boiling of low grade massecuite under vacuum, if necessary.

16.16. Jigger steam is to be used occasionally where it requires.Jigger steam is to be used occasionally where it requires.

17.17. Low pressure and low temperature (first vapour) is to be used instead of 4 bar steam. Low pressure and low temperature (first vapour) is to be used instead of 4 bar steam.


AcknowledgementAcknowledgement

First of all I am thankful to “Almighty First of all I am thankful to “Almighty Allah”, who made me able to conduct this Allah”, who made me able to conduct this presentation. I am also thankful to the presentation. I am also thankful to the Mian Nadeen Khalique, Executive Mian Nadeen Khalique, Executive Director RSM who give me permission to Director RSM who give me permission to present this paper. In the last but not present this paper. In the last but not least, I am thank full to Engr: Abdul Aziz least, I am thank full to Engr: Abdul Aziz Tahir (Technical Director), who always Tahir (Technical Director), who always gives me technical and moral guidance in gives me technical and moral guidance in each step of my life.each step of my life.

Thank YouThank You