improving mill extraction

IMPROVING MILL EXTRACTIONIMPROVING MILL EXTRACTION

BYBY

SUMIT BHATISUMIT BHATIDY. MANAGERDY. MANAGER--ENGG.ENGG.

TriveniTriveni Engineering & Industries Ltd.Engineering & Industries Ltd.Sugar UnitSugar Unit-- RamkolaRamkola, , KushinagarKushinagar (U.P.)(U.P.)

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OBJECTIVE OF MILLINGOBJECTIVE OF MILLING

nn Maximum possible extraction of sucroseMaximum possible extraction of sucrose

nn Minimum extraction of non sugarsMinimum extraction of non sugars

nn Minimum sucrose in final bagasseMinimum sucrose in final bagasse

nn Optimum moisture in final bagasseOptimum moisture in final bagasse

nn Optimum power/ energy consumptionOptimum power/ energy consumption


THRUST AREAS FOR EFFICIENT MILLINGTHRUST AREAS FOR EFFICIENT MILLING

1.1. CANE MANAGEMENTCANE MANAGEMENT2.2. PREPERATION OF CANEPREPERATION OF CANE3.3. SPECIFIC FIBRE LOADINGSPECIFIC FIBRE LOADING4.4. HYDRAULIC LOADHYDRAULIC LOAD5.5. PROPER SETTING OF MILLSPROPER SETTING OF MILLS6.6. PRIMERY EXTRACTION PRIMERY EXTRACTION 7.7. SECONDARY EXTRACTIONSECONDARY EXTRACTION8.8. IMBIBITIONIMBIBITION9.9. MILL SANITATIONMILL SANITATION


CANE MANAGEMENTCANE MANAGEMENT

uu Quality cane supplyQuality cane supply1. Minimum extraneous matters and 1. Minimum extraneous matters and binding materialsbinding materials2. Clean and fresh2. Clean and fresh

uu Uniform supply of cane to avoid reduced Uniform supply of cane to avoid reduced crushing situationcrushing situation

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PREPERATIONPREPERATION OFOF CANECANE

AA Optimum cane preparatory Index as 85Optimum cane preparatory Index as 85

AA Long fibrous preparation Long fibrous preparation

AA Avoid excess of cane preparatory devicesAvoid excess of cane preparatory devices

AA Avoid dusting of caneAvoid dusting of cane

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CANE PREPARATIONCANE PREPARATION

Good cane preparationGood cane preparationnn Improve Bulk density and higher number of juice Improve Bulk density and higher number of juice

open cellsopen cellsnn Make easy to extract free juiceMake easy to extract free juicenn Improve mill extractionImprove mill extractionnn Reduction in power consumptionReduction in power consumptionnn Improve Improve feedabilityfeedability to millsto millsnn Lower down mill openingLower down mill openingnn Lower mill speedLower mill speednn Lower hydraulic loadingLower hydraulic loadingnn Effective Effective imbibitionimbibitionnn Lower down Lower down reabsorptionreabsorption


BULK DENSITY AND PREPARATORY INDEXBULK DENSITY AND PREPARATORY INDEX

Relationship between bulk density and Relationship between bulk density and preparatory index at 15% preparatory index at 15% fibrefibreB.D.(kg/cm2) P.I.B.D.(kg/cm2) P.I.

400 44.5400 44.5450 52.85450 52.85500 61.25500 61.25550 69.65550 69.65600 78.05600 78.05650 86.45650 86.45700 94.85700 94.85


HYDRAULICHYDRAULIC LOADLOAD

a. To be decided by Specific Hydraulic loading a. To be decided by Specific Hydraulic loading (SHP )(SHP )

SHP = F/ 0.1LDSHP = F/ 0.1LD

Where F = Total load on top Where F = Total load on top roller (Tons)roller (Tons)

L = Length of roller (Mt.)L = Length of roller (Mt.)D = Dia. Of roller (Mt.)D = Dia. Of roller (Mt.)

b. To curb excessive lift of top rollerb. To curb excessive lift of top roller

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Mean Value Of SHPMean Value Of SHP

11stst 22ndnd 33rdrd 44thth 55thth

12 Roller 240 220 250 27512 Roller 240 220 250 275

15 Roller 240 220 230 250 27515 Roller 240 220 230 250 275Above values of SHP are in tons/ft2Above values of SHP are in tons/ft2

Nitrogen gas pressure in accumulator should be Nitrogen gas pressure in accumulator should be in the range of 70 to 90% of the hydraulic in the range of 70 to 90% of the hydraulic pressure. Nitrogen gas pressure should never be pressure. Nitrogen gas pressure should never be higher than the oil pressurehigher than the oil pressure


SPECIFIC FIBRE LO ADINGSPECIFIC FIBRE LO ADING

nn This is the maximum This is the maximum fibrefibre load to beload to begiven to a milling tandemgiven to a milling tandem

nn This is influenced by type of feeding This is influenced by type of feeding devicesdevices

nn Optimum range of SFL is 20kg/mOptimum range of SFL is 20kg/m33 to to 25kg/m25kg/m33 for mills with D chute and for mills with D chute and UFRUFR

nn Optimum range of SFL is 27kg/cmOptimum range of SFL is 27kg/cm3 3 to to 30kg/m30kg/m33 for mills with GRPF/TRPF for mills with GRPF/TRPF


REABSORPTIONREABSORPTIONSpeed of bagasse is lesser than roller Speed of bagasse is lesser than roller surface speed when it comes in contact to surface speed when it comes in contact to rollers gripping zone and reaches equal to rollers gripping zone and reaches equal to roller speed at neutral plane. The speed of roller speed at neutral plane. The speed of bagasse is higher than roller speed bagasse is higher than roller speed between neutral plane and axial plane. between neutral plane and axial plane. This phenomenon of excess speed causes This phenomenon of excess speed causes the extrusion of bagasse which gives the extrusion of bagasse which gives higher volume of bagasse than the higher volume of bagasse than the escribedescribed volume generated by the opening volume generated by the opening between the rollers called between the rollers called ReabsorptionReabsorption


REABSORPTION FACTORREABSORPTION FACTOR

The ratio of actual volume of bagasse The ratio of actual volume of bagasse emerged to emerged to escribedescribed volume volume generated by the opening between generated by the opening between rollers at axial plane is known as rollers at axial plane is known as reabsorptionreabsorption factorfactor


RF CALCULATIONSRF CALCULATIONS

RF 1RF 1STST Mill 0.75+ 0.0052V + 0.01Mill 0.75+ 0.0052V + 0.01ΦΦRF 2RF 2NDND Mill 0.65+ 0.0052V + 0.01Mill 0.65+ 0.0052V + 0.01ΦΦRF 3RF 3RDRD Mill 0.60+ 0.0052V + 0.01Mill 0.60+ 0.0052V + 0.01ΦΦRF 4RF 4THTH Mill 0.60+ 0.0052V + 0.01Mill 0.60+ 0.0052V + 0.01ΦΦ

Where V Roller surface speed (ft/minWhere V Roller surface speed (ft/min))ΦΦ FibreFibre index (lbs/ftindex (lbs/ft3 )3 )


FACTORS INCREASES REABSORPTIONFACTORS INCREASES REABSORPTION

nn Poor cane preparationPoor cane preparationnn Higher surface speedHigher surface speednn Higher hydraulic loading than Higher hydraulic loading than

requiredrequirednn Inefficient juice drainageInefficient juice drainagenn Roller polishingRoller polishingnn Increase in pressureIncrease in pressure


PROPER SETTING OF MILLSPROPER SETTING OF MILLS

nn Relative positioning of three rollers Relative positioning of three rollers (Top, Feed & Discharge)(Top, Feed & Discharge)

nn Trash plate properly drawn and Trash plate properly drawn and positionedpositioned

nn Setting of feeding devicesSetting of feeding devicesnn Proper setting of scrapers knivesProper setting of scrapers knives

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MILL SETTINGSMILL SETTINGS

nn FibreFibre method of mill settingmethod of mill settingnn FibreFibre % bagasse after each mill% bagasse after each mill

I II III IV I II III IV V VIV VI12 roll 33 42 47 5212 roll 33 42 47 5215 roll 32 41 47 52 5515 roll 32 41 47 52 5518 roll 32 40 47 53 57 18 roll 32 40 47 53 57 6060


MILL SETTINGMILL SETTING

nn wt. of bagasse after each mill (W)wt. of bagasse after each mill (W)(kg/hr)= (kg/hr)= TCHxfbx1000 TCHxfbx1000

FibreFibre% bagasse% bagasseWhere Where fbfb fibrefibre % cane% cane

nn Assume bagasse density after each Assume bagasse density after each mill (d ) in kg/mmill (d ) in kg/m33

I II III IVI II III IV1200 1210 1220 12301200 1210 1220 1230



nn Discharge opening (operating )Discharge opening (operating )

DwoDwo = = W x 1000W x 1000d x 3.14xDxnxLx60 d x 3.14xDxnxLx60

Where D Diameter of mill rollerWhere D Diameter of mill rollern Mill rpmn Mill rpmL Mill roller lengthL Mill roller lengthd Bagasse densityd Bagasse density

nn ReabsorptionReabsorption correction as undercorrection as underDwoDwo / RF/ RF



nn Mill RatioMill Ratio

Feed/Discharge Feed/Discharge Conventional 2.0 to 1.80Conventional 2.0 to 1.80With GRPF/TRPF 1.75 to 1.6 With GRPF/TRPF 1.75 to 1.6

nn Trash plate/Feed ratio Trash plate/Feed ratio

TP/FeedTP/FeedConventional 1.9 to 2.2Conventional 1.9 to 2.2With GRPF/TRPF 1.7 to 1.8With GRPF/TRPF 1.7 to 1.8

TP toe angleTP toe angle Mill apex angleMill apex angle6 6

Heal angleHeal angle >25 and < 30>25 and < 30TP slopeTP slope 4.5% to 5.5 % 4.5% to 5.5 %


UFR settingUFR setting

nn Speed Ratio for UFR= 1.1Speed Ratio for UFR= 1.1nn Average speed of UFR =Average speed of UFR =

Mill speed + UFR speedMill speed + UFR speed2 2

nn FibreFibre Compaction (kg/mCompaction (kg/m33 )=)= 85 to 12085 to 120nn UFR work opening=UFR work opening=

Fibre/minx1000Fibre/minx1000V x L x V x L x FibreFibre compaction compaction

Where V = surface speed of UFR (Where V = surface speed of UFR (mtmt./min)./min)L = Length of UFR (L = Length of UFR (mtmt ) )


DONNELLY CHUTE SETTINGDONNELLY CHUTE SETTING

nn Average speed for D chute =Average speed for D chute =Mill speed + UFR speedMill speed + UFR speed

2 2 nn FibreFibre Compaction (kg/mCompaction (kg/m33 )) 50 to 8550 to 85nn D chute opening =D chute opening =

Fibre/minx1000Fibre/minx1000V V coscosΦΦ x L x x L x FibreFibre compaction compaction

Where V Where V coscosΦΦ = Surface speed of UFR (= Surface speed of UFR (mtmt./min)./min)L = Length of UFR (L = Length of UFR (mtmt ) )


GRPF/TRPF SETTINGGRPF/TRPF SETTING

nn GRPF SETTINGGRPF SETTING1. Speed ratio (A) 1.2 to 1.41. Speed ratio (A) 1.2 to 1.42. Volumetric ratio (B) 1.3 to 1.5 2. Volumetric ratio (B) 1.3 to 1.5

nn TRPF SETTINGTRPF SETTING1. Speed ratio (A) 1.0 to 1.21. Speed ratio (A) 1.0 to 1.22. Volumetric ratio (B) 2.0 to 3.02. Volumetric ratio (B) 2.0 to 3.0


PRESSURE CHUTE SETTING

nn Normal value of inlet pressure chute angle Normal value of inlet pressure chute angle is 21 degreeis 21 degree

nn Normal value of out let angle of pressure Normal value of out let angle of pressure chute is 45 degreechute is 45 degree

nn Divergence angle of pressure angle varies Divergence angle of pressure angle varies from 5 to 7 degreefrom 5 to 7 degree

nn Pressure chute should be symmetrical to Pressure chute should be symmetrical to the axis joining mid point of PF opening the axis joining mid point of PF opening and mill feed openingand mill feed opening


PRIMERY EXTRACTIONPRIMERY EXTRACTION

nn High purity extractionHigh purity extractionnn To be achieved maximumTo be achieved maximum

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SECONDARY EXTRACTIONSECONDARY EXTRACTION

nn Low purity extractionLow purity extractionnn Extraction based on imbibition Extraction based on imbibition

efficiencyefficiencynn Extraction of more non sugarsExtraction of more non sugarsnn High power consumptionHigh power consumption

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IMBIBITIONIMBIBITION

nn By cold waterBy cold waternn By hot waterBy hot waternn Preferably by hot waterPreferably by hot waternn Optimum temperature of hot water Optimum temperature of hot water

7070ooC. C.

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MILL SANITATIONMILL SANITATION

nn To avoid bacterial growth To avoid bacterial growth nn Rapid growth of Rapid growth of LuconosticsLuconostics in acidic and in acidic and

Low Low BrixBrix juicejuicenn Regular steaming Regular steaming nn Regular chemical sprayRegular chemical spray

-- 3030--40 40 ppmppm shock dosing under extreme shock dosing under extreme conditionsconditions

-- 10 10 ppmppm for regular dosingfor regular dosingnn ChemicalsChemicals

1. 1. QuaterreryQuaterrery Ammonium saltsAmmonium salts2. Carbonates bases2. Carbonates bases3. Bleaching powder3. Bleaching powder Thrust area


NORMAL MILL PRACTICESNORMAL MILL PRACTICES

ÆÆ Not to monitor lift of top rollerNot to monitor lift of top rollerÆÆ It is assumed that top roller lifts only that value It is assumed that top roller lifts only that value

considered during mill setting calculationsconsidered during mill setting calculationsÆÆ Normally actual lift of top roller during operation is higher Normally actual lift of top roller during operation is higher

than considered in mill setting calculationthan considered in mill setting calculationÆÆ Higher thickness of cane/bagasse blanket passes through Higher thickness of cane/bagasse blanket passes through

mills due to excessive lift of top rollermills due to excessive lift of top rollerÆÆ This leads to poor extraction of sucrose and results in This leads to poor extraction of sucrose and results in

higher sugar loss in final bagassehigher sugar loss in final bagasseÆÆ Hydraulic load applies on top roller simply by Hydraulic load applies on top roller simply by

assumption/experienceassumption/experienceÆÆ It is seldom to consider the lift of top roller while deciding It is seldom to consider the lift of top roller while deciding

the hydraulic pressurethe hydraulic pressureÆÆ To compromise with mill performance due to power To compromise with mill performance due to power

constrainconstrain


PERFORMANCE OF INDIVIDUAL MILLSPERFORMANCE OF INDIVIDUAL MILLS

ÆÆ Plotting of Plotting of BrixBrix curve for feed and curve for feed and discharge sidedischarge side

ÆÆ To monitor lift of top roller To monitor lift of top roller ÆÆ Analysis of bagasse leaving the mills for Analysis of bagasse leaving the mills for

free free polpol and total and total polpolÆÆ Measurement of temperature of juice on Measurement of temperature of juice on

feed and discharge feed and discharge ÆÆ Measurement of Measurement of polpol for bagasse leaving a for bagasse leaving a

mill and juice from back roller of same mill and juice from back roller of same mill mill


OVEROVER--ALL PERFORMANCE OF MILLSALL PERFORMANCE OF MILLS

ÆÆ PolPol percent final bagasse percent final bagasse ÆÆ BrixBrix of last expressed juiceof last expressed juiceÆÆ Primary extraction (PE)Primary extraction (PE)ÆÆ Reduced mill extraction (RME) Reduced mill extraction (RME)


MAINTENANCE FOR QUALITY MAINTENANCE FOR QUALITY PRODUCTIONPRODUCTION

AIM OF MAINTENANCE IS TO KEEP DOWN AIM OF MAINTENANCE IS TO KEEP DOWN TIME MINIMUM AND TO ACHIEVE TIME MINIMUM AND TO ACHIEVE DESIRED CAPACITY UTILIZATION WITH DESIRED CAPACITY UTILIZATION WITH EFFICIENCY AND QUALITY PRODUCTIVITYEFFICIENCY AND QUALITY PRODUCTIVITY


PRESENT STATUS OF MAINTENANCEPRESENT STATUS OF MAINTENANCE

ÆÆ There is seldom preventive/predictive There is seldom preventive/predictive maintenancemaintenance

ÆÆ No records of individual equipmentsNo records of individual equipmentsÆÆ No records about repair of equipmentsNo records about repair of equipmentsÆÆ No proper training programmeNo proper training programmeÆÆ No proper house keeping worksNo proper house keeping worksÆÆ No separate inspection cellNo separate inspection cellÆÆ Lack of motivation among staff Lack of motivation among staff


PROPER MAINTENANCE SYSTEMPROPER MAINTENANCE SYSTEM

ÆÆ Complete repair and overhauling during Complete repair and overhauling during offoff--seasonseason

ÆÆ Preventive/ predictive maintenance Preventive/ predictive maintenance during crushing seasonduring crushing season


STEPS FOR GOOD MAINTENANCESTEPS FOR GOOD MAINTENANCE

ÆÆ Right selection of equipments and their Right selection of equipments and their componentscomponents

ÆÆ Correct orientation of wrongly placed Correct orientation of wrongly placed equipmentsequipments

ÆÆ Quality repair during offQuality repair during off--seasonseasonÆÆ Planning and scheduling of various jobsPlanning and scheduling of various jobsÆÆ Equipment cardsEquipment cardsÆÆ Provision of stand by equipmentsProvision of stand by equipments


PREVENTIVE MAINTENANCEPREVENTIVE MAINTENANCE

CONSTANT MONITORING ON OPERATIONAL CONSTANT MONITORING ON OPERATIONAL PARAMETERS THROUGH SYSTEMATIC PARAMETERS THROUGH SYSTEMATIC INSPECTION SO AS TO TAKE TIMELY INSPECTION SO AS TO TAKE TIMELY REPAIR/REPLACEMENT OF COMPONENTS REPAIR/REPLACEMENT OF COMPONENTS UNDERGOING WER AND TEAR TO AVOID UNDERGOING WER AND TEAR TO AVOID DOWNTIME DUE TO FAILUREDOWNTIME DUE TO FAILURE


ELEMENTS OF PREVENTIVE MAINTENANCEELEMENTS OF PREVENTIVE MAINTENANCE

ÆÆ Preventive maintenance cell with proper Preventive maintenance cell with proper motivationmotivation

ÆÆ Proper inventory to be maintainedProper inventory to be maintainedÆÆ Categorization of plant and machineryCategorization of plant and machineryÆÆ Analysis of wear and tear and evaluation Analysis of wear and tear and evaluation

of service life of service life


PREDICTIVE MAINTENANCEPREDICTIVE MAINTENANCE

IT IS MORE ADVANCE ON STREAM NON IT IS MORE ADVANCE ON STREAM NON DESTRUCTIVE TESTING WITH A VIEW TO DESTRUCTIVE TESTING WITH A VIEW TO AVOID UNNECESSARY SHUT DOWNS BY AVOID UNNECESSARY SHUT DOWNS BY TAKING FULL HELP OF TROUBLE TAKING FULL HELP OF TROUBLE PREDICTING AND TROUBLE SHOOTING PREDICTING AND TROUBLE SHOOTING TEST INSTRUMENTS TEST INSTRUMENTS


improving mill extraction

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