DSTA, AGRI. & TECII..62ND CONV.2OI6It

CRYSTAI,I,IZNIION WTTH FOURTH EFFECT FALLTNG FILXIEVAPORATOR TO ENHANCE POWER GENERATION

INTRODUCTION

In the last two decades many sugarmills started practicing co_generation u]rOcontributing in reducing the energy defi citthat India is currently facing. But rnany millsare unable realise the benefits of co_generation for which it is intended for. Thereare several factors confuibuting to the issue.However apart from the non_technicalfactors there exist several technical factorswhich need to be addressed. The time hascome for the implementation.

KEYFACTORS

The key areas which have majorimpact on enhancing power export are:1. Reduction in use ofprocess thermal

energy with optimizd vapour bleedingscheme.

2. Reductioninin-houseelecficalpowerconsumption.

3. Recovery of waste heat from a..streams for use in process or po\\ e:generation.

4. The installation of more efficien.cogeneration systems.

5" Installation of energy efficien:equipment in the process house.

6. Optirnization of process layout an:operational parameters.

So one,s thrust should be o:minimization of the steam requirement tc :sugar processing through effi cient vapou:bleeding by most suitable selection c.,evaporator type and size.

SYSTEM CONFIGURATION ANDACHIEVEMENTS

A live example on embracing variou.technologies which are implemlnted :-Dhanalakshmi Srinivasan Sugars pr,t. LtcTamilnadu are reflected next, that led th:,

Verma Vivek

Cogeneration is knot'n to be thermodt'nantically ef.ficient utilisation oJ fuel where its thermalenergt/- is used to generote elec'tricitt' as treli as Ltse part of remaining heat energy to meet theprocess requirentents The aut/tor through this paper explctined how to enhance power generationb'v crystalltzation tt trlt fcturrh e-/fect -falti"ng fitm evaporator using innovcttive approach & fficienttechnologies and gi e true erample through Dhancilakshmi Srinivasan sugars, Tamil Naclu whichis one of tr's kinds o-f plctnt thctt **as designecl ntuch fficient that,. it is exporting electric power atthe rate of l0a klf',,Ton of cane.

Ke1'w'6'4t' Cogeneration, Evaporation, Conrinuous crystailization, Refinecr sugctr, Corour varuet\{assecuite Boiling, Flashing System.

\I:,nagingDrrector,SprayEngineeringDevicesLimited,vir,ek.verma@,om

ABSTRA.CT

].STA. AGRI. & TECH.-62ND CONV.2OI6

:lant much efficient. The current steam:emand ofthe plant i s31-34o/oon cane and

=chieved highest exporting power range. e. 1 00- 1 OSkWTon of cane.

Steam is consumed directly or:directly rnainly in two areas of the sugar:rocessing i.e. evaporation and--rystallization. This paper presentedjifferent techniques to enhance cogeneration'.i'ith minimurn steam constunption in sugar

-ctories in order to make the sugar factory-nore profitable by increasing the powererport.

This plant operates at 1 1 0 ata. 5400C:vcle with one I 10 TPH boiler and 23 MWPower Generation capacity with Sulphur-Free Refined Sugarproduction. Apart &omte steam ecohomy and power generation:rulestones of this plant has few more special:bahres.

o A modem2roTler 4-mill tandem plantwith electrical drives and an inlineshredder.

o The clarification is Sulphur free withonly defecation followed.

A modern boiling house with a

eombination of Falling FilmEvaporators (FFEs), Direct ContactHeaters, Vertical Continues Pan forA,B, C, Rl and R'2 Massecuite boilingwith Melt Clarification system.

CIP system with full automation in lineFFEs.

Steam and vapour balance done toachieve 3l% process steamconsumption on cane.

l9t

40oh savings on power consurnptionbythe advancedAc-VFD Motors inthe process plant over the conventionalsystems.

Fully automated Sugar and Co-Generation units with DCS confols.

State of art cooling and condensingsystem with gravity inflow coolingtowers.

The achievement oftheplant lies in theprocess house especially the evaporationand crystallization,in this plantthe systemsrvere designed and implemented to ensureits supremacy rn achier..ing the performance.

A. Evaporator Station

Concentration of cane juice tosaturation point alone consumes majorportion of total energy demand. Thequantum of steam used for this purpose isvery significant for co-gen. Optimizedselection oftotal temperature difference and

number of effects reduces a lot the sinkingofthe energy in this section.

Making availability of more numbersof skeams for process heating and that tooat required temperature & pressure, dophenomenal improvements in the sugarprocess.

Typically, more is the number ofevaporator effects; greater will be the steam

economy. The evaporator station in this plantwas designed to deliver 0 .65-0.7 0 absolute

bar pressure to pans and that too from 4rr,

effect vapours. The whole thing that liesbehind all *ris happening is by crystalli:zaaon

;G FIL\fro.\

....!.:,

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DS'IA, ACR.I, & Tirl.l-i -52|rD CONV'-2016

rvith fburth etTecl ofFalling Film Evaporators

(FFEs). Falling F'ilm Eve.porator contrary ro

fusing Film and Rohert type evapcrator can

be easily operatecl with,o'ery low A T i.e. as

lor,v as 3-4"C. FFEs as acting as thebackbone fbr the efliciency levels that plantis achier,ed.

Extensive vapours coming out of thedifferent effects of the e-,.aporators ere used

for juice heaters and vacuuin pans. FFEsmaking whole evaporaticn station as

amalgam of efficient bleeding system alongwith flashing system with enhancing flashrecoverv- arc making the plant high energyefficient & reduced steam demand. f-heefficient distribution of liquid for constantwetting ofheating tubes with juice is welltaken care fbr a kouble-fiee operation of aFalling Film Evaporaior. The FF'E withhi-tech cascade distributor design forms a

thin and even fiim of fbed sclution at innersurface ofthe tube n:iaintaining positive juicecirculation. The competent design

1q:

modification offalling fiIm evaporators anc

its distributor design helped in achievinsmervelous consequences in this plant. The

evaporator station setup at this plant is a.

under:

o Quintuple Evaporator station with a-identical Falling Film bodies (7 Nos. :L

1500 m:)"

o CondensateFlashVesselSystemlrri

flashing off vapours frorn h,: .

condensate to be further utilised t,::juice evaporation. Parallellr. ,

eliminated the condensate pumps :,individual steam/vapours consumilDirect Contact Juice Heaters (DCr.for Raw, Defecated and Clear Jur-.& Syrup heating in vary clo..approach.

r SingleFloatingEvaporatorforclearr:

all effects.

o Working temperature range of -_:.

evaporator is 125'C to 75oC.

Tabie 1: Fresent operatingparameters of evaporator station

Sr. No. EvaporatorEffects

OperatingPressure

Operating Temp.

fc) oarA)Operating Temp.

Difference (AT)

1 1" Eftbct 1.8-1.9 118-120 6-goc

I 2"d Effect 1.3-t.4 1 10-1 12 g-goc

J 3'd EtTect 0.9-1.0 98-102 7-l\oc4 4ft Effect 0.6-0.65 93-96 5-7oC

5 5ft Effect 0.35-0.40 7s-78 72-750C

19:

3\ aporators and

eC in achievins

n this plant. The

t :his plant is as

'siationwith a1,

r.'.dies (7Nos. :i

sei Systemri'ir::s frorn hc.:er utilised fi,Para11el1r.

1>3te pumps : ,*:s consum-!-ieaters (DC. -

:.; Clear Ju-:.r r ar,v clc,..

l,:tbrclear::-.

' -:noe ,rf '-

, -s.c

nlg Temp

:rce (-rTt

-t i-

DSTA, AGRI. & TECH.-62ND CONV.2O]6

It'igure I : E'

The bleeding scheme is the heart ofj- lporator station where lot of energy can-, saved for enhance power generation

.:acity specifically by operating--. stallization pafi using foufih eflect r.'apours

-lhng fi1m evaporator.

Dhanalakshrd Srinivasan Sugars pvt.

Ltd. entii'ejuice heating was only rvith direct

contact heaters (DCH) (no tubular. no

PHE).

a. Mi-xed Juice is two stages heatine. flrst

with Pan Vapors fclloived br. 5,', eli-ect

i93

Figure 1 : EvaporatorStation

DSTA, AGRI. & TECH.-62ND CONV-2016

vapour. These two stages heating raise

the juice temperatur e at 7 0 -l 4" C.

b. Limed Juice is in three stages allthrough DCH using 4n', 3'd & 2nd effect

vapour.

The said bleeding scherne has reduced

the steam consumption at 3 1.0-3 4.0%o oncane and enhanced the power generationcapacity.

B. Crystallization

Crystallization is anothermajor enerryintensive area. This section, furtherhavesignificant effect on the efficiency oftheplant

But in Dhanalakshmi Srinivasan Sugars

all are Vertical Continuous Vacuum Pan(SCP@) so the demands are ofminimumpossible steam pressure for massecuiteboiling. Lower pressure requisite for thisplant for pan bleeding have made higherimpactonthe co-gen.

l9l

Clear juice is single stage using 2n'

effectvapour.

All crystallization part is taken br

Vertical Continuous Vacuum Pai:

(SCP@) which is operating with 4'effect vapour of falling fi lrn evaporato:

Continuous pans are characterizec :constant boiling point and constant he a::.-.surface to volume ratio in contrast to b::: -

boiling where temperature increases i, -:boiling. In lowpressure operatioflpofls r-: :

temperature does not increase much and .,.improves sugar quality beside thermal er:.::benefits there are qualitybenefits as u e r.

The effect of low pressure boilin: -

sugar quality of Dhanalakshmi Snrur - -Sugars is that their refined sugar colc -:only 33-34IU. The SCP@ configuratrc:.pans are efficiently making optim:: - -evaporative crystallization ofsugar solu: -,SCP@ has shown high efficiency withou .-compromise on the process paramet-!

c.

d.

Sr. No. Description Configuration OperatingTemperature

1 MJ lst Heating Pan Vapour 54-57 0C

2 MJ 2nd Heating 5th Effect Vapour 74-77 0CaJ DJ lst Heating

,4th Effect Vapour 86-89 0C

4 DJ 2nd Heating 3rd Effect Vapour 96-99 0C

5 DJ 3rd Heating 2nd Effect Vapour 107-110 0C

6 CJ lst Heating 2nd Effect Vapour 107-110 0C

7 All Pans (A, B, C & R) 4th Effect Vapour 86-89 0C

T able 2 : Vapour bl eeding arrangement

DSTA, /

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2U25"t

playden€rs/gsnerat

TImassec

.AlPa

.: t a::

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\-- _ r: -

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- .-'-- -- - l*:--L- --' -

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: r-'.. .\CRI. & TECH.-62ND CONV-2016

Vertical continuous pan is easily:.rated at very low At i.e. as low as

- -15"C. Vertical continuous vacuum pan

: :-, ed a significant role in the reduction of:--:r9\/ Consumption and to enhance power

- -:gration that plant is achieved.

The installed vacuum pan for various

-- -secuite boiling is as under:

r AllthreeVerticalContinuousVacuum

Pan (SCP@) for A, B, C, R1 & R2

19_i

massecuite boiling r,vith completeautomation.

Molasses Conditioner forAH, BH, CLand R1 molasses of direct contactheatingtlpe.

2 nos. of Seed Crystallizer of20T forA and B Seeds.

2 nos. of Grain Crystallizer of 30T forB and C Grain.

5 nos. of supply tanks of 2 for syrup& melt and 3 for molasses storage.

arilgerafure

,-iC

I rt

1-t ,-C

.C

Figure Z:PanStation

Sr.

No.

Particulars Unit SEASON WISE

2014-15 20t3-14 20t2-13 2011-r2 2010-11 2009-

I Planl CrushingRatc

MT 3204 3000 2000 1600 2200 191_

2 Powcr ConsumPtionper ton of Cane

kwh/T 29.40 30.84 30.79 32.13 32.63 3E . -

a Sugar Colour(Season average)

ru 33.93

I)-s] \. .\GRI. & f ii(lil.-62ND CON\"-2016

'l'he process cngineering design ofthe

piant have made significant impact on

various aspccts of lactory operation and

cquipment usage ancl linally to power

gcneration and exporl. -lhis design together

deprcsscs the utility rcquirements to a

greatcr ler.cl in 1he sugar process house.

Middle pressure stcam requirement is

19:

eliminated. Furthermore, all these togethe:

alter the co-gen in an encouraging way suc:

thatthe total electricity generation ofthe p1r

gets increasedby 9-12% if compared rr i-*-

other factories operating in the viciniry*.

Other remarkable parameters of t:-,

plant are as under:

!

Table 3 : Season wise Parameters

Figure 3 : Cogeneration Unit

-

196

these togetherg:IgwaysuchionoftheplantomparedwithLe ricinity.

rneters of this

DSTA, ACRI. & TITCH.-62ND CONV_2016

RESULTAND DISCUSSIONS

A lot ofopportrurities for energy saving:-rist in the sugar industry and there is need'.r exploit these for better per-formance. lt isjrperative for cogeneration to be adopted: the industry to increase electricity output.:d to make better use of process steam:rough optimised bleeding arrangement

,-gported by efficient evaporators and:.-,ntinuous pans. The deplo5rment ofenergy-:icient equiprnent and technology forthe. -.frovement of co-gencration can entirely. - ange the present scenario of sugar factory.

Increasing power export beyond:::sent level of 70-80 kWh/Ton to 100_

,t kWh/Tons, it bccomes very important

Table 4 : Month wise cogeneration details

I9-7

for profi tability of this industry.

This concludes that l2yo of totalelectricity generation can be enriched bycorrection in energy management system asa ultimate measure in the efficiencyimprovement ofzugarplant. Adopting suchtechnology and idea, the sugar infiastucturewill have enoughpowerto caterthe energydemand ofthemselves and their vicinity.FURTHER SCOPE

There is firther scope ofimprovementin power co-generation with addition &balancing ofenergy efficient equipment &technology like bagasse d.yer, flue gas heatrecovery, exhaust condensate heating.

I

Jan-2016 Mar-16 Apr-16Power Generation per Tonof Cane

128.11 135.8s

Power Consumption per TonofCane

Power Export per Tonof Cane

105.21

I