Poster presentation on NATURAL DRAFT COOLING TOWER

‘THERMAL ANALYSIS AND DESIGN OF A NATURAL DRAFT COOLING TOWER OF A 1000 MW NUCLEAR POWER PLANT’, 2nd International Bose Conference, 2015, December 2015, University of Dhaka, Dhaka, Bangladesh.

1. RESEARCH POSTER PRESENTATION DESIGN © 2015
www.PosterPresentations.com
Inatypicalcoolingtowerwatercircuit,warmwaterfromthecondenserof
thenuclearplantispumpedtothecoolingtower,whereitisdischarged
throughaseriesofspraysagainstastreamofcoolingair.Insomecases
oneormorepropellerfanareusedmovingairverticallyuporhorizontally
throughthetower.Bafflesandfillmaterialsareplacedinthepathofthe
fallingwatertobreakitupintotinydrops,thusincreasingtheeffective
surfaceareaofthewater.Thesebafflesaremadewood,ceramicsandin
recenttimesplasticsareused.Thetowercoolsthewaterbybringingitin
contactwithairandevaporatingsomeofthewater.Theheatlosttotheair
whichbecomeshotandmoistbywaterevaporation.Waterincollectedina
reservoirandpumpedbacktothecondenser.Make-upwaterisaddedto
thetanktoreplacethewaterthatislostdietoevaporation,driftandbleed.
ABSTRACT
OBJECTIVES
a) Natural draft cooling
Theaircirculationthroughthetowerisbynaturalconvection.Thistypeof
towersaremadeofwoodorsteeldeck.Warmwaterisdischargedatthe
topthattricklesdownacrossthewoodenormetallicdecksandintoabasin
atthebottom.Inspraytypetowerswaterispumpedatthetopandsprayed
throughthenozzlestofallintothebasinofthetower.
b) Mechanical Draft Cooling tower
Theaircirculationofthesetypeoftowerisdonethroughbymeansof
blowerorfan.Therearetypetypesofmechanicaldraftcoolingtowers
namely:
i.ForcedDraftCoolingTower:
Herethefangeneratesacentrifugalpullusingthepropellerofthefanthat
blowsairthoughthetower,countertotheflowofthewaterinthetower.A
forceddraftcoolingtoweriscompactinsizebutitrequiresadditional
horsepowerandinfactmorethantheinducedone.
ii. Induced Draft Cooling Tower:
Inthistypeoftowerthepropellerfanislocatedatthetopofthetowerand
theairispulledoutofitfromtheendsthroughthetoweracrossthewater
flowpath.
•Reactor thermal output = 3200 MW th
•Power plant output = 1170 MW e
•Power plant output, net = 1082 MW e
•Reactor type: Pressurized Water Reactor (PWR)
VVER -1000 SPECIFICATIONS SELECTION OF COOLING TOWER FILL
Theheartofevaporativecoolingisitsfill,apackingofsortdesignedto
providethenecessarycontactareaandcontacttimebetweenairandwater.
Ifthefillisingoodconditionthetowerwillprovideampleamountof
coolingtoweratthetemperaturethatiswasdesignedtoprovide.Ifnot
thenitwillnotprovidecoolwater.
SUMMARY
Fromtheabovetwotableitisclearlydepictingthatsplashtypefillwould
bethemosteffective.Itisbesttoconsultwithcoolingtowermanufacturer
whattypeoffillwouldbebestwithexcellentthermalpropertiesanda
waterspecialistwhocanrecommendtheappropriatetreatmentchemicals
tominimizedeposits.
Theauthorsofthispaperhavemathematicallyanalyzedtherelationship
amongdifferentparametersasrange,approach,massflowrateetc.forthe
naturaldraftcoolingtowerofaratednuclearpowerplant.Fromthe
calculation,a150mhighNDcoolingtowerhasbeenselectedforRuppur
nuclearpowerplant(VVER-1000).Thefigureshelptovisualizea
generalizedanalysisofdifferentcoolingtower.Furthertoimprovethe
performanceofheattransferimpactsofvarioustypesoffillmediawere
discussed.
1.To provide an overview of different types of cooling tower used in a
typical nuclear reactor.
2.To design a Natural Draft Cooling Tower for a 1000MW nuclear
reactor.
3.To analyze the cooling tower in different conditions.
4.To select the type of fill media.
BANGLADESH UNIVERSITY OF ENGINEERING & TECHNOLOGY
SayeedMohammed, SyedaNoor –E–Lamia, MusannaGaliband M. A. Rashid Sarkar
THERMAL ANALYSIS AND DESIGN OF A NATURAL DRAFT COOLING TOWER OF A 1000 MW
NUCLEAR POWER PLANT
WORKING PRINCIPAL OF COOLING TOWER
Coolingtowersusetheprincipleofevaporativecoolingtoremoveprocess
heatfromthecoolingwaterandreducesitstemperaturetothewet-bulbair
temperature.Itisaheatandmasstransferdevice.Thismethodofcooling
provideswithefficientandenvironment-friendlymethodofcooling
particularlyinlocationswheresufficientcoolingwatercannotbeeasily
obtainedfromnaturalsourcesorwhereconcernfortheenvironment
imposessomelimitsonthetemperatureatwhichcoolingwatercanbe
returnedtothesurrounding.Coolingtowersareanimportantpartofthe
nuclearpowerplantswhichremoveheatfromcoolant(water)ofthe
condenserandrecirculateit.Naturaldraftcoolingtowersrepresenta
relativelyinexpensiveanddependablemeansofremovingheatfrom
coolingwaterasairinsideitiscirculatedbynaturalconvection,no
mechanicalmeanssuchasfanspropellersareneeded.Theperformanceof
thenaturaldraftcoolingtowerisdominatedbywindspeed,ambientair
temperaturesandhumidityintheatmosphericconditions.Thispaper
providestheanalysisofdesigninganaturaldraftcoolingtowerconsidering
alltheseparameterswiththehelpoftrialanditerativemethod.Theeffect
ofheight,diameter,andthetypeoffillingmaterialselected,arestudied.
TYPES OF COOLING TOWER
RUPPUR NUCLEAR POWERPLANT
Theplantisaproposed2GWenuclearpowerplantofBangladesh.Itis
proposedtogointooperationby2022andwillbethecountry'sfirst
nuclearpowerplant.ThenuclearpowerplantwillbebuiltatRuppur,
200kmnorth-westofDhaka,intheIshwardisubdistrictofPabnaDistrict,
inthenorthwestofthecountry.Theproposalwasfirstraisedin1961.
Governmenttook253.90acreoflandofcurrentplaceatthatyeartobuild
theplant.In1963theplantwasapproved.Discussionstookplacewiththe
Canadiangovernmentin1964and1966.Discussionswiththegovernments
ofSwedenandNorwaywerealsogoingoninthoseyears.However,no
realprogresswasachieved.AftertheindependenceofBangladesh,the
GovernmentofBangladeshstarteddiscussionwiththeSovietUnionin
1974,howevernoagreementwasreached.
In2009theBangladeshgovernmentagainstarteddiscussionwiththe
Russiangovernmentandon13Februarythetwogovernmentssigneda
MoU.Rosatomsaidtheywouldstartconstructionby2013.
In2013groupofBangladeshiscientistsfromBangladeshandtheglobal
diasporavoicedprofoundconcernoverthesafetyandeconomicviability
oftheplant.Severalseparateissueswereraised,fromtheunsuitabilityof
thesitetotheobsolescenceoftheVVER-1000modelproposed,
questionablefinancingarrangementsandalackofagreementwithRussia
overnuclearwastedisposal.
In2015theproposalwasdelayedbyayear.Rosatomalsoofferedatwo
VVER-1000reactorpowerplant,whichwouldincreaseoutputto2.4GWe.
TOWER DESIGN
Based on the specifications of Ruppurnuclear reactor a design of natural
draft cooling tower was made using the above equations through iterations
the height of the cooling tower was determined
NAME SYMBOL DESCRIPTION UNITS
Duty
coefficient
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∗
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)
�.�
--
Base area of
tower
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m
2
Height of
tower
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Assumed values are used during
calculations to confine to a height to
diameter ratio of 3:2; in case of
hyperbolic natural draft towers
m
Diameter of
tower
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m
No.
Height
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(m
2
)
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(m)
Height to
diameter ratio
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??????≈1.5
1 150 7321 96.55 1.55 ≠ 1.5
2 145 7446.64 97.37 1.48 ≠ 1.5
3 147 7395.81 97.041.51 ≅1.5
From the above calculation it is evident that about 150m high natural draft
cooling tower is to be designed to cool a 1000MW nuclear reactor.
Now here the design was made for a particular range. Now for other ranges
we can visualize how the height of the tower changes
There are different types of fill media and each have different capabilities.
Now as an engineer it is a challenge to determine the optimum fill media
based on the design of the cooling tower. So they types of fill that are
available for the design are
Nowtheaboveshowsusthedifferenttypesoffillbuttochoosethebest
fillthefollowingtwochartswillmaketheselectioncriteriaeasier.
REFERENCE
1.Selecting the Optimum Cooling Tower Fill by Paul R. Puckorius.
2.Determination of Optimum Height for Counter Flow Cooling Tower by
Ashraf Kotb.
3.ASHRAE Handbook, “HVAC Systems and Equipment (SI)”, American
Society of Heating, Refrigeration and Air Conditioning Engineers, Inc..
ASHRAE (2008).