化工原理习题2.docx
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化工原理习题2.docx
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化工原理习题2
«化工原理Ⅱ»习题
一、填空题
1.Inthetwo-filmtheory,()isassumedattheinterface,andtheresistancestomasstransferinthetwophasesareaddedtogetan(),thereciprocal(倒数)ofwhichisthe().
2.Duringgasabsorption,whenthevaluesofV,ya,yb,andxaremainconstant,decreasingtheflowrateoftheabsorbentwillmakethedrivingforceofmasstransfer(),andtheoperatinglinewillapproch().
3.Principlesofgasabsorptionis(),inwhich()isassumedattheinterface.
4.Foragivengasflow,areductioninliquidflowwill()theslopeoftheoperatingline,and()thedrivingforceofthecolumn.
5.Agasstreamcontaining3.0%A(molepercent)ispassedthroughapackedcolumntoremove90percentoftheAbyabsorptioninwater.Theequilibriumrelationisy*=0.6x,(L/V)min=()
6.Atlowconcentrationgasabsorption(1atm),iftemperatureremainsconstant,increasingthetotalpressurewillmakem(),E(),drivingforce().(increase,decrease,remainconstant)
7.Allfiveofthefeedtypesareasfollows:
(),(),(),(),().
8.Atypicalcontinuousfractionatingcolumnisequippedwiththenecessaryauxiliaries,suchas(),().
9.Therelativevolatilityofabinarymixtureα=3,attotalrefluxxn=0.3,soyn+1=().
10.WhenxD,xB,andRareallremainconstant,forvarioustypesoffeed,thevalueofqforcoldliquid-feedisthe(),thedistancebetweenthestrippingoperatinglineandtheequilibriumcurveisthe(),andthetotalnumberofidealplatesrequiredisthe().(greatest,smallest,orthesame)
11.Wheneitherdistillationorextractionmaybeused,thechoiceisusually().
12.Inthetrianglediagram,thevertexes(顶点)ofthetrianglerepresent(),thepointoneachsiderepresents(),andthepointinthetrianglerepresents().
13.Thetrianglediagramisdividedintotwopartsbytheequilibriumcurve,thezoneunderthecurveis(),andthezoneoutsidethecurveis(),sotheextractionmustbeoperatedinthezoneof().
14.Inliquidextraction,()isthelayerofsolventplusextractedsolute,and()isthelayerfromwhichsolutehasbeenremoved.
15.Intherighttrianglediagram,
(0.4,0.4,0.2)representthe
coordinate(坐标)ofthepoint();
and(0.2,0.2,0.6)representthepoint().
16.Whenthehumidityofairisconstant,thehigherthetemperatureis,()therelativehumidityis,and()thewetability(吸湿能力)is,so()enteringthedryer,thewetairshouldbepreheated.
17.Ifthedry-bulbtemperatureofthewetairat1atmremainsconstant,increasingthehumidityoftheairwillmakethepercentagehumidityHA(),wet-bulbtemperatureTw(),thedewpointtemperatureTd(),thehumidheatcs().
18.ThehumidityHofawetairremainsconstantat1atm.Increasingitsdry-bulbtemperatureTwillmakepercentagehumidityHp(),humidheatCS(),wettemperatureTW()andenthalpy
().(increase,decrease,unchange)
二、判断题
1.Packedcolumnsareoftenusedfordistillationwhentheseparationisrelativelyeasyandtherequiredcolumndiameterisnotverylarge.
2.TheL/Vratioisimportantintheeconomicsofabsorptioninacountercurrentcolumn.
3.ThenumberoftransferunitsNoyrepresentsthechangeinvaporconcentrationdividedbytheaveragedrivingforce.()
4.Theoperatinglinemustlieabovetheequilibriumlineinorderforabsorptiontotakeplace.()
5.Fordilutemixtures,containinglessthan10%ofsolutegas,theeffectofchangesintotalflowisusuallyignoredandthedesignisbasedontheaverageflowrates.()
6.IntheabsorptionofNH3inwater,increasingtheliquidvelocitywillgetamuchgreaterrateofabsorption.()
7.Thenumberoftransferunitsequalstothenumberofidealstagesiftheoperatinglineandtheequilibriumlinearestraightandparallel.()
8.ThechoiceoftheoptimumL/Vratiotouseinthedesigndependsonaneconomicbalance.()
9.Forabsorption,theequilibriumlineisusuallysteeperthantheoperatingline.()
10.ThestrippingfactorSistheratiooftheslopeoftheoperatinglinetothatoftheequilibriumline.()
11.Extractionequipmentmaybeoperatedbatchwiseorcontinuously.
12.Theraffinateisthelayerofsolventplusextractedsolute.
13Thecompositionsoftheextractandtheraffinateareequalatplaitpoint(临界混溶点).
14.Hightemperaturewillbegoodforextraction.
15.Theraffinateisthelayerfromwhichsolutehasbeenremoved.()
16.Onlyselectivitycoefficientβ<1,theextractionseparationispossible.()
17.Hightemperatureisgoodforliquidextraction.()
18.Theliquidandvaporenteringanidealplatearebroughtintoequilibrium.()
19.Indistillationthefeedlinemustcrossthepoint(xF,xF).()
20.Theliquidandvaporleavingapartialcondenserareinequilibriumwitheachother.()
21.Alltheplatesbelowthefeed,includingthefeedplateitselfconstitutetherectifyingsection.()
22.WhentherefluxratioRisinfinite,thenumberofidealplatesisalsoinfinite.()
23.Alltheplatesabovethefeed,includingthefeedplateitselfconstitutetherectifyingsection.()
24.WhentherefluxratioRisminimum,thenumberofidealplatesisinfinite.()
25.Thesolidsurfaceisatthewet-bulbtemperatureduringtheconstant-rateperiod.
26.Forairofdefinitehumidity,themoisturecontentofthesolidleavingthedryershouldbelessthantheequilibriummoisturecontent.()
27.Decreasingthethicknessofthematerialgivesalowercriticalmoisturecontent.()
28.Wet-bulbtemperatureisnotthegastemperature,buttheliquidtemperature.()
29.ThecriticalmoisturecontentXCwillvarywiththethicknessofthematerial.()
三、选择题
1.TheabsorptionofNH3inwaterisoftencitedasanexampleof.
Agas-filmcontrolBliquid-filmcontrol
Ctwo-filmcontrolDuncertain
2.Onanidealplate,arebroughtintoequilibrium.
Atheliquidandvaporleavingtheplate
Btheliquidandvaporenteringtheplate
Ctheliquidenteringtheplateandvaporleavingtheplate
Dtheliquidleavingtheplateandvaporenteringtheplate
3.WhentherefluxratioRdecreases,theoperatinglinewillbeclosetotheequilibriumcurve.Inordertoaccomplishtheseparationrequirement,thenumberofidealplateswill()
AdecreaseBincreaseCunchangeDuncertain
4.Ingasabsorption,thetotaldrivingforceonacrosssectionofthecolumnis().
A.x*-xB.x-x*C.xi-xD.x-xi
5.Flashdistillationisusedtoseparateabinarymixture,thetemperatureoftheoverheadproduct(vapor)containing75molepercentlightcomponentis
andthetemperatureofthebottomproduct(liquid)containing50molepercentlightcomponentis
.Therelationof
andT2is().
A.
=
B.
<
C.
>
Duncertain
6.()willbebeneficialtogasdesorption.
AHighpressureandlowtemperatureBlowpressureandlowtemperature
CHighpressureandhightemperatureDlowpressureandhightemperature
7.Inordertoseparatethemixtureofsoluteanddilulent,solventshouldbeaddedtothemixturetomakethecompositionoftheresultingmixturelie().
A.upontheequilibrium;B.undertheequilibrium
C.ontheequilibrium;D.ontheordinate
8.Theparameterofthewetairthatdoesnotchangeinthepreheateris().
A.therelativehumidityHRB.theenthalpyI
C.thewettemperatureTwD.thedewpointTd
9.Forthesaturatedgas,therelationshipamongthedry-bulbtemperatureT,thewet-bulbtemperatureTw,andthedewpointTdis.
AT=
=
BT>
>
CT<
<
DT>
=
10.Todryasampleofthesamesolidwiththesameinitialmoisturecontent,alowercriticalmoisturecontentwillmakethetotaltimeofdrying().
A.prolongedB.shortenC.unchangeD.uncertain
11.TheabsorptionofCO2inwaterisclearly()
A.gas-filmcontrolledB.liquid-filmcontrolled
C.two-filmcontrolledD.uncertain
12.Ingasabsorption,thetotaldrivingforceonacrosssectionofthecolumnis()
A.y*-yB.y-y*C.yi-yD.y-yi
13.()willbebeneficialtogasabsorption.
A.HighpressureandlowtemperatureB.lowpressureandlowtemperature
C.HighpressureandhightemperatureD.lowpressureandhightemperature
14.Inthex-ydiagram,thevariationofqwillmakethelinesof()change.
A.equilibriumcurveanddiagonal(对角线)B.equilibriumcurveandthefeedlineC.operatinglineandthefeedlineD.operatinglineandequilibriumcurve
15.If8idealplatesplusareboilerarecalledforandtheefficiencyis50percent,thenumberofactualplatesis().
A.14B.16C.12D.uncertain
16.()havethesameseparationfunctionofanidealplate.
A.reboiler,totalcondenserB.reboiler,partialcondenser
C.vaporizer(汽化器),totalcondenserD.reboiler,vaporizer
17.Whentherelativehumidityoftheairstreamis80%,therelationshipamongthedry-bulbtemperatureT,thewet-bulbtemperatureTw,andthedewpointTdis.
A.T=
=
B.T>
>
C.T<
<
D.T>
=
18.()candividethetotaldryingtimeintotwoparts:
theconstant-rateperiodandthefalling-rateperiod.
A.unboundwaterB.freemoistureC.boundwaterD.criticalmoisture
19.Forclose-boilingmixtures,()shouldbeusedtoseparatethem.
A.distillationB.extractionC.absorptionD.leaching
20.Duringtheextraction,()showsthatthechoiceofsolventisnotsuitable.
A.
<1B.
=1C.β>1Dβ<1
21.Indistillationtherelationshipamongtheconcentrationoftheliquidsleavingtheplate(n-1),n,(n+1)is().
A.
B.
C.
D.uncertain
22.Thesmallertherelativevolatilityαofabinarymixtureis,the()theseparationofthemixturebydistillationis.
A.easierB.moredifficultC.morecompletelyD.uncertain
23.Bythetwo-filmtheory,attheinterface().
A.thegasconcentrationisgreaterthanth
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