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1、ProblemsforMassTransferandSeparationProcessAbsorption1Theammonia–airmixturecontaining9%ammonia(molarfraction)iscontactwiththeammonia-waterliquidcontaining5%ammonia(molarfraction).Underthisoperatingcondition,theequilibriumrelationshipisy*=0.97x.Whentheabovetwophasesarecon
2、tact,whatwillhappen,absorptionorstripping?Solution：Itisanabsorptionoperation.2Whenthetemperatureis10andtheoverallpressureis101.3KPa,thesolubilityofoxygeninwatercanberepresentedbyequationp=3.27´104x,wherep(atm)andxrefertothepartialpressureofoxygeninthevaporphaseandthemole
3、fractionofoxygenintheliquidphase,respectively.Assumethatwaterisfullycontactwiththeairunderthatcondition,calculatehowmuchoxygencanbedissolvedinthepercubicmeterofwater?Solution:themolefractionofoxygeninairis0.21,hence:p=Py=1x0.21=0.21amtBecausethexisverysmall,itcanbeapprox
4、imatelyequaltomolarratioX,thatisSo3Anacetone-airmixturecontaining0.02molarfractionofacetoneisabsorbedbywaterinapackedtowerincountercurrentflow.And99％ofacetoneisremoved,mixedgasmolarflowfluxis0.03kmol·s—1m-2,practiceabsorbentflowrateLis1.4timesasmuchastheminamountrequired
5、.Undertheoperatingcondition,theequilibriumrelationshipisy*=1.75x.VolumetotalabsorptioncoefficientisKya=0.022kmol·s—1m-2y-1..Whatisthemolarflowrateoftheabsorbentandwhatheightofpackingwillberequired?solution：xa=0YibinCityCitytracktrafficplanningisYibincityregionalrangewith
6、intracktrafficsystemofonceintegration,andcitytracktrafficalsoisYibinCityCityintegratedtracktrafficsystemintheofpart,foraccurategraspcitytracktrafficresearchofobjectNumberofmasstransferunitsNoy=(y1-y2)/Dy=12(yb-ya)=0.02-0.0002Dy=[(yb-y*b)-(ya-y*a)]/ln[(yb-y*b)/(ya-y*a)](y
7、b-y*b)=0.02-1.75xb=0.0057Xb=V/L(yb-ya)=(0.02-0.0002)/2.43=0.00815(ya-y*a)=ya=0.0002Or=124ThemixedgasfromanoildistillationtowercontainsH2S=0.04(molarfraction).Triethanolamine(absorbent)isusedasthesolventtoabsorb99%H2Sinthepackingtower,theequilibriumrelationshipisy*=1.95x,
8、themolarfluxrateofthemixedgasis0.02kmol·m-2·s-1，overallvolumeabsorptioncoefficientisKya=0.05kmol·s—1m-2
