化学反应工程原理课件 1-1

1绪论化工生产过程

用化学方法将原料加工成产品的生产过程。pretreatmentphysicaltreatmentsteps

separationphysicaltreatmentstepsrawmaterialsrecycleproductschemicaltreatmentsteps化学工程：

工程技术的一个分支，探讨化工生产过程的规律性，并根据对其规律性的认识来解决化工生产中的问题。pretreatmentphysicaltreatmentsteps

separationphysicaltreatmentstepsrawmaterialsrecycleproductschemicaltreatmentsteps1.1ChemicalReactionEngineeringconcernedwiththeexploitationofchemicalreactionsonanindustrialscale.engineeringaspectofchemicalreactionindustrialreactorsTheresearchesonchemicalprocesses:

before1920s

forproductionofspecificproducts

1920s

unitoperations

1960

transportphenomena

1957

reactionengineering

engineeringscience1.1.1研究对象

对于化学变化的研究，有：尺度基础研究对象量子量子力学分子间化学变化的微观规律分子动力学或化学动态学分子经典力学众多分子间化学变化的宏观规律微团或设备化学动力学传递理论工业反应器中的化学变化规律化学动力学化学反应工程－工业反应过程1.1.2Objectives(1)

developmentofreactiontechnology(2)

optimizationofoperatingcondition(3)design,scale-up,andanalysisofreactor,

predictionofreactorperformance1.1.3Context

Kineticsmechanismandrateofreaction

Foracertainreactionsystem,therateofreactionisusuallyexpressedas

r=f(c,T,p)Modeloftransportphenomena

v,p,c,T=f(x,y,z,t)

effectoftransportprocessesontherateofreaction

optimizedoperationcondition,

themostappropriatetypeandstructureofreactor（三传一反）（反应器设计与分析）Oxidationofammoniaonacatalyst:

Chemicalandphysicalprocessesoccursimultaneously.NH3O2NOH2OQ4NH3+5O2

4NO+6H2OHr

reactionheatandmasstransfermomentum,1.1.4Methodmathematicalmodeling

resolutionofproblemchemicalreactionphysicalprocessesreactionkineticsmodeloftransportcombinationMathematicalmodeling:过程实验与观察过程的分析研究计算机模拟物理模型数学模型用于反应器设计、放大与分析与实验结果比较否模型参数(实验)合理简化是理论、实验和计算的结合1.2ConversionandYieldofReaction1.2.1Extentofreaction

Areactionis

AA+BB

RR(1.1)whereisthestoichiometriccoefficient,

for

reactant(A,B),isnegative;

for

product(R),ispositive.

initialmoles:nA0,nB0,nR0

attheendofreaction:nA

,nB

,nR

Theratio

Foranycomponenti,

ni

ni

0=i

(1.3)IfcomponentiinvolvesinMreactions,isapositiveconstant,=

(1.2)theextentofreaction.(1.4)1.2.2ConversionInitialcondition:continuousatthe

inletofthereactorbatch

atthebeginningofthereactionItisthefractionofareactantconverted,amountofreactantconverted

initial

amountofthereactantX=(1.5)Conversion:Calculationsareusuallybasedontheconversionofkeycomponent,e.g.,Aisusuallythemostexpensivereactant,soitsamountinthemixtureislimited.thevalueofXreflectstheeconomy;themaximumvalueofXis100%.amountofreactantconverted

initial

amountofthereactantX=(1.5)TherelationbetweenconversionXand

is

(1.6)1.2.3Yieldandselectivity

TheyieldisdefinedforreactionproductR,whereAisusuallythekeycomponent.amountofRformed

initialamountofA

(1.7)orYR=

molesofAconsumedforR

molesofAfedtothesystem(1.8)Formultiplereactions,theselectivityisoftenused,definedas(1.11)TherelationbetweenconversionX,yieldY,andselectivitySis

Y=SX(1.12)S=molesofAconsumedfordesiredproduct

molesofAconvertedExample1.2

inlet

outlet

C2H41515x

y/2O277x/23y/2

C2H4O0xCO21010+yH2O0

y

Ar

1212

N2

56

56.

total100100x/2Theequationsforconcentrationsattheexit:

ethyleneoxygenx,y

separationrawmaterialsproductsreactorrecycleConversion:单程转化率separationrawmaterialsproductsreactorrecycle全程转化率amountofreactantconverted

initial

amountofthereactantX=(1.5)Exercises:Chap.1:1,21.3ClassificationofReactionsandReactors1.3.1Classificationofreactions

homogeneoussystems:

gas,liquidheterogeneoussystems:

gas-solid,gas-liquid,liquid-liquid,liquid-solid,gas-liquid-solid

1.3.2TypesofreactorsAccordingtotheconstructionofreactors,wehave(1)tubularreactor

(2)stirredtankreactor(3)towerreactorGLGLGLGLplatetowerpackedtowerbubblecolumnspraytower(4)fixedbedreactorpackedtubularreactor(5)fluidizedbedreactor

G(L)G(6)movingbedreactorSG(7)tricklebedreactorL

G1.4ModeofOperation1.Batchoperation

nomaterialentersorleavesthereactorduringreaction.

Feature:

closing

usuallyconstant-volume

unsteady-state

cRcAtcA00Itisusuallyinastirredtankreactorforslowreactionandsmallamountofoutput.reactionA

R:2.Continuousoperationreactantsenterandproductsleavethereactorcontinuously.

Feature:

open

steady-state

usuallyconstantpressureLz0cALcRLcRcAcA0e.g.,reactionA

Rinatubularreactor:3.Semi-batchoperation

Atleastoneofthereactantsorproductsisfedinortakenoutcontinuously,andothersarechargedordischargedinbatchmode,whichmaybeusedtotreatagaswithaliquid,tocontrolahighlyexothermicreaction,toimproveproductyield.1.5DesignandScale-upofReactorsObjectives:selectthetypeofreactordeterminetheoptimumoperatingconditiondeterminethesizeofreactor1.5.1Generalprocedureforreactordesign

Generalrequirements:

inchemistry:sufficientreactiontime

inmasstransfer:

inheattransfer:

insafety:Generalprocedure:(1)forallreactions,collectthedataonkineticsandthermodynamicsundertheoperatingcondition;(2)collectthephysicalpropertiesneeded;(3)determinetheratecontrollingprocessandselectthetypeofreactor;(4)determinetheoperatingcondition;(5)calculatethesizeofreactor;(6)selectappropriateconstructionmaterial;(7)carryoutinitialmechanicaldesign;(8)evaluatethecapitalandoperationcostsofvariousdesignsandassesstheeconomicoptimumdesign.1.5.2BasicequationsforreactordesignreactorsizeV

rateofreactionrA(c,T,p)

c,T,p=f(x,y,z,t)Basicequations:(1)materialbalanceforanycomponent

ci

(x,y,z,t)(2)energybalance

T(x,y,z,t)(