CRE LAB.pptx

8/9/2019 CRE LAB.pptx

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What ischemical

reactionengineering?

Chemistrydealing

withchemicalreactors


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Chemical Reaction Engineering

Chemical reaction engineering(reaction engineering or reactor

engineering) is a secialty inchemical engineering or industrialchemistry dealing with Chemical

Reactors! "re#uently the termrelates seci$cally to catalyticreaction systems where either aHomogeneous or HeterogeneousCatal stis resent in the reactor!


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Origin of Chemical Reaction

EngineeringChemical reactionengineering as a disciline started in the

early 1950s under theimulse o% researchers at the

&hell 'msterdam researchcenter and the niersity o%*el%t! The term chemicalreaction engineering wasaarently coined +y J.C.Vlugter while rearing the1st Euroean &ymosium onChemical ,eactionEngineering which was heldin 'msterdam in 15.!


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'/ o%

C!,!E

Chemical reactionengineering aims atstudying and

otimiing chemicalreactionsin order tode$ne the +estreactordesign!Hence theinteractions o% owhenomenamasstrans%er heattrans%er andreaction 4ineticsareo% rime imortance

in order to relatereactor er%ormanceto %eed comositionand oeratingconditions!


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,eaction ,ateThe reactionrate(rate o%reaction) or speedofreaction %or a reactantor

productin a articularreactionis intuitiely de$nedas how %ast or slow a reactionta4es lace! "or eamle theoidatie rusting o% iron under

EarthAtmosphereis a slowreaction that can ta4e manyyears +ut the com+ustion o%cellulosein a $re is areaction that ta4es lace in%ractions o% a second!


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Iron

Rusting

/ron,usting hasa lowreaction

rate


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WoodCombustion

6oodcom+ustionhas a highreaction

rate! Thisrocess is%ast!


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Rate of Reaction

The rate of reaction r is de$nedto +e the sloe o% the

concentration-time lot %or asecies diided +y thestoichiometric coe7cient o% thatsecies! 'dditionally i% thesecies is a reactant thenegatie alue o% the sloe isused +ecause the slo e is


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Reaction TypesCatalysis Reaction

First Order Reaction

Second Order Reaction

ero Order Reaction

Homogeneous Reaction

Heterogeneous Reaction


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First Order Reaction/% a reaction rate deends on a single reactant

and the alue o% the eonent is one then thereaction is said to +e $rst order! /n organicchemistry the class o% SN1(nucleohilic

su+stitution unimolecular) reactions consists

o% $rst-order reactions! "or eamle

in thereaction o% aryldiaonium ions withnucleohiles in a#ueous solution ArN

!! "#

$ Ar" ! N the rate e#uation is r%

!&ArN!' where 'r indicates an aryl grou!


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Second Order

Reaction ' reaction is said to +e second order when

the oerall order is two! The rate o% asecond-order reaction may +e roortionalto one concentration s#uared or (morecommonly) to the roduct o% two

concentrations ! r %(&A'&)''s an eamleo% the $rst tye the reaction NO! CO $

NO ! COis second-order in the reactant

892and ero order in the reactant C9!


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:ero 9rder ,eaction "or zero-orderreactions the reaction rate isindeendent o% the concentration o% areactant so that changing its concentrationhas no e;ect on the seed o% the reaction!

This is true %or many enyme-catalyedreactions roided that the reactantconcentration is much greater than the

enyme concentration which controls the rate!"or eamle the +iological oidation o%ethanol to acetaldehyde +y the enyme lieralcohol dehydrogenase (


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*omogeneous

Reaction /n homogenous reaction

all thecomonents=reactantsta4ing art in the reaction

%orm one single hase withthe reaction occurring in

the +ul4 o% this system!


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*eterogeneous

Reaction

/n heterogeneous reaction all thecomonents=reactants ta4ingart in the reaction are indi;erent hases with thereaction occurring +etween thedelimiting sur%ace o% the

comonents=reactants!


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Reactors +sed

"ollowingreactors

are>-


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)atchReactor

generic term %or a tye o%essel widely used in therocess industries! 'tyical +atch reactorconsists o% a tan4 with anagitator and integral

heating=cooling system!These essels may ary insie %rom less than 1 litreto more than 15000litres! They are usually%a+ricated in steel

stainless steel glass linedsteel glass or eotic alloy


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Semi,batch Reactor

Semibatch(semiow)reactors oerate much li4e

+atch reactorsin that theyta4e lace in a single stirredtan4 with similar e#uiment!Howeer they are modi$edto allow reactant addition

and=or roduct remoal intime! ' normal +atch reactoris $lled with reactants in asingle stirred tan4 at time@0and the reaction roceeds! 'semi+atch reactor howeer

allows artial $lling o%reactants with the ei+ilityo% adding more as timerogresses!


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on nuous rre , anReactor

The continuous .o/ stirred,tan(reactor(CS-R) also 4nown asat- or +ac4mi reactor is acommon ideal reactortye in

chemical engineering! ' C&T,

o%ten re%ers to a model used toestimate the 4ey unit oeration

aria+les when using a continuous

agitated-tan4 reactor to reach aseci$ed outut!The C/&T, model

is o%ten used to simli%yengineering calculations and can+e used to descri+e research

reactors! /n ractice it can only +earoached in articular in

industrial sie reactors!


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Alug "low ,eactorThe plug .o/ reactor (0FRsometimes called continuoustubularreactor C-R orpiston.o/reactors) is a

model used to descri+echemical reactionsincontinuous owing systemso% cylindrical geometry! TheA", model is used to redict

the +ehaiour o% chemicalreactorso% such design sothat 4ey reactor aria+lessuch as the dimensions o% thereactor can +e estimated!


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-han(s

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CRE LAB.pptx