REACTOR DESIGN

WHAT IS REACTOR? Chemical reactors are vessels that are designed for a chemical reaction to occur inside of them

Types of VesselsTank reactor A tank that is usually enclosed to keep contaminants out of the reaction vessel, or envelope Tubular reactor A pipe or tube

Selection Criteria of ReactorConversion SelectivityProductivityYield Heat exchange MixingCatalyst DistributionHold-up TimeAvailabilityEnergy utilizationSafetyEconomics

MODE OF REACTION 1. BATCH 2. CONTINUOUS

MODE OF OPERATION BATCH 1.HANDLE SMALL QUANTITIES

2. LARGE RESIDENCE TIMECONTINUOUS1.HANDLE LARGE QUANTITIES

2.SHORT RESIDENCE TIME

PHASES IN CONTACT GAS-LIQUID FOR THIS PURPOSE REACTORS USED ARE 1.BATCH STIRRED TANK REACTOR 2. CSTR 3. TUBULAR REACTOR

Why I choose Semi Batch Stirred Tank Reactor?Mixing of ReactantsGood Temperature ControlHigh heat and mass transfer efficienciesUseful for slow reactions requiring large hold up timeUniformDistribution of CatalystFor Liquid-Gas system ControlLess Man power requirements

DESIGNING

General design considerations for the reactor is Rate of reactionResidence time Volume of reactor Power consumption Molecular weightChain Diameter Chain Length

DESIGN PROCEDURE FOR REACTOR

Calculate molar flow rate from given mass flow ratesCalculate volumetric flow rate from molar flow rateCalculate initial concentration from volumetric flow rate Calculate the concentration for given conversion Calculate the rate of reaction by the given kinetic equationCalculate the residence time Calculate the reactor volumeCalculate the actual volume of reactorCalculate the dimension of reactor Calculate the power

GIVEN DATA

Flow rate of ETHYLENE entered6439 Kg/hrFlow rate of CATALYST entered0.631 Kg/hrFlow rate of HYDROGEN entered6.31 Kg/hrFlow rate of SOLVENT entered92.4 Kg/hrDensity of ETHYLENE0.0892 Kg/dm3Density of CATALYST0.96 Kg/dm3Temperature of Reactor85CoPressure inside the Reactor8 atmConversion98%

Rate Equation

kp9.21/seckfm0.211/seckt0.21 dm3/mol.secki14.61/secK10.031/secK20.031/sec

CALCULATION OF PARAMETERS

Molar flow rate

molar. Flow rate = mass. Flow rate / mol.wtSoMolar flow rate of Ethylene = 229973.6 mol / hr Molar flow rate of catalyst = 4.635 mol / hr

Volumetric flow rate :

Vol. flow rate= mass flow rate / Density SoVolumetric flow rate of Ethylene 72189.01 dm3/ hrVolumetric flow rate of Catalyst 0.668421 dm3/ hr

Initial Concentration:

CAo=molar flow rate/Vol. Flow rate

Initial Concentration of Ethylene 3.1857mol/dm3Initial Concentration of Catalyst 6.934 mol/dm3

Concentration at given Conversion:CA=CAO(1-XA) As given conversion is 98% SoConcentration of Ethylene=0.026218mol/dm3Concentration of Catalyst=0.0571 mol/dm3

Rate of reaction: Rate Equation

By putting the values we get - rp=0.002874mol/dm3min

Residence Time: As for CSTR

So, =192.6 min =3.214 hrs

Reactor Volume: V= *VFRSoV=232.0426m3 There are two reactors in series and the ratio of their residence time is given in literature.2.09 So, Reactor Volume of the 1st reactor=157.56m3 Reactor Volume of the 2nd reactor=74.49m3

CHAIN LENGTH: AsL=M(Lo/Mo)SoL=5.46*10-6 m

CHAIN DIAMETRE As D=(4/(Lo/Mo)-1*(*6.02*10-26)-1)So D=5.5*10-6m

Reference: PREDICTIVE MODELING OF METAL-CATALYZEDPOLYOLEFIN PROCESSESByNeeraj Prasad Khare

Specification Sheet

Continued