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MULTI-PHASE AND CATALYTIC CHEMICAL MULTI-PHASE AND CATALYTIC CHEMICAL REACTORS DESIGN SIMULATION TOOLREACTORS DESIGN SIMULATION TOOL

Jack R. HopperJack R. HopperJamal M. SalehJamal M. Saleh

Sandeep WaghchoureSandeep WaghchoureSandesh C. HegdeSandesh C. Hegde

Niraj RamachandranNiraj RamachandranLamar University, Beaumont, TX 77710Lamar University, Beaumont, TX 77710

Ralph W. PikeRalph W. PikeLouisiana State UniversityLouisiana State UniversityBaton Rouge, LA 70803Baton Rouge, LA 70803

Overview of Advanced Process Analysis SystemOverview of Advanced Process Analysis System

Process control Process Modification

Advanced Process Analysis System

On-Line Optimization

Flowsheet Simulation Reactor Analysis Pinch Analysis Pollution Index

OBJECTIVEOBJECTIVE

To develop a User Friendly Simulation Package for multi-phase catalytic and non-catalytic reactor analysis as a component for the Advanced On-line Process Analysis System for Pollution Prevention

REACAT REACTOR SIMULATION TOOL REACAT REACTOR SIMULATION TOOL FEATURESFEATURES

User Friendly input/ output interface Graphical and Tabular Data Output Extensive Selection of Reactor Models Component Material Balances for Gas, Liquid and

Catalyst Phase Total Energy Balance Prediction of reactor hydrodynamics such as

pressure drop, power consumption, catalyst wetting

factor and flow regimes Reactor Models with numerous Options

Classification of Homogeneous and Heterogeneous Reactor Models

REACTION PHASE REACTOR MODEL

Homogeneous Plug Flow, CSTR, Batch

Heterogeneous:-

CatalyticTwo Phase

Gas-Catalyst orLiquid-Catalyst

Three PhaseGas-Liquid-Catalyst

Non-Catalytic

Gas-Liquid

Packed-Bed or Fluidized-Bed

Trickle-bed, Bubble Fixed-BedCSTR Slurry, Bubble Slurry,3-Phase Fluidized

Gas-Liquid CSTR, Gas-LiquidBubble Column

Reactor Definitions

•Catalytic Packed Bed: Gas or Liquid Reactants flow over a fixed bed of catalysts.

•Catalytic Fluidized Bed: The up-flow gas or liquid phase suspends the fine catalyst particles.

•CSTR Gas-Liquid: Liquid and gas phases are mechanically agitated

•Bubble Gas-Liquid Bed: Liquid phase is agitated by the bubble rise of the gas phase. Liquid phase is continuous.

Reactor Definitions (Contd..)

•Trickle-Bed: Concurrent down-flow of gas and liquid over a fixed-bed of catalyst. Liquid trickles down, while gas phase is continuous

•Bubble-Fixed Bed: Concurrent up-flow of gas and liquid. Catalyst bed is completely immersed in a continuous liquid flow while gas rises as bubbles.

•CSTR Slurry: Mechanically agitated gas-liquid-catalyst reactor. The Fine catalyst particles are suspended in the liquid phase by means of agitation. (Batch liquid phase may also be used)

•Bubble Slurry Column: Liquid is agitated by means of the dispersed gas bubbles. Gas bubble provides the momentum to suspend the catalyst particles. •Three-Phase Fluidized Bed: Catalyst particles are fluidized by an upward liquid flow while gas phase rises in a dispersed bubble regime.

Reactor Types Included in the Reactor Simulation Tool, ReaCat

Plug Flow

CSTRBatch

Homogeneous Reactors:

Reactor Types Included in the Reactor Simulation Tool, ReaCat (Contd..)

Gas /Liquid Catalytic Reactors

Fixed Bed

Fluidized Bed

Gas-Liquid Reactors

Gas

Liquid

Gas-Liquid CSTR

Liquid

Gas

Gas-Liquid Bubble Column

Two-Phase Reactors:

Reactor Types Included in the Reactor Simulation Tool, ReaCat (Contd..)

Three-Phase Reactors:Three Phase Catalytic Reactors

Liquid

Liquid Liquid Liquid

Gas

Gas Gas Gas

Gas

Liquid

Cocurrent Downflow Trickle Bed

Cocurrent Upflow Packed Bed

Bubble Slurry Column

Three-Phase Fluidized Column

Gas-Liquid Catalytic CSTR Slurry Reactor

REACTION RATE MODEL OPTIONS

Power-law reaction rate or Langmuir- Hinshelwood model to account for the adsorption effects.

Correlations to estimate the external mass transfer effects and dispersion coefficients

Catalytic effectiveness factor estimation to account for intra-particle resistance

Flow Regime Options

Isothermal and non-isothermal/non-adiabatic conditions

Multi-reaction systems with up to 30 reactions and 36

components

Industrial Examples of Multi-phase and Catalytic Reactors

Catalytic Gas/ Liquid Fluidized-bed Reactor

• Fluid Catalytic Cracking

• Production of Allyl Chloride.

• Production of Phthalic Anhydride

• Acrilonitrile by the Sohio Process

Catalytic Fixed Bed Reactor

• Partial oxidation of O-xylene to Pthalic Anhydride • Hydrogenation of Aromatics and Olefins

• Dehydrogenation of Ethylbenzene to Styrene

Industrial Examples of Multi-phase and Catalytic Reactors

Three-phase Reactor:

Trickle-BedCatalytic hydro-desulfurizationCatalytic hydrogenationCatalytic hydrocrackingFixed-bed upward bubble-flowFischer-TropschCoal liquefaction CSTR SlurryHydrogenation of fatty oils and unsaturated fats.Hydrogenation of acetoneBubble-Slurry ColumnCatalytic oxidation of olefinLiquid-phase xylene isomerizationThree-phase fluidized BedProduction of calcium acid sulfiteCoal liquefaction, SRC process

Industrial Examples of Multi-phase and Catalytic Reactors

Gas-Liquid Continuous Stirred Tank Reactor:

Oxidation of cyclohexane to adipic acid, cumene to cumene

hydroperoxide, and toluene to benzoic acid.

Absorption of SO3 in H2SO4 for manufacture of Oleum

Absorption of NO2 in water for the production of HNO3

Addition of HBr to alpha olefins for the manufacture of alkyl

bromide.

Addition of HCl to vinyl acetylene for the manufacture of

chlroprene.

Absorption of butenes in sulfuric acid for conversion to

secondary butanol.

Multi-phase Reactors- Advantages and Disadvantages

Advantages Disadvantages

Catalytic FixedBed Reactor

The fluid flow regimesapproach plug flow, sohigh conversion can beachieved.

Pressure drop is low.

Owing to the high hold-up there is better radialmixing and channelingis not encountered.

High catalyst load perunit of reactor volume

The intra-particlediffusionresistance is veryhigh.

Comparatively lowHeat and masstransfer rates

Catalystreplacement isrelatively hard andrequires shutdown.

Multi-phase Reactors- Advantages and Disadvantages

Advantages Disadvantages

Catalytic

Fluidized-bedReactor

The smooth, liquid-like flow of particles

allows continuous controlled operations

with ease of handling.

Near isothermal conditions due to the rapid

mixing of solids.

Small Intra-Particle resistance leads to a

better heat and mass transfer rate.

This violent particle motion of

particles tends to homogenize all

intensive properties of the bed.

Thus it is not generally possible to

provide an axial temperature

gradient which might be highly

desirable in some instances.

Erosion by abrasion of

particles can be serious.

Particle attrition

Three-phase Reactors- Advantages and Disadvantages

Advantages Disadvantages

Trickle-BedReactor

Gas and liquid flow regimesapproach plug flow; highconversion may be achieved.

Large catalyst particle, therefore,catalyst separation is easy.

Low liquid holdup, therefore liquidhomogenous reactions areminimized.

Low pressure drop

Flooding problems are notencountered.

High catalyst load per unit reactorvolume.

Poor distribution of theliquid-phase

Partial wetting of the catalyst

High intra-particle resistance

Poor radial mixing

Temperature control isdifficult for highly exothermicreactions

Low gas-liquid interactiondecreases mass transfercoefficients.

Three -phase Reactors- Advantages and Disadvantages

Advantages Disadvantages

BubbleFixed- BedReactor

High liquid holdup,therefore, catalyst arecompletely wetted, bettertemperature control, and nochanneling problems.

Gas-liquid mass transfer ishigher than in Trickle beddue to higher gas-liquidinteraction.

Axial back mixing ishigher than trickle-beds, conversion islower.

Feasibility of liquid sidehomogeneousreactions

Pressure drop is high

Flooding problems mayoccur.

Three -phase Reactors- Advantages and Disadvantages

Advantages Disadvantages

Slurry and3-phase FluidizedReactor

Ease of heatrecovery andtemperaturecontrol.

Ease of catalystsupply andregenerationprocess.

Low intra-particleresistance.

High external Mass transfer rate (Gas-liquid and Liquid Solid)

Axial mixing isvery high

Catalystseparation mayrequire filtration.

High liquid to solidratio may promoteliquid sidereactions.

Low catalyst load.

Multi-phase Reactors- Advantages and Disadvantages

Advantages Disadvantages

Gas LiquidContinuousStirredTankReactor

Very effective for viscousliquids and at very low gasrates and large liquid volumes.

Best for system with largeheat effects because ofsuperior heat transfercharacteristics.

Useful for slow reactionsrequiring high liquid holdup.

Residence time of liquid and extent of agitation can be easily varied.

Both liquid and gas phase are almost completely backmixed.

High power consumption per unit volume of the fluid.

Sealing and stability of Shaft in tall reactors.

Comparison of Three Phase Trickle- Bed and Bubble Fixed Bed Reactors

Characteristics Trickle- Beds Bubble Fixed-Beds

Pressure Drop Channeling at low liquidflow rates

No Liquid flowmaldistribution

Heat Control Relatively Difficult Easy

Radial mixing Poor radial mixing Good mixing

Liquid/Solid ratio Low High

Catalyst Wetting Partial wetting is possible Completewetting

Conversion High Poor due toback mixing

Comparison of Three Phase Suspended Bed Reactors

Characteristic CSTR Slurry Bubble Slurry Three- phaseFluidized

Catalyst Attrition Significant Insignificant Insignificant

Mass and HeatTransferEfficiencies

Highest High High

MechanicalDesign

Difficult Simple Simple

CatalystSeparation

Easy Easy Easiest

PowerConsumption

Highest Intermediate Lowest

CatalystDistribution

Uniform Nonuniformitymay exist

Nonuniformitymay exist

Gas-Liquid-Solid Contact in Three-phase Reactors

External Diffusion

InternalDiffusion

Catalytic Surface

Bubble Particle

Theory of Catalytic Gas- Liquid Reactions

A(G) + B(L) C

Gaseous reactant A reacts with non-volatile liquid reactant B on solid catalyst sites.

Mechanism Of Three- Phase Reactions:-Mass Transfer of component A from bulk gas to gas-liquid

interfaceMass transfer of component A from gas-liquid interface to bulk

liquidMass transfer of A& B from bulk liquid to catalyst surfaceIntraparticle diffusion of species A& B through the catalyst pores

to active sites.Adsorption of both or one of the reactant species on catalyst

active sitesSurface reaction involving at least one or both of the adsorbed

speciesDesorption of products, reverse of forward steps .

Common Flow Regimes in Industrial Catalytic Gas- Liquid Reactors

Catalytic Gas-Liquid Reactor Common Flow Regime

Cocurrent Down-Flow Fixed-Bed

Trickle-Flow

Cocurrent Up- Flow Fixed-Bed Bubble- Flow

Bubble Column Slurry Reactor Homogeneous Bubble- Flow

Three- phase Fluidized- Bed Bubble- Flow

Design Models For Catalytic Gas- Liquid Reactors

Flow Regime Gas-phaseDesign Model

Liquid- PhaseDesign- Model

Trickle FlowCocurrentDown-Flow Fixed-Bed

Dispersion Dispersion

CSTR Slurry, Continuous or Semi-Batch

CSTR CSTR/ Batch

Homogeneous Bubble- Flow ContinuousBubble ColumnSlurry Reactor

Dispersion Dispersion

Homogeneous Bubble- Flow Semi-Batch Bubble Column Slurry

Dispersion Batch

Bubble FlowThree- phase Fluidized Bed

Dispersion Dispersion

Correlations Used for the Three-Phase Catalytic Reactors

Correlation Trickle-Bed Fixed Up-Flow CSTR Slurry Bubble Slurry 3-PhaseFluidized

Pressure drop Larkins et al.1961Ellman et al.1988

Turpin &Hintington 1967 - - -

L & G Holdup Sato et al. 1973Ellman et al.1989

Fukushima &Kuasaka 1979Achwal &Stepanek 1976

Galderbank1958Yung et al.1979

Yamashita &Inoue 1975Maselkar 1970

Kim et al.1975

L-S MassTrans. Coeff.

Van Krevelen1948Dharwadker &Sylvester 1977

Specchia et al.1978

Sano et al.1947

Kobayashi &Saito 1965

Lee et. Al1974

L DispersionCoeff.

Michell &Furzer 1972

Stiegel & Shah1977 -

Deckwer etal.1974

El-Temtamy1979

G DispersionCoeff.

Hochman &Effron 1969 - -

Mangartz &Pilhofer 1981 -

Wall HeatTransf. Coeff.

Baldi 1979- -

Fair 1967 -

PowerConsumption - -

Luong &Volesky 1979Michel andMiller 1962

- -

Correlations Used for the 2-Phase Reactors

Gas Liquid Continuous Stirred Tank Reactor

1. Maximum Gas Flow rate (QGmax) – Zwietering (1963)

2. Bubble diameter (db) – Van Dierendonck (1970)

3. Gas holdup (G) - Van Dierendonck (1970)

4. Liquid side Mass transfer coefficient (kL) – Van Dierendonck (1970)

5. Liquid side Mass transfer coefficient (kL) for single bubbles - Hughmark(1971)

Catalytic Liquid Fluidized Bed

Mass Transfer Coefficient (KL) – Chu, Kalil and Wetteroth (1953)

Catalytic Gas Fluidized bed

1. Voidage at Minimum Fluidization (mf) – Broadhurst and Becker (1975)

2. Velocity at Minimum fluidization (Umf) – Kunii and Levenspiel (1969 )

3. Bubble Diameter (DB)- Horio and Nonaka (1984)

4. Mass Transfer Coefficients (KBC and KCE) – Kunni and Levenspiel (1969)

5. Coefficient for Axial Dispersion (DGA) – Yoshida,Kunii and Levenspiel(1969)

Calculation of Catalytic Effectiveness Factor

Catalytic Effectiveness Factor:

where- Thiele Modulus

1st order reaction rate:

Spherical Pellet

Cylindrical Pellet

Slab Pellet

)313(1 Coth

DepkSaR /3

DepkSaR /2

DepkSaL /

Catalytic Fixed-Bed Reactor - Design Model

Mass Balance around the catalyst

Gas-Phase component mass balance (Plug Flow model)

Gas-Phase component mass balance (Dispersion model)

Energy Model

inetSGicc RiCCak )()()(

0.0)()( iSGiccGi

G CCakdzdCU

0.0)()(2

2

iSGiccGi

GGi

G CCakdzdCU

zdCdiD

)()( TaTUAjHRjdzdTCpU RGGG

Catalytic Gas-Fluidized Bed Reactor- Design Model

Bulk Gas Phase( Bubble Phase):

Plug Flow:-

With Axial Dispersion:

Intermediate(Cloud- Wake) Phase:

Catalyst (Emulsion) Phase:

Energy Balance:

)( icibBCib

b CCKdZ

dCU

)(2

2

icibBCib

bib

ga CCKdZ

dCU

dZ

CdD

)()()( ieicCEeiCloudPhascicibBC CCKRCCK

haseiEmulsionPeieicCE RCCK )()(

)(** Re1

actorambientj

NR

jpgbg TTaUHrRjdZ

dTCU

Catalytic Liquid -Fluidized Bed Reactor-Design Model

Liquid-phase component balance:

Plug Flow:-

(1)

Dispersion:-

(2)

Catalyst (Emulsion) Phase:

(3)

Energy Balance:-

(4)

)( iSiLLiL

L CCKdZ

dCU

)(2

2

iSiLLiL

LiL

La CCKdZ

dCU

dZ

CdD

haseiCatalystPiSiLL RCCK )()(

)(** Re1

actorambientj

NR

jpLLL TTaUHrRjdZ

dTCU

Gas-Liquid Agitated Tank- Design Model

Gas-phase Component Mass Balance:

or

(1)

Liquid-phase Volatile-Component Mass Balance:

(2)

Liquid-phase Non-Volatile-Component Mass Balance:

(3)

Energy Balance:

0)/(**))(/( Lio

io

LRio

ii

G CHPaKEVPPRTQ

0)/(**)(/ Lio

LRio

ii

Tgas CHPoiaKEVPPPF

0*)/(**)( RinetLio

io

LRLio

Lii

L VRCHPaKEVCCQ

0*)( RinetLio

Lii

L VRCCQ

0)(*

)]*(*[)](3/)(2/)([ 3322

ToTaAU

RHRVToTiToTiToTiF jjRiiiii

Three-Phase Gas-Liquid Catalytic Reactor- Design Model(Trickle-Bed, Fixed-upflow Bubble-Bed, Bubble Slurry Bed,

3-Phase Fluidized Bed)Non-Volatile Liquid-phase mass balance:

Volatile Liquid-phase mass balance:

Boundary Conditions:

At Z=0

At Z=L

Gas-phase mass balance:

Component mass balance around the catalyst:

0.0)()( ,,,

2,

2

, iSiLicciL

LiL

iL CCaKdzdCU

dzCdD

0.0)()()()( ,,,,,

2,

2

, iSiLicciLig

igLiL

LiL

iL CCaKCHiCaK

dzdCU

dzCdD

)( ,,,

, iLi

iLLiL

iL CCUdzdCD

0, dzdC iL

0.0)()( ,,, iLi

igigL

igg C

HCaK

dzdCU

0.0)()( ,,, iLi

igigL

igg C

HCaK

dzdCU

Three-Phase Gas-Liquid Catalytic Reactor- Design Model (CSTR Slurry)

Non-Volatile Component Liquid-phase mass balance:

(1)

Non-Volatile Component Liquid-phase mass balance:

(2)

Gas-phase mass balance:

(3)

Component mass balance around the catalyst:

(4)

0.0)()()( ,,,, iSiLo

iccRiLo

iLi

L CCakVCCQ

0.0)()()()()( ,,,,

,, iSiLo

iccRiLoig

o

igLRiLo

iLi

L CCakVCHiCaKVCCQ

0.0))()( ,,

(,, iLoiG

o

igLRiGo

iGi

G CHiCakVCCQ

)()()( ,, iRiSiLo

iccR rVCCaKV

ReaCat Start up screen

Reaction Reaction Phase Menu

Reactor Type Reactor Type Menu

Inlet Temperature and Pressure, Energy Model Selection

Physical Properties of Components

Reaction Stoichiometry

Rate Law

Reaction Rate Constant

Reactor Specifications

Run

REACTION

Reaction Phase Menu

REACTOR TYPE

Reactor Type Menu

Global Options

Physical Properties

Reaction Stoichiometry

Reaction Rate

Rate Constant

Reactor Specifications

Feed Composition Input

Heat Transfer Data for Non-isothermal cases

Graphical Output of the ReaCat Program

Reactor Flow-Sheeting

ReaCat, Test Cases Catalytic Gas Fluidized Bed

Multiple reaction system for the production of Phthalic Anhydride from naphthalene.

“Fluidization Engineering”; Kunii and Levenspiel.(1991, Butterworth- Heinman, P 298)

Literature ReaCat (1) ReaCat (2) ReaCat(2)

Plug Flow Plug Flow Plug Flow Dispersion

Conversion 97% 94.93 % 85.49% 81.26%

(1) – Experimental bubble diameter values has been used by the program

(2) – The correlation of Horio and Nonaka (1984) has been used to find the bubble

diameter.

ReaCat, Test Cases

Continuous Gas-Liquid Stirred Tank Reactor

Liquid phase oxidation of o-xylene into o-methylbenzoic acid

by means of air.

Chemical Reactor Analysis and Design; G.F.Froment and

K.B. Bischoff (1979)

Literature ReaCat

Conversion 83.39% 83.95%

ReaCat, Test Cases

Trickle-Bed

Liquid-phase oxidation of formic acid in the presence of CuO.ZnO

catalyst; Baldi et. Al. 1974, Goto and Smith (1975)

Experimental ReaCat (plug flow) ReaCat (Dispersion)

Conversion 88.5 % 91.0% 89.8 %

ReaCat, Test Cases

Continuous Catalytic Gas-Liquid Slurry Stirred TankReactor

Hydrogenation of Aniline to Cyclohexylamine (Supported Nickel

catalyst)

(Govindrao and Murthy, 1975; Ramachandran and Chaudari 1983 p.

303

Literature ReaCat

Reactor Volume 98 Liter 99 Liter

(46 % conversion of Aniline)

ReaCat, Test Cases

Semi-Batch Catalytic Gas-Liquid Slurry Stirred Tank Reactor

Butynediol Synthesis by the reaction of gaseous acetylene withaqueous formaldehyde in the presence of copper acetylide catalysts.; Kale et. Al (1981)

Experimental ReaCat (1) ReaCat (2)

Conversion 62 % 61.0% 68.5 %

1) Adsorption at catalyst surface is taken into account by the program2) No adsorption effects

Sulfuric Acid Production by Contact Process

SO2 + ½ O2 SO3

2/1

22

312

32'2/1

21'

2/12

'2

'

2OP

SOP

PK

SOP

SODP

SOCP

OBPA

OP

SoP

SOr

Where,PSO2, PO2,PSO3 = Interfacial Partial Pressures of SO2, O2

and SO3 (atm)

P' denotes partial pressures of SO2 and O2 at zeroconversion under total pressure at the point in thereactor(atm)

KP = Thermodynamic Equilibrium Constant, atm-1/2

Log10KP = 5129/T – 4.869 T in oK

Constants A,B,C,D are functions of temperature.

Parameters and Operating Conditions for the Sulfuric Acid Contact Process

Inlet Temperature 787 oFInlet Pressure 19.4 PsiaViscosity 0.09 lb/ft.hr

Reactor Dimensions:Diameter 2.453 ftLength 44 ftVolumetric Flow Rate ( SCFM) 5439.174

Inlet Partial Pressures (Psia):S02 11.08O2 7.958SO3 0.362

Catalyst Properties:Density 33.8 lb/ft3Particle Diameter 0.0405 ftBed Voidage 0.45

Graph of Temperature v/s Tube Length for Contact Process

Graph of Concentration v/s Tube Length for Contact

Process

Graph of Conversion v/s Tube Length for the Contact Process

SO2 Conversion v/s Inlet Temperature

0

0.1

0.2

0.3

0.4

0.5

0.6

700 750 800 850 900 950 1000

INLET TEMPERATURE (F)

SO

2 C

ON

VE

RS

ION

CONVERSION

SO2 Conversion v/s Inlet Flowrate

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

3000 3500 4000 4500 5000 5500 6000

INLET FLOWRATE (SCFM)

SO

2 C

ON

VE

RS

ION

conversion

CONCLUSIONCONCLUSION

A Package for multi-phase catalytic and non-catalytic reactors has been developed which demonstrates the capability to handle complex Material and Energy Balances and associated correlations.

Features to Be Added:-

Add a utility to perform reaction rate optimization. This is very useful when reaction rate is not known.

Build a kinetic database of specific industries such as Sulfuric Acid and Ammonium Phosphate.