cfd for process industry 051505-revised[1] · computational combustion for the process industry...

Computational Combustion for the PetroChemical

Process Industry

AlionAlion Science & TechnologyScience & Technology““ACCESACCES””

AAdvanced dvanced CCombustion and ombustion and CChemical hemical EEngineering ngineering SSolutions olutions

Tulsa, OKTulsa, OK

Computational Combustion for the Process Industry

OUTLINEOUTLINE

Introduction to ACCESIntroduction to ACCESReactive Flow AnalysisReactive Flow AnalysisDetailed Kinetics and Mixing modelsDetailed Kinetics and Mixing modelsExamplesExamplesConclusions and SummaryConclusions and Summary


ACCES: Part of the ACCES: Part of the AlionAlion TeamTeamPractical Problem Solving for the Process IndustryPractical Problem Solving for the Process Industry

Joseph D. Smith, Ph.D. (Brigham Young)Joseph D. Smith, Ph.D. (Brigham Young)Turbulent reactive flows (Dow ChemicalTurbulent reactive flows (Dow Chemical--gasification, incinerators, gasification, incinerators, CabotCabot--fumed metal oxides, John Zinkfumed metal oxides, John Zink--process heaters, flares, process heaters, flares, incinerators)incinerators)

Eric Hixson, P.E. (Iowa State)Eric Hixson, P.E. (Iowa State)Inorganic & organic chemical production (Dow ChemicalInorganic & organic chemical production (Dow Chemical--organic organic chemicals, incineration, FMCchemicals, incineration, FMC--inorganic chemicals, AEinorganic chemicals, AE--StaleyStaley--biochemicalsbiochemicals, Bayer, Bayer--biochemicalsbiochemicals, Cabot, Cabot--aerogelsaerogels, fumed metal , fumed metal oxides, John Zinkoxides, John Zink--process heaters, incinerators)process heaters, incinerators)

Larry Berg, M.S. (MIT)Larry Berg, M.S. (MIT)Design/Application of Combustion equipment for Process Industry Design/Application of Combustion equipment for Process Industry (John Zink); Engineering Solutions for NOx retrofits of Coal fir(John Zink); Engineering Solutions for NOx retrofits of Coal fired ed Power Generation (RJM)Power Generation (RJM)

Mike Mike FardFard, M.S. (, M.S. (UnivUniv of Tulsa)of Tulsa)Technology Development/application to LNG, Upstream productionTechnology Development/application to LNG, Upstream production


Group’s Relevant ExperienceGroup’s Relevant Experience60+ years Hands60+ years Hands--On experience in CPI/HPIOn experience in CPI/HPIPractical, applied solutions using advanced CFD toolsPractical, applied solutions using advanced CFD toolsProven track record in Chemical and Petrochemical Proven track record in Chemical and Petrochemical industryindustry

Key Achievements by Group MembersKey Achievements by Group MembersAdvanced optimization of Industrial Incineration SystemsAdvanced optimization of Industrial Incineration SystemsLead CFD Groups for Dow Chemical and Koch Lead CFD Groups for Dow Chemical and Koch IndustriesIndustriesDeveloped/Patented advanced process equipment for gas Developed/Patented advanced process equipment for gas flares and flare pilots, industrial drying ovens, HAZflares and flare pilots, industrial drying ovens, HAZ--Waste incinerators, BioWaste incinerators, Bio--chemical reactorschemical reactors

Background: Background: Who are we?Who are we?


We addWe add value by:value by:Providing advanced engineering analysis ofProviding advanced engineering analysis of

CoalCoal--fired Electric Power Generation fired Electric Power Generation

Gas flares (air assist, steam assist, multiGas flares (air assist, steam assist, multi--tip, enclosed)tip, enclosed)

PyrolysisPyrolysis furnacesfurnaces

Low NOLow NOxx burnersburners

HazHaz--waste incineratorswaste incinerators

Specialized Reaction Engineering expertise Specialized Reaction Engineering expertise Coal combustionCoal combustion

ChloroChloro--hydrocarbon chemistryhydrocarbon chemistry

Hydrocarbon ProductionHydrocarbon Production

Fumed metal oxidesFumed metal oxides

BioBio--Chemical ProcessingChemical Processing


We Can Help you:We Can Help you:Meet tighter environmental regulationsMeet tighter environmental regulations

NOx, CO, NOx, CO, PIC’sPIC’s

Identify “best” design to meet your needsIdentify “best” design to meet your needsBurners, turbines, nozzles, reactors, etc.Burners, turbines, nozzles, reactors, etc.

DeDe--bottleneck and/or optimize existing systemsbottleneck and/or optimize existing systemsYield, Quality, Safety, Production, etc.Yield, Quality, Safety, Production, etc.

Reduce downtime when retrofitting new Reduce downtime when retrofitting new technology into existing systemtechnology into existing system

Shorten down time for Plant turnaround when installing new Low Shorten down time for Plant turnaround when installing new Low NOx Burners into operating furnaceNOx Burners into operating furnace


Computational CombustionComputational CombustionGrowing Impact of CFDGrowing Impact of CFD

Validation critical (Lab and Plant)Validation critical (Lab and Plant)

Start with known Base CaseStart with known Base Case

Identify trends vs. exact valuesIdentify trends vs. exact values

Improves Bottom line (operating costs, yield, quality, and safetImproves Bottom line (operating costs, yield, quality, and safety)y)

Best done handBest done hand--inin--hand with Experimenthand with ExperimentFocus testing on “best” design options Focus testing on “best” design options -- reduce experimental costsreduce experimental costs

Shorten development cycle/reduce development costShorten development cycle/reduce development cost

Industry uses what’s available & WORKS (e.g., Industry uses what’s available & WORKS (e.g., Correlation, spreadsheet, CFD, etc.)Correlation, spreadsheet, CFD, etc.)

Bridges gap between Theory & PracticeBridges gap between Theory & Practice


SecondaryAir w/ Swirl

Fuel &Primary Air

Physics of Combustion AnalysisPhysics of Combustion Analysis

4 Heat Transfer - gas recirculation, heat transfer, participating media

CoolWalls

Quarl

4

Cool

Cool

1 Free shear layer - mixing of fuel and oxidizer, hot gas recirculation on centerline

1

3

Fluid Mechanics- plug flow

3

Hot

Hot2

2 Multiphase –droplet/ particle dispersion, vaporization

Atomizer


Turbulent DispersionWall Deposition

Nucleation/Agglomeration

Particle/Droplet/Surface Reactions(Heterogeneous)

PyrolysisDevolatilization

Vaporization

Particle Mechanics

Computational CombustionComputational Combustion Combines Combines MultiMulti--Physics into CFD Based ToolPhysics into CFD Based Tool

Gaseous Fluid Mechanics

Momentum EquationsEnergy Equation

Turbulence Model

Multi-PhysicsCombustion

Analysis

Gaseous Reactions(Homogeneous)Local Equilibrium

Turbulence CouplingPDF Chemistry

Discrete OrdinatesData for ComparisonRadiative Properties

Heat TransferRadiation

Pollutant Formation(Trace Chemistry)

SOx - Non-EquilibriumNOx - Fuel and Thermal

PIC - Incineration


CFD Includes MultiCFD Includes Multi--physicsphysics•• Fluid MechanicsFluid Mechanics::

All flow regimes All flow regimes –– laminar and turbulentlaminar and turbulentAll fluid types All fluid types –– Newtonian and nonNewtonian and non--NewtonianNewtonianCompressible and incompressibleCompressible and incompressibleSteady state and transientSteady state and transient

•• Heat TransferHeat Transfer::Convection, conduction, radiationConvection, conduction, radiationConjugate heat transferConjugate heat transfer

•• MultiphaseMultiphase::LagrangianLagrangian, , EulerianEulerian, Free Surface, Free SurfaceParticles, sprays, droplets, bubbles, Particles, sprays, droplets, bubbles, cavitationcavitation

•• Chemical ReactionsChemical ReactionsTurbulent Chemistry w/ Detailed KineticsTurbulent Chemistry w/ Detailed Kinetics


Coupling Chemistry to Turbulent Coupling Chemistry to Turbulent FlowFlow


Turbulent Chemistry IssuesTurbulent Chemistry IssuesWhat Turbulent Mixing ModelsWhat Turbulent Mixing Models

Consider mixing time and reaction times: Consider mixing time and reaction times: DDaa = = ττtt//ττcc = (= (lltt/v/v')/ (l')/ (lff//ssLL))DDaa ≈≈ 0 (Frozen); 0 (Frozen); DDaa ≈≈ ∞∞ (Fast); (Fast); DDaa ≈≈ 1 (Coupled)1 (Coupled)

How to couple chemistry & turbulenceHow to couple chemistry & turbulenceResolve flow to micro scale for reactionsResolve flow to micro scale for reactionsCouple fluctuations on macroCouple fluctuations on macro--scale with reactionscale with reaction

Require Detailed Kinetic mechanismRequire Detailed Kinetic mechanismCHCH44 combustion combustion -- GRIMECH (50 species, 350 x2 reactions)GRIMECH (50 species, 350 x2 reactions)

CHCH22ClCl22 combustion combustion -- BozzelliBozzelli mechanism (35 species, 170 x2 reactions)mechanism (35 species, 170 x2 reactions)

Must Reduce Degrees of Freedom for “practical” problemsMust Reduce Degrees of Freedom for “practical” problemsChemical state space (r, H, YChemical state space (r, H, Y11,...,,...,YYnsns) ) ⇒⇒ 2+ns degrees of freedom (2+ns degrees of freedom (dofdof) ) For each DOF, 1 Non linear PDE must be solved over ~10For each DOF, 1 Non linear PDE must be solved over ~1066 grid pointsgrid points

Large disparity in reaction time scales (fast Large disparity in reaction time scales (fast vsvs slow reactions)slow reactions)


Eddy BreakEddy Break--Up Models (EBU & Combined Kinetics/EBU)Up Models (EBU & Combined Kinetics/EBU)Reaction rate approximated by mixing rateReaction rate approximated by mixing rate

Simplified kinetics when reaction time << mixing timeSimplified kinetics when reaction time << mixing time

Presumed Probability Density Function (PPDF)Presumed Probability Density Function (PPDF)Mixing Limited (Reaction time << mixing time)Mixing Limited (Reaction time << mixing time)

Probabilistic mixing for local turbulence effect with local equiProbabilistic mixing for local turbulence effect with local equilibrium librium

Detailed species transport (reduced or global mechanism)Detailed species transport (reduced or global mechanism)Limited # of species described with individual PDELimited # of species described with individual PDE

Detailed species transport (NDetailed species transport (N--step mechanism)step mechanism)Full mechanism with partial turbulence effectsFull mechanism with partial turbulence effects

Others: Manifolds, TPDF, RCCE, etc.Others: Manifolds, TPDF, RCCE, etc.

Current Modeling ApproachesCurrent Modeling Approaches


Reaction Analysis: Which Tool?Reaction Analysis: Which Tool?Thermodynamics AnalysisThermodynamics Analysis

Requires good thermodynamic dataRequires good thermodynamic data

Assumes infinite reaction rate and perfect mixingAssumes infinite reaction rate and perfect mixing

Reaction temperature & products upper limitReaction temperature & products upper limit

Detailed Kinetics AnalysisDetailed Kinetics AnalysisRequires consistent reaction mechanismRequires consistent reaction mechanism

Assumes detailed kinetics with generalized mixing (PFR, CSTR)Assumes detailed kinetics with generalized mixing (PFR, CSTR)

Reaction temperature/products < thermodynamics estimateReaction temperature/products < thermodynamics estimate

CFD AnalysisCFD AnalysisUser specifies reactor geometry, operating conditionsUser specifies reactor geometry, operating conditions

Approximate chemical kinetics and turbulent mixing processApproximate chemical kinetics and turbulent mixing process

Analyze/interpret results based on assumptionsAnalyze/interpret results based on assumptions

Increasing Com

plexityD

ecre

asin

g C

ompu

tatio

nal T

ime


Thermodynamics vs. KineticsThermodynamics vs. Kinetics

0

20

40

60

80

100

500

Exte

nt o

f rea

ctio

n ba

sed

upon

HC

l

1000 1500 2000 2500 3000

ξ

Temperature, K

General thermodynamics

Literature elementary reactions (PSR)

Should I use Thermodynamic equilibrium or kinetic mechanism to estimate HCl/Cl2 split?

Typical Operating Temperatures


Measured Measured vsvs. Predicted [Cl. Predicted [Cl22]]

0

100

200

300

400

500

600

1 2 3 4 5 6 7

Cl2 (Exp) ppmCl2 (Prd) ppm

Experiment No.

Kinetic effects control chemistry at high flowrates


Reaction Chemistry in Industrial Reactor

Sparger TubeConstricted ExitReaction Zone

Typical Reactor Geometry


Dashed lines = ILDM

Solid Points = Reduced chemistry

Measured Concentrations

Predicted Concentration Profiles: full chemistry vs. reduced chemistry


Predicted Ignition point

Predicted Ignition points: different kinetic mechanisms


NONOxx Chemical KineticsChemical Kinetics

Thermal NOZeldovich-NO

Prompt NOFenimore-NO

Fuel NO

NOx routesof formation

Measured and calculated NO-concentrations in H2 – air flames

complex set of elementary reactionscomplex set of elementary reactionswide range of parallel and sequential rate processeswide range of parallel and sequential rate processes


Glass Furnace SimulationGlass Furnace Simulation

Highly resolved individual portHighly resolved individual port--necksnecksmeasurements for boundary conditions & validationmeasurements for boundary conditions & validationcalculated portcalculated port--neck exhaust define b.c.’s for furnaceneck exhaust define b.c.’s for furnace

Full furnace calculation (with as much resolution as possible)Full furnace calculation (with as much resolution as possible)LES in portLES in port--necksnecks


Temperature Distribution in the Burner Temperature Distribution in the Burner PlanePlane

Single port model (Temperature in K)


Velocity Validation Study

Two distinct regions: High velocities in the flame region and a large recirculation in the crown region Not much variation between different modelsGood agreement with experiments

Hole 2 Hole 5

X Velocity (m/s) X Velocity (m/s)

Distance above glass surface(m)

Distance above glass surface(m)

Single port

Three-port

ExperimentFull furnace

Single port

Three-port



Temperature Validation

Reasonable predictions: Low gradient region (1 m from glass)Flame region very sensitive to mesh resolutionAccurate flame temperature predictions

Accurate air flow inlets: Profile very important Robust turbulent mixing model : Large Eddy Simulations (LES)High resolution mesh: resolve different scales in the furnace

Hole 1 Hole 2

Single portThree-port


Single portThree-port


Dist above glass surface(m)

Dist above glass surface(m)

Temperature (K) Temperature (K)


from Tieszen, Nicolette, Gritzo, Holen, Murray, Moya, 1996

Buoyancy Driven Plumes: Flares and Fires

Multiphysics has strong couplingbuoyancy (density variations)combustion & radiation affect density gradientssoot dominates radiation

Modeling radiation & sootempirical soot correlations using optically thin approximationempirical radiation model w/ no soot model (eg., 20-30% heat loss)


Soot Prediction Soot Prediction (add something from ISIS)(add something from ISIS)

Thick layers of soot not predicted by empirical models


Applications: Spray CombustionApplications: Spray Combustion

Spray Combustion Facility (NIST)* swirl burner with a movable 12-vane swirl cascade* profile droplet size, number density, velocity, and gas

species concentrationshttp://www.cstl.nist.gov/div836/836.02/sprays.html

Combustion Research Facility (Sandia)

Advanced Combustion Center (ACERC)

Others (MIT, School of Mines, etc.)


Applications: Spray Applications: Spray PyrolysisPyrolysisProduction of Fumed Ceria OxideProduction of Fumed Ceria Oxide

Metal Oxide particle

formation in Flame

Vaporization region

Particle agglomeration region


H2 Diffusion flame

Particle formation

Applications: Metal Oxides Applications: Metal Oxides ProductionProduction


Simulation of Fumed MetalSimulation of Fumed Metal--Oxide Oxide FlameFlame

Gas Temperature


CFD used to “Fix” existing equipment problemsCFD used to “Fix” existing equipment problemsEthylene furnace had flame impingement on process tubesEthylene furnace had flame impingement on process tubes

DeDe--rated capacity rated capacity -- significant impact on “Bottomsignificant impact on “Bottom--Line”Line”

Customer asked for help fixing problemCustomer asked for help fixing problemTeam formed to solve problemTeam formed to solve problemCFD primary tool to evaluate various optionsCFD primary tool to evaluate various optionsTeam identified most promising solution Team identified most promising solution Implemented in field Implemented in field -- Worked First Time!Worked First Time!

Applications: Plant OptimizationApplications: Plant Optimization


Initial problem: Flame roll over into tubes

Problem Fixed!


CFD helps develop new equipment/technologyCFD helps develop new equipment/technologyCustomer system must destroy CFCustomer system must destroy CF44 (>80% DRE)(>80% DRE)Kinetics analysis indicated reaction temperatures must Kinetics analysis indicated reaction temperatures must be >3300 °F to achieve required DREbe >3300 °F to achieve required DREAlumina based refractory melts <3000 °FAlumina based refractory melts <3000 °FCFD used to design new system able to meet customer CFD used to design new system able to meet customer needsneeds

Applications: Equipment SalesApplications: Equipment Sales


Quench inlets designed w/ CFD to keep

refractory surfaces cool

Combustion temperatures

>3000 °F required to oxidize CF4


CFD used to Optimize new equipment performanceCFD used to Optimize new equipment performanceFlames from New Low NOFlames from New Low NOxx Burners in Vertical Cylindrical Burners in Vertical Cylindrical furnace much longer than original onesfurnace much longer than original onesFlames merged together and extended into convection Flames merged together and extended into convection sectionsectionResulted in lower operating capacity/high emissionsResulted in lower operating capacity/high emissionsCFD used to identify most likely solutionCFD used to identify most likely solutionImplemented in field Implemented in field -- Worked First Time!Worked First Time!

Applications: Implementing New Applications: Implementing New TechnologyTechnology


AfterAfterAfterBeforeBeforeBefore


Reactor Geometry

Organic Vents

Gaseous)

Combustion Air

Fuel Gas

0.07620.6096

6.1722

1.067

0.1778

0.2032

0.3048

30.256°

30° swirl vanes

0.0762

CenterlineFuel Gas/VCM Vent Ring

water wall (1st Tube Pass)

Vapor Vent

Applications: Hazardous Vent Applications: Hazardous Vent IncinerationIncineration


Hazardous Vent Incineration Hazardous Vent Incineration ––Expected DRE?Expected DRE?

Find local maximum and average exit concentrations to improve efficiency

Burning Non-Design Hazardous Wastes


Hazardous Vent Incineration Hazardous Vent Incineration --Performance OptimizationPerformance Optimization

1350125014001300

12001050950

16001550

1500

13001100850650500

400

950

Case 5 Simulation (4% Excess O2)

13001300

1200

1050950

11501250

13501400

14501350125010001000

Gas temperature profile (K)

Case 4 Simulation (Near Stoichiometric Conditions)


Conclusions Conclusions –– Industrial Problem Industrial Problem SolvingSolving

Many opportunities in HPI/CPI for advanced Many opportunities in HPI/CPI for advanced problem solving skillsproblem solving skills

ACCES uses experience to solve problems for ACCES uses experience to solve problems for HPI/CPIHPI/CPI

Tough Problems Solved:Tough Problems Solved:Vent IncinerationVent IncinerationHydrocarbon ProductionHydrocarbon ProductionPlant retrofitPlant retrofitCoal CombustionCoal CombustionProcess OptimizationProcess Optimization


Capabilities and Limitations:Capabilities and Limitations:CFD can examine phenomena not previously CFD can examine phenomena not previously considered due to safety, cost, time, etc.considered due to safety, cost, time, etc.Advances in analysis of reacting flow with detailed Advances in analysis of reacting flow with detailed kineticskineticsCFD is not a black box that blindly & unerringly CFD is not a black box that blindly & unerringly reproduces physicsreproduces physicsComputational combustion can evaluate new fuels, Computational combustion can evaluate new fuels, new designs, and help optimizenew designs, and help optimize

ACCES can impact your bottom line!ACCES can impact your bottom line!

Conclusions Conclusions –– Industrial Problem Industrial Problem SolvingSolving

cfd for process industry 051505-revised[1] · computational combustion for the process industry...

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