cfd for process industry 051505-revised[1] · computational combustion for the process industry...
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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 Page 2
OUTLINEOUTLINE
Introduction to ACCESIntroduction to ACCESReactive Flow AnalysisReactive Flow AnalysisDetailed Kinetics and Mixing modelsDetailed Kinetics and Mixing modelsExamplesExamplesConclusions and SummaryConclusions and Summary
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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
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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?
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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
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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
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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
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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
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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
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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
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Coupling Chemistry to Turbulent Coupling Chemistry to Turbulent FlowFlow
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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)
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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
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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
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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
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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
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Reaction Chemistry in Industrial Reactor
Sparger TubeConstricted ExitReaction Zone
Typical Reactor Geometry
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Dashed lines = ILDM
Solid Points = Reduced chemistry
Measured Concentrations
Predicted Concentration Profiles: full chemistry vs. reduced chemistry
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Predicted Ignition point
Predicted Ignition points: different kinetic mechanisms
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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
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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
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Temperature Distribution in the Burner Temperature Distribution in the Burner PlanePlane
Single port model (Temperature in K)
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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
ExperimentFull furnace
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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
ExperimentFull furnace
Single portThree-port
ExperimentFull furnace
Dist above glass surface(m)
Dist above glass surface(m)
Temperature (K) Temperature (K)
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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)
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Soot Prediction Soot Prediction (add something from ISIS)(add something from ISIS)
Thick layers of soot not predicted by empirical models
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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.)
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Applications: Spray Applications: Spray PyrolysisPyrolysisProduction of Fumed Ceria OxideProduction of Fumed Ceria Oxide
Metal Oxide particle
formation in Flame
Vaporization region
Particle agglomeration region
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H2 Diffusion flame
Particle formation
Applications: Metal Oxides Applications: Metal Oxides ProductionProduction
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Simulation of Fumed MetalSimulation of Fumed Metal--Oxide Oxide FlameFlame
Gas Temperature
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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
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Initial problem: Flame roll over into tubes
Problem Fixed!
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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
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Quench inlets designed w/ CFD to keep
refractory surfaces cool
Combustion temperatures
>3000 °F required to oxidize CF4
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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
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AfterAfterAfterBeforeBeforeBefore
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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
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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
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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)
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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
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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