Computational Fluid Dynamics (CFD) Modelling for Designing & Troubleshooting Fired Heaters

CFD Modeling Capability
Furnace Improvements Services

www.heatflux.com
Furnace Improvements Services: The Company
❖ Furnace Improvements Services is a reputed engineering and consulting company
which provides specialized technological services that integrates mechanical and
process engineering with CFD capabilities in order to design or revamp fired heaters
and boilers in Oil & Gas industry
Company Overview
❖ Offices
▪ Headquarters: Sugar Land, Texas, USA
▪ Process & Mechanical Group: New Delhi, India
▪ CFD & Process Group: Pune, India
❖ Services
▪ Turn-key services for design, engineering and supply of new
fired heaters
▪ Revamps of all types of refinery fired heaters
▪ CFD Modeling
▪ Troubleshooting

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Typical Project Progress
Methodical Approach
Mechanical
•2D Drawings as per Client Documents
•C&I summaries
Process
•Datasheets: Heater, Burner, Fans, APH, etc.
•FRNC Simulations: Operating, Existing, and Proposed cases
•Comparison with design parameters and identification of
deviating parameters
CFD
•2D drawings from Mechanical team + FRNC simulations and
process calculations from Process team
•Evaluation of existing design using CFD Modeling
•Validation with operating observations
•Confirmation of operating issues
•Evaluation of recommendations based on resolution of
operating issues
•Final proposed design
•Detailed proposed design sent to Mechanical and Process
team for Drawings and Datasheet
Kick-off:
▪Client Drawings
and Documents
▪Operating data
▪Field
measurements
Final report with
Existing and
Proposed cases:
▪2D drawings
▪Datasheets
▪CFD report

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Basis for Study and Resolution Approach
Operating Issue:
• Operating data
• Field measurements
• Comparison with design
parameters
• Identification of deviating
parameters
Root Cause Analysis:
• Evaluation of existing design
using CFD Modeling
• Validation with operating
observations
• Confirmation of operating
issues
Propose modifications:
• Various designs and configurations
are analysed
• Burner tip, perforated plate, and
number and location of burners for
combustion cases
• Vanes, angles, baffles and
perforated/corrugated plate designs
for flow improvements
Final Design:
• Best results and least
modification
• Comparison with existing
design to show
improvements
Issue Identification and Approach

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Computational Fluid Dynamics (CFD)
❖ Computational Fluid Dynamics (CFD) is a branch of fluid mechanics,
used to solve and analyze problems of fluid flow through numerical
analysis of conservation equations for mass, momentum, energy, etc.
❖ Benefits of CFD Modeling
▪ Insight: Gain detailed understanding of the phenomena inside the equipment or
system
▪ Foresight: Virtual prototyping and testing to answer many “What If?”
▪ Efficient: Based on the foresight, CFD helps to achieve better design faster and with
less cost. CFD helps to reduce the design and development cycle, with rapid
prototyping
CFD Description

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CFD Applications in Fired Heaters
CFD Scope
Combustion
Air Flow Distribution
Fan Suction / Discharge Ducts
AIG and SCR units
Flow Distribution in Manifolds

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CFD Modeling Steps Outline
General Workflow
MODELING
MESHING
CFD SOLVER PRESENTATION
POST-
PROCESSING
Detailed 3D model of fluid system
to accurately represent the domain
to be analyzed
Setup of models, boundary conditions,
computational parameters and
convergence goals
Combine details from each step to
present a simple structure of the
methodology and CFD results
Meshing of the 3D domain with
mesh resolution and refinement
Analysis of converged solution with
the help of contours, vectors, fluxes,
plots and animations

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Case Studies
❖ Following slides show the application of CFD for various
components of a fired heater system
❖ Typically one example is included for each component
❖ Apart from this, our CFD team is capable to simulate other
applications related to refinery operations
Sample Case Studies

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Outline of Case Studies
CFD Analysis
Vertical Cylindrical
(VC) Heater
Cabin/Box Heater
Combustion Analysis

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Flame Profiles colored by Height
Improvement in Flame Profile
[ft]
Flame Height: 25 ft
Flame Height: 11 ft
Flame height is reduced by more
than 50% for the proposed case
Existing Proposed

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Maximum
TMT: 840 °F
Maximum
TMT: 800 °F
Radiant Tube Metal Temperature Profiles
Improvement in TMT Profile
Significant reduction in radiant
tube metal temperatures.
Reducing tube metal
temperature increases the
heater run length.
[°F]
Existing Proposed

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0
8
16
24
32
40
0 120 240 360 480 600 720 840 960 1,080 1,200
Radiantsectionheight,ft
Mole fraction CO, ppmv
Variation of CO mole fraction with height
Existing
Proposed
CO Mole Fraction Profile
Decrease in CO levels
Average CO levels at
each cross-section of the
heater has reduced
considerably, showing a
faster combustion and
lower flame heights

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CFD Analysis
Plenum-mounted Burners
Combustion Air Flow

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Hot Air Velocity Profile
Improved air flow in duct and burners
[ft/s]
Existing Proposed

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Mass flow deviation at burner outlets
Substantial Reduction in RMS Deviation
-20
-15
-10
-5
0
5
10
15
20
1 2 3 4 5 6 7 8 9 10 11 12
RMSDeviationinMassFlow,%
Burner No.
Existing
Proposed
Mass flow deviation for the
proposed case is within ± 3%
89
10
11
12
1
2 3
4
5
6
7

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CFD Analysis
Fan Suction and Discharge

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ID Fan Suction Duct Results
❖ Pressure drop was reduced by
around 0.5 inches WC on the
suction side
Better Fan Performance
Pressure Profile [inches WC]
Existing
Proposed
Existing
Proposed
Velocity Profile [ft/s]

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ID Fan Discharge Duct Velocity Profile
❖ Pressure drop was reduced by
around 0.25 inches WC on the
discharge side
Uniform flow at stack cross-section
[ft/s]
ProposedExisting

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CFD Analysis
Model
Geometry
AIG Lances
AIG - SCR

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AIG Lances
Lance Designs
Existing
Proposed

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NOx Distribution at SCR inlet
Substantial Improvement in Mixing
RMS deviation at SCR inlet
is ± 4.56%
is ± 17.25%
Existing Proposed
[ppmv]

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NH3 Distribution at SCR inlet
Substantial Improvement in Distribution
is ± 2.87%
Existing Proposed
[ppmv]
is ± 19.32%

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CFD Analysis
Fluid Transfer LinesMulti-phase Flow

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Liquid volume fraction surface
Liquid Fraction in Transfer Line
Liquid Volume Fraction Contours
Inlet
Inlet
Surface of liquid volume fraction of 0.5 is created to show the liquid
flow in the pipes
Existing Proposed

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Flow Rate Deviation across Passes (Liquid & Vapor)
Comparison: Existing vs. Proposed
-25
-20
-15
-10
-5
0
5
10
15
20
A B C D E F G H
%DeviationinLiquidFlow
Pass Number
Existing Proposed
-20
-15
-10
-5
0
5
10
15
20
25
A B C D E F G H
%DeviationinVaporFlow
Pass Number
Existing Proposed
Deviation in Liquid Flow Deviation in Vapor Flow
Improved liquid flow distribution for the proposed
case; deviation in liquid flow across all the passes is
less than ±10%
Improved vapor flow distribution for the proposed
case; deviation in vapor flow across all the passes is
less than ±5%

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Get in Touch
❖ Above case studies highlight FIS capability of carrying out CFD
study for diverse applications
❖ Our team will be happy to discuss any specific project
requirement
Thank You!
Furnace Improvements Services Inc.
@uniformheattransfer
Furnace Improvements Serviceswww.heatflux.com

Computational Fluid Dynamics (CFD) Modelling for Designing & Troubleshooting Fired Heaters

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