improve fired heaters performance and reliabilty
DESCRIPTION
Fired heaters are often suffering from high tube metal temperatures and short run lengths. Operators are always worried about hot spots in the furnace. While refineries want to push the heaters hard, the heater starts coking up and very soon, the heater tubes have to be cleaned. FIS has done extensive research and CFD modelling of heaters in the recent time and has concluded that localized burner flame and hot flue gas currents are responsible for the hot spots on the tubes. FIS has now developed a new patented technology for solving hot spot problems. This technology called Inclined Firing Technology involves orienting the burners at an angle on the floor / wall/ roof to direct the flame away from the tubes. The results of this technology have been extremely good and with a very low investment, the reliability and run length of the heater is improved significantly.TRANSCRIPT
Furnace
Improvements
Services
Improving Fired Heaters Performance and Reliability
Ashutosh Garg
Furnace Improvements
www.heatflux.com
1
Furnace
Improvements
ServicesFired Heaters
Important equipment in refineries and chemical plants
High temperature heat transfer
Fuel gas fired
High tube metal temperature problem
Coking
Shutdown
RadiantTubes
Breech
Tubes
Finned/
Section
Damper
TubesStudded
Shield
Section
FloorBurners
Peep Door
Radiant
Convection
Stack
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Furnace
Improvements
ServicesOperating and Reliability
IssuesHigh tube metal temperatures is the biggest
problem in fired heater operation
Most of the high tube metal temperatures is due to localized flame impingement.
Fired heaters have burners that are fired vertically upright, sideways or downwards.
FIS patented technology reorient the burner at a slight angle away from the tubes.
Hottest flame and flue gases are moved away from the tubes.
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Furnace
Improvements
ServicesBenefits of Inclined Firing
System
Significant reduction in tube metal
temperatures
Low coking rates
Higher tube life and run lengths
Increased capacity possible in most heaters
Uniform firing achieved across the tubes
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Furnace
Improvements
Services
1/29/2014 www.heatflux.com 5
4'
BCD
12'-9"
TCD
12'-9"
INLET
OUTLET
4'
4'-4 ½”
2'-7"
4'
BCD
6'
5'
2'-7"
12'-9"
TCD
12'-9"
INLET
OUTLET
4'
Burners areinclined at5-10 deg.
Inclined Firing
System
INTERHEATER -2 INTERHEATER -1 CHARGE HEATER
35'-6" 35'-6"
5' 5'
6'
5' 5'
4'-6"
5' 5'
4'-6"
5-10deg.
Furnace
Improvements
Services
20'-0 7/8" (SHELL WIDTH)
24.0000
8 0.7500
113.0000 113.0000
4.0000 4.0000
24.0000
8 0.7500
EXISTING
4'-0"
2'-8 1/2"2'-8 1/2"
7.0000
5'-5" 5'-5"
20'-0 7/8" (SHELL WIDTH)
24.0000
8 0.7500
113.0000 113.0000
4.0000 4.0000
24.0000
8 0.7500
PROPOSED
4'-0"2'-8 1/2"
2'-8 1/2"
7.0000
5'-5" 5'-5"
3.5o
3.5o
7.0000
C B
UR
NE
RL C B
UR
NE
RL C
BU
RN
ER
L
PROPOSED INCLINED BURNER
EXISTING PROPOSED20'-0 7/8" (SHELL WIDTH)
24.0000
8 0.7500
113.0000 113.0000
4.0000 4.0000
24.0000
8 0.7500
EXISTING
4'-0"
2'-8 1/2"2'-8 1/2"
7.0000
5'-5" 5'-5"
20'-0 7/8" (SHELL WIDTH)
24.0000
8 0.7500
113.0000 113.0000
4.0000 4.0000
24.0000
8 0.7500
PROPOSED
4'-0"2'-8 1/2"
2'-8 1/2"
7.0000
5'-5" 5'-5"
3.5o
3.5o
7.0000
C B
UR
NE
RL C B
UR
NE
RL C
BU
RN
ER
L
PROPOSED INCLINED BURNER
Inclined Firing System in a Down Fired Steam Reformer
Furnace
Improvements
Services
EXISTING PROPOSED
HDS Depentanizer Reboiler H-102 Burners
6’-8” (B.C.D) 6’-8” (B.C.D)
14’-0 1/4” (T.C.D) 14’-0 1/4” (T.C.D)
C B
UR
NE
RL C B
UR
NE
RL
C B
UR
NE
RL
C H
EA
TE
RL
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Furnace
Improvements
Services
EXISTING PROPOSED
Depentanizer Reboiler H-205 Burners
(B.C.D)5’-6” (B.C.D)
11’-8 1/8” (T.C.D) 11’-8 1/8” (T.C.D)
C B
UR
NE
RL C B
UR
NE
RL
C B
UR
NE
RL
C H
EA
TE
RL
COMMON
PLENUM
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Furnace
Improvements
Services
EXISTING
F-4202 F-4201
C B
UR
NE
R
762 1372
3200 (P.C.D.) 3962 (P.C.D.)
B.C.D. B.C.D.
L C B
UR
NE
RL C B
UR
NE
RL C B
UR
NE
RL
EXISTING
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Furnace
Improvements
Services
Proposed Burner Layout in a VC Heater
F-4202 F-4201
⌽1650 ⌽2350
(TYP.)3°
(TYP.)5.5°
C B
UR
NE
R
C B
UR
NE
R
3200 (P.C.D.) 3962 (P.C.D.)
762 1372
B.C.D. B.C.D.
FLOOR PLT. FLOOR PLT.
L
L
C B
UR
NE
R
C B
UR
NE
RL
L
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Furnace
Improvements
Services
Case Studies
Two case studies presented in this paper
First one – Coker Heater
Second one – Crude Heater
Both cases had high tube metal temperatures
CFD Modeling carried out to demonstrate the benefits of Inclined Firing
Can be used with all types of burners and in all types of heaters ( Contact FIS with your specific case )
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Furnace
Improvements
Services
CFD ModelingStart
CAD Geometry
CAD Geometry &
Meshing
Boundary
Conditions
Solver
Converged
Solution
Post Processor
Analysis
End
Diverge
Optimization
CFD
Computational Fluid
Dynamics
Uses numerical methods
and algorithms to study
fluid flow
Flow patterns in fired
heaters, burners,
fireboxes
3D models of fired
equipment are created
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Furnace
Improvements
ServicesCoker Heater High tube metal
temperature issues
Fuel gas fired low NOx
burners
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Furnace
Improvements
ServicesHeater Geometry
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Burner
GeometryHeater
Geometry
Air inlet
Furnace
Improvements
ServicesResults
The flow pattern of flue gases is shown using
Velocity Vectors
Path Lines
The temperature profile in the heater is shown
using
Temperature Contours
The flame profile is shown using
CO envelope of 2000 ppm
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Furnace
Improvements
ServicesVelocity Vectors
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(ft/s) Plane @ Primary tipZoomed View
Furnace
Improvements
ServicesVelocity Vectors (by temperature)
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(F)Plane @ Primary tip
Furnace
Improvements
ServicesTemperature Contours
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(°F) Plane @ Primary tip
Furnace
Improvements
ServicesTube Metal Temperature Contours
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(°F)
Furnace
Improvements
ServicesRefractory Temperature Contours
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Furnace
Improvements
Services
Flames Shape(Iso-Surface of CO 2000 ppm)
22Colored by Temperature (°F)
B-4B-1 B-2 B-3
Furnace
Improvements
Services
Inclined Firing
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Burner
Geometry
Heater
Geometry
Air inlet
Burners are inclined by 7.5
deg towards the walls
Furnace
Improvements
ServicesVelocity Vectors
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(ft/s)
Plane @ Primary tip
Inclined Firing
Furnace
Improvements
ServicesTemperature Contours
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(°F) Plane @ Primary tip
Inclined Firing
Furnace
Improvements
Services
Tube Metal Temperature Contours
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(°F)
Inclined Firing
Furnace
Improvements
ServicesIso-Surface of CO 2000 ppm
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Colored by Temperature
(°F) B-4B-1 B-2 B-3
Inclined Firing
Furnace
Improvements
ServicesVertical Up Firing VS. Inclined Firing
Flow Profiles
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Furnace
Improvements
Services
Vertical Up Firing VS. Inclined Firing
Temperature
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Furnace
Improvements
ServicesVertical Up Firing VS.
Inclined Firing Flame Profile
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Furnace
Improvements
Services
Conclusion
Inclined firing resulted in reduction of tube
metal temperatures by about 40-50 F
Elimination of flame impingement
Longer life of tubes
Longer heater run lengths
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Furnace
Improvements
Services
Case Study-2-Crude Heater
Client facing flame
impingement and high tube
metal temperatures in radiant
section
FIS recommended inclined
burner firing system to eliminate
flame impingement
Carry out CFD Modeling of the
Burners and Radiant Section to
demonstrate the benefit of
inclined burner firing system
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Furnace
Improvements
ServicesExisting Burner Arrangement
EXISTING FLOOR & PLENUM ARRANGEMENT
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Furnace
Improvements
ServicesInclined Firing System Burner Arrangement
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Furnace
Improvements
ServicesVelocity vectors (ft/s) °
Base case vs. Inclined Firing System
50 ft
36 ft
19 ft
0 ft
height in ftwww.heatflux.com 35
Furnace
Improvements
Services
Temperature ContoursBase Case VS. inclined firing
system
Base case Inclined Firing Systemwww.heatflux.com 36
Furnace
Improvements
Services
Temperature contours(°F)at 10 ft section- Base Case VS.
inclined firing system
Base caseInclined Firing
System
At 10 ft At 10 ft
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Furnace
Improvements
ServicesTemperature contours (°F)
at 15 ft section- Base Case VS. inclined firing system
Base case Inclined Firing System
1
At 15 ft At 15 ft
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Furnace
Improvements
Services
CO mass fraction contours (PPM) at 10 ft section- Base Case VS.
inclined firing system
At 10 FtInclined Firing
System
1
Base CaseAt 10 Ft.
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Furnace
Improvements
Services
CO mass fraction contours (PPM) at 15 ft section- Base Case VS.
inclined firing system
At 15 Ft.Inclined Firing
System
1
Base CaseAt 15 Ft.
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Furnace
Improvements
ServicesBase Case VS. inclined firing system
Quarter section view
• Pathlines shows the flow towards radiant section for the base case at entrance of heater
• However for inclined firing system flow does not interact to radiant tubes at entrance of heater
Flow on
radiant
tubes
Furnace
Improvements
Services
Iso surface of CO mf 2000 PPM colored by temperatures (o F) Base Case VS.
Inclined Firing System
Base Case Inclined Firing
SystemTop View
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Furnace
Improvements
ServicesIso surface of CO mass fraction
2000 PPM colored by flame height (ft)
Base case Inclined Firing SystemVS.
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Furnace
Improvements
ServicesRadiant wall temperatures (°F)
Base design Modified design
For h =100 Btu/ft2-h
and T=800 °F
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Furnace
Improvements
Services
SummaryInclined Firing is proven in solving high
tube metal temperatures problems
CFD Modeling helped in demonstrating the
benefit in performance improvement
FIS is ready to evaluate your heater if it is a
suitable candidate for inclined firing at no
cost.
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Furnace
Improvements
Services
We hope you will find our presentation helpful
and informative.
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