improve fired heaters performance and reliabilty

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

www.heatflux.com 13

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

www.heatflux.com 21(°F)

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

www.heatflux.com 29

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

www.heatflux.com 31

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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