new approach to optimizing fired heater.pptx

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Energy Consumption

• Petroleum Refining

▫ 7.5% of the total energy

consumption in USA

• 0.40 MMBtu/ BBL of oil

• Total Energy consumed in

refining- 7.1 Quadrillion BTU/yr

• Energy cost -$6/MMBtu

• Total Energy Cost- 42 Billion /yr

• Fired heaters -40-70% of the

energy



Energy Consumption

• A Typical refinery process 100,000 BPD

• Consumption of 0.40 MMBTU/BBL

• $6 per MMBTU

• Energy bill of $ 87.6 million per year.

Potential Saving

• 1% Efficiency improve • $876,000/Year



Fired Heaters

• Essential component inPetrochemical and ChemicalPlants

• Each refinery has ≈ 20-50 firedheaters

• Design efficiency - 70-90%▫ Operating efficiency is even less

than design.



Maintaining Design Operation• Maintain the design conditions

(very difficult)

• In the field, heater loadschange constantly due to variations in:▫ Feed flow rate

▫ Feed temperature

▫ Fuel composition▫ Ambient temperature

• The heater will be operating anon-optimal conditions

• Requires optimization 24/7



How to Maintain the Design Efficiency?• When the heater conditions

change, adjustments in the heaterare required.

• Manual adjustments areprovided- not adequate

• Optimizing the fired heater will:

▫ Reduce Energy Consumption

▫ Increase run length

▫ Minimize maintenance

• FIS has proposed two prongapproach

• Software based- HeaterPerformance Index

• Hardware based- Draft & ExcessO2 Control



Fired Heater

• Heat liberated by thecombustion of fuels istransferred to fluids

contained in coils

• Fired Heater:

▫ Radiant Section

▫ Convection Section

▫ Stack

www.heatflux.com



Typical heater efficiency• Natural Draft- 70-84%

• Balance Draft-90-92%

• Natural Draft heaters inIndustry- 86%

• Balanced Draft heaters inIndusty-12%

• Typical stack temperature –

500-800 F• Typical stack Oxygen- 2-10%

• Target Oxygen-2-3%

• Plenty of room foroptimization



Combustion

• Combustion Requires▫ Air ( 0.21O2 + 0.79 N2)

▫ Fuel

▫ Ignition source

• Complete Combustion▫ Excess air

• Incomplete Combustion▫ Energy Loss

▫ CO and H2 are released



Draft

• Pressure inside the heater▫ Combustion air is drawn inside the

heater through the burner’s airregister

▫ Hot Flue gas flows out of the heaterthrough the stack

• Types of Draft

▫ Natural Draft (ND) > 80%

▫ Forced Draft (FD) < 1%

▫ Induced Draft (ID) ≈ 10%

▫ Balanced Draft ≈ 10%



Draft

• Stack Dampershelps control thedraft

• Arch is thehighest pressurepoint in theheater

• Excess orshortage of draftis not acceptable

CONVECTION

SECTION

STACK

________

BURNERS

0.05"- 0.1"

W.G. DRAFT

DRAFT AT RADIANTSECTION OUTLET,

R0

R A D I A N T S E C T

I O N

Pc

(SE)a STACK

EFFECT

IN STACK

(SE)c

NEGATIVE PRESSURE

0.05"- 0.1" W.G. AT

TOP OF RADIANT

SECTION

Pb

(SE)r

Pa

NEGATIVE

PRESSURE

POSITIVE

PRESSURE0

STACK

EXIT LOSS



Burner Operation

• Correct combustion infirebox include:

▫ The firebox is clear

▫ No smoky appearance

▫ Burners flames aresteady and well-formed

• Check burners regularly

• Adjusting burnerregisters to control airintake



Air Leakages

• Air entering in to furnacefrom a number of places:

▫ Peepholes

▫ Header box doors

▫ Tube guide opening

▫ Feed tubes entering andexits

▫ Not pressure tightstructure



Heater Optimization

• Target set 2-3% O2 inthe flue gas.

• Operating conditions

fluctuates :▫ Manual control

/adjustments

▫ Operators

Number going down Experience going down

Need training



Optimisation Case Study -1

• FIS performed a tuning job for arefinery.

• Heater:

▫ Depentanizer reboiler heater

▫ Horizontal tube box

▫ Absorbed heat duty - 87 MMBtu/hr

▫ 15 up fired burners

▫ The stacks is connected to a largecommon stack

▫ Two off take ducts provided withmanual dampers



Optimisation Approach• Check draft

▫ Adjust using off-take

dampers

• Check excess O2

▫ Adjust burner register

• Check burners

▫ Light up all burners

▫ Check Flames/Firebox



0.1

0.2

0.3

0.4

0.5

0.6

0.7

10:48 12:00 13:12 14:24

Time (7/22/09)

D

r a f t , i n H 2 O

Draft



2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

10:48 12:00 13:12 14:24

Time (7/22/09)

E x c e s s O x y g e n , %

Excess Oxygen



595

605

615

625

635

645

10:48 12:00 13:12 14:24

Time (7/22/09)

S t a c k T e m p e

r a t u r e , ° F

Stack Temp. A

Stack Temp. B

Stack Temperature



78.0

79.0

80.0

81.0

82.0

83.0

10:48 12:00 13:12 14:24

Time (7/22/09)

T h e r m a l E f f i c i e n c y , %

Thermal Efficiency



Crude Heater Tuning

Case Study -2• Natural Draft Crude

Heater

• Horizontal tube

• Up-fired burners

• 11 burners



Before & After Tuning

F

u e l g a s f l o w , M S

C F D

F u e l g a s

p r e s s u r e , p s i g

0

2

4

6

8

10

12

14

16

18

20

3260

3280

3300

3320

3340

3360

3380

3400

3420

3440

11:15 AM 11:30 AM11:45 AM 12:00PM

12:45 PM 1:00 PM 1:15 PM 1:30 PM

Flue Gas Flow,MSCFD

Fuel GasPressure, psig

Fuel gas Flow and Pressure



580

600

620

640

660

680

700

720

740

760

11:15 AM 11:30 AM 11:45 AM 12:00 PM 12:45 PM 1:00 PM 1:15 PM 1:30 PM

T S k i n ,

° F

Before & After TuningTube Skin Temp



Recommendations

• Furnace working off design conditions• Poor quality of dampers• Lower number of operators• Operator without sufficient training

• Software▫ Heater Performance Index(HPI)

• Hardware▫ Draft control system▫ Excess O2 control system

Observations in Refineries



Heater Performance Index

• Analyzes theperformance of FiredHeater 24/7

• Built into DCS• Generates guidelines

• Built in intelligence

• Customized modeling

▫ Thermal Efficiency

▫ Fuel gas rate,

▫ Draft,

▫ Excess O2,

▫ Tube skintemperatures,

▫ Feed flow rate,

▫ Pressure drop,

▫ Coking rate,

▫ Air preheaterperformance



Crude Flow Rates

TAG No. SERVICE UNITS SET

POINT

8/15/2009 8/16/2009 8/17/2009

Data 1 Data 2 Data 3

PROCESS

57FC0009.PV Total Crude Flow BPH 4337.6 5249.1 4807.3 4637.7

57FC0001.PV Crude Flow to Pass 1 BPH 542.2 709.5 711.6 668.0







Average BPH 542.2 706.7 717.7 684.7



Coil Inlet Pressure


POINT

8/15/2009 8/16/2009 8/17/2009


PROCESS

57PI0054.PV Crude Inlet Pressure (Pass 1) psig 147.9 278.9 287.4 286.0







Average psig 147.9 285.7 295.3 294.1



Fluids Cross-over Temperatures.

TAG No. SERVICE UNITS SETPOINT

8/15/2009 8/16/2009 8/17/2009


PROCESS

57TI0583 Crude Inlet Temperature oF 542 557.2 553.8 555.3

57TI0590 Cross-over Temp. (Pass-1) oF 610 585.1 581.9 583.6







AVERAGE Cross-over Temp. oF 610.0 590.9 588.0 589.4



Coil Outlet Temperatures


POINT

8/15/2009 8/16/2009 8/17/2009


PROCESS

57TI0633 Coil Outlet Temp. (Pass 1) oF 730 686.8 687.0 687.4




57TI0629 Coil Outlet Temp. (Pass 5)o

F 730 683.4 683.5 683.7



AVERAGE Coil Outlet Temp. oF 730.0 679.9 679.9 680.1



Heater Performance Index. Remarks

RADIANT COIL TUBE METAL TEMP.

CRUDE HEATER 537-F-001

700.00

800.00

900.00

1000.00

1100.00

1200.00

PASS1 PASS2 PASS3 PASS4 PASS 5 PASS 6 PASS 7 PASS 8

T e m

p e r a t u r e ,

D e g F

Operating- Data 1

Operating- Data 2

Operating- Data 3

Operating- Data 4

Operating- Data 5

Operating- Data 6

Operating- Data 7

Design CLEAN

Design FOULEDMetallurgical Limit



Heater Performance Index. Remarks

THERMAL EFFICIENCY

CRUDE HEATER 537-F-001

90.32 90.25

89.56

89.35

89.57

89.73 89.69

89.26

88.60

88.80

89.00

89.20

89.40

89.60

89.80

90.00

90.20

90.40

90.60

Design Data 1 Data 2 Data 3 Data 4 Data 5 Data 6 Data 7

T h e r m

a l E f f i c i e n c y ,

( % )

H t P f I d



Heater Performance Index



Oxygen & Draft Control System(Natural Draft Heater)



Draft Control

System



Stack dampers• Reliable

• Correctly sized

• Pneumatically operated• Opposed blades



Reliable Dampers Opposed blades vs. Parallel Blades



Excess O2 Control• Control air supply to burners

• Pneumatically operateddampers or registers

• Provide proper control scheme

• Damper opening is provided based on

▫ Draft

▫ Excess O2▫ Firing rate

▫ Other parameters

• Savings realized through outthe day



Summary• Manual controls are not

adequate

• Energy prices are high

• Advanced Controls possible

• Use DCS based or PLC based

• Provide adequate safe guards

• Intelligent analysis of heater

parameters• Substantial savings can be

realized

• Payout will be less than a yearin most cases



Thank you very much

• Questions and comments are welcome

new approach to optimizing fired heater.pptx

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