rrtc sept.05 g caronno fired heaters presentationjh final 1 animated

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Giampiero CaronnoSales Manager, Equipment DivisionFoster Wheeler Italiana Spa

RRTC 22 & 23 September 2005

Fired HeatersEnhancing Refinery Profitability


Fired Heaters – Enhancing Refinery Profitability

Contents

• How a fired heater works

• Fired heater design basis – the importance of the ‘heart’ of the unit

• Parameters influencing fired heater operation

• Maximization of process unit profitability

• Improper operation

• Example of revamping – case studies



How a fired heater works

Balanced (forced) draft

Natural draft

Stac

kC

onve

ctio

nR

adia

nt s

ectio

n

sect

ion

Damper

Stack exit loss

Stack effect in stack

Stack effect in convection section

Burners

0.05” –0.1” W.G. draft.Draft at radiant section outlet, R0

Negative pressure 0.05” – 0.1” W.G. at top of radiant section

Stack effect in radiant section

Negative pressure Positive pressure0



Design Basis

• Tailored design to meet design requirements

• Main design parameters: efficiency and heat flux

• Optimization between efficiency and cost

• How many fired heaters have a proper design basis ?

• How many fired heaters work in line with the design basis ?



Parameters influencing fired heater operation

EFFICIENCY REDUCTIONEFFICIENCY REDUCTION==

Heat LoadHeat Load++

Excess AirExcess Air++ FoulingFouling

++



Parameters influencing fired heater operation (*)

• Higher heat flux

• Reduced tube life time

• Reduced efficiency

Heat load

(*) Based on:(*) Based on:

Fuel Oil LHV= 9500 Kcal/Kg Fuel Oil LHV= 9500 Kcal/Kg Fuel Oil Cost= 0.2 €/KgFuel Oil Cost= 0.2 €/Kg

430400°CStack temperature

62 (+20%)52Gcal/hFired heater duty

77.2

67.36

75.5

82.12

%Fired heater Efficiency

Gcal/hHeat fired




Excess Air

5252Gcal/hFired heater duty

259,200

65.82

400

20

67.36

400

40

€ Yearly saving

Gcal/hHeat fired

°CStack temperature

%Excess air

33000€Extra Yearly Cost

21Kg/hExtra Fuel

2100Kg/hExtra Air






• Clean condition

• Internal fouling

• External fouling

52Gcal/hFired heater duty

€/yearIncremental fuel cost

€/hIncremental fuel cost

7090Kg/hFuel fired

100,000HrsTubelife

448°CMetal temperature

435°CPeak film temperature

400°CStack temperature

77.2%Heater efficiency

Clean condition

52

464,000

58

7380

20,000

524

438

450

74.2

Internal fouling

52

944,000

118

7680

100,000

456

441

500

71.3

External Fouling

Fouling of exchange surface



Maximization of process unit profitability

Reduce utilityReduce utilityconsumptionconsumption

Maximization unit profitability

Minimize Minimize operatingoperating

costcost

OptimizeOptimizefired heatersfired heatersperformanceperformance

Reduce Reduce emissionsemissions

IncreaseIncreasecapacitycapacity

MaximizeMaximizeonon--stream timestream time




OptimizeOptimizefired heatersfired heatersperformanceperformanceUniform conditionsUniform conditions

Optimize firingOptimize firing

Reduce Reduce emissionsemissionsReduce firing rateReduce firing rate

Replace burnersReplace burnersIncreaseIncreasecapacitycapacity

Limited firing capacityLimited firing capacity

Limited heat transfer surfaceLimited heat transfer surface

Draft shortageDraft shortage

Flame impingementFlame impingementHigh tube metal temperatureHigh tube metal temperature

Firing control difficultiesFiring control difficultiesCoke formation inside tubesCoke formation inside tubes


Add extra surfaceAdd extra surface

APH installationAPH installation

Cleaning surfacesCleaning surfaces

MaximizeMaximizeonon--stream timestream time

Proper operationProper operation

Maintenance scheduleMaintenance schedule

Fired Heater componentsFired Heater components

Minimize Minimize operatingoperating

costcostInternal tube cleaningInternal tube cleaning

Fire cheap fuelsFire cheap fuels

Automatic devicesAutomatic devices

Instrumentation improvementInstrumentation improvement



Maximization of process unit profitability (*)

• Higher efficiency• Milder conditions at constant load• Possible increased fired heater load


Reduce utilityReduce utilityconsumptionconsumption24,40028,000Kcal/h m2Heat flux

8370%Fired heater efficiency

N.A.

393

33

46,000

1,243,000

387

33

46,000

€/yearSaving

°CPeak film temperature

Gcal/hFired heater duty

BPSDTopping capacity

Increase of convection surface



30,900

81

387

43

60,000

Increase of radiant surface



Maximization of process unit profitability (*)

Installation of air preheating system

6,0807,090Kg/hFuel fired

70,00070,000BPSDTopping capacity

9077%Fired heater efficiency

N.A.

40

52

1,620,000

20

52

€/yearSaving

%Excess air

Gcal/hFired heater duty





• Higher efficiency• Short payout period




Reduce Reduce emissionsemissions

184t on/yNox outlet (**)

250mg/Nm3Nox emissions (**)

442t on/yNox outlet (*)

600mg/Nm3Nox emissions (*)

40%Excess air

77.2%Heater efficiency

H.I. burners low eff.

54

75

252

350

20

79

Low Noxburners

56

90

253

400

20

90

Low Nox

w/APH

(*) Fuel oil firing(**) Fuel gas firing

Emission reductions



Improper fired heater operation

Original fired heater

design

Currentfired heaterconditionsDamper design

Low velocityinside tubes

Old typeburners

Positive pressure

Uneven flow distribution

Fouling on heat transfer

surfaces

Air infiltration

High excess air



Case 1 Atmospheric distillation fired heater

• Installation of a fix type air preheating system (APH) on a twenty-five year crude heater

• APH Installation was carried out during scheduled turnaround

• Forced and induced draft system installed

• Fired heater control was upgraded

Fired heater duty, Gcal/h 52 52

Net efficiency, % 72 90

Heat fired, Gcal/h 72.2 57.8

Fuel oil saving, Kg/h 1,520

Annual saving, Euros (*) 1,216,000

(*) Euros equivalent / F.O. Cost : 0.1 €/ Kg equivalent



Case 2 Refinery fired heaters

• Firing optimization and emission reduction program for most of refinery process heaters

• Burners of significant fired heaters were replaced during phasedturnarounds; minor modifications on fired heater floors required

• Refinery fuel balance re-arranged to have most effective FO / FG ratio

• Refinery global flue gas emissions were reduced to 65%

Overall fired heaters duty, Gcal/h 1,039.4

Ave. NOx emissions, mg/Nm3 455.5 296.3

Total NOx outlet, Kg/h 425.6 276.8



Case 3 Vacuum Distillation fired heater

• Improved operating conditions of vacuum distillation fired heater

• Replaced burners with state-of-the-art type to solve tube bending due to flame impingement problems and to reduce flue gas emissions

• Convection section and stack were modified and replaced



Heat fired, Gcal/h 27 25

Fuel oil saving, Kg/h 214

Annual fuel saving, Euros(*) 342,000(*) Not considering improvement in operating conditions



Case 4 Atmospheric Distillation fired heater

• Increase unit capacity from 30,000 to 42,000 BPSD

• Improved fired heater efficiency (+40% capacity with only 11% additional heat fired)

• Added radiant surface in available space

• Replaced bare tubes with finned tubes in convection section

Unit capacity, BPSD 30 42



Heat fired, Gcal/h 38.5 42.7

Heat flux, Kcal/h m2 27,000 28,500



Case 5 Steam reformer revamping in a middle east refinery

• Identified a need of additional hydrogen production capacity of 12’000 Nm3/h

• Revamped an existing steam reformer; the upgrading project included the catalyst tubes replacement with new ones with new material (lower thickness)

• The increased catalyst volume, the higher catalyst performances and the convection review allowed to target a production increase of 20%

Hydrogen capacity, Nm3/h 60,000 72,000

Fuel+feed consumption, Gcal/h 247 298

Overall steam production, t/h 120 158

Export steam, t/h 63 93



The importance of the fired heater specialist

360° vision on fired heaters

Dampers & stackDampers & stack

Fans and Fans and blowersblowers

Pressure profilePressure profile

Heat recovery Heat recovery sectionsection

Pressure partsPressure parts

Tube supports & tube Tube supports & tube sheetssheets

Burners operationBurners operation

Emission Emission reductionsreductions

MechanicalMechanical

ReRe--ratingrating

ProcessProcess


Giampiero CaronnoSales Manager, Equipment DivisionFoster Wheeler Italiana Spa

[email protected] www.fwc.com

Thank you

rrtc sept.05 g caronno fired heaters presentationjh final 1 animated

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