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Heaters Efficiency

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Optimizing Fired Heaters

New Approach to Optimizing Fired HeatersAshutosh Garg, Furnace ImprovementsSugar Land Texas, USA

IETC, Houston- Save Energy in Fired HeatersMay 12-13, 1999by Ashutosh Garg,Furnace Improvements, Sugar Land, TX1Energy ConsumptionPetroleum Refining 7.5% of the total energy consumption in USA0.40 MMBtu/ BBL of oilTotal Energy consumed in refining- 7.1 Quadrillion BTU/yrEnergy cost -$6/MMBtuTotal Energy Cost- 42 Billion /yrFired heaters -40-70% of the energy

IETC, Houston- Save Energy in Fired HeatersMay 12-13, 1999by Ashutosh Garg,Furnace Improvements, Sugar Land, TX2Energy ConsumptionA Typical refinery process 100,000 BPDConsumption of 0.40 MMBTU/BBL$6 per MMBTUEnergy bill of $ 87.6 million per year.

Potential Saving

1% Efficiency improve $876,000/Year3Fired HeatersEssential component in Petrochemical and Chemical Plants

Each refinery has 20-50 fired heaters

Design efficiency - 70-90%Operating efficiency is even less than design.

4Maintaining Design OperationMaintain the design conditions (very difficult)

In the field, heater loads change constantly due to variations in:Feed flow rateFeed temperatureFuel compositionAmbient temperature

The heater will be operating a non-optimal conditionsRequires optimization 24/7

5How to Maintain the Design Efficiency?When the heater conditions change, adjustments in the heater are required.Manual adjustments are provided- not adequateOptimizing the fired heater will:Reduce Energy ConsumptionIncrease run lengthMinimize maintenanceFIS has proposed two prong approachSoftware based- Heater Performance IndexHardware based- Draft & Excess O2 Control

6Fired HeaterHeat liberated by the combustion of fuels is transferred to fluids contained in coils

Fired Heater:Radiant SectionConvection Section Stack

www.heatflux.com

7Typical heater efficiencyNatural Draft- 70-84%Balance Draft-90-92%Natural Draft heaters in Industry- 86%Balanced Draft heaters in Industy-12%Typical stack temperature 500-800 FTypical stack Oxygen- 2-10%Target Oxygen-2-3%Plenty of room for optimization

8CombustionCombustion RequiresAir ( 0.21O2 + 0.79 N2)FuelIgnition source

Complete CombustionExcess air

Incomplete CombustionEnergy Loss CO and H2 are released

9DraftPressure inside the heaterCombustion air is drawn inside the heater through the burners air registerHot Flue gas flows out of the heater through the stack

Types of DraftNatural Draft (ND)> 80%Forced Draft (FD) < 1%Induced Draft (ID) 10%Balanced Draft 10%

10DraftStack Dampers helps control the draft

Arch is the highest pressure point in the heater

Excess or shortage of draft is not acceptable

11Burner OperationCorrect combustion in firebox include:The firebox is clearNo smoky appearanceBurners flames are steady and well-formedCheck burners regularly

Adjusting burner registers to control air intake

12Air LeakagesAir entering in to furnace from a number of places:

PeepholesHeader box doorsTube guide openingFeed tubes entering and exitsNot pressure tight structure

IETC, Houston- Save Energy in Fired HeatersMay 12-13, 1999by Ashutosh Garg,Furnace Improvements, Sugar Land, TX13Heater OptimizationTarget set 2-3% O2 in the flue gas.Operating conditions fluctuates :Manual control /adjustmentsOperators Number going downExperience going downNeed training

IETC, Houston- Save Energy in Fired HeatersMay 12-13, 1999by Ashutosh Garg,Furnace Improvements, Sugar Land, TX14Optimisation Case Study -1FIS performed a tuning job for a refinery.

Heater:Depentanizer reboiler heaterHorizontal tube box Absorbed heat duty - 87 MMBtu/hr 15 up fired burnersThe stacks is connected to a large common stackTwo off take ducts provided with manual dampers

15Optimisation ApproachCheck draftAdjust using off-take dampers

Check excess O2Adjust burner register

Check burnersLight up all burnersCheck Flames/Firebox

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19

20Crude Heater TuningCase Study -2

Natural Draft Crude Heater

Horizontal tube

Up-fired burners

11 burners

21 Before & After TuningFuel gas flow, MSCFDFuel gas pressure, psig

Fuel gas Flow and PressureFired Heaters Operation School - Crude and Coker UnitsMay, 200122Before & After Tuning

Tube Skin Temp

23RecommendationsFurnace working off design conditionsPoor quality of dampersLower number of operatorsOperator without sufficient training

SoftwareHeater Performance Index (HPI)

Hardware Draft control systemExcess O2 control system

Observations in Refineries24Heater Performance IndexAnalyzes the performance of Fired Heater 24/7Built into DCSGenerates guidelinesBuilt in intelligenceCustomized modeling

Thermal EfficiencyFuel gas rate, Draft, Excess O2, Tube skin temperatures, Feed flow rate, Pressure drop, Coking rate, Air preheater performance

25Crude Flow RatesTAG No.SERVICEUNITSSET POINT8/15/20098/16/20098/17/2009Data 1Data 2Data 3PROCESS57FC0009.PVTotal Crude FlowBPH4337.65249.14807.34637.757FC0001.PVCrude Flow to Pass 1BPH542.2709.5711.6668.057FC0002.PVCrude Flow to Pass 2BPH542.2676.5725.0725.057FC0003.PVCrude Flow to Pass 3BPH542.2670.8671.1635.657FC0004.PVCrude Flow to Pass 4BPH542.2729.1731.1686.357FC0005.PVCrude Flow to Pass 5BPH542.2729.1731.2686.357FC0006.PVCrude Flow to Pass 6BPH542.2695.1710.1680.257FC0007.PVCrude Flow to Pass 7BPH542.2737.4743.8711.8AverageBPH542.2706.7717.7684.726Coil Inlet PressureTAG No.SERVICEUNITSSET POINT8/15/20098/16/20098/17/2009Data 1Data 2Data 3PROCESS57PI0054.PVCrude Inlet Pressure (Pass 1)psig147.9278.9287.4286.057PI0055.PVCrude Inlet Pressure (Pass 2)psig147.9296.0309.6309.857PI0056.PVCrude Inlet Pressure (Pass 3)psig147.9275.9282.8284.857PI0057.PVCrude Inlet Pressure (Pass 4)psig147.9286.0294.8293.057PI0058.PVCrude Inlet Pressure (Pass 5)psig147.9281.7290.4288.757PI0059.PVCrude Inlet Pressure (Pass 6)psig147.9283.8292.4290.257PI0060.PVCrude Inlet Pressure (Pass 7)psig147.9298.2310.0306.8Averagepsig147.9285.7295.3294.127Fluids Cross-over Temperatures.TAG No.SERVICEUNITSSET POINT8/15/20098/16/20098/17/2009Data 1Data 2Data 3PROCESS57TI0583 Crude Inlet Temperature oF542557.2553.8555.357TI0590Cross-over Temp. (Pass-1)oF610585.1581.9583.657TI0591Cross-over Temp. (Pass-2)oF610589.7586.9587.957TI0592Cross-over Temp. (Pass-3)oF610592.0589.4590.357TI0593Cross-over Temp. (Pass-4)oF610597.1594.2595.857TI0618Cross-over Temp. (Pass-5)oF610594.5591.9593.257TI0619Cross-over Temp. (Pass-6)oF610590.9588.4589.757TI0620Cross-over Temp. (Pass-7)oF610594.4591.1593.0AVERAGE Cross-over Temp.oF610.0590.9588.0589.428Coil Outlet TemperaturesTAG No.SERVICEUNITSSET POINT8/15/20098/16/20098/17/2009Data 1Data 2Data 3PROCESS57TI0633Coil Outlet Temp. (Pass 1)oF730686.8687.0687.457TI0634Coil Outlet Temp. (Pass 2)oF730678.6678.3677.557TI0635Coil Outlet Temp. (Pass 3)oF730680.2680.6679.057TI0636Coil Outlet Temp. (Pass 4)oF730678.5678.6679.957TI0629Coil Outlet Temp. (Pass 5)oF730683.4683.5683.757TI0630Coil Outlet Temp. (Pass 6)oF730670.1670.0670.957TI0631Coil Outlet Temp. (Pass 7)oF730683.0682.2683.3AVERAGE Coil Outlet Temp.oF730.0679.9679.9680.129Heater Performance Index. Remarks

30Heater Performance Index. Remarks

31

Heater Performance Index

32Oxygen & Draft Control System (Natural Draft Heater)

33

Draft Control System34Stack dampersReliableCorrectly sizedPneumatically operatedOpposed blades

Reliable DampersOpposed blades vs. Parallel Blades

36Excess O2 ControlControl air supply to burnersPneumatically operated dampers or registersProvide proper control schemeDamper opening is provided based on DraftExcess O2Firing rateOther parametersSavings realized through out the day

SummaryManual controls are not adequateEnergy prices are highAdvanced Controls possibleUse DCS based or PLC basedProvide adequate safe guards Intelligent analysis of heater parametersSubstantial savings can be realizedPayout will be less than a year in most cases

Thank you very muchQuestions and comments are welcome

39Drag the side handle to change the width of the text block.CONVECTIONSECTIONSTACK________BURNERS0.05"- 0.1"W.G. DRAFTDRAFT AT RADIANT SECTION OUTLET, R0RADIANT SECTION(SE)a STACKEFFECTIN STACKPc(SE)cNEGATIVE PRESSURE 0.05"- 0.1" W.G. AT TOP OF RADIANT SECTIONPb(SE)rPaNEGATIVE PRESSUREPOSITIVEPRESSURE0STACK EXIT LOSSChart40.60352265370.61901813420.60674231820.59391874780.59998898240.61230636960.61826444610.61887395660.61260860170.60580666610.5844399760.61055521330.59905813620.60192180240.59563500110.58634293920.61482827490.62006065790.59897967960.58430709240.59801861620.60538014090.59840687430.59116159270.601359450.60154279570.59719686430.60144493520.59524247780.60443812090.61645952360.58068180840.58911985860.59383782810.59241413510.59972742040.59253013790.59194603870.60727529450.62670610080.59759103970.59541116550.59836677490.60257306440.60268612360.60540387010.61692101190.59821613940.59057917560.60620753970.61758690180.6105257770.60304395420.60604035390.60977641430.60169658510.61020612340.60997850310.59311519830.58796019070.59898796980.58925941050.58568669120.60074104850.59804564950.59439128970.57396043190.58142252040.58367445340.57589835820.57847222760.56315925180.57435343580.58029523230.59431049020.59098503530.59517717740.58327754460.58848739980.58266707290.57595446730.57186481150.56399403970.58741291680.59069127360.58254566340.58189356050.56538427160.56743471640.5621946440.58695112810.58305563140.57447724830.57455240080.55570875750.57459445260.56228938070.58807628360.56760893090.55350947940.59464552270.58590193620.57321851840.55636861010.58604695480.60037201410.59963592770.58203767790.57516791880.58505194960.5987623320.60571204960.61

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