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New Approach to Optimizing Fired Heaters Ashutosh Garg, Furnace Improvements Sugar Land Texas, USA.

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Presentation on theme: "New Approach to Optimizing Fired Heaters Ashutosh Garg, Furnace Improvements Sugar Land Texas, USA."— Presentation transcript:

1 New Approach to Optimizing Fired Heaters Ashutosh Garg, Furnace Improvements Sugar Land Texas, USA

2 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 % of the energy

3 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

4 Fired Heaters Essential component in Petrochemical and Chemical Plants Each refinery has ≈ fired heaters Design efficiency % ▫Operating efficiency is even less than design.

5 Maintaining Design Operation Maintain the design conditions (very difficult) In the field, heater loads change constantly due to variations in: ▫Feed flow rate ▫Feed temperature ▫Fuel composition ▫Ambient temperature The heater will be operating a non-optimal conditions Requires optimization 24/7

6 How to Maintain the Design Efficiency? When the heater conditions change, adjustments in the heater are required. Manual adjustments are provided- not adequate Optimizing the fired heater will: ▫Reduce Energy Consumption ▫Increase run length ▫Minimize maintenance FIS has proposed two prong approach Software based- Heater Performance Index Hardware based- Draft & Excess O2 Control

7 Fired Heater Heat liberated by the combustion of fuels is transferred to fluids contained in coils Fired Heater: ▫Radiant Section ▫Convection Section ▫Stack

8 Typical heater efficiency Natural Draft % Balance Draft-90-92% Natural Draft heaters in Industry- 86% Balanced Draft heaters in Industy-12% Typical stack temperature – F Typical stack Oxygen- 2-10% Target Oxygen-2-3% Plenty of room for optimization

9 Combustion Combustion Requires ▫Air ( 0.21O N 2 ) ▫Fuel ▫Ignition source Complete Combustion ▫Excess air Incomplete Combustion ▫Energy Loss ▫CO and H 2 are released

10 Draft Pressure inside the heater ▫Combustion air is drawn inside the heater through the burner’s air register ▫Hot Flue gas flows out of the heater through the stack Types of Draft ▫Natural Draft (ND)> 80% ▫Forced Draft (FD) < 1% ▫Induced Draft (ID)≈ 10% ▫Balanced Draft ≈ 10%

11 Draft Stack Dampers helps control the draft Arch is the highest pressure point in the heater Excess or shortage of draft is not acceptable

12 Burner Operation Correct combustion in firebox include: ▫The firebox is clear ▫No smoky appearance ▫Burners flames are steady and well-formed Check burners regularly Adjusting burner registers to control air intake

13 Air Leakages Air entering in to furnace from a number of places: ▫Peepholes ▫Header box doors ▫Tube guide opening ▫Feed tubes entering and exits ▫Not pressure tight structure

14 Heater Optimization Target set 2-3% O2 in the flue gas. Operating conditions fluctuates : ▫Manual control /adjustments ▫Operators  Number going down  Experience going down  Need training

15 Optimisation Case Study -1 FIS performed a tuning job for a refinery. Heater: ▫Depentanizer reboiler heater ▫Horizontal tube box ▫Absorbed heat duty - 87 MMBtu/hr ▫15 up fired burners ▫The stacks is connected to a large common stack ▫Two off take ducts provided with manual dampers

16 Optimisation Approach Check draft ▫Adjust using off-take dampers Check excess O2 ▫Adjust burner register Check burners ▫Light up all burners ▫Check Flames/Firebox

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21 Crude Heater Tuning Case Study -2 Natural Draft Crude Heater Horizontal tube Up-fired burners 11 burners

22 Before & After Tuning Fuel gas flow, MSCFD Fuel gas pressure, psig Fuel gas Flow and Pressure

23 Before & After Tuning Tube Skin Temp

24 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

25 Heater Performance Index Analyzes the performance of Fired Heater 24/7 Built into DCS Generates guidelines Built in intelligence Customized modeling ▫Thermal Efficiency ▫Fuel gas rate, ▫Draft, ▫Excess O2, ▫Tube skin temperatures, ▫Feed flow rate, ▫Pressure drop, ▫Coking rate, ▫Air preheater performance

26 Crude Flow Rates TAG No.SERVICEUNITS SET POINT 8/15/20098/16/20098/17/2009 Data 1Data 2Data 3 PROCESS 57FC0009.PVTotal Crude FlowBPH FC0001.PVCrude Flow to Pass 1BPH FC0002.PVCrude Flow to Pass 2BPH FC0003.PVCrude Flow to Pass 3BPH FC0004.PVCrude Flow to Pass 4BPH FC0005.PVCrude Flow to Pass 5BPH FC0006.PVCrude Flow to Pass 6BPH FC0007.PVCrude Flow to Pass 7BPH AverageBPH

27 Coil Inlet Pressure TAG No.SERVICEUNITS SET POINT 8/15/20098/16/20098/17/2009 Data 1Data 2Data 3 PROCESS 57PI0054.PV Crude Inlet Pressure (Pass 1)psig PI0055.PV Crude Inlet Pressure (Pass 2)psig PI0056.PV Crude Inlet Pressure (Pass 3)psig PI0057.PV Crude Inlet Pressure (Pass 4)psig PI0058.PV Crude Inlet Pressure (Pass 5)psig PI0059.PV Crude Inlet Pressure (Pass 6)psig PI0060.PV Crude Inlet Pressure (Pass 7)psig Averagepsig

28 Fluids Cross-over Temperatures. TAG No.SERVICEUNITS SET POINT 8/15/20098/16/20098/17/2009 Data 1Data 2Data 3 PROCESS 57TI0583 Crude Inlet Temperature oFoF TI0590 Cross-over Temp. (Pass-1) oFoF TI0591 Cross-over Temp. (Pass-2) oFoF TI0592 Cross-over Temp. (Pass-3) oFoF TI0593 Cross-over Temp. (Pass-4) oFoF TI0618 Cross-over Temp. (Pass-5) oFoF TI0619 Cross-over Temp. (Pass-6) oFoF TI0620 Cross-over Temp. (Pass-7) oFoF AVERAGE Cross-over Temp. oFoF

29 Coil Outlet Temperatures TAG No.SERVICEUNITS SET POINT 8/15/20098/16/20098/17/2009 Data 1Data 2Data 3 PROCESS 57TI0633 Coil Outlet Temp. (Pass 1) oFoF TI0634 Coil Outlet Temp. (Pass 2) oFoF TI0635 Coil Outlet Temp. (Pass 3) oFoF TI0636 Coil Outlet Temp. (Pass 4) oFoF TI0629 Coil Outlet Temp. (Pass 5) oFoF TI0630 Coil Outlet Temp. (Pass 6) oFoF TI0631 Coil Outlet Temp. (Pass 7) oFoF AVERAGE Coil Outlet Temp. oFoF

30 Heater Performance Index. Remarks

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32 Heater Performance IndexHeater Performance Index

33 Oxygen & Draft Control System (Natural Draft Heater)

34 Draft Control System

35 Stack dampers Reliable Correctly sized Pneumatically operated Opposed blades

36 Reliable Dampers Opposed blades vs. Parallel Blades

37 Excess O2 Control Control air supply to burners Pneumatically operated dampers or registers Provide proper control scheme Damper opening is provided based on ▫Draft ▫Excess O2 ▫Firing rate ▫Other parameters Savings realized through out the day

38 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 year in most cases

39 Thank you very much Questions and comments are welcome


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