2011 AFRC Industrial Flares Colloquium Houston, TX September 18-21, - - PowerPoint PPT Presentation

2011 AFRC Industrial Flares Colloquium Houston, TX

September 18-21, 2011

T F Tom Farmer Zeeco Flare Applications Engineer

 2011 ZEECO, INC.  2010 ZEECO, INC.  2011 ZEECO, INC.

Company Profile

• Incorporated in 1979
• 250-acre facility located in Broken Arrow, OK
• Specialists in the design and manufacturing of combustion equipment

 2011 ZEECO, INC.

Zeeco Product Lines

Flare Systems Incineration Systems Industrial Burners

 2011 ZEECO, INC.

Flare Systems Incineration Systems Industrial Burners

Background

Fl t ti d t d b TCEQ d Th U i it f T

• Flare testing conducted by TCEQ and The University of Texas

 Determined how air assisted and steam assisted flares perform

at turndown rates

 Suggested that incorrectly designed or operated flares may

gg y g p y reduce the Destruction and Removal Efficiency (DRE) of flares

• Zeeco testing
• Zeeco testing

 Performed testing of steam assisted flares to compliment TCEQ

t t tests

 Zeeco focused on API recommended purge rates

 2011 ZEECO, INC.

Testing Instrumentation & Setup

• Performed at Zeeco Combustion Research & Test Facility in Broken

Arrow, OK

• Equipment



36” Steam Assisted Flare Tip  QFSC Steam Assisted Tip  UFSC Steam Assisted Flare Tip



Temperature elements



Temperature elements positioned on flare tip

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Testing Instrumentation & Setup

 Sample induction probe

 Inductor  Flow conditioner  Thermocouples at probe inlet

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Testing Instrumentation & Setup

 LSI FLIR GasFindIR camera  Air Hygiene emissions testing service  Miscellaneous equipment

 Video camera  Still camera  Still camera

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Testing

• Phase 1- Test API recommended purge rates with steam
• perating at cooling rates

p g g

 Three purge rates tested

 Velocity Seal purge rates G S  Gas Seal purge rates  No Seal purge rates

Velocity Seal Gas Seal No Seal Purge Gas NG NG NG Purge Rate (SCFH) 990 250 1992 (SCFH)

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Testing

 Three steam assist methods were tested for each purge rate

 Center steam only  Upper steam only  Upper steam only  Combined upper and center steam

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Testing

• Phase 2- Building a Hypothesis

 Set steam rates and adjusted gas flow to achieve a high

j g g destruction efficiency

 Set purge rates and adjusted center, upper, and combined

t fl t t hi hi h d t ti ffi i steam flow rates to achieve a high destruction efficiency

 The steam flow was turned down as low as reasonably possible without condensing

• A trend developed between the DRE and the LHV of the

combined steam and gas stream combined steam and gas stream

 2011 ZEECO, INC.

Testing

• Phase 3- Verify

Hypothesis

 Test points selected to

produce a combined stream LHV which stream LHV, which achieved a 98% destruction efficiency

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Results

• Destruction Removal Efficiency (DRE) evaluation

 CO, CO2, NOx, and total hydrocarbons were measured  The DRE calculations are based on the measured values and carbon

balance accounts for the percentage of plume captured

DRE = destruction and removal efficiency mol THC measured = total mol hydrocarbons measured in the plume sample

 2011 ZEECO, INC.

mol THCout measured = total mol hydrocarbons measured in the plume sample mol THCin measured = total mol hydrocarbons measured entering the flare

Results

• Summary

 Testing indicated that the DRE is impaired by cooling steam while

• perating at API recommended purge rates

 Strong correlation between the DRE and the LHV of the combined

gas and steam rates gas and steam rates

 The addition of center steam resulted in the largest reduction of DRE

 2011 ZEECO, INC.

Results

• Combined LHV vs. DRE with Center Steam Only

LHV vs. DRE with Center Steam Only

95 100

LHV vs. DRE with Center Steam Only

80 85 90 uction Efficiency 70 75 Destru 65 50 100 150 200 250 300 350 400 450 LHV

 2011 ZEECO, INC.

Results

• Combined LHV vs. DRE with Upper Steam Only

LHV vs. DRE with Upper Steam Only

95 100

LHV vs. DRE with Upper Steam Only

80 85 90 uction Efficiency 70 75 Destru 65 50 100 150 200 250 300 350 400 450 LHV

 2011 ZEECO, INC.

Results

• Combined LHV vs. DRE with Upper & Center Steam

LHV vs. DRE Combination Only

95 100

LHV vs. DRE Combination Only

80 85 90 ruction Efficiency 70 75 Destr 65 50 100 150 200 250 300 350 400 LHV

 2011 ZEECO, INC.

Results

• Steam to Gas Ratio vs. DRE with Upper & Center Steam

Upper & Center Steam

92 94 96 98 100

Upper & Center Steam

82 84 86 88 90 92 uction Efficiency % 72 74 76 78 80 82 Destru 70 72 1 2 3 4 5 6 7 8 9 10 Steam to Flare Gas Ratio (lb/lb)

 2011 ZEECO, INC.

Results

• Steam to Gas Ratio vs. DRE with Center Steam

Center Steam

92 94 96 98 100

Center Steam

82 84 86 88 90 92 uction Efficiency % 72 74 76 78 80 82 Destru 70 72 1 2 3 4 5 6 7 8 9 10 Steam to Flare Gas Ratio (lb/lb)

 2011 ZEECO, INC.

Results

• Steam to Gas Ratio vs. DRE with Upper Steam

98 99 100 89 90 91 92 93 94 95 96 97 81 82 83 84 85 86 87 88 89 RUCTION EFFECIENCY % 72 73 74 75 76 77 78 79 80 DESTR 67 68 69 70 71 72 1 2 3 4 5 6 7 STEAM TO FLARE GAS RATIO (LB/LB)

Z T i i h N l G CMA T i i h

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Zeeco Testing with Natural Gas (914 TU/SCF) CMA Testing with Propylene (2183 BTU/SCF)

Results

• Thermocouple evaluation

 Center Steam is used as an effective means for cooling the flare tip

800

Flare Tip Temperature 7/18/11 Afternoon

Center

500 600 700

• deg. F

Upper & Center Steam Center Steam Only

200 300 400

Temperature Level 1 Level 2 Level 3

U

100 0:14:24 0:43:12 1:12:00 1:40:48 2:09:36 2:38:24 3:07:12 3:36:00 4:04:48 4:33:36 5:02:24

Upper Steam Only

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Time

Results

• Thermocouple evaluation continued

 At low center steam rates, burning was found within the flare tip

Flare Tip Temperature 7/19/11 Afternoon

600 700 800 900

• eg. F

p p

200 300 400 500

Temperature de Level 1 Level 2 Level 3

100 200 0:00:00 1:12:00 2:24:00 3:36:00 4:48:00 6:00:00

Time

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Results

• Thermocouple evaluation continued

 When the flame was stable and located at the exit of the flare tip, a

higher DRE was observed

Flare Tip Temperature 7/22/11 Morning

500 600 700

• g. F

p p g

200 300 400

Temperature deg Level 1 Level 2 Level 3

100 7:12:00 AM 8:24:00 AM 9:36:00 AM 10:48:00 AM 12:00:00 PM

Ti

 2011 ZEECO, INC.

Time

Conclusion

• Constant cooling steam is necessary for thermal protection of

the flare tips and equipment

• Strong indication that cooling steam, while operating at API

Purge Rates does reduce destruction efficiency Purge Rates, does reduce destruction efficiency

• LHV for combined steam and gas

i f di ti th is necessary for predicting the destruction efficiency of flares

 2011 ZEECO, INC.

Recommendations

• Is this a real problem?

 Many plants operate with sweep gases that are higher than API

recommended rates

 API rates are listed as the minimum recommended purge rate

• Increase LHV combustion zone

 A minimum of 225 Btu/SCF is recommended

• Use nitrogen purge where available
• Use other means of flashback protection

 Flame arrestor  Liquid seal base of flare stack and designed for flashback

 2011 ZEECO, INC.

 Liquid seal base of flare stack and designed for flashback

 Questions

 2010 ZEECO, INC.  2011 ZEECO, INC.