2011 AFRC Industrial Flares Colloquium Houston, TX · 2011 AFRC Industrial Flares Colloquium...

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2011 AFRC Industrial Flares Colloquium Houston, TX September 18-21, 2011 T F T om Farmer Zeeco Flare Applications Engineer 2011 ZEECO, INC. 2010 ZEECO, INC. 2011 ZEECO, INC.

Transcript of 2011 AFRC Industrial Flares Colloquium Houston, TX · 2011 AFRC Industrial Flares Colloquium...

2011 AFRC Industrial Flares ColloquiumHouston, TX September 18-21, 2011

T FTom FarmerZeeco 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 SystemsIndustrial Burners

2011 ZEECO, INC.

Flare Systems Incineration SystemsIndustrial Burners

BackgroundFl 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 yreduce the Destruction and Removal Efficiency (DRE) of flares

Zeeco testing Zeeco testing

Performed testing of steam assisted flares to compliment TCEQ t ttests

Zeeco focused on API recommended purge rates

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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 operating at cooling ratesp 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 streamcombined steam and gas stream

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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 efficiencymol THC measured = total mol hydrocarbons measured in the plume sample

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

Results Summary

Testing indicated that the DRE is impaired by cooling steam while operating at API recommended purge rates

Strong correlation between the DRE and the LHV of the combined gas and steam ratesgas and steam rates

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

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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

uctio

n Effi

cienc

y

70

75

Dest

ru

650 50 100 150 200 250 300 350 400 450

LHV

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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

uctio

n Effi

cienc

y

70

75

Dest

ru

650 50 100 150 200 250 300 350 400 450

LHV

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Results Combined LHV vs. DRE with Upper & Center Steam

LHV vs. DRE Combination Only

95

100

LHV vs. DRE Combination Only

80

85

90

ruct

ion E

fficie

ncy

70

75

Dest

r

650 50 100 150 200 250 300 350 400

LHV

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

Upper & Center Steam

92949698

100

Upper & Center Steam

828486889092

uctio

n Effi

cienc

y %

727476788082

Dest

ru

7072

0 1 2 3 4 5 6 7 8 9 10

Steam to Flare Gas Ratio (lb/lb)

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Results Steam to Gas Ratio vs. DRE with Center Steam

Center Steam

92949698

100

Center Steam

828486889092

uctio

n Effi

cienc

y %

727476788082

Dest

ru

7072

0 1 2 3 4 5 6 7 8 9 10

Steam to Flare Gas Ratio (lb/lb)

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Results Steam to Gas Ratio vs. DRE with Upper Steam

9899

100

899091929394959697

818283848586878889

RUCT

ION

EFFE

CIEN

CY %

727374757677787980

DEST

R

676869707172

0 1 2 3 4 5 6 7STEAM 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 withPropylene (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

Tem

pera

ture

Level 1Level 2Level 3

U

0

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

Tem

pera

ture

de

Level 1Level 2Level 3

0

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

Tem

pera

ture

deg

Level 1Level 2Level 3

0

100

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

Ti

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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 efficiencyPurge 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

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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

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Liquid seal base of flare stack and designed for flashback

Questions

2010 ZEECO, INC. 2011 ZEECO, INC.