2011 AFRC Industrial Flares Colloquium Houston, TX September 18-21, 2011 T Tom Farmer F 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 Industrial Burners Industrial Burners Incineration Systems Incineration Systems Flare Systems Flare Systems 2011 ZEECO, INC.
Background Flare testing conducted by TCEQ and The University of Texas Fl t ti d t d b TCEQ d Th U i it f T 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 tests t 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 2011 ZEECO, INC.
Testing Instrumentation & Setup Sample induction probe Inductor Flow conditioner Thermocouples at probe inlet 2011 ZEECO, INC.
Testing Instrumentation & Setup LSI FLIR GasFindIR camera Air Hygiene emissions testing service Miscellaneous equipment Video camera Still camera Still camera 2011 ZEECO, INC.
Testing Phase 1- Test API recommended purge rates with steam operating at cooling rates p g g Three purge rates tested Velocity Seal purge rates Gas Seal purge rates G S No Seal purge rates Velocity Seal Gas Seal No Seal Purge Gas NG NG NG Purge Rate 990 250 1992 (SCFH) (SCFH) 2011 ZEECO, INC.
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 2011 ZEECO, INC.
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 steam flow rates to achieve a high destruction efficiency t fl t t hi hi h d t ti ffi i 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 2011 ZEECO, INC.
Results Destruction Removal Efficiency (DRE) evaluation CO, CO 2 , NO x , 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 mol THC out measured = total mol hydrocarbons measured in the plume sample measured = total mol hydrocarbons measured in the plume sample mol THC in measured = total mol hydrocarbons measured entering the flare 2011 ZEECO, INC.
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 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 LHV vs. DRE with Center Steam Only 100 95 90 uction Efficiency 85 80 Destru 75 70 65 0 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 LHV vs. DRE with Upper Steam Only 100 95 90 uction Efficiency 85 80 Destru 75 70 65 0 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 LHV vs. DRE Combination Only 100 95 90 ruction Efficiency 85 80 Destr 75 70 65 0 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 Upper & Center Steam 100 98 96 94 92 92 uction Efficiency % 90 88 86 84 82 82 Destru 80 78 76 74 72 72 70 0 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 Center Steam 100 98 96 94 92 92 uction Efficiency % 90 88 86 84 82 82 Destru 80 78 76 74 72 72 70 0 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 100 99 98 97 96 95 94 93 92 91 90 89 89 RUCTION EFFECIENCY % 88 87 86 85 84 83 82 81 DESTR 80 79 78 77 76 75 74 73 72 72 71 70 69 68 67 0 1 2 3 4 5 6 7 STEAM TO FLARE GAS RATIO (LB/LB) Zeeco Testing with Natural Gas Z T i i h N l G CMA T CMA Testing with i i h (914 TU/SCF) Propylene (2183 BTU/SCF) 2011 ZEECO, INC.
Results Thermocouple evaluation Center Steam is used as an effective means for cooling the flare tip Flare Tip Temperature 7/18/11 Afternoon 800 Center Center 700 Upper & Steam Center Only 600 Steam deg. F 500 Temperature 400 Level 1 Level 2 300 Level 3 200 Upper U Steam 100 Only 0 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 Time 2011 ZEECO, INC.
Results Thermocouple evaluation continued At low center steam rates, burning was found within the flare tip Flare Tip Temperature 7/19/11 Afternoon p p 900 800 700 eg. F 600 Temperature de 500 Level 1 400 Level 2 300 Level 3 200 200 100 0 0:00:00 1:12:00 2:24:00 3:36:00 4:48:00 6:00:00 Time 2011 ZEECO, INC.
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 p p g 700 600 g. F 500 Temperature deg 400 Level 1 300 Level 2 200 Level 3 100 0 7:12:00 AM 8:24:00 AM 9:36:00 AM 10:48:00 AM 12:00:00 PM Ti Time 2011 ZEECO, INC.
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 is necessary for predicting the f di ti th 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 Liquid seal base of flare stack and designed for flashback 2011 ZEECO, INC.
Questions 2010 ZEECO, INC. 2011 ZEECO, INC.
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