N EW D EVELOP MEN TS IN FLARIN G P R E S E N T E D B Y E AS T H AR R I S COU N TY AI R P AR TN E R S
Flare Discussion 2 � Types � Regulation � Operation � TCEQ Flare Study � Next Steps � Anticipated Results
What do you know about flares? 3 ?
Single Point Flare Types of Flares 4 Staged Flare
Types of Flares Air-assisted Flares 5
Types of Flares Multi-point Ground Flare 6
Types of Flares Enclosed Ground Flare and Tips 7
Types of Flares 8 Enclosed Ground Flare and Flare Tips (from inside)
Types of Flares Steam-assisted Flares 9
Ground Flares Types of Flares 10 Elevated Flare
Flare Operation 11 � Primary function is as a safety device � Protect equipment from catastrophic failure (pressure relief) � Protect employees/ community from exposure to pollutants � Designed with safety in mind: big enough to handle the largest release � Over the years, flare operations have evolved � Initially designed only for emergencies (safety devices) � Then became “dump” for waste gases, off-spec materials, etc. � Later used as alternative to venting directly to atmosphere � Today used as emissions control devices for most process vents
Flare Operation 12 � In addition to process gases, purge gas and assist gas are often routed to flares � Purge gas (usually natural gas) sweeps the flare header of oxygen, corrosives, reactives, and inerts � Assist gases (usually steam or air) improve mixing for better combustion, help protect the flare tip from heat damage, and help minimize visible emissions
Flare Operation 13 � Flare operators have been trained to add sufficient steam (or air) to prevent visible emissions � Over the years this has translated into “more is better” � Many facilities have reduced continuous flaring, resulting in flares that operate well below their design capacities � Operating at <1% of design capacity is known as “high turndown” � Some recent study data indicate that this combination of high flare turndown + increased assist rate may be contributing to lower flare destruction efficiency (DRE) � DRE = how well a flare destroys the materials being burned
“Over-steamed” Flare 14 Good looking flare? Here’s what’s really going on!! Video Source: TCEQ Houston Office
“Over-steamed” Flare 15 TCEQ R12 oversteam video.wmv Qualitative Test with IR Camera Shows Significant Flare Hydrocarbon Emissions In the Presence of Visible Steam Video Source: TCEQ Houston Office
Background 16 � EPA regulates flares through a rule called “60.18” Visible emissions limited to 5 minutes in 2 hours � Flame must be present at all times � Limits on minimum net heating value and maximum gas exit velocity � Monitor to ensure the above conditions are met � � Flares meeting all 60.18 requirements assumed to have a 98% destruction and removal efficiency (DRE) For every 100 pounds VOCs fed to the flare, 98 pounds will be destroyed and only 2 pounds � will be emitted � Air quality studies raised questions about differences in measured air quality vs. estimated emissions Texas 2000 Air Quality Field Study � 2006 Texas Air Quality Study (TexAQSII) � Numerous Houston-area flyovers � 2009 Study of Houston Atmospheric Radical Precursors (SHARP) � � Some skepticism about flare DRE arose
TCEQ Flare Study 17 � $2.2 million study conducted in Sept. 2010 � Objective to measure DRE at very low turndown � Not emergency flare scenarios � Limited test conditions � Vent gas was simple mixture of propylene, natural gas, and nitrogen � Test conditions met 60.18 requirements � Assist gas rates varied from zero to point of snuffing out flare flame � Emissions sampler & remote sensing instruments
Extractive Sampler Parts 18 Flue Ga s Ed uctor Pitot GPS Extra ctiv e Sa m p le Inlet Sa m p le Positioning Lines Cha ins Elev a tion Cha in Forced Air Device Positioned with Crane while Extracting Samples of Flare Emissions
Test Point A4.6 DRE (%) 99.4 Test Results at Incipient Smoke Point 350 Btu Btu/scf Vent Gas 937 lb/hr 19
Test Point S3.1 Test Results with Transparent Flame 20
Test Point S3.6 Test Results with Visible Flame 21
Effect of Small Increase in Steam 22 Test Point S4.3 Test Point S4.2 Test Point S4.7 Visible Flare and Invisible Steam Result in >99% DRE Visible Steam Results in Rapidly Falling DRE
Why is High DRE Important? 23 Test Point S4.2 Test Point S4.7 Test Point S4.3 At 99.2% DRE, At 90.6% DRE, At 27.3% DRE, 20,000 pounds of flare gas 20,000 pounds of flare gas 20,000 pounds of flare gas results in (0.008 x 20000) = results in (0.094 x 20000) = results in (0.727 x 20000) = 160 pounds of unburned flare gas 1880 pounds of unburned flare gas 14,540 pounds of unburned flare gas Third photo has almost 100 times higher emissions compared to first photo
TCEQ Flare Test Results Summary 24 � The flares tested were able to achieve greater than 99% DRE for vent gas streams at low flow rates (high turndown) under certain conditions � For the conditions tested, the highest DRE was achieved at or near the point when smoke first appeared (incipient smoke point) � Low DRE occurred with invisible flames � Operating the flare within legal requirements of 60.18 and no visible emissions may or may not minimize emissions � Proper assist rates appear to be key to good DRE under high turndown conditions
Flares in your Area 25 � Plant Managers have provided a brief summary of the number & types of flares they have � Emergency-only flares � Process-only flares � Combination emergency & process flares
Flares in your Area 26 � Summary of DPCAC Flare Survey � 7 of 14 DPCAC plants have flares � 50 flares among the 7 plants � 3 of the 50 flares are emergency only flares 24 of the 50 flares are process only flares, with continuous flow � 10 of the 50 flares are process only flares, with intermittent flow � 13 of the 50 flares are combination flares � 13 of the 50 flares are steam-assisted � 5 of the 50 flares are air-assisted � 12 of the 50 flares have no assist � 1 plant of 7 (Shell) has flare gas recovery �
Next Steps 27 � TCEQ, EPA, and Industry are working to better understand flare performance � Industry is examining its current flare operating practices to find improvements � Looking at manual assist rates � Exploring better controls, monitoring equipment, and alternative emissions control technology that might be implemented in some cases � TCEQ is developing flare operator guidance � EPA is developing new flare rules � Flare vendors are reassessing their designs and operating recommendations
Over-Steamed? 28
Too Little Assist? “Perfect” Assist? 29
Proper Assist = High DRE 30
Results 31 � Changes to flare operations will potentially result in: � New visual landscape of small “candles” � Likelihood of seeing some short-duration visible emissions from flares � � But also… � Reduced emissions ☺ � Improved air quality ☺ � Better public health ☺
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