NEW DEVELOPMENTSIN

FLARINGP R E S E N T E D B Y

EAST HARRIS COUNTY AIR PARTNERS

Flare Discussion

TypesRegulationOperationTCEQ Flare Study Next Steps Anticipated Results

2

What do you know about flares?3

?

Types of Flares4

Staged Flare Single Point Flare

Types of Flares5

Air-assisted Flares

Types of Flares6

Multi-point Ground Flare

Types of Flares7

Enclosed Ground Flare and Tips

Types of Flares8

Enclosed Ground Flare and Flare Tips (from inside)

Types of Flares9

Steam-assisted Flares

Types of Flares10

Elevated Flare Ground Flares

Flare Operation

Primary function is as a safety deviceProtect equipment from catastrophic failure (pressure relief)Protect employees/community from exposure to pollutantsDesigned with safety in mind: big enough to handle the largest release

Over the years, flare operations have evolvedInitially designed only for emergencies (safety devices)Then became “dump” for waste gases, off-spec materials, etc.Later used as alternative to venting directly to atmosphereToday used as emissions control devices for most process vents

11

Flare Operation

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

12

Flare Operation

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

13

“Over-steamed” Flare

Good looking flare? Here’s what’s really going on!!

Video Source: TCEQ Houston Office

14

“Over-steamed” Flare

Qualitative Test with IR Camera Shows Significant Flare Hydrocarbon EmissionsIn the Presence of Visible Steam

Video Source: TCEQ Houston Office

15

TCEQ R12 oversteam video.wmv

Background16

EPA regulates flares through a rule called “60.18”Visible emissions limited to 5 minutes in 2 hoursFlame must be present at all timesLimits on minimum net heating value and maximum gas exit velocityMonitor 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 Study2006 Texas Air Quality Study (TexAQSII) Numerous Houston-area flyovers2009 Study of Houston Atmospheric Radical Precursors (SHARP)

Some skepticism about flare DRE arose

TCEQ Flare Study

$2.2 million study conducted in Sept. 2010

Objective to measure DRE at very low turndownNot emergency flare scenarios

Limited test conditions Vent gas was simple mixture of propylene, natural gas, and nitrogen Test conditions met 60.18 requirementsAssist gas rates varied from zero to point of snuffing out flare flame

Emissions sampler & remote sensing instruments

17

Extractive Sampler Parts

Elevation Chain

PositioningChains

ExtractiveSample

Inlet

Pitot

Flue GasEductor

GPS

SampleLines

Forced Air Device Positioned with Crane while Extracting Samples of Flare Emissions

18

Test Results at Incipient Smoke Point

Test Point A4.6

Vent Gas Btu/scf DRE (%)937 lb/hr 350 Btu 99.4

19

Test Results with Transparent Flame

Test Point S3.1

20

Test Results with Visible Flame

Test Point S3.6

21

Effect of Small Increase in Steam

Test Point S4.2 Test Point S4.7 Test Point S4.3

Visible Flare and Invisible Steam Result in >99% DREVisible Steam Results in Rapidly Falling DRE

22

Why is High DRE Important?

Test Point S4.2 Test Point S4.7 Test Point S4.3

At 99.2% DRE, 20,000 pounds of flare gasresults in (0.008 x 20000) =

160 pounds of unburned flare gas

At 90.6% DRE, 20,000 pounds of flare gasresults in (0.094 x 20000) =

1880 pounds of unburned flare gas

At 27.3% DRE, 20,000 pounds of flare gasresults in (0.727 x 20000) =

14,540 pounds of unburned flare gas

Third photo has almost 100 times higher emissions compared to first photo

23

TCEQ Flare Test Results Summary

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

24

Flares in your Area

Plant Managers have provided a brief summary of the number & types of flares they have

Emergency-only flaresProcess-only flaresCombination emergency & process flares

25

Flares in your Area

Summary of DPCAC Flare Survey

7 of 14 DPCAC plants have flares 50 flares among the 7 plants3 of the 50 flares are emergency only flares24 of the 50 flares are process only flares, with continuous flow10 of the 50 flares are process only flares, with intermittent flow13 of the 50 flares are combination flares13 of the 50 flares are steam-assisted5 of the 50 flares are air-assisted12 of the 50 flares have no assist1 plant of 7 (Shell) has flare gas recovery

26

Next Steps

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

27

Over-Steamed?28

Too Little Assist? “Perfect” Assist?29

Proper Assist = High DRE30

Results

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 ☺

31