Assessment of Gas Flaring Activity Effects on Its Local Environment

A Term Paper on Air Pollution; Oil and Gas Engineering

By:

Henry Olayemi Falokun

Memorial University of Newfoundland, Canada 2012

i

Abstract

This term paper will assess empirically the adverse effect of gas flaring on the Nigeria’s Niger-Delta

environment and also the economic advantage of eliminating it. Globally, gas flares emit about 390

million tons of carbon dioxide every year in contribution to global emissions of CO2; flaring does not only

pose the serious problem of energy wastage, it plays a role in the increase of greenhouse gas emissions.

According to 2010 World Bank record, Nigeria flares the second largest volume of gas of any producer

accounting for 11.34% of the world's gas flaring, and this represents about one third of her total CO2

emissions. Archival series of data available from the World Bank records and Nigerian National

Petroleum Company (NNPC) will be and analyzed statistically and trend fitted. The result is expected to

show that the reduction of gas flaring in Nigeria will not only contribute to energy efficiency but

significantly reduce greenhouse gas emission and thus climate change mitigation.

ii

Table of Contents

Abstract ......................................................................................................................................................... i

List of Figures ............................................................................................................................................... iii

List of Tables ................................................................................................................................................ iii

Introduction .................................................................................................................................................. 1

Case Study Description ................................................................................................................................. 2

Why Gas Flaring Happens ............................................................................................................................ 3

Procedure and Tools for Air Pollution Due to Flaring ................................................................................. 4

Factors Affecting Dispersion ........................................................................................................................ 5

Wind Speed ............................................................................................................................................... 5

Ground Conditions/Local Terrain effects: ................................................................................................. 5

Atmospheric Stability: ............................................................................................................................... 6

Height of the Release above ground: ....................................................................................................... 7

Momentum of the released material (Plume rise from flares): ............................................................... 7

Pollution Dispersal Assessment Results ...................................................................................................... 8

Assumptions .............................................................................................................................................. 8

Pollutant Dispersion Result – Class A Atmospheric Condition.................................................................. 9

Pollutant Dispersion Result – Class B Atmospheric Condition ................................................................ 11

Pollutant Dispersion Result – Class C Atmospheric Condition ................................................................ 13

Pollutant Dispersion Result – Class D Atmospheric Condition ............................................................... 15

Pollutant Dispersion Result – Class E Atmospheric Condition ................................................................ 17

Pollutant Dispersion Result – Class F Atmospheric Condition ................................................................ 19

Conclusions and Observations ................................................................................................................... 21

References .................................................................................................................................................. 22

iii

List of Figures

Figure 1 Gas flaring activities in close proximity to settlements. (Source: World Bank, 2011) ..................................... 3

Figure 2 Plume Dispersion from Stack Height ............................................................................................................... 4

Figure 3 Effect of ground conditions on vertical wind gradient .................................................................................... 6

Figure 4 Air temperatures as a function of altitude for Day and Night condition ......................................................... 6

Figure 5 Diffusion of Flare Pollutant - Class A Scenario ................................................................................................. 9

Figure 6 Class A Scenario - 3D Surface Plot ................................................................................................................. 10

Figure 7 Effects on Close Proximity - Class A ............................................................................................................... 10

Figure 8 Effects on Far Distances - Class A ................................................................................................................... 10

Figure 9 Diffusion of Flare Pollutant - Class B Scenario ............................................................................................... 11

Figure 10 Class B Scenario - 3D Surface Plot ................................................................................................................ 12

Figure 11 Effects on Close Proximity - Class B ............................................................................................................. 12

Figure 12 Effects on Far Distances - Class B ................................................................................................................. 12

Figure 13 Diffusion of Flare Pollutant – Class C Scenario ............................................................................................ 13

Figure 14 Class C Scenario - 3D Surface Plot ................................................................................................................ 14

Figure 15 Effects on Close Proximity - Class C ............................................................................................................. 14

Figure 16 Effects on Far Distances - Class C ................................................................................................................. 14

Figure 17 Diffusion of Flare Pollutant - Class D Scenario ............................................................................................. 15

Figure 18 Class D Scenario - 3D Surface Plot ............................................................................................................... 16

Figure 19 Effects on Close Proximity - Class D ............................................................................................................. 16

Figure 20 Effects on Far Distances - Class D ................................................................................................................ 16

Figure 21 Diffusion of Flare Pollutant - Class E Scenario ............................................................................................. 17

Figure 22 Class E Scenario - 3D Surface Plot ................................................................................................................ 18

Figure 23 Effects on Close Proximity - Class E ............................................................................................................. 18

Figure 24 Effects on Far Distances - Class E ................................................................................................................. 18

Figure 25 Diffusion of Flare Pollutant - Class F Scenario ............................................................................................. 19

Figure 26 Class F Scenario - 3D Surface Plot ................................................................................................................ 20

Figure 27 Effects on Close Proximity - Class F.............................................................................................................. 20

Figure 28 Effects on Far Distances - Class F ................................................................................................................. 20

List of Tables

Table 1 Top 20 Flaring Country (GGRF, 2011)................................................................................................................ 2

Table 2 Pasqual stability classes A to F .......................................................................................................................... 7

Table 3 Ground level pollution dispersion - Class A Scenario ........................................................................................ 9

Table 4 Ground level pollution dispersion - Class B Scenario ...................................................................................... 11

Table 5 Ground level pollution dispersion - Class C Scenario ...................................................................................... 13

Table 6 Ground level pollution dispersion - Class D Scenario ...................................................................................... 15

Table 7 Ground level pollution dispersion - Class E Scenario ...................................................................................... 17

Table 8 Ground level pollution dispersion - Class F Scenario ...................................................................................... 19

1

Introduction

Flaring is the practice of burning gas that is deemed uneconomical to collect and sell. Flaring is also used

to burn gases that would otherwise present a safety problem.

Flares emit a host of air pollutants, depending on the chemical composition of the gas being burned and

the efficiency and temperature of the flare. Flaring results in hydrogen sulfide emissions if hydrogen

sulfide is present in large enough amounts in the natural gas. There may also be additional by-products

formed if some of the chemicals used during the drilling or hydraulic fracturing process are converted to

a gaseous form and are burned along with the natural gas.

During upstream petroleum operations, flares are commonly used either for routine or emergency

purpose in the removal of associated gas for safe operations. This may be considered a better

alternative to vent boom due to the anticipated destruction of natural gas but the resulting several air

pollutants identified as emission products from this activity calls for another approach in natural gas

removal. Though IPCC (1996) recognized carbon dioxide (CO2) and water (H2O) as major output from

gas flares, Sonibare and Akeredolu (2004) predicted other products to include carbon monoxide (CO),

nitrogen oxide (NO), and nitrogen dioxide (NO2), from “sweet” natural gas while “sour” gas emits

sulphur dioxide (SO2) in addition. Incomplete combustion may be an impetus for the release of volatile

organic compounds (VOCs) into the atmosphere from this same source. These additional products are

attributed to the variations in operating conditions of gas flares and the gaseous emissions have

degradation potential on the environment either as primary or secondary pollutants.

The Ventura County Air Pollution Control District, in California has estimated that the following air

pollutants may be released from natural gas flares: benzene, formaldehyde, polycyclic aromatic

hydrocarbons (PAHs, including naphthalene), acetaldehyde, acrolein, propylene, toluene, xylenes, ethyl

benzene and hexane. Researchers in Canada have measured more than 60 air pollutants downwind of

natural gas flares. (Leahey, 2001)

2

Case Study Description

The case study of this term paper will focus on the southern part of Nigeria, Niger Delta, where there are

high flaring activities from the oil and gas producing facilities located in the region. All data as made

available by the ministry of environment and the Department of Petroleum Resources (DPR) of Nigeria

online are referenced and assumed data are indicated as well.

Nigeria flares 14.6 billion3 m of natural gas per year in conjunction with the exploration of crude oil in

the Niger Delta (GGFR 2011). This high level of gas flaring is equal to approximately one quarter of the

current power consumption of the African continent (GGFR 2011). This problem has been produced by a

range of international oil companies which have been in operation for over four decades (Africa News

Service 2003). The economic and environmental ramifications of this high level of gas flaring are serious

because this process is a significant waste of potential fuel which is simultaneously polluting water, air,

and soil in the Niger Delta.

Table 1 Top 20 Flaring Country (GGRF, 2011)

It is shocking to see the endless burning of this gas 24 hours a day. Even though Nigeria has grown to be

fairly dependent on oil and it has become the center of current industrial development and economic

activities in the country, Nigeria still rarely consider how oil exploration and exploitation processes

3

create environmental, health, and social problems in local communities near oil producing fields

(O’Rourke and Connolly 2003). For this reason, I hope that this study helps to be more aware of the

actual adverse effect the volume of flaring in the region has on the quality of the air at distances away

from the flare zones.

Figure 1 Gas flaring activities in close proximity to settlements. (Source: World Bank, 2011)

Why Gas Flaring Happens

In many oil fields, large volumes of gas are produced with crude oil when it is brought to the surface.

This is particularly true in the Niger Delta where much of the oil has a high proportion of this ‘associated’

gas. When most producing companies first built many of its production facilities in the 1950s, there was

little demand or market for gas in many parts of the world, including Nigeria. So, associated gas (AG)

was usually burned off safely – a process called flaring. Since then, demand for gas in Nigeria and other

countries have now grown. Technology to harness, liquefy and export natural gas to distant markets has

become commercial and climate change has become an increasingly important issue.

Today, most people agree that continuous flaring of associated gas must be reduced significantly. It

contributes to greenhouse gases that cause climate change and it is a waste of resources and revenue.

There are more various reasons for the continuous gas flaring. From a political perspective, as Michael

Watts (2001) said “In Nigeria, oil became the basis for important forms of political mobilization,” in

which petro-capital became the cause of political violence against those advocating environmental

justice or compensation for the costs of ecological degradation. The Nigerian government has not

enforced environmental regulations effectively because of the overlapping and conflicting jurisdiction of

separate governmental agencies governing petroleum and the environment as well as because of non-

transparent governance mechanisms (Kaldany 2001, GGFR 2002). Neither the Federal Environmental

Protection Agency (FEPA) nor the Department of Petroleum Resources (DPR) has implemented anti-

flaring policies for natural gas waste from oil production, nor have they monitored the emissions to

ensure compliance with their own regulations (Manby 1999).

4

From an economic perspective, the Nigerian government’s main interest in the oil industry is to

maximize its monetary profits from oil production (ESMAP 2001). Oil companies find it more

economically expedient to flare the natural gas and pay the insignificant fine than to re-inject the gas

back into the oil wells. Additionally, because there is an insufficient energy market especially in rural

areas (GGFR 2002), oil companies do not see an economic incentive to collect the gas so they flare the

gases as they are produced.

This paper, however, calls attention to the fact that in addition to this ethical concern of gas flaring,

there are very real potential economic and environmental benefits of recovering the gas as an energy

source. Correcting these market failures would be a simple way to ensure that the natural gas currently

flared is used more efficiently.

Procedure and Tools for Air Pollution Due to Flaring

The objectives of this study are achieved partially by the use of Dispersion Models of Gaussian

puff/plume model for buoyant gaseous releases from both gas and liquid sources. The model assumes a

Gaussian concentration distribution within the plume. For the steady state situations considered in this

study, such distribution is represented mathematically by the following relation:

Figure 2 Plume Dispersion from Stack Height

Where

C (x,y,z) is the avg. concentration (kg/m3),

H is the height of the releasing source (m),

X, Y, and Z, are distances in downwind, cross wind and vertical direction, respectively (m)

5

Q is release strength (kg/s)

U is wind velocity (m/s)

σy and σz are dispersion coefficients in y and z direction respectively (m). σy and σz is a function of

stability class, downwind distance.

Factors Affecting Dispersion

Dispersion models describe the airborne transport of toxic materials away from the release site into the

community. After a release the airborne toxic material is carried away by the wind in a characteristic

plume, as shown in Figure 2 Plume Dispersion from Stack Height above.

The maximum concentration of toxic material occurs at the release point (which may not be at ground

level). Concentrations downwind are less, because of turbulent mixing and dispersion of the toxic

substance with air. A wide variety of parameters affect atmospheric dispersion of toxic materials

considered in this exercise is:

• Wind Speed

• Atmospheric Stability

• Ground Conditions

• Height of the Release above ground

• Initial momentum of the released material

Wind Speed

• Any emitted gas is initially diluted with the passing volumes of air.

• The emitted gas is carried downwind faster but is diluted faster by a larger quantity of air.

• Wind speed and direction are often presented by wind rose diagram.

• Near-neutral and stable air condition wind profile is given by:

Where, p is the power co-efficient. For Urban area p = 0.40; Sub urban area p =0.28; and Rural area p =

0.16.

Ground Conditions/Local Terrain effects:

• Ground conditions/Terrain Characteristics affect the mechanical mixing at the surface and the

wind profile with height.

• Trees and buildings increase mixing, whereas lakes and open areas decrease it.

• Following Figure shows the change in wind speed versus height for a variety of surface

conditions.

6

Figure 3 Effect of ground conditions on vertical wind gradient

Atmospheric Stability:

Stability is defined by atmospheric vertical temperature gradient.

At day time, the air temperature decreases rapidly with height, encouraging vertical motions. In the

night time, the temperature decrease is less, resulting in less vertical motion. Laps rate: Negative of the

temperature gradient in atmosphere. The dry adiabatic lap’s rate:

Figure 4 Air temperatures as a function of altitude for Day and Night condition

Atmospheric stability is classified into:

Unstable: Sun heats ground faster than heat can be removed so that air temperature near the ground is

higher than the air temperature at higher elevations.

Neutral: The air above the ground warms and the wind speed increases, reducing the effect of solar

input.

7

Stable: The sun cannot heat the ground as fast as the ground cools - temperature at ground is lower.

According to Pasqual stability classes (Denoted by A to F), the air conditions are normally classified into

six sub-classes as shown in the following table:

Table 2 Pasqual stability classes A to F

Height of the Release above ground:

Ground level concentration of a dispersed plume is decreased with the increase of source of release

height.

Momentum of the released material (Plume rise from flares):

• Effective release height depends on initial buoyancy and momentum of the released material.

The momentum of a high-velocity jet will carry the gas higher than the point of release.

• The gas heavier than air becomes neutral downwind as it mixes with air. It will initially be

negatively buoyant and will slump toward the ground.

• The gas has a lower density than air, will initially be positively buoyant and will lift upward.

For flare stack releases, Turner suggested using the empirical Holland formula to compute the additional

height resulting from the buoyancy and momentum of the release:

where

ΔH, is the correction to the release height H

us is the stack gas exit velocity (m/s)

d is the inside stack diameter (m)

u is the wind speed (m/s)

P is the atmospheric pressure (mb)

T, is the stack gas temperature (K), and

Ta is the air temperature (K).

8

Pollution Dispersal Assessment Results

This study focuses on the size of the dangerous cloud of the released gas as well as its location relative

to the source point. It should be emphasized that the aim is not to investigate or criticize a specific

installation.

However, the study considered data comparable to real situations that may develop in an oil and gas

flare stack within the country. Thus, the study may be useful and beneficial to the local industrial sector.

It should be also emphasized that the results of this study are purely computational and have not been

verified experimentally. However, so many researchers have conducted experiments using the Gaussian

model and have verified its reliability.

Different values of the meteorological parameters wind speed and atmospheric stability class as well as

the number of operating trains are considered.

Assumptions

The case assumes and deals with a wind speed of 1.5, 2.0, 2.5…6.0 m/s which were considered to be the

most often range encountered normally.

Stability classes A to F were considered for each of the wind speed cases.

In order to emphasize the environmental impact on the relatively populated areas, the source point is

assumed to be in the rural environment and the wind is assumed to blow from one direction.

Composition (by volume): 10% SO2, 10%H

2O, 23.4%CO

2, 56.6%N

2. (Badr, 2004)

Total Emission Rate: 20 Kg/s

Toxic limits of SO2: TWA 5000 mmg/m3 (2 PPM) and STEL 13000 mmg/m3 (5 PPM) (NIOSH, 2012)

Stack height (m) 60 Gas exit velocity (m/s) 20

Stack diameter (m) 0.9144 Gas exit temperature (C) 600

Emission rate (g/s) 20000 Ambient Temperature 20

9

Pollutant Dispersion Result – Class A Atmospheric Condition

Table 3 Ground level pollution dispersion - Class A Scenario

Figure 5 Diffusion of Flare Pollutant - Class A Scenario

u (m/s) Ht (m) 0 0.5 0.8 1.5 3 5 10 20 35 60 100

1.5 230.15 0 27977 55664 34253 11353 4602 1355 417 167 71 32

2 187.61 0 51020 59071 28356 8728 3482 1019 313 125 53 24

2.5 162.09 0 63773 56256 23838 7069 2798 816 250 100 43 19

3 145.07 0 69015 51918 20450 5934 2338 680 209 83 35 16

3.5 132.92 0 70043 47537 17861 5110 2007 583 179 72 30 14

4 123.81 0 68894 43540 15833 4486 1759 511 157 63 27 12

4.5 116.72 0 66690 40013 14207 3997 1564 454 139 56 24 11

5 111.04 0 64025 36931 12879 3604 1409 409 125 50 21 10

5.5 106.4 0 61217 34242 11774 3281 1281 372 114 46 19 9

6 102.54 0 58429 31888 10841 3011 1175 341 104 42 18 8

Estimated Concentration of Ground-Level Pollution (mmg/m3)

on Plume Centerline at Selected Distances (km) from Source

Wind

Velocity

Stack

Effect

10

Figure 7 Effects on Close Proximity - Class A

Figure 8 Effects on Far Distances - Class A Figure 6 Class A Scenario - 3D Surface Plot

11

Pollutant Dispersion Result – Class B Atmospheric Condition

Table 4 Ground level pollution dispersion - Class B Scenario

Figure 9 Diffusion of Flare Pollutant - Class B Scenario

u (m/s) Ht (m) 0 0.5 0.8 1.5 3 5 10 20 35 60 100

1.5 230.15 0 578 20276 46522 22828 10061 3069 953 382 162 73

2 187.61 0 5118 39880 45901 18336 7734 2316 716 287 122 55

2.5 162.09 0 14144 51777 42143 15183 6265 1859 573 230 97 44

3 145.07 0 24357 57292 38069 12910 5259 1552 478 191 81 37

3.5 132.92 0 33378 58987 34377 11211 4529 1332 410 164 70 31

4 123.81 0 40423 58600 31186 9898 3975 1166 358 143 61 27

4.5 116.72 0 45533 57138 28460 8857 3542 1037 319 128 54 24

5 111.04 0 49033 55157 26130 8011 3194 934 287 115 49 22

5.5 106.4 0 51281 52964 24127 7311 2907 849 261 104 44 20

6 102.54 0 52590 50726 22394 6723 2668 779 239 96 41 18

Estimated Concentration of Ground-Level Pollution (mmg/m3)

on Plume Centerline at Selected Distances (km) from Source

Wind

Velocity

Stack

Effect

12

Figure 11 Effects on Close Proximity - Class B

Figure 12 Effects on Far Distances - Class B Figure 10 Class B Scenario - 3D Surface Plot

13

Pollutant Dispersion Result – Class C Atmospheric Condition

Table 5 Ground level pollution dispersion - Class C Scenario

Figure 13 Diffusion of Flare Pollutant – Class C Scenario

Ht (m) 0 0.5 0.8 1.5 3 5 10 20 35 60 100

230.15 0 0 466 23993 37034 23997 10434 4434 2299 1259 727

187.61 0 9 4331 40133 35551 20112 8159 3384 1740 949 547

162.09 0 149 12261 48035 32194 17012 6665 2731 1398 761 438

145.07 0 748 21417 50679 28848 14648 5622 2287 1168 635 365

132.92 0 2047 29619 50596 25915 12823 4858 1967 1003 545 313

123.81 0 4003 36099 49204 23425 11386 4274 1725 879 477 274

116.72 0 6395 40851 47236 21321 10229 3814 1536 782 424 244

111.04 0 8973 44145 45065 19536 9281 3443 1384 704 382 219

106.4 0 11539 46296 42877 18011 8490 3138 1260 641 347 200

102.54 0 13964 47582 40764 16696 7822 2882 1156 587 319 183

Estimated Concentration of Ground-Level Pollution (mmg/m3)

on Plume Centerline at Selected Distances (km) from Source

Stack

Effect

14

Figure 15 Effects on Close Proximity - Class C

Figure 16 Effects on Far Distances - Class C Figure 14 Class C Scenario - 3D Surface Plot

15

Pollutant Dispersion Result – Class D Atmospheric Condition

Table 6 Ground level pollution dispersion - Class D Scenario

Figure 17 Diffusion of Flare Pollutant - Class D Scenario

Ht (m) 0 0.5 0.8 1.5 3 5 10 20 35 60 100

230.15 0 0 0 18 2931 10353 15415 12054 8122 5147 3225

187.61 0 0 0 489 9933 17971 17159 10946 6785 4109 2510

162.09 0 0 5 2343 16950 21913 16739 9640 5730 3392 2046

145.07 0 0 46 5571 22010 23373 15667 8498 4929 2879 1724

132.92 0 0 198 9404 25132 23499 14476 7554 4312 2497 1488

123.81 0 1 530 13159 26822 22964 13342 6778 3827 2203 1309

116.72 0 3 1063 16468 27554 22124 12318 6137 3437 1970 1167

111.04 0 9 1773 19206 27672 21164 11409 5600 3118 1781 1053

106.4 0 22 2609 21377 27406 20179 10607 5147 2852 1625 960

102.54 0 44 3518 23044 26906 19217 9899 4759 2627 1494 881

Estimated Concentration of Ground-Level Pollution (mmg/m3)

on Plume Centerline at Selected Distances (km) from Source

Stack

Effect

16

Figure 19 Effects on Close Proximity - Class D

Figure 20 Effects on Far Distances - Class D

Figure 18 Class D Scenario - 3D Surface Plot

17

Pollutant Dispersion Result – Class E Atmospheric Condition

Table 7 Ground level pollution dispersion - Class E Scenario

Figure 21 Diffusion of Flare Pollutant - Class E Scenario

Ht (m) 0 0.5 0.8 1.5 3 5 10 20 35 60 100

132.1 0 0 0 190 11621 25586 28278 21795 16487 12454 9549

125.51 0 0 0 343 12725 24294 24665 18349 13691 10268 7842

120.81 0 0 0 501 13172 22822 21868 15882 11740 8761 6673

117.22 0 0 0 650 13277 21412 19660 14026 10297 7656 5820

114.36 0 0 0 786 13194 20126 17876 12578 9185 6810 5169

111.99 0 0 0 909 13008 18970 16404 11414 8299 6139 4654

109.99 0 0 0 1017 12767 17936 15169 10458 7576 5594 4236

108.27 0 0 0 1113 12496 17009 14116 9656 6974 5141 3890

106.76 0 0 0 1198 12212 16175 13209 8974 6465 4759 3598

105.42 0 0 0 1272 11924 15423 12417 8387 6028 4432 3348

Estimated Concentration of Ground-Level Pollution (mmg/m3)

on Plume Centerline at Selected Distances (km) from Source

Stack

Effect

18

Figure 23 Effects on Close Proximity - Class E

Figure 24 Effects on Far Distances - Class E Figure 22 Class E Scenario - 3D Surface Plot

19

Pollutant Dispersion Result – Class F Atmospheric Condition

Table 8 Ground level pollution dispersion - Class F Scenario

Figure 25 Diffusion of Flare Pollutant - Class F Scenario

u (m/s) Ht (m) 0 0.5 0.8 1.5 3 5 10 20 35 60 100

1.5 119.83 0 0 0 0 21 732 4221 6474 6395 5562 4605

2 114.36 0 0 0 0 43 1027 4725 6597 6284 5361 4392

2.5 110.46 0 0 0 0 68 1260 4970 6509 6047 5092 4142

3 107.49 0 0 0 0 94 1441 5072 6334 5778 4818 3898

3.5 105.11 0 0 0 0 119 1581 5092 6127 5510 4560 3674

4 103.14 0 0 0 0 144 1689 5062 5913 5255 4322 3471

4.5 101.48 0 0 0 0 167 1772 5004 5701 5018 4107 3289

5 100.05 0 0 0 0 188 1837 4929 5498 4800 3911 3125

5.5 98.799 0 0 0 0 208 1886 4843 5305 4599 3733 2976

6 97.69 0 0 0 0 226 1922 4753 5123 4414 3571 2842

Estimated Concentration of Ground-Level Pollution (mmg/m3)

on Plume Centerline at Selected Distances (km) from Source

Wind

Velocity

Stack

Effect

20

Figure 27 Effects on Close Proximity - Class F

Figure 28 Effects on Far Distances - Class F Figure 26 Class F Scenario - 3D Surface Plot

21

Conclusions and Observations

Gas flaring is not only the cause of economic loss, but also the cause of environmental degradation and

health risk. Theoretically, the combustion processes with complete combustion create relatively

innocuous gases such as carbon dioxide and water (Leahey and Preston 2001). However, because the

flaring efficiency depends on wind speeds, stack exit velocity, stoichiometric mixing ratios, and heating

value, the flaring in reality is rarely successful in the achievement of complete combustion (Leahey and

Preston 2001).

The result shows that gas flaring produces significant amounts of air pollutant concentration, the flaring

process with incomplete combustion emits a variety of compounds, including methane, propane, and

hazardous air pollution such as volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons

(PAHs), and soot (Kindzierski 2000). And, it could be assumed that the gas flaring not equipped with a

gas scrubber will produce much more of those pollutants than a gas flaring equipped with a gas scrubber

as assumed by this effort.

22

References

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