2G

Taweelah B IWPP - Environmental Impact Assessment (EIA)

Air Dispersion Modelling Report

Prepared By

Dome Oilfield Equipment & Services

December 06, 2004

Dome Oilfield Equipment & Services Al Masaood Tower, Hamdan Street P.O. Box 6924, Abu Dhabi, United Arab Emirates Tel: +0971 2 6348800 Fax: +971 2 6348826 E-mail: [email protected]

Dome International LLC Spectrum Building, Qataiyat Road, P.O. Box 24652, Dubai, United Arab Emirates Tel: +971 4 3366144 Fax: +971 4 3359434 E-mail: [email protected]

http://www.domeint.com

Taweelah B Extension Project Air Dispersion Modelling Report

TABLE OF CONTENTS 1.0 Introduction 2 2.0 Methodology.. 4 3.0 Input Data10 4.0 Results 12

Appendix I NOx/NO2 Conversion Appendix II Air Emission Input - ADWEA

Appendix III Air Emission Input - Marubeni/PB

Dome Oilfield Equipment & Services Page 1 December, 2004 ED42.04


1.0 INTRODUCTION

Background

1.1 Marubeni Corporation has contracted Dome Oilfield Equipment & Services (Dome) to update the air dispersion modelling study carried out for Taweelah Power Complex on behalf of Abu Dhabi Water & Electricity Authority (ADWEA).

1.2 The main objective of this air dispersion modelling exercise is to incorporate the modified/additional sources of emissions associated with the proposed Taweelah B IWPP Project to the background emission data established through the initial air dispersion modelling and assess the compliance of the cumulative emissions against the relevant ambient air quality standards.

1.3 The initial air dispersion modelling exercise was carried out on behalf of ADWEAs Projects Privatisation Directorate and it covers the current emissions from the existing sources within Taweelah Power Complex as follows:

Taweelah A1 operated by Gulf Total Power Company. Taweelah A2 operated by Emirates CMS Power Company. Taweelah B operated by Al Taweelah Power Company. Taweelah B Extension operated by Al Taweelah Power Company.

The entire Taweelah Power Complex.

1.4 This report presents the results/findings of the updated air dispersion modelling exercise required to provide input to the air quality impact assessment carried out as part of the Environmental Impact Assessment (EIA) for the Taweelah B IWPP Project.

Study Overview 1.5 The air dispersion modelling exercise covered the following activities:

Undertake an air dispersion modelling for the various operational

scenarios associated with the proposed Taweelah B IWPP project as discussed later in this report.

Incorporate the above (i.e. Taweelah B IWPP) emission sources with the

already established emission data from other power plants within Taweelah Power Complex (i.e. Taweelah A1 and Taweelah 2).

Estimate the cumulative air quality impact (i.e. ground level concentration

- GLC) associated with the future operational profile of the entire power



complex for the main air pollutants (i.e. NO2, CO and SO2) from the entire power complex.

Assess the environmental compliance (in terms of ambient air

quality/ground Level Concentration) with the relevant ambient air quality standards and guidelines for the future operational scenarios.

Study Scope 1.6 The air dispersion modelling exercise considered the following scenarios:

1. Scenario 1 existing plant fired on natural gas. 2. Scenario 2 existing plant fired on crude oil.

3. Scenario 3 new and refurbished plant fired on natural gas.

4. Scenario 4 new and refurbished plant fired on gas oil.

1.7 The principal air pollutants considered within the scope of this study include the following:

NOx/NO2 CO SO2

1.8 The following relevant ambient air quality standards/limits were used for results interpretation and compliance assessment for various air pollutants as applicable:

PWPA Ambient Air Quality Limits. Federal Environmental Agency Ambient Air Quality Standards.

World Bank Standards.



2.0 METHODOLOGY

2.1 The following section presents an overview of the methodology followed while carrying out the air dispersion modelling exercise including:

Modelling scenarios. Pollutants modelled.

Assessment criteria.

Modelling approach.

Modelling Assumptions - Percentage Oxidation of NOx to NO2

Modelling Scenario

2.2 The air dispersion modelling study has considered the potential ambient air quality impacts from the main emission sources associated with the various operating scenarios of the proposed Taweelah B IWPP project in addition to the contribution from other sources (i.e. Taweelah A1 and Taweelah A2) within Taweelah Power Complex.

2.3 The air dispersion modelling considered four scenarios, representing the plant

before and after refurbishment and extension and representing normal (natural gas) and standby (crude oil or gas oil) fuels, on this basis:

Scenario No.

Description

Scenario 1 Existing plant fired on natural gas Scenario 2 Existing plant fired on crude oil Scenario 3 New and refurbished plant fired on natural gas Scenario 4 New and refurbished plant fired on gas oil

2.4 Scenario 3 is further divided into two cases, 3A and 3B, representing

respectively operating cases C1 and OP1. C1 represents the capability of the plant, while OP1 represents a normal operating condition.

2.5 It was not immediately clear which is the worst case for air quality impact;

case C1 reflects maximum fuel combustion (hence emissions) but case OP1 results in a significantly lower exhaust temperature (hence less effective dispersion), accordingly it was considered that both should be modelled. (Scenario 4 represents case C1 on oil firing; there is no recognised OP1 case for oil firing as it is a standby fuel).

2.6 The modelling represents the whole B complex, which is plant subject to the

new Construction Environmental Permit. The study has also considered the contribution of the B plant in each scenario to air quality at ground level, combined with background air quality levels established by the initial mentioned ADWEAs air dispersion modelling.



Pollutants Modelled 2.7 The main pollutants considered for the above study are:

NOx/NO2 CO.

SO2

2.8 The SO2 emissions have been modelled for the liquid firing (i.e. crude oil and

gas oil) scenarios associated with the proposed Taweelah B IWPP project only.

2.9 The main reason behind the above approach was the fact that the SO2

emission rates are mainly dependent on the sulphur content in the gas fuel (for the gas firing scenarios) supplied by Abu Dhabi National Oil Company (ADNOC/GASCO) and the power companies have no control over its content. Consequently, there was no reliable data available at this stage regarding the SO2 emission rates from any of the power plants in order to be considered in this modelling exercise.

Assessment Criteria

2.10 The study has used the ambient air quality standards established by ADWEA

(i.e. PWPA Standards) and the other relevant UAE Federal Environmental Law for various air quality pollutants.

2.11 The above limits were used to assess the compliance of the future ambient

air quality (i.e. Ground Level Concentration - GLC) associated with various operational scenarios as described earlier based on the modelling exercise output.

2.12 The following tables provides an overview of the ambient air quality

standards/limits for various criteria air pollutants used for the air dispersion modelling study including:

ADWEA - PWPA Standards. Federal Environmental Agency (FEA) - Ambient Air Quality Standards.

World Bank Standards.



Table 2.1 ADWEA - PWPA Standards

SUBSTANCE SYMBOL MAX. ALLOWABLE LIMITS (ug/m3)

AVERAGE TIME

Nitrogen Dioxide

NO2 200 1 hour

Sulphur Dioxide

SO2 200 1 hour

Note: There are two different requirements as specified in each PWPA (Appendix N) as

follows: 1) Limits for pollutants concentration in the flue gas. This applies only when

operating the units in the range of 60% to 100% power. Compliance with this requirement is checked for each power unit during its commissioning and further monitored in service. Each stack exhaust is therefore equipped with instruments to analyse on-line the flue gas composition.

2) Concentration limits of pollutants at the ground level. Compliance implies

designing the stack with a sufficient height. These limits (i.e. ambient air quality limits) were used as the applicable PWPA limits for compliance assessment in this air dispersion modelling report.

Table 2.2 FEA - Ambient Air Quality Standards

SUBSTANCE SYMBOL MAX. ALLOWABLE

LIMITS (ug/m3) AVERAGE TIME

Carbon Monoxide CO 30 (mg/m3)

10 (mg/m3)

1 hour

8 hours Nitrogen Dioxide NO2 400

150

1 hour

24 hours Sulphur Dioxide

SO2 350

150

60

1 hour

24 hour

Annual

Table 2.3 World Bank Standards

SUBSTANCE SYMBOL MAX. ALLOWABLE LIMITS (ug/m3)

AVERAGE TIME

Nitrogen Dioxide

NO2 150

100

24 hour

Annual Sulphur Dioxide

SO2 150

100

24 hour

Annual

Modelling Approach

2.13 The emissions from the identified sources were modelled using atmospheric dispersion model US EPA AERMOD. Information required for input into a dispersion models includes process conditions, meteorological data, topography of the area and buildings in the vicinity.



2.14 The maximum predicted ground level concentrations attributable to emissions

from various Taweelah B IWPP operational scenarios were assessed and compared to the ambient air quality standards and guidelines as discussed above.

Air Dispersion Model

2.15 US EPA AERMOD software package was used for the air dispersion modelling exercise. AERMOD is a 'new generation' computer based model widely accepted as industry standard in the USA.

2.16 The model was specially designed to support the EPA's regulatory modelling

program and it contains basically the same options as ISCST3 model with few enhancements in data processing/presentation.

Meteorological Data

2.17 The meteorological data (wind speed, wind direction, temperature, etc) used for the study were taken from the Abu Dhabi International Airport for the following years:

1999. 2000. 2001.

2002. 2003.

2.18 The met data from Abu Dhabi Airport meteorological station which is the

closest station to the Taweelah site, which has all the information/data, required for the air dispersion modelling input file was used for the modelling exercise and the data were purchased from Trinity Consultants, USA. It is worth mentioning that the distance between the met station and the Taweelah Power Complex is less than 40km.

2.19 The following land use characteristics were used to the model as follows:

Water 70 - 210 Desert 210 - 70

Base Map

2.20 In order to establish a base map for the modelling exercise, a geo-referenced

satellite imagery was used to establish the base map used for the modelling and identifying the receptors grid.

2.21 The emission sources, buildings, etc were physically placed on the BIIP view

package of the software and the UTM coordinates were generated automatically.



2.22 The following table summarize the main site domain characteristics used for the base map:

Table 2.3 Base Map Site Domain Characteristics

Coordinates/Specifications Details

NE Corner (x,y) -295151.53,2747295.5 SW Corner (x,y) 260629.4,2724943.03

Height 22352.47 Width 34522.13

Building and Topography

2.23 As advised by Marubeni, there are few buildings of significant size and

proximity to the sources of emissions that were requested to be included in the modelling exercise.

2.24 The following table summarize the data on the building inputted into the

model is order to assess the building downwash effect.

Table 2.4 Buildings Considered for Downwash

Plant Building Approx. height, m

Approx. width, m

Approx. length, m

Approx. distance from stack, m

Initial B Boiler 47.8 15E-W 30 N-S 25 Initial B Extension

HRSG 20 8 E-W 17 N-S 0

HRSG

22 12 N-S 26 E-S 0 New B Extension

Gas turbine hall

20 14 E-W 115 N-S 50 (unit 95) 60 (units 96 & 97)

2.25 In addition to the above and based on the typical flat terrain within Taweelah

area, flat topography was used as an input for modelling purposes.

Receptors and Contours

2.26 The model provides predictions of pollutant concentrations at user-defined locations (receptors). In this study, the modelling was carried out for a grid of 441 receptors.

2.27 A Uniform Cartesian Grid was used for the modelling with origin (SW Corner)

(0x,0y) of 260722.92 m and 2725173.2 m respectively. The uniform spacing (Dx,Dy) used for the modelling was 1721.43 and 1087.59 m respectively and the length of the grid was 34428.6 and 21751.8 m respectively.

2.28 The modelled concentrations were processed using a contour-plotting

package to produce contour plots of ground level pollutant concentrations, for different averaging periods.



Modelling Assumptions - Percentage Oxidation of NOx to NO2

2.29 The oxides of nitrogen (NOx) emitted to atmosphere within combustion gases largely of nitric oxide (NO), a relatively innocuous substances. However, once released into the atmosphere the NO is oxidised to nitrogen dioxide (NO2), which is of concern with respect to health and other impacts.

2.30 The proportion of NO oxidised to NO2 depends on a number of factors and

the oxidation is limited by the availability of oxidants, such as ozone (O3).

2.31 Extensive measurements have been made of the percentage oxidation of NO to NO2 in power station plumes, and empirical relationships have been derived based on downwind distance, ozone concentration, wind speed and season of the year [A Classification of NO Oxidation Rates in Power Plant Plumes Based on Atmospheric Condition. Atmospheric Environment, 22 (No.1) 43-53. Janssen, LHJM et al (1988)].

2.32 Details regarding the approach used to consider the above NOx to NO2 conversion is included in Appendix I of this report for future reference.



3.0 INPUT DATA 3.1 Input information required for the air dispersion modelling was established as

follows:

Emission details related to the existing Taweelah A1, Taweelah A2 and Taweelah B operations were established through a series of technical clarifications/meeting between ADWEA and Dome and coordination with the Taweelah operators during the course of the original air dispersion modelling exercise.

Emission details related to the future Taweelah B operational scenarios

(i.e. Scenarios 1 to 4) were provided by Marubeni/PB during the modelling update exercise.

3.2 The basic information inputted to the air dispersion model include the

following:

Source description. Stack diameter. Stack height above the ground. Exit velocity. Exist temperature. Emission rates/limits for various pollutants. Flue gas flow rate. Building details.

3.3 The following section provides an overview of the main input data used for the

model development (i.e. emission data) for the modelled scenario considered in the subject study.

ADWEA Input Data

3.4 As agreed with ADWEA during the initial air dispersion modelling exercise,

the modelling approach was based on the worst-case operational scenario in accordance with the PWPA Admissible Limits.

3.5 The above worst-case scenario represents the maximum emissions (as per

the limits established by the PWPA) data from the existing power companies within the Taweelah Power Complex (i.e. Taweelah A1, A2, B and B - Ext) at contracted capacity conditions (i.e. 100% power and water capacity) while operating on combined cycle mode and burning natural gas.

3.6 The above data were received from ADWEA for the various power plants

operating within Taweelah Power Complex and the emission calculation sheet including the model input data is included in Appendix II of this report.



Marubeni/PB Input Data

3.7 The air dispersion modelling input data provided by Marubeni/PB for the

modelling update exercise are provided in Appendix III of this air dispersion modelling report.



4.0 RESULTS

4.1 The spatial distribution of the predicted concentrations of NO2,C O and SO2

emitted from the various scenarios modelled were presented as contour plots along the receptors grid system established.

4.2 The plots present the results for the hourly, 8-hourly, daily and annual mean

concentrations (as specified in the above specified air quality limits/standards) during normal operating conditions.

4.3 The peak predicted ground level concentration resulting from the various

modelled scenarios has been assessed for their compliance against the relevant ambient air quality standards. The peak represents the highest concentration predicted at any location.

4.4 The results of air dispersion modelling exercise are presented in the following

tables including comparison with the relevant air quality standards.



Dome Oilfield Equipment & Services December, 2004 ED42.04


Appendix I

NOx/NO2 Conversion


A.3.3 Conversion of nitric oxide (NO) to nitrogen dioxide (NO2)

NOx emissions from the proposed gas turbines will consist of the gases NO and NO2. It is only nitrogen dioxide that is of concern in terms of direct health and environmental effects. However NO is a source of NO2 in the atmosphere. The gases are in equilibrium in the air, with NO predominating at the stack exit. Typically, NOx produced by combustion consists of 5 per cent NO2 and 95 per cent NO at source.

In rural areas, where the atmosphere is relatively unpolluted, the oxidation process occurs rapidly and NO2 is the predominant species. However, in more polluted areas where the oxidizing capacity of the atmosphere may be limited, NO predominates. Urban areas are typical of this limited oxidation pattern.

For assessing the impacts on air quality of emissions to atmosphere from combustion sources, it is important that realistic estimates are made of how much NO has been oxidized to NO2 at all receptors considered.

The rate of oxidation of NO to NO2 depends on both the chemical reaction rates and the dispersion of the plume in the atmosphere. The oxidation rate is dependent on a number of factors that include the prevailing concentration of ozone, the wind speed and the atmospheric stability.

One method of estimating the proportion of the oxides of nitrogen that will be in the form of nitrogen dioxide at ground level, in the study area, is the empirical estimates made by Janssen et al (1988). Technical Guidance issued by the DETR (TG3(00)) in the UK regarding the selection and use of dispersion models for air quality review and assessment purposes notes the need in detailed assessments for a more realistic estimate of NO2, and recommends the use of the Janssen paper to derive such conversion rates for industrial sources.

Between 1975 and 1985 about 60 sets of measurements were made of the concentrations of nitric oxide and nitrogen dioxide in various power station plumes. From the data collected Janssen et al suggests an empirical relationship for the percentage oxidation in the plume based on downwind distance, season of the year, wind speed and ambient ozone concentration. This can be described by the following equation:

( )xx

eANONO =

1][][ 2

where x is the distance downwind (km) of the emission point, A is a coefficient dependent on ozone concentration and the intensity of sunlight and is related to wind speed and ozone concentration.

The A coefficient can be determined from the expression: -

1

31

2 1][

+=

OkkA

Where k1 is the second order rate constant for the reaction of NO with O3 and k2 is the rate constant for the photo-dissociation of NO2. Janssen et al uses a value for k1 of 29 ppm-1 min-1 determined by Becker and Schurath in 1975. The value for k2 is dependent on the intensity of sunlight at a particular location and Janssen et al quotes values determined by Parrish et al in 1983 of between 0 in the dark and 0.55 min-1 in full sunlight. We have preferred a more recent determination of 0.48 min-1 determined by Mao et al in 2003 under clear sky conditions in the region of 30S to 30N as being typical of the values expected at the proposed site in UAE.

The UK Meteorological Office STOCHEM global ozone model indicates that a background ozone concentration, [O3], of 0.03 0.04 ppm would be expected in countries of latitude similar to the UAE and it is in good agreement with amateur data collected at Abu Dhabi between 1 March and 1 April 1999, via the Global Ozone Passive Monitoring Project, which returned an average ozone concentrations of 0.038 ppm respectively. For the purposes of this modelling exercise a value of 0.038 ppm has been considered representative of the ozone concentration likely to be observed at Taweelah.

It implies for the proposed plant: -

1

1038.0*29

48.0

+=A = 0.696

The value of has been determined experimentally by Janssen et al and has been applied by PB Power to a number of sites across the UK where both wind speed and ozone data were available from locations in close proximity. These are at Southampton, Sheffield, Heathrow, Hillingdon, Teddington and Bournemouth. Because is not believed to be a function of the intensity of solar radiation, it is assumed here that it is independent of latitude and can, therefore, be applied equally to plumes anywhere in the world. Notwithstanding expectations, some seasonal variation of was observed (higher values in summer, lower values in winter) and therefore the worst-case value was considered here. These values of have in turn been used to give the maximum calculated conversion rates to return more realistic concentrations of nitrogen dioxide.

TABLE A.5 WORST CASE VALUES OF USED FOR THE DETERMINATION OF NOX

CONVERSION FACTORS

Wind speed at plume height

Background ozone concentration (ppb) 0 5 m/s 5 15 m/s > 15 m/s

120 200 0.40 0.65 0.8

60 120 0.2 0.35 0.45

40 60 0.15 0.25 0.35

30 40 0.1 0.15 0.25

20 30 0.1 0.1 0.15

10 20 0.1 0.1 0.1

0 10 0.05 0.05 0.05

The available meteorological data for Abu Dhabi indicates that at least 99 per cent of the time the ground level wind speed does not exceed 8 m/s. This value is unlikely to exceed 15 m/s at plume height; therefore, for an ozone concentration of 38ppb (30 40 ppb), Table A.5 yields a value for of 0.15.

The overall empirical formula suggested by Janssen et al to describe NOx conversion with distance at the proposed plant becomes:

( )xx

eNONO 15.02 1*696.0

][][ =

This equation has therefore been used to calculate a specific maximum conversion rate for each receptor considered in the dispersion modelling in order to give more realistic ground level concentrations of nitrogen dioxide. Conversion rate for a sample of distances from the site are shown in Table A.6.

TABLE A.6 TYPICAL VALUES OF NO2 IN NOX AS A PERCENTAGE WITH DISTANCE

Downwind distance (km) Conversion Factor (%)

0.5 5

1 10

2 18

3 25

5 37

10 54


Appendix II

Air Emission Input - ADWEA


SOURCE GAS FLOW GAS DENSITY GAS FLOW EL-Nox EL-CO % H2O % O2 ER-Nox ER-CO Stack TEMP DIA VELOCITYID KG/SEC KG/NM3 NM3/SEC MG/NM3 MG/NM3 G/SEC G/SEC Height (M) DEG C M M/SEC

TAW-A1 1 350.4 1.224 286.3 60 50 13.13 12 22.51 12.43 55 185 5.3 21.782 350.4 1.224 286.3 60 50 13.13 12 22.51 12.43 55 185 5.3 21.783 350.4 1.224 286.3 60 50 13.13 12 22.51 12.43 55 185 5.3 21.784 373.4 1.224 305.1 60 50 13.13 12 23.99 13.25 55 173 5.3 22.605 373.4 1.224 305.1 60 50 13.13 12 23.99 13.25 55 173 5.3 22.606 373.4 1.224 305.1 60 50 13.13 12 23.99 13.25 55 173 5.3 22.607 373.4 1.224 305.1 60 50 13.13 12 23.99 13.25 55 173 5.3 22.608 373.4 1.224 305.1 60 50 13.13 12 23.99 13.25 173 5.3 22.60

TAW-A2 1 556 1.224 454.2 50 30 13.13 12 29.76 11.84 55 153.8 6.3 22.792 556 1.224 454.2 50 30 13.13 12 29.76 11.84 55 153.8 6.3 22.793 556 1.224 454.2 50 30 13.13 12 29.76 11.84 55 153.8 6.3 22.79

TAW-B EXT 1 1.224 298.0 50 30 13.13 12 19.53 7.77 55 175 5.33 21.932 1.224 298.0 50 30 13.13 12 19.53 7.77 55 175 5.33 21.93

TAW-B 1 1.19 118.0 150 100 20.6 2 14.84 9.37 70 145 3.04 24.902 1.19 118.0 150 100 20.6 2 14.84 9.37 70 145 3.04 24.903 1.19 118.0 150 100 20.6 2 14.84 9.37 70 145 3.04 24.904 1.19 118.0 150 100 20.6 2 14.84 9.37 70 145 3.04 24.905 1.19 118.0 150 100 20.6 2 14.84 9.37 70 145 3.04 24.906 1.19 118.0 150 100 20.6 2 14.84 9.37 70 145 3.04 24.90

Emission Calculations

ER-NOx=NM3/SEC*(MG/NM3*1/1000)*(1-%H20/100)*(20.9-%O2)/(20.9-15 OR 3 FOR TAW-B)ER-CO=NM3/SEC*(MG/NM3*1/1000)*(1-%H20/100)VELOCITY=NM3/SEC*((EXH TEMP+273)/273)/(0.785*DIA*DIA)


Appendix III

Air Emission Input - Marubeni/PB


TAWEELAH B COMPLEX INPUT FOR AIR DISPERSION MODELLING

REV 2 16 NOV 2004

In common with the previous air dispersion modelling study, it is proposed that the modelling should consider four scenarios, representing the plant before and after refurbishment and extension and representing normal (natural gas) and standby (crude oil or gas oil) fuels, on this basis:

1. Scenario 1 existing plant fired on natural gas. 2. Scenario 2 existing plant fired on crude oil. 3. Scenario 3 new and refurbished plant fired on natural gas. 4. Scenario 4 new and refurbished plant fired on gas oil.

Scenario 3 is further divided into two cases, 3A and 3B, representing respectively operating cases C1 and OP1. C1 represents the capability of the plant, while OP1 represents a normal operating condition. It is not immediately clear which is the worst case for air quality impact; case C1 reflects maximum fuel combustion (hence emissions) but case OP1 results in a significantly lower exhaust temperature (hence less effective dispersion). It is considered that both should be modelled. (Scenario 4 represents case C1 on oil firing; there is no recognised OP1 case for oil firing as it is a standby fuel.) The modelling should represent the whole B complex as this is the plant which is subject to the new Construction Environmental Permit. The study should consider the contribution of the B plant in each scenario to air quality at ground level, combined with background air quality levels obtained from the ADWEA Research Centre monitoring station at Taweelah. The background will include the contribution from A1 and A2 plants, so there is no requirement for emissions from these sources to be added. This approach is conservative as the contribution from existing B plant will be included twice: in the background and in the emissions from Initial B and Initial B Extension plants.

Appendix III

DISPERSION MODELLING INPUT DATA FOR EACH EXISTING BOILER

Scena

rio 1 Scenario 2

Scenario 3A

Scenario 3B

Scenario 4

NOx emission level

mg/Nm3 150 (4) 250 100 (1) 100 (1) 150

NOx flow rate g/s 14.84 (4)

24.7 (5)

9.89 (8)

9.89 (8)

14.84 (9)

SO2 emission level

mg/Nm3 -(4,13) 1265.1 (6)

-(4,13) - (4,13) 529.4 (10)

SO2 flow rate g/s -(4,13) 149.28(2)

- (4,13) - (4,13) 62.47 (3)

CO emission level mg/Nm3 100 (4) 100 (7) 100 (4) 100 (4) 100 (7)

CO flow rate g/s 9.37 (4) 9.37 (7) 9.37 (4) 9.37 (4) 9.37 (7)

Flue gas temperature

K 418.1 (4)

418.1 (7)

418.1 (4)

418.1 (4)

418.1 (7)

Stack diameter m 3.04 (4) 3.04 (4) 3.04 (4) 3.04 (4) 3.04 (4)

Flue gas velocity m/s 24.9 (4) 24.9 (7) 24.9 (4) 24.9 (4) 24.9 (7)

Normalised flue gas flow rate

Nm/s 118.0 (4)

118.0 (7)

118.0 (4)

118.0 (4)

118.0 (7)

Actual flue gas flow rate

m/s 180.7 (4)

180.7 (7)

180.7 (4)

180.7 (4)

180.7 (7)

Stack height m 70 70 70 70 70

Notes:

1. Projected NOx level as per EPC contract. 2. At typical crude oil sulphur content of 0.75% by weight. 3. At typical gas oil sulphur content of 0.3% by weight. 4. As agreed with ADWEA 5. Prorata from gas firing: 14.84 g/s x 250/150. 6. Consistent with emission rate and flow rate: 149.28 g/s x 1000 mg/g / 118 Nm/s. 7. Estimated to be same as on gas firing. 8. Prorata from Scenario 1: 14.84 g/s x 100/150 9. Estimated to be as in Scenario 1 (also at 150 mg/Nm).. 10. Consistent with emission rate and flow rate: 62.47 g/s x 1000 mg/g / 118 Nm/s. 13. Based on 250 ppmv sulphur in natural gas as H2S.

Appendix III

DISPERSION MODELLING INPUT DATA FOR EACH EXISTING GT/HRSG

Scenario 1

Scenario 2

Scenario 3A

Scenario 3B

Scenario 4

NOx emission level

mg/Nm3 50 (4) 120 50 (4) 50 (4) 120

NOx flow rate g/s 19.53 (4)

46.87 (11)

19.53 (4)

19.53 (4)

46.87 (11)

SO2 emission level

mg/Nm3 - (4,13) 145.7 (12)

- (4,13) - (4,13) 145.7 (12)

SO2 flow rate g/s - (4,13) 43.41(3)

- (4,13) - (4,13) 43.41 (3)

CO emission level mg/Nm3 30 (4) 30 (7) 30 (4) 30 (4) 30 (7)

CO flow rate g/s 7.77 (4) 7.77 (7) 7.77 (4) 7.77 (4) 7.77 (7)


K 448.1 (4)

448.1 (7)

448.1 (4)

448.1 (4)

448.1 (7)

Stack diameter m 5.33 (4) 5.33 (4) 5.33 (4) 5.33 (4) 5.33 (4)

Flue gas velocity m/s 21.93 (4)

21.93 (7)

21.93 (4)

21.93 (4)

21.93 (7)


Nm/s 298.0 (4)

298.0 (7)

298.0 (4)

298.0 (4)

298.0 (7)


m/s 489.0 (4)

489.0 (7)

489.0 (4)

489.0 (4)

489.0 (7)

Stack height m 55 (4) 55 (4) 55 (4) 55 (4) 55 (4)

Notes:

3. At typical gas oil sulphur content of 0.3% by weight. 4. As agreed with ADWEA. 7. Estimated to be same as on gas firing. 11. Prorata from gas firing: 19.53 g/s x 120/50. 12. Consistent with emission rate and flow rate: 43.41 g/s x 1000 mg/g / 298 Nm/s. 13. Based on 250 ppmv sulphur in natural gas as H2S.

Appendix III

DISPERSION MODELLING INPUT DATA FOR EACH PROPOSED GT/HRSG

Scenario 1

Scenario 2

Scenario 3A

Scenario 3B

Scenario 4

NOx emission level

mg/Nm3 - 60 60 120

NOx flow rate g/s - 38.8 36.1 62.2

SO2 emission level

mg/Nm3 - 29.5(13)

27.0(13)

171.4 (3)

SO2 flow rate g/s - 14.8(13)

13.8(13)

83.9 (3)

CO emission level mg/Nm3 - 20 20 13

CO flow rate g/s - 12.9 12.0 6.7


K - 416.7 383.8 435.3

Equivalent stack diameter

m - 7.0 6.7 7.0

Flue gas velocity m/s - 20 20 20


Nm/s - 499.7 508.9 489.6


m3/s - 762.5 715.1 780.3

Stack height m - 55 55 55

Notes: 3. At typical gas oil sulphur content of 0.3% by weight. 13. Based on 250 ppmv sulphur in natural gas as H2S.

Appendix III

SOURCES OF EMISSIONS

Plant Unit Approximate bearings, m, in drawing PE 4027 BC 001 rev 0

E S Initial B 11 3325 2940 21 3380 2940 31 3525 2940 41 3585 2940 51 3635 2940 61 3690 2940 Initial B Extension - 3805 2855 - 3865 2855 New B Extension 95 3980 2900 96 3970 2860 97 3970 2815

Appendix III

Study OverviewStudy ScopeAssessment Criteria

Modelling ApproachInitial B15E-W

COVER PAGE.pdfDome Oilfield Equipment & ServicesDome International LLC

Appendix I.pdfATMOSPHERIC DISPERSION MODELLINGIntroductionEnvironmental impactThe dispersion model and inputsGeneralInputs to the modelConversion of nitric oxide (NO) to nitrogen dioxide (NO2)

Modelling results

Appendix II.pdfSheet1

Appendix III.pdfTAWEELAH B COMPLEX INPUT FOR AIR DISPERSION MODELLINGInitial B

2G

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