Review of a Case Study on Application of LCA Methodology for Environment Impact Assessment of Natural Gas Plants

GHOLAMREZA BAHMANNIA

National Iranian Gas Company (NIGC)

South Pars Gas Complex (SPGC)

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An Introduction:

This paper takes on a challenging task in attempting to develop a generic framework with a simple, yet comprehensive set of environmental measures for identification of more sustainable practices for the oil & gas industry.

Identify relatively simple ways of measuring the level of environmental sustainability in the first instance and thereby contribute to further understanding of the meaning of sustainable development for these industries.

Quantification of measures for assessment, future improvements and benchmarking.

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Environment Measures of Sustainability Development

Environmental impacts,

Environmental

efficiency,

Voluntary actions.

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Why LCA?

Both Environmental Impacts and Environmental Efficiency indicators proposed here are calculated routinely through LCA and, by analogy with LCA, are expressed per functional unit.

The third set of environmental indicators is related to a pro-active response of companies to environmental problems. These indicators are designed to reward business for their contributions to the environment and therefore to the society.

the impacts as defined in LCA at present represent only potential rather than actual effects on the environment

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LCA Based on ISO 14040-14043

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Case Study:

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The primary goal of LCA in Phases 6, 7,8 Gas Treating plant in South Pars Gas Complex (SPGC) as a case study is to quantify and analyze the total environmental aspects of producing sour and dry pipeline gas (plus side-products LPG and condensate) via traditional treatment(Dehydration) processes as a typical gas plant in Iran.

The size of the plant is 110 million normal cubic meters per day which is typical of large scale size that would be found at today's world gas plants

An Overall View:

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This plant is located on south of Iran in Assaluyeh Port close to Persian Gulf. Phases 6, 7 and 8 refinery is projected to produce 158,000 barrels of gas condensates, 4700 tons of liquid propane and butane, and 104 million cubic meters of sour /dry gas daily. The phases" gas via a 56-inch and 512-km pipeline will be injected into Aghajari oil region’s wells for inhancement.

Plant Flow Diagram

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Unit 100 Rec.

Facilities

Unit 104Dehydratio

n

Unit 101HP

Separation

Unit 105 Extraction

Unit 105 Fractionatio

n

Unit 114Rec.

Facilities

Unit 101HP

Separation

Unit 104Dehydratio

n

Unit 107Refrigeratio

n

Unit 105Extraction

Unit 107Refrigeratio

n

Unit 103Cond. Stabil.

Unit 102MEG

Recovery

Unit 109Sour Water

Str,

Unit 140FLARE

SYS.

Unit 106 Export Comp.

OFF SHORE PLATFORM

Unit 143COND. STOR.

UTILITIES(C5 AREA)

Unit 122FUEL GAS

Unit 129WWT

Unit 145C3/C4 STOR.

EXPORT GAS (SOUR GAS)

PROPANEBUTANE

CONDENSATE

EARLY PRODUCTION

ONSHORE PLANT –PHASE 6

(Train 1)

(Train 2)

Unit 551Booster

Comp.

System Boundaries

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Raw Material Extraction

RM

Em

E

Off shore Gas Extraction & Production &Gathering lines

Natural Gas TreatingPlant

Constructionof Equipment

Em

Em

E

E

EEm

RM

RM

M

Electricity Production

ERMEm

& Land fillingRecycling

BoosterCompressors &Aghajari Gas Injection.Facilities

E Em

Em

RM

RM

E = energy

Em = emissions

M = materials

RM = raw materials

Major Assumptions:

The software package used to track the material and energy flows between the process blocks in the system was HYSYS, TEAM, Eco-it, SimaPro and plant DCS software.

The heaters and furnaces efficiency in plant is assumed 75% and for this study, the plant life was set at 20 years with 2 years of construction. In year one, the gas plant begins to operate; plant construction takes place in the two years to this (years negative two and negative one). During the last quarter of year 20 the gas plant is decommissioned.

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Environment Impact Result

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The environmental impacts indicators include the usual categories considered in LCA. The impacts are divided into two categories: those from planned emissions and those from unintentional or accidental releases

Solid WastesGHG & GWP

Resource Consumption

Water Emissions

Air Emissions

Impact Assessment

Air Emissions

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In terms of total air emissions, CO2 is emitted in the greatest quantity, accounting for 99 wt% of the total air emissions. The vast majority of the CO2 (84%) is released at the natural gas plant.

In natural gas plant the major emissions are belonged to flares, heaters, furnaces, gas turbines (for driving the compressors and electricity generation), reboilers and burn pits.

84.0%

7.3%1.4% 7.3%

Co2 Nox Co Others

GHG & Global Warming Potential

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The GWP of the system is a combination of CO2, CH4 and N2O emissions. The capacity of CH4 and N2O to contribute to the warming of the atmosphere is 21 and 310 times higher then CO2 , respectively , for a 100 year time frame according to the Intergovernmental Panel on Climate Change ( IPCC ) Thus, the GWP of a system can be normalized to CO2

10.6% 0.1%

89.3%

CO2 CH4 N2O

10.621 1111.888

1.256

0

1

2

3

4

5

6

7

8

9

10

11

12

13

CO2 CH4 N2O GWP

Resource consumption

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accounting for 94.5% of the total resources on a weight basis, followed by, iron (ore plus scrap) at 4.6%, limestone at 0.4%, and oil at 0.4%.

breakdown of the water consumption for system and the majority of the water is consumed at the gas plant.

94.5

4.60 0.4 0.4

Natural Gas Iron Lime Oil

95.1%

3.6%1.3%

Cons. & Decom. Operation Prod. & Transport

Water Emissions

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The total amount of water pollutants for this study equals 0.19 g/kg of gas with the primary pollutant being oils (60%) followed by dissolved matter (29%). It is interesting to note that the water pollutants come primarily from the material manufacturing steps required for pipeline and plant construction.

Solid Waste

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The waste produced from the system is miscellaneous non-hazardous waste; totaling 201.6 g/kg of gas produced Following data contains a breakdown of the percentage of waste from each of the subsystems:

Total Solid Waste: 201.6 Lt/Kg gas

4%17%

72%

7%

Cons. & Decom. Operation

Prod. & Transport Elec. Generation

Impact Assessment Summary

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Energy Requirements

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The energy in the natural gas is greater than the energy content of the gas produced. Therefore; the life cycle efficiency is negative.

Voluntary Actions

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Environmental Management Systems (EMS) Environmental improvements above the compliance

levels (ICL) Assessment of suppliers (AS)

Improvement Opportunities

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Reducing the natural gas losses and flaring Reducing the methane release Reducing Sour Gas Flaring in commissioning time Reduction of excess fuel gas On-Line Gas emission monitoring Minimizing Fuel gas consumption Improvement of Gas Turbines efficiencies ( combined cycle) Air release detection and prevention Performing An Effective Waste management system Maintaining of Energy management system On Conditioning maintenance for reducing the maintenance

programs

Conclusion

A life cycle approach has been taken in this work and, like in Life Cycle Assessment; it is proposed that the indicators be standardized according to the function the system delivers. Monitoring of LCA indicators can show effective trend toward sustainability development in industries. The advantage of this approach, compared to some other approaches, is that it explicitly avoids trying to express environmental performance in monetary terms.

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Thank You For Your Attention

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