Ukccs Kt s3.2 Sp 001 Mah Report Final

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UK Carbon Capture and StorageDemonstration Competition

UKCCS - KT - S3.2 - SP - 001

MAH Summary Report

April 2011

ScottishPower CCS Consortium



May 2011

UK Carbon Capture and StorageDemonstration Competition

UKCCS - KT - S3.2 - SP - 001

MAH Summary Report

April 2011

ScottishPower CCS Consortium

Mott MacDonald, 1 Atlantic Quay, Broomielaw, Glasgow G2 8JB, United Kingdom

T +44(0) 141 222 4500 F +44(0) 141 221 2048, W www.mottmac.com

ScottishPower Generation LimitedLongannet Power StationKincardine on ForthClackmannanshireScotland

IMPORTANT NOTICE

Information provided further to UK Government’s Carbon Capture and Storage (“CCS”) competition to develop afull-scale CCS facility (the “Competition”)

The information set out herein (the Information ) has been prepared by ScottishPower Generation Limited and its sub-contractors (the Consortium ) solely for the Department for Energy and Climate Change in connection with the Competition.The Information does not amount to advice on CCS technology or any CCS engineering, commercial, financial, regulatory,legal or other solutions on which any reliance should be placed. Accordingly, no member of the Consortium makes (and theUK Government does not make) any representation, warranty or undertaking, express or implied as to the accuracy,adequacy or completeness of any of the Information and no reliance may be placed on the Information. In so far as permittedby law, no member of the Consortium or any company in the same group as any member of the Consortium or theirrespective officers, employees or agents accepts (and the UK Government does not accept) any responsibility or liability of

any kind, whether for negligence or any other reason, for any damage or loss arising from any use of or any reliance placedon the Information or any subsequent communication of the Information. Each person to whom the Information is madeavailable must make their own independent assessment of the Information after making such investigation and takingprofessional technical, engineering, commercial, regulatory, financial, legal or other advice, as they deem necessary.



Access to and use of the information in this document is subject to the terms of the disclaimer at the front of the document

UKCCS - KT - S3.2 - SP - 001 MAH Summary Report

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UKCCS Demonstration CompetitionMAH Summary Report

Chapter Ti t le Page

1. Introduction 7

2. Project Overview 8

3. Requirements of the Major Accident Hazard Report 9

3.1 Scope of the Longannet Major Accident Review ____________________________________________ 9

3.2 Safety and Hazard Assessment Studies Undertaken ________________________________________ 9

4. Outline of the Carbon Capture Plant Environs 11

4.1 Site Location ______________________________________________________________________ 11

4.2 People and Population _______________________________________________________________ 11

4.2.1 On Site Population __________________________________________________________________ 11

4.2.2 Local Communities__________________________________________________________________ 11

4.2.3 Other COMAH Sites _________________________________________________________________ 11

4.2.4 Local Weather Conditions ____________________________________________________________ 11

4.2.5 Local Environment __________________________________________________________________ 11

5. Outline of the Carbon Capture Process 13

5.1 Overview _________________________________________________________________________ 13

5.2 Flue Gas __________________________________________________________________________ 13

5.3 CO2 Absorption ____________________________________________________________________ 13

5.4 CO2 Strippers ______________________________________________________________________ 14

5.5 CO2 Compression __________________________________________________________________ 14

5.6 CO2 Drying and Oxygen Removal ______________________________________________________ 14

5.7 AGI and CO2 Export _________________________________________________________________ 15

5.8 Control of CO2 Specification __________________________________________________________ 15

5.9 Auxiliary Plant _____________________________________________________________________ 16

5.9.1 Power and Steam Supply ____________________________________________________________ 16

5.9.2 Cooling Water _____________________________________________________________________ 16

5.9.3 Effluents and Waste _________________________________________________________________ 16

5.9.4 Ancillary Services ___________________________________________________________________ 16

5.10 Control Philosophy __________________________________________________________________ 17

5.10.1 Carbon Capture Plant Control Philosophy ________________________________________________ 17

5.10.2 End-to-End Carbon Capture and Storage Chain Control Philosophy ___________________________ 18

5.10.2.1 Overview _________________________________________________________________________ 18

5.10.2.2 Control Systems ____________________________________________________________________ 18

5.11 Carbon Capture Site Boundaries _______________________________________________________ 21

6. Safety Management Systems 22

6.1 Overall Project Safety Management SMS ________________________________________________ 22

6.2 Longannet Power Station Health and Safety Policy ________________________________________ 22

6.3 Carbon Capture Plant SMS ___________________________________________________________ 236.4 Longannet Power Station Business Continuity Plan ________________________________________ 23

Content





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7. Identification of Potential Major Accident Hazards 24

7.1 Hazardous Substances on Site ________________________________________________________ 24

7.1.1 Carbon Dioxide ____________________________________________________________________ 24

7.1.2 Amines ___________________________________________________________________________ 24

7.1.3 Other Substances __________________________________________________________________ 25

7.2 Major Accident Hazard Identification ____________________________________________________ 26

7.3 MAHs to be Considered ______________________________________________________________ 27

7.3.1 MAHs – CO2 Dispersion ______________________________________________________________ 27

7.3.2 MAHs – Natural Gas Release _________________________________________________________ 27

7.3.3 Amine Release _____________________________________________________________________ 27

7.3.4 Other Hazards _____________________________________________________________________ 27

8. Consequence Modelling 28

8.1 Modelling Methods __________________________________________________________________ 28

8.1.1 Modelling Software __________________________________________________________________ 28

8.1.2 Weather Conditions for Modelling ______________________________________________________ 28

8.2 Modelling Cases Considered __________________________________________________________ 28

8.2.1 Carbon Dioxide Releases ____________________________________________________________ 28

8.2.2 Natural Gas Releases _______________________________________________________________ 29

8.3 Other releases and Future Work _______________________________________________________ 29

9. Discussion of Results 309.1 Carbon Dioxide Releases ____________________________________________________________ 30

9.2 Natural Gas Releases _______________________________________________________________ 30

9.3 Amine Releases ____________________________________________________________________ 31

9.4 Safeguards and Mitigation ____________________________________________________________ 32

10. Conclusions and Recommendations 34

10.1 Conclusions _______________________________________________________________________ 34

10.2 Recommendations __________________________________________________________________ 34

Glossary 35





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The UK Government (via the Department of Energy and Climate Change (DECC)), launched a competition

to develop the UK’s first full scale Carbon Capture and Storage (CCS) demonstration project. The

Consortium, consisting of ScottishPower, National Grid and Shell has been invited to submit a Front End

Engineering Design (FEED) study to demonstrate that their scheme proposals can realise the desired CCS

demonstration project and will help the UK Government’s long term aim of implementing CCS at a

commercial scale. The objective of the FEED study is to develop the project design to obtain greater

certainty over scope, design and costs and demonstrate risk reduction when compared with the earlier

conceptual design. The scope of the FEED covers the process connection to the existing power station,

carbon dioxide (CO2) capturing and conditioning equipment, onshore CO2 transportation, offshore

transportation and permanent storage.

For the purposes of the CCS Demonstration Competitions it has been agreed to assume that major

hazards permissioning legislation applies to the FEED proposals and the bidders are required to submit

appropriate safety, health and environmental (SHE) documentation to the Health and Safety Executive

(HSE) and the Scottish Environment Protection Agency (SEPA) for consideration as part of the DECC

competition. Therefore a Major Accident Hazard (MAH) review was undertaken for the carbon capture

facilities located at Longannet site. The MAH review was based on the data available during the FEED

study and hence is not final.

This MAH report review identified the major hazards on site and gave an indication of the risks and

consequences of the main hazards identified. The MAH review will be continued and a report issued in its

final form during the implementation stage of the project when the detail design is sufficiently advanced and

key parameters are frozen.

This document summarises the MAH review undertaken during the FEED study.

1. Introduction





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The CCS project involves the post combustion removal of CO2 from a portion of the flue gases from one of

the existing Longannet Power Station (LPS) units by retrofitting a Carbon Capture Plant (CCP) which will

be located adjacent to the power station. Captured CO2 from this plant will be dried and compressed,

transported, in a gaseous phase, from Longannet by the use of an onshore pipeline to the Blackhill

Compressor Station located in the vicinity of the St Fergus Terminal, north of Aberdeen. At Blackhill, the

CO2 will be further compressed to dense phase and transported via an existing sub-sea pipeline to the

Goldeneye platform in the North Sea from where the CO2 will be injected into a depleted gas field for

permanent geological storage.

The CCS process is subdivided into individual chain process elements, as depicted in Figure 2-1 below.The elements are defined as follows along with the identification of the associated Consortium partner;

CO2 Source: The CO2 source is the existing Longannet power station. Flue gas will be diverted from

one of the two generating units which will supply flue gas to the CCP. Only one unit will supply flue gas

the CCP at any one time (by ScottishPower)

CO2 Capture: CO2 from the flue gas will be captured using a new CCP at Longannet (by ScottishPower

using Aker Clean Carbon technology). As part of the retrofit CCP, a new Steam and Power Supply

(SPS) is also required to provide steam and electricity to the CCP (by ScottishPower)

CO2 Onshore Transportation: The CO2 will be transported from the CCP via a new interconnecting

pipeline to an existing onshore pipeline and onward to a new compressor station at Blackhill (by

National Grid)

CO2 Offshore Transportation, Injection and Storage: The CO2 will be conveyed via an existing offshore

pipeline from St Fergus to the Goldeneye platform for injection into the depleted Goldeneye offshore

gas field for permanent storage (by Shell)

Figure 2-1: Schematic of the CCS Chain

ScottishPower National Grid Shell

LongannetPower Station

Utilities

Compression

CarbonCapture

Plant Dehydration

BlackhillCompressor Station

Existing and Proposed Pipelines

Existing Pipeline

Storage

Goldeneye

ExistingOffshorePlatform

Source: ScottishPower Consortium

2. Project Overview





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For the purposes of the UKCCS Demonstration Competition it has been agreed to assume that major

hazards permissioning legislation applies to the FEED proposals. As a result, the ScottishPower CCS

Consortium are required to submit appropriate health, safety and environmental documentation to the

Health and Safety Executive (HSE) and the Scottish Environment Protection Agency (SEPA) for

consideration as part of the DECC Competition. HSE/SEPA will provide information to DECC by the end of

March 2011 confirming whether the bidders have made a sufficient case for health, safety and

environmental considerations.

The HSE advised that for the purposes of the FEED assessment exercise it should be assumed that

existing permissioning legislation applies to the onshore pipelines and offshore activities and that CO2 is a

dangerous substance under the Control of Major Accident Hazards Regulations (COMAH) or dangerous

fluid under the Pipeline Safety Regulations (PSR).

CO2 does not have the flammable characteristics of hydrocarbons (which attract the offshore suite of

legislation), but nevertheless it should be considered within the framework of this legislation on the basis of

its toxicity. Consideration should also be given to possible cryogenic impact following loss of containment.

The HSE further advised that where the quantities of CO2 stored fall below likely future COMAH thresholds,

the Consortium should adopt a proportionate approach when considering their As Low As Reasonably

Practicable (ALARP) demonstration for the CCS. Planning and Hazardous Substance Consents do not

currently apply to CO2, but precautionary guidance should be offered for both pipelines and onshore

storage, where the likely future thresholds will be exceeded. These thresholds are as follows:

50 tonnes for PSR

Approximately 100 tonnes for COMAH.

Substances which are currently subject to permissioning legislation (e.g. hydrogen) should be considered

in the normal manner.

The Major Accident Hazards (MAHs) review of the proposed carbon capture plant gave an indication of the

potential risks.

3.1 Scope of the Longannet Major Acc ident Rev iew

The MAH review is only concerned with safety of the carbon capture aspects of the CCS project at

Longannet site. The other aspects of project i.e. the pipeline from Longannet to Blackhill Compressor

Station, the booster compressors at Blackhill, the pipeline to the offshore platform and the offshore platform

and storage reservoir (Goldeneye) have been the subject of separate MAH reviews.

3.2 Safety and Hazard Assessment Stud ies Undertak en

A series of formal safety assessment workshops and studies have been performed for the CCS facilities at

Longannet site. These include:

HAZID (Hazard Identification) studies

HAZOP (Hazard and Operability) studies

SIL (Safety Integrity Level) studies

3. Requirements of the Major AccidentHazard Report





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Major Accident Hazard study

This document presents the results of the Major Accident Hazard study of the CCP, the CO2 conditioning

and compression plant and the pipeline as far as the boundary between the juristictions of the Control of

Major Accident Hazards (COMAH) Regulations 1999 and the Pipeline Regulations (PSR) 1996.

For the CCP and CO2 conditioning and compression plant the HAZID, HAZOP and SIL studies were

performed by Aker Clean Carbon. Their findings are summarized in the following documents:

UKCCS-KT-S3.2-ACC-001 Project HSE Report

UKCCS-KT-S3.2-ACC-002 HAZID and Hazards Analysis Report

For the Onshore Transportation System above ground installation (AGI) the HAZID and HAZOP were

performed by National Grid. Their findings are summarised in the following document:

UKCCS-KT-S3.3-NG-001 National Grid HSE Summary Report

In addition, a safety review was also performed to identify whether there were any End-to-End hazards that

affect more than one of the Consortium Partners and that had not already been identified or resolved in the

individual or interface hazard studies. The review findings are summarised in the following document:

UKCCS-KT-S3.1-E2E-001 End-to-End Safety Review





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4.1 Si te Loca t ion

Longannet Power Station is located 2 miles (3km) to the south east of Kincardine in Fife, on the shores of

the Firth of Forth in Scotland.

4.2 People and Popula t i on

4.2.1 On Si te Populat ion

The normal population on site consists of power station employees, visitors and contractors. Thepopulation is at a maximum during the day shift and is significantly reduced during the night shift. There is

a major increase in on-site population during the summer maintenance periods.

As part of the UKCCS Demonstration Project requirements there will be frequent visitors to the site. These

visitors will generally be at an off-site visitors’ centre with controlled parties visiting the CCP and its control

room under the close supervision of ScottishPower staff.

4.2.2 Loca l Communi t ies

Off-site population, in the immediate vicinity of the power station can be inferred from Ordinance Survey

maps as being low (a few isolated farms).

4.2.3 Other COMAH Sit es

The Grangemouth Oil Refinery is a top tier site under the Control of Major Accident Hazards Regulations

(COMAH) 1999. It is located on the other side of the Forth estuary approximately 3 km from the power

station site.

4.2.4 Local Weather Condi t ions

Weather information obtained from the Gogarbank Meteorological Station outside Edinburgh, has been

used for the study.

4.2.5 Local Environment

The CCP project site is located adjacent to a large tidal estuary, within the characteristic flat, low-lying

coastal land which interfaces with the intertidal and maritime parts of the Forth Estuary. Groundwater is

anticipated to flow from north to south across the CCP project site towards the Forth estuary. The low-lying

areas are dominated by industrial or river related development, LPS and associated lagoons or arable

farmland with large field patterns.

The land use around the CCP site varies considerably. The majority of the existing LPS complex is

occupied by built industrial elements and associated uses. Other areas include the Coal Storage Area

located to the west of LPS and the Longannet Ash Lagoons situated to the east from the existing complex.

The lower parts of the surrounding area are covered with arable fields, whereas the uplands are

characterised by hill pastures. Other land use includes small quarrying operations (often historic) and land

4. Outline of the Carbon Capture PlantEnvirons





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related to defence or port uses. Recreation and tourism are also important land uses as many of theattractions and assets for these are dispersed though the area and include houses, gardens and other

sites.

The Forth Estuary is the dominant water feature. In addition, along the river, there are extensive areas of

intertidal mudflats. Tributaries to the Forth Estuary include Bluther Burn, which flows to the east of High

Valleyfield into Torry Bay. To the south of the Forth Estuary, the River Carron and Grange Burn both

converge close to the refinery at Grangemouth. Further east, the River Avon converges to the east of the

chemical works at Grangemouth. Areas of the Middle Forth have been designated as a RAMSAR Site,

SSSI and Special Protected Area due to their breeding bird assemblages. River Teith SAC is located

approximately 18km upstream and is designated due to the presence of Salmon and Lamprey which will

migrate down the Middle Forth past the CCP.

Devilla Forest is located to the north west of the existing LPS complex. This is an extensive area of

managed coniferous forest. Other tree and woodland cover is limited to linear belts and small blocks, often

located on the slope of the ridgeline.





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5.1 Overview

The CCP will be laid out in two identical trains each rated to treat the flue gas from the equivalent of 165

MWe and will comprise:

Direct Contact Cooler (DCC);

Absorber; and

Stripper

The CO2 from the two trains will be fed to two compression and conditioning trains and into the Onshore

Transportation System.

5.2 Flue Gas

Longannet Power Station comprises of four sub-critical pulverised coal fired units each rated at 600 MWe

gross. The CCP will treat the flue gas from either Unit 2 or Unit 3, depending on which is operating in order

to maximise CCP availability. Flue gases will be directed through Selective Catalytic Reduction (SCR),

Electro-Static Precipitators (ESPs) and Sea Water scrubbing Flue Gas Desulphurisation (SWFGD) plants

before a portion of the gas is abstracted by the CCP. The SCR, ESP and SWFGD do not form part of the

CCP scheme.

5.3 CO 2 Absorpt ion

Flue gases leaving the Unit 2 or Unit 3 SWFGD will be led to the main stack by individual ducts. A

connection from the flue gas ducts with isolating dampers will be made available to enable the flue gas

from either unit to enter the CCP through a single duct.

Degenerative components in the flue gas degrade the amine solution and will influence the amine

reclamation frequency, the amount of make-up amine required and consequently the operating costs

associated with the CCP. A high flue gas inlet temperature can also reduce the CO2 capture plant

performance. Therefore the flue gas will pass through a packed bed DCC with added sodium hydroxide

(NaOH) before entering the CO2 absorber towers. In the DCC the flue gas will flow counter-current to the

water flow in a packed bed and the water is recycled through a circulation pump and seawater cooled heat

exchanger. Potable water will also be required for make up. The water solution is re-circulated through theDCC column in order to cool the flue gas from about 80ºC to approximately 30ºC. NaOH is added to the

DCC liquid as required to capture and neutralise the incoming SO2. The DCC accumulates sodium

sulphate and suspended solids stemming from fly ash and therefore an aqueous effluent bleed is required.

The flue gas leaving the DCC will be routed through the booster fan before entering the bottom of the

absorber tower, where it will come into contact with the amine solvent. Lean amine, fed at the top of the

mass transfer section, will flow through a bed of packing counter-current to the flue gas and will end up as

CO2 rich amine in the absorber’s sump. The clean flue gas will be discharged to the atmosphere via a new

stack common to the two absorber towers and the steam and power supply (SPS). Two water wash

sections will be located on the upper part of the CO2 absorber in order to minimise amine emissions to the

environment (amine slip) and to cool the flue gas.

5. Outline of the Carbon Capture Process





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5.4 CO 2 Str ippers

The rich amine from the CO2 absorber tower’s sump will be pumped through heat exchangers to raise the

temperature of the rich amine before continuing to the stripper. A portion of the stream will be passed

through the rich amine filter module where particles, pollution and some high molecular amine degradation

products will be removed for disposal. CO2 will be released and the amine solvent regenerated in the

stripper. Heat required for the CO2 stripping process will be provided by condensing steam in the reboilers.

The CO2 product will be washed in a packed bed section in order to minimise amine carry over to the

stripper overhead condenser.

In the stripper overhead condenser the CO2 will be cooled to 30°C and the condensed water will be routed

back to the stripper overhead section.

A small slip stream of the CO2 lean amine solvent will be routed to a proprietary amine reclaimer connected

to the stripper. Caustic soda will be injected into the amine reclaimer to recover some of the heat stable

salts as molecular amines. These will be conveyed back to the stripper.

5.5 CO 2 Compress ion

CO2 from the stripper will be routed to the CO2 transportation conditioning plant where the CO2 will be

compressed, cooled and dried prior to export. Two 50% rated compression and drying trains are proposed.

The CO2 will be compressed from 0.5 bar(g) to up to 36 bar(g) (Note: expected maximum export pressure

is 34 bar(g)) at a temperature of 30ºC and the CO2 will be exported via the National Grid pipeline in the

vapour phase.

In between compression stages, cooling and condensation/removal of water will be included.

5.6 CO 2 Drying and Ox ygen Removal

Free water combined with CO2 forms carbonic acid (H2CO3) which is detrimental to carbon steel

components, such as pipelines, causing corrosion on the internal surfaces. Additionally, at elevated

pressures and ambient temperature, hydrates can form which could cause blockages in equipment, valves

and pipelines. Free water comes both from the carbon capture process and from the chemical combination

of free oxygen (O2) and free hydrogen (H2) in the CO2 stream. To control the O2 level, H2 is injected in

slight excess quantities upstream of a catalyst bed which will combine the free O2 and free H2 to producewater. A preconditioning vessel (containing a fixed bed catalyst) is provided for the conversion of any free

O2 to water using H2. The H2 requirement is estimated at 0.26 kgmol/h and will potentially be supplied by

hydrogen cylinders in 4 truck trailers.

To minimise formation of carbonic acid or hydrates during CO2 transportation, a dehydration system will be

included following CO2 compression at Longannet. The dehydration system consists of a series of knock-

out pots to remove the bulk of the free water followed by an absorption dryer package, which will remove

moisture to less than 50 ppmv so as to protect the downstream equipment. The maximum permitted

moisture content is specified as 50 ppmv to ensure that free water will not be released from the CO 2 stream

at the worst possible combination of pressure and temperature experienced within the onshore

transportation pipeline.

The absorption dryer is a vendor package typically consisting of:





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Multi bed molecular sieve dryers, with one normally off-line for regeneration; Filters;

Regeneration gas compressor;

Electric dryer bed regeneration heater;

Switching valves;

Controls

5.7 AGI and CO 2 Export

A small CO2 Above Ground Installation (AGI) will be provided beside the CCP. This will contain an

analyser, remote operated and manual isolation valves and a pigging station. The main AGI is located offsite to the north of the power station at a location called Valleyfield. The Valleyfield site will contain pigging

stations, flowmeters, isolation valves, etc. The pipeline from the CCP to Valleyfield will be 600mm NB and

approx 3.5 km long. Beyond Valleyfield the pipeline will be 900mm NB.

5.8 Contro l o f CO 2 Spec i f i ca t ion

Measures have been put in place to prevent out of specification CO2 being exported from the CCP into the

Onshore Transportation System. This consists of a series of analysers which will measure the levels of the

specified contaminants, including water, in the compressed CO2 stream. Each CCP train will have a full set

of analysers just upstream of the export terminal point. If the contaminant levels within the CO2 stream are

greater than specified limits the CO2 stream will be vented to the CCP stack where it will mix with the

depleted flue gases and be vented to atmosphere. When the contaminant levels are all within specificationthe CO2 stream will be switched to export and the vent closed. Should the contaminant levels go out of

specification at any time the CO2 flow will be diverted from export to vent until the contaminant levels fall

back below the specified limits. At this time, since no analysers with adequate resolution of contaminants

in CO2 have been identified which have a SIL rating, it is envisaged that operators will manually control the

vent/export of the CO2 based on measurement trends and alarms from the analysers. This is considered

adequate since no rapid changes in contaminant levels are anticipated.

A further layer of protection against contaminants, including water, exceeding specified limits in the CO2 is

proposed in the FEED design. This consists of a further set of analysers downstream of the carbon

capture plant / onshore transportation pipeline terminal point. Should out of specification contaminant

levels be detected an order will be given from the end-to-end system manager to vent the CO 2 from theCCP and to close the isolation valves in the Onshore Transporation System at the Valleyfield AGI. This will

contain the out of specification CO2 to a 3.3 km length of pipeline. Facilities will be provided to

depressurise this 3.3 km section by venting to atmosphere under manual control utilising the CCP stack

should detailed analysis of the exported CO2 indicate that it is required. This length of pipeline will then be

re-pressurised in a controlled manner when the export CO2 again meets specification.

A High Integrity Pressure Protection System (HIPPS) will be provided to prevent over pressurisation of the

Onshore Transportation System. The details of the design of the HIPPS have yet to be finalised.





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5.9 Auxi l ia r y P lant

5.9.1 Power and Steam Supply

A power and steam supply (SPS) plant will be installed to provide steam and electricity to the carbon

capture process. The CCP will require low pressure steam under normal operation and an additional

medium pressure steam during the solvent reclaiming process. The full quantity of condensate will be

returned from the CCP reboiler to the SPS plant with cleanliness ensured through conductivity monitoring.

The SPS flue gas will be discharged via a new stack also used for the clean flue gas discharge from the

absorbers.

The SPS will be fuelled by natural gas taken from upstream of the existing power station supply

connection. The detailed configuration of the SPS has yet to be finalised but will probably consist of two

40 MWe gas turbine generator sets, each equipped with a heat recovery steam generator (HRSG) which

will also have supplementary firing plus one steam turbine generator set. In addition there will be one

package boiler which will supply steam for peaking activities and to maintain the CCP in a hot standby

condition when the CCP is not operating. The SPS will operate in ‘island’ mode or in parallel with the

existing LPS electrical system. Surplus power generated will be fed to the LPS 275 kV system.

5.9.2 Cooling Water

Seawater will be used as the main cooling medium for the new facilities. Additional sea water cooling

pumps will be installed at Longannet that will abstract water from one or more existing cooling water inletchambers located upstream of the existing drum screens.

5.9.3 Eff luents and Waste

Six main effluent and waste streams have been identified for the whole CCP process. These effluents and

their method of disposal will be as follows:

DCC effluent containing sodium sulphate and traces of suspended solids: Disposal to the Firth of Forth

following on-site treatment

Amine reclaimer waste: Off-site incineration in a waste incinerator

Condensate waste: Recycling for re-use in the process

Boiler blowdown: Disposal to the Firth of Forth after cooling Spent carbon filter waste: Removed from site by road tanker for recycling

Solvent filter waste: Removed from site by road tanker for disposal.

These solutions will be subject to meeting the necessary environmental and permitting requirements and

will be revisited upon receipt of more detailed operational information from the Mobile Test Unit (MTU)

installed at LPS.

5.9.4 Anci l lary Services

The main ancillary services for the CCS plant will consist of:

Distributed control system

Instrument and service air supply

Fire fighting water





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Potable water Demineralised water

Nitrogen

Sulphuric acid

Sodium hydroxide

A preliminary design package has been prepared for these systems.

5.10 Cont ro l Ph i losophy

5.10.1 Carbon Capture Plant Contro l Phi losophy

Although the CCP is to be retrofitted to the existing power station and is co-located within the site, the CCP,

CO2 compression plant, and SPS will be controlled by an entirely new control system from a new, manned

dedicated control room within the existing Longannet site boundary. Shutdowns and trips within the CCP

will not have an impact on power station operations, however, if the power station trips (or reduces load),

the CCP will come off line.

A summary of the control philosophy for the CCP and CO2 Compression plant is provided below.

The operating modes for the power station will be start-up, part load, base load and shutdown. The unit

selected for carbon capture will normally only operate at base load, 600 MWe gross, 24 hrs/day with the

CCP process permitted to extract CO2 when the unit is operating above 363 MWe gross load. The CCP is

designed to accept the volume of flue gas equivalent to approximately 50% of rated output and the unitmust run at a 10% higher load to provide excess flue gases ensuring a positive flow up the stack to avoid

air being drawn down the stack into the CCP.

On start-up the flue gases will be directed up the existing stack until the unit reaches 363 MWe, when

dampers can be opened to divert a proportion of flue gases to the CCP. Once the CO2 is captured, the

CCP plant will vent the CO2 until it meets the specification required by the downstream processes. When

the CO2 meets specification it will be directed to the Onshore Transportation System.

A new control system will be supplied for the CCP to control the plant and support the operational

strategies and requirements of the operators and carbon capture process. The control system will be a

single dedicated DCS system and will provide the sole means of remote control and supervision of theCCP, providing the control functions for the CCP equipment, the gas turbines, the Heat Recovery Steam

Generators, the steam turbine, CO2 Compression and Drying as well as various auxiliary systems.

The system will be based on a supervisory DCS providing supervisory control and monitoring of various

plant packaged control systems. The majority of the mechanical plant packages will have their own vendor

supplied programmable logic control (PLC) systems. The plant packages comprise of: 2 x Gas Turbines, 1

x Steam Turbine, 2 x Burner Management Systems and 2 x CO2 Compressors. Remaining equipment

control is integrated into the DCS.

The system will interface with the existing upstream power plant and the downstream pipeline system.





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5.10.2 End-to -End Carbon Capt ure and Stora ge Chain Control Phi los ophy

5.10.2.1 Overview

The CO2 compression and conditioning plant at Longannet will operate to maintain the CO2 production rate

and the flow rate requirements of the pipeline system to National Grid’s Blackhill Compressor Station. The

pipeline systems between LPS and Blackhill Compressor Station and between Blackhill and Goldeneye

have capacity to provide some line-pack by varying line pressure and consequently the quantity of CO2 in

the pipelines. Line-pack in the pipeline will be utilised to manage, whenever practicable, abnormal

conditions and small transients due to time lags between supply and demand balancing. For example, if the

generator trips or is about to shut down, the wells can be turned down to minimum flow to utilize the line-

pack to extend the period of well operation and avoid a shutdown. Alternatively, if the wells shut down,carbon capture can continue at Longannet until the pipelines are at maximum pressure. It will not be used

as an operational tool to manage significant supply/demand imbalance. There is only a limited amount of

line-pack between the maximum and minimum operating pressures (31 – 34 barg) to absorb these

transients

Once the CO2 has reached the offshore systems, the start-up and shutdown of the downstream systems

will be mainly by remote valve operation. These valves will allow CO2 to enter Shell’s injection and storage

systems.

If the injection wells shut down the flue gases from the generator will be diverted to the existing station

stack when the pipelines reach maximum pressure.

5.10.2.2 Control Systems

The proposed control solution will comprise of four independent control systems (one system per chain

section), ie:

1. ScottishPower’s LPS Control System: Responsible for the control of the existing power plant equipment

(from which the CO2 is to be extracted from the flue gas)

2. ScottishPower’s CCP DCS: Responsible for controlling the CCP, the CO2 compression and conditioning

plant and the SPS

3. National Grid’s Pipeline Control System: Responsible for controlling the Onshore Transportation System

from LPS to Blackhill; and the dense phase Blackhill Compressor Station

4. Shell’s St Fergus/Goldeneye Platform Control System; this system will control the CO2 transportationfrom the Blackhill Compressor Station to the Goldeneye platform and the injection into the permanent

storage reservoir

There will also be a dedicated Information Management System (IMS) which will provide a central,

accessible, data repository for the Consortium Partners. This system will share data and is not considered

critical to operations. This system will also provide a real-time overview of the CCP chain to the Consortium

Partners and selected key stakeholders. This system will be based on Plant Information (PI) technology.

The four new control systems will be operated from four permanently manned control rooms by three

independent organisations (ScottishPower, National Grid and Shell). The control systems will communicate

with each other to provide a reliable and safe solution.





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The controls for each system will be based on standard, developed control system technology alreadyestablished in the respective industry. There will be no new novel techniques or systems deployed. The

control systems to be deployed shall be well established for their application and their design is recognised

as best practice through experience of operating the process. As a result there is no requirement to

harmonise the control system design across the project.

Generally each control system will be designed to provide the following principle functions:

Support the operation of the plant

Ensure automatic, safe, secure and efficient operation of the plant under all conditions

Ensure the plant remains within operational constraints

A sufficient level of automation reducing dependence on operators activities

Allow remote control of the equipment (via a remote human machine interface) Operation, shutdown, control and monitoring of process equipment, instruments, electrical plant, and

proprietary control systems

Monitoring of instruments

The systems will be designed such that the start-up, operation and shutdown of the associated process

plant can be carried out from a remote location (the dedicated Central Control Room for each CCS chain

element). Dedicated supervisory workstations will be provided for this function.

The systems will be automated, where appropriate, with the operator normally involved in a supervisory

capacity only, with a minimal number of manual activities to start and stop the plant consistent with a new

demonstration process.

For process control, the control systems will be connected to field mounted instrumentation and process

control elements and actuators (such as electrical plant, pumps, fans, valves etc). The systems will utilise

control logic through logic solvers to automatically control the process. This will be undertaken by plant

actuators, which are set by the control system, depending on process conditions measured by the plant

instrumentation. The operator will interface with the process via the control systems human machine

interfaces (operator stations/local control panels).

This independent solution was chosen as the preferred control option due to the diverse operating

environments and specialisms required for each chain section. The proposed scheme will mirror the control

solutions deployed for similar, proven national gas pipeline networks as the chain will be operated and

controlled in a similar fashion. Integration of the chain control systems into one unified system was notconsidered as the approach would not support the local operational requirements.

Each section of the CCS chain will be supplied with a complete control system that will include all facilities

and systems necessary to operate the associated process and electrical plant. These will generally

comprise of the following:

Operation and Monitoring System Facilities

Automated Control and Protection Equipment

Communication Systems

Data Storage and Retrieval Systems

Instrumentation to monitor the process and electrical/mechanical plant





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The systems will follow modern control system practice based on microprocessor technology. They will bedesigned to achieve the required reliability, availability and performance of the entire chain. A fault tolerant

design approach will be adopted to ensure that no failure will cause the operator to lose control of and/or

communication to/from the plant.

Each chain element will be self-sufficient, supervised and operated in an independent fashion as far as

possible under the guidance of their respective operating procedures.

The control systems will be interfaced, rather than integrated, to facilitate overall co-ordinated control and

monitoring. The individual control systems will interlink and exchange data as necessary for process

coordination. Signals critical to safety and operation of plant and personnel will be transmitted directly

between the systems; and non-essential signals, will be transited via a live information managementdatabase.

The data exchanged will have no controlling actions on adjacent party systems. Any controlling actions

required between parties will be requested via a manual instruction process with the subsequent controlling

actions carried out by the operator for the area concerned.

National Grid will coordinate the operation of the chain by balancing the flow of CO2 along the End-to-End

CCS chain due to their central location within the chain and their considerable experience of operating

pipeline networks similar to the CCS chain. National Grid will therefore exchange data with the other parties

as required to achieve the required coordination.

The control and performance of the existing power generating station is not expected to be affected by theoperation of the new CCP, therefore the existing control arrangements for LPS remain as per the existing

procedures. The plant is operated from an existing, permanently manned control room utilising the existing

control system.

The CCP, including the SPS, will be controlled from a new adjacent permanently manned control room,

using dedicated control systems.

CO2 transportation (from Longannet to Blackhill Compressor Station) and the dense phase compression

activities will be controlled by the onshore transportation pipeline control system. The control system is a

dedicated Supervisory Control and Data Acquisition (SCADA) system allowing remote principle operation

of the equipment from National Grid’s Control Centre. The National Grid installation(s) will be normallyunmanned.

All activities connected with CO2 offshore transportation and injection into geological strata will be

controlled locally by Shell’s St Fergus Control Centre.

The IMS system transmits non-essential operational data and is subsequently not essential for operation.

Therefore the operation of the end-to-end chain is not affected if the IMS system is not available.

Each independent installation on the end-to-end CCS chain will have a number of industrial safety systems

installed that are designed to protect the personnel, the environment, and plant (equipment and structures)

from the inherent dangers of the process.





21


Safety control systems will be independent (hardware) from its respective process control system andcertified by a relevant third party organisation. The key safety systems for the project comprise of the

following: ESD system; CO2 Composition Analysis; F&G Detection System; CO2 Detection; High Integrity

Pressure Protection System (HIPPS).

5.11 Carbon Capture Si t e Boundar ies

The scope of the carbon capture plant in shown in the block diagram below.

The key process tie-in points are:

Flue gas: At the existing flue gas ductwork adjacent to the stack

CO2 export: At the National Grid Longannet AGI adjacent to the carbon capture plant

Table 5.1: Block Diagram of the Carbon Capture Plant

Source: Aker Clean Carbon





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6.1 Overa l l Pro jec t Safety Managem ent SMS

An overall Carbon Capture and Storage project Safety Management System (SMS) will be developed to

provide a safety framework for the project as a whole. This will provide a unified approach to safety across

the consortium partners and project interfaces.

ScottishPower will lead a Health and Safety (H&S) Steering Group (SG) with membership from each

Consortium partner. The objective of this H&S SG will be to manage and resolve CCS chain interface

issues through the joint working policies and management controls of the overarching safety management

system (SMS). These will be developed and implemented during design, construction, commissioning andoperations, for the End-to-End Project.

The H&S SG will hold regular interface meetings to discuss H&S performance, any incidents or near

misses, effectiveness of emergency plan testing, audit results and progress with actions, as well as

identifying any emerging H&S issues that require consideration and implementation of controls.

6.2 Longannet Power Stat ion Heal th and Safety Pol icy

ScottishPower maintains a Policy Statement on Health and Safety for Longannet Power Station, which will

also apply to the CCP. This statement comprehensively documents how Longannet Power Station will

identify, plan and control all health, safety and welfare issues to ensure compliance with health and safety

legislation and Approved Codes of Practice and guidance. In particular it addresses HSG 65: Successful

Health and Safety Management, published by HMSO.

This document covers the four main areas:

Safety Management System: This outlines the formulation and development of the safety management

system employed at Longannet Power Station

Policy Statement: This is a general statement of intent and outlines the philosophy in respect of the

management of health, safety and welfare

Organisation: This outlines individual’s roles and responsibilities within the Longannet Power Station

management structure

Arrangements: This details procedures to be used to ensure effective implementation of the policy

statement.

ScottishPower requires the SMS to address the Health and Safety at Work Etc. Act 1974, and the

Management of Health and Safety at Work Regulations 1999, by preparing, and revising, a safety policy

brought to the attention of all employees. The SMS is to record arrangements for effective organisation,

planning, implementation, control, monitoring and review of the preventative and protective measures. The

SMS is to be updated at least annually and after any internal or external audits, with the objectives of:

Complying with new legislation and formulating new procedures

Identifying the potential risk to business and people

Amending existing procedures following review

Developing Safe Systems of Work

6. Safety Management Systems





23


The ScottishPower policy identifies requirements for planning, actively and reactively monitoring, auditing,and reviewing the SMS. It also identifies sources of external information for assisting in establishing

management techniques and best practice, key performance indicators are identified for review, together

with feedback to personnel and benchmarking against other ScottishPower businesses, other utility

companies and contractors.

The ScottishPower Policy identifies the organisation and the individual responsibilities for all personnel.

This also covers issues such as: Accident Investigations, Audits, Occupational Health, Contractors and

Visitors.

The Policy identifies the types of hazards that may arise, training requirements, safe systems of work, the

environment, safe place of work, machinery and plant, noise, radiation, COSHH, asbestos, fire, First Aidand welfare, record keeping and emergency procedures.

6.3 Carbon Capt ure Plant SMS

A specific Safety Management System for the CCP will be required. This will be developed by

ScottishPower and their contractor, Aker Clean Carbon. This will address the management and operation

of the CCP and the interfaces with other parts of the CCS project, particularly LPS and the Onshore

Transportation System.

Should the COMAH Regulations apply; a Major Accident Prevention Plan will also be developed for the

Carbon Capture plant.

The Safety Management System and, if applicable, the Major Accident Prevention Plan will be integrated

with the existing Business Continuity Plan and Health and Safety Policy for Longannet Power Station,

which are described below.

6.4 Longannet Pow er St at ion Bus iness Cont inu i t y Plan

ScottishPower maintains a Business Continuity Plan for the Longannet Power Station. This aims to

minimise the impact of a loss of generation but stresses a prioritisation is to ensure the safety of all staff,

visitors and contractors on the site by invoking the existing emergency plans. It is further stressed that at all

times safety must not be compromised, so prioritisation should also take account of safety systems

recovery. It is also stressed that the prioritisation of recovery of all normal business processes is thereforenot relevant. This Business Continuity Plan will need to be revised to take account of the CCP.

In the event of an incident the recovery team (who are identified within the Business Continuity Plan)

should be established and start to work through their responsibilities as identified within the Business

Continuity Plan.





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7.1 Hazardous Substances on Si te

The following hazardous substances are expected to be on site.

7.1.1 Carbon Dioxide

Carbon dioxide (CAS number 000124-38-9) will be present in the CCP in the following forms:

As a constituent of the power station flue gas

Absorbed in the amine solution

As a low pressure gas from the strippers, which will be saturated with water As a high pressure gas from the carbon dioxide compressors; this gas will be dried and any trace

oxygen removed so that the gas is effectively 100% carbon dioxide

No storage facilities for CO2 storage are to be provided on the site.

The maximum total mass of CO2 in gaseous form on site is expected to be considerably less than the

COMAH lower tier threshold for CO2 which is expected to be set at 100 tonnes. Consequently the site

would appear not to come under the COMAH regulations.

7.1.2 Amines

A mixture of two amine solutions (Amine 1 and Amine 2) is to be used for this project. The details of

amines, Amine 1 and Amine 2, and the mixture are kept confidential at this stage due to commercial and

competitive reasons. However to enable the Competent Authority to assess the safety and environmental

impact of the CC project full details of the amines and their properties will supplied directly to the

HSE/SEPA by Aker Clean Carbon in a separate document. Below is a summary of the main health and

risk information for the two amines.

Amine 1

The following Risk Phases apply:

R36/38 Irritating to eyes and skin

R52/53 Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment.

Amine 1 will be stored on site in a bunded storage tank

Amine 2

The following Risk Phases apply:

R34 Causes Burns

R42/43 May cause sensitisation by inhalation and skin contact

R63 Possible risk of harm to the unborn child

R52/53 Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment.

7. Identification of Potential Major AccidentHazards





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Amine 2 will be stored on site in 1 m³ IBCs distributed between each of the two process streams on-sitewith the remainder stored in the chemical storage bund.

Amine Mixture Properties

A mixture of amine 1 and amine 2 will be used in the process. The properties of the mixture are as follows:

The following Risk Phases apply to the mixture:

R34 Causes burns

R42/43 May cause sensitisation by inhalation and skin contact

R62 Possible risk of impaired fertility

R63 Possible risk of harm to the unborn child R52/53 Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment.

7.1.3 Other Substanc es

Table 7.1 below details the the hazardous substances, other than CO2 and amines, expected to be used on

Longannet CCP site:





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Table 7.1: Hazardous Substances Expected to be Used at Longannet Carbone Capture Plant

7.2 Major Acc iden t Hazard Iden t i f i ca t ion

A specific MAH HAZID meeting was held to identify the potential major accident hazards that could resultfrom the operation of the carbon capture plant.

For the meeting, the plant was divided into seven nodes which were examined to identify potential major

accident hazards.

The main findings of the meeting were:

Five cases of Major Accident Hazards were identified

One additional case of a possible Major Accident Hazard was identified but due to insufficient design

information at this time this was actioned for further investigation at the detailed design stage

The quantities of potentially hazardous substances on site were considerably less than the lower tier

threshold for COMAH or in the case of CO2 the anticipated lower tier level should it be redesignated as

a relevant fluid in the proposed revision of the Seveso Directive





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Note: Detailed HAZIDs and HAZOPs have also been carried out on the plant as part of the FEED process.Some of the results of the HAZIDs and HAZOPs have been incorporated, including installing a HIPPS

system on the outlet of the CCP and there is an action to review options to ensure that there can be no

significant CO2 flow back from the export pipeline in the event of a pressure boundary failure in the CCP.

Other results are recorded for action during the detail design stage.

7.3 MAHs t o be Considered

As a result of the HAZID meeting and subsequent discussions with the Competent Authority it was agreed

that the following Major Accident Hazards would be further investigated as potentially the worse case

accidents.

7.3.1 MAHs – CO 2 Dispersion

Leakage of low pressure CO2 from the stripper and downstream pipework

Leakage of high pressure CO2 from the discharge of the compressors and downstream pipework

7.3.2 MAHs – Nat ural Gas Release

Jet fire

Flash fire

Vapour cloud explosion

7.3.3 Amine Release

Release of amines to the environment.

7.3.4 Other Hazards

Although not considered in detail at this stage, it is recognised that the final COMAH safety report would

have to take account of the following additional hazards:

Release of hydrogen leading to fire and explosion

Leakage of other chemicals to the environment

External hazards especially from the power station, e.g. leakage from the propane storage tanks leading

to fire and explosion.





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8.1 Model l ing Methods

8.1.1 Model l ing Software

Accidental releases of CO2 and natural gas were modelled using the DNV (Det-Norsk Veritas) PHAST

modelling software version 6.6. This is a well recognised consequence software package that has been

specifically evaluated by the HSE for modelling CO2 releases.

8.1.2 Weather Condi t ions for Model l ing

All scenarios were modelled under three standard weather conditions as recommended by DNV.

Table 8.1: Standard Atmospheric Conditions Modelled

Wind speed (m/s) Pasquill (Atmospheric) Stability

Category

Definition

5 m/s D Neutral

1.5 m/s D Neutral

1.5 m/s F Stable

Source: DNV Phast

HSE has suggested higher wind speeds should be considered and this will be done for any future MAHstudy. However the models run so far show worse case results occur for stable atmospheric conditions.

8.2 Model l ing Cases Considered

The following cases were modelled for this stage of the work.

8.2.1 Carbon Dioxide Releases

Low Pressure CO2 Releases

The parameters for the release modelled were:

Design point temperature and pressure for the low pressure part of system

Full bore rupture of piping

Duration of release – 6 minutes

All wind directions were modelled

A number of cases at different points along the route of the low pressure system from the CO 2 stripper to

the inlet to the compressors were modelled.

High Pressure CO2 Releases


Design point temperature and pressure of the piping Full bore rupture of piping


8. Consequence Modelling





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Cases were modelled at two points along the route of the high pressure CO 2 piping from the compressorsto the pigging station.

8.2.2 Natura l Gas Releases


Design point temperature and pressures of the piping

Full bore rupture of the piping

Duration of release – 60 seconds


Jet fire, flash fire and vapour cloud explosion were modelled

Most of the gas piping will be run underground. Releases were modelled at the location of the gas

treatment plant for the SPS and at the approximate gas input point for the power generation equipment.

8.3 Other re leases and Future Work

Hydrogen release modelling will be performed during the next stage of the work.

Safeguards and mitigations have been identified for amine releases.

All consequence modelling will be repeated during the implementation phase of the work for inclusion in the

final issue of the MAH report that will be submitted to the HSE.





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9.1 Carbon Diox ide Releases

Low Pressure CO2 Releases

The modelling of this accident is very pessimistic as it assumes that a full bore diameter rupture of the

pipeline occurs that cannot be isolated and therefore the release continues at the normal stripper CO2

discharge rate. The model assumed the release occurred for 6 minutes but toxic end points were not time

limited.

In practice, in the event of a CO2 pipeline rupture the steam supply to the stripper would be shut-offremotely and the rate of CO2 release would reduce as the residual heat in the stripper reduced. At the

detailed design stage consideration will be given to providing remote operating isolation valves on the

outlet from the stripper that could be closed in the event of a leak occurring.

The results obtained show that inner effect zone is confined to the immediate vicinity of the CCP. The

outer effect zones barely reach the control room. It would therefore be most likely that personnel within the

control room would survive such an event. There appears to be no significant risk to personnel within the

power station buildings or to the general public outside the power station and CCP boundaries.

From the wind rose information obtained from Gogarbank Meteorological Station it can be seen that there

is a strong prevalence of winds from the south west. This wind direction would blow released CO2 to the

north east - away from the CCP control room and the power station, thus reducing the risk to personnel and

visitors on site.

The main risk for personnel on site may well be entering pockets of CO 2 formed following smaller leaks that

would be more difficult to detect. At the implementation stage of the project, consideration will need to be

given to how fixed and portable CO2 detectors will be used to safeguard personnel working on the plant

and visitors to the site.

High Pressure CO2 Releases

A failure of the high pressure CO2 line has been modelled. In theory this failure could depressurise the

Onshore Transportation System. However, multiple independent failsafe features are built into the pipelinedesign and such an occurrence is considered to be virtually incredible. The pipeline has been assumed to

be isolated, the compressors shut down and pipeline depressurised within 60 seconds of a leak occurring.

The modelling shows the inner effect zone is limited to the area around the high pressure CO 2 system and

generally the effects zones are smaller than those for the low pressure release.

9.2 Natura l Gas Releases

The results for the releases of natural gas leading to jet fire and vapour cloud explosion (VCE) indicated

that the inner effect zones would cover the whole of the of the carbon capture plant and in the case of the

VCE part of the power station as well. However the modelling undertaken to date is provisional as there is

no firm design for the SPS and it is assessed to be pessimistic. In particular it is expected that the

following may affect the consequences of accidents:

9. Discussion of Results





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Though the resistance of 1 km of pipeline was considered in the modelling no further restrictions arecurrently accounted for

Pipeline failures were considered to be full bore guillotine failures

No account was taken of the shielding effects of buildings and equipment on site

The potential for an unconfined natural gas cloud explosion (VCE) with natural gas of the scale

modelled is debatable - this is because it has been found that only the proportion of the gas within the

congested region contributes to the explosion

The type of gas turbines to be used for the SPS will be standard units with a considerable history of safe

operation and the gas pipelines will be designed and built to established codes. Pipeline failure rates have

not been considered at this time as this preliminary report considers only the worst case scenarios.

However, pipeline failure rates will need to be reviewed during the major accident hazard studies during thedetail design stage of the project.

It is expected that more detailed analysis of the confirmed design will be able to show that the risks for

personnel operating the SPS will tolerable and as low as reasonably practicable and the risks to the

existing power station and the general public outside the power station and carbon capture boundaries will

be negligible.

9.3 Amine Releases

Aspects of the installation that could be a factor in the potential for amine release to the environment

include storage/replenishing of amine tanks located in the CCP process area and stormwater / firewater

discharge, as a result of catastrophic tank failure overtopping the bunds and/or sumps or prolonged rainfallor firewater inundation resulting in overflow.

Storage arrangements for the amine chemicals required for use within the CCP are shown in the table

below.

Table 9.1: Amine Storage Summary

Chemical Use in Process Storage Arrangement

Amine 1 Absorber Unit in CCP Above ground bunded tank

Amine 2 Absorber Unit in CCP 1 m3 IBC containers

Amine mix Absorber Unit in CCP Above ground bunded tank

Source: Aker Clean Carbon

The mechanism of amine impact is direct fish toxicity (salmon and lamprey) and indirect impact to feeding

birds through direct impacts to their prey (molluscs and crustaceans).

The assessment of amines considered those of 2-amino ethanol (monoethanolamine, MEA) which is

commonly used in carbon capture processes. LC50 concentration (96 hours) for MEA for fish toxicity is

125 mg/l and the EC50 (48 hours) concentration for Daphnia magna is 33mg/l. Partition coefficient for

MEA is negative (LogKow = -1.31), meaning that the compound preferentially partitions to water rather thanlipid-based cellular material. MEA is considered to have no bio-concentration potential, due to its negative





32


partition coefficient. Impacts to birds from eating contaminated prey are therefore considered to beinsignificant.

A worst case catastrophic event of tank failure would potentially result in a significant release of mixed

amine to the environment. Further work would be needed to assess any impacts to the Middle Forth

marine environment from such a major accident release. The adoption of the proposed control measures

discussed below is designed to minimise the impacts of such a release to the environment.

9.4 Safeguards and Mi t igat ion

The detailed design of the CCP has not yet started. As such the full list of design safeguards and

mitigation against potential MAHs is not yet available. However, the following features would be expectedto be in the design:

Use of experience gained from the on-site MTU pilot plant

Use of appropriate materials for the service environment

Equipment will be to appropriate codes and standards

The plant will be fully instrumented, probably beyond that needed for control purposes as this is a

technology demonstration plant

An appropriate control system will be used with any safety critical functions SIL rated

Alarms will be provided to detect process upsets and potentially hazardous occurrences

Where flammable gas may be present a zoning assessment will be performed and appropriately rated

equipment employed

There will multiple means of preventing backflow of CO2 from the export pipeline. The CCP operator

will be able to close all remotely operated valves at the AGI adjacent to the CCP. Consideration isbeing given to providing non return valves and/or a HIPPS to prevent return flow. There are also non

return valves at the Valleyfield AGI, which will stop flow back from the main pipeline. This is in addition

to the remote operated isolation valves and non-return valves at Valleyfield

An on-site emergency plan will be developed

The operators will be fully trained including rehearsing emergency procedures

Instrumentation, fixed and/or mobile, will be deployed to detect releases. It should be noted that

existing CO2 sensor types are not reliable for large CO2 leaks due to the thermal and mechanical shock

and indirect means such as temperature sensors and pressure instrumentation may have to be used to

detect large leaks

An automatic leak detection and isolation system will be used to isolate natural gas supplies in the event

of a major gas leak Appropriate personnel protection equipment will be employed

Appropriate fire detection and suppression equipment will be provided

A permit to work system will be used for working in potentially hazardous areas

In relation to potential hazards associated with a release of amines to the environment the following

measures are expected to be implemented and incorporated in the Plant design:

Unused amines will be stored in an above ground tank bunded to contain 110% of the tank capacity and

in 1 m³ IBC containers stored in bunded areas or on storage trays sized to contain 110% of the capacity

of the largest container or 25% of the total volume of chemicals stored, whichever is the greater

Tank filling will be carried out in a bunded area or with drainage to the contaminated drainage system to

ensure uncontrolled spillage or tanker rupture are contained

Hazardous waste will be stored in individually labelled containers such that the contents can be clearly

identified in accordance with waste labelling requirements including the European Waste Category





33


number. For larger volumes of hazardous waste such as spent amine the waste will be stored andtransported in tanks. Such material will be removed from site by a licensed waste contractor for

disposal in accordance with waste management regulations. The disposal route is expected to be

incineration

Rainfall from potentially contaminated areas will flow to Retention Pond A while other areas will flow to a

Retention Pond B. Uncontaminated water will be pumped to Retention Pond B for onward discharge to

the Forth. Discharge to the Forth will be prevented in the event of a fire and firewater contained for

appropriate disposal. Effluent will be tested for amine contamination prior to release to Forth

Liquids captured within bunds or sumps will be tested to establish whether there is any amine

contamination. A threshold of 2 mg/l is proposed as a trigger for requiring treatment of the liquids. Any

spillage or contaminated water will be pumped out and either recycled through the amine reclaimer unit

or disposed of by tanker to an appropriately licensed waste disposal facility In the event of prolonged rainfall or firewater inundation or catastrophic tank failure the bunds and/or

sumps will overflow to Retention Pond A. Stormwater or firewater in this pond will be contained until an

appropriate means of disposal is identified. In these circumstances this is mainly expected to be by

recycling through the amine reclaimer unit or by being tankered away for disposal to an appropriately

licensed waste disposal facility. Retention Pond A will remain essentially dry during normal operation to

ensure full capacity is maintained for emergency situations

Appropriate mitigation will be considered at the detail design stage to provide a form of flood protection

against the potential risk that contaminants will be transferred in flood water as the ponds are located

within the 0.5% annual exceedance probability tidal flood extent. Suitable valve flaps will be required at

the end of the stormwater outlets to ensure there is no intrusion of sea water back into the retention

ponds





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The key conclusions and recommendations identified in the MAH review are as follows:

10.1 Conclus ions

A preliminary examination of the risks associated with the proposed carbon capture plant planned to be

built at Longannet Power Station has been carried out. This assessment is necessarily preliminary as

the CCS project is still in the FEED stage and key aspects of the plant layout and configuration have yet

to be finalised.

The CCP would not come under the COMAH regulations as they are currently enacted butconsideration is being given to including CO2 as a named substance in a future revision of the

regulations. However, this project will not store CO2 on site and there is a limited inventory of CO2 in

process so it doubtful whether the COMAH regulations would apply even if they were to be amended to

include CO2.

The power plant will continue to be operable without the CCP by sending the flue gases to the existing

stack, thus failure of the CCP or unavailability of the pipeline to Blackhill Compressor Station would not

affect the safe and continued operation of the power station.

The effects of major failures of CO2 pipework have been modelled. Very pessimistic assumptions have

been used in the modelling. Even so the risks to personnel and the public outside the CCP boundary

would appear to be negligible. At this stage the worse case accident would appear to be failure of the

large bore low pressure pipeline between the stripper and the gas compressor.

The potential accidents involving the natural gas supply to the Steam and Power system were also

modelled.

A preliminary assessment of the effects on the environment of a release of amine has been carried out.

The analysis undertaken so far shows no reason why the risks associated with the operation of the CCP

could not be demonstrated to be tolerable and as low as reasonably practicable once the design is fully

developed.

10.2 Recommendat ions

Further hazard assessment should be carried out once the design is sufficiently mature. This shouldinclude consideration of other hazardous substances present on site, such as hydrogen.

Consideration should be given to having remotely operable isolation valves fitted on the CO2 outlet from

the stripper vessels.

Careful consideration should be given to the provision of fixed and / or portable CO2 monitors or other

devices to give warning to personnel of CO2 leaks.

More detailed consideration should be given to potential releases of hazardous chemicals to the

environment.

These recommendations will be carried forward to the implementation phase of the project.

10. Conclusions and Recommendations





35


AGI Above Ground Installation

ALARP As Low As Reasonably Practicable

CCP Carbon Capture Plant

CCS Carbon Capture Plant

CO 2 Carbon Dioxide

COMAH Control of Major Accident Hazards (Regulations)

DCC Direct Contact Cooler

DCS Distributed Control System

DECC The Department of Energy and Climate Change

ES D Emergency Shut Down

ESP Electrostatic Precipitator

F& G Fire and Gas

FEED Front End Engineering Design

H 2 Hydrogen

H& S Health and Safety

HAZID HAZard Identification (study)

HAZOP HAZardous Operations (study)

HIPPS High Integrity Pressure Protection System

HSE Health and Safety Executive

HSE Health, Safety and Environment

IMS Information Management System

LPS Longannet Power Station

MAH Major Accident Hazard

MTU Mobile Test Unit

MWe Megawatt electrical

NaOH Sodium Hydroxide

O 2 Oxygen

ppmv Parts per million by volume

PSR Pipeline Safety Regulations

SCADA Supervisory Control and Data Acquisition

SCR Selective Catalytic Reduction

SEPA The Scottish Environment Protection Agency

SG Steering Group

SH E Safety Health and Environment

SI L Safety Integrity LevelSM S Safety Management System

Glossary




SO 2 Sulphur Dioxide

SPS Steam and Power Supply

SWFGD Sea Water scrubbing Flue Gas Desulphurisation

UK United Kingdom

VCE Vapour Cloud Explosion

Ukccs Kt s3.2 Sp 001 Mah Report Final

Documents

Transcript of Ukccs Kt s3.2 Sp 001 Mah Report Final