hazop

Prepared by: Karin Nilsson

14 July 2009

Prepared for:

Eraring Energy

Document Number: ERAPOW\12-B177

Revision B

HAZOP STUDY REPORT OF THE

TURBINE HYDRAULIC POWER UNIT,

BOILER UPGRADE AND LOW NO

X

BURNERS AS PART OF THE ERARING

ENERGY POWER STATION UPGRADE

PROJECT

Acknowledgment

The author would like to thank the HAZOP review team and in particular Ian

O’Brian, Phil Fenney, Steve Shawcross, Graeme Hankin and Frank Mieszala

for organising the HAZOP Studies and providing input and reviews of minutes

and report.

Disclaimer

This report was prepared by Planager Pty Ltd (Planager) as an account of work

for Eraring Energy. The material in it reflects Planager's best judgement in the

light of the information available to it at the time of preparation. However, as

Planager cannot control the conditions under which this report may be used,

Planager and its related corporations will not be responsible for damages of any

nature resulting from use of or reliance upon this report. Planager's

responsibility for advice given is subject to the terms of engagement with

Eraring Energy.

HAZOP Study Report of the Turbine Hydraulic Power

Unit, Boiler Upgrade and Low NOx Burners as Part of

the Eraring Energy Power Station Upgrade Project

Rev Date Description Prepared By Authorised By A 19/06/2009 Draft for Comment Karin Nilsson Frank Mieszala

C

ONTENTS

1

I

... 6

1.1

Background ... 6

1.2

Aim of This Report ... 6

1.3

Location of EPS ... 7

1.4

Project Description ... 7

1.5

Scope of HAZOP Study ... 7

1.5.1

Boiler Upgrade ... 8

1.5.2

Turbine Hydraulic Power Supply ... 8

1.5.3

Low NO

Burners ... 8

2

M

... 9

2.1

Introduction ... 9

2.2

Details of the HAZOP Study Procedure ... 9

2.3

HAZOP Study Guidewords ... 10

2.4

Risk Ranking Tools ... 12

3

R

R

... 13

3.1

Presentation of Risk Results ... 13

3.2

Risk Levels of the Boilers Design ... 14

3.2.1

Level 4 Risks Boilers ... 14

3.2.2

Level 3 Risks Boilers ... 15

3.2.3

Level 2 and Level 1 Risks Boilers ... 18

3.3

Risk Levels of the Turbine Hydraulic Power Unit Design ... 18

3.3.1

Level 4 Risks Hydraulic Power Unit ... 18

3.3.2

Level 3 Risks Hydraulic Power Unit ... 18

3.4

Risk Levels of the Low NO

Burner Design ... 19

3.4.1

Level 4 Risks Low NO

Burners ... 19

3.4.2

Level 3 Risks Low NO

Burners ... 19

3.4.3

Level 2 and Level Low NO

Burners ... 19

3.5

Risk Profile of Plant Assuming HAZOP Recommendations in

Place ... 20

4

C

... 21

5

R

... 222

L

IST OF

A

PPENDICES

Appendix 1 – HAZOP Study Minutes

Appendix 2 – Approval as HAZOP Leader

Appendix 3 – Eraring Energy Risk Tools

R

EPORT

PROJECT TITLE:

Power Station Upgrade Project

LOCATION:

Eraring Energy Power Station.

HAZOP MINUTES:

Appendix 1

HAZOP Leaders:

Karin Nilsson (DoP Approved)

Mark Wyburn (Eraring Energy, second

half

day

of

Boiler

HAZOP.

Methodology

used

and

outcome

reviewed by Karin Nilsson)

HAZOP SCOPE AND DATES FOR STUDY:

-

Boiler Upgrade

8 April and 5 May 2009 (1½ days)

-

Turbine Hydraulic Power Supply 23 March 2009 (one day)

-

Low NO

Burners

22 April 2009 (one day)

RECORD OF ATTENDANCE

Name

Company

Position

Boiler Upgrade

Ian O’Brian

Eraring Energy

Project Manager, Boiler

Upgrade Project

Ray Ansell

Eraring Energy

Senior Tradesman

Chris Brucki

Eraring Energy

Boiler Team Leader and Asset

Management

Shaun Edwards

Eraring Energy

Project Change Manager

Gary Craig

Eraring Energy

Project Manager, CCP Project

Phil Fenney

Eraring Energy

Project Manager, Low NO

Burners

Mark Wyburn (part

time)

Eraring Energy

Chemical Asset Team Leader

RECORD OF ATTENDANCE

Turbine Hydraulic Power Unit

Steve Shawcross

Eraring Energy

Project Manager Turbine

Upgrade Project

Graham Hankin

Eraring Energy

Turbine Asset

Phil McWilliam

PPI – DPPA Rep

Project Manager

Daniel McNally

Eraring Energy

E&I Technician

Keith Clark

Eraring Energy

Operator

Ian Dawson

Eraring Energy

Projects Engineer

Steve Wheeler

Eraring Energy

Operations Team Leader

Steve Gambrill (part

time)

Eraring Energy

Environment

Gemma Keith

Eraring Energy

Secretarial Support

Low NO

Burner

Phil Fenney

Eraring Energy

Project Manager, Low NO

Burners

Steve Wheeler

Eraring Energy

Operations Engineer

Chris Brucki

Eraring Energy

Boiler Team Leader and Asset

Management

John Harris

Eraring Energy

Plant Owner

Tarkel Larson

Siemens

Field Services Manager

Kenneth Tichy

Siemens

Project Manager, Low NO

Burners

1

I

NTRODUCTION

1.1 B

ACKGROUND

The

Energy Directions Green Paper

(Ref 1) prepared by the NSW Government

identified that if the current trend of increased electricity demand continues,

additional generation capacity or demand management would be required by

2010.

Eraring Energy (EE), one of three State-Owned Corporations that manages a

diverse set of electricity-generating assets located throughout NSW operates a

coal-fired power station (at Eraring), known as Eraring Power Station (EPS).

EE has put forward a proposal to undertake capacity increase and performance

improvements to the existing EPS to increase the capacity of each of the four

660 MW generating units (which are capable of generating at an equivalent

rating of around 700 MW) to enable the units to operate up to a maximum

continuous rating of 750 MW.

EE has obtained Project Approval, subject to a number of Consent Conditions,

for the capacity increase project under section 75J of the EP&A Act in

accordance with the provisions of Part 3A of the EP&A Act. The Minister for

Planning is the approval authority for the application.

One of these Consent Conditions requires a HAZOP Study to be undertaken for

the proposed development, as follows:

...a Hazard and Operability Study (HAZOP) for the power station

upgrade, chaired by an independent, qualified person or team. The

independent person or team shall be approved by the

Director-General. The Study shall be carried out in accordance with the

Department’s publication Hazardous Industry Planning Advisory

Paper No. 8

– HAZOP report. If the Proponent intends to defer the

implementation of a recommendation, justification must be included.

1.2 A

IM OF

T

HIS

R

EPORT

Eraring Energy has commissioned Planager Pty Ltd to lead a multidisciplinary

team through the

HAZOP Study

of a number of sub-projects which form part of

the EPS’ Upgrade Project.

Planager’s principal risk engineer, Karin Nilsson, has received approval from

the Department of Planning to lead the HAZOP Study. The letter of approval for

Karin Nilsson as HAZOP study leader is included in Appendix 2.

The aim of the HAZOP study is to review a design of a technological system to

identify hazards or significant obstacles to operability, which could arise,

particularly through deviations from the design intent.

1.3 L

OCATION OF

EPS

EPS’s site comprises approximately 1,200 hectares of land and is located in a

natural dip on the western shore of Lake Macquarie. The site falls within the

Lake Macquarie Local Government Area, near the township of Dora Creek,

within the Morisset Planning District. The power station and associated

infrastructure covers a footprint of approximately 150 hectares, with the

remaining area including the CCP management facility, water canals, and

ancillary power station facilities.

The surrounds of the EPS consist largely of natural vegetated areas with

development dedicated primarily to the extractive industries, such as coal

mining. Some semi-rural areas exist to the south on the shores of Lake

Macquarie.

1.4 P

ROJECT

D

ESCRIPTION

The key objective of the project is to upgrade the infrastructure at EPS. By

replacing existing aging components of plant and equipment within the EPS

operating units, EE would be able to maintain operational capacity and the

replacement/renewal program would enable improved efficiency of operations

and the environmental and safety performance of EPS.

The upgrade would allow the four existing 660 MW generating units to operate

at a MCR of up to 750MW. This improved performance would be used to meet

the increasing demands of the NEM, particularly during peak periods.

Aged components of the Boiler and Turbine Generating Plant would be

refurbished to achieve a MCR of 750 MW generated at a Power Factor of 0.9 at

rated conditions (Generator 833 MVA rating). This would include:



“Steam Path Upgrade” of high pressure, intermediate pressure and low

pressure stages of the turbine;



Upgrade of generator;



Upgrade of generator transformer cooling system;



Additional tubing inside boiler;



Replacement of 28 boiler burners with low NOx burners; and



Other miscellaneous work.

1.5 S

COPE OF

HAZOP

S

TUDY

EE has identified the following three operations which would benefit from a

HAZOP Study:



Boiler Upgrade



Turbine Hydraulic Power Supply



Low NO

Burners

The HAZOP study sessions were all carried out

By Difference

with the existing

plant operation, i.e. the HAZOP focussed on the implication of the changes to

plants and processes which result from the proposed changes to boilers,

hydraulic unit and burners. As such, the HAZOP did not attempt to cover the

whole of the Power Station operation and design. The scope of each HAZOP

study is as follows:

1.5.1 Boiler Upgrade



Included:

The scope of the Boiler HAZOP includes the design and

operation of the actual boilers.



Excluded:

The scope excludes the new (Low NO

Burners, see below),

including the burner management, flame stability and wind box.

1.5.2 Turbine Hydraulic Power Supply



Included:

The scope includes the design and operation of pumps, fans,

piping, valving, instrumentation etc. which form part of the hydraulic

power unit.



Excluded:

The scope excludes the control system and the main oil

pump and the auxiliary pump. The Emergency Trip Device is also

outside the scope of this HAZOP. Further, outside the scope is the

extractor relay dump valve operation, the Turbine protection and control

module, the mechanical steam path upgrade.

Note that at the time of the HAZOP the exact composition of the

hydraulic oil was not known (it was believed to be some type of

phosphate ester). The HAZOP team took into account that it could be

potentially hazardous to people handling the material. As such the

HAZOP of the turbine hydraulic power unit is regarded as a

Preliminary

HAZOP

and further engineering investigation will be required (whether it

be in the form of supplementary HAZOP studies or other risk

management techniques).

1.5.3 Low NO

Burners



Included:

The scope of the Burner HAZOP included the new Low NO

Burners, including burner management, flame stability and wind box.

2

M

ETHODOLOGY

2.1 I

NTRODUCTION

The HAZOP study is based on engineering line diagrams (P&ID's) and outline

operating procedures. The consequences and deviations are identified, the

existing safeguards are highlighted and, where necessary, appropriate

corrective actions initiated.

A HAZOP study is a form of design review which concentrates on how the plant

will cope with abnormal conditions, rather than on how it will perform under

normal conditions. The study comprises consideration of each process line and

vessel, examining for each the possible causes and consequences of a wide

range of process abnormalities. While some of the postulated abnormalities

may be inapplicable for a particular process line, they are all probed with the

objective of identifying any significant route to a process upset, operating

problem or hazardous incident. It is, in effect, a very thorough but mainly

qualitative approach.

HAZOP is the method recommended for identifying hazards and problems

which prevent efficient operation of a processing plant. It is a technique which

provides opportunities for people to think creatively and examine all possible

ways in which hazards or operating problems might arise. To reduce the

chance that something is missed it is done in a systematic way - each pipeline

and each type of hazard being considered in turn. The study is carried out by a

team so that they can stimulate each other and build on each other’s ideas.

The results of a HAZOP depend more upon the experience and attitudes of the

participants and on the leadership style adopted, than on the procedures

themselves. The participants were selected to provide the necessary

experience, knowledge, skills and authority to approve the actions decided

upon. The Study leader needs to be very experienced in HAZOP studies and

Hazard Analysis techniques and capable of performing as an independent and

unbiased leader. This person needs to be familiar with other related techniques

and to know when other techniques would be beneficial compared to the

HAZOP technique.

2.2 D

ETAILS OF THE

HAZOP

S

TUDY

P

ROCEDURE

The HAZOP study was conducted according to ICI's traditional HAZOP

methodology, corresponding to established engineering practices. The study of

each step in the operation of the plant followed the pattern outlined below:



A brief outline of the purpose of the step in the operation and of the lines

involved with the operation is provided by one of the team members (usually

by the designer). The lines are highlighted on the P&ID with dotted lines



The purpose, design features, operating conditions, fittings, etc, are

explained.



Any general questions about the lines are then answered.



The detailed "line by line" study commences at this point. The discussion

leader takes the group through a series of guide words set out in a book

(see Section 2.3). Each card has a guide word or prompt on it, such as

"FLOW - HIGH", which identifies a deviation from normal operating

conditions. This is used to prompt discussion of the possible effects of flow

at an undesirably slow speed, and of the possible causes. If in the opinion

of the meeting, the combination of the consequences and the likelihood of

occurrence are sufficient to warrant action, then the combination is regarded

as a "problem" and minuted as such. Potential incidents with severe

consequences where the team judges that the risk management techniques

already designed into the process are sufficient are also minuted in order to

provide a record of the safeguards to be installed. Further, if a particular

item was subject to discussions then it would be minuted to record the

outcomes of these discussions.



For major risk areas the need for action is assessed quantitatively. For less

important risks the need for action can be based on experience and

judgement. The person responsible for defining the corrective action is also

nominated.



It should always be remembered that the main aim of the meeting is to find

problems needing solution, rather than determine actual solutions. If the

group becomes tied down by trying to resolve a problem it is better to

continue the discussion at a later date and proceed with the study.



When each guide word requires no more consideration, the chairperson

turns that card down revealing the next guide word.



Discussion for each guide word is confined to the line marked, the vessels or

other major equipment at each end and any equipment such as pumps or

heat exchangers in between. Any changes agreed at the meeting are

minuted, and where possible, marked on the P&I diagram or layout with red

pen.



When all guide words have been covered, the line is fully highlighted

(instead of with a dotted line) to show that it has been covered, and the next

line is chosen.



When all the lines in a plant sub-section have been reviewed, additional

guide words are used for review (overview) of the P&ID as a whole (see

below).

2.3 HAZOP

S

TUDY

G

UIDEWORDS

The guidewords applicable for continuous operations were used for the most of

the designs under review. If the operation has critical sequencing conditions,

such as for the Low NO

Burner project, then the continuous operation

guidewords were complemented with batch guidewords as listed below.

Line-By-Line Guidewords - Continuous Process



High Level / High Flow



Low Level / Low Flow



Zero Flow / Empty



Reverse Flow



High Pressure - Venting, relief rate



Low Pressure - Venting, relief rate



High Temperature



Low Temperature



Impurities - gaseous, liquid, solid



Change in concentration / Change in composition / Two phase flow /

Reactions



Testing - equipment / product



Plant Items - operable / maintainable



Instruments - sufficient for control / too many / correct location

Overview Guidewords



Toxicity



Commissioning



Start-up



Shutdown (isolation, purging)



Breakdown (including services failure)



Effluent



Fire and Explosion



Safety Equipment



Noise



Materials of Construction



Services required



Electrical: area classification / isolation / earthing



Quality and Consistency



Output - reliability and bottlenecks



Efficiency – losses



Simplicity

Line-By-Line Guidewords - Batch Process



Timing – start too early/late; stop too early/late



Flow High / Low



Level High / Low



Zero Flow / Empty



Reverse Flow



None



Density High / Low



Viscosity High / Low



Static



Effects on Existing Equipment



Concentration High / Low



Contamination / Extra Phase



Duration – Delayed / Omitted



Out of Sequence / Wrong Operation



Not Complete



Duplication



Testing - equipment / product



Plant Items - operable / maintainable



Instruments - sufficient for control / too many / correct location

Overview Guidewords



Operator Health



Environment



Electrical



Services



Materials of Construction



Non-routine Conditions - Start-up/ Shutdown / Maintenance / Cleaning /

Commissioning



Fire and Explosion



Safety Equipment



Quality and Consistency



Output - reliability and bottlenecks



Simplicity & Efficiency

2.4 R

ISK

R

ANKING

T

OOLS

The HAZOP Study was complemented with a formal risk ranking of each

scenario using Eraring Energy’s risk ranking tool (Ref 2) presented in Appendix

3. This is as per Eraring Energy’s requirements for risk reviews of their

projects.

3

R

ESULTS AND

R

ECOMMENDATIONS

3.1 P

RESENTATION OF

R

ISK

R

ESULTS

Items were recorded on the HAZOP Study Record Sheets, which may be seen

in Appendix 1. The 3.5 days HAZOP generated a total of 115 issues and

recommendations.

As per the methodology, entries were made on the record sheets as follows:



Where a hazard or an operational problem was recognised as requiring

further risk or operations controls;



Where the potential consequences of an incident were severe even

though the management of the risk considered acceptable.



Where a particular item was discussed in detail during the study and

hence required minuting to record the final outcome of these discussions.

HAZOPs are focussed on the engineering design of a particular plant or

equipment. Hence, trip, slip and fall type incidents were not recorded nor were

they discussed. These are better discussed in a Job Safety Assessment (or

similar) type forum.

The table in Appendix 1 shows the following columns:



Risk Number,



Guideword,



Causes,



Consequences



Controls in place (a listing of the controls currently in place and approved

as part of the present project),



Current risk rating (rating of the risk with the controls which are currently

in place or approved),



Mitigating actions (further risk reduction recommendations aiming to

reduce the risk to ALARP

levels),



Residual risk rating (the risk rating of the scenario with the recommended

mitigating actions (above) in place,

Below is provided a listing of Levels 4 and 4 risk scenarios as identified and

evaluated for the existing design. The resultant risk level once the

recommendations arising out of the HAZOP Study have been implemented is

also discussed for each scenario. The table in Section 3.5 below presents the

risk profile of the systems under study assuming all recommendations have

been implemented successfully.

3.2 R

ISK

L

EVELS OF THE

B

OILERS

D

ESIGN

Below are listed the risk scenarios for each Risk Level (as per Eraring Risk

definition) for the Boiler Design. These risk levels are as per current design

without

the additional risk reduction recommendations arising from the HAZOP

implemented.

3.2.1 Level 4 Risks Boilers

A. Risk of increased copper transportation (Scenario 5)

Increased copper transportation has largely got a financial effect to EE. Copper

would eventually carry-over through to turbine blades, reducing the efficiency of

the turbine operation and hence output capacity. It may cause flow restrictions

in superheater tubes and lead to a decreased life on low pressure heaters. The

copper transportation issue will require a change in the manner in which

maintenance is carried out on the superheaters and turbine rotors.

Current controls include ongoing routine copper transportation survey; a

Strategy Review which is being conducted on the merits of chemically cleaning

the superheaters versus foam clean of turbine; a review of the procedures for

boiler tube repairs have been reviewed; and new boiler chemical controls being

installed to reduce copper transportation from LP heaters.

Recommended additional controls are as follows:

Option a: Successful chemical clean carried out on super heaters which will be

carried out there-after as required need to review sliding pressure operation.

This would reduce the consequences of this event resulting in reducing the

overall risk level to a Level 3 risk.

Option b: Replacement of LP heaters to allow oxygenated treatment of the

boiler feed water. This would reduce the risk level to 1.

NB: Eraring Energy has engaged a contractor to complete superheater tube

cleaning commencing with unit four in November 2009.

B. Insufficient power supplies or access for operation during

construction (Scenarios 51 and 52)

Insufficient power supplies for construction purposes and insufficient access for

operations such as cranage due to other works (e.g. bottom ash hopper

crushing plant and boiler upgrade crane location) would lead to delays in

meeting program. The likelihood of such delays is seen as Very High leading to

a Level 4 risk.

It is recommended to place these risk scenarios on the Electrical Project Teams

(#51) and Site Operations Managers (#51 and #52) agenda. This would reduce

the risk to a Level 1 and Level 2 for scenarios 51 and 52 respectively.

3.2.2 Level 3 Risks Boilers

A. Flow accelerated corrosion due to increase in normal operational

flow (Scenario 1)

Flow accelerated corrosion (FAC) is a temperature dependent corrosion

mechanism normally occurring after a bend or in a straight pipe after a flow

disturbance e.g. thermocouple probe, orifice plate etc. It may lead to pipe

failure and loss of containment of high pressure water, injury from burns,

possible fatalities. Existing controls are confirmation of adequate thickness of

piping etc. (thickness survey already conducted); planned thickness surveys 4

years after start up and the fact that there is no change in geometry as a result

of the project.

Further recommendations are to determine high risk areas in terms of FAC and

to perform thickness survey at targeted areas at first Combined Maintenance

Outage Program (CMOP

) outage on units 4 and 2 and correlate to the duration

above the original design flow. It is also recommended to record the extent of

flow above the original design (for use in thickness survey mentioned above)

and to confirm that FAC study by contractor has been completed and is valid for

current design.

Implementation of these recommendations would reduce the likelihood from a

Moderate to a Low. It would however not reduce the overall risk rating, which

remains a Level 3 risk due to the relatively High consequence rating.

B. Failure of new pressure parts (Scenarios 7, 15, 19, 26, 50)

Failure of new pressure parts for a number of reasons may lead to pipe failure

and loss of containment of high pressure steam / water, injury from burns, and

possible fatalities.

Current and approved controls include the fact that the design and construction

will adhere to Australian Standards including inspection; 100% radiography on

all site tube welds; all other site welds to be NDT in compliance with Australian

Standards; testing, including Non Destructive Testing (NDT); Asset Strategy

defined field test for creep life of welds.

Provided that these controls are successfully implemented and maintained the

team concluded that the risk of these scenarios are

As Low As Reasonably

2

Practicable

(ALARP) and no further risk control measures were identified. The

risk scenarios remain however at Level 3 risk due to the relatively High

consequence should they occur even though the likelihood is considered as low

as reasonably practicable.

C. Increased

maximum

flow

exceeds

maximum

capacity

of

superheater safety valves (Scenario 14)

An increase in the maximum flow may exceed the maximum relieving capacity

of superheater safety valves. This would result in over pressurisation of the

superheater leading to pipe failure and loss of containment of high pressure

water, injury from burns, possible fatalities.

Current controls include the review carried out by contractors in this regards

which provides advice on the safe operation of safety valves.

Recommendations are to establish actual flows for overload and revise plant

control limits if necessary and to include (in the amended plant operating

manuals) the established plant limitation. This would have the effect of

minimising the likelihood of this event. However, due to the relatively High

consequence of the scenario the risk level remains 3.

NB: Review of flow rates from boiler designer indicates that operation to 750

MW will be achievable with installed safety valves. It is not expected that safety

valve replacement will be required however it will be assessed post upgrade.

D. Increase of velocities (Scenario 36)

Boiler operation at higher loads increases average flue gas velocity which

increases grit erosion. This could lead to tube failures and reduced boiler tube

life and would increase maintenance/costs.

Current and approved controls include Combined Maintenance Outage

Program (CMOP) inspections and shielding, as identified in surveys for current

known high wear area; existing baffling along the wall sections; and acoustic

detectors to minimise damage in the event of a failure. Further, tube wall

thickness design takes into account exposure to erosion and new economiser

panels have all bends enclosed out of gas flow.

Further recommendations from the HAZOP are for the design process to

evaluate the need for baffling, shielding and soot blower locations in primary

superheater and Reheater backpasses; the review to include rear wall

penetration and seal boxes as now in an area of historical high risk. Prior to

warranty expiration (12 months) take unit out of service for grit erosion survey

on new design items; cold air flow testing and smoke bombs to identify high

velocity areas and record high flow areas for targeted inspection - adjust baffling

or shielding as required; perform inspections on previously un exposed areas

while elements are removed during upgrade; and modify the boiler strategy to

reflect concerns and learnings from inspections.

Provided these recommendations are implemented the risk level of this

scenario is reduced to a Level 2.

E. Higher gas temperatures in the backpass (superheater and

Reheater passes) (Scenario 42)

Higher flue gas temperatures after the air heater exit and attemperation point

will cause fabric filter bag failures due to excessive shrinkage. This could lead

to cell isolations and potential breach of the environmental licence if EPS load

not reduced. The failure may require long time to implement repairs if a stock

holding of replacement bags is not available due to long lead time (3-6 months)

on bags.

The risk exposure exists until 2015 when all PAN filter bags would have been

replaced. Currently EPS has excellent bag life with 6 to 7 year bag replacement

cycle.

Current and approved safeguards are using experience with this potential risk

(which exists also in the existing plant); the new attemperating air system which

initiates at 125 deg C, a High Alarm at 135 deg C and a High High Alarm at 140

deg C - for load reduction. Boiler flue gas design brief is 135 deg C at air

heater exit at 720 MW with a 32 degree ambient air temperature. Fabric filter

bag supply contract requires 8 cells of bags on site

Further recommendation are for documentation to be produced to implement an

operating limit of 135 deg C to manage bag life, with a nominal operating target

of less than 130 deg C; adjustment of operating limit down on subsequent units

if rapid multi cell failures occur; evaluating the need of attemperating air spray

system if operating need exists; stock holding costs versus risk to be assessed;

and investigation of stock holding limits with contracted supplier.

If the recommendation above are implemented the risk is reduced to a Level 2

(possibly to a Level 1 depending on the rigour of implementation).

F. Poor Access To Bottom Bank Reheater Tubes (Scenario 46)

Poor access to bottom bank Reheater tubes may mean that in the event of a

tube failure the outage may need to be extended to gain access to carry out

repairs.

There are currently no controls for this scenario (apart from a trained workforce

with adequate operating procedures and PPE).

Recommendation is if for a review to achieve workable access for maintenance.

Provided this is workable access is achieved adequately the risk of this scenario

is reduced to a Level 2.

G. Change in boiler components (Scenario 53)

Change in boiler components would result in change in load distribution.

Currently structural review is being undertaken by contractor which also

includes earthquake and wind load code compliance. Further action is to

ensure that action resulting from design study to reflect latest Australian

Standards and Codes. This would result in a Level 1 risk scenario.

H. Changes to existing job sheets for boiler start up and shut down

(Scenario 56 and 57)

Changes to existing job sheets for boiler start up and shut down leading to plant

damage or injury. Current controls are that boiler project team work scope

includes procedural review. A tight control of the completion of plant

modification process would result in a Level 1 risk.

3.2.3 Level 2 and Level 1 Risks Boilers

There are a number Level 2 and Level 1 risks that were identified. These are

detailed in Appendix 1.

3.3 R

ISK

L

EVELS OF THE

T

URBINE

H

YDRAULIC

P

OWER

U

NIT

D

ESIGN

3.3.1 Level 4 Risks Hydraulic Power Unit

There are not Level 4 risks identified.

3.3.2 Level 3 Risks Hydraulic Power Unit

A. Removal of Pump MRP

Removal of Pump MRP causes Safety issue with 11MPa. Current controls are

primary isolation valve and the pressure gauge.

Recommended further controls are to ensure positive isolation to allow stand-by

pump removal and to ensure the main isolation valves can be locked out.

Provided these recommendations are implemented the risk level for this

scenario is reduced to a Level 2 risk.

B. Impact on fluid trip drain from valves back to tank causes pinching

Impact on fluid trip drain from valves back to tank causes pinching resulting in

an inability to trip turbine. This may, in adverse operating conditions, cause a

burst of drain pipe over 1.4MPa with injury potential to personnel from high

pressure event.

Current and approved controls are the appropriate layout of piping (very short

pipe) and protection of pipe between structures.

Further recommendations are to review the layout of drainpipe to rule out

impact; consult with contractor as to implications of a blocked drain line on

operation; and to ensure EE field surveillance officer approves pipe line layout

with attention to mechanical damage and weld inspection. The target is to

ensure that this scenario becomes incredible.

3.3.3 Level 2 and Level 1 Risks Hydraulic Power Unit

There are a number Level 2 and Level 1 risks that were identified. These are

detailed in Appendix 1.

3.4 R

ISK

L

EVELS OF THE

L

OW

NO

B

URNER

D

ESIGN

3.4.1 Level 4 Risks Low NO

Burners

There are not Level 4 risks identified.

3.4.2 Level 3 Risks Low NO

Burners

A. Pressure controller has been disabled or the Atomising air pressure

is high (Scenario 12)

If the pressure controller has been disabled or the atomising air pressure is high

while atomising air to the ignitor it is possible for the unit to fail to ignite causing

an operational upset and loss of power generation. Note that this is not a safety

concern.

It is recommended to review air pressure requirements with designers and

respond appropriately. This would reduce the risk of this scenario to a Level 2.

B. Inability to remove oil gun and spark rod on D level (Scenario 13)

New burner layout may result in an inability to remove oil gun and spark rod on

D level.

Provided the design change to relocate oil gun to allow removal this scenario is

reduced to a Level 1 risk.

3.4.3 Level 2 and Level Low NO

Burners

There are a number Level 2 and Level 1 risks that were identified. These are

detailed in Appendix 1.

3.5 R

ISK

P

ROFILE

The risk profile of the part of the plant assessed, assuming that the risk

reduction measures recommended during the HAZOP Studies are all

implemented successfully, is as follows:

Table 1 – Levels of Risk With HAZOP Recommendations Implemented

Risk Level

Risk Scenario

Boilers

Level 4

No scenarios identified remain at Level 4

Level 3

FAC due to increase in normal operational flow (scenario 1)

Financial effect only: Risk of increased copper transportation

(scenario 5). Reduced to a Level 1 based on feasibility study.

Failure of new pressure parts (scenario 7, 15, 19, 26, 50)

Increased maximum flow exceeds maximum capacity of

superheater safety valves (Scenario 14). Reduced to a Level 1

based on commissioning data and plant control settings.

Level 2

Detailed in HAZOP Minute sheets in Appendix 1

Level 1

Detailed in HAZOP Minute sheets in Appendix 1

Turbine Hydraulic Power Unit

Level 4

No scenarios identified remain at Level 4

Level 3

No scenarios identified remain at Level 3

Level 2

Detailed in HAZOP Minute sheets in Appendix 1

Level 1

Detailed in HAZOP Minute sheets in Appendix 1

Low NO

Burners

Level 4

No scenarios identified remain at Level 4

Level 3

No scenarios identified remain at Level 3

Level 2

Detailed in HAZOP Minute sheets in Appendix 1

4

C

ONCLUSION

The formal HAZOP review process for major project

is part of EE’s multilevel

risk management strategy and represents a clear commitment by EE as to the

management of risks for the business and for safety, health and environment.

This type of process allows for input by a number of experienced and senior

representatives from operations, design, maintenance, safety etc. at a defined

number of stages throughout the life of the project, from early conception

through to detailed design and to final operation.

It provides an opportunity for a multidisciplinary team to formally review a

proposal and to use their experience and corporate memory to improve this

proposal and wherever possible avoid any repeat of errors or issues that may

have occurred in the past.

The team that took part in the HAZOP reviews which are presented in the

present report participated freely and with a high degree of expertise.

This is apparent from the results from these HAZOP Study reviews which

provides for a solid understanding as to the risks associated with the projects.

c:\erapow\12-b177\HAZOP Report Upgrade Project Rev B.Doc Revision B 14 July, 2009 A1.1

HAZOP Study Report Of The Turbine Hydraulic Power Unit, Boiler Upgrade And Low Nox Burners As Part Of The Eraring Energy Power Station Upgrade Project

Appendix 1

HAZOP Minutes



Burner HAZOP



Turbine Hydraulic Power HAZOP



Low NO

x

Burner HAZOP

HAZOP Study Report of the Turbine Hydraulic

Power Unit, Boiler Upgrade and Low NOx Burners

as Part of the Eraring Energy Power Station

Upgrade Project

BOILER HAZOP

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng 1 General - -

Line: Feedwater from economiser inlet through to drum and furnace.

2 High Flow FAC due to increase in normal

operational flow.

May lead to pipe failure and loss of containment of high pressure water, injury from burns, possible fatalities

Thickness survey already conducted. Planned thickness survey 4 years after start up,

No change in geometry

4 2 3 a. Determine high risk areas in terms of FAC. Perform Thickness survey at targeted areas at first CMOP outage on units 4 and 2 and correlate to duration above original design flow.

b. Record the extent of flow above original design (for use in thickness survey mentioned in action 1a above)

c. Confirm that FAC study by CW has been completed and is valid for current design.

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng

3 High Flow Inability of drum to effectively separate water from steam at higher flow rates of upgraded design.

If drum unable to effectively separate water form steam, the possibility of carryover of water to superheater. Deposition of chemicals and erosion of turbine blades

Design 2 2 2 Perform carry over test at commissioning of unit 4 and if carryover found engineer out (i.e. replacement separators)

1 1 1

4 High Flow Increased maximum flow exceeds maximum capacity of drum safety valves. Over pressurisation of drum may cause failure. May lead to pipe failure and loss of containment of high pressure water, injury from burns, possible fatalities.

Design review carried out by Connell Wagner and the safety valves on the drum have been confirmed to be adequate. (10% margin above 750MW flow rate.) With this safeguard in place this scenario has

effectively been eliminated.

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng 5 High Pressure Risk of increased copper transportation Eventually carry-over of copper through to turbine blades. Copper affects the efficiency of the turbine and may cause blockage in superheater tubes. The copper

transportation issue will also require a change in manner of which maintenance is carried out on superheaters. Decrease life on LP heaters. Ongoing routine copper transportation survey.

Strategy Review being conducted on merits of chemically cleaning the superheaters versus foam clean of turbine.

Procedures for boiler tube repairs have been reviewed.

New boiler chemical controls are being installed to reduce copper transportation from LP heaters. Improved start up and shut down procedures.

4 4 4 a. Successful chemical clean carried out on super heaters and turbine. Carry out routinely if cannot stop copper transportation. brevier sliding pressure characteristic.

c. Replacement of LP heaters to allow

oxygenated treatment (this option is being considered).

2 1 4 1 3 1

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng

6 Low Flow Imbalance of flow between front and back pass

economisers

Flow may be too low in front pass

encroaching in steaming margin. May cause pipe damage and level stability issues in drum (so called drum swell). Mixing at T-piece may be unstable.

Design review carried out. Regular operational inspections to confirm design review outcomes. Hazard warning through noise. 1 1 1 Install thermocouples on each outlet header of economisers.

1 1 1

7 Low Flow Failure of new pressure parts

May lead to pipe failure and loss of containment of high pressure water, injury from burns, possible fatalities.

Design and constructed to standards including inspection, testing and NDT.

4 1 3 No further action identified. 4 1 3

8 Low Temperature Design will lower economiser duty by 35% Lowering of the feedwater temperature to the drum which leads to higher gas flows and increased risk of erosion.

Parameters have been given to designers as part of design scope and outcomes have been reviewed and accepted by Eraring.

1 1 1 No further action identified. 1 1 1

9 Impurities Construction debris left in system. Blockages, tube starvation and failure. Financial effect. Impact on human Safety low.

Construction

methodology including flush processes. Visual inspections, ITP's

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng 10 Reaction Cooler temperatures in economiser Possible reduced effectiveness of chemical dosing regime (particularly at start up) Tube samples at outages. Continuous chemical monitoring. Upgrade of Chemical Control Room (CCR) with respect to instrumentation. 1 2 1 Issue to be reviewed by Chemical Team. 1 1 1

11 Operability New operating parameters

Potential mal operation impacting life and viability of equipment.

Training requirements 1 2 1 New performance data sheets to be compiled. 1 1 1 12 Operability/ maintaina-bility Obstruction to galleries from new economiser feed pipe to drum.

Poor access around and into boiler

Ensure adequate access around boiler

1 1 1 No further action identified. 1 1 1

13 Instrumenta-tion inadequate information of plant condition Failure to understand plant condition Existing instrumentation will be a guide to

requirements for new equipment.

1 1 1 Refer to action No.6 w.r.t. thermocouples

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng

Line: Steam from the Heat Recovery Area outlet header through the Superheaters to the Main Steam Outlet

14 High Flow Increased maximum flow exceeds maximum capacity of superheater safety valves. Over pressurisation of superheater may cause failure. May lead to pipe failure and loss of

containment of high pressure water, injury from burns, possible fatalities.

Designer review carried out by CW. Relieving capacity reduced from IHI design of 155.6 to 139.4 kg/s. Minimum Aust Standard code requirements (20% of steam flow relieving) equates to max steam flow rate of 695kg/s, hence steady state 750MW flow

conditions of 624kg/s within this margin. Original design assessment allowed for discharging 25% of steam flow rate through superheaters and under this basis 622 kg/s is maximum steam flow under original IHI design or 557 kg/s under revised CW capacity.

4 2 3 a. Establish actual flows at commissioning for overload and revise plant limits if necessary

b. Plant limitation to be included in amended plant operating manuals.

c. Based on findings in (a) determine need to install larger size safety valves to allow achievement of additional overload above 633 kg/sec (being 22% of the revised CW relieving capacity). 4 1 1 1 3 1

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng

15 Low Flow Failure of new pressure parts

May lead to pipe failure and loss of containment of high pressure water, injury from burns, possible fatalities.

Design and constructed to standards including inspection, testing and NDT.

4 1 3 No further action identified. 4 1 3

16 High Temperature Higher steam temperatures resulting in more frequent use of spray water

Potential for thermal fatigue failure of spray water system

Original design and material selection. 12-yearly inspections of spray water systems.

3 2 2 Increase frequency of inspections of spray water system (currently 12-yearly). 3 1 2 17 High Temperature Insufficient capacity of spray water to control superheater steam temperatures. Accelerated creep life usage. Material Failure. Design parameter reviewed and accepted by Eraring Energy. Metal temperature operational limits and alarms (except SSH).

1 1 1 No further action identified. 1 1 1

18 High Temperature Accelerated creep life consumption of headers Reduced life of headers Software system to monitor header life (ODAS).

Field testing -

replication of headers

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng 19 High Temperature Reduced creep life of welds

Pressure part weld failure. Loss of containment of steam internal of boiler, could be external to boiler. Burns.

Asset Strategy defined field test for creep life of welds

4 1 3 No further action identified. 4 1 3

20 High Temperature Burner replacement Higher or lower temperatures To be covered in burner HAZOP - - - To be covered in burner HAZOP - - - 21 High Temperature Increased primary superheater surface area Higher steam temperature for stages 1,2 and 3 resulting in higher metal temperatures causing metallurgical failure.

Design review has indicated that

materials are suitable for duty

1 1 1 No further action identified. 1 1 1

22 Impurities Increased flow rate increases demand on polishing plant, particularly during periods of salt leaks

Salt leak tolerance reduced due to lack of polishing plant capacity. Load reduction, boiler damage Reduce load as operating procedure. Polishing plant capacity review is carried out by CW

1 3 2 a. Implement actions from CW review on polishing plant capacity.

OR

b. Review the turbine condenser life strategy

1 1 1 1 1 1

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng 23 Impurities Increased exfoliation of internal stable oxide layer due to the increase flow rate and heat fluxes

Blocked super heater tubes or solid particle erosion of HP turbine

Not an issue at current operating conditions.

2 2 2 Desk top review of

superheater metallurgy and susceptibility to the phenomena 2 1 1 24 Instrumentati on Inadequate information of plant condition Failure to understand plant condition

TBA 1 1 1 Review instrumentation when it becomes available from designers

1 1 1

Line: Steam from superheater outlet valve through the Reheater to IP Turbine

25 High Flow Increased maximum flow exceeds maximum capacity of Reheater safety valves. Over pressurisation of Reheater may cause failure. See No. 1 above.

Design review carried out and confirmed. Maximum Reheater flowrate of 646kg/s for existing safety valves. Hence superheater safety valves are the first high flow limitation with respect to boiler safety valves.

1 1 1 No further action identified. 1 1 1

High Flow Increased design flow and additional surface area increases DP across the Reheater Reduced IP turbine inlet pressure which may lead to reduced output

Boiler turbine matching review completed with outcome for boiler designer to advise of Reheater DP

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp

ac t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp ac t Lik elih oo d R aw R isk R ati ng

26 Low Flow Failure of new pressure parts

May lead to pipe failure and loss of containment of high pressure water, injury from burns, possible fatalities.

Design and constructed to standards including inspection, testing and NDT.

4 1 3 No further action identified. 4 1 3

27 High Temperature Increased surface area enabling Reheater to exceed design temperatures Metallurgical failure of tubing resulting in loss of generation and revenue. Reduced Creep life on hot Reheater header.

Temperature control with back pass dampers. ODAS system for creep life monitoring. Field replications as per strategy.

Note: Existing spray water is

decommissioned

2 2 2 Implement alarms on hot reheat steam outlet temperature. Implement appropriate training. 2 1 1 28 High Temperature Tube failure of hot Reheater elements due to achieving design temperatures

Tube failure unit out of service, loss of revenue

Material review carried out by designers

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp_ac

t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp_ac t Lik elih oo d Ta rg et R ati ng

Line: Furnace Area/gas side - from Ash hopper throat to furnace rear wall screen tubes.

29 High Flow Increased firing Increased gas flow causing increased vibration/movement on superheater pendants leading to tube failure. Outage inspections/condition monitoring, acoustic detectors will limit the impact.

2 2 2 No further actions 2 2 2

30 High Flow No erosion issues identified

- - - No further actions - - - 31 High Pressure Upgrade not

affecting existing

- - - No further actions - - -

32 Low Pressure Upgrade not affecting existing - - - No further actions - - - 33 High Temperature Refer to Low NOx Burner HAZOP Slagging No further actions

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp_ac

t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp_ac t Lik elih oo d Ta rg et R ati ng 34 High Temperature Increased time at higher metal temperatures on superheaters. Increased rate of creep life consumption requiring early replacement.

CMOP inspection for gap between pendants and nose

1 1 1 Furnace flue gas temperature measurements to confirm design expectations. Consider metal temperature instrumentation on SSH if flue gas temperatures high. 1 1 1 35 High Temperature Increased temperatures on superheaters leading to increased metal temperatures Increased rate of creep life consumption requiring early replacement.

CMOP inspection for gap between pendants and nose

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp_ac

t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp_ac t Lik elih oo d Ta rg et R ati ng

Line: Backpass (superheater and Reheater passes)

36 High Flow Overall average velocity increases with reduced bias from front to rear pass - specifically higher flow in the superheater compared to previously. High flow causes grit erosion Tube failures, increased maintenance/costs, shorter life

CMOP inspections and shielding as identified in surveys for current known high wear areas.

Existing baffling along the wall sections. Acoustic detectors to minimise damage in the event of a failure. Tube wall thickness design takes into account exposure to erosion. New economiser panels have all bends enclosed out of gas flow.

3 3 3 a) Design process to consider baffling,

shielding and soot blower locations in primary superheater and Reheater.

b) Review to include rear wall penetration and seal boxes as now in an area of historical high risk. c) Prior to warranty expiration (12 months) take unit out of service for grit erosion survey on new design items.

d) Cold air flow testing and smoke bombs to identify high velocity areas and record high flow areas for targeted inspection - adjust baffling or shielding as required. e) Perform inspections on previously un exposed areas while elements are removed during upgrade. f) Modify the boiler strategy to reflect concerns and learnings from inspections.

No Guide Word Causes Consequences Safeguards (Existing and Approved) Imp_ac

t Lik elih oo d R aw R isk R ati ng Further Mitigating Actions Imp_ac t Lik elih oo d Ta rg et R ati ng

37 High Flow Overall average velocity increases with reduced bias from front to rear pass - specifically higher flow in the superheater compared to previously. High flow causes grit erosion Possible increased grit erosion on dampers, with increased maintenance costs - damper failure loss of temperature control

CMOP inspections to confirm if problem has increased from current

1 1 1 Inspect at 12 month warranty survey

1 1 1

38 Low Pressure Higher DP across finned economiser.

ID fan capacity margin is reduced which may lead to forced load limitation particularly in summer.

Soot Blowing 2 2 2 Review ID fan cut back set point with regards to the risk of duct implosion limits.

2 1 1

39 Low Pressure Higher DP across finned economiser.

More soot blowing to control dust build up in finn tubes, potentially causing higher rates of soot blower steam erosion on tubes leading to tube failure.

Shield soot blower steam impact areas.