Large Rehabilitation ProjectsLarge Rehabilitation Projects ...e2010.drustvo-termicara.com/resources/files/presentations/spalding.pdf · Large Rehabilitation ProjectsLarge Rehabilitation

Large Rehabilitation ProjectsLarge Rehabilitation ProjectsCase Study fromNikola Tesla ‘A’, Serbia.

D Spalding and J Beaton

Power Plants 2010, Serbia

Nikola Tesla A4 – A6 Boiler Rehabilitations

Doosan Power Systems have participated in the rehabilitation of the boilers on units A4, A5 & A6.

Unit Year Role Description Funded by

Unit A5 2004 Main Contractor Full boiler island rehabilitation EAR

Unit A4 2007 Main Contractor Boiler pressure parts, steam lines EPSand ancillaries, chemical clean & steam blow& steam blow.

Unit A6 2008 Main Contractor Boiler pressure parts & ancillaries EPS

Unit A6 2010 Main Contractor Boiler pressure parts & ancillaries EPSchemical clean & steam blow.

Power Plants 2010, Serbia 1


Nikola Tesla Boilers Units A3 – A5

• Benson type once through lignite fired tower boiler with spiral furnace and steam flow of 920 T /H (305MW )920 Tonnes/Hour (305MWe).

• Supplied by SES Tlmace Slovakia.

Nikola Tesla Unit A6Nikola Tesla Unit A6

• Sulzer type once through lignite fired tower boiler with vertical tube furnace and steam flow of 930 Tonnes/hour (308MWe)of 930 Tonnes/hour (308MWe).

• Supplied by Rafako Poland.



Units A3 – A6 History and Condition (Prior to Rehabilitation)

• Units A3 – A6 were commissioned between 1976 and 1979.

• No major investment for many yearsNo major investment for many years.

• Boiler tube degradation due to off-line corrosion.

• Suffering reduced output and large efficiency lossesand forced outages

• All units in need of major rehabilitation• All units in need of major rehabilitation.



UNIT A5 Rehabilitation

• Works split into 3 main lots, Boiler Island, Turbine Island and E,C&I.• Project funded by the European Agency for Reconstruction (EAR).• Project management by TENT and Vattenfall Powerconsult

• DPS awarded Boiler Island in March 2004 after international competitive tender• DPS awarded Boiler Island in March 2004 after international competitive tender.• Remarkable outage programme of 270 days to synchronisation achieved.• Over 750,000 manhours expended on Boiler Island Works.• 44,600 site butt welds with weld repair rate < 2%., p



UNIT A5 W kUNIT A5 Workscope

• 1000 tonnes of pressure parts to replace.• 44 600 site butt welds to complete• 44,600 site butt welds to complete.• HP & IP Steam lines to replace• New Atomising steam fuel oil system• New sootblowing system• Coal and Ash plant refurbishment• Draught plant refurbishment.• Coal mill refurbishment.• Boiler Valves and damper replacemento e a es a d da pe ep ace e t• Insulation and refractory replacement• Chemical clean and steam blow.


Local Laydown Area Allowed Efficient Stockpiling, Smooth Movement and Pre-Assembly of Pressure Parts.


Temporary Support Structures Developed for Lower Furnace Removal

Lower Furnace Structural supports tied back to the Upper Furnace and

Roof allowed safe removal of


Roof allowed safe removal of Evaporator Tubing

Furnace Removed from the Hopper to 56m level


Replacement Superheater Elements Lifting Process

Runway Beam usedRunway Beam usedto accelerate liftingprocess


Transition Panel Datum Position Critical Phase in Furnace Re-tube


The upper furnace walls and superheater elements can then be installed


The lower furnace follows - 1


The lower furnace follows - 2

Replacement of furnace sidewalls


Use of hand welded corner tubes in-situ to accelerate replacement of evaporator walls


Coal Burner Panel Replacement


Rehabilitation of the Economiser Outlet Flue to the Chimney


Before After

Rehabilitation of the Heavy Fuel Oil handling System and Burners

New HFO Pumps Installed New Atomising Fuel Oil


New Atomising Fuel Oil Burners

Rehabilitation of the Lignite Beater Mills During Furnace Modernisation

I t ll ti f Mill C i d Mill i t l


Installation of Mill Casing and Mill internals


UNIT A4 Rehabilitation

• Works split into a greater number of lots, with more local contractors directly engaged by TENTTENT.

• Project funded by Elektroprivreda Srbija (EPS).• Project management by TENT.

• DPS awarded Boiler Island in March 2007 after international competitive tender.• Greater intensity of pressure part works. 54,000 site butt welds.• Hydraulic test achieved in just 28 weeks from commencement.• Weld repair rate maintained at a remarkable level of just 2%.



UNIT A4 Workscope

• 1700 tonnes of pressure parts to replace.• 54,000 site butt welds to complete.• HP & IP Steam lines to replace• Ash plant refurbishment• Boiler Valves and damper replacement• Boiler Valves and damper replacement• Insulation replacement• Chemical clean and steam blow.


A4 Lessons Learned – Hopper Removed Last to Improve Safety


A4 Steamlines being lifted into place


Hopper Pre-assembly to Accelerate Programme Completion


A4 Job Nearly Done! - Steam Blow after the Chemical Clean

Mov03679.mpg



Unit A6 Rehabilitation 434 element/panel lifts through a narrow boiler furnaceopening with afterburner

• Works carried out in 2 phases,– 2008– 2010.

opening with afterburnergrates in place.

• Upgrade of unit output to 348MWe• Replacement of virtually all boiler pressure

parts.• Very challenging programmes inVery challenging programmes in,

– 2008 only 189 days to completion and– 2010 only 203 days.

• Detailed planning and lifting studies iti l t hi th 2008critical to achieve the 2008 programme.

A clever lifting solution was developed



UNIT A6 Workscope – Phase 1 - 2008

• 1057 Tonnes of pressure parts and26 000 it b tt ld i l di26,000 site butt welds including

• Upper Furnace Front & Rear Walls• Superheater 1

R h t 1• Reheater 1• Triflux Elements• Superheater 2

R h t 2• Reheater 2• Superheater 4• Superheater 5


A6 Rehabilitation Phase 1 - Limited to above the 47.5m Level


A6 Rehabilitation Phase 1 - Superheaters and Reheaters Being Lifted into Place



UNIT A6 W k Ph 2 2010UNIT A6 Workscope – Phase 2 – 2010

• 1038 tonnes of pressure parts with 17,500site butt welds includingg

• Upper Furnace side walls• Superheater 3• Evaporator• Economiser• Afterburner Grates Renewal• Chemical Clean and steam blow


A6 Rehabilitation Phase 2 – Replacement of Membrane Walls and wall superheater below 47.5m Level


A6 Rehabilitation Phase 2 – Positioning of Wall Superheater


Nikola Tesla A4 – A6 Boiler Rehabilitations - Achievements

• A remarkable series of Major Boiler Rehabilitations where all key j yprogramme milestones were achieved.

• Despite the pace at which the works were carried out strong project management ensured very high Quality Assurance levels.

• Strong on-site management and decision making enabled continuous progress.

• A strong client contractor relationship was developed which ensured rapid on site dispute resolutionrapid on-site dispute resolution.

• Great cooperation with sub-contractors resulted in eliminating potential delays.

• The contract model evolved from a full boiler island rehabilitation on A5• The contract model evolved from a full boiler island rehabilitation on A5 to a highly customised workscope on A6.

• This allowed TENT to secure greater value by sub-contracting lower risk activities and DPS to focus on core boiler works


Conclusions

• Units A5, A4 and A6 boilers were successfully rehabilitated meeting all programme and technical requirements.

• Completion to programme allowed EPS to continue to supply electricity to theCompletion to programme allowed EPS to continue to supply electricity to the region and minimise energy imports over the winter months.

• Even though the scope of work on each project was extensive,exceptional quality standards were achieved,Th b il k l t d i ll l t i ifi t k th b l• The boiler works were completed in parallel to significant works on the balance of plant and turbine while the other units remained operational

• Full engagement with the local supply chain and solving problems directly with the client and the client’s advisor were critical to success.

• Effective application of a full range of project management skills was demonstrated at all levels from site and supplier management through to client relationships.


Acknowledgements

Doosan Babcock would like to acknowledge and thank EPS/TENT, Vattenfall Powerconsult and all our partners for their support in

making Nikola Tesla A4 to A6 units such exemplary large h bilit ti j trehabilitation projects.


Thank You – Any Questions?

Douglas [email protected]

+44 7767 290015Power Plants 2010, Serbia

44 7767 290015

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Large Rehabilitation ProjectsLarge Rehabilitation Projects ...e2010.drustvo-termicara.com/resources/files/presentations/spalding.pdf · Large Rehabilitation ProjectsLarge Rehabilitation