Case Study from Nikola Tesla A, Serbia.

Transcription

1 Large Rehabilitation Projects Case Study from Nikola Tesla A, Serbia. D Spalding and J Beaton Power Plants 2010, Serbia

2 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 A Main Contractor Full boiler island rehabilitation EAR Unit A Main Contractor Boiler pressure parts, steam lines EPS and ancillaries, chemical clean & steam blow. Unit A Main Contractor Boiler pressure parts & ancillaries EPS Unit A Main Contractor Boiler pressure parts & ancillaries EPS chemical clean & steam blow. Power Plants 2010, Serbia 1

3 Nikola Tesla A4 A6 Boiler Rehabilitations Nikola Tesla Boilers Units A3 A5 Benson type once through lignite fired tower boiler with spiral furnace and steam flow of 920 Tonnes/Hour (305MWe). Supplied by SES Tlmace Slovakia. Nikola Tesla Unit A6 Sulzer type once through lignite fired tower boiler with vertical tube furnace and steam flow of 930 Tonnes/hour (308MWe). Supplied by Rafako Poland. Power Plants 2010, Serbia 2

4 Nikola Tesla A4 A6 Boiler Rehabilitations Units A3 A6 History and Condition (Prior to Rehabilitation) Units A3 A6 were commissioned between 1976 and No major investment for many years. Boiler tube degradation due to off-line corrosion. Suffering reduced output and large efficiency losses and forced outages All units in need of major rehabilitation. Power Plants 2010, Serbia 3

5 Nikola Tesla A4 A6 Boiler Rehabilitations 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. 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%. Power Plants 2010, Serbia 4

6 Nikola Tesla A4 A6 Boiler Rehabilitations UNIT A5 Workscope 1000 tonnes of pressure parts to replace. 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 oe Valves esadda and damper replacement epace et Insulation and refractory replacement Chemical clean and steam blow. Power Plants 2010, Serbia 5

7 Local Laydown Area Allowed Efficient Stockpiling, Smooth Movement and Pre-Assembly of Pressure Parts. Power Plants 2010, Serbia 6

8 Temporary Support Structures Developed for Lower Furnace Removal Lower Furnace Structural supports tied back to the Upper Furnace and Roof allowed safe removal of Evaporator Tubing Power Plants 2010, Serbia 7

9 Furnace Removed from the Hopper to 56m level Power Plants 2010, Serbia 8

10 Replacement Superheater Elements Lifting Process Runway Beam used to accelerate lifting process Power Plants 2010, Serbia 9

11 Transition Panel Datum Position Critical Phase in Furnace Re-tube Power Plants 2010, Serbia 10

12 The upper furnace walls and superheater elements can then be installed Power Plants 2010, Serbia 11

13 The lower furnace follows - 1 Power Plants 2010, Serbia 12

14 The lower furnace follows - 2 Replacement of furnace sidewalls Power Plants 2010, Serbia 13

15 Use of hand welded corner tubes in-situ to accelerate replacement of evaporator walls Power Plants 2010, Serbia 14

16 Coal Burner Panel Replacement Power Plants 2010, Serbia 15

17 Rehabilitation of the Economiser Outlet Flue to the Chimney Before After Power Plants 2010, Serbia 16

18 Rehabilitation of the Heavy Fuel Oil handling System and Burners New HFO Pumps Installed New Atomising Fuel Oil Burners Power Plants 2010, Serbia 17

19 Rehabilitation of the Lignite Beater Mills During Furnace Modernisation Installation ti of Mill Casing and Mill internals Power Plants 2010, Serbia 18

20 Nikola Tesla A4 A6 Boiler Rehabilitations UNIT A4 Rehabilitation Works split into a greater number of lots, with more local contractors directly engaged by TENT. 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%. Power Plants 2010, Serbia 19

21 Nikola Tesla A4 A6 Boiler Rehabilitations 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 Insulation replacement Chemical clean and steam blow. Power Plants 2010, Serbia 20

22 A4 Lessons Learned Hopper Removed Last to Improve Safety Power Plants 2010, Serbia 21

23 A4 Steamlines being lifted into place Power Plants 2010, Serbia 22

24 Hopper Pre-assembly to Accelerate Programme Completion Power Plants 2010, Serbia 23

25 A4 Job Nearly Done! - Steam Blow after the Chemical Clean Mov03679.mpg Power Plants 2010, Serbia 24

26 Nikola Tesla A4 A6 Boiler Rehabilitations Unit A6 Rehabilitation Works carried out in 2 phases, Upgrade of unit output to 348MWe Replacement of virtually all boiler pressure parts. Very challenging programmes in, 2008 only 189 days to completion and 2010 only 203 days. Detailed planning and lifting studies critical to achieve the 2008 programme. 434 element/panel lifts through a narrow boiler furnace opening with afterburner grates in place. A clever lifting solution was developed Power Plants 2010, Serbia 25

27 Nikola Tesla A4 A6 Boiler Rehabilitations UNIT A6 Workscope Phase Tonnes of pressure parts and 26,000 site butt welds including Upper Furnace Front & Rear Walls Superheater 1 Reheater 1 Triflux Elements Superheater 2 Reheater 2 Superheater 4 Superheater 5 Power Plants 2010, Serbia 26

28 A6 Rehabilitation Phase 1 - Limited to above the 47.5m Level Power Plants 2010, Serbia 27

29 A6 Rehabilitation Phase 1 - Superheaters and Reheaters Being Lifted into Place Power Plants 2010, Serbia 28

30 Nikola Tesla A4 A6 Boiler Rehabilitations UNIT A6 Workscope Phase tonnes of pressure parts with 17,500 site butt welds including Upper Furnace side walls Superheater 3 Evaporator Economiser Afterburner Grates Renewal Chemical Clean and steam blow Power Plants 2010, Serbia 29

31 A6 Rehabilitation Phase 2 Replacement of Membrane Walls and wall superheater below 47.5m Level Power Plants 2010, Serbia 30

32 A6 Rehabilitation Phase 2 Positioning of Wall Superheater Power Plants 2010, Serbia 31

33 Nikola Tesla A4 A6 Boiler Rehabilitations - Achievements A remarkable series of Major Boiler Rehabilitations where all key programme 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 resolution. Great cooperation with sub-contractors resulted in eliminating potential delays. 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 Power Plants 2010, Serbia 32

34 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 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, The boiler works were completed in parallel l to significant ifi 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. Power Plants 2010, Serbia 33

35 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 rehabilitation ti projects. Power Plants 2010, Serbia 34

36 Thank You Any Questions? Douglas Spalding Power Plants 2010, Serbia