International Conference Power Plants 2012 Society of Thermal Engineers of Serbia Oct 30 th Nov 2 nd, 2012 Zlatibor, Serbia

Transcription

1 Repowering Older Plants - The HRSG View International Conference Power Plants 2012 Society of Thermal Engineers of Serbia Oct 30 th Nov 2 nd, 2012 Zlatibor, Serbia

2 Heat Recovery Steam Generators offered by CMI Power Plants of 32

3 Inherent features Horizontal & Vertical HRSGs Horizontal Vertical Accessibility / Maintainability - + Cleanability - + Duct firing + = Arrangement = + Catalysts + = Erection cranes = + Cycling = + Lets review the specific application of repowering power plants and fuel oil in the following presentation slides Power Plants of 32

4 Introduction to power plants repowering In the Balkan and Central Europe, there is a large fleet of old coal fired power plants with a potential for repowering into modern combined cycle power plants. Compared to green field projects, repowering a steam turbine with a new train of gas turbine and HRSG includes some special challenges. Most of the time, the HRSGs have to be tailored made to suit limited foot print, and existing repowered steam turbine. CMI has completed such a large repowering project, like Senoko in Asia or Dunamenti in Hungary. These experience will be the support throughout this presentation to explain these specific repowering challenges. Besides this main topic, CMI will present the HRSG for heavy oil application, and the most recent references in Central Europe. Power Plants of 32

5 Concept of Plant Repowering OPTION Condenseur REMAIN 7 6 Turbine à vapeur 13 5 NEW HRSG 4 3 Pompes alimentaires : condensats - 2 : eau alimentaire - 3: eau alimentaire. IP - 4: eau alimentaire HP 5: vapeur HP - 6: retour turbine (Cold reheat) - 7: resurchauffe - 8 : vapeur LP - 9: eau désurchauffe by-pass IP - 10: by-pass IP by-pass LP 12: eau désurchauffe by-pass LP - 13 : by-pass HP Power Plants of 32

6 Repowering Senoko - Project background Repowering of old 3*120MW steam turbine into efficient CCPP Main contractor was Alstom using its gas turbine engine GT26B CMI Vertical HRSG 3P+R in natural circulation HRSG tailor designed to suit numerous constraints Project challenges: - limited foot print of old boiler - existing site very congested - only 18 months outage ALSTOM GT26 arrival at site Power Plants of 32

7 Site limitations 3D model new boiler Original fired boiler had to contain new GT+ HRSG. Available area for HRSG was limited to 30.6*28.1m HRSG indoor includes main auxiliaries (cargo lift, FWP, feedwater tank, etc) CMI exchanged with Alstom 3D model to make detailed plant modelling Power Plants of 32

8 Vertical HRSG flexible layout A Vertical HRSG behind GT class F for greenfield is around 35 meters long. In case of Vertical HRSG, tubes length impact directly the overall boiler length. This is not the case for Horizontal HRSGs. This is a special flexibility feature offered by the Vertical HRSG only. Typical tubes length 20.4 m GT Typical heigth 9 m Overall boiler length 35 meters Power Plants of 32

9 Vertical HRSG flexibility layout To match this repowering limited space (length 30,6 meters), CMI has taken advantage of this flexible arrangement offered by the Vertical HRSG: CMI used shorter tubes length. For unchanged casing cross section, boiler casing was enlarged in proportion Longest tube 20.4 m Reduced tube/boiler length Gas cross section Flexible Gas cross section unchanged Slightly enlarged boiler width Power Plants of 32

10 Vertical HRSG flexibility layout Considering the installed boiler heating surface, this HRSG was arranged in 3 modules in width by 4 levels in height, instead of 2 modules wide by 5 levels height which would have applied otherwise for a greenfield site. Heating surface modules flexible arrangement Standard 'greenfield' arrangement Senoko enlarged casing width Power Plants of 32

11 Modular construction HRSG was made of 12 heat exchanger modules prefabricated and hydrotested to reduce erection time. The largest module dimensions was 23.6 meters long * 3.9 wide *2.9 heigth. Heat exchanger modules unloading and transportation Power Plants of 32

12 Congested existing site Boiler modules were transported by hydraulic trailer self propelled which reduced convoy length and help to perform precise movements with large angle orientation wheels in congested site Heat exchanger modules arriving at the gate of the existing power plant (Site very congested) Power Plants of 32

13 Modules erection using hydraulic jacks 28 hydraulic jacks to lift modules on top of structure Vertical HRSG: No large crane was required. Vertical HRSG Steel structure with jacks on top for module lifting Power Plants of 32

14 Modules erection using hydraulic jacks Considering a congested site, the CMI Vertical HRSG erection features: - no module tilting performed - no large cranes required Horizontal HRSG typical lifting system Power Plants of 32

15 Modules erection sequence The first row of 3 modules was hanged to cables and lifted up just enough to introduce the next row of 3 modules. This operation was repeated until all 4 levels of modules were suspended to one another. Power Plants of 32

16 Modules erection sequence Erection cables Temporary plates (peinted in yellow) Final suspensions First row of modules suspended Power Plants of 32

17 Modules erection sequence Hydraulic trailer self propelled had to manoeuvre in limited space. Introduction of the second row of modules. Power Plants of 32

18 Modules erection sequence The module was positioned exactly and it was attached to the module just above it on each support plates. Then, the hydraulic trailer was lowered and released. Power Plants of 32

19 Modules erection sequence Erection of last row: All modules remained flat during the complete erection sequence Power Plants of 32

20 Modules erection sequence Completion of 12 modules suspended Only adjacent header ends were to be welded Power Plants of 32

21 Modules erection sequence The complete assembly (1450 tonnes) was then jacked up on top of the steel structure. Hydraulic jacks were released, dismantled and installed on the next unit. All modules suspended in final position inside the steel structure Power Plants of 32

22 Modules erection sequence Boiler modules erection completed in 6 days only! Power Plants of 32

23 Indoor HRSG HRSGs steel structure has been extended to an enclosure wrapped all around for weather protection, noise abatement and aesthetic. View of completed repowered Senoko Power Plant Power Plants of 32

24 Repowering de Dunamenti G3 in Hungary Unit 9 Unit 8 G3 to be repowered Power Plants of 32

25 Repowering Dunamenti - Project background The GDF SUEZ Group, majority owner of the Dunamenti power station, Hungary s second largest power plant, decided to upgrade its G3 unit, a combined-cycle gas turbine (CCGT) block, from 215 MW to 400 MW, commissioning in In this repowering process, Dunamenti, the existing gas-fired steam turbine and installed a heat recovery steam generator (HRSG) and a gas turbine. This raised the unit s efficiency from 36% to 57%. The Dunamenti plant accounted for 7% of all electricity generated in Hungary in 2010, producing 2.6 terawatt-hours. View of the Repowered Dunamenti Power Plant Power Plants of 32

26 Repowering Older Plants - The HRSG View Repowering of old conventional plants into new efficient CCPP (new GT-HRSG sets with old ST sets) is a cost effective solution, because existing equipments remains such as steam turbine, electrical distribution, cooling system, etc. Permitting is also more easy as this is an existing power plant. Compared to greenfield plants, repowering of old units always requires tailor made design to match specific constraints: - remaining equipment's (steam turbine, condenser, etc) - limited available space of the old fired boiler - minimum outage of the existing plant - congested existing site - indoor HRSGs The Vertical HRSG has proofed to be very flexible and accommodating for those specific repowering constraints. Power Plants of 32

27 Design Criteria for HRSG Heavy Fuel Oil Operation Gas turbines are operated typically on natural gas, with no risk of fouling and typical dew point at 60 C. Both Horizontal or Vertical HRSG are suitable for the purpose. Heavy fuel oil has high sulfur content with Acid Dew Point (ADP) up to 145 C Such high sulfur content requires a special HRSG design because all metallic surfaces must remain above ADP to prevent internal corrosion on tubes and ducting. Temperature of condensate water entering finned tubes must be controlled to remain above ADP to avoid acid formation on tubes It limits the heat recovery in the back end of the HRSG Ducting metal must remain above ADP which is not feasible with internal insulation. HRSG must be externally insulated with ducting remaining at inside flue gas temperature. Power Plants of 32

28 Design Criteria for HRSG Heavy Fuel Oil Operation Combination of Heat Exchangers arrangement and Sootblowers must maintain permanent industrial cleanliness of finned tubes: Finned tubes Maximum height of solid fins Maximum fins density (160 fpm on heavy oil) Staggered or inline arrangement with constant minimum tubes pitches Limitation of tube rows per bank Sootblowers Between tubes banks for on-load cleaning Rotary or Rake type parallel to tubes Boiler design for Fuel Oil is different than Natural Gas. This requires specific boiler expertise with references. Power Plants of 32

29 Proven HRSG design for Distillate Oil HRSG designed for continuous operation on distillate oil Power Plants of 32

30 Proven HRSG design for Crude Oil HRSG designed especially for continuous operation with crude oil and equipped with sootblowers Power Plants of 32

31 Conclusions There is real potential for repowering of old steam turbines in the Balkans. In a lot of old conventional plants, fired boilers have exhausted their useful life before its steam turbine. Repowering of those old steam sets into efficient combined cycle with new GTs and HRSG is a cost effective solution. Today, available gas turbines can provide the exhaust energy for steam turbines of MW of which there are many examples in Europe dating back from the 1970 s. These units could be repowered so as to increase power supply with a significant improvement in operating efficiency, flexibility and emissions. CMI has completed the Senoko and Dunamenti plants, which are a very successful example of such repowering. Vertical HRSG has been proofed to be very accommodating for those the specific repowering constraints, which always require a tailor made design to suit limited space. In addition CMI Vertical HRSGs are uniquely fit behind Gas Turbine firing fuel oils. Power Plants of 32

32 Question time Thank you for your attention Europe: hrs@cmigroupe.com Website: Power Plants of 32