Siemens Power Generation supplied two turnkey 830MW combined-cycle power plants in Argentina. A Siemens-led consortium constructed the plants in Campana in the province of Buenos Aires and in Timbúes near Rosario in the province Santa Fe.
For both projects, Siemens PG delivered two high-efficiency SGT5-4000F gas turbines, one SST-5000 steam turbine and its SPPA-T3000 instrumentation and control system. The $1.6bn contract also includes heat recovery steam generator and power electronics.
The primary fuel is natural gas, with liquid fuel as an alternative. Commercial operation began in the first half of 2008 in open cycle mode. The operations were started with the first 270MW natural gas turbine. Full operation in combined cycle mode will commence when the plant reaches a capacity of 830MW. Siemens will maintain the two plants for ten years.
High efficiency gas turbines
Since its market introduction in 1996, the fleet of SGT5-4000F (formerly the V94.3A) and its three smaller sister models SGT6-4000F, SGT5-3000E and SGT 1000F (formerly V84.3A, V94.2A and V64.3A) have accumulated over 2.7 million Equivalent Operating Hours (EOH).
The reliability level of the SGT5-4000F engines has been above 99% for five consecutive years. Availability levels are typically above 94%, depending on the percentage of engines that have a major revision in the period.
Siemens has enhanced the SGT5-4000F, giving higher component efficiencies due to better compressor and turbine aerodynamics and higher gas turbine output.
The upgrade includes slightly re-designed compressor blades and vanes on Stages 1 and 2 and inlet guide vanes for increased mass-flow.
The row 4 turbine blades were also re-staggered to reduce aerodynamic losses at increased mass flow.
A redesign of Ceramic Heat Shields (CHS) material has reduced service cost by lowering the fallout rate.
Operating parameters have been adjusted to stay in premix mode at turndown below 50% base load while remaining within required emissions limits. A Hydraulic Clearance Optimization (HCO) system controls turbine blade-tip clearances to increase power and efficiency. Aerodynamic characteristics of the first two compressor stages and the inlet guide vane have been modified to increase compressor inlet mass flow and so increase efficiency.
The airfoil geometry was adapted to the existing flow channel and the slots in the rotor discs. The last stage blade was also re-staggered by 1.5°, achieved by a simple casting change by turning the existing airfoil on the existing blade root.
Tightened radial clearances
Tight radial clearances in both the compressor and the turbine section are key to raising component efficiencies. During operation, radial clearances must be small to avoid contact between rotating and stationary parts. Siemens balanced the warm-up and cool-down behavior of the casing and rotor components.
The rotor, which typically has the slower thermal response, can be heated and cooled quickly by internal secondary airflows. The conical flow path in the turbine casing of the frames allows extra clearance control by combining axial and radial growth. The rotor can be shifted against the flow direction, reducing the radial gaps above the turbine blade tips.
The SGT5-4000F already had a good thermal balance allowing for tight clearances. Once the engine is fully heated during base load, the clearances are larger than needed because they are chosen for hot restart (the most critical operation mode). Clearances also need to be large enough to account for casing ovalisation during heat up. Tackling these two effects allows turbine clearances to be reduced after the engine is fully heated.
The new turbine was intensively tested in a lead engine of customer Kraftwerke Mainz-Wiesbaden. Further evolutionary improvements, especially in the combustor and burner, are on their way.
Argentinian economy growing
Over the past three years Argentina’s economy has grown by about 9% a year. These new orders are part of the government’s national energy plan from 2004 to prevent an energy shortage.
Presently, Argentina has an installed capacity of 24,000MW. By the year 2015, experts expect an increase of the installed capacity to approximately 38,000MW.
Both Campana projects are being constructed and operated by the Independent Power Producers Termoeléctrica Manuel Belgrano (TMB) and Termoeléctrica José de San Martín (TSM).
Main shareholders for these two companies are ENDESA, TOTAL, AES, PETROBRAS, EDF and DUKE. The consortia partners Duro Felguera S.A. and Electroingeniería S.A. for TMB and Inelectra S.A.C.A. and Electroingeniería S.A. for TSM are responsible for the balance of plant and construction.