Siemens Provides Power To Austrian Town
BY ROBERTO CHELLINI
A single-shaft combined-cycle gas turbine generates 412 MW for Timelkam, Austria
Siemens Energy has installed a combined-cycle power plant in Timelkam, Austria, a small town located between Salzburg and Linz. This plant has an installed capacity of 408 MW and will have an annual generating capacity of 2400 gigwatthours. Overall efficiency of the plant is approximately 59%. The plant is also engineered to provide up to 100 MW to a district heating system, which results in a 70% overall energy utilization of the natural gas fuel.
The new plant replaces a 47-year-old coal-fired plant and was designed to produce seven times more energy. At the same time, it reduces the production of harmful emissions. CO2 per generated kW/h is two-thirds lower, and NOx is reduced by 90% when compared to the old installation, said Siemens. A heat recovery steam generator (HRSG) with built-in catalytic reactor was incorporated to keep NOx emissions levels below 20 mg/Nm3.
The Timelkam combined-cycle plant has been designed for base load operation (7500 hours per year) with very high flexibility, for variances ranging from 25 to 100% load. Its configuration is single shaft. The gas turbine, the generator and the steam turbine are connected inline to form one 45 m long unit enclosed inside a 55 m long and 34 m wide building.
The gas turbine is an SGT5-4000F rated 292 MW and features a 39.8% efficiency. These turbines are built by Siemens in its Berlin, Germany, plant. This model was first launched at the
beginning of the 1990s with the designation of V94.3A and an introductory rating of 240 MW with an efficiency of 37%.
In 2004, a hydraulic clearance optimization system was integrated into the design of the turbine. This feature uses the hydraulics system to drive the motion of the rotor in the axial direction to reduce the gap between the turbine blades and the casing after the turbine has warmed up. This operation minimizes internal gas recirculation, improving the overall efficiency of the machine, said the company. Siemens considers the SGT5-4000F its workhorse. Since its introduction, 240 units of this turbine have been sold, and more than 200 of them are in service.
The great majority of these turbines are operated in plants with a combinedcycle configuration, and among these, 73 are SCC5-4000F1S single-shaft units. Altogether, gas turbines of this type have accumulated a total of 4.7 million equivalent operating hours (EOH), with the leading machine surpassing 100 000 EOH. The average fleet reliability is over 99%, Siemens said.
The other two core components of the single-shaft train are the generator, placed in the middle, and the steam turbine on the opposite end. The SGen5-2000H generator is hydrogen cooled. The SST5-5000 steam turbine features a double casing (combined high pressure/ intermediate pressure and doubleflow low pressure) with reheating. It operates at 3000 r/min and has a gross output range between 120 and 500 MW, depending on the plant configuration.
Transportation of these components to the Timelkam site was a challenge. The gas turbine, after being fully assembled for testing in Berlin, was disassembled in several modules for transportation. The steam turbine casings were shipped from the Mülheim an der Ruhr, Germany, plant by waterway and train. While the 350 ton, 12 m long generator built in Charlotte, North Carolina, U.S.A., after being shipped across the Atlantic, traveled from Antwerp, Belgium, to Linz, Austria, on the Rhine-Main-Danube Canal and then on a specially built, 64 m long, 32-axle train car from Linz to the plant site.
Another major piece of equipment is the vertical HRSG with a NOx catalytic converter, which was delivered by Austrian company Balcke-Dürr, which was recently acquired by Siemens. In
addition to the auxiliary and secondary equipment, Siemens delivered the electric systems and the SPPA-T3000 control system and then integrated them into the customer’s systems.
Interface problems were minimized by commissioning Siemens ELIN to install the entire technical building system. The new Timelkam plant not only produces electricity for about 700 000 households, it also delivers up to 100 MW of heat to a district heating system. The heat grid extends for 166 km to serve 4860 “heat customers.”
The 50 MJ/s of heat is extracted from the outlet of the intermediate steam turbine casing, which provides steam at 3.7 bar and 270°C. The second extraction, from the low-pressure casings, supplies steam at 1.2 bar and 150°C. The condensate from the heaters is fed back into the condensate line downstream the main condensate pumps.
The steam extraction of 50 MJ/s corresponds to roughly 240 kg/s fed into the district heating system, reducing the electric power output by about 5 MW. Siemens has been providing heat to
district heating systems from singleshaft combined-cycle plants since building the Donaustadt 3 plant in Vienna, Austria, 10 years ago. Construction of the Timelkam combined-cycle plant involved a total of 725 876 man-hours. At peak times, a workforce of more than 800 was
employed at the site. Timelkam CC, the plant operator, signed a 12-year, US$96 million maintenance contract for the gas turbine unit with Siemens.