Now that the 412-MW Timelkam Power Plant has replaced a 47-year-old coal-fired power plant located in the Vöcklabruck District, northern Austrians can bid auf wiedersehen (goodbye) to high levels of air pollution. Compared to its predecessor, the new gas-fired combined-cycle plant has dramatically cut CO2 and NOx emissions and produces seven times more energy.

Austria is famous for Alpine ski slopes, historic castles, and Mozart’s melodies. Beyond its tourist attractions, it is a prosperous country with a well-developed market economy and citizens who enjoy a high standard of living. The latest example of Austrians wedding style and function is the Timelkam combined-cycle power plant (CCPP), which is configured to also supply steam to the local district heating system. The facility’s attractive architecture is called “marriage with the sky” and is intended to symbolize the replacement of coal with natural gas, which represents a cleaner energy supply.

Austria’s annual gross electrical production is approximately 67.1 billion kWh and its consumption is about 68.65 billion kWh (2008 estimates), according to statistics from e-controls (Austrian regulators). The country exports approximately 14.93 billion kWh of electricity yearly and imports about 19.8 billion kWh (2008 estimates).

The 412-MWe/100 MWt Timelkam CCPP, which went into operation in December 2008, was built to provide for the electrical needs of the state of Upper Austria, home to the city of Linz. With its advanced turbine technology, the facility can attain an electrical efficiency of approximately 58.7% in its condensing operation while producing low pollutant emissions. With district heat extraction of up to 100 MWt, the plant utilizes up to 70% of its fuel. Carbon dioxide (CO2) emissions per generated kilowatt-hour are two-thirds lower than emissions generated by the coal-fired power plant that formerly operated at the same location, while nitrous oxides (NOx) are reduced by 90%. NOx emissions are kept at an exceptionally low level of less than 20 milligrams per normal cubic meter thanks to the built-in catalytic reactor unit.

Project Data

As in simple-cycle applications, the gas turbine is the main driver for power generation at CCPPs. However, to improve overall efficiency, CCPPs also use exhaust heat from the gas turbine to produce steam for the generation of additional electricity by a steam turbine.

The power plant consists of an SCC5-4000F-1S single-shaft unit of the Siemens design, in which the main components—SGT5-4000F gas turbine (Figure 1), SST5-5000 steam turbine, and SGen5-2000H generator—are arranged along a single line of shafting, according to Martin Wilkening, Siemens sales manager for gas turbine power plant solutions in Central Eastern Europe.

1. The brawn beneath the casing. The SGT5-4000F gas turbine at the Timelkam plant, shown before final assembly. Courtesy: Siemens

“The gas turbine deployed in Timelkam—our proven ‘workhorse’—was the SGT5-4000F and it was previously known as the V94.3A,” Wilkening said. “This machine is highly successful in operation, with an average reliability of over 99%. More than 280 of these turbines have been sold since it was first installed in Didcot, England, in 1996, and more than 200 are already commissioned. All together, gas turbines of this type have amassed 4,700,000 equivalent operating hours (EOH), with the leading machine clocking 98,000 EOH.”

The SST5-5000 is a three-stage steam turbine with reheating and functions in the following stages: high pressure, intermediate pressure, and low pressure. It has a speed of 3,000 revolutions per minute and a gross output of between 120 MW and 500 MW, depending on whether it is operating in extraction steam mode for district heating or condensing mode for maximum power generation. The SGen5-2000H generator employed at the Timelkam plant is hydrogen-cooled and based on proven technology. Hydrogen-cooled generators are employed in the power output range of 350 MVA to 600 MVA.

Distinctive Design Features

The Timelkam plant is based on the single-shaft reference power plant, which has been tried and proven globally; 82 such units have already been sold by Siemens (50 are in commercial operation), according to Wilkening. The total length of the configuration is 45 meters. The powerhouse at the Timelkam plant extends 55 meters and is 34 meters wide. The compact layout is mainly achieved by the high level of arrangement of the single-shaft power train.

The Siemens basic power plant is modular, resulting in a high degree of flexibility and making it relatively easy to select the most advantageous options for a particular location and a customer’s specific requirements. This modular design results in short project lead times and offers an optimal balance between capital costs, plant performance, and operation and maintenance. In particular, the Timelkam plant has been optimally adapted for district heat extraction, he pointed out.

“I would also like to point out the hydraulic clearance optimization (HCO),” Wilkening said. “This design feature—first introduced in the SGT5-4000F in 2004—is unique to the new Siemens turbines. HCO enables the turbine rotor to be moved hydraulically in the axial direction in order to reduce the gap between the turbine blades after the turbine has warmed up and when operating under load.”

Construction Challenges

Siemens handed over the new natural gas–fired Timelkam CCPP to Energie AG Oberösterreich and the Swiss Groupe E in December 2008 after an approximately two-year construction period that began in October 2006. Construction of the plant involved a total of 725,876 man-hours. At peak times, a workforce of more than 600 was employed at the site.

In addition to turnkey construction of the power island, Siemens also delivered the SGT5-4000F gas turbine from its Berlin plant. The SGT5-4000F was launched in the early 1990s with a capacity of 240 MW and 37% efficiency. Through optimization, it now has a capacity of 292 MW and an improved efficiency of 39.8%. Timelkam’s SST-5-5000 steam turbine comes from the factory in Mülheim, Germany.

The generator was built in Charlotte, N.C. Transporting the 348–metric ton generator from the Charlotte plant to Timelkam represented a special technical challenge. The massive weight of this packed generator is roughly comparable to an Austrian Railjet train with one locomotive and seven coaches.

The first part of the 7,000-kilometer journey for the generator, which measures more than 12 meters in length, was via ship across the Atlantic Ocean. Then it traveled from Antwerp to Linz on the Rhine-Main-Danube Canal. The final leg of the journey to Timelkam was by rail, in a specially constructed transport device that took about a year to design and build. The total length of the unique 32-axle train car, traveling mostly at low speeds through Upper Austria, was 64 meters—not including the locomotive.

Transporting the gas turbine from the Siemens plant in Berlin required additional logistical prowess. Because the turbine could not be transported in one piece, it had to be dismantled after initial assembly and tests in Berlin and then transported in individual sections to Upper Austria, where the final assembly was completed.

The upright waste-heat boiler with NOx catalytic converter was delivered by the Austrian company Balcke-Dürr, which was recently acquired by Siemens. In addition to the auxiliary and secondary equipment, Siemens delivered the electrical systems and SPPA-T3000 control system, and also integrated them into the customer’s systems.

A 12-year maintenance contract worth €71 million was signed for the turbine unit. Interface problems were minimized by commissioning Siemens ELIN GmbH & Co KG to install the entire technical building systems.

High Achiever

The new Timelkam gas-fired power plant’s performance makes it one of the most efficient and cleanest power plants not only in Austria but also worldwide. Its annual production of approximately 2,500 GWh, which corresponds to the electrical consumption of about 700,000 households, helps to stimulate the regional economy and is a welcome addition to the Vöcklabruck District.

Angela Neville, JD, is POWER’s senior editor.