Operation of a power plant fired by natural gas
© Helsingin Energia
In the Vuosaari natural gas-fired power plants, natural gas from Russia is combusted in gas turbines. Flue gas, which comes out of the gas turbine at a temperature of some 500 degrees, is conducted into the steam boiler where the water heats up and turns into steam.
The resulting water vapour makes the rotor of the steam turbine rotate when it travels through the blades connected to the turbine shaft. The energy from the rotating movement is converted into electric energy in the generator, which is connected to the same shaft as the turbine. The steam that has travelled through the turbine still contains plenty of heat energy. Steam is condensed, i.e. converted back into water, by cooling it with district heating water, which, in turn, is utilised when buildings are heated with district heat. The recovered heat raises the efficiency of the power plant to up to 92 per cent.
Russian natural gas consists almost exclusively of coal and hydrogen, which produce carbon dioxide and water under combustion. Nitrogen emissions causing acid rain account for one-sixth of the nitrogen emissions of the coal-fired power plant, and there are no sulphur or dust emissions.