Mechanical energy is required to drive the generator. Actually, any type of "motor" can be used to drive the generator, e.g. gas turbine, steam turbine, water, turbine or wind turbine, we could also use petrol engines or diesel engines. If we wish to generate mechanical energy for industrial applications, the motor must be very powerful and extremely efficient. The size of the motor is less important. Of these machines, the steam turbine is by far the best suited for meeting these requirements. In this case, the source of power is steam, and the energy conversion is performed by allowing the high-pressure of the steam to drop to pressure and temperature values as low as possible.

A steam turbine consists of a series of blades mounted on a shaft. As the steam jet is inflected, it puts pressure on these blades, making the shaft rotate. The pressure and heat content of the steam drops and part of the pressure and thermal energy is converted into kinetic energy and consequently mechanical energy.

The steam turbines generally contain one high-pressure and several low-pressure chambers. The pressure and heat content of the steam drops between two consecutive stages! This enables optimal use of the steam power. The steam which leaves the high-pressure turbine is dried and reheated. This means it no longer contains harmful water droplets and extra energy is supplied before the steam drives the low-pressure turbine.

In the high-pressure chamber, the pressure drops from around 60 bar (depending on the unit) to approximately 10 bar, and the steam temperature also drops proportionally. The low-pressure steam at the outlet of the high-pressure chamber is superheated in so-called superheaters; which are heat-exchangers that make use of a part of the steam bypassed at the entry of the high-pressure turbine. The pressure of the steam in the low pressure chambers then drops to approximately 0.05 bar, practically a total vacuum.

Turbine-Generator.
In front view, the HP element and the three LP elements.