Condensing Turbine

a steam turbine whose operating cycle ends with the condensation of steam. One of the principal advantages of a condensing turbine (as compared with any other engine) is that a high power output (1,200 megawatts [MW] and higher) can be produced by a single unit. condensing turbines are used to drive the generators at all large steam and atomic power plants; they are also used as the propulsion engines of ships and to drive the turbo blowers of blast furnaces.

Powerful condensing turbines usually have several stages and a complete system for regenerative heating of feed water (as many as eight or nine bleedings of steam for heating). condensing turbines with rated power of more than 100 MW usually use a single intermediate superheating step.

In the USSR the first condensing turbine was built at the Leningrad Metal Works in 1924. It had a rated power of 2 MW and operated on steam at initial pressure of 1.1 meganewtons per sq m (MN/m²), or 11 kilograms-force per sq cm (kgf/cm²), and temperature of 300°C. In 1970 the same factory built a close-coupled condensing turbine with a rated power of 800 MW, initial steam pressure of 24 MN/m² (240 kgf/cm²), and temperature of 540°C. A close-coupled condensing turbine with a rated power of 1,200 MW and featuring immediate superheating was under construction in 1973. It is unique in world turbine production.

Atomic power plants usually use condensing turbines operating on saturated steam. The steam consumption of such turbines is about 60–65 percent higher than that of condensing turbines of the same rated power operating on superheated steam. To pass the increased quantity of steam through the last stages, the blade length must be increased, which is possible only by decreasing the speed of rotation of the turbine. Therefore, condensing turbines with rated power of 500 MW and more are usually built to operate at 1,500 rpm rather than 3,000 rpm. The S. M. Kirov Kharkov Turbine Plant manufactures condensing turbines that operate on saturated steam at 3,000 rpm, with rated power of 220 and 500 MW. A new series of condensing turbines rated at 500 and 1,000 MW at 1,500 rpm is under development at the same plant.

A variety of condensing turbine is the type in which bleeding of steam for heating and industrial purposes is controllable. Such turbines, which are used for combined production of electric power and heat, are called heating turbines; they are installed in heat and electric power plants. In 1971 the Urals Turbine Plant built the first heating turbine with intermediate superheating; it had a power output of 250 MW and was designed for a heat release of 394 MW (340 gigacal/hr).