Condensing steam turbine It is widely used in power generation at thermal power plants. The condensing equipment mainly consists of a condenser, a circulating water pump, a condensate pump, and an air extraction device. The exhaust steam from the steam turbine enters the condenser, where it is completely cooled and condensed into water by the circulating water. The condensed water is then pumped out by the condensate pump, heated through various stages of heaters, and finally sent to the boiler as feedwater.

The condenser commonly used in condensing steam turbines is the surface-type condenser. After cooling, the condenser cooling water is discharged into a cooling pond or cooling tower and then recirculated for reuse. In power plants located near rivers, lakes, and other bodies of water, if water resources are abundant, the cooling water discharged from the condenser can be directly released into these water bodies—this is known as runoff cooling. However, this method may cause thermal pollution to rivers and lakes. In regions experiencing severe water shortages, power plants can opt for air-cooled condensers. Yet due to their bulky structure and high consumption of metallic materials, such condensers are rarely adopted by conventional power plants except in mobile power stations. Some older power plants employ hybrid condensers, in which the exhaust steam from the turbine is directly mixed with cooling water for contact cooling. However, since the condensate from the exhaust steam becomes contaminated by the cooling water, it must undergo treatment before it can be used as boiler feedwater; thus, this approach is seldom utilized.

Condensing steam turbine Due to the large volume of condensing steam, it is generally more suitable for cooling with cooling water in areas with abundant water resources. If used in regions with water scarcity, air cooling would be required instead. However, when air cooling is employed for large volumes of steam, the air-cooled condenser becomes larger in size, making cooling more challenging and increasing equipment investment. The primary function of a condenser is to establish and maintain the required vacuum in the turbine exhaust chamber, allowing the steam to expand to a lower pressure within the turbine. This increases the available enthalpy drop of the steam, thereby converting more thermal energy into mechanical work. At the same time, the condenser condenses the turbine exhaust steam into water, which is then reheated and pressurized before being recycled as boiler feedwater, thus reducing water production costs. Moreover, the condenser also has an oxygen-removal function. Additionally, the condenser serves as the lowest-pressure steam-water collector in the thermal system; it receives steam discharged from the bypass system during unit startup and shutdown, recovers condensate, and discharges various types of water.

Condensing steam turbine Manufacturers believe that, in order to maximize the amount of work steam can do in the turbine, the condenser must operate at a very low pressure—meaning it must maintain a high vacuum. This, in turn, requires the condenser body and the vacuum system to be highly leak-proof, preventing air from leaking in and disrupting the heat exchange conditions within the condenser, thereby reducing the vacuum level and contaminating the condensate. However, achieving absolute sealing of both the condenser body and the vacuum system is simply impossible. Therefore, vacuum equipment—such as vacuum pumps—must be continuously operated to pump out any air that leaks into the condenser. Furthermore, the water-side sealing must be excellent, ensuring that the condensate does not become contaminated due to leakage of circulating water. This is especially critical for large-scale facilities with stringent water quality requirements.