Different condensers according to steam condensation can be divided into surface type (also called partition type) and mixed type (also called contact type). In a surface condenser, steam separated from the cooling medium is condensed into a liquid on a cooling wall (usually a metal tube). The cooling medium can be water or air. Water-cooled surface condensers are classified into a single process (Fig. 1) and a dual process (Fig. 2) according to the flow pattern of cooling water. In a hybrid condenser, steam is condensed into a liquid with mixing with a cooling medium. The condensed steam can be either water vapor or vapor of other substances.
The double-flow condenser water-cooled surface condenser is mainly composed of a casing, a tube bundle, a hot well, a water chamber and the like. The exhaust steam of the steam turbine enters the casing through the throat, condenses into water on the cooling pipe bundle and collects it in the hot well, and is extracted by the condensate pump. Cooling water (also known as circulating water) enters the cooling tube bundle from the inlet water chamber and is discharged from the outlet water chamber. In order to ensure a high vacuum and good heat transfer in the condenser during steam condensation, it is equipped with a pumping device that continuously draws air and other non-condensable gases that leak into the condenser. The pumping equipment mainly includes a water jet aspirator, a jet air extractor, a mechanical vacuum pump and a combined vacuum pump.
The air-cooled surface condenser air is traversed or naturally ventilated outside the tube bundle by means of a fan, and the steam is condensed into water in the tube bundle. In order to improve the heat transfer outside the tube, the condenser uses an external finned tube. Its back pressure is much higher than that of a water condenser.
Hybrid condensers are available in both spray and flat jet versions. In a spray condenser, the cooling water is atomized into a droplet shape; in the planar jet type, the cooling water is in contact with the exhaust steam of the steam turbine in a film form. Generally, a flat jet structure is used because it has a higher vacuum and can discharge all non-condensable gases.