Introduction to the Working Principle of Condensing Steam Turbines

The condenser commonly used in condensing steam turbines is of the surface type. The cooled water is circulated and reused in cooling towers. At power plants located near rivers and lakes, if water availability is sufficient, the discharged water can be directly released back into the rivers and lakes—this practice is known as runoff. However, this approach may cause thermal pollution to the rivers and lakes. In regions experiencing severe water shortages, power plants can employ air-cooled condensers. Yet due to their bulky structure and high consumption of metallic materials, they are rarely used in conventional power plants except for mobile power stations.

What’s going on with the condensing steam turbine’s cylinder being sealed?

A condensing steam turbine is one in which the steam expands and does work within the turbine, and except for a small amount of leakage from the shaft seals, all the steam is directed into the condenser, where it condenses into water. So, what exactly is "cylinder trapping" during the operation of a condensing steam turbine?

Some Key Points About Condensing Steam Turbines

Condensing steam turbines are widely used in thermal power plants for power generation. 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.

Next, let’s talk about the startup procedures for a condensing steam turbine.

With the widespread use of steam turbine equipment, manufacturers have made numerous design choices. Generally, the startup procedures for condensing steam turbines can be categorized into hot start, warm-state start, medium-temperature start, and cold-state start. Improper startup procedures can easily damage the equipment, disrupt its normal operation, reduce operational efficiency, and shorten its service life.

Some Common Sense Introduction to Condensing Steam Turbines

The condensing equipment is an essential component of a condensing steam turbine. Due to factors such as design, installation, maintenance, and operational mechanisms, low vacuum in the condenser frequently occurs during operation. If the condenser vacuum falls too low, not only will the effective enthalpy drop of steam within the unit be reduced, but also the thermal efficiency of the cycle will decline, leading to an increase in the exhaust steam temperature, deformation of the exhaust cylinder, and vibration. Under normal operating conditions, the relationship between the exhaust pressure and exhaust temperature of the condenser follows that of saturated steam.

What are the characteristics of a condensing steam turbine?

As the primary condensing equipment in a condensing steam turbine unit, the condenser’s task is to establish and maintain a high vacuum at the turbine exhaust port, condense the turbine exhaust steam into water, and then pump this condensed water via a condensate pump to the deaerator, where it is converted into boiler feedwater. The vacuum level of the condenser directly affects the normal operation of the unit. It can be said that the operational performance of the condenser has a direct impact on the safe and economical operation of the steam turbine unit.