A condensing steam turbine refers to a turbine where, after the steam expands and does work within the turbine, almost all of it enters the condenser to condense into water, with only a small amount escaping through the shaft seal.
In the process of steam condensation into water within the condenser, the volume of the steam suddenly shrinks, creating a vacuum in the sealed space originally filled with steam. This reduces the exhaust pressure of the steam turbine, increases the ideal enthalpy drop of the steam, thereby enhancing the thermal efficiency of the unit. Non-condensable gases (mainly air) in the steam turbine exhaust are extracted by a vacuum pump to maintain the necessary vacuum level.
The commonly used condenser for steam turbines is a surface-type one. Cooling water is discharged into a cooling water pool or tower to be cooled before being recycled. Power plants near rivers, lakes, or reservoirs, with sufficient water supply, can directly discharge the cooled water from the condenser into the water bodies, known as runoff cooling. However, this method may cause thermal pollution to rivers and lakes. In severely water-scarce areas, air-cooled condensers can be used. But they are structurally large, consume a lot of metal materials, and are rarely adopted by general power plants except for train power stations.
Primarily composed of the turbine body, condensate pump, condenser, and circulating pump, it refers to the process where steam, after doing work within the turbine, enters the condenser to cool and become liquid water, which is then returned to the boiler by the condensate pump.
The vacuum pump's function is to establish the necessary vacuum between the steam turbine and the condenser prior to the turbine's start-up. During the operation of the condensing steam turbine, it continuously removes air and other non-condensable gases from the condensing equipment to ensure the heat exchange efficiency of the condenser's heat exchange tubes and maintain the vacuum level. The performance of the vacuum equipment directly determines the exhaust pressure of the condensing steam turbine, which in turn affects the size of the unit's enthalpy drop and the amount of steam consumption. Different vacuum extraction methods can impact the equipment investment cost, the complexity of operational procedures, and the system complexity of the steam turbine unit, making the vacuum pump equipment quite important for condensing steam turbines.
Performance Features
A condensing steam turbine unit is a multi-stage condensing steam turbine with high steam cycle utilization. It can extract steam for use in production processes or heating systems. The turbine's exhaust enters the condenser, where it condenses into water, which is then recycled back to the boiler for reuse. The pressure of the turbine's exhaust is below atmospheric pressure. It operates stably and is widely used in industries such as thermal power, oil, chemicals, dyeing, textiles, cement, sugar production, and papermaking.
Structural Form: Quick Assembly Double-Support Impulse Multi-Stage Small Steam Turbine
Arrangement Style: Single-layer or Double-layer
Speed Control System: Hydraulic actuator manufactured with Siemens technology, featuring a 505 digital speed controller from a U.S. company and German electro-hydraulic transducer.
Over-speed Protection: Two sets of mechanical fly hammer with electromagnetic valve and electronic intelligent control
Steam seal type: Stainless steel blade labyrinth steam seal
Main Steam Valve: Integrated Automatic Main Steam Valve (Combination Regulating Valve)
Main shaft assembly: Multi-speed impeller blades, sleeve fit rotor and impeller set, embedded blade design impeller blades
Lubrication System: Forced oil lubrication, equipped with oil tank, thin oil station, and cooler.
Thermal Expansion Compensation: Front bearing support with sliding thermal compensation
Electrical Configuration: Complete control cabinets, protection cabinets, main control cabinets, and matching Siemens generators
Wheel Braking Device: Electric Wheel Braking
