Extraction Steam Turbine
In general, an extraction steam turbine (EST) is a type of turbine whose purpose is to extract some of the available energy from the exhaust steam from another turbine. This is usually done to prevent the low-pressure steam from entering the normally high-pressure condenser, or for power generation in its own right. In either case, the working fluid of the extraction steam turbine is the exhaust steam from another turbine, supplied from the turbine’s own outlet either directly or via a boiler or steam generator.
In operation, the exhaust steam is drawn off the outlet of the first turbine and directed through the inlet of the EST. It then passes along the length of the turbine casing, rotating the turbine and extracting energy from the steam as it moves. The steam, now at lower pressure, is then discharged through the turbine’s outlet to the condenser.
The extraction steam turbine as described above is a relatively simple device and has several distinct advantages. Firstly, it is highly efficient since it is able to fully utilize the heat energy in the steam. The turbines exceptional short retention time also makes it the ideal choice for applications where rapid response is important, and it can operate at higher speeds than steam turbines of comparable size. Additionally, the device can operate at very low pressures and temperatures and therefore does not require complicated reheat systems.
ESTs are used for a variety of applications. In power plants and other industrial systems, ESTs are employed to decrease the pressure of the exhaust steam and so increase the efficiency of the power plant. The extracted steam can also be used for process applications or to generate additional power, providing an optimal balance between cost and efficiency. Furthermore, by harvesting thermal energy from the exhaust steam, it can be utilized more effectively, either for generating additional power or for reheating the steam, increasing overall system efficiency.
ESTs are available in a range of sizes and configurations. They are usually horizontal or vertical in orientation, and can be customized for a variety of different applications. In particular, for power generation, the turbine can be configured for either back-pressure or condensing operation, depending on the application needs. Furthermore, for process applications, the turbines inlet conditions can be set to ensure optimal operation.
Overall, ESTs are reliable, efficient, and cost-effective devices that are suitable for a variety of applications. By maximizing the use of the available energy in the exhaust steam, they can provide a significant contribution to system efficiency, while also reducing operational costs.
