Study on Shaft Seals for Potassium Turbine

摘要

Shaft seals for a potassium turbine using potassium vapor as a working fluid is described. The potassium turbine is one of the components in the Rankine cycle which is operated in the temperature range from 450 to 900 C. When this turbine is used together with a steam turbine as a binary vapor cycle, very high efficiency can be expected. It is extremely important that the outward leak of potassium from the turbine through the shaft seals at high vapor pressure to the atmosphere be prevented because of potassium's caustic chemical properties. Furthermore, the inward leaking of the gases to the turbine at low vapor pressure also must be prevented to avoid a decrease in turbine efficiency. Therefore it is necessary to develop a highly reliable seal system to achieve the successful operation of a potassium turbine. One of the main objectives of the study is the development of the shaft seal system for a small potassium turbine in test facilities, and the other is the design of a seal system for large scale turbines in commercial power plants.