The main shaft seal of the water turbine is one of the key components of the unit. It is set between the water guide bearing and the rotary wheel to reduce or prevent the leakage of the pressure water between the rotating part (mainly refers to the main shaft) and the fixed part, to prevent the water from submerging the water guide bearing, to prevent the accident of the unit and to ensure the safety of the power station. The quality of the main shaft seals is directly related to the operation safety, maintenance period and the economic benefits of power plants. Therefore, all links include the design of the main shaft seal, the manufacture, and the installation must be attached great importance to.
In recent years, new developments have been made in the design of mechanical seal structure and application of new materials for water turbine main shaft. In the design of a new power station, in general, we should adopt a main shaft sealing structure that is mature, reliable and convenient. At the same time, various kinds of sealing structures can be designed to meet the needs of different power stations according to the requirements of the users.
The main shaft seal of the water turbine can be divided into water turbine working seal and water turbine maintenance seal according to its working nature. Generally, a water turbine integrates both working seal and maintenance seal. Below is the introduction of these two seals, for the design discussion reference.
The working seal of the water turbine is the main seal of the main shaft seal. It is set up for reducing the leakage of the water during the operation of the unit. According to the seal structure, it can be divided into radial seal, axial seal, non-contact seal and combined seal. Radial seal can be divided into packing seal and cutting ring seal. Radial seal mainly uses wear-resistant materials, under the action of mechanical spring, to form a radial cover along the radial and the anti-wear bushing on the main shaft, which is lubricated by clean water. The sealing surface is mainly through contact pressure and lubricating water to stop leakage and seal.