The working principle of the labyrinth seal
The labyrinth seal is between the sealing cavity and the rotating shaft. A series of regular throttle gaps and expansion cavities are formed by a set of sealing teeth. When the gas flows through the gap formed by the sealing teeth and the shaft surface, the airflow is subjected to one time With throttling, the pressure and temperature of the air flow decrease and the flow rate increases. After passing through the gap, there is a larger cavity formed by two sealing teeth. As shown in the figure, the volume of the gas in this cavity increases, the speed decreases and a vortex flow is formed, generating a certain amount of heat energy. Therefore, before the gas in this cavity causes the temperature to return to the throttling, each time the gas passes through the gap and the subsequent larger cavity, the airflow is subject to throttling and expansion. As the number of gas flows through gaps and cavities increases, and the gap value decreases, the flow rate and pressure drop of the gas become larger and larger. When the pressure drops to approximately the back pressure, the gas does not continue to flow out, thereby realizing the gas Seal.
Precautions for labyrinth seal assembly and operation
(1) Ensure that the axial series of the bearing is less than 0.06mm. If it is too large, it may cause friction between the labyrinth bottom sleeve and the labyrinth positioning sleeve during operation.
(2) The concentricity of the pump and the motor should be ensured within the required range: radial 0.10m, end face <0.08mm
(3) Be sure to inject flushing fluid into the seal cavity before starting the pump to prevent dry friction of the mechanical seal
Advantages of labyrinth seal
(1) Suitable for high speed, the sealing effect is better at higher speed than at low speed.
(2) It is a non-contact seal and does not require lubrication. It is suitable for high temperature and high pressure applications, allowing thermal expansion and low power consumption.
(3) The maintenance is simple, if the manufacturing, assembly, and operation methods are reasonable, the service life is long.
(4) The material requirements are not high. Generally speaking, aluminum, bronze or carbon steel can be made of aluminum, bronze or carbon steel without special requirements such as temperature and anti-corrosion. High-pressure side steam temperature of industrial steam turbine
