Types of bearings of steam turbines

There are two types of turbine bearings: thrust bearings and support bearings.

The support bearing is to bear the weight of the rotor and the centrifugal force generated by the unbalanced mass of the rotor, and to determine the radial position of the rotor to ensure that the center of the rotor is consistent with the center of the cylinder to ensure the correct radial clearance between the rotor and the stationary part.

Thrust bearing is to bear the unbalanced axial thrust on the rotor and determine the axial position of the rotor to ensure the axial clearance between the dynamic and static parts.

The working principle of steam turbine support bearing

In the sliding support bearing, the inner diameter of the bearing pad is slightly larger than the outer diameter of the journal. When the rotor is stationary, the journal is at the bottom of the bearing pad, and a wedge-shaped gap is naturally formed between the journal and the bearing pad. If lubricating oil with a certain pressure and viscosity is continuously supplied to the bearing gap, when the journal rotates, the lubricating oil rotates with it, and in the gap on the right side, the lubricating oil is brought from the wide port to the narrow port. Since the inlet oil volume in this gap is greater than the outlet oil volume, the lubricating oil will accumulate in the narrow wedge-shaped gap and the oil pressure will rise. When the oil pressure in the clearance exceeds the load on the journal, the journal is lifted. After the journal is lifted, the clearance increases, the oil pressure decreases, and the journal falls again, until the oil pressure in the clearance and the load balance, the journal rotates stably at a certain position. At this time, the journal and the stainless steel bearings bush are completely separated by the oil film, forming liquid friction.

The working principle of steam turbine thrust bearing

The structure of the custom designed bearings is to install several thrust tiles on the front and back of the inference disk. We generally call the working tile on the generator side, which mainly bears the positive axial thrust, and the other side is called the non-working tile. Watts, mainly to withstand the sometimes instantaneous reverse thrust. After the steam turbine rotates, the lubricating oil rotates with the thrust plate and enters the gap between the thrust plate and the pad. When the rotor generates axial thrust, the oil layer in the gap is under pressure and transmitted to the thrust pad. Eccentrically supported, the force is deflected, which forms a wedge-shaped gap with the thrust disc; as the turbine speed increases, an oil film is established. At this time, the thrust disc and the thrust pad are completely separated by the oil film. Liquid friction is formed.