What is "steam turbine bearing"

Update:02-09-2021
Summary:

Turbine radial bearings are divided into two types: fix […]

Turbine radial bearings are divided into two types: fixed-pad bearings and tilting-pad bearings.
Fixed tile bearing
Fixed pad bearings include cylindrical bearings, elliptical pad bearings, multi-oil wedge and multi-oil leaf bearings (currently not widely used). Ordinary cylindrical bearings are composed of upper and lower halves. The outer circumference of the lower half of the bearing is provided with three radial adjustment pads, and the top of the upper half of the bearing is provided with a radial adjustment pad for bearing adjustment.
The elliptical bush bearing is a self-aligning bearing, which has the advantage of less layers in the structure. Babbitt alloy is directly poured on the inner surface of the bearing body to process the inner bush surface of the bearing into an elliptical form.
Tilting pad bearing
Four tilting pad bearings, on the back of the upper half of the two pads, there is a spring at the oil outlet along the turning direction, so that the pads have a tendency to press against the rotor at the back, and prevent the oil inlet side of the pads and the journal It produces a bad tendency of braking, and at the same time trims the slope on the oil inlet side of the tile surface to facilitate the entry of lubricating oil into the tile surface.
The upper half is a round tile and the lower half consists of two tilting pads. The stability of the bearing of this structure is stronger than that of cylindrical bearings. The bearing capacity is larger than that of ordinary tilting pad bearings. It has a pair of tilting pad bearings. The advantage of less sensitivity to eccentric load and misalignment.
At present, the relatively new type of tilting pad bearing with an oil inlet groove on the oil inlet side of the tile surface, the lubricating oil adopts the method of direct oil supply and oil discharge. Each tile has an oil inlet groove, and the lubricating oil is directly discharged after the tile surface is working, which has a small power consumption.
Classification of thrust bearings
Radial thrust combined bearing
The feature of this structure is that the radial and thrust bearings are integrated in one body, and the bearing bush body and the bearing sleeve are fitted with a spherical surface, so that the bearing can be adjusted automatically according to the deflection and deformation of the shaft. Better contact, this structure is suitable for units with flexible rotors and not too large axial load.
There is also a radial thrust combined bearing that is an elastic balanced pad. The thrust pad is placed on an elastic ring, and the elastic ring is elastically deformed during load, so as to meet the requirements of good contact between the surface of each pad and the plane of the thrust plate. This structure is used in units with rigid rotors and not too much axial load.
Kingsbury Thrust Bearing
The tiles are supported symmetrically, which can be used for the front and back steering work.
Overhaul of bearings
Contact check
The uniform contact area between the bearing housing and the bearing seat is greater than 75%, and the contact between each adjustment washer and the pad and between the adjustment washer and the pad is greater than 75%, and each tilting pad is more than 75% The corresponding mandrel is compounded, and the uniform contact area is greater than 80%.
If the bearing is in the correct position, rotate the bearing about 2 to 4 degrees along the radial line and axis. This movement should be carried out step by step. You can only move a little bit at a time in each direction to avoid rapid movement, otherwise the impressions will not reflect the actual The surface contact situation.
If the repair requires a lot of work: during rough repair, grinding is more efficient than scraping. It is important that the grinding should be done carefully to avoid geometric deformation of the shell. A flap wheel can be used to grind the spherical shell. The recommended particle size of the wheel is 160-180. A scraper is recommended for finishing.

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