Analysis of the reasons for the rise in turbine thrust tile temperature?

Is the bearing alloy damaged? Is the lubricating oil temperature and oil pressure also affected? It doesn't matter if the bearing oil inlet temperature is high or the oil is low.

The reasons for the increase in temperature of some bearings may be:: 1. The bearing oil inlet pipeline is blocked and the bearing alloy is damaged. ； 2. The joint surface is uneven and the bearing clearance is too small. ； All causes of increased bearing temperature: 1. The oil pressure is too low and the oil volume is reduced, such as oil pipe rupture, blockage, or oil pump failure. ； 2. The cooling water is interrupted, the cooling water pressure drops, and the cooling water pipeline is blocked, causing the oil temperature to be too high. ； 3. Poor lubrication and changes in oil quality ；

1 Check whether the temperature measuring point is damaged. 1 Cause analysis 1.1 The automatic return capability of the radial combined thrust bearing is poor. Unit 4 is the last unit of this type produced by Shanghai Steam Turbine Factory, and the spherical surface processing accuracy of its radial combined thrust bearing is low. Defects such as high spots and pits can be found during maintenance, so that when the rotor lift changes with the load, the bearing cannot flexibly adjust its position according to the changes in the rotor lift, resulting in the top and bottom pads of the thrust pads being alternately stressed. Due to the concentration of stress, the temperature rises. When the load continues and the rotor lift decreases to a certain angle, the pressure that the top tiles can withstand reaches the limit, the oil film cannot be effectively established, and the temperature of the tiles continues to rise, causing the tile temperature to exceed the alarm value. In severe cases, it may even cause a tile burning accident. 1.2 Low machining accuracy There should be a high perpendicularity between the thrust pad plane of the radial combined thrust bearing and the horizontal center plane of the radial bearing, which generally must be less than 0.02 mm. The perpendicularity between the rotor thrust plate and the rotor axis line cannot be greater than 0.02 mm. If the verticality of any one of them is too large, the axial force transmitted by the rotor cannot be evenly carried on each tile of the thrust tile, causing concentrated stress on some tiles and causing an increase in tile temperature. To ensure the normal operation of the thrust pad under oil lubrication conditions, the minimum oil film thickness at the oil outlet must meet the design value (for example, the oil film thickness of the thrust bearing of a large unit is generally 0.03 to 0.07 mm). When the roughness of the thrust plate is high, the oil film may be destroyed, causing the bearing friction loss to increase. When the unit load increases and the axial thrust increases, the pressure on the thrust pads increases, causing the temperature of the thrust pads to rise. 1.3 The installation accuracy is not high. The parallelism of the thrust tiles is generally not greater than 0.02 mm. The relative height difference between the thrust tiles is generally controlled within 0.02 mm. If the flatness is not good and its deviation exceeds the minimum oil film thickness, it will destroy the oil film established between the thrust shoe and the thrust plate. If the relative height difference between the thrust tiles is large, some of the tiles will be stressed, causing the tile temperature to rise. 2. Treatment measures (1) Finely grind all thrust tiles. First, the thrust pads and the thrust plate are carefully ground, and then the thrust pads are assembled and ground against the rotor thrust plate, so that the contact area of ​​each pad is more than 75%, and the contact points are evenly distributed. After the thrust tiles are installed, measure the relative height difference of each tile and control it within 0.01 mm. Increase the oil wedge depth of the positive and negative thrust pads to increase the amount of oil inlet. (2) Use 500-mesh abrasive sand, red red powder and turbine oil to make a special abrasive, and finely grind the spherical surface of the radial joint thrust bearing to maintain high accuracy on the spherical surface and the spherical shell. The assembly gap between the bearing housing and the spherical seat is increased, thereby improving the self-positioning performance of the bearing housing, making each thrust shoe evenly loaded, and improving the total load-bearing capacity of the thrust shoe. (3) Adjust the thickness of the spring support gasket at the bottom of the radial combined thrust bearing spherical body to facilitate leveling of the middle plane of the bearing shell. (4) Adjust the installation height of the rotor front bearing to the design standard range. (5) Filter the lubricating oil and flush the entire lubricating oil system.

Load changes may also cause the temperature of the thrust bearing to increase.

Thermocouple problems Check and calibrate the oil supply temperature of each thermocouple. Check the pressure and flow of cooling water. If necessary, use a backup oil cooler. The amount of lubricating oil has decreased. Check the oil level of the oil storage and the working condition of the pump. Check the pressure difference before and after the lubricating oil filter, the opening of the oil system valve and oil leakage. Find out the cause and deal with it. The performance of the lubricating oil decreases. Perform a performance analysis of the lubricating oil. Replace the lubricating oil when the lubricating oil deteriorates. Dehydrate the oil when the water content in the oil is too high. The bearing clearance is too small or damaged. Check, repair or replace the bearing. The axial thrust increases or the thrust bearing is improperly assembled. Check the working condition of the steam turbine and eliminate factors that increase the axial force. Check the thrust bearing and eliminate defects. The amount of steam leakage from the turbine shaft seal is too large. Adjust the amount of steam leakage from the shaft seal. If necessary, replace the air seal. The unit is not properly aligned and re-center it.