Temperature control of thrust bearings with elastic metal-plastic segments

Abstract

1. When the usual segments with a babbitt coating are replaced by EMP segments with a fluoroplastic coating, the temperature on the friction surfaces does not substantially change if the areas of the friction surfaces remain approximately equal. 2. The temperature of the body of EMP segments at a distance of 20–30 mm from the friction surfaces (at the place of installing the temperature monitoring sensors) decreases in comparison with the usual segments by as much as 30° due to the worse thermal conductivity of fluoroplastic in comparison with babbitt, and in the case of a considerable reduction of the area of the segments, also due to a decrease of friction losses in the bearing. 3. An increase of the scatter of the temperature of EMP segments in comparison with babbitted segments in the bearings of units at some hydrostations is explained by the fluoroplastic coating of the EMP segments in these cases (of jointed fluoroplastics sheets). As a result of this hot oil passes from the oil film through leaks of the joints on individual segments under the fluoroplastic, causing additional heating of the temperature sensors. 4. The experience of operation and investigations showed that as a result of the increased life of the EMP segments and their other positive features, the existing temperature monitoring with placement of the sensors 20–30 mm from the working surface is sufficient for timely detection of disturbances on the working surface of the segments. 5. In bearings with EMP segments under a specific load up to 7 MPa it is sufficient to have the usual temperature protection system with placement of the sensors in 2–4 segments, as well as the usual periodic visual monitoring system. In this case, in bearings on a hydraulic support the visual temperature monitoring sensors should be installed in each segment, regardless of their number; in one-row bearings on a fixed screw support — each segment when their number is 12 and less or in half of the segments (every other one) when their number is more than 12; in two-row bearings — 1/3 of the bearings (every other two) of each row. 6. In bearings under a specific load of more than 7 MPa the temperature sensors both for visual monitoring and for protection should be installed in all segments, regardless of their number and type of bearing. 7. Measurement and recording of the temperature of the EMP segments from the visual monitoring sensors should be carried out regularly at least 3 times a day. During the first start after maintenance or inspection, during which the bearing is exposed, the temperature should be continuously monitored (with a small interval between measurements) until steady values of the temperature under the full load of the generator.