A solution for heating when the bearing is in use

High bearing temperature is a common and harmful fault of rotating equipment, which will reduce the service life of the bearing and increase the maintenance cost. When the temperature rises faster and the temperature exceeds the standard, it will easily lead to unplanned outage or reduced load operation. The economic benefits have a great impact. Therefore, it is the guarantee for the continuous and safe operation of the equipment to quickly determine the cause of the fault and take appropriate measures to solve it.

Common causes of excessive bearing temperatures

1. The amount of fuel is not appropriate, too little or too much grease

The bearing housing should be refueled regularly as required by the job. After the bearing is refueled, sometimes the temperature will be high, mainly due to excessive refueling. At this time, the temperature continues to rise, and will remain unchanged after reaching a certain point, and then gradually decrease.

2. The grease added to the bearing does not meet the requirements or is contaminated.

The lubricating grease is not suitable for selection, and it is not easy to form a uniform lubricating oil film. The internal friction and wear of the bearing cannot be reduced, the lubrication is insufficient, and the bearing temperature is increased. When different types of grease are mixed, a chemical reaction may occur, causing the grease to deteriorate and agglomerate, reducing the lubricating effect. The contamination of the grease will also increase the temperature of the bearing, and the dust will fall into the process of adding grease, causing oil contamination, resulting in deterioration of the grease inside the bearing housing, which will damage the bearing lubrication and increase the temperature.

Therefore, suitable grease should be selected. The bearing box and bearing should be cleaned during maintenance, and the fueling pipeline should be checked and unblocked. Different types of grease should not be mixed. If other types of grease are replaced, the original grease should be cleaned first; Regularly add grease, grease should be properly kept to prevent moisture and dust.

3, cooling is not enough

Check if the pipeline is blocked, whether the inlet temperature and return water temperature exceed the standard. If the cooler is not suitable for use and the cooling effect is poor and cannot meet the requirements for use, it should be replaced in time or a new cooler installed in parallel. The axial flow induced draft fan should also check the insulation and sealing of the core barrel.

4. Confirm that there is no such problem and then check the coupling alignment and bearing

The alignment of the coupling must conform to the process standard. In the case of axial flow induced draft fans, hydraulic couplers, etc., the problem of thermal expansion of the equipment during operation should also be considered. The impeller side of the induced draft fan expands due to heat, and the bearing box rises. When the temperature of the hydraulic coupler increases, the bearing housing expands and the bearing rises. Therefore, the timing of the motor should be higher. The size of the reserve should be based on the characteristics of the equipment. Depending on the temperature parameters in operation.

The main inspection of the bearing is as follows:

1, the quality of the bearing

During the disassembly of the bearing housing, first, check whether the lubricating grease has deterioration, agglomeration, impurities, etc. This is an important basis for judging the cause of bearing damage. Secondly, check the bearing for bite and wear; check the smoothness of the inner and outer rings of the bearing, the rolling element, the surface of the cage, and whether there are defects such as cracks, rust, peeling, pits, thermal discoloration, etc., and measure whether the bearing clearance exceeds the standard; Whether the bushing has wear, pit or peeling, if necessary, replace the new bearing.

2, bearing cooperation

When the bearing is installed, the inner diameter of the bearing and the cooperation between the shaft and the outer diameter and the outer casing are very important. When the fitting is too loose, the mating surface will be called relative creep to be creep. Once creep occurs, it will wear out the mating surface, damage the shaft or the outer casing, and the wear powder will invade the inside of the bearing, causing heat, vibration and damage. When the interference is too large, the outer diameter of the outer ring becomes smaller or the inner diameter of the inner ring becomes larger, which reduces the internal clearance of the bearing. In order to select the suitable fit, it is necessary to consider the nature, size, temperature conditions of the bearing load, and the various conditions of the inner ring outer ring.

3. Adjustment of the matching clearance of each part of the bearing

When the bearing clearance is too small, the friction loss of the oil in the gap is too large, which will cause the bearing to heat up. At the same time, if the clearance is too small, the amount of oil will decrease, and it is too late to take away the heat generated by the friction, which will further increase the temperature rise of the bearing. . However, if the clearance is too large, the dynamic characteristics of the bearing will be changed, causing the rotor to be unstable. It is therefore necessary to select the verified bearing clearance for different equipment and conditions of use.