Application Research on Large Vertical Water Pump Oil Bearing Water-diversion Bearing

This bearing often fails during the application process, mainly as follows: (1) Since the cycle of circulating tube Pitot often break, the bottom of the bearing body rotating oil pan oil can not reach the tank, bearing and journal dry friction and damage; (2) the lower part of the bearing seal labyrinth ring seal leakage, less than water leakage, guide vane hub leakage of water level rise, exceeding the maximum allowable bearing damage caused by water bearing. Each pump has occurred such failures, an average of about 4 times per occurrence, up to more than 10 times, and often occurs in the drainage drought drought stage, had to repair the replacement bearing, and sometimes the unit must be all open, hanging out Because of short time, tight manpower and poor environment (the other units are still running), the quality of the repaired units is hard to be guaranteed, which often results in continuous failures, which seriously affect the reliability of the units and the equipment is in good condition Rate, increase maintenance costs and labor intensity. In view of the above, after the 3 #, 8 # pump oil lubricated bearings to water lubricated bearings before and after 1972, respectively, in 1996 and 1997 to conduct a comprehensive disintegration inspection, periodic overhaul. At that time, the pump had been operating for 15 years and had an operating hour of 50000h and an overhaul cycle of more than 7 to 10 years. During this period, the pump was in a good working condition (the other pump oil bearing had an average of 2 to 3 service intervals over a 15-year period) Wear only 1mm, unit reliability and pump bearing life are greatly increased, saving maintenance costs, and achieved good economic returns. In contrast, the fourth pumping station a bearing oil lubrication into a water-lubricated pump, in just over a year time, the bearing failure occurred three times overhaul, the most serious is the flood in 1991 during the flood tensions, bearing wear To the bearing body, the bearing body in turn pulled out the pump shaft pits 1 ~ 2mm deep dent, and the occurrence of blade husks. The reason why this happens, mainly to remove the shaft protection, the use of river water lubrication, and the larger the river sediment. In addition, the larger pump (D = 3.1m), the bearing radial force is also greater, is another cause of bearing damage. 4 large vertical water pump bearing water should be noted that the main problems Impeller diameter more than 2m vertical water pump oil lubricated bearings to water, with good reliability, low cost, easy installation and maintenance advantages. The bearing is also suitable for newly designed and manufactured large vertical pumps. However, because of the unbalanced radial force of rotating parts, the bearing capacity of non-metallic materials used in water-lubricated bearings is relatively poor compared with that of babbitt. The abrasion resistance and water quality of lubricants are very important. The following problems should be paid attention to when using them. 4.1 The use of pipe-type water lubrication structure Practice has proved that the pipe-type water-bearing lubrication can effectively prevent sediment into the bearings, using this structure, lubrication of water must have sufficient flow and pressure to ensure clean water lubrication. Hydrodynamic seal is set between the protective tube outside the pump body and the pump shaft. The concentricity of the pump shaft and the inner side of the protective tube with the pump shaft shall meet the requirements. Otherwise, the pump shaft sealing effect is not good, a lot of lubrication water leaks, and caused by water pressure can not be formed, and a large number of leaking can cause drainage, environmental problems, and even the effusion of water endanger the motor above. 4.2 Reasonable design of bearings To design a reasonable bearing, we must first determine a reasonable bearing design load. The actual load of the water pump guide bearing is composed of electromagnetic imbalance force of the supporting motor, mechanical unbalance force of rotating components of the unit and hydraulic imbalance force of the pump [3]. Through a comprehensive analysis of the factors affecting the bearing load, the author puts forward the method of determining the design load. Design load is determined, the choice of bearing and wear resistance of non-metallic bearing materials, bearing structure, especially the size of lubrication sink, to meet the pressure bearing area and bearing capacity of both the requirements. 4.3 to reduce the guide bearing load pump unit manufacturing and installation of mass error and the structure is caused by the pump bearing the root cause of load. The way to reduce the bearing load is as follows: to improve symmetry uniformity of motor air gap: to reduce the eccentric mass of the rotating parts; to set the pump shaft protection tube while eliminating the flow resistance of the pump shaft; to measure and adjust the blade angles to reduce the angle error; High-quality inlet channels reduce impeller flow non-axisymmetric. Especially when the unit is installed, the installation error should be reduced as much as possible. Attention should be paid to control the installation error direction so that the sub-loads acting on the bearings will be opposite in direction and offset each other, which can greatly reduce the actual working load of the bearing and prolong the service life of the bearing. 5 Conclusion Compared with the bearing, the use of large-scale vertical water pump protection of water-lubricated bearings, which can stop the pump pumping water sediment into the bearings, which not only has the advantages of investment and maintenance convenience and reliability, long working life . As long as the design is reasonable, to ensure the quality of lubrication water quality, pressure and flow, improve the quality of the installation, reduce the bearing working load, to ensure that the sealing performance between the pipe and the shaft seal, water pipe lubrication bearings in the low lift large vertical pump Promote the use of value.