The cause analysis and countermeasures of thrust bearing surface burning

The cause analysis and countermeasures of thrust bearing surface burning - 2020 08 - 22 five units of a certain power plant DG270140B boiler feed water pump, high pressure between the pump and motor using elastic coupling of synthetic, often occurs in the operation of the motor bearing auxiliary thrust surface wear burning phenomenon, loss of lateral thrust tile are pump, and the accident occurred in the pump start-up moment. To solve such problems, after repeated practice and analysis, finally found the reason, and formulated the operation specification and the technical retrofit scheme, obtain good effect. The cause of motor thrust bearing surface burning loss according to the laws of the failure and the structure characteristics of the pump, we think the cause of motor thrust bearing surface burning is due to the pump rotor runtime large axial thrust instantaneous effect on motor thrust bearing surface. The axial force was passed by the elastic coupling of synthetic. Below for detailed analysis of this view. Pump rotor axial force balancing device is shown in figure 1, the pump starts, due to the stress balance room has not yet been established, the balance disc, thrust disc axial force balance role temporarily, after the balance room set up pressure, thrust plate only play a supplementary role, thrust plate and auxiliary driving face the gap between the 2 mm, auxiliary surface play a pump shut down the limit of rotor axial displacement of the largest negative effect, the maximal displacement value of 2 mm. When pump idle away after the shutdown process, the rotor in the balance of chamber pressure and pump fluid flow under the action of inertial forward, to the high pressure pump rotor end up still, thrust disc is clingy auxiliary push and stop, and due to the coupling transmission torque is small, idle walk between the two with the pump and motor can pass through the friction of synthetic axial force is small, the motor rotor basic axial position in the run will stop, in this way, every time after stopping the pump, the motor rotor and the pump rotor in axial distance of about 2 mm. The pump is started again, because the starting torque is large, two and a half of the friction between the wheel is very big, when the pump rotor balance disc to be near balance board up to low voltage side, will drive the motor rotor to move away from the direction of the pump. So after stop repeat many times, the distance of the two rounds of S ( See figure 2) Gradually increased, until before the start of motor rotor has been parked in the axial limit position, the motor shaft thrust plate already stick motor thrust bearing surface ( See figure 3) 。 And if in this case the feed water pump, the balance disc and thrust plate has yet to play a role, the axial force of pump rotor will be through the coupling to the motor rotor, causing the motor thrust face burned. Because of the failure is a prerequisite for the pump, after many start-stop motor and pump rotor axial distance increases to limit position, start the pump and in this case. Aiming at this characteristic, is the most simple force, method to avoid this problem in the pump before the start of each time, human will be resumed the distance between the pump and motor rotor to the standard position ( Figure 2 S = 5 ~ 7 mm) 。 This avoids the limiting case, to avoid the failure. The radical way to solve this problem is to improve the coupling. Due to the action of external force stop the pump when the pump rotor axial channeling move to high end, and the motor idle when the axial force is small, as long as the chosen type coupling will end in order to ensure the pump and motor rotor axial distance between in many times after start-stop still conform to the standard operation. To facilitate the installation, we please zhengzhou institute of machine tool design and manufacture the gear coupling, as shown in figure 4 when installation does not need to do any changes on the original equipment foundation. Effect after more than three years to test and use, method 1 can meet the requirements, but more trouble, for an additional operator workload; Method 2 after 3 years of trial, the effect is very ideal. （ Source: web)