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Method for reducing the grinding speed of MD mine wear-resistant multi-stage pump balance disc
Working principle of the balance plate of md mine wear-resistant multi-stage pump
The balance plate of the wear-resistant multi-stage pump for mines is used to balance the axial force. The working fluid is liquid. The centrifugal pump balance plate is mainly used to automatically balance the axial thrust. The working principle is that the pressurized liquid from the final stage flows into the cavity in front of the balance plate through the radial gap of the adjusting sleeve, and the cavity is in a high-pressure state. There is a balance pipe connected to the pump inlet behind the balance plate, and its pressure is approximately the inlet pressure. In this way, the pressure on both sides of the balance plate is not equal, and thus a backward axial thrust is generated, that is, the balance force. The balance force is opposite to the axial force, which automatically balances the axial thrust of the impeller.
When the axial thrust of the impeller is greater than the force of the balance disc, the pump rotor will move to the inlet side. Due to the effect of inertia, this movement will not stop at the balance position immediately, but will exceed the limit, causing the balance disc shaft Excessive reduction in the direction gap reduces the leakage, and the pressure in the front cavity of the balance plate increases, so the balance force on the balance plate increases, and exceeds the axial thrust of the impeller, pulling the rotor to the outlet side again. The same process is inertial, which increases the axial gap of the balance disc, causing the balance force to be less than the axial thrust, and the rotor moves to the side of the population. Repeat the above process. This process is automatic. When the centrifugal pump is working, the rotor always moves axially in a certain equilibrium position, but the amount of movement is very small, which is difficult to see from the appearance.
Method for reducing wear of balance disc of wear-resistant multi-stage pump for mine
1. Adopt a balance drum and balance plate combined device
There is no axial gap in the balance drum. The labyrinth seal/comb seal and the radial concave and convex grooves of the balance drum form a radial gap, which can play a better decompression effect. The high-pressure gas enters the balance after flowing through the radial gap of the balance drum. The cavity then enters the balance pipe connected with the inlet, so that the pressure in the cavity is always equal to or slightly higher than the inlet pressure to achieve the purpose of balancing the axial force.
2. Choose wear-resistant materials
md mining wear-resistant multi-stage pumps have many stages, relatively slender shafts and large static deflection, which are prone to collision between the rotor and fixed parts, resulting in unstable operation, increased vibration and noise, and premature damage to vulnerable parts . In order to overcome this defect, we require the manufacturer to increase the design size of the spindle on the basis of the original design, so that the rigidity of the spindle is greatly enhanced and the operation is more stable.
3. Reduce impurities in the conveying medium
Frequently clean the sedimentation tank or sump and filter to minimize the content of impurities in the conveying medium. According to the characteristics of the conveyed medium, wear-resistant, corrosion-resistant and friction-reducing coatings are adopted for the bonding surface of the balance plate and the balance ring of the multi-stage pump. At the same time, measures to reduce the balance backwater resistance are adopted to effectively reduce the chamber. Pressure greatly improves the reliability of the shaft seal and reduces leakage.
4. Balance the water pipe
md mine wear-resistant multi-stage pump balances the axial force by the balance mechanism in the pump, the balance liquid flows out from the balance device, and the balance liquid is connected to the suction section by the balance water pipe, or a short pipe is designed outside the balance room, and the balance liquid passes through the short pipe. Flow out of the pump. To ensure the normal operation of the pump, the balance water pipe must never be blocked.
5. Avoid cavitation
During the operation of the pump, it is necessary to ensure a sufficiently high water level to avoid excessive suction height, which can not only avoid cavitation, but also improve the efficiency of the pump.
6. The method of pre-tightening assembly
Aiming at the problem of out-of-stock rotation or micro-swing of the guide vane sleeve in the middle section of the md-type wear-resistant multi-stage pump for mining that has not been solved for a long time, we adopted the pre-tightening assembly method to completely solve it, reducing the vibration and noise of the pump, so that The pump runs more smoothly and quietly.
7. Strengthen the management of operation and maintenance, and strictly implement the operating procedures
Startup: Before starting the pump, turn the pump rotor to check whether the rotor is flexible; open the pump suction valve, close the pump outlet pipeline gate valve and pressure gauge cock to fill the pump with liquid, or use a vacuum system to remove the air in the suction pipe and pump; start After the motor is running normally, open the pressure gauge cock and slowly open the pump outlet gate valve until the pressure gauge pointer points to the required pressure.
Operation: During operation, you must pay attention to observe the meter readings, whether the bearing heating, filling water leakage and heating, and the vibration and sound of the pump are normal. If abnormal conditions are found, they should be dealt with in time; the change in bearing temperature reflects the assembly quality of the pump. The temperature rise of the bearing should not be higher than the ambient temperature of 35℃, and the maximum temperature of the bearing should not be higher than 75℃; there is a certain axial movement of the pump rotor during operation, and the axial movement should be within the allowable range. The clearance value between the end faces of the coupling; the impeller, sealing ring, guide vane sleeve, shaft sleeve, balance disc and other parts should be regularly checked for wear during the operation of the pump. If the wear is too large, it should be replaced in time.
Stop: Before stopping, close the pressure gauge cock and slowly close the outlet gate valve. After the outlet valve is closed, stop the motor, and close the suction valve of the pump after the pump has stopped.
The reason why the balance plate of the md type wear-resistant multi-stage pump can balance the axial thrust depends on the pressure difference between the two sides of the centrifugal pump balance plate, and can automatically maintain this by the change of the gap between the balance plate and the balance seat A pressure difference produces a balance between the balance force and the axial thrust, which is also the common principle of balancing the axial force of the balance disc of the domestic multi-stage centrifugal pump.