Slurry pump is a common machinery that uses centrifugal force to increase the energy of solid-liquid mixed media, mainly used in mining, metallurgy, construction and other fields. As a common practical auxiliary tool, there are three common problems in the use of slurry pumps, which are unstable flow, cavitation, and seal failure, leading to slurry leakage problems. So, how can you solve such problems? Now let's popularize science!
1、 How to solve the unstable flow of slurry pump?
The reasons for the unstable flow rate of the slurry pump are roughly as follows:
1. Leakage of the suction pipe or bottom valve, or blockage of the inlet, are common reasons for insufficient flow. It is necessary to check the source of air leakage in the suction pipe and bottom valve and promptly block it, or clean the sludge or blockage at the inlet.
2. Low voltage leads to a decrease in the speed of the slurry pump, resulting in insufficient flow rate of the slurry pump. At this time, the power supply voltage should be checked and adjusted in a timely manner.
3. If there is a leak in the pipeline or air in the pump body, the air in the pipeline should be discharged in a timely manner.
4. Severe wear of sealing rings or impellers can also lead to unstable flow of slurry pumps. It is necessary to promptly inspect and replace severely worn sealing rings and impellers.
5. The depth of the bottom valve entering the water is insufficient, resulting in air entering during pumping. The depth of the bottom valve should be adjusted according to the suction stroke of the slurry pump.
6. If the slurry pump works normally after starting for a period of time, but the current gradually decreases and the flow rate is significantly insufficient, and this problem still occurs after restarting and running normally for a period of time, it is mostly due to the accumulation of slurry or other debris in the suction pipe, causing cavitation of the slurry pump. In severe cases, the slurry pump will make a loud noise and the pump head vibration will be obvious. At this time, the front pool and suction pipe should be thoroughly cleaned, the length below the elbow should be reduced, or the mixing device should be added to reduce slurry settling.
2、 How to solve the cavitation phenomenon of slurry pump?
At a certain temperature, when the liquid pressure drops below the saturation pressure, boiling gasification occurs, which is a characteristic of the liquid itself. At a certain temperature, the saturation pressure is constant and increases with the increase of temperature.
For centrifugal pumps such as slurry pumps, reducing the suction pressure is necessary to allow the liquid to be drawn into the pump. When the suction pressure is lower than the saturation pressure corresponding to the water temperature, the liquid sucked in will undergo gasification reaction. The bubbles formed by gasification gather at the lower pressure position inside the slurry pump, which is the back of the blades above the impeller inlet. As the surrounding liquid flows outward, the impact of the liquid can cause noise and vibration, which can eventually erode and damage the impeller.
Generally speaking, measures to solve cavitation phenomena include:
1. Control the suction liquid level pressure to prevent the liquid level pressure from being too low.
2. Control the suction flow rate to ensure that the slurry pump operates at the specified pumping rate.
3. Reduce the installation height of the slurry pump appropriately.
4. The suction valve should be fully open and the filter screen should be cleaned regularly.
3、 How to solve the sealing failure of slurry pump?
At different stages of operation, the causes of seal failure in slurry pumps vary. Next, we will analyze them one by one.
1. Leakage of slurry pump during assembly process
During the installation process, slurry pumps are prone to problems. Generally, static pressure tests are required to observe whether the slurry pump leaks. When the leakage is small, there may be problems with the sealing rings of the dynamic or static rings. If the leakage is large, it may be due to friction between the dynamic and static rings. Leakage medium is sprayed along the axial direction, mostly due to the problem of the dynamic ring seal. If the leakage medium sprays outwards or leaks out from the water cooling port, it is mostly due to the problem of the static ring seal. At this time, careful observation should be made to determine the problem and make timely adjustments.
2. Leakage during the trial operation of the slurry pump
After the static pressure test, the reason for the leakage of the slurry pump is generally caused by the damage of the dynamic and static ring friction pairs. There are many reasons that can cause this phenomenon, generally including axial force caused by abnormal phenomena such as cavitation, evacuation, and pressure build-up, excessive compression during seal installation, tight or loose dynamic or static ring seals, and particles entering the friction pair in the working medium. The main solution is to disassemble and replace the seal.
3. Sudden leakage during normal operation of slurry pump
This situation is rarely caused by normal wear and tear or the slurry pump reaching its service life, but mostly due to changes in operating conditions or improper operation and maintenance. The main reasons include: cavitation or prolonged pressure holding, insufficient actual output, interruption of sealed cooling water, prolonged shutdown without turning, increase of corrosive, polymeric or adhesive substances in the medium, severe temperature changes in the working environment of the slurry pump, frequent adjustment of working conditions, etc. During the use of the slurry pump, attention should be paid to the usage standards. Before use, the shaft seal water must be connected, and the pump can only be turned off after stopping for five minutes. When the pump is stopped for a long time, the pump chamber and mechanical seal need to be cleaned with clean water before stopping. When restarting, manual turning is required to extend the service life of the slurry pump.
Above, we have summarized some common problems in the use of slurry pumps. To avoid the occurrence of problems during use, the usage process of slurry pumps should be standardized, and regular inspections should be carried out. In case of abnormal situations, the cause should be identified and adjustments should be made in a timely manner to ensure the normal use of equipment and the normal operation of the plant.