A slurry pump is a kind of large centrifugal pump, which is mainly used for conveying a medium containing abrasive solid particles. It is indispensable universal equipment in mining, chemical, coal, and metal smelting industries.
The failure of the slurry pump is not only related to the harsh conditions of production but also has a great relationship with the daily maintenance and repair quality of the equipment. In order to reduce the failure rate of the slurry pump and improve the utilization efficiency of the equipment, it is necessary to use the slurry pump correctly and formulate a suitable maintenance plan.
Cause Analysis of Common Slurry Pump Failures
Because the slurry pump is the most widely used general-purpose mechanical equipment, it is used in various industries. Since the working conditions of these industries are not the same, the equipment failures under different application conditions are also different, but most of the failures are the same as the original equipment.
1. No material at work
The failure of the slurry pump to run or not to discharge smoothly is a failure encountered in almost all industries where the slurry pump is used. After the first commissioning or overhaul, the slurry pump does not run. The replacement of spare parts is related, mostly because the feed level of the slurry pump is too low or the steering error after the pump is running.
The main reasons for the sudden failure of the slurry pump to not discharge material under normal working conditions are as follows:
(1) Blockage of the blade passage or pump inlet/outlet The sudden failure of the slurry pump to discharge material under normal working conditions is largely caused by the blockage of the blade passage of the impeller or the inlet/outlet pipe of the pump. Because the slurry transported by the slurry pump contains a lot of solid particles, some of these solid particles have large diameters, and the slurry generally has strong coagulation and is easy to scar, and another flexible foreign matter is mixed, which will affect the normal entry of the slurry. The pump cavity, impeller, or inlet and outlet pipelines are blocked, which also makes it difficult for the pulp to obtain the energy transmitted by the impeller. After such a fault occurs, there will be some abnormal noises in the pump cavity, and the current of the motor will also show a significant downward trend.
(2) The occurrence of cavitation is related to the blockage of the impeller of the slurry pump or the inlet of the pump. The blockage of the impeller or the inlet itself will affect the discharge of the slurry pump, and the occurrence of cavitation not only leads to The poor discharge of the pump but will further aggravate and will also generate noise and serious vibration, which will cause the overall performance of the slurry pump to decline seriously, which will interrupt the discharge of the pump, and the motor current will jump significantly.
(3) Serious wear of the flow parts The wear of the main flow parts of the slurry pump has a certain gradual process, and with the gradual wear of these flow parts, the performance of the pump will gradually decline. Due to the wear of the overcurrent parts, the failure of unsmooth discharge has a long period, and the operation of most slurry pumps will be too stable, and the motor current is in a very low but stable state.
2. Severe vibration of the slurry pump
Vibration is an inevitable phenomenon that occurs when the equipment is running. It can be divided into different levels according to the severity of the vibration. The vibration of the equipment that does not exceed the level range is a normal phenomenon. If the equipment has exceeded the normal vibration level, it will directly affect the equipment. Stable operation.
There are many reasons for the serious vibration of the slurry pump. Generally, there are the following aspects:
(1) The impeller of the impeller eccentrically loaded slurry pump has undergone dynamic balance alignment treatment before leaving the factory, and the quality of each part is relatively uniform, but after the long-term operation, certain wear or adhesion will occur, which is to a certain extent. This leads to the eccentric load of the rotating parts of the slurry pump. After the slurry pump is running, the eccentric load causes a seriously unbalanced rotating force and causes the slurry pump to vibrate.
(2) Loosening of fixed bolts The slurry pump relies on multiple anchor bolts to connect with the foundation, and at the same time, the various components also rely on bolts to maintain the stable state of the pump. Due to the existence of equipment vibration, the slurry pump will gradually lead to these problems after long-term operation. The loosening of the fastening bolts will cause the slurry pump to intensify the vibration due to the loss of the restraint of the fixing bolts, and at the same time, the vibration of the equipment and the further loosening of the bolts, and the wear of the components form a vicious circle.
(3) Insufficient bearing lubrication or substandard lubricating oil grades Good lubrication of the equipment can not only reduce the wear of parts but also the oil film formed by the lubricating oil between the two parts can absorb a large part of the vibration. When the slurry pump rotates at high speed, the lubricating oil will form a sufficient oil film between the rolling elements of the bearing to reduce the vibration value. If the slurry pump is insufficiently lubricated or the grade of the lubricating oil is not up to standard, the viscosity is insufficient, and it is difficult to form an effective lubricating oil film between the bearings, or the lubricating oil film ruptures prematurely, which will cause serious vibration of the slurry pump and cause serious bearing wear.
3. Shaft seal leakage
Shaft seal leakage is the most common failure of slurry, especially in the petrochemical industry, more than 80% of pump failures come from shaft seal leakage, so the treatment of shaft seal leakage will determine the utilization rate of the pump and the cost of maintenance. In the leakage failure of the shaft seal, more than 65% of the failures are caused by the poor sealing of the seal end face caused by the scaling of the compression spring and the cooling water. Therefore, the key to preventing the leakage of the shaft seal is to soften the cooling water of the shaft seal. , reduce the speed of cooling water scaling.
Maintenance of Slurry Pump
Due to the poor working conditions of the slurry pump, to ensure the long-term stable operation of the slurry pump, it is necessary to properly maintain and maintain the slurry pump to minimize the influence of working conditions.
(1) Check the amount of lubricating oil in the bearing bracket of the slurry pump every day during operation to ensure that the oil level is 2mm above and below the oil level line, and replace the lubricating oil regularly. It can be replaced according to the actual situation of the lubricating oil.
(2) Regularly check and tighten the bolts of the foundation and the pump casing. When the equipment is disassembled, inspected and reassembled, apply an appropriate amount of thread locking agent on the bolts to avoid loosening of the bolts. If the production conditions permit, the inlet and outlet pipes of the pump can be regularly inspected. Check and clean the pipeline and pump cavity to ensure that the pipeline is unobstructed.
(3) Regularly clean the equipment to keep the equipment clean, dry, free of oil and leakage. If the shutdown time is long, the sediment in the pump should be flushed to prevent the medium sediment from affecting the next start and operation.
The utilization efficiency of slurry pumps and other mechanical equipment is closely related to the reasonable selection of equipment, the correct judgment and treatment of faults, and whether the daily maintenance and maintenance of equipment are correctly implemented. Processing and timely maintenance require equipment practitioners to summarize and analyze the faults that are constantly exposed by the equipment, and formulate corresponding treatment plans and maintenance cycles. Implementing it is a prerequisite for improving the efficiency of equipment operation.
