The abnormal vibration of the suction dredge pump is the main cause of other failures. At the same time, the failure of the equipment will aggravate the vibration of the equipment, resulting in a vicious cycle, which will seriously affect the safe operation of the imaging equipment, and thus bring corresponding maintenance costs, as well as production losses caused by equipment failures. So what causes the dredge pump to vibrate? What are the dangers of dredge pump vibration? How to prevent and solve dredge pump vibration?
1. Cause analysis of dredge pump vibration
1. Mass imbalance of impeller
The centrifugal force generated by the mass imbalance of the impeller always acts on the dredge pump. When the equipment leaves the factory, due to the corresponding inspection and adjustment of various spare parts of the dredge pump, especially the static / dynamic balance detection and drilling / milling alignment of the impeller, the position of the mass imbalance will be processed. At this time, the impeller is in the relatively best mass balance state, so the dredge pump is also in the most stable state at this time, The vibration of the equipment is also slight. However, after a long time of operation, due to the wear of the impeller and the scabs caused by the adhesion of sand slurry, the overall mass balance of the impeller will be broken, and the corresponding “eccentric load” of the impeller will occur. At this time, the centrifugal force on the heavier side of the dredge pump impeller will increase, especially when the suction dredge pump rotates at high speed, the eccentric load impeller will cause serious unbalanced rotating force. At this time, it will be found that the vibration amplitude gradually increases from the motor end to the pump end.
2. Vibration fault caused by coupling
The vibration caused by coupling is common in dredge pumps, especially the rigid coupling. The vibration of motor and pump produces resonance phenomenon in the transmission of coupling, which leads to the intensification of vibration. Even the pin coupling, which is common in dredge pumps, will produce violent and transient vibration because the pin / rubber ring and other components cannot meet the axial movement, although the failure of coupling will also cause the vibration of pump. But it is far less than the vibration caused by impeller failure. The coupler will also be leveled in the later stage after fabrication. Coupling leveling and impeller leveling are also to minimize the unbalanced force generated during rotation. However, in addition to its own mass alignment, the balance of the installation and coordination of the two couplings should also be considered.
In addition to the balance of its own mass, the balance of a pair of couplings must also meet the following two conditions:
1) Make the centers of two pairs of wheels coincide, that is, make the outer circles of two pairs of wheels coincide.
2) Make the joint surfaces (end faces) of the two pairs of wheels parallel (the two centerlines are parallel).
In addition to the above two reasons, the suction dredge pump vibration has the following reasons:
- Vibration caused by loose fastening bolts
- Vibration caused by bearing wear or insufficient lubrication
- Equipment failure caused by unstable feeding
2. Harm of suction dredge pump vibration
1. Affect the service life of each spare part of the dredge pump
According to relevant statistics, equipment failures caused by dredge pump vibration account for 74% of equipment failures. During the operation of the pump, due to the imbalance, the centrifugal force increases the load of the bearing, and the vibration beyond the allowable range of the dredge pump will cause the lubricating oil film on the surface of the bearing rolling element to be damaged prematurely, and the bearing cannot be effectively lubricated and dissipated, resulting in the accelerated damage of the bearing temperature rise.
2. Damage and leakage of mechanical seal
The vibration of the suction dredge pump will cause the sealing end face of the mechanical seal to be unable to stably fit and operate, resulting in slight material loading in the early stage. The vibration of the mechanical seal will also cause sand slurry particles to be mixed in the friction process of the two end faces, resulting in the early damage of the sealing surface.
3. Wear and leakage of pump body
In order to improve the working efficiency of centrifugal pump, the clearance between spare parts inside the pump cavity such as impeller, front / rear guard plate, volute and other components is designed to minimize the clearance between components (under the same conditions, the smaller the clearance, the higher the efficiency of the pump). Vibration will lead to the movement of the pump transmission shaft and the beating of the shaft head. This movement will do great harm to the components inside the pump cavity, and will also lead to the impact or wear of the guard plate and the impeller. This situation will lead to the damage of some spare parts, which will make the pump lose its working capacity or reduce the use efficiency, and the joint surface will leak due to the friction force of each spare part inside the pump cavity.
4. Equipment energy consumption increases
The vibration of the suction dredge pump will produce additional friction loss and uneven centrifugal force, which will not only reduce the stability of the pump operation, but also reduce the pump operation efficiency, increase the reactive work, and produce higher power consumption.
5. Shaft breakage
The vibration of the pump will cause the impeller to produce unbalanced centrifugal force, which will make the impeller at the end of the shaft always in an unbalanced state, resulting in excessive stress on the shaft. Long term operation will inevitably produce metal fatigue and lead to shaft failure.
3. Prevention and treatment of pump vibration
- The working conditions and working environment of the suction dredge pump are generally bad, so the failure rate of the dredge pump is often relatively high, which requires that the equipment with higher specifications should be selected as far as possible on the premise of meeting the production technical requirements, and at the same time, a good working environment should be ensured during feeding.
- The centrifugal pump will produce partial cavitation during operation, especially in the case of insufficient feeding, which will aggravate the vibration of the pump. The vibration caused by short-term cavitation is caused by the uneven distribution of liquid in the pump cavity. By stabilizing the feeding of the centrifugal pump or adjusting the speed of the outlet valve pump, the vibration of the pump can be effectively eliminated.
- Lubrication should not only consider the oil level and quantity of lubricating oil, but also consider the viscosity of lubricating oil. When the viscosity of the lubricating oil is insufficient, the centrifugal pump will also produce vibration. When the centrifugal pump is running, the temperature of the bearing box will rise. When the temperature rises, the viscosity of the lubricating oil will decrease. Therefore, when detecting the oil level and quantity of the equipment, it is also necessary to ensure that the temperature of the equipment is within the appropriate range. When the temperature of the equipment rises, the reason should be found out in time, otherwise the bearing will also be vibrated and damaged due to poor lubrication.
- In the “slight vibration” state, the bolts will loosen. When reinstalling the equipment after maintenance, you can apply some thread locking agent on the bolts, which can not only prevent the loosening of the bolts, but also prevent the damage of the bolts. When disassembling, you can melt the locking agent only by heating. Although the investment is small, it is essential for the reinstallation of the equipment.
- Stable feeding. In addition, sedimentation, scarring and large particle blockage in the slurry at the later stage of use will cause the feeding process to fail to meet the flow requirements of the suction dredge pump, so it is necessary to clean the pipes and valves. Control the flow by adjusting the outlet valve, not by adjusting the inlet valve.
Through this article, we understand the causes and hazards of pump vibration, as well as preventive measures when vibration occurs. Hope this article is useful to readers.
4. About Ocean Pump
Tai’an Ocean Pump (OCEAN Pump) Co., Ltd. is the leading dredge pump and sand dredger solutions manufacturer, supplier and exporter in China. We have more than 30 talented dredge pump experts and 15,000 square meters factory. More than 4 series 20 kinds of dredge pumps, dredge pumps, sand dredgers and related parts had been manufactured to satisfy your pumping requirements. OCEAN Pump is the Certification of New Hi-tech Enterprises by the Government. We provide our customers with a complete set of sand, slurry, gravel pumping solutions and related parts. Our main products include centrifugal portable dredge pump, marine dredge pump, dredge pump, suction dredging pumps, gravel pump, mud pump, submersible dredge pump, vertical dredge pump, simple small dredge pump dredger, submersible dredger, mini dredge for sale, small dredging equipment, small pond dredging equipment, sand suction dredger, suction dredging equipment, cutter suction dredger , sewage submersible pump, lake dredging equipment, mini dredges for sale, sand dredging machine, river dredging equipment and other parts like discharging sand pipe, floater, rubber hose. They are widely used in mining, metallurgy, coal washing, power plants, sewage water treatment and dredging in such industries as mine, chemical and petroleum. We are looking for pump dealers all over the world.
