Shanxi submersible pump to solve the cavitation phenomenon of water pump

Shanxi submersible pump how to pump to solve the cavitation phenomenon of water pump, pressure reduction is the condition of cavitation, there are a large number of bubbles in the water rapid rupture is the internal cause of cavitation. Therefore, in order to improve and reduce the cavitation damage of the main drainage pump impeller in coal mines, it is necessary to increase the inlet pressure of the pump.
1. Causes of cavitation
When the absolute pressure at the pump inlet is reduced to the cavitation pressure at the current water temperature, the water vaporizes. The water forms a gas at the water inlet, so that many small bubbles form at the water inlet. When these small bubbles flow into the high-pressure zone with the water, the bubbles burst rapidly, and the surrounding liquid immediately fills the original bubble cavity. Because the bubble burst time is very short, the hydraulic impact of up to several hundred MPa is formed. Bubbles continue to form and rupture, the huge hydraulic impact to tens of thousands of times per second frequency repeatedly acting on the impeller, a long time, it will make the impeller blades gradually due to fatigue and peeling; at the same time, the bubble is also mixed with some active gas (such as oxygen), the smooth layer of metal due to electrolysis and gradually become rough. After the metal surface roughness is destroyed, the mechanical ablation is accelerated. In addition, in the process of bubble formation and rupture, the temperature difference between the two ends of the over-current component will be generated, and the cold end and the hot end will form an electric couple to generate a potential difference, so that the metal surface will be electrolyzed, and the smooth layer of the metal will gradually become rough due to electrolysis. Under the combined action of mechanical denudation, chemical corrosion and electrochemistry, the metal surface will soon appear honeycomb pitting, and gradually form a void and damage, this phenomenon is called cavitation.
2, Shanxi submersible pump cavitation phenomenon occurred after the serious impact on the pump
When the cavitation develops to a certain extent, it will affect the performance of the water pump and hinder its normal operation. Mainly for the following aspects:
(1) The performance of the pump changes when the cavitation is born, it has no obvious effect on the external characteristics of the pump. After cavitation develops to a certain extent, the power, efficiency, flow and head of the pump will suddenly drop. When the cavitation is fully developed, the effective flow area of the water flow will be reduced a lot, so that the water flow is interrupted and cannot work.
(2) caused by vibration and noise bubble rupture, the liquid particle impact each other, resulting in noise and unit vibration, the two mutual excitation so that the pump produces strong vibration, known as cavitation resonance phenomenon.
(3) the damage of the surface of the over-flow parts will greatly shorten the life of the pump. When the erosion and corrosion are serious, it will produce major accidents such as blade fracture or perforation.
3, Shanxi submersible pump impeller wear experimental analysis.
Using the method of painting on the impeller blades, the location and degree of impeller damage are qualitatively analyzed. Experimental conditions: wear experiments are carried out with clean water in the case of cavitation. After the pump runs for 10h under the above two conditions, the damage of the impeller is observed and analyzed. In practical application, the most serious damage to the impeller of the main drainage pump of coal mine is the inlet pressure surface and the suction surface of the blade. The material of the blade is peeled off to form pits, and even the blade is seriously peeled off: the pressure surface of the blade outlet is also worn seriously. The rear cover panel is uneven from the blade inlet to the middle of the blade, and is damaged to varying degrees. Practice has proved that only the inlet end of the blade with paint has obvious solid particle friction traces, and the entire impeller blade flow channel has no cavitation points. In the case of cavitation loss, the paint at the blade inlet end, blade inlet pressure surface and blade outlet pressure surface has relatively serious friction traces of solid particles, especially the large area of cavitation points on the blade inlet suction surface, which are basically consistent with the actual damage of the impeller of the main drainage pump in the coal mine in the damaged position and extent, and the degree is better than that without cavitation. The experiment of clear water under condition 2 has no wear marks, only cavitation points, and the degree of cavitation is much smaller than that of sand-laden water, indicating that the sand-laden mineral water expands the scope of cavitation. It can be seen that under the same fluid medium conditions, the damage when cavitation occurs is more serious than that when cavitation does not occur; under the same cavitation conditions, the medium with solid particles is more serious than that without solid particles. Therefore, cavitation is the main cause of damage to the impeller of the main drainage pump in coal mines, eliminating cavitation can reduce the damage of the pump, and eliminating solid particles in the water can reduce the damage to a greater extent. The experimental results show that although it is not clear whether cavitation is related to the size of solid particles, it can verify the objective existence of damage.