First, improve the anti-cavitation pump performance
1, reduce the necessary NPSH
(1) Double suction impeller pump . As the double-suction pump NHA Δhc than single-stage single-suction pump NPSH Δhc small, for the same speed n and flow Q pump, try to use double-suction impeller.
(2) Appropriate to increase the impeller inlet diameter and increase the width of the blade inlet. When the impeller inlet diameter and blade inlet width increases, the impeller inlet absolute velocity and relative velocity decrease, we can see that the pump's critical NPSH decreases. However, at this time, the area of ​​the leakage ring at the inlet of the impeller is increased, the amount of leakage is increased, and the volumetric efficiency of the pump is reduced.
(3) Impeller before the introduction of induction. Set the inducer in front of the centrifugal pump impeller. Induction wheel and pump leaf operation, the resulting pressure wheel co-operation with the coaxial assembly, the pressure generated by the impeller inlet pressure to improve the pump anti-cavitation performance. However, the introduction of induction wheel will make the pump performance instability, therefore, still need to be further exploration and research.
2, to improve the anti-cavitation material flow components Over-flow components in order to reduce cavitation damage to the pump to extend its life, often use strong anti-cavitation material. Such as the use of cast manganese, bronze, stainless steel and alloy steel casting impeller; or polymer coating or laser spraying over-flow parts surface to resist cavitation damage. In addition, the flow of parts surface finishing, improve its finish, but also reduce the risk of cavitation.
Reduce the pump cavitation approach Second, improve the anti-cavitation ability of the water inlet device
The NPSH is closely related to the water inlet device and piping system. Therefore, a well-designed water inlet device should be designed to improve the NPSH of the pump inlet as much as possible so as to meet the requirements of dynamic pressure drop in the pump.
(1) reasonable to determine the water pump height. As the pumps are generally operating under non-design conditions, should take full account of the pump may encounter a variety of working conditions, the determined water absorption height in any condition should meet the water pump performance requirements.
(2) Matching a reasonable water inlet pipe. As far as possible to reduce the length of the inlet pipe and unnecessary pipe fittings, increase the inlet pipe diameter, to reduce the water loss of the inlet pipe to improve the pump inlet NPSH. For large and medium-sized axial-flow pumps, the water flow rate and pressure in the water inlet pipe should be distributed as evenly as possible to prevent cavitation.
(3) well-designed intake pool. A good inlet not only reduces the drop of the water level in the pool, but also reduces the drag coefficient of the inlet, and the water in the pool is stable and does not produce eddies. Air can be prevented from entering the pump to prevent cavitation from occurring prematurely.
3, operational management can take measures
(1) try to make the pump running in the design conditions annex. Pump stations can follow the specific conditions, the use of variable valves, variable speed, variable angle and other regulatory measures to prevent the pump operating conditions deviate from the design conditions too far.
(2) control the pump actual speed higher than the design speed range. As the NPSH must be proportional to the square of the rotation speed, when the rotation speed is too high, not only the NPSH must be increased greatly, but also the effective NPSH should be reduced.
(3) pump cavitation occurs during operation, the pump inlet can be filled with a small amount of air or high pressure water flow approach to reduce or avoid cavitation damage.
Oil Pan,Oil Sump,Oil Drain Pan,Oil Drip Pan
WUQIANG HONGMA TOOLS MANUFACTURE CO., LTD , https://www.hmrapairtools.com