What Is The Cavitation Phenomenon Of The Slurry Pump?

What is the cavitation phenomenon of slurry pumps?

The cavitation phenomenon of the slurry pump refers to the partial vaporization of the liquid being transported due to the saturated vapor pressure at the conveying temperature equal to or lower than the pressure at the inlet of the slurry pump (actually at the inlet of the blade), causing noise and vibration of the pump. In severe cases, the pump flow rate, pressure head and efficiency will significantly decrease. Obviously, the cavitation phenomenon is not allowed to occur in the normal operation of the slurry pump.

The key to avoiding cavitation is that the installation height of the slurry pump must be correct, especially when conveying volatile liquids with higher temperatures, pay more attention.

　　Installation height of slurry pump Hg Permissible vacuum height Hs refers to the large vacuum degree that can be achieved by the pressure p1 at the inlet of the slurry pump. The actual value of the allowable vacuum height Hs is not the value calculated according to the formula, but the value determined by the slurry pump manufacturer. This value is attached to the slurry pump sample for users to check.

It should be noted that the Hs value given in the slurry pump sample is the value when the operating conditions are 20°C and the pressure is 1.013×105Pa. When the operating conditions and working medium are different, it needs to be converted.

(1) Transfer clean water, but the operating conditions are different from the experimental conditions, and can be converted according to the following formula.

Hs1 = Hs+(Ha-10.33) － (Hυ-0.24)

　　(2) Transfer other liquids When the liquid and the villain are delivered are different from the experimental conditions, two steps need to be converted: according to the above formula, the Hs1 found in the pump sample is converted according to the following formula; the second step converts Hs1 to H?s2 The actual installation height value of the slurry pump should be less than the calculated value. When the calculated Hg is a negative value, it means that the suction port position of the pump should be below the liquid level of the tank.

For example, a pump found from the sample that the allowable vacuum height Hs=5.7m. It is known that the total resistance of the suction pipeline is 1.5mH2O, the local atmospheric pressure is 9.81×104Pa, and the dynamic pressure head of the liquid in the suction pipeline can be negligible. Try to calculate: (1) Installation of the pump when conveying 20℃ of clean water; (2) Change to the installation height of the pump when conveying 80℃ of water.

Solution: (1) The installation height of the pump when conveying 20℃ of clean water is known: Hs=5.7m Hf0-1=1.5m u12/2g≈0 The local atmospheric pressure is 9.81×104Pa, which is basically consistent with the experimental conditions when the pump leaves the factory, so the installation height of the pump is Hg=5.7-0-1.5=4.2 m.

(2) Installation height of the pump when conveying 80℃ water. When conveying 80℃ water, the installation height cannot be calculated directly using the Hs value in the pump sample. The Hs time line needs to be converted according to the following formula, that is,

Hs1 = Hs+(Ha-10.33) - (Hυ-0.24)

　　It is known that Ha=9.81×104Pa≈10mH2O, and the saturated steam pressure of 80℃ water is found from the appendix to be 47.4kPa. Hv=47.4×103 Pa=4.83 mH2O

Hs1=5.7+10-10.33-4.83+0.24=0.78m

Substitute the Hs1 value into the formula to find the installation height.

When using the slurry pump under other complex working conditions, please contact us and we will wholeheartedly provide you with pre-sales and after-sales services to assist in the selection of models.