Pressure drop issue in shielded pumps
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Background: The liquid level in the condenser of the vacuum system is maintained at 50%. There is a low liquid level switch on the liquid discharge pipeline, and the liquid discharge pump is a canned pump located 20 meters above the condenser. A pressure drop occurs during the normal operation of this canned pump; equipment failures and blockages in the inlet pipeline have been ruled out. Sometimes the pump pressure suddenly improves again. The specific reason is unknown; please advise
Under normal circumstances, once the level switch of the liquid discharge pipe gives an alarm, the pressure of the pump drops rapidly.
What is the vertical height of the liquid level from the pump inlet at the time of a level alarm? Is there a cracking sound inside the pump casing when the pressure decreases? It is suspected to be cavitation.
Increasing the liquid level and lowering the medium temperature are likely causes of cavitation.
The level switch is located about 18 meters away from the pump inlet.
The pump’s head is 35 m; 98% of the fluid it transports is water. The liquid level is about 20 m away from the pump inlet. The pump’s pressure can drop down to 300 kPa, and its vibration levels are acceptable
The pump relies entirely on this head difference of 20m from the condenser to provide NPSHr~~~~ The pressure drop at the outlet is certainly caused by deteriorating suction conditions at the inlet~~~~ Therefore, it is recommended to: 1. Add an impeller to the pump； 2. Pre-pump condensate line string cooler ； 3. Improve the liquid level control line~~~ (raise the alarm level)
95% of the fluid is acidic water, with a temperature of 28°C; this is already a very low temperature； The condenser liquid level is controlled at around 80%, which is also quite high. When the pump pressure drops, vibration in the inlet pipeline can be felt (in a non-fully filled state), though sometimes it improves. The specific reason cannot be found.
“Vibration of the inlet pipeline (non-fully filled state)”~~~ The inlet line actually has: “Non-fully filled state?” ! ”~~~