The water ring vacuum pump is designed to be too large
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Discuss this issue: The water ring vacuum pump is designed to be too large, resulting in insufficient suction capacity at the inlet; moreover, this pump experiences high vibration and loud noise. What is this phenomenon called in academic terms? It should not meet the definitions of cavitation and vapor erosion.
This happens when the pumping volume (flow rate) is set too high. Check the vacuum level; it might be possible to install a valve at some point on the inlet side to allow air to leak in, thereby increasing the pumping volume (of course, with the goal of maintaining the desired vacuum level)
That’s indeed the case; the vacuum level is too high. Now, add a return line. I don’t know what this phenomenon is called. One definition of a water ring compressor is overcompression.
The more mature technology nowadays is to use a Roots pump together with a water ring instead of a single water ring.
What does it have to do with the air extraction volume? Inlet pressure and water temperature are the key factors……
In a station where a water ring vacuum pump with a pumping capacity of 400 m3/h was originally used, installing a water ring vacuum pump with a capacity of 40,000 m3/h would not cause such a problem!
The condition you are describing is cavitation. Cavitation is not determined by whether the pump has reached its test limit pressure, but rather by the limit pressure corresponding to the inlet water temperature. Generally, if the inlet pressure is lower than the saturated vapor pressure corresponding to the inlet water temperature plus 6.5°C, plus 0.5 kPa.a, the vibration and noise of the pump will increase gradually. The limit pressure is reached when the inlet pressure equals the saturated vapor pressure corresponding to the inlet water temperature plus 6.5°C (this is under the condition that the exhaust pressure is one standard atmosphere)
Add a cross-line to the inlet and outlet pipelines, and open it slightly
The inlet water temperature is fine, so this can be ruled out. The issue now is that the inlet pressure is too low (the vacuum level is too high)
You may not have paid close attention to what I said on the 7th floor: if one wants to control and increase the inlet pressure, a proper design involves installing exhaust gas return pipelines in the system, with valves used to regulate the amount of flow back in order to control the vacuum level. Depending on the specifications of the water ring vacuum pump, variable frequency control can also be employed; however, in most cases, the flow rate that can be adjusted using variable frequency is limited – this is determined by the speed range of the impeller, and each model has a different speed range!
Excuse me, senior, where does this theory come from? Thank you