Multistage centrifugal pump problems
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I have a multistage centrifugal pump here. When it is running, the axial force in the inlet direction is large. The balance plate is adjusted to half of the total series volume. The balance pipe is also checked. I have the following questions. The first-stage impeller flow path is wider than other impellers. Should the orifice ring be correspondingly larger? What is the standard for the gap between the cavity sleeve and the impeller that matches the balance plate? The current measurement is 0.60mm. Can anyone give me some guidance? Thanks. It would be best to have relevant standard procedures issued to you.
1. Structural form is important! Are there any pictures or structural diagrams? 2. The size of the gap is related to the size of the mating diameter and the temperature of the medium. Please add details. 3. Large axial force! In what ways!
Adjust the balance plate gap to half of the total channeling? How big is the gap? Can the balance plate still work? The gap of the balance plate is only about 0.1 to 0.2mm, and the designs of each manufacturer may be different.
The orifice ring clearance is related to the diameter of the impeller and the temperature of the medium. For details, you can check API610
Is this what you mean by 0.10 to 0.20?
The medium temperature is only 40 to 50 degrees. The axial force is clearly seen to move towards the inlet end after operation. The compression of the mechanical seal at the motor end increases and there is white smoke.
I am asking a question, what is the principle of the flow path width of the first stage impeller, and is there any explanation for the mouth ring clearance?
The value of b2 in the figure below is the axial clearance between the balance plate and the balance plate.
The first-stage impeller generally has a larger inlet than the secondary impeller in order to reduce the cavitation margin of the pump.
Thank you for your reply. Can you give me the details of your picture or a detailed explanation of how the balance plate balances the axial force of a multi-stage centrifugal pump?
I searched the picture on Baidu to explain to you where the gap is. In multi-stage pumps, the impeller generally does not have a rear orifice ring, and the area of the suction inlet side of the impeller, that is, the front cover, is smaller than the area of the rear cover. Force is equal to pressure times the area of action. Therefore, an axial force toward the entrance will be generated. There is a small gap between the balance plate and the balance plate for pressure reduction and flow restriction. The cavity behind the balance plate will be led to the inlet of the pump or the inlet tank using a balance pipe. The pressure in this chamber is close to the inlet pressure. The cavity between the balance plate and the final impeller is the pressure at the outlet of the pump. So the balance plate will create a backward force. This allows the axial force to be balanced.