The impellers of the multistage centrifugal pump are arranged in the same direction, with the axial force of each stage impeller in the same direction. In order to balance the axial force, a balancing mechanism is specially set up to ensure that the axial force is balanced. The balancing disc device consists of a balancing disc, a balancing sleeve and a balancing seat.
The function of the balancing disc is to adjust the amount of over-flowing medium through the change of shaft clearance, so as to make the axial force completely balanced. Next, the professional manufacturer of multi-stage centrifugal pump "Changsha Zhonglian Pump Industry" technical engineer to introduce the working principle of multi-stage centrifugal pump balance plate and gap adjustment method, to facilitate the user friends to do a good job of multi-stage centrifugal pump daily maintenance.
1、Working principle of multi-stage centrifugal pump balancing disc:
The axial force of multi-stage sectional centrifugal pumps is balanced by the balancing disc at the high pressure end. The balancing principle is that the force generated by the pressure difference between the two sides of the balancing disc to balance the axial thrust of the impeller As the axial thrust changes with the working conditions, the balancing force must also change accordingly, that is, the pressure difference between the two sides of the balancing disc multiplied by the area of the balancing disc, should be equal to the axial force at any time.
As the water pressure flowing to the balance plate is the water pressure of the final impeller, if the axial force F is greater than the balance force A, the rotor shaft will be to the low pressure side of the fountain left injustice, and the balance plate is fixed on the rotor shaft, only to make the axial gap b reduced, the flow resistance increases, the pressure on the left side of the balance plate will rise, the balance force A acting on the plate also increases, it pushes the rotor shaft to the high pressure side of the fountain right injustice, so that the gap b increases again, this is the balance plate This is the principle of automatic balancing. However, due to the inertia of the shaft displacement, the right pushing position will not return to the original left pushing position, nor can it stop immediately at the new balance position in time, but exceeds the original position. At this point, the axial clearance b is too large, and caused the balance force is less than the axial force, so the rotating shaft will be left again, and due to inertia left shift will be too much, resulting in the balance force is greater than the axial force. So back and forth scurry shuttle, resulting in low-frequency scurry vibration, while thrust tile in the axial force is too large when the thrust tile temperature rise and burn, if the axial force continues to increase, will cause the balance disk dynamic Yao static part in the friction process contact surface wear, after a long time, will make the dynamic static disk bite and thus generate vibration, serious threat to the safe operation of the pump.
2、multi-stage centrifugal pump balance disk clearance adjustment method:
The normal standard for the axial clearance of multistage centrifugal pumps during operation is 0.1mm~0.2mm, but the axial movement of the rotor is required. As can be seen from the structural diagram of the multistage centrifugal pump, 7 is the accessory balance disc.
(1) The size of the clearance can be adjusted by adding or subtracting shims or thrust bearings on the inside of the thrust disc.
(2) After installing the thrust bearing, let the rotor string to the low pressure side and the balance disc clearance value is the percentage meter reading.
(3) With the balance disc and balance seat close together, the reading is marked on the shaft head with a percentage meter. Adjustment is made after assembly according to the clearance values marked on the drawings. Many people believe that after the impeller is aligned, there should be a clearance of 0.1mm between the balance disk and the balance sleeve to prevent friction between the balance disk and the balance sleeve. The multistage centrifugal pump manufacturer summarises the clearance adjustment method for multistage centrifugal pumps.