How to solve the major axis deep well pump deep well vibration Failures

Via the vibration of large deep well pump failure analysis and possible vibration various reasons put forward in the field of the motor and pump means easy to judge.

First, the technical performance parameters of deep-well pump
Model: 30JD-19x3, 3 impeller
Flow rate: 1450m3 / h
Shaft length: 24.94m, a total of nine axial
Shaft diameter: 080mm
Shaft Material: 40Cr
Speed: 985r/min
Thrust Bearing oil temperature: <50 ℃
Cooling water pressure: 0.8MPa
Yang pipe diameter: 500mm
Head: 80m
Rubber Bearing Lubricant: Water
When stand-alone non-motor re: 14t
Vertical Motor Model JKL15-6
Rated power: 500kW
Rated Voltage: 6000V
Rated current: 60A
Rotor inertia: 58kg · m2
Motor weight: 4t
Motor and pump body allow the vertical and horizontal amplitude values: <0.l0mm
This deep well pump required less than 0.1% water sediment concentration, particle size less than 0.2mm, and the water pump impeller should be soaked first-class people move less water lm. Present in seven, in August the Jinsha River during the flood of deep well water sediment taken up nearly 20%.

Second, vibration Faults
Operation of the pump and motor vibration, in the conditional, first disconnect the coupling between the two, of vibration source from the pump or motor, and carefully check the vertical electrical connection to a fixed base and the pump bolts is tight, the horizontal installation is tolerance.

1. Motor vibration source and identification

(1) the rotor speed is close to the critical speed.
Can calculate the motor shaft torsional stiffness and torsional vibration frequency of motor critical speed is the same motor, the pump angular frequency and power frequency close to resonance. In particular, the motor is the first time, vibration failure occurred, to conduct analysis and calculation. The work of rotor speed should be at least 25% lower than the critical speed or about 40% higher than the critical speed. In the analysis should also take into account the quality of rotor can not be simplified to focus on the quality of the situation, but the distribution along the shaft, which should be analysis of the critical speed to the second and third major critical speed.

(2) motor rotor imbalance.
Rotor imbalance is the most important and common causes of vibration, such as: 17 #, 19 # motor, with speed vibrometer (displacement meter) measured motor vibration speed 9.8-l0mm / s, velocity control IS02372 standards III machinery should be less than 4.5mm / s, while the 9.8-l0mm / s state, measured with a vibrometer motor amplitude value reached 0.30mm. In order to ascertain the extent of rotor imbalance, we produced a two-site set up two parallel steel rails, respectively (Note that steel should have sufficient stiffness), on the surface into a smooth rail Cleansing, will meet with a spirit level adjust the level of rail surface and fixed. Check will be placed on two rails above the rotor, the rotor back and forth by hand to promote the rolling several times, let it rest after making the tag below the rotor. Paste with goo position in favor symmetry point, and then conducted a number of rotating the rotor until the rotor stops in random positions can confirm rotor has reached static equilibrium. Equivalent quality to replace the paste materials, the completion of rotor balancing. If using the above method does not resolve the problem, on the rotor for balancing the need to test. The two motors that increase in the rotor side of the balance weight 45-5g, the amplitude is reduced to 0.05mm, with a displacement gauge the value of vibration velocity measured in 2.1mm / s or so.

(3) over a period of time has been normal use of the motor, the vibration to check bearing clearance is too large, shaft seat screw is loose, bent shaft for wear and short-circuit or a part of the winding, uneven air gap, rotor and uneven gap between the stator ring for more than 10%.

Of particular note is that motor amplitude close to the standard value, that is believed to be in compliance within the scope of the case, with load after the motor amplitude values are exceeded, this is because the entire deep well pump drive system vibration factor is the interaction and the result of the interaction.

2. Pump vibration source and determine

(1) pump installation and assembly error caused by vibration.
Thrust Bearing pump and after installing the horizontal and vertical pipes Yang degree tolerance will cause the pump's vibration, while the three control value has a certain relevance. After installing the pump, Yang pipes and pump head (not including the filter) a total length of 26m, are linked to vacant home, if Yang pipe perpendicularity deviation is too large, the pump will cause rotation in the pipe and shaft Yang so severe vibration. Yang pipe perpendicularity tolerance is too large will also be produced during the pump operation of alternating stress, caused by broken water mains Yang. After deep-well pump assembly, Yang within the total length of pipe in the vertical error should be controlled to ± 2mm. Pump to the level of vertical and horizontal error <0.05/l000mm. Impeller on the pump head of static balance tolerance is not more than 10g, there should be 8-12mm assembly finished moving up and down series of gaps. Installation and assembly clearance error is an important factor causing the pump vibration. (2) shaft whirl. Eddy, also known as "rejection transfer" is an axis of rotation self-excited vibration occurs, it neither has the characteristics of free vibration, nor is the type of forced vibration. It is characterized by a shaft between the bearing performance of the rotary movement, the vibration does not reach the critical speed in the shaft when it occurs in a large range and speed of their relationship with the shaft less. Transferred mainly by deep-well pump's rejection is not sufficient cause bearing lubrication, shaft and bearings if the gap between the larger question, then the rotation direction of motion in the opposite direction with the axis of rotation, this axis also known as jitter. In particular, deep-well pump drive shaft is very long, rubber bearings and shaft with clearance for the 0.20-0.30mm, shaft and bearings when there is a certain gap, shaft and bearing misalignment, the center from a larger gap in the lack of lubrication, such as deep rubber bearing lubrication pump water pipes break, jam, misuse of water supply caused by inadequate or not timely, etc., the more susceptible to jitter. In the journal of a transient turning point of contact with the rubber bearings, journal bearings to it by the shear force, force direction and the axis set the speed in the opposite direction, this force to the axis of translation, the mechanical effect the equivalent of an anti-clockwise torque, and a role of power in the journal center, the force parallel to the bearing wall of the tangent direction of the contact point, and there is a trend to lower the journal, the journal bearing wall along purely rolling, the equivalent of an internal gear, thus forming the opposite direction with the rotation axis movement.

This has been our day to day running of the situation confirmed, this will enable longer duration of burning rubber bearings.

(3) overload-induced vibration.
Pump Thrust Bearing with Xiji Ba's alloy, which allows the load to 18MPa (180kgf/cm2). Pump in the start, the thrust tile boundary lubrication in the lubrication. Respectively, in the pump outlet valve fitted with electric and manual valve. Starting at the pump at the same time open the electric valve, due to silt deposits caused by valve plate can not open or close the valve manually man-made factors, such as the exhaust is not timely, the pump will cause the violent vibration, and quickly thrust burning tile, such as 15 #, 17 # pump that is so.

(4) Export turbulent vibration.
In order to set Dg500 short pump outlet pipe, check valve, electric butterfly valve, manual valve, head and water hammer arrester, water turbulence Movement irregular pulse phenomenon, coupled with the valve block, a greater local resistance caused the change of momentum and pressure changes acting on the wall and the pump body to vibration, which can be observed values of pulse pressure gauge to illustrate the phenomenon. Turbulent changes in pulse pressure and velocity field continuously passed to the pump energy, when the turbulence of the main frequency of deep well pump system similar to the natural frequency, the system must absorb energy and cause vibration. To reduce this vibration, the valve should be fully open, the short length of pipe should be appropriate and additional bearings. Click to treatment, was significantly reduced vibration.

(5) deep well pump torsional vibration.
Long axis deep well pump motor connected with the elastic coupling, the drive shaft length of 24.94m. During pump operation, the existence of different angular frequency of the main vibration superposition. Harmonic vibration angular frequency synthesized two different results are not necessarily harmonic vibration, that exist within the pump torsional vibration of two degrees of freedom, it is inevitable. Mainly affects the vibration and damage Thrustpad. Therefore, to ensure that every block in the tile plane thrust into the oily corresponding wedge, we were the original equipment specifications set forth in 68 # 100 # replace the oil change the oil, increase the viscosity of lubricating oil thrust pad to Thrust Bearing Oil hydrodynamic lubricant film formation and maintenance is not being damaged.

(6) mounted on the pump beam with a vibration caused by the interaction.
Deep well pump and motor is installed in two sections of reinforced concrete frame for the 1450mmx410mm the beam, each focused on the quality of the pump and motor up to 18t, two adjacent pump beam in the same framework of the functioning of vibration, which in turn is a two- degrees of freedom vibration system, when one of the serious excessive motor vibration test run in non-load, that is not connected to the flexible coupling when idling motor, another motor normal operation of the pump amplitude increased to about 0.15mm, This situation is not so noticeable, should attract attention.