Knowledge Hall: Vibration Fault Analysis of Large Long Axis Deep Well Pumps

Through the vibration analysis of large-scale deep well pump and various reasons that may cause vibration, a simple method to judge motor and pump in the field is proposed. Panzhihua Iron and Steel in the upper reaches of the Jinsha River has built a large deep-well pump station, pumping station consists of two 18m ID, deep 31m deep and the upper plant form. The Jinsha River flows into the deep well via four dg1200 pipes. The upper part of the deep well houses 20 sets of 30jd-19x3 sand control deep well pumps on a reinforced concrete frame beam with a cross-section of 1450mm × 410mm. After a long period of installation and maintenance, we made some explorations on the causes of vibration. First, the deep well pump technical performance parameters Model: 30jd-19x3, three impeller flow: 1450m3 / h drive shaft length: 24.94m, a total of 9 shaft pump shaft diameter: 0 80mm shaft material: 40cr speed: 985r / min thrust Oil temperature: <50 ℃ Cooling water pressure: 0.8mpa Yang pipe diameter: 500mm Head: 80m rubber bearing lubrication medium: water without motor Single weight: 14t Vertical motor model jkl15-6 Rated power: 500kw Rated voltage: 6000v Rated current: 60a Motor rotor moment of inertia: 58kg · m2 Motor weight: 4t Motor and pump vertical and horizontal allowable amplitude: <0.l0mm This deep well pump water quality requirements of not more than 0.1% sediment, particle size of not more than 0.2mm , And the first impeller of the pump should be immersed in water level lm below. At present, during the floods in July and August, the highest concentration of water in the Jinsha River from deep-well pumps is nearly 20%. Second, the vibration fault judgment Pump and motor vibration occurs during operation, when conditions, the first should disconnect the coupling between the two, the vibration source is from the pump or motor, and carefully check the vertical motor base and Pump connection bolts are tightened, the installation level is over tolerance. 1. Motor vibration source and determine (1) the rotor speed is close to the critical speed. It can be calculated by calculating the motor shaft torsional stiffness and torsional vibration motor frequency with the motor critical speed, pump frequency and frequency close to produce resonance. In particular, the first use of the motor, the occurrence of vibration failure, to be analyzed and calculated. Motor rotor speed should be at least below the critical speed of 25% or higher than the critical speed of about 40%. In the analysis, we must also consider that the quality of the rotor of the motor can not be simplified into the concentrated quality situation but distributed along the rotation axis. Therefore, the critical speeds such as second and third order should be analyzed when analyzing the critical speed. (2) Motor rotor imbalance. Motor rotor imbalance is the most important and common causes of vibration, such as: 17 #, 19 # motor speed vibration meter (displacement meter) measured motor vibration speed of 9.8-l0mm / s, the control is02372 vibration speed standard, iii class of machinery should be less than 4.5mm / s, and in the 9.8-l0mm / s state, measured with a vibrometer amplitude of the motor reaches 0.30mm. In order to find out the unbalance degree of the rotor of the motor, we made two steel frames on the scene to set up two parallel rails (pay attention to the steel frame should have sufficient rigidity), the surface of the rails processed into smooth and clean, Face adjustment and fixed. Check the motor rotor placed on top of the two rails, manually push the rotor to scroll back and forth several times, to be stationary after each, under the rotor marked. With sticky paste in the emphasis position of the symmetry point, and then rotate the rotor several times until the rotor can stop at random position, make sure the motor rotor has reached a state of static equilibrium. To replace the paste with equivalent quality to complete the balance of the motor rotor. If using the above method still can not solve the problem, you need to motor balancing test motor. The above two motors that increase 45-5g balance weight on the rotor side, the amplitude value reduced to 0.05mm, with the displacement meter measured vibration velocity value of 2.1mm / s or so.