300 MW Unit Condensate Pump Motor Elimination Vibration Method Liu Baofeng

1 Condensate pump motor structure characteristics The factory 300MW machine condensate pump motor is a three-phase vertical asynchronous motor manufactured by Hunan Xiangtan Motor Factory, its model is YLST500-41000KW6KV, by the stator, rotor, frame, thrust bearing (thrust bearing components For: thrust head, insulation pads, mirror plates, thrust tiles, upper and lower positioning bearings and other major components.

Because the weight of the pump and motor rotor and the axial force in operation all depend on the thrust bearing, and the axial direction of the pump and the motor rotor depends on the thrust bearing, the motor and the water pump are connected by a rigid coupling, so the vibration and disturbance of the motor Will be passed to the pump. Condensate pump motor rotor structure see.

The rotor structure of the condensate pump motor indicates the cause of the vibration of the condensate pump motor. The 300MW machine A and the condensate pump all generate vibration during operation. The measured maximum amplitude is 0.46mm, which seriously threatens the safe operation of the unit.

After an in-depth analysis by the staff and searching for relevant information, it is considered that the motor rotor's oscillation is the main cause of motor vibration. The ambassador took the bearings up and down to locate the bearing, especially the motor's lower bearing was subjected to additional radial disturbance force, which caused serious wear of the motor bearing end cap, which affected the normal operation of the pump rotor, and would seriously damage the radial positioning of the pump and cause the pump The motor cannot run. The main reasons affecting the swing are the following: 1 The clearance between the thrust head and the spindle is large; 2 The thickness of the locking plate is uneven; The 3 axis itself is bent; 4 The bottom plane of the thrust disk mirror plate is not perpendicular to the axis.

3 Condensate pump motor vibration inspection 3.1 Inspect and adjust the thrust head and thrust plate 3.1.1 The radial head clearance with the shaft Check, measure and adjust the motor Dismantling inspection found that the electric corrosion of the joint of the B condensate pump motor shaft and the thrust shaft sleeve is serious. , Measuring the original size of the journal and the maximum size of the electric corrosion over a difference of 030mm, and the whole circle is irregular, can not achieve close cooperation with the thrust head. Therefore, during the inspection and repair, the journal will be turned, the original size of the journal will be 180mm, the size after turning will be 179mm, and the thrust sleeve and the journal joint will be plated. After turning, the tolerance of the shaft is: axis 1790, Hole 179+0.03 to meet the assembly process requirements. After dismantling, it was found that both the locking piece of the fixed thrust bushing and the locking slot on the shaft were worn out, and the maximum depth of the locking piece wear was 1 mm. Therefore, after replacing the two-half retaining ring with a 0.03 mm feeler gauge, there was no clearance to check the rotor. Uniform load.

From the analysis, it was found that the vibration caused by the unstable operation caused the axial thrust of the rotor to be too large, and the oil film was squeezed too thin. First, thousands of friction occurred, and the tungsten metal temperature increased. The ions in the oil during operation are exchanged with the current generated by the rotor at the rotor end of the operation. The main cause of this problem is due to unreasonable assembly and electrical corrosion during operation. Electrocorrosion is mainly due to the fact that there is no insulation between the thrust shim and the stator of the motor, which causes corrosion between the metals. This corrosion accelerates the cathodic corrosion between metals. The potential change is the corrosion potential in the medium where the metal or non-metal is located, but not Compare with a simple standard potential.

The corrosion caused by the shaft current proves that the thrust pads are much more corrosive than the bearing pads. The corrosion of the pads can be seen from the inspection of the condensate pump. The maximum depth of corrosion is about 0.3mm, and the area to be corroded is 20x20mm. On the oil exit side of the pad, traces of tungsten melted on the bearing bushes appeared.

In order to overcome and prevent electrical corrosion, it should be done in the overhaul: 1 Select different metals with the same kind of metal or small potential difference; 2 Use different electrical insulation between metals; 3 Prevent electrolyte; 4 Increase the polarity of the electrode; Reduce the area of ​​the cathode and increase the area of ​​the anode; use a qualified lubricant.

3.1.2 The axial clearance of the thrust head and the shaft shall be checked, measured and adjusted. The height of the inner end of the thrust head shall be matched with the height of the shaft. When the height is high or low, the two half rings shall be re-formulated to process the force in the axial direction of the rotor. Next, ensure that the axial gap is not large. 3.1.3 Inspection and adjustment of the thrust plate Check the flatness of the surface of the thrust head and the mirror plate. Use the sample steel ruler to cross over the surface to be inspected. Check whether the transparent point and the feeler gauge have gap. Thrust bearing combination with a model straight ruler placed on the surface of the mirror, and then use the above method to check to see whether the flatness of the surface of the mirror is qualified, whether it produces wavy, otherwise it can adjust the tightening degree of the connecting screw to meet the technical requirements value.

3.1.4 Measurement and adjustment of the deflection of the thrust pan Scroll the measurement axis of the lathe on the rotor of the motor to a maximum value of 0.03 mm. Measure the deflection of the thrust disc plate after mounting the thrust disc and the coupling, and the maximum scoop of the thrust disc. For 0.08mm (standard 矣 0.02mm), combined with the maximum swing value measured before repair, through the calculation of the unilateral scraping of the thrust disk insulation pad, after repeated scraping, adjustment, the maximum deviation of the thrust disk measured 0.02mm Measuring the coupling surface scourer deviation is less than 0.04mm, the coupling radial slump is less than 0.04mm. 3.1.5 Inspection and grinding of the thrust bearing scraper After the thrust disk is adjusted, put the thrust disk on the wooden frame. Steady, the thrust disk mirror plate washed with pure alcohol, and then coated with a layer of thin red red powder on the mirror plate, the thrust of the tile covered on the mirror plate, in the mirror circle clockwise sliding 3 ~ 5 Check the contact surface between the thrust pad and the mirror plate, and scrape the thrust pad until the contact point of each thrust pad surface is 3 to 5 points per square centimeter. The contact area should be more than 70%, and each tile should be Both the inlet and outlet sides should be scraped out of the oil tank. When scratching the thrust tile on the mirror plate, care should be taken to protect the mirror plate.

The upper frame with thrust pads will be installed on the vertical lathe with the calibrated level, and then the 8 pieces of thrust pads will be installed on the lathe to measure whether 8 thrust pads are in the same horizontal position. If the horizontal error is greater than 0.03 mm, The anti-vibration bolts can be adjusted so that each thrust pad is on the same level and the locking plate is fixed after adjustment.

3.1.6 Checking and replacing the upper and lower bearings of the motor The upper and lower bearing seats of the motor are worn due to the influence of the degree of rotation of the motor rotor. The upper and lower bearing seats can be plated to ensure the fit clearance of the bearing seats. If both the upper and lower bearings of the motor are worn, the upper and lower bearings of the motor must be replaced.

3.2 Motor rotor slew and adjustment 3.2.1 Before measuring the motor rotor slew The purpose of finding the slew of the motor rotor is to check and correct the verticality of the rotor axis of the motor relative to the plane of the thrust disk mirror plate, that is, to measure the motor shaft backrest wheel. The swing of the flange. During the measurement, the lower bearing of the motor and the flange of the motor's back wheel are divided into 8 equal parts along the circumference and marked with a symbol so that the same symbol is in the same vertical plane. At the same time, two dial gauges are installed at the guide bearing of the motor and the flange of the back wheel of the motor. The dial gauge in the same plane should be at a right angle, and the two dial gauges in the same plane should be in the same vertical plane. If the center line of the shaft and the surface of the thrust plate are not perpendicular, the shaft will inevitably oscillate when operating. The degree of swing can be read from the dial indicator. The total swing of each measurement point is the relative point of the dial indicator in the diameter direction. The difference between the readings, the swing should be 矣 0.02mm, when the swing exceeds the allowable value, the thickness of the insulation pad can be adjusted generally. Pre-repair measurement results are as follows: The maximum value of the swing angle at the wheel is 0.45mm, and the value of the B pump is 3.2.2. The motor rotor is assembled after the rotor assembly is measured. After the repair, the various parts of the motor rotor are assembled, and the rotor swing is reviewed. The maximum oscillating value of the rotor of a condensate pump motor is measured as 0.04mm; the maximum oscillating value of the rotator of a condensate pump motor is 0.05mm. After the maintenance, the no-load vibration measurement of the motor: the maximum vibration of the condensate pump motor is 0.05 Mm; B condensate pump motor maximum vibration is 0.04mm. Motor with load measurement vibration: A condensate pump motor maximum vibration is 0.05mm; B condensate pump motor maximum vibration is 0.07mm. 4 Conclusion condensate pump motor vibration protection to protect Huadian energy The safe and economic operation of the 300MW unit of Mudanjiang No. 2 Power Plant has provided reference for the overhaul of large-scale vertical water pumps such as circulating pumps for 300MW units. Through the overhaul of the 300MW unit A and the condensate pump motor, adopting the above-mentioned maintenance methods not only saves time and costs, but also improves the maintenance capabilities of the employees and lays a solid foundation for the company to go to market.

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