Problem of excessive shaft displacement in the de-coking water pump
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Our plant has two coking water pumps, and since they were put into operation, there has been a problem of excessive shaft displacement. After maintenance, the gap in the balance disc was set at 0.18 mm; the shaft displacement was adjusted so that it was 0.20 mm from the main thrust force, with the positive direction corresponding to the main thrust force. Currently, the rear axle displacement while driving is 0.5 mm, but upon disassembly inspection, there are no signs of wear on the thrust bearings; in other words, the thrust bearings have deformed by 0.30 mm. Is this possible? The distance between the thrust pad seat and the probe is also only 300 mm. I would appreciate some advice from those who are more experienced – how can we determine where this 0.30 deformation occurs?
Since there are no signs of wear on the thrust pads, it means that the pump itself is also in good condition. The thrust bearing itself does not undergo such significant deformation, but due to the high pressure at the outlet of the defoaming water pump, the relative load on the bearing is relatively high. As there are also other clearance gaps present, a deviation of around 20 units is considered normal. Our pumps are of the “Koll” type. Our solution is as follows: 1. Before setting the zero position, apply a certain amount of pre-tension in the direction of thrust at the coupling end (the magnitude of this force has to be determined based on experience; we certainly can’t guess arbitrarily), and then set the zero position. 2. Adjust the shafting to the main thrust position; set the “zero position” directly at -20. Also, be careful not to set it too large, otherwise the flash drive will touch the displacement sensor. Note: The methods above are for reference only.
What was the total series resistance measured when the rotor was installed at that time? Is it installed centered?