Multi-stage high-pressure boiler feed water pumps are often used for high-lift water delivery in factories and cities. The main parts of multi-stage high pressure boiler feed water pump include shaft, sleeve, inlet section, impeller, sealing ring, middle section, outlet section, balance ring, balance plate, and tail cover. If a part of the water pump fails during use, it will affect the use, so how should the parts of the multi-stage high-pressure boiler feed water pump be overhauled?
(1) Multi-stage high pressure boiler feed water pump balance device
Check the balance plate and the balance plate for axial wear marks and scratches. If there are, the two worn surfaces should be slightly trimmed on the lathe. For deep scars or severe partial wear, if they are repaired and reused, it is guaranteed The alignment between the inlet of the guide vane and the center of the outlet of the impeller should be adjusted by trimming the length of the toothed pad (from the flat end surface). If it cannot be guaranteed, the wearing parts should be replaced;
Check the balance cover and the balance plate for axial wear marks or scratches. If so, the two worn surfaces should be slightly trimmed on the lathe. For deep scars or severe partial wear, re-use after trimming. In order to ensure the alignment of the guide vane inlet and the center of the impeller outlet, the length of the toothed pad should be adjusted (from the flat end surface) to adjust, and the wearing parts should be replaced if it cannot be guaranteed;
Check the balance sleeve and balance sleeve for radial wear marks. If so, the worn surface should be slightly trimmed on the lathe, and the radial clearance should be controlled within the allowable deviation range (less than 0.25mm). ), if this value exceeds the stipulation, these two pieces should be replaced.
(2) Multi-stage high pressure boiler feed water pump shaft
Check the maximum runout tolerance of the shaft (ie, shaft bending). In principle, if the runout of the shaft exceeds the allowable tolerance, it is never allowed to use the hot and cold method to straighten it, and a new shaft should be replaced.
During the inspection, the axle bracket can be carried out between the two centers of the lathe (you can also use the V-shaped iron to support the supporting parts to detect the beating). But note that the axle should be accurately centered on the lathe, otherwise errors will occur.
(3) Multi-stage high-pressure boiler feed water pump hydraulic components and inter-stage sealing components
Check whether there are cracks or grinding on the sealing surfaces of the middle section, guide vanes, impellers, middle seal rings, front seal rings and guide vane sleeves;
Use a dial indicator to measure four points on the circumference of the sealing surface to check the parallelism. The deviation of the guide vane and the middle section must not exceed 0.03mm, and the other deviations must not exceed 0.01mm. If there are scars on the sealing surface, it is best to repair it on a lathe. If the sealing surface can be trimmed on a lathe, it can be ground and trimmed with a grinding tool. The mating surface must not be used as a ground tire to grind the sealing surface, because this will cause the spout to expand.
Check the radial clearance of the seal ring and the guide vane sleeve. If the measured gap value exceeds the maximum allowable value, replace the new components (remove the spot welding points on the guide vane and the middle section, and remove the old guide vane (Sleeve and front seal ring), respectively inspect the wheel shell and neck of each impeller, check whether there is abrasion, and then trim the contour and neck from the second stage to the last stage.
(4) Multi-stage high pressure boiler feed water pump bearings
Check the bearing bush, if there are cracks, delamination, pores and severe wear, if necessary, scrape off the slight indentation with a scraper.
The contact angle between the journal and the lower shoe is 60+5°, and it should be in the middle of the shoe, and the contact should be even.
(5) Multi-stage high pressure boiler feed water pump shaft seal
Damaged shaft sleeves and sealing elements should be replaced with new ones. If there are slight scratches or grooves on the surface of the shaft sleeve, they should be repaired.
(6) Rotor parts of multi-stage high pressure boiler feed water pump
After the rotor parts are repaired or replaced, it is necessary to re-install the test assembly (the "O" seal ring is not necessary for the test assembly), and then measure the radial runout of the hole in the guide vane sleeve of the outer diameter of the impeller seal ring, and balance the runout value of the end face of the disc to make Do not exceed the specified tolerance (<0.06mm). Perform a dynamic balance test on the rotor, and the allowable unbalanced torque M is shown in the following table:
