Boiler feed water pump (Shenyang water pump) assembly gap data and adjustment
1. Bending of pump shaft:
High pressure pump structure is precise, the gap between the dynamic and static parts is small, the rotor speed is high, and the shaft is negative
Load. Therefore, the requirements for the shaft are relatively strict. The bending degree of the shaft is generally not allowed to exceed 0.02mm, more than 0.04mm should be carried out straight shaft treatment, the bending of the shaft is too large potential will increase the sway of the pump rotor, sway degree is necessary to increase the sealing ring and guide vane bushing gap, if the gap is too large, will also form eddy current, causing the pump vibration. Reduced pump efficiency.
2. Assembly clearance between impeller and pump shaft:
The impeller of the multistage feed pump and the pump shaft are generally assembled with a clearance, and the clearance is 0.00mm-0.04mm, which is determined by the processing tolerance of the pump shaft and the impeller. On the one hand, excessive clearance or interference increases the assembly difficulty, on the other hand, affects the thermal expansion of the rotor components, and increases the generation of acquired sway of the pump rotor, causing the rotor mass imbalance. Excessive clearance increases the wobble of the pump rotor, resulting in unstable dynamic balance of the pump rotor, and the matching part of the inner hole of the impeller and the shaft increases due to long-term use and multiple disassembly, so the matching shaft segment or the inner hole of the impeller can be repaired by spraying.
3. Adjustment of pump shaft key and keyway clearance:
Pump impeller and pump shaft transfer rotation by key. The key and pump shaft keyway should be interference fit, the tight force should be 0.00mm-0.03mm, the key and impeller keyway should be gap fit, its value is also 0.00mm-0.03mm.
4. Small rotor installation:
a) The purpose of a small dress. The rotor small assembly, also known as pre-assembly or trial assembly, is the key to determining the assembly quality. Its purpose is to measure and eliminate the rotor tight state shake to avoid internal friction, reduce vibration and improve the shaft seal working condition; Adjust the axial distance between the impellers to ensure the exit alignment of the impellers at all levels; Determine the size of the adjusting sleeve.
b) Determination of axial expansion clearance of the rotor kit, because the rotor kit is different from the pump shaft material. In addition, both ends of the pump shaft are outside the pump body, so in the hot state, the expansion of the pump shaft and the rotor set is greater than the pump shaft, so the value of the expansion gap in the rotor is determined according to the length of the rotor and water temperature, generally in the 10 impeller about the rotor expansion gap is about 1 mm, the expansion gap is too large, it can not be well fastened the rotor set, the expansion gap is too small. It may cause the rotor to bend in hot state. Cause static friction, damage equipment.
c) Check before small assembly, check the size of each component on the rotor, and eliminate obvious out-of-tolerance. The swing of the assembly on the shaft should generally not exceed 0.02mm. For all the assembly on the shaft, such as the impeller, balance disc, shaft sleeve, etc., the verticality of the center line of the end face should be checked on the special tool. The false shaft and the kit maintain a gap of 0.00mm-0.04mm, rotate the kit by hand, after one week of rotation, the runout value of the dial indicator should be below 0.015mm, check the verticality of the other end with the same method, you can also use the false shaft, and put the assembly on the flat plate to measure, such a measurement method can not get the vertical error of the end face and the center line of the shaft. The result is the parallelism error of the upper and lower ends.
d) Measure the slosh degree of the pump rotor, after the above preparations, clean the kit, and install it on the shaft in the order from the low pressure side to the high pressure side, tighten the shaft sleeve lock, leave the expansion gap (for the hot sleeve rotor, only install the first and last two poles of the impeller, the middle level is not installed) or measure the slosh of each part, as shown in the table
Measuring position The balance plate at the impeller mouth of the shaft sleeve at the journal
Radial axis at the ring
Allowable value /mm ≤0.02 ≤0.04 ≤0.08 ≤0.04 ≤0.03
After the rotor small assembly swing degree meets the requirements, the relative position of each component should be marked, the impeller should be marked with a good prefix, and removed in turn, waiting for the final assembly
5. Rotor axial position (half channeling) adjustment:
After completing the measurement and adjustment of the total amount of the rotor, balance the disk, adjust the set well and
Lock the mother to the small installation position, the rack dial indicator, before and after the rotor, the dial indicator reading difference is the rotor half channeling amount, the rotor half channeling amount should be half of the total channeling amount, such as the half channeling amount and the total channeling amount does not match, the adjustment set should be adjusted to make it in line.
6. Adjustment of work channeling:
Large feed pumps are equipped with working channeling adjustment device, some feed pump with thrust tile to adjust, some feed pump with thrust bearing to adjust, the measurement method is the same as the rotor measurement total half channeling method, in the thrust bearing (or thrust tile) working face or non-working face to add or reduce the pad can adjust the work channeling. Generally, the feed pump works by 0.8mm-0.2mm, when the pump starts and stops and the balance plate is not yet established the pressure difference, the axial thrust of the impeller is borne by the working tile of the thrust bearing, the balance plate once the pressure difference is established, the axial thrust of the impeller is completely balanced by the balance plate, and the thrust plate is out of contact with the working tile, to achieve such requirements, At this time, the balance plate and the balance seat should have a gap of 0.01mm, if the gap is too large or no gap. The gasket on the back of the working tile can be adjusted, and the position of the balance disc on the shaft can also be adjusted. The oil film thickness of the thrust bearing during operation is about 0.02mm to 0.03mm. In order to make the thrust bearing not more than 0.03mm-0.045mm during the normal operation of the pump, only in this way can the thrust disc be in the working tile and the non-working tile not put into work. If the thrust bearing is still in working condition, the axial clearance between the balance plate and the balance seat should be readjusted.
The axial clearance between the thrust disk and the non-working tile is far less than the back clearance of the rotor impeller (that is, half channeling amount). When the pump shaft is channeling due to cavitation or unstable working conditions, the thrust disk and the non-working tile work first, and the rotor will not friction with the pump shell.
7. Adjust the radial clearance of the pump
After the pump body is installed, the end covers and tiles at both ends are installed
Adjust the concentricity of rotor and stator (lift shaft). For the concentricity of the rotor and the stator, the requirements are: half lift and half of the total lift or slightly smaller (considering the static winding of the rotor), the gap on both sides of the roof is equal and the four corners are uniform.
Lifting shaft measurement: before the final installation of the bearing shingle, each end of the bearing frame is installed with a dial indicator, the meter rod center line should be perpendicular to the shaft center line, and contact the journal, with a crowbar at both ends of the shaft at the same time smoothly lift the shaft, the dial indicator reading difference in the upper and lower position, is the total lift of the rotor.
Pry up the rotor and put it into the lower tile. At this time, the dial indicator reading should be half of the rotor lift, and it should be half of the total lift, otherwise it needs to be adjusted. When adjusting, if the adjustment bolt is under the bearing frame, it is only necessary to loosen and tighten the bolt. If there is no adjustment bolt, the thickness of the gasket under the bearing shell can be adjusted.
For the concentricity of both sides of the rotor and the stator, it is generally determined by whether the gap between the two sides of the bearing shell is uniform. After placing the lower tile, the feeler ruler is used to measure the gap between the four tiles of the bearing shell, and the adjustment is uniform and the single-side gap of the tile should be half of the top gap of the bearing shell.
8. Adjustment of bearing and mechanical seal clearance
The adjustment of the clearance tension of the bearing bush is adjusted according to the requirements of the disintegration process. The adjustment principle of the clearance adjustment of the mechanical seal is: the compression amount of the pretension force of the static ring of the mechanical seal is half of the total compression amount. The adjustment method is to push the pump rotor to the low pressure side of the pump, adjust the dynamic ring of the mechanical seal and the seal ring of the pump shaft to ensure the pretension force of the mechanical seal on the high and low pressure side of the pump.
Shenyang pump production of boiler feed pump product models, specific models of the gap data welcome to consult!
