Working principle of the compressor thrust bearing and bearing heater

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This post was last edited by ely30861 on 2021-4-10 21:17. It covers the working principle of the compressor support bearings and bearing heaters, a brief overview of the related manufacturing processes, as well as additional information on the subject. A bearing heater is also known as a bearing induction heater or electromagnetic induction heater; it is a type of heating device. The heating element is integrated with the platform, ensuring safety, reliability, and ease of use. It is primarily used to heat various types of metal components such as bearings, gears, bushings, shaft sleeves, diameter rings, pulleys, shrink rings, and connectors. By heating them, bearing heaters cause them to expand, thereby meeting the requirements for interference fitting. Functions include: quick setting of plate temperature and alarm temperature, real-time temperature display, automatic over-temperature protection, and automatic heat retention. Working principle: The working principle of a bearing heater is to generate heat in the metal by inducing eddy currents in a alternating magnetic field; it is commonly used in metal heat treatment and similar applications. The principle is that when a thicker piece of metal is placed in an alternating magnetic field, an electric current is generated due to electromagnetic induction. In thicker metals, after an electric current is generated, it forms a spiral path of flow within the metal. As a result, the heat produced by this current flow is absorbed entirely by the metal itself, causing it to heat up rapidly. Installation and commissioning 1. Short-circuit heating: The main unit is a transformer with a special structure; a movable yoke is used to directly enclose bearings or other workpieces that are to be heated. During operation, the power supply of the main unit is turned on, and a short-circuit current is induced in the workpiece (which acts as the secondary winding), causing it to heat up. 　　2. Place the yoke iron on the end face of the main machine core. 　　3. Check that the wiring of the plug and socket is correct, ensure proper grounding, and then insert the plug into the power socket equipped with a control switch. 　　4. Set the function selection switch to the manual control position and turn on the power; at this point, the red indicator light will turn on. 　　5. Press the start button to power on the main unit; at this point, the green indicator light turns off while the red one turns on ； Press the stop button; the red light turns on while the green light turns off. Thus, the debugging is complete and it can be put into use. Operation procedure: 1. Select the appropriate yoke based on the inner diameter of the bearing, and place the yoke fitted over the bearing on the end face of the main machine’s core; it should fit snugly and evenly. 　　2. During the heating process, use a spot thermometer to measure the temperature rise at the end face of the inner ring of the bearing. When the temperature rise meets the requirements, note the time accurately, stop heating, remove the yoke, take off the bearing, and then it can be assembled. 　　3. Heat bearings of the same specification continuously by setting the function selection switch to the timer mode and specifying the heating time; the power will be automatically turned off once the bearings have been heated for the specified duration. 　　4. After the work is completed, turn the function selection switch to the stop position to cut off the power. Scope of application: The bearing heater is suitable for use in mechanical manufacturing and maintenance in fields such as power plants, textile factories, papermaking, the chemical industry, the oil sector, machinery production, and mine maintenance. It can be used to heat circular components such as bearings, connectors, gears, and mechanical bushings, as well as to automatically demagnetize them. This allows the components to expand cylindrically, meeting the requirements for interference fitting. The heater is controlled by a microcomputer, which enables it to automatically detect equipment faults, adjust its heating power, and enable soft start/stop functions. Features The eight key features of bearing heaters: 1. Fast heating speed, with temperature display to control the heating process. 　　2 A completely new eddy current induction design, utilizing advanced international technologies such as “Fuzzy Control” and “Neural Network”. 　　3 Can operate continuously, with high output power and efficiency. 4 The heating process is safe and reliable. 5 It can heat bearings with seals. 6 Features a rotating (hydraulic) rocker-type or hinge-type heating rod design for easier use. 　　7 The heating process can display the heating time. 8 No open flame, no pollution, environmentally friendly, and no risk of accidents. 1 Application of balance pipes in centrifugal compressors; r$ c$ E; I& g: l J% X In centrifugal compressors, a pressure difference generated by the gas acts on the wheel cover and disk of the impeller, resulting in an axial thrust on the compressor rotor directed toward the inlet side of the impeller. This thrust is generally counteracted by a balance disc. Since the balance drum is located above the shaft end, a portion of the process gas leaks from the mechanical seal to the outside of the balance drum. Now, the balance tube must be used to guide the gas on the outside of the balance disk to the compressor inlet. ; l) }3 h0 Z4 C3 R5 L, D 2To understand the function of the compressor balance pipe, it is necessary to know at which points on the compressor the two ends of this pipe are connected! On one side of the balance tube is the compressor inlet, which is something most people are aware of; as for where the other side is connected to, however, people may not be able to explain it clearly. On the other side is the outer cavity of the labyrinth shaft seal on the high-pressure side of the Comac compressor. To ensure a certain flow rate of the primary sealing gas for the dry gas seal, it is necessary to keep the pressure of the primary sealing gas about 0.3 MPa higher than the pressure of the reference gas; the pressure of the reference gas corresponds to the pressure in the balance line. : g) The O4 O/ u5 O; S9 x 3 dry gas seal balance lines are drawn from between the labyrinth seals at the high and low pressure ends, combined, and then fed into the compressor’s first-stage inlet pipeline; their purpose is not to balance axial forces. Its main function is to promptly extract the medium gas leaking from the labyrinth seal, ensuring that the pressure of the buffer gas is 0.05 Mpa higher than that of the leaking medium gas, thereby achieving a flow-blocking sealing effect and preventing the medium gas from contaminating the main sealing surface of the dry gas seal. & The function of the balance tube in W1 l- h, h: w& v* y9 D 4 is to balance the axial force on the rotor; it serves as a connecting pipe between the high-pressure and low-pressure sections of the compressor, and is usually installed at the high-pressure end. The pressure on both sides of the balance disk is equal to the low-pressure section pressure, and this pressure balances 70% of the rotor’s axial force. The dry gas seal uses the pipeline pressure as a reference to ensure the proper operation of the main sealing gas for the dry gas seal (the exhaust gas from the high-pressure side of the compressor serves as the gas source). A4 {(k% H5 E balance disk: It is a component that is fixed to the shaft. Due to the different gas pressures on either side of each impeller stage, a axial force acts on the rotor in the direction of the low-pressure side. To prevent the rotor from moving axially, the pressure difference on both sides of the balance disk is used to counteract most of this axial force; the remaining axial force is absorbed by the thrust bearings. Compressors using some other balancing methods may not have balance discs. III. Relevant images IV. Summary of Haiyou’s views Viewpoint 1: The axial thrust is too high; it is necessary to check the clearance of the thrust bearings, as well as the pressure difference between the gas inlet and outlet. If needed, check whether the clearance of the internal sealing rings is within acceptable limits. Viewpoint 2: The lubrication is not proper; it is necessary to verify whether the oil pump, oil cooler, and filter are functioning correctly. Additionally, it is important to check whether the oil pressure, oil temperature, oil volume, and oil quality are all within normal and acceptable ranges. Viewpoint 2: It is difficult to analyze the underlying causes of the fault merely based on this phenomenon. On the surface, it is undoubtedly severe wear, and the cause of this wear is naturally poor lubrication. And what causes poor lubrication? There are two main reasons for this. One is the quality of the lubricating oil; for example, if the lubricating oil heat exchanger fails, water can get into the oil, which leads to the breakdown of the oil film. At this time, the rotor is rotating at high speed, generating significant axial forces. By the time it’s possible to remove the bearings from the rotor, it is likely that this situation has already occurred. Another reason is excessive axial force; for example, improper control in the upstream process can result in liquid being present in the gas flowing through the compressor, which causes the outlet pressure to rise suddenly. This increase exceeds the bearing capacity of the oil film, leading to its breakdown. Once the compressor stops operating, this phenomenon becomes apparent. Therefore, it is difficult to draw conclusions based solely on this phenomenon; other parameters prior to parking must be taken into account to make an accurate judgment. Conclusion: 1. The thrust bearing was installed in the wrong direction, preventing the formation of an oil wedge and resulting in wear and damage within one hour.