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KR-20260067668-A - Turbo Machine Capable of Expending Lifespan of Air Bearings

KR20260067668AKR 20260067668 AKR20260067668 AKR 20260067668AKR-20260067668-A

Abstract

A turbomachine capable of extending the lifespan of air bearings is introduced. The turbomachine is configured such that when the rotational speed of the rotor (21) is below a reference value, an electromagnet (30, 40) operates to support the rotor (21) by a rolling bearing (61, 62). The rolling bearing (61, 62) is of the outer ring rotation type and includes a first rolling bearing (61a, 62a) that supports the rotor (21) below the center of rotation of the rotor (21), and a second rolling bearing (61b, 62b) that supports the rotor (21) above the center of rotation of the rotor (21).

Inventors

  • 김정일

Assignees

  • (주) 터보맥스

Dates

Publication Date
20260513
Application Date
20241106

Claims (5)

  1. A turbomachine comprising a housing (10), a rotor (21) and a stator (22) housed within the housing (10), an impeller (9) connected to the front end of the rotor (21), and journal air bearings (6a, 6b) for supporting the rotor (21) in a radial direction, Ferromagnetic bodies (24, 25) provided in the rotor (21) above; Electromagnets (30, 40) provided in the above housing (10) and positioned facing ferromagnetic bodies (24, 25) to pull the rotor (21) in a radial direction when operated; and It includes rolling bearings (51, 52, 61, 62) disposed at the front and rear ends of the rotor (21) so as to support the rotor (21) in a radial direction when the above electromagnets (30, 40) are operated, A turbomachine configured such that when the rotational speed of the rotor (21) is below a reference value, the electromagnet (30, 40) operates so that the rotor (21) is supported by rolling bearings (61, 62).
  2. In claim 1, the electromagnet (30, 40) is, A turbomachine configured to pull the rotor (21) in the 3 o'clock or 9 o'clock direction based on the axial view of the rotor (21).
  3. In claim 1, the rolling bearing (61, 62) is of the outer ring rotation type, When the above electromagnets (30, 40) are operated, they are arranged to support the rotor (21) in alignment with the rotor support surface (3a) of the journal air bearings (6a, 6b) or to support the rotor (21) radially inward from the rotor support surface (3a). A turbomachine positioned between 2 o'clock and 5:30 or between 6:30 and 10 o'clock based on the axial view of the rotor (21).
  4. In claim 3, the first rolling bearing (61a, 62a) has its rotation center (X2, X4) positioned between 4 o'clock and 5:30 or between 6:30 and 8 o'clock, and The above second rolling bearing (61b, 62b) is a turbomachine with its rotation center (X3, X5) positioned between 2 o'clock and 3 o'clock or between 9 o'clock and 10 o'clock.
  5. In claim 1, the rolling bearing (61, 62) is of the outer ring rotation type, When the above electromagnets (30, 40) are operated, they are arranged to support the rotor (21) in alignment with the rotor support surface (3a) of the journal air bearings (6a, 6b) or to support the rotor (21) radially inward from the rotor support surface (3a). A first rolling bearing (61a, 62a) supporting the rotor (21) below the center of rotation of the rotor (21), and A turbomachine having a second rolling bearing (61b, 62b) that supports the rotor (21) above the center of rotation of the rotor (21).

Description

Turbo Machine Capable of Expending Lifespan of Air Bearings The present invention relates to a turbomachine, in particular, a turbomachine capable of reducing damage and extending the lifespan of an air bearing. Turbomachinery, such as turbo blowers and turbo compressors, is known for transferring energy between a rotor and a fluid. Turbo blowers utilize the rotational force of an impeller coupled to a rotor to blow air at high speeds and are widely used in industrial sites requiring the blowing of pressurized air, such as aeration facilities in sewage or wastewater treatment plants and powder conveying. The rotors of high-speed rotating turbomachinery are non-contact supported by air bearings or magnetic bearings. Non-contact bearings are suitable for high-speed turbomachinery because they do not require lubrication and produce less friction and noise. Air bearings are hydrodynamic gas bearings that use gas as a lubricant; a gas film builds up between the rotating rotor and the air bearing, causing the rotor to levitate. Air bearings are used in high-speed rotating machinery due to their low power loss and excellent high-speed stability. Air bearings consist of an elastic bump foil and a top foil covering the bump foil. An air film is built up between the rotor and the top foil, and the bump foil elastically supports the top foil. Air bearings are classified into thrust air bearings for axial load support and journal air bearings for radial load support. An example of a journal air bearing is shown in Fig. 1. Referring to FIG. 1, the journal air bearing is positioned between the bearing sleeve (2) and the rotor (1) and supports the rotor (1) in a direction perpendicular to the axis of rotation. The journal air bearing is equipped with a top foil (3) that directly supports the rotor (1) and a bump foil (4) that provides substantial damping performance. Although an arched bump foil (4) is shown in FIG. 1, it can be configured in other forms, such as a cantilever type. Air bearings do not come into contact with the rotor during high-speed rotation in a normal state. However, during the starting phase from a standstill until the rotor is lifted, the braking phase from the lifted state until the rotor comes to a stop, and during the shutdown phase, air bearings, particularly journal air bearings, are subjected to the load of the rotor and experience the accumulation of fatigue damage. Frequent shutdowns and emergency shutdowns place extreme stress on the air bearings, causing deformation and damage to the air bearings. Deformed or damaged air bearings cannot properly support the rotor. For example, if any of the journal air bearings at both ends of the rotor are severely deformed or damaged, the rotor will exhibit abnormal behavior and cause vibration. In severe cases, the impeller may strike the impeller housing and be damaged. If the damage to the air bearing is extensive, or if the damage is exacerbated by repeated attempts at operation, the impeller may be severely damaged to the point of being unusable. Deformation or damage to air bearings can lead to the failure of key drive components of turbomachinery. To prevent damage to the impeller or rotor, the turbomachine is immediately controlled to a braking mode if the rotor exhibits abnormal behavior. Although air bearings theoretically have a semi-permanent lifespan when the motor is operated continuously without stopping, a reduction in lifespan due to fatigue accumulation is unavoidable when applied to processes with frequent stoppages. While lubrication and wear-resistant coatings are sometimes applied to air bearings to improve durability, there are limitations. In the case of heavy rotors, mechanical friction with the air bearings increases proportionally to their weight, making the reduction in air bearing lifespan a more significant issue. Air bearings used in processes involving frequent start-ups and stop-ups rank high among the repair items for turbomachinery, and their replacement cycles are short. Since replacing air bearings requires shutting down the turbomachinery in operation, there is a high demand in industrial settings for extending their lifespan. (Patent Document 1) Korean Patent Publication No. 2013-0024405 (Publication Date: March 8, 2013) (Patent Document 2) Korean Patent Publication No. 2017-0116417 (Publication Date: Oct. 19, 2017) Figure 1 shows a schematic cross-section of a journal air bearing. FIG. 2 shows a schematic cross-section of a turbomachine according to an embodiment of the present invention. FIG. 3 shows turbomachine operation control according to an embodiment of the present invention. Figure 4 shows the air pressure profile around a rotor supported by a journal air bearing. FIGS. 5A and FIGS. 5B show rolling bearings according to an embodiment of the present invention, FIG. 5A shows a rolling bearing at the front end of the rotor, and FIG. 5B shows a rolling bearing at the rear end of the rotor. FIGS. 6a to 6c show