Because the axial current caused by the rotor charged ultimately causes damage to machine components in the early emergence of biogas generator, so generally the formation of shaft current and electromagnetic effects associated. With the application of centrifugal compressors driven by steam turbines in large petroleum and chemical plants, especially in fertilizer plants, the problem of shaft current affecting the long-term safe operation of biogas generators has become increasingly prominent. It is produced in thrust bearings, radial bearings, coupling, floating ring seals and transmission gears of biogas generators. The electric spark discharge damages the metal surface and destroys the formation of oil film. If this damage is not detected in time, it will bring many problems to the operation of the machine, and may cause severe damage to the main components of the machine.
The introduction of shaft current fault is relatively rare, in this connection with the actual problems encountered in production to do a simple introduction.
Rotating shaft must adopt a certain lubrication way to keep the rotor and bearings in direct contact, that is, the entire rotor and stator in high-speed rotation between the oil film insulation. Because the rotor has resistance to the ground, once charged, it will establish a voltage to the ground, when the voltage rises to a certain value, it will break down in the area of the smallest resistance, spark discharge occurs. The main consequences of this discharge are as follows:
(1) melting metal particles in the discharge area and forming tiny electrical pitting on the metal surface.
(2) The pits make the surface rough and lose luster. If they occur on the bearing bush, pure mechanical wear will occur.
(3) The molten metal particles enter the lubrication system, causing the lubricant to be polluted, the lubrication function of the whole lubrication system deteriorates, and the lubricant containing a large number of metal particles will reduce the oil film resistance and accelerate the progress of EDM corrosion.
(4) Local high temperature occurs in bearing bearing bearing area, which destroys oil film, burns out metal, increases wear and eventually causes severe friction damage.
In the rotor system of rotating machinery, the most easily discharged parts are the bearing surface of radial bearing and thrust bearing, the working tooth surface of tooth coupling and the sealing surface of floating ring. These parts may cause oil because of various premises (such as load, temperature, lubrication condition and rotor vibration, etc.). The film and air gap resistance decrease, resulting in EDM phenomenon at these locations.
For radial journal bearings, the development of electric erosion pits in bearings will cause severe erosion on the surface of Babbitt alloy. This will not only change the original clearance of bearings, but also lead to surface abrasion and scratches, local high temperature along burn. The wear of Babbitt alloy on the surface of high-speed light-load bearing will cause a part of bearing bush to lose the preloading effect on the rotor journal. The oil film whirl is easily induced when the rotor rotates, resulting in the rotor system is not disturbed. On the other hand, the disorderly oil film will cause a sharp drop in the resistance of bearing oil film, make more shaft electricity flow smoothly through this area, aggravate the role of electric spark, excite each other, and ultimately lead to the damage of bearing or rotor system.
This article is supported by biogas generator. For more details, please click on our official website at http://www.huannengpower.com. We will provide you with satisfactory service wholeheartedly.