Bearings are the key structural components of hydro-generator units. The pros and cons of their operating performance directly affect the level of unit operation reliability. The bearing accident rate accounts for a large proportion in the unit operation accidents. The reason is that, in addition to the low level of design and manufacturing quality, most of them are caused by insufficient maintenance and operation experience and improper handling and adjustment. So what exactly is it? Kaplan Turbine Design Factory will come to tell you.
I. Shaving and treatment of generator bearings.
There are two cases of generator oil dumping: internal oil dumping and external oil dumping. Internal oil dumping is the lubricating oil being thrown from the gap between the thrust head (or guide bearing journal) and the oil retaining cylinder to the inside of the generator. Lubrication is thrown from the seal between the thrust head and the cover to the outside.
1.Inside dump oil
Reasons for oil dumping:
(1) When the unit is running, the rotor rotates and blows air, which makes it easy to form a local negative pressure between the lower side of the thrust head (or guide journal) and the oil surface. Formation of internal oil rejection;
(2) There are different degrees of eccentricity between the oil retaining cylinder and the inner circular wall of the thrust head (or guide journal) due to manufacturing and installation reasons, making the oil ring between the equipment very uneven. When this clearance design is small, the relative eccentricity is large, so when the inner wall of the thrust head (or guide journal) supports the static oil around it, it acts like an eccentric oil pump, making the oil ring more The large pressure pulsates, and the oil is channeled upwards, splashing over the oil block and splashing into the generator.
The following Pelton Turbine suppliers will come to tell you how:
(1) Blocking method.
The first is to install a fan in the thrust head. Fan blades can be welded above the normal oil level. When the thrust head rotates, the fan generates wind pressure to prevent the oil level from rising; it can also be welded below the normal oil level or inside the mirror plate. The blades are immersed in the oil and rotated. You can press down the oil level to prevent the oil level from rising.
The second type is to install an oil ring on the inner wall of the thrust head (or guide bearing neck). There are two types of oil retaining ring; one is closed, the gap between the oil retaining ring and the oil retaining cylinder is small; the other is open, the gap between the oil retaining ring and the oil retaining cylinder is large.
(2) Dredge Law.
Increase the clearance between the thrust head (or guide bearing journal) and the oil retaining cylinder to reduce the relative eccentricity, reduce the pressure pulsation value of the oil ring, and maintain the balance of the oil surface to prevent oil from splashing up.
2. Shake the oil outside.
Reasons for oil dump outside:
When the unit is running, the thrust head and the outer wall of the mirror plate drive viscous static oil movement, which causes the oil surface to surge and splash on the outer wall of the oil tank due to centrifugal force, which easily causes oil droplets or oil mist to escape from the gap of the oil tank cover and form an external shake the oil.
Treatment of external oil dumping:
(1) Strengthen sealing performance. A labyrinth groove is set between the main shaft and the cover plate, and a wool felt is installed in the groove.
(2) Install oil retaining ring on the outside of thrust head (or guide bearing journal) to weaken the energy of centrifugal force of oil flow and make the oil level stable. However, care must be taken not to affect the circulating cooling of the oil.
(3) Install a transom device (respirator) on the oil tank cover to make the liquid surface of the oil tank communicate with the atmosphere to balance the internal pressure.
(4) Reasonably select the oil level, and the oil level must not be too high. The normal stationary oil level of the inner circulation thrust bearing should not be higher than the plane of the mirror plate, and the normal stationary oil level of the guide bearing should not be higher than the center of the guide bearing pad. If the thrust bush and the bearing bush are in the same oil tank, the oil level should meet the requirements of medium and high oil level.
The above is how to deal with the fault caused by the bearing of the hydraulic turbine unit shared by the manufacturer of Hydraulic Turbine Generator China, I hope to help everyone.