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First, the cause and elimination of the heat of thrust bearing
1. Cause of failure
There may be three causes of failure: (1) Insufficient roughness of thrust disk surface; (2) high speed of bearing surface line; and (3) excessive shaft tolerance. The main reason is that the axial endurance is too large after analysis. The compressor rotor is made up of four impellers and balanced drums in series on the spindle, and has a balanced cheer chamber, TE218 thrust bearing at the end of the bearing box, while the TE201 thrust bearing operating temperature is 81 ℃, indicating that the balance drum balance force is less than four impeller produced axial force, the air seal clearance on the balance drum is reduced, Reduces the balance of power. After more ventilation seal, the temperature of the TE218 measuring point no longer rises, remains in the 98~99℃, is still close to the alarm value of 100 ℃, indicating that the shaft tolerance is still too large.
(1) Increase the pressure difference before and after the balance drum to reduce the shaft tolerance
The most direct way to increase the balance force is to increase the diameter of the balanced drum, but its transformation is difficult and costly. Another method is to reduce the pressure of the gas chamber after balancing the drum into negative pressure, increase the pressure difference before and after the balance drum to improve the balance force. For this reason, the hole is drilled in the worm shell of the gas chamber after the balance drum, and the DN50 pipe is connected to the compressor level air inlet, so that the balanced gas chamber forms a certain negative pressure. As shown in Figure 1, the TE218 operating temperature of 93℃,te201 is 83 ℃ under the oil temperature of 45 ℃.
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(2) Reduce shaft tolerance by using motor magnetic lines that do not coincide
Although the balance tube solves the partial equilibrium force, it is necessary to increase the vacuum system to achieve full balance, but adding equipment to the compressor is not only complex and not easy to operate. The growth machine transmission gear for the character teeth, from the motor to the compressor coupling for the elastic diaphragm coupling, you can consider using the motor magnetic force to balance the thrust shaft tolerance. When the compressor unit is in the right direction, adjust the axial dimension of the coupling to the maximum (1.7mm), and adjust the magnetic centerline of the motor and the position of the center line of the rotor to deviate from 4mm, so that the magnetic force when the force is opposite the axis of axial tolerance, and through the elastic diaphragm coupling transmission, you can reduce the shaft tolerance accordingly. After finding the positive, the TE218 bearing temperature is low 3℃,te201 temperature is 83 ℃.
During the trial run, the TE218 also appeared temperature rebound to 94 ℃, the inspection found that tile blackened, the middle of the housing has carbon accumulation, further analysis is considered to be a small amount of lubricating oil, bearing heat belt does not go.
Second, the reason why the lubricant takes away the low heat
(1) Insufficient supply of oil and too high oil temperature;
(2) Lubricating oil spoilage;
(3) The oil supply, oil return structure is unreasonable.
According to the site monitoring, hydraulic >300kpa, oil temperature 45 ℃ are normal. The bearing seat structure is analyzed and the lubricating oil is found to supply thrust bearings from both sides of the housing, but the bearing has no discharge point, forming the dead zone, the heat can not be taken away, thus producing carbon accumulation. To this end, two holes are drilled on both sides of the middle of the housing, and the discharge point is increased by opening two halves of the outer groove close to the two holes on the bearing cover. After the change of thrust bearing operating temperature reached normal.
ET218 bearings will increase the amount of lubrication oil supply after changing the oil return, resulting in a reduction in the amount of oil supply to other bearings. Therefore, it is necessary to adjust the oil pressure of the ET218 bearing distribution point from 280kPa to 250kPa, and the oil pressure of other bearing distribution points remains unchanged.