During operation, the male rotor directly drives the female rotor. From the intake process, the gas is compressed in the sealed cogging volume and finally moved to the exhaust process. Lubricating oil pumps spray a large amount of lubricating oil into the body to lubricate, seal, cool and reduce noise. The advantages of the oil-injected screw compressor are reliable operation, long service life and easy remote control. At the same time, the screw compressor also has the characteristics of forced gas transmission, that is, the displacement is almost independent of the exhaust pressure. The shortcoming of the oil-injected screw compressor is that it produces strong medium and high frequency noise. Secondly, the screw tooth surface is a space tooth surface, and the machining precision is very high. In addition, the compressor relies on the gap to seal the gas, so the compressor can not carry liquid during operation. Oil-injected screw type 40 compressor technology, 2000, issue 6 (total 164th)
During the operation of the compressor, there is a certain gap between the anode and the anode. When a small amount of propane liquid enters the machine body, the compressor can discharge the liquid quickly under high-speed operation, so the compressor is allowed to enter a small amount during operation. Liquid. However, the compressor enters a large amount of liquid before or during the start of the operation. Due to the incompressibility of the liquid, the compressor will cause a strong impact between the anode and the anode, and the light will damage the shaft seal static sealing surface. Causes damage to the tooth surface of the cathode and the anode, damage to the bearing, bending of the shaft, and even cracks in the casing.
2 screw compressor design and setting parameters
The design parameters of the compressor are: design pressure (maximum) 2500 kPa, speed 3600r/min. The working parameters set on the microcomputer when the compressor is actually running are: intake pressure 110kPa, maximum shutdown exhaust pressure 2100kPa, alarm Exhaust pressure 2050kPa, maximum shutdown exhaust temperature 100, alarm exhaust temperature 90, maximum shutdown lubricant temperature 75, alarm lubricant temperature 70, filter pressure difference is 172kPa. According to process design requirements, the equipment in the natural gas processing plant process After working normally, its working parameters should reach: flow rate 8480kg/h; inlet pressure 105bar*; outlet pressure 19 bar; inlet temperature -392; lubricating oil temperature control 55~ 65.
3 screw compressor shaft rotation and the cause of cracks in the shell
31 compressor rotor can not move
Under normal circumstances, the reasons for causing the rotor of the compressor to turn around are as follows: The 311 compressor is overloaded for a long time.
The compressor is overloaded for a long time, causing the rotor tooth surface and bearing fatigue to damage the stuck shaft. This situation is unlikely because the compressor has a discharge pressure of only 19 MPa during the test run from October to December 1998, which is lower than the maximum discharge pressure of the compressor design of 25 MPa. The maximum shutdown pressure set on the microcomputer for protecting the compressor is 21 MPa. And after the external technician walks, the exhaust pressure of the machine has not been able to reach the technical requirements during normal operation. The exhaust pressure is 19 MPa, generally less than 16 MPa, so there is no overload operation.
312 compressor lubricant deterioration
Deterioration of the compressor lubricating oil causes poor lubrication of the compressor, causing excessive wear of the female and male rotors and bearings to damage and jamming the shaft. The lubricant used in this compressor is ISO-VG150, which is the designated lubricant for York. The lubricant is quality certified by York and is used for a long time, and there is no quality problem during the life cycle.
313 compressor lubricating oil line blocked
The compressor lubricating oil pipeline is blocked, causing the compressor to be short of oil, causing the anode and the anode and the bearing temperature to be too high and damaged. The compressor has set parameters such as lubricant level, oil pressure and filter pressure difference on the microcomputer. If this happens, it will automatically stop to protect the compressor.
314 compressor enters a large amount of propane liquid at startup
When the compressor starts, a large amount of propane liquid enters, and a strong impact occurs between the female and male rotors, causing the female and male rotor shafts to bend or the rotor tooth surface and bearing to be damaged. This can happen if the operator does not operate the compressor in strict accordance with the operating procedures.
315 compressor multiple times with liquid starter
The compressor is turned on with the liquid several times to cause the compressor to be yin, and the fatigue surface of the male rotor tooth surface is damaged and falls off the stuck shaft. The compressor starts when there is not much liquid, and the fourth condition will not occur, but this may happen if the liquid is started several times.
316 operation reasons
The operator does not strictly operate the compressor in accordance with the operating procedures. The compressor is not carefully checked before starting the compressor. If the valve is open, the preparation is ready, etc., after the start of the machine, the compressor is not fast until the temperature of the lubricating oil reaches 30 or higher. Load, accelerate the yin, male rotor tooth surface and bearing wear. When the wear reaches a certain level, the tooth surface and the bearing will be damaged, causing the rotor to rotate.
317 poor maintenance quality
(1) If the bearing and the yin are disassembled when the compressor is repaired, the assembly quality after the male rotor is poor, the assembly accuracy is not up to the requirement, and the anode and the anode axis are not parallel, so that the female and male rotors cannot rotate.
(2) The method of repairing the compressor is improper. An incorrect method was applied to the external force applied to the rotor, and the axial and radial gaps between the female and male rotors were changed so that they could not be rotated.
32 causes the compressor housing to crack.
321 shell quality reasons
This is basically impossible. Because the compressor has been tested and tested for water pressure and air tightness before leaving the factory.
When the 322 compressor started, it entered the propane liquid.
When the compressor starts, a large amount of propane liquid enters, and a strong impact is generated between the anode and the anode. The impact energy is transmitted to the compressor casing through the shaft and the bearing to cause cracks.
323 improper operation
If the operator does not check the compressor strictly according to the operating procedures before the compressor is running, the exhaust valve does not open when the machine starts, causing the compressor to press, or the compressor enters a large amount of propane liquid before starting the machine and does not discharge. Therefore, there is a strong impact between the male and female rotors, and the load exceeds the bearing capacity.
324 poor maintenance quality
(1) An incorrect method was taken when applying an external force to the compressor casing while servicing the compressor.
(2) When the compressor is repaired, the bearing and the yin and the male rotor are disassembled, and the assembly quality is poor, causing the yin and yang rotors to smash and the load generated exceeds the bearing capacity.
4 reasons why propane liquid enters the compressor
It can be seen from the above splitting that the screw compressor can not only rotate the rotor or crack the casing, but it is related to the large amount of liquid entering the compressor with the liquid starting or running. The reasons for starting the machine are as follows: 41 design errors.
It can be seen from the structure and working principle of the screw compressor that the screw compressor requires no liquid in the gas to be inhaled at the time of starting. The inlet line of the three screw compressors of the 1.2 million m3 natural gas processing unit in the tower is equipped with a liquid collector to prevent the propane liquid from entering the body. However, due to design errors, the inlet line of the 4-K1 screw compressor that should be placed horizontally was designed to be placed vertically about 2 m high, and the liquid collector was about 4 m before the vertical inlet line. Each time the compressor is shut down, the propane vapor condenses into a liquid in the vertical inlet line and enters the compressor through the inlet line. Since a large amount of propane liquid has accumulated in the inlet of the compressor and in the machine body, when the compressor is started, the compressor will be infuriated and a strong impact will occur between the male and the rotor, which was confirmed during the trial operation from October to December 1998. This is the case. In order to avoid this mistake, two additional rules were added in the development of the screw compressor operating procedures, namely:
(1) close the compressor inlet valve immediately after each stop of the compressor;
(2) Slowly open the inlet valve after each start of the compressor. The purpose of the first one is to prevent the propane liquid condensed in the inlet line from entering the compressor body after the compressor is stopped; the second function is to open the inlet valve after starting the compressor, so that the propane liquid is fully vaporized at the compressor inlet. To prevent propane liquid from entering the compressor. The speed of opening the inlet valve should be slow and even. If it is too fast, the vaporization of the propane liquid will be insufficient. Some of the liquid will enter the body, causing noise in the body, and it will easily damage the tooth surface of the cathode and the anode. If it is too slow, it will cause vacuum at the inlet. , causing the compressor to stop.
42 improper operation
According to the structural characteristics of the compressor, the compressor allows a small amount of liquid to enter during operation, and most of the liquid enters the liquid collector. It is only a schematic diagram of the 1RWB-676 screw compressor. When the liquid level of the collector exceeds the limit value, the compressor will automatically stop and protect. If the operator violates the operating procedures, the inlet valve is not closed after the compressor is stopped, or the inlet valve is opened before the machine is started, so that a large amount of propane liquid is entered into the compressor, which will cause a negative between the anode and the rotor when starting the machine. Produces a strong impact.
43 The compressor is shut down for too long due to production stoppage, maintenance or other reasons, causing propane to condense in the compressor body.
This usually happens in the winter. In winter, the temperature is low, and after the compressor is shut down, the propane vapor in the body will condense into a liquid. If the downtime is too long, the propane liquid in the body will be more and more until it fills the entire compressor. In theory, when the liquid level of the propane in the compressor body exceeds the anode and the anode axis, it cannot be started. Since the propane liquid is colorless and transparent, it is difficult to see from the liquid level observation hole of the compressor. If the operator does not observe carefully and does not remove the propane liquid in the body in time, it is easy to cause the liquid to start. In this case, the opportunity creates very serious consequences.
5 summary
In summary, the biggest cause of the rotor rotor not being able to rotate may be that the inlet valve is not closed in time after the compressor is stopped, and the propane liquid condensed in the body and the inlet line is not eliminated before starting the machine, so that when the compressor starts, A strong impact occurs between the female and male rotors, causing damage to the tooth surface of the male and female rotor shafts or bending of the shaft. The biggest cause of cracks in the compressor casing may be caused by the compressor coming into contact with the machine multiple times or when the compressor is repaired, the incorrect method is applied to the casing, and the external force is applied and is too large.
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