The first device has been in operation for nearly two years and no similar problems have occurred. After consulting the manufacturer's design personnel, the relevant design has been accounted for, the drawings have passed the audit, and there should be no problems in the design.
2.3 Analysis and judgment of the reasons for the machine manufacturing and installation steps a. The cause of the imbalance of the compressor rotor.
B compressor bearing vibration 4 0.00-100.00C compressor bearing vibration 1 speed encoder signal rotor is the core part of air compressor, in the process of manufacturing, there are shape asymmetry, material unevenness, heat treatment deformation, processing and Due to assembly errors and the like, there is inevitably a manufacturing process error that creates an imbalance. The imbalance of the rotor must be removed from the factory by static and dynamic unbalance, and the rotor of the machine has been tested by the manufacturer at high and low speeds. If the dynamic balance of the rotor changes after a period of time, the amplitude of the unit is changed from small to large. From the comparison and analysis of the vibration history curve, the vibration average value of the machine has certainly increased, but the vibration value has been showing fluctuations in the high and low fluctuations of the plant, which is not consistent with the phenomenon of imbalance of the rotor and should be excluded. The frequency test and diagnostic analysis of the rotor vibration also verified that the rotor did not have an imbalance. b. Reasons for machine installation.
a). Improper installation causes friction in which the moving and static parts are loose.
Friction occurs in the static and dynamic parts, which are related to improper installation or high temperature of the unit, deformation of components, loose parts, etc. The characteristic phenomena of vibration are as follows: vibration is intensified, vibration frequency distribution is wide, and the range is 2~8 times. Unusual noise can be heard at frequency, start or stop. Since the equipment can't stop at random during production, whether there is abnormal sound when starting or stopping can't be tested, but the vibration data of the machine is intensified, and the vibration frequency analysis range is also inconsistent with this. It is basically possible to determine the possibility of friction in the moving and static parts. Very little sex.
If the coupling is poorly aligned during installation, its characteristics should be: the vibration is usually increased on the bearing near the coupling, the vibration random group load increases and the vibration frequency is 2~3 times lower frequency frequency. In this case, the bearings at all levels change, and the vibration does not increase after the load increases.
c). Bearing failure caused by improper installation.
If the oil circuit is blocked by foreign matter in the oil circuit system during installation, the oil may be damaged or the bearing may be damaged. The looseness of the fastener may also cause the bearing clearance to expand. The vibration caused by such failure is generally: unit vibration Increase, oil temperature rises and even exceeds normal values. However, the bearing temperature of the machine does not change too much, and the oil temperature change is not obvious when the vibration changes, and the cause of the bearing failure can be basically eliminated.
2.4 Analysis and Practice of Vibration Caused by Rotation and Surge of Airflow The occurrence of surge phenomenon of centrifugal air compressor involves two factors: the airflow of the centrifuge under the conditions of "rotational disengagement" and the joint network system of the unit The characteristics are suitable, causing the surge phenomenon of the centrifugal compressor, and the cause of the surge phenomenon is caused by other objective factors and improper control operations. From the investigation of the fault phenomenon in this example, we have found that the vibration and the abrupt change in the vibration abnormality are related to the temperature change of the suction port gas. The vibration frequency and amplitude of the machine caused by surge are closely related to the volume of the pipe network. When the temperature of the suction port changes, the density of the air will inevitably cause the change of the actual pipe network capacity. The self-controlled operating system controls the inlet guide vane according to the constant output pressure. Degree, when the external conditions change, the operating system performs a series of automatic regulation to maintain the constant output pressure of the air compressor. During the regulation process, the phenomenon of “rotation and detachment†of the airflow will cause the vibration of the compressor rotor to occur. When the characteristics of the combined joint working pipe network system are just right for the surge condition of the centrifugal compressor, the surge will occur and the vibration will suddenly change. produce. Centrifugal compressor products are generally equipped with a pressure-flow characteristic curve. According to the equipment specification, the pressure-flow characteristic curve of the machine is checked. It is found that the pressure-flow performance curve expected from the description of the air compressor differs greatly from the actual operating parameters. More progress indicates that the reason for the surge is possible. In the actual operation, the verification is arranged. By manually adjusting the outlet pressure setting of the air compressor, it can be observed that reducing the outlet pressure change of the air compressor can affect the vibration amplitude, and attempting to change the operation when the vibration mutation occurs, manually and quickly Open the outlet relief valve to reduce the air compressor pressure, then it can be found that the sudden increase in amplitude will be suppressed and gradually reduced. Therefore, it is determined that the fundamental cause of abnormal vibration fluctuation and sudden change of the air compressor equipment is caused by the air compressor rotation and the objective factors such as the outside and the pipe network and the uncomfortable adjustment of the unit operation.
3 Elimination of vibration fluctuations of air compressors According to the above analysis, the vibration fluctuations and sudden changes of air compressors are mainly related to the change of the state of the external pipe network and the adjustment of the operation of the unit, but not related to the mechanical equipment itself. According to the analysis results, the operation status of the unit is monitored and adjusted in the process, and the operating system is adapted to the change of the pipe network status. The unit was subjected to anti-surge test using a short-term shutdown opportunity. The operation control system of the unit was improved based on the anti-surge vibration test data, and the operation of the unit was adjusted. The post-re-machine operation is in good condition, and the vibration fluctuation and sudden change of the air compressor are completely eliminated.
Through careful research and scientific judgment, a major failure of a vibration anomaly is quickly and accurately eliminated. This not only saved a lot of expenses for the original dismantling and repairing of the machine, but also freed precious time for production, created considerable economic benefits, and solved a large-scale oxygen production system in Handan Iron and Steel Co., Ltd. problem.
The large-scale centrifugal air compressor is the key equipment of the metallurgical enterprise. The reason for the vibration is theoretically analyzed, and the actual judgment is combined with the actual situation, which can greatly help the maintenance and operation of the equipment and avoid the equipment. It is very important to have a production accident.
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