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Talking about the debugging problem in the process of mechanical equipment
Source: China Bearing Network Time: 2013-11-10
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Mechanical equipment is in the process of equipment; it is generally required to perform single-machine debugging and linkage debugging; its intention is to verify the reliability of normal operation of the equipment; however, there are often many unexpected abnormal appearances in practice. As long as it is in practice These "abnormal appearances" are useful for analysis and disposal; in order to make mechanical equipment and equipment work properly.
I. Introduction to mechanical equipment The mechanical equipment is transported by the production plant to the construction address; with some things and instruments; after necessary construction; the equipment is correctly placed in the direction of the reservation; and the operation conditions are reached after commissioning. Whether the mechanical equipment can be smoothly put into production; whether it can fully exert its functions; the service life of the extended equipment and the quality of the products produced; the quality of mechanical equipment is largely determined.
1. The general process of mechanical equipment and equipment The equipment process of various mechanical equipment generally needs to go through: hoisting and transportation, equipment unpacking inspection, placing the line in place, equipment fixing, cleaning, assembly and adjustment of parts and equipment, component testing and engineering inspection. What is different is that in these processes; different methods are used for different mechanical equipment; for example; in the process of equipment; the separation equipment method is adopted for large equipment; and the whole equipment method is used for small equipment.
2. The construction contents of mechanical equipment mainly include lifting and transportation of equipment, assembly of mechanical equipment and parts, equipment of pipe fittings, cutting and welding, equipment of internal parts of various containers, equipment of electric motors, instrumentation and active control. Equipment commissioning, pressure test and trial operation.
3. The construction equipment requirements must first ensure the quality of equipment and equipment; the correct construction should be carried out according to the drawing drawings, equipment structure drawings, equipment specifications and construction inspection specifications, quality inspection and identification specifications and operating procedures; secondly, scientific construction methods should be selected. Accelerate the progress of the project; ensure that the production is on schedule.
Second, debugging in the process of mechanical equipment and equipment. There are three reasons for the abnormally high bearing temperature of the bearing: the smoothness is poor, the cooling is not good, and the bearing is abnormal. The centrifugal fan bearing is placed outside the fan; if the bearing wears out, the temperature is increased due to the wear and tear of the bearing. Elevation. Generally, it can be judged by listening to the movement and measurement of the bearing; if the reason is not smooth, the reason for the cooling can be determined by visual inspection, hand model and other intuitive methods. The bearings of the axial fan are concentrated in the bearing housing; Below the inlet chamber; when the temperature of the bearing is high; because the fan is working; it is difficult to judge that the bearing is still a problem of smoothness and cooling. In practice, the following problems should be dealt with in the following aspects.
Top of the list; whether the refueling is appropriate should be in accordance with the rules of the manufacturer's instructions to refuel the bearing housing. After the bearing refueling, sometimes the temperature will be high; the first is to refuel too much. At this time, the appearance is that the temperature continues to rise; after reaching a certain point ( Generally, it will remain unchanged at 10 l5 °C higher than the normal operating temperature; then it will gradually decrease.
Second; the cooling fan has a small cooling air volume. The temperature of the air at the induced draft fan is 120 140 ° C; if the bearing box has no useful cooling, the bearing temperature will rise. Compared with the simple and energy-saving treatment, the bearing on the hub side is Set tight air cooling. When the temperature is low, it can be cooled without opening the air. When the temperature is high, open and tighten the air to cool. Admit that there is no such problem and then look at the bearing housing.
2. Bearing oscillation fan bearing oscillation is a common problem in the operation. The oscillation of the fan will cause damage to the bearing and the blade, loose bolts, damage to the casing and air duct; severely endanger the safe operation of the fan.
The fan itself incurs oscillation of the oscillating fan; in general, the source of the oscillation comes from itself. If the unevenness of the data of the component is changed, the quality of the rotor in which the processing error occurs is unbalanced, the quality of the equipment and the repair is poor, and the operation of the fan is poorly adjusted when the load is changed. Wear or damage; front and rear guide vanes wear and deformation, the inlet and outlet baffle opening adjustment is not in place, the bearing and bearing seat problems, etc. can make the fan oscillate under the effect of small interference force. During the operation of the fan, it is necessary to adopt a series of corresponding disposal methods to reduce or eliminate the sensation; for example, the fan impeller and the rear guide vane are wear-proof; the bearing uses imported high-quality products; the bearing box and the core end plate are connected with high-strength bolts. Adopted the anti-loose method; improved the support and fixing of the core tube; added lacing, severely repaired the process quality; added the fan operation monitoring equipment and so on.
The oscillation of the air duct system causes the oscillating flue of the fan and the oscillation of the air duct to cause the forced oscillation of the fan. This is a situation in which the production is simple and simple and neglected. The fan outlet dispersing cylinder increases with the load. The intake and output air volume Increase. The oscillation will also change; the lower part of the general dispersion tube only needs 4 fulcrums; the other side of the joint asbestos canvas is a soft joint. This makes the 60% component of the entire dispersion tube a suspension force. a condition; add a live fulcrum below the outlet end of the dispersing barrel; can be raised or lowered to move. When the unit load changes; only need to fine-tune the fulcrum;
3. Surge in the process of the fan operation; when the flow rate is continuously reduced to the Qmin value; the airflow entering the cascade is separated; in the other direction, along the direction of the impeller rotation and at a speed lower than the angular velocity of the impeller; this is the rotation. Rotating and dispersing to the entire channel; the fan outlet pressure will drop sharply; and the pressure in the pipe network does not drop immediately; therefore, the gas pressure in the pipe network is greater than the pressure at the fan outlet; the gas in the pipe network flows back to the fan Until the pressure in the pipe network drops below the fan outlet pressure. Then, the blower starts to supply air to the pipe network; the backflow gas is pressed out; this in turn reduces the flow in the machine; the pressure drops again; the pipe network The gas in the tank flows backwards into the fan; this cycle reciprocates; periodic low-frequency and high-amplitude pressure pulsation and airflow oscillation appear in the whole system; and announces a large movement; the machine violently oscillates; Surge. Can enter the surge condition; can be judged according to the different conditions of the fan operation.
The top of the list; listen to the airflow noise of the fan outlet pipe. In the near surge condition; the noise declared by the airflow in the air outlet pipe is high and low; the periodic changes are made. When entering the surge condition, the noise increases sharply; There is a popping sound.
Second; observe the fan outlet pressure and import flow changes. The normal operation of its export pressure and import flow changes little; when entering the surge zone; both changes are very large.
Third; observe the oscillation state of the body. When entering the surge zone; the body and the bearing will have intense oscillations. The first way to avoid surge is to use the air duct to deflate. Set the bypass pipe on the air outlet pipe; once the air volume drops To the Qmin value; the valve on the bypass pipe actively opens the air; at this moment, the inlet flow is added; the operating point can be moved from the surge zone to the stable operation zone; then the intake flow is small, the angle of attack is too large, and the stall and the asthma are caused. The possibility of vibration. When the inlet guide vane is used to adjust the air volume; follow the working condition change; the vane rotation changes the passage area to the new working condition; then avoid the gas loss speed; it can be used to avoid the fan surge.
4. The moving leaf card axial fan fan blade conditioning is completed by changing the oil pressure difference between the two sides of the hydraulic cylinder through the transmission mechanism of the sliding valve. In the operation of the axial fan; sometimes the appearance of the moving blade conditioning is difficult or completely unregulated. This representation is generally considered to be the problem of the fan conditioning oil system and the internal conditioning of the wheel hub. However, in practice, there is generally another reason; there is a certain open space between the fan blade and the hub to complete the conditioning of the blade view. However, it does not completely burn the carbon scale or dust to block the open space. It is difficult to adjust the moving leaves. The appearance of the moving leaves is more common in oil-fired boilers and boilers that use water film to remove dust. The main treatment methods are:
Top of the list; try to make fuel or coal incineration in the commissioning operation; cut carbon black; properly improve the exhaust temperature and inlet air temperature; avoid the condensation of sulfur in the flue gas in the air preheater.
Second; set the steam purge pipe at the impeller inlet; clean the impeller when the fan stops; adhere to the impeller hygiene; steam pressure ≤ 0. 2Mpa; temperature ≤ 200 ° C.
Thirdly; when adjusting the opening degree of the moving blade; avoiding the blade forming a scale at a certain opening for a long time; the moving blade should continuously move at 0 to 55° after the fan is stopped.
Fourth; often look at the moving blade transmission tissue; properly add smooth oil.
In general, with the progress of China's machinery production level; the functions, power and reliability of various types of machinery and equipment are catching up with or surpassing similar products from abroad; however, there are still many problems in the practice of debugging and debugging; All the operations before the commissioning work; pay close attention to the mechanical equipment; abnormal appearance in the course of the work; strengthen the protection work, etc. are the key to improving the reliability of mechanical equipment.
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