Compressor host of screw air compressor: The core component of screw air compressor is compressor host, which is a kind of positive displacement compressor. Air compression is realized by the volume change of the cogging of the convex rotor and the concave rotor installed in the shell and engaged in parallel with each other. The rotor pair rotates in the casing which is closely matched with it, so that the gas between the rotor cogging constantly produces periodic volume changes and is pushed from the suction side to the exhaust side along the rotor axis, completing the three working processes of suction, compression and exhaust. Therefore, the profile technology of twin-screw rotor determines the product positioning level of screw air compressor. Screw air compressor 1 working principle process, the bearing running out of the outer ring is generally caused by insufficient matching accuracy and unreasonable design of the positioning mode of the outer ring. Generally speaking, the design of screw heads is similar, and there is no design problem in structure. The appearance of the outer ring is mainly caused by machining errors of individual head parts. Of course, this phenomenon is difficult to maintain, because once the outer ring deviates, it will inevitably lead to increased wear of bearing holes, so that its fit can not meet the design requirements. You can think about specific solutions through different structures. 2. If the screw rotor has been seriously worn, that is, when the gas replacement caused by leakage can no longer meet the gas demand of users, it must be repaired. When repairing, it can be sprayed on the screw machine. However, because most service providers do not have such strength, it is difficult to complete. Of course, it can also be repaired manually after spraying, which requires knowing the specific profile equation of the screw, machining a module for manual repair, and designing a set of special tooling to complete the repair work. 3. Generally speaking, if the twin-screw die is used for more than ten years (as long as it is used normally), the wear of its rotor is not obvious, that is to say, its efficiency will not decrease too much. For normal maintenance, bearings can be replaced in about 25,000 hours to 30,000 hours. (Not all headsets are carried out according to this time. If it is well maintained, it can be postponed; if it is not well maintained, it needs to be advanced).
When the screw pump works, the liquid is sucked into the sealed space surrounded by the thread and the pump shell. When the driving screw rotates, the sealing volume of the screw pump increases the pressure of the screw pump under the extrusion of the thread and moves along the axial direction. Because the screw rotates at a uniform speed, the liquid outflow is also uniform.
Screw pump uses the rotation of screw to suck and discharge liquid. 38+0 in 438 of figure 65shows the sectional view of three screw pump. In the figure, the middle screw is the driving screw, which is driven by the prime mover, and the screws on both sides are the driven screws, which rotate in the opposite direction to the driving screw. The threads of the driving screw and the driven screw are both double-headed threads.
Due to the mutual engagement of the screws and the close fit between the screws and the inner wall of the bushing, one or more sealed spaces will be separated between the suction port and the discharge port of the pump. With the rotation and meshing of the screw, these sealed spaces are continuously formed at the suction end of the pump to seal the liquid in the suction cavity, and continuously push the liquid from the suction cavity to the discharge end along the axial direction of the screw, and continuously discharge the closed liquid in each space, just like pushing the nut forward when the screw rotates. This is the basic working principle of screw pump.
Screw pumps include single screw pump, double screw pump and three screw pump.
The working principle of screw pump is: when the screw pump works, liquid is sucked into the sealed space surrounded by thread and pump shell. When the driving screw rotates, the sealing volume of the screw pump is squeezed by the screw teeth, which increases the pressure of the screw pump and moves along the axial direction. Because the screw rotates at a uniform speed, the liquid outflow is also uniform.
Screw pump can transport lubricating oil, fuel oil, various oils and polymers for transporting viscous liquids.
Screw pump is characterized by low loss and good economic performance. High and uniform pressure, uniform flow and high rotation speed, which can be directly connected with the prime mover.
1. Install the compressor correctly.
The correct installation of the compressor can ensure that the compressor works according to the design parameters. If it is not installed correctly, it will lead to a series of problems such as high exhaust temperature, large vibration and abnormal noise. Firstly, the air compressor is installed on a solid ground, and the equipment foundation is cast-in-situ with C20 concrete. Two axial flow fans are respectively installed on the wall opposite to the air intake grille of each air compressor in the air compressor workshop, with the elevation of 1.6m, and the air speed of the air intake grille does not exceed1.5m/s. The designed ventilation volume of the axial flow fans is consistent with that of the compressor fans, which ensures the smooth ventilation system. In order to ensure that the air pressure drop in the cooling duct does not exceed 30Pa, the cross-sectional area of the exhaust duct from the outlet of the compressor should be 2 ~ 3 times that of the top of the air compressor. And the ventilation pipe is not contracted. For other types of screw compressors, if the air pressure drop in the cooling duct exceeds 30Pa, a ventilator should be installed at the outlet of the cooling duct to ensure that the compressor outlet temperature is controlled within the normal range. At the initial stage of air compressor operation, the exhaust temperature of ventilation system is as high as 108℃. Through the analysis of the reasons, it was found that there were more tree hairs in the air in May, which blocked the plate-fin heat exchanger and affected the heat transfer effect of the outlet gas. In order to prevent tree hair from blocking the plate-fin heat exchanger, 60 mesh stainless steel mesh was installed at the entrance of two axial flow fans, and the effect was very obvious. In addition, in the future operation process, the plate-fin heat exchanger should be purged regularly, so that the exhaust temperature will not be high in the future.
2. Set parameters reasonably
After the compressor is installed, it is the basic guarantee to ensure the normal gas supply of the compressor to debug the compressor, correctly and reasonably set the loading and unloading pressure of the compressor and the number of motor starts per hour. In addition, reasonable setting of loading time and motor starting times can prevent the compressor from being in the state of big horse-drawn car for a long time. Correctly installing and debugging the compressor can make the equipment in an efficient and stable running state and prolong the service life of the equipment. According to the gas supply requirements of the device, the designed loading pressure is 6 12Bar and the unloading pressure is 8Bar. From commissioning to present operation, this set value can ensure the normal operation of the device, especially meet the instrument air requirements of the cryogenic device.
3. Strengthen daily maintenance.
When the equipment is running, it needs frequent maintenance. Planned maintenance can make the compressor have the best use efficiency and prolong the service life of the equipment.
(1) Change the lubricating oil in time. Lubricating oil plays three main roles in oil injection screw compressor: one is to lubricate bearings, speed-increasing gears and screws; The second is to play a cooling role and take away the heat generated by the rotating parts in time; The third is to play a sealing role and increase the output air pressure. Therefore, the key to ensure the normal operation of the whole transmission system is the quality of lubricating oil. The equipment manufacturer suggests using special lubricating oil to protect the screw system directly driven by the motor. Its special formula ensures the full play of compressor performance and prolongs the life of moving parts. At the same time, the unique formula makes it have good oil-gas separation performance, lubrication performance, carbon deposition prevention performance and excellent heat dissipation performance. Using special lubricating oil can extend the replacement cycle of moving parts from 2000 hours to 4000 hours, thus saving costs. According to statistics, paying attention to the maintenance of lubricating oil can reduce the failure rate by 50%. Poor quality of lubricating oil or untimely oil change may lead to abnormality and noise of the main engine of oil injection screw. Long-term carbon deposition on the screw surface of air compressor and bearing damage may cause the main engine of oil injection screw to bite. So change the lubricating oil in time. In addition, the motor grease should be replenished regularly, and 15 ~ 20 Rotoglide grease should be added every 2000h to prevent motor damage.
(2) Prevent the motor from reversing. Motor reverse rotation is easy to cause shaft damage, gear fracture and screw locking.
(3) Clean the air filter in time. When the inlet air filter of GA37P- 10 oil injection screw compressor is cleaned, only 98% impurities can be filtered out, and the remaining 2% dusty air enters the compressor. In the process of operation, dust, water mist, acid mist and oil mist will inevitably be inhaled in the air. If there are a lot of dust and impurities in the air, if the air intake filter is not cleaned in time, the combination of water mist and dust will block the gear teeth and affect the transmission effect. Acid mist inhaled into the body will corrode parts. This model is an oil injection screw air compressor. The dust in the air comes into contact with the lubricating oil, which pollutes the lubricating oil, reduces the quality of the lubricating oil and affects the lubrication of the bearing, thus affecting the whole transmission system.
4) Check the compressor regularly for running, running, dripping and leakage. Regularly check whether the automatic condensate drain valve is unobstructed and whether the drainage volume is normal, so as to ensure that the water separated from the outlet gas can be discharged in time.
4. Common faults of annular air valve
The air valve is one of the most important and easily damaged parts in the air compressor, and the failure of the air valve is usually the main reason for the unplanned shutdown of the air compressor. Compared with air compressor components, the air valve is the most sensitive, and its quality directly affects the economy and reliability of air compressor operation. Therefore, the relevant design documents and operating procedures stipulate that the valve must be inspected and maintained regularly to minimize the occurrence of valve failures.
The air velocity, valve plate lift and spring force have direct influence on the working condition of air valve. Common faults of annular air valve are: (1) air leakage caused by abrasion of sealing edge between valve seat and valve plate; (2) The valve body is cracked or even broken, which makes the valve invalid; (3) The spring of the air valve loses its elasticity, which leads to the serious knocking of the air valve at work, leading to the early damage of the air valve. Among them, the consequences of valve rupture are the most serious. Fracture of valve seat, valve plate and center bolt will cause "cylinder collision" accident of air compressor, which will seriously damage cylinder, piston, piston rod and crosshead. Wear-resistant covered electrode
How to maintain screw air compressor
Daily maintenance project
1, check the empty filter element and coolant level;
2. Check whether the hose and all pipe joints are leaking;
3. Check the records. If the wearing parts have reached the replacement cycle, they must be stopped and replaced;
4. Check the records. When the exhaust temperature of the main engine reaches or approaches 98℃, the oil cooler must be cleaned.
5, check the condensate discharge, if found that the displacement is too small or no condensate discharge, must stop cleaning water separator.
Monthly maintenance project
1, check the surface of the oil cooler and clean it if necessary;
2. After cleaning the cooler;
3. Check that all wires are connected and fastened;
4. Clean the dust on the surface of the air inlet of the motor and the surface of the shell;
5. Clean the oil return filter.