Innovation of alkane air compressor valve and production technology of valve material
1 question raised Piston compressors are widely used in various sectors such as machinery, chemical engineering, and metallurgy, and the reliability of their work is extremely important. The gas valve is one of the key components in the piston compressor. Its performance has a great influence on the reliability and economy of the compressor. A good gas valve has a long life and high efficiency. . The life of the gas valve directly affects whether the production can be carried out in a planned manner. The accidental shutdown not only affects the production, but also affects the production cost of the enterprise. The good valve life can reach 8 000 h or higher, and the poor valve It is less than 300 hours, and some may even be damaged in a few days, causing accidents to stop frequently. Therefore, increasing the life of the valve is important to ensure reliable operation of the compressor. The flow resistance loss generated by the gas valve during normal operation of the machine is about 3% to 5% of the power of the compressor shaft, and the flow resistance loss of the poorly designed gas valve is as high as 15% to 20% of the power of the compressor shaft. In the piston type compressor, various types of air valves, such as a ring valve, a mesh valve, a strip valve, etc., are used, and the valve of the domestic compressor mostly adopts a ring valve structure. A 4L - 20/ 8 oil-free propane gas compressor of the Yanshan Petrochemical Company's refinery in Beijing uses a gas valve with a ring-shaped valve structure, which is often damaged during operation. Sometimes the gas valve is replaced once in a few days, which seriously affects The production is carried out normally. 2 reasons analysis The main advantages of the annular valve are simple structure, convenient manufacture and strong versatility. However, the movement quality of the valve plate of this structure is large, and there is friction between the valve piece and the guide block, which determines that the valve piece is not easy to be timely and rapid when it is opened and closed without oil; the rings of the valve piece are separated from each other, It is difficult to make the pace consistent in the process of opening and closing, thus reducing the flow capacity of the gas; the buffering effect of the valve sheet is poor, because the metal foil is easily deformed and broken after use. The above problems limit the use of ring valves in oil-free compressors. In addition, the calculation of the valve is unreasonable, making the movement of the valve plate unreasonable, which is one of the reasons for the valve to be easily damaged. 3 structural improvement measures In response to the above problems, the gas valve structure of the oil-free compressor has been improved, and a valve type gas valve is used, and the valve piece is filled with a polytetrafluoroethylene material. The improved gas valve has the following advantages compared with the annular valve: (1) The valve type valve is used, the material is PTFE, the airtightness between the valve piece and the valve seat is good, and the sealing performance is strengthened; 2) The strength of the valve plate is increased, it is not easy to be damaged or broken, and the wearing parts of the valve are reduced, which is convenient for maintenance; (3) The structure has improved flow flow, and the resistance coefficient is smaller than that of the annular valve; (4) Valves of the same structural size can change the size and number of openings to suit different exhaust volumes. The improved gas valve basically overcomes the problem that the annular valve is easily damaged in the oil-free compressor. 4 gas valve design After the structure of the gas valve is selected, the next step is to determine the main characteristic parameters of the valve, such as air flow speed, flow area, valve lift, spring force, structural size of the main parts of the valve, etc., and check the strength of the main parts. Wait. The valve of the well-operated valve should have good movement, opening and closing in time. For this reason, the movement law of the valve piece should be analyzed and calculated during the design of the valve, so that a reasonable valve can be designed. The equation of motion of the valve plate is as follows. Intake valve motion law equation group hDDD valve plate displacement θDDD crank angle M vDDD valve plate motion mass ωDDD crank angular velocity βDDD thrust coefficient a pDDD valve seat flow area ZDDD The number of springs on a gas valve pDDD spring stiffness coefficient H 0DDD spring pre-compression KDDD adiabatic process index VDDD cylinder gas volume V hDDD cylinder stroke volume εDDD relative clearance volume RDDD gas constant T sDDD intake air temperature NDDD cylinder on the same side of the same name valve number αvDDD flow coefficient 6 d iDDD valve hole diameter in the same valve and gas pressure ratio before and after φDDD exhaust valve The T dDDD exhaust temperature is solved by the numerical method for the above equation, and the valve motion curve can be obtained. 5 valve sheet material and manufacturing process The selected valve sheet material is PTFE fiber powder, with a small amount of graphite powder, glass fiber powder, etc., the detailed composition. 511 crushed and sieved The PTFE material used is a fibrous powder, which is easy to agglomerate during storage and transportation. It needs to be centrifugally pulverized before use, sieved with a 20 mesh sieve, and used with the sieve. Filler materials such as graphite are required to have a certain purity and particle size, and the particle size is required to be sieved with a 250 mesh sieve. 512 preform The raw materials were weighed into a mold and scraped with a flat ruler to evenly distribute the raw materials in the mold. For ease of demolding, the release agent can be pre-coated in the mold and then pressed. The pressurization should be carried out slowly, without impact, and it must be maintained for a certain period of time after reaching the specified pressure. 513 sintering Sintering at 327 ° C or higher, should be kept at the sintering temperature for a certain period of time, so that the dispersed individual numerical particles are bonded to each other to form a whole. 514 cooling The cooling process should be relatively slow. In order to make the mechanical properties of the material better, it is generally cooled with the furnace. The above method was used to improve the valve of the 4L - 20/ 8 propane gas compressor of the Beijing Yanshan Petrochemical Company refinery. Before the improvement, the gas valve of the machine is a ring valve, which is often damaged. Sometimes the gas valve should be replaced once in a few days; after the modification, the structure is a mushroom valve, and the gas valve can work normally for more than half a year. 6 Conclusion (1) The annular valve has its problems in frictionless force between the valve plate and the guide block, which limits its application in oil-free compressors. (2) The mushroom valve structure using the PTFE material as the valve plate is more suitable for the oil-free compressor. (3) In the design of the valve, the appropriate structure type is adopted, and the motion law of the valve plate can be analyzed and calculated to design a reliable valve. (4) The manufacturing process of the valve piece has a certain influence on its working life. Bicycle Toptube Bag Jiaxing Love Riding Electronic Technology Co.Ltd. , https://www.loveridings.com