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Mechanical seal structure with rotating shaft tower and installation W Cai Xiaojun (Department of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing-style, installation requirements and problems in use to solve common tower shaft seal problems 133: A with rotating shaft tower The shaft seal problem is a difficult problem that often plagues us when designing or equipment modification. This is due to the technical structure of the tower equipment itself, which makes it difficult to solve such problems. The shaft seal of the tower is generally installed at the top of the tower. Both are above 20m, which requires that the shaft seal must be simple in structure, easy to disassemble and install. Secondly, the ratio of the major axis of the tower is very different, often forming a super-slim shaft, which has poor rigidity and large yaw. Therefore, when the shaft end seal is required, the error between the center line of the shaft end seal and the coaxiality of the tower main shaft should be minimized. The process condition of the tower determines that the operation period of the tower must be more than one year, and the middle is not allowed. There is the possibility of replacing or repairing the shaft seal, so the shaft end seal design must be able to maintain its long-term operation without leakage. Therefore, we must try our best when designing the shaft seal of the tower. The working characteristics of the tower equipment not only require reasonable and feasible sealing structure, but also ensure the safety and reliability in operation. 1 Structure and characteristics There are two types of shaft seals in general: packing seal and mechanical seal due to vibration and oscillation of the tower main shaft Only the packing seal can not achieve a good sealing effect, and the packing seal is used for the shaft seal of the tower. The maintenance cost is very high, generally about 20 times higher than the mechanical seal, so the mechanical seal is better than the packing seal, which can satisfy the Reliable and safe technical requirements In the mechanical seal, there are two types of sealing structures: single-end and double-end. Compared with the two sealing structures, the double-face sealing has the following advantages: 1 It can satisfactorily seal the fluid under gas or vacuum conditions. 2 Sealing the safe handling capacity of the suspension solution is higher than that of the single-end seal. 3 Its structure has the safety feature of preventing the toxic fluid from escaping to the outside atmosphere. 4 It is the only design structure that can handle very high pressure difference, and its sealing life is longer. The double-end seal can meet the shaft seal requirements of the tower more than the single-end seal. The specific structure of the tower is determined according to the process and structure of the tower. The turntable tower is the main equipment of a certain device. The original design uses hydraulic internal drive. The optimum quenching rate is affected by the turbulence caused by hydraulic drive. After the modification, the external motor is used for driving. When the modified turntable tower load reaches 42~44m3/m2, Improve the yield of refined oil by 65% ​​~ 80%, to meet the needs of process production. In the process of changing from internal power drive to external motor drive, how to solve the shaft seal of the tower becomes the main problem of the turntable tower process conditions: Operating pressure 0. 6MPa, operating temperature 150 ° C, spindle speed 0. 5r / s, medium is 10% furfural solvent and minus two, three, four-wire mixture, installation position at the top of the tower (27m high) spindle diameter 3 80mm, length 15m, diameter to length ratio is 1:190, is a super-slim shaft, poor rigidity, large yaw property, considering that the material in the tower contains 10% furfural solvent, and the furfural solvent is strongly oxidized by oxygen in the air. The oil becomes viscous, and the material in the corrosive tower cannot leak out, and the air is not allowed to enter the tower. Therefore, the double-end multi-spring and non-balanced seal form are used as the shaft seal of the tower. See that the seal is installed at the tower height of 27m, so the structure is easy to assemble and disassemble. The double-face seal can form a single unitary structure. The sealing chamber is equipped with two sets of friction bodies, together with the bushing and the spring, forming a whole body with a diameter of 3260mm and a height of 256mm. The total mass is about 20kg, one person can 扛To the top of the tower, it is convenient to repair and install. According to the large yaw axis and poor rigidity of the slender shaft, the multi-spring structure is adopted (the spring diameter is 39 mm, the spring steel diameter is 01.3 mm, the circumference is evenly distributed, and one side is 12, There are 24 on both sides, the pressure is uniform, and the follow-up of the seal is good. The spindle speed is 0.5r/s, which is relatively low. The specific pressure of the spring is wider than 13Pa, so that even if the main shaft swings at 0.5mm, the sealing performance can be maintained. In addition, in order to keep the surface of the frictional body forever in the case of the main shaft swinging, the moving ring surface is selected to be 3 95.4<9. The static ring friction surface 399<9 (units are mm), the required sealing performance is achieved.
1 welding rod, hardness Rc49~53 (hardness of finished product) static ring is graphite impregnated furan resin, compressive pressure 160MPa, Shore hardness HS87. Sealing ring is 4FV type, spring material is 65Mn, sealing surface contact width double end sealing structure is usually equipped There is a pressurized spray supply system, also known as a sealant system, for pumping liquid from the outside. This auxiliary liquid must meet two basic requirements. First, it must have good lubricity, and secondly it must be chemically compatible with the material.
The system must also meet the following requirements: 1 In order to make the sealing system of the double-face seal structure work well, it is necessary to maintain a positive pressure in the sealed chamber to provide suitable lubrication to the sealing contact surface, and the positive pressure can also prevent foreign particles from entering the seal. The chamber is generally higher than the operating pressure in the tower. The heat generated by the double-faced sealing structure of 2MPa2 can also be dissipated by the blocking liquid. The double-face seal sealing liquid selection 3 (mechanical oil, the oil pressure is maintained at 1 MPa (the tower operating pressure is 0. The operating stress in the tower is out, the material in the tower does not leak out. Because the air pressure is higher than the air pressure, the atmosphere does not enter the sealed chamber. Inside, and the seals are all immersed in 3 (1 mechanical oil, the medium is in good condition, the friction resistance is small, and the sealing life is long. If the single-end seal is used, the sealing liquid can only use static pressure, because the pressure fluctuation inside the tower is large, the seal The surface is easy to be punched out and causes the sealing method of the double-face seal sealing liquid to seal the failure. After careful consideration and calculation, the sealed cavity is installed at the top of the tower with a height of 27m, and a sealing liquid line is installed, which not only has a large workload. And it is not economical. Considering that the rotation speed of the turntable tower is 0.5r/s, the heat of the friction and the heat of the stirring are relatively small, so the fixed pneumatic injection method is used instead of the sealing liquid pipeline, see 30dm3, and the internal load is 4/5. The upper space of the tank is filled with gas at a pressure of 1 MPa. The tank is equipped with 3 copper pipe joints and an on-off valve. When the pressure in the seal chamber drops, the oil in the tank is replenished. When the oil in the tank is reduced, the tank cover can be refueled. Hole replenishment oil volume tank pressure drop The small gas cylinder can be used for charging. The small gas cylinder is made of 3762mm stainless steel tube. The two ends are welded with the head to make the small gas cylinder filled with nitrogen. The pressure is 5MPa. The pressure is adjusted to 1MPa by the pressure reducing valve and then filled into the tank to keep the oil. The tank pressure general sealing system often needs to be cooled when injecting fluid, so the system needs to be equipped with a heat exchanger. The tower sealing chamber is installed at the top of the tower with a height of 27m, and the air is naturally cooled. In addition, the spindle speed is only 0. The contact surface width is only 4.5m, the average line speed is only 0. The heat of the heat and the heat of stirring are very low. The normal temperature of the tower is touse.gmsreserved.rtp://vvww.cnki.nei
A captive bolt pistol (also variously known as a cattle gun, stunbolt gun, bolt gun, or stunner) is a device used for stunning animals prior to slaughter.
The principle behind captive bolt stunning is a forceful strike on the forehead using a bolt to induce unconsciousness. The bolt may or may not destroy part of the brain.
The bolt consists of a heavy rod made of non-rusting alloys, such as stainless steel. It is held in position inside the barrel of the stunner by means of rubber washers. The bolt is usually not visible in a stunner in good condition. The bolt is actuated by a trigger pull and is propelled forward by compressed air or by the discharge of a blank round ignited by a firing pin. After striking a shallow but forceful blow on the forehead of the animal, spring tension causes the bolt to recoil back into the barrel.
The captive bolt pistols are of three types: penetrating, non-penetrating, and free bolt. The use of penetrating captive bolts has, largely, been discontinued in commercial situations in order to minimize the risk of transmission of disease.
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