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    Home > Active Ingredient News > Drugs Articles > Analysis on the vibration reason of siphon centrifuge and its elimination measures

    Analysis on the vibration reason of siphon centrifuge and its elimination measures

    • Last Update: 2007-02-03
    • Source: Internet
    • Author: User
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    Li Xun, Feng Licheng, Chen Wenmei, Chu liangyin and Li Bixian summarize the common vibration phenomena and causes in the operation of siphon centrifuge from the empty car operation The process of feed dehydration and discharge are analyzed, and the corresponding solutions are put forward Key words: siphon centrifuge scraper vibration 1 siphon centrifuge principle structure in the early 1970s, West Germany, kranss Maffei, the company launched an epoch-making new type of centrifuge, namely siphon scraper discharge centrifuge, in 1973 achema Chemical Machinery Exhibition on the rise, and soon formed a series of products Due to its large driving force, low moisture content of filter residue, adjustable filtration speed, renewable residual layer, and computer control, high automation, reliable operation, stable operation and strong adaptability, this machine is especially suitable for heavy load production and materials that need to be fully washed, At present, it has been widely used in the separation of polyacrylonitrile, vitamin B, baking soda, sodium perborate, calcium phosphate and other materials The structure diagram of siphon centrifuge is shown in Figure 1, mainly composed of drum, scraper device, siphon device, recoil pipe, feeding pipe and other components As shown in Figure 1, the slurry enters the inner surface of the centrifuge drum through the feeding pipe, the solid particles are intercepted by the filter medium to form the filter cake layer, the liquid phase passes through the filter cake layer and the filter medium under the centrifugal force to enter the outer drum, and enters the siphon chamber through the inclined hole at the bottom of the drum along the fluid channel When the siphon rotates into the liquid pool of the siphon chamber, the filtrate in the siphon chamber will be discharged out of the unit quickly through the siphon because of the pressure difference, and a negative pressure area will be formed between the filter medium and the siphon chamber, making the filtering driving force become centrifugal force and vacuum pumping force The material layer in the drum is washed by the washing water added into the washing pipe The dehydrated and washed materials are scraped off by the rotary scraper, and the materials unloaded by the scraper are discharged out of the machine through the discharge hopper After unloading, the scraper and siphon are in and suspended: position The backwash water is added into the siphon chamber through the backwash pipe, and the backwash water enters into the drum through the inclined hole at the bottom of the drum, so that the residual layer of the filter cake becomes loose again At the same time, a layer of liquid ring is formed on the inner surface of the residual layer of the filter cake, so that the material is evenly distributed and vibration is avoided in a new round of feeding After recoil, enter the next operation cycle In the process of operation of siphon centrifuge, the common fault of Zui is vibration, which is very harmful to the operation In serious cases, it will cause great damage to the machine itself, the environment and the operators In order to make the operation stable and reliable, this paper analyzes the common vibration phenomena and causes in the operation of siphon centrifuge from three aspects of empty car operation, feeding dehydration process and unloading, and puts forward effective solutions 2 Common vibration of siphon centrifuge and elimination measures 2.1 vibration during empty car operation When the machine is operated, it is only when the empty car starts to run at full speed before feeding During the starting process, the vibration and noise of the main engine are not related to the materials, which may be caused by the following reasons The main bearing is defective, worn or improperly installed; the rotating drum is unbalanced, resulting in the eccentricity of the rotating parts; the taper of the drum and the main shaft does not fit well; the installation of various parts of the machine is not well tightened or the lubrication is not good At this time, it is necessary to stop, analyze the above possible causes and take corresponding measures to eliminate the vibration If the main bearing is defective or worn, resulting in excessive clearance, the main bearing can be replaced and installed correctly; if the rotor is eccentric, the dynamic balance shall be carried out again; if the main shaft is not well matched, the conical surface of the matching between the main shaft and the drum shall be scraped again, and the pulley shall be moved by hand, and the drum shall rotate freely without any friction and abnormal noise If the installation is not tight or the lubrication is poor, check the lubrication system and the fastening connections before starting the machine to ensure the normal operation of the empty car 2.2 vibration in the process of feeding and dehydration During the feeding process of the centrifuge, the materials added are uneven or the concentration is too low or too thick, and the feeding speed is not stable, which may cause the vibration of the main engine Therefore, when feeding, try to ensure the relatively stable solid-liquid ratio of the suspension Different materials have different solid-liquid ratios, which can be determined through experiments, In addition, the feeding speed shall be adjusted by the gate valve in front of the feeding valve In addition, the surface mesh may be damaged due to the poor installation of the bottom mesh and the surface mesh, resulting in material leakage The aging of vibration absorbing rubber will also lead to the vibration of the machine During installation, the surface mesh shall be close to the screen mesh to form the end face seal, avoiding the use of pleated filter media If the mesh surface is damaged, it shall be replaced or repaired in time After aging, the vibration absorbing rubber should also be replaced in time In the process of recoil, if the recoil is not sufficient, the machine will vibrate, so the recoil should be sufficient 2.3 vibration during unloading The problem of more Zui during unloading is the vibration of scraper frame, which induces the vibration of main machine and causes unloading vibration for many reasons The main reasons and improvement measures are as follows: 2.3.1 generally, the reason of scraper blade wear is: the scraper support is damaged The scraper is not aligned during installation and is not parallel to the axis line Too much line pressure on the scraper The scraper material is improper, too hard or too soft Due to electrostatic discharge, electrolytic corrosion, burning and other reasons, the blade is corroded Improper lubrication and so on can shorten the life of the scraper, especially in manual operation, the time of each process can not be accurately controlled For example, in the process of producing soda ash, the siphon scraper discharge centrifuge is used for heavy alkali separation If the drying time of the material layer is too long, the filter residue is too hard, especially when the washing liquid pipe is blocked or the water pressure is low, There is a layer of hard crystal salt (sodium chloride, etc.) on the drum When the scraper is unloaded, strong vibration will appear The scraper and bearing are easy to be damaged After the scraper is worn, the contact area with the material layer will increase relatively, resulting in increased resistance, loose blade, serious salt accumulation on the back of the blade, changing the angle of the blade, etc., which will cause unloading vibration, Install, use and maintain the scraper properly In order to solve this problem, first of all, the scraper material should be selected correctly The blade is the * part in the scraper device which is in direct contact with the filter residue It must be smooth, have a sharp and even edge, and the blade material should be uniform, There is no hard or weak point or uneven distribution of packing When selecting the blade material, the requirements of discharging for the scraper, the surrounding temperature, corrosion, the load attached to the blade, the wear resistance of the blade, etc should be taken into account In the past, there were many blades made of steel, but in the process of using, the steel blade scraper wear fast and its service life is short, so it needs to change the blade frequently, The productivity is low With the progress of science and technology, a new type of ceramic scraper has been used in practice It is used to spray ceramic on the blade of steel knife At present, there are two kinds of ceramic raw materials commonly used in the chemical industry: alumina ceramic and zirconia ceramic Rex BTG company is an early manufacturer of alumina ceramic scraper, Green coat company of South Korea is the main manufacturer of zirconia ceramic scraper It has been proved by practice that the ceramic scraper has the following characteristics: A wear resistance, long service life, 5-6 times of the general steel scraper, saving the time for changing the scraper, It reduces the operating strength, B It has good heat resistance and corrosion resistance, C one of its main raw materials, silicon carbide, has the characteristics of large thermal conductivity, small thermal expansion coefficient and good thermal vibration resistance, D It has high manufacturing accuracy, smooth surface, blunt scraper, and can be sharpened, However, to keep the front and back corners of the scraper, cooling liquid should also be used to reduce the grinding temperature and prevent the scraper from deformation, surface burn, annealing and serious wear The scraper should be replaced in time For the scraper that is not straight, it should be straightened and installed, and the levelness can be corrected by using a water level meter, so that the parallelism error between the blade and the center line of the main shaft is not more than 1m M / m Pay attention to adjust the top dead center position of the scraper, so that the distance between the scraper and the filter medium and the wall on both sides of the drum must be kept at 6-10 mm, which can be realized by adjusting the upper limit bolt of the door cover, so as to avoid the screen from being damaged, causing accidents, 2.3.2 abrasion of the scraper shaft sleeve, add lubricating oil from the central hole of the scraper shaft, and then pass through the oil groove on the shaft, It is dispersed in the oil groove of the scraper shaft sleeve to lubricate the shaft sleeve Because the oil hole of the shaft is thin and long, and the rotation angle of the shaft is small (generally about 40), the lubrication effect is poor, and it may be difficult for the scraper shaft to rotate, and the scraper lifting is not flexible, or even unable to rise and fall, especially when the oil resistant rubber at the front gland of the shaft sleeve is damaged, the corrosive liquid is easy to enter the shaft sleeve, In addition, the radial force of the shaft is large, which is easy to damage the shaft sleeve After the shaft sleeve is worn, the fit clearance becomes large, and the scraper shaft is easy to shake After the scraper cuts into the slag layer, it will receive a force cutting into the slag layer, and the radial runout of the shaft will increase When the scraper shaft rotates to the end position of Zui, the blade will not be parallel to the drum surface, The distance may be smaller than the installation requirements (6-10 mm), which is easy to cause vibration and noise during scraping, and even damage the filter screen Some people put forward the way to improve the lubrication of scraper shaft, that is, connect a tee outside the oil pressure gauge, and press the hydraulic oil output from the oil pump into the shaft sleeve after passing through the needle valve When the oil seeps out from the door cover, close the needle valve to stop refueling In addition, it is proved by practice that if the gland is made of stainless steel plate and the oil seal is made of Teflon, the abrasion of scraper shaft sleeve will be improved 2.3.3 uneven distribution of materials: when the materials in the high-level tank are stored for a long time and there is no mixing device, the crystal salt is easy to precipitate, and the solid-liquid ratio will be misadjusted during feeding, so that the materials added into the drum are not evenly distributed, which not only causes serious vibration during feeding and filtering, but also causes serious vibration during scraper unloading The mixing device should be added, Mix the materials in the high-level tank evenly and control the solid-liquid ratio to eliminate the vibration caused by uneven distribution 2.3.4 too fast scraping speed and too fast scraping speed make the filter slag too thick and the cutting force significantly increase, which will cause vibration during scraping The speed of scraper rotation can be adjusted by changing the oil delivery speed The speed regulating valve adopts the form of combination of pressure reducing valve and throttle valve in series The pressure difference before and after the throttle valve is guaranteed not to be affected by the load by the pressure reducing valve, so that the flow through the throttle valve is a constant value If the governor flow is found to be unstable, it can be removed, take out the pressure reducing valve, clean it, check whether the damping hole is blocked, etc., so as to make it work normally At the same time, the aging of the sealing ring in the unloading oil cylinder or the wear of its cylinder block will not guarantee the pressure After the abrasion of the scraper oil cylinder piston, the driving force of the scraper will be smaller, the clearance between the oil pump blades in the oil pressure system will be too large, and the oil pressure will not reach the required pressure, which will cause the scraper to vibrate when working The vibration of the tool holder induced by these factors is sometimes very intense In operation, it needs to be carefully analyzed, checked one by one, and improved in time to ensure the safe operation of the centrifuge This paper analyzes the reason of centrifuge vibration from three aspects
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