Technical analysis of the principle of horizontal siphon scraper discharge centrifuge
2021-08-31 11:04:24
The horizontal siphon scraper discharge centrifuge is a machine for separating two liquids of different density and immiscible liquid from the solid particle suspension by using the rotating drum to drive the centrifugal force generated by the material in the drum for high-speed rotation. It is a patented product of KRAUSSMAFFEI, Germany. After three or four years of development, it has a series of products. At present, Germany, France and Japan are producing and improving the technical parameters, serialization and automation. China currently has a large demand for this model and mainly relies on introduction. Therefore, it is especially important to achieve localization.
1 Siphon principle Horizontal siphon scraper discharge centrifuge adds a siphon chamber and siphon device compared to a conventional scraper centrifuge. During filtration, the filtrate flows through the filter cloth through the side holes on the drum into the siphon chamber, and the filtrate in the siphon chamber is withdrawn by a stationary sputum siphon. The outside of the sputum siphon is connected to a hydraulic mechanism to control the liquid level in the siphon chamber by hydraulically adjusting the position of the sputum siphon. The thickness of the filter cake layer is H', and the pressure difference between the two sides of the filter medium is Δp, and the filtration speed is v=k'ΔpH' (where k' is a proportional constant). That is, the filtration speed v is proportional to the pressure difference Δp on both sides of the filter medium, and inversely proportional to the thickness H' of the filter cake layer. The filter siphon blade centrifuge uses the siphon principle on the other side of the filter medium to increase the pressure difference across the filter medium, thereby increasing the filtration speed v. Therefore, the advantages of the siphon blade centrifuge compared to the conventional filter blade centrifuge are remarkable. The filtration of the suspension is divided into two successive phases: the level of the suspension drops to the surface of the filter cake layer and the filtrate continues to fall in the filter cake layer. The filtrate continuously passes through a filter residue layer having different resistances, that is, a normal filter residue layer and a blade compacted filter residue layer (hard slag layer). The filtration time at different stages shall be calculated separately, taking into account the total resistance of the different filter layers. Under the same conditions, the speed of the siphon scraper centrifuge is faster than that of the ordinary scraper centrifuge, and the speeds of filtration, drying, washing, etc. are also easily adjusted according to different requirements of each operation stage.
It can be seen from Fig. 1 that all the filtrate passing through the medium enters the filtrate chamber, and the filtrate is discharged through the sputum tube to change the position of the fistula tube to control the liquid level in the siphon chamber, that is, to control the Hμ value. The height of the liquid layer above the H0 medium in the figure; the distance from the liquid level of the Hμ siphon chamber to the filter medium. The operation mode of the siphon scraper centrifuge and its advantages are:
(1) The Hμ value is reduced in the feeding stage (at least the filtrate can be filled to the siphon chamber to make Hμ a negative value), and the filtration speed is lowered to form a filter cake having a relatively uniform thickness.
(2) The filtration phase increases the Hμ value and increases the filtration speed to increase the throughput per unit time.
(3) The Hμ value is reduced in the washing stage, the filtration speed is lowered, the washing liquid is slowly passed through the filter cake, the residence time of the washing liquid in the filter residue is prolonged, the consumption of the washing liquid is reduced, a good washing effect is obtained, and the washing efficiency is improved.
(4) In the spin-drying stage, Hμ reaches a large value of zui, and the filtration driving force is large, and a filter cake having a low liquid content is obtained.
(5) The regeneration medium of the filter medium rinses the liquid from the outside to the siphon chamber, and the rinsing liquid flows from the filtrate chamber through the filter cake medium to the inside of the drum to realize reverse washing of the filter medium, so that the filter medium recovers the filtration performance.
As can be seen from the above, the siphon blade discharge centrifuge can adjust the filtration speed by adjusting the position of the siphon suction port without changing the rotation speed of the drum, and changing the drum speed is more difficult than the conventional blade filter centrifuge. The experiment of separating the chalk suspension with a particle size of 20 μm was carried out by a siphon doctor centrifuge. When the separation factor was 500, H0=47 mm, when Hμ=0 (ie, like the ordinary doctor centrifuge, no siphon effect), 3L was separated. The suspension takes 50 s; when Hμ = 38 mm, the separation time is only 12 s. Compared with the ordinary scraper discharge centrifuge, the siphon scraper discharge centrifuge not only has higher productivity and better separation effect, but also has strong adaptability to materials, and can be separated into medium or fine particles (0.01 mm~ A suspension of 5 mm) can also separate a suspension containing short fibers (fiber length less than 4 mm) with a concentration ranging from 10% to 60%. The siphon blade centrifuge is insensitive to fluctuations in suspension concentration or feed rate, and the duration of each step in the operation can be arbitrarily adjusted; the filter cake can also be well washed.
2 Conclusion This new type of scraper discharge centrifuge is stable for both low temperature and high temperature (limited by the vapor pressure of the liquid). It is especially suitable for applications requiring adequate washing and low solids content. It has been used to separate polyacrylonitrile, vitamin B, baking soda, sodium perborate, calcium phosphate and other materials. With the development of modern industry, the siphon scraper centrifuge is steadily advancing on the road of serialization and localization. It saves a lot of foreign exchange for the country and brings certain economic benefits to the enterprise.
1 Siphon principle Horizontal siphon scraper discharge centrifuge adds a siphon chamber and siphon device compared to a conventional scraper centrifuge. During filtration, the filtrate flows through the filter cloth through the side holes on the drum into the siphon chamber, and the filtrate in the siphon chamber is withdrawn by a stationary sputum siphon. The outside of the sputum siphon is connected to a hydraulic mechanism to control the liquid level in the siphon chamber by hydraulically adjusting the position of the sputum siphon. The thickness of the filter cake layer is H', and the pressure difference between the two sides of the filter medium is Δp, and the filtration speed is v=k'ΔpH' (where k' is a proportional constant). That is, the filtration speed v is proportional to the pressure difference Δp on both sides of the filter medium, and inversely proportional to the thickness H' of the filter cake layer. The filter siphon blade centrifuge uses the siphon principle on the other side of the filter medium to increase the pressure difference across the filter medium, thereby increasing the filtration speed v. Therefore, the advantages of the siphon blade centrifuge compared to the conventional filter blade centrifuge are remarkable. The filtration of the suspension is divided into two successive phases: the level of the suspension drops to the surface of the filter cake layer and the filtrate continues to fall in the filter cake layer. The filtrate continuously passes through a filter residue layer having different resistances, that is, a normal filter residue layer and a blade compacted filter residue layer (hard slag layer). The filtration time at different stages shall be calculated separately, taking into account the total resistance of the different filter layers. Under the same conditions, the speed of the siphon scraper centrifuge is faster than that of the ordinary scraper centrifuge, and the speeds of filtration, drying, washing, etc. are also easily adjusted according to different requirements of each operation stage.
It can be seen from Fig. 1 that all the filtrate passing through the medium enters the filtrate chamber, and the filtrate is discharged through the sputum tube to change the position of the fistula tube to control the liquid level in the siphon chamber, that is, to control the Hμ value. The height of the liquid layer above the H0 medium in the figure; the distance from the liquid level of the Hμ siphon chamber to the filter medium. The operation mode of the siphon scraper centrifuge and its advantages are:
(1) The Hμ value is reduced in the feeding stage (at least the filtrate can be filled to the siphon chamber to make Hμ a negative value), and the filtration speed is lowered to form a filter cake having a relatively uniform thickness.
(2) The filtration phase increases the Hμ value and increases the filtration speed to increase the throughput per unit time.
(3) The Hμ value is reduced in the washing stage, the filtration speed is lowered, the washing liquid is slowly passed through the filter cake, the residence time of the washing liquid in the filter residue is prolonged, the consumption of the washing liquid is reduced, a good washing effect is obtained, and the washing efficiency is improved.
(4) In the spin-drying stage, Hμ reaches a large value of zui, and the filtration driving force is large, and a filter cake having a low liquid content is obtained.
(5) The regeneration medium of the filter medium rinses the liquid from the outside to the siphon chamber, and the rinsing liquid flows from the filtrate chamber through the filter cake medium to the inside of the drum to realize reverse washing of the filter medium, so that the filter medium recovers the filtration performance.
As can be seen from the above, the siphon blade discharge centrifuge can adjust the filtration speed by adjusting the position of the siphon suction port without changing the rotation speed of the drum, and changing the drum speed is more difficult than the conventional blade filter centrifuge. The experiment of separating the chalk suspension with a particle size of 20 μm was carried out by a siphon doctor centrifuge. When the separation factor was 500, H0=47 mm, when Hμ=0 (ie, like the ordinary doctor centrifuge, no siphon effect), 3L was separated. The suspension takes 50 s; when Hμ = 38 mm, the separation time is only 12 s. Compared with the ordinary scraper discharge centrifuge, the siphon scraper discharge centrifuge not only has higher productivity and better separation effect, but also has strong adaptability to materials, and can be separated into medium or fine particles (0.01 mm~ A suspension of 5 mm) can also separate a suspension containing short fibers (fiber length less than 4 mm) with a concentration ranging from 10% to 60%. The siphon blade centrifuge is insensitive to fluctuations in suspension concentration or feed rate, and the duration of each step in the operation can be arbitrarily adjusted; the filter cake can also be well washed.
2 Conclusion This new type of scraper discharge centrifuge is stable for both low temperature and high temperature (limited by the vapor pressure of the liquid). It is especially suitable for applications requiring adequate washing and low solids content. It has been used to separate polyacrylonitrile, vitamin B, baking soda, sodium perborate, calcium phosphate and other materials. With the development of modern industry, the siphon scraper centrifuge is steadily advancing on the road of serialization and localization. It saves a lot of foreign exchange for the country and brings certain economic benefits to the enterprise.
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