Original Title: Working Principle and Application of Various Centrifuges (Picture and Text Explanation Worth Collecting) Centrifugation is to use the strong centrifugal force generated by the high-speed rotation of the centrifuge rotor to accelerate the sedimentation rate of particles in the liquid and separate the substances with different sedimentation coefficients and buoyancy densities in the sample. Therefore, it is necessary to use the centrifuge to generate a strong centrifugal force to force these particles to overcome the diffusion and produce sedimentation movement. A centrifuge has a cylinder, called a drum, that rotates at high speed about its own axis, usually driven by an electric motor. After the suspension (or emulsion) is added to the drum, it is rapidly driven to rotate at the same speed as the drum, and the components are separated under the action of centrifugal force and discharged separately. In general, the higher the drum speed, the better the separation. Centrifuge base Expand the full text Centrifuge main body Centrifuge feed pipe Centrifuge buffer plate Sieve Blue Stent Centrifugation is to use the strong centrifugal force generated by the high-speed rotation of the centrifuge rotor to accelerate the sedimentation rate of particles in the liquid and separate the substances with different sedimentation coefficients and buoyancy densities in the sample. Centrifuges are widely used in chemical, petroleum, food, pharmaceutical, mineral processing, coal, water treatment and shipping sectors. What are the classifications of centrifuges? Industrial centrifuges can be divided into filtration centrifuges, sedimentation centrifuges and separators according to their structure and separation requirements. 1. Filter centrifuge The centrifuge for realizing centrifugal filtration is a filtering centrifuge which relies on the action of a filter screen and centrifugal force. Structural features: filter screen, drum. Principle of filter centrifuge: there are many small holes on the wall of the drum, and there is a filter screen (filter cloth) in the wall. The suspension rotates in the drum, and the liquid phase is thrown out of the screen by centrifugal force, while the solid phase particles are intercepted by the screen to form a filter cake, thus realizing the separation of solid and liquid. Applicable range: suspension with high solid content and large solid particles (d > 10 μm). Comparison of Several Kinds of Filter Centrifuge 1. Tripod filter centrifuge: The utility model relates to a manual upper part feeding type centrifuge. Widely used in: chemical, pharmaceutical, food, light industry and other industries. Structure: drum, filter screen, main shaft, bearing, chassis, shell, three pillars, belt drive, motor, etc. Principle of separation during operation Operating principle during unloading Working sequence: starting, feeding, filtering, washing, drying, stopping and unloading. Periodic, intermittent operation. The suspension is gradually added into the drum after startup. Under the action of the centrifugal force field, the liquid is thrown out through the filter cloth (filter screen) and the drum hole, while the solid is trapped in the filter screen to form a filter cake. Advantages: (1) strong adaptability to materials, and can be used for solid-liquid separation, finished product liquid removal, and filter cake washing. (2) that structure is simple, and the cost of manufacture, installation, maintenance and use is low. (3) Stable operation, easy to achieve sealing and explosion-proof. Disadvantages: unloading to stop, low efficiency. Other types of tripod: ① Three-foot automatic scraper lower discharge type. ② Tripod lifting unloading type. ③ Three-leg air discharge type. ④ Tripod piston upper discharge type. The tripod centrifuge is the most numerous and widely used filtration centrifuge. When a centrifugal filter is used to filter a suspension containing very small particles, a filter cloth is usually used as the filter medium, and the filter cake is required not to move relative to the filter cloth. Obviously, the simplest type of centrifuge that meets these requirements is the tripod centrifuge. It has a cylindrical drum with a vertical shaft, a solid bottom and a semi-closed top. The surrounding edge of the top is called the drum edge. The drum is supported on a three-legged frame, so it is called a three-legged centrifuge. Under normal circumstances, the drum cover is drilled with many small holes, and the inside is covered with one or more layers of large-hole metal filter screen, which is used as the support of the filter cloth installed in the drum. Before or after start-up, the white top of the suspension is introduced into the drum so that the filtrate flows out through the mantle while the solid particles are trapped on the filter cloth. In general, the filter residue is removed manually after shutdown or unloaded by replacing the filter bag. One of the more advanced tripod centrifuges is used by reducing the speed of the bowl to a few revolutions per minute and then pushing a plow blade into the filter residue to remove the solid material. The plough knife turns the solid to the axis of the rotary drum, so that the filter residue falls out of the opening at the bottom of the rotary drum. With the help of a timer, all operations can be carried out automatically.
2. Top suspension centrifuge Vertical filter centrifuge with main shaft fulcrum higher than the center of gravity of rotating parts. Widely used in: chemical, pharmaceutical, light industry, food and so on. Uch as sugar, salt, glucose and the like. Structure: the rotary drum is fixed at the lower end of the slender shaft, the upper end of the shaft is provided with a bearing suspension mechanism connected with a motor, and the shaft drives the rotary drum to rotate. Working cycle: feeding, rotary separation, washing, dewatering, unloading, washing filter screen, etc. Working features: low speed upper feeding, full speed separation, washing, dehydration, low speed lower unloading. Rotational speed is continuous but varies periodically. The invention has the advantages that: (1) the invention has strong adaptability to materials and is suitable for suspensions with different concentrations. (2) that machine doe not stop for feeding and discharge, the machine runs continuously, and the relative efficiency is high. ③ The structure is relatively simple. Disadvantages: ① Slow down during feeding and unloading, and the operation is periodic. ② The main shaft is long, which is easy to produce flexural deformation. Other types of structures: ① Upper suspension scraper discharge type. ② Upper suspension automatic unloading type. 3. Horizontal scraper discharge centrifuge Working cycle: feeding, filtering, washing, separating and discharging at high speed. Working features: high-speed continuous operation, intermittent feeding and unloading. It can handle the suspension of coarse, medium and fine particles. Structure: rotary drum, filter screen, feeding pipe, scraper mechanism, discharge chute, shell, spindle, machine body and motor. Widely used in: chemical, pharmaceutical, light industry, food and other industries. Uch as salt, ammonium sulfate, ammonium bicarbonate, polyvinyl chloride and the like. How it works Application Advantages: ① Strong adaptability to materials. It can handle the suspension of coarse, medium and fine particles. (2) that proces time of filtering, was, separating and discharging can be adjusted at will. ③ Continuous operation, uniform speed and high efficiency. Disadvantages: the scraper wears quickly and is prone to impact. The scraper blade is most easily damaged by wear, impact and corrosion when it works, so it should be made of wear-resistant, corrosion-resistant and high-strength materials. Scraper structure: ① Upper suspension scraper. ② Rotary scraper. 4. Horizontal piston discharge centrifuge Working cycle: continuous feeding, separation, washing and drying at full speed, and continuous unloading by piston. Working features: continuous operation at uniform speed, automatic continuous feeding, hydraulic pulsation piston unloading, unattended and automatic operation. Structure: Rotary drum, screen mesh, pushing plate, cloth hopper, hollow shaft, push rod, composite cylinder, casing, base, hydraulic system, etc. Widely used in: chemical, fertilizer, pharmaceutical, sugar and other industries. Advantages: (1) high efficiency, high yield and stable operation. ② Automatic loading and unloading to realize unattended duty. ③ Strong adaptability to materials, suitable for suspension of coarse and medium particles. Disadvantages: ① Not suitable for fine particle suspension. ② It is sensitive to concentration fluctuation and easy to cause material leakage. ③ The structure is relatively complex. The pusher plate moves back and forth, and the number of times of reciprocation: 20 ~ 30 times/min; the stroke is 1/10 of the drum length. Classification of this centrifuge: ① Single-stage piston pusher centrifuge. (2) Multistage piston pusher centrifuge-each stage has a short drum, easy to push the residue, thin filter residue layer and long filter residue retention time, which is conducive to dehydration and washing. 5. Centrifugal inertia force discharge centrifuge Also known as: cone basket centrifuge. Type of the centrifuge: vertical cone basket type; horizontal cone basket type. Working cycle: continuous feeding, separation, washing, drying and discharging at full speed. Working features: working at full speed, automatic and continuous feeding and discharging, without special discharging device. Structure: conical drum, filter screen, feed pipe, distributor, spindle, casing, hemp extraction centrifuge ,nutsche filter dryer, vibration isolator, motor, etc. Advantages: (1) simple structure, small size and low cost. ② High efficiency and low power consumption. ③ It can load and unload automatically, and no one is on duty. Disadvantages: ① Sensitive to material properties and concentration changes, poor adaptability. ② The retention time of materials is not easy to control, and it is easy to produce liquid leakage. Filter residue movement principle: (ignoring the gravity effect of particles) Widely used in chemical industry, small fertilizer, pharmacy, food, etc. II. Decanter centrifuge Principle: There is no hole or filter screen on the drum. The suspension rotates with the drum at a high speed. Due to the different specific gravity of the solid and liquid phases, different centrifugal inertia forces are generated. The solid particles with large centrifugal force are deposited on the inner wall of the drum, while the liquid phase is deposited on the inner layer, and then discharged from different outlets to achieve the purpose of separation.
Generally, the rotational speed of the decanter centrifuge is high: n = 7000-8000 rpm Applicable range: less solid content and smaller solid particles (d < 10 μm). Common model: spiral discharge type. Divided into: (1) Screw discharge sedimentation centrifuge (horizontal and vertical) (2) Scraper discharge horizontal sedimentation centrifuge (3) Three-column sedimentation centrifuge 1. Screw discharge type sedimentation centrifuge It is widely used in chemical industry, petroleum, metallurgy, pharmacy, light industry, food, sewage treatment, etc. It is used to treat suspension with particle size d < 10 μm. Working features: continuous feeding, separation, unloading, full speed operation, high speed n = 7000 ~ 8000 rpm. Working principle: the suspension enters from the center. Under the action of centrifugal force, an annular liquid pool is formed in the drum. The heavy phase particles settle to the inner surface of the drum to form sediment, which is pushed to the small end of the drum by the spiral blade to be discharged. The large end cover of the rotary drum is provided with overflow holes which are arranged in a circular shape, and the clear liquid is discharged from the overflow holes. The main operating parameters of the screw discharge sedimentation centrifuge are: the number of revolutions of the drum, the speed difference between the drum and the conveying screw, the position of the overflow port and the feeding speed; the main structural parameters are: the inner diameter D of the big end of the drum, the length of the drum? L, the length-diameter ratio L/D of the rotary drum, the semi-cone angle alpha of the rotary drum, and the number of screw heads and the screw pitch of the conveying screw. The main advantages of the spiral discharge sedimentation centrifuge are as follows: automatic continuous operation, no need of filter cloth, long-term continuous operation, easy maintenance, wide application range, solid dewatering, liquid clarification, solid particle classification according to particle size, and liquid-liquid-solid separation; It has good adaptability to materials, the range of solid particle size that can be separated is 0.005 mm-2 mm, and the range of volume concentration of suspension is 2% -40%. The concentration fluctuation has little influence on the separation effect; the structure is compact, the structure is easy to be sealed, and the sealed machine can be operated under a certain positive pressure; the single machine has large production capacity (the large machine can reach 190m3/H), the operation cost is low, and the occupied area is small. The disadvantages of the spiral discharge sedimentation centrifuge are as follows: the liquid content of the sediment is generally high; although the sediment can be washed, the washing effect is not good; the structure is complex and the machine cost is high. 2. Settling-filter centrifuge Drum: divided into: sedimentation section and filtration section 1. Settling section : Forms are cylindrical and conical; full conical. Function: The suspension enters the sedimentation section for sedimentation and separation, and the clear liquid overflows from the overflow hole at the big end; the sediment is conveyed to the filtration section by the screw conveyor for filtration and dehydration. 2. Filter section : Cylindrical in form, with screen and mesh. Function: The sediment is filtered by the screen in this section, the liquid is separated, and the filter residue is discharged from the large hole at the left end. If the filter residue is required to be washed or dried, the central hole is filled with washing liquid or steam, and the filter residue is washed in the filtering section. Refreshing the screen: introduce compressed air or clean water from the blowback pipe to blow back the screen to make it fresh. 3. Spiral-disc centrifuge Mechanism: horizontal spiral discharge centrifuge and butterfly separator. Function: The spiral discharge centrifuge separates the solid from the liquid; the butterfly separator further processes the liquid to obtain liquid products with high clarity. Drum: It is composed of main separation chamber and auxiliary separation chamber. Main separation chamber: It is a horizontal screw centrifuge, mainly for solid-liquid separation. Most of the solid particles are separated and discharged by the screw conveyor. Auxiliary separation chamber: It is a butterfly separator, which further separates the liquid and separates out finer particles. How it works: The suspension enters the spiral centrifuge section from the central pipe, the solid particles are separated from the liquid by the centrifugal force at high speed, and the sediment is discharged from the small end discharge hole by the conveyor. The liquid enters the butterfly separator from the overflow hole at the big end of the centrifuge, and is subjected to solid-liquid separation again, fine particles are discharged from the peripheral holes, and high-clarity liquid is discharged from the middle overflow hole (9). 3. Separator Working principle: according to the density difference of liquid-liquid two phases, under the high-speed centrifugal force field, the liquid-liquid is layered, the heavy phase is in the outer layer, the light phase is in the inner layer, and then they are discharged respectively to achieve the purpose of separation.
Scope of application: emulsion separation, emulsion containing trace solid particles (d < 5 μm) Common models: tube separator, chamber separator, disc separator. Uses: oil, paint, pharmaceutical, chemical and so on. Such as: oil-water separation, protein, penicillin, essential oil separation. 1. Dish separator Separator is a type of sedimentation centrifugal separation, which is used to separate materials that are difficult to separate. Disc separator is the most widely used decanter centrifuge. Two operations of separation and clarification can be completed. Dish centrifuge is a vertical centrifuge, the drum is installed on the upper end of the vertical shaft, driven by the motor through the transmission device to rotate at high speed. A group of disc-shaped parts, discs, are nested together in the rotary drum, and a small gap is left between the discs. The suspension (or emulsion) is fed into the drum through a feed tube located in the center of the drum. When the suspension (or emulsion) flows through the gap between the discs, the solid particles (or droplets) settle onto the discs under centrifugal force to form a sediment (or liquid layer). The sediment slides along the surface of the disc and separates from the disc and accumulates in the largest part of the inner diameter of the rotary drum, and the separated liquid is discharged out of the rotary drum from the liquid outlet. Solids accumulated in the drum shall be removed manually by disassembling the drum after the separator is stopped, or discharged from the drum through the slag discharge mechanism without stopping. The main operating parameters of the disc separator are: the number of revolutions of the drum, the speed of light liquid, the position of the interface between light liquid and heavy liquid, feeding speed, etc.; the main structural parameters of the stack separator are: the inner diameter of the drum, the equivalent settling area, the size and total number of discs, slag discharge mode and slag discharge mechanism. Disc centrifuges are widely used in chemical, pharmaceutical, light industry, food, biological engineering and transportation sectors because of their compact structure, small footprint and large production capacity, which are suitable for liquid-solid and liquid-liquid separation. The disadvantage of butterfly separator is that the structure is complex and the speed is high, so the operation and maintenance requirements are relatively high, and the cleaning is more troublesome. Chamber separator Chamber separator is a widely used centrifugal sedimentation equipment, which is used to separate suspension with solid content below 2%. Its structure is basically the same as that of stack separator except for the drum (such as transmission mechanism, base, speed measuring device, brake, etc.). In the drum of a chamber separator, a group of concentric separation cylinders divide the internal space of the drum into a plurality of chambers (i.e. annular spaces) connected in series with each other, and the internal space of the drum is generally separated according to the principle that the radial spacing of each chamber is equal or the cross-sectional area of each chamber is equal. The feed pipe for the suspension to be clarified is introduced into the center of the drum and then flows outward from the center through the chambers one by one, the flow rate of the liquid in each chamber being gradually reduced (when the radial spacing of each chamber is equal) or kept constant (when the cross-sectional area of each chamber is equal). As the radius increases from the center to the outside, the separation factor of each chamber becomes larger and larger, so the largest solid particles are deposited on the inner wall of the first chamber located in the center, and the finer solid particles are deposited in the outer chambers. The clarified liquid is discharged from the drum by a centripetal pump, and the discharge pressure can reach 0.28 MPa. Due to the concentric separation cylinder installed in the drum of the chamber separator, the settling distance of solid particles is shortened and the settling area is enlarged. Compared with the stacking separator, the structure of the stacking separator is simpler, the parts in the rotary drum are fewer, and the space for accommodating the sediment in the rotary drum is larger, so that the stacking separator can be used for separating the suspension with slightly higher solid content, and is more convenient for removing the sediment and cleaning the rotary drum than the disc separator. Tubular separator Features: Speed up to 15000 R/min (high-speed separator). Separation factor Fr = 13205. The emulsion with the density of two phases greater than 10 can be separated, and the suspension with the solid phase particle d = 0.01-1.0 μm or the solid phase concentration less than 1% can also be separated. Structure: Tubular drum with inner diameter of 105mm, drum length of 730mm, flexible main shaft, upper and lower bearing chambers, casing, base, brake device, etc. Working principle: The emulsion enters the drum from the bottom, and the two liquids are separated under the action of high-speed centrifugal force. The heavy phase liquid is in the outer layer and the light phase liquid is in the inner layer. The heavy phase liquid is discharged from the upper nozzle of the rotary drum, and the light phase liquid is discharged from the center of the separation head to the flow channel.
The tubular separator is applicable to the clarification of suspension with solid content less than 1%, solid particles less than 5 um and small density difference between solid and liquid; it is also applicable to the separation of emulsion with density difference between light liquid and heavy liquid less than high dispersibility. The tubular separator is simple in structure, small in size, stable in operation, and high in separation factor, and can separate materials that are difficult to separate, so it is widely used in chemical, pharmaceutical, biological products production, paint making, vegetable oil refining, mineral oil processing and other industrial sectors. Main uses: separation of viscous suspensions with low solid content, such as the clarification of varnishes, fruit juices, bacterial cultures, etc.; classification of solid particles in suspensions according to their size, such as the classification of enamel raw materials by tubular separators to remove impurities; separation of difficult emulsions, such as water from vegetable oils,50l rotovap, fish and animal fats, and mineral oils; Used for the separation and particle size distribution of highly dispersed and colloidal systems. The main disadvantages of the tubular separator are intermittent operation and small drum volume. In order to avoid frequent shutdown to remove sediment, the solid content of the material separated by the tubular separator should not exceed 1%. Source: Edited by chemists club Recommend to return to Sohu to see more Responsible Editor:. toptiontech.com
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