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Yuan Lei told you | the application of fillers in water treatment. How many types of fillers are there?

Release time:

2024-01-29 09:35

 

Yuan Lei told you | the application of fillers in water treatment. How many types of fillers are there?

 

Filler refers to the material that is filled in other objects. In chemical engineering, packing refers to the inert solid materials installed in the filling tower, such as Pall ring and Raschigo ring, etc., its role is to increase the gas-liquid contact surface, so that they are strongly mixed with each other. In chemical products, fillers, also known as fillers, are solid materials used to improve processing performance, mechanical properties of products and (or) reduce costs. In the field of sewage treatment, it is mainly used in the contact oxidation process, and microorganisms will accumulate on the surface of the filler to increase the surface contact with the sewage and degrade the sewage.

 

Fillers are also known as fillers, extenders. Some fillers are also extender pigments. The filler of micro-button has good hiding power and is often used in the coating industry.

Fillers can be used in a variety of polyurethane products, such as polyurethane coatings, sealants: polyurethane slurry, special elastomers I polyurethane foam. Melamine plant fiber polymerization, soap ginseng polyol, etc., organic fillers can be used for polyurethane foam plastics; Calcium carbonate kaolin (clay, porcelain clay), molecular sieve powder talc, wollastonite, tritech titanium dioxide, barite powder (barium sulfate) 'and other fine inorganic powders can be used as fillers for polyurethane sealant, polyurethane flexible foam polyurethane elastomer, adhesive, polyurethane coating, etc.
General refers to materials that are filled in other objects. In chemical engineering, packing refers to the inert solid materials installed in the filling tower, such as Pall ring and Raschigo ring, etc., its role is to increase the gas-liquid contact surface, so that they are strongly mixed with each other. In chemical products, fillers, also known as fillers, are used to improve the use of fillers.Solid materials that have industrial properties, mechanical properties of products and (or) reduce costs. Which can significantly improve the strength of the product of the filler, such as long fibers and whiskers often specifically called reinforcing materials, carbon black called reinforcing filler. Pharmaceutical tablets, cosmetics and detergents often add solid materials and calcium carbonate as fillers, but its purpose is to adjust the dose and concentration rather than improve performance, so it should be called diluent. Plastic plasticizers, rubber oil and spinning oil, etc., although can improve performance, can also affect the cost, but the habit of these liquid materials as processing aids.
In the polymer chemical industry, filler (filler) is the largest amount of additives, almost all plastics (including thermoplastic and thermosetting plastics), natural rubber and coatings use a large number of fillers. For example, adding wood powder, clay or calcium carbonate when making plastics can not only improve the mechanical properties of products, increase hardness, but also reduce costs. Graphite, magnetic powder or mica as filler can improve the conductivity, magnetic permeability and heat resistance of plastics. Adding carbon black or silica (white carbon black) to rubber can significantly improve the physical properties of products. Titanium dioxide (titanium dioxide) can be added to the spinning solution to shade and dye. White or colored fillers (such as titanium dioxide, talc, calcium carbonate, barium sulfate, etc.) are often added in the coatings industry to improve the optical, physical and chemical properties of coatings. Fillers (fillers) for such purposes are called extender pigments or pigments.

 

Packing performance

Mainly depends on: ① has a larger specific surface area (m2/m3 filler layer);② liquid in the filler surface has a good uniform distribution performance; ③ air flow can be evenly distributed in the filler layer; ④ seasoning has a larger porosity (m3/m3 filler layer). In addition, the choice of filler should also consider its mechanical strength, source, manufacture and price and other factors.

 

role of packing
The filler increases the viscosity of the material, especially the fiber filler increases the viscosity significantly. The filler before addition should be dehydrated to avoid consuming part of the isocyanate. It must be noted that the generation of carbon dioxide will cause the resin to foam and affect the physical properties of the polyurethane resin.
In order to speed up the wetting speed of the filler and reduce the viscosity of the system at the same time} l_. Or in the polyurethane resin to add more filler, sometimes in advance in the resin to add wet, wet dispersant.
In-mold paint is an additive with three functions of coating, color paste and release agent. It is evenly sprayed in the mold, after the paint film is dried, you can mold polyurethane soles, self-skinning foam, polyurethane flexible foam. After the hard foam product is demoulded, the color paint is attached to the molded peripheral product.

 

The mechanism of action of the filler: filler as an additive, mainly through its occupied volume play a role, due to the presence of filler, the molecular chain of the matrix material can no longer occupy all the original space, so that the connected chain segments are fixed to some extent, and may cause the orientation of the matrix polymer. Due to the dimensional stability of the filler, in the filled polymer, the molecular chain movement in the polymer interface region is restricted, and the glass transition temperature is increased, the thermal deformation temperature is increased, the shrinkage rate is reduced, and the elastic modulus, hardness, stiffness, and impact strength are increased.
the role of filler:
① Reduce the shrinkage rate of molded parts, improve the dimensional stability, surface finish, smoothness and flatness or matte of the products;
② effective regulator of resin viscosity;
③It can meet different performance requirements, improve wear resistance, improve electrical conductivity and thermal conductivity, etc. Most fillers can improve the impact strength and compressive strength of the material, but can not improve the tensile strength;
④ can improve the coloring effect of pigment;
⑤ Some fillers have excellent light stability and chemical resistance;
⑥ has the function of increasing capacity, which can reduce costs and improve the competitiveness of products in the market.

 

The purpose of filler in epoxy floor paint

Fillers in epoxy floor paint, also known as fillers, generally refers to the addition to the epoxy resin liquid, as a component of epoxy floor paint, to change the performance of epoxy resin glue and reduce the cost of the material.
The purpose of using filler in epoxy floor paint has the following aspects:
1 reduce costs, inhibit reaction heat, brilliant color.
2 extend the pot life of the resin mixture.
3 Reduces the shrinkage of the cured resin.
4 Improve the heat resistance of the cured resin.
5 Reduce the thermal expansion coefficient of the resin cured product, reduce the water absorption of the resin cured product, and improve the aging resistance and chemical resistance of the cured product.
6 improve the compressive strength of the cured resin, but the tensile strength and impact toughness will be reduced.
7 to improve the arc resistance of resin curing and improve other electrical properties.
8 Improve the abrasion resistance of the cured resin.

 

Filler selection criteria
For a particular application, the optimal standard of filler filler is based on the desired properties of the composite material, but the following basic principles must be considered.
1. The filler must maintain its original structure during processing, and maintain inertness, insolubility, thermal stability, non-volatility, no catalytic activity and low adsorption.
2, the filler must be compatible with the substrate, non-corrosive.
3. Easy to handle, high bulk density, low moisture content, low dust, non-toxic.
4, must be easy to get, sufficient supply, moderate price, stable quality.

 

Type of filler
There are many types of fillers, and metal powders such as aluminum powder, zinc powder, copper powder, and silver powder can be used as conductive fillers. Cement, fly ash, etc. can also be used as fillers. Plant powders such as wood flour and starch can also be used as fillers. Calcium fluoride can be used in a small amount of polyurethane adhesive and sealant system; both the role of carbon dioxide absorbent.
In general, fine powder filler or modified fine filler, as well as fibrous, flake filler, a small amount of use can improve its overall performance,. For example, it has a certain reinforcing effect on elastic polymers (such as rubber, polyurethane elastomer_), increasing modulus, strength, and so on,. Wear resistance, heat resistance, improve its dimensional stability, hard products can also be appropriate to improve the strength, aging resistance. However, if the amount used is too large, the physical properties will be reduced, and the operation is difficult when the amount of filler is large. There are the following types of fillers: According to the different filling methods, it can be divided into bulk fillers and structured fillers.

 

Bulk filler
Bulk packing is a certain geometry and size of the particles, generally in a random manner stacked in the tower, also known as random pile packing or granular packing. Bulk packing can be divided into ring packing, saddle packing, ring saddle packing and spherical packing according to different structural characteristics. Several typical bulk fillers are introduced:
Rassey ring Bauer ring step ring arc saddle filler moment saddle filler metal ring moment saddle filler spherical filler

 

Rassey Ring
(1) Raschie ring packing was invented by Raschie (F. Rashching) in 1914 and is a ring with an outer diameter and a height equal to that of the ring. The gas-liquid distribution of Raschier ring packing is poor, the mass transfer efficiency is low, the resistance is large, the flux is small, and it has been rarely used in industry.

 

Ball Ring
(2) Pall ring packing is an improvement of Raschid ring. Two rows of long square windows are opened on the side wall of Raschid ring. One side of the cut ring wall is still connected with the wall surface, and the other side is bent into the ring to form inwardly extending tongue leaves. The sides of the tongue leaves are matched in the center of the ring. Due to the opening of the ring wall, the utilization rate of the inner space and the inner surface of the ring is greatly improved, the air flow resistance is small, and the liquid distribution is uniform. Compared with the Raschie ring, the gas flux of the Pall ring can be increased by more than 50%, and the mass transfer efficiency can be increased by about 30%. Ball ring is a kind of packing with wide application [1].
Step ring
(3) The step ring packing is an improvement of the Pall ring. Compared with the Pall ring, the height of the step ring is reduced by half and a tapered flange is added at one end. Due to the reduction of the aspect ratio, the average path of the gas around the outer wall of the packing is greatly shortened, reducing the resistance of the gas through the packing layer. The tapered flanging not only increases the mechanical strength of the filler, but also changes the line contact between the fillers into point contact, which not only increases the gap between the fillers, but also becomes the collection and dispersion point of the liquid flowing along the surface of the filler, which can promote the surface renewal of the liquid film and improve the mass transfer efficiency. The comprehensive performance of the stepped ring is better than that of the Pall ring, and it is the most excellent one among the ring packing used.

 

arc saddle filler

(4) arc saddle filler is a kind of saddle filler, its shape like a saddle, generally made of porcelain materials. The characteristic of the arc saddle filler is that the surface is all open, regardless of inside and outside, the liquid flows evenly on both sides of the surface, the surface utilization rate is high, the flow channel is arc-shaped, and the flow resistance is small. The disadvantage is prone to nested, resulting in a part of the filler surface is overlapped, so that the mass transfer efficiency is reduced. The strength of the arc saddle filler is poor, the capacity is broken, and it is not used much in industrial production.

 

Moment saddle filler
(5) The moment saddle filler changes the arc surface at both ends of the arc saddle filler into a rectangular surface, and the two sides are not the same size, which becomes the moment saddle filler. The moment saddle filler will not be nested when stacked, and the liquid distribution is more uniform. The moment saddle filler is generally made of porcelain material, and its performance is better than that of Raschid. The vast majority of domestic applications of porcelain raschiga ring occasions, have been replaced by porcelain saddle filler moment.

 

Metal ring moment saddle packing
(6) metal ring moment saddle packing ring moment saddle packing (known as Intalox abroad) is a new type of packing designed to take into account the characteristics of ring and saddle structure. The packing is generally made of metal, so it is also called metal ring moment saddle packing. Ring moment saddle packing combines the advantages of both ring packing and saddle packing, and its comprehensive performance is better than Pall ring and stepped ring, which is widely used in bulk packing.

 

spherical packing
(7) Spherical filler is generally made of plastic injection molding, and its structure has a variety. Spherical packing is characterized by the ball is hollow, can allow gas, liquid through its interior. Due to the symmetry of the spherical structure, the packing density is uniform, and it is not easy to produce holes and bridges, so the gas-liquid dispersion performance is good. Spherical packing is generally only suitable for some specific occasions, less engineering applications.

 

In addition to the above-mentioned typical bulk fillers, new types of fillers with unique configurations have been developed, such as conjugate ring fillers, haier ring fillers, and nat ring fillers. The characteristic data of bulk fillers commonly used in industry can be found in relevant manuals.

 

structured packing
Structured packing is arranged according to a certain geometric configuration, neatly piled up packing. There are many types of structured packing, which can be divided into grid packing, corrugated packing, pulse packing and so on according to its geometric structure.

 

Grating filler
(1) The grille filler is a strip-shaped unit body through a certain combination of rules, with a variety of structural forms. The earliest grille filler used in industry is wood grille filler. The more common applications are grille grille filler, mesh grille filler, honeycomb grille filler, etc., of which grille filler is the most representative.

 

The specific surface area of the grid packing is low, and it is mainly used for occasions such as small pressure drop, large load and anti-blocking.

 

corrugated packing

 

(2) Corrugated packing The vast majority of structured packing used in industry is corrugated packing, which is a disc-shaped packing composed of many corrugated sheets. The inclination angle between corrugated and tower shaft is 30 ° and 45 °. When assembling, two adjacent corrugated plates are oppositely stacked. Each disc packing is vertically installed in the tower, and two adjacent discs are staggered by 90 °.

Corrugated packing according to the structure can be divided into net corrugated packing and plate corrugated packing two categories, its material and metal, plastic and ceramic, etc.

 

Metal wire mesh corrugated packing is the main form of mesh corrugated packing, which is made of metal wire mesh. The pressure of corrugated metal wire mesh packing is reduced and the separation efficiency is very high. It is especially suitable for precision distillation and vacuum distillation equipment, which provides an effective means for the distillation of difficult separation systems and heat-sensitive systems. Despite its high cost, but because of its excellent performance is still widely used.
Metal plate corrugated packing is a main form of plate corrugated packing. The corrugated sheet of the packing is punched with many small holes of about f5mm, which can play a role in coarse distribution of liquid on the sheet and strengthening of horizontal mixing. The corrugated plate is rolled into fine grooves, which can serve to finely distribute the liquid on the plate and enhance the surface wetting performance. Metal orifice plate corrugated packing high strength, strong corrosion resistance, especially suitable for large diameter tower and gas-liquid load larger occasions.
Metal calendering plate corrugated packing is another representative plate corrugated packing. The main difference between it and the corrugated filler of the metal orifice plate is that the surface of the plate is not a punching hole, but a puncture hole, and a small puncture hole with a very dense aperture of 0.4~0.5mm is formed on the plate by rolling. Its separation ability is similar to the net corrugated packing, but the anti-blocking ability is stronger than the net corrugated packing, and the price is cheap, and the application is more extensive.

 

The advantages of corrugated packing are compact structure, low resistance, high mass transfer efficiency, large processing capacity, and large specific surface area (commonly used are 125, 150, 250, 350, 500, 700, etc.). The disadvantage of corrugated packing is not suitable for dealing with high viscosity, easy polymerization or suspended materials, and loading and unloading, cleaning difficulties, high cost.
(3) pulse packing pulse packing is a kind of regular packing which is assembled in a certain way by a hollow prismatic individual with constriction. After the pulse packing is assembled, a porous prismatic channel with a constriction will be formed, and its longitudinal flow channel will alternately shrink and expand, and strong turbulence will occur when the gas-liquid two-phase passes through. In the necking section, the gas velocity is the highest and the turbulence is intense, thus enhancing the mass transfer. In the expansion section, the gas velocity is minimized to achieve the separation of the two phases. The alternating repetition of channel contraction and expansion realizes the "pulse" mass transfer process.
Pulse packing is characterized by large processing capacity and small pressure drop, which is an ideal packing for vacuum distillation. Because of its excellent liquid distribution performance to reduce the amplification effect, it is particularly suitable for large tower diameter occasions.

 

tetrafluoro filler
PTFE valve stem packing is PTFE fine powder as raw material, using a new process from a soft products. White, continuous rope, circular in cross-section. It has a high degree of flexibility, excellent filling, self-lubricating, low friction coefficient, corrosion resistance and other properties. Technical parameters: use temperature -260~260, use pressure <20MPa, apply to all chemical substances except elemental fluorine and molten alkali metal. Advantages: · Loading is convenient and quick. When filling, it is generally not necessary to disassemble the valve, only the rope-shaped packing is wound on the valve stem, pushed into the stuffing box, and the cap is tightened, and the packing is pressed into a dense whole.
· Excellent sealing performance. The unique microstructure of expanded polytetrafluoroethylene gives the product excellent flexibility and moldability, so that it can easily fill the internal gaps of the stuffing box, and even all the pits and grooves on the valve stem and the body. This also makes the old valves that are corroded and worn avoid replacement or repair. · Long service life. Because of its long-term maintenance of soft plasticity, so that the leakage gap is filled at any time, but also because it is not corroded, will not age, can be used for a long time. · Flexible and light valve opening and closing. Because polytetrafluoroethylene has the lowest coefficient of friction and excellent self-lubrication. · Does not contaminate the fluid in the pipeline. Because it is white and clean, it will not fall off due to corrosion and aging, making it especially suitable for medicine, fine chemicals, food and other industries. Good versatility of specifications, reduce filler storage and save money. Only several sizes of stem packing are available to meet the needs of most valves. Generally, the largest filler that can be embedded by hand is selected, but the finer filler can also be used in large-size valves. After compaction, it will also be molded to obtain a dense sealing body.

 

plastic filler

Plastic filler is a filler formed by die pressing. It does not need to be cut into a ring like a braided filler when in use, and is made into a ring according to the size of the journal. Plastic fillers are available in two forms, cotton-like and laminated.
(1) Filler
The cotton filler is a mixture of fiber, graphite, mica, metal powder (or metal flake), grease and elastic binder, molded into a ring, and then braided a layer of asbestos yarn on the outer layer (metal wire can also be used as required). Another way of use is to put the mixture directly into the filler cavity and use it directly after being pressed by the gland. Because the filler has no fixed size, improper filling of the filler will easily affect the sealing performance, so this method is less used. The type and ratio of various mixtures in the cotton-like filler can be adjusted according to the working conditions, such as high-pressure steam sealing with copper powder, acid medium sealing with lead particles or lead sheets, and more elastic binders can be added when the shaft vibrates. Since this packing does not contain lubricants, its volume changes very little under high pressure and can be used for high-speed pumps and high-pressure valve seals. If a solid lubricant is added, good self-lubricating performance can be guaranteed, and the structure is compact, which helps to improve the sealing performance. In addition, the cotton filler has plastic fluidity and can also be used in combination with a metal filler.

 

(2) Laminated packing

This kind of filler is coated with rubber on the surface of asbestos cloth or canvas, and is formed by hot pressing and vulcanizing after lamination or winding. It can also be internally clamped with soft fillers such as rubber cores or embedded springs, and several laminated fillers. Laminate packing good sealing, can be used for low pressure steam, water and ammonia below 120 ℃, mainly used as a reciprocating shaft seal and valve stem seal, no interface ring packing can also be used as a reciprocating pump piston ring. Due to the lack of lubricant contained in the laminated filler, lubricants need to be added during use.

 

 

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