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What the hell is Yuan Lei's small class? These 10 common fillers must be unknown! (with packing selection tips)

Release time:

2024-01-29 09:37

 

What the hell is Yuan Lei's small class? These 10 common fillers must be unknown! (with packing selection tips)

 

Fillers are widely used in chemical production processes. What do you know about fillers? What are the common types of fillers? How to choose the right filler? Take a look ~

 

 

 

What is filler?

 

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 Raschil ring, etc., its role is to increase the gas-liquid contact surface, so that they are strongly mixed with each other.

 

In chemical productsFiller, also known as filler, refers to solid materials used to improve processing performance, mechanical properties of products and (or) reduce costs.

 

In the field of sewage treatmentMainly used for contact oxidation process, microorganisms will accumulate on the surface of the filler, in order to increase the surface contact with the sewage, the sewage degradation treatment.

 

Advantages:Simple structure, small pressure drop, easy to use corrosion-resistant non-metallic materials, etc. It is suitable for gas absorption, vacuum distillation and handling of corrosive fluids.

 

Disadvantages:When the tower neck increases, it causes uneven distribution of gas and liquid, poor contact, etc., resulting in a decrease in efficiency, which is called the amplification effect. At the same time, the packed tower also has the disadvantages of heavy weight, high cost, trouble cleaning and maintenance, and large packing loss.

 

 

What are the types of fillers?

 

1. Rassey ring packing

 

Rassey ring packing was invented by Rassey (F. Rashching) in 1914 and is a ring with an equal outer diameter and height. 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.

 

 

2. Ball ring packing

 

Ball 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 connected 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 which is widely used.

 

 

3. Step ring packing

 

The stepped ring packing is a modification of the Pall ring. Compared with the Pall ring, the stepped ring height is reduced by half and a tapered flanging 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.

 

 

4. Arc saddle filler

 

Arc saddle filler is a kind of saddle filler, its shape is 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.

 

5. Moment saddle filler

 

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.

 

 

6. Metal ring moment saddle filler

 

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.

 

 

7. Spherical packing

 

Spherical packing 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.

 

8. Regular 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 grille packing, corrugated packing and so on according to its geometric structure.

 

increaseGrating filler

 

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.

 

 

It is.corrugated packing

 

Most of the 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 axis is 30 ° and 45 °. When assembling, two adjacent corrugated plates are opposite to each other. 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.

 

a.pulse packing

 

Pulse packing is a kind of regular packing which is assembled by hollow prismatic individuals with necking.

 

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.

 

9. 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.

 

 

Advantages:

 

increaseLoading 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.

 

It is.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.

 

a.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.

 

Valve opening and closing flexible and light. Because polytetrafluoroethylene has the lowest coefficient of friction and excellent self-lubrication.

 

NoorDo 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.

 

NoorayGood 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.

 

10. 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.

 

increaseflannel 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.

 

It is.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.

 

 

How to choose filler?

 

The selection of the filler includes determining the type, specification and material of the filler. The selected filler should not only meet the requirements of the production process, but also minimize the equipment investment and operating costs.

 

1. Selection of packing type

 

Considering the requirements of the separation process, the following aspects are usually considered:

 

  • In general, the mass transfer efficiency of structured packing is higher than that of bulk packing.

  • Flux to be large. On the premise of ensuring high mass transfer efficiency, the packing with high floodpoint gas velocity or gas phase kinetic energy factor should be selected.

  • The pressure drop of the packing layer should be low.

  • The filler has strong anti-fouling performance and is convenient for disassembly, assembly and maintenance.

 

2. Selection of packing specifications

 

The filler specification refers to the nominal size or specific surface area of the filler.

 

increaseSelection of Bulk Filler Size

 

Industrial tower commonly used bulk packing mainly DN16, DN25, DN38, DN50, DN76 and other specifications.

 

Similar packing, the smaller the size, the higher the separation efficiency, but the resistance increases, the flux decreases, and the packing cost also increases a lot. The application of large-size packing in small-diameter columns will cause poor liquid distribution and serious wall flow, which will reduce the separation efficiency of the column.

 

Therefore, the ratio of tower diameter and packing size should have a regulation, the ratio of general tower diameter and packing nominal diameter D/d should be greater than 8.

 

It is.Selection of structured packing specifications

 

There are many ways to express the types and specifications of structured packing commonly used in industry. It is customary to express the specific surface area in China, mainly including 125, 150, 250, 350, 500, 700 and other specifications.

 

For the same type of structured packing, the larger the specific surface area, the higher the mass transfer efficiency, but the resistance increases, the flux decreases, and the packing cost also increases significantly.

 

The selection should be from the separation requirements, flux requirements, site conditions, material properties and equipment investment, operating costs and other aspects of comprehensive consideration, so that the selected filler can meet the technical requirements, but also has economic rationality.

 

3. Selection of filler material

 

The material of the filler is divided into three categories: ceramic, metal and plastic.

 

increaseceramic filler

 

Ceramic fillers have good corrosion resistance and heat resistance, ceramic fillers are cheap, have good surface wetting properties, brittle, fragile is its biggest disadvantage. It is widely used in gas absorption, gas washing, liquid extraction and other processes.

 

It is.plastic packing

 

The material of plastic filler mainly includes polypropylene (PP), polyethylene (PE) and polyvinyl chloride (PVC), etc., and polypropylene material is generally used in China. The corrosion resistance of plastic filler is good, and it can resist the corrosion of general inorganic acid, alkali and organic solvent. It has good temperature resistance and can be used for a long time below 100 ℃.

 

Plastic filler is light, cheap, has good toughness, impact resistance, not fragile, can be made into thin-walled structure. It has a large flux and a reduced pressure, and is mostly used in absorption, desorption, extraction, dust removal and other devices.

 

Plastic fillers have the disadvantage of poor surface wetting properties, but their surface wetting properties can be improved by appropriate surface treatment.

 

a.metal packing

 

Metal filler can be made of a variety of materials, the choice of the main consideration of corrosion.

 

Carbon steel fillers are low in cost and have good surface wetting properties, and should be preferred for non-corrosive or low-corrosive systems.

 

Stainless steel filler corrosion resistance is strong, the general ability to resist in addition to Cl-other common corrosion, but its high cost, and the surface wetting performance is poor, in some special occasions (such as very low spray density under the vacuum distillation process), the need for surface treatment, in order to achieve good results.

 

Titanium, special alloy steel and other materials made of filler cost is very high, generally only in some highly corrosive materials used under the system.

 

Generally speaking, metal fillers can be made into thin-walled structures, which have large flux, low gas resistance, and high impact resistance. They can be used at high temperature, high pressure, and high impact strength, and have the widest range of applications.

 

Summary:

 

When selecting fillers, the optimal criteria for a particular application are based on the desired properties of the composite material, taking into account the following basic principles.

 

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 and non-corrosive.

 

3. Easy to handle, high bulk density, low moisture content, low dust, non-toxic.

 

4. It must be easy to get, sufficient supply, moderate price and stable quality.

 

 

 

 

 

 

Packing, corrugated, performance, surface, structure, application, general, metal, efficiency

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