What are the types of fillers?

1. Lassie ring packing

The Rashching ring filler was invented by F. Rashching in 1914 and is a circular ring with an equal outer diameter and height. The gas-liquid distribution of Rasi ring packing is poor, with low mass transfer efficiency, high resistance, and low flux, which has been less widely used in industry.

2. Ball ring packing

The Bauer ring filler is an improvement on the Lacy ring by opening two rows of rectangular window holes on the side wall of the Lacy ring. One side of the cut ring wall is still connected to the wall, while the other side bends inward into the ring, forming an inward extending tongue leaf. The sides of the tongue leaves overlap at the center of the ring.

Due to the opening on the ring wall, the Bauer ring greatly improves the utilization of the inner space and surface, reduces airflow resistance, and distributes liquids evenly. Compared with the Lacy ring, the gas flux of the Bauer ring can be increased by more than 50%, and the mass transfer efficiency can be improved by about 30%. Ball ring is a widely used filler.

3. Stepped ring packing

The stepped ring packing is an improvement on the Bauer ring, which reduces the height of the stepped ring by half and adds a conical flange at one end compared to the Bauer ring.

Due to the decrease in aspect ratio, the average path of gas around the outer wall of the packing is greatly shortened, reducing the resistance of gas passing through the packing layer. Conical flanging not only increases the mechanical strength of the filler, but also changes the main contact between the fillers from line contact to point contact. This not only increases the gap between the fillers, but also serves as a gathering and dispersing point for liquid flow along the surface of the filler, which can promote the surface renewal of the liquid film and improve mass transfer efficiency.

The comprehensive performance of the stepped ring is superior to that of the Bauer ring, making it the most excellent type of ring packing used.

4. Arc saddle packing

Arc saddle filler is a type of saddle shaped filler, which is shaped like a saddle and is generally made of porcelain material.

The characteristic of arc saddle packing is that the surface is fully open, without distinction between inside and outside, and the liquid flows evenly on both sides of the surface. The surface utilization rate is high, the flow channel is curved, and the flow resistance is small.

Its disadvantage is that it is prone to stacking, causing a portion of the filler surface to overlap, resulting in a decrease in mass transfer efficiency. The arc saddle filler has poor strength, can withstand crushing, and is not widely used in industrial production.

5. Rectangular saddle packing

The rectangular saddle filling material changes the curved surfaces at both ends of the arc saddle filling material to rectangular surfaces with unequal sizes on both sides, making it a rectangular saddle filling material.

When the saddle packing is stacked, it will not overlap and the liquid distribution is relatively uniform. The rectangular saddle filler is generally made of porcelain material, and its performance is better than that of the Lacy ring. The vast majority of occasions in China where ceramic lacing rings are used have been replaced by ceramic rectangular saddle fillers.

6. Metal ring saddle packing

Intalox, also known as metal ring saddle packing, is a new type of packing designed to take into account the characteristics of both ring and saddle structures. The packing is generally made of metal material, so it is also known as metal ring saddle packing.

Ring shaped saddle packing combines the advantages of both ring shaped and saddle shaped packing, and its comprehensive performance is better than that of Ball ring and stepped ring, which is widely used in bulk packing.

7. Spherical packing

Spherical fillers are generally made of plastic injection molding and have various structures. The characteristic of spherical packing is that the sphere is hollow, allowing gas and liquid to pass through its interior.

Due to the symmetry of the spherical structure, the packing density is uniform, and it is not easy to generate cavities and bridge, resulting in good gas-liquid dispersion performance. Spherical fillers are generally only suitable for certain specific occasions and are rarely used in engineering.

In addition to the typical bulk fillers mentioned above, new types of fillers with unique configurations have been continuously developed, such as conjugated ring fillers, Haier ring fillers, and Nate ring fillers.

8. Regular packing

Regular fillers are fillers arranged in a certain geometric configuration and neatly stacked. There are many types of structured fillers, which can be divided into grid fillers, corrugated fillers, etc. based on their geometric structure.

Grid filler

Grid fillers are composed of strip-shaped units that are combined according to certain rules and have various structural forms. The earliest industrial application of grid filler is wood grid filler.

The commonly used types include Gridge grid fillers, mesh grid fillers, honeycomb grid fillers, etc. Among them, Gridge grid fillers are the most representative. The specific surface area of grid fillers is low, mainly used in situations where low pressure drop, high load, and anti blocking are required.

Ripple packing

The vast majority of regular fillers used in industry are corrugated fillers, which are disc shaped fillers composed of many corrugated thin plates. The inclination angles of the corrugations to the tower axis are 30 ° and 45 °, and the adjacent corrugated plates are stacked against each other during assembly. Each tray of fillers is vertically installed inside the tower, with adjacent trays of fillers arranged in a 90 ° staggered manner.

Corrugated fillers can be divided into two categories based on their structure: mesh corrugated fillers and plate corrugated fillers, with materials such as metal, plastic, and ceramic.

Metal wire mesh corrugated packing is the main form of mesh corrugated packing, which is made of metal wire mesh. The pressure of metal mesh corrugated packing is reduced, and the separation efficiency is very high. It is particularly suitable for precision distillation and vacuum distillation devices, providing an effective means for distillation of difficult to separate and heat sensitive materials. Despite its high cost, it has been widely used due to its excellent performance.

Metal plate corrugated packing is one of the main forms of plate corrugated packing. The corrugated plate of the filler is stamped with many small holes of about f5mm, which can play a role in coarse distribution of liquid on the plate and strengthen lateral mixing.

The corrugated plate is rolled into small grooves, which can subdivide the liquid on the plate and enhance the surface wettability. Metal orifice corrugated packing has high strength and strong corrosion resistance, especially suitable for large diameter towers and occasions with high gas-liquid loads.

Metal rolled orifice corrugated packing is another representative type of corrugated packing. The main difference between it and corrugated metal plate fillers is that the surface of the plate is not a punched hole, but a pricked hole. A dense pore size of 0.4-0.5mm is formed on the plate by rolling.

Its separation ability is similar to that of mesh corrugated packing, but its anti blocking ability is stronger than that of mesh corrugated packing, and it is cheap and widely used.

The advantages of corrugated packing are compact structure, low resistance, high mass transfer efficiency, large processing capacity, and large specific surface area (commonly used include 125, 150, 250, 350, 500, 700, etc.). The disadvantage of corrugated fillers is that they are not suitable for handling materials with high viscosity, easy aggregation, or suspended solids, and are difficult to load, unload, and clean, resulting in high cost.

Pulse packing

Pulse filling is a structured filling material composed of hollow prismatic individuals with necks that are assembled in a certain way.

After the assembly of pulse fillers, a porous prismatic channel with a necking will be formed, and its longitudinal flow channels will alternately shrink and expand, resulting in strong turbulence when the gas-liquid phase passes through. In the necking section, the gas velocity is the highest and turbulence is intense, thereby enhancing mass transfer. In the expansion section, the gas velocity is minimized to achieve two-phase separation. The alternating repetition of channel contraction and expansion achieves a "pulse" mass transfer process.

The characteristics of pulse packing are large processing capacity and low pressure drop, making it an ideal packing material for vacuum distillation. Due to its excellent liquid distribution performance, the amplification effect is reduced, making it particularly suitable for situations with large tower diameters.

9. Tetrafluoro filler

PTFE valve stem packing is a soft product made from PTFE fine powder and processed using a new process.

White, continuous rope shaped, with a circular cross-section. It has high flexibility, excellent filling, self-lubrication, low friction coefficient, corrosion resistance, and other properties.

Advantages:

Convenient and fast loading. When filling, it is generally not necessary to disassemble the valve. Simply wrap the rope shaped packing around the valve stem, push it into the packing box, tighten the cover cap, and the packing will be compressed into a dense whole.

Excellent sealing performance. The unique microstructure of expanded polytetrafluoroethylene endows the product with excellent flexibility and moldability, making it easy to fill the internal gaps of the packing box, even all pits and grooves on the valve stem and body. This also prevents the replacement or repair of corroded and worn old valves.

Long service life. Due to its long-term softness and plasticity, the leakage gap can be filled at any time. Additionally, it is not corroded or aged, and can be used for a long time.

The valve is flexible and lightweight in opening and closing. Because polytetrafluoroethylene has the lowest friction coefficient and excellent self-lubrication.

Do 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 particularly suitable for industries such as medicine, fine chemicals, and food.

The specification has good universality, reduces the storage capacity of fillers, and saves expenses. Simply prepare several sizes of stem packing to meet the needs of most valves.

Generally, the largest size of packing that can be inserted by hand is selected, but the finer type of packing can also be used in large-sized valves. After compression, it will also plastic form to obtain a dense sealing body.

10. Plastic filler

Plastic filler is a type of filler formed by mold pressing, which does not need to be cut like braided filler before being coiled into a circular shape. It is also made into a circular shape based on the size of the shaft neck. Plastic fillers come in two forms: cotton like and laminated.

Soft filling material

Cotton filling material is a mixture of fibers, graphite, mica, metal powder (or metal flakes), grease, and elastic binder, molded into a circular shape, and then woven with a layer of asbestos yarn (metal wire can also be used as needed) on the outer layer.

Another way to use it is to place the mixture directly into the packing chamber and use it directly after being compressed by the gland. Due to the unfixed size of the packing, improper filling of the packing can easily affect the sealing performance, so this method is less commonly used.

The types and proportions of various mixtures in the sponge filling can be adjusted according to working conditions, such as adding copper powder for high-pressure steam sealing, adding lead particles or sheets for acidic medium sealing, and adding more elastic and good adhesive when the shaft is vibrating.

Due to the absence of lubricants, this type of packing has minimal volume change under high pressure and can be used for sealing high-speed pumps and high-pressure valves. If solid lubricants are added, good self-lubricating performance can be ensured, and the structure is dense, which helps to improve sealing performance. In addition, cotton fillers have plastic fluidity and can also be used in combination with metal fillers.

Layer filling material

This type of filler is coated with rubber on the surface of asbestos or canvas, which is laminated or wound before hot press vulcanization forming. It can also be sandwiched with soft fillers such as rubber cores or embedded in springs, and has several layered filler structures.

The packing layer has good sealing performance and can be used for low-pressure steam, water, and ammonia liquid below 120 ℃. It is mainly used for reciprocating shaft seals and valve stem seals. The ring packing layer without interfaces can also be used as piston rings for reciprocating pumps. Due to insufficient lubricant in the packing layer, lubricant needs to be added during use.