Fillers - a possibility to increase the effective surface
In chemical processes it is necessary to extend the surface of the sphere of action. At the same time the flow resistance is kept low. This is achieved with a packing. The application areas are in apparatus engineering and process engineering. The materials used range from stainless steel to plastics and ceramics. Steel is often used in the chemical industry, as it often has to withstand chemical, aggressive influences. In biological water treatment, plastic is used for fouling bodies.
Areas of application for fillers
In biological wastewater treatment, bacterial cultures are cultivated with it. Polyethylene is extremely bacteria-friendly. Thus the cultures are sufficiently washed around by the waste water. The packing is marked with bars, lamellas and openings to improve this process even more. For this type of waste water treatment, suspended solids, rotating immersion solids, trickling filters or a submerged fixed bed are used.
A separation column that is equipped with a loose layer of packing is called a packed column. In the chemical industry these are placed on perforated support grids. The steam flows through them into the fill. This serves to separate mixtures. It is important to note that no brook formation occurs. This can be caused by equal alignment of the packing or an uneven density of the fill. Marginality is avoided by proper placement and choice of packing.
What types of fillers are available?
The most common form is "rings". These are hollow cylinders, which are provided with webs or incisions. But also ball or saddle forms are possible. Mostly they are used as piles with high porosity and inner surface.
The best mass transfer is given with a VFF-NetBall. This is a spherical body. It has a special net structure and is hydraulically extremely resilient. In addition, it works with the lowest pressure loss.
The BIO-NET liquid distributor has grid tubes with lamellas inside. These are welded into blocks. This variant is used in rotating immersion bodies and immersed fixed beds. This way waste water is treated biologically.
A VFF-Twin-Pak is a VFF patent. It is a metal, modern high-performance packing with profile. This corresponds in roughly ordered packings, but offers all the advantages of a tower packing. This design ensures optimum pressure loss with a fixed mass transfer.
NOR-PAC packings have short sections of grid tubes with lamellas inside. The grid structure results in a lower pressure drop or a high hydraulic load. This model is mainly used in drinking water treatment.
A VSP is a hollow cylinder with an elaborate grid structure. Some of them are equipped with cross bars. This packing is very light.
The circumferential helix Hel-X is provided with lamellas which are directed inwards. This creates a large surface with a high degree of gaps. This version is made of HDPE and is used for waste water purification, biological exhaust air purification and water treatment.
The Berl saddle is very similar to a horse saddle. It is two saddles which are twisted into each other.
Hackettes are spherical filling bodies with segments that are formed like webs. The cohesion is given by a ring.
The Raschig ring is one of the oldest fillers at all (synonym: bulk fillers). He brought a decisive leap forward in the development of process technology. This is a hollow cylinder with the same diameter and length. A special application is the use of borosilicate glass. This prevents the formation of critical masses.
A hiflow ring is a hollow cylinder with eight sail surfaces and a cross. The sail surfaces point offset inwards. This design also leaves holes.