Line filters

Line filters are generally applied in case of the following requirement profile: 

- large exhaust air quantities, 

- large material quantities, 

- continuous operation, 

- expandability. 

• Large exhaust air quantities
  
  Exhaust plants with air quantities > 50.000 m³/h primarily are equipped with line filters applied as intermediate filter. The installation close to the building results in short ways for the exhaust pipework and for the return air system leading to low pressure loss and therewith an energy-saving operation.
  
  In principle line filters can be lengthened user-defined, so that existing plants can be adapted to changed demand.

• Large material quantities
  
  Line filters can be equipped with a scraper conveyor or a conveyor screw, installed into the hopper elements. By dividing the brought in air- and material quantities to several injection chambers an evenly spread material entry is reached. By one or several rotary valves distributed along the length of the hopper the discharged material is handed over to the transport plant. 
  
  Only for extreme large material quantities cyclones with preseparators are applied and the filter plant is used as afterfilter.
  
  

• Continuous operation
  
  Particularly in case of connection of production lines with several working shifts an uninterrupted 24-hour operation is required. With the cleaning systems compressed air (jet-pulse) and in particular scavenging air (process air) this requirement can be fulfilled.
  
  During the scavenging air cleaning process the heavy duty fan mounted on a carriage is moved from filter hose line to filter hose line and the air sucked out of the clean-air room is blown into the filter hoses. By the generated scavenging effect the dust cake formed on the outside of the filter hoses is loosened. To avoid disturbing of the cleaning process the neighbour filter hose lines are covered and an air flow is prevented.
  
  The cleaning process is released either depending upon pressure difference or timedependent. 

Filter houses

Referring to the exhaust air quantities and material quantities for the filter houses in principle similar characteristics are valid as mentioned above for the line filters. Based on the design of these filters the following characteristics arise:

Filter houses are compact units with square base, being able to cope with large air- and material quantities on a small installation area. Compared to line filters the filter houses can not be expanded.

The filter house consists of a filter-/clean-air chamber and a container, capable for a material volume of up to 30 m³, so that the separated material can be buffered in it. By this possibility variations in material quantity are balanced. A further, very important advantage in the process is that the transport plant can be driven not permanent, but generally intermittently and for this reason energy-saving.

The material is discharged by a solid, rotating, horizontally positioned conveyor screw and handed over to the transport plant by one or two rotary valves.

With filter houses exhausting plants with an air quantity of up to 100.000 m³/h can be equipped.

Filter houses are an alternative to the line filters, particularly when the aspects compactness and material buffering are important.

Filters in modular design

Also the large filter units are designed in modular design, this means that only a small quantity of different construction parts is used for construction of the filter unit. Its advantage is that the individual canted steel plate profiles can be produced in larger quantities. The result is a very good price-performance-ratio.

The filters consist of individual elements and/or modules:

- profile steel frame with hopper (line filter) or container for material buffering (filter house), 
- filter chamber, 
- blow-in chamber and
- clean-air chamber. 

• Profile steel frame
  Made of heavy profile steel girder as screwed bending resistant frame assembly.
  
  

• Hopper (line filter)
  The hopper is made of galvanised steel plate profiles. For the discharge of material it can be equipped with a solid chain scraper conveyor or a trough screw conveyor. 
  
  The hopper is completely assembled in our factory.
  
  

• Material container (filter house)
  The container is made of galvanised, canted steel plate profiles. The separated material is handed over to the transport plant via a heavy discharging unit with two horizontally working conveyor screws with adjustable forced feed via two ejection openings and rotary valves.
  
  

• Filter chamber 
  As standard the filter chambers are executed in three construction heights for the filter hoses with different hose lengths. The quality of the filter material depends upon the application. In the wood branch as standard dust class M is applied for return air plants. 
  
  The filter hoses are charged from the outside and easy to install and easy to maintain fastened with a snap ring in the filter plate.
  
  

• Blow-in chamber
  The exhaust pipework lines are connected to separate blow-in chambers via non-return valves. By the reduction of the flow speed and the flow direction change larger particles are directly separated (preseparation effect) and for this reason the filter hoses are only charged gentle with fine particles.
  
  

• Clean-air chamber
  In the clean-air collecting room the air fan (reverse-air cleaning) assembled onto a carriage or the compressed-air rods with compressed-air tank and magnetic valves are installed.
  
  The clean-air chamber can be designed higher so that a walkable service- and/or maintenance alleyway results.