Pneumatic systems are extremely safe and reliable and – because they contain hardly any mechanical moving parts – are virtually maintenance-free and non-wearing compared to mechanical conveyors.
There are generally two basic designs: the low-pressure or low-density conveying system, which uses a radial fan as the compressor, and the high-pressure (HP) or high-density (HD) conveying system, which uses a rotary piston blower. High-pressure systems are ideal for use with conveying quantities of 1 to 100 t/h, conveying systems of up to 1,500 m in length, and nominal widths between 88 and 500 mm.
The longer the material conveying path and the higher the quantity of material that needs to be transported, the more criteria speak for the use of high-pressure conveyor systems. The key components of this design are a rotary blower that combines high levels of efficiency with low energy costs, and airlocks such as massive rotary valves (Scheuch type zss) or particularly massive cutting rotary valves (Scheuch type zsm), both in welded design.
Even with large quantities of material, the injectors ensure that only a small amount of energy is expended for the drive power. Thick-walled steel pipes and bends with wear protection ensure long service lives. High-pressure systems are ideal for use with conveying quantities of 1 to 100 t/h, conveying systems of up to 1,500 m in length, and nominal widths between 88 and 500 mm.
1. Cyclic process system (closed circular pipeline) without separator:
Recommended for smaller material quantities and shorter conveying distances. The exhaust air is re-used as conveying air. The advantages of this design lie in its low investment costs, lack of exhaust air and, therefore, absence of a filter, with material being injected directly into the silo or container. Decoupling is required for safety reasons.
2. Cyclic process system (closed circular pipeline); cyclone and rotary valve:
This system is used for larger material quantities and short conveying distances. It offers the same advantages as those listed above. This system is also decoupled by means of the rotary valve.
3. Filtering separator:
The most economical system for large material quantities and long conveying distances. The separator can take the form of either a silo installation filter with a housing strength that is able to withstand the internal pressure of the silo or a bag filter with a rotary valve for decoupling.
While the first variant offers the advantage of low investment costs despite the drawback of overpressure in the silo, the second variant offers decoupled material discharge and neutral pressure conditions in the silo.