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Some common solids as flour, sugar, cement and many more,
can be suspended and transported in air - referred as pneumatic
conveying. A pneumatic conveying system may transport solids
up to approximately 50 mm size. The powder or solid must be
dry, with no more than 20% moisture and not sticking.
In a pneumatic conveying system, most of the energy is used
for the transport of the air itself. The energy efficiency
of a pneumatic conveying plant is therefore relatively low,
but this is often outweighed by easy handling and, in well
designed systems, dust free solutions.
In general the length of a pneumatic system should not extend
300 m for each pneumatic unit. The products can be conveyed
over long distances by connecting the systems in series.
There are three basic designs of pneumatic transport systems:
dilute phase conveying at a high gas speeds (20 - 30 m/s)
strand conveying at a limited gas speeds (15 - 20 m/s)
dense phase conveying at a low gas speeds (5 - 10 m/s)
Pneumatic systems can operate with both positive and negative
pressures - vacuum. The working pressure should not extend
40 kN/m2.
The maximum temperature rise during pneumatic compression
is seldom above 5oC, which makes pneumatic transport systems
suitable to sensitive products as medicines, food or similar
 
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