3. General layout of a pneumatic conveying system
The pneumatic pressure conveying system consists of three main components
· Generation and preparation of compressed air
· Pressure sending vessel with material feeding attachmet,
· Conveying pipes, receiving silo with dust extraction filter.
Compressed air generation and preparation
The compressed air required for pneumatic conveying can be sourced from
an existing works air pressure line or generated by a separate compressor.
When sourcing the compressed air from a works pressure line (generally
a working gauge pressure of 6 bar), it must be reduced to the required
conveying pressure. Also, the required air volume must be adjusted. This
is done by means of an air-pressure-reducing and volume-control station.
When pressure reduction is employed there is an obvious direct energy
loss. Air is compressed to 6 bar, prepared and then expanded to conveying
pressure (e.g. 3 bar).
For direct generation of compressed air up to 1 bar an oil-free rotary
piston compressor is used and for air pressure > 1 bar a screw compressor.
The compressed air is then cooled to operating temperature (in most cases
30° C) either with a water cooler or an air-to-air cooler, depending on
availability of space or customer requirement. The compressed air must
be cooled for a number of reasons. First, special seals are not required
with cooled air, and insulation of tanks and pipe lines is also dispensed
with. Second, the conveyed material would be needlessly heated and, depending
on the type of the product conveyed, possibly sustain damage. The most
important reason for cooling the air, however, is that only with cooled
air can a constant air volume be attained. Since the the air temperature
rises simultaneously with increasing conveying pressure, the conveying
air expands. Uncooled conveying air results in higher and irregular velocities
of flow. This reduces output and increases wear.
Since condensation can develop during the cooling process we recommend
installing a condensation arrester.
3.2 The pressure vessel and its equipment.
On or two automatic shut-off valves are fitted to the inlet of the pressure
tank. Each pressure tank is further fitted with a level indicator, a safety
valve and a pressure relief cock.
Normally, each pressure tank is also fitted with an aspiration line. The
displacement air can be fed into the conveying line via this aspiration
line during the filling of the pressure tank. The pressure tank is further
equipped with an aeration device.
A pressure sensor of the control monitors the conveying process by measuring
and evaluating the conveying pressure.
The pressure vessel discharge gate is fitted with an control device. The
feeding attachmet or Beckshulte's nozzle housing system is available in
various designs depending on the nominal diameter of the conveying line
The conveying lines and the receiving silo with
dust extraction filter.
The path or the layout of the conveying pipes is important. The conveying
pipes must only be laid vertically or horizontally.
The receiving silo or container is fitted with a full indicator and with
a dust extraction filter which is pneumatically cleaned (residual dust
content > 1.0 mg/m³). If hazardous materials are conveyed, a
fine filter stage must be installed (residual dust content > 0.01 mg/m³)
The conveying pipe leads into a Beckschulte impact
head system.The silo must be fitted with at least one mechanical safety
device for controlling excess and low pressure. An additional pressure
switch to monitor the pressure electrically is recommended.
To Expand - 65 KB
Setting of pressure values in the visualization,
CZ - Teplice.
To Expand - 45 KB
Pressure characteristics at the end of conveying,
CZ - Teplice