11.1 Suction plants
A suction plant is used for sucking off and transporting bulk material, in particular abrasive, with the help of a vacuum airstream. The Roots blower generates a vacuum causing ambient air to be sucked off. This airstream can transport dry or wet granular materials that are stored in bulk.
A suction unit for sucking off disposable and non-disposable abrasives consists of the following components:
- suction nozzle to suck off the abrasive
- suction hoses to transport the abrasive
- deposition unit to separate the mixture of air/abrasive (trough, vacuum silo)
- cyclone trough for pre-collecting dusts
- filter chamber to protect the blower, with vacuum valve
- dust hopper below the filter chamber to collect the dust
- Roots-blower to generate vacuum stream
- drive motor (with diesel and electric drive)
The conveyed material is collected by the expansion of the air in collecting units. For this purpose, troughs and vacuum silos are used. Abrasive cleaner and vacuum tight silos are used at recycling operation to separate the abrasive. The remaining dust is pre-collected within the cyclone with a tough underneath. The residual dust particles are collected in the cartridge filter chamber. The blower is connected with the driving unit via a belt drive. According to place and purpose of application electric or diesel motors are used.
In order to guarantee trouble-free operation and to avoid overload of the blower we recommend to use suction nozzles. The nozzles are designed in such a way that – if used properly - sufficient external air is always sucked off to transport the material.
The suction hoses have a rubber core or a polyurethane core that reaches a long service time also when abrasive materials are used. They are put together with hose connections and connected to the suction units with quick-release couplings.
In order to avoid overload of the blower various safety devices are mounted. The vacuum can be permanently controlled via a manometer. At idle run there will be a value of 0.2 b, this value will amount to 0.4 – 05 b at operation. If a value higher than 0.5 b will be displayed the following reasons could exist:
- blockage of the pipe
- overloading
- high friction losses caused by too long distances to be covered
In such a case the vacuum safety valve opens so that the blower sucks off ambient air. A thermometer controls the temperature of the outlet air and switches the unit off in case of overheating. If there is an electric drive the motor will be switched off in case of too high power consumption.
Suction plant
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Schematic presentation
of a suction unit
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