Position: Sorbent powder is purchased in 25kg bags. Bags are emptied through a door into the powder feeder, which can hold about 2 sacks of powder. The powder hopper is fitted with a dust extraction unit. The fan sucks air and entrained dust from the bag discharge point through cartridge filter elements which filter the air and return the collected dust to the weigh hopper.
The powder feeser has an air powered impact vibrator which is mounted on the side of the weigh feeder's hopper. This runs intermittently, the air supply being controlled by an adjustable integrated timer / solenoid valve. It breaks up the lumps of agglomerated powder so that it feeds through the finger guard into the lump breaker.
The lump breaker has a double claw rotor, driven at constant speed. The walls of the chamber are polyurethane, so they flex with the movement of the rotor. The width of the chamber reduces towards the bottom, forming a trough.
The powder feed screw is an auger running in this trough and through the vessel wall. Outside the vessel wall the auger runs in a feeder tube that is attached to the vessel. This tube runs full and discharges the powder through the tundish to the venturi. The auger is driven via a manually controlled variable speed unit, different gear box ratios are available giving several ranges of powder delivery rate.
The venturi is driven by compressed air at 6 bar. This discharges air through a nozzle under the powder feed point and this airflow entrains the powder. The venturi discharges into a tube for connection to the process. The shut off valve closes automatically if the air pressure to the venturi is lost.
What The Feeder Does
Injects powders into process gas flows where the process gas is at a pressure up to 0.3 bar gauge. Allows remote location for convenient sack and pallet handling. Can handle most gas treatment powders but lime, Ca(OH)2, can cause blockages in the venturi eductor.
Capacity of Powder Feeder A-HP
Powder weigh feeder's hopper approximately 60 kg powder
Powder feeding (max.) depending on choice of gearbox, 20 / 15 / 12 / 8 / 5 kg/h
Powder feeding (min) 20% of maximum,
Conveying air 30 Nm3/h
Entrained air depends on conveying distance, typically 10 Nm3/h
Conveying distance 15m horizontally, 5m vertically, up to 3 swept bends
Motors of The Powder Feeder A-HP
Impact vibrator requires 6 bar air and 110v supply for air solenoid valve
Lump breaker 0.37 kW, 3-phase
Screw feeder 0.25 kW, 3-phase
Fan 0.75 kW, 3-phase
Filter cleaning controller 110v supply
Compressed air requires 110v supply for ball valve, n/c.
Feeder Control
Two interlocked start signals are required: on the ‘Start Blowing’ command, the compressed air valve and impact vibrator are switched on; on the ‘Start Feeding’ command the lump breaker and screw feeder are started. The ‘Stop’ signals reverse the effect of the corresponding ‘Start’ signals.
The unit can be supplied either complete with a control panel or with no controls. Caldo’s control panel incorporates the stop / start controls, overloads, emergency stop and main isolation switch. Alternatively, the purchaser can integrate the weigh control into a larger panel serving several modules.
Maintenance of The Feeder
Lubrication:top up oil in impact vibrator lubricator
Inlet air filter: clean entrained air inlet filter
Caldo Engineering, 1 Worcester Court, Saxon Business Park, Bromsgrove, Worcs, B60 4FH UK;
Tel +44 (0)1527 579000; Fax +44 (0)1527 579036; email caldo@caldo.coms; web http://www.caldo.com
