SCREW CONVEYOR
A & S THAI WORKS CO., LTD
A & S THAI WORKS CO., LTD
SCREW CONVEYOR is especially designed for transportation of raw materials, intermediate material like cooked material and press cake, and meals from one process step to the next.
Consist of the screw, trough U-shaped or circular, and gear motor drive and a cover for u-shaped troughs. The length of screw conveyors can go from 1 meter up to 32 meters and the diameter is standard ø250, ø300, ø350, ø400, ø500, ø600 mm, but practical length is what can fit into a 40 foot (12 meters) container. Very long screw conveyors can be flanged and joined together and still be transported in 40 foot container.
Construction materials can be made from mild steel or stainless steel or combinations. Some require stainless steel.
ASTW troughs mostly have a 120 degree liner made from hardened steel at the bottom of the trough to reduce wear.
The screw flight pitch is mostly 1:1 pitch/diameter when the conveyor is horizontal or little inclined, or 2/3 = pitch/diam when the conveyor is inclined up to maximum 30 degrees, only sometimes up to 45 degrees.
If more than 30 degrees a “hold back” angle-bar should be mounted at the up-turn side of the screw.
Screws in feeding, surge, metering bins or hoppers with VSD = variable speed drives can have increasing pitch for even emptying of the bin or hopper.
ASTW use screw conveyor for the following industries:
Beyond the actual transportation, the screw conveyor can also be used the following tasks:
ASTW has worked for over 11 years to make efficient and reliable vertical screw conveyors to lift dried meals to be stored in bins and silos, and also for continuous re-circulation and cooling of the meal in the bin.
To drain off loose liquids after twin screw press or HTR – continuous high temp rendering cooker.
It is important to air-cool fishmeal just after drying. The reason is to avoid oxidation and self-heating of the fishmeal and to make the fishmeal par-ticles more free-flowing and brittle before grinding. Rendering materials are less sensitive.
The option to cooling conveyor is to use a dedicated meal cooler, which in any case will be used for larger capacities.
For plant size under 60 tons input per 24 hours one can, to save cost, use one or two units of combined screw conveyor and meal cooler in one unit. One cooling screw conveyor is mounted after the drier and one unit after the hammer mill, and both units cool down the fishmeal by airflow, connected to a cyclone and blower. The warm air outlet can be ducted outside the factory into a water scrubber or bio filter to reduce any smell from the meal.
Key-hole type screw conveyors is the best solution to transport large pieces of un-hogged raw material from abattoir to the rendering plant bin, such as large bones, rib cages and cattle heads. Lamella pumps require pre-hogging and do not pump dry material very well and have high wear and maintenance costs, and occasionally clog up.
A good example is a meat processor in Melbourne: in 2015 they installed 150 meters of key hole, 500mm diameter screw conveyors from abattoir to the raw material bin, installation partly indoor and partly outdoor.
ALMOST AN “INSTALL AND FORGET” INSTALLATION EXEPT FOR OIL CHANGE FOR GEARS AND BASIC MAINTENANCE.
The raw material is un-hogged to reduce deterioration, and the material is only hogged or pre-broken just before entering the processing machinery.
To be used as a metering (feeding)(surge) unit for continuous processes such as cooker, pre-heater, dryer, twin screw press and hammer mill.