The mechanical drier is the most effective drier in plastics recycling for reduction of water content after washing. Residual humidity is reached with this equipment that markedly reduces the effort of thermal drying. Depending on the product, residual humidity of < 1 % are reached.
The ground material to be dried is taken up by the machine and passed without intermediate conveying (distance up to 5 metres) to the next process stage by means of a specially designed material spout.
Rotor and basket screen are designed so that high friction forces arise. Apart from drying the material, this also leads to cleaning from dust. The basket screen is therefore always kept clean by automatic screen cleaning. If desired, the vanes of the rotors may be fitted with interchangeable elements when there is high wear, in order to be able to have low repair costs.
STEP DRIER
The step drier is excellent for dewatering and drying granulate in the thermoplastics polycarbonate, polyethylene, polyamide, polypropylene and polystyrene. The achievable residual moisture levels fluctuate in the range of 0.4 – 0.06 wt%.
Method of operation:
Compared with conventional equipment, the step drier is fitted with a step-shaped basket screen and with an equally step-shaped rotor.
The mixture of granulate and water flows into the low part of the basket screen and is conveyed from there with conveyance vanes to the next step.
Here, the granulate is accelerated radially and arrives again at the stationary screen.
After separation of the splash water in the first step, the granulate is suddenly accelerated in the second step.
High inertia forces are produced here, whereby the residual water drops as well as adhered water film are significantly better separated than with previously known equipment.
Step drier
Configuration of a step drier
Before the granulate leaves the separation area, it is thoroughly flushed with air. The static pressure arising in the upper part of the drier prevents fine water mist is carried through with the exit of the product.
The step drier consists of a round machine housing with drive motor and an air extraction area underneath it. The product feeding hopper is mounted on the side alongside the housing. The rotor is attached with a flange and can be lifted out of the housing after loosening of the fixing screws and swivelled to the side. Exit of the product is provided by a spiral-shaped opening in the cover. Exit of water can be chosen to be provided vertically or horizontally. All metal parts – with exception of motor and lifting hoist are made in rust-free and durable stainless steel.
