Grinding screens are intended for bulky waste material that are found in industrial and domestic wastewater. Grinding screens can be installed in sewer pump stations (SPS) and in the headworks of wastewater treatment plants. The screens are intended for use in wastewater with a pH of 6.5-8.5.
Cutters and shafts of the screens are manufactured from high tensile tool steel, while the frame is manufactured from stainless steel AISI 304. The screen consist of two sets of rotating cutters located vertical on drive shafts enclosed in the frame. Rotating filter drums can be installed on one or both sides ofthe grinding unit depending on the channel width. The cutters and drums are driven by geared motors.
Auxiliary fixing devices allow lifting of the screen from the channel without emptying it,therefore maintenance can be carried out without stopping operation. The grinding mechanism and filtering drum are installed as separate units and can be removed from the device without lifting the grinding screen.
From the rotation of the perforated drums, the solids are moved to the grinding unit where the cutters grind the waste and direct it further along the channel. The cutters rotate at different speeds to create the shear effect.
- Protects downstream equipment by reducing the size of solids suspended in the wastewater.
- Reduction of service personnel demand of the pumping stations and costs on waste disposal.
- High screen productivity and reliable performance due to the design of the drums which prevent waste build up inside the screen.
- High serviceability due to the screen design – easy mounting and dismounting.
Automatic protection against jamming with reverse and restart of the grinding cutters
Screen automation can be done according to different parameters:
- Time period.
- Wastewater level difference upstream and downstream of the screen.
- Any customized program.
The screen’s automatic safety is achieved by a short reverse cycle of the cutters to prevent jamming by solid waste.
Alarm systems of the normal operation indication, the emergency stops, the wastewater top level in the channel and others are provided. It is possible to transfer equipment status data to a higher level automated process control system depending on the client’s requirements.
|Minimum width of the channel, mm||300…1100|
|Channel depth, mm||750…2500|
|Drive power of cutters, kW||3…7,5|
There are three types of the screens:
- Small – without filtering drum
- Middle – with one filtering drum
- Large – with two filtering drums
- Rods screen