Rake screens can be installed at sewer pumping stations and at headworks of wastewater treatment plants.
Rake screens are intended for extraction of large and medium waste solids from industrial and municipal wastewater with subsequent unloading on a transporter or into a waste bin.
The screens are intended for use in the wastewater with pH = 6.5÷8.5.
Rake screens of different dimensions are made of stainless steel AISI 304 or AISI 316 on client demand. Dimensions of the rake screens are selected depending on required flow rate, wastewater composition and dimensions of the channels.
The rake screen is a filtering mesh consisting of bars installed into a frame. The bars are made from structural shapes with a tear drop shaped cross section that improves flow characteristics of the filtering mesh. The screen’s filtering mesh can also be made of rectangular or round profile bars.
Bar spacing in the filtering mesh can vary from 5 - 100mm for typical equipment or can be adjusted individually. The rectangular frame consists of two longitudinal boards connected by cross beams. The laminated stainless steel chains can be moved along polymer guides installed on the longitudinal boards of the screen. Chain tension is adjustable.
Cross rakes are installed on the chains for cleaning of the filtering mesh. Chains and rakes are actuated by shaft rotation with drive sprockets located in the screen top section. The shaft is driven by a geared motor. At the screen bottom, the chain is moved along a pilot slider made of a wear resistant polymer material. Therefore, there are no rotating parts in the submerged section of the screen.
The screen is installed onto an axis of a special rotating prop mounted on the wall of the channel or onto special platform fastened in the channel while the screen itself can be lifted over the channel for maintenance. If there is a lack of space in a short channel without possibility of screen lifting, a special telescopic platform is used.
The rake screen collects and removes solids from wastewater that larger than bar spacing. The solids are periodically taken off from the filtering mesh by the rake moving them to the top edge of the frame. The solids are then removed from the rake by means of a kicker and dispatched along the gravity slide onto a transporter or into waste bin. The screen operation periodicity depends on the chosen equipment automation scheme and defined by technological commission results.
Screen automation can be done according to different parameters:
|Channel width, mm||600÷2100|
|Channel depth, mm||600÷6500|
|Bar spacing, mm||5; 6; 8; 10; 15; 20; 30÷100|
|Inclination angle, °||80|
|Waste unloading height, mm||depend on project|
|Power, kW||0,37; 0,75|
|Drive protection rating||IP 55|
* Screen dimensions can be adjusted depending on the client’s requirements.