EM50 - SCRAPER WITH TRAVELLING BRIDGE FOR RECTANGULAR TANK
|Application||Clarifying of primary and secondary waste water|
|Tipi di macchine||Concrete runways
|Characteristics||The equipment consists of a rotating bridge with bottom and surface scrapers.|
|Operation||The waste water is clarified in a rectangular tank, the sedimentable solids settle on the tank bottom and are conveyed to a hopper by the bottom scrapers, while the floating material is conveyed into an oil removal pipe.|
|Materials||Hot dip galvanized carbon steel or Stainless steel|
|Installation||In a concrete tank|
|Tank diametre||From 4 to 25 m.|
|Tank length||From 2 to 100 m.|
|Optionals||Scum removal system|
PRINCIPLES OF SIZING
Hydraulic sizing (process)
The sizing of the feeding zone is based on the following parametres: • influent flow rate • dimensions of the pipings The water flowing to the sedimentation zone must have a very low kinetic energy in order to guarantee a good separation and settling of the solids.
The sizing of the bottom scraper is based on the type of sludge to be evacuated from the tank bottom.
Normally the trolleys and the scrapers are designed to bear a stress of 20 Kg. per linear metre.
The following checks regarding the movement of the machine components are very important for this kind of machine: • bridge: forward-backward movement • bottom scraper: lifting-lowering • surface scraper: lifting-lowering • electrical supply Our travelling bridges are always equipped with two limit switches for each movement (1 for operation and 1 for emergency) Buffer groups are also installed to limit the run of the moving units in case of failure the electrical limit switches and they are sized to bear the maximum stress.
We use a double motorization for bridges exceeding 6 m. of width and moving over a runway of more than 12 m. This solution allows to achieve a good alignment of the bridge, even if the two motorized wheels diametres are not exactly equal.
In this case, a simple motorization through a central shaft may cause the side-slip of one of the two motorized wheels.
Both the motorized hweels and the idle wheels must be perfectly parallel and at the same distance; for this purpose, after the installation of the bridge, the diagonals between the wheels must be carefully measured.
Contrast wheels and buffers
The contrast wheels and the buffers must be designed and sized so that the bridge cannot skid laterally out of the runways, under no circumstances.