EM53 - SCRAPER WITH DREDGING CHAIN FOR RECTANGULAR TANK
|Application||Clarifying of primary and secondary waste water|
|Characteristics||The equipment consists of a dredging chain 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 2 to 16 m.|
|Tank length||From 20 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 scrapers is based on the type of sludge to be evacuated from the tank bottom. Normally the scrapers, shafts and chains are designed to bear a stress of 20 Kg. per linear metre.
Torque limiting device (dynamometric cell)
The dynamometric cell measures the torque transmitted by the drive unit. This value is evident directly on the instrument and allows to evaluate the stresses on the moving members during the rotation. The device is equipped with limit switches set at two different torque values, one for alarm and one for the machine shutdown.
The movement of the chains must be carefully checked because it is very important for this type of machine.
For this purpose, we use to apply some sensors to check the idle shafts rotation.