Sludge scrapers for circular tanks
The correct structured entity is functionality and durability.
In the Finnchain system patented efficient removal of the floating scum. The scraper flight, moving at the surface of the tank, transfers the floating scum to the scum box on the side wall of the tank. The efficiency of the scum removal is ensured by scum gates. The scum gates can be adjusted, which enables more efficient removal of the floating scum.
If the tank has large sludge loads or the diameter of the tank is more than 40 m, Finnchain’s patented system with two drives can be used. The results of the load tests performed in the Finnchain’s test tank showed that the maximum load on the chain decreased almost 40% when the second drive was installed.
Finnchain has developed self-aligning scraper flight wheels which automatically find the correct path. This saves the bottom of the tank and the wheels from wearing.
The parts of the system are non-corrosive. The materials are plastic, fibreglass or stainless steel, surface treatment of components is not required.
Easy to cover
Tanks can be easily covered in order to prevent odour. The scraper will be rotated from the bottom, so that the covering of the tank can be attached to the tank walls.
Easy to transport, install and maintain
The scraper consists of components which can be assembled during the installation of the tank. The components are light-weight, which eases and speeds up the installation and the maintenance. The heaviest parts are the drive motor and gearbox weighing about 100 kg. Therefore the scraper can be delivered without special transportation and unloading of the cargo nor does the installation require special cranes.
Low construction costs
Light-weight structure of the scraper does not require massive concrete walls. A support structure in the middle of the tank is also not necessary, as the scrapers are attached to their own central bearing which is to be installed at the bottom of the tank. Due to its innovative structure the tank operates without complex electrical installations, it is sufficient to provide a power supply to the drive, located at the wall of the tank. The scraperload on the wall is carried by the idler wheels. Maximum load is 300 kg/idler wheel.
No problems with frost
Freezing on the top of walls of the tank does not cause scraper’s operational problems as all parts of the scraper are submerged.
PARTS – SLUDGE SCRAPERS FOR CIRCULAR TANKS
1 Driving mechanism
The drive motor, located on the edge of the tank, rotates a gear, from which the stainless steel drive shaft transmits the motion to the drive wheel.
2 Drive wheel
Stainless steel drive wheel carries the collector chain. The drive wheel has a patented adjustment feature that extends operating life of collector chain and wheel.
3 Idler wheels
The chain travels over idler wheels made from polypropylene, installed onto the tank wall. Idler wheels are installed in 3-4 m intervals.
4 Collector chain
The patented, polyamide collector chain is attached to the pulling chain, which moves the bottom- and surface scrapers.
5 Surface scum skimmer
The surface scraper is made of a fibreglass profile and is attached to the bottom scraper with a stainless pipe structure. The patented scum collector at the end of the scum skimmer efficiently transfers the floating scum to the scum box at the edge of the tank.
6 Bottom scraper
Each tank has at least two bottom scrapers, made of fibreglass profile. If there is a lot of sludge or the tank has a large diameter, additional bottom scrapers can be easily installed.