Belt Filter Presses – Type 400
Sludge Dewatering with Belt Filter Presses Type «400»
Belt Filter Presses Description
Belt filter presses type “400” main characteristic is their inexpensiveness thanks to the project optimization aimed to use simple and reliable components.
Belt filter presses type “400” are manufactured in different models to meet the sludge characteristics and quantity to be dewatered.
The main characterists to distinguish the different models are:
Quantity of pressing rollers:
Filtering belts width:
Accessories on board of the machine: Predewatering Drum
- Mixer for Small Flowrates
- Mixer for Big Flowarates
1. BEARING FRAME
Made of two very thick carbon steel plates (on request, SST AISI 304), fixed to each other by means of profiles and welded to form a stiffen perfectly levelled unit. The whole structure is protected by sand-blasting type Sa 2.5, then by a zinc-aluminium alloy hot spraying and finally covered by a layer of bicomponent polyurethanic resin. Bolts and nuts are made of SST A2 AISI 304.
The pressing, tensioning, transmission and sludge discharge rollers are protected by hot metal spraying and painted with bicomponent polyurethanic emails. The motorized pressing roller and the trajectory correction one are coated by 8 mm. of rectified rubber layer (on request, all of them can be rubber covered).
All the rollers are supported by ball bearings type ‘Y’ which are suitably sized and guarantee a perfect impermeability.
4. FILTERING BELTS
The filter press is equipped with SST clipper seam belts, protected by epoxy resins.
5. BELTS TRACTION SYSTEM
Models with belts width of 800¸ 2000 mm.:
it consists of a worm motor variator with speed manual adjustment, directly keyed to the roller;
Models with belts width of 2500¸ 3000 mm.:
it consists of an epicyclic motor variator connected to a traction roller by a toothed crown and chains protected by carters.
6. BELTS GUIDE SYSTEM
Pneumatic type with proportional action probes to keep the belts continuously centered and one upon the other.
7. BELTS TENSION SYSTEM
It consists of pneumatic jacks with air springs which keep the belts tensioned.
8. BELTS WASHING SYSTEM
It consists of spray header pipes equipped with nozzles which can be cleaned by a special device with brushes which can be operated from outside. The header pipes are protected by carters which avoid the aerosol effect and collect the belts washwater separately. The whole system is made of SST AISI 304, apart from the protection carters which are made of carbon steel (on request, they can be made of SST AISI 304).
9. WATER COLLECTING PANS
They are completely made of carbon steel and equipped with suitable slopes and outlet pipes.
On request, they can be made of SST AISI 304.
10. ELECTRIC AND PNEUMATIC PLANTS ON BOARD OF THE MACHINE
Electric plant in waterproof casing with terminal strips for all the power cables and signals.
The machine is also equipped with a pneumatic plant complete with reduction filters and manometers to adjust the belts tension and the speed of the trajectory correction devices.
All the conduits of the electric cables and the air pipes are made of self-extinguishing PVC, in accordance with the law.
11. SAFETY AND ALARMS
The machine is equipped with push-buttons and limit switches to give alarm and stop when the belts tend to move out of the rollers (a malfunction of the belts trajectories control system).
As regards the safety, the machine is protected by grating panels and protecting structures wherever the operator runs the risk to hurt himself (EEC regulations) in case of a careless operation.
Process and Operation Principles
1a. PREDEWATERING DRUM
Completely made of SST AISI 304, it is installed to mix the sludge and the polymer solution, as well as to remove the water from the suspension resulting from the drum cloth filtering action. On diluted sludge, the belt press throughput can increase up to 60%.
1b. MOTORIZED MIXER (FOR SMALL FLOWRATES)
Completely made of carbon steel. It consists of a cylindrical tank and a stirrer capable to mix the sludge and the polymer solution completely.
In this way, a suspension of flocs which can quickly release the water onto the filtering belt is obtained. It is suitable for small flowrates of sludge.
1c. MOTORIZED MIXER (FOR BIG FLOWRATES)
Contrary to the previous one, this model is assembled out of the machine and the stirrer is driven by a geared variator. It is suitable for big flowrates of sludge.
Process and Operation Principles – ctd
5. CAKE BREAKAWAY
At the end of the process, when the two filtering belts move apart and wind around the traction rollers, the sludge layer tends to detach by itself; anyway, the action is completed by two scraping doctor blades (one for each roller).
2. SLUDGE DISTRIBUTION AND DRAINAGE BY GRAVITY
The sludge, which has been previously thickened in the predewatering drum (or the motorized mixer), is conveyed in a suitable area placed between the tensioning roller of the lower belt and the beginning of the drainage by gravity zone. This area has the function to distribute the sludge uniformly onto the belt whole width. To this purpose, at its outlet, it is equipped with a blade which can be adjusted in height and inclination. This blade levels the sludge carried ahead by the belt, which, being pressed, is uniformly distributed and starts draining by gravity.
4. PRESSING ZONE
The sludge is now gradually pressed while going forward and winding around rollers with decreasing diameters.
The main factors to obtain a high pressing efficiency are:
- a good permeability of the belt which must be chosen according to the type of sludge to be treated;
- high and increasing pressure while the sludge goes forward and winds around the rollers.
3. WEDGE ZONE
After the drainage by gravity, the sludge passes through a wedge zone where the pressure on the sludge layer increases slightly because of a series of seven idler and adjustable rollers placed both above and below the belts. This is useful to drain a fair quantity of water before the sludge reaches the proper pressing zone.
SAFETY AND ALARMS
Belt filter presses type “400”, manufactured in different models, are equipped with safety devices in accordance with the UE 89-392 regulations and following modifications 91-368, 93-44, 93-68.
Belt filter presses type “400” are manufactured in 3 different models