Belt Filter Presses – Type 200
Dewatering with Belt Filter Presses Type «200»
Belt Filter Presses Description
Belt filter presses type «200» main characteristic is their simple and linear structure aimed to guarantee the highest reliability and operation expensiveness.
Our belt filter presses can be used to dewater any type of water suspensions: municipal and industrial sludges, as well as sludges coming from production processes (e.g. chemical, food industries and so on).
Belt filter presses type «200» are available in different models, according to the characteristics and quantity of sludge to be dewatered.
The main features of 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
- Mixer for Heavy Sludges
1. BEARING FRAME
It consists of carbon steel very thick rectangular shaped pipes, strenghtened and welded to form a stiffened and 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.
They are equipped with a stiff structure with hot-driven pins and flanges. They are sized for a linear tension of 8 kg/cm. The pressing, tensioning, transmission and trajectory correction rollers are coated by 8 mm. of rectified rubber layer.
The pre-compression rollers are made of Rilsan covered mild steel.
All the rollers are supported by ball bearings (hot-driven) which are suitably sized to guarantee a life of at least 75.000 hours.
4. FILTERING BELTS
They are made of polyester, continuous loop woven type or, at the customer’s choice, with SST clipper seam protected by epoxy resins.
5. BELTS TRACTION SYSTEM
It consists of an epicyclic motor variator connected to the traction rollers by means of toothed crowns and chains protected by carters.
6. BELTS SPEED VARIATION SYSTEM
Servocontrolled system to change the filter belts speed from the electric control panel.
7. BELTS GUIDE SYSTEM
Pneumatic type with proportional action probes to keep the belts continuously centered and one upon the other.
8. BELTS TENSIONING SYSTEM
It consists of pneumatic jacks with air springs which keep the belts tensioned.
9. 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 spray 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
10. WATER COLLECTING PANS
They are completely made of carbon steel and equipped with suitable slopes and outlet pipes.
The framework is equipped with suitable connections to place the “cantilevers” which are used for the continuous loop woven belts replacement. The “cantilevers” are supplied as optional.
12. ELECTRIC AND PNEUMATIC PLANTS ON BOARD OF THE MACHINE
Placed in two separate waterproof casings: the electric plant is complete with terminal strisps for all the power cables and signals; the pneumatic plant is complete with reduction filters and manometers for the belts adjustment and the intervention of the trajectory correction devices. All the conduits for the electric cables and the air pipes are made of self-extinguishing PVC, according to the law.
13. SAFETY AND ALARMS
The machine is equipped with push-buttons to give the alarm and the 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 (EEC regulations).
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 flow rates 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 “200”, 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.
CONTINUOUS LOOP WOVEN BELTS
The machine is designed to allow the assembly of continuous loop woven belts by means of the “cantilevers” which can be easily assembled onto the Belt Filter Press frame.
The continuous loop woven belts main feature is a longer life with respect to the clipper seam ones. This means a great save of time and costs in the machine maintenance.
Belt Filter Presses type «200» are manufactured in 4 models