Densified RDF production
With its experience in the densification/agglomeration of different materials using the agglomerators/densifiers PES (Promeco Extrusion System), Promeco developed plants to produce densified RDF in briquettes or pellets.
RDF densification brings several advantages:
- Increase in bulk density of the material, facilitating the storage and handling and reducing transport costs
- Reduction of residual moisture, thus increasing the calorific value of the material
- Homogenization of material properties, thus facilitating its use as fuel even on traditional plants (coal) while maintaining a good combustion control
- Substantial elimination of any organic residues, given the relatively high temperatures reached during the process; this which involves a reduction of odors and a relative disinfecting and sanitizing of the product, which subsequently can be stored for relatively long periods of time
The characteristics of incoming materials and outgoing product line are shown in the table below.
| Pellets | Thickened | |
|---|---|---|
| Raw material | MSW inorganic fraction, or other waste/scrap from productive activities | MSW inorganic fraction, or other waste/scrap from productive activities |
| Max humidity inputs | <15% H20 | <30% H20 |
| Hourly production | 1500-2000 kg / h depending on the quality of incoming material | 5000-6000 kg / h depending on the quality of incoming material |
| Product | briquettes of variable length, cylindric with a diameter of 32 mm, depending on the matrix and the material used | thickened shape and size vary depending on the material used |
| Bulk density | 900-1200 kg/m³ (depending on the quality of incoming material) | up to 500 kg/m³ (depending on the quality of incoming material) |
Process description
The two lines are substantially similar, and are illustrated by the following diagram.
The material supplied to the plant is stored in a separate area until processing. After the removal of any metal cables, the material is mechanically removed and fed to an elevating conveyor (Pos 1) sending the material in a eddy current separator for non ferrous metals (Pos 2). The flow is collected by another conveyor belt (Pos 3), and after a magnetic separation (Pos 4) in order to intercept the ferromagnetic fractions, if any, is sent to a ballistic separator (Pos 5) in order to separate the fractions are not suitable for production of CDR (inert, glass, etc..). The material is then collected on a belt conveyor feeding the single rotor shredder (Pos 6), which has a 30 mm grate in order to limit the size of the material sent to the next steps.
The shredded material is collected by a conveyor belt (Pos 7) followed by an elevating belt (Pos 8) feeding the hopper (Pos 9) dell'Extruder.
The Promeco Extruder System includes a hopper that feeds the material to the machine and a vibrating table (Pos 10) to optimize the dosing of the flow in the PES extrusion chamber (Pos 11).
Here the material is subjected to the high friction and pressure generated by the rotating screws, and then pushed through an extrusion matrix (Pos 12), which determines the shape and size of the product.
During the process heat and steam are generated. The latter, along with possible dust, is collected by an exhausted air suction system and, if needed, sent to an air treatment system. The hoods sucking the air to treat are located above the extruder feeding system and over the stabilization track.
From the matrix, the profile is pushed along a stabilization track to a cutting or size reduction system (Pos 14) that regulates the product according to the desired length specifications.
Eventually the product may move into a forced ventilation cooling system (Pos 15), where it will stay for a determined time before being stored in a specific area.
The control system (Pos 20) is equipped with PLC and inverter for the main engines, that require speed adjustment. The system is controlled by multiple control panels placed close to the different phases.
The plant can operate with 1 employees per shift, and in both automatic and manual mode.
