RECYCLING IN PRODUCTION OF EXTRUDED PRODUCTS FROM DRIED WASTE

RATIONALIZATION OF PRODUCTION BY ELIMINATING ANY FORM OF WASTE AND IMPROVING QUALITY

OF THE FINISHED PRODUCT

In a dry pet food or fish food production line, the first layer of a new production batch is discarded as it is too dry: this occurs because the product flows along the dryer which is not working at full capacity; this occurs independently of the type of dryer. In a line that produces about 10 tons/h, this amount never falls below 500 <1,000 kilos and the product is re-ground to be employed as a substandard raw material.

This operation results in a loss of production, a waste of electricity (grinding and extrusion) and thermal energy (drying) as well as an economic loss as the recycled product is downgraded for use in a normally cheaper formulation.

All these costs can be fully recovered by installing a storage buffer between the outlet of the dryer and the subsequent coating and flavoring line. The recovery in production cycle can be easily automated.

The buffer allows to store the first layer of the dried product and/or any other product that is not perfectly compliant (e.g. with density standards), in order to dilute it up to 15 <20% during the subsequent production line.

In case of a product that is too dry, the moisture contained in the kibble will migrate uniformly inside the final packaging. This non-compliant density is so diluted that it doesn’t cause any packaging problems and is not perceived by the animal.  
Storage and subsequent dosing for reintroduction are operations that require a hopper and a very special doser.
The kibble must in fact be kept warm enough for coating, but it is necessary to prevent condensation which causes it to aggregate and transform into a single unusable lump.

In order to reintroduce the product into production, it is necessary to employ a volumetric doser which ensures precision in managing the quantity of recycling in production and prevents the kibble to be ground during the dosing process.
CRISTIANO TORRE has developed a system which, thanks to its shape, materials and technical solutions, guarantees flawless functioning and perfect integration into the production process.

  • No risk of blockage due to aggregation inside the bin due to aggregation, even while maintaining a temperature high enough for subsequent fixing of fats and palatants during coating;

  • Sufficient ventilation to avoid formation of mold or mycotoxins during storage;

  • Great attention to accessibility for cleaning;

  • Compliance with food standards;

  • Dosing precision in the reintegration process.

FROM THE DRYER DISCHARGE

DECOMPRESSION HOPPER

FORCED VENTILATION

WEIGHING

DISCHARGE HOPPER

DOSING ROTARY VALVE

DOSING TOWARDS COATING FOR RECYCLING IN PRODUCTION

The hospital bin is entirely built in AISI 304 stainless steel.
Full penetration welds with smooth and polished internal/external surface finish 
Useful capacity is calculated at the request of the user but we recommend a minimum capacity of 4,000 liters.
Weighing is always recommended for batch traceability.

CYLINDRICAL DRUM

Monolithic structure without flanges so as to avoid retention of small amounts of dust and consequent formation of larvae.
The cover lid is connected to the cylindrical part by a radius that prevents retention and facilitates cleaning.
The whole frame is insulated with high density rockwool: the outer jacket is fully welded.

An access door with anti-fall protection as well as a blade level gauge for the full bin signalling are installed on the door. The product inlet point and the suction probe on the lid ensure flexible connection to allow weighing. The flexible connections are flat flexible plates to guarantee greater insulation and absence of product retention.
 

DECOMPRESSION HOPPER

Built in a pyramidal shape with ALL rounded corners to prevent dust retention and facilitate cleaning.
The hopper is equipped with a fan connection mounted on hinges and an internal ventilation air distribution system. On the hopper there are access doors for cleaning, which are closed by means of watertight hinged lids.
All accesses are protected by magnetically coded sensors to ensure safe use and maintenance.
2B internal finish and Scotch Brite fine external finish.
On the hopper there are supports for sample weights, used for the first calibration of the weighing system. Bolted hatches are provided on the 4 corners of the hopper to guarantee emergency access even when the tank is full.

WEIGHING

The whole system is placed on three standard compression load cells OIML R60 made of stainless steel, which provide an effective means of ensuring batch traceability and enabling the inspection of productive processes. Weighing precision is about +/- 2<5 Kg.

FORCED VENTILATION

The storage of a product which is partially humid and still hot in a closed environment inevitably leads to the release of moisture and to condensation; in the case of extruded cereals, it results in the formation of compact lumps and mycotoxins that are very dangerous for the health of the animal being fed.
TORRE company has developed a ventilation system that consists in creating an airstream passing homogeneously through the stored product, thereby removing the moisture released by the product itself without significantly cooling it and therefore avoiding any problems.
NO LUMP FORMATION.
NO POSSIBILITY OF CONTAMINATION BY MYCETES
PRODUCT MAINTAINED AT A SUITABLE TEMPERATURE FOR SUBSEQUENT GREASING AND SURFACE FLAVORING.
Before the air starts circulating inside the bin, it is filtered by a G4 filter mat.
The whole ventilation process can be completely automated with the introduction of appropriate probes for automatic monitoring of temperatures and relative humidity.

DISCHARGE HOPPER

The discharge hopper is the unit that conveys the kibble from the decompression hopper to the rotary dosing valve.
Its shape is designed to prevent the formation of lumps and facilitate product scrolling. All corners are rounded to eliminate any retention points.
This element is always equipped with a large access door for internal cleaning. A magnetically coded sensor signals the opening of the door.
2B is the standard internal surface finish, whereas Scotch Brite fine is the external surface finish. 
Upon request, the hopper can be supplied with polished internal surface, with roughness <0.4 µ

DOSING VALVE

In order to reintroduce into production the product stored in the bin, it is necessary to use a volumetric device that ensures dosing accuracy and makes it possible to vary the flow rate. Moreover, it is necessary to guarantee air tightness and ensure that kibble is not cut or ground during operation.
Taking its cue from equipment used in other sectors, CRISTIANO TORRE engineering has developed a volumetric dosing valve that perfectly fulfills the above mentioned task. Its shape is modified to prevent the rotor from shearing the kibble during rotation.
The valve is entirely made of stainless steel with an electro-polished surface finish and is available in 3 different sizes. With flow rates from 1600; 3,500 and 5,700 liters/h.
The inner part is perfectly accessible for cleaning by means of doors that are protected by magnetically coded sensors.

SUCTION UNIT

MANUAL  SUCTION CONTROL 

VALVE 

SUCTION FAN

HIGH 

PERFORMANCE CYCLONE

POWDER DISCHARGE

Storing extruded cereals, even if temporarily, leads to problems caused by the release of moisture; this occurs because the product is stored as soon as it exits the dryer and is therefore hot. It is a known-fact that a hot/humid environment is ideal for the development and proliferation of mycotoxins.
Product ventilation is an essential condition to remove the released moisture and maintain the wholesomeness of the stored product, without cooling it too much and therefore making it no longer suitable for the subsequent coating and flavoring treatment.
CRISTIANO TORRE has developed a mixed ventilation system: air is introduced from the base hopper and sucked in from the lid of the hospital bin. This guarantees perfect wholesomeness while maintaining an acceptable temperature for subsequent coating.
It is obvious that the airstream passing through the product carries a certain, albeit small, amount of dust and particles that cannot be discharged into the environment.
The pictures show a high efficiency cyclone air treatment system with continuous discharge of powders that can also be reused in extrusion.
It is possible to install an automatic bag filter in order to improve efficiency in the separation process; in this case, however, powders cannot be reused as they might be contaminated by the felt surface of the bag filter.