Characteristics, objects and advantages of the present invention will be better highlighted in the following description, with reference to the figures of the annexed drawings of embodiments given in not limiting way, wherein: Figure 1 is a schematic side view of the pre-crushing device, coupled with a conveyor/cooler of hot loose materials coming from the combustion chamber of a boiler or from vacuum-operated combustion chambers; Figure 2 is a view of the pre-crushing device in a single configuration; and Figure 3 is a view of the pre-crushing device in a multiple configuration.

It should be pointed out that the same reference numbers in the different Figures indicate the same or equivalent parts.

For conveying hot loose materials 11, like in particular heavy ashes and other combustion products belonging to boilers or burning furnaces 10, the conveyor/cooler according to the present invention uses a metal belt handling means 9 made of steel, inserted in a tight metal container 12.

The hot loose material 11, because of the force of gravity, leaves the boiler or the burning furnace 10 under which the metal conveyor belt 9 is placed, and the material 11 is laid down thereon forming a continuous bed travelling toward the discharge hopper 6, where the pre-crushing device 8 and the main crusher 7 are disposed.

Due to malfunctions of the boiler 10, it often happens that the ash blocks handled by the conveyor/cooler 9 can reach sizes such that they can not enter the main crusher 7. Because of the particular type of crusher 7, these blocks can not be reduced in size by the rotor 15, thus filling up the passage section 16 of the material and causing bunchings that can reach the discharge hopper 6 and consequently block the conveyor/cooler belt 9.

All the aforementioned problems are solved using the pre-crushing device 8

equipping the conveyor/cooler which is the object of the present invention.

In case of the material picked up from the conveyor belt 9 is made also of large lumps, the pre-crusher 8 is used to obtain a first size reduction of the material, avoiding that it is accumulated over the crusher 7. Thus, the object of the pre-crusher is to reduce the blocks of material to a sufficiently small size in order to be processed by the crusher 7 placed downstream.

The dust material with smaller grain size which falls from the metal belt 9 and deposits on the bottom of the container 12 is conveyed toward the discharge hopper 6 using a chain or metal grid scraper conveying means 17.

The speed of the conveyor belt 9 can be set according to the flow rate of the conveyed material 11 and the particular cooling requirements, in order to optimize the ash layer on the belt and thus the thermal exchange.

The cooling of the loose material 11, coming out from the combustion chamber at a temperature generally near to 800-900°C, takes place by the combined adduction of air flows and nebulized water jets inside the container 12.

Extemal air is sucked in the metal container 12 through the air intakes 18, due to the vacuum present in the combustion chamber 10 when the conveyor/cooling system is connected to vacuum-operated boilers 10.

A first air flow enters from the air intakes 18 and passes through the metal . container 12, advancing in the opposite direction with respeptto the movement of the hot material 11 conveyed by the metal belt 9 toward the main pre-crusher 8.

Concerning the second air flow sucked by the intakes 19, it flows on the bottom of the container 12 placed beneath the conveyor belt 9 toward the discharge hopper 6, where it is mixed with the first air flow coming from the air intakes 18.

The air quantity used for the two cooling flow parts entering from the valves 18 and 19 can be regulated by an adjusting mechanism 20 placed in the lower part of the metal container 12, near the discharge hopper 6.

The air absorbs the heat released by the hot material 11, thanks to the direct convective thermal exchange between the air and the material, the wall of the metal container 12, heated by radiance, and the metal belt 11, both in its forward and backward run, and also the heat released through the possible combustion of unburnt elements present in the conveyed material 11. It should be pointed out that, in this specific case, the metal conveyor belt 9 acts as a regenerative heat exchanger, absorbing the heat from the hot loose material 11 in the forward run and

dissipating it in the cooling air during the backward run.

The pre-crushing device 8 forming object of the present invention, placed upstream the crusher 7, allows to increase both the extraction and the cooling capability of the conveyor/cooler, thus increasing the thermal exchange surface.

The pre-crushing device 8 is designed in two different configurations, according to the available overall dimensions and the size of the blocks of material handled by the conveyor/cooler 9.

The first configuration, shown in Figure 2, includes a fixed steel frame 1, integral with a restraint hopper 6, and a mobile frame 2, free to slide on the fixed frame 1 by means of wheels 3 and activated by two pneumatic pistons 4. One or more steel bars 5, free to slide downward or upward too and able to crush blocks of hard material interposed in their stroke, are rigidly connected to the mobile frame 2.

The device is connected to the restraint hopper 6 of the material to be pre-crushed, connected in its turn to a crusher 7 which provides for a secondary crushing of the material with reduced size.

The second configuration, shown in Figure 3, provides for the installation of a pre-crusher integral with the restraint hopper 6, said pre-crusher comprising two connection cylinders 23 and two block-breaker bars 21 connected to pneumatic pistons 22, said pneumatic pistons 22 being connected in their turn with the connection cylinder 23. The block-breaker bars 21 are pushed downward or upward by the pneumatic cylinders 22. During their stroke, the block-breaker bars 21 are able to break any blocks of hard material which is eventually interposed between said block-breaker bars 21 and the rotor of the crusher 7. The activation of the two block- breaker bars 21 through the pneumatic pistons 22 can be performed simultaneously or alternatively.

In both configurations, the operating pressure of the pneumatic piston 4,22 is such that the block-breaker bars 21 compress the blocks of material against the rotor 15 until the breaking of said blocks is obtained.

In both configurations, the pre-crusher intervention logic can be: timed ; activated by a level feeler, such as a strap 14 hinged to the ceiling of the container 12, which checks a high level of material in the discharge hopper 6 acting as a storage volume; activated by a feeler, such as a roller balance 13, which checks the lack

of material downstream the crusher.

It is evident that several modifications, adjustments, additions, variations and replacements of elements with functionally equivalent others could be made to the embodiments described hereinbefore with illustrative and not limiting purpose, without falling outside the scope of protection defined in the appended claims.