DESCRIPTION

Technical Field

The present invention relates to an apparatus for disintegrating biomasses, more particularly biomasses provided as bales.

The present invention also relates to a method of disintegrating biomasses, more particularly biomasses provided as bales.

The present invention finds particular application in plants for pre-treating biomasses intended for a biorefinery or a similar facility for producing biofuels.

Prior Art

Biorefineries are known where biofuels, including in particular bioethanol, are obtained from biomasses through a fermentation process.

More particularly, in order to avoid subtracting resources from the food sector, attempts have been made in recent times to obtain biofuels, and more particularly bioethanol, from cellulose present in non-food biomasses, such as wheat straw or rice straw and other agricultural wastes.

On the other hand, cellulose is a raw material that is of great interest not only for producing bioethanol, but more generally for the whole sector of the so-called "green chemistry".

Yet, at present, bioethanol production from cellulose appears to be too expensive and non-competitive from an economic viewpoint if compared with production from sugar-rich crops, such as sugar cane, maize, sunflower and soy.

The main difficulties in producing bioethanol from cellulose lie especially in the preliminary phases of pre-treatment of raw materials, rather than in cellulose fermentation process.

Indeed, in order to make cellulose available for the fermentation process and to expose it to the microorganisms responsible for such a fermentation process, it is necessary to separate cellulose from lignin. Such separation can take place according to different methods, e.g. through chemical-physical processes (e.g. "steam cracking"), through thermal processes (e.g. gasification), through enzymatic processes.

Whatever the separation method is, it is necessary that the raw materials are made homogenous and purified from possible contaminating elements, such as pebbles, stones, earth, metal pieces and so on. In currently known plants, non-food biomasses, such as wheat straw and/or rice straw, provided as bales are freed from straps and shredded.

The shredding step may possibly be accompanied, preferably preceded, by a step of removal of foreign bodies, as disclosed for instance in Patent Applications TO2014A000741 and TO2014A000742 in the name of the Applicant.

In order to make the shredding step (and, if provided for, the foreign body removal step) easier and effective, it is convenient that the biomasses, that usually are provided as bales, are freed from the straps and disintegrated,

Such disintegration of the biomasses allows spreading the biomasses and feeding them to the shredding apparatus as a substantially uniform layer. Moreover it allows exposing the foreign bodies possibly present in the biomass, making removal thereof easier.

Devices for disintegrating biomasses formed into bales, especially for disintegrating straw bales intended for livestock farms, are known in the art. Yet, such devices are designed for dealing with limited amounts of biomasses and they cannot be effectively applied or readapted for use in plants for pre-treating biomasses intended for biorefineries and similar facilities, in which it is desirable to achieve biomass throughputs of 10 - 30 tonnes/hr.

Therefore, it is the main object of the present invention to provide an apparatus for and a method of disintegrating biomasses, more particularly biomasses formed into bales, which can be effectively employed for disintegrating great amounts of biomasses and which is therefore fit for industrial applications in plants for treating biomasses intended for biorefineries and similar facilities.

The above and other objects are attained by the apparatus and the method as claimed in the appended claims.

Synthetic Disclosure of the invention

According to the invention, the apparatus for disintegrating biomasses includes two separate stations arranged in series, namely a first station for coarse disintegration of the biomasses and a second station, located downstream said first station, for fine disintegration of said biomasses.

The first station for coarse disintegration of the biomasses provides for milling the biomasses, usually provided as pressed bales, resulting in a reduction of the size of the biomass material and at the same time in a volume increase.

The second station for fine disintegration of the biomasses provides for refining the material coming from said first station in order to obtain a disintegrated material with the density desired for the subsequent treatment steps (removal of foreign bodies, shredding and so on).

Similarly, the method of disintegrating biomasses according to the invention includes two separate and successive steps, namely a first step of coarse disintegration of the biomasses and a subsequent second step of fine disintegration of said biomasses.

The first station for coarse disintegration in the apparatus according to the invention can be implemented by using a plurality of augers arranged parallel to and at a distance from one another, each auger including a respective rotating shaft equipped with a toothed worm screw.

The second station for fine disintegration in the apparatus according to the invention can be implemented by using a plurality of augers arranged parallel to and at a distance from one another, each auger including a respective rotating shaft equipped with a toothed worm screw.

In a preferred embodiment of the invention, the biomasses are fed through said first and second disintegration stations while being placed on a plane (such as the plane of a conveyor belt) and the rotating shafts of the augers in said first and second disintegration stations are arranged along a direction which is substantially perpendicular to said feeding plane.

In an embodiment of the invention, each disintegration station is provided with a common driving device driving the rotating shafts of all augers.

In an alternative embodiment of the invention, the rotating shaft of each auger in each disintegration station includes a separate driving device.

In a preferred embodiment of the invention, the rotating shafts of the augers in said first and/or said second disintegration stations are so driven that their direction of rotation can be inverted.

Preferably, the rotating shafts of the augers in a same station rotate in the same direction of rotation, and inversion of the direction of rotation takes place simultaneously for all rotating shafts in the same station.

Advantageously, the inversion period can be determined depending on one or more parameters of the biomasses to be treated, such as the material said biomasses are composed of, the throughput or the advancing speed of the biomasses and so on.

Brief Description of the Figures

Further features and advantages of the invention will become more apparent from the following detailed description of a preferred embodiment of the invention itself, given by way of non-limiting example with reference to the accompanying Fig. 1, which is a perspective view schematically showing an apparatus for disintegrating biomasses according to the invention.

Description of a Preferred Embodiment of the Invention

A preferred embodiment of the invention will be described in detail hereinafter.

Such an embodiment is not to be intended as limiting the scope of protection of the present invention.

More particularly, even though hereinafter reference will be made in particular to disintegration of wheat and/or rice straw provided as pressed bales, the invention could be equally applied to biomasses of different nature and/or provided in different forms.

Fig. 1 schematically shows an exemplary apparatus 1 for disintegrating biomasses according to the invention. Said apparatus 1 for disintegrating biomasses includes a support structure mounted on support feet 3 and having a bottom wall 5 and side walls 7.

Preferably the support structure is wholly shielded, in order to retain powders generated during biomass disintegration, but in Fig. 1 it is shown without shield for the sake of clarity.

Inside the support structure, on bottom wall 5, a transport line 9 is provided, consisting of one or more conveyor belts 9a, 9b.

According to the invention a first disintegration station 11 and, downstream said first disintegration station 11 in the advancing direction of transport line 9, a second, distinct and separate disintegration station 21 are arranged along transport line 9.

More particularly, the first disintegration station 11 performs a coarse disintegration of biomasses fed on transport line 9, whereas the second disintegration station 21 performs a subsequent fine disintegration of said biomasses.

For instance, in case the biomasses consist of wheat straw and/or rice straw formed into pressed bales, the first disintegration station 11 mills the biomasses, thereby reducing their size, whereas the second disintegration station 21 refines the milled material leaving said first station 11 in order to obtain the desired density, suitable for being effectively submitted to the subsequent treatment steps.

Preferably, in case of biomasses provided as bales, a strap removing station (not shown) will be provided upstream the first disintegration station 11 for removing the straps from the bales.

Advantageously, spraying nozzles (not shown) for spraying water in order to prevent the risk of explosions, as well as one or more fire-preventing spraying nozzles might be provided in correspondence of the disintegration area (that is, of the first and the second disintegration stations 11, 21).

The first disintegration station 11 includes one or more augers 13 mounted on a supporting portal 17, and each said auger includes a rotating shaft 13a carrying a worm screw 13b. Advantageously, worm screws 13b of augers 13 are equipped with teeth fastened thereto for instance by means of bolts.

Rotating shafts 13a of augers 13 are arranged parallel and aligned and are suitably spaced from one another. In the preferred embodiment shown in the Figure, rotating shafts 13a of the augers are arranged in a direction substantially perpendicular to the plane on which the biomasses are fed, i.e. to the plane of transport line 9.

In the embodiment shown in the Figure, rotating shaft 13a of each auger includes a separate driving device 15, consisting for instance of a motor and a corresponding reducing gear.

In the alternative, the first disintegration station 11 could be equipped with a single driving device and with a kinematic mechanism for transferring motion from said driving device to rotating shafts 13a of all augers 13.

Driving devices 15, or the single driving device and the associated kinematic mechanism, are arranged to make rotating shafts 13a of augers 13 rotate at the same or different speed(s), in the same or different direction(s) of rotation. Preferably, rotating shafts 13a of all augers 13 are driven so as to rotate in the same direction of rotation.

According to a preferred embodiment of the invention, driving devices 15, or the single driving device and the associated kinematic mechanism, are arranged to periodically invert the direction of rotation of rotating shafts 13a of augers 13. For instance, they are equipped with an inverter. Advantageously, the inversion period may be determined depending on one or more parameters of the biomasses to be treated, for instance depending on the material the biomasses are composed of.

In similar manner, the second disintegration station 21 includes one or more augers 23 mounted on a supporting portal 27, and each said auger includes a rotating shaft 23 a carrying a worm screw 23b. Advantageously, worm screws 23b of augers 23 are equipped with teeth fastened thereto, for instance by means of bolts.

Rotating shafts 23a of augers 23 are arranged parallel and aligned and are suitably spaced from one another. More particularly, depending on the cases, the spacing between rotating shafts 23a of two adjacent augers 23 may be chosen so that the respective toothed worm screws 23b partially intersect or may be chosen so that said toothed worm screws 23b do not intersect.

In the preferred embodiment shown in the Figure, rotating shafts 23a of the augers are arranged along a direction substantially perpendicular to the plane on which the biomasses are fed, i.e. to the plane of transport line 9.

Rotating shaft 23a of each auger 23 may include a single driving device (not shown) and an associated kinematic mechanism (not shown) for transferring motion from said driving device to rotating shafts 23a of all augers 23. In the alternative, the second disintegration station 21 might be equipped with a separate driving device for each auger 23.

Said single driving device and the associated kinematic mechanism, or said separate driving devices, are arranged to make rotating shafts 23a of augers 23 rotate at the same or different speed(s), in the same or different direction(s) of rotation. Preferably, rotating shafts 23a of all augers 23 are driven so as to rotate in the same direction of rotation.

Like in the case of the first disintegration station 11, the single driving device and the associated kinematic mechanism, or said separate driving devices, of the second disintegration station 21 are arranged to periodically invert the direction of rotation of rotating shafts 23a of augers 23. More particularly, they may be equipped with an inverter. Also in this case, the inversion period might be advantageously determined depending on one or more parameters of the biomasses to be treated, for instance depending on the material the biomasses are composed of.

Thanks to the provision of the first disintegration station 11 upstream the second disintegration station 21, the material entering said second disintegration station 21 is already coarsely disintegrated, and this enables making augers 23 of said second disintegration station 21 rotate at high speed with a reduced electrical power consumption.

Moreover, thanks to the provision of two separate, serially arranged disintegration stations, it is possible to deal with high biomass throughputs, in the range 10 to 30 tonnes/hr and preferably 20 to 30 tonnes/hr.

Always thanks to the provision of two separate and serially arranged disintegration stations, it is possible to attain an effective disintegration of the biomasses being treated. For instance, in case of wheat straw and/or rice straw provided as pressed bales, it is possible to pass from an average particle size of 200 to 1000 mm before disintegration to an average particle size of 20 to 50 mm after disintegration.

In view of the above description, the skilled in the art will readily appreciate that the method according to the invention will include:

- a first step of coarse disintegration of the biomasses;

- a second step of fine disintegration of the biomasses, following said first step of coarse disintegration.

Preferably, each said step will be carried out by using a plurality of augers, which are arranged parallel and aligned and at a suitable distance from one another, each auger comprising a rotating shaft and a toothed worm screw carried by said rotating shaft.

More preferably, each said step will be carried out by using a plurality of augers arranged along a direction which is substantially perpendicular to the plane on which said biomasses are fed.

In the case of such an implementation, in the method according to the invention it will be possible to control and adjust, either individually or collectively, the rotation speed and the direction of rotation of the rotating shafts of the augers. More particularly, in the method according to the invention it will be possible to periodically invert the direction of rotation of the rotating shafts of said augers.

From the above description, it is clear that the apparatus and the method according to the invention allow attaining the objects set above.

Indeed, thanks to the two-step disintegration performed according to the invention, it is possible to deal with high biomass throughputs, while keeping the electrical power consumption limited and supplying at the output an effectively disintegrated product.

Moreover, it is clear that the above description relating to the preferred embodiment has been given only by way of example and that several changes and modifications can be made based upon the common knowledge of the skilled in the art, without thereby departing from the scope of protection as defined by the following claims.

More particularly, even if reference has been made hereinbefore to the pre-treatment of pressed wheat straw and/or rice straw formed into pressed bales, clearly the invention could be applied as well to biomasses of different kinds, both food and non-food biomasses.

Moreover, even if reference has been made hereinbefore to biomasses intended for biorefineries for producing biofuels such as bioethanol, it is apparent that the invention could be applied in other fields as well.