FIELD OF THE INVENTION

The present invention concerns a low-emission heating apparatus that uses the well-known process of pyrolysis, also called cracking, or gasification, of a biomass, for example pellets or other materials derived from wood, to produce heat. The heating apparatus can be applied in the field of heating spaces, for example domestic or industrial, of public premises, or ones open to the public, but also in the field of boilers to produce domestic water and/or to be used in heating systems.

BACKGROUND OF THE INVENTION

Heating apparatuses are known, commonly called stoves, which use biomass in an inconsistent form for fuel, for example formed by chips, pellets or suchlike, in which combustion occurs thanks to the presence of a comburent, usually consisting of the oxygen contained in the ambient air, which is supplied as primary and secondary air. The primary air is made to enter a brazier to fuel the combustion of the biomass after the latter has first been ignited.

When operating normally, pyrolysis occurs during combustion, that is, the physical and chemical decomposition process of the combustible biomass, caused by it being heated to temperatures between about 300°C and about 600°C.

As is known, pyrolysis decomposes biomass into two parts: one gaseous and one solid. The gaseous part consists of a flammable mixture of gases, such as mainly carbon monoxide, hydrogen and methane, and a condensable compound, known to persons of skill in the art by the acronym TAR, while the solid part substantially consists of coal, known also by the term CHAR.

The mixture of gases derived from pyrolysis, which in this field is called “syngas”, is ignited by ignition, and with the introduction of secondary air completes the combustion of the biomass, generating heat and a flame.

Known stoves, which are based on the pyrolysis process, have a brazier in which the biomass can be loaded, which can then be ignited. Primary air can be introduced into the brazier to create a so-called “flame cap” above the biomass.

When the stove is working, the heat of the combustion descends into the brazier in proximity to the still non-combusted biomass and causes the pyrolysis thereof. Then, to complete the combustion, secondary air is introduced into the brazier which ignites the combustible gases resulting from pyrolysis.

However, these known stoves have a series of disadvantages such as, for example, poor performance, poor versatility of use, difficult management of the power and speed of production of the combustible gases and discontinuous operation.

In fact, the combustion process occurs until the loaded biomass is completely consumed by the pyrolysis process. When this process ends, because the biomass is finished, it is necessary to reload more biomass into the brazier and then restart the process by means of a new ignition. It is therefore quite clear that these operations require the intervention of an operator.

In addition, the introduction into the brazier of ambient air, having an oxygen component of approximately 23.3% by weight, contributes to a high production of polluting gases. In fact, biomass also includes nitrogen, generally bound with the carbon and hydrogen atoms present in it, and which, as is known, binds with the oxygen of the ambient air introduced into the brazier, producing nitrogen oxides which are very polluting.

Document DE 3718022 Cl is also known, which describes a biomass-fueled boiler, which comprises a brazier to contain the biomass, having a plurality of lateral entry apertures through which a mixture of air and fumes enters to trigger the pyrolysis of the biomass. Moreover, the brazier also comprises an exit aperture from which the combustible gases produced by the pyrolysis of the biomass exit. In correspondence with the exit aperture there are also air injection apertures to trigger the combustion of the combustible gases in a combustion chamber disposed directly downstream of the exit aperture of the brazier. The boiler also comprises a conduit that connects the combustion chamber disposed directly downstream of the exit aperture of the brazier to a post-combustion chamber comprising another air injection aperture to trigger the post-combustion of the fumes deriving from the first combustion, which took place in the combustion chamber disposed directly downstream of the exit aperture of the brazier.

Furthermore, in the boiler described in document DE 3718022 Cl, the pyrolysis of the biomass is triggered by a mixture of air and fumes the oxygen content of which also induces the production of nitrogen oxides, which are very polluting. In fact, for this reason, the fumes from the combustion of the combustible gases produced by the pyrolysis of the biomass are conveyed to the post-combustion chamber to trigger a second combustion with the purpose of reducing the nitrogen oxides.

Lastly, the boiler described in document DE 3718022 Cl is fed in batches, that is, before inserting a new biomass into the brazier it is necessary to terminate the decomposition of the biomass already present inside and then to empty it, so it is particularly difficult to control and regulate the combustion.

There is therefore a need to provide a new and original heating apparatus that can overcome at least one, better all, the disadvantages of the state of the art.

One purpose of the present invention is to provide a heating apparatus that produces reduced pollutant emissions into the environment.

Another purpose of the present invention is to provide a heating apparatus that allows to regulate both the production speed of the combustible gases and also the calorific power generated.

Another purpose of the present invention is to provide a heating apparatus which also allows to obtain a continuous operation, that is, without interruptions and which, moreover, can be easily automated at least to allow automatic start up and switch off.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In accordance with the above purposes, a heating apparatus which overcomes the limits of the state of the art and eliminates the defects present therein, comprises: thermochemical decomposition means configured to receive a biomass which functions as fuel and a first comburent and suitable to thermochemically decompose the biomass and produce at least one combustible gas, and a combustion chamber configured to receive both a second comburent and also the at least one combustible gas and suitable to develop heat by means of a flame, fed by the at least one combustible gas and which produces fumes.

According to one aspect of the present invention, the heating apparatus also comprises both conveyor means interposed between the thermochemical decomposition means and the combustion chamber to convey the combustible gas to the combustion chamber, and also recirculation means to convey at least a first part of the fumes from the combustion chamber to the thermochemical decomposition means.

The first part of the fumes advantageously constitutes the first comburent.

According to another aspect of the present invention, the heating apparatus also comprises heat exchange means associated with the recirculation means and configured to heat the second comburent using the heat contained in the first comburent before the second comburent reaches the combustion chamber.

According to another aspect of the present invention, the thermochemical decomposition means comprise a brazier substantially closed with respect to the external environment and comprising a first entry aperture for the biomass to enter, a second entry aperture for the first comburent to enter and an exit aperture for the combustible gas to exit.

The combustion chamber also comprises an entry aperture to receive the second comburent from the external environment and the combustible gas and, according to another aspect of the present invention, the conveyor means comprise at least one conveyor compartment interposed between the exit aperture of the brazier and the entry aperture of the combustion chamber.

According to another aspect of the present invention, the recirculation means comprise at least one recirculation aperture made on the combustion chamber and at least one recirculation conduit communicating with the recirculation aperture and also with the second entry aperture of the brazier.

According to another aspect of the present invention, the combustion chamber also comprises at least one evacuation aperture communicating with a respective evacuation pipe, to evacuate a second part of the fumes into the external environment.

According to another aspect of the present invention, the heating apparatus also comprises a first fan disposed downstream of the at least one recirculation aperture and upstream of the second aperture of the brazier and configured to draw the first comburent from the combustion chamber and introduce it into the brazier. The heating apparatus also comprises a second fan disposed downstream of the evacuation aperture and configured to draw the second part of the fumes from the combustion chamber.

According to another aspect of the present invention, a heating method comprises the following steps:

- providing a brazier and introducing a biomass into the brazier;

- providing a combustion chamber and drawing a first comburent from the combustion chamber;

- introducing the first comburent into the brazier in order to thermochemically decompose the biomass and produce a combustible gas;

- conveying the combustible gas into the combustion chamber.

According to another aspect of the present invention, the method also provides to draw a second comburent from the external environment and convey the latter into the combustion chamber in order to ignite the combustible gases, developing heat and fumes, and to draw at least a second part of the fumes from the combustion chamber and evacuate the second part of the fumes into the external environment.

According to another aspect of the present invention, the method also provides to heat the second comburent by means of an exchange of heat between the latter and the first comburent before the second comburent enters the combustion chamber.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a schematic block representation of a heating apparatus according to the present invention in accordance with a first embodiment;

- fig. 2 is a schematic block representation of a heating apparatus according to the present invention in accordance with a second embodiment;

- fig. 3 is a schematic block representation of a heating apparatus according to the present invention in accordance with a third embodiment;

- fig. 4 is a schematic block representation of a heating apparatus according to the present invention in accordance with a fourth embodiment;

- fig. 5 is a schematic block representation of a heating apparatus according to the present invention in accordance with a variant of the third embodiment;

- fig. 6 is a schematic block representation of a heating apparatus according to the present invention in accordance with a variant of the fourth embodiment;

- fig. 7 is a section lateral view of the heating apparatus of fig. 1 ;

- fig. 8 is a section along the line VIII- VIII of fig. 7;

- fig. 9 is a three-dimensional view of the heating apparatus of fig. 1 , taken from the rear;

- fig. 10 is a three-dimensional view similar to that of fig. 9, but partly exploded;

- fig. 11 is a block electrical diagram of a control circuit of the heating apparatus of fig. 1.

We must clarify that in the present description and in the claims the term vertical, with its declinations, has the sole function of better illustrating the present invention with reference to the drawings and must not be in any way used to limit the scope of the present invention itself, or the field of protection defined by the attached claims. For example, by the term vertical we mean an axis or a plane that can be either perpendicular to the line of the horizon, or inclined, even by several degrees, for example up to 20°, with respect to the latter.

Furthermore, the people of skill in the art will recognize that certain sizes or characteristics in the drawings may have been enlarged, deformed, or shown in an unconventional or non-proportional way in order to provide a version of the present invention that is easier to understand. When sizes and/or values are specified in the following description, the sizes and/or values are provided for illustrative purposes only and must not be construed as limiting the scope of protection of the present invention, unless such sizes and/or values are present in the attached claims.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications.

DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

With reference to fig. 1, a heating apparatus 10 according to the present invention is of the pyrolysis type and, in accordance with a first embodiment, comprises thermochemical decomposition means Ml configured to receive a biomass C which functions as fuel and a first comburent FI, as will be explained below.

The thermochemical decomposition means Ml are suitable to thermally decompose the biomass C and produce, by means of pyrolysis, combustible gases S, for example consisting mainly of methane, hydrogen, carbon monoxide.

The heating apparatus 10 also comprises a combustion chamber 20 configured to receive both a second comburent A, different from the first comburent FI, and also the combustible gases S. The combustion chamber 20 is suitable to develop heat by means of a flame, fed by the combustible gases S and which produces fumes F, as will be explained below.

Furthermore, the heating apparatus 10, in accordance with one aspect of the present invention, comprises both conveyor means M2 interposed between the thermochemical decomposition means Ml and the combustion chamber 20 to convey the combustible gases S toward the latter, and also recirculation means M3 to convey at least a first part FI of the fumes F, which constitutes the first comburent, from the combustion chamber 20 to the thermochemical decomposition means Ml .

Furthermore, the heating apparatus 10 comprises heat exchange means M4, associated with the recirculation means M3 and configured to heat the second comburent A, using the heat contained in the first comburent FI before the second comburent A reaches the combustion chamber.

Hereafter, with reference to figs. 1 and from 7 to 11, the first embodiment of the heating apparatus 10 is described in more detail.

The thermochemical decomposition means Ml comprise a brazier 11 substantially closed with respect to the external environment and delimited by four lateral walls 12 and one upper wall 13. Furthermore, the brazier 11 is delimited at the bottom by a metal plate 14 provided with at least one exit aperture 15. The exit aperture 15 of the brazier 11 is also configured to allow the combustible gases S to exit and the burnt and/or thermochemically decomposed biomass C to be discharged from the brazier 11.

The metal plate 14 can be selectively removable or openable, in any known way, to allow access to the brazier 11 from below, for example to carry out maintenance or cleaning thereof.

Furthermore, the brazier 11 has an entry aperture 16 for the biomass C to be introduced, comprising, for example, inconsistent wooden material such as chips, pellets or suchlike, and an entry aperture 18 from which the first comburent F 1 , which is of the aeriform type, can enter.

It should also be noted that the brazier 11 does not have any apertures that allow the comburent air to enter directly from the external environment.

The entry apertures 16 and 18 of the brazier 11 are preferably disposed in the upper part of the latter, that is, at a higher level than the one at which the exit aperture 15 is located. This configuration allows to introduce the biomass C and the first comburent FI from the top downward.

It should be noted that the reciprocal position of the first aperture 16 and of the second aperture 18 may vary compared to that shown in the drawings, so that, for example, one or both can be disposed laterally, or one at a different level from the other.

In an alternative embodiment, not shown in the drawings, the first aperture 16 of the brazier 11 can be disposed substantially level with the lower part thereof. In this configuration, the biomass C can be introduced into the brazier 11 from the bottom upward, or, alternatively, laterally, that is, in a substantially horizontal way. For example, the first aperture 16 can be disposed substantially level with the metal plate 14, in order to introduce the biomass C directly above the latter.

Furthermore, inside the brazier 11 there is an ignition device 19, configured to selectively trigger the combustion of the biomass C, for example when the heating apparatus 10 is switched on.

In the embodiment shown here, the ignition device 19 comprises an electrical resistance disposed in a lower zone of a lateral wall 12, that is, close to the metal plate 14, for example in the same lateral wall 12 in which the first entry aperture 16 is made. The ignition device 19 can be sized so as to come into contact, during use, with the biomass C present in the brazier 11. Alternatively, the ignition device 19 can be configured to ignite the biomass C indirectly, that is, by heating the air in contact with the latter.

The combustion chamber 20 is substantially closed and is in fluidic communication with the brazier 11 by means of a conveyor compartment 21, which is preferably hermetically sealed. In particular, the conveyor compartment 21 is interposed between the lower part of the brazier 11 and the lower part of the combustion chamber 20. Alternatively, the conveyor compartment 21 can be replaced by one or more conduits.

We must clarify that the exit aperture 15 of the brazier 11 flows directly into the conveyor means M2. In particular, in the example provided here, the exit aperture 15 of the brazier 11 flows directly into the conveyor compartment 21, which defines the conveyor means M2.

We must also clarify that, in accordance with one aspect of the present invention, the brazier 11 and the combustion chamber 20 are autonomous, separated from each other and connected in a fluidic way by means of the conveyor compartment 21.

According to one aspect of the invention, the combustion chamber 20 is fluidically connected with the comburent entry aperture 18 of the brazier 11.

In particular, in the embodiment described here, the combustion chamber 20 is delimited by two lateral walls 22, by one upper wall 23, by one front wall 24, for example able to be opened, which functions as closing door, by one rear wall 25 and by one lower wall 26.

One or more recirculation apertures 27 are made on an upper part of the rear wall 25, each communicating with an upper end of a respective recirculation conduit 28, which is outside the combustion chamber 20 and has a lower end which, by means of a manifold 43, is connected to the intake of a first fan 29, the delivery of which is fluidically connected to the second entry aperture 18 of the brazier 11.

In addition or alternatively, the recirculation apertures 27 can be made in other walls of the combustion chamber 20.

Preferably, the recirculation conduits 28 are substantially parallel to each other and to the rear wall 25, and also detached from each other and from the rear wall 25, for example by between 1 and 3 cm.

The heating apparatus 10 also comprises a containing body 32, substantially box-shaped, on which two feed apertures 31 are made, which are in communication with the outside and through which the second comburent A can enter.

The containing body 32 is attached on the external surface of the rear wall 25 of the combustion chamber 20 creating, in cooperation with the latter, a containing compartment V in which the recirculation conduits 28 are disposed.

An entry aperture 33 is made in the lower wall 26 of the combustion chamber 20, substantially in a central zone thereof, in said entry aperture 33 there being positioned a nozzle 30 having, in the example given here, a central conduit 34 disposed along a longitudinal axis X, substantially vertical, and a series of lateral through holes 35, which substantially lie on a substantially horizontal plane P disposed below the lower wall 26. The lateral holes 35 are in communication with the central conduit 34.

We must clarify that the conformation and disposition of the central conduit 34 and of the lateral holes 35 may differ, even considerably, compared to what is described here and represented in the attached drawings. For example, instead of the lateral holes 35, an aperture or a slot (not shown) of any suitable shape and size can be made.

The central conduit 34 is in communication with the conveyor compartment 21 and has the function of injecting the combustible gases S into the combustion chamber 20, while the lateral holes 35 have the function of conveying the second comburent A, coming from the containing compartment V. In particular, the second part V2 of the containing compartment V surrounds the portion of the nozzle 30 on which the lateral holes 35 are made, which are configured to receive the second comburent A coming from the second part V2 of the containing compartment V and to promote the mixing of the second comburent A with the combustible gases S in order to promote the combustion of the latter.

The feed apertures 31 are disposed below the lower ends of the recirculation conduits 28, that is, substantially level with the lower part of the combustion chamber 20. Furthermore, a dividing wall, or partition, 37 is disposed inside the containing body 32, substantially dividing the containing compartment V into two parts, that is, into a first part VI, in which the recirculation conduits 28 are disposed, and into a second part V2, which laps both the rear wall 25 and also the lower wall 26 of the combustion chamber 20.

The first part V 1 and the second part V2 of the containing compartment V are in communication with each other in correspondence with the upper part of the partition 37 which, preferably, is disposed in correspondence with the upper ends of the recirculation conduits 28, that is, where the latter are connected to the respective recirculation apertures 27.

Therefore, during use, the second comburent A enters from the feed apertures 31, passes through the first part VI of the containing compartment V and heats up in contact with the recirculation conduits 28, until it reaches the top of the dividing wall, or partition, 37. Then, the second comburent A enters the second part V2 of the containing compartment V from above and passes through it all, until it reaches the lateral holes 35 of the nozzle 30, lapping the rear wall 25 of the combustion chamber 20, heating up further.

It should be noted that, thanks to this conformation, the containing body 32, in cooperation with the recirculation conduits 28 and the walls 25 and 27 of the combustion chamber 20, constitutes a counter-current heat exchanger, which corresponds to the heat exchange means M4 as above.

Furthermore, on each of the lateral walls 22 (fig. 8) of the combustion chamber 20 there are evacuation apertures 36, to each of which a respective evacuation pipe 38 is connected, outside the combustion chamber 20 and substantially vertical.

Each evacuation pipe 38 is fluidically connected to an evacuation chamber 40, in turn connected to the intake of a second fan 39 (fig. 7), the delivery of which communicates with the outside of the apparatus 10.

The heating apparatus 10 can optionally also comprise an external containing structure 41, substantially in the shape of a parallelepiped and comprising a second compartment 42, inside of which there are disposed, with ample clearance, both the evacuation pipes 38 and also at least a part of the combustion chamber 20, of the conveyor compartment 21 and of the evacuation chamber 40. The external structure 41 has, in its lower part, an entry aperture 47, to which a third fan 45 is connected in order to selectively introduce ambient air R into the second compartment 42, and in its upper part an exit aperture 44 from which the same air R can exit in contact with the evacuation pipes 38.

The heating apparatus 10 also comprises an injection device 46, of any type known per se, to introduce the biomass C into the brazier 11 in a controlled way, whether intermittently or continuously.

In the example provided here, the injection device 46 comprises a container 48, substantially in the shape of a hopper, containing a biomass C load and an associated metering device 49, of a type known per se, having an exit connected to the entry aperture 16 of the brazier 11 and configured to meter the quantity of biomass C introduced into the brazier 11 in a way that is selective and proportional to certain electrical signals, under the control of a control unit 50 (fig. 11), as will be described in detail below.

Therefore, the biomass C lies in an autonomous and separate environment with respect to the brazier 11, and it is introduced therein in a selective, automatic and substantially continuous way by the injection device 49.

The metering device 49 (fig. 7) is of the type which comprises a rotating element 51 provided with radial blades 52 and connected to an electric motor 53 (fig. 11) controlled by the control unit 50. With each rotation, even partial, of the rotating element 51 , a certain quantity of biomass C is introduced into the brazier 11, by means of an introduction conduit 54.

It is therefore clear that the quantity of biomass C introduced into the brazier 11, in a given unit of time, is a function of the rotation speed of the rotating element 51 (fig. 7).

In other embodiments, not shown in the drawings, the metering device 49 can comprise an auger.

The injection device 46 allows to introduce the biomass C into the brazier 11 in an automatic, controlled and continuous way, so as to allow to adjust the flow rate of biomass C introduced into the brazier 11.

The heating apparatus 10 also comprises a sensor 58 (figs. 7 and 11), also of a type known per se and for example consisting of a lambda probe, which is suitable to detect the quantity of oxygen present in the environment which surrounds it. In the example provided here, the sensor 58 is positioned downstream of the combustion chamber 20 and in particular inside the evacuation chamber 40.

In other embodiments, the sensor 58 can be disposed inside the evacuation pipes 38 and/or inside the recirculation conduits 28 in order to detect the quantity of oxygen in the fumes F.

The sensor 58 is connected to the control unit 50 and it is configured to transmit to the latter an electrical signal SP proportional to the quantity of oxygen detected by it.

The control unit 50 is configured to also control the first fan 29 and the second fan 39, and possibly also the third fan 45.

In addition, the control unit 50 is configured to command the operation of the recirculation means M2 in order to adjust the flow rate of the first comburent FI, and to command the operation of the injection device 46 in order to control the flow rate of the biomass C introduced into the brazier 11.

In particular, the control unit 50 can control the rotation speed of the first fan 29 and consequently the flow rate of the first comburent FI, the rotation speed of the second fan 39 and consequently the flow rate of the second comburent A, and the rotation speed of the rotating element 51 of the metering device 49 and consequently the flow rate of biomass C into the brazier 11.

In other embodiments of the present invention, not shown in the drawings, an element made of thermoconductive material, for example ceramic, can be attached at least to the lateral walls 22 of the combustion chamber 20, in order to increase the thermal inertia.

In other embodiments of the present invention, not shown in the drawings, one or more pipes for circulating water can be associated with at least the lateral walls 22 of the combustion chamber 20.

With reference to fig. 2, in a second embodiment, a heating apparatus 100 according to the present invention can comprise all the components of the heating apparatus 10 described above, except the heat exchange means M4. In this embodiment, the heating apparatus 100 can also comprise a second ignition device, not shown in the drawings, disposed substantially in proximity to the nozzle 30 and configured to trigger the combustion of the combustible gases S. With reference to fig. 3, in a third embodiment, a heating apparatus 200 according to the present invention can comprise all the components of the heating apparatus 10 described above, except the heat exchange means M4 and the first fan 29.

Also in this embodiment, the heating apparatus 200 can also comprise a second ignition device, not shown in the drawings, disposed substantially in proximity to the nozzle 30 and configured to trigger the combustion of the combustible gases S.

With reference to fig. 4, in a fourth embodiment, a heating apparatus 300 according to the present invention can comprise all the components of the heating apparatus 10 described above, except the first fan 29.

It should be noted that, in the third and fourth embodiments, the heating apparatus 200, 300 only comprises the second fan 39, connected to the combustion chamber 20 in order to draw the fumes F generated inside the latter.

Furthermore, in the third and fourth embodiments, a conduit connected downstream of the second fan 39 can be connected to the brazier 11 in order to function as a recirculation mean M3 to convey a first part FI of the fumes F, which functions as a first comburent.

In other possible variants of the third and fourth embodiments, the conduit described above, which functions as a recirculation mean M3, can be disposed upstream of the second fan 39 and downstream of the combustion chamber 20 (figs. 5 and 6).

The operation of the heating apparatus 10 described heretofore, which corresponds to the method according to the present invention, comprises the following steps.

When the heating apparatus 10 is started, the control unit 50 drives the injection device 46 to introduce a certain quantity of biomass C into the brazier 11 and the ignition device 19 to ignite the biomass C in the brazier 11.

Furthermore, the control unit 50 drives the first fan 29 which takes a first comburent F 1 from the combustion chamber 20 and introduces it into the brazier 11. We wish to clarify that, at start-up, substantially ambient air is present inside the combustion chamber 20.

The control unit 50 also drives the second fan 39 which draws the second comburent A from the external environment, through the feed apertures 31 , and introduces the latter into the combustion chamber 20 through its entry aperture 33.

In this start-up step, the combustion between the biomass C inside the brazier 11 and the first comburent FI, which hereafter will be referred to as start-up combustion, is substantially of the reverse flame type, also called downdraft by the people of skill in the art, that is, by introducing the first comburent FI into the brazier 11 from the top downward, in such a way that it passes, in this direction, through the biomass C disposed, during use, in the brazier 11 and consequently generating a flame which is also directed from the top downward, and fumes.

The fumes produced by the start-up combustion are conveyed into the combustion chamber 20 by means of the conveyor compartment 21, thanks to the draw provided by the first fan 29 which, subsequently, re-introduces them into the brazier 11. Therefore, in this step, the first comburent FI consists of a first part of the start-up combustion fumes.

In particular, a first part FI of the start-up combustion fumes is drawn by the first fan 29 by means of the first recirculation apertures 27 and is re-introduced into the brazier 11 from its second aperture 18, functioning as first comburent FI, and a second part F2 of the start-up combustion fumes is drawn in by the second fan 39 by means of the evacuation apertures 36 and is expelled from the heating apparatus 10.

After a certain period of time, a steady state operating condition is reached, in which the first comburent FI has a temperature and quantity of oxygen suitable to trigger the process of pyrolysis of the biomass C present in the brazier 11.

At this point, the first comburent FI introduced into the brazier 11 is suitable to thermochemically decompose the biomass C inside the brazier 11 and produce combustible gases S.

It should be noted that the thermochemical decomposition of the biomass C also substantially occurs in downdraft, that is, by introducing the first comburent FI into the brazier 11 from the top downward, in such a way that it passes, in this direction, through the biomass C which is disposed, during use, in the brazier 11. In this way, the combustible gases S produced by the thermochemical decomposition of the biomass C escape from the lower portion of the brazier 11. This configuration is advantageous in that it forces the combustible gases S to pass through the biomass C contained in the brazier 11 and this allows to separate their volatile components, producing combustible gases S with a reduced quantity of TAR.

Therefore, during steady state operation, it is no longer the fumes generated by the start-up combustion that exit from the exit aperture 15 of the brazier 11 , but the combustible gases S generated by the thermochemical decomposition of the biomass C.

The method then provides to introduce the combustible gases S into the combustion chamber 20 by means of the conveyor compartment 21, thanks to the draw of the first fan 29. In fact, we wish to clarify that, when operating at steady state, only the combustible gases S pass through the conveyor means M2. In particular, in the example given here, when operating at steady state, only the combustible gases S that are introduced into the combustion chamber 20 pass through the conveyor compartment 21

The method then provides to oxidize, or ignite, the combustible gases S by means of the second comburent A introduced into the combustion chamber 20, producing a flame, fumes F and developing heat.

Optionally, the method can provide to heat the second comburent A, using the heat contained in the first comburent FI before the second comburent A reaches the combustion chamber 20. This heat exchange is preferably carried out in countercurrent.

It should be noted that, in this case, the ignition of the oxidation, or combustion, or fire, of the combustible gases S in the combustion chamber 20 occurs only by means of the “meeting” between the latter and the second heated comburent A. This is very advantageous, since it does not require the presence and use of additional ignition devices.

As before, a first part FI of the fumes F generated, this time, by the combustion of the combustible gases S is drawn by the first fan 29 by means of the recirculation apertures 27 and is reintroduced into the brazier 11 from its comburent entry aperture 18, functioning as a first comburent FI, and a second part F2 of the fumes F is drawn by the second fan 39 by means of the evacuation apertures 36 and is expelled from the heating apparatus 10. At this point, the first part FI of the fumes F, re-introduced into the brazier 11, and which in fact functions as first comburent FI, has an oxygen component advantageously comprised between about 7% and about 12% by volume, which is smaller than that present in the ambient air. This is particularly advantageous since, by doing so, an anoxic environment is created in the brazier 11, that is, lacking in oxygen, which is present in a quantity sufficient to react mainly with the carbon present in the biomass C and generate the combustible gases.

Therefore, the production of polluting emissions such as, for example, nitrogen oxides, is significantly decreased since there is not a sufficient quantity of oxygen in the brazier 11 to bind with the nitrogen comprised in the biomass C.

Furthermore, when operating at steady state, the first part FI of the fumes F, the moment it enters the brazier 11 , has a temperature comprised between about 240°C and about 320°C, this is advantageous since at least part of the CO2 present therein is re-converted into CO, that is, carbon monoxide, which is combustible. Another advantage is that the water present in gaseous phase in the first part FI of the fumes F in the brazier 11 is converted into hydrogen, increasing the calorific value of the combustible gas S.

The control unit 50 can also control the injection device 46, the first fan 29 and the second fan 39 on the basis of the electrical signal received from the sensor 58. For example, the control unit 50 can modify the flow rate of the first comburent FI, of the second comburent A and/or of the biomass C in feedback, until the value detected by the sensor 58 reaches a predetermined target value. Optionally, the control unit 50 also drives the third fan 45 to generate a flow of ambient air R which passes into the second compartment 42 in order to exchange heat with the evacuation pipes 38, heating up. The heated ambient air R is then conveyed once again toward the external environment.

In fact, it should be noted that the injection device 46, the first fan 29 and the second fan 39 allow to manage the flow rate of the first comburent FI, of the second comburent A and/or of the biomass C in a coordinated way, so as to reduce the polluting emissions of the heating apparatus 10 and better manage the generation of heat thereby.

It is clear that modifications and/or additions of parts may be made to the heating apparatus 10 as described heretofore, without departing from the field and scope of the present invention as defined by the claims.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of heating apparatus 10, all coming within the scope of the present invention.

In the following claims, the sole purpose of the references in brackets is to facilitate reading and they must not be considered as restrictive factors with regard to the field of protection defined by the claims.