Description

Field of the invention

The invention refers to the field of heating systems. Even more specifically, the invention is adapted to provide a biomass combustion system which may be used in stoves, thermostoves, fireplaces and other heating apparatuses, which uses the bottom fuel feeding method, obtaining a self-cleaning effect.

Prior art

The pellet stove is a device similar to the wood stove, used for heating any type of environment, which uses pellets as solid fuel. It is considered an ecological product since wood processing waste is normally used to obtain pellets.

The structure is similar to a traditional stove and has a compartment or tank, usually with top loading, which contains the pellets to be burned. It can have a different capacity. Inside there is an infinite screw or auger (valve or other means of transport) which drags the pellets from the tank into the brazier where the fuel is burned thanks to the presence of an electrical resistance which, becoming incandescent during the start-up step, ignites the flame. The heat produced is diffused into the environment (through a heat transfer fluid which can be water or air) both by natural convection and by forced air with one or more fans which contribute to distributing the hot air in the rooms. In some models it is also possible to channel the hot air into small ducts and position one or more vents to channel the heat into other rooms. The most recent models are provided with a chronothermostat which allows you to program automatic on and off times, the speed of the fan for forced hot air and the desired temperature degrees. The type of pellet used can also affect the heat output of the stove. The fumes deriving from combustion are discharged through an external pipe. The piping must be made of material resistant to operating temperatures, acids and any condensation produced by combustion. The stove requires ordinary cleaning of the brazier and the ash pan (if present) to be carried out with variable frequency according to use in terms of operating times and set power and the type of pellets used. Cleaning must be done with an ash vacuum cleaner, cleaning the glass of the stove from ash residues requires a special product suitable for this glass; it also requires more thorough cleaning at least once a year, but even more often depending on the model and usage.

To date, in a market that is increasingly moving towards the exploitation of renewable sources and towards the energy efficiency of homes, there are many patent applications that have dealt with supplying heating systems with pellets, chips or similar sources, that are increasingly efficient.

An example is the subject of patent application KR20180014481 A to C.J. KIM. The invention relates to a stove which uses wood and pellets as a heat source. According to the invention, the wood and/or pellet stove comprises: a stove with a combustion chamber for oxidizing heat source materials and for generating thermal energy; and an ash pan for receiving the ash generated by the materials of the heat source which has entered a lower side of the combustion chamber; a feed unit comprising in turn: an inlet hopper communicating with the combustion chamber of the stove for feeding the heat source materials; an auxiliary pipe connected to the inlet hopper for feeding the heat source materials; a movable pipe communicating with the auxiliary pipe for moving the heat source materials to a combustion chamber network; and a main duct for receiving the movable duct and for communicating with the interior and exterior of the combustion chamber; and a height control means comprising: a handle formed near the feed unit for controlling a feed volume of heat source materials and for controlling a height with one end of the movable pipe, thereby setting and controlling correctly a combustion heating power and a combustion time; and a housing groove for accommodating the handle at one end of the main tube. As such, this invention is able to make the use of wood pellets in a wood burning stove very simple, to allow a user to operate the stove by inputting pellets or wood indiscriminately and to reduce costs, thus allowing each user to obtain the appropriate heating power for your needs.

Another example is the subject of patent application US5001993A to D.E. GRAMLOW. The invention relates to a stove for burning pellets and biomass grain. A free-standing thermostatically controlled stove provides positive draft combustion of pellets or cereal grains. The particulate biofuel is gravity fed from a hopper into a slower moving first auger conveyor which feeds a second faster moving conveyor which communicates with the lower side portion of a combustion container being transported to a combustion chamber. The combustion container has a vertically spaced air chamber which supplies combustion air and inlet holes to allow recirculation of the combustion chamber gases for secondary combustion. The combustion chamber discharges the flue gases via negative pressure. A programmable microprocessor adjusts operating parameters to provide distinguishable preprogrammed burn cycles for maximum efficiency with only two operator controls for off/on and thermostat controlled operation.

The invention object of the present patent aims to exploit the pellet supply method known as the bottom fuel feeding system, in which the fuel is brought into the combustion chamber from below. Other patents to date have dealt with this particular feeding method, and an example is the object of W. ZHUIANG's patent application CN201875688U. The invention provides a pot type bottom fuel feeding biomass burner. The burner comprises a feeding device, an air supply device, a combustion chamber plate and a stirrer, wherein an edge above the combustion chamber plate is shaped to form a ventilation band of a certain width and is formed by a plurality of vents. The stirrer is located in the center of the plate and is located at a supply port. An annular band combustion mode is induced in the burner, so that the burner is not limited by size, thus being able to be applied to large, medium and small size boilers. The burner has simple and intuitive controls, has optimal energy use and is safe and reliable.

The inventions described up to now by way of a purely non-exhaustive example are to be considered representative of the current scenario regarding the field of the invention.

The object of the present invention is to provide a biomass combustion system which can be used in stoves, thermo-stoves, fireplaces and other heating devices, suitable for exploiting the bottom fuel feeding method, and for allowing the use of various types of fuel including pellets, shells, peanuts and chips.

Even more advantageously, the system presented herein is supplied with various modules which can be implemented, according to the needs of the end user, to take advantage of various optional functions.

Description of the invention

According to the present invention, a system for biomass combustion with a bottom fuel feeding method is provided which can be used for the construction of stoves, thermo-stoves and other heating devices, adapted to allow the indistinct use of various types of fuel including pellets, shells, peanuts and chips, and such as to require very limited maintenance by virtue of the self-cleaning effect guaranteed by the bottom fuel feeding method.

The system is made up of some modular elements in order to guarantee the indistinct use of any biomass fuel. The system is made up of some fundamental parts such as the combustion chamber, the hopper into which the fuel is inserted, a fume and air extraction system inside the combustion chamber itself. The fuel arrives from the hopper in a first module which is made up of a dosing screw, this has a continuous helix and has the function of dosing the fuel in a homogeneous way. Directly below the dosing screw is a rotary valve module which may also function as a dosing or safety flame arrester. Furthermore, the dosing is done in such a way that the rear part of the feeding screw is empty to avoid overheating and backfiring. The rotary valve module, as well as the other modules in the system, may be fitted or removed according to the final function of the system. This valve is able to dose the fuel. The rotary valve is connected to drive gear wheels driven by a motor. The motor and the gear wheels then turn a helicoid which, having an angled notch, allows the excess fuel to be chopped up once the rotary valve sector has been filled. The angled notch of the helicoid has a calibrated inclination so as to guarantee a mechanical cutting action within a desired range of force. The transmission wheels also have a reduction ratio such as to guarantee a homogeneous and continuous supply of fuel to the combustion chamber, avoiding overheating of the same.

The fuel thus reaches a feed screw which has the function of bringing it into the combustion chamber. The feed screw is made with two symmetrical coaxial spiral sections whose rotation along a horizontal axis allows the fuel to move in a vertical direction, upwards to be able to reach the combustion chamber. The feed screw is able to rotate as it is supported by two support bearings which mount a protective gasket adhering to the axis of the inlet auger itself, such as to protect them from ash, dust and other fragments of material that can affect their correct functioning. The protective gasket of said support bearings is therefore made of an elastic material so as to adhere perfectly to the axis of the feed screw and which is resistant to high temperatures, such as for example glass-ceramic, ceramic fiber and the like. The feed screw thus pushes the fuel towards the combustion chamber through the center of a brazier plate. The brazier plate has some holes through which the air taken from a special air box is introduced. The holes in the brazier plate are made in such a way as to guarantee an optimal intake of air into the brazier, being made in a horizontal direction in the lower part and following an increasingly inclined direction towards the vertical in the upper part. The plate also has one or more cavities to allow the housing of one or more spark plugs which have the task of triggering combustion.

An additional module that the system can fit is an extendable post-combustion module. This module can be mounted on the brazier plate or be an integral part of it, increases its height and provides a greater air intake for the post-combustion of harmful gases, significantly reducing the environmental impact of the combustion itself. A blower module can also be mounted upstream of the combustion chamber in order to compensate for pressure drops along the ventilation ducts and to facilitate the work of the fume extraction system.

All the modular parts are obviously removable, in fact, if the system is to be used only for the combustion of pellets, the dosing screw module can be removed; in the same way, if the system is to be used only for the combustion of wood chips or another fuel that does not require further chopping, the rotary valve module can be removed, in this case the motor continues to power the transmission wheels guaranteeing the rotation of the dosing screw only.

The system is furthermore favorably arranged for the implementation of a resistance sensor adapted to determine the presence of an excessively hard element in the helicoid of the rotary valve. When an element of this type erroneously ends up inside the helicoid of the rotary valve, the sensor sends out a visual and/or acoustic signal and stops combustion to avoid overheating of the combustion system as well as wasting energy.

The advantages offered by the present invention are clear in the light of the above description and will be even clearer from the accompanying figures and the related detailed description.

Description of the figures

The invention will hereinafter be described in at least a preferred embodiment thereof by way of non-limiting example with the aid of the accompanying figures, in which:

- FIGURE 1 shows two perspective views and a detail of the biomass combustion system with bottom fuel feeding method 100;

- FIGURE 2 shows a perspective view and two detail views of components of said biomass combustion system with bottom fuel feeding method 100;

- FIGURE 3 shows a sectional perspective view of two examples of application of said biomass combustion system with bottom fuel feeding method 100 in a stove and a thermostove.

Detailed description of the invention

The present invention will now be described purely by way of non-limiting or binding example with the aid of the figures, which illustrate some embodiments relative to the present inventive concept.

With reference to FIG. 1 and FIG. 2, perspective views and details of the biomass combustion system with bottom fuel feeding method 100 according to the present invention are shown. FIG. 1 and 2, as in the following description, the embodiment of the present invention considered to be the best to date is illustrated.

Said biomass combustion system with bottom fuel feeding method 100 capable of allowing the use of biomass fuel 1 of various kinds such as pellets, shells, pits and/or chips comprises at least a combustion chamber 101, at least a hopper 102, at least an extraction system 103, a dosing screw 110, a rotary valve 120, transmission gearwheels 121, a motor 122, a helicoid 123 with an angled notch 124, a resistance sensor 125, at least a feed screw 130 with two coaxial spiral trunks 131, at least two support bearings 132 with at least a protective gasket 133, at least a plate for brazier 140 with holes 141, at least a spark plug 142, at least an extensible post-combustion module 143, at least an air box 150, at least a blower module 160.

Said combustion chamber 101 is where the combustion of said biomass fuel 1 takes place. Said hopper 102 is the element that houses said biomass fuel 1. Said extraction system 103, on the other hand, is adapted to suction the air into said combustion chamber 101, generating a depression. From said hopper 120, said dosing screw 110 causes said biomass fuel 1 to descend by gravity towards said rotary valve 120 which performs a chopping action of the fuel when its dimensions are greater than a suitably calibrated limit for correct operation of the system. Once shredded, said biomass fuel 1 is brought by gravity towards said feed screw 130 which is made with two symmetrical coaxial spiral trunks 131 whose rotation along a horizontal axis allows said biomass fuel 1 to move, at said plate for brazier 140 in an upward vertical direction to be able to reach said combustion chamber 101. Said feed screw 130 rotates on said support bearings 132 (the detail of which in FIG. 1) which are coupled with said protective gasket 133 adhering to the axis of the feed screw 130, so as to protect the bearings themselves from ash, dust and other fragments of material which can affect their correct functioning.

The detail of said rotary valve 120 is shown in FIG. 2 in which it can be seen that it is connected to transmission gearwheels 121 suitable for being driven by said motor 122 and for turning said helicoid 123 which, having said angled notch 124, allows to carry out the chopping action of said biomass fuel 1. In the detail presented it is also possible to see said resistance sensor 125 which is adapted to determine the presence of an excessively hard element in said helicoid 123 to be shredded with said angled notch 124.

FIG. 2 again shows the detail of said brazier plate 140 where it is possible to observe said holes 141 through which said air box 150 introduces air thanks to the thrust of said blower module 160. The detail of said brazier plate 140 also shows the position of said spark plug 142 and of said extensible post-combustion module 143 which supplies an air supplement to the harmful gases resulting from combustion, obtaining a post-combustion which reduces their concentration.

Finally, with reference to FIG. 3, a sectional perspective view of two examples of application of said biomass combustion system with bottom fuel feeding method 100 in a stove and a thermo-stove is shown.

Said biomass combustion system with bottom fuel feeding 100 can in fact be used in order to heat a fluid which can be air (as in the example of the stove in FIG. 3 (A)) or water (FIG. 3 (B)). In the example shown in FIG. 3 (B) it can also be observed that only the module relating to said rotary valve 120 is present since said biomass fuel 1 is exclusively of the type to be shredded.

Finally, it is clear that modifications, additions or variants may be made to the invention described thus far which are apparent to those skilled in the art, without departing from the scope of protection that is provided by the appended claims.