IT202000003047A1 - GASIFIER STOVE - Google Patents

Description

Title

GAS STOVE S IFIC ATRICE TITLE: GASIFICATION STOVE

DESCRIPTION

The present invention relates to a gas stove.

Heating equipment, such as in particular stoves or boilers, which can be fed with solid fuel, for example wood or pellets, are known and widely used for heating air and / or water in living spaces.

Such known equipment usually comprises a containment structure in which are housed respectively a combustion chamber, an electric igniter, a storage tank for solid fuel, means for moving the fuel in the combustion chamber, a first pumping means, o fan, for moving the combustion air in thrust or suction, an air-to-air heat exchanger and a second pumping means, or fan, for the forced exchange of heat and conveyance of hot air in the domestic environment.

The combustion chamber usually houses a brazier inside which the fuel is deposited, through predisposed devices usually of the screw type.

The combustion air is taken from outside the containment structure thanks to the action of first pumping means, such as for example a first fan with blades which can be operated by an electrically powered motor, and conveyed through an inlet duct at the brazier; here, by means of suitable ignition means, combustion is triggered, which generates burnt gases at high temperatures.

The gases then pass through a heat exchanger, usually arranged downstream of the combustion chamber, to exchange heat with the containment structure of the apparatus, which in turn dissipates it, by radiation and / or natural convection, in the home installation environment.

Optionally, second pumping means, such as a second fan operated by an electric motor, can be provided to distribute heat to the external environment in a forced convective way, improving the thermal efficiency of the equipment and allowing to heat even environments other than the installation one. .

The combustion fumes are expelled from the apparatus through a suitable exhaust duct, thanks to the action of said first pumping means.

Command and control means, such as a suitably programmed electronic card, are generally provided to manage and coordinate the various electrical users provided in the apparatus to allow its correct operation.

In the case of pellet stoves for domestic use, a visible flame is generated through a glass and the heat is released into the environment thanks to the combination of radiation and forced and natural convection implemented in the structure of the stove.

An example of a gasifying stove? illustrated in the patent WO2019 / 033044A1 in which the quantity? of pellets present in the brazier? constant charge and allows a combustion regime of the gases generated at a predetermined power.

Furthermore, the presence of pellets in the brazier? entrusted to a manual filling or by gravity, without the possibility? to modify the power output rate of the equipment.

The drawbacks attributable to the known art consist substantially in the fact that pollutants are generated, which are typically a secondary product of biomass combustion; these pollutants occur in the form of harmful gases (including nitrogen oxides and their mixtures -Nox- and carbon monoxide -CO-) and in the form of fine dust (PM10 and PM2.5 particles) which represent a threat to health and to the environment.

In the state of the art the flame anchored on the wood mass? much more? large and spatially extended how much greater? the flow rate of pellets introduced into the unit? of time.

At the maximum power regime c '? a high supply of pellets and therefore a very spatially diffused flame, while at the minimum power regime there is a small flame distributed only in the vicinity? of the embers burning and almost totally hidden in the brazier.

A popular way to reduce emissions, specifically for particulate matter,? that of carrying out a staged combustion, in which first pyrolysis and gasification takes place, and then complete oxidation is carried out and therefore the visible flame in a position distant from the original biomass.

This artifice, combined with the use of a glass for viewing the flame, while reducing particulate emissions, generates a flame, visibly less attractive than the one anchored to the woody mass, of an aesthetically unsuitable shape and color.

Main task of what is the subject of this application? therefore that of solving the technical problems highlighted, eliminating the drawbacks of the cited known art and then devising a gasifying stove which allows to contain the generation of pollutants.

Within the scope of the above aim, another important object of the invention? that of realizing a gasifying stove that generates a flame of aesthetically appreciable shape and color, developed volumetrically so as to be in front of a flame inspection glass.

Another purpose? to create a gasif icing stove that allows to transmit the heat of combustion as much as possible possible towards the surrounding domestic environment by containing the dissipations through the exhaust gases that are conveyed outside through the chimney.

Not the least purpose? that of obtaining a gasifying stove which is structurally simple, which has low construction costs and which can be produced with the usual known plants.

The task and purposes mentioned, as well as? others that more? they will clearly appear later, are reached by a gasification stove (1) comprising a containment structure (2) in which a storage tank (3) for biomass fuel (4), a gasification crucible (6) connected to an expansion chamber (13) in turn connected to a combustion chamber (15), an air-to-air heat exchanger, which is characterized by the fact that said expansion chamber (13), above said crucible (6) of gasification and underlying said combustion chamber (15), has an intermediate section (18) having dimensions greater than those of a section (17), which enters from said gasification crucible (6).

Conveniently, the expansion chamber (13) has an intermediate section (18) having dimensions greater than those of the outlet section (16) to said combustion chamber (15).

Further characteristics and advantages of the invention will become clearer from the detailed description of a particular, but not exclusive, embodiment, illustrated by way of non-limiting example in the attached drawings, in which:

fig. 1 illustrates the gasifying stove in a three-quarter side schematic view;

fig. 2 shows the stove in a partially sectioned three-quarter side view;

fig. 3 shows the stove in a view taken according to the section plane III-III of Figure 1;

fig. 4 shows a detail of the crucible;

fig. 5 illustrates the stove in a schematic side view;

fig. 6 shows, in a schematic view and in a detail, the passage of a third combustion air;

fig. 7 illustrates, in a schematic view and in a detail, the passage of a second combustion air;

fig. 8 illustrates a different embodiment.

In the following embodiment examples, single characteristics, reported in relation to specific examples, may actually? be interchanged with other different characteristics, existing in other embodiments.

Furthermore ? to note that everything that in the course of the procedure for obtaining the patent turned out to be already? known, it is intended not to be claimed and subject to excerpt (disclaimer) from the claims.

With reference to the aforementioned figures yes? number 1 indicates a gasifying stove comprising a containment structure 2, of desired shape, in which a storage tank 3 for biomass fuel, such as pellets 4, is housed.

Tank 3? at the bottom connected to a pellet discharge duct 14 4.

Tank 3? further made airtight and therefore does not allow the entry of air from the pellet discharge duct 14 4.

There is a gasification crucible 6, substantially tubular in shape with a constant, circular or rectangular section.

The 6 gasification crucible? delimited, at the extremity? 7 from a first opening 8 suitable for allowing the passage of a first gasification air 9.

The air inlets all come from a portion of the duct called plenum, meaning by it a portion of ducting for the containment in a "calm" state of the air flow plus? or less high and whose main function? that of distributor or general manifold.

In general, the plenums are sized so that the speed? inside them is decidedly modest (lower) than the speed? of the input channel and of the output channel of the portion in question.

The first opening 8, through which the first gasification air 9 passes,? in connection with a first plenum 10a fed by a ducted inlet in turn fed by a general air supply duct 30.

The 6 gasification crucible? bordered at the end? 11, by a series of second openings 12 suitable for allowing the passage of a second combustion air 28, in correspondence with the passage towards an overlying gas expansion chamber 13, and also has a cross section of between (3,000 -7,000) sq.mm, preferably of 5,000 sq.mm.

Is it also foreseen, externally to said crucible 6 for gasification and in the vicinity? of said extremity? 11, a second plenum 10b, advantageously circumscribing said gasification crucible 6 externally, presenting a series of second openings 12, for the second combustion air 28, and therefore coinciding between the passage from the tubular section of the gasifier crucible 6 and the expansion chamber 13.

The expansion chamber 13? bounded at the end? lower by the series of second openings 12 suitable for allowing the passage of the second combustion air 28, in correspondence with the communication with the gasification crucible 6.

The expansion chamber 13 communicates at the top with a combustion chamber 15 and has an outlet section 16 and an inlet section 17.

The combustion chamber 15 has, in correspondence with said section 16, at the outlet, from said expansion chamber 13, third openings 16a suitable for allowing the passage of a third combustion air 31.

The expansion chamber 13 has a box-like conformation in which? a section 18 is defined, intermediate between said section 16, at the outlet towards said combustion chamber 15, and said section 17, at the inlet from said gasification crucible (6), which has dimensions greater than those of said section 16, at the outlet , and section 17, inlet, and comprised between (7,000-16.00) 0 sq.mm, preferably 13,000 sq.mm.

The inlet section 17 preferably has a smaller area than that of said intermediate section 18 and is comprised between (5,000-9,000) sq. Mm.

Externally to said outlet section 16, a third plenum 10c is also provided, advantageously circumscribing said expansion chamber 13 externally, having said series of third openings 16a for said third combustion air 31, coinciding between the passage from expansion chamber 13 and combustion chamber 15.

The area of the section of the combustion chamber 15 located above the section 17, leading from the expansion chamber 13 towards the combustion chamber 15,? greater than the area of section 17 itself and? comprised between (15,000-50,000) sq.mm, preferably 33,000 sq.mm.

Coinciding with the combustion chamber 15 c '? in addition a glass 19 which allows the flame to be viewed from the outside and allows the transmission of heat by radiation from the inside of the stove to the surrounding domestic environment.

The combustion chamber 15 therefore has, in correspondence with the outlet section 16 of said expansion chamber 13, said third openings 16a, substantially coinciding with the underlying outlet section 16, and a second upper opening 20 which connects it to the heat exchange and expulsion of exhaust gases.

The combustion chamber 15 has an additional inlet 23, for a fourth combustion air 24, obtained on one of its walls 25 and connected to a fourth plenum 10d, connected to the air supply duct 30.

There is an igniter 29 communicating with the inside of the gasification crucible 6.

Figures 1 to 7 refer to a geometry in which the fact that the intermediate section (18)? greater than both the inlet section 17 to the expansion chamber 13 and the outlet section 16 from the expansion chamber 13.

Figure 8 refers to the geometry in which the intermediate section 18? larger only than the section 17 inlet to the expansion chamber 13.

The combustion circuit? cos? composed of distinct chambers defined by the crucible 6 gasif icator, which extends from the extremity? bottom 7 for the inlet of the first gasification air 9, which passes through the first openings 8 to the inlet section of the second combustion air 28 which passes through the second openings 12, from the expansion chamber 13, which extends from the inlet of the second combustion air 28, through the second openings 12 to the outlet section 16, of the third air 31 through the third openings 16a, and from the combustion chamber 15 which extends beyond the outlet section 16, and it includes the additional inlet 23 for the fourth combustion air 24.

Thereafter, the combustion chamber 15 connects with the rest of the containment structure 2 to convey the gases resulting from combustion to a heat exchanger and then to the flue gas exhaust system through known types of smoke ducts.

There? which defines the start and end of the components? the position of the air inlets.

The fan predisposed to pumping can? operate in thrust, if mounted at the combustion air inlet (combustion system in positive pressure), or in suction, if mounted at the stove outlet, before the smoke duct (combustion system in negative pressure).

Operating in suction, the air enters from one or more? ducts that are connected to the various plenums; each plenum complies with the function of air distribution on all the passage openings provided.

Conveniently, but not necessarily, each plenum allows distribution over the entire perimeter of the area affected by the air inlet.

Appropriately, but not necessarily, two or more? plenum can be merged into a single larger plenum, leaving the air outlet points unchanged.

How does it work? the following: the pellet 4, contained in the sealed tank 3, is transported through the duct 14 inside the gasification crucible 6 using a worm screw, or a propeller, or a motorized screw with suitable motorized means.

The pellet 4 falls into the gasification crucible 6 and is held by the first opening 8: the full / empty ratio of the first opening 8? such as to retain the pieces of intact pellets, and to allow the passage of air which a possible pumping means 21 or 22, such as a fan, will push into the crucible 6.

Once the 6 gasification crucible? partially full, the igniter 29, of the glow plug type, provides for heating it; triggers the chemical phenomenon of pyrolysis in the internal woody part in the absence of air (endothermic reaction with the release of gases, liquid compounds and combustible solids) and the phenomenon of gasification (exothermic reaction of partial oxidation) where c '? a minimum quantity? of air.

The accumulated 4 pieces of pellets do not allow an adequate passage of air, thus creating a situation of heating of the wood mass in lack of oxygen that does not allow the reaction to proceed to complete combustion, and therefore there is generation of a singas and a weak flame which consumes a small part of it.

The phenomenon of gasification being exothermic allows to self-sustain the entire pyro-gasifier process inside the crucible 6.

The gas generated inside the gasification crucible 6, which is not involved in the combustion, rises upwards until it meets the second combustion air 28, coming from the second plenum 10b through the second openings 12.

It is in that moment and position that the mixing of singas and enough oxygen is triggered to develop the real flame.

The expansion chamber 13 has two specific functions: to allow the partial mixing of the singas with the oxygen entering in correspondence with an expansion of the ducting through the second openings 12 and through the third openings 16a, air-singas recirculations are triggered which reduce emissions of particulate matter, as well as spatially expanding the flame.

The combustion chamber 15 also has an additional inlet 23 for the sole purpose of supplying the excess air necessary to ensure the completion of the combustion of each molecule of combustible gas.

The air used for the gasification and combustion processes flows inside the stove thanks to one or more? suitable pumping means, or fans, such as a first pumping means 22 operating in thrust or a second pumping means 21 operating in suction.

The air path goes from a generic inlet to the border of the stove, passes inside the general air supply duct 30 of the various plenums, flowing into the first plenum 10a, the second plenum 10b, the third plenum 10c and the fourth plenum 10d , is distributed through the first opening 8, the second openings 12, the third openings 16a and the additional inlet 23, it ends up in the fluid volume included in the gasification crucible 6, in the expansion chamber 13 and in the combustion chamber 15, then under form of burnt gas all flows into a suitable air-to-air exchanger (not shown) and then into an exhaust gas expulsion duct.

The partialization of the air at the various inlets with a possible single pumping means, in suction or thrust,? guaranteed by suitable geometries of air passages located downstream of the various plenums.

Yup ? cos? it has been observed that the invention has achieved the intended aim and objects, having obtained a stove which allows to activate the pyrolytic and gasifying phenomena in one area of the stove and then to carry out the complete oxidation of the singas in another area with suitable air inlets, which although always in a hyperstichiometric regime, they generate a flame visibly equivalent to that of classic wood combustion.

The flame inside the combustion chamber is soft, that is? without the tongues of fire typical of all pellet stoves and therefore has a conspicuously much more volumetric development? ample for the benefit of an attractive aesthetic.

An added benefit? consisting of the fact that, while the common state-of-the-art pellet stoves vary from the burned power to have a very low flame and almost completely inside the brazier, resulting invisible to sight through the glass, the flame referred to in the present solution is however developed inside the combustion chamber, in front of the glass, even at the corresponding minimum power and in a much more? conspicuous compared to the stoves of the known state of the art.

A further advantage of the present invention? that the staged combustion, passing through distinct positions in which gasification and combustion of singas takes place, emits particulate matter in quantity? lower than combustion with a flame anchored to the actual wood mass.

Another advantage of the present invention? the possibility? to increase or decrease the

Claims (11)

presence of air inside the stove thanks to the first pumping means, operating in suction or thrust, which appropriately divided over the various inlets to the various plenums distributes this air to the various inlets. The presence of the means for conveying the pellets 4 from the tank 3 to the gasification crucible 6 also allows the contribution of the wood mass or pellets 4 to be increased or decreased. The two actions, coordinated through the electronic controls, allow the stove of the present invention to operate at different power regimes. Of course, the materials used as well as? the dimensions constituting the individual components of the invention may be more? relevant according to specific needs. The characteristics indicated as advantageous, convenient or the like may also be missing or be replaced by equivalents. CLAIMS 1. Gasification stove (1) comprising a containment structure (2) in which a storage tank (3) for biomass fuel (4), a gasification crucible (6) connected to an expansion chamber (13) are housed in turn connected to a combustion chamber (15), an air-air heat exchanger, which is characterized by the fact that said expansion chamber (13), above said gasification crucible (6) and below said combustion chamber (15), has an intermediate section (18) having dimensions greater than those of a section (17), which enters from said gasification crucible (6). 2. Gasification stove as in claim 1 which is characterized in that said expansion chamber (13), above said gasification crucible (6) and below said combustion chamber (15), has an intermediate section (18) having dimensions higher than those of the outlet section (16) towards said combustion chamber (15). 3. Gasifier stove as per one or both of the preceding claims which is characterized in that said crucible (6) gasifier, substantially tubular in shape with constant, circular or rectangular section,? delimited, at the extremity? lower (7), from a first opening (8) designed to allow the passage of a first gasification air (9), coming from a first plenum (10a), called gasification crucible (6) presenting, at the extremity? upper (11), a series of second openings (12) suitable for allowing the passage of a second combustion air (28), in correspondence with the passage towards said, above, gas expansion chamber (13). 4. Gasifying stove as to one or more? of the preceding claims which is characterized by the fact that said expansion chamber (13) communicates at the bottom with said gasification crucible (6) and has a section (17), inlet to said expansion chamber (13), of equal area or substantially equal to that of said gasification crucible (6) itself. 5. Gasifying stove as to one or more? of the preceding claims which is characterized in that said expansion chamber (13) has a box-like conformation in which? defined said section (18), intermediate between said section (16), outlet to said combustion chamber (15), and said section (17), inlet towards said expansion chamber (13) itself, which has larger dimensions to those of said inlet section (17), it is comprised between (7,000-16,000) sq.mm, preferably 13,000 sq.mm. 6. Gasifying stove as to one or more? of the preceding claims which is characterized in that said expansion chamber (13) has a box-like conformation in which? defined said section (18), intermediate between said section (16), of outlet to said combustion chamber (15), and said section (17), of inlet towards said expansion chamber (13) itself, said section (16) output being between (5,000-9,000) sq. mm. 7. Gasif icing stove as to one or more? of the preceding claims which is characterized in that the area of the section of said combustion chamber (15) placed above said section (16), at the outlet from said expansion chamber (13)? greater than the area of said section (16) itself and? between (15,000-50,000) sq. mm. 8. Gasif icing stove as to one or more? of the preceding claims which is characterized by the fact that, externally to said gasification crucible (6) and in the vicinity? of said extremity? upper (11),? there is a second plenum (10b), externally circumscribing said crucible (6), for gasification presenting a series of second openings (12), for a second combustion air (28), placed in correspondence with said passage from the tubular section of said crucible (6) gasifier and said expansion chamber (13). 9. Gasifying stove as to one or more? of the preceding claims which is characterized by the fact that, externally to said expansion chamber (13) and in the vicinity? of said section (16), output,? present a third plenum (10c), presenting a series of third openings (16a), for a third combustion air (31), placed in correspondence with the passage from said expansion chamber (13) and said combustion chamber (15) . 10. Gasifying stove as to one or more? of the preceding claims which is characterized by the fact that said combustion chamber (15) has an additional inlet (23), for a fourth combustion air (24), obtained on one of its walls (25) and connected to a fourth plenum (10d), connected to said general air supply duct (30). 11. Gasifying stove as to one or more? of the preceding claims which is characterized in that it comprises a duct (14) for discharging said biomass fuel (4) comprising a worm screw, or a propeller, or a motorized screw with