Patent Application
20250102141
The present invention relates to a burner with internal fumes recirculation. In particular, with the definition of burner with fumes recirculation, reference is made to a peculiar type of burners configured to allow a suction of an amount of combustion fumes so as to reintroduce them inside the burner mixed with the comburent air.
Specifically, the combustion gases, containing a low percentage of residual oxygen and having a relatively high temperature, by mixing with the air sucked from the environment, cause an increase in the total volumetric amount of comburent necessary to complete the combustion. This results in a dispersion of the energy developed during combustion in a greater specific volume with the consequent lowering of the absolute flame temperature and decrease in the formation of NOx by thermal effect. Merely by way of non-limiting example, the burners can be supplied by natural gas (G20/G25) or LPG (G30/G31) or other gases not expressly indicated herein or they can be mixed (gas and diesel or gas and naphtha or still other not expressly indicated herein).
The burners generally comprise a combustion head adapted to trigger and maintain stable the combustion by virtue of a given ratio of fuel and comburent.
In essence, the combustion head is an element of the burner which allows the correct mixing between the comburent and the fuel, generating the first flame front and developing a retention zone thereof so as to ensure operating stability during the operations of the burner.
The known combustion heads can have the most varied conformations, however such combustion heads are, generally, united by the presence of an outer tubular body, configured to supply comburent, and an inner tubular body, configured to supply the fuel.
In use, the combustion head is introduced inside the combustion chamber so as to optimise the mixing between the fuel and the comburent so as to achieve the optimal development of the flame inside the combustion chamber.
In particular, the combustion chamber, inside which the combustion head is arranged, comprises at least one flue adapted to allow the exit of the gases produced during the plurality of different operating steps.
The aforementioned fumes recirculation systems comprise bulky recirculation ducts connected to such a flue and communicating with the supply duct of the comburent on the burner.
In essence, the recirculation ducts put the combustion chamber flue and the comburent supply duct in fluid communication so as to re-introduce part of the gases produced during combustion inside the comburent supply duct.
Disadvantageously, the bulkiness induced by the aforementioned recirculation ducts strongly limits the use thereof to particularly spacious operating environments, precluding the application thereof to cramped, narrower environments.
Disadvantageously, moreover, the adoption of such recirculation technology determines the need for substantial interventions on the generator flue and thus downstream of the burner so as to allow the application of the aforementioned recirculation ducts.
That is, the conversion of a classic system to a fumes recirculation system so as to limit the production of NOx becomes particularly onerous, as it involves the substantial modification of the structure of the flue, having to implement a further insulated duct and appropriate condensate discharges.
In this situation, the technical task underpinning the present invention is to provide a burner with fumes recirculation capable of overcoming the above-mentioned drawbacks of the prior art.
In particular, it is an object of the present invention to make a burner with fumes recirculation which is economically cheaper and easier to install relative to the solutions of the prior art.
It is still an object of the present invention to make a burner with fumes recirculation which allows to reduce NOx emissions without causing an increase in the production of further pollutants (such as carbon monoxide). A further object of the present invention is to provide a burner with fumes recirculation capable of limiting the noise of the burner to which the fumes recirculation system to the flue is typically adapted.
The technical task set and the objects specified are substantially attained by a burner with fumes recirculation comprising the features as set out in one or more of the claims.
The dependent claims correspond to possible embodiments of the invention.
Further features and advantages of the present invention will become more apparent from the indicative and thus non-limiting description of an embodiment of a burner with fumes recirculation.
Such a description will be set out below with reference to the appended drawings, which are provided solely for illustrative and therefore non-limiting purposes, in which:
With reference to the appended drawings, the reference number 1 has been used to generally designate a burner with internal fumes recirculation, which will be indicated here as burner 1.
The burner 1 comprises a first supply duct 2 for supplying fuel, having at least a first inlet opening 3 and a first outlet opening 4.
Furthermore, the burner 1 comprises a second supply duct 5 for supplying comburent, having at least a second inlet opening 6 and a second outlet opening 7.
In particular, the first outlet opening 4 and the second outlet opening 7 can be confluent at a head 8 of the burner 1 configured to generate a flame.
That is, the burner 1 can comprise a head 8 adapted to promote the generation of a flame. Furthermore, the aforementioned first outlet opening 4 and second outlet opening 7 can be confluent at such a head 8 so as to allow an effective generation of such a flame.
Furthermore, the burner 1 can comprise regulation means 30 configured to modify a relative positioning between the first outlet opening 4 and the second outlet opening 7 so as to ensure an effective inflow of fuel and comburent near the head 8.
Purely by way of non-limiting example, the regulation means can comprise an elongated body, for example a rod, inserted or insertable inside the first supply duct 2 and/or connected or connectable thereto to cause a reversible axial sliding of at least one portion of the first supply duct 2 so as to change the positioning of the first outlet opening 4 relative to the head 8. In the preferred embodiment, such a sliding portion has a reduced or increased diameter relative to a fixed portion so as to overlap the latter during said sliding.
Preferably, the burner 1 comprises an end disc arranged at the first outlet opening 4 and the second outlet opening 7 and having a plurality of through holes adapted to promote an exit of the comburent and a plurality of radial ducts extending radially relative to the first supply duct 2 to promote the exit of the fuel.
In use, the head 8 can be arranged at least partially inside a combustion chamber adapted to at least partially confine the flame generated during the operating steps of the burner 1.
Preferably, the burner 1 comprises an additional duct for supplying the comburent arranged at least partially inside the first supply duct 2 and preferably coaxial thereto. In particular, such an additional duct for supplying the comburent is in fluid communication with the second supply duct 5 at the second inlet opening 6.
It should be noted that the fuel is supplied in the space defined between the first supply duct 2 and said additional duct as depicted in
The fumes return duct 10 has a third fumes inlet opening 11 arranged at the head 8 of the burner 1.
Preferably, such a third inlet opening 11 surrounds the head 8 of the burner 1 and the second comburent supply duct 5. Even more preferably, said fumes return duct 10 is coaxial to the second comburent supply duct 5 at said third inlet opening 11.
In particular, the fumes return duct 10 has a third outlet opening 12 placed in fluid communication with the second inlet opening 6 for the comburent to promote an at least partial re-introduction of the combustion fumes in the second comburent supply duct 5.
Advantageously, the suction means 9 is configured to promote a movement of the combustion fumes from the fumes return duct 10 to the second supply duct 5. In particular, the combustion fumes can suitably be mixed with an amount of comburent air sucked from the passage surface 23.
In accordance with a possible embodiment and as illustrated in the appended drawings, the suction means 9 comprises a mixing chamber 13. In particular, the mixing chamber 13 has a first port 14, adapted to be placed in fluid communication with an environment outside the burner 1 to allow an inflow of comburent to the mixing chamber 13, and a second port 15, adapted to be placed in fluid communication with the fumes return duct 10 to promote an inflow of the combustion fumes to the mixing chamber 13.
In essence, the suction means 9 are configured to introduce a mixture of the comburent and the combustion fumes in the second supply duct 5. Preferably, the burner 1 comprises adjustment means 16 active on the first port and/or on the second port to adjust an inflow of comburent through the first port 14 and/or an inflow of combustion fumes from the second port 15, respectively.
In accordance with a purely exemplary and non-limiting embodiment, the suction means 9 comprises a fan 17 arranged downstream of the aforementioned mixing chamber 13.
Preferably, such a fan 17 is a centrifugal fan with axial suction and radial emission.
Advantageously, the first supply duct 2 and/or the second supply duct 5 can be at least partially inserted in the fumes return duct 10.
Preferably, the first supply duct 2 can be at least partially inserted in the second supply duct 5.
In particular, the first supply duct 2 and the second supply duct 5 define a passage volume therebetween for the comburent delimited by the second supply duct 5 and by the first supply duct 2. Furthermore, the second supply duct 5 can be at least partially inserted in the fumes return duct 10. According to a possible embodiment of the present invention and as illustrated in the appended drawings, the second supply duct 5 is coaxial to the first supply duct 2.
Furthermore, the fumes return duct 10 can have a portion at least partially coaxial to the first supply duct 2.
Thereby, the specific geometry of the aforementioned ducts gives the burner 1 a particularly compact shape which allows it to be adopted both in spacious environments and in environments with particularly limited volumes.
It should be noted that the present invention therefore overcomes the need for long and expensive interventions on the boiler, for example due to the need to apply a fumes recirculation duct to the flue of the boiler, in order to reduce NOx emissions.
In fact, the present invention provides a burner comprising the fumes return duct 10, which is applied to the combustion chamber substantially without further interventions during the step of connecting the burner to the combustion chamber itself.
That is, the present invention overcomes the need for a duct applied to the flue of the combustion chamber by sucking the combustion gases from the opening of the combustion chamber employed for the insertion of the burner 1.
Therefore, the present invention allows an easy and economical conversion of a system developed without the technology of combustion fumes recirculation in a combustion fumes recirculation system, for example in order to reduce the production of NOx, through the sole replacement of the burner.
Advantageously, the fumes return duct 10 comprises a portion peripherally arranged around the first supply duct 2 and/or the second supply duct 5. In particular, the third inlet opening 11 can be arranged in a retracted position relative to the first outlet opening 4 and/or the second outlet opening 7 relative to a fuel and/or comburent supply direction.
Thereby, the fumes return duct 10 together with the third inlet opening 11 ensures that the gases generated during combustion are effectively sucked through the third inlet opening 11 under the action of the suction means 9.
Furthermore, the fumes return duct 10 together with the third inlet opening 11 ensures that the gases generated during the combustion are not withdrawn close to the flame front.
Advantageously, the burner 1 comprises a heat exchange section 18 interposed between the third inlet opening 11 and the third outlet opening 12.
The heat exchange section 18 is configured to promote a decrease in the temperature of the combustion fumes during a passage thereof between the third inlet opening 11 and the third outlet opening 12.
Thereby, the burner 1 allows to give the sucked combustion gases a temperature such as not to damage the ventilating part and the adjustment members for mixing fuel and comburent.
Purely by way of non-limiting example, the temperature of the combustion fumes during a passage thereof between the third inlet opening 11 and the third outlet opening 12 can pass from a peak temperature range comprised between 800° C. and 700° C., preferably 750° C., near the third inlet opening 11 to a temperature range comprised between 400° C. and 200° C., preferably 250° C., near the third outlet opening 12.
Preferably, the heat exchange section can be made by means of a heat exchanger 19 active at least between the fumes return duct 10 and the second comburent supply duct 5 and interposed between the third inlet opening 11 and the third outlet opening 12.
In accordance with a possible embodiment and as illustrated in the present invention, the heat exchanger 19 comprises a tube bundle 20 obtained as a branch of the second supply duct 5 and a shell container 21 obtained as an enlargement of the fumes return duct 10.
That is, the second supply duct 5 can comprise a plurality of tubes branching from at least one branching portion of the second supply duct 5 and, preferably, merging into at least one merging portion of the second supply duct. Such a plurality of tubes is preferably at least partially arranged inside the heat exchange section.
In accordance with a further possible embodiment not illustrated in the appended drawings, the heat exchanger 19 can comprise an exchange jacket, for example extending peripherally and/or at least partially interposed with the plurality of tubes defining the tube bundle 20, configured to allow the circulation of a heat exchange fluid, for example water, so as to allow a more effective decrease in the temperature of the fumes. In such a version not depicted in the drawings, with the integration of the cooling of the fumes through the boiler inlet water, an advantageous increase in the heat exchange efficiency of the generator as a whole is also obtained.
Furthermore, the heat exchanger 19 can comprise one or more conveying surfaces adapted to convey the flow of the combustion fumes during a passage thereof between the third inlet opening 11 and the third outlet opening 12, for example through the tube bundle 20, so as to ensure a highly efficient heat exchange.
Advantageously, the burner 1 can comprise an outer casing 22 adapted to at least partially contain the fumes return duct 10, the first supply duct 2 and the second supply duct 5.
In particular, the outer casing 22 can have an aeration system configured to promote an air passage between the inside and the outside of the outer casing 22.
Preferably, the aeration system of the outer casing 22 defines a closed guide area with respect to the outside for conveying the air from the external environment towards the first port 14 of the mixing chamber 13 so that the inlet air is guided through said area.
Furthermore, as illustrated in the appended drawings, the aforementioned aeration system comprises a plurality of holes and/or slits 23 from which the air enters, which is then conducted through the guide area towards the first port 14.
Advantageously, in fact, the aforementioned plurality of holes and/or slits 23 allows a fluid communication between the second inlet opening 6 and the environment outside the burner so as to allow an inflow of comburent to the second supply duct 5 under the suction action of the suction means 9.
In particular, the aforementioned plurality of holes and/or slits 23 can be arranged at the heat exchange section 18 so that the comburent flow thus generated, by lapping the outer walls thereof, contributes to the reduction of the temperature of the combustion gases passing through the heat exchanger 19.
Advantageously, moreover, the possibility of sucking the comburent air from the wide passage section 23, placed distant from the adjustment part 16, allows to maintain a particularly low noise level.
It is therefore noted that the present invention achieves the proposed objects by making a burner with fumes recirculation capable of reducing NOx emissions by virtue of the presence of a fumes return duct having a third fumes inlet opening arranged at the head of the burner and a third outlet opening placed in fluid communication with the second inlet opening for the comburent to promote an at least partial re-introduction of the combustion fumes in the second comburent supply duct.
Advantageously, the present invention ensures an easy and economical conversion of a system developed without the classic technology of combustion fumes recirculation, for example in order to reduce the production of NOx, through the sole replacement of the burner.
That is, the present invention can allow an easy implementation, substantially by retrofit, of a fumes recirculation system on common burners lacking such a peculiarity.
Advantageously, the present invention provides a particularly compact and silent solution for reducing the production of NOx and which, therefore, can be easily applied in operating environments having restricted volumes.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102022000001109 | Jan 2022 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2023/050538 | 1/23/2023 | WO |
