Supply assembly for supplying hydrogen-containing fuel gas to a combustor of a

Abstract

A supply assembly for supplying at least one fuel gas to a burner of a boiler, having a supply conduit (3) configured to supply a supply stream of fuel gas to the burner (2) in a supply direction (D1); and a safety device (4) arranged in the supply duct (3) and shaped to define a stagnation zone (9) configured to inhibit a return flow of gas from the burner (2) back into the supply duct (3) in a return direction (D2) substantially opposite the supply direction (D1).

Description

[0001] Cross-reference to related applications

[0002] This patent application claims the priority of Italian Patent Application No. 102022000011300 filed on May 27, 2022, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The invention relates to a supply assembly for supplying hydrogen-containing fuel gas to a burner of a boiler.

[0004] Furthermore, the invention relates to a burner assembly comprising the supply assembly and to a boiler comprising the burner assembly. Background Art

[0005] As we all know, a boiler is a device that transfers heat to the liquid distributed in the heating system through combustion.

[0006] Generally, a boiler includes a burner assembly provided with a burner configured to combust a fuel gas and a gas supply pipe for supplying the fuel gas to the burner in a supply direction.

[0007] The use of fuel gases or fuel gas mixtures with high flame speeds presents a serious risk of a phenomenon commonly known as "flashback". The flashback phenomenon generally involves a return flow of burned or hot gases back from the burner along the supply conduit in a direction opposite to the direction in which the fuel gas was supplied.

[0008] In boilers of known type, flashbacks may damage parts of the boiler, such as supply pipes for the fuel gas.

[0009] The object of the present invention is therefore to achieve a supply assembly for supplying fuel gas to a burner of a boiler which alleviates the drawbacks of the known art indicated herein. Summary of the invention

[0010] In particular, the object of the invention is to produce a supply assembly which is reliable and which is able to avoid damage to its components due to possible flashbacks in a simple and cost-effective manner.

[0011] According to the invention, a supply assembly for supplying at least one fuel gas to a burner of a boiler is manufactured, the supply assembly comprising:

[0012] - a supply conduit configured to supply a supply flow of fuel gas to the burner along a supply direction; and

[0013] A safety device arranged in the supply duct and shaped to define a stagnation zone configured to inhibit a return flow of gas from the burner into the supply duct in a return direction substantially opposite to the supply direction.

[0014] By means of the invention, components of a boiler can be protected from the effects of flashback in a simple, cost-effective and reliable manner.

[0015] If flashback occurs, a return flow defined by hot gases and at least partially still in the combustion phase returns to the supply duct in a return direction opposite to the supply direction of the gas flow. This return flow is greatly slowed down and impeded by the safety device arranged in the supply duct due to the stagnation zone.

[0016] In other words, the stagnation zone inhibits the advancement of the return flow, preventing the flow from advancing further in the return direction along the supply conduit.

[0017] In practice, the safety device made according to the invention is able to suppress flashback without the use of moving parts or electronic components, such as sensors or control units, thus increasing the simplicity and reliability of the supply assembly.

[0018] In particular, the safety device is arranged in the supply conduit to define at least one passage restriction for the supply flow of the fuel gas.

[0019] Therefore, at the inlet of the passage restriction, the flow velocity of the fuel gas increases. In this way, it can be determined that in the passage restriction, the return flow of the gas encounters resistance when advancing in the return direction.

[0020] In particular, the safety device comprises a stagnation chamber delimiting a stagnation zone and provided with an inlet opening towards the burner, thereby defining a passage to the stagnation chamber.

[0021] In this way, the return flow of gas can be confined inside the stagnant zone, thereby preventing it from advancing in the return direction along the supply conduit.

[0022] In particular, the inlet opening defines the only access to the stagnation chamber.

[0023] In this way, the return flow is trapped in the stagnation chamber and subsequently discharged into the feed duct and fed back to the burner.

[0024] In particular, the safety device comprises a blocking wall which at least partially delimits the stagnation chamber and which extends transversely with respect to the supply direction in order to block the return flow of gas returning in the return direction in the event of a flashback.

[0025] In particular, the barrier wall has an aerodynamic profile in the supply direction in order to limit the pressure drop of the fuel gas flow supplied in the supply direction.

[0026] Due to the aerodynamic profile, the safety device ensures the stability of the supply flow of the fuel gas in the supply direction. That is, the safety device helps to prevent turbulence from occurring in the supply flow of the fuel gas.

[0027] An aerodynamic profile is a shape designed to provide minimal drag when impinged upon by an incident airflow in a feed direction.

[0028] Preferably, the aerodynamic profile reduces the occurrence of vortices and instabilities in the feed flow.

[0029] Specifically, the blocking wall includes: a first part having a first surface that collides with the supply flow of the fuel gas in the supply direction; and a second part having a second surface that collides with the supply flow of the fuel gas in the supply direction; the first surface and the second surface are oriented so as to determine a leading edge of the supply flow of the fuel gas in the supply direction.

[0030] In this way, it is possible to reduce the resistance of the safety device to the flow of fuel gas in the supply direction, while suppressing the advancement of the return flow along the supply pipe in the return direction.

[0031] In particular, the first face and the second face are oriented such that a front angle is defined therebetween, the front angle being between 10° and 120°.

[0032] In more detail, a smaller front angle corresponds to a longer length of the safety device measured along the feed direction and a smaller hydrodynamic resistance to the fuel gas flow in the feed direction.

[0033] Conversely, a larger front angle corresponds to a shorter length of the safety device measured along the feed direction and a greater hydrodynamic resistance to the fuel gas flow in the feed direction.

[0034] Specifically, the safety device comprises a first side wall and a second side wall, each of which is arranged at a respective end of the barrier wall so as to define a stagnation chamber together with the barrier wall; the first side wall and the second side wall extend transversely relative to the barrier wall.

[0035] In this way, a stagnation zone can be defined on three sides to effectively block the progress of the flame in the return direction.

[0036] In practice, due to the first and second side walls, the stagnation chamber is closed on three sides and is only open in the return direction.

[0037] Specifically, the barrier wall and / or the first side wall and / or the second side wall are made of a heat conductive material.

[0038] In this way, if a flashback occurs, the flame can be extinguished and quickly dissipated by being confined within the stagnant zone.

[0039] Another object of the present invention is to create a burner assembly that alleviates the drawbacks of the known art.

[0040] According to the present invention, a burner assembly is manufactured, which includes the supply assembly as described above and includes a burner configured to burn the fuel gas supplied by the supply assembly.

[0041] Another object of the present invention is to create a boiler that alleviates the drawbacks of the known art.

[0042] According to the invention, a boiler is manufactured comprising a burner assembly as described above.

[0043] In this way, components of the boiler can be protected from the heat generated by flashback without the need to arrange moving parts or electronic components, such as sensors or control units, in the boiler, thereby increasing the simplicity and reliability of the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other features and advantages of the invention will become apparent from the following description of non-limiting exemplary embodiments with reference to the accompanying drawings, in which:

[0045] Figure 1 is a schematic diagram of a boiler manufactured according to the present invention;

[0046] Figure 2 yes Figure 1 A schematic diagram of the details of the boiler;

[0047] Figure 3 yes Figure 1 A cross-sectional view of a detail of a boiler in which some parts have been removed for clarity;

[0048] Figure 4 and Figure 5 yes Figure 1 A perspective view of a corresponding embodiment of the boiler safety device in FIG. 1 ; and

[0049] Figure 6 yes Figure 1 A cross-sectional view of a detail of a boiler supply assembly in which some parts have been removed for clarity. DETAILED DESCRIPTION

[0050] refer to Figure 1 , reference numeral 1 denotes a boiler as a whole that can be used in a heating system. Specifically, the boiler 1 can be used in a household or industrial field, or in any other field that requires heat to be transferred to a liquid distributed in a heating system by combustion.

[0051] In the examples described and shown herein, but not limiting to the invention, the boiler 1 is of the "condensing" type. In particular, the fuel gas used is a high flame speed gas, such as hydrogen, methane, LPG, a mixture of hydrogen and air, a mixture of methane and air or a mixture of methane and hydrogen. It should be understood that within the scope of the invention, any gas or any mixture suitable for producing a combustion reaction may be used.

[0052] refer to Figure 1 and Figure 2 The boiler 1 includes a burner assembly 32 , which includes: a burner 2 configured to burn at least one fuel gas; and a supply assembly 15 configured to supply the fuel gas to the burner 2 .

[0053] The supply assembly 15 includes: a supply pipe 3, configured to supply a supply flow of fuel gas to the burner 2 along a supply direction D1; and a safety device 4, arranged in the supply pipe 3 and shaped to define a stagnation zone 9, which is configured to suppress a return flow returning from the burner 2 and having a return direction D2 that is substantially opposite to the supply direction D1.

[0054] In particular, the portion of the supply duct 3 housing the safety device 4 extends along a longitudinal axis A1 , and the burner 2 extends along a longitudinal axis A2 that is substantially perpendicular to the longitudinal axis A1 .

[0055] Furthermore, the boiler 1 comprises an air supply inlet 5, a gas supply inlet 6, the gas being, for example, hydrogen or methane, a suction device 7 configured to draw in air and gas through the respective inlets 5 and 6, and a mixing device 8 configured to mix the drawn air with the gas to produce a fuel gas.

[0056] refer to Figure 1 The boiler 1 includes: an outer shell 10; a heat exchanger 11, to which the heating gas generated by the burner 2 is supplied, and the heat exchanger is configured to heat the working fluid; a discharge assembly 12, which is arranged downstream of the heat exchanger 11 and is configured to transport the condensate generated by at least partial condensation of the heating gas to a condensate discharge system 13; and an output pipe 14 for the heating gas.

[0057] In particular, the heat exchanger 11 comprises a supply conduit 16 for the working fluid, the supply conduit having an inlet portion 17 for the working fluid to enter the boiler 1 and an outlet portion 18 for the working fluid to exit from the boiler 1 .

[0058] The discharge assembly 12 includes a collecting tank 19 for collecting condensate in the heat exchanger 11 , a siphon pipe 20 to which the condensate is supplied, and a pipe 21 connecting the collecting tank 19 to the siphon pipe 20 .

[0059] Specifically, the siphon 20 is configured to convey condensate toward the condensate drain system 13 while simultaneously obstructing heated gas from passing through the siphon 20 .

[0060] refer to Figure 3 and Figure 4 , the safety device 4 comprises a stagnation chamber 33 delimiting the stagnation zone 9 and provided with an inlet opening 31 towards the burner 2, defining a passage to the stagnation chamber 33. In practice, in the event of a flashback, the inlet opening 31 allows a return flow of gases from the burner to enter the stagnation zone 9 in the return direction D2.

[0061] In more detail, the inlet opening 31 defines the only access to the stagnation chamber 33 .

[0062] Specifically, the safety device 4 comprises a barrier wall 22 which at least partially delimits the stagnation chamber 33 and extends transversely relative to the supply direction D1 so as to block the return flow returning in the return direction D2 in the event of a flashback. Specifically, the barrier wall 22 has an aerodynamic profile in the supply direction D1.

[0063] In the example described and shown herein, but not limited to the present invention, the barrier wall 22 comprises: a portion 23 having a surface 35 ( Figure 4 and Figure 5 ) and a portion 24 having a surface 36 (which collides with the supply flow of the fuel gas in the supply direction D1) Figure 4 and Figure 5 ).

[0064] Specifically, the surface 35 and the surface 36 are oriented so that the leading edge of the supply flow of the fuel gas along the supply direction D1 is determined between them. Figure 4 and Figure 5 ) are oriented so as to define a front angle α between them, the front angle being between 10° and 120°. Specifically, the parts 23 and 24 are integrally connected to each other.

[0065] According to alternative embodiments (not shown in the drawings), the barrier wall 22 may adopt any configuration suitable for blocking the return flow of gas along the return direction D2. As an example, the barrier wall may be "C" shaped, wherein the concave surface of the barrier wall faces the burner 2.

[0066] Furthermore, the safety device 4 comprises a side wall 25 and a side wall 26, each of which is arranged at a respective end of the barrier wall 22 so as to delimit, together with the barrier wall 22, a stagnation zone 9. In more detail, the side walls 25 and 26 delimit an inlet opening 31 .

[0067] Specifically, the side wall 25 is integrally coupled to the portion 23, and the side wall 26 is integrally coupled to the portion 24. In other words, the portions 23 and 24 and the side walls 25 and 26 are integrally made into one piece.

[0068] In the examples described and shown herein, the side wall 25 and the side wall 26 extend transversely relative to the barrier wall 22. In particular, the portion 23 and the side wall 25 define an angle β between them that is greater than 90°, preferably between 120° and 150°, and the portion 24 and the side wall 26 define an angle γ between them that is greater than 90°, preferably between 120° and 150°.

[0069] According to one embodiment, the portion 23 and / or the portion 24 and / or the side wall 25 and / or the side wall 26 are made of a heat conducting material, preferably a metal material. Specifically, the safety device 4 is manufactured by bending a portion of a metal fin to form the portions 23, 24 and the side walls 25, 26.

[0070] refer to Figure 3 , the safety device 4 is arranged in the supply conduit 3 to define two channel restrictions 27 for the supply flow of the fuel gas.

[0071] In particular, each side wall 25, 26 and wall 28 of the supply duct 3 defines a respective channel restriction 27 for the flow of the fuel gas in the supply direction D1. In practice, the barrier wall 22 is shaped to guide the flow of the fuel gas in the channel restriction 27, in particular in order to divide the flow of the fuel gas in the supply direction D1 into two separate flows.

[0072] In more detail, in each channel restriction 27 , the distance d1 , d2 between the respective side wall 25 , 26 and the wall 28 of the supply duct 3 along a direction D3 substantially perpendicular to the direction D1 is smaller than a dimension d3 of the supply duct 3 along this direction D3 .

[0073] In the examples described and illustrated herein, each side wall 25 , 26 extends in a direction substantially parallel to the longitudinal axis A1 , and therefore, the respective distances d1 and d2 are substantially constant along the longitudinal axis A1 .

[0074] According to an alternative embodiment (not shown in the drawings), each side wall 25, 26 extends intersecting the longitudinal axis A1. In this configuration, the distances d1 and d2 of the side walls 25 and 26 vary along the longitudinal axis A1, in particular, they decrease in the direction D1.

[0075] refer to Figure 4The safety device 4 comprises two fixing fins 29, which are configured to enable the safety device 4 to be fixed to the wall of the supply pipe 3. Specifically, each fixing fin 29 is provided with a through opening 30, which is configured to allow a fixing device such as a screw or a rivet to be inserted through the corresponding fixing fin 29.

[0076] According to one embodiment (not shown in the drawings), the safety device 4 comprises at least one housing for sensors such as speed sensors and / or pressure sensors or for other devices such as thermostats and / or thermal fuses to control the flow conditions of the fuel gas and prevent the boiler 1 from catching fire in the event of damage due to flashback.

[0077] refer to Figure 5 , shows another embodiment of the safety device 4. According to this embodiment, the safety device 4 includes at least one flow straightening element 34, which is arranged in one of the channel restrictions 27 and is configured to determine a laminar supply flow of the fuel gas in the corresponding channel restriction 27. In other words, the flow straightening element 34 is shaped to avoid vortexes in the supply flow of the fuel gas along the supply direction D1.

[0078] In particular, the safety device 4 comprises two flow straightening elements 34, each of which is fixed to a respective side wall 25, 26 outside the stagnation zone 9. In more detail, each flow straightening element 34 is arranged in a respective passage restriction 27.

[0079] In the examples described and illustrated herein, but not limiting of the present invention, each flow straightening element 34 comprises a grid made of a metallic material.

[0080] Furthermore, each flow straightening element 34 is configured to dissipate heat transferred to the safety device 4 by the gas in the return flow.

[0081] refer to Figure 6 , along a line perpendicular to the longitudinal axis A1 ( Figure 3 ), the supply conduit 3 has a substantially rectangular cross section. Specifically, the supply conduit 3 has a dimension D4 along a direction D3 substantially perpendicular to the dimension d3 and a direction D4 perpendicular to the longitudinal axis A1.

[0082] The safety device 4 extends over a dimension d4 inside the supply pipe 3. In more detail, the barrier wall 22 and the side walls 25 and 26 extend along the direction D4 over a dimension d5 that is substantially equal to the dimension d4. In other words, the barrier wall 22 and the side walls 25 and 26 are configured to block the return flow of gas in the supply pipe 3 along the entire dimension d4.

[0083] In the example described and shown herein, the distances d1 and d2 of the channel restriction 27 are constant along the direction D4. In other words, the side walls 25 and 26 extend in a direction substantially parallel to the direction D4.

[0084] According to an alternative embodiment (not shown in the drawings), along a direction perpendicular to the longitudinal axis A1 ( Figure 3 ), the supply duct 3 has a substantially circular cross-section. As an example, in this configuration, the barrier wall comprises four parts, which are inclined to each other to form a square bottom right pyramid with the bottom facing the burner 2.

[0085] In use and reference Figure 1 The suction device 7 determines to suck air from the inlet 5 and to suck gas from the inlet 6. The mixing device 8 mixes the sucked air and gas to produce fuel gas, which is supplied from the suction device 7 to the burner 2 through the supply pipe 3.

[0086] The burner 2 burns the supplied fuel gas to generate a flame, and transfers the heat to the heat exchanger 11 .

[0087] refer to Figure 3 When the fuel gas is supplied to the supply pipe 3 along the supply direction D1, the safety device 4 guides the flow of the fuel gas in the channel restriction 27. Specifically, since the area of ​​the channel restriction 27 transverse to the flow of the fuel gas is smaller than the area of ​​the supply pipe 3 transverse to the flow of the fuel gas, when the fuel gas enters the channel restriction 27, the safety device 4 determines the acceleration of the flow of the fuel gas along the supply direction D1. In other words, the flow velocity of the fuel gas flow in the channel restriction 27 increases.

[0088] In the examples described and illustrated herein, barrier walls 23 and 24 of barrier wall 22 help direct the flow of fuel gas in passage restriction 27 by dividing the flow of fuel gas into two separate branch flows.

[0089] The fuel gas is stagnant in the stagnant area 9. In other words, in the stagnant area 9, the fuel gas does not flow toward the burner 2 in the supply direction D1.

[0090] For example, when flashback occurs due to a decrease in the flow velocity of the fuel gas in the supply pipe 3 , the flame advances from the burner 2 into the supply pipe 3 in the return direction D2 .

[0091] In this case, in the channel restriction 27, the flame encounters resistance when advancing in the return direction D2 because the flow velocity of the fuel gas in the supply direction D1 is maximum in the channel restriction 27. Therefore, the flame is guided and confined in the stagnation zone 9, where the flame is extinguished and the heat generated by the flame is rapidly dissipated due to the barrier walls 23 and 24 and the side walls 25 and 26.

[0092] Finally, it is obvious that modifications may be made to the embodiments described without departing from the scope of protection of the appended claims.

Claims

1. A supply assembly for supplying at least one fuel gas to a burner of a boiler, the supply assembly comprising: - a supply conduit (3) configured to supply a supply flow of fuel gas to the burner (2) along a supply direction (D1); as well as - a safety device (4) arranged in the supply duct (3) and shaped to define a stagnation zone (9) configured to inhibit a return flow of gas from the burner (2) into the supply duct (3) along a return direction (D2) substantially opposite to the supply direction (D1).

2. The supply assembly according to claim 1, wherein: The safety device (4) is arranged in the supply conduit (3) to define at least one passage restriction (27) for the supply flow of the fuel gas.

3. The supply assembly according to claim 2, wherein: The safety device (4) comprises at least one flow straightening element (34) which is arranged in the channel restriction (27) and is configured to determine a laminar supply flow of the fuel gas in the corresponding channel restriction (27).

4. The supply assembly according to claim 3, wherein: The at least one flow straightening element (34) is configured to dissipate heat transferred to the safety device (4) by the gas in the return flow.

5. A supply assembly according to any one of the preceding claims, wherein: The safety device (4) comprises a stagnation chamber (33) which delimits the stagnation zone (9) and is provided with an inlet opening (31) towards the burner (2) so as to define a passage to the stagnation chamber (33).

6. The supply assembly according to claim 5, wherein: The inlet opening (31) defines the only access to the stagnation chamber (33).

7. The supply assembly according to claim 5 or 6, wherein: The safety device (4) comprises a barrier wall (22) which at least partially delimits the stagnation chamber (33) and extends transversely with respect to the feeding direction (D1).

8. The supply assembly according to claim 7, wherein: The barrier wall (22) has an aerodynamic profile in the feed direction (D1).

9. The supply assembly according to claim 7 or 8, wherein: The barrier wall (22) includes: a first portion (23) having a first surface (35) that collides with the supply flow of the fuel gas in the supply direction (D1); and a second portion (24) having a second surface (36) that collides with the supply flow of the fuel gas in the supply direction (D1); the first surface (35) and the second surface (36) are oriented so that a leading edge for the supply flow of the fuel gas in the supply direction (D1) is determined between the first surface and the second surface.

10. The supply assembly according to claim 9, wherein: The first face (35) and the second face (36) are oriented such that a front angle (α) is defined between the first face and the second face, the front angle being between 10° and 120°.

11. The supply assembly according to any one of claims 7 to 10, wherein: The safety device (4) comprises a first side wall (25) and a second side wall (26), wherein the first side wall and the second side wall are each arranged at a respective end of the barrier wall (22) to define the stagnation chamber (33) together with the barrier wall (22); the first side wall (25) and the second side wall (26) extend transversely relative to the barrier wall (22).

12. The supply assembly according to claim 11, wherein: The portion of the supply conduit (3) housing the safety device (4) extends along a first longitudinal axis (A1); the first side wall (25) and the second side wall (26) are substantially parallel to the first longitudinal axis (A1).

13. The supply assembly according to claim 11 or 12, wherein: The barrier wall (22) and / or the first side wall (25) and / or the second side wall (26) are made of a heat-conducting material.

14. A supply assembly according to any one of the preceding claims, wherein: The safety device (4) comprises at least one fixing tab (29) configured to enable the safety device (4) to be fixed to the wall of the supply duct (3).

15. A burner assembly comprising a supply assembly (15) according to any one of the preceding claims and comprising a burner (2) configured to combust fuel gas supplied by the supply assembly (15).

16. A boiler comprising a burner assembly (32) according to claim 15.

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