Feeding Assembly for Feeding a Fuel Gas Containing Hydrogen to a Burner of a Boiler and Boiler Comprising Said Feeding Assembly

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

The present invention relates to a feeding assembly for feeding a hydrogen-containing fuel gas to a burner of a boiler.

Furthermore, the present invention relates to a burner assembly comprising said feeding assembly and a boiler comprising said burner assembly.

As is well known, a boiler is an equipment that carries out a passage of heat, by means of combustion, to a liquid distributed in a heating system.

Generally, the boiler comprises a burner assembly provided with a burner configured to burn a fuel gas, and a gas feeding duct for feeding fuel gas to the burner in a feeding direction.

The use of fuel gases or mixtures of fuel gases with a high flame speed involves serious risks of occurrence of a phenomenon normally referred to as “backfire”. The backfire phenomenon generally involves a return flow of burnt or incandescent gases from the burner along the feeding duct, in a direction opposite to the feeding direction of the fuel gases.

In boilers of known type, the backfire can damage components of the boiler, such as for example the feeding duct of fuel gas.

It is therefore an object of the present invention to realize a feeding assembly for feeding a fuel gas to the burner of a boiler that mitigates the known art drawbacks highlighted herein.

In particular, it is an object of the present invention to produce a feeding assembly that is reliable and able to simply and cost-effectively avoid damage to its components deriving from possible backfires.

In accordance with the present invention a feeding assembly for feeding at least one fuel gas to a burner of a boiler is produced, the feeding assembly comprising:

Thanks to the present invention, it is possible to protect the components of the boiler from a backfire in a simple, cost-effective and reliable manner.

In case of backfire, a return flow defined by a hot gas and at least partly still in a combustion phase returns to the feeding duct in a return direction opposite to the feeding direction of the gas flow. Thanks to the safety device arranged in the feeding duct, this return flow is substantially slowed down and hindered by the stagnation zone.

In other words, the stagnation zone contains the advancement of the return flow preventing said flow from advancing further along the feeding duct in the return direction.

In practice, the safety device produced in accordance with the present invention contains a backfire without the need to use moving parts or electronic components, such as for example sensors or control units, thus increasing the simplicity and reliability of the feeding assembly.

In particular, the safety device is arranged in the feeding duct so as to define at least one passage restriction for the feeding flow of the fuel gas.

Therefore, the flow of fuel gas is accelerated at the inlet of the passage restriction. In this way, in the passage restriction it is possible to determine a resistance to advancement of the return flow of gas in the return direction.

In particular, the safety device comprises a stagnation chamber, which delimits the stagnation zone and is provided with an inlet opening directed toward the burner defining an access to the stagnation chamber.

In this way, it is possible to confine the return flow of gas inside the stagnation zone, preventing said return flow from advancing along the feeding duct in the return direction.

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

In this way, the return flow is trapped in the stagnation chamber and subsequently discharged in the feeding duct and fed back to the burner.

In particular, the safety device comprises a blocking wall, which delimits, at least in part, the stagnation chamber and extends transversely with respect to the feeding direction so as to block the return flow of gas in the return direction in case of backfire.

In particular, the blocking wall has an aerodynamic profile in the feeding direction so as to limit pressure drops of the fuel gas flow fed in the feeding direction.

Thanks to the aerodynamic profile, the safety device ensures a stability of the feeding flow of fuel gas in the feeding direction. In other words, the safety device helps to prevent turbulence in the feed flow of fuel gas.

An aerodynamic profile is a shape designed to offer minimum resistance when it is hit by an incident gas flow in the feeding direction.

Preferably, the aerodynamic profile reduces the occurrence of vortices and instability in the feeding flow.

In particular, the blocking wall comprises a first portion having a first face of impact with the feeding flow of the fuel gas in the feeding direction, and a second portion having a second face of impact with the feeding flow of the fuel gas in the feeding direction; the first and second faces being oriented so as to determine a leading edge for the feeding flow of fuel gas in the feeding direction.

In this way, it is possible to reduce the resistance of the safety device to the flow of fuel gas in the feeding direction and at the same time contain the advancement of the return flow along the feeding duct in the return direction.

In particular, the first and second faces are oriented so as to determine between them a leading angle comprised between 10° and 120°.

In more detail, small leading angles correspond to a greater length of the safety device measured along the feeding direction and a lower fluid-dynamic resistance to the flow of fuel gas in the feeding direction.

In contrast, large leading angles correspond to a shorter length of the safety device measured along the feeding direction and to a greater fluid-dynamic resistance to the flow of fuel gas in the feeding direction.

In particular, the safety device comprises a first lateral wall and a second lateral wall, each of which is arranged at a respective end of the blocking wall so as to define the stagnation chamber together with the blocking wall; the first lateral wall and the second lateral wall extending transversely with respect to the blocking wall.

In this way, it is possible to delimit the stagnation zone on three sides to effectively block the advancement of the flame in the return direction.

In practice, thanks to the first and second lateral walls, the stagnation chamber is closed on three sides and is open only in the return direction.

In particular, the blocking wall and/or the first lateral wall and/or the second lateral wall are made of a heat conducting material.

In this way, in case of backfire, it is possible to extinguish the flame confined inside the stagnation zone and quickly dissipate the heat.

A further object of the present invention is to produce a burner assembly that mitigates the drawbacks of the known art.

In accordance with the present invention, a burner assembly comprising the feeding assembly as previously described and a burner configured to burn fuel gas fed by the feeding assembly is produced.

A further object of the present invention is to produce a boiler that mitigates the drawbacks of the known art.

In accordance with the present invention, a boiler comprising the burner assembly as previously described is produced.

In this way, it is possible to protect the components of the boiler from the heat generated by a backfire without the need to arrange moving parts or electronic components in the boiler, such as for example sensors or control units, increasing the simplicity and reliability of the boiler.

With reference to, reference numberindicates, as a whole, a boiler that can be used in a heating system. In particular, the boilercan be employed in the domestic or industrial field or in any other field that requires a passage of heat, by means of combustion, to a liquid distributed in a heating system.

In the case described and illustrated herein, but not limited to the present invention, the boileris of the “condensing” type. In particular, the fuel gas employed is a high-flame-speed gas, such as for example hydrogen or methane or LPG or a mixture of hydrogen and air or a mixture of methane and air or a mixture of methane and hydrogen. It is understood that within the scope of the present invention, any gas or any mixture suitable for causing a combustion reaction can be employed.

With reference to, the boilercomprises a burner assemblycomprising a burnerconfigured to burn at least one fuel gas; and a feeding assemblyconfigured to feed the fuel gas to the burner.

The feeding assemblycomprises a feeding ductconfigured to feed to the burnera feeding flow of fuel gas in a feeding direction D1; and a safety device, which is arranged in the feeding ductand is shaped to define a stagnation zoneconfigured to contain a return flow coming from the burnerand having a return direction D2 substantially opposite to the feeding direction D1.

In particular, the portion of the feeding ductin which the safety deviceis housed extends along a longitudinal axis A1 and the burnerextends along a longitudinal axis A2 substantially perpendicular to the longitudinal axis A1.

In addition, the boilercomprises an air feeding inlet; a gas feeding inlet, such as for example hydrogen or methane; a suction deviceconfigured to suck air and gas through the respective inletsand; and a mixing deviceconfigured to mix sucked air and gases so as to generate the fuel gas.

With reference to, the boilercomprises an outer casing; a heat exchanger, which is fed by the heating gases generated by the burnerand is configured to heat a working fluid; a drainage assembly, which is arranged downstream of the heat exchangerand is configured to convey to a condensate drainage systema condensate liquid generated by the condensation, at least partial, of the heating gases; and an evacuation ductof the heating gases.

In particular, the heat exchangercomprises a feeding ductof the working fluid, which has an inlet portionfor the entry of the working fluid into the boilerand an outlet portionfor the exit of the working fluid from the boiler.

The drainage assemblycomprises a collection tankfor collecting the condensate liquid in the heat exchanger; a siphonfed with the condensate liquid; and a duct, which connects the collection tankto the siphon.

In particular, the siphonis configured to convey the condensate liquid towards the condensate drainage systemand, at the same time, to obstruct the passage of the heating gases through the siphon.