HYDROGEN TO A BURNER OF A BOILER AND BOILER COMPRISING SAID

FEEDING ASSEMBLY"

CROSS-REFERENCE TO RELATED APPLICATIONS

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 .

TECHNICAL FIELD

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 .

BACKGROUND

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 normal ly 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 obj ect of the present invention to reali ze a feeding assembly for feeding a fuel gas to the burner of a boiler that mitigates the known art drawbacks highlighted herein .

SUMMARY

In particular, it is an obj ect of the present invention to produce a feeding assembly that is reliable and able to simply and cost-ef fectively 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 :

- a feeding duct configured to feed to the burner a feeding flow of fuel gas in a feeding direction; and

- a safety device , which is arranged in the feeding duct and is shaped to define a stagnation zone conf igured to contain a return flow of gas from the burner in the feeding duct in a return direction substantially opposite to the feeding direction .

Thanks to the present invention, it is possible to protect the components of the boiler from a backfire in a simple , cost-ef fective 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 i s 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 of fer 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 ef fectively 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 obj ect 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 compris ing the feeding assembly as previously described and a burner configured to burn fuel gas fed by the feeding assembly is produced .

A further obj ect 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 .

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become apparent from the following description of a non-limiting example embodiment , with reference to the accompanying Figures , wherein :

- Figure 1 is a schematic view of a boiler produced in accordance with the present invention;

- Figure 2 is a schematic view of a detail of the boiler of Figure 1 ;

- Figure 3 is a section view, with parts removed for clarity, of a detail of the boiler of Figure 1 ;

- Figures 4 and 5 are perspective views of respective embodiments of a boiler safety device of Figure 1 ; and

- Figure 6 is a section view, with parts removed for clarity, of a detail of a boiler supply assembly of Figure 1 .

DESCRIPTION OF EMBODIMENTS

With reference to Figure 1 , reference number 1 indicates , as a whole , a boiler that can be used in a heating system . In particular, the boiler 1 can 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 boiler 1 is 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 Figures 1 and 2 , the boiler 1 comprises a burner assembly 32 comprising a burner 2 configured to burn at least one fuel gas ; and a feeding assembly 15 configured to feed the fuel gas to the burner 2 .

The feeding assembly 15 comprises a feeding duct 3 configured to feed to the burner 2 a feeding flow of fuel gas in a feeding direction DI ; and a safety device 4 , which is arranged in the feeding duct 3 and is shaped to define a stagnation zone 9 configured to contain a return flow coming from the burner 2 and having a return direction D2 substantially opposite to the feeding direction DI .

In particular, the portion of the feeding duct 3 in which the safety device 4 is housed extends along a longitudinal axis Al and the burner 2 extends along a longitudinal axis A2 substantially perpendicular to the longitudinal axis Al .

In addition, the boiler 1 comprises an air feeding inlet 5 ; a gas feeding inlet 6 , such as for example hydrogen or methane ; a suction device 7 configured to suck air and gas through the respective inlets 5 and 6 ; and a mixing device 8 configured to mix sucked air and gases so as to generate the fuel gas .

With reference to Figure 1 , the boiler 1 comprises an outer casing 10 ; a heat exchanger 11 , which is fed by the heating gases generated by the burner 2 and is conf igured to heat a working fluid; a drainage assembly 12 , which is arranged downstream of the heat exchanger 11 and is configured to convey to a condensate drainage system 13 a condensate liquid generated by the condensation, at least partial , of the heating gases ; and an evacuation duct 14 of the heating gases .

In particular, the heat exchanger 11 comprises a feeding duct 16 of the working fluid, which has an inlet portion 17 for the entry of the working fluid into the boiler 1 and an outlet portion 18 for the exit of the working fluid from the boiler 1 .

The drainage assembly 12 comprises a collection tank 19 for collecting the condensate liquid in the heat exchanger 11 ; a siphon 20 fed with the condensate liquid; and a duct 21 , which connects the collection tank 19 to the siphon 20 .

In particular, the siphon 20 is configured to convey the condensate liquid towards the condensate drainage system 13 and, at the same time , to obstruct the passage of the heating gases through the siphon 20 .

With reference to Figures 3 and 4 , the safety device 4 comprises a stagnation chamber 33 , which delimits the stagnation zone 9 and is provided with an inlet opening 31 directed toward the burner 2 defining an access to the stagnation chamber 33 . In practice , the inlet opening 31 allows the entry into the stagnation zone 9 of a return flow of gas from the burner in the return direction D2 in case of backfire .

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

In particular, the safety device 4 comprises a blocking wall 22 , which delimits , at least in part , the stagnation chamber 33 and extends transversely with respect to the feeding direction DI so as to block the return flow in the return direction D2 in case of backfire . In particular, the blocking wall 22 has an aerodynamic profile in the feeding direction DI .

In the case described and illustrated herein, but not limited to the present invention, the blocking wall 22 comprises a portion 23 having a face 35 ( Figures 4 and 5 ) of impact with the feeding flow of the fuel gas in the feeding direction DI , and a portion 24 having a face 36 ( Figures 4 and 5 ) of impact with the feeding flow of the fuel gas in the feeding direction DI .

In particular, the face 35 and the face 36 are oriented so as to determine between them a leading edge for the feeding flow of fuel gas in the feeding direction DI . In more detail , the face 35 and the face 36 ( Figures 4 and 5 ) are oriented so as to determine between them a leading angle a comprised between 10 ° and 120 ° . In particular, portions 23 and 24 are integrally coupled to each other .

In accordance with alternative embodiments , not shown in the accompanying figures , the blocking wall 22 can assume any configuration adapted to block the return flow of gas in the return direction D2 . By way of example , the blocking wall may be "C"- shaped, in which the concave face of the blocking wall faces the burner 2 .

Furthermore , the safety device 4 comprises a lateral wall 25 and a lateral wall 26 , each of which is arranged at a respective end of the blocking wall 22 so as to delimit the stagnation zone 9 together with the blocking wall 22 . In more detail , the lateral wall s 25 and 26 delimit the inlet opening 31 .

In particular, the lateral wall 25 is integrally coupled to the portion 23 and the lateral wall 26 is integrally coupled to the portion 24 . In other words , portions 23 and 24 and lateral walls 25 and 26 are made integral in one piece .

In the case described and illustrated herein, the lateral wall 25 and the lateral wall 26 extend transversely with respect to the blocking wall 22 . In particular, the portion 23 and the lateral wall 25 determine between them an angle p greater than 90 ° , preferably comprised between 120 ° and 150 ° , and the portion 24 and the lateral wall 26 determine between them an angle y greater than 90 ° , preferably comprised between 120 ° and 150 ° .

In accordance with an embodiment , the portion 23 and/or the portion 24 and/or the lateral wall 25 and/or the lateral wall 26 are made of a heat conducting material , preferably of a metallic material . In particular, the safety device 4 is made by bending a portion of metal plate so as to form the portions 23 , 24 and the lateral walls 25 , 26 .

With reference to Figure 3 , the safety device 4 is arranged in the feeding duct 3 so as to define two passage restrictions 27 for the feeding flow of the fuel gas .

In particular, each lateral wall 25 , 26 and a wall 28 of the feeding duct 3 delimit respective passage restrictions 27 for the flow o f fuel gas in the feeding direction DI . In practice , the blocking wall 22 is shaped to direct the flow of fuel gas in the passage restrictions 27 , in particular so as to divide the flow of fuel gas in the feeding direction DI into two separate flows .

In more detail , in each passage restriction 27 , the distance dl , d2 between the respective lateral wall 25 , 26 and the wall 28 of the feeding duct 3 along a direction D3 substantially perpendicular to the direction Dl is smaller than a dimension d3 of the feeding duct 3 along said direction D3 .

In the case described and illustrated herein, each lateral wall 25 , 26 extends in a direction substantially parallel to the longitudinal axis Al and, consequently, the respective distances dl and d2 are substantially constant along the longitudinal axis Al .

In accordance with an alternative embodiment , not shown in the accompanying figures , each lateral wall 25 , 26 extends transversely to the longitudinal axis Al . In such configuration, the distances dl and d2 of the lateral walls 25 and 26 vary along the longitudinal axis Al , in particular said distances dl and d2 decrease in the direction Dl .

With reference to Figure 4 , the safety device 4 comprises two fixing flaps 29 , configured to allow the safety device 4 to be secured to a wall of the feeding duct 3 . In particular, each fixing flap 29 is provided with a through opening 30 configured to allow the insertion of a fixing means , such as for example a screw or a rivet , through the respective fixing flap 29 .

In accordance with an embodiment , not shown in the accompanying Figures , the safety device 4 comprises at least one housing for sensors , such as for example speed and/or pressure sensors , or for further devices , such as for example thermostats and/or thermal fuses , to control the state of the flow of fuel gases and prevent the ignition of the boiler 1 in case of damage caused by backfire .

With reference to Figure 5 , a further embodiment of the safety device 4 is shown . In accordance with said embodiment , the safety device 4 comprises at least one flow recti fier element 34 , which is arranged in one of the passage restrictions 27 and i s configured to determine a laminar feeding flow of the fuel gas in the respective passage restriction 27 . In other words , the flow recti fier element 34 is shaped to avoid vortices in the feed flow of fuel gas in the feeding direction DI .

In particular, the safety device 4 comprises two flow recti fier elements 34 , each of which is secured to a respective lateral wall 25 , 26 outside the stagnation zone 9 . In more detail , each flow recti fier element 34 i s arranged in the respective passage restriction 27 .

In the case described and illustrated herein, but not limited to the present invention, each flow recti fier element 34 comprises a grid made of metallic material .

Also , each flow recti fier element 34 is configured to dissipate heat transmitted by the gases of the return flow to the safety device 4 .

With reference to Figure 6 , the feeding duct 3 has a section of substantially rectangular shape along a cutting plane V-V perpendicular to the longitudinal axis Al ( Figure 3 ) . In particular, the feeding duct 3 has a dimension d4 along a direction D4 substantially perpendicular to the direction D3 of the dimension d3 and to the longitudinal axis Al . The safety device 4 extends inside the feeding duct 3 for the entire dimension d4 . In more detail , the blocking wall 22 and the lateral walls 25 and 26 extend along the direction D4 for a dimension d5 substantially equal to the dimension d4 . In other words , the blocking wall 22 and the lateral walls 25 and 26 are configured to block the return flow of the gases in the feeding duct 3 along the entire dimension d4 .

In the case described and illustrated herein, the distances dl and d2 of the passage restrictions 27 are constant along the direction D4 . In other words , the lateral walls 25 and 26 extend in a direction substantially parallel to the direction D4 .

In accordance with an alternative embodiment , not shown in the attached Figures , the feeding duct 3 has a section of substantially circular shape along a cutting plane V-V perpendicular to the longitudinal axis Al ( Figure 3 ) . By way of example , in such configuration, the blocking wall comprises four portions inclined to each other so as to form a straight square-based pyramid with the base facing the burner 2 .

In use and with reference to Figure 1 , the suction device 7 determines the suction of air from the inlet 5 and of gas from the inlet 6 . The mixing device 8 mixes sucked air and gas so as to generate the fuel gas , which is fed from the suction device 7 to the burner 2 through the feeding duct 3 .

The burner 2 burns the fuel gas fed so as to generate a flame and transmit heat to the heat exchanger 11 .

With reference to Figure 3 , when the fuel gas is fed into the feeding duct 3 in the feeding direction DI , the safety device 4 directs the flow o f fuel gas in the passage restrictions 27 . In particular, the safety device 4 determines an acceleration of the flow of fuel gas in the feeding direction DI when the fuel gas enters the passage restrictions 27 since the area transverse to the flow of fuel gas of the passage restrictions 27 is smaller than the area transverse to the flow of fuel gas of the feeding duct 3 . In other words , the speed of the flow of fuel gas in the passage restrictions 27 is increased .

In the case described and illustrated herein, the blocking walls 23 and 24 of the blocking wall 22 contribute to channel the flow of fuel gas in the passage restrictions 27 by dividing the flow of fuel gas into two separate branches .

In stagnation zone 9 the fuel gas stagnates . In other words , in the stagnation zone 9 the fuel gas does not flow in the feeding direction DI towards the burner 2 .

When, for example , due to a reduction of the speed of the flow of fuel gas in the feeding duct 3 , a backfire occurs the flame advances in the return direction D2 from the burner 2 in the feeding duct 3 .

In such circumstance , in the passage restrictions 27 the flame encounters a resistance to advancement in the return direction D2 since in the passage restrictions 27 the speed of the flow of fuel gas in the feeding direction DI is maximum . Therefore , the flame is directed and confined in the stagnation zone 9 , in which, thanks to the blocking walls 23 and 24 and to the lateral wall s 25 and 26 , the flame is extinguished and the heat generated by the flame is quickly dissipated .

Finally, it is evident that variations can be made to the present invention with respect to the described embodiments without thereby departing from the scope of protection of the appended claims .