Premix gas heating system for h2

Abstract

A premix gas heating system comprising: a fan assembly (2) configured to supply a premix air-gas flow required for combustion, wherein the fuel gas in the premix air-gas flow comprises at least 20% by volume of hydrogen; a burner (5) comprising a plurality of orifices, wherein the plurality of orifices provide a free pass area defined as an area allowing the premix air-gas flow to flow from an area upstream of the burner (5) to an area where a combustion flame is generated; a load controller configured to adjust an output load of the burner (5) to cause the heating system to regulate between a minimum load and a maximum load, wherein a ratio between the minimum load and the maximum load is at least 4, wherein the minimum load of the heating system is set such that a combustion index defined as a ratio between the minimum load and the free pass area of the burner is between 4E06 and 6E07.

Description

Technical Field

[0001] This invention relates to a combustion unit for a heating system, and more particularly to a premixed gas burner. The invention also relates to a method for operating and manufacturing a premixed gas heating system.

[0002] This heating system serves as a boiler. The invention also relates to a method for heating water within the heating system. Background Technology

[0003] A boiler is a device in which water to be heated flows through a heat exchanger that works in conjunction with a gas burner. Existing technology for producing hot water exists. Boilers for domestic use typically have combustion units internally comprising base elements and an outer sheath, within which a combustion chamber is defined to house the heat exchanger through which the fluid to be heated flows.

[0004] Typically, heat exchangers are formed from coiled tubes and positioned close to the outer sheath.

[0005] The outer sheath is closed at one end by a base component and at the opposite end by a cover through which the unburned premixed air-gas mixture from the fan unit flows.

[0006] Boilers with premixed gas burners typically have systems for mixing and conveying gaseous fuel and combustion air, systems for conveying the air-gas mixture, and a burner head on the outer surface of which a flame is generated.

[0007] The boiler also includes piping configured to deliver the unburned air-gas mixture from the fan unit to the burner.

[0008] The high-temperature flue gas generated by the flame originating from the head of the burner is forced to flow through the heat exchanger to transfer heat to the fluid flowing through the heat exchanger.

[0009] Patent documents US2020386482A1, EP3770528A2 and EP3690345A1 describe examples of combustion units for prior art boilers.

[0010] In these combustion units, the burner heats up due to the flame at the burner head and may therefore undesirably transfer heat to components located upstream of the burner, particularly the unit's cover. The unit described in the aforementioned document therefore includes insulation material to prevent overheating of the components upstream of the burner. This insulation material has a limited lifespan because it is continuously exposed to very high temperatures and therefore requires periodic replacement. On the other hand, using such insulation material results in a very bulky product and high cost.

[0011] For this reason, there is a need to create combustion units that can be cooled without using the aforementioned insulation materials, in order to keep the unit in the most compact form possible and reduce construction and maintenance costs.

[0012] In this context, patent document WO2015150902A1 describes a premixed gas burner comprising a flange, a conveyor, a burner head, and a distributor located between the burner head and the conveyor. The burner is enclosedly sealed between the flange and the conveyor, and during operation of the burner, a mixture of air and fuel gas flowing through the conveyor passes through the distributor to the burner head to form a flame on the outer surface of the burner head. The distributor has a plurality of orifices of different sizes, while the burner head comprises a non-perforated outer peripheral portion and a perforated central portion. Therefore, the air and gas mixture flowing from the distributor element toward the burner head contacts the outer peripheral portion of the burner head and creates a circulation that cools the burner.

[0013] The aforementioned invention provides a solution for cooling the burner head without the need for insulation materials. However, this invention does not provide any solution for cooling the conveyor, which is in direct contact with the burner and distributor. For this reason, there is a need for better cooling.

[0014] Another problem with conventional combustion units involves the piping being entirely formed within the delivery element (i.e., the cover) to connect the fan unit to the latter. This construction increases the overall size of the unit and necessitates the removal of the door leading to the burner or combustion chamber each time the fan unit is removed. Patent document EP2306112A1 provides another example of a combustion unit. Furthermore, the burners used in conventional units are natural gas burners. However, the use of these burners is criticized because carbon dioxide emissions lead to severe environmental impacts. Using gas burners utilizing 100% hydrogen or a mixture of natural gas and hydrogen constitutes a promising approach to reducing carbon dioxide emissions. However, hydrogen, or gaseous fuels with a very high hydrogen content, has different combustion characteristics than natural gas. These different combustion characteristics lead to a range of problems, such as burner flashback.

[0015] Patent document WO2020182902A1 describes a method using a premixed gas burner that can be adjusted between minimum and full load, wherein the fuel gas supplied to the burner comprises at least 20% hydrogen by volume. Furthermore, patent document WO9523315A1 describes another known example of an adjustable heating system. However, there is a growing need in the art to create a more efficient heating system capable of using hydrogen, and a method for using such a heating system. Summary of the Invention

[0016] The purpose of this invention is to provide a combustion unit for a heating system and a method for heating water in a heating system that overcomes the above-mentioned defects of the prior art.

[0017] In particular, the object of the present invention is to provide a combustion unit for a heating system that is easy to use and maintain, has improved cooling capacity without the need for insulation materials, has a smaller overall size, maintains a high level of reliability, and is relatively easy to manufacture at a better cost.

[0018] Another object of the present invention is to provide a regulating heating system and a method of using the same, which is capable of operating in a stable, controlled and efficient manner using an air-H2 mixture.

[0019] The objective is achieved entirely by the combustion unit and method for a heating system according to the invention, as characterized in the appended claims.

[0020] According to one aspect of the present invention, a combustion unit for a heating system is provided. This combustion unit may also be defined as a "heat exchange unit".

[0021] The combustion unit includes a fan unit (also referred to as the "fan assembly" in this specification). The fan unit is configured to supply the premixed air-gas flow required for combustion.

[0022] It should be noted that the fan unit includes a fan, which includes an impeller (with a corresponding volute and a diffuser when needed) and an electric motor that rotates it. The fan unit also includes a gas supply and an air inlet; the gas supply may be located upstream or downstream of the fan.

[0023] The combustion unit includes a combustion chamber. The combustion chamber preferably extends along a longitudinal axis from a first end to a second end. The combustion unit (i.e., the unit) includes a cover. The cover is configured to close the first end of the combustion chamber. The unit includes a burner. A combustion flame is formed on the outer surface of the burner. According to one example, the burner has a convex shape. This shape allows the burner to have mechanical stability without deformation due to thermal load. Furthermore, this shape allows for optimal flame distribution, avoiding the superposition of individual flames and contributing to cleaner combustion. According to another example, the burner may have a flat shape.

[0024] The burner includes a central portion (also referred to as the "central portion" in this specification). The central portion of the burner is perforated. The burner may also include an outer peripheral portion (also referred to as the "outer peripheral portion" in this specification). The outer peripheral portion of the burner is non-perforated. The unit also includes a distributor. According to one example, the distributor has a convex shape. The convex shape of the burner and the distributor reduces the axial dimension of the assembly formed by the burner and the distributor, further making the assembly compact. The distributor includes an outer peripheral portion (also referred to as the "outer peripheral portion" in this specification) with an opening. The distributor is located upstream of the burner. The distributor is configured to supply a premixed air-gas flow to the burner. The burner is positioned such that the outer peripheral portion of the distributor faces the outer peripheral portion of the burner. This configuration enables the circulation of an air-gas flow between the outer peripheral portion of the burner and the outer peripheral portion of the distributor, thereby cooling the burner. The unit may include a flange. The flange is configured to connect a cap to the burner. The unit includes a heat exchanger. The heat exchanger is preferably formed of a tube wound into a coil. This coil is arranged around a longitudinal axis to surround the combustion chamber. The coil has multiple helical portions (also referred to as "wound portions" in this specification). The first helical portion of the coil is close to the burner. The last helical portion of the coil is away from the burner. According to one example, the flange has a receiving surface for receiving the first helical portion of the coil for heat exchange through direct contact with it. This configuration allows for a large contact surface for heat exchange between the flange and the first helical portion of the coil, preventing overheating of the flange exposed to the hot flame of the burner, since heat exchange will occur between the flange and the heat exchanger. For this reason, cooling of the burner and downstream components can be optimized and overheating prevented without the use of insulation materials. According to one example, the minimum absolute (also referred to as "overall" distance) between the coil for heat exchange and the burner varies between a minimum and a maximum value relative to the angular position about the longitudinal axis. The minimum absolute distance is less than 15 mm. The maximum minimum absolute distance is less than 25 mm. The minimum absolute distance is preferably less than 8 mm. The maximum absolute distance is preferably less than 18 mm. According to one example, the minimum axial distance along the longitudinal axis between the heat exchange coil and the burner varies between a minimum and a maximum value. The minimum axial distance is less than 20 mm. The maximum axial distance is less than 30 mm. The minimum axial distance is preferably less than 12 mm. The maximum axial distance is preferably less than 22 mm. These minimum distances ensure the most compact shape of the unit and allow a small portion of the flange to be exposed to the hot flame of the burner, which is advantageous because it protects the flange from overheating.

[0025] The burner and distributor form a burner unit (also referred to as a "burner assembly" in this specification). According to one example, the burner unit is connected to a flange in a first connection region via one or more connecting elements. A cover is secured to the flange in a second connection region. The second connection region is different from and separate from the first connection region. This configuration protects the cover from overheating because there is no direct contact between the cover and the burner unit.

[0026] The unit also includes a feed chamber. According to one example, the feed chamber is defined between the cover and the distributor. The flange may include lugs. The lugs extend radially relative to the longitudinal axis. The flange is configured to receive the fan unit connected thereto. This arrangement creates the possibility of accessing the combustion chamber by simply removing the cover, thus providing easier maintenance. Alternatively, the fan unit may be positioned directly on the cover.

[0027] According to one example, the lug of the flange, in conjunction with the cap, defines the feed pipe. The feed pipe is configured to deliver a premixed air-gas flow supplied from the fan unit to the feed chamber. The premixed air-gas flow flows forward in the combustion chamber from a first end to a second end. According to one example, the feed pipe has an inlet located in the outlet of the fan unit and an outlet leading to the feed chamber. Preferably, the premixed air-gas flow within the feed pipe is oriented in an inlet direction having at least one component pointing longitudinally in the direction opposite to the forward direction.

[0028] According to one example, the premixed air-gas flow within the feed tube is oriented at the outlet of the supply pipe in an outlet direction having at least one component pointing radially toward the longitudinal axis. This configuration helps to further cool the cap as the air-gas flow contacts the cap at the outlet of the feed tube.

[0029] The cover has an inner surface. This inner surface defines the combustion chamber. Preferably, the inner surface of the cover has a protrusion in its central portion that extends into the feed chamber, thus forming an annular portion within the feed chamber. This annular portion, in conjunction with an opening in the outer peripheral portion of the distributor, provides a manifold for distributing the premixed air-gas supplied by the fan unit to the opening in the outer peripheral portion of the distributor. This configuration directs the air-gas flow toward the opening in the outer peripheral portion of the distributor, thus resulting in better cooling of the combustor.

[0030] It should be noted that the protrusion surrounds a certain volume of air located between the cover and the burner; this volume of air communicates with the feed chamber through a hole. This volume of air functions as an acoustic resonator, used to cut off unwanted frequencies.

[0031] The unit may include a gasket disposed between the cap and the flange for sealing the cap. The gasket for sealing the cap has a first portion and a second portion. According to one embodiment, the first portion of the gasket for sealing the cap is annular and positioned about a longitudinal axis. The second portion is preferably offset relative to the longitudinal axis and contacts a lug of the flange.

[0032] The distributor may include multiple holes in its central portion. According to one example, the holes in the central portion of the distributor have different dimensions from the openings in the outer peripheral portion. The holes have a smaller diameter than the openings in the outer peripheral portion of the distributor, protecting the cover from the radiation of the flame on the burner. Preferably, the openings in the outer peripheral portion form at least 60% of the total surface area of ​​the holes in the distributor. This arrangement allows for better air-gas flow circulation between the distributor and the outer peripheral portion of the burner.

[0033] It should be noted that when referring to the “diameter” of a hole or opening in this invention, it does not mean that the hole or opening is limited to having a circular shape, but generally means that the area of ​​the hole or opening is equivalent to that of a circle having that diameter.

[0034] According to one aspect of the invention, a method for heating water in a heating system is also provided. The method includes the step of arranging a fan unit. The method includes the step of arranging a cover. The method includes the step of arranging a burner having a convex shape. The method includes the step of arranging a distributor having a convex shape.

[0035] The method includes the step of arranging a ring for heat exchange. The ring for heat exchange extends around a longitudinal axis to surround a combustion chamber. The heat exchanger has multiple helical portions, including a first helical portion near the burner and a final helical portion away from the burner. The method includes the step of arranging a cover for sealing a first end of the combustion chamber.

[0036] The method may include the step of arranging a burner having a central perforated region and a peripheral non-perforated region. The method may also include the step of arranging a distributor having an outer peripheral portion with openings. The method includes the step of positioning the distributor upstream of the burner such that the outer peripheral portion of the distributor faces the outer peripheral portion of the burner. The method may include the step of arranging a flange for connection with a cap and the burner. According to an example, the method includes the step of arranging a flange having a receiving surface. The receiving surface receives a first spiral portion of a receiving ring for heat exchange through direct contact with it.

[0037] The method includes the step of circulating water in a coil for heat exchange. The method also includes the step of supplying a premix of fuel gas and air to the burner via a distributor. Furthermore, the method includes the step of directly securing the burner unit, formed by the burner and distributor, to a flange. According to one example, a fan unit is connected to the flange, thereby enabling access to the burner unit formed by the burner and distributor by removing the cover without removing the fan unit. The method includes the step of having a feed chamber between the cover and the distributor and conveying a premixed air-gas flow to the feed chamber via a duct defined by the flange and the cover through the fan unit. Preferably, the premixed air-gas flow is conveyed to the feed chamber in an orientation having a radial component pointing towards the longitudinal axis, thereby generating an air-gas flow within the feed chamber that contacts the inner surface of the cover.

[0038] According to one aspect of the present invention, a premixed gas heating system is provided. In this specification, when referring to a premixed gas heating system, a surface-stable premixed gas heating system is desired. This heating system, regardless of the fuel used, may include a combustion unit according to one or more aspects of the present invention.

[0039] The heating system includes a fan unit. The fan unit is configured to supply the premixed air-gas stream required for combustion. According to one example, the fuel gas in the premixed air-gas stream contains at least 20% hydrogen by volume. Alternatively, the heating system may use a natural gas stream.

[0040] The heating system includes a burner. The burner includes multiple orifices. These orifices provide an effective delivery area (also referred to herein as "free passage area"). This effective delivery area is defined as the area allowing a premixed air-gas flow from a feed chamber upstream of the combustion chamber to the combustion chamber that produces the combustion flame. The heating system also includes a load controller. The load controller is configured to adjust the burner's outlet load (also referred to as "output load") to regulate the heating system between a minimum load and a maximum load. In other words, the load controller adjusts the output load of the heating system. According to one example, the ratio between the maximum load and the minimum load is at least 4. According to one example, the minimum load of the heating system is set to keep the combustion index between 4 E06 and 6 E07. The combustion index is defined as the ratio between the minimum load and the effective delivery area of ​​the burner.

[0041] It should be noted that the expression "minimum load" refers to the minimum power load in watts. It should also be noted that the effective delivery area is the area in square meters in the context of the calorific value.

[0042] According to another example, the combustion index of the heating system is between 8 E06 and 2 E07. The burner's multiple orifices may include a first set of orifices with a first diameter and a second set of orifices with a second diameter. According to one example, the first diameter is smaller than the second diameter. Preferably, the second diameter is increased by at least 30% relative to the first diameter. According to one example, the area covered by the second set of orifices is less than 40% of the total effective delivery area of ​​the burner. According to one example, the ratio between the minimum load and the maximum load of the heating system is equal to 8. A larger ratio between the minimum load and the maximum load reduces the continuous on / off cycles of the heating system that adversely affect its efficiency and cause unnecessary wear on its components. According to one example, the fuel gas (also referred to as "combustible gas" in this specification) supplied to the burner in the premixed air-gas stream contains at least 60% hydrogen by volume. According to another example, the fuel gas supplied to the burner in the premixed air-gas stream is 100% hydrogen. This approach helps reduce emissions from the heating system.

[0043] The burner may include a central portion and an outer peripheral portion. The central portion is perforated, while the outer peripheral portion is non-perforated. The system also includes a distributor. According to one example, the distributor includes an outer peripheral portion provided with openings. The distributor is located upstream of the burner for delivering a premixed air-gas flow to the burner. Preferably, the distributor is positioned such that its outer peripheral portion faces the outer peripheral portion of the burner. This configuration results in cooling of the burner because the air-gas flow from the distributor contacts the non-perforated outer peripheral portion of the burner before exiting through the openings in the central portion of the burner, creating a circulation capable of removing heat from the burner.

[0044] The distributor may include multiple holes in its central portion. According to one example, the holes in the central portion of the distributor have different dimensions than the openings in the outer peripheral portion. Preferably, the diameter of the holes in the central portion is smaller than the diameter of the openings in the distributor. Preferably, the openings in the outer peripheral portion form at least 60% of the total area of ​​the holes in the distributor. This allows for better circulation of air-gas flow between the outer peripheral portion of the distributor and the non-perforated areas in the burner. According to one example, the burner has a cylindrical shape. Alternatively, the burner has a convex shape. The convex shape of the burner improves the mechanical stability of the components and prevents deformation due to thermal load. Simultaneously, the convex shape of the burner can reduce the overall size of the heating system.

[0045] According to one example, the central portion of the burner includes an interior (also referred to as the "inner portion" in this specification) and an exterior (also referred to as the "outer portion" in this specification). According to one example, the interior of the central portion of the burner is non-perforated. Alternatively, according to another example, the exterior of the central portion of the burner is perforated. The exterior of the central portion of the burner may be an annular region surrounding the interior of the central portion of the burner. Additionally, the interior of the burner has a perforated region facing the distributor.

[0046] Furthermore, according to one example, the central portion of the distributor includes a central interior (also referred to herein as the "inner central portion") and a central exterior (also referred to herein as the "outer central portion"). According to one example, both the central interior and the central exterior are perforated and can be separated by a non-perforated region. The non-perforated region of the distributor can be an annular region. According to one example, the central exterior of the distributor faces the exterior of the central portion of the burner where the perforation exists and therefore the flame is present. Furthermore, the central interior of the distributor faces the non-perforated interior of the central portion of the burner.

[0047] Furthermore, according to one example, the outer perimeter of the burner's central section extends further than the outer perimeter of the distributor's central section. In other words, the effective delivery area of ​​the burner is larger than that of the distributor.

[0048] For this reason, it is possible to optimize burner cooling and improve the performance of the heating system.

[0049] In particular, according to one aspect of the invention, the orifice in the outer center of the distributor is aligned with the orifice in the outer center of the burner. For this reason, in the outer center of the burner where the flame is present, the premixed air-gas flow passes directly through the orifice of the distributor aligned with the burner's orifice at a sufficiently high velocity; thus, the orifice in the burner can be properly supplied, thereby uniformly distributing the flame and improving the stability of the flame on the burner surface and preventing the flame from returning to the interior of the combustion chamber.

[0050] In addition, such as Figure 9 As shown, in the perforated outer peripheral portion of the burner and inside the perforated central portion of the burner, the premixed air-gas flow from the distributor contacts the burner before exiting the perforations in the outer part of the central portion. For this reason, the area near the perforations of the burner, where the temperature is highest due to the flame, is cooled.

[0051] Furthermore, the contact between the air-gas flow and the area near the burner orifice generates turbulence in the movement of the air-gas mixture due to the change in direction.

[0052] In one example, the load controller has access to memory. The memory contains multiple reference ranges for values ​​used in the combustion index. Each reference range provides a range of effective adjustment for the heating system. The load controller is programmed to provide the user with multiple operating modes.

[0053] Each of the multiple operating modes corresponds to a specific range among the multiple reference ranges. The load controller is programmed to set the minimum load of the heating system to a value within the reference range corresponding to the user-selected operating mode. According to one aspect of the invention, a burner unit is provided. The burner unit can be used in a premixed gas heating system. For example, the burner unit can be used in a heating system and combustion unit according to one or more aspects of the invention.

[0054] The burner unit includes a burner. The burner unit also includes a distributor. The distributor and burner of the burner unit are based on one or more aspects of the present invention.

[0055] According to one aspect of the invention, a method is provided for using a premixed gas heating system capable of adjusting between a minimum load and a maximum load. According to one example, the ratio between the maximum load and the minimum load is at least 4. The method includes the step of setting up a fan unit configured to supply a premixed air-gas flow required for combustion. The method includes the step of supplying a flow of premixed air and fuel gas to a burner. Preferably, the fuel gas in the premixed air-gas flow contains at least 20% hydrogen by volume. The method includes the step of setting up a burner comprising a plurality of orifices. The plurality of orifices provide an effective delivery area defined to allow the premixed air-gas flow to flow from a region upstream of the burner to a region producing a combustion flame. According to one example, the method includes the step of setting up a load controller. The load controller is configured to adjust the output load of the heating system to allow the heating system to adjust between a minimum load and a maximum load. The method may include the step of setting a minimum load value such that a combustion index value is between 4 E06 and 6 E07. The combustion index is defined as the ratio of the minimum load to the free passage area of ​​the burner. The method may also include the step of setting up a burner having a first set of orifices and a second set of orifices. Preferably, the diameter of the second set of holes is at least 30% larger than that of the first set of holes. According to one example, the area covered by the second set of holes is less than 40% of the total effective delivery area of ​​the burner.

[0056] The method may include the step of configuring a burner having a perforated peripheral portion. The method may also include the step of configuring a distributor comprising a peripheral portion. The peripheral portion of the distributor has multiple openings. The distributor also includes a central portion having multiple orifices. Preferably, the openings of the peripheral portion constitute at least 60% of the total area of ​​the orifices of the distributor.

[0057] The method may include the step of positioning a distributor upstream of the burner to deliver a premixed air-gas flow to the burner. The distributor is positioned such that its outer peripheral portion faces the outer peripheral portion of the burner. This configuration enables better circulation between the burner and the distributor, resulting in burner cooling.

[0058] The method may include the step of providing a user with multiple operating modes. Each of the multiple operating modes corresponds to a specific range among multiple reference ranges used for the flammability index.

[0059] The method includes the step of selecting a reference range for the flammability index from multiple reference ranges based on a user-selected operating mode. The method also includes the step of setting a minimum load to a value within the selected reference range.

[0060] According to one aspect of the invention, a method is provided for forming a premixed gas heating system capable of adjusting between a minimum load and a maximum load. According to one example, the ratio between the maximum load and the minimum load is at least 4. The method includes the step of setting up a fan unit configured to provide a premixed air-gas flow required for combustion. According to one example, the method includes the step of providing a flow of premixed air and fuel gas to a burner, wherein the fuel gas in the premixed air-gas flow contains at least 20% hydrogen by volume. The method includes the step of setting up a burner comprising a plurality of orifices. The plurality of orifices provide an effective delivery area defined to allow the premixed air-gas flow to exit from a region upstream of the burner to a region producing a combustion flame.

[0061] The method may include the step of setting a load controller. The load controller is configured to adjust the outlet load of the heating system to regulate the heating system between a minimum load and a maximum load. The minimum load is set to a predetermined reference value. According to an example, the effective delivery area provided by the burner results in a combustion index value between 4 E06 and 6 E07. The combustion index is defined as the ratio between the reference value of the minimum load and the effective delivery area of ​​the burner. Attached Figure Description

[0062] These and other features of the invention will become more apparent from the following detailed description with reference to the accompanying drawings, of which:

[0063] Figure 1 The combustion unit according to the invention is shown;

[0064] Figure 2 Show Figure 1 An exploded perspective view of the combustion unit;

[0065] Figure 3This is a cross-sectional view of a burner unit formed by the burner and the distributor;

[0066] Figure 4A and 4B This is a front view of the burner unit (showing the distributor and burner respectively).

[0067] Figure 5 This is a front view of the combustion unit's cover;

[0068] Figure 6 This is a front view of the interior and exterior of the central part of the burner;

[0069] Figure 7 This is a front view of the dispenser;

[0070] Figure 8 and 9 This is a cross-sectional view of the burner unit and distributor. Detailed Implementation

[0071] Referring to the accompanying drawings, reference numeral 1 indicates a combustion unit for a boiler. The combustion unit (i.e., unit) 1 includes a fan unit 2. The fan unit 2 is configured to supply a premixed air-gas flow required for combustion. Unit 1 includes a combustion chamber. The combustion chamber extends along a longitudinal axis L from a first end to a second end. Unit 1 includes a cover 3. The cover 3 is configured to close the first end of the combustion chamber. The unit includes a base element 4. Unit 1 is closed at its first end by the cover 3 and at its second end by the base element 4. Unit 1 includes a burner 5. According to one example, the burner 5 has a convex shape. The burner may include a central portion 501 and an outer peripheral portion 502. The central portion 501 is perforated, while the outer peripheral portion 502 is non-perforated. Unit 1 also includes a distributor 6. Preferably, the distributor 6 is convex. The distributor 6 includes an outer peripheral portion provided with an opening 601. The distributor may also include a central portion having a plurality of holes. According to one example, the central hole 602 of a plurality of holes in the central portion of the distributor 6 is smaller than the opening 601 of the outer peripheral portion of the distributor 6. According to one example, the opening 601 of the outer peripheral portion forms at least 60% of the total surface area of ​​the holes in the distributor 6. The distributor 6 is located upstream of the burner 5 for delivering a premixed air-gas flow to the burner 5.

[0072] Distributor 6 is positioned such that its outer peripheral portion faces the outer peripheral portion 502 of burner 5. In this manner, a premixed air-gas flow enters the opening 601 of the outer peripheral portion of distributor 6 and contacts the outer peripheral portion 502 of burner 5; a circulation of air-gas flow cooling burner 5 is created between the outer peripheral portion of burner 5 and the outer peripheral portion of distributor 6 before the air-gas flow passes through the central portion 501 of burner 5. According to one example, the opening 601 of the outer peripheral portion of distributor 6 forms at least 60% of the total surface area of ​​the orifice of distributor 6. Unit 1 may include a flange 7. The flange 7 is configured to connect the cover 3 to burner 5.

[0073] Unit 1 includes a coil 8 for heat exchange. The coil 8 is arranged around a longitudinal axis L to surround the combustion chamber. The coil 8 is provided with multiple helical portions, including a first helical portion 801 near the burner 5 and a final helical portion away from the burner 5. Unit 1 also includes an outer sheath 9 configured to receive the coil 8. Preferably, the inner diameter of the flange 7 is equal to or greater than the inner diameter of the coil 8. The flange 7 provides a receiving surface that receives the first helical portion 801 of the coil 8 for heat exchange through direct contact with it.

[0074] According to one example, the absolute distance D between the heat exchange coil 8 and the burner 5 varies relative to the angular position around the longitudinal axis L. The absolute distance D varies between a minimum and a maximum value. According to one example, the minimum absolute distance D is less than 15 mm. Preferably, the minimum absolute distance D is less than 8 mm. The maximum absolute distance D is less than 25 mm. Preferably, the maximum absolute distance D is less than 18 mm. According to one example, the minimum axial distance A along the longitudinal axis L between the heat exchange coil 8 and the burner 5 varies between a minimum and a maximum value. According to one example, the minimum axial distance A is less than 20 mm. Preferably, the minimum axial distance A is less than 12 mm. According to one example, the maximum minimum axial distance A is less than 30 mm. Preferably, the maximum minimum axial distance A is less than 22 mm. The burner 5 and the distributor form a burner unit. According to one example, the burner unit is fixed to the flange at a 10° angle in the first connection area C by one or more screws. Preferably, the flange 7 has a portion in the shape of teeth 702 at the first connection area C. This design allows the minimum portion of flange 7 to be directly connected to the burner unit and prevents flange 7 from overheating. According to one example, cover 3 is fixed to flange 7 in a second connection region S. Preferably, cover 3 is fixed to flange 7 by a plurality of axial screws 10B. According to one example, the second connection region S is different from and separate from the first connection region C. Unit 1 also includes a feed chamber 11. Feed chamber 11 is defined between cover 3 and the distributor. Flange 7 includes lugs 701. Lugs 701 extend radially relative to the longitudinal axis L. Lugs 701 are configured to receive fan unit 2. Unit 1 includes a feed tube for delivering a premixed air-gas flow supplied by fan unit 2 to feed chamber 11. According to one example, lugs 701 of flange work in conjunction with cover 3 to define feed tube. Feed tube has an inlet located in the outlet of fan unit and an outlet leading to feed chamber. According to one example, the premixed air-gas flow in combustion chamber 11 flows forward in a forward direction F from a first end to a second end of combustion chamber 11. Preferably, the premixed air-gas flow within the feed tube is oriented at the inlet of the feed tube in an inlet direction having at least one component pointing in a rearward direction opposite to the forward direction F in the longitudinal direction. Furthermore, preferably, the premixed air-gas flow within the feed tube is oriented at the outlet of the feed tube in an outlet direction having at least one component pointing radially towards the longitudinal axis L.

[0075] The cover 3 includes an inner surface defining the combustion chamber 11. According to one example, the cover 3 includes a protrusion in the central portion of its inner surface. The protrusion projects into the feed chamber 11 and forms a shaped annular portion 301. According to one example, the annular portion 301 has a cover 302. The cover includes an opening. According to a preferred example, the annular portion 301 works in conjunction with an opening 601 provided in the outer peripheral portion of the distributor 6 to provide a manifold for distributing the premixed air-gas supplied by the fan unit 2 to the opening 601 in the outer peripheral portion of the distributor 6.

[0076] Unit 1 may also include a gasket 12 for sealing the cover 2. The gasket 12 is located between the cover 3 and the flange 7. According to one example, the gasket 12 for sealing the cover 2 has a first portion 12A and a second portion 12B. The first portion 12A is annular and positioned about the longitudinal axis L. The second portion 12B is offset relative to the longitudinal axis L and contacts the lug 701 of the flange.

[0077] According to one aspect of the invention, a method for heating water in a heating system is also provided. The method includes the step of arranging a fan unit 2 to provide a premixed air-gas flow required for combustion. The method includes the step of arranging a cover 3. The method includes the step of arranging a burner 5. The burner preferably has a convex shape. The method includes the step of arranging a distributor 6. The distributor preferably has a convex shape. The method further includes the step of providing a ring 8 for heat exchange. According to an example, the ring 8 for heat exchange extends around a longitudinal axis L to surround a combustion chamber. The ring 8 has a plurality of spiral portions, including a first spiral portion 801 near the burner and a final spiral portion away from the burner 5. The method includes the step of arranging the cover 3. The cover 3 is configured to close a first end of the combustion chamber. The method may include the step of arranging a burner 5 having a perforated central portion 501 and a non-perforated outer peripheral portion 502. The method may include the step of providing a distributor 6 having an outer peripheral portion provided with an opening 601. The distributor is located upstream of the burner 5 such that the outer peripheral portion of the distributor 6 faces the outer peripheral portion 502 of the burner 5.

[0078] The method may include the step of providing a flange 7. According to one example, the flange 7 is connected to the cover 3 and the burner 5. According to one example, the flange 7 has a receiving surface 701 and receives a first helical portion 801 of a coil 8 for heat exchange through direct contact. The method includes the step of circulating water within the coil 8 for heat exchange. The method also includes the step of supplying a mixture of fuel gas and air to the burner 5 via a distributor 6. According to one example, the fuel gas in the mixture of gas and air is natural gas.

[0079] The method may include the step of directly securing the burner unit formed by the burner 6 and the distributor 5 to the flange 7. According to one example, the burner unit is secured to the flange 7 in a first connection region C and the cover 8 is secured to the flange 7 in a second connection region S. The second connection region S is different from and separate from the first connection region C. According to one example, the fan unit 2 is connected to the flange 7; therefore, the burner unit formed by the burner 5 and the distributor 6 can be accessed by removing the cover 3 without removing the fan unit 2. The method may include the step of providing a feed chamber 11 between the cover 3 and the distributor 6. The method may include the step of conveying a premixed air-gas flow provided by the fan unit 2 to the feed chamber 11 through a conduit defined by the flange 7 and the cover 3. Preferably, the premixed air-gas flow is conveyed to the feed chamber 11 in an orientation having a radial component pointing towards the longitudinal axis L to create an air-gas flow within the feed chamber 11 that contacts the inner surface of the cover 3.

[0080] According to one aspect of the invention, a premixed gas heating system is also provided. The heating system may include a combustion unit according to one or more aspects of the invention, regardless of the fuel used. The heating system includes a fan unit 2. The fan unit 2 is configured to supply a premixed air-gas flow required for combustion. According to one example, the fuel gas in the premixed air-gas flow contains at least 20% hydrogen by volume. Preferably, the fuel gas in the premixed air-gas flow supplied to the burner contains at least 60% hydrogen by volume. More preferably, the fuel gas in the premixed air-gas flow supplied to the burner is 100% hydrogen. Alternatively, the heating system may use a mixture of air and natural gas. The heating system includes a burner 5. The burner 5 has a plurality of orifices. The plurality of orifices provide an effective delivery area defined to allow the premixed air-gas flow to flow from a feed chamber 11 upstream of the burner 5 to the combustion chamber that produces the combustion flame. The heating system may include a load controller. The load controller is configured to adjust the outlet load of the heating system to regulate the heating system between a minimum load and a maximum load. According to one example, the ratio between the maximum load and the minimum load is at least 4. Preferably, the ratio between the minimum load and the maximum load is equal to 8.

[0081] For example, the minimum load of the heating system is set to keep the combustion index between 4 E06 and 6 E07. The combustion index is defined as the ratio between the minimum load and the effective delivery area of ​​the burner. The heating system can have different ranges for the combustion index value. The optimal range (i.e., the high range) includes combustion indices between 6 E07 and 2 E07. Within this range, the heating system has high efficiency and low regulation amplitude. The heating system can also have a range for the combustion index between 8 E06 and 2 E07. This range represents a balance between the efficiency of the heating system and its regulation amplitude.

[0082] The combustion index of the heating system can be in a third range (i.e., the low range) between 4 E06 and 8 E06. Within this range, the heating system has a greater range of adjustment and lower efficiency than the other two ranges. According to one example, the burner 5 has multiple orifices including a first set of orifices and a second set of orifices. The first set of orifices has a first diameter. The second set of orifices has a second diameter. According to one example, the first diameter is smaller than the second diameter.

[0083] According to one example, the second diameter is increased by at least 30% relative to the first diameter. Preferably, the area covered by the second set of holes is less than 40% of the total effective delivery area of ​​the burner 5. The burner 5 of the heating system may include a central portion 501 and an outer peripheral portion 502. According to one example, the central portion 501 is perforated while the outer peripheral portion 502 is non-perforated, and the heating system also includes a distributor 6. The distributor 6 has an outer peripheral portion provided with an opening 601. The distributor 6 is located upstream of the burner for delivering a premixed air-gas flow to the burner 5. Preferably, the distributor 6 is positioned such that the outer peripheral portion of the distributor 6 faces the outer peripheral portion 502 of the burner 5.

[0084] The distributor 6 may include a plurality of holes in its central portion. The holes in the central portion of the distributor have different dimensions from the openings in the outer peripheral portion. According to an example, the openings 601 in the outer peripheral portion form at least 60% of the total area of ​​the holes in the distributor 6. According to an example, the burner 5 has a convex shape. Alternatively, the burner 5 may have a cylindrical shape.

[0085] According to one example, the central portion 501 of the burner 5 includes an inner portion 501A and an outer portion 501B. According to one example, the inner portion 501A of the central portion 501 of the burner 5 is non-perforated. Furthermore, according to one example, the outer portion 501B of the central portion of the burner is perforated. The outer portion 501B of the central portion of the burner may be an annular region surrounding the inner portion 501A of the central portion of the burner. Additionally, there is a perforated region inside the burner facing the distributor.

[0086] Additionally, according to one example, the central portion of the distributor includes a central interior 600A and a central exterior 600B. According to another example, both the central interior 600A and the central exterior 600B are perforated and can be separated by a non-perforated region 600C. The non-perforated region 600C of the distributor 6 can be an annular region. According to another example, the central exterior 600B of the distributor faces the outer portion 501B of the central portion of the burner, which has perforations and therefore a flame. Furthermore, the central interior 600A of the distributor 6 faces the inner portion 501A of the central portion of the burner 5.

[0087] Furthermore, according to one example, the outer portion 501B of the central portion 501 of the burner extends further than the outer portion 600B of the center of the distributor. In other words, the effective delivery area of ​​the burner is larger than that of the distributor.

[0088] In one example, the load controller has access to memory. The memory contains multiple reference ranges for values ​​used in the flammability index. Furthermore, the load controller is programmed to provide the user with multiple operating modes, each corresponding to a specific reference range selected by the user.

[0089] According to one aspect of the invention, a method is provided for operating a premixed gas heating system capable of adjusting between a minimum load and a maximum load. The heating system may include a combustion unit according to one or more aspects of the invention. According to one example, the ratio between the maximum load and the minimum load is at least 4. According to another example, the ratio between the maximum load and the minimum load is equal to 8. The method includes the step of setting up a fan unit 2 configured to provide a premixed air-gas flow required for combustion. The method includes the step of providing a flow of premixed air and fuel gas to a burner. According to one example, the fuel gas in the premixed air-gas flow contains at least 20% hydrogen by volume. The method includes the step of setting up a burner 5. The burner 5 includes a plurality of orifices on a central portion 501 of the burner 5. The plurality of orifices provide an effective delivery area defined to allow the premixed air-gas flow to flow from a region upstream of the burner 5 to a region producing a combustion flame. The method may include the step of setting up a burner 5 having a first set of orifices and a second set of orifices. According to one example, the diameter of the second set of orifices is at least 30% larger than that of the first set of orifices. Preferably, the area covered by the second set of orifices is less than 40% of the total effective delivery area of ​​the burner. The method includes the step of setting a load controller. The load controller is configured to adjust the outlet load of the heating system to regulate the heating system between a minimum load and a maximum load. The method may include the step of setting a minimum load value to place a combustion index value between 4 E06 and 6 E07. The combustion index is defined as the ratio between the minimum load and the effective delivery area of ​​the burner.

[0090] The method may further include the step of providing a burner 5 with a perforated peripheral portion 502. The method includes the step of providing a distributor 6. The distributor includes a peripheral portion having an opening 601. The distributor includes a central portion having a plurality of holes. According to an example, the opening 601 of the peripheral portion constitutes at least 60% of the total area of ​​the holes in the distributor 6. Preferably, the method includes the step of positioning the distributor 6 upstream of the burner 5 to deliver a premixed air-gas flow to the burner 5 and having the peripheral portion of the distributor 6 face the peripheral portion 502 of the burner 5.

[0091] The method may include the step of providing a user with multiple operating modes. Each of the multiple operating modes corresponds to a corresponding range among multiple reference ranges. Each reference range includes multiple values ​​for the combustion index. The method may include the step of selecting three ranges for the values ​​of the combustion index: "optimal," "balanced," and "low." The optimal range allows for high efficiency and low adjustment. The balanced range does not allow for high efficiency or extremely high adjustment. The low range allows for as much adjustment as possible.

[0092] The method includes the step of selecting a reference range for the flammability index from among multiple reference ranges based on a user-selected operating mode. The method also includes the step of setting a minimum load to a value within the selected reference range.

[0093] According to one aspect of the invention, a method is provided for forming a premixed gas heating system capable of adjusting between a minimum load and a maximum load. The heating system may include a combustion unit according to one or more aspects of the invention, regardless of the fuel used. According to one example, the ratio between the maximum load and the minimum load is at least 4. The method includes the step of setting up a fan unit 2 configured to provide a premixed air-gas flow required for combustion. The method includes the step of providing a flow of premixed air and fuel gas to a burner. According to one example, the fuel gas in the premixed air-gas flow contains at least 20% hydrogen by volume. Alternatively, the fuel gas may be a flow of natural gas. The method may include the step of setting up a burner 5. The burner 5 includes a plurality of orifices. The plurality of orifices provide an effective delivery area defined to allow the premixed air-gas flow from a region upstream of the burner 5 to a region producing a combustion flame. The method may include the step of setting up a burner having a perforated peripheral portion 502. The method may include the step of setting up a distributor 6. The distributor has a central portion including orifices. The distributor 6 includes a plurality of openings 601 in its peripheral portion. According to one example, the method includes the steps of positioning a distributor upstream of a burner 5 to deliver a premixed air-gas flow to the burner 5 and having the outer peripheral portion of the distributor face the outer peripheral portion 502 of the burner. The method may include the step of setting a load controller. The load controller is configured to adjust the outlet load of the heating system to regulate the heating system between a minimum load and a maximum load. The minimum load is set to a predetermined reference value. The effective delivery area provided by the burner 5 results in a combustion index value between 4 E06 and 6 E07. The combustion index is defined as the ratio between the reference value of the minimum load and the effective delivery area of ​​the burner.

[0094] The following paragraphs marked with alphanumeric symbols represent exemplary and non-limiting ways of describing the invention.

[0095] A. A combustion unit (1) for a heating system, the combustion unit (1) comprising:

[0096] A fan assembly (2) is configured to supply the premixed air-gas flow required for combustion.

[0097] Combustion chamber extending from the first end to the second end along the longitudinal axis (L);

[0098] (3) is a cover used to seal the first end of the combustion chamber.

[0099] Burner (5);

[0100] The flange (7) is configured to connect the cover (3) to the burner (5);

[0101] The heat exchange ring (8) is arranged around the longitudinal axis (L) to surround the combustion chamber and has multiple winding portions including a first winding portion (801) near the burner (5) and a last winding portion away from the burner.

[0102] A1. According to the heat exchange unit (1) of paragraph A, the burner (5) has a convex or flat profile.

[0103] A1.1. According to paragraph A1, the combustion unit (1) includes a central part (501) and an outer peripheral part (502), wherein the central part (501) is perforated and the outer peripheral part (502) is non-perforated.

[0104] A1.2. According to any one of paragraphs A1 to A1.1, the combustion unit (1) wherein the plurality of holes of the burner (5) includes a first set of holes having a first diameter and a second set of holes having a second diameter, the first diameter being smaller than the second diameter.

[0105] A1.2.1. According to the combustion unit (1) in paragraph A1.2, the second diameter is increased by at least 30% relative to the first diameter.

[0106] A1.2.2. According to paragraph A1.2 or A1.2.1, the combustion unit (1) is wherein the area covered by the second set of holes is less than 40% of the total free passage area of ​​the burner.

[0107] A2. The combustion unit (1) according to any one of paragraphs A to A1.2.2 includes a distributor (6) located upstream of the burner (5) for delivering a premixed air-gas flow to the burner (5).

[0108] A2.1. According to paragraph A2, the combustion unit (1) has a convex or flat profile.

[0109] A2.2. Combustion unit (1) according to any one of paragraphs A2 to A2.1, wherein the distributor (6) includes an outer peripheral portion provided with an opening (601) and is configured such that the outer peripheral portion of the distributor (6) faces the outer peripheral portion (502) of the burner (5).

[0110] A2.3. The combustion unit (1) according to any one of paragraphs A2 to A2.2, wherein the distributor (6) includes a plurality of holes on its central portion having different sizes from the openings of the outer peripheral portion, and wherein the openings (601) of the outer peripheral portion form at least 60% of the total area of ​​the holes of the distributor (601).

[0111] A3. A combustion unit (1) according to any one of paragraphs A to A2.3, wherein the flange (7) has a receiving surface (701) that accommodates a first winding portion (801) of a heat exchanger (8) in direct contact with it.

[0112] A4. According to any one of paragraphs A to A3, the minimum total distance (D) between the heat exchanger (8) and the burner (5) varies between a minimum and a maximum angular position relative to the longitudinal axis (L), and at least one of the following conditions is satisfied:

[0113] i) The minimum total distance (D) is less than 15 mm;

[0114] ii) The maximum value of the minimum total distance (D) is less than 25 mm.

[0115] A4.1. According to the combustion unit (1) of paragraph A4, at least one of the following conditions is met:

[0116] i) The minimum total distance (D) is less than 8 mm;

[0117] ii) The maximum value of the minimum total distance (D) is less than 18 mm.

[0118] A5. According to any one of paragraphs A to A4.1, the minimum axial distance (A) between the heat exchanger (8) and the burner (5) along the longitudinal axis (L) varies between a minimum and a maximum value, and at least one of the following conditions is satisfied:

[0119] i) The minimum value of the minimum axial distance (A) is less than 20 mm;

[0120] ii) The maximum value of the minimum axial distance (A) is less than 30 mm.

[0121] A5.1. According to the combustion unit (1) of paragraph A5, at least one of the following conditions is met:

[0122] i) The minimum value of the minimum axial distance (A) is less than 12 mm;

[0123] ii) The maximum value of the minimum axial distance (A) is less than 22 mm.

[0124] A6. Combustion unit (1) according to any one of paragraphs A to A5.1, wherein the burner assembly formed by the burner (5) and the distributor (6) is attached to the flange (7) at the first connection area (C) by one or more connecting elements.

[0125] A6.1. According to the combustion unit (1) of paragraph A6, the cover (3) is attached to the flange (7) at the second connection area (S), which is different from and separate from the first connection area.

[0126] A7. The combustion unit (1) according to any one of paragraphs A to A6.1 further includes a feed chamber (11) defined between a cover (3) and a distributor (6), wherein the flange (7) includes a lug (703) extending radially relative to the longitudinal axis (L) for receiving a fan assembly (2) connected thereto.

[0127] A7.1. According to the combustion unit (1) of paragraph A7, wherein the lug (703) of the flange (7) cooperates with the cover (3) to define the feed pipe, which is configured to deliver the premixed air-gas flow supplied by the fan assembly (2) to the feed chamber.

[0128] A7.1.1. Combustion unit (1) according to paragraph A7.1, wherein air-gas flows in a forward direction (F) from a first end of the combustion chamber to a second end in the combustion chamber (11), and wherein the feed pipe has an inlet located at the outlet of the fan assembly and an outlet leading to the feed chamber, wherein the premixed air-gas flow in the feed pipe is oriented at the inlet of the feed pipe in an inlet direction having at least one component pointing in the longitudinal direction in a rearward direction opposite to the forward direction.

[0129] A7.1.2. Combustion unit (1) according to paragraph A7.1 or A7.1.1, wherein the premixed air-gas flow in the feed tube is directed at the outlet of the feed tube in an outlet direction having at least one component pointing radially toward the longitudinal axis (L).

[0130] A8. Combustion unit (1) according to any one of paragraphs A to A7.1.2, wherein the cover (3) has an inner surface defining the combustion chamber and a protrusion protruding into the feed chamber is provided at the center of the inner surface, thereby forming an annular portion (301) in the feed chamber (11).

[0131] A8.1. According to paragraph A8, the combustion unit (1) wherein the annular portion (301) cooperates with the opening (601) provided at the outer peripheral portion of the distributor (6) to provide a manifold for delivering the premixed air-gas supplied by the fan assembly (2) to the opening of the outer peripheral portion of the distributor.

[0132] A9. The combustion unit (1) according to any one of paragraphs A to A8.1 includes a cover sealing gasket (12) disposed between the cover (3) and the flange (7), wherein the cover sealing gasket (12) has a first portion (12A) and a second portion (12B), wherein the first portion of the cover sealing gasket is annular and disposed around the longitudinal axis (L), and the second portion (12B) is offset from the longitudinal axis and contacts the lug (703) of the flange (7).

[0133] B. A premixed gas heating system, comprising:

[0134] A fan assembly (2) configured to supply a premixed air-gas flow required for combustion, wherein the combustible gas in the premixed air-gas flow contains at least 20% hydrogen by volume;

[0135] A burner (5) having multiple orifices, wherein the multiple orifices provide a free passage area defined to allow the premixed air-gas flow to flow from the feed chamber (11) upstream of the burner (5) to the combustion chamber that produces the combustion flame;

[0136] A load controller is configured to adjust the output load of the heating system so that the heating system is regulated between a minimum load and a maximum load, wherein the ratio between the maximum load and the minimum load is at least 4.

[0137] B1. According to the heating system in paragraph B, the minimum load of the heating system is set to keep the combustion index between 4E06 and 6E07, and the combustion index is defined as the ratio of the minimum load to the free passage area of ​​the burner.

[0138] B1.1. The heating system according to paragraph B1, wherein the combustion index is in the range of 8 E06 to 2 E07.

[0139] B2. A heating system according to any one of paragraphs B to B1.1, wherein the load controller:

[0140] It has access to a memory containing multiple reference ranges for values ​​used in the flammability index;

[0141] It is programmed to provide the user with multiple operating modes, each of which corresponds to a corresponding range in a plurality of reference ranges; and

[0142] It is programmed to set the minimum load to a value within a reference range corresponding to the user-selected operating mode.

[0143] B2.1. According to the heating system in paragraph B2, the memory contains:

[0144] The first reference range for flammability index values ​​is between 4 E06 and 8 E06;

[0145] The second reference interval for flammability index values ​​is between 8 E06 and 2 E07;

[0146] The third reference range for flammability index values ​​is between 2 E07 and 6 E07.

[0147] B3. For any of the heating systems described in paragraphs B to B2.1, the ratio between the maximum load and the minimum load is preferably 8.

[0148] B4. A heating system according to any one of paragraphs B to B3, wherein the combustible gas in the premixed air-gas stream supplied to the burner comprises at least 60% hydrogen by volume.

[0149] B4.1. According to paragraph B4, the combustible gas in the premixed air-gas stream supplied to the burner is 100% hydrogen.

[0150] B5. A heating system according to any one of paragraphs B to B4.1, wherein the burner (5) has the features described in one or more of paragraphs A1 to A1.2.2.

[0151] B6. A heating system according to any one of paragraphs B to B4.1, wherein the burner (5) has a cylindrical or flat profile.

[0152] B7. A heating system according to any one of paragraphs B to B6, which includes a distributor (6) located upstream of the burner (5).

[0153] B7.1. The heating system according to paragraph B7, wherein the distributor (6) has the features described in one or more of paragraphs A2 to A2.3.

[0154] B8. A heating system according to any one of paragraphs B to B7.1, wherein the burner (5) comprises a central portion (501) and an outer peripheral portion (502), wherein the central portion (501) of the burner comprises an inner portion (501A) and an outer portion (501B), wherein the inner portion is non-perforated and the outer portion of the central portion of the burner is perforated, and the outer portion of the central portion of the burner is an annular region surrounding the inner portion of the central portion.

[0155] B8.1. The heating system according to paragraph B8 also includes a distributor (6) located upstream of the burner for delivering a premixed air-gas flow to the burner, wherein the inner portion of the central part of the burner faces the perforated area of ​​the distributor (6).

[0156] B8.1.1. The heating system according to paragraph B8.1, wherein the distributor (6) comprises:

[0157] The outer peripheral portion (preferably annular) is provided with an opening;

[0158] An outer central portion (preferably annular, preferably coaxial with and located inside the outer peripheral portion) is provided with a hole.

[0159] An internal central portion with a hole (preferably annular or disc-shaped, preferably coaxial with and located inside the external central portion).

[0160] The inner part of the central part of the burner faces the inner central part of the distributor (6), while the perforated area of ​​the burner (the outer part of the central part of the burner) faces the outer central part of the distributor (6).

[0161] C. A method for heating water in a heating system, comprising the following steps:

[0162] Set up the fan assembly (2) and the burner (5);

[0163] A heat exchange ring (8) is provided, which extends around a longitudinal axis (L) to surround the combustion chamber and has multiple winding portions including a first winding portion (801) near the burner (5) and a final winding portion away from the burner;

[0164] A cover (3) is provided for sealing the first end of the combustion chamber;

[0165] A flange (7) is provided to connect with the cover (3) and the burner (5);

[0166] The water circulates in the heat exchanger (8);

[0167] A premixed mixture of combustible gas and air is supplied to the burner via a distributor.

[0168] C1. According to the method in paragraph C, the flange has a receiving surface (701) and a first winding portion (801) that receives the heat exchanger (8) in direct contact with it.

[0169] C2. According to any one of paragraphs C to C1, wherein the burner (5) has the features described in one or more of paragraphs A1 to A1.2.2.

[0170] C3. According to any one of paragraphs C to C1, wherein the burner (5) has a cylindrical or flat profile.

[0171] C4. The method according to any one of paragraphs C to C3 includes the step of positioning the distributor (6) upstream of the burner (5).

[0172] C4.1. According to the method in paragraph C4, the allocator (6) has the features described in one or more of paragraphs A2 to A2.3.

[0173] C5. The burner assembly formed by the burner (5) and the distributor (6) is directly attached to the flange according to any one of paragraphs C to C4.1.

[0174] C6. The fan assembly (2) is connected to the flange (7) according to any of paragraphs C to C5, so that the burner assembly formed by the burner (5) and the distributor (6) can be accessed by removing the cover without removing the fan assembly.

[0175] C7. The method according to any one of paragraphs C to C6, wherein the feed chamber (11) is disposed between the cover and the distributor and wherein a premixed air-gas flow is delivered from the fan assembly to the feed chamber via a feed tube defined by the flange and the cover.

[0176] C7.1. According to the method in paragraph C7, the premixed air-gas flow is delivered to the feed chamber (11) in an orientation having a radial component pointing to the longitudinal axis (L), thereby ensuring that the air-gas flow contacts the inner surface of the cover in the feed chamber.

[0177] D. A method for operating a premixed gas heating system adjustable between a minimum load and a maximum load, wherein the ratio of the maximum load to the minimum load is at least 4, the method comprising the steps of:

[0178] A fan assembly (2) is configured to supply the premixed air-gas flow required for combustion.

[0179] A premix of combustible gas and air is supplied to the burner, wherein the combustible gas in the premixed air-gas stream contains at least 20% hydrogen by volume;

[0180] The burner (5) includes multiple orifices, wherein the multiple orifices provide a free passage area defined to allow a premixed air-gas flow from an area upstream of the burner to an area that produces a combustion flame;

[0181] A load controller is set up and configured to adjust the output load of the heating system so that the heating system adjusts between minimum and maximum load.

[0182] D1. According to the method in paragraph D, the minimum load is set as the minimum load value that makes the combustion index value in the range of 4 E06 and 6 E07, which is defined as the ratio of the minimum load to the free passage area of ​​the burner.

[0183] D2. According to any one of paragraphs D to D1, wherein the burner (5) has the features described in one or more of paragraphs A1 to A1.2.2.

[0184] D3. According to any one of paragraphs D to D2, wherein the burner (5) has a cylindrical or flat profile.

[0185] D4. The method according to any one of paragraphs D to D3 includes positioning the distributor (6) upstream of the burner (5).

[0186] D4.1. According to the method in paragraph D4, the allocator (6) has the features described in one or more of paragraphs A2 to A2.3.

[0187] D5. According to the method of any one of paragraphs D through D4.1, it further includes the following steps:

[0188] Provide customers with multiple operating modes, where each of the multiple operating modes corresponds to a corresponding range in multiple reference ranges;

[0189] In response to the user-selected operating mode, a reference range for the combustion index value is selected from multiple reference ranges used for the combustion index value;

[0190] Set the minimum load to a value within the selected reference range.

[0191] D5.1. According to the method in paragraph D5, there are three operating modes with the following three corresponding reference intervals:

[0192] The first reference range for flammability index values ​​is between 4 E06 and 8 E06;

[0193] The second reference interval for flammability index values ​​is between 8 E06 and 2 E07;

[0194] The third reference range for flammability index values ​​is between 2 E07 and 6 E07.

[0195] E. A method for manufacturing a premixed gas heating system capable of adjusting between a minimum load and a maximum load, wherein the ratio of the maximum load to the minimum load is at least 4, the method comprising the steps of:

[0196] A fan assembly (2) is configured to supply the premixed air-gas flow required for combustion.

[0197] A premix of combustible gas and air is provided to the burner, wherein the combustible gas in the premixed air-gas stream contains at least 20% hydrogen by volume;

[0198] The burner is configured to include multiple orifices, wherein the multiple orifices provide a free passage area defined to allow a premixed air-gas flow from an area upstream of the burner to an area that produces a combustion flame;

[0199] A load controller is configured to adjust the output load of the heating system so that the heating system adjusts between a minimum load and a maximum load, wherein the minimum load is set to a predetermined reference value.

[0200] E1. According to the method in paragraph E, the free passage area provided by the burner makes the combustion index value range between 4 E06 and 6 E07, which is defined as the ratio of the minimum load reference value to the free passage area of ​​the burner.

[0201] E2. According to the method of paragraph E or E1, it includes the features described in one or more of paragraphs D2 to D5.1.

[0202] F. A burner assembly comprising:

[0203] The burner (5) includes multiple orifices, wherein the multiple orifices provide a free passage area defined to allow a premixed air-gas flow from the feed chamber (11) upstream of the burner (5) to the combustion chamber that produces the combustion flame;

[0204] A distributor (6), located upstream of the burner (5), is used to deliver a premixed air-gas flow to the burner (5).

[0205] F1. The burner assembly according to paragraph F, wherein the burner has one or more of the features of the following paragraphs: A1 to A1.2.2 and B8.

[0206] F2. The burner assembly according to paragraph F or F1, wherein the distributor has the characteristics of one or more of the following paragraphs: A2.1 to A2.3 and B8.1 to B8.1.1.

Claims

1. A premixed gas heating system, comprising: A fan assembly configured to supply a premixed air-gas flow required for combustion, wherein the combustible gas in the premixed air-gas flow contains at least 20% hydrogen by volume; A burner including multiple orifices, wherein the multiple orifices provide a free passage area defined to allow the premixed air-gas flow to flow from a feed chamber upstream of the burner to a combustion chamber that produces a combustion flame; A load controller is configured to adjust the output load of the burner to regulate the heating system between a minimum load and a maximum load, wherein the ratio between the maximum load and the minimum load is at least 4. The minimum load of the heating system is set such that the combustion index is between 4 E06 and 6 E07, and the combustion index is defined as the ratio of the minimum load to the free passage area of ​​the burner.

2. The heating system according to claim 1, wherein, The flammability index is between 8 E06 and 2 E07.

3. The heating system according to claim 1 or 2, wherein, The burner has a plurality of holes, including a first set of holes with a first diameter and a second set of holes with a second diameter, wherein the first diameter is smaller than the second diameter.

4. The heating system according to claim 3, wherein, The second diameter is at least 30% larger than the first diameter.

5. The heating system according to claim 3, wherein, The area covered by the second set of holes is less than 40% of the total free passage area of ​​the burner.

6. The heating system according to claim 1 or 2, wherein, The ratio between the minimum load and the maximum load is at least 8.

7. The heating system according to claim 1 or 2, wherein, The combustible gas in the premixed air-gas stream supplied to the burner contains at least 60% hydrogen by volume.

8. The heating system according to claim 7, wherein, The combustible gas in the premixed air-gas stream supplied to the burner is 100% hydrogen.

9. The heating system according to claim 1 or 2, wherein, The burner includes a central portion and an outer peripheral portion, wherein the central portion is perforated and the outer peripheral portion is non-perforated. The heating system also includes a distributor having an outer peripheral portion provided with an opening, the distributor being located upstream of the burner for supplying the premixed air-gas to the burner, and being configured such that the outer peripheral portion of the distributor faces the outer peripheral portion of the burner.

10. The heating system according to claim 9, wherein, The dispenser includes a plurality of holes on its central portion having different dimensions from the openings on the outer peripheral portion, wherein the openings on the outer peripheral portion form at least 60% of the total area of ​​the holes in the dispenser.

11. The heating system according to claim 1 or 2, wherein, The burner has a cylindrical shape or a convex profile.

12. The heating system according to claim 1 or 2, wherein, The burner includes a central portion and an outer peripheral portion. The heating system further includes a distributor located upstream of the burner for supplying the premixed air-gas to the burner. The central portion of the burner includes an inner portion and an outer portion, wherein the inner portion is non-porous and the outer portion of the central portion is perforated. The outer portion of the central portion of the burner is an annular region surrounding the inner portion of the central portion, and wherein the inner portion of the central portion of the burner faces the perforated region of the distributor.

13. The heating system according to claim 1 or 2, wherein, The load controller: It has access to a memory containing multiple reference ranges for the values ​​of the combustion index; It is programmed to provide a user with multiple operating modes, each of which corresponds to a corresponding range among the multiple reference ranges; and It is programmed to set the minimum load to a value within the reference range corresponding to the operating mode selected by the user.

14. A method for operating a premixed gas heating system adjustable between a minimum load and a maximum load, wherein the ratio of the maximum load to the minimum load is at least 4, the method comprising the steps of: The fan assembly is configured to supply the premixed air-gas flow required for combustion; A premix of combustible gas and air is supplied to the burner, wherein the combustible gas in the premixed air-gas stream contains at least 20% hydrogen by volume; The burner is provided with a plurality of orifices, wherein the plurality of orifices provide a free passage area defined to allow the premixed air-gas flow to flow from a region upstream of the burner to a region where a combustion flame is generated; A load controller is configured to adjust the output load of the heating system to allow the heating system to regulate between a minimum load and a maximum load. The minimum load value is set such that the combustion index is in the range of 4 E06 to 6 E07, and the combustion index is defined as the ratio of the minimum load to the free passage area of ​​the burner.

15. The method of claim 14, further comprising the step of providing a first set of holes and a second set of holes for the burner, wherein the diameter of the second set of holes is increased by at least 30% relative to the first set of holes, and wherein the area covered by the second set of holes is less than 40% of the total free passage area of ​​the burner.

16. The method of claim 14 or 15, further comprising the step of: The burner is provided with a non-porous outer peripheral portion; A dispenser is provided, comprising an outer peripheral portion having an opening and a central portion having a plurality of holes, wherein the opening of the outer peripheral portion forms at least 60% of the total area of ​​the holes of the dispenser; The distributor upstream of the burner is configured to supply premixed air-gas to the burner and is configured such that the outer peripheral portion of the distributor faces the outer peripheral portion of the burner.

17. The method according to claim 14 or 15, comprising the following steps: Multiple operating modes are provided to the user, wherein each of the multiple operating modes corresponds to a corresponding range in a plurality of reference ranges; In response to the user-selected operating mode, a reference range for the combustion index is selected from a plurality of reference ranges for the value of the combustion index; Set the minimum load to a value within the selected reference range.

18. A method for manufacturing a premixed gas heating system adjustable between a minimum load and a maximum load, wherein the ratio of the maximum load to the minimum load is at least 4, the method comprising the steps of: The fan assembly is configured to supply the premixed air-gas flow required for combustion; Provide a premix of combustible gas and air to the burner, wherein the combustible gas in the premixed air-gas stream contains at least 20% hydrogen by volume; The burner is provided with a plurality of orifices, wherein the plurality of orifices provide a free passage area defined to allow the premixed air-gas flow to flow from a region upstream of the burner to a region where a combustion flame is generated; A load controller is configured to adjust the output load of the heating system to regulate the heating system between a minimum load and a maximum load, wherein the minimum load is set to a predetermined reference value. The free passage area provided by the burner allows the combustion index value to be in the range of 4 E06 to 6 E07, and the combustion index is defined as the ratio of the reference value of the minimum load to the free passage area of ​​the burner.

Images