Hybrid fuel burner

Abstract

The invention relates to a heating system and to a control method for controlling a heating system for heating a main gas flow flowing through a flow duct, the system comprising an in-duct burner comprising at least one fuel intake manifold provided with at least one injector arranged to inject fuel into a premixing circuit through an injection outlet, and a control assembly arranged to supply fuel to the burner and configured to allow at least one fuel injection parameter to be controlled, the control method and the change in the flow cross-sectional area of the premixing circuit being configured in such a way that the gas flow portion has, at the injection outlet, a flow velocity that is greater than the flame velocity of the fuel in the outlet area.

Description

HYBRID FUEL BURNER TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of burners intended to be placed in a conduit to heat a flow of gas circulating in the conduit, also called vein burners. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Conventionally, a vein burner equipping a flow vein with a gas flow F, as shown in, comprises a portion of vein A in which one or more distribution tubes B extend, transversely to the direction of circulation of the gas. The tube B is supplied with fuel and pierced with holes, possibly equipped with injectors, making it possible to emit jets of combustible gas into the vein A, thus making it possible to locally form a fuel-oxidant mixture which is ignited to generate combustion. The combustion is maintained by a continuous injection of fuel into the heart of the oxidant flow.

[0003] Conventionally, the injectors are directed downstream, and the burners have deflectors C fixed on the tube B so as to divert the flow of combustion gas to create a protected zone downstream of the deflector C where the flame can develop in a stabilized manner.

[0004] An embodiment of a deflector of the prior art, represented in, has been described in particular in the document FR 2 622 277. The tube B is connected to a source of combustible gas and is pierced with holes through which jets of fuel are emitted in the direction of flow of the gas flow F. The stabilizer C comprises two diverging wings D forming deflectors which are connected to a sheath E in which the tube B is housed. The tube B is provided with injectors I emitting jets of fuel through nozzles G, by dragging a local depression sucking a fraction of the gas through openings H made through the sheath E.

[0005] A gas-fuel mixture is therefore formed in nozzle G and feeds the stabilized combustion reaction downstream of stabilizer C.

[0006] Such an embodiment is used in particular with hydrocarbon fuels, for example natural gas.

[0007] In the current context of the desire to decarbonize industry, the use of hydrogen as a fuel for industrial combustion presents itself as a serious alternative to hydrocarbon fuels, thus making it possible to significantly limit the CO2 emissions generated for a given quantity of thermal energy provided by the combustion reaction.

[0008] Given the still nascent development of the hydrogen production industry and supply circuits, it is however desirable to maintain flexibility allowing the use of more common fuels such as natural gas due to uncertainties over the costs and actual availability of hydrogen resources.

[0009] This search for flexibility comes up against fundamental differences between the combustion of hydrogen and that of traditional combustible gases such as natural gas.

[0010] Indeed, the combustion of hydrogen is very different from that of natural gas. Compared to natural gas, hydrogen is a gas with a much lower density (density 7 times lower), has much higher ignition speeds (up to more than 10 times faster than that of natural gas, particularly in the context of sub-stoichiometric combustion), a hotter flame (on average 150 °C for identical conditions and air ratio) and a flammability zone in air at least 5 times wider.

[0011] Consequently, the hydrogen flame is hotter and more intense from its inception at the burner tip, and the speed of the hydrogen flame also leads to a significant risk of flame rising inside nozzle G, up to injector I, which would cause very significant degradation of stabilizer C.

[0012] There is therefore a need for a solution that allows the use of a vein burner with different types of fuels, including hydrogen gas and natural gas, or a mixture of the two.

[0013] In order to meet the needs of the solutions proposed in the prior art, the invention proposes a method for controlling a heating system for heating a main gas flow passing through a flow stream, the system comprising: - a flow stream burner comprising at least one fuel inlet manifold equipped with at least one injector arranged to inject fuel into a premixing circuit configured to allow the fuel to be mixed with a portion of the gas, the injector opening into the premixing circuit at an injection outlet, the premixing circuit being configured to allow a portion of the gas flow to be taken from the stream to guide it into the premixing circuit to an outlet section, the premixing circuit being shaped so that it has a straight flow section whose surface area varies as it flows from upstream to downstream depending on the flow of the portion of the flow in the premixing circuit,- a control assembly arranged to ensure the fuel supply to the burner and configured to allow the control of at least one fuel injection parameter, the control method and the evolution of the surface of the straight flow section of the premixing circuit being configured in such a way that the portion of gas flow has, in the premixing circuit at the injection outlet, a flow speed greater than the flame speed of the fuel at the outlet section.,

[0014] Such a configuration makes it possible to significantly limit the risk of flashback, or the flame rising in the nozzle and in the burner, without having to modify the geometry of the burner when changing fuel. This makes it possible to change fuel during burner operation, without necessarily having to interrupt it. This therefore allows the use of a hydrogenated fuel when available while operating with a more conventional fuel when hydrogenated fuel is not available. Indirectly, this makes it possible to deploy heating systems operating with conventional fuels that are capable of operating with low CO2 emissions thanks to the use of a hydrogen fuel when it is available, which facilitates the transition to a lower CO2 emitting industry.

[0015] Advantageously, the invention may be combined with one or a combination of the following features:

[0016] - the control assembly is capable of controlling the supply pressure of the intake rail; this makes it possible to adapt the speed of ejection of the fuel by the injector, which makes it possible to adapt the flow rate of the flow in the premixing circuit;

[0017] - the fuel comprises gaseous hydrogen or a gaseous hydrocarbon, for example natural gas, or a mixture of the two, and the control assembly is capable of controlling at least one fuel injection parameter as a function of the combustion speed of the fuel at the outlet section; this makes it possible to adapt the operation of the burner to the type of fuel used, and therefore to adapt the flow speed of the stream in the premixing circuit as a function of the type of fuel used;

[0018] - the control unit is capable of controlling the composition of a mixture of hydrogen and gaseous hydrocarbon; this makes it possible to adapt the type of fuel used according to the fuel available to supply the burner.

[0019] In order to meet the needs of the solutions of the prior art, the invention also proposes a heating system for heating a gas flow passing through a flow vein configured to be implemented by means of a method according to the invention, comprising: - a vein burner comprising a fuel inlet ramp equipped with at least one injector extending in a longitudinal direction, and at least one flame stabilizer arranged opposite the injector, the stabilizer comprising a wall delimiting a pipe extending from upstream to downstream in the longitudinal direction and forming with the inlet ramp and the injector a premixing circuit configured to allow the mixing of the fuel and the gas, the premixing circuit comprising at least one inlet opening arranged to allow a portion of the flow to be taken from the vein to guide it into the premixing circuit,an upstream portion having a cross section delimited externally by the wall of the stabilizer and internally by the injector, and a downstream portion having a cross section delimited externally by the stabilizer wall, the injector opening into the premixing circuit at an injection outlet, the premixing circuit being configured so that it has a cross section of flow whose surface varies while circulating from upstream to downstream along the circulation of the flow in the premixing circuit, - a control assembly arranged to ensure the supply of fuel to the burner and configured to allow the control of at least one fuel injection parameter.,

[0020] The invention also proposes a vein burner for a heating system according to the invention, the vein burner comprising:- a fuel inlet manifold equipped with at least one injector extending in a longitudinal direction, and- at least one flame stabilizer arranged opposite the injector, the stabilizer comprising a wall delimiting a pipe extending from upstream to downstream in the longitudinal direction and forming with the inlet manifold and the injector a premixing circuit configured to allow the mixing of the fuel and the gas, the injector opening into the premixing circuit at an injection outlet, the premixing circuit comprising at least one inlet opening arranged to allow a portion of flow to be taken from the manifold to guide it into the premixing circuit, an upstream portion having a cross section delimited externally by the wall of the stabilizer and internally by the injector,and a downstream portion having a cross section delimited externally by a nozzle of the stabilizer, the premixing circuit being configured so that it has a cross section of flow whose surface area varies while circulating from upstream to downstream along the circulation of the flow portion in the premixing circuit, the cross section of flow having a first surface area at the injection outlet and a second surface area in the downstream portion, the first surface area representing between 40% and 70% of the second surface area.,

[0021] Advantageously, such a burner comprises one or a combination of the following characteristics:

[0022] - the nozzle has an outside diameter and an inside diameter configured so that a ratio between the inside diameter and the outside diameter is between 0.55 and 0.85, the nozzle being made of a material comprising a refractory steel; such a configuration makes it possible to ensure temperature resistance of the stabilizer, by limiting the degradation of mechanical performance despite the increase in temperature while promoting the diffusion of heat to ensure the cooling of the stabilizer;

[0023] - the nozzle has a total length and comprises an upstream portion and a downstream portion shaped to promote expansion of the flow passing through the nozzle, the downstream portion having a length configured so that a ratio between the length and the total length of the nozzle is between 0.70 and 0.85, and so that a ratio between the length and the outside diameter of the nozzle is between 0.65 and 0.75; such a configuration makes it possible to promote the expansion effect in the nozzle while optimizing the rigidity of the nozzle to limit deformations, in particular during temperature increases;

[0024] - the injectors have a substantially cylindrical geometry having an injector outer diameter and the nozzle has a minimum inner diameter, configured so that a capacity factor corresponding to a ratio between the injector outer diameter and a minimum inner diameter of the nozzle is between 0.5 and 0.8; this makes it possible to improve the suction effect of the flow portion caused by the injection of the fuel into the premixing circuit, and therefore to modulate the quantity of air in the air / gas premix in the nozzle 15 and to optimize several combustion parameters, such as for example the ignition speed, the position of the flame front relative to the nozzle 15 or the nozzle outlet, nitrogen oxide emissions;

[0025] - the injection outlet is located at a relative distance from an inlet of the nozzle in the longitudinal direction, and the nozzle has a minimum internal diameter, configured so that a drive factor corresponding to a ratio between the relative position and the minimum internal diameter of the nozzle is between -0.2 and 0.4; this makes it possible to optimize the suction capacity while limiting the risk of flashback, particularly critical when using a fuel with a high hydrogen content. BRIEF DESCRIPTION OF THE FIGURES

[0026] The figures are presented for information purposes only and in no way limit the invention.

[0027] is an overall sectional view of a vein burner according to the prior art.

[0028] is a side sectional view of a vein burner according to the prior art.

[0029] is a front sectional view, along a plane normal to the direction of circulation of the gas flow in the flow vein, representing a vein burner stabilizer according to the invention.

[0030] is a side sectional view of a vein burner stabilizer according to the invention.

[0031] is a side sectional view of a vein burner according to the invention, more particularly a detailed view of the stabilizer nozzle.

[0032] is a cross-sectional profile representation of a vein burner according to the invention, more particularly a detailed view of the stabilizer nozzle.

[0033] is a cross-sectional profile representation of a vein burner according to the invention, more particularly a detailed view of the injector.

[0034] is a schematic representation of a method for controlling a heating system according to the invention. DETAILED DESCRIPTION

[0035] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0036] The invention relates to a heating system 1 for heating a main gas flow F1 circulating in a vein 2, comprising a vein burner 3 configured to inject a gaseous fuel flow F2 into the main gas flow F1 and a control assembly 4 configured to control at least one operating parameter of the vein burner 3, the vein burner 3 comprising a premixing circuit 5 in which a portion of gas flow F3 circulates and an injector 6 configured to inject the gaseous fuel flow F2 into the premixing circuit 5 at an injection outlet 7 located between an inlet opening 51 and an outlet section 52 of the premixing circuit 5,the control assembly 4 and the premixing circuit 5 being configured in such a way that a flow velocity of the gas flow portion F3 in the premixing circuit 5 at the injection outlet 7 is greater than the flame velocity of the gaseous fuel at the outlet section 52.,

[0037] Flame speed is understood to mean the laminar flame speed of the combustion reaction of the gaseous fuel and the oxidant contained in the gas flow. The flame speed depends on the type of fuel and oxidant used but also on physical parameters, including temperature and pressure.

[0038] This makes it possible in particular to prevent the flame from propagating in the premixing circuit 5 during ignition of the gas mixture, and makes it possible to ensure that the combustion of the gas mixture is effective downstream of the premixing circuit 5. In particular, due to the temperature and pressure conditions at the different points of the premixing circuit 5, the flame speed at the outlet section 52 of the premixing circuit is higher than the flame speed further upstream, in particular at the injection outlet 7. By ensuring a circulation speed at the injection point 7 higher than the flame speed at the outlet section 52, it is ensured that the combustion reaction cannot propagate in the premixing circuit 5 as far as the injection outlet 7.

[0039] The control assembly 4 is in particular configured to enable the control of an operating parameter of the vein burner 3 in order to adapt the flow rate of the gas flow portion F3 in the premixing circuit 5 at the injection outlet 7 as a function of the flame speed of the gaseous fuel used. Such a configuration makes it possible to use various types of fuels, in order to adapt the operation of the heating system 1 according to the most abundant or least polluting fuel, depending on the desired goal. For example, an operating parameter of the vein burner 3 controlled by means of the control assembly 4 may be the flow rate of the main gas flow F1, adapted according to the type of fuel used to ensure a flow rate of the gas flow portion F3 allowing optimal operation of the burner 3.

[0040] This makes it possible, in particular, to use hydrogen gas, or a hydrocarbon gas, for example natural gas, or a mixture of hydrogen gas and hydrocarbon gas, as fuel, and to control one or more operating parameters of the heating system 1 depending on the fuel used. In addition, this allows the burner to operate with very low carbon dioxide emissions, depending on the proportion of hydrogen gas contained in the gaseous fuel, which reduces the pollutant emissions due to the operation of the burner.

[0041] In a preferred embodiment as represented in, the vein 2 of the heating system 1 extends in a longitudinal direction X, and the notions of upstream and downstream refer to the direction of circulation of the main flow of gas F1 in the vein 2, which circulates in a direction normal to the plane of representation of the.

[0042] The vein burner 3 comprises one or more intake ramps 8 extending in a transverse direction relative to the vein 2, on which one or more injectors 6 are mounted, the intake ramp 8 being configured to simultaneously supply fuel to the injectors 6 mounted on said intake ramp 8.

[0043] The injector(s) 6 mounted on the intake manifold 8 extend in the longitudinal direction X, and a stabilizer 9 is arranged opposite at least one of the injectors 6, preferably opposite each injector 6.

[0044] With reference to the, the stabilizer 9 comprises a body 10 extending in the longitudinal direction X and comprising a wall 11 delimiting a conduit extending in the longitudinal direction X, and two diverging fins 12 extending from the body 10 configured so as to deflect the main gas flow F1 on either side of the body 10 to generate a “dead” zone just downstream of the stabilizer 9, making it possible to stabilize the flame generated by the vein burner 3 by limiting the aerodynamic disturbances linked to the turbulence of the main gas flow F1 in the flame formation zone.

[0045] The stabilizer 9, the intake manifold 8 and the injector 6 are positioned in such a way that the wall 11 delimits with the injector 6 the premixing circuit 5. The premixing circuit 5 extends from upstream to downstream between an intake opening 51 and an outlet section 52. The intake opening 51 is in fluid communication with the flow stream 2 so as to admit a portion of the main gas flow F1 passing through the stream 2, and may be formed by one or more openings provided in the body 10 of the stabilizer 9, or by a space formed by the relative positioning of the stabilizer 9 and the intake manifold 8 or a space formed by the relative positioning of the stabilizer 9 and the injector 6. The outlet section 52 is in fluid communication with the stream 2, downstream of the fins 12.

[0046] The injection outlet 7 is positioned downstream of the intake opening 51 and upstream of the outlet section 52. In the embodiment shown, the injector 6 extends longitudinally projecting from the intake ramp 8 and thus extends at least partially into the wall 11, thus defining the premixing circuit 5.

[0047] In the embodiment shown in, the wall 11 comprises, from upstream to downstream, a first portion 13 extending from the intake opening 51, a second portion 14 converging from upstream to downstream, and a substantially cylindrical nozzle 15 opening at the outlet section 52. The injector 6 extends in the first portion 13 and at least partially in the second portion 14. Downstream of the injection outlet 7, the premixing circuit 5 has a substantially circular cross section.

[0048] In operation, the injector 6 injects fuel into the premixing circuit 5 towards the nozzle 15. The fuel injection causes a venturi effect which causes a pressure reduction in the premixing circuit 5 upstream of the injection outlet 7, which causes the gas flow portion F3 to be sucked in through the inlet opening 51 of the premixing circuit 5. The gas flow portion F3 mixes with the fuel in the nozzle 15 and the mixture is ejected through the outlet section 52.

[0049] The profile of the injector 6 and the wall 11 are configured so as to accelerate the flow portion F3 between the intake opening 51 and the injection outlet 7, which limits the risk of gaseous fuel rising in the premixing circuit 5 upstream of the nozzle 15. This makes it possible to preserve the mechanical integrity of the burner in vein 3 by limiting the risk of combustion at the heart of the premixing circuit 5, particularly in areas which are not designed to accommodate combustion, in particular between the intake pipe 8 and the wall 11.

[0050] With reference to the, the flow cross-section Ai of the gas flow portion F3 is defined as a cross-section of the premixing circuit 5 normal to the mean flow direction Fm of the gas flow portion F3. Upstream of the injection outlet 7, a cross-section of the flow circulates by being channeled externally by the wall 11 of the stabilizer 9 and internally by the injector 6, in fact “surrounding” the injector 6. Downstream of the injection outlet 7, the flows combine. A plurality of cross-sections Aj, Ak, Al, Am are shown as an illustration of the evolution of the flow cross-section Ai during the circulation of the gas flow portion F3 in the premixing circuit 5.

[0051] Advantageously, the flow cross-section Ai has a first surface A1 at the injection outlet 7 and a second surface A2 at the nozzle 15, the first surface A1 representing a proportion of between 40% and 70% of the second surface A2. Such a ratio makes it possible to ensure an acceleration of the speed of the gas mixture upstream of the injection outlet 7. In certain embodiments, the nozzle 15 has a slightly frustoconical profile, also the flow cross-section in the nozzle 15 has a second surface A2 which varies along the circulation of the flow portion F3 in the nozzle 15. In this embodiment, the first surface A1 represents between 40% and 70% of the second surface S2 regardless of the position of the flow cross-section Ai in the nozzle 15.

[0052] With reference to the, advantageously, the nozzle 15 is delimited radially by a wall having an inner diameter Di and an outer diameter De, and extends along the longitudinal direction X between an inlet section 16 and the outlet section 52. Here, the term inlet section 16 of the nozzle 15 is understood to mean the cross section along the longitudinal axis X at the upstream end of a lateral separation wall between two adjacent nozzles 15, the separation wall not being shown in the figures because it is outside the section plane. Advantageously, the ratio between the inner diameter and the outer diameter (Di / De) is between 0.55 and 0.85. The outer diameter De may be between 20mm and 30mm, for example 26mm, and the inner diameter Di may be between 11mm and 25mm.The wall is made of a material configured to maintain optimal mechanical characteristics despite exposure to high temperatures (around 1000°C), advantageously a refractory austenitic steel, for example AISI 314. Such a material has the particular advantage of not exhibiting any acceleration of hot corrosion, nor of an absence of qualified mechanical resistance for equilibrium temperatures of the order of 1000°C, while efficiently conducting heat. Indeed, this combination of material and geometric configuration makes it possible to provide a wall thickness 11 sufficient for the heat to diffuse efficiently from the nozzle 15 to the other parts of the stabilizer 9, in particular the fins 12.

[0053] In a preferred embodiment, the nozzle 15 has a converging upstream portion 15a and a downstream portion 15b advantageously having an internal diameter Di which increases while circulating from upstream to downstream within the downstream portion 15b of the nozzle 15. The downstream portion 15b therefore extends from upstream to downstream from a section having a minimum internal diameter Di1 to the outlet section 52 having a maximum internal diameter Di2. The minimum internal diameter Di1 of the downstream portion 15b is therefore the minimum internal diameter Di of the nozzle 15. In the downstream portion 15b, the ratio (Di1 / Di2) between the minimum internal diameter Di1 and the maximum internal diameter Di2 is between 0.85 and 0.95, for example 0.89. The downstream portion 15b may have a minimum internal diameter Di1 of between 15mm and 22mm, for example 18mm, and a maximum internal diameter Di2 of between 16mm and 26mm, for example 20.5mm.The downstream portion 15b has a length L representing a proportion of between 0.70 and 0.85 of the total length Lt of the nozzle 15. The downstream portion 15b of the nozzle has a length L of between 15mm and 25mm, for example 18mm, and the nozzle 15 has a total length Lt of between 20mm and 35mm, for example 25mm. This makes it possible to promote the expansion of the gas flow portion F3 during circulation in the nozzle 15, and thus to limit the risk of flame rising in the nozzle 15.

[0054] Advantageously, the downstream portion 15b of the nozzle 15 has a length L representing a proportion of the outer diameter De of the nozzle 15 (L / De) of between 0.65 and 0.75. Such a configuration makes it possible to promote the expansion phenomenon within the nozzle 15 by maximizing the length L of the downstream portion 15b of the nozzle while making it possible to guarantee significant structural rigidity thanks to the ratio (L / De) between the length L of the downstream portion 15b of the nozzle 15 and the outer diameter De of the nozzle 15.

[0055] The combination of the geometric characteristics, in particular the ratio (Di1 / Di2) between the minimum internal diameter Di1 and the maximum internal diameter Di2 and the ratio (L / De) between the length L and the external diameter De of the nozzle 15, and the materials of the nozzle 15 allows the mechanical properties of the stabilizer 9 to be maintained during temperature increases, which is particularly critical when using fuel with a high hydrogen content. Indeed, the ignition of a mixture with a high hydrogen content is faster than for a conventional hydrocarbon fuel, which implies that the combustion reaction occurs in an area closer to the burner 3 than for a conventional hydrocarbon fuel, thus resulting in a greater temperature increase of the stabilizer 9.

[0056] With reference to the, advantageously, the injectors 6 have a substantially cylindrical geometry having an injector outer diameter δe. The injector outer diameter δe may be between 10mm and 20mm, for example 12mm. Advantageously, the injector outer diameter δe and the minimum internal diameter Di1 of the nozzle 15 are configured so that a ratio (δe / Di1), called capacity factor φc, between the injector outer diameter δe and the minimum internal diameter Di1 of the nozzle 15 is between 0.5 and 0.8. The capacity factor φc defines the theoretical maximum suction capacity generated by the venturi effect. Such a range of values ​​of the capacity factor φc makes it possible to modulate the quantity of air in the air / gas premix in the nozzle 15 and to optimize several combustion parameters, such as the ignition speed, the position of the flame front relative to the nozzle 15 or the nozzle outlet, and nitrogen oxide emissions.

[0057] Furthermore, the injection outlet 7 is located at a relative distance λ relative to the inlet section 16 of the nozzle 15 in the longitudinal direction X, the relative distance λ being configured so that a ratio (λ / Di1), called the drive factor φe, between the relative distance λ and the minimum internal diameter Di1 of the nozzle 15 is between -0.2 and 0.4. The relative distance λ is considered positive when the injection outlet 7 is located upstream of the inlet section 16 of the nozzle 15, and negative when the injection outlet is located downstream of the inlet section 16 of the nozzle 15. The relative distance λ can be between -4mm and 8mm, for example 4.5mm. Such a range of values ​​of the entrainment factor φe makes it possible to optimize the suction capacity while limiting the risk of flashback.Such a range of values ​​of the entrainment factor φe makes it possible to generate a bulk in the premixing circuit 5 upstream of the inlet of the nozzle 15 to form an acceleration zone of the flow portion F3 upstream of the mixing point with the fuel ejected through the injection outlet 7. This makes it possible to promote the continuous acceleration of the flow from this acceleration zone to the outlet section 52 of the premixing circuit 5, which limits the risk of flame rise in the premixing circuit 5, which is particularly important when using hydrogen in the fuel.

[0058] The control assembly 4 is configured to allow the control of at least one operating parameter of the vein burner 3, in particular as a function of the type of gaseous fuel used. The associated control method is configured to control said operating parameter of the vein burner 3 in such a way that the speed of the gas flow portion F3 at the injection outlet 7 is greater than the flame speed of the gaseous fuel used. This makes it possible to avoid flashback in the premixing circuit 5 regardless of the type of fuel used. This is particularly advantageous because it allows the vein burner 3 to be able to operate with different types of fuels, in particular hydrogen or natural gas or a mixture of the two, without introducing any architectural modification depending on the type of fuel used.The use of heating system 1 is simplified, and the utilization rate is improved because there is no need to carry out a modification operation of the burner in vein 3 depending on the type of fuel used.

[0059] Advantageously, the control assembly 4 comprises a means for controlling the pressure 17 of the gaseous fuel in the intake rail 8, comprising for example a pump or a piston. The pressure setpoint can be adjusted by an operator depending on the type of gaseous fuel used and the control assembly 4 maintains the pressure level in the intake rail 8 at the set setpoint level.

[0060] Advantageously, the control assembly 4 comprises a setpoint generator 18 configured to generate a gaseous fuel pressure setpoint in the intake manifold 8 as a function of the type of fuel used in real time. This makes it possible to improve the fluidity of use of the heating system 1 which adapts its operation without an operator needing to make a modification to the operating parameters, which in particular makes it possible to switch from one type of fuel to another smoothly without the heating system 1 undergoing any interruption in its operation.

[0061] Advantageously, the intake rail 8 is supplied by means of a supply circuit comprising several fuel sources in parallel opening into a mixer, the output of the mixer being in fluid communication with the intake rail 8. A first source supplies a first fuel, a second source supplies a second fuel, and depending on the type of fuel that one wishes to use, it is possible to switch continuously from one fuel to the other by progressive substitution of one of the first and second types of fuel. The setpoint generator 18 adapts the pressure setpoint in the intake rail 8 continuously depending on the fuel mixture used.

[0062] Advantageously, the control assembly 4 comprises a pressure estimator 19 configured to estimate the pressure of the gaseous fuel in the intake rail 8, which makes it possible to regulate the pressure in the intake rail 8 as a function of the status feedback from the pressure estimator 19. Closed-loop regulation improves the safety of the system by ensuring that the pressure in the intake rail 8 is maintained at the setpoint level despite a disturbance, for example degraded operation of the pressure control means 17.

[0063] Advantageously, the setpoint generator 18 is also configured to generate a setpoint as a function of a parameter of the main gas flow F1 passing through the vein 2. For example, by adapting the pressure setpoint in the intake manifold 8 as a function of the flow rate of the main gas flow F1.

[0064] Advantageously, the control assembly 4 comprises a processing unit, comprising a processor and a memory comprising code data capable of, when processed by means of the processor, implementing the method for controlling the heating system 1.

[0065] The piloting process 1 can be expressed in the form of steps, including the following steps:

[0066] S1: Determination of a set value of an injection parameter of the fuel used configured to ensure a flow rate of the flow portion F3 at the injection outlet 7 greater than the flame rate of the fuel used;

[0067] S2: Injection of the previously determined setpoint value into a control means so as to vary the injection parameter of the fuel used and cause a modification of the flow rate of the flow portion F3 at the injection outlet 7.

[0068] The method advantageously comprises a step S0 of acquiring a burner operating status data item and a fuel used status data item, and a step S1' during which the determination of the setpoint value is carried out as a function of the data acquired during step S0. During step S0, the measured burner status parameters 3 comprise, for example, the flow rate of the main gas flow F1.

Claims

Method for controlling a heating system (1) for heating a gas flow passing through a flow vein (2), the system comprising: - a vein burner (3) comprising at least one fuel intake ramp (8) equipped with at least one injector (6) arranged to inject fuel into a premixing circuit (5) configured to allow the fuel to be mixed with a portion of the gas, the injector (6) opening into the premixing circuit (5) at an injection outlet (7), the premixing circuit (5) being configured to allow a portion of the gas flow (F3) to be taken from the vein (2) to guide it into the premixing circuit (5) to an outlet section (52), the premixing circuit (5) being shaped so that it has a straight flow section (Ai) whose surface varies while circulating from upstream to downstream according to the circulation of the portion of flow (F3) in the premixing circuit (5),- a control assembly (4) arranged to ensure the supply of fuel to the burner and configured to allow the control of at least one fuel injection parameter, the control method and the evolution of the surface of the cross-section (Ai) of flow being configured in such a way that the portion of flow (F3) of gas in the premixing circuit (5) at the injection outlet (7) has a flow speed greater than the flame speed of the fuel at the outlet section (52)., Control method according to claim 1, in which the control assembly (4) is capable of controlling the supply pressure of the intake rail (8). Control method according to one of the preceding claims, in which the fuel comprises gaseous hydrogen or a gaseous hydrocarbon, for example natural gas, or a mixture of the two, and in which the control assembly (4) is capable of controlling at least one fuel injection parameter as a function of the combustion speed of the fuel at the outlet section (52). Control method according to claim 3, in which the control assembly (4) is capable of controlling the composition of a mixture of hydrogen and gaseous hydrocarbon. Heating system (1) for heating a gas flow passing through a flow vein (2) configured to be implemented by means of a method according to one of claims 1 to 4, comprising:- a vein burner (3) comprising a fuel intake ramp (8) equipped with at least one injector (6) extending in a longitudinal direction, and at least one flame stabilizer (9) arranged opposite the injector (6), the stabilizer (9) comprising a wall delimiting a pipe (11) extending from upstream to downstream in the longitudinal direction and forming with the intake ramp (8) and the injector (6) a premixing circuit (5) configured to allow the mixing of the fuel and the gas, the premixing circuit (5) comprising at least one intake opening (51) arranged to allow a portion of flow (F3) to be taken from the vein (2) to guide it in the circuit premix (5),an upstream portion having a cross section delimited externally by the wall (11) of the stabilizer (9) and internally by the injector (6), and a downstream portion having a cross section delimited externally by the wall (11) of the stabilizer (9), the injector (6) opening into the premixing circuit (5) at an injection outlet (7), the premixing circuit (5) being configured so that it has a cross section (Ai) of flow whose surface varies while circulating from upstream to downstream along the circulation of the flow in the premixing circuit (5), - a control assembly (4) arranged to ensure the supply of fuel to the burner and configured to allow the control of at least one fuel injection parameter., A vein burner (3) for a heating system (1) according to claim 5, the vein burner (3) comprising:- a fuel intake ramp (8) equipped with at least one injector (6) extending in a longitudinal direction, and- at least one flame stabilizer (9) arranged opposite the injector (6), the stabilizer (9) comprising a wall delimiting a pipe (11) extending from upstream to downstream in the longitudinal direction and forming with the intake ramp (8) and the injector (6) a premixing circuit (5) configured to allow the mixing of the fuel and the gas, the injector (6) opening into the premixing circuit (7) at an injection outlet (7), the premixing circuit (5) comprising at least one intake opening (51) arranged to allow a portion of flow (F3) to be taken from the vein (2) for the guide in the premix circuit (5),an upstream portion having a cross section delimited externally by the wall of the stabilizer (9) and internally by the injector (6), and a downstream portion having a cross section delimited externally by a nozzle (15) of the stabilizer (9), the premixing circuit (5) being configured so that it has a cross section (Ai) of flow whose surface varies while circulating from upstream to downstream along the circulation of the flow portion in the premixing circuit (5), the cross section having a first surface (A1) at the injection outlet (7) and a second surface (A2) in the downstream portion, the first surface (A1) representing between 40% and 70% of the second surface (A2)., Burner according to claim 6, wherein the nozzle (15) has an outer diameter (De) and an inner diameter (Di) configured so that a ratio between the inner diameter and the outer diameter (Di / De) is between 0.55 and 0.85, and wherein the nozzle (15) is made of a material comprising a refractory steel. Burner according to claim 7 in which the nozzle (15) has a total length (Lt) and comprises an upstream portion (15a) and a downstream portion (15b) shaped to promote expansion of the flow passing through the nozzle, the downstream portion (15b) having a length (L) configured so that a ratio (L / Lt) between the length (L) and the total length (Lt) of the nozzle (15) is between 0.70 and 0.85, and so that a ratio (L / De) between the length (L) and the external diameter (De) of the nozzle (15) is between 0.65 and 0.

75. Burner according to claim 6 wherein the injectors (6) have a substantially cylindrical geometry having an injector outer diameter (δe) and wherein the nozzle (15) has a minimum inner diameter (Di1), configured so that a capacity factor (φc) corresponding to a ratio (δe / Di1) between the injector outer diameter (δe) and a minimum inner diameter (Di1) of the nozzle is between 0.5 and 0.8, Burner according to claim 6, wherein the injection outlet (7) is located at a relative position (λ) of an inlet section (16) of the nozzle (15) in the longitudinal direction (X), and wherein the nozzle (15) has a minimum internal diameter (Di1), configured so that a drive factor (φe) corresponding to a ratio (λ / Di1) between the relative position (λ) and the minimum internal diameter (Di1) of the nozzle (15) is between -0.2 and 0.4.

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