Mixed fuel burner

Abstract

The present invention relates to a heating system and to a control method of controlling a heating system for heating a primary gas flow through a flow duct, the system comprising: an in-duct burner comprising at least one fuel intake manifold provided with at least one injector, the at least one injector is arranged to inject fuel into the pre-mixing circuit through the injection outlet; and a control assembly arranged to supply fuel to the combustor and configured to allow control of at least one fuel injection parameter, the control method and variation in the cross-sectional flow area of the premix circuit are configured such that the flow velocity of the airflow portion at the injection outlet is greater than the flame velocity of the fuel in the outlet region.

Description

Technical Field

[0001] The technical field of this invention is burners intended to be placed in ducts to heat airflow circulating in the ducts, also known as in-duct burners. Background Technology

[0002] In general, such as [ Figure 1 As shown, an in-line burner assembled into a flow duct for airflow F includes a duct section A in which one or more distribution pipes B extend transversely to the airflow direction. Pipes B are supplied with fuel and punctured with orifices (possibly fitted with injectors) to eject a fuel gas jet into duct A, thereby locally forming a fuel-oxidizer mixture that is ignited to produce combustion. Combustion is maintained by continuously injecting fuel into the oxidizer stream.

[0003] Typically, the injector is pointed downstream, and the burner is characterized by a deflector C attached to pipe B to deflect the oxidizing gas flow to create a protected zone downstream of the deflector C, in which the flame can develop in a stable manner.

[0004] [ Figure 2 An embodiment of the prior art deflector shown is specifically described in document FR 2 622 277. A tube B is connected to a fuel gas source and pierced by orifices through which a fuel jet is emitted in the direction of gas flow F. A stabilizer C has two diverging fins D forming the deflector, which are connected to a sheath E in which the tube B is housed. The tube B is fitted with injectors I, which emit a fuel jet through nozzles G, thereby inducing a partial vacuum that draws in a portion of the gas through an opening H in the tube E.

[0005] Therefore, a gas-fuel mixture is formed in nozzle G, and this gas-fuel mixture provides a stable combustion reaction downstream of stabilizer C.

[0006] This type of application is particularly useful for hydrocarbon fuels, such as natural gas.

[0007] In the context of today's industrial decarbonization, using hydrogen as a fuel for industrial combustion is an important alternative to hydrocarbon fuels, which allows us to significantly limit CO2 emissions for a given amount of heat energy supplied by the combustion reaction.

[0008] Given that the hydrogen production industry and supply chain are still in their early stages of development, and given the uncertainty surrounding cost and the actual availability of hydrogen resources, it remains wise to retain the flexibility to use more conventional fuels, such as natural gas.

[0009] This pursuit of flexibility is constrained by the fundamental differences between hydrogen combustion and the combustion of conventional fuel gases, such as natural gas.

[0010] Hydrogen combustion is very different from natural gas combustion. Compared to natural gas, hydrogen has a much lower density (1 / 7), a much higher ignition rate (up to 10 times faster than natural gas, especially in substoichiometric combustion), a hotter flame (on average 150°C higher under the same conditions and air ratio), and a flammability zone that is at least 5 times wider than that in air.

[0011] Therefore, the hydrogen flame is hotter and more intense once it emerges from the burner nose, and the speed of the hydrogen flame also means that there is a high risk of backfire inside the nozzle G (which may spread to the injector I), which will cause very serious damage to the stabilizer C.

[0012] Therefore, a solution is needed that allows in-pipe burners to be used with different types of fuels, including hydrogen and natural gas or a mixture of both. Summary of the Invention

[0013] To meet the needs of solutions proposed in the prior art, this invention proposes a control method for controlling a heating system for heating the main airflow flowing through a flow pipe, the system comprising:

[0014] - An in-pipe burner comprising at least one fuel intake manifold, the at least one fuel intake manifold being provided with at least one injector arranged to inject fuel into a premixing circuit configured such that the fuel can be mixed with a portion of the gas, the injector appearing at an injection outlet in the premixing circuit, the premixing circuit being configured such that a portion of the gas flow can be drawn from the pipe and guided through the premixing circuit to an outlet region, the premixing circuit being shaped such that it has a flow cross-sectional area whose surface area changes along the flow of that portion of the flow in the premixing circuit as that portion of the gas flowes from upstream to downstream.

[0015] - A control assembly arranged to supply fuel to the burner and configured to allow control of at least one fuel injection parameter.

[0016] The control method and the change in the cross-sectional flow area of ​​the premixed circuit are configured such that the flow velocity of the gas flow portion in the premixed circuit at the injection outlet is greater than the flame velocity of the fuel in the outlet region.

[0017] This design significantly reduces the risk of backfire or flame re-entry into the nozzle and burner without requiring modifications to the burner geometry during fuel changes. This allows for fuel changes while the burner is running without interrupting its operation. It also allows for the use of hydrogen fuel when available and operation with more conventional fuels when unavailable. Indirectly, this enables the deployment of heating systems that operate on conventional fuels, which, due to the availability of hydrogen, can operate with low CO2 emissions, thus facilitating the transition to industries with lower CO2 emissions.

[0018] Advantageously, the present invention can be combined with one or a combination of the following features:

[0019] - The control component can control the supply pressure to the intake manifold; this allows adjustment of the rate at which fuel is injected through the injector, which in turn allows adjustment of the flow rate in the premixing circuit.

[0020] - The fuel comprises gaseous hydrogen or gaseous hydrocarbons or a mixture of both, such as natural gas, and the control component is capable of controlling at least one fuel injection parameter based on the combustion rate of the fuel in the outlet area; this allows the operation of the burner to be adapted to the type of fuel used, and thus the flow rate in the premixed circuit to be adjusted according to the type of fuel used.

[0021] - This control component can control the composition of the hydrogen-hydrogen mixture; this allows the type of fuel used to be adjusted according to the fuel available to supply the burner.

[0022] To meet the needs of existing technical solutions, the present invention also proposes a heating system configured to use the method according to the invention for heating an airflow passing through a flow channel, the heating system comprising:

[0023] - An in-pipe burner comprising a fuel intake manifold and at least one flame stabilizer, the fuel intake manifold having at least one injector extending longitudinally, the at least one flame stabilizer being arranged opposite the injector, the stabilizer including a wall defining a duct extending downstream in the longitudinal direction and forming a premixing circuit with the intake manifold and the injector, the premixing circuit being configured to mix fuel and gas, the premixing circuit including at least one intake opening, an upstream portion, and a downstream portion, the at least one intake opening being arranged such that a portion of the flow can be drawn from the duct and guided through the premixing circuit, the upstream portion having a cross-section externally defined by the stabilizer wall and internally defined by the injector, the downstream portion having a cross-section externally defined by the stabilizer wall, the injector entering the premixing circuit at an injection outlet, the premixing circuit being configured to have a flow cross-sectional area whose surface varies along the flow in the premixing circuit as the portion of the flow circulates from upstream to downstream.

[0024] - A control component arranged to supply fuel to the burner and configured to allow control of at least one fuel injection parameter.

[0025] The present invention also proposes an in-pipe burner for a heating system according to the present invention, the in-pipe burner comprising:

[0026] - A fuel intake manifold, wherein the fuel intake manifold is provided with at least one injector extending in the longitudinal direction, and

[0027] - At least one flame stabilizer, arranged opposite the injector, the stabilizer including a wall defining a duct extending from upstream to downstream in the longitudinal direction and forming a premixing circuit together with the intake manifold and the injector, the premixing circuit being configured to mix fuel and gas, the injector being fed into the premixing circuit at its injection outlet.

[0028] The premixing circuit includes at least one inlet opening, an upstream portion, and a downstream portion. The at least one inlet opening is designed to allow a portion of the flow to be drawn from the duct and directed into the premixing circuit. The upstream portion has a cross-section externally defined by the stabilizer wall and internally defined by the injector. The downstream portion has a cross-section externally defined by the stabilizer nozzle.

[0029] The premixed circuit is configured to have a flow cross-sectional area whose area varies along the circulation of the flow portion in the premixed circuit as the flow circulates from upstream to downstream. The flow cross-sectional area has a first surface area at the injection outlet and a second surface area in the downstream portion, the first surface area being between 40% and 70% of the second surface area.

[0030] Advantageously, this burner includes one or a combination of the following features:

[0031] - The nozzle has an outer diameter and an inner diameter, which are configured such that the ratio between the inner diameter and the outer diameter is between 0.55 and 0.85. The nozzle is made of a material including fire-resistant steel. This construction ensures the temperature resistance of the stabilizer, limiting the deterioration of mechanical properties even when the temperature rises, while promoting heat diffusion to ensure the cooling of the stabilizer.

[0032] - The nozzle has an overall length and includes an upstream portion and a downstream portion, which are shaped to facilitate the expansion of the flow through the nozzle. The downstream portion has a length configured such that the ratio between the length and the overall length of the nozzle is between 0.70 and 0.85, and the ratio between the length and the outer diameter of the nozzle is between 0.65 and 0.75. This configuration facilitates the expansion effect in the nozzle while optimizing the nozzle stiffness to limit deformation, especially during temperature rise.

[0033] - The injector has a generally cylindrical geometry with an outer diameter and a minimum inner diameter. The outer diameter and the minimum inner diameter are configured such that the capacity factor corresponding to the ratio between the outer diameter and the minimum inner diameter is between 0.5 and 0.8. This improves the suction effect of the flow portion caused by fuel injection into the premixed circuit, thus regulating the amount of air in the air / gas premix in the nozzle 15 and optimizing several combustion parameters, such as ignition rate, flame front positioning relative to the nozzle 15 or nozzle outlet, and nitrogen oxide emissions.

[0034] - The injection outlet is located at a relative distance from the nozzle inlet in the longitudinal direction, and the nozzle has a minimum inner diameter. The relative positioning and the minimum inner diameter are configured such that the ejector factor corresponding to the ratio between the relative positioning and the minimum inner diameter of the nozzle is between -0.2 and 0.4. This optimizes the suction capability while limiting the risk of backfire, which is especially critical when using fuels with high hydrogen content. Attached Figure Description

[0035] The accompanying drawings are illustrative and in no way limit the scope of the invention.

[0036] [ Figure 1 This is a cross-sectional overview of an in-pipe burner based on existing technology.

[0037] [ Figure 2 [This is a cross-sectional profile view of an in-pipe burner based on existing technology.]

[0038] [ Figure 3 [Illustration 1] is a front cross-sectional view of the in-pipe burner stabilizer according to the invention in a plane orthogonal to the direction of gas flow in the flow pipe.

[0039] [ Figure 4 [ ] is a cross-sectional profile view of the in-pipe burner stabilizer according to the present invention.

[0040] [ Figure 5 [Illustration 1] is a cross-sectional profile view of the burner inside the pipe according to the present invention, and in particular a detailed view of the stabilizer nozzle.

[0041] [ Figure 6 [ ] is a detailed view of the profile cross-section of the in-pipe burner according to the present invention, especially the stabilizer nozzle.

[0042] [ Figure 7 [Illustration 1] is a detailed view of the profile cross-section of the burner in the pipe according to the present invention, especially the injector.

[0043] [ Figure 8 [Illustration] is a schematic diagram of a method for controlling a heating system according to the present invention. Detailed Implementation

[0044] Unless otherwise specified, the same elements appearing in different figures have the same reference numerals.

[0045] The present invention relates to a heating system 1 for heating a main airflow F1 circulating in a pipe 2, the heating system comprising: an in-pipe burner 3 configured to inject a gaseous fuel stream F2 into the main airflow F1; and a control assembly 4 configured to control at least one operating parameter of the in-pipe burner 3, the in-pipe burner 3 comprising: a premixing circuit 5 in which a portion of the airflow F3 circulates; and an injector 6 configured to inject the gaseous fuel stream F2 into the premixing circuit 5 at an injection outlet 7 located between an inlet opening 51 and an outlet region 52 of the premixing circuit 5, the control assembly 4 and the premixing circuit 5 being configured such that the flow velocity of the portion of the airflow F3 in the premixing circuit 5 at the injection outlet 7 is greater than the flame velocity of the gaseous fuel in the outlet region 52.

[0046] "Flame speed" refers to the laminar flame speed of the combustion reaction between gaseous fuel and the oxidizer contained in the gas stream. Flame speed depends not only on the type of fuel and oxidizer used, but also on physical parameters such as temperature and pressure.

[0047] Specifically, this prevents the flame from spreading into the premixed circuit 5 when the gas mixture is ignited, and ensures efficient combustion of the gas mixture downstream of the premixed circuit 5. Specifically, due to the temperature and pressure conditions at various points in the premixed circuit 5, the flame velocity in the outlet region 52 of the premixed circuit is higher than the flame velocity further upstream, particularly at the injection outlet 7. By ensuring that the flow velocity at the injection point 7 is higher than the flame velocity in the outlet region 52, it is ensured that the combustion reaction cannot propagate through the premixed circuit 5 to the injection outlet 7.

[0048] Specifically, the control component 4 is configured to control the operating parameters of the in-duct burner 3 to adjust the flow velocity of the gas stream portion F3 within the premixed circuit 5 at the injection outlet 7 according to the flame velocity of the gaseous fuel used. This configuration allows for the use of various types of fuel, enabling the operation of the heating system 1 to be adapted to supply the most abundant or least polluting fuel depending on the desired objective. For example, the operating parameters of the in-duct burner 3 controlled by the control component 4 could be the flow velocity of the main gas stream F1, adapted to the type of fuel used to ensure that the flow velocity of the gas stream portion F3 achieves optimal operation of the burner 3.

[0049] Specifically, this allows the use of hydrogen or hydrocarbon gases (such as natural gas) or a mixture of hydrogen and hydrocarbon gases as fuel, and enables the control of one or more operating parameters of the heating system 1 based on the fuel used. This also allows the burner to operate with very low carbon dioxide emissions (depending on the proportion of hydrogen contained in the gaseous fuel), thereby reducing pollutant emissions from burner operation.

[0050] In such as [ Figure 3 In the preferred embodiment shown, the pipe 2 of the heating system 1 extends in the longitudinal direction X, and the concepts of upstream and downstream refer to the circulation direction of the main airflow F1 in the pipe 2, which is in conjunction with... Figure 3 The flow is in the direction orthogonal to the plane shown.

[0051] The in-pipe burner 3 includes one or more intake manifolds 8 extending transversely to the in-pipe burner 2, and one or more injectors 6 mounted on the one or more intake manifolds, the intake manifolds 8 being configured to simultaneously supply fuel to the injectors 6 mounted on the intake manifolds 8.

[0052] The injector 6 mounted on the intake manifold 8 extends in the longitudinal direction X, and the stabilizer 9 is arranged opposite to at least one of the injectors 6, preferably opposite to each injector 6.

[0053] refer to[ Figure 4 The stabilizer 9 includes a body 10 and two diverging fins 12. The body extends along the longitudinal direction X and includes a wall 11 defining a duct extending along the longitudinal direction X. The two diverging fins extend from the body 10 and are configured to deflect the main airflow F1 on either side of the body 10 to create a "dead" zone directly downstream of the stabilizer 9, thereby stabilizing the flame generated by the burner 3 in the duct by limiting aerodynamic disturbances caused by turbulence in the main airflow F1 in the flame forming zone.

[0054] Stabilizer 9, intake manifold 8, and injector 6 are positioned such that wall 11, together with injector 6, defines premixing circuit 5. Premixing circuit 5 extends from upstream to downstream between intake opening 51 and outlet region 52. Intake opening 51 is in fluid communication with flow duct 2 to allow a portion of the main airflow F1 to flow through duct 2, and may be formed by one or more openings in the body 10 of stabilizer 9, or by a space formed by the relative positioning of stabilizer 9 and intake manifold 8, or by a space formed by the relative positioning of stabilizer 9 and injector 6. Outlet region 52 is in fluid communication with duct 2 downstream of fin 12.

[0055] The injection outlet 7 is located downstream of the intake opening 51 and upstream of the outlet region 52. In the illustrated embodiment, the injector 6 protrudes longitudinally from the intake manifold 8 and thus extends at least partially into the wall 11, thereby defining the premixing circuit 5.

[0056] exist[ Figure 4 In the embodiment shown, wall 11 includes, from upstream to downstream, a first portion 13 extending from intake opening 51, a second portion 14 converging from upstream to downstream, and a generally cylindrical nozzle 15 opening at outlet region 52. Injector 6 extends into the first portion 13 and at least partially into the second portion 14. Downstream of injection outlet 7, premixed circuit 5 has a generally circular cross-section.

[0057] During operation, injector 6 injects fuel into the premixing circuit 5 in the direction of nozzle 15. The fuel injection produces a Venturi effect, which causes a pressure drop in the premixing circuit 5 upstream of the injection outlet 7, resulting in the intake of airflow portion F3 through the intake opening 51 of the premixing circuit 5. Airflow portion F3 mixes with the fuel in nozzle 15, and the mixture is ejected through the outlet region 52.

[0058] The contours of the injector 6 and wall 11 are configured to accelerate the flow portion F3 between the intake opening 51 and the injection outlet 7, thereby limiting the risk of backfire of gaseous fuel within the premixed circuit 5 upstream of the nozzle 15. This maintains the mechanical integrity of the combustor 3 within the duct by limiting the risk of combustion at the center of the premixed circuit 5, especially in areas not designed for combustion, such as between the intake duct 8 and wall 11.

[0059] refer to[ Figure 5 The flow cross-section Ai of the airflow section F3 is defined as the cross-section of the premixing circuit 5 orthogonal to the average flow direction Fm of the airflow section F3. Upstream of the injection outlet 7, the flow cross-section is guided externally by the wall 11 of the stabilizer 9 and internally by the injector 6, thus effectively “surrounding” the injector 6. Downstream of the injection outlet 7, the flow merges. Several cross-sections Aj, Ak, Al, and Am are shown to illustrate the variation of the flow cross-sectional area Ai during the circulation of the airflow section F3 through the premixing circuit 5.

[0060] Advantageously, the flow cross-sectional area Ai has a first surface area A1 at the horizontal plane of the injection outlet 7 and a second surface area A2 at the horizontal plane of the nozzle 15, with the first surface area A1 accounting for between 40% and 70% of the second surface area A2. This ratio ensures acceleration of the gas mixture velocity upstream of the injection outlet 7. In some embodiments, the nozzle 15 has a slightly truncated conical profile, so that the cross-sectional area of ​​the flow in the nozzle 15 has a second surface area A2 that varies along the flow portion F3 in the nozzle 15. In this embodiment, regardless of the positioning of the flow cross-sectional area Ai in the nozzle 15, the first surface area A1 accounts for between 40% and 70% of the second surface area S2.

[0061] refer to[ Figure 6Advantageously, the nozzle 15 is radially defined by a wall having an inner diameter Di and an outer diameter De, and extends along the longitudinal direction X between the inlet section 16 and the outlet section 52. Here, the inlet section 16 of the nozzle 15 means the cross-section along the longitudinal axis X at the upstream end of the lateral partition wall between two adjacent nozzles 15, which is not shown in the figure because it is outside the plane of the cross-section. Advantageously, the ratio of the inner diameter to the outer diameter (Di / De) is between 0.55 and 0.85. The outer diameter De may be between 20 mm and 30 mm, for example 26 mm, and the inner diameter Di may be between 11 mm and 25 mm. The wall is made of a material configured to maintain optimal mechanical properties even when exposed to high temperatures (about 1000°C), advantageously a fire-resistant austenitic steel, such as AISI 314. This material has the particular advantage of not accelerating hot corrosion while conducting heat efficiently, and also does not lack adequate mechanical strength at an equilibrium temperature of about 1000°C. In fact, this combination of materials and geometry provides sufficient wall thickness 11 to allow heat to diffuse efficiently from nozzle 15 to the other parts of stabilizer 9, particularly fins 12.

[0062] In a preferred embodiment, the nozzle 15 has a converging upstream portion 15a and a downstream portion 15b, the downstream portion advantageously having an inner diameter Di that increases as the airflow flows from upstream to downstream within the downstream portion 15b of the nozzle 15. Thus, the downstream portion 15b extends from upstream to downstream from a section having a minimum inner diameter Di1 to an outlet section 52 having a maximum inner diameter Di2. Therefore, the minimum inner diameter Di1 of the downstream portion 15b is the minimum inner diameter Di of the nozzle 15. In the downstream portion 15b, the ratio (Di1 / Di2) between the minimum inner diameter Di1 and the maximum inner diameter Di2 is between 0.85 and 0.95, for example, 0.89. The downstream portion 15b may have a minimum inner diameter Di1 between 15 mm and 22 mm, for example, 18 mm, and a maximum inner diameter Di2 between 16 mm and 26 mm, for example, 20.5 mm. The downstream portion 15b has a length L, which represents a proportion of the total length Lt of the nozzle 15 between 0.70 and 0.85. The downstream portion 15b of the nozzle has a length L between 15 mm and 25 mm, for example, 18 mm, and the nozzle 15 has a total length Lt between 20 mm and 35 mm, for example, 25 mm. This promotes the expansion of the F3 portion of the airflow as it circulates through the nozzle 15, thereby limiting the risk of backfire in the nozzle 15.

[0063] Advantageously, the downstream portion 15b of the nozzle 15 has a length L, which represents the ratio (L / De) of the outer diameter De of the nozzle 15 between 0.65 and 0.75. This configuration promotes expansion within the nozzle 15 by maximizing the length L of the downstream portion 15b of the nozzle, while ensuring high structural stiffness due 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.

[0064] The combination of geometric properties (especially the ratio between the minimum inner diameter Di1 and the maximum inner diameter Di2 of nozzle 15 (Di1 / Di2) and the ratio between the length L and the outer diameter De (L / De)) and the material of nozzle 15 enables the mechanical properties of stabilizer 9 to be maintained during temperature rise, which is particularly critical when using fuels with high hydrogen content. In fact, igniting a mixture with high hydrogen content is faster than igniting a conventional hydrocarbon fuel, meaning that the combustion reaction occurs in a zone closer to burner 3 than with conventional hydrocarbon fuels, resulting in a greater temperature rise in stabilizer 9.

[0065] refer to[ Figure 7 Advantageously, the injector 6 has a generally cylindrical geometry with an outer diameter δe. The outer diameter δe can be between 10 mm and 20 mm, for example, 12 mm. Advantageously, the outer diameter δe of the injector and the minimum inner diameter Di1 of the nozzle 15 are configured such that the ratio (δe / Di1) between the outer diameter δe of the injector and the minimum inner diameter Di1 of the nozzle 15 is called the capacity factor. c) Between 0.5 and 0.8. Capacity factor c defines the theoretical maximum suction capacity generated by the Venturi effect. Capacity factor. This wide range of values ​​for c allows for adjustment of the amount of air in the air / gas premixture in nozzle 15 and optimization of several combustion parameters, such as ignition rate, flame front positioning relative to nozzle 15 or nozzle outlet, and nitrogen oxide emissions.

[0066] Additionally, the injection outlet 7 is located at a relative distance λ from the inlet section 16 of the nozzle 15 in the longitudinal direction X. The relative distance λ is configured such that the ratio (λ / Di1) between the relative distance λ and the minimum inner diameter Di1 of the nozzle 15 (called the ejection factor) e) Between -0.2 and 0.4. The relative distance λ is considered positive when the injection outlet 7 is upstream of the inlet section 16 of the nozzle 15, and negative when the injection outlet is downstream of the inlet section 16 of the nozzle 15. The relative distance λ can be between -4 mm and 8 mm, for example, 4.5 mm. Ejector factor This range of values ​​for e optimizes suction capability while limiting the risk of backfire. (Ignition factor) This range of values ​​for e helps to create congestion in the premixed circuit 5 upstream of the nozzle inlet 15, forming an acceleration zone for the flow portion F3 upstream of the mixing point with the fuel ejected through the injection outlet 7. This promotes continuous acceleration of the flow from this acceleration zone to the outlet region 52 of the premixed circuit 5, which limits the risk of backfire in the premixed circuit 5, which is particularly important when hydrogen is used as fuel.

[0067] Control component 4 is configured (particularly depending on the type of gaseous fuel used) to control at least one operating parameter of the in-pipe burner 3. The associated control method is configured to control said operating parameter of the in-pipe burner 3 such that the velocity of the gas flow portion F3 at the injection outlet 7 is greater than the flame velocity of the gaseous fuel used. This prevents backfire in the premixed circuit 5, regardless of the type of fuel used. This is particularly advantageous because it allows the in-pipe burner 3 to operate with different types of fuels (including hydrogen or natural gas, or a mixture of both) without introducing any structural modifications based on the type of fuel used. Since it is not necessary to modify the operation of the in-pipe burner 3 depending on the type of fuel used, the operation of the heating system 1 is simplified, and its utilization is improved.

[0068] Advantageously, the control assembly 4 includes a component for controlling the pressure 17 of the gaseous fuel in the intake manifold 8, which may include, for example, a pump or piston. The pressure setpoint can be adjusted by the operator depending on the type of gaseous fuel used, and the control assembly 4 maintains the pressure level in the intake manifold 8 at the setpoint level.

[0069] Advantageously, the control component 4 includes a setpoint generator 18 configured to generate a gaseous fuel pressure setpoint in the intake manifold 8 depending on the type of fuel used in real time. This improves the mobility of the heating system 1, allowing it to adapt to its operation without requiring any changes to operating parameters by the operator. Specifically, this enables a seamless switch from one type of fuel to another without interrupting the operation of the heating system 1.

[0070] Advantageously, the intake manifold 8 is supplied using a supply circuit comprising several parallel fuel sources leading to a mixer, the mixer outlet of which is in fluid communication with the intake manifold 8. A first source supplies a first fuel, a second source supplies a second fuel, and depending on the type of fuel to be used, a continuous switch from one fuel to another can be made by gradually replacing one of the first fuel type and the second fuel type. A setpoint generator 18 continuously adjusts the pressure setpoint in the intake manifold 8 according to the fuel mixture used.

[0071] Advantageously, control component 4 includes a pressure estimator 19 configured to estimate the pressure of the gaseous fuel in the intake manifold 8, thereby enabling the pressure in the intake manifold 8 to be regulated based on feedback from the pressure estimator 19. Closed-loop control improves system reliability by ensuring that the pressure in the intake manifold 8 remains at the setpoint level even in the presence of disturbances, such as deteriorating operation of the pressure control component 17.

[0072] Advantageously, the setpoint generator 18 is also configured to generate a setpoint based on parameters of the main airflow F1 flowing through the duct 2. For example, the pressure setpoint in the intake manifold 8 can be adjusted based on the flow velocity of the main airflow F1.

[0073] Advantageously, the control component 4 includes a processing unit comprising a processor and a memory containing code data that, when processed by the processor, enables methods for controlling the heating system 1.

[0074] Control method 1 can be represented by steps, which include the following steps:

[0075] S1: Determine the setpoint value for the fuel injection parameters used, which are configured to ensure that the flow velocity of the flow section F3 at the injection outlet 7 is greater than the flame velocity of the fuel used.

[0076] S2: Add the previously determined setpoint to the control unit to change the injection parameters of the fuel used and cause a change in the flow velocity of the flow section F3 at the injection outlet 7.

[0077] Advantageously, the method includes step S0 for acquiring burner operating status data and fuel status data, and step S1' during which a setpoint is determined based on the data acquired during step S0. During step S0, the measured status parameters of the burner 3 include, for example, the flow velocity of the main airflow F1.

Claims

1. A control method for controlling a heating system (1) for heating an airflow passing through a flow pipe (2), the system comprising: - An in-pipe burner (3), the in-pipe burner comprising at least one fuel intake manifold (8), the at least one fuel intake manifold being provided with at least one injector (6), the at least one injector being arranged to inject fuel into a premixing circuit (5), the premixing circuit being configured such that the fuel can be mixed with a portion of the gas, the injector (6) appearing at an injection outlet (7) in the premixing circuit (5), the premixing circuit (5) being configured such that a portion of the gas flow (F3) can be drawn from the pipe (2) and guided through the premixing circuit (5) to an outlet section (52), the premixing circuit (5) being shaped such that it has a direct flow section (Ai), the cross-sectional area of ​​the direct flow section changing from upstream to downstream along the flow of the portion of the flow (F3) in the premixing circuit (5), - Control component (4), the control component is arranged to supply fuel to the burner and is configured to allow control of at least one fuel injection parameter. The control method and the variation of the cross-sectional flow area (Ai) of the premixed circuit are configured such that the flow velocity of the airflow portion (F3) at the injection outlet (7) in the premixed circuit (5) is greater than the flame velocity of the fuel in the outlet region (52).

2. The control method according to claim 1, wherein the control component (4) is capable of controlling the supply pressure of the intake manifold (8).

3. The control method according to any one of the preceding claims, wherein the fuel comprises gaseous hydrogen or gaseous hydrocarbon or a mixture of both, the gaseous hydrocarbon being, for example, natural gas, and wherein the control component (4) is adapted to control at least one fuel injection parameter according to the fuel combustion rate in the outlet region (52).

4. The control method according to claim 3, wherein the control component (4) is capable of controlling the composition of the mixture of hydrogen and hydrocarbon gas.

5. A heating system (1) configured to use the method according to any one of claims 1 to 4 for heating an airflow passing through a flow pipe (2), the heating system comprising: - An in-pipe burner (3), the in-pipe burner comprising a fuel intake manifold (8) and at least one flame stabilizer (9), the fuel intake manifold being provided with at least one injector (6) extending in a longitudinal direction, the at least one flame stabilizer being arranged opposite to the injector (6), the stabilizer (9) comprising a wall defining a duct (11) extending from upstream to downstream in the longitudinal direction and forming a premixing circuit (5) together with the intake manifold (8) and the injector (6), the premixing circuit being configured to mix fuel and gas, the premixing circuit (5) comprising at least one intake opening (51), an upstream portion and a downstream portion, the at least one intake opening being The flow is arranged such that a portion of the flow (F3) can be drawn from the pipe (2) and guided through the premixing circuit (5), the upstream portion having a cross-section externally defined by the wall (11) of the stabilizer (9) and internally defined by the injector (6), the downstream portion having a cross-section externally defined by the wall (11) of the stabilizer (9), the injector (6) being introduced into the premixing circuit (5) at the injection outlet (7), the premixing circuit (5) being configured such that it has a flow cross-sectional area (Ai), the surface of which varies along the flow in the premixing circuit (5) as the portion of the flow circulates from upstream to downstream. - Control component (4), which is arranged to supply fuel to the burner and is configured to allow control of at least one fuel injection parameter.

6. A pipe burner (3) for use in the heating system (1) according to claim 5, the pipe burner (3) comprising: - A fuel intake manifold (8), wherein the fuel intake manifold is provided with at least one injector (6) extending in the longitudinal direction, and - At least one flame stabilizer (9) is arranged opposite to the injector (6), the stabilizer (9) includes a wall defining a duct (11) extending from upstream to downstream in the longitudinal direction and forms a premixing circuit (5) together with the intake manifold (8) and the injector (6), the premixing circuit being configured to mix fuel and gas, the injector (6) being introduced into the premixing circuit (5) at the injection outlet (7). The premixing circuit (5) includes at least one air inlet (51), an upstream portion, and a downstream portion. The at least one air inlet is designed such that a portion of the flow (F3) can be drawn from the pipe (2) and directed into the premixing circuit (5). The upstream portion has a cross-section externally defined by the stabilizer wall (9) and internally defined by the injector (6). The downstream portion has a cross-section externally defined by the nozzle (15) of the stabilizer (9). The premixed circuit (5) is configured to have a flow cross-sectional area (Ai), the area of ​​which varies along the circulation of the portion of the flow in the premixed circuit (5) as the portion of the flow circulates from upstream to downstream. The flow cross-sectional area has a first surface area (A1) at the injection outlet (7) and a second surface area (A2) in the downstream portion, the first surface area (A1) being between 40% and 70% of the second surface area (A2).

7. The burner according to claim 6, wherein the nozzle (15) has an outer diameter (De) and an inner diameter (Di), the outer diameter and the inner diameter being configured such that the ratio of the inner diameter to the outer diameter (Di / De) is between 0.55 and 0.85, and wherein the nozzle (15) is made of a material comprising fire-resistant steel.

8. The burner according to claim 7, wherein the nozzle (15) has a total length (Lt) and includes an upstream portion (15a) and a downstream portion (15b) shaped to facilitate expansion of the flow through the nozzle, the downstream portion (15b) having a length (L) configured such that the ratio (L / Lt) between the length (L) and the total length (Lt) of the nozzle (15) is between 0.70 and 0.85, and such that the ratio (L / De) between the length (L) and the outer diameter (De) of the nozzle (15) is between 0.65 and 0.

75.

9. The burner according to claim 6, wherein the injector (6) has a generally cylindrical geometry with an injector outer diameter (δe), and wherein the nozzle (15) has a minimum inner diameter (Di1), the injector outer diameter and the minimum inner diameter being configured such that the capacity factor corresponding to the ratio (δe / Di1) between the injector outer diameter (δe) and the minimum inner diameter (Di1) of the nozzle is ( c) Between 0.5 and 0.

8.

10. The burner according to claim 6, wherein the injection outlet (7) is located at a relative position (λ) in the longitudinal direction (X) of the inlet section (16) of the nozzle (15), and wherein the nozzle (15) has a minimum inner diameter (Di1), the relative position and the minimum inner diameter being configured such that the ejection factor corresponding to the ratio (λ / Di1) between the relative position (λ) and the minimum inner diameter (Di1) of the nozzle (15) is ( e) Between -0.2 and 0.4.

Images