DEVICE FOR PRODUCING A HYDROGEN-GASEOUS HYDROCARBON MIXTURE

Abstract

Device for producing a hydrogen-hydrocarbon gas mixture. The present invention relates to a device (1) for producing a mixture of hydrocarbon gas and hydrogen arranged to be disposed upstream of at least one burner of a gas boiler, notable in that it comprises at least: - a Venturi tube (2), - a first inlet orifice (3) for hydrocarbon gas, - an outlet orifice (4) for the mixture of hydrocarbon gas and hydrogen produced by said device (1), - a second inlet orifice (5) for hydrogen, - a hydrogen safety and regulation group (6) connected to said second inlet orifice (5) and to the neck of said Venturi tube (2), and - a pressure switch (7) measuring the hydrogen pressure entering through said second inlet orifice (5), - a differential pressure switch (8) between the inlet and the neck of said Venturi tube (2), and - an electronic control unit (9) for regulating Hydrogen supply. Fig 2

Description

Description Title of the invention: DEVICE FOR PRODUCING A HYDROGEN MIXTURE —- GASED HYDROCARBON Technical field of the invention

[0001] — The present invention relates to the general field of gas burners in particular For boilers, it specifically targets a device for producing a mixture variable of hydrogen and gaseous hydrocarbon arranged to be disposed upstream of less a gas burner for a gas boiler, but also a process of putting implementation of said device on a gas burner. State of the art

[0002] In the field of gas burners for boilers in particular, it is known to use a gaseous hydrocarbon, which is mostly composed of methane. Hydro- Gaseous hydrocarbons offer numerous economic and even environmental advantages. since gaseous hydrocarbons have levels of pollutant emissions that significantly lower compared to other fossil fuels such as coal or oil.

[0003] — However, for obvious ecological reasons, it is now essential to reduce all pollutant emissions, including carbon dioxide emissions carbon is responsible for nearly 65% ​​of the anthropogenic greenhouse effect.

[0004] To reduce emissions of pollutants generated by gaseous hydrocarbons, one The solutions consist of mixing these with a quantity of hydrogen re- presenting a ratio of around 20% or even more. The advantage of mixing Hydrogen in a gaseous hydrocarbon has multiple functions. First, it allows, among other things, an obvious way to reduce CO2 emissions and fossil gas consumption. This last aspect also has geopolitical significance by limiting dependence on countries vis-à-vis gaseous hydrocarbon producing countries. Furthermore, the mixture Hydrogen – a gaseous hydrocarbon – also has economic value, because hydrogen is a way to store electricity produced from renewable energy sources, and can be produced at times when electricity production from sources Renewable energy production exceeds consumption. Finally, combustion hydrogen produces a significant amount of water vapor, increasing the temperature dew from the flue gases and promotes condensation in the heat exchanger of the associated boiler.

[0005] — Thus, devices known to produce a mixture of gaseous hydrocarbon and The hydrogen concentrations are such that the mixing is ensured upstream of the distribution network. of gaseous hydrocarbon using a mixer. This type of mixer is classified This type of mixer is composed of proportional valves combined with a flow meter and an electronic component that ensures the correct ratio of gaseous hydrocarbon to hydrogen. The major drawback of this type of mixer is the complexity of maintaining proportional dosing regardless of the gaseous hydrocarbon flow rate, which limits its use to research applications and network infrastructure. Furthermore, with this type of known mixer, the mixture of hydrogen and gaseous hydrocarbon is obtained for higher hydrogen and gaseous hydrocarbon pressures than those used for feeding burners operating solely on gaseous hydrocarbon, which implies installing additional pressure-reducing stages to lower the supply pressure of said burners. Finally, since the mixing is carried out upstream of the gaseous hydrocarbon distribution circuit, this type of mixer is not suitable for producing a mixture of gaseous hydrocarbon and "green" hydrogen, the latter being produced from renewable energy sources and, preferably, locally. In the field of gas burners, air / gaseous hydrocarbon mixers are already known, coupled with a pneumatic gas regulator that allows for a gas mixture of 7 to 10% gas to 90 to 93% air, regardless of the air flow rate. This type of mixer is based on the Venturi effect, named after the Italian physicist Giovanni Battista Venturi. Venturi describes a phenomenon in fluid dynamics whereby a flowing fluid experiences a pressure drop where the flow cross-section narrows. Thus, this type of mixer consists of a variable-flow air duct connected to a Venturi tube with a progressively narrowing cross-section, creating a pressure drop at the throat (the narrowest point of the Venturi tube) proportional to the air flow rate. In this type of mixer, the gaseous hydrocarbon is injected at the throat to mix with the air.Furthermore, to guarantee a constant air / gaseous hydrocarbon mixing ratio regardless of the air flow rate, the gaseous hydrocarbon pressure upstream of the throat is regulated to a pressure practically equal to the air pressure upstream of the Venturi tube. The advantage of this technology is to ensure precise and constant metering, and the mixing flow rate is controlled accordingly. Air / gaseous hydrocarbon mixing can be adapted over a relatively wide range. However, this type of mixer has several drawbacks. Specifically, it is not suitable for producing a mixture of gaseous hydrocarbon and hydrogen, and it can negatively impact air handling systems with significant pressure drop. Summary of the invention The aim of the present invention is therefore to provide a device for producing a mixture of gaseous hydrocarbon and hydrogen arranged to be placed upstream of at least one burner of a gas boiler and advantageously near a green hydrogen production, said device being compact and quick to set up and allowing to mix at a variable rate of hydrogen in gaseous hydrocarbon depending on the flow rate of the latter without adverse effect on the burner, whatever its technology, and as soon as said burner is in operation, said device being able to be easily adjusted by a person who has had training on burner adjustments. According to the invention, a device is therefore proposed for producing a mixture of gaseous hydrocarbon and hydrogen arranged to be placed upstream of at least one burner of a gas boiler, remarkable in that it comprises at least: - a Venturi tube, - a first inlet orifice located at the entrance of said Venturi tube and arranged to be connected to a supply pipe, - an outlet orifice disposed at the inlet of said Venturi tube and arranged to be connected to a discharge piping for the mixture of gaseous hydrocarbon and hydrogen produced by said device, - a second inlet port arranged to be connected to a hydrogen supply pipe, - a hydrogen safety and regulation group connected by its inlet to said second inlet orifice and by its outlet to the neck of said Venturi tube and allowing the hydrogen pressure at the neck of said Venturi tube to be regulated proportionally to the gaseous hydrocarbon supply pressure at the first inlet orifice, - a pressure switch measuring the hydrogen pressure entering said device through its second inlet port, - a differential pressure switch detecting a pressure difference between the inlet and the neck of said Venturi tube, and - an electronic control unit allowing the hydrogen supply of the device to be regulated using said hydrogen safety and regulation group according to the pressure measurements of the pressure switch and the differential pressure switch in a manual mode or in an automatic mode. The Venturi tube is advantageously shaped to generate a maximum pressure difference between its inlet and throat, while limiting the pressure loss between the first inlet orifice and the outlet orifice of the device. According to an advantageous embodiment, the hydrogen safety and control group comprises, depending on the direction of hydrogen flow, at least: - a shut-off solenoid valve connected to the second inlet port of the device, allowing or preventing the supply of hydrogen to the Venturi tube, - a pressure regulator associated with a servo-regulator and connected to the outlet of the shut-off solenoid valve, and allowing the hydrogen pressure at the neck of said Venturi tube proportionally to the gaseous hydrocarbon supply pressure at the first inlet orifice, and - a flow limiter connected between the outlet of the pressure regulator and the neck of the Venturi tube allowing the flow of hydrogen to be limited at the neck of said Venturi tube. Preferably, the shut-off solenoid valve is electrically powered and controlled by the electronic control box so that in automatic mode, the shut-off solenoid valve opens and allows the hydrogen supply only when the hydrogen pressure measured by the pressure switch is greater than or equal to a first threshold value, and when the pressure difference between the inlet and the throat of the Venturi tube measured by the differential pressure switch is greater than or equal to a second threshold value, said first and second threshold values ​​being predetermined according to the applications of the device and respectively set on the pressure switch and the differential pressure switch. The pressure regulator is advantageously of the normally closed type and includes a movable valve between a "closed" position in which it rests on a seat, according to a partial seal, so as to limit the passage of hydrogen through said seat, and an "open" position in which it is no longer resting on said seat so as to allow a greater circulation of hydrogen upstream of the flow limiter, said valve being connected by a rod to a deformable diaphragm. According to a more advantageous embodiment, the servo-regulator comprises a movable needle between an "open" position in which it allows the circulation of hydrogen taken upstream of the pressure regulator to the diaphragm of said pressure regulator on the side opposite the valve, and a "closed" position in which it rests against a seat, with a partial seal, so as to limit the passage of said hydrogen and to allow the movement of the diaphragm of said pressure regulator to return the valve to its closed position; a movable diaphragm for moving said needle from its open position to its closed position, and vice versa; pressure means for maintaining said needle against the diaphragm; and return means for returning said diaphragm to a position such that it maintains the needle in its open position, said diaphragm being subjected, on the one hand,to the pressure of the gaseous hydrocarbon sampled at the first inlet orifice, which determines a setpoint pressure, and, on the other hand, to the pressure of the hydrogen sampled downstream of the pressure regulator. According to an even more advantageous embodiment, the return means of the servo-regulator are associated with an adjustment screw allowing the force of said return means to be adjusted. The flow limiter is preferably of the screw type and includes an adjustment screw which, when tightened or loosened, allows the flow to be reduced or increased respectively. flow rate of hydrogen injected at the level of the neck of the Venturi tube and to modulate the ratio of hydrogen in the mixture produced by the device. The invention also relates to a method of implementing a device according to the invention upstream of at least one burner of a gas boiler, notable in that it comprises at least the following steps: a) the device being switched off, the latter only delivering gaseous hydrocarbon, its hydrogen safety and regulation group not being electrically powered, b) positioning the burner at an operating point corresponding to its maximum power, then measuring the oxygen level in the flue gases exiting the gas boiler, c) switching the hydrogen safety and regulation group to manual mode, then measuring the oxygen level present in the said fumes, d) adjusting the injected hydrogen flow rate using the hydrogen safety and regulation group in relation to data from a nomogram representing the evolution of the oxygen level in the flue gases exiting the gas boiler as a function of the injected hydrogen level, e) switching off the device, the latter delivering only gaseous hydrocarbon, its hydrogen safety and regulation group not being electrically powered, f) positioning the burner at an operating point corresponding to its minimum power, then measuring the oxygen level in the flue gases exiting the gas boiler, (g) switching the hydrogen safety and regulation group to manual mode, then measuring the oxygen level present in said fumes, h) adjusting the flow rate of injected hydrogen using the hydrogen safety and regulation group in relation to the data of said nomogram, i) automatic switching of the hydrogen safety and regulation group. Advantageously, the process includes, before step a), a step of creating the nomogram showing the evolution of the oxygen level in the flue gases as a function of the hydrogen level present in the flue gases exiting the gas boiler, this creation step being based on the following input data: - the excess air applied to said burner, - the range of variation of the hydrogen concentration, - the nature of the gaseous hydrocarbon and the nature of the hydrogen. Brief description of the figures Other advantages and features will be better explained in the description that follows. to follow an embodiment of the invention with reference to the attached figures in which: [Fig.1] is a schematic view of a device for producing a variable mixture of gaseous hydrocarbon and hydrogen according to the invention, [Fig.2] is a perspective view of a device from [Fig.1], [Fig.3] is another perspective view of the device of [Fig.2] shown partially, [Fig.4] is a view from below of the device in [Fig.2], [Fig.5] is a partial schematic vertical cross-sectional view of the device of [Fig.2] along the VV' axis of [Fig.2], [Fig.6] is a schematic view of an example of a nomogram allowing the implementation of the device of [Fig.2] on a burner of a gas boiler, said nomogram showing the evolution of oxygen in the fumes as a function of the hydrogen level in the gas. Description of the implementation methods With reference to [Fig. 1] and in accordance with the invention, the device 1 for producing a variable mixture of gaseous hydrocarbon and hydrogen arranged to be disposed upstream of at least one gas boiler burner comprises at least: - a Venturi tube 2, - a first inlet orifice 3 disposed at the inlet of said Venturi tube 2 and arranged to be connected to a gaseous hydrocarbon supply piping, - an outlet 4 disposed at the inlet of said Venturi tube 2 and arranged to be connected to a discharge piping for the mixture of gaseous hydrocarbon and hydrogen produced by said device 1, - a second inlet port 5 arranged to be connected to a hydrogen supply pipe, - a hydrogen safety and regulation group 6 connected by its inlet to said second inlet orifice 5 and by its outlet to the neck of said Venturi tube 2, - a pressure switch 7 measuring the hydrogen pressure entering said device 1 through its second inlet orifice 5, - a differential pressure switch 8 detecting a pressure difference between the inlet and the neck of said Venturi tube 2, and - an electronic control unit 9 allowing the hydrogen supply to be regulated by means of said hydrogen safety and regulation group 6 according to the pressure measurements of the pressure switch 7 and the differential pressure switch 8 in a manual mode or in an automatic mode. Here, "input" or "output" refers to elements or parts of elements of the device 1 located on the inlet or outlet side of a fluid depending on its direction of flow. Furthermore, here we refer to a "pressure switch" as a device used to relay information on pressure variations of a fluid within an element, said pressure switch being of any type such as, for example, mechanical, electrical, electronic or pneumatic. The Venturi tube 2 is configured to generate a maximum pressure difference of between 5 and 10 mbar between the inlet and the throat of said Venturi tube 2, while limiting the pressure drop between the first inlet port 3 and the outlet port 4 of the device 1 to between 1 and 4 mbar. This particular configuration is necessary to allow the system to admit a significant amount of hydrogen at the throat of the Venturi tube 2, while limiting the pressure drop of the gas mixture produced upstream of a gas boiler burner, i.e., at the outlet port 4 of the device 1, so as to always maintain a gas mixture under conditions that guarantee optimal operation of the associated burner. Another advantage of this particular configuration of the Venturi tube 2 is that it allows operation with a low-pressure hydrogen supply (which must be slightly higher than the gaseous hydrocarbon supply pressure, on the order of 5 to 10 mbar). This particular configuration therefore helps to reduce the risk of gas leaks inside the premises housing the device 1. Finally, this configuration of the Venturi tube 2 with a strong depression between its inlet and its neck allows, on the one hand, an adaptation to variations in the pressure of gaseous hydrocarbon without disturbing the rate of hydrogen injected at the level of said neck and, on the other hand, to guarantee a safe admission of hydrogen. The first inlet port 3 and the outlet port 4 of the device 1 are advantageously materialized by male fittings with a gas thread fixed on the Venturi tube 2. Furthermore, the second inlet port 5 is advantageously materialized by a flange equipped with a female fitting with a gas thread. According to an advantageous embodiment, with reference to Figures 2 to 5, the hydrogen safety and control group 6 comprises, depending on the direction of hydrogen flow, at least: - a shut-off solenoid valve 10 connected to the second inlet port 5 of device 1, - a pressure regulator 11 associated with a servo-regulator 12 and connected to the outlet of the shut-off solenoid valve 10, and - a flow limiter 13 connected between the outlet of the pressure regulator 11 and the neck of the Venturi tube 2. The shut-off solenoid valve 10 allows the supply of hydrogen to the Venturi tube 2 to be authorized or not. The shut-off solenoid valve 10 is electrically powered and controlled by the electronic control box 9 in automatic or manual mode, the switch from one mode to the other being ensured by a switch on said electronic control box 9.Thus, in automatic mode, the shut-off solenoid valve 10 opens and allows the supply of hydrogen, and therefore the passage of the latter, only when the hydrogen pressure measured by the pressure switch 7 is greater than or equal to a first threshold value, and when the pressure difference between the inlet and the neck of the Venturi tube 2 measured by the differential pressure switch 8 is greater than or equal to a second threshold value, said first and second threshold values ​​being predetermined according to the applications of the device 1 and respectively set on the pressure switch 7 and the differential pressure switch 8. The control of the shut-off solenoid valve 10 by the electronic control unit 9, based on the values ​​measured by the pressure switch 7 and the differential pressure switch 8, is important because it ensures the safety of device 1 by only admitting hydrogen into said device 1 when hydrogen is available at a sufficient pressure and when consumption of the produced hydrogen-hydrogen gas mixture is actual (consumption detected by a pressure difference between the inlet and the throat of the Venturi tube 2), for example, when the associated burner is operating. Furthermore, when device 1 is switched off, the shut-off solenoid valve 10 is closed and no hydrogen is injected at the throat of the Venturi tube 2. Indeed, the large difference in density between gaseous hydrocarbons and hydrogen leads to gas separation during periods when the produced gas mixture is not consumed. This phenomenon can result in a significant accumulation of hydrogen in the pipe upstream of the associated burner, and create dangerous ignition conditions for the burner. Furthermore, assuming the use of locally produced hydrogen from non-dispatchable renewable energy sources, the quantity of hydrogen available is not always sufficient, which implies preventing the introduction of hydrogen from the supply line in the event of too low hydrogen pressure, in order to avoid the reflux of gaseous hydrocarbon into the hydrogen line. The hydrogen safety and regulation group 6 also includes a pressure regulator 11 associated with a servo-regulator 12 allowing the regulation of hydrogen pressure upstream of the flow regulator 13. With reference to [Fig. 5], the pressure regulator 11 conventionally comprises a movable valve 14 between a "closed" position in which the valve 14 bears against a seat 15, in a partially sealed manner, so as to limit the The passage of hydrogen through said seat 15 allows the desired hydrogen pressure to be obtained upstream of the flow restrictor 13 for a low flow rate of gaseous hydrocarbon, and an "open" position in which the valve 14 is no longer in contact with said seat 15 so as to have a hydrogen flow rate and pressure upstream of the flow restrictor 13 adapted to a higher flow rate of gaseous hydrocarbon. Said valve 14 is connected by a stem 16 to a deformable diaphragm 17. Furthermore, the pressure regulator 11 is of the normally closed type and includes return means 18 for returning said valve 14 to its closed position. Here, "partial sealing" refers to a seal that is obtained, in a classic way, by a metal-to-metal contact that is not perfect in principle, and therefore cannot be absolute, this type of sealing allowing a small flow of gas to pass through. With reference to [Fig. 5], the servo-regulator 12 comprises a movable needle 19 between an “open” position, in which it allows the flow of hydrogen drawn upstream of the pressure regulator 11 to the diaphragm 17 of said pressure regulator 11 on the side opposite the valve 14, and a “closed” position, in which it bears against a seat 20, providing a partial seal, so as to limit the passage of said hydrogen and to allow the diaphragm 17 of said pressure regulator 11 to move the valve 14 back to its closed position. Said servo-regulator 12 further comprises a movable diaphragm 21 for moving said needle 19 from its open position to its closed position, and vice versa, and pressure means 22 for maintaining said needle 19 in contact with the diaphragm 21.The membrane 21 is subjected, on the one hand, to the pressure of the gaseous hydrocarbon taken from the first inlet orifice 3 of the device 1 determining a set pressure and, on the other hand, to the pressure of the hydrogen taken from downstream of the pressure regulator 11. Furthermore, the servo-regulator 12 includes return means 23 tending to return the membrane 20 to a position such that it maintains the needle in its open position. With reference to [Fig. 5], the pressure regulator 11 - servo-regulator 12 assembly operates as follows. Thus, if the hydrogen pressure downstream of the pressure regulator 11 is greater than the setpoint pressure, then the diaphragm 21 will move the needle 19 from its open position to its closed position, and the hydrogen drawn upstream of the pressure regulator 11 will flow at a reduced rate to the diaphragm 17 of the pressure regulator 11 on the side opposite the valve 14. This has the effect of moving the valve 14 of the pressure regulator 11 from its open position to its closed position, reducing the hydrogen pressure downstream of the pressure regulator 11 until equilibrium is reached between the hydrogen pressure downstream of the pressure regulator 11 and the setpoint pressure. Conversely, if the hydrogen pressure downstream of the pressure regulator 11 is less than the setpoint pressure, setpoint, then the membrane 21 will move the needle 19 from its closed position to its open position and the hydrogen taken upstream of the pressure regulator 11 will flow significantly to the membrane 17 of the pressure regulator 11 on the opposite side of the valve 14, which has the effect of moving the valve 14 of said pressure regulator 11 from its closed position to its open position, increasing the hydrogen pressure downstream of the pressure regulator 11, until equilibrium is reached between the hydrogen pressure downstream of the pressure regulator 11 and the setpoint pressure. The return means 23 are further associated with an adjustment screw 24 which allows the effort of said return means 23 to be adjusted, in order to finely adjust the settings and to introduce a variation of the hydrogen rate between the minimum and maximum power of the gas burner. The hydrogen safety and regulation group 6 also includes a flow limiter 13 for limiting the flow of hydrogen entering the Venturi tube 2. With reference to [Fig.5], said flow limiter 13 is of the screw type and includes an adjusting screw 25, the tightening or loosening of which respectively reduces or increases the flow of hydrogen injected at the neck of the Venturi tube 2 and, consequently, modulates the hydrogen ratio in the mixture produced by the device 1 according to the invention. It is clear that the device 1, configured as such, allows the hydrogen pressure to be regulated proportionally to the gaseous hydrocarbon supply pressure, that is, at the first inlet orifice 3 of said device 1. This automatically compensates for pressure variations in the gaseous hydrocarbon supply network. Furthermore, even if the hydrogen supply pressure needs to be slightly higher than the gaseous hydrocarbon supply pressure, the pressure drop at the point where the hydrogen and gaseous hydrocarbon mix, located at the throat of the Venturi tube 2, is sufficient to regulate the injected hydrogen flow rate. Furthermore, it is clear that maintaining the hydrogen level in device 1 according to the invention is, regardless of the gaseous hydrocarbon flow rate, completely autonomous and independent of the burner on which it is implemented. Moreover, the hydrogen admission management is integrated into said device 1 and is electromechanical in nature, making the management of said device 1 accessible to any heating engineer and / or boiler room operator equipped with standard tools. However, in order to ensure the correct adjustment and operation of device 1, the invention also relates to a method of implementing said device on a gas boiler burner. The said process consists of deducing the hydrogen content present in the mixture of hydrogen and gaseous hydrocarbon produced by device 1 according to the invention as a function of the oxygen content present in the flue gases exiting the gas boiler. This method is intended to be carried out by heating engineers experienced in adjusting burners using a combustion analyzer that measures the oxygen level in the flue gases and a nomogram representing the evolution of the oxygen level in the flue gases as a function of the hydrogen level present in the flue gases (See [Fig. 6]). To achieve this, the process of implementing said device on a gas boiler burner includes at least the following steps: a) switching off device 1, the latter device 1 only delivering gaseous hydrocarbon, its hydrogen safety and regulation group 6 not being electrically powered, b) positioning the burner at an operating point corresponding to its maximum power, then measuring the oxygen level in the flue gases exiting the gas boiler, c) switching the hydrogen safety and regulation group 6 to manual mode, then measuring the oxygen level present in said fumes, d) adjustment of the injected hydrogen flow rate using the hydrogen safety and regulation group 6 in relation to the data from a nomogram representing the evolution of the oxygen level in the flue gases exiting the gas boiler as a function of the injected hydrogen level, €) switching off device 1, the latter device 1 only delivering gaseous hydrocarbon, its hydrogen safety and regulation group 6 not being electrically powered, f) positioning the burner at an operating point corresponding to its minimum power, then measuring the oxygen level in the flue gases exiting the gas boiler, (g) switching the hydrogen safety and regulation group 6 to manual mode, then measuring the oxygen level present in said fumes, h) adjusting the injected hydrogen flow rate using the hydrogen safety and regulation group 6 in relation to the data in said nomogram, i) automatic switching of the hydrogen safety and regulation group 6. Before step a), the process advantageously includes a step of creating the nomogram showing the evolution of the oxygen level in the fumes exiting the gas boiler as a function of the level of hydrogen injected. This creation step relies on the following input data: - the excess air applied to said burner, - the range of variation of the hydrogen concentration (for example from 2 to 50%), - the nature of the gaseous hydrocarbon and the nature of the hydrogen. Once these input data are known, the theoretical stoichiometric air flow rate in the gaseous hydrocarbon is deduced in the absence of hydrogen injection. Next, the flow rate of the admitted hydrogen-gaseous hydrocarbon mixture is calculated as a function of the hydrogen content, since the density of this mixture varies with the hydrogen concentration. With a constant air flow rate injected by a fan at the burner, the excess air value can then be determined as a function of the hydrogen concentration in the mixture, from which the oxygen concentration in the flue gases exiting the gas boiler can be deduced. Thus, in the end, for a given type of gaseous hydrocarbon, we obtain a nomogram representing the evolution of the oxygen content in the flue gases exiting the gas boiler as a function of the hydrogen content present in the mixture injected into the burner for different values ​​of the air flow rate injected at said burner, said nomogram having on the x-axis a scale giving the hydrogen content in the mixture produced by device 1 between 0 and 60%, and on the y-axis a scale giving the oxygen content present in the flue gases exiting the gas boiler between 3 and 10%. On the example of a nomogram shown in [Fig.Figure 6] shows the evolution of the oxygen level in the flue gases exiting the gas boiler as a function of the hydrogen level present in the mixture injected into the burner for different values ​​of the oxygen level in the flue gases exiting the gas boiler in the absence of hydrogen present in the mixture, these values ​​of said oxygen level going from low to high from 3.5 to 6% which corresponds to classic gas boiler setting values. It is clear that with the specific configuration of device 1 according to the invention, the hydrogen content in the mixture produced by said device 1 will be between 0 and 60%. This level is particularly suitable for a gas burner, because above 60% the other equipment associated with said gas burner may no longer operate safely. Device 1 for producing a variable mixture of gaseous hydrocarbon and hydrogen according to the invention finds a particular application for supplying at least one gas burner of a boiler, but it is understood that said device 1 can be adapted for use on other equipment such as, for example, a mixing station for a chemistry laboratory or an industrial welding process. Finally, it goes without saying that the examples of device 1 conforming to the invention which have just been described are only particular illustrations, in no way limiting of the invention.

Claims

Claims

1. Device (1) for producing a mixture of gaseous hydrocarbon and of hydrogen arranged to be placed upstream of at least one burner gas, characterized in that it comprises at least: - a Venturi tube (2), - a first inlet orifice (3) arranged at the inlet of said tube of Venturi (2) and arranged to be connected to a supply pipe, - an outlet orifice (4) arranged at the inlet of said Venturi tube (2) and arranged to be connected to a mixture delivery pipe of gaseous hydrocarbon and hydrogen produced by said device (1), - a second inlet port (5) arranged to be connected to a hydrogen supply piping, - a hydrogen safety and regulation group (6) connected by its inlet to said second inlet orifice (5) and by its outlet at the neck of said Venturi tube (2) and allowing the hydrogen pressure to be regulated at neck of said Venturi tube (2) proportionally to the pressure gaseous hydrocarbon supply at the first orifice entrance (3), - a pressure switch (7) measuring the pressure of hydrogen entering said device (1) through its second inlet orifice (5), - a differential pressure switch (8) detecting a pressure difference between the inlet and neck of said Venturi tube (2), and - an electronic control box (9) for regulating the hydrogen supply of the device (1) using said group of safety and regulation of hydrogen (6) based on measurements of pressure of the pressure switch (7) and the differential pressure switch (8) according to a mode manual or automatic mode.

2. Device (1) according to claim 1 characterized in that the tube of Venturi (2) is shaped to generate a pressure difference maximum between 5 and 10 mbar between its inlet and neck, while limiting the pressure loss between the first inlet port (3) and the port output (4) of the device (1) between 1 and 4 mbar.

3. Device (1) according to any one of claims 1 or 2 ca- characterized in that the security and regulation group of hydrogen (6) comprises according to the direction of circulation of hydrogen to the LESS ! - a cut-off solenoid valve (10) connected to the second port input (5) of the device (1) and allowing to authorize or not the hydrogen supply to the Venturi tube (2), - a pressure regulator {11) associated with a servo-regulator (12) and connected to the output of the cut-off solenoid valve (10), and allowing regulate the hydrogen pressure at the neck of said Venturi tube (2) propor- tionally to the gaseous hydrocarbon supply pressure at level of the first inlet port (3), and - a flow limiter (13) connected between the outlet of the regulator pressure (11) and the neck of the Venturi tube (2) allowing to limit the hydrogen flow at the neck of said Venturi tube (2).

4. Device (1) according to claim 3 characterized in that the cut-off solenoid valve (10) is electrically powered and controlled by the electronic control box (9) so that in au- automatic, the cut-off solenoid valve (10) opens and authorizes hydrogen supply, only when the pressure of hydrogen measured by the pressure switch (7) is greater than or equal to a first threshold value, and when the pressure difference between the inlet and the neck of the Venturi tube (2) measured by the dif- pressure switch differential (8) is greater than or equal to a second threshold value, said first and second threshold values ​​being predetermined in function of the device applications (1) and respectively set to the pressure switch (7) and the differential pressure switch (8).

5. Device (1) according to any one of claims 3 or 4 ca- characterized in that the pressure regulator (11) is of the normal type- improperly closed and comprises a valve (14) movable between a position “closed” in which it rests on a seat (15), according to a partial sealing, so as to limit the passage of hydrogen through of said seat (15), and an "open" position in which it is no longer in support on said seat (15) so as to allow more circulation importing hydrogen upstream of the flow limiter (13), said valve (14) being connected by a rod (16) to a membrane (17) de- trainable.

6. Device (1) according to claim 5 characterized in that the servo- regulator (12) comprises a needle (19) movable between a position “open” in which it allows the circulation of hydrogen taken upstream of the pressure regulator (11) up to the membrane (17) of said pressure regulator (11) on the side opposite the valve (14), and a “closed” position in which it rests on a seat (20), according to a partial seal, so as to limit the passage said hydrogen and to allow the displacement of the membrane (17) of said pressure regulator (11) to bring the valve (14) back to its closed position, a movable membrane (21) for moving said needle (19) from its open position to its closed position, and vice versa, pressure means (22) tending to maintain said needle (19) in support against the membrane (21) and return means (23) tending to return said membrane (20) to a position such that it maintains the needle in its open position, said membrane (21) being subjected, on the one hand, to the pressure of the gaseous hydrocarbon taken from the level of the first inlet port (3) determining a set pressure and, on the other hand, to the pressure of the hydrogen taken downstream of the regulator pressure (11).

7. Device (1) according to claim 6 characterized in that the means return screw (23) of the servo-regulator (12) are associated with a screw of adjustment (24) allowing the force of said return means (23) to be adjusted.

8. Device (1) according to any one of claims 3 to 7 ca- characterized in that said flow limiter (13) is of the screw type and includes an adjustment screw (25) which, when screwed or unscrewed, allows respectively to reduce or increase the flow rate of injected hydrogen at the neck of the Venturi tube (2) and, consequently, to modulate the ratio of hydrogen in the mixture produced by the device (1).

9. Method of implementing a device (1) according to any one of the claims 1 to 8 upstream of at least one burner of a boiler gas characterized in that it comprises at least the following stages: a) switching off the device (1), the latter only delivering gaseous hydrocarbon, its safety and regulation group hydrogen (6) not being electrically powered, b) positioning the burner at a correct operating point responding to its maximum power, then measuring the oxygen level in the fumes coming out of the gas boiler, c) putting the safety and regulation group into manual mode of hydrogen (6), then measurement of the oxygen level present in said fumes, d) adjustment of the injected hydrogen flow rate using the safety group and hydrogen regulation (6) compared to the data of a re- showing the evolution of the oxygen level in the fumes coming out of the gas boiler depending on the rate of hydrogen injected, e) switching off the device (1), the latter only delivering gaseous hydrocarbon, its safety and regulation group hydrogen (6) not being electrically powered, f) positioning the burner at a correct operating point- responding to its minimum power, then measuring the oxygen level in the fumes coming out of the gas boiler, g) putting the safety and regulation group into manual mode of hydrogen (6), then measurement of the oxygen level present in said fumes, h) adjustment of the injected hydrogen flow rate using the safety group and hydrogen regulation (6) in relation to the data of said abacus, 1) putting the safety and regulation group into automatic mode of hydrogen (6).

10. | Method according to claim 9 characterized in that it comprises, before step a), a step of creating the abacus showing the evolution of the oxygen level in the fumes leaving the gas boiler in depending on the rate of hydrogen injected, this creation step based on the following input data: - the excess air applied to said burner, - the range of variation of the hydrogen rate, - the nature of the gaseous hydrocarbon and the nature of the hydrogen.