Flashback-proof gas burner

Abstract

To provide a flashback-proof gas burner adapted to be coupled to an aperture of a combustion chamber.SOLUTION: The gas burner is characterized by a specific configuration of a probe and its location for sensing the temperature. The probe has a fast response to changes in temperature, in particular when the flame is extinguished, allowing a fast response to close a valve for supplying gas to an inlet port, thereby preventing any explosion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flashback-proof gas burner adapted to be coupled to an aperture in a combustion chamber. The gas burner is characterized by the specific configuration and location of a probe for detecting temperature. The probe has a fast response to temperature changes, especially when the flame is extinguished, allowing a fast response to close the valve for supplying gas to the inlet port, thereby preventing any explosion. [Background technology]

[0002] One of the more intensively developed technological fields is all that is related to the combustion of hydrocarbons, mainly due to the impact on the emission of greenhouse gases, certain toxic gases such as NOx, and above all due to the very strict safety requirements that are imposed on the combustion of hydrocarbons.

[0003] Combustion of hydrocarbons formed by a mixture of various gases, such as natural gas, has different conditions than the combustion of gases such as hydrogen, methane, or propane. Each of the gases has different chemical reaction kinetics with very different reaction rates and combustion temperatures.

[0004] Different reaction rates mean that the flame position within the burner tends to be closer to or further away from the nozzle, and therefore the burner design must be suitable for stable and safe flame anchoring.

[0005] Burners based on premixing a fuel gas with a combustion gas, usually air, are well known. Premix burners are easy to manufacture because they have different mixing and injection stages in the combustion chamber, and each component only needs to perform one function, making the burner easier to manufacture.

[0006] However, premix burners have several safety issues. The most obvious is that when the fuel is mixed with the supporting material, a reaction can be initiated at any time when the ignition energy is reached, which can occur before the mixture is introduced into the combustion chamber. This can lead to an explosion and the risk of such an accident.

[0007] Another problem that exists with premixed burners is that the parts that form the conduit for the mixture from where it is formed to the burner have joints that must be very carefully sealed against leaks, since if the mixture of gas and combustion-supporting substance were to spread outside the device, it would create a danger in the vicinity of the device.

[0008] In either case, the accumulation of fuel and supporting materials without the fuel being burned poses an explosion hazard. This condition primarily occurs when the flame is extinguished for some reason while the burner is operating. Because fuel or a mixture of fuel and supporting materials continues to enter the combustion chamber without burning to consume the fuel, the accumulation of fuel and supporting materials can become so large that it can explode and cause serious damage.

[0009] Additionally, if the flame is extinguished after the burner is turned on, there is an area of ​​the burner that is hot enough to become an ignition source as the burning fuel mixture may reach ignition energy levels.

[0010] To avoid fuel buildup, the valve that shuts off the fuel supply must be actuated as quickly as possible. According to regulations, this should occur in less than one second.

[0011] Very fast sensors based on flame radiation measurements are known, which react almost instantaneously to sudden drops in radiation, such as occurs when a flame goes out. The problem with this type of system is its technical complexity and high cost, especially when, in addition to the complexity, two or more must be installed for measurement redundancy for safety reasons.

[0012] The problems described and known in the state of the art are solved in a very effective and inexpensive way by the invention described below. Summary of the Invention

[0013] A first aspect of the present invention is a flashback-proof gas burner adapted to be coupled to an aperture of a combustion chamber such that the combination of the burner and the combustion chamber is a heat generating system.

[0014] A first aspect of the present invention is a burner that allows for a rapid response to flame extinction. The first aspect of the present invention is preferably adapted to be installed within the opening of a combustion chamber, and can function, for example, as part of a replacement kit for other burners installed on the opening of the combustion chamber, allowing for the replacement of burners with different combustion mechanisms or adapted to burn different gases. In this configuration, no modifications to the combustion chamber are required.

[0015] The gas burner is suitable for burning fuel gases including hydrogen, and is more particularly adapted for burning hydrogen.

[0016] The gas burner is a flashback-proof gas burner, and the bonding between the fuel and the combustion support material occurs just before combustion occurs. This configuration is very safe, as the fuel has no ability to react until it is already introduced into the combustion chamber.

[0017] Thus, the fuel is supplied through one set of conduits and the combustion supporting substance is supplied separately through a different set of conduits from the fuel.

[0018] Burner is -Air inlet port; a fuel gas inlet port; a fuel gas manifold in fluid communication with the fuel gas inlet port by a fuel gas conduit, the fuel gas manifold comprising at least one fuel gas nozzle positioned to inject fuel gas into the combustion chamber when the burner is operably coupled to the combustion chamber; an air manifold in fluid communication with the air inlet port by an air conduit, the air manifold having at least an air outlet configured to supply air proximate the gas nozzle to operatively create a combination of air and fuel gas within the combustion chamber and external to the flashback-preventing gas burner; Equipped with.

[0019] The fuel inlet port allows fuel to enter the combustion chamber, for example from a pressure pump or from a tank containing fuel, at a pressure higher than the pressure at which the combustion chamber is operating, preferably about ambient pressure.

[0020] The fuel gas manifold receives the fuel coming from the inlet port and functions as a space where the fluid state of the fuel, e.g., pressure, is homogenized, so that the fluid state of the fuel is the same everywhere, especially where at least one fuel gas nozzle is located. According to one embodiment, when the fuel gas manifold comprises multiple fuel gas nozzles, each nozzle operates under approximately the same conditions.

[0021] The air inlet port allows air to enter the combustion chamber, for example, from an air impeller, thereby providing control of the flow, particularly the air / fuel ratio, when the flow of fuel gas is also under control, as is the case in the present invention. According to a preferred embodiment, the air / fuel ratio is operationally within the range of [1.05, 2.1], more preferably within the range of [1.0, 1.8], more preferably within the range of [1.1, 1.7], more preferably within the range of [1.2, 1.6], more preferably within the range of [1.3, 1.5], more preferably about 1.4 volumetrically, relative to the air / fuel ratio at stoichiometric conditions, and in all cases operating with excess oxygen.

[0022] For clarity, we use standard mathematical notation where (a,b) denotes an open interval between the a and b values, and [a,b] denotes a closed interval between the a and b values. An open interval does not include the extreme values, and a closed interval does include the extreme values. An interval may be open at one end and closed at the other end.

[0023] According to one example of implementation, the system formed by the combustion chamber and the burner includes an exhaust probe at the exhaust gas outlet for measuring the concentration of at least one component of the exhaust gas, which probe is preferably part of a closed-loop control system for ensuring the air-fuel ratio as a set value.

[0024] According to a preferred embodiment, the air-to-fuel ratio is constant for any given air intake flow rate.

[0025] Air enters the air manifold through an air inlet port, and the air manifold houses a fuel gas manifold. The air manifold has at least one air outlet through which at least one fuel gas nozzle injects fuel into the combustion chamber. The fuel gas exits the gas nozzle through the air outlet, allowing the air flow to impinge on the injected fuel gas and causing the two flows to merge in the combustion chamber.

[0026] According to a preferred embodiment, the fuel gas manifold comprises a plurality of fuel gas nozzles which inject fuel gas through at least one air outlet of the air manifold.

[0027] According to another embodiment, which may be according to any of the embodiments disclosed below, the air manifold includes a plurality of air outlets, and each fuel gas nozzle is adapted to inject fuel gas through an air outlet of the air manifold.

[0028] moreover, the burner comprises a probe adapted to sense a temperature, the probe comprising a connection part and a heat measurement area; The connecting portion of the probe is housed in the air manifold and the heat measurement area is located in or near the area where the flame is located when the gas burner is in operating mode.

[0029] The probe is an element responsible for carrying out a thermal measurement of the thermal state, this probe comprising at least two different parts: an area where a parameter representative of the thermal state is measured, and a connection part forming the link between the area where the measurement is carried out and a connection part providing a signal with a measured value that makes it possible to act, for example, at the moment when flame extinction is detected.

[0030] The connecting part is a structural part, but may have other functions, such as transmitting signals obtained in the measurement region. The connecting part is understood as a part of the probe other than the measurement area. An example of a connecting part is the body of the probe, which has wires or communication elements for carrying measurement signals. Another example of a connecting part is a part of the head body, which comprises a measurement region and a separate part that is cooled in accordance with the present invention and is different from the measurement region. In order for the probe to respond quickly, the connecting part does not need to be a complete part or piece, but simply a part that is operatively under different temperature conditions from the measurement region of the probe.

[0031] The measurement area is located in or near the area where the flame is operatively located during combustion. This allows for the measurement of flame temperature, an estimate of flame temperature, or a parameter representative of thermal conditions. An example of a parameter representative of thermal conditions is a probe that provides a potential difference in response to temperature or temperature fluctuations. Any physical element of the probe that supports the measurement area will also be hot. This creates thermal inertia, which means that a sudden temperature change, such as that caused by flame extinction, will not be detected instantly in the signal provided by the temperature measurement area but will require a time period that may be too long to meet safety requirements. A very slow response of the signal containing the temperature value of the measurement area will prevent the fuel supply valve from closing in time.

[0032] However, according to a first aspect of the invention, the probe connection is housed within an air manifold, the interior of which is not yet filled with fuel and therefore contains fresh air. In this configuration, the fresh air flow is by convention in direct contact with the probe connection, providing a very effective form of heat transfer, which tends to reduce its temperature as quickly as possible.

[0033] As a result, upon flame extinction, the temperature measurement area attached to the cooled connection will lose its temperature by conduction, providing a probe output signal response that is indicative of the actual temperature drop with a much faster response time.

[0034] This configuration has been experimentally verified to allow response times well below the regulatory maximum of one second for the device to be safe.

[0035] In one embodiment, even when two probes are involved under these conditions, the manufacturing cost for a temperature sensor based solution rather than a flame radiation index based solution is significantly lower.

[0036] In one embodiment according to any of the previously disclosed embodiments, the probe is a thermocouple.

[0037] A thermocouple is a device that utilizes two dissimilar metals so that a potential difference is established depending on the temperature of one metal and the other. In one example of a thermocouple, the dissimilar metals are in close proximity to each other, thereby creating a potential difference at the junction. This is not the only configuration, and the metals can be at different points under different thermal conditions.

[0038] In the context of the present invention, two types of thermocouples are to be distinguished: in the first type of thermocouple, the measurement is made in a measurement region located at the tip of the probe, and the response in the form of a potential difference represents the absolute temperature at which the tip is located.

[0039] A second type of low-cost thermocouple has a first metal in the measurement area at the tip of the probe and a second metal in a reference point, called the cold junction, located within the connection away from the measurement area.

[0040] With this second type of thermocouple, the measured value does not establish an absolute temperature measurement, but provides a signal representative of the thermal conditions near the flame that depends, among other factors, on the temperature difference between the measurement area and the cold junction.

[0041] Next, in one embodiment according to any of the previously disclosed embodiments, the probe is a thermocouple, the temperature measurement region of the probe is at a bimetallic joint of the thermocouple, and the connecting portion of the probe is at least a part of a metallic connecting portion connecting the bimetallic joint of the thermocouple.

[0042] This embodiment follows the first type of thermocouple.

[0043] As mentioned above, a thermocouple according to this first type is a probe with a bimetallic joint adapted to provide a signal responsive to temperature.

[0044] The signal is a potential difference that becomes larger or smaller depending on the temperature of the bimetallic joint. The signal is transmitted to the connection via conductive elements that are also good thermal conductors and part of the connection, and therefore exposed to the burner supply air flow in the operating mode.

[0045] As a result, the bimetallic joint is at a temperature close to the flame temperature when the burner is in operation. When the flame is extinguished, the burner supply air is cold and comes into contact with the cold connecting part, which is closer to the ambient temperature than the measuring area, so that as soon as the flame is extinguished, the temperature of the connecting part causes a rapid cooling of the bimetallic joint via the conductive element that maintains the connection between the bimetallic joint and the connecting part.

[0046] An embodiment using a second type thermocouple as the probe according to any of the disclosed embodiments, in which the probe is a thermocouple comprising two dissimilar metal parts, the measurement region of the probe including one dissimilar metal and the other dissimilar metal at a reference cold junction located within the connection portion of the probe, and the probe is adapted to provide a signal amplitude in response to a temperature difference between the temperatures of the at least two dissimilar metals.

[0047] With this thermocouple configuration, the signal amplitude responds to the temperature difference between the two portions of the probe: the measurement region operatively located near or within the flame, and the cold junction operatively located at the connecting portion and cooled by fresh air flowing inside the air manifold.

[0048] In this embodiment, when the flame is extinguished, the temperature of the measurement area is reduced, and the temperature of the cold junction is also reduced. As the cold junction is cooled by fresh air flowing through the air manifold in which the cold junction is located, the temperature difference increases in the first stage and tends to zero over time.

[0049] Flame extinction can be detected in several ways: According to the first criterion, the variation of the signal proportional to the temperature difference in absolute value exceeds a predetermined threshold value.

[0050] The threshold is a positive value, lower the smaller the variation that is allowed. The value is positive because the variation relative to the reference is measured using an absolute value function, which is always positive.

[0051] However, the same criteria can be converted into a standard that uses absolute (or true) values ​​rather than values ​​relative to a given reference. In this case, the comparison is not with a threshold value, but with a value that is either above or below the reference value. However, this alternative form of expression is considered equivalent in all cases.

[0052] According to the second criterion, the derivative with respect to time of the signal proportional to the temperature difference, or an estimate of such a derivative, varies in absolute value beyond a predetermined threshold.

[0053] The first and second criteria are evaluated based on a signal proportional to the temperature difference, the third criterion being the criterion that first identifies a change that establishes the need to act on the control valve to shut off the fuel gas.

[0054] In one embodiment according to any of the previously disclosed embodiments, the probe has an elongated shape and the temperature measurement region is located at one end of the probe.

[0055] The elongated configuration of the probe is - perpendicular to the wall of the air manifold and to the measurement area under the influence of the flow entering through the air outlet of the air manifold to admit air into the combustion chamber, or - being oblique to the wall of the air manifold, which positions the measurement area away from the influence of the flow entering through the air outlet of the air manifold to admit air into the combustion chamber; Allows placement of probes positioned in two different orientations.

[0056] These two options may be used in any of the disclosed embodiments, particularly the first type thermocouple and the second type thermocouple.

[0057] According to a preferred embodiment applicable to all described examples, the air manifold houses a fuel gas manifold, the air manifold having flat or convex walls. Air openings are located in the flat or convex walls, and fuel gas is introduced through the air openings using a nozzle or injector (both terms are used). The fuel gas manifold housed inside the air manifold positions the nozzle near an interior area of ​​the flat or convex wall of the air manifold. In a preferred embodiment, the fuel gas manifold is formed by at least two pieces, preferably stamped sheet metal, joined together. These two pieces extend along a flat or convex main reference surface. According to one embodiment, the fuel gas manifold has an opening that does not cover the entire main reference surface. The probe preferably passes through one of the openings and is perpendicular or oblique to the main reference surface.

[0058] The first option is best suited for thermocouples of the first type, whose measurement area is subject to the influence of airflow, and the second option is best suited for thermocouples of the second type, whose measurement area is located away from the influence of airflow.

[0059] These two positions are characterized by the elongated configuration, a temperature measurement area operatively located within or near the flame-locked area of ​​the side of the combustion chamber; a connection part located inside the air manifold, and a connection for acquiring a measurement signal, which is located outside the air manifold and is accessible for connection to a control means; This means that the three probe locations can be differentiated within a small space.

[0060] In one embodiment according to any of the previously disclosed embodiments, the fuel gas manifold is housed within the air manifold.

[0061] The arrangement in which the fuel gas manifold is housed inside the air manifold is a very effective arrangement for positioning at least one fuel gas nozzle or injector on the wall side of the air manifold that defines the boundary between its interior and the combustion chamber.

[0062] When the fuel gas manifold is provided with multiple injectors or nozzles, these are distributed on the surface of the fuel gas manifold close to the inner surface of the wall of the air manifold. Thus, fuel gas can be injected into the interior of the combustion chamber through the opening of the air manifold, and at the same time, an air flow can be injected to join the fuel gas just before it enters the combustion chamber. Therefore, the resulting burner is a flashback-proof burner.

[0063] In one embodiment according to the previously disclosed embodiments, at least one fuel gas nozzle injects fuel gas through at least one air outlet, with a gap between the fuel gas nozzle and the air outlet to allow air to pass through.

[0064] According to this embodiment, the air outlet through which the fuel gas is injected by the nozzle or injector has a gap between the outlet and the nozzle, according to a preferred embodiment the gap is shown according to a radial direction with respect to the axis of the nozzle.

[0065] According to one example, when an embodiment includes multiple air outlets and also multiple nozzles, air ducts are provided between the inner wall of the air manifold wall and the fuel gas manifold wall. These ducts promote air distribution near each nozzle. These air ducts also provide reinforcing ribs for the surface of the air manifold facing the combustion chamber.

[0066] This gap allows air to enter the combustion chamber, but forces the air to flow against the flow of fuel gas, and preferably transverse to the gas flow, thereby promoting coupling between the two.

[0067] In one embodiment according to any of the previously disclosed embodiments, the fuel gas manifold comprises at least two plates joined together to form either a flat collector or a collector extending along a convex surface.

[0068] A very efficient combustion mode is one in which the flame has a flat configuration, or at least extends along a surface: the air-fuel gas coupling process takes place on one side of the surface supplying the flame, and after combustion, the hot gases carry the heat to the rest of the combustion chamber, where the exchange means exist for transporting the heat to its final application.

[0069] It has been shown that easily constructed configurations are based on the joining of two plates, preferably punched or stamped, which together result in a flat manifold or a manifold extending along a convex surface, a particular case of which is a spherical section.

[0070] In one embodiment according to any of the previously disclosed embodiments, the air manifold comprises a wall having an air outlet, the wall being either a flat wall or a wall extending along a convex surface.

[0071] The walls of the air manifold with the air outlets define, among other parameters, the shape and anchorage of the flame. Flat or convex walls allow the burner to optimize its available surface when installed in the opening of the combustion chamber. In certain embodiments, the flat or convex walls are received in an area surrounded by a seat adapted to close the opening of the combustion chamber when the burner is operatively installed in the combustion chamber.

[0072] In one embodiment according to any of the previously disclosed embodiments, the probe passes through at least a wall of an air manifold that includes an air outlet.

[0073] The probe is located partially inside the air manifold, and the end having the area for temperature measurement is located within the combustion chamber. According to this embodiment, the probe passes through at least a wall of the air manifold that includes the air outlet.

[0074] This arrangement has the advantage of resulting in a very compact and responsive device and is particularly useful when the configuration of the area in which the nozzles are distributed has a configuration that extends according to a plane or convex surface, since a perpendicular or nearly perpendicular position to this surface allows a very fast cooling effect.

[0075] In one embodiment according to previously disclosed embodiments, the probe passes through the fuel manifold.

[0076] The described configuration of the fuel manifold is either flat or convex. This does not mean that the entire manifold covers either the flat or convex area, but rather that the nozzles are positioned according to either a flat or convex spatial distribution. That is, according to one embodiment, the fuel manifold is formed by, for example, radially distributed conduits that cover the area where the nozzles are positioned. In this configuration, the feature that the probe "passes" through the fuel manifold can be interpreted in either of two ways: the probe passes from one side to the other, for example, using gaps or openings left by radial ducts, or it actually passes through the fuel gas wall, which may require sealing the inlet and outlet openings in the fuel manifold and insulating the section of the probe housed inside the fuel manifold. The first case is the preferred feature.

[0077] According to this embodiment, the probe passes through the fuel manifold, preferably through an opening, and also passes through at least one wall of the air manifold, preferably through an opening.

[0078] In the specific example described below, not only do the elements involved in combustion extend close to either a flat or convex surface, but the entire burner essentially adopts this shape, so that the sensor is easily accessible from the outside while at the same time keeping the two most relevant internal parts, the connection part and the temperature measurement area, at different temperatures.

[0079] In one embodiment according to any of the previously disclosed embodiments, the burner further comprises a processor; the processor is in communication with the probe and with a command valve for supplying the fuel gas manifold, the command valve being adapted to shut off the flow of fuel gas when commanded; the processor is further adapted to receive a signal from the probe providing a measurement in response to temperature; and a) the absolute measurement signal value, or b) the absolute value of the first derivative with respect to time, or c) Either of the two former options a) or b) is adapted to send a signal to a control valve to shut off the flow fuel gas inlet when the variation value of exceeds a threshold value.

[0080] These three options apply to all types of probes.

[0081] Option a) is preferably used when the probe is a first type thermocouple when the temperature responsive measurement is a temperature value in the measurement region of the probe, and option b) is preferably used when the probe is a second type thermocouple when the temperature responsive measurement is a measurement of the temperature difference between the measurement region of the probe and a colder region.

[0082] According to this embodiment, the burner is provided with safety means that allow it to react to dangerous situations, such as the extinction of the flame. The signal generated by the probe is sent to a processor that compares the value of the signal representative of the temperature in the temperature measurement area with a threshold value. If the signal representative of the temperature falls below this threshold value, the processor sends a signal to the burner commanding the closure of the fuel supply valve.

[0083] Although the closing time is not instantaneous, a configuration according to one of the described examples allows for a very fast response in generating a signal indicative of a temperature change due to low thermal inertia. The processor responds to this change in input signal by closing the valve in a very short time, clearly less than the number of seconds required by regulation.

[0084] In one embodiment according to the previously disclosed embodiments, the processor is further adapted to send a signal to the recommended valve to shut off the flow fuel gas inlet when the signal representing the temperature is greater than a second threshold value.

[0085] According to this embodiment, the processor is adapted to react by closing the fuel gas inlet when it detects flame extinction and when there is a combustion condition that results in an extremely high temperature above a predetermined condition, which is also a dangerous condition that must be controlled, and according to this embodiment, the processor also responds by closing the control valve.

[0086] A second aspect of the present invention is a burner system comprising a burner according to any of the previously disclosed embodiments and further comprising a combustion chamber, the burner being installed and adapted to be coupled to an aperture in the combustion chamber.

[0087] The burner may further comprise two probes for redundant measurements according to any of the above-mentioned embodiments, where both thermocouples can be of one type, both can be of a second type, or the first probe can be of one type and the second probe can be of a second type.

[0088] This is also an embodiment of a system burner, a system such as that described above, further comprising an exhaust probe adapted to measure at least one component of the exhaust gas, and wherein the processor is further adapted to control the burner, preferably in a closed loop, so that the air / fuel ratio is, relative to the air / fuel ratio at stoichiometric conditions, operationally, in all cases operating with excess oxygen, preferably when the air / fuel ratio is constant for any air inlet flow rate, a volumetric measurement within the range of [1.05, 2.1], more preferably within the range of [1.0, 1.8], more preferably within the range of [1.1, 1.7], more preferably within the range of [1.2, 1.6], more preferably within the range of [1.3, 1.5], more preferably about 1.4.

[0089] These and other features and advantages of the present invention will be more clearly understood from the following detailed description of preferred embodiments, given by way of illustrative and non-limiting example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0090] [Figure 1] This figure shows in a perspective view a first embodiment of a burner including air propulsion means and a fuel gas supply management valve, the burner being installed in an aperture of the combustion chamber. [Figure 2] This figure shows the same embodiment as the previous figure in perspective view, with the burner, fuel gas valve and drive means separated from the combustion chamber to allow visual access to both the combustion chamber aperture and the remaining elements. [Figure 3] This figure shows the same embodiment as the previous figure in perspective view, with the valves and pipes for the fuel gas supply and air propulsion means removed to allow a closer view of the burner. [Figure 4] This figure shows the same burner in perspective view with the combustion chamber removed. [Figure 5] This figure shows the same burner as the previous figure, but from an opposite perspective, allowing visual access to the air outlet and fuel gas nozzle outlet. [Figure 6] This view shows a cross-section of the previous view allowing visual access to the interior portions of the air manifold and the fuel gas manifold. [Figure 7] This figure shows the cross section of the previous figure using a different perspective, moving the probe off the burner and providing visual access to all parts of the probe. [Figure 8] This figure shows an enlarged view of FIG. 7, but with the probe in its final position. [Figure 9] This figure shows the same elements and the same cross section as shown in Figure 7, but with the probe in its final position. DETAILED DESCRIPTION OF THE INVENTION

[0091] As will be appreciated by those skilled in the art, aspects of the present invention may be embodied as a flashback-resistant gas burner adapted to be coupled to an aperture.

[0092] Figure 1 shows an embodiment of a flashback-proof gas burner (B) that includes a combustion chamber (5), which is a chamber in which a combustion reaction takes place in the form of a flame, producing heat that is transferred, for example via a heat exchanger, to a destination for this energy depending on the end use.

[0093] In this embodiment, the combustion chamber (5) has an aperture (5.1) onto which the burner (B) is coupled and fixed. This configuration allows for maintenance of both the burner (B) and also the elements accessible from inside the combustion chamber (5), as well as for example the replacement of the complete burner (B), which may be justified by the need to use a burner (B) configured for a different type of fuel.

[0094] The burner (B) according to this embodiment is adapted to burn a gaseous fuel containing hydrogen, more particularly containing only hydrogen.

[0095] The burner (B) in this embodiment is a flashback-proof gas burner and therefore has an air inlet port (1), a combustion support material, and a gas fuel inlet port (2). Figure 1 shows at the bottom of the figure an air propulsion means (4) for drawing air from the atmosphere into the combustion chamber (5) and imposing an overpressure above atmospheric pressure. Air leaving the propulsion means (4) is conducted through an air conduit (6.1) into the interior of the air manifold (6).

[0096] A control valve (8) is also shown at the bottom of Figure 1, which controls the flow of fuel gas. The fuel gas can come from either a source under pressure or by propelling the fuel gas. This source of fuel gas is not shown in the figure for clarity.

[0097] Figure 2 is a perspective view of the same embodiment, where the burner (B) is held together with the command valve (8) and the air propulsion means (4), and this group of elements is separated from the combustion chamber (5) to make it possible to observe the aperture (5.1) of the combustion chamber (5) onto which the burner (B) is engaged.

[0098] The flame formation in the burner (B) occurs immediately behind a circular plate that engages over the aperture (5.1) of the combustion chamber (5) which, according to this particular embodiment, has a circular configuration. Also, according to this embodiment, the flame emits heat into the combustion chamber (5), which also has a primarily flat configuration and includes a heat exchanger (5.2), shown in this embodiment as a ring stack, through the aperture (5.1).

[0099] In Figure 3, both the control valve (8) and the air propulsion means (4) have been eliminated to allow a close-up view of the burner (B) mounted above the combustion chamber (5).

[0100] Figure 4 shows the same burner (B) after removing the combustion chamber (5).

[0101] Figures 1 to 4 also show the outer parts of the two probes (7), mainly the ends that allow connections to receive the signals measured by the probes (7) and to determine the flame temperature or measurements of the zone close to the flame. The use of two probes (7) is a safety measure for redundancy in the measurement of the same parameters.

[0102] For this purpose, they engage connections that convey the signals to a processor (not shown) in charge of processing the signals and responding to the measured values, and in particular to changes thereof.

[0103] The command valve (8) receives a signal from the processor in response to, for example, a flame extinguishing event, thereby allowing the burner (B) to be shut off.

[0104] Fuel gas flows from the control valve (8) to the fuel gas manifold (3) by a fuel gas conduit (3.1).

[0105] Burner (B) is a flashback-proof gas burner in which the fuel gas and the combustion support material meet in a cross-flow manner just as they enter the combustion chamber (5). To achieve this, the fuel gas manifold (3) is housed inside the air manifold (6), both of which (3, 6) have a similar configuration. In this embodiment, the fuel gas manifold (3) has a flat configuration and has a plurality of fuel gas nozzles (3.2) distributed on at least its surface for providing fuel gas jet injection into the combustion chamber (5).

[0106] Figure 5 shows a perspective view of the burner (B) from the opposite side of the burner to the perspective used in Figures 1 to 4. This view shows the insulation (10) located in the aperture (5.1) of the combustion chamber (5) which ensures a thermally protected closure.

[0107] The figure also shows the electrodes (9) which cause the flame ignition, their ends being placed in a position close to the area where the flame is operatively fixed to the burner.

[0108] The inner zone of the insulation (10) shows several outlets corresponding to the outlet openings of a plurality of fuel gas nozzles (3.2) that are intended to introduce fuel gas into the combustion chamber (5). These outlets are air outlets (6.2), i.e., they are outlets through which air exits, since the ends of the fuel gas nozzles (3.2) do not completely close the surrounding air outlets (6.2). The air outlets (6.2) are outlets located in the wall of the air manifold (6). Therefore, in this embodiment, the fuel gas manifold (3) and the air manifold (6) have a flat configuration, since the position of the fuel gas nozzles (3.2) must be near and inside the air outlets (6.2) located in the wall of the air manifold (6).

[0109] That is, between the fuel gas nozzle (3.2) and the air outlet (6.2) through which the fuel gas nozzle (3.2) passes, there is a gap that determines the distance that the air or combustion support material can enter around the jet of fuel gas injected by the fuel gas nozzle (3.2). Under these conditions, the air inlet occurs mainly in a radial direction transverse to the fuel gas inlet direction. This condition allows the flows to cross and creates a coupling process in a very small space.

[0110] Let us return to Figure 8 to see what this configuration looks like in cross section.

[0111] Figure 6 shows a cross-section of the example shown in Figure 5, observing the flat configuration of the fuel gas manifold (3) and how it is housed within the air manifold (6), one of the walls of the air manifold (6) being substantially flat and housing the air outlet (6.2). However, the wall of the air manifold (6.2) that is closely parallel to the wall of the fuel gas manifold (3) has reinforcing ribs that also create channels that facilitate air entry into the area surrounding the air outlet (6.2) to reduce pressure drop.

[0112] Figure 7 is another cross-sectional view in which the probe (7) is shown in an exploded perspective view. This same view is seen in Figure 9 where the probe (7) is now in its final position. The cross-sectional view removes half of the burner (B) where the second probe (7) is located.

[0113] FIG. 8 is an enlarged view of FIG. 9 and shows how the probes (7) are positioned relative to each of the interior spaces of the burner (B), particularly the air manifold (6) and the fuel gas manifold (3).

[0114] To extract the measurement signal, the probe (7) has one connection located in the measurement area (7.2) and a second connection, the cold junction, in the connection area. The signal responds to the potential difference between the two points. In this embodiment, the probe (7) is a second type of thermocouple, in which the signal is generated in the form of a potential difference in response to specific temperature conditions in the measurement area (7.2) and the cold junction.

[0115] Between the two ends, a sleeve-shaped section is shown in an elongated configuration, allowing it to be screwed onto the rear wall of the air manifold (6) forming a sealed joint, and a further elongated section, made of metal in this embodiment, through which the signal is transmitted. This extension, which is metal in this embodiment, is a good conductor of heat, and the part that conducts the signal is also a good signal conductor. This should be interpreted as a connection part (7.1) to any intermediate section between the two ends of the probe (7), which has the ability to conduct heat with the area (7.2) whose temperature is to be measured. In this embodiment, the connection part (7.1) also contains the cold junction of the thermocouple. Referring to Figure 8, the connecting part (7.1) is located inside the space formed by the air manifold (6), so that this connecting part (7.1) is exposed to the phenomenon of heat transfer by convection when interacting with the air circulating inside the air manifold (6), so that the temperature of the connecting part (7.1) is close to the ambient temperature, except for any variations that may occur due to the pressure increase of the air propulsion means (4).

[0116] The temperature measurement area (7.2) is then at one end, with the probe (7) passing through at least the wall of the air manifold (6), and the temperature measurement area (7.2) being in direct contact with the interior of the combustion chamber (5). To reach this location inside the combustion chamber (5), the probe (7) also overcomes the location of the fuel gas manifold (3) by either passing through the fuel gas manifold (3) or, more safely, passing between channels or ribs that carry the fuel gas, leaving free space or openings between such channels or ribs, such as those that allow the probe (7) to pass through. This form of passage, rather than passing through the interior of the fuel gas manifold (3), eliminates the possibility of high temperatures being transmitted inside the space containing the fuel gas in an operating configuration, thereby reducing the risk.

[0117] As shown in Figures 5 and 6 disclosed above, the temperature measuring area (7.2) emerges from the surface formed by the wall of the air manifold (6) in direct contact with the interior of the combustion chamber (5) and protrudes a distance that allows the temperature measuring area (7.2) to be at least close to the flame.

[0118] The temperature measurement area (7.2) measures either the flame temperature or a temperature close to it.

[0119] When the flame is extinguished, the temperature in the temperature measuring area (7.2) drops because heat in this area is transferred both to the surroundings and along the probe (7), especially through the connection (7.1). The cold junction located at the connection cools faster because it is under the influence of the air flow in the air manifold, so the temperature difference increases in the first period and then tends to decrease. This rapid change in the very first period is detected and a signal is generated with a very short response time, sufficient to respond by cutting off the fuel gas supply.

[0120] In this embodiment, the signal representative of and proportional to the temperature difference, in particular its rapid development due to flame extinction, is processed by a processor which compares it with a threshold value, evaluates the absolute value of the comparison and, if it is found to exceed said threshold value, sends a signal commanding the closure of the control valve (8), thereby cutting off the fuel gas supply.

[0121] This rapid response prevents the accumulation of fuel gases inside the combustion chamber (5) which could lead to an explosion.

Claims

1. A flashback-proof gas burner (B) adapted to be coupled to an aperture (5.1) of a combustion chamber (5) suitable for the combustion of a fuel gas containing hydrogen, said burner (B) comprising: an air inlet port (1); a fuel gas inlet port (2); a fuel gas manifold (3) in fluid communication with the fuel gas inlet port (2) by a fuel gas conduit (3.1), the fuel gas manifold (3) comprising at least one fuel gas nozzle (3.2) arranged to inject fuel gas into the combustion chamber (5) when the burner (B) is operably coupled to the combustion chamber; an air manifold (6) in fluid communication with the air inlet port (1) by an air conduit (6.1), the air manifold (6) having at least one air outlet (6.2) configured to supply air adjacent the gas nozzle (3.2) to operatively effect a combination of the air and the fuel gas within the combustion chamber (5) and external to the flashback-preventing gas burner (B); Equipped with the burner (B) comprises a probe (7) adapted to detect temperature, the probe (7) comprising a connection part (7.1) and a temperature measurement area (7.2); the connecting part (7.1) of the probe (7) is housed in the air manifold (6), and the temperature measurement area (7.2) is located in or near the area where the flame is located when the gas burner (B) is in operation mode; Flashback prevention gas burner (B).

2. 2. Burner according to claim 1, characterized in that the probe (7) is a thermocouple, the temperature measuring area (7.2) of the probe (7) is the bimetallic joint of the thermocouple, and the connection part (7.1) of the probe (7) is at least a part of a metallic connection connecting the bimetallic joint of the thermocouple.

3. 2. The burner according to claim 1, wherein the probe (7) is a thermocouple comprising two dissimilar metal parts, the measurement area (7.2) of the probe (7) including one dissimilar metal and the other dissimilar metal at a reference cold junction located in the connection part (7.1) of the probe (7), and the probe (7) is adapted to provide a signal amplitude in response to a temperature difference between the temperatures of at least the two dissimilar metals.

4. Burner according to any one of claims 1 to 3, characterized in that the probe (7) has an elongated shape and the temperature measurement area (7.2) is located at one end of the probe (7).

5. Burner according to any one of claims 1 to 4, wherein the fuel gas manifold (3) is housed within the air manifold (6).

6. 5. The burner of claim 4, wherein the at least one fuel gas nozzle (3.2) injects the fuel gas through the at least one air outlet (6.2), and a gap exists between the fuel gas nozzle (3.2) and the air outlet (6.2) to allow the air to pass through.

7. 7. Burner according to any one of claims 1 to 6, wherein the fuel gas manifold (3) comprises at least two joined plates forming either a flat collector or a collector extending along a convex surface.

8. 8. Burner according to any one of claims 1 to 7, wherein the air manifold comprises a wall having the air outlets (6.2), the wall being either a flat wall or a wall extending along a convex surface.

9. 9. A burner according to any one of claims 2, 3 and 4 and according to claim 8, wherein the probe (7) is positioned perpendicular to the wall of the air manifold (6) and to the measurement area (7.2) under the influence of a flow entering through an air outlet (6.2) of the air manifold (6) to admit air into the combustion chamber.

10. 9. A burner according to any one of claims 2, 3, 4 and claim 8, wherein the probe (7) is positioned obliquely relative to the wall of the air manifold (6) which positions the measurement area (7.2) away from the influence of the flow entering through the air outlet (6.2) of the air manifold (6) to admit air into the combustion chamber.

11. Burner according to any one of the preceding claims, wherein the probe (7) passes through at least the wall of the air manifold (6) comprising the air outlet (6.2).

12. Burner according to any one of the preceding claims, wherein the probe (7) passes through the fuel manifold (3).

13. the burner further comprising a processor; the processor is in communication with the probe (7) and with a command valve (8) for supplying the fuel gas manifold (3), the command valve (8) being adapted to shut off the flow of the fuel gas when commanded; the processor is further adapted to receive a signal from the probe (7) providing a measurement in response to the temperature; and a) the absolute measurement signal value, or b) the absolute value of the first derivative with respect to time, or c) Either of the two former options a) or b). is adapted to send a signal to the control valve (8) to shut off the flow fuel gas inlet when the variation value of exceeds a threshold value; Optionally, the processor is further adapted to send a signal to the recommended valve (8) to shut off the flow fuel gas inlet when the signal representative of the temperature is higher than a second threshold. A burner according to any one of claims 1 to 12.

14. A burner system comprising a burner according to claim 13 and further comprising a combustion chamber (5), said burner being installed and adapted to be coupled to an aperture (5.1) of the combustion chamber (5).

15. 15. The burner system of claim 14, wherein the burner system further comprises an exhaust probe adapted to measure at least one component of the exhaust gases, and wherein the processor is further adapted to control the burner, preferably in a closed loop, so that the air / fuel ratio is volumetrically measured within the range of [1.05, 2.1], more preferably within the range of [1.0, 1.8], more preferably within the range of [1.1, 1.7], more preferably within the range of [1.2, 1.6], more preferably within the range of [1.3, 1.5], more preferably about 1.4, in all cases when operationally operating with excess oxygen, preferably when the air / fuel ratio is constant for any air inlet flow rate, with respect to the air / fuel ratio at stoichiometric conditions.

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