Anti-backfire gas burner and burner system

Abstract

The invention relates to an anti-backfire gas burner and a burner system. The anti-backfire gas burner is adapted to be coupled to an orifice of a combustion chamber. The gas burner is characterized by a specific configuration of the probe for sensing temperature and its position. The probe has a quick response to temperature changes, particularly when the flame is extinguished, thereby allowing the quick response to close the valve for supplying gas to the inlet port, thereby preventing any explosion.

Description

Technical Field

[0001] The present invention relates to a flashback-proof gas burner adapted to be coupled to an orifice of a combustion chamber. The gas burner features a probe for sensing temperature and a specific configuration of the probe's position. The probe responds quickly to temperature changes, particularly when the flame is extinguished, thereby enabling rapid closure of the valve supplying gas to the inlet port, thereby preventing any explosion. Background Art

[0002] One of the more intensively developed technical fields is anything related to the combustion of hydrocarbons, mainly because of its impact on the emission of greenhouse gases, gases with certain toxicities such as NOx, and, above all, because the combustion of hydrocarbons entails very strict safety requirements.

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

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

[0005] Burners based on premixing of fuel gas and combustion gas, typically air, are known. Premix burners are easy to manufacture because the mixing and injection phases in the combustion chamber are distinct, making the burner easier to manufacture since each component only needs to perform one function.

[0006] However, premix burners present several safety issues. The most obvious is that once the fuel and oxidant are mixed, the reaction can begin any time ignition energy is reached, and this can occur before the mixture is introduced into the combustion chamber. If this occurs, an explosion can occur, creating a risk of unforeseen consequences.

[0007] Another problem present in premix burners is that the parts forming the duct for the mixture from the location where the mixture is formed to the burner have joints that must be sealed very carefully to prevent leakage, since diffusion of the mixture of gas and oxidant outside the device creates a risk in the vicinity of the device.

[0008] In any case, the accumulation of fuel and oxidant without the fuel being burned is a source of explosion risk. This situation primarily occurs when the burner is operating and the flame goes out for any reason. Fuel or a mixture of oxidant and fuel continues to enter the combustion chamber without burning to exhaust the fuel, and thus very high volumes of fuel and oxidant can accumulate, which can explode and cause serious damage.

[0009] Additionally, when the flame goes out after the burner has been operated, high temperature areas of the burner may be a source of ignition because the burning fuel mixture may have reached an ignition energy level.

[0010] To prevent fuel from accumulating, the valve that shuts off the fuel supply needs to be operated as quickly as possible. According to regulations, this should happen in less than a second.

[0011] Very fast-acting sensors based on flame radiation measurement are known, which enable an almost instantaneous response to a sudden drop in radiation, such as occurs when a flame goes out. A problem with this type of system is its technical complexity and high cost, especially if, in addition to its complexity, more than one sensor needs to be installed for measurement redundancy for safety reasons.

[0012] According to the invention described below, the problems described and known in the prior art are solved in a very effective and inexpensive manner. Summary of the Invention

[0013] A first aspect of the present invention is an anti-flashback gas burner.The anti-flashback gas burner is adapted to be coupled to an orifice 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 failure. This first aspect of the present invention is suitable for, and more specifically, installation in an opening of a combustion chamber, allowing the burner to be used, for example, as a component of a replacement kit for other burners installed in the opening of the combustion chamber, thereby replacing a different combustion mechanism or burner suitable for burning a different gas. In this configuration, no modifications to the combustion chamber are required.

[0015] The gas burner is suitable for the combustion of fuel gas including hydrogen, and more particularly, suitable for the combustion of hydrogen.

[0016] The gas burner is a flashback proof gas burner in which the combination of fuel and oxidant occurs only for a short time before combustion occurs. This configuration is very safe as the fuel does not have the ability to react before it has been introduced into the combustion chamber.

[0017] Thus, the fuel is supplied through one set of conduits, while the oxidant is supplied separately through a different set of conduits from the fuel.

[0018] The burner includes:

[0019] - Air inlet port;

[0020] - fuel gas inlet port;

[0021] a fuel gas manifold in fluid communication with the fuel gas inlet port by means of a fuel gas conduit, the fuel gas manifold comprising at least one fuel gas nozzle arranged for injecting fuel gas into the combustion chamber when the burner is operatively coupled to the combustion chamber;

[0022] an air manifold in fluid communication with the air inlet port by means of an air duct, the air manifold comprising at least an air outlet configured to supply air in the vicinity of the gas nozzle for operatively producing a combination of air and fuel gas in the combustion chamber and out of the anti-flashback gas burner.

[0023] 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 that is higher than the pressure at which the combustion chamber operates, preferably about ambient pressure.

[0024] The fuel gas manifold receives fuel from the inlet port and serves as a space where the fluid conditions of the fuel, such as pressure, are uniformed, making them the same at all locations, and particularly at locations where at least one fuel gas nozzle is located. If, according to an embodiment, the fuel gas manifold includes a plurality of fuel gas nozzles, each nozzle operates under substantially the same conditions.

[0025] The air inlet port allows air to enter the combustion chamber, for example from an air impeller, thereby providing flow control, in particular control of the air / fuel ratio when the flow of the fuel gas is also controlled as in the present application. According to a preferred embodiment, in all cases of operation with excess oxygen, the air / fuel ratio measured by volume is operationally in the range of [1.05, 2.1], and more preferably in the range of [1.0, 1.8], and more preferably in the range of [1.1, 1.7], and more preferably in the range of [1.2, 1.6], and more preferably in the range of [1.3, 1.5], and more preferably about 1.4 relative to the air / fuel ratio under stoichiometric conditions.

[0026] For clarity, we use standard mathematical notation, where (a,b) represents an open interval between the values ​​a and b, and [a,b] represents a closed interval between the values ​​a and b. An open interval excludes extreme values, and a closed interval includes extreme values. An interval can be open at one end and closed at the other.

[0027] According to an example of implementation, the system formed by the combustion chamber and the burner comprises an exhaust gas probe at the exhaust gas outlet for measuring the concentration of at least one component of the exhaust gas. This probe is preferably part of a closed-loop control system to ensure the air / fuel ratio is at a set value.

[0028] According to a preferred embodiment, the air / fuel ratio is constant for any intake air flow rate.

[0029] Air enters the air manifold from the air inlet port, which houses the fuel gas manifold. The air manifold includes at least one air outlet, wherein at least one fuel gas nozzle injects fuel through the air outlet into the combustion chamber. The fuel gas exits the gas nozzle through the air outlet, allowing the air flow to impact the injected fuel gas, causing the two flows to merge in the combustion chamber.

[0030] According to a preferred embodiment, the fuel gas manifold comprises a plurality of fuel gas nozzles injecting fuel gas through the at least one air outlet of the air manifold.

[0031] According to another embodiment, which may be according to any of the embodiments disclosed below, the air manifold comprises a plurality of air outlets, and each fuel gas nozzle is adapted to inject fuel gas through an air outlet of the air manifold.

[0032] Additionally:

[0033] - the burner comprises a probe adapted to sense temperature, the probe comprising a connection portion and a heat measurement area;

[0034] - The connection part of the probe is housed in the air manifold and the thermal measurement area is located in or close to the area where the flame is located when the gas burner is in operating mode.

[0035] The probe is an element responsible for performing thermal measurements of thermal conditions, wherein the probe comprises at least two distinct parts: an area measuring a parameter representative of the thermal condition; and a connecting part establishing a link between the area performing the measurement and a connection providing a signal with the measurement result, thus allowing, for example, to act upon the moment of detecting the extinction of a flame.

[0036] The connecting portion is a structural component, but it can also have other functions, such as transmitting the signal obtained in the measurement area. The connecting portion is to be understood as the portion of the probe other than the measurement area. An example of a connecting portion is the probe body with the wires or communication elements for transmitting the measurement signal. Another example of a connecting portion is a portion of the head body, where the head includes the measurement area and a different component that is cooled according to the present invention and is different from the measurement area. To ensure a fast response of the probe, the connecting portion does not need to be a complete component or piece, but rather a portion that is subjected to different temperature conditions than the measurement area of ​​the probe during operation.

[0037] The measurement region is located in or near the area where the flame is operatively positioned during combustion. This allows for the measurement of flame temperature, an estimate of flame temperature, or a parameter indicative of thermal conditions. An example of a parameter indicative of thermal conditions is a probe that provides a potential difference in response to temperature or temperature changes. Any physical components of the probe supporting the measurement region will also be at high temperatures. This results in thermal inertia, which means that sudden temperature changes, such as those caused by flame extinction, cannot be detected instantaneously in the signal provided by the temperature measurement region, but rather over a period of time that may be too long for safety requirements. The very slow response of the signal to the temperature value of the measurement region prevents the fuel feed valve from closing in a timely manner.

[0038] However, according to the first aspect of the present invention, the probe's connecting portion is housed in an air manifold. The interior of the air manifold contains fresh air, even before it meets the fuel. In this configuration, the fresh air flow is in direct contact with the probe's connecting portion, a highly efficient form of heat transfer that tends to reduce the temperature of the probe's connecting portion as quickly as possible.

[0039] Thus, when the flame goes out, the temperature measuring area attached to the cooled connection portion reduces its temperature by conduction, giving a response in the probe output signal with a faster response time, which response shows the actual temperature drop.

[0040] It has been shown experimentally that this configuration allows response times well below the one second maximum time imposed by equipment safety regulations.

[0041] Even in the embodiment comprising two probes under these conditions, the manufacturing costs are very low for a solution based on a temperature sensor that is not based on the flame radiation index.

[0042] In any of the embodiments according to the preceding disclosure, the probe is a thermocouple.

[0043] A thermocouple is a device that uses two dissimilar metals to create a potential difference based on the temperature of one metal and the other. In the case of a thermocouple, the dissimilar metals are brought together so that a potential difference appears at the junction. This isn't the only configuration; the metals can be at different points under different thermal conditions.

[0044] In the context of the present invention, two types of thermocouples will be distinguished, in the first type of thermocouples, the measurement takes place in a measuring region located at the probe tip and in which the response in the form of a potential difference represents the absolute temperature at which the tip is located.

[0045] A second, less expensive type of thermocouple has a first piece of metal in the measuring region in the probe tip and a second piece of metal at a reference point in the connecting portion, away from the measuring region, which we will call the cold spot.

[0046] In the second case, although the measurements do not establish an absolute temperature measurement, they provide a signal representative of the thermal conditions in the vicinity of the flame, which signal depends, among other factors, on the temperature difference between the measurement area and the cold spot.

[0047] Then, in any embodiment according to the aforementioned disclosed embodiments, the probe is a thermocouple, the temperature measurement area of ​​the probe is at the bimetallic junction of the thermocouple, and the connecting portion of the probe is at least a portion of the metal connection portion connected to the bimetallic junction of the thermocouple.

[0048] This embodiment is based on a first type of thermocouple.

[0049] As previously mentioned, a thermocouple according to this first type is a probe comprising a bimetallic junction adapted to provide a signal responsive to temperature.

[0050] This signal is a potential difference of greater or lesser magnitude, depending on the temperature of the bimetallic connection. The signal is transmitted to the connection via conductive elements. These elements are also good thermal conductors and are part of the connection so that, in operating mode, this part is exposed to the burner supply air flow.

[0051] Thus, when the burner is in operating mode, the temperature of the bimetallic joint is close to the flame temperature. When the flame goes out, the burner feed air is cold and comes into contact with the connection part, which is also cold and closer to the ambient temperature than the measurement area, so that once the flame goes out, the temperature of the connection part causes a rapid cooling of the bimetallic joint by the conductive element that keeps the bimetallic joint and the connection part connected.

[0052] An embodiment according to any of the disclosed embodiments and using the second type of thermocouple as the probe, wherein the probe is a thermocouple comprising two dissimilar metal parts, and wherein a measurement region of the probe comprises one dissimilar metal part and the other dissimilar metal part is at a reference cold spot located in a connection portion of the probe, wherein the probe is adapted to provide a signal amplitude responsive to at least a temperature difference between the temperatures of the two dissimilar metal parts.

[0053] According to this thermocouple structure, the signal amplitude is responsive to the temperature difference between two parts of the probe, namely the measurement area, which is operatively located near or in the flame, and the cold spot, which is operatively located in the connecting part and is cooled by the fresh air flowing in the air manifold.

[0054] In this embodiment, when the flame goes out, the temperature of the measurement area is cooled and the temperature of the cold spot is also cooled. Because the cold spot is cooled by the fresh air flowing in the air manifold where the cold spot is located, the temperature difference increases in the first stage and tends to zero over time.

[0055] Flame extinction can be detected in several ways. According to a first criterion, since the change in the signal is proportional to the temperature difference, it exceeds a predetermined threshold in absolute value.

[0056] The threshold is positive and the smaller the threshold, the smaller the change allowed. The threshold is positive because the change from the reference value is measured using an absolute value function which is always positive.

[0057] However, the same standard 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 made to a threshold value, but rather to values ​​above or below a reference value. However, these alternative expressions are considered equivalent in all cases.

[0058] According to a second criterion, since the derivative of the signal with respect to time, or an estimate of such a derivative, is proportional to the temperature difference, it varies in absolute value above a predetermined threshold.

[0059] In the third criterion, the first and second criteria are evaluated based on a signal proportional to the temperature difference, and this criterion first identifies a change that determines the need to act on the command valve to shut off the fuel gas.

[0060] In any of the embodiments according to the aforementioned disclosure, the probe has an elongated shape, and the temperature measurement area is located at one end of the probe.

[0061] The elongated configuration of the probe allows installation of the probe in two different orientations:

[0062] - the probe is perpendicular to the wall of the air manifold and the measurement area is subject to the flow entering through the air outlet of the air manifold for admitting air into the combustion chamber, or,

[0063] The probe is tilted relative to the wall of the air manifold so as to position the measurement area unaffected by the flow entering through the air outlet of the air manifold for admitting air into the combustion chamber.

[0064] These two options can be used for any of the disclosed embodiments, in particular for the first type of thermocouple and the second type of thermocouple.

[0065] According to a preferred example, which applies to all described examples, the air manifold houses a fuel gas manifold, wherein the air manifold has a flat or convex wall. The flat or convex wall is positioned with an air opening through which fuel gas is introduced using a nozzle or injector (both terms will be used). The fuel gas manifold housed within the air manifold positions the nozzle adjacent to an inner area of ​​the flat or convex wall of the air manifold. In a preferred example, the fuel gas manifold is formed from at least two pieces, which are preferably stamped metal sheets that are joined together. The two pieces extend along a flat or convex main reference surface. According to one example, the fuel gas manifold has openings and does not cover the entire main reference surface. The probe preferably passes through one of these openings, and the vertical or inclined direction is relative to the main reference surface.

[0066] The first option is optimal for a first type of thermocouple, wherein the measuring area is affected by air flow, and the second option is optimal for a second type of thermocouple, wherein the measuring area is not affected by air flow.

[0067] These two positions mean that the long configuration allows three probe positions to be distinguished in a small space:

[0068] a temperature measurement area which is operatively positioned on one side of the combustion chamber inside or close to the area in which the flame is fixed;

[0069] - a connecting portion positioned inside the air manifold; and

[0070] A connection end for obtaining a measurement signal, which is positioned outside the air manifold and can be used for connection to a control device.

[0071] In any of the embodiments according to the preceding disclosure, the fuel gas manifold is housed within the air manifold.

[0072] The configuration in which the fuel gas manifold is housed within the air manifold is a very efficient configuration for positioning at least one fuel gas nozzle or injector on the side of a wall of the air manifold, wherein the wall of the air manifold defines the boundary between the interior of the air manifold and the combustion chamber.

[0073] When the fuel gas manifold includes multiple injectors or nozzles, these are distributed across the surface of the fuel gas manifold, near the inner surface of the air manifold wall. This allows fuel gas to be injected into the combustion chamber through the openings in the air manifold, while also allowing the injected air flow to intersect with the fuel gas just before it enters the combustion chamber. The resulting burner is thus a flashback-resistant burner.

[0074] In an embodiment according to the aforementioned disclosed embodiment, at least one fuel gas nozzle injects fuel gas through at least one air outlet, and wherein a gap is present between the fuel gas nozzle and the air outlet to allow passage of air.

[0075] According to this embodiment, the air outlet into which the fuel gas is injected by means of a nozzle or injector has a gap between the outlet and the nozzle. According to a preferred embodiment, the gap is shown according to the radial direction with reference to the axis of the nozzle.

[0076] According to an example, when the embodiment includes multiple air outlets and multiple nozzles, air ducts are provided between the inner wall of the air manifold and the fuel gas manifold wall. These ducts facilitate air distribution near each nozzle. These air ducts also serve as reinforcing ribs for the surface of the air manifold facing the combustion chamber.

[0077] This gap allows air to enter the combustion chamber, but causes the air to flow against the flow of fuel gas, preferably in a direction transverse to the gas flow, which promotes integration between the two.

[0078] In an embodiment according to any of the aforementioned disclosed embodiments, the fuel gas manifold comprises at least two plates which are joined so as to construct a flat collector or a collector extending along a convex surface.

[0079] A very efficient combustion mode is one in which the flame has a flat configuration or at least extends along the surface. The process of combining the air and fuel gas occurs on one side of the surface feeding the flame, and after combustion, the hot gases carry the heat to the rest of the combustion chamber, where there is an exchange device that transports the heat to the final application site.

[0080] It has been shown that an easily constructible configuration is based on the joining of two plates, preferably die-cut and stamped, which together form a flat manifold or a manifold extending along a convex surface.A special case of a convex surface is a spherical surface portion.

[0081] In an embodiment according to any of the before-disclosed embodiments, the air manifold comprises a wall having the air outlet, the wall being a flat wall or a wall extending along a convex surface.

[0082] Among other parameters, the walls of the air manifold with air outlets define the shape and positioning of the flame. A flat wall or a wall extending along a convex surface allows the burner's usable surface to be optimized when the burner is installed in the opening of the combustion chamber. In a particular embodiment, the flat wall or the wall extending along a convex surface is located within an area surrounded by a seat adapted to close the combustion chamber's opening when the burner is operatively installed in the combustion chamber.

[0083] In an embodiment according to any of the aforementioned disclosed embodiments, the probe penetrates at least a wall of the air manifold comprising the air outlet.

[0084] The probe is partially located inside the air manifold and the end with the area for temperature measurement is located in the space of the combustion chamber.According to this embodiment, the probe passes through at least the wall of the air manifold containing the air outlet.

[0085] This arrangement has the advantage of producing a very compact and reactive device and is particularly useful when the configuration of the area in which the nozzles are distributed has a configuration extending according to a plane or according to a convex surface, since a position perpendicular or close to perpendicular to this surface allows a very rapid cooling effect.

[0086] In an embodiment according to the previously disclosed embodiment, the probe passes through the fuel manifold.

[0087] The fuel manifold configurations described are either flat or convex. This does not mean that the entire manifold covers the flat or convex area, but rather that the manifold positions the nozzles according to a flat or convex spatial distribution. That is, depending on the embodiment, the fuel manifold is formed by, for example, radially distributed conduits covering the area where the nozzles are located. With this configuration, the probe's "passing through" the fuel manifold allows for two interpretations: either the probe passes from one side to the other, for example, by exploiting gaps or openings left by radial conduits, or the probe actually passes through the wall of the fuel gas, in which case the inlet and outlet openings in the fuel manifold need to be sealed and the section of the probe housed within the fuel manifold needs to be thermally insulated. The first scenario is the preferred one.

[0088] According to this embodiment, the probe passes through the fuel manifold, preferably through an opening, and also through at least one wall of the air manifold, preferably through an opening.

[0089] According to the specific example that will be described below, not only do the elements involved in combustion extend close to a flat or convex surface, but the entire burner essentially adopts this shape, making the sensors easily accessible from the outside while keeping the two most relevant parts of the interior, namely the connection part and the temperature measurement area, at different temperatures.

[0090] In an embodiment according to any of the previously disclosed embodiments, the burner further comprises a processor,

[0091] a processor in communication with the probe and with a command valve for feeding the fuel gas manifold, the command valve being adapted to shut off the flow of fuel gas when commanded, and

[0092] wherein the processor is further adapted to receive a signal from the probe providing a measurement responsive to temperature and to send a signal to the command valve to shut off the flowing fuel gas inlet if:

[0093] a) the absolute value of the measured signal, or

[0094] b) the absolute value of the first derivative with respect to time, or

[0095] c) Either of the first two options a) or b).

[0096] These three options apply to any probe type.

[0097] Option a) is preferably used when the probe is a first type of thermocouple and when the measured value in response to temperature is a temperature value at the measuring area of ​​the probe, and option b) is preferably used when the probe is a second type of thermocouple and when the measured value in response to temperature is a measurement value of the temperature difference between the measuring area of ​​the probe and a cold area.

[0098] According to this embodiment, the burner is equipped with a safety device that allows for a response to dangerous situations, such as flame failure. The signal generated by the probe is transmitted to a processor, which compares the value of the signal representing the temperature in the temperature measurement area with a threshold value. If the temperature signal falls below the threshold value, the processor sends a signal to the burner commanding the closure of the fuel supply valve.

[0099] The closing time is not instantaneous, but the configuration according to one of the described examples allows for a very rapid response when a signal is generated that indicates a temperature change due to low thermal inertia. The processor responds to this change in the input signal by closing the valve in a very short time, significantly less than the seconds required by regulations.

[0100] In an embodiment according to the aforementioned disclosed embodiment, the processor is further adapted to send a signal to the command valve to shut off the flowing fuel gas inlet if the signal representing the temperature is above a second threshold value.

[0101] According to this embodiment, the processor is adapted to react by closing the fuel gas flow inlet when it detects flame failure and when there are combustion conditions resulting in very high temperatures exceeding predetermined conditions. This is also a dangerous condition that must be controlled, and according to this embodiment, the processor also responds by closing the command valve.

[0102] A second aspect of the 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 mounted and adapted to be coupled to an orifice of the combustion chamber.

[0103] The burner according to any of the preceding embodiments may further comprise two probes for redundant measurement, which may have two thermocouples of one type, two thermocouples of a second type, or a first probe of one type and a second probe of a second type.

[0104] A system burner embodiment is also provided, the system being like the system described above, wherein the system further comprises an emissions probe adapted to measure the concentration of at least one component of the exhaust gas, and wherein the processor is further adapted to control the burner, preferably in a closed loop, such that in all cases of operation with excess oxygen, the air / fuel ratio measured by volume is operationally in the range of [1.05, 2.1], and more preferably in the range of [1.0, 1.8], and more preferably in the range of [1.1, 1.7], and more preferably in the range of [1.2, 1.6], and more preferably in the range of [1.3, 1.5], and more preferably about 1.4, preferably the air / fuel ratio being constant for any intake flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0105] These and other features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments thereof, given by way of illustrative and non-limiting examples only, with reference to the accompanying drawings.

[0106] Figure 1 A first embodiment of a burner comprising an air pulse device and a fuel gas feed management valve is shown in perspective.The burner is mounted in an orifice of a combustion chamber.

[0107] Figure 2The same embodiment as in the previous figures is shown in perspective, wherein the burner, fuel gas valve and drive are separated from the combustion chamber to allow visual access to both the combustion chamber orifice and the rest of the elements.

[0108] Figure 3 The same embodiment as in the previous figures is shown in perspective, with the valves and pipes for the fuel gas supply and the air pulse device removed, allowing the view of the burner to be enlarged.

[0109] Figure 4 The same burner is shown in perspective with the combustion chamber removed.

[0110] Figure 5 The same burner as in the previous figures is shown in perspective from the opposite side, allowing visual access to the air outlet and fuel gas nozzle outlet.

[0111] Figure 6 A cross-section of the previous figures is shown, allowing visual access to the interior of the air manifold and the interior of the fuel gas manifold

[0112] Figure 7 The cross-section of the previous figure is shown using a different perspective view, which moves the probe out of the burner to allow visual access to all parts of the probe.

[0113] Figure 8 Shown Figure 7 , but with the probe in its final position.

[0114] Figure 9 Shown with Figure 7 The elements shown in FIG. 5 are the same elements and the same cross-section, but the probe is in its final position. DETAILED DESCRIPTION

[0115] As will be appreciated by those skilled in the art, aspects of the present invention may be embodied as a burner flashback proof gas burner adapted for coupling to an orifice.

[0116] Figure 1 An embodiment of a flashback-proof gas burner B is shown, comprising a combustion chamber 5. The combustion chamber 5 is a chamber in which a combustion reaction takes place in the form of a flame. Heat is generated in the combustion reaction, which is transferred to a destination of the energy, for example via a heat exchanger, depending on the final application.

[0117] In this embodiment, the combustion chamber 5 has an orifice 5.1 to which the burner B is coupled and fixed. This configuration not only allows maintenance of both the burner B and the elements accessible from inside the combustion chamber 5, but also allows, for example, replacement of the entire burner B. Such replacement may be necessary if a burner B configured for a different type of fuel is required.

[0118] The burner B according to this embodiment is configured to burn a gas fuel including hydrogen, and more specifically, including only hydrogen.

[0119] The burner B of this embodiment is a flashback-proof gas burner and therefore has an air inlet port 1 , an oxidant, and a gas fuel inlet port 2 . Figure 1 At the lower part of the figure is shown an air pulse device 4 for drawing air from the atmosphere into the combustion chamber 5, thereby applying an overpressure above atmospheric pressure. The air leaving the pulse device 4 is led to the interior of the air manifold 6 through an air duct 6.1.

[0120] exist Figure 1 Also shown in the lower part of the diagram is a command valve 8 which controls the flow of fuel gas. The fuel gas either comes from a source under pressure or is generated by means of pulses of fuel gas. For the sake of clarity, the fuel gas source is not shown in the drawings.

[0121] Figure 2 It is a perspective view of the same embodiment, in which the burner B is held together with the command valve 8 and the air pulse device 4, and this group of elements is separated from the combustion chamber 5 to allow viewing of the orifice 5.1 of the combustion chamber 5 for engaging the burner B.

[0122] The formation of the flame in the burner B takes place immediately behind a circular plate which engages the orifice 5.1 of the combustion chamber 5, which according to this embodiment is also of circular configuration. Furthermore, according to this embodiment, the flame also has a generally flat configuration and projects heat into the combustion chamber 5, which in this embodiment comprises a heat exchanger 5.2, which is shown as an annular stack through the orifice 5.1.

[0123] exist Figure 3 , both the command valve 8 and the air pulse device 4 are removed to allow observation of the burner B mounted on the combustion chamber 5 in an enlarged view.

[0124] Figure 4 The same burner B is shown after the combustion chamber 5 has been removed.

[0125] Figures 1 to 4Also shown are the external parts of the two probes 7, primarily the ends that allow for connection, which receive the signals measured by the probes 7 and allow for determination of a measurement of the flame temperature or of the area close to the flame. The use of two probes 7 is a safety measure for redundant measurement of the same parameter.

[0126] It is at this end that the two probes 7 are joined with a connection that transmits the signals to a processor, not shown, which is responsible for processing the signals and responding to the measured values, and in particular to changes in the measured values.

[0127] The command valve 8 allows burner B to be shut down, for example because the command valve 8 receives a signal from the processor in response to a flame failure event.

[0128] Fuel gas is led from the command valve 8 to the fuel gas manifold 3 by means of a fuel gas conduit 3 . 1 .

[0129] Burner B is a flashback-proof gas burner, ensuring that the fuel gas and the combustion aid meet immediately upon entering the combustion chamber 5, and furthermore, meet in a cross-flow pattern. To achieve this condition, the fuel gas manifold 3 is housed within the air manifold 6, and both manifolds 3 and 6 have similar configurations. In this embodiment, the fuel gas manifold 3 has a flat configuration, at least in its surface, where a plurality of fuel gas nozzles 3.2 are distributed for injecting fuel gas jets into the combustion chamber 5.

[0130] Figure 5 A perspective view of a burner B is shown, wherein the observation point is located at the burner relative to Figures 1 to 4 This view shows the thermal insulation 10 which is located inside the orifice 5 . 1 of the combustion chamber 5 , thus ensuring a heat-protective closure.

[0131] This figure also shows the electrode 9 that causes the ignition of the flame, the end of the electrode 9 being placed in a position close to the area where the flame is operatively fixed to the burner.

[0132] In the interior of thermal insulation 10, a plurality of outlets are shown, corresponding to the outlet openings of the plurality of fuel gas nozzles 3.2 for introducing fuel gas into the interior of combustion chamber 5. These outlets are air outlets 6.2, i.e., outlets through which air can exit, as the ends of fuel gas nozzles 3.2 do not completely enclose the surrounding air outlets 6.2. Air outlets 6.2 are located in the wall of air manifold 6. Therefore, in this embodiment, fuel gas manifold 3 and air manifold 6 have a flat configuration, as fuel gas nozzles 3.2 must be located close to and within air outlets 6.2 located in the wall of air manifold 6.

[0133] In other words, there is a gap between the fuel gas nozzle 3.2 and the air outlet 6.2 located within the fuel gas nozzle 3.2. This gap determines the distance that air or combustion aid must travel to reach the surrounding area of ​​the fuel gas jet ejected by the fuel gas nozzle 3.2. Under these conditions, the air inlet occurs in a radial direction that is approximately transverse to the direction of the fuel gas inlet. This situation causes the flows to intersect and combine in a very small space.

[0134] We will return to Figure 8 To observe the cross-section of this configuration.

[0135] Figure 6 Shown Figure 5 A cross-sectional view of the example shown in Figure 5 The flat configuration of the fuel gas manifold 3 and how it is housed inside the air manifold 6 can be observed in FIG. 1 , wherein the walls of the air manifold 6, namely the wall where the air outlet 6.2 is located, are approximately flat. However, the wall of the air manifold 6.2 adjacent to and parallel to the wall of the fuel gas manifold 3 has reinforcing ribs that also create channels for air to enter the area around the air outlet 6.2 to reduce pressure drop.

[0136] Figure 7 Another cross-sectional view is shown, wherein the probe 7 is shown in an exploded perspective view. Figure 9 The same view is seen in FIG, where the probe 7 is now in its final position. The cross-sectional view has removed the half of the burner B in which the second probe 7 is located.

[0137] Figure 8 yes Figure 9 , and shows how the probe 7 is positioned relative to each of the interior spaces of the burner B, in particular the air manifold 6 and the fuel gas manifold 3.

[0138] To extract the measurement signal, probe 7 has one connection at the measurement region 7.2 and a second connection at the connection region, the cold spot. The signal is responsive to the potential difference between the two points. In this embodiment, probe 7 is a second-type thermocouple, where the signal is generated in the form of a potential difference in response to certain temperature conditions at the measurement region 7.2 and the cold spot.

[0139] Between the two ends, a sleeve-shaped section is shown in an elongated configuration, allowing for threaded connection to the rear wall of the air manifold 6, thereby establishing a sealed joint. Also shown is an elongated section, which in this embodiment is metal, through which the signal is transmitted. This extension, which in this embodiment is metal, is a good thermal conductor, and the portion conducting the signal is also a good signal conductor. This extension should be interpreted as any intermediate section between the connecting portion 7.1 and the two ends of the probe 7 that is capable of thermally conducting to the temperature measurement area 7.2. In this embodiment, the connecting portion 7.1 also serves as the cold point of the thermocouple.

[0140] Reference Figure 8 , the connection portion 7.1 is located inside the space formed by the air manifold 6, so that this connection portion 7.1 will undergo heat transfer phenomena by convection when interacting with the air circulating inside the air manifold 6. Therefore, except for the changes that may be caused by the pressure increase of the air pulse device 4, the temperature of the connection portion 7.1 is close to the ambient temperature.

[0141] Accordingly, temperature measurement area 7.2 is located at one end, where probe 7 at least passes through the wall of air manifold 6 and is then in direct contact with the interior of combustion chamber 5. To reach this location within combustion chamber 5, probe 7 also overcomes the location of fuel gas manifold 3 by passing through fuel gas manifold 3, or more safely, by passing between channels or ribs that carry fuel gas, leaving free space or openings between such channels or ribs, such as those that allow the passage of probe 7. This form of passage without passing through the interior of fuel gas manifold 3 prevents high temperatures from being transferred to the interior of the space that operatively contains the fuel gas, thereby reducing risks.

[0142] As disclosed above Figure 5 and Figure 6 As shown in , the temperature measurement area 7.2 emerges from the surface formed by the wall of the air manifold 6, is in direct contact with the interior of the combustion chamber 5 and protrudes a certain distance, which allows the temperature measurement area 7.2 to be at least close to the flame.

[0143] The measured value of the temperature measurement area 7.2 will be the flame temperature or a temperature close to the flame temperature.

[0144] When the flame goes out, the temperature of temperature measurement area 7.2 drops because heat in this area is transferred both to the surrounding environment and along probe 7, particularly through connection 7.1. The cold spot at the connection cools more rapidly due to the air flow within the air manifold, so the temperature difference increases for a first period of time and then tends to decrease. This rapid change during the first period of time is detected, and a signal is generated with a very short response time sufficient to initiate a response by shutting off the fuel gas supply.

[0145] In this embodiment, the signal representative of the temperature difference and proportional to the temperature difference, and in particular the signal of such rapid evolution due to the extinction of the flame, is processed by a processor so that, upon comparing the signal with a threshold value, evaluating the absolute value of the comparison and verifying that the signal has exceeded the threshold value, the processor sends a signal commanding the closing of the command valve 8 and therefore cutting off the fuel gas supply.

[0146] This rapid response prevents the accumulation of fuel gas within the combustion chamber 5 which could lead to an explosion.

Claims

1. A flashback-proof gas burner (B), adapted to be coupled to an orifice (5.1) of a combustion chamber (5), adapted for combustion of a fuel gas comprising hydrogen, comprising: 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 means of a fuel gas conduit (3.1), the fuel gas manifold (3) comprising at least one fuel gas nozzle (3.2), the at least one fuel gas nozzle (3.2) being arranged for injecting fuel gas into the combustion chamber (5) when the burner (B) is operatively coupled to the combustion chamber (5); an air manifold (6) in fluid communication with the air inlet port (1) by means of an air duct (6.1), the air manifold (6) comprising at least one air outlet (6.2), the at least one air outlet (6.2) being configured to supply air in the vicinity of the gas nozzle (3.2) for operatively producing a combination of the air and the fuel gas in the combustion chamber (5) and out of the anti-flashback gas burner (B); in, The burner (B) comprises a probe (7) suitable for sensing temperature, wherein the probe (7) comprises a connecting portion (7.1) and a temperature measuring area (7.2); The connecting portion (7.1) of the probe (7) is housed in the air manifold (6), and the temperature measurement area (7.2) is located at or near the area where the flame is located when the gas burner (B) is in operating mode.

2. The burner according to claim 1, wherein The probe (7) is a thermocouple, the temperature measurement area (7.2) of the probe (7) is a bimetallic joint of the thermocouple, and the connecting portion (7.1) of the probe (7) is at least a portion of a metal connecting portion of the bimetallic joint connected to the thermocouple.

3. The burner according to claim 1, wherein The probe (7) is a thermocouple comprising two dissimilar metal parts, and wherein the measurement region (7.2) of the probe (7) comprises one dissimilar metal piece and the other dissimilar metal piece is at a reference cold spot located in the connecting portion (7.1) of the probe (7), wherein the probe (7) is adapted to provide a signal amplitude responsive to at least a temperature difference between the temperatures of the two dissimilar metal pieces.

4. A burner according to any one of the preceding claims, wherein The probe (7) has an elongated shape, and the temperature measurement area (7.2) is located at one end of the probe (7).

5. A burner according to any one of the preceding claims, wherein The fuel gas manifold (3) is accommodated in the air manifold (6).

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

7. A burner according to any one of the preceding claims, wherein The fuel gas manifold (3) comprises at least two plates which are joined to construct a flat collector or a collector extending along a convex surface.

8. A burner according to any one of the preceding claims, wherein The air manifold comprises a wall having the air outlet (6.2), the wall being a flat wall or a wall extending along a convex surface.

9. The burner according to any one of claims 2, 3, 4 and claim 8, wherein The probe (7) is positioned perpendicular to the wall of the air manifold (6), and the measurement area (7.2) is affected by the flow entering through the air outlet (6.2) of the air manifold (6) for letting air into the combustion chamber.

10. The 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) so as to position the measurement area (7.2) unaffected by the flow entering through the air outlet (6.2) of the air manifold (6) for letting air into the combustion chamber.

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

12. Burner according to the preceding claim, wherein The probe (7) passes through the fuel manifold (3).

13. A burner according to any one of the preceding claims, wherein The burner also includes 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, and The processor is further adapted to receive a signal from the probe (7), the signal providing a measurement result responsive to the temperature, and to send a signal to the command valve (8) to close the fuel gas inlet when a change in the following exceeds a threshold: a) measure the absolute value of the signal, or b) the absolute value of the first derivative with respect to time, or c) either of the first two options a) or b), and Optionally, the processor is further adapted to send a signal to the command valve (8) to close the fuel gas inlet when the signal representing the temperature is higher than a second threshold value.

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

15. The burner system of claim 14, wherein: The burner system further comprises an exhaust gas 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 closed loop, such that in all cases of operation with excess oxygen, the air / fuel ratio measured by volume is operationally in the range of [1.05, 2.1], and more preferably in the range of [1.0, 1.8], and more preferably in the range of [1.1, 1.7], and more preferably in the range of [1.2, 1.6], and more preferably in the range of [1.3, 1.5], and more preferably about 1.4, preferably the air / fuel ratio being constant for any intake air flow rate.

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