Method of operating an adjustment burner

Abstract

The present invention relates to a method for operating a surface-stabilized fully premixed gas burner, the burner being configured to modulate between minimum load and full load, the ratio of full load to minimum load being at least 4. The method includes supplying a premix of combustible gas and air to the burner at an air-to-combustible gas ratio, the combustible gas supplied to the burner comprising at least 20 volume percent hydrogen. In the method, a mechanism is configured to set the air-to-combustible gas ratio of the premix supplied to the burner when the burner is operated at minimum load to be at least 20 percent higher than the air-to-combustible gas ratio of the premix supplied to the burner when the burner is operated at full load.

Description

Technical Field

[0001] The present invention relates to a regulated surface-stabilized gas premixing burner, and more particularly to the technical field of a method for operating a burner in which a combustible gas contains at least 20 volume percent hydrogen.

Background Art

[0002] The adjustment of gas burners is becoming increasingly common. This means that the load of the burner can be varied over a fairly wide range. For example, when the ratio of the maximum burner load to the minimum burner load is 4 or more.

[0003] Gas burners using natural gas have become established. The use of such burners has been criticized for emitting carbon dioxide. The use of a gas burner using 100% hydrogen or a mixture of natural gas and hydrogen seems to be an interesting solution for reducing carbon dioxide emissions. However, hydrogen (or a gas fuel with a high hydrogen content) has a different combustion behavior from other hydrocarbon gases such as natural gas and propane. When the combustion behavior is different, many problems occur. For example, the burner is prone to flashback of the flame.

[0004] A mixture of a combustible gas and air is supplied to a surface-stabilized premixed gas burner. The performance of the burner is determined by the air-to-combustible gas ratio. Sufficient air needs to be supplied for complete combustion (such as reducing the emission of carbon monoxide). In order to increase the heat transfer efficiency in a heat cell where a surface-stabilized gas burner is used, it is necessary to ensure that the amount of air is not too much. Therefore, it is known to operate a natural gas burner at a predetermined constant air-to-combustible gas ratio through a pneumatic gas valve or through a control mechanism such as measuring the ionization current of the burner flame.

[0005] DE3937290A1 discloses, for example, controlling the air and / or fuel supply to a burner heating appliance in order to maintain an optimal ratio. A flame ionization probe measures the flame conductivity and uses the difference between the measured conductivity and a reference value to adjust, for example, the gas valve and / or the fan speed.

[0006] US2008 / 318172A proposes a method for adjusting an ignition device taking into account the temperature and / or the burner load, especially when using a gas burner. This method includes adjusting the temperature generated by the ignition device using a certain characteristic. A certain characteristic indicates a range of values corresponding to a desired temperature that depends on a first parameter corresponding to the burner load, and when representing that characteristic, a second parameter, preferably the ratio of the actually supplied air to the amount of air theoretically required for optimal stoichiometric combustion, defined as the air ratio (lambda), is constant.

[0007] WO2014 / 060991A1 discloses a device for adjusting and controlling combustion in a fuel gas burner that can maintain an optimal value of the air / gas ratio in order to obtain optimal emissions of carbon dioxide, carbon monoxide, and nitrogen oxides, regardless of the type of gas used by the burner and the power supplier. This device includes the following components integrated with each other. A combustion gas / fuel gas mixing pipe equipped with a Venturi mixer and corresponding to which a fuel gas supply duct opens, a means for adjusting the flow rate of the fuel gas, a fan at least partially housed in the mixing pipe, a burner arranged downstream of the fan, a safety system based on the detection of the flame present in the burner, and an electronic control unit of the device belonging to the device. This device includes a temperature probe arranged on the inner surface of the burner, a valve for adjusting the fuel gas flow rate in the duct, which belongs to the control means and is mechanically controlled by an actuator, and an electronic card electronically connected to the probe, the fan, and the actuator.

Summary of the Invention

[0008] According to the present invention, there is provided a method for operating a surface-stabilized fully-premixed gas burner, the burner being configured to be adjusted between a minimum load and a full load, and the ratio of the full load to the minimum load being at least 4.

[0009] The method includes the following steps. - Supplying a pre-mixture of a combustible gas and air to the burner at an air-to-combustible gas ratio, wherein the combustible gas supplied to the burner contains at least 20 volume percent hydrogen. - When the burner is operating at the minimum load, the air-to-combustible gas ratio of the pre-mixture supplied to the burner is set by a mechanism to be at least 20 volume percent higher than the air-to-combustible gas ratio of the pre-mixture supplied to the burner when the burner is operating at the full load.

[0010] The burner is, for example, part of a burner system and includes further components for operating and controlling the burner. Optionally, the mechanism is part of the same burner system as the burner.

[0011] The burner is provided (specifically configured) to be adjustable between a minimum load and a full load. The ratio of the full load to the minimum load is at least 4, for example greater than 4, more preferably greater than 5, more preferably greater than 7, and even more preferably greater than 10.

[0012] According to the present invention, the air-to-combustible gas ratio of the pre-mixture supplied to the burner is set to be at least 20 percent higher at the minimum load of the burner than the air-to-combustible gas ratio supplied to the burner at the full load. There is a mechanism for correctly setting the air-to-combustible gas ratio.

[0013] As an example, when the air-to-combustible gas ratio at the full load of the burner is 1.3, it means that the air-to-combustible gas ratio at the minimum load is at least 1.20 * 1.3, that is, at least 1.56.

[0014] The "air-to-combustible gas ratio" means the ratio of the amount of air to the amount of combustible gas in a premixed mixture of air and combustible gas with respect to the amount of air theoretically stoichiometrically required for the complete combustion of the combustible gas.

[0015] The "burner load" (expressed in kW) means the amount of energy supplied to the burner per unit time. The amount of energy is equal to the mass flow rate multiplied by the calorific value of the combustible gas per unit mass.

[0016] An advantage of the present invention is that while flashback of the flame is prevented under normal operating conditions, the impact on the overall efficiency of a heat exchanger using a surface-stabilized gas premixing type burner is very small. A surface-stabilized complete premixing type gas burner supplied with hydrogen in the combustible gas tends to cause flashback of the flame when the burner load is low. This is thought to be due to the high combustion rate of hydrogen, which is much faster than the combustion rate of natural gas. The method of the present invention significantly reduces or eliminates the probability of flashback by increasing the air-to-combustible gas ratio at a lower load level. Thus, at a lower load level, the outlet velocity of the premixed gas flowing out of the burner deck increases, the flame speed decreases, and the burner deck is cooled. These effects act synergistically to reduce the possibility of flashback of the flame. Since the air-to-gas ratio increases only at a low load level, the efficiency at a high load level of the connected heat exchanger that transfers heat from the flue gas generated by the burner to another medium (such as water) remains at a high level. Due to the large amount of excess air in the premixed supply, the efficiency is slightly lower only when the load is low. However, when the efficiency is averaged over the total amount or mass of the combustible gas converted by the burner over a certain period, the impact of the lower efficiency at a lower burner load is very low.

[0017] Preferably, the combustible gas supplied to the surface-stabilized fully premixed gas burner contains at least 40 volume percent hydrogen, more preferably at least 60 volume percent hydrogen. More preferably, it contains at least 80 volume percent hydrogen. Optionally, the combustible gas supplied to the surface-stabilized fully premixed gas pre-mixing burner contains at least 95 volume percent hydrogen, at least 98 volume percent hydrogen, or from 95 volume percent to 98 volume percent hydrogen. More preferably, the combustible gas is 100 percent hydrogen, excluding impurities and / or any odoriferous substances and / or colorants.

[0018] Optionally, the burner used in the method according to the invention includes a burner deck on which combustion is stabilized when the burner is operating. For example, the burner deck is or includes a perforated metal plate. For example, the burner deck is or includes a cylindrical perforated metal plate. The premix of air and combustible gas flows from the inside of the cylindrical perforated metal plate through the holes of the cylindrical perforated metal plate to the outside, where it is combusted. Optionally, one end of the cylindrical perforated metal plate is closed by a metal end cap.

[0019] Optionally, the burner includes a perforated plate (i.e., a plate with a plurality of holes), for example, a perforated metal plate that is entirely or partially covered with a fibrous metal material, for example, a woven or knitted fibrous metal material. For example, fibrous materials known in the art as "NIT" can be used. For example, the fibrous metal material completely or partially covers the area of the effective plate containing the holes.

[0020] Although this is an optional feature, the burner includes a perforated plate, for example a perforated metal plate, and the perforated plate has holes only in a part of its surface, for example only in the area of the plate that forms the axial end of the burner or the axial end of the burner deck of the burner. Although this is an optional feature, a fibrous metal material, for example a woven or knitted fibrous metal material, for example a fibrous material in the art known as "NIT", covers the part of the surface of the perforated plate that contains the holes.

[0021] Although this is an optional feature, the burner has a burner deck that includes gauze. Although this is an optional feature, the gauze is covered with a fibrous metal material, for example a woven or knitted fibrous metal material. For example, a fibrous material in the art known as "NIT" can be used.

[0022] Although this is an optional feature, the burner deck of the burner is or includes a woven or knitted deck, particularly a deck of woven or knitted fibrous metal material.

[0023] Although this is an optional feature, the burner deck is or includes a perforated ceramic plate.

[0024] Although this is an optional feature, in the method according to the invention, the air-to-combustible gas ratio of the premix supplied to the burner is set to be at least 25 percent higher, more preferably 35 percent higher, at the minimum load of the burner than at the air-to-combustible gas ratio supplied to the burner at the full load of the burner. For example, the air-to-combustible gas ratio of the premix supplied to the burner is set to be at least 40 percent higher, optionally 60 percent higher, at the minimum load of the burner than at the air-to-combustible gas ratio supplied to the burner at the full load of the burner.

[0025] Although this is an optional choice, the method according to the present invention is carried out using a burner system comprising a burner, or a fan for supplying air to the burner, or for supplying a premixed mixture of combustible air and gas to the burner. The fan forms part of, for example, a burner load controller.

[0026] Although this is an optional choice, the method according to the present invention is carried out using a burner system or burner according to the present invention.

[0027] In one embodiment of the method according to the present invention, the air-to-combustible gas ratio at average load is less than 10% higher than the air-to-combustible gas ratio at full load. The average load is defined as the average of the minimum load and the full load. Although this is an optional choice, the air-to-combustible gas ratio at average load is less than 5% higher than the air-to-combustible gas ratio at full load.

[0028] In one embodiment of the method according to the present invention, the air-to-combustible gas ratio at average load is at least 5%, preferably at least 10% lower than the average between the air-to-combustible gas ratios at minimum load and full load. The average load is defined as the average of the minimum load and the full load.

[0029] In one embodiment of the method according to the present invention, the air-to-combustible gas ratio of the premixed gas supplied to the burner at full load is less than 1.3, preferably less than 1.25.

[0030] In one embodiment of the method according to the present invention, the air-to-combustible gas ratio of the premixed gas supplied to the burner is set by a mechanism as a predetermined function of the burner load.

[0031] This can be achieved, for example, when the mechanism uses an air pressure gas valve to set the supply rate of combustible gas to the burner in order to set the air-to-combustible gas ratio of the premixed gas supplied to the burner as a defined function of the burner load.

[0032] Although this is an arbitrary choice, a pneumatic gas valve including a spring is used, and at least a partially defined function is determined by one or more characteristics of the spring.

[0033] In one embodiment of the method according to the present invention, air or a premix of combustible air and gas is supplied to a burner or a burner system by a fan (e.g., the fan of a burner load controller), and the amount of air supplied to the burner is measured by a sensor. Alternatively or in addition, the fan speed is used as an indicator of the amount of air supplied to the burner or burner system, or the pressure drop is recorded as a measurement of the amount of air supplied to the burner or burner system. In this embodiment, the amount of combustible gas supplied to the burner is set according to a defined relationship with the amount of air supplied to the burner. For example, an electric control valve can be used to set the amount of combustible gas supplied to the burner.

[0034] In one embodiment of the method according to the present invention, air or a premix of combustible air and gas is supplied to a burner or a burner system by a fan (e.g., the fan of a burner load controller), and the amount of combustible gas supplied to the burner is measured by a sensor. In this embodiment, the amount of air supplied to the burner is set according to a defined relationship with the amount of combustible gas supplied to the burner. For example, fan speed control can be used to set the amount of air supplied to the burner.

[0035] In one embodiment of the method according to the present invention, air or a premix of combustible air and gas is supplied to a burner by a fan (e.g., the fan of a burner load controller), and a value providing information on combustion, flue gas, and / or the mixture from air to gas supplied to the burner is measured by at least one sensor. In this embodiment, this value is used in combination with values indicating burner load, fan speed, and / or the flow rate of air supplied to the burner to set the air-to-combustible gas ratio.

[0036] Although this is an arbitrary choice, in this embodiment, at least one sensor is a temperature sensor or includes a temperature sensor, and the value providing combustion information represents the flue gas temperature or the burner flame temperature.

[0037] Although this is an arbitrary choice, in this embodiment, the burner used in the method according to the present invention includes a burner deck where combustion stabilizes when the burner is operating, at least one sensor is a temperature sensor (e.g., a thermocouple) or includes it, and the value providing combustion information represents the temperature of the burner deck of the burner.

[0038] Although this is an arbitrary choice, in this embodiment, alternatively or additionally, at least one sensor is provided to measure a value representing the oxygen content of the flue gas generated by the burner or a value representing the oxygen content of the pre - mixture of air and combustible gas supplied to a premixed burner.

[0039] In one embodiment of the method according to the present invention, the burner used includes a perforated metal plate for stabilizing the flame.

[0040] The method according to the present invention can be implemented, for example, using a surface - stabilized fully premixed gas premixing burner system according to the present invention.

[0041] The present invention further relates to a surface - stabilized fully premixed gas premixing burner system, the burner system comprising the following. - A burner comprising a burner deck, the burner deck having a plurality of holes. - An air inlet, a combustible gas inlet, and a mixer in communication with the air inlet and the combustible gas inlet, the mixer being configured to mix air and combustible gas to form a pre - mixture of combustible gas and air at an air - to - combustible gas ratio, and the combustible gas inlet being suitable for receiving a combustible gas containing at least 20 volume percent hydrogen. - A burner inlet configured to receive the pre - mixture of combustible gas and air and supply it to the burner. - A burner load controller configured to vary the load of a burner between a minimum load and a full load, wherein the ratio of the full load to the minimum load is at least 4, whereby the burner is adjusted between the minimum load and the full load. - A mechanism configured to set an air-to-combustible gas ratio of a premixed gas of combustible gas and air generated by a mixer, wherein the setting of the air-to-combustible gas ratio of the premixed gas of combustible gas and air is performed at least partially in response to the load of the burner, and the air-to-combustible gas ratio of the premixed gas supplied to the burner when the burner is operating at the minimum load is at least 20 percent higher than the air-to-combustible gas ratio of the premixed gas supplied to the burner when the burner is operating at the full load, as set by the mechanism.

[0042] In the burner of the burner system according to the present invention, preferably, the total surface area of the holes is at most 5 percent of the surface area of the burner deck. Thereby, the burner system can use a combustible gas containing at least 20 volume percent of hydrogen. Combustible gases containing 20 percent or more of hydrogen exhibit quite different behaviors from the normal natural gas used in gas burners. In particular, combustible gases with a high volume percentage of hydrogen (e.g., at least 40 percent, at least 50 percent, at least 80 percent, at least 95 percent, at least 98 percent, between 95 percent and 98 percent, and 100 percent including inevitable impurities) are advantageous by virtue of the total surface area of the holes being at most 5 percent of the surface area of the burner deck.

[0043] The total surface area of the holes exceeds 0 percent of the surface area of the burner deck.

[0044] Optionally, the total surface area of the holes is between 0.5 percent and 5 percent of the surface area of the burner deck, for example, between 1 percent and 5 percent of the surface area of the burner deck.

[0045] Although it is an optional choice, the combustible gas inlet is suitable for receiving a combustible gas containing at least 20 volume percent of hydrogen, and the total surface area of the holes is at most 10 percent of the surface area of the burner deck.

[0046] Although it is an optional choice, the combustible gas inlet is suitable for receiving a combustible gas containing at least 50 volume percent of hydrogen, and the total surface area of the holes is at most 9.5 percent of the surface area of the burner deck.

[0047] Although it is an optional choice, the combustible gas inlet is suitable for receiving a combustible gas containing at least 95 volume percent of hydrogen, and the total surface area of the holes is at most 5 percent of the surface area of the burner deck.

[0048] Although it is an optional choice, the combustible gas inlet is suitable for receiving a combustible gas containing at least 98 volume percent of hydrogen, and the total surface area of the holes is at most 5 percent of the surface area of the burner deck.

[0049] Although it is an optional choice, the combustible gas inlet is suitable for receiving a combustible gas containing 95 to 98 volume percent of hydrogen, and the total surface area of the holes is at most 5 percent of the surface area of the burner deck.

[0050] Although it is an optional choice, the combustible gas inlet is suitable for receiving a combustible gas containing 100 volume percent of hydrogen excluding inevitable impurities, and the total surface area of the holes is at most 5 percent of the surface area of the burner deck.

[0051] In a surface-stabilized gas burner, the position of the flame is at least substantially determined by the burner deck of the burner. The burner deck is a part of the burner where there are holes through which a premixed gas of combustible gas and air exits the burner and burns. In particular, the burner deck does not include a blind area without holes, for example, adjacent to one or both axial ends of a cylindrical burner. In the case of a blind area, the boundary between the burner deck and the blind area can be defined as being at a distance of half the pitch of the holes in the burner deck from the center of the outermost hole or holes in the burner deck. The pitch is the distance between the centers of two adjacent holes in the burner deck.

[0052] The burner system according to the present invention includes a burner having a burner deck. The burner deck has a plurality of holes. During use of the burner system, a premixed gas of combustible gas and air exits the burner through these holes and is burned. Accordingly, the flame is supplied through the plurality of holes. During operation, the flame is stabilized on the burner deck.

[0053] Optionally, the burner deck is or includes a perforated metal plate. For example, the burner deck is a cylindrical perforated metal plate, and the premixed gas of air and combustible gas flows from the inside of the cylindrical perforated metal plate through the holes of the cylindrical perforated metal plate to the outside and is burned. Optionally, one end of the cylindrical perforated metal plate is closed by a metal end cap.

[0054] Optionally, the burner includes a gas distributor configured to distribute gas onto the burner deck in a predetermined manner.

[0055] The burner system according to the present invention further includes an air inlet, a combustible gas inlet, and a mixer in communication with the air inlet and the combustible gas inlet. The mixer is configured to mix air and combustible gas to form a premixed gas of combustible gas and air at an air-to-combustible gas ratio. Optionally, the mixer is or includes a venturi.

[0056] The combustible gas inlet is suitable for receiving a combustible gas containing at least 20 volume percent hydrogen. This is achieved, for example, by the combustible gas inlet meeting the regulatory requirements for holding such a combustible gas, the combustible gas inlet being made of a suitable material, and / or the combustible gas inlet being directly or indirectly connectable to a source of combustible gas containing at least 20 volume percent hydrogen.

[0057] The "air-to-combustible gas ratio" means the ratio of the amount of air in a premixed mixture of air and combustible gas with respect to the amount of air theoretically stoichiometrically required for complete combustion of the combustible gas.

[0058] The burner system according to the present invention further comprises a burner inlet configured to receive a premixed mixture of combustible gas and air and supply it to the burner. The burner inlet is arranged upstream of the mixer and downstream of the burner as viewed in the direction of the flow of combustible gas and air through the burner system.

[0059] The burner system according to the present invention further comprises a burner load controller configured to vary the load of the burner between a minimum load and a full load. The ratio of the full load to the minimum load is at least 4, for example greater than 4, whereby the burner can be adjusted between the minimum load and the full load.

[0060] "Burner load", expressed in kW, means the amount of energy supplied to the burner per unit time. The amount of energy is equal to the mass flow rate multiplied by the calorific value of the combustible gas per unit mass.

[0061] The burner is provided (specially configured) to be adjustable between a minimum load and a full load. The ratio of the full load to the minimum load is at least 4, for example greater than 4, more preferably greater than 5, more preferably greater than 7, and even more preferably greater than 10.

[0062] The burner system according to the present invention further comprises a mechanism configured to set the air-to-flammable gas ratio of the premixed gas of flammable gas and air generated by the mixer. The setting of the air-to-flammable gas ratio of the premixed gas of flammable gas and air is at least partially according to the load of the burner. The air-to-flammable gas ratio of the premixed gas supplied to the burner when the burner is operating at the minimum load is set by the mechanism to be at least 20 percent higher than the air-to-flammable gas ratio of the premixed gas supplied to the burner when the burner is operating at the full load.

[0063] As an example, when the air-to-flammable gas ratio at the full load of the burner is 1.3, the air-to-flammable gas ratio at the minimum load means at least 1.20 * 1.3, that is, at least 1.56.

[0064] Preferably, the mechanism is configured to set the air-to-flammable gas ratio of the premixed gas supplied to the burner at least 25 percent higher, more preferably 35 percent higher, than the air-to-flammable gas ratio of the premixed gas supplied to the burner at the full load of the burner when the burner is at the minimum load. More preferably, the mechanism is configured to set the air-to-flammable gas ratio of the premixed gas supplied to the burner at least 40 percent higher, more preferably at least 60 percent higher, than the air-to-flammable gas ratio of the premixed gas supplied to the burner at the full load of the burner when the burner is at the minimum load.

[0065] In one embodiment of the burner system according to the present invention, the burner system further comprises a controller. The controller is programmed to control the mechanism such that the air-to-flammable gas ratio of the premixed gas supplied to the burner when the burner is operating at the minimum load is set by the mechanism to be at least 20 percent higher than the air-to-flammable gas ratio of the premixed gas supplied to the burner when the burner is operating at the full load.

[0066] The controller is, for example, a microprocessor, a PLC system, and / or a pneumatic system, or includes them.

[0067] In one embodiment, the controller comprises a data input port connectable to a sensor or a sensor system to receive a signal including measurement data generated by the sensor or the sensor system. The controller is configured to generate a control signal based on the signal including the measurement data received from the sensor or the sensor system. The control signal is transmitted to a data output connectable to a mechanism to determine the setting of the mechanism and control the air-to-combustible gas ratio. The connection between the sensor or the sensor system and the data input port of the controller may be either direct or indirect, and may be either wired or wireless. The connection between the data output port of the controller and the mechanism may be either direct or indirect, and may be either wired or wireless.

[0068] In an embodiment of the burner system according to the present invention, the mechanism is configured to set the air-to-combustible gas ratio of the premixed gas supplied to the burner as a defined function of the burner load.

[0069] In an embodiment of the burner system according to the present invention, the mechanism comprises a pneumatic gas valve configured to set the supply rate of the combustible gas to the burner to set the air-to-combustible gas ratio of the premixed air supplied to the burner as a defined function of the burner load.

[0070] Optionally, the pneumatic gas valve comprises a spring, and the characteristics of the spring at least partially determine the defined function.

[0071] In an embodiment of the burner system according to the present invention, the burner system further comprises a fan, which is arranged to supply air to the mixer or to supply a premixed mixture of combustible air and gas to the burner. The fan is optionally part of the burner load controller and / or is controlled by the burner load controller or an element thereof.

[0072] In an embodiment of the burner system according to the present invention, the burner system further comprises a fan, which is arranged to supply air to the mixer or to supply a premixed mixture of combustible air and gas to the burner, and the burner system further comprises the following. - A sensor configured to measure the amount of air supplied to the burner. - A combustible gas supply controller configured to control the amount of combustible gas supplied to the mixer and / or the burner, and configured to set the amount of combustible gas supplied to the burner according to a defined relationship to the amount of air supplied to the burner measured by the sensor.

[0073] The fan is optionally part of the burner load controller and / or is controlled by the burner load controller or an element thereof.

[0074] In an embodiment of the burner system according to the present invention, the burner system further comprises a fan, which is arranged to supply air to the mixer or to supply a premixed mixture of combustible air and gas to the burner, and the fan has a variable fan speed. In this embodiment, the burner system further comprises the following. A combustible gas supply controller configured to control the amount of combustible gas supplied to a mixer and / or a burner, the controller being configured to set the amount of combustible gas supplied to the burner according to a defined relationship with the amount of air supplied to the burner, wherein the fan speed is a measure of the amount of air.

[0075] The fan, which is optional, forms part of the burner load controller and / or is controlled by the burner load controller or an element thereof.

[0076] In an embodiment of the burner system according to the present invention, the burner system further comprises a fan, which is arranged to supply air to the mixer or to supply a premixed mixture of combustible air and gas to the burner, and the burner system further comprises the following. - A sensor configured to measure the amount of combustible gas supplied to the burner. - An air supply controller configured to control the amount of air supplied to the mixer and / or the burner, the air supply controller being configured to set the amount of air supplied to the burner according to a defined relationship with the amount of combustible gas supplied to the burner measured by the sensor.

[0077] The fan, which is optional, forms part of the burner load controller and / or is controlled by the burner load controller or an element thereof.

[0078] In a further embodiment of the burner system according to the present invention, the burner system further comprises a controller. The controller is programmed to control the mechanism such that the air-to-combustible gas ratio of the premixed mixture supplied to the burner when the burner is operating at minimum load is at least 20 percent higher than the air-to-combustible gas ratio of the premixed mixture supplied to the burner when the burner is operating at full load. In this embodiment, the burner system further comprises the following. - A fan configured to supply air to a mixer or to supply a premixed mixture of combustible air and gas to a burner. - A sensor configured to measure a value providing information on combustion, flue gas, and / or a mixture of air and gas supplied to a burner, and to generate measurement data regarding said value.

[0079] Here, the controller is configured to receive measurement data related to said value from the sensor and to use said measurement data in combination with a value indicating burner load, fan speed, and / or the flow rate of air supplied to the burner, and to control a mechanism to set the air-to-combustible gas ratio of the premixed mixture.

[0080] The fan is, optionally, part of a burner load controller and / or is controlled by a burner load controller or an element thereof.

[0081] Optionally, at least one sensor is a temperature sensor or includes a temperature sensor, and the value providing information on combustion represents the flue gas temperature and / or the flame temperature of the burner.

[0082] Optionally, at least one sensor is a temperature sensor or includes a temperature sensor, and the value providing information on combustion represents the temperature of the burner deck of the burner.

[0083] Optionally, at least one sensor is configured to measure a value representing the oxygen content of the flue gas generated by the burner or the oxygen content of the premixed mixture of air and combustible gas supplied to the burner.

[0084] The present invention further relates to a method of operating a surface-stabilized fully premixed gas premixing burner, in which a premix of a combustible gas and air is supplied to the burner, the combustible gas supplied to the burner contains at least 20 volume percent of hydrogen, the burner is provided to be adjustable between a minimum load and a full load, the ratio of the full load to the minimum load exceeds 4, and the burner is characterized in that at the minimum load of the burner, the air-to-combustible gas ratio of the premix supplied to the burner is set to be at least 20 percent higher than the air-to-combustible gas ratio supplied to the burner at the full load of the burner.

[0085] In this further method, a premix of a combustible gas and air is supplied to the burner. The combustible gas supplied to the burner contains at least 20 volume percent of hydrogen. The burner is provided to be adjustable between a minimum load and a full load. The ratio of the full load to the minimum load is greater than 4, more preferably greater than 5, more preferably greater than 7, and even more preferably greater than 10. Optionally, the ratio of the full load to the minimum load is at least 4. The burner is provided with a mechanism such that at the minimum load of the burner, the air-to-combustible gas ratio of the premix supplied to the burner is set to be at least 20 percent higher than the air-to-combustible gas ratio supplied to the burner at the full load of the burner.

[0086] As an example, when the air-to-combustible gas ratio at the full load of the burner is 1.3, it means that the air-to-combustible gas ratio at the minimum load is at least 1.20 * 1.3, that is, at least 1.56.

[0087] The "air-to-combustible gas ratio" means the ratio of the amount of air in the premix of air and combustible gas with respect to the amount of air theoretically stoichiometrically required for the complete combustion of the combustible gas.

[0088] The "burner load" (expressed in kW) means the amount of energy supplied to the burner per unit time. The amount of energy is equal to the product of the mass flow rate and the calorific value of the combustible gas per unit mass.

[0089] As an advantage of the present invention, while the influence on the overall efficiency of a heat exchanger using a surface-stabilized gas pre-mixed burner is very low, flashback of the flame may be prevented. A surface-stabilized fully pre-mixed gas burner to which hydrogen is supplied in a combustible gas tends to cause flashback of the flame when the burner load is low. This is considered to be due to the high combustion rate of hydrogen, which is much faster than the combustion rate of natural gas. The method of the present invention significantly reduces or eliminates the probability of flashback of the flame by increasing the air-to-combustible gas ratio at a lower load level. Thus, at a lower load level, the outlet velocity of the pre-mixed gas flowing out of the burner deck increases, the flame speed decreases, and the burner deck is cooled. These effects act synergistically to reduce the possibility of flashback of the flame. Since the air-to-gas ratio increases only at a low load level, the efficiency at a high load level of a connected heat exchanger that transfers heat from the flue gas generated by the burner to another medium (such as water) remains at a high level. Since the excess air amount of the pre-mixed supply is large, the efficiency is slightly lower only when the load is low. However, when the efficiency is averaged over the total amount or mass of the combustible gas converted by the burner over a certain period of time, the influence of the lower efficiency at a lower burner load is very low.

[0090] Preferably, the combustible gas supplied to the surface-stabilized fully pre-mixed gas burner contains at least 40 volume percent hydrogen, more preferably at least 60 volume percent hydrogen, and even more preferably at least 80 volume percent hydrogen. Even more preferably, the combustible gas is 100 percent hydrogen, excluding impurities.

[0091] In a preferred method, the burner or burner system comprises a fan for supplying air to the burner, or a fan for supplying a pre-mixture of combustible air and gas to the burner. The fan is an optional choice but forms part of a burner load controller and / or is controlled by a burner load controller or an element thereof.

[0092] Preferably, the burner comprises a burner deck in which combustion is stabilized during operation of the burner. More preferably, the burner deck is or comprises a perforated metal plate. Even more preferably, the burner deck is a cylindrical perforated metal plate. Here, the premixed gas of air and combustible gas flows from the inside of the cylindrical perforated metal plate through the holes of the cylindrical perforated metal plate to the outside thereof, where it is combusted. Even more preferably, one end of the cylindrical perforated metal plate is closed by a metal end cap.

[0093] Preferably, the burner or burner system comprises a mechanism such that the air-to-combustible gas ratio of the premixed gas supplied to the burner is set to be at least 25 percent higher, more preferably at least 35 percent higher, than the air-to-combustible gas ratio supplied to the burner at full load at the minimum load of the burner. More preferably, the burner comprises a mechanism such that the air-to-combustible gas ratio of the premixed gas supplied to the burner is set to be at least 40 percent higher, more preferably at least 60 percent higher, than the air-to-combustible gas ratio supplied to the burner at full load at the minimum load of the burner.

[0094] In a preferred method, the air-to-combustible gas ratio at the average load exceeds 5 percent, preferably exceeds 10 percent, more than the average between the air-to-combustible gas ratios at the minimum load and the full load. The average load is defined as the average between the minimum load and the full load.

[0095] Preferably, the air-to-combustible gas ratio at the average load is less than 10 percent higher than the air-to-combustible gas ratio at the full load. Even more preferably, the air-to-combustible gas ratio at the average load is less than 5 percent higher than the air-to-combustible gas ratio at the full load. The average load is defined as the average between the minimum load and the full load.

[0096] Preferably, the air-to-combustible gas ratio of the premixed gas supplied to the burner at full load is less than 1.3, preferably less than 1.25.

[0097] Preferably, the mechanism includes setting the air-to-combustible gas ratio of the premixed gas supplied to the burner as a defined function of the burner load.

[0098] In a preferred method in which the mechanism sets the air-to-combustible gas ratio of the premixed gas supplied to the burner as a defined function of the burner load, the mechanism sets the supply rate of the combustible gas to the burner using a pneumatic gas valve to set the air-to-combustible gas ratio of the premix supplied to the burner as a defined function of the burner load. More preferably, the characteristics of the spring of the pneumatic gas valve at least partially execute the defined function.

[0099] In a preferred method in which the mechanism sets the air-to-combustible gas ratio of the premixed gas supplied to the burner as a defined function of the burner load, the burner or burner system includes a fan for supplying air or a fan for supplying a premix of combustible air and gas to the burner. A sensor is used to measure the amount of air supplied to the burner, or the fan speed is used as a measure of the amount of air supplied to the burner, or the pressure drop is recorded as a measure of the amount of air supplied to the burner. The amount of combustible gas supplied to the burner is set according to a defined relationship with the amount of air supplied to the burner, for example via an electronically controlled valve.

[0100] In a preferred method, the burner or burner system includes a fan for supplying air to the burner or a fan for supplying a premix of combustible air and gas to the burner. A sensor is used to measure the amount of combustible gas supplied to the burner, and the amount of air supplied to the burner is set according to a defined relationship with the burner load determined by the amount of combustible gas supplied to the burner, for example by controlling the fan speed.

[0101] In a preferred method, the burner or burner system comprises a fan for supplying air or a premixed mixture of combustible air and gas to the burner. At least one sensor is used to measure a value that provides information on combustion, flue gas, or the mixture of air and gas supplied to the burner. This value is used in combination with a value indicating the burner load, fan speed, or the flow rate of air supplied to the burner to set the ratio of air to gas.

[0102] In a preferred method in which at least one sensor is used, the at least one sensor includes a temperature sensor, and the value providing information on combustion represents the flue gas temperature or the flame temperature of the burner.

[0103] In a preferred method in which at least one sensor is used, the at least one sensor includes a temperature sensor (e.g., a thermocouple), and the value providing information on combustion represents the temperature of the burner deck of the burner. In such a method, the burner comprises a burner deck on which combustion is stabilized during operation of the burner.

[0104] In a preferred method in which at least one sensor is used, the at least one sensor is provided to measure a value representing the oxygen content of the flue gas generated by the burner and a value representing the oxygen content of the premixed mixture of air and combustible gas supplied to the burner.

[0105] Preferably, the burner comprises a perforated metal plate on which the flame is stabilized.

[0106] The present invention further relates to a surface-stabilized fully premixed gas premixing burner comprising means for carrying out the method in any embodiment of the first aspect of the present invention.

[0107] Preferably, the surface-stabilized fully premixed gas premixing burner comprises a controller. The controller is programmed to operate the burner in a manner similar to any embodiment of the first aspect of the present invention.

[0108] Preferably, the burner includes a burner deck where combustion is stabilized during operation of the burner. More preferably, the burner deck is a perforated metal plate. Even more preferably, the burner deck is a cylindrical perforated metal plate. Here, the premixed gas of air and combustible gas flows from the inside of the cylindrical perforated metal plate through the holes of the cylindrical perforated metal plate to the outside, where it is combusted. Even more preferably, one end of the cylindrical perforated metal plate is closed by a metal end cap.

Brief Description of the Drawings

[0109]

Figure 1

Figures 2-3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0110] The present invention relates to a method of operating a surface-stabilized fully-premixed gas pre-mixing burner, which has the advantage that the combustible gas supplied to the burner contains at least 20 volume percent of hydrogen and flashback of the flame is prevented. Flashback of the flame is a complex phenomenon, but it is related to the ratio of the outlet velocity (m / s) of the premixed gas passing through the burner deck to the combustion velocity (m / s) of the combustible gas. The outlet velocity is proportional to the volume flow rate of the premixed gas divided by the surface area of the through-holes of the burner deck where combustion is stabilized. The combustion velocity depends on a plurality of parameters such as the temperature of the gas premix and / or the air-to-fuel ratio of the gas premix. However, when the initial estimated value and other parameters are considered equal, it can be considered constant from the minimum load to the full load of the burner. It has been found that when the ratio of the outlet velocity (m / s) of the premixed gas passing through the burner deck to the combustion velocity (m / s) of the combustible gas becomes low, the risk of flashback of the flame increases.

[0111] Figure 1 schematically illustrates a method of controlling a surface-stabilized fully-premixed gas pre-mixing burner using a constant air-to-combustible gas ratio over the entire range of burner operation from minimum load to full load. Figure 1(a) shows the air-to-combustible gas ratio (Y) as a function of the burner load (X, in kW) from the minimum burner load (m) to the full burner load (M). In the method of Figure 1, the air-to-combustible gas ratio is kept constant. Figure 1(b) shows, for the control method shown in Figure 1(a), the ratio (Z) of the outlet velocity (m / s) of the premixed gas passing through the burner deck to the combustion velocity (m / s) of the combustible gas on the vertical axis as a function of the burner load (X). This ratio is linear and is minimum at the minimum burner load, and thus the risk of flashback of the flame is highest.

[0112] Figure 2 schematically illustrates a method for controlling a surface-stabilized fully premixed gas pre-mixing burner according to the present invention. Figure 2(a) shows the air-to-combustible gas ratio (Y) used as a function of the burner load (X, in kW) from the minimum load (m) to the full burner load (M). From the full load of the burner to the burner load A, a first value of the air-to-combustible gas ratio is used. For burner loads less than A, the value of the air-to-combustible gas ratio is set higher (increasing as the burner load decreases). This ratio is at least 20 percent higher than the first value at the minimum burner load. The result can be seen in Figure 2(b) which shows the corresponding ratio (Z) of the exit velocity to the combustion velocity for the method of controlling this burner. At the burner load level A, the curve changes and the minimum value of the ratio (Z) of the exit velocity (in m / s) of the premixed gas passing through the burner deck to the combustion velocity (in m / s) of the combustible gas is significantly increased compared to the situation in Figure 1(a). Thus, the risk of flashback of the flame is significantly reduced. Furthermore, when the amount of the premixed gas is large (because more air is supplied), the cooling of the burner deck is enhanced, further reducing the risk of flashback of the flame. When the amount of the premix is large, the flame speed of the mixture decreases, further reducing the risk of flashback of the flame.

[0113] Figure 3 schematically illustrates a method for controlling a surface-stabilized fully premixed gas pre-mixing burner according to the present invention. Figure 3(a) shows the air-to-combustible gas ratio (Y) used as a function of the burner load (X, unit: kW) from the minimum load (m) to the full burner load (M). At the minimum load, the air-to-combustible gas ratio is at least 20 percent higher than that at the full burner load. The result of the air-to-combustible gas ratio at the burner load can be confirmed in Figure 3(b), which shows the ratio (Z) of the exit velocity to the combustion velocity of the method for controlling this burner. At the burner load level B, the curve reaches a minimum. The minimum value of the exit velocity relative to the burner velocity is significantly increased compared to the situation in Figure 1(a). Therefore, the risk of flashback of the flame is significantly reduced. Furthermore, when the amount of the premixed gas is large (because more air is supplied), the cooling of the burner deck is enhanced, further reducing the risk of flashback of the flame. When the amount of the premixed gas is large, the flame velocity of the mixture decreases, further reducing the risk of flashback of the flame.

[0114] In the embodiments of Figures 1, 2 and 3, normal operating conditions apply.

[0115] Figure 4 shows an example of the method according to the present invention. Figure 4 shows a surface-stabilized fully premixed gas pre-mixing burner 400. The burner has a cylindrical perforated plate 410 as the burner deck. The premix of air and combustible gas is supplied inside the cylindrical perforated plate. The combustible gas supplied to the burner contains at least 20 volume percent of hydrogen. The premix flows through the through-holes of the cylindrical perforated plate. The gas burns outside the cylindrical perforated plate. Combustion is stabilized outside the cylindrical perforated plate. A fan 420 is provided to supply the premix to the cylindrical perforated plate. The fan sucks in air (sucked in through the supply line 430), and the combustible gas (through the supply line 440) is supplied to the air stream. An air pressure gas valve 450 is used, and its operating characteristics are predefined such that an air-to-combustible gas ratio as a function of the burner load can be obtained, for example, as shown in Figure 2(a), 3(a) or Figure 5.

[0116] Alternatively, the amount of gas can be set as a function of the fan speed (known or measured via burner control) via a controlled valve using a pre-defined function, thereby executing a pre-defined function for setting the air-to-combustible gas ratio of the premixed gas supplied to the burner, for example, the function shown in FIGS. 2(a), 3(a) or FIG. 5.

[0117] FIG. 5 shows a practical example of a defined function for setting the air-to-combustible gas ratio of the premixed gas supplied to the burner. The cylindrical perforated plate burner is operated between a minimum load of 5 kW and a full load of 25 kW. The surface-stabilized fully premixed cylindrical burner had a diameter of 63 mm and a length of 158.4 mm. The cylindrical burner had a 32 mm long non-perforated portion for the premix supply along its length and was non-perforated with a length of 14.6 mm at the plate end. The holes were circular with a diameter of 0.8 mm and were uniformly distributed over a length of 111.8 mm of the burner. The porosity of the burner deck was 1.5 percent. The burner was operated using 100 percent hydrogen as the combustible gas. And the function shown in FIG. 5 was used for the air-to-combustible gas ratio (Y-axis) as a function of the burner load (axis X, unit kW). The experiment showed that there was no flashback of the flame at all.

[0118] FIG. 6 schematically shows an embodiment of a burner system 500 according to the present invention.

[0119] The burner system 500 includes a burner 501 including a burner deck 502. The burner deck 502 includes a plurality of holes 503. In the burner 501 of the burner system 500, the total surface area of the holes 503 is at most 5 percent of the surface area of the burner deck 502. Thereby, the burner system can use a combustible gas containing at least 20 volume percent hydrogen. The blind zone 504 does not have the holes 503 therein and thus is not part of the burner deck 502.

[0120] In the embodiment of FIG. 6, the burner deck 502 is formed by a cylindrical perforated metal plate. A premixed gas of air and a combustible gas flows from the inside of the cylindrical perforated metal plate through the holes of the cylindrical perforated metal plate (i.e., holes 503) to the outside thereof, where it is combusted. Optionally, one end of the cylindrical perforated metal plate is closed by a metal end cap.

[0121] Optionally, the burner 501 comprises a gas distributor configured to distribute gas onto the burner deck in a predetermined manner.

[0122] The burner system 500 further comprises an air inlet 510, a combustible gas inlet 520, and a mixer 530 in communication with the air inlet 510 and the combustible gas inlet 520. The mixer 530 is configured to mix air and a combustible gas to form a premixed gas of combustible gas and air at an air-to-combustible gas ratio. Optionally, the mixer 530 is a venturi or includes a venturi.

[0123] The combustible gas inlet 520 is suitable for receiving a combustible gas containing at least 20 volume percent hydrogen. This is achieved, for example, by the combustible gas inlet 520 meeting the regulatory requirements for holding such a combustible gas, the combustible gas inlet being made of a suitable material, and / or the combustible gas inlet being connectable directly or indirectly to a source of combustible gas containing at least 20 volume percent hydrogen.

[0124] The burner system 500 further comprises a burner inlet 540 configured to receive the premixed gas of combustible gas and air from the mixer 530 and supply it to the burner 501. The burner inlet 540 is arranged between the mixer 530 and the burner 501 as viewed in the direction of flow of combustible gas and air through the burner system. from the direction of flow of combustible gas and air through the burner system. downstream and the burner 501. upstream is arranged between the mixer 530

[0125] The burner system 500 further includes a burner load controller 561 configured to vary the load of the burner between a minimum load and a full load. The ratio of the full load to the minimum load is at least 4, and optionally greater than 4, whereby the burner can be adjusted between the minimum load and the full load. The burner load controller controls the load of the burner, for example, by a valve or a fan 563.

[0126] In the embodiment of FIG. 6, the burner load controller forms part of an overall burner control system 560.

[0127] The burner 501 is configured to adjust between a minimum load and a full load. The ratio of the full load to the minimum load is at least 4, and optionally greater than 4, more preferably greater than 5, more preferably greater than 7, and even more preferably greater than 10.

[0128] The burner system 500 further includes a mechanism 570 configured to set the air-to-combustible gas ratio of the premixed gas of combustible gas and air generated by the mixer 530. The setting of the air-to-combustible gas ratio of the premixed gas of combustible gas and air depends at least in part on the load of the burner 501. The air-to-combustible gas ratio of the premixed gas supplied to the burner 501 when the burner 501 is operating at the minimum load is set by the mechanism 570 to be at least 20 percent higher than the air-to-combustible gas ratio of the premixed gas supplied to the burner 501 when the burner 501 is operating at the full load.

[0129] The mechanism 570 includes, for example, a pneumatic gas valve configured to set the supply rate of combustible gas to the burner to set the air-to-combustible gas ratio of the premixed gas supplied to the burner as a predetermined function of the burner. For example, the pneumatic gas valve includes a spring, and the characteristics of the spring define at least in part the defined function.

[0130] The burner system 500 of FIG. 6 further includes a controller 562. The controller 562 is programmed to control a mechanism 570 such that when the burner is operating at a minimum load, the air-to-combustible gas ratio of the premixed gas supplied to the burner 501 is at least 20 percent higher than the air-to-combustible gas ratio of the premixed gas supplied to the burner 501 when the burner 501 is operating at full load, as set by the mechanism 570.

[0131] In the embodiment of FIG. 6, the controller 562 forms part of an overall burner control system 560.

[0132] In the embodiment of FIG. 6, a fan 563 of the burner load controller 561 is arranged to supply a premixed gas of combustible air and gas to the burner 501.

[0133] FIG. 7 schematically shows a modification of the embodiment of FIG. 6.

[0134] In the embodiment of FIG. 7, the burner system 500 further includes a sensor 590. The sensor 590 is configured to measure the amount of air supplied to the burner 501. In this embodiment, the sensor 590 is arranged at the burner inlet 540, but alternatively, it can be arranged at the air inlet 510, for example.

[0135] In the embodiment of FIG. 7, the burner system 500 further includes a combustible gas supply controller 591 configured to control the amount of combustible gas supplied to the mixer 530 and, together therewith, the amount of combustible gas supplied to the burner 501.

[0136] The combustible gas supply controller 591 is configured to set the amount of combustible gas supplied to the burner 501 according to a defined relationship with respect to the amount of air supplied to the burner 501 measured by the sensor 590.

[0137] The combustible gas supply controller 591 optionally includes a fan. This fan optionally forms part of the burner load controller and / or is controlled by the burner load controller or an element thereof. If such a fan is used within the combustible gas supply controller 591, the fan 563 of the embodiment of FIG. 6 may be omitted.

[0138] FIG. 8 schematically shows a modification of the embodiment of FIG. 6.

[0139] In the embodiment of FIG. 8, the burner system 500 further includes a sensor 592. The sensor 592 is configured to measure the amount of combustible gas supplied to the burner 501. In this embodiment, the sensor 592 is arranged at the burner inlet 540, but alternatively it can be arranged, for example, at the combustible gas inlet 520.

[0140] In the embodiment of FIG. 8, the burner system 500 further includes an air supply controller 593 configured to control both the amount of air supplied to the mixer and the amount of air supplied to the burner 501 therewith. The air supply controller 593 is configured to set the amount of air supplied to the burner 501 according to a defined relationship with respect to the amount of combustible gas supplied to the burner 501 measured by the sensor 592.

[0141] The air supply controller 593 optionally includes a fan. This fan optionally forms part of the burner load controller and / or is controlled by the burner load controller or an element thereof. If such a fan is used within the air supply controller 593, the fan 563 of the embodiment of FIG. 6 may be omitted.

Claims

1. A method for operating a surface-stabilized premixed gas premixing burner, the burner being configured to be adjusted between a minimum load and a full load, the ratio of the full load to the minimum load being at least 4, the method comprising: - supplying a premixed gas of combustible gas and air to the burner at an air-to-combustible gas ratio, wherein the combustible gas supplied to the burner contains at least 20 volume percent hydrogen, - the air-to-combustible gas ratio of the premixed gas supplied to the burner when the burner is operating at minimum load is set by a mechanism to be at least 35 percent higher than the air-to-combustible gas ratio of the premixed gas supplied to the burner when the burner is operating at full load.

2. The method according to claim 1, wherein the air-to-combustible gas ratio at the average load is less than 10 percent higher than the air-to-combustible gas ratio at the full load, and the average load is defined as the average between the minimum load and the full load.

3. The method according to claim 1 or 2, wherein the air-to-combustible gas ratio of the premixed gas supplied to the burner at full load is less than 1.

3.

4. The method according to claim 1, wherein the air-to-combustible gas ratio of the premixed gas supplied to the burner is set by the mechanism as a defined function of the burner load.

5. The method according to claim 4, wherein an air pressure gas valve for setting the supply rate of the combustible gas to the burner is used by the mechanism to set the air-to-combustible gas ratio of the premixed gas supplied to the burner as a defined function of the burner load.

6. The method according to claim 5, wherein an air pressure gas valve including a spring is used, and the characteristics of the spring at least partially determine the defined function.

7. Air or a premixed gas of combustible gas and air is supplied to the burner by a fan, the amount of air supplied to the burner is measured by a sensor or the fan speed is used as an indicator of the amount of air supplied to the burner, the amount of combustible gas supplied to the burner is set according to a defined relationship to the amount of air supplied to the burner.

8. Air or a premixed gas of combustible gas and air is supplied to the burner by a fan, the amount of combustible gas supplied to the burner is measured by a sensor, The method according to claim 1, wherein the amount of air supplied to the burner is set according to a defined relationship with respect to the amount of combustible gas supplied to the burner.

9. Air or a premixed mixture of combustible gas and air is supplied to the burner by a fan, The value providing information on combustion, flue gas, and / or the ratio of air to combustible gas supplied to the burner is measured by at least one sensor, This value is used in combination with a value indicating the burner load, fan speed, and / or the flow rate of air supplied to the burner to set the air-to-combustible gas ratio. The method according to claim 1.

10. The method according to claim 9, wherein the at least one sensor is a temperature sensor or includes a temperature sensor, and the value providing combustion information represents the flue gas temperature or the flame temperature of the burner.

11. The burner includes a burner deck where combustion stabilizes when the burner is operating, The method according to claim 9, wherein the at least one sensor is a temperature sensor or includes a temperature sensor, and the value providing combustion information represents the temperature of the burner deck of the burner.

12. The method according to claim 9, wherein the at least one sensor is provided to measure a value representing the oxygen content of the flue gas generated by the burner or a value representing the oxygen content of the premixed mixture of combustible gas and air supplied to the premixed burner.

13. The method according to claim 1, wherein the burner used includes a perforated metal plate where the flame stabilizes.

14. A surface-stabilized fully premixed gas premixing burner system, The burner system includes: - A burner including a burner deck with a plurality of holes, - An air inlet, a combustible gas inlet, and a mixer in communication with the air inlet and the combustible gas inlet, the mixer being configured to mix air and combustible gas to form a premixed mixture of combustible gas and air at an air-to-combustible gas ratio, and the combustible gas inlet being suitable for receiving a combustible gas containing at least 20% by volume of hydrogen, an air inlet, a combustible gas inlet, and a mixer in communication with the air inlet and the combustible gas inlet, - A burner inlet configured to receive the premixed mixture of combustible gas and air and supply it to the burner. - A burner load controller configured to vary the load of the burner between a minimum load and a full load, wherein the ratio of the full load to the minimum load is at least 4, whereby the burner is adjusted between the minimum load and the full load, the burner load controller, - A mechanism configured to set the air-to-combustible gas ratio of the premixed gas of combustible gas and air generated by the mixer, wherein the setting of the air-to-combustible gas ratio of the premixed gas of combustible gas and air is performed at least partially in response to the load of the burner, and when the burner is operating at the minimum load, the air-to-combustible gas ratio of the premixed gas supplied to the burner is at least 35 percent higher than the air-to-combustible gas ratio of the premixed gas supplied to the burner when the burner is operating at the full load, and is set by the mechanism, the mechanism, A burner system comprising the above.

15. The burner system according to claim 14, wherein the total surface area of the holes is at most 5 percent of the surface area of the burner deck.

16. The burner system further comprises a controller, The controller is programmed to control the mechanism such that when the burner is operating at the minimum load, the air-to-combustible gas ratio of the premixed gas supplied to the burner is set to be at least 20 percent higher than the air-to-combustible gas ratio of the premixed gas supplied to the burner when the burner is operating at the full load. The burner system according to claim 14 or 15.

17. The burner system according to claim 14, wherein the mechanism is configured to set the air-to-combustible gas ratio of the premixed gas supplied to the burner as a defined function of the burner load.

18. The mechanism includes a pneumatic gas valve, The pneumatic gas valve is configured to set the supply rate of the combustible gas to the burner in order to set the air-to-combustible gas ratio of the premixed gas supplied to the burner as a defined function of the burner load. The burner system according to claim 14.

19. The pneumatic gas valve according to claim 18 includes a spring, and the characteristics of the spring at least partially determine the defined function. The burner system according to claim 18.

20. The burner system further comprises a fan, The burner system according to claim 14, wherein the same fan is arranged to supply air to the mixer or to supply a premixed mixture of combustible gas and air to the burner.

21. The burner system further comprises - a sensor configured to measure the amount of air supplied to the burner, and - a combustible gas supply controller configured to control the amount of combustible gas supplied to the mixer and / or the burner, the combustible gas supply controller being configured to set the amount of combustible gas supplied to the burner according to a defined relationship with the amount of air supplied to the burner measured by the sensor, The burner system according to claim 20, comprising.

22. The fan has a variable fan speed, The burner system further comprises - a combustible gas supply controller configured to control the amount of combustible gas supplied to the mixer and / or the burner, the combustible gas supply controller being configured to set the amount of combustible gas supplied to the burner according to a defined relationship with the amount of air supplied to the burner, and the fan speed being a measure of the amount of that air,

23. The burner system further comprises - a sensor configured to measure the amount of combustible gas supplied to the burner, and - an air supply controller configured to control the amount of air supplied to the mixer and / or the burner, the air supply controller being configured to set the amount of air supplied to the burner according to a defined relationship with the amount of combustible gas supplied to the burner measured by the sensor,

24. The burner system further comprises - a fan arranged to supply air to the mixer or to supply a premixed mixture of combustible gas and air to the burner, and - a sensor configured to measure a value providing information on the ratio of combustion, flue gas, and / or air and combustible gas supplied to the burner, and to generate measurement data regarding the value. The controller is configured to receive measurement data related to the value from a sensor and use the measurement data in combination with a value indicating burner load, fan speed, and / or the flow rate of air supplied to the burner, and to control the mechanism to set the air-to-combustible gas ratio of the premix, the burner system according to claim 16.

25. The burner system according to claim 24, wherein the at least one sensor is a temperature sensor or includes a temperature sensor, and the value providing combustion information represents flue gas temperature and / or burner flame temperature.

26. The burner system according to claim 24, wherein the at least one sensor is a temperature sensor or includes a temperature sensor, and the value providing combustion information represents the temperature of the burner deck of the burner.

27. The burner system according to claim 24, wherein the at least one sensor is configured to measure a value representing the oxygen content of the flue gas generated by the burner or a value representing the oxygen content of the premix of air and combustible gas supplied to the burner.

Images