How does a gas heater work?

Abstract

The present invention relates to a method for operating a gas heater, in particular a gas heater for providing central heating and / or domestic hot water, in particular a gas boiler, in particular a condensing boiler, comprising the following steps: supplying gas and a fuel gas into a mixing chamber of the gas heater and supplying the mixed gas from the mixing chamber to a burner of the gas heater, measuring a differential pressure per unit of time and / or presenting a sensor signal to a control unit in order to determine a gas amount defined by volume per unit of time or mass per unit of time before the gas is supplied to the mixing chamber, measuring a differential pressure per unit of time and / or presenting a sensor signal to a control unit in order to determine a fuel gas amount defined by volume per unit of time or mass per unit of time before the fuel gas is supplied to the mixing chamber, and determining whether at least one operating condition of the gas heater is fulfilled based on the determined gas amount and / or the determined fuel gas amount.

Description

[Technical field]

[0001] The present invention relates to a method for operating a gas heater. Furthermore, the present invention relates to a gas heater and a boiler equipped with such a gas heater. Furthermore, the present invention relates to a heating system having such a gas heater and / or boiler, and to the use of such a gas heater and / or boiler. Furthermore, the present invention relates to a computer program product. [Background technology]

[0002] A number of gas heaters are known from the prior art. A gas heater usually comprises a mixing chamber in which a gas, in particular air, is mixed with a fuel gas. The mixed gas is fed to a burner of the gas heater. Such a gas heater can be used, for example, in a boiler. The boiler comprises a heat exchanger in which water is heated by the heat provided by the gas heater.

[0003] US Patent No. 5,486,107 is directed to improved determination of fuel properties including calorific value and oxygen demand and Wobbe index or number for more accurate fuel metering and combustion control with a view to accurately determining the amount of oxygen required for complete combustion of a given type and amount of fuel that is valid for a wide range of fuel compositions and is as accurate as it is less susceptible to errors in the measured parameters from which the values ​​are derived. The present invention relates to a method for determining thermophysical or thermochemical property values ​​of a natural or other hydrocarbonaceous gaseous fuel gas using a microbridge type sensor, the microbridge type sensor being fluidly coupled to receive the fuel and to provide a signal value, thermal conductivity, k, of the fuel, the method comprising the steps of: applying the fuel to the static microbridge type sensor to obtain a thermal conductivity value of the fuel; applying the fuel to the static microbridge type sensor to obtain a specific heat value of the fuel, the microbridge type sensor being fluidly coupled to receive the fuel and to provide a signal value, specific heat, c p, of the fuel; correcting the values ​​of the signals k and c p using a plurality of measured sensor signal values ​​k and c p obtained at different temperatures so that the values ​​can be processed to obtain corresponding values ​​at a reference condition of the fuel; ps processing a plurality of measured different temperature values ​​of cp to obtain a value of dcp / dT at a reference condition of k s To obtain the value of dk / dT at the reference condition, s and in a processor, processing the values ​​obtained in the previous step to obtain a desired property of the fuel according to a relationship selected from the following: JPEG2024506974000002.jpg49167 where Ys is the higher calorific value, H is the oxygen demand, D is the Wobbe index, Wo is the relative density or specific gravity, ρ is the absolute density, ρ a ; inert material, I; compression coefficient, Z; critical compression ratio R c represents the thermophysical or thermochemical parameter of interest selected from viscosity, η; A0, A1...A i is a constant or coefficient, and ni , m i , p i , q i , r i , s i is an exponent with a value between -20 and 20, including 0, the number of terms i ranges from 1 to 15, and k s and c ps represent their values ​​at given reference conditions of temperature and pressure, and x s represents dk / dT at the reference condition, and Y s is the dc current at the reference conditions p / dT, where T s represents the temperature at reference conditions, and P s represents the absolute pressure at reference conditions.

[0004] The specification of US Patent No. 6,561,791 is directed to providing a regulating device for a gas burner that avoids the drawbacks of a limited operating range, such as a limited operating range or limitations due to the interaction between low actuation force and operating tolerances as a result of interference effects, and discloses a regulating system for a gas burner in which a flow of fuel gas and a flow of combustion air are led to the burner. The flow of fuel gas is regulated according to the pressure of the flow of combustion air. A differential pressure sensor is arranged between the flow of fuel gas and the flow of combustion air. The sensor generates an electronic signal that is used to regulate a gas valve for the fuel gas.

[0005] WO 2020 / 148,434 is directed to providing a less complex but more accurate method for adjusting the gas mixture of a fuel gas-operated heating device, which is also robust against external influences such as dust, and discloses a method for controlling a gas mixture formed from a gas and a fuel gas of a fuel gas-operated heating device, in which the gas mixture is generated by a gas amount and a fuel gas amount supplied by a first actuator and a second actuator, respectively, and then mixed; a micro-thermal gas mixture sensor that detects at least one material property of the gas mixture is supplied together with the gas mixture and continuously transmits a sensor signal that depends on the particular gas mixture to a control device; the control device compares the detected sensor signal with a set value of the sensor signal and activates at least one of the first and second actuators if the detected sensor signal deviates from the set value sensor signal, so that the gas mixture is adjusted by increasing or decreasing the gas amount and / or increasing or decreasing the fuel gas amount until the set value of the sensor signal is achieved.

[0006] German Utility Model No. 2020 / 18,101,271 is directed to providing a fuel gas operated heater in which the type of fuel gas is determined before the heater is started and used for the start-up process, and discloses a fuel gas operated heater with an electronic gas-air system, the heater having at least one blower for conveying an air volume flow, a gas supply with a gas actuator for a controlled supply of fuel gas, a burner, an ignition unit for igniting the burner, a sensor arranged in the gas supply and flowing with the fuel gas, and a control device for determining the gas mass flow of the fuel gas and regulating the air volume flow conveyed by at least the blower and the gas actuator, a. the sensor is designed as a gas mass sensor for determining a fuel gas mass and a physical property assigned to the fuel gas mass; b. The physical properties of the fuel gas can be measured by the gas mass sensor and transmitted to the control unit; c. the type of fuel gas can be determined by the control device from a measured physical property of the fuel gas; d. The control device of the gas control element can adjust the first starting gas mass flow according to the specific fuel gas type, which is lower than the ignition limit of the fuel gas of the specific fuel gas type; e. the supplied gas mass flow can be increased at a constant air volume flow, starting from an initial gas mass flow, until the range of ignition of a particular fuel gas type is exceeded by an ignition attempt by the ignition unit; f. Burner ignition may be monitored and recorded during the ignition attempt.

[0007] EP 3,683,500 is directed to providing a method for regulating a gas mixture in a fuel gas-operated heating device, which detects changes in the properties of the gas supplied to the fuel gas and adapts the control parameters in a targeted manner. It discloses a method for regulating a gas mixture formed from gas and fuel gas in a fuel gas-operated heating appliance, in which the gas mixture is generated by supplying and mixing a gas amount by a first control element and a fuel gas amount by a second control element, a micro thermal gas sensor and a gas mixture sensor are used, the sensor signal is relayed to a controller, when the detected sensor signal of the gas sensor changes, the newly detected sensor signal of the gas sensor is compared with a reference value measured in a laboratory and stored in a table of values ​​of the controller, from which a target value of the sensor signal of the gas mixture sensor is determined, without changing the mixture ratio of the gas mixture composed of fuel gas and gas.

[0008] EP 2,574,918 is directed to specifying a method for a simple and cost-effective upgrade of suitable gas flow measurement technology to a high accuracy gas quality sensor, which is a parameter relevant for combustion technology such as calorific value, Wobbe index, methane number and / or air requirement through correlation with basic properties of heat capacity, determining the thermal conductivity or density of the gas, a first sensor for a physical gas property (γ), e.g. density (ρ) or heat capacity (cp) or mass flow or volumetric flow or a combination of these variables. JPEG2024506974000003.jpg11166 discloses a method for determining a physical gas property of a gas mixture for correlation of variables related to combustion of the gas mixture by combining JPEG2024506974000004.jpg15154, where at least a micro-thermal sensor is exposed to the gas flow, and the thermal conductivity (λ) of the gas mixture is measured separately using the micro-thermal sensor.

[0009] WO 2019 / 185,181 is directed to providing a regulating device capable of achieving reliable and accurate control of the mixing ratio between a first gas and a second gas over a wide dynamic range of absolute flow rates of the gases, even when there are large differences between their flow rates, and discloses a regulating device comprising a first sensor S1 for determining one or more thermal parameters of a gas mixture, the sensor being arranged in a common conduit downstream of the mixing region and upstream of the fan such that the sensor S1 is exposed to the gas mixture.

[0010] The control device receives a sensor signal from the first sensor S1. Based on the sensor signal, the control device derives a control signal for adjusting the opening of the fuel control valve. The control device further adjusts the power for operating the fan. Further sensors can be provided in the air conduit and / or the fuel conduit. By way of example, a second sensor S2 is provided in the air conduit upstream of the mixing region. Additionally or alternatively, a third sensor S3 is provided in the fuel conduit downstream of the fuel control valve and upstream of the mixing region. As with the first sensor S1, the second sensor S2 and / or the third sensor S3 are also advantageously protected from direct exposure to the respective gas streams by placing each sensor in a dead-end recess in the wall of the respective conduit and / or by protecting each sensor by a gas-permeable membrane. The sensor S1 is operative to determine the thermal conductivity λmix, the thermal diffusivity Dmix, and the temperature Tmix of the gas mixture in the common conduit downstream of the mixing region. Sensor S2 is operative to determine the thermal conductivity λ air , the thermal diffusivity D air , and the temperature T air of the air conduit upstream of the mixing region.

[0011] From these quantities the air pressure couple is determined. The air pressure couple or air density determined from the signal of sensor S2 can be used as an additional diagnostic parameter. In particular the air pressure couple or air density can be used to detect a blockage or malfunction of the fan. For example the air pressure or density can be monitored permanently or periodically during operation of the regulator. A change in air pressure or density while operating the fan at a constant fan power can indicate a blockage or a malfunction of the fan. Determining the air pressure or density from the signal of sensor S2 is possible during normal operation of the regulator. Sensor S3 operates to determine the thermal conductivity λ fuel, the thermal diffusivity D fuel and the temperature T fuel of the fuel gas in the fuel conduit downstream of the fuel control valve and upstream of the mixing region. The mixture ratio x is calculated using the values ​​λ mixed determined by sensor S1, λ air determined by sensor S2 and λ fuel determined by sensor S3, JPEG2024506974000005.jpg9166. WO 2019 / 185,181 further discloses that a mass flow meter can be used to further measure the flow rate of air in the air conduit, the flow of fuel in the fuel conduit, or the flow of the gas mixture in the common conduit. In this way, WO 2019 / 185,181 determines the absolute heating power of the gas mixture delivered to the gas burner. The mass flow rate can be used to control a fan to adjust the heating power. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Pat. No. 5,486,107 [Patent Document 2] U.S. Patent No. 6,561,791 [Patent Document 3] International Publication No. 2020 / 148,434 Brochure [Patent Document 4] German Utility Model No. 2020 / 18,101,271 [Patent Document 5] European Patent No. 3,683,500 [Patent Document 6] European Patent No. 2,574,918 [Patent Document 7] International Publication No. 2019 / 185,181 Brochure Summary of the Invention [Problem to be solved by the invention]

[0013] In a conventional electronic air ratio control system, the gas heater controller controls the heat load of the gas heater by controlling the ratio of gas to fuel gas. Because the flame signal depends on the composition of the mixed gas, the ratio of gas to fuel gas can be controlled based on the ionization signal. Thus, the gas heater can be internally adapted to the same fuel gas. However, known gas heaters cannot be used with mixtures of fuel gas containing more than 95 mol% hydrogen. In particular, when the fuel gas is or contains more than 95 mol% hydrogen, the ionization signal cannot be used to adapt the mixed gas to the composition required for the burner to deliver the required power. Thus, conventional gas adaptation systems require the use of sufficient natural gas to utilize the ionization signal, and therefore such systems cannot perform hydrogen combustion of 95 mol% or more. [Means for solving the problem]

[0014] The object of the present invention is to provide a method for operating a gas heater that can be adapted to various types of fuel gas or mixtures of fuel gases. In particular, the gas heater should be gas compatible with various types of fuel gas or mixtures of fuel gases, including fuel gases containing hydrogen, and should avoid high emissions or poor efficiency due to inaccurate mixing of gas and fuel gas. Furthermore, the method should also avoid the heater not starting or having flashback due to inaccurate gas to air ratio.

[0015] The object is to provide a method for operating a gas heater, in particular a gas heater for providing central heating and / or for providing domestic hot water, in particular a gas boiler, in particular a condensing boiler, comprising: supplying gas and fuel gas into a mixing chamber of the gas heater, and supplying the mixed gas from the mixing chamber to a burner of the gas heater; measuring a differential pressure per unit time and / or presenting a sensor signal to a controller to determine a quantity of gas defined by volume per unit time or mass per unit time before the gas is delivered to the mixing chamber; measuring a differential pressure per unit time and / or providing a sensor signal to a controller to determine an amount of fuel gas, defined by volume per unit time or mass per unit time, before the fuel gas is supplied to the mixing chamber; and The problem is solved by a method comprising the steps of:

[0016] Another object of the present invention is to provide a gas heater that can be used with various types of fuel gases or mixtures of fuel gases.

[0017] The object is solved by a gas heater comprising a mixing chamber for mixing gas and a fuel gas, a burner arranged downstream of the mixing chamber and capable of supplying the mixed gas of the mixing chamber, a first sensor for measuring the differential pressure per unit time and / or for presenting to the control unit a sensor signal for determining a gas amount defined by a volume per unit time or a mass per unit time of gas supplied to the mixing chamber, a second sensor for measuring the differential pressure per unit time and / or for presenting to the control unit a sensor signal for determining a fuel gas amount defined by a volume per unit time or a mass per unit time of fuel gas supplied to the mixing chamber, and a control unit adapted to determine whether at least one operating condition of the gas heater is fulfilled based on the determined gas amount and / or the determined fuel gas amount.

[0018] According to the invention, it has been recognized that by determining whether at least one operating condition of the gas heater is fulfilled based on the determined gas amount and / or the determined fuel gas amount, it is possible to adapt the gas to fuel gas ratio so that the burner can deliver the required power with safe operation even in the case of a high hydrogen concentration in the fuel, 95 mol % or more. In particular, it is possible to deliver a gas mixture having a gas to fuel gas ratio corresponding to a predetermined gas to fuel gas ratio, when at least one or all operating conditions are fulfilled.

[0019] The predetermined gas to fuel gas ratio of the gas mixture can depend on the operation of the gas heater, in particular the burner. It can be determined in a laboratory and stored in an electrical memory of the gas heater. In particular, gas to fuel gas ratios covering all operations of the burner, meaning from minimum load to maximum load, can be stored in the electrical memory. The electrical memory can be part of the control unit.

[0020] Therefore, when a high concentration of hydrogen is present in the fuel gas, it is possible to determine the gas to fuel gas ratio of the mixed gas leaving the mixing chamber independently of the ionization signal. The composition of the fuel gas that can be used in the gas heater is therefore more versatile than in known embodiments. Furthermore, in embodiments of the invention, the gas and fuel gas amounts are always known and can always be controlled, which is advantageous for safety reasons, especially when hydrogen is used as fuel gas or as part of the fuel gas.

[0021] A further advantage of the present invention is that the gas and fuel quantities can be set to prevent flashback, which occurs when the gas mixing velocity is less than the flame velocity and the flame traverses upstream towards the burner deck and even across the burner deck into the burner.

[0022] The fuel gas can be natural gas, methane, ethylene, propane, butane, coal gas, biogas, and the like, mixtures thereof and mixtures thereof further containing hydrogen, or hydrogen, in particular pure hydrogen. Pure hydrogen is present when the fuel gas has at least 98 mol% hydrogen.

[0023] The gas may be air.

[0024] The controller is an electrical controller. Further, the controller is adapted to receive the electrical sensor signal and output the electrical control signal. The controller may include at least one processor and / or a printed circuit board.

[0025] The sensor is, for example, a flow sensor. The flow sensor may be a sensor that measures a differential pressure. In particular, the sensor may be a mass flow sensor or a volumetric flow sensor. Furthermore, the sensor may be a thermal sensor, a temperature anemometer sensor, an ultrasonic flow sensor, a magnet flow sensor, a Coriolis mass flow sensor and / or an optical sensor. The sensor may be an electrical or electronic sensor.

[0026] The mixed gas is the output gas that exits the mixing chamber. The mixed gas may include gas and fuel gas, or the mixed gas may consist of gas only if no fuel gas is inserted into the mixing chamber.

[0027] A first sensor is disposed upstream of the mixing chamber to determine the amount of gas supplied to the mixing chamber. A second sensor is also disposed upstream of the mixing chamber. In the following, the terms "downstream" and "upstream" refer to the direction of gas flow from the fan of the gas heater to the burner or the direction of fuel gas flow from the fuel gas valve to the burner.

[0028] If the gas is air, the gas source corresponds to the surroundings from which the fan draws the air. The fuel gas can be stored in a fuel gas tank or a gas line or a gas grid, or can be generated on-site, such as by an electrolyser.

[0029] The burner may be a premixed burner, premix meaning that a mixture of fuel gas and gas is supplied to the burner. The combustion system may be an electronic combustion control or a pneumatic combustion control system.

[0030] The burner may be operated between minimum load and full load. The ratio of full load to minimum load may be at least 4. The ratio of gas to fuel gas in the mixture supplied to the burner may be as low as 1, for both, less than 4 at low load and less than 2 at full load.

[0031] According to an embodiment of the invention, the gas and the fuel gas are fed into the mixing chamber after a heat demand is requested. The heat demand can be requested for a heat need, in particular when hot water is required in a domestic environment. Furthermore, a heating process can be performed when at least one operating condition, in particular all operating conditions, are met. The heating process can be igniting a gas heater or changing the output of a burner. The term "perform" means that a heating process can be started or that a heating process already started can be continued.

[0032] The gas heater may comprise an actuator for setting the gas amount. The control unit may be configured to control the actuator for setting the gas amount if an operating condition of the gas heater is not met. The operating condition may include a check whether the determined gas amount corresponds to a predetermined gas amount. As mentioned above, the predetermined gas amount depends on the operation of the burner.

[0033] The actuator can optionally be integrated into the fan or a separate component for sucking in the gas. The actuator can also act on the fan, in particular to increase or decrease the fan speed to control the gas supplied into the chamber. The fan can be configured to have a variable fan speed. In particular, the actuator can control the fan speed when at least one operating condition is not met. Alternatively, the actuator can be part of or act on the gas valve. The control can control the flow cross-sectional area of ​​the gas valve and thus the amount of gas supplied to the mixing chamber.

[0034] The first sensor can be located upstream or downstream of the actuator and / or the gas valve. The first sensor can be located in a gas line where gas is supplied into the mixing chamber. Alternatively, the first sensor can be located in a bypass line to the gas line. Providing the first sensor in the bypass line provides a more accurate measurement compared to placement in the fuel gas line.

[0035] Furthermore, the gas heater may comprise a further actuator for setting the fuel gas amount. The further actuator may be integrated in the fuel gas valve or may be a separate component. The further actuator may be configured to act on the fuel gas valve to control the fuel gas supplied to the mixing chamber. In particular, the further actuator may control the fuel gas valve when a further operating condition is not met. The control unit may control the further actuator for setting the fuel gas amount if a further operating condition of the gas heater is not met. The further operating condition may include a check whether the determined fuel gas amount corresponds to a predetermined fuel gas amount. The determination whether the further operating condition is met may be performed after the determination whether the operating condition is met. In particular, the determination of the further operating condition is performed only when the operating condition is met.

[0036] If the heating process is to ignite a gas heater, in particular a burner, the control unit can control a further actuator based on a check whether the fuel gas quantity profile corresponds to a predefined ignition ramp. The ignition ramp is a predefined fuel gas profile that must be present so that the burner can ignite. The further actuator can be a fuel gas valve or act on the fuel gas valve. The second sensor can be arranged upstream or downstream of the further actuator or the fuel gas valve. The second sensor can be arranged in the fuel gas line, whereby the fuel gas is supplied into the mixing chamber. Alternatively, the second sensor can be arranged in a bypass line to the fuel gas line. Providing the second sensor in the bypass line results in a particularly accurate measurement compared to an arrangement in the fuel gas line.

[0037] The ignition lamps can be determined in the laboratory and adapted to gas and gas fuel settings in order to have the correct ignition in all environmental conditions. In the laboratory, the ignition behavior of the two burners is tested in extreme conditions: start-up of the cold system occurs when the temperature is below 10°C, and start-up of the hot system occurs when the temperature is above 25 or 30°C. In addition, the burners can also be tested in climatic chamber conditions where the temperature is below -40°C.

[0038] Ignition lamps can be judged based on these tests and the noise of the ignition. The requirement is that ignition must occur without noise so that the air to gas ratio is adjusted to match the settings that guarantee noise-free ignition.

[0039] Additionally, the length of the flue may also affect the ignition ramp, as the longer the flue, the greater the pressure loss, and so the ignition is adjusted to the length of the flue. Additionally, the ignition ramp can be adjusted to minimize heat input.

[0040] The controller can send a control signal to the actuator if the determined gas amount does not correspond to the predetermined gas amount, which is the case when the gas to fuel gas ratio of the gas mixture is not suitable for the intended operation of the burner and therefore needs to be adapted.

[0041] Based on the received control signal, the actuator increases or decreases the flow cross-sectional area of ​​the gas valve through which the gas supplied to the mixing chamber flows. Finally, the amount of gas can be easily controlled by the actuator.

[0042] The control unit can close the fuel gas valve if the determined fuel gas quantity does not correspond to a predetermined fuel gas quantity, in particular if the fuel gas quantity profile does not correspond to a predetermined ignition lamp. This is necessary for security reasons. In particular, the presence of a mixture of explosive gas and fuel gas should be avoided. The fuel gas valve can be an electronically controlled gas valve.

[0043] The gas heater may comprise a third sensor for detecting a flame signal. The third sensor may be an optical sensor, such as a UV sensor, that can easily detect whether a flame is present, in particular a flame generated by burning a gas containing 95% or more by mole of hydrogen. Alternatively, the third sensor may be a thermocouple, which is also capable of detecting the presence of a flame. The third sensor may be arranged in the burner. Alternatively, the third sensor may be arranged in a combustion chamber in which at least a part of the burner is located.

[0044] The control unit can determine whether another operating condition is met. This can be done after the further operating condition is met. This means that if the determined fuel gas amount corresponds to a predetermined fuel gas amount, a flame signal detection can be performed. The other operating condition includes checking whether a flame signal is present. If a flame signal is not detected, the fuel gas valve can be closed.

[0045] Furthermore, the gas heater may be equipped with a temperature sensor for measuring the temperature in the combustion chamber and / or the burner of the gas heater and / or in the flue gas pipe of the gas heater. The control unit may determine whether an additional operating condition is fulfilled when another condition is fulfilled. This means that the determination is made when a flame signal is detected. The control unit may check whether the measured temperature in the combustion chamber corresponds to a predetermined temperature or whether the determined increase in temperature in the combustion chamber exceeds a predetermined threshold value. In this case, the additional operating condition is fulfilled. If not, the heating process is stopped or adapted.

[0046] The gas volume can be determined after the fan starts to supply gas to the mixing chamber. The fuel gas volume can be determined after the fuel gas valve is opened. Therefore, the gas volume and / or fuel gas volume do not need to be measured all the time, but only when they need to be measured.

[0047] Also, the fuel gas quantity is determined after the gas quantity is determined. The fuel gas quantity can be determined when the determined gas quantity corresponds to a predetermined gas quantity. Thus, the risk of explosive mixture generation can be reduced.

[0048] According to an embodiment, the fan speed can be used for checking to verify whether the gas heater operates properly. In particular, the control unit can be adapted to check whether the fan speed corresponds to a predefined fan speed assigned to the determined gas quantity or is within a predefined fan speed range assigned to the determined gas quantity.

[0049] Such an operation makes it possible to easily check whether the first sensor is functioning well. In particular, considering the fan speed verifies the validity of the gas amount determination. If the first sensor is not functioning well, the fan speed does not correspond to the predetermined fan speed or is outside the predetermined fan speed range.

[0050] Thus, for example, if the fan speed during the ignition phase does not correspond to the predetermined fan speed or is outside the predetermined fan speed range, the boiler will shut down. The boiler will also shut down if the determined fuel gas does not correspond to the predetermined fuel gas quantity, especially if the determined fuel gas profile does not correspond to the predetermined ignition ramp.

[0051] The heating process can be performed when at least one condition is met: the fan speed corresponds to a predefined fan speed assigned to the determined gas quantity or is within a predefined fan speed range assigned to the determined gas quantity; otherwise, the heating process can be aborted.

[0052] In particular, the control unit may have at least one set gas flow rate in relation to the differential pressure, in particular in the form of a parameter curve which refers to a heating process, for example an ignition process. The gas flow rate may depend on the power of the boiler.

[0053] At least one parameter curve is stored in the control for the boiler. The parameter curve indicates that the gas flow rate is between 0% and 100% of the mixture fed to the burner depending on the burner power. The set gas flow rate is pre-determined, for example in a laboratory. The differential pressure is related to the expected fan speed in revolutions per minute (rpm). If the measured differential pressure and the measured rpm are within a predefined range, the heating process continues. The measurements are thus matched in relation to the pressure difference and the rpm.

[0054] The control unit is also adapted to check whether the electric signal supplied to the fuel gas valve corresponds to an electric signal assigned to a predetermined fuel gas amount or is in a predetermined electric signal range assigned to a predetermined fuel gas amount. This makes it possible to check whether the second sensor functions well and thus to prevent, for example, a situation in which the fuel gas amount supplied to the mixing chamber is much higher than the determined fuel gas amount. In particular, taking into account the electric signal, the validity of the determination of the fuel gas amount is verified.

[0055] The heating process can be performed when at least one condition is satisfied: the electrical signal provided to the fuel gas valve corresponds to an electrical signal assigned to a predetermined fuel gas quantity or is within a predetermined electrical signal range assigned to the predetermined fuel gas quantity; otherwise, the heating process can be discontinued.

[0056] The control unit may have at least one set fuel gas flow rate, in particular in the form of a parameter curve, with respect to the differential pressure which is indicative of the heating process, for example the ignition process. The set fuel gas flow rate is pre-determined, for example in a laboratory. The fuel gas flow rate may depend on the power of the boiler. For the boiler, at least one parameter curve is stored in the control unit. The parameter curve indicates a fuel gas flow rate which is between 0% and 100% of the mixture supplied to the burner, depending on the burner power. The differential pressure is related to an expected electrical signal which is supplied to the fuel gas valve. If the measured differential pressure and the measured electrical signal are within a predefined range, the heating process continues. Thus, the measured delta pressure and the electrical signal are linked and aligned.

[0057] In either case, the sensor signal is used to verify that the system is operating properly.

[0058] According to an embodiment of the present invention, the first sensor can be a flow sensor, in particular a mass flow sensor, and / or the second sensor can be a flow sensor, in particular a mass flow sensor. The flow sensor, in particular a mass flow sensor, measures a differential pressure, respectively. The gas amount and the fuel gas amount, respectively, are determined based on the measured differential pressure. Thus, the control unit can check whether the measured differential pressure corresponds to a predetermined differential pressure by determining whether the operating condition and / or further operating condition are met. Alternatively, the first sensor can be a volumetric flow sensor, and / or the second sensor can be a volumetric flow sensor.

[0059] In an embodiment, the gas heater is configured to use a gaseous fuel comprising 10 mol% to 100 mol%, in particular 50 mol% to 100 mol%, preferably 95 mol% to 100 mol%, more preferably 95 mol% to 98 mol% hydrogen. The gas heater according to the invention is not limited to the use of a gaseous fuel comprising hydrogen. Any type of fuel gas may be used as fuel, for example natural gas, methane, ethylene, propane, butane, coal gas, biogas, etc., mixtures thereof, and mixtures thereof further comprising hydrogen, or hydrogen, in particular pure (at least 98 mol%) hydrogen. In this embodiment, the gaseous fuel also comprises hydrogen, preferably 95 mol% or more hydrogen. However, any combination of hydrogen and, for example, natural gas may be used.

[0060] The gas heater can be used in or may be a boiler. The boiler comprises a combustion chamber and a heat exchanger capable of transferring heat generated by a burner of the gas heater to water. The burner of the gas heater is at least partially disposed inside the combustion chamber. The boiler may be a condensing boiler. Condensing boilers achieve high energy efficiency by condensing the water vapor of the exhaust gases to recover the latent heat of vaporization. This has the added advantage that condensing boilers use less fuel and electricity while emitting less CO2 compared to non-condensing boilers.

[0061] The boiler and / or gas heater may have communication means for communicating with a communication device, in particular a server. The communication may be established via a data line or wirelessly. The boiler and / or gas heater may be configured so that it can be remotely controlled. The control is possible, for example, by an application installed on a mobile device or a computer. This simplifies the control and / or maintenance of the boiler and / or gas heater.

[0062] According to an advantageous embodiment, a heating system is provided, which may comprise a fuel cell and / or a heat pump, preferably a gas absorption heat pump, and / or at least one photovoltaic (PV) module, which may be used, for example, to heat a fluid recirculating in the circuit of the heat pump.

[0063] A further advantageous embodiment is a computer program product comprising instructions for causing the controller to carry out the method of the invention when said program is executed by the controller. Furthermore, a data carrier is provided on which the computer program is stored and / or a data carrier signal is provided which transmits the computer program.

[0064] In the figures, the subject matter of the invention is illustrated diagrammatically, and identical or similarly acting elements are generally provided with the same reference numbers. [Brief description of the drawings]

[0065] [Figure 1] FIG. 1 is a schematic diagram of a gas heater. [Diagram 2] FIG. 2 is a schematic diagram of a portion of the gas heater shown in FIG. [Diagram 3] 4 is a flowchart of an ignition process of a gas heater. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] The gas heater 1 shown in FIG. 1 comprises a mixing chamber 2 in which gas and fuel gas are mixed. The mixed gas leaves the mixing chamber 2 and is supplied to a burner 12 of the gas heater 1. Furthermore, the gas heater 1 comprises a fan 13 arranged upstream of the mixing chamber 2 and used to draw in gas, in particular ambient air. A first sensor 7 is provided upstream of the fan 13 and is used to determine the gas amount. However, the first sensor 7 can also be provided downstream of the fan 13 (not shown). Thereby, the first sensor 7 detects the gas amount of the gas before it flows into the mixing chamber 2.

[0067] The gas heater 1 includes a fuel gas valve 6. The fuel gas valve 6 controls the flow of fuel gas into the mixing chamber 2. A second sensor 8 is disposed downstream of the fuel gas valve 6 and upstream of the mixing chamber 2. The second sensor 8 determines the amount of fuel gas before the fuel gas flows into the mixing chamber 2. The fuel gas is stored in a fuel gas tank (not shown).

[0068] The gas heater 1 also comprises a control unit 9 shown in Fig. 2. The control unit 9 is adapted to determine whether at least one operating condition of the gas heater 1 is fulfilled based on the determined gas amount and / or the determined fuel gas amount.

[0069] The gas heater 1 comprises a manifold 14 arranged downstream of the mixing chamber 2 and upstream of the burner 12. The manifold 14 is used to supply the mixed gas to the burner 12. The burner 12 is arranged in part in a combustion chamber 5, not shown in detail. The combustion chamber 5 can be part of a boiler, which also comprises a heat exchanger, not shown. The exchanged heat is used to exchange heat between the combustion chamber and water for heating the water. The flue gases leave the combustion chamber 5 as shown by the arrows.

[0070] The gas heater 1 comprises an ignition electrode 15 which is used to ignite the burner 12. In particular, a gas mixture fed to the burner 12 is ignited. After ignition, the burner 12 heats the combustion chamber 5.

[0071] A third sensor 16, in particular a detector, of the gas heater 1 is used to detect the flame of the burner. In particular, the third sensor 16 detects the presence or absence of a flame. A temperature sensor 17 of the gas heater 1 is used to measure the temperature which may be located in the burner and / or in the combustion chamber 5, the burner being preferred. Furthermore, the gas heater 1 may comprise a fourth sensor to measure one or more properties of the gas mixture (not shown). The composition of the mixed gas may be determined based on a sensor signal provided by the fourth sensor.

[0072] Figure 2 shows a schematic diagram of a part of the gas heater 1 shown in Figure 1. In particular, Figure 2 shows a part of the gas heater 1 of Figure 1, which is arranged in the dotted rectangle. In it, the first and second sensors 7, 8 are shown merely to illustrate that they are electrically connected with the control unit 9. The positions of the first and second sensors 7, 8 are shown in Figure 1. As is evident from Figure 2, the gas heater 1 comprises an actuator 3 and a further actuator 4. The actuator 3 is used to control the fan 3, in particular the speed of the fan, in order to set the amount of gas in the gas line 19.

[0073] The actuator 3 and the fan 13 are two separate components arranged at a distance from each other. In another, not shown, embodiment, the actuator 3 can be integrated in the fan 13. The further actuator 4 and the fuel gas valve 6 are two separate components arranged at a distance from each other. In another, not shown, embodiment, the further actuator 4 can be integrated in the fuel gas valve 6.

[0074] The gas line 19 is fluidly connected at one end to the mixing chamber 2. At another end, the gas line 19 is fluidly connected to the fan 13 shown in FIG. 1. A further actuator 4 is used to control the fluid gas valve 6 to set the amount of fuel gas in the fuel gas line 20. The fuel gas line 20 is fluidly connected at one end to the mixing chamber 2. At another end, the fuel gas line 20 is fluidly connected to a fuel gas tank, not shown.

[0075] The first sensor 7 is arranged upstream of the fan 13 as shown in FIG. 1, and the second sensor 8 is arranged downstream of the fuel gas valve 6. Both sensors 7, 8 are arranged upstream of the mixing chamber 2. In an alternative embodiment, not shown, the sensor 7 can be arranged downstream of the fan 13. As can be obtained from FIG. 2, both sensors 7, 8 and both actuators 3, 4 are electrically connected to a control unit 9 as shown by dotted lines. The control unit 9 determines whether at least one condition, in particular several conditions, are met based on the determined gas amount and the determined and determined fuel gas. The control unit 9 controls the actuator 3 and the other actuator 4 based on the determination result as shown by dotted lines.

[0076] 3 shows a flow chart of the heating process of the gas heater 1. The heating process is in this case an ignition process. However, the operation of the gas heater 1 according to the method of the invention is not limited to the ignition process of the burner 12.

[0077] In a first step S1, the heating process is started. This causes the control unit 9 to receive a heating request. Then, in a second step S2, the control unit 9 executes a sensor signal control and in a third step S3 verifies whether the sensor is operational and / or in an operational mode. If the verification is not successful, the heating process is stopped.

[0078] If the verification in the third step S3 is successful, the fan 13 is started in a fourth step S4. After the fan has been started, in a fifth step S5 the first sensor 7 starts to determine the gas quantity and sends a sensor signal to the control unit 9. In a sixth step S6 the control unit 9 checks whether the operating conditions of the gas heater 1 are fulfilled. In particular, the control unit 9 checks whether the determined gas quantity corresponds to a predetermined gas quantity. Thereby the control unit 9 checks whether the measured differential pressure corresponds to a predetermined differential pressure. The predetermined gas quality depends on the power that the burner 12 has to supply.

[0079] If the determined gas amount does not correspond to the predetermined gas amount, the control unit 9 sends a control signal to the actuator 3 and steps S5, S6 are repeated. The mixing chamber 2 is allowed to post-ventilate before a control signal is sent to the actuator 3. If, after a predetermined amount of trials, the determined gas amount does not correspond to the predetermined gas amount, the heating process is aborted.

[0080] However, if the control unit 9 determines in the sixth step S6 that the determined gas amount corresponds to the predetermined gas amount, the ignition electrode 15 sparks in the seventh step S7. Then, in the eighth step S8, the fuel gas valve is opened and the second sensor 8 starts to determine the fuel gas amount.

[0081] In a ninth step S9, the control unit 9 determines whether further operating conditions are met. In particular, the control unit 9 checks whether the determined fuel gas amount corresponds to a predetermined fuel gas amount. In particular, the control unit 9 checks whether the determined ignition ramp corresponds to a predetermined ignition ramp. In this case, the heating process is continued in a tenth step S10.

[0082] In a tenth step S10, the control unit 9 determines whether other operating conditions are met. In particular, the control unit 9 determines whether there is a flame or not. If the third sensor 16 detects the presence of a flame, in an eleventh step S11, the temperate sensor 17 measures the temperature of the combustion chamber 5. Also, in an eleventh step S11, the control unit 9 determines whether additional operating conditions are met. In particular, the control unit 9 checks whether the measured temperature is above a threshold value. In this case, the heating process is successfully terminated.

[0083] In the ninth step S9, if the control unit 9 determines that the determined fuel gas amount does not correspond to the predetermined fuel gas amount and / or the measured ignition ramp does not correspond to the predetermined ignition ramp, the fuel gas valve 6 is closed. Similarly, in the tenth step S10, if no flame is detected by the third sensor 16, the fuel gas valve 6 is closed. In either case, the mixing chamber 2 is post-ventilated and the process steps S7-S10 are repeated. However, as described above for the process steps S5 and S6, the process steps S7-S10 are repeated only for a predetermined amount of trials. If the aforementioned further conditions, other conditions and additional conditions are not met within said predetermined amount of trials, the heating process is aborted.

[0084] When the control unit 9 determines in the eleventh step S11 that the temperature does not reach the threshold value, it stops the heating process. [Explanation of symbols]

[0085] 1 Gas heater 2 Mixing chamber 3 Actuator 4 Further Actuators 5. Combustion chamber 6 Fuel Gas Valve 7 First Sensor 8 Second Sensor 9. Control Unit 12 Burner 13 Fan 14 Manifold 15 Ignition electrode 16 3rd Sensor 17 Temperature Sensor 19 Gas Line 20 Fuel Gas Line S1-S11 Steps 1 to 11

Claims

1. A method for operating a gas heater (1), in particular for providing central heating and / or for providing domestic hot water, in particular a gas boiler, in particular a condensing boiler, comprising the steps of: supplying gas and fuel gas into a mixing chamber (2) of the gas heater (1) and supplying the mixed gas from the mixing chamber (2) to a burner (12) of the gas heater (1); measuring a differential pressure per unit time and / or presenting a sensor signal to a control unit in order to determine a quantity of gas defined by a volume per unit time or a mass per unit time before the gas is fed into the mixing chamber (2); measuring a differential pressure per unit time and / or presenting a sensor signal to a control unit to determine the amount of fuel gas defined by volume per unit time or mass per unit time before the fuel gas is supplied to the mixing chamber (2); determining whether an operating condition of the gas heater (1) is fulfilled based on the determined gas amount, the operating condition comprising checking whether the determined gas amount corresponds to a predetermined gas amount; determining whether further operating conditions of the gas heater (1) are fulfilled based on the determined fuel gas amount, the further operating conditions comprising checking whether the determined fuel gas amount corresponds to a predetermined fuel gas amount; wherein determining the further operating condition occurs when the operating condition is satisfied.

2. a. the actuator (3) for setting the gas quantity is controlled when said one operating condition is not fulfilled, and / or b) the actuator (3) for setting the gas quantity is controlled based on a check whether the determined gas quantity corresponds to a predetermined gas quantity, and / or The method according to claim 1, characterized in that the actuator (3) controls the speed of a fan to control the gas supplied into the chamber of the gas heater (1) when the one operating condition is not met.

3. 3. The method according to claim 2, characterized in that a control signal is sent to the actuator (3) when the determined gas quantity does not correspond to the predetermined gas quantity.

4. a. a further actuator (4) for setting the fuel gas quantity is controlled when a further operating condition is not met, and / or b) the further actuator (4) for setting the fuel gas quantity is controlled based on checking whether the determined fuel gas quantity corresponds to a predefined fuel gas quantity, in particular whether the fuel gas quantity profile corresponds to a predefined ignition ramp, and / or 4. The method according to claim 1, further comprising controlling the fuel gas valve when a further operating condition is not met.

5. a. determining whether another operating condition is met, the other condition including said checking whether a flame signal is present; and / or 5. The method according to claim 1, further comprising determining whether a further operating condition is satisfied when the determined fuel gas amount corresponds to a predetermined fuel gas amount.

6. The fuel gas valve (6), a. when the determined fuel gas quantity does not correspond to a predetermined fuel gas quantity, in particular when the fuel gas quantity profile does not correspond to a predetermined ignition ramp; and / or b. If no flame signal is detected 6. The method according to claim 4 or 5, characterized in that the method is closed to

7. a. It is determined whether an additional operating condition is met, said additional operating condition comprising a check whether the measured temperature of the combustion chamber (5) of said gas heater (1) or the determined temperature rise of said combustion chamber (5) exceeds a predefined threshold value; and / or b. the amount of gas is determined after the fan (13) starts to supply gas to the mixing chamber (2); and / or c. the fuel gas quantity is determined after the fuel gas valve (6) is opened; and / or d. the fuel gas quantity is determined after the gas quantity is determined; and / or 7. The method according to claim 1, wherein the fuel gas quantity is determined when the determined gas quantity corresponds to a predetermined gas quantity.

8. a. checking whether the fan speed corresponds to a predefined fan speed assigned to said determined gas quantity or is within a range of predefined fan speeds assigned to said determined gas quantity; and / or A method according to any one of claims 1 to 7, characterized in that it is checked whether the electric signal presented to the fuel gas valve (6) corresponds to an electric signal assigned to said predetermined fuel gas quantity or is within a range of predetermined electric signals assigned to said predetermined fuel gas quantity.

9. the heating process is performed when the fan speed corresponds to a predefined fan speed assigned to the determined gas quantity or is within a range of predefined fan speeds assigned to the determined gas quantity and when the at least one condition is met; and / or The method according to claim 8, characterized in that the heating process is carried out when the electric signal presented to the fuel gas valve (6) corresponds to an electric signal assigned to the predetermined fuel gas amount or is within a predetermined range of electric signals assigned to the predetermined fuel gas amount and when the at least one condition is satisfied.

10. The present invention relates to a gas supply system including a mixing chamber (2) for mixing a gas and a fuel gas, a burner (12) arranged downstream of the mixing chamber (2) and capable of supplying the mixed gas of the mixing chamber (2), a first sensor (7) for measuring a differential pressure per unit time and / or for providing a sensor signal to a control unit for determining the amount of the gas determined by the volume per unit time or the mass per unit time of the gas supplied to the mixing chamber, and a second sensor (7) for measuring the differential pressure per unit time and / or for providing a sensor signal to a control unit for determining the amount of the fuel gas determined by the volume per unit time or the mass per unit time of the fuel gas supplied to the mixing chamber. a second sensor (8) for indicating whether the determined amount of gas is within a predetermined range of the determined amount of fuel gas, and a control unit (9) adapted to determine whether one operating condition of the gas heater (1) is satisfied based on the determined amount of gas, the operating condition including a check whether the determined amount of gas corresponds to a predetermined amount of gas, and to determine whether a further operating condition of the gas heater (1) is satisfied based on the determined amount of fuel gas, the further operating condition including a check whether the determined amount of fuel gas corresponds to a predetermined amount of fuel gas, and the determination of the further operating condition is performed when the operating condition is satisfied.

11. a. the gas heater (1) is provided with a temperature sensor (17) for measuring the temperature of the combustion chamber (5) and / or the burner (12), and / or b) said control unit (9) is adapted to check whether the fan speed corresponds to a predefined fan speed assigned to said determined gas quantity or is within a range of predefined fan speeds assigned to said determined gas quantity; and / or c) the control unit (9) is adapted to check whether the electrical signal presented to the fuel gas valve (6) corresponds to an electrical signal assigned to the predetermined fuel gas quantity or is within a predetermined range of electrical signals assigned to the predetermined fuel gas quantity; and / or d) The gas heater (1) according to claim 10, characterized in that the gas heater (2) is configured to use a fuel gas containing at least 10 mol %, in particular at least 95 mol % hydrogen.

12. 12. A boiler for heating a liquid, in particular water, in particular a condensing boiler, comprising a gas heater (2) according to claim 11 and a heat exchanger having a combustion chamber, characterized in that the burner (12) of the gas heater (1) is at least partially arranged inside the combustion chamber.

13. 13. A heating system comprising a gas heater according to claim 10 or 11 or a boiler according to claim 12, further comprising a fuel cell and / or a heat pump, preferably a gas absorption heat pump, and / or at least one photovoltaic (PV) module.

14. 13. Use of a gas heater according to claim 10 or 11 or a boiler according to claim 12 in a hydrogen or hydrogen-containing fuel gas heating application or in a natural gas heating application.

15. A computer program product comprising instructions which, when executed by a control unit, cause the control unit to carry out the method according to any one of claims 1 to 9.

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