EP4180719A1 - An air-gas mixture burning appliance with a variable ignition safety time - Google Patents
An air-gas mixture burning appliance with a variable ignition safety time Download PDFInfo
- Publication number
- EP4180719A1 EP4180719A1 EP22202347.5A EP22202347A EP4180719A1 EP 4180719 A1 EP4180719 A1 EP 4180719A1 EP 22202347 A EP22202347 A EP 22202347A EP 4180719 A1 EP4180719 A1 EP 4180719A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- gas
- air
- burning
- unit
- gas mixture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000203 mixture Substances 0.000 title claims abstract description 127
- 238000009825 accumulation Methods 0.000 claims abstract description 12
- 231100001261 hazardous Toxicity 0.000 claims abstract description 11
- 230000003466 anti-cipated effect Effects 0.000 claims abstract description 9
- 230000037361 pathway Effects 0.000 claims description 38
- 238000011144 upstream manufacturing Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 16
- 230000001105 regulatory effect Effects 0.000 claims description 10
- 239000007789 gas Substances 0.000 description 324
- 238000001514 detection method Methods 0.000 description 4
- 230000003111 delayed effect Effects 0.000 description 3
- 230000007257 malfunction Effects 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000004880 explosion Methods 0.000 description 2
- 239000002737 fuel gas Substances 0.000 description 2
- 239000008240 homogeneous mixture Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000003915 liquefied petroleum gas Substances 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000037452 priming Effects 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/24—Preventing development of abnormal or undesired conditions, i.e. safety arrangements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/24—Preventing development of abnormal or undesired conditions, i.e. safety arrangements
- F23N5/242—Preventing development of abnormal or undesired conditions, i.e. safety arrangements using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/72—Safety devices, e.g. operative in case of failure of gas supply
- F23D14/725—Protection against flame failure by using flame detection devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/002—Regulating fuel supply using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/20—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays
- F23N5/203—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2900/00—Special features of, or arrangements for fuel supplies
- F23K2900/05002—Valves for gaseous fuel supply lines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2227/00—Ignition or checking
- F23N2227/02—Starting or ignition cycles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2229/00—Flame sensors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2231/00—Fail safe
- F23N2231/06—Fail safe for flame failures
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2231/00—Fail safe
- F23N2231/10—Fail safe for component failures
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2231/00—Fail safe
- F23N2231/12—Fail safe for ignition failures
Definitions
- the present invention relates to an air-gas mixture burning appliance.
- the air-gas mixture burning appliance comprises a controller, a burning unit for burning a combustible air-gas mixture, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, and a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit.
- the present invention relates to a method of operating an air-gas mixture burning appliance that comprises a controller, a burning unit for burning a combustible air-gas mixture, a flame detector for sensing a presence of a flame in the burning unit, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, and a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit.
- an air-gas mixture burning appliance having a burning unit, an air-gas mixing unit, and a gas valve is known. More specifically, known air-gas mixture burning appliances usually mix air and gas directly before the burning unit. During the ignition phase, the combustible air-gas mixture enters the burning unit where it is ignited. However, sometimes the combustible air-gas mixture is not ignited immediately, which can lead to a build-up of the combustible air-gas mixture after the burning unit. A delayed ignition, which refers to igniting the built-up combustible air-gas mixture, usually leads to an explosion that may damage internal components of the air-gas mixture burning appliance and endanger the surrounding environment.
- the maximum allowed opening time of the gas valve without a flame being detected is limited to a short time period, which is sometimes also referred to as the ignition safety time.
- the ignition safety time is usually a fixed duration of time that is predetermined.
- gas refers to any fuel in gaseous form that, when mixed with air, forms a combustible air-gas mixture.
- gases include hydrogen, propane, butane, methane, liquefied petroleum gas, etc.
- air refers to any suitable oxidizer that may be mixed with a fuel gas to form a combustible air-gas mixture.
- the present invention relates to an air-gas mixture burning appliance, comprising a burning unit for burning a combustible air-gas mixture, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit, and a controller that is adapted for determining a variable ignition safety time for an ignition phase of the burning unit by selecting from at least two different durations of time, wherein the controller determines the variable ignition safety time as an anticipated maximum duration of time that elapses between an opening of the gas valve and a closing of the gas valve for avoiding a hazardous accumulation of the combustible air-gas mixture in the burning unit.
- the inventive air-gas mixture burning appliance may be able to adjust the ignition safety time and adapt to different modes of operation.
- the air-gas mixture burning appliance further comprises a secured gas pathway that is arranged between the gas valve and the air-gas mixing unit and is adapted for providing the gas from the gas valve to the air-gas mixing unit, and wherein the controller determines the variable ignition safety time based on an inferred concentration of the gas in the secured gas pathway.
- the controller can select the variable ignition safety time based on whether the secured gas pathway is already filled with a gas or whether the secured gas pathway is filled with air at the beginning of the ignition phase.
- the controller determines the variable ignition safety time based at least on the type of the gas.
- the inventive air-gas mixture burning appliance may be operated with different gas types.
- the controller determines the variable ignition safety time by selecting from a predetermined number of at least three different discrete durations of time, wherein all values of the at least three different discrete durations of time are smaller than or equal to a predetermined maximum ignition safety time.
- the controller may have a simple design and be low cost.
- the controller determines the variable ignition safety time by selecting from a continuous range of values, wherein all values in the continuous range of values are smaller than or equal to a predetermined maximum ignition safety time.
- the controller may fine-tune the ignition safety time and react to the combination of multiple parameters that may have an influence on the ignition safety time.
- the air-gas mixture burning appliance further comprises a flame detector for sensing a presence of a flame in the burning unit, wherein the controller determines the variable ignition safety time based at least on an elapsed time since the flame detector previously sensed a flame in the burning unit.
- the inventive air-gas mixture burning appliance may reliably predict the concentration of the gas in the secured gas pathway at the beginning of the ignition phase.
- the controller directs the gas valve to shut off if, during the ignition phase of the burning unit, the gas valve is open and the flame detector fails to sense a flame in the burning unit during the variable ignition safety time.
- the controller ensures the prevention of a dangerous build-up of the combustible air-gas mixture after the burning unit and a related delayed ignition.
- the controller triggers a warning and/or puts the air-gas mixture burning appliance into one or more of a safe state, a restricted state, or a non-operational state, if during a predetermined number of consecutive ignition phases of the burning unit, the gas valve is open and the flame detector fails to sense a flame in the burning unit during the variable ignition safety time.
- an operator may be alerted and/or the risks associated with a malfunction of the air-gas mixture burning appliance may be reduced.
- a method of operating an air-gas mixture burning appliance that comprises a controller, a burning unit for burning a combustible air-gas mixture, a flame detector for sensing a presence of a flame in the burning unit, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, and a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit, comprises determining with the controller, a variable ignition safety time for an ignition phase of the burning unit by determining an anticipated maximum duration of time that can safely elapse between an opening of the gas valve and a closing of the gas valve for avoiding a hazardous accumulation of the combustible air-gas mixture in the burning unit.
- the inventive method may operate an air-gas mixture burning appliance by adjusting the ignition safety time and adapt to different modes of operation.
- the method further comprises directing with the controller, the gas valve to shut off if, during the ignition phase of the burning unit, the gas valve is open and no flame is detected in the burning unit during the variable ignition safety time.
- the inventive method may prevent a hazardous build-up of the combustible air-gas mixture in the burning unit of the air-gas mixture burning appliance.
- the air-gas mixture burning appliance further comprises a secured gas pathway that is arranged between the gas valve and the air-gas mixing unit and is adapted for providing the gas from the gas valve to the air-gas mixing unit, and determining the variable ignition safety time further comprises determining the variable ignition safety time based at least on the type of the gas, and/or on an inferred concentration of the gas in the secured gas pathway, and/or on an elapsed time since a flame detector previously sensed a flame in the burning unit.
- the inventive method may consider different parameters when determining the ignition safety time.
- the method further comprises triggering with the controller, a warning and/or putting, with the controller, the air-gas mixture burning appliance into one or more of a safe state, a restricted state or a non-operational state, if, during a pre-determined number of consecutive ignition phases of the burning unit, the gas valve is open and no flame is detected in the burning unit during the variable ignition safety time.
- an operator may be alerted and/or the risks associated with a malfunction of the air-gas mixture burning appliance may be reduced.
- Fig. 1 shows an exemplary air-gas mixture burning appliance 100 with a burning unit 120 for burning a combustible air-gas mixture 130, an air-gas mixing unit 110, a gas valve 194, a flame detector 150, and a controller 140.
- the air-gas mixture burning appliance 100 may be used in a boiler or, more generally, in a building heating system.
- the air-gas mixing unit 110 is arranged upstream of the burning unit 120 and is adapted for mixing of air 111 and gas 119 to form the combustible air-gas mixture 130.
- the combustible air-gas mixture 130 is a homogenous mixture of the air 111 and the gas 119.
- the air-gas mixing unit 110 includes an air supply unit and a gas supply unit.
- the air supply unit includes a fan 114 that may be operated with an adaptable fan speed and/or within predetermined ranges of fan speeds.
- the fan 114 may push air 111 into the air-gas mixing unit 110. If desired, and as shown in Fig. 2 , the fan 114 may draw the combustible air-gas mixture 130 from the air-gas mixing unit 110.
- the gas supply unit may include the gas valve 194.
- the gas valve 194 is arranged upstream of the air-gas mixing unit 110 and is adapted for regulating a flow of the gas 119 to the air-gas mixing unit 110.
- a secured gas pathway 116 is arranged between the gas valve 194 and the air-gas mixing unit 110 and is adapted for providing the gas 119 from the gas valve 194 to the air-gas mixing unit 110.
- the air supply unit and the gas supply unit may be interconnected via a mixer 118 which forms a corresponding discrete point of mixing.
- the combustible air-gas mixture 130 is formed at the discrete point of mixing and guided via the mixer 118 and the combustible air-gas pathway 132 to the burning unit 120.
- the burning unit 120 is provided with a burner surface 124 that is arranged downstream of the air-gas mixing unit 110 such that the combustible air-gas mixture 130 flows towards the burner surface 124.
- the combustible air-gas mixture 130 is burned by the burning unit 120 and, more specifically, at the burner surface 124.
- the combustible air-gas mixture 130 from the air-gas mixing unit 110 may be ignited in the burning unit 120 at the burner surface 124.
- the resulting flame 122 is illustratively stabilised against the burner surface 124.
- the flame detector 150 is provided for sensing presence of a flame 122 in the burning unit 120.
- the flame detector 150 is suitable for determining whether a flame 122 is present at the burner surface 124 in the burning unit 120.
- suitable flame detection techniques that may be used with the flame detector 150 are well-known to the person skilled in the art and are, therefore, not described in more detail, for brevity and conciseness.
- the flame detector 150 may use any suitable sensing element for sensing presence of the flame 122 in the burning unit 120.
- the flame detector 150 may be connected to the controller 140. If desired, the flame detector 150 may generate and/or provide a flame detection signal 162 to the controller 140 based on whether the flame detector 150 senses the presence of a flame 122 in the burning unit 120 or fails to sense the presence of a flame 122 in the burning unit 120.
- the controller 140 may determine whether a flame 122 is present in the burning unit 120 by comparing the detected flame signal 160 with a predetermined flame detection threshold.
- the controller 140 may be connected to the gas valve 194.
- the controller 140 may receive a control signal 182 from the gas valve 194.
- the control signal 182 may be indicative of the status of the gas valve 194.
- the controller signal 182 may indicate whether the gas valve 194 is open or closed.
- the controller 140 may send an actuator signal 183 to the gas valve 194. If desired, the actuator signal 183 may direct the gas valve 194 to open and/or to close. For example, at the beginning of an ignition phase, the controller 140 may direct the gas valve 194 to open.
- the controller 140 tracks the duration of time between the opening of the gas valve 194 and the detection of a flame signal 160 at the burning unit 120.
- a delayed ignition which refers to igniting a hazardous accumulation of the combustible air-gas mixture 130 and which usually leads to an explosion that may damage internal components of the air-gas mixture burning appliance 100 and endanger the surrounding environment
- the maximum allowed opening time of the gas valve 194 without a flame 122 being detected is limited to a short period of time, which is sometimes also referred to as the ignition safety time.
- the gas valve 194 needs to be open for a minimum opening time.
- the minimum opening time is defined as the time that is required for the gas 119 to flow from the gas valve 194 through the secured gas pathway 116 to the air-gas mixing unit 110 and from there, as a combustible air-gas mixture 130 to the burner surface 124, where a sufficient quantity of the combustible air-gas mixture 130 is required to accumulate such that a reliable ignition of the flame 122 is ensured.
- the time between the opening of the gas valve 194 and the accumulation of a quantity of the combustible air-gas mixture 130 in the burning unit 120 that is sufficient for a sustained ignition may depend on the concentration of the gas 119 in the secured gas pathway 116 at the opening of the gas valve 194.
- the air-gas mixture burning appliance 100 were to stop burning gas 119, but after a short period of time be re-lit, then the secured gas pathway 116 would still be filled with gas 119, and the combustible air-gas pathway 132 would still be filled with the combustible air-gas mixture 130, and, as a result, a flame 122 could be established comparatively quickly at the burner surface 124.
- the concentration of the gas 119 in the secured gas pathway 116 and in the combustible air-gas pathway 132 decays overtime.
- the secured gas pathway 116 and the combustible air-gas pathway 132 is nominally filled with air and contains a negligible concentration of the gas 119 at the start of the ignition sequence.
- the nominally air that is present in the secured gas pathway 116 and in the combustible air-gas pathway 132 must be displaced by gas 119 that is streaming through the opened gas valve 194.
- This process of re-priming the secured gas pathway 116 and the combustible air-gas pathway 132 takes some time, which may depend, for example, on the flow rate of nominally air and the volume of the consecutive pathways 116, 132.
- the controller 140 is adapted for determining a variable ignition safety time for an ignition phase of the burning unit 120 by selecting from at least two different durations of time. Thereby, the controller 140 determines the variable ignition safety time as an anticipated maximum duration of time that elapses between an opening of the gas valve 194 and a closing of the gas valve 194 for avoiding a hazardous accumulation of the combustible air-gas mixture 130 in the burning unit 120.
- the controller 140 may determine the variable ignition safety time based on an inferred concentration of the gas 119 in the secured gas pathway 116.
- the decay of the concentration of the gas 119 and/or the time to reprime the secured gas pathway 116 and the combustible air-gas pathway 132 may depend on the type of gas 119.
- the difference in density of hydrogen or any other fuel gas that is less dense than air may result in an exacerbated delay in the appearance of a flame 122 at the burner surface 124. Therefore, the controller 140 may determine the variable ignition safety time based at least on the type of the gas 119.
- the controller 140 may determine the variable ignition safety time based at least on an elapsed time since the flame detector 150 previously sensed a flame 122 in the burning unit 120.
- the controller 140 may determine the longest duration of time after the opening of the gas valve 194 that it is safe to wait for a flame 122 to appear in the burning unit 120 before the gas valve 194 must be closed to prevent an excessive accumulation of the combustible air-gas mixture 130 in the burning unit 120.
- This longest duration of time is sometimes also referred to as a predetermined maximum ignition safety time.
- the controller 140 may determine the variable ignition safety time by selecting from a predetermined number of at least three different discrete durations of time wherein all values of the at least three different discrete durations of time are smaller than or equal to a predetermined maximum ignition safety time.
- the controller 140 may determine the variable ignition safety time by selecting from a continuous range of values, wherein all values in the continuous range of values are smaller than or equal to a predetermined maximum ignition safety time.
- the controller 140 may direct the gas valve 194 to shut off if, during the ignition phase of the burning unit 120, the gas valve 194 is open and the flame detector 150 fails to sense a flame 122 in the burning unit 120 during the variable ignition safety time.
- the controller 140 may direct the gas valve 194 to close using actuator signal 183.
- the controller 140 may trigger a warning, if during a predetermined number of consecutive ignition phases of the burning unit 120, the gas valve 194 is open and the flame detector 150 fails to sense a flame 122 in the burning unit 120 during the variable ignition safety time.
- the warning may be any signal that alerts an operator about the malfunction of the air-gas mixture burning appliance 100.
- the warning may be a visual signal (e.g., a flashing display, a color coded display, a message, etc.), an audio signal (e.g., a warning message, a beeping signal, etc.), a tactile signal (e.g., a vibration), or any combination thereof.
- the controller 140 may put the air-gas mixture burning appliance 100 into one or more of a safe state, a restricted state, or a non-operational state, if during a predetermined number of consecutive ignition phases of the burning unit 120, the gas valve 194 is open and the flame detector 150 fails to sense a flame 122 in the burning unit 120 during the variable ignition safety time.
- the controller 140 may trigger a warning and put the air-gas mixture burning appliance 100 into one or more of a safe state, a restricted state, or a non-operational state, if during a predetermined number of consecutive ignition phases of the burning unit 120, the gas valve 194 is open and the flame detector 150 fails to sense a flame 122 in the burning unit 120 during the variable ignition safety time.
- Fig. 2 shows a schematic view of an air-gas mixture burning appliance 100 having a fan 114 downstream of an air-gas mixer 118 and an air flow channel 250 to a reference pressure port 242 of a gas valve 194.
- the air-gas mixture burning appliance 100 may include an air inlet for providing air 111, a gas inlet 117 for providing gas 119, and a flue outlet 155 for the evacuation of exhaust gas 152.
- the air-gas mixture burning appliance 100 may further include an air-gas mixing unit 110, a burning unit 120, and a heat exchanger 170.
- the air-gas mixing unit 110 is preferably adapted for mixing of air 111 and gas 119 to form a combustible air-gas mixture 130.
- the combustible air-gas mixture 130 is a homogenous mixture of the air 111 and the gas 119.
- the burning unit 120 is provided with a burner surface 124 that is arranged downstream of the air-gas mixing unit 110 such that the combustible air-gas mixture 130 flows towards the burner surface 124.
- the fan 114 may drive the combustible air-gas mixture 130 through the combustible air-gas pathway 132 towards the burner surface 124.
- the combustible air-gas mixture 130 is burned by the burning unit 120 and, more specifically, at the burner surface 124.
- the heat exchanger 170 may transfer the heat that is generated at the burner surface 124 to another medium.
- the heat exchanger 170 may transfer the heat that is generated at the burner surface 124 to water in a water circuit.
- the flue outlet 155 may evacuate the exhaust gas 152 from the air-gas mixture burning appliance 100.
- the gas valve 194 may include a reference pressure port 242.
- the air flow channel 250 is adapted for providing the flow of the air 111 to the reference pressure port 242, and the gas valve 194 is adapted for regulating the flow of the gas 119 based on the pressure of the flow of the air 111 at the reference pressure port 242.
- the controller 140 is adapted for determining a variable ignition safety time for an ignition phase of the burning unit 120 by selecting from at least two different durations of time. Thereby, the controller 140 determines the variable ignition safety time as an anticipated maximum duration of time that elapses between an opening of the gas valve 194 and a closing of the gas valve 194 for avoiding a hazardous accumulation of the combustible air-gas mixture 130 in the burning unit 120.
- the controller 140 may send an actuator signal 183 to the gas valve 194. If desired, the actuator signal 183 may direct the gas valve 194 to open and/or to close. For example, at the beginning of an ignition phase, the controller 140 may direct the gas valve 194 to open.
- the controller 140 may direct the gas valve 194 to shut off if, during the ignition phase of the burning unit 120, the gas valve 194 is open and the flame detector 150 fails to sense a flame 122 in the burning unit 120 during the variable ignition safety time.
- the controller 140 may direct the gas valve 194 to close using actuator signal 183.
- actuator signal 183 may override the reference pressure port 242 of the gas valve 194.
- Fig. 3 shows a flowchart illustrating a method 300 of operating an air-gas mixture burning appliance.
- the air-gas mixture burning appliance comprises a burning unit for burning a combustible air-gas mixture, a flame detector for sensing a presence of a flame in the burning unit, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, and a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 comprises a burning unit 120 for burning a combustible air-gas mixture 130, a flame detector 150 for sensing a presence of a flame 122 in the burning unit 120, an air-gas mixing unit 110 that is arranged upstream of the burning unit 120 and is adapted for mixing of air 111 and gas 119 to form the combustible air-gas mixture 130, and a gas valve 194 that is arranged upstream of the air-gas mixing unit 110 and is adapted for regulating a flow of the gas 119 to the air-gas mixing unit 110.
- the air-gas mixture burning appliance determines, with a controller, a variable ignition safety time for an ignition phase of the burning unit by determining an anticipated maximum duration of time that can safely elapse between an opening of the gas valve and a closing of the gas valve for avoiding a hazardous accumulation of the combustible air-gas mixture in the burning unit.
- air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may use controller 140 to determine a variable ignition safety time for an ignition phase of the burning unit 120 by determining an anticipated maximum duration of time that can safely elapse between an opening of the gas valve 194 and a closing of the gas valve 194 for avoiding a hazardous accumulation of the combustible air-gas mixture 130 in the burning unit 120.
- the air-gas mixture burning appliance directs, with the controller, the gas valve to shut off if, during the ignition phase of the burning unit, the gas valve is open and no flame is detected in the burning unit during the variable ignition safety time.
- air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may use controller 140 to direct the gas valve 194 to shut off if, during the ignition phase of the burning unit 120, the gas valve 194 is open and no flame 122 is detected in the burning unit 120 during the variable ignition safety time.
- the air-gas mixture burning appliance may further comprise a secured gas pathway that is arranged between the gas valve and the air-gas mixing unit and is adapted for providing the gas from the gas valve to the air-gas mixing unit.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may comprise a secured gas pathway 116 that is arranged between the gas valve 194 and the air-gas mixing unit 110 and is adapted for providing the gas 119 from the gas valve 194 to the air-gas mixing unit 110.
- the operation of determining 310 the variable ignition safety time may further comprise the operation of determining the variable ignition safety time based at least on the type of the gas, and/or on an inferred concentration of the gas in the secured gas pathway, and/or on an elapsed time since a flame detector previously sensed a flame in the burning unit.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may determine the variable ignition safety time based at least on the type of the gas 119.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may determine the variable ignition safety time based at least on an inferred concentration of the gas 119 in the secured gas pathway 116.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may determine the variable ignition safety time based at least on an elapsed time since a flame detector 150 previously sensed a flame 122 in the burning unit 120.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may determine the variable ignition safety time based at least on the type of the gas 119, and an inferred concentration of the gas 119 in the secured gas pathway 116.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may determine the variable ignition safety time based at least on the type of the gas 119 and an elapsed time since a flame detector 150 previously sensed a flame 122 in the burning unit 120.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may determine the variable ignition safety time based at least on an inferred concentration of the gas 119 in the secured gas pathway 116, and an elapsed time since a flame detector 150 previously sensed a flame 122 in the burning unit 120.
- the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may determine the variable ignition safety time based at least on the type of the gas 119, and on an inferred concentration of the gas 119 in the secured gas pathway 116, and on an elapsed time since a flame detector 150 previously sensed a flame 122 in the burning unit 120.
- the controller of the air-gas mixture burning appliance may further trigger a warning and/or put the air-gas mixture burning appliance into one or more of a safe state, a restricted state or a non-operational state, if, during a predetermined number of consecutive ignition phases of the burning unit, the gas valve is open and no flame is detected in the burning unit during the variable ignition safety time.
- the controller 140 of the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may trigger a warning, if, during a predetermined number of consecutive ignition phases of the burning unit 120, the gas valve 194 is open and no flame 122 is detected in the burning unit 120 during the variable ignition safety time.
- the controller 140 of the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may put, the air-gas mixture burning appliance 100 into one or more of a safe state, a restricted state or a non-operational state, if, during a predetermined number of consecutive ignition phases of the burning unit 120, the gas valve 194 is open and no flame 122 is detected in the burning unit 120 during the variable ignition safety time.
- the controller 140 of the air-gas mixture burning appliance 100 of Fig. 1 or Fig. 2 may trigger a warning and put, the air-gas mixture burning appliance 100 into one or more of a safe state, a restricted state or a non-operational state, if, during a predetermined number of consecutive ignition phases of the burning unit 120, the gas valve 194 is open and no flame 122 is detected in the burning unit 120 during the variable ignition safety time.
Abstract
Description
- The present invention relates to an air-gas mixture burning appliance. The air-gas mixture burning appliance comprises a controller, a burning unit for burning a combustible air-gas mixture, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, and a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit. Furthermore, the present invention relates to a method of operating an air-gas mixture burning appliance that comprises a controller, a burning unit for burning a combustible air-gas mixture, a flame detector for sensing a presence of a flame in the burning unit, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, and a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit.
- From the state of the art, an air-gas mixture burning appliance having a burning unit, an air-gas mixing unit, and a gas valve is known. More specifically, known air-gas mixture burning appliances usually mix air and gas directly before the burning unit. During the ignition phase, the combustible air-gas mixture enters the burning unit where it is ignited. However, sometimes the combustible air-gas mixture is not ignited immediately, which can lead to a build-up of the combustible air-gas mixture after the burning unit. A delayed ignition, which refers to igniting the built-up combustible air-gas mixture, usually leads to an explosion that may damage internal components of the air-gas mixture burning appliance and endanger the surrounding environment.
- Therefore, during the ignition phase of the burning unit, the maximum allowed opening time of the gas valve without a flame being detected is limited to a short time period, which is sometimes also referred to as the ignition safety time. The ignition safety time is usually a fixed duration of time that is predetermined.
- In the remainder of this description, the term "gas" refers to any fuel in gaseous form that, when mixed with air, forms a combustible air-gas mixture. Examples for such a gas include hydrogen, propane, butane, methane, liquefied petroleum gas, etc. Moreover, the term "air" refers to any suitable oxidizer that may be mixed with a fuel gas to form a combustible air-gas mixture.
- The present invention relates to an air-gas mixture burning appliance, comprising a burning unit for burning a combustible air-gas mixture, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit, and a controller that is adapted for determining a variable ignition safety time for an ignition phase of the burning unit by selecting from at least two different durations of time, wherein the controller determines the variable ignition safety time as an anticipated maximum duration of time that elapses between an opening of the gas valve and a closing of the gas valve for avoiding a hazardous accumulation of the combustible air-gas mixture in the burning unit.
- Accordingly, the inventive air-gas mixture burning appliance may be able to adjust the ignition safety time and adapt to different modes of operation.
- Optionally, the air-gas mixture burning appliance further comprises a secured gas pathway that is arranged between the gas valve and the air-gas mixing unit and is adapted for providing the gas from the gas valve to the air-gas mixing unit, and wherein the controller determines the variable ignition safety time based on an inferred concentration of the gas in the secured gas pathway.
- Thus, the controller can select the variable ignition safety time based on whether the secured gas pathway is already filled with a gas or whether the secured gas pathway is filled with air at the beginning of the ignition phase.
- Preferably, the controller determines the variable ignition safety time based at least on the type of the gas.
- Accordingly, the inventive air-gas mixture burning appliance may be operated with different gas types.
- Optionally, the controller determines the variable ignition safety time by selecting from a predetermined number of at least three different discrete durations of time, wherein all values of the at least three different discrete durations of time are smaller than or equal to a predetermined maximum ignition safety time.
- Thus, the controller may have a simple design and be low cost.
- According to one aspect, the controller determines the variable ignition safety time by selecting from a continuous range of values, wherein all values in the continuous range of values are smaller than or equal to a predetermined maximum ignition safety time.
- Accordingly, the controller may fine-tune the ignition safety time and react to the combination of multiple parameters that may have an influence on the ignition safety time.
- Preferably, the air-gas mixture burning appliance further comprises a flame detector for sensing a presence of a flame in the burning unit, wherein the controller determines the variable ignition safety time based at least on an elapsed time since the flame detector previously sensed a flame in the burning unit.
- Thus, the inventive air-gas mixture burning appliance may reliably predict the concentration of the gas in the secured gas pathway at the beginning of the ignition phase.
- Optionally, the controller directs the gas valve to shut off if, during the ignition phase of the burning unit, the gas valve is open and the flame detector fails to sense a flame in the burning unit during the variable ignition safety time.
- Accordingly, the controller ensures the prevention of a dangerous build-up of the combustible air-gas mixture after the burning unit and a related delayed ignition.
- Preferably, the controller triggers a warning and/or puts the air-gas mixture burning appliance into one or more of a safe state, a restricted state, or a non-operational state, if during a predetermined number of consecutive ignition phases of the burning unit, the gas valve is open and the flame detector fails to sense a flame in the burning unit during the variable ignition safety time.
- Accordingly, an operator may be alerted and/or the risks associated with a malfunction of the air-gas mixture burning appliance may be reduced.
- Furthermore, a method of operating an air-gas mixture burning appliance that comprises a controller, a burning unit for burning a combustible air-gas mixture, a flame detector for sensing a presence of a flame in the burning unit, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, and a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit, comprises determining with the controller, a variable ignition safety time for an ignition phase of the burning unit by determining an anticipated maximum duration of time that can safely elapse between an opening of the gas valve and a closing of the gas valve for avoiding a hazardous accumulation of the combustible air-gas mixture in the burning unit.
- Accordingly, the inventive method may operate an air-gas mixture burning appliance by adjusting the ignition safety time and adapt to different modes of operation.
- Optionally, the method further comprises directing with the controller, the gas valve to shut off if, during the ignition phase of the burning unit, the gas valve is open and no flame is detected in the burning unit during the variable ignition safety time.
- Thus, the inventive method may prevent a hazardous build-up of the combustible air-gas mixture in the burning unit of the air-gas mixture burning appliance.
- Preferably, the air-gas mixture burning appliance further comprises a secured gas pathway that is arranged between the gas valve and the air-gas mixing unit and is adapted for providing the gas from the gas valve to the air-gas mixing unit, and determining the variable ignition safety time further comprises determining the variable ignition safety time based at least on the type of the gas, and/or on an inferred concentration of the gas in the secured gas pathway, and/or on an elapsed time since a flame detector previously sensed a flame in the burning unit.
- Thus, the inventive method may consider different parameters when determining the ignition safety time.
- Optionally, the method further comprises triggering with the controller, a warning and/or putting, with the controller, the air-gas mixture burning appliance into one or more of a safe state, a restricted state or a non-operational state, if, during a pre-determined number of consecutive ignition phases of the burning unit, the gas valve is open and no flame is detected in the burning unit during the variable ignition safety time.
- Accordingly, an operator may be alerted and/or the risks associated with a malfunction of the air-gas mixture burning appliance may be reduced.
- Exemplary embodiments of the present invention are described in detail hereinafter with reference to the attached drawings. In these attached drawings, identical or identically functioning components and elements are labelled with identical reference signs and they are generally only described once in the following description.
- Fig. 1
- shows a schematic view of an air-gas mixture burning appliance according to the present invention, during the ignition phase,
- Fig. 2
- shows a schematic view of an air-gas mixture burning appliance having a fan downstream of an air-gas mixer and an air flow channel to a reference pressure port of a gas valve, and
- Fig. 3
- shows a flowchart illustrating a method of operating an air-gas mixture burning appliance.
-
Fig. 1 shows an exemplary air-gasmixture burning appliance 100 with a burningunit 120 for burning a combustible air-gas mixture 130, an air-gas mixing unit 110, agas valve 194, aflame detector 150, and acontroller 140. By way of example, the air-gasmixture burning appliance 100 may be used in a boiler or, more generally, in a building heating system. - The air-
gas mixing unit 110 is arranged upstream of the burningunit 120 and is adapted for mixing ofair 111 andgas 119 to form the combustible air-gas mixture 130. Preferentially, the combustible air-gas mixture 130 is a homogenous mixture of theair 111 and thegas 119. - By way of example, the air-
gas mixing unit 110 includes an air supply unit and a gas supply unit. Illustratively, the air supply unit includes afan 114 that may be operated with an adaptable fan speed and/or within predetermined ranges of fan speeds. - As shown in
Fig. 1 , thefan 114 may pushair 111 into the air-gas mixing unit 110. If desired, and as shown inFig. 2 , thefan 114 may draw the combustible air-gas mixture 130 from the air-gas mixing unit 110. - The gas supply unit may include the
gas valve 194. Thegas valve 194 is arranged upstream of the air-gas mixing unit 110 and is adapted for regulating a flow of thegas 119 to the air-gas mixing unit 110. A securedgas pathway 116 is arranged between thegas valve 194 and the air-gas mixing unit 110 and is adapted for providing thegas 119 from thegas valve 194 to the air-gas mixing unit 110. - The air supply unit and the gas supply unit may be interconnected via a
mixer 118 which forms a corresponding discrete point of mixing. Preferably, the combustible air-gas mixture 130 is formed at the discrete point of mixing and guided via themixer 118 and the combustible air-gas pathway 132 to theburning unit 120. - Illustratively, the
burning unit 120 is provided with aburner surface 124 that is arranged downstream of the air-gas mixing unit 110 such that the combustible air-gas mixture 130 flows towards theburner surface 124. The combustible air-gas mixture 130 is burned by theburning unit 120 and, more specifically, at theburner surface 124. - By way of example, during an ignition phase of the air-gas
mixture burning appliance 100, the combustible air-gas mixture 130 from the air-gas mixing unit 110 may be ignited in theburning unit 120 at theburner surface 124. The resultingflame 122 is illustratively stabilised against theburner surface 124. - According to one aspect, the
flame detector 150 is provided for sensing presence of aflame 122 in theburning unit 120. Thus, theflame detector 150 is suitable for determining whether aflame 122 is present at theburner surface 124 in theburning unit 120. However, it should be noted that suitable flame detection techniques that may be used with theflame detector 150 are well-known to the person skilled in the art and are, therefore, not described in more detail, for brevity and conciseness. For instance, theflame detector 150 may use any suitable sensing element for sensing presence of theflame 122 in theburning unit 120. - Illustratively, the
flame detector 150 may be connected to thecontroller 140. If desired, theflame detector 150 may generate and/or provide aflame detection signal 162 to thecontroller 140 based on whether theflame detector 150 senses the presence of aflame 122 in theburning unit 120 or fails to sense the presence of aflame 122 in theburning unit 120. - Alternatively, the
controller 140 may determine whether aflame 122 is present in theburning unit 120 by comparing the detectedflame signal 160 with a predetermined flame detection threshold. - As shown in
Fig. 1 , thecontroller 140 may be connected to thegas valve 194. Illustratively, thecontroller 140 may receive acontrol signal 182 from thegas valve 194. By way of example, thecontrol signal 182 may be indicative of the status of thegas valve 194. For example, thecontroller signal 182 may indicate whether thegas valve 194 is open or closed. - Illustratively, the
controller 140 may send anactuator signal 183 to thegas valve 194. If desired, theactuator signal 183 may direct thegas valve 194 to open and/or to close. For example, at the beginning of an ignition phase, thecontroller 140 may direct thegas valve 194 to open. - During the ignition phase, the
controller 140 tracks the duration of time between the opening of thegas valve 194 and the detection of aflame signal 160 at theburning unit 120. To avoid a delayed ignition, which refers to igniting a hazardous accumulation of the combustible air-gas mixture 130 and which usually leads to an explosion that may damage internal components of the air-gasmixture burning appliance 100 and endanger the surrounding environment, the maximum allowed opening time of thegas valve 194 without aflame 122 being detected is limited to a short period of time, which is sometimes also referred to as the ignition safety time. - In contrast thereto, the
gas valve 194 needs to be open for a minimum opening time. The minimum opening time is defined as the time that is required for thegas 119 to flow from thegas valve 194 through the securedgas pathway 116 to the air-gas mixing unit 110 and from there, as a combustible air-gas mixture 130 to theburner surface 124, where a sufficient quantity of the combustible air-gas mixture 130 is required to accumulate such that a reliable ignition of theflame 122 is ensured. - However, the time between the opening of the
gas valve 194 and the accumulation of a quantity of the combustible air-gas mixture 130 in theburning unit 120 that is sufficient for a sustained ignition may depend on the concentration of thegas 119 in the securedgas pathway 116 at the opening of thegas valve 194. - As an example, If the air-gas
mixture burning appliance 100 were to stop burninggas 119, but after a short period of time be re-lit, then thesecured gas pathway 116 would still be filled withgas 119, and the combustible air-gas pathway 132 would still be filled with the combustible air-gas mixture 130, and, as a result, aflame 122 could be established comparatively quickly at theburner surface 124. - As another example, in between periods of operation, the concentration of the
gas 119 in the securedgas pathway 116 and in the combustible air-gas pathway 132 decays overtime. Thus, if the air-gasmixture burning appliance 100 is re-lit after a sufficient period of time, the securedgas pathway 116 and the combustible air-gas pathway 132 is nominally filled with air and contains a negligible concentration of thegas 119 at the start of the ignition sequence. In this case, the nominally air that is present in the securedgas pathway 116 and in the combustible air-gas pathway 132 must be displaced bygas 119 that is streaming through the openedgas valve 194. - This process of re-priming the secured
gas pathway 116 and the combustible air-gas pathway 132 takes some time, which may depend, for example, on the flow rate of nominally air and the volume of theconsecutive pathways - Consequently, a
flame 122 appears at theburner surface 124 only after this priming process has sufficiently progressed, and takes more time in comparison to the ignition attempt made shortly after an end of a previous burn that was described in the previous example. - Thus, the
controller 140 is adapted for determining a variable ignition safety time for an ignition phase of theburning unit 120 by selecting from at least two different durations of time. Thereby, thecontroller 140 determines the variable ignition safety time as an anticipated maximum duration of time that elapses between an opening of thegas valve 194 and a closing of thegas valve 194 for avoiding a hazardous accumulation of the combustible air-gas mixture 130 in theburning unit 120. - Since the decay of the concentration of the
gas 119 in the securedgas pathway 116 over time is driven by a diffusion process that is relatively repeatable and predictable, thecontroller 140 may determine the variable ignition safety time based on an inferred concentration of thegas 119 in the securedgas pathway 116. - Moreover, the decay of the concentration of the
gas 119 and/or the time to reprime the securedgas pathway 116 and the combustible air-gas pathway 132 may depend on the type ofgas 119. For example, the difference in density of hydrogen or any other fuel gas that is less dense than air may result in an exacerbated delay in the appearance of aflame 122 at theburner surface 124. Therefore, thecontroller 140 may determine the variable ignition safety time based at least on the type of thegas 119. - Illustratively, the
controller 140 may determine the variable ignition safety time based at least on an elapsed time since theflame detector 150 previously sensed aflame 122 in theburning unit 120. - By way of example, the
controller 140 may determine the longest duration of time after the opening of thegas valve 194 that it is safe to wait for aflame 122 to appear in theburning unit 120 before thegas valve 194 must be closed to prevent an excessive accumulation of the combustible air-gas mixture 130 in theburning unit 120. This longest duration of time is sometimes also referred to as a predetermined maximum ignition safety time. - Illustratively, the
controller 140 may determine the variable ignition safety time by selecting from a predetermined number of at least three different discrete durations of time wherein all values of the at least three different discrete durations of time are smaller than or equal to a predetermined maximum ignition safety time. - If desired, the
controller 140 may determine the variable ignition safety time by selecting from a continuous range of values, wherein all values in the continuous range of values are smaller than or equal to a predetermined maximum ignition safety time. - Illustratively, the
controller 140 may direct thegas valve 194 to shut off if, during the ignition phase of theburning unit 120, thegas valve 194 is open and theflame detector 150 fails to sense aflame 122 in theburning unit 120 during the variable ignition safety time. For example, thecontroller 140 may direct thegas valve 194 to close usingactuator signal 183. - By way of example, the
controller 140 may trigger a warning, if during a predetermined number of consecutive ignition phases of theburning unit 120, thegas valve 194 is open and theflame detector 150 fails to sense aflame 122 in theburning unit 120 during the variable ignition safety time. - The warning may be any signal that alerts an operator about the malfunction of the air-gas
mixture burning appliance 100. For example, the warning may be a visual signal (e.g., a flashing display, a color coded display, a message, etc.), an audio signal (e.g., a warning message, a beeping signal, etc.), a tactile signal (e.g., a vibration), or any combination thereof. - Illustratively, the
controller 140 may put the air-gasmixture burning appliance 100 into one or more of a safe state, a restricted state, or a non-operational state, if during a predetermined number of consecutive ignition phases of theburning unit 120, thegas valve 194 is open and theflame detector 150 fails to sense aflame 122 in theburning unit 120 during the variable ignition safety time. - If desired, the
controller 140 may trigger a warning and put the air-gasmixture burning appliance 100 into one or more of a safe state, a restricted state, or a non-operational state, if during a predetermined number of consecutive ignition phases of theburning unit 120, thegas valve 194 is open and theflame detector 150 fails to sense aflame 122 in theburning unit 120 during the variable ignition safety time. -
Fig. 2 shows a schematic view of an air-gasmixture burning appliance 100 having afan 114 downstream of an air-gas mixer 118 and anair flow channel 250 to areference pressure port 242 of agas valve 194. As shown inFig. 2 , the air-gasmixture burning appliance 100 may include an air inlet for providingair 111, agas inlet 117 for providinggas 119, and aflue outlet 155 for the evacuation ofexhaust gas 152. Illustratively, the air-gasmixture burning appliance 100 may further include an air-gas mixing unit 110, aburning unit 120, and aheat exchanger 170. - The air-
gas mixing unit 110 is preferably adapted for mixing ofair 111 andgas 119 to form a combustible air-gas mixture 130. Preferentially, the combustible air-gas mixture 130 is a homogenous mixture of theair 111 and thegas 119. - Illustratively, the
burning unit 120 is provided with aburner surface 124 that is arranged downstream of the air-gas mixing unit 110 such that the combustible air-gas mixture 130 flows towards theburner surface 124. If desired, thefan 114 may drive the combustible air-gas mixture 130 through the combustible air-gas pathway 132 towards theburner surface 124. - The combustible air-
gas mixture 130 is burned by theburning unit 120 and, more specifically, at theburner surface 124. Theheat exchanger 170 may transfer the heat that is generated at theburner surface 124 to another medium. For example, theheat exchanger 170 may transfer the heat that is generated at theburner surface 124 to water in a water circuit. Theflue outlet 155 may evacuate theexhaust gas 152 from the air-gasmixture burning appliance 100. - The
gas valve 194 may include areference pressure port 242. Preferably, theair flow channel 250 is adapted for providing the flow of theair 111 to thereference pressure port 242, and thegas valve 194 is adapted for regulating the flow of thegas 119 based on the pressure of the flow of theair 111 at thereference pressure port 242. - The
controller 140 is adapted for determining a variable ignition safety time for an ignition phase of theburning unit 120 by selecting from at least two different durations of time. Thereby, thecontroller 140 determines the variable ignition safety time as an anticipated maximum duration of time that elapses between an opening of thegas valve 194 and a closing of thegas valve 194 for avoiding a hazardous accumulation of the combustible air-gas mixture 130 in theburning unit 120. - Illustratively, the
controller 140 may send anactuator signal 183 to thegas valve 194. If desired, theactuator signal 183 may direct thegas valve 194 to open and/or to close. For example, at the beginning of an ignition phase, thecontroller 140 may direct thegas valve 194 to open. - By way of example, the
controller 140 may direct thegas valve 194 to shut off if, during the ignition phase of theburning unit 120, thegas valve 194 is open and theflame detector 150 fails to sense aflame 122 in theburning unit 120 during the variable ignition safety time. For example, thecontroller 140 may direct thegas valve 194 to close usingactuator signal 183. - Thus,
actuator signal 183 may override thereference pressure port 242 of thegas valve 194. -
Fig. 3 shows a flowchart illustrating amethod 300 of operating an air-gas mixture burning appliance. The air-gas mixture burning appliance comprises a burning unit for burning a combustible air-gas mixture, a flame detector for sensing a presence of a flame in the burning unit, an air-gas mixing unit that is arranged upstream of the burning unit and is adapted for mixing of air and gas to form the combustible air-gas mixture, and a gas valve that is arranged upstream of the air-gas mixing unit and is adapted for regulating a flow of the gas to the air-gas mixing unit. - For example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 comprises aburning unit 120 for burning a combustible air-gas mixture 130, aflame detector 150 for sensing a presence of aflame 122 in theburning unit 120, an air-gas mixing unit 110 that is arranged upstream of theburning unit 120 and is adapted for mixing ofair 111 andgas 119 to form the combustible air-gas mixture 130, and agas valve 194 that is arranged upstream of the air-gas mixing unit 110 and is adapted for regulating a flow of thegas 119 to the air-gas mixing unit 110. - During
operation 310, the air-gas mixture burning appliance determines, with a controller, a variable ignition safety time for an ignition phase of the burning unit by determining an anticipated maximum duration of time that can safely elapse between an opening of the gas valve and a closing of the gas valve for avoiding a hazardous accumulation of the combustible air-gas mixture in the burning unit. - For example, air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may usecontroller 140 to determine a variable ignition safety time for an ignition phase of theburning unit 120 by determining an anticipated maximum duration of time that can safely elapse between an opening of thegas valve 194 and a closing of thegas valve 194 for avoiding a hazardous accumulation of the combustible air-gas mixture 130 in theburning unit 120. - During
operation 320, the air-gas mixture burning appliance directs, with the controller, the gas valve to shut off if, during the ignition phase of the burning unit, the gas valve is open and no flame is detected in the burning unit during the variable ignition safety time. - For example, air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may usecontroller 140 to direct thegas valve 194 to shut off if, during the ignition phase of theburning unit 120, thegas valve 194 is open and noflame 122 is detected in theburning unit 120 during the variable ignition safety time. - If desired, the air-gas mixture burning appliance may further comprise a secured gas pathway that is arranged between the gas valve and the air-gas mixing unit and is adapted for providing the gas from the gas valve to the air-gas mixing unit.
- For example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may comprise a securedgas pathway 116 that is arranged between thegas valve 194 and the air-gas mixing unit 110 and is adapted for providing thegas 119 from thegas valve 194 to the air-gas mixing unit 110. - In such an air-gas mixture burning appliance, the operation of determining 310 the variable ignition safety time may further comprise the operation of determining the variable ignition safety time based at least on the type of the gas, and/or on an inferred concentration of the gas in the secured gas pathway, and/or on an elapsed time since a flame detector previously sensed a flame in the burning unit.
- As an example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may determine the variable ignition safety time based at least on the type of thegas 119. - As another example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may determine the variable ignition safety time based at least on an inferred concentration of thegas 119 in the securedgas pathway 116. - As yet another example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may determine the variable ignition safety time based at least on an elapsed time since aflame detector 150 previously sensed aflame 122 in theburning unit 120. - As yet another example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may determine the variable ignition safety time based at least on the type of thegas 119, and an inferred concentration of thegas 119 in the securedgas pathway 116. - As yet another example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may determine the variable ignition safety time based at least on the type of thegas 119 and an elapsed time since aflame detector 150 previously sensed aflame 122 in theburning unit 120. - As yet another example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may determine the variable ignition safety time based at least on an inferred concentration of thegas 119 in the securedgas pathway 116, and an elapsed time since aflame detector 150 previously sensed aflame 122 in theburning unit 120. - As yet another example, the air-gas
mixture burning appliance 100 ofFig. 1 orFig. 2 may determine the variable ignition safety time based at least on the type of thegas 119, and on an inferred concentration of thegas 119 in the securedgas pathway 116, and on an elapsed time since aflame detector 150 previously sensed aflame 122 in theburning unit 120. - Illustratively, the controller of the air-gas mixture burning appliance may further trigger a warning and/or put the air-gas mixture burning appliance into one or more of a safe state, a restricted state or a non-operational state, if, during a predetermined number of consecutive ignition phases of the burning unit, the gas valve is open and no flame is detected in the burning unit during the variable ignition safety time.
- As an example, the
controller 140 of the air-gasmixture burning appliance 100 ofFig. 1 orFig. 2 may trigger a warning, if, during a predetermined number of consecutive ignition phases of theburning unit 120, thegas valve 194 is open and noflame 122 is detected in theburning unit 120 during the variable ignition safety time. - As another example, the
controller 140 of the air-gasmixture burning appliance 100 ofFig. 1 orFig. 2 may put, the air-gasmixture burning appliance 100 into one or more of a safe state, a restricted state or a non-operational state, if, during a predetermined number of consecutive ignition phases of theburning unit 120, thegas valve 194 is open and noflame 122 is detected in theburning unit 120 during the variable ignition safety time. - As yet another example, the
controller 140 of the air-gasmixture burning appliance 100 ofFig. 1 orFig. 2 may trigger a warning and put, the air-gasmixture burning appliance 100 into one or more of a safe state, a restricted state or a non-operational state, if, during a predetermined number of consecutive ignition phases of theburning unit 120, thegas valve 194 is open and noflame 122 is detected in theburning unit 120 during the variable ignition safety time.
Claims (12)
- An air-gas mixture burning appliance (100), comprising:a burning unit (120) for burning a combustible air-gas mixture (130);an air-gas mixing unit (110) that is arranged upstream of the burning unit (120) and is adapted for mixing of air (111) and gas (119) to form the combustible air-gas mixture (130);a gas valve (194) that is arranged upstream of the air-gas mixing unit (110) and is adapted for regulating a flow of the gas (119) to the air-gas mixing unit (110); anda controller (140) that is adapted for determining a variable ignition safety time for an ignition phase of the burning unit (120) by selecting from at least two different durations of time, wherein the controller (140) determines the variable ignition safety time as an anticipated maximum duration of time that elapses between an opening of the gas valve (194) and a closing of the gas valve (194) for avoiding a hazardous accumulation of the combustible air-gas mixture (130) in the burning unit (120).
- The air-gas mixture burning appliance of claim 1, further comprising:
a secured gas pathway (116) that is arranged between the gas valve (194) and the air-gas mixing unit (110) and is adapted for providing the gas (119) from the gas valve (194) to the air-gas mixing unit (110), and wherein the controller (140) determines the variable ignition safety time based on an inferred concentration of the gas (119) in the secured gas pathway (116). - The air-gas mixture burning appliance of any one of the preceding claims, wherein the controller (140) determines the variable ignition safety time based at least on the type of the gas (119).
- The air-gas mixture burning appliance of any one of the preceding claims, wherein the controller (140) determines the variable ignition safety time by selecting from a predetermined number of at least three different discrete durations of time, wherein all values of the at least three different discrete durations of time are smaller than or equal to a predetermined maximum ignition safety time.
- The air-gas mixture burning appliance of any one of claims 1 to 3, wherein the controller (140) determines the variable ignition safety time by selecting from a continuous range of values, wherein all values in the continuous range of values are smaller than or equal to a predetermined maximum ignition safety time.
- The air-gas mixture burning appliance of any one of the preceding claims, further comprising:
a flame detector (150) for sensing a presence of a flame (122) in the burning unit (120), wherein the controller (140) determines the variable ignition safety time based at least on an elapsed time since the flame detector (150) previously sensed a flame (122) in the burning unit (120). - The air-gas mixture burning appliance of claim 6, wherein the controller (140) directs the gas valve (194) to shut off if, during the ignition phase of the burning unit (120), the gas valve (194) is open and the flame detector (150) fails to sense a flame (122) in the burning unit (120) during the variable ignition safety time.
- The air-gas mixture burning appliance of claim 6 or 7, wherein the controller (140) triggers a warning and/or puts the air-gas mixture burning appliance (100) into one or more of a safe state, a restricted state, or a non-operational state, if during a predetermined number of consecutive ignition phases of the burning unit (120), the gas valve (194) is open and the flame detector (150) fails to sense a flame (122) in the burning unit (120) during the variable ignition safety time.
- A method (300) of operating an air-gas mixture burning appliance (100) that comprises a controller (140), a burning unit (120) for burning a combustible air-gas mixture (130), a flame detector (150) for sensing a presence of a flame (122) in the burning unit (120), an air-gas mixing unit (110) that is arranged upstream of the burning unit (120) and is adapted for mixing of air (111) and gas (119) to form the combustible air-gas mixture (130), and a gas valve (194) that is arranged upstream of the air-gas mixing unit (110) and is adapted for regulating a flow of the gas (119) to the air-gas mixing unit (110), the method comprising:
determining (310) with the controller (140), a variable ignition safety time for an ignition phase of the burning unit (120) by determining an anticipated maximum duration of time that can safely elapse between an opening of the gas valve (194) and a closing of the gas valve (194) for avoiding a hazardous accumulation of the combustible air-gas mixture (130) in the burning unit (120). - The method of claim 9, further comprising:
directing (320) with the controller (140), the gas valve (194) to shut off, if, during the ignition phase of the burning unit (120), the gas valve (194) is open and no flame (122) is detected in the burning unit (120) during the variable ignition safety time. - The method of any one of claims 9 or 10, wherein the air-gas mixture burning appliance (100) further comprises a secured gas pathway (116) that is arranged between the gas valve (194) and the air-gas mixing unit (110) and is adapted for providing the gas (119) from the gas valve (194) to the air-gas mixing unit (110), and wherein determining (310) the variable ignition safety time further comprises:
determining the variable ignition safety time based at least on the type of the gas (119), and/or on an inferred concentration of the gas (119) in the secured gas pathway (116), and/or on an elapsed time since a flame detector (150) previously sensed a flame (122) in the burning unit (120). - The method of any one of claims 10 or 11, further comprising:
triggering with the controller (140), a warning and/or putting, with the controller (140), the air-gas mixture burning appliance (100) into one or more of a safe state, a restricted state or a non-operational state, if, during a pre-determined number of consecutive ignition phases of the burning unit (120), the gas valve (194) is open and no flame (122) is detected in the burning unit (120) during the variable ignition safety time.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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GB2116392.8A GB2612830A (en) | 2021-11-12 | 2021-11-12 | An air-gas mixture burning appliance with a variable ignition safety time |
Publications (1)
Publication Number | Publication Date |
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EP4180719A1 true EP4180719A1 (en) | 2023-05-17 |
Family
ID=79163561
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Application Number | Title | Priority Date | Filing Date |
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EP22202347.5A Pending EP4180719A1 (en) | 2021-11-12 | 2022-10-19 | An air-gas mixture burning appliance with a variable ignition safety time |
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EP (1) | EP4180719A1 (en) |
GB (1) | GB2612830A (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3836868A1 (en) * | 1987-11-06 | 1989-06-15 | Vaillant Joh Gmbh & Co | Automatic firing system |
DE19941978A1 (en) * | 1999-09-03 | 2001-03-15 | Stiebel Eltron Gmbh & Co Kg | Production of synthesis gas for operating fuel cell from fuel involves regulation to ensure over-stoichiometric air supply for start-up, then incomplete combustion after start-up |
US20140199640A1 (en) * | 2013-01-11 | 2014-07-17 | Honeywell International Inc. | Method and system for controlling an ignition sequence for an intermittent flame-powered pilot combustion system |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58221317A (en) * | 1982-06-16 | 1983-12-23 | Tokyo Gas Co Ltd | Gas supply system |
JPH0779842B2 (en) * | 1988-03-28 | 1995-08-30 | 富士電機株式会社 | Gas accident prevention device |
GB0116228D0 (en) * | 2001-07-03 | 2001-08-29 | Lerwick Engineering & Fabricat | Apparatus and method |
GB2598970A (en) * | 2020-09-22 | 2022-03-23 | Bosch Thermotechnology Ltd Uk | An air-gas mixture burning appliance with a variable equivalence ratio ignition sequence |
-
2021
- 2021-11-12 GB GB2116392.8A patent/GB2612830A/en active Pending
-
2022
- 2022-10-19 EP EP22202347.5A patent/EP4180719A1/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3836868A1 (en) * | 1987-11-06 | 1989-06-15 | Vaillant Joh Gmbh & Co | Automatic firing system |
DE19941978A1 (en) * | 1999-09-03 | 2001-03-15 | Stiebel Eltron Gmbh & Co Kg | Production of synthesis gas for operating fuel cell from fuel involves regulation to ensure over-stoichiometric air supply for start-up, then incomplete combustion after start-up |
US20140199640A1 (en) * | 2013-01-11 | 2014-07-17 | Honeywell International Inc. | Method and system for controlling an ignition sequence for an intermittent flame-powered pilot combustion system |
Also Published As
Publication number | Publication date |
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GB202116392D0 (en) | 2021-12-29 |
GB2612830A (en) | 2023-05-17 |
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