Burner Control System of or for a Heating System and Method for Controlling a Burner Control System

Abstract

The present disclosure relates to a burner control system, comprising a controller, a burner connectable to a combustible gas supply and comprising a controllable valve coupled to the controller, an optical sensor arranged at the burner and coupled to the controller, wherein the controller is configured to determine a use state of the burner, from a group of use states comprising at least an ignition state, based on a measurement signal of the optical sensor that is indicative for a light level corresponding to said use state, and to selectively control the controllable valve in dependency of said use state of the burner.

Claims

1. A burner control system, comprising: a controller; a burner connectable to a combustible gas supply and comprising a controllable valve coupled to the controller; and an optical sensor arranged at the burner and coupled to the controller, wherein the controller is configured to determine a use state of the burner, from a group of use states comprising at least an ignition state, based on a measurement signal of the optical sensor that is indicative for a light level corresponding to said use state, and to selectively control the controllable valve in dependency of said use state of the burner.

2. The burner control system according to claim 1, wherein the controller is configured to determine a load of the burner based on the measurement signal of the optical sensor and a known combustible gas-air ratio of the combustible gas emitted by the burner.

3. The burner control system according to claim 1, wherein the controller is configured to determine a load of the burner based on the measurement signal of the optical sensor and a known combustible gas-air ratio of the combustible gas emitted by the burner.

4. The burner control system according to claim 1, further comprising a UV sensor, and wherein the controller is configured to determine if the measurement signal indicative for the UV light level is above a pre-determined threshold indicative for a presence of a hydrogen flame.

5. The burner control system according to claim 4, wherein the controller is configured to perform a safety procedure if the measurement signal indicative for the UV light level is below the pre-determined threshold indicative for the presence of the hydrogen flame in the combustion state.

6. The burner control system according to claim 1, wherein the group of use states further comprises a combustion state, and the controller is configured to determine if the measurement signal indicative for the light level is above a pre-determined threshold indicative for a presence of a flame.

7. The burner control system according to claim 6, wherein the controller is configured to perform a safety procedure if the measurement signal indicative for a light level is below the pre-determined threshold indicative for the presence of a flame in the combustion state.

8. The burner control system according to claim 1, further comprising: a spark plug coupled to the controller and configured to selectively emit sparks to ignite combustible gas emitted by the burner; a spark detection sensor coupled to the controller; and wherein the group of use states further comprises a pre-ignition state, and the controller is configured to: control the spark plug to selectively emit sparks to thereby ignite combustible gas; receive a spark detection signal from the spark detection sensor indicative for the pre-ignition state; and control the controllable valve of the burner to emit combustible gas based on the spark detection signal.

9. The burner control system according to claim 8, wherein the spark detection signal indicative for the pre-ignition state comprises a fluctuating spark detection signal.

10. The burner control system according to claim 8, wherein: the spark detection sensor is the optical sensor; and the spark detection signal obtained through the spark detection sensor is indicative for light from sparks emitted by the spark plug.

11. The burner control system according to claim 8, wherein the controller is configured to determine if the spark detection signal indicative for the pre-ignition state is above a pre-determined threshold indicative for the pre-ignition state and below the pre-determined threshold indicative for the presence of the flame.

12. The burner control system according to claim 1, wherein the controller is configured to: perform a zero-level signal measurement indicative for a background level of light using the optical sensor when the burner is an inactive state; and determine the use state of the burner based on the zero-level signal.

13. The burner control system according to claim 7, wherein the controller is configured to perform the safety procedure based on the measurement signal of the optical sensor by performing one or more than one of: closing the controllable valve of the burner; stopping an operation of a fan comprised by the burner control system; and performing a safety shutdown of the burner control system.

14. The burner control system according to claim 4, wherein the optical sensor is the UV sensor.

15. A method for controlling a burner control system of or for a heating system, the method comprising: obtaining a measurement signal of an optical sensor that is indicative for a light level; determining a use state of a burner, from a group of use states comprising at least an ignition state, based on the obtained measurement signal corresponding to said use state, wherein the burner is connectable to a combustible gas supply and comprised by the burner control system; and selectively controlling a controllable valve of the burner control system in dependency of said use state of the burner.

16. The method according to claim 15, further comprising: controlling a spark plug of the burner control system to selectively emit sparks to thereby ignite combustible gas; receiving a spark detection signal from a spark detection sensor of the burner control system; controlling the controllable valve of the burner to emit combustible gas based on the spark detection signal; and determining if the spark detection signal indicative for the pre-ignition state is above a pre-determined threshold indicative for the ignition state and below the pre-determined threshold indicative for the combustion state.

17. The method according to claim 15, the method further comprising determining a load of the burner based on the measurement signal of a UV sensor and a known hydrogen gas-air ratio of the hydrogen gas emitted by the burner.

18. The method according to claim 15, wherein the controller is configured to determine a load of the burner based on the measurement signal of the optical sensor and a known combustible gas-air ratio of the combustible gas emitted by the burner.

19. The method according to claim 15, wherein the group of use states further comprises a combustion state, the method further comprising: determining if the measurement signal indicative for the light level is above a pre-determined threshold indicative for the presence of a flame in the combustion state.

20. The method according to claim 19, the method further comprising performing a safety procedure if the measurement signal indicative for the light level is below a pre-determined threshold indicative for the presence of a flame.

21. The method according to claim 15, wherein method further comprising: performing a zero-level signal indicative for a background level of light using the optical sensor; and determining the use state of the burner based moreover on the zero-level signal.

22. The method according to claim 15, wherein performing the safety procedure comprises one or more of: closing the controllable valve of the burner; stopping an operation of a fan comprised by the burner control system; and performing a safety shutdown of the burner control system.

Description

[0042] The burner control system according to the present invention and methods for operating this system will be elucidated here below with reference to the drawing, in which:

[0043] FIG. 1 depicts a schematic representation of a burner control system according to the present invention; and

[0044] FIG. 2 illustrates a graph explaining the operation of the burner control system of FIG. 1 during various stages of operation of the burner control system.

[0045] Referring now to FIG. 1, a schematic representation of at least part of a burner control system 100 is depicted. The burner control system 100 comprises at least a controller 105, a burner 110 and an optical sensor 120.

[0046] In accordance with preferred embodiments of the burner control system 100 according to the present invention, the optical sensor 120 is an ultraviolet (UV) sensor 120 configured to detect light having a wavelength within the UV part of the electromagnetic spectrum. Here below, the burner control system 100 according to the present invention is elucidated with reference to this UV sensor 120. However, it should be understood that, in particular for embodiments in which the burner control system 100 is fueled by a non-hydrogen combustible gas, the UV sensor 120 can be replaced by an optical sensor 120 configured to detect visible and/or infrared light.

[0047] The burner 110 is connected to a combustible gas supply 112 by means of a controllable valve 114 that in turn is connected to the controller 105.

[0048] The combustible gas supply 112 may contain any suitable type of combustible gas, including hydrogen gas various forms of natural gas. Moreover, the combustible gas may be either a gas tank or a gas distribution network of a known type. In the following parts of the present disclosure, it is assumed that the gas supply 112 is hydrogen gas supply 112. Nevertheless, it is emphasised here that the present disclosure is not limited thereto and that, generally, other types of combustible gas may likewise be utilised.

[0049] The UV sensor 120 is connected to the controller 105 and arranged at the burner 110, so that UV light 116 stemming from a hydrogen flame 111 emitted by the burner 110 is sensed by the UV sensor 120. The resultant measurement signal of the UV sensor 120 is fed to the controller 105 so that the controller 105 may open or close the controllable valve 114 based on this received measurement signal. The burner 110 is thus configured to selectively emit combustible gas under the control of the controller 105. When this emitted hydrogen gas is ignited, there is a hydrogen flame 111 emitting primarily UV light 116.

[0050] An amplifier 122 and filter 124 may be provided downstream of the UV sensor 120 to, respectively, amplify and filter the signal from the UV sensor 120 before it is fed to the controller 105. Moreover, a comparator 130 is provided to compare the measurement signal of the UV sensor 120 to any one of several different reference or threshold values that will be elucidated further below. While the amplifier 122, the filter 124 and the comparator 130 are depicted as components distinct from the controller 105, they may in practice be comprised by the controller 105.

[0051] The burner control system 100 further preferably comprises a spark plug 140 for igniting hydrogen gas and optionally a spark detection sensor 121 configured to detect sparks emitted by the spark plug 140. As can be discerned from FIG. 1, both the spark plug 140 and the spark detection sensor 121 are coupled to the controller 105. Primarily the sparks can be detected by sensor 120, making an additional sensor redundant. An additional sensor may be applicable if, for example, the sensitivity and/or measurement range of one sensor is not sufficient for measuring both the sparks and the UV-signal of the full load (or modulation) range of the system.

[0052] FIG. 2 shows an exemplary graph of the measurement signal from the UV sensor 120 as a function of time during different subsequent use states of the burner control system 100. Within the context of the present disclosure, the term use state refers to any one of various operative states of the burner control system 100 and its components, in particular with respect to an opened or closed state of the controllable valve 114 whether or not the spark plug 140 is controlled to emit sparks. The graph of FIG. 2 depicts an exemplary sequence of five of such use states during respective consecutive time periods T.sub.1, T.sub.2, T.sub.3, T.sub.4 and T.sub.5. These use states are, respectively, an inactive state, a pre-ignition state, an ignition state, a combustion state (in which an output power of the burner control system 100 may be adjusted or the burner control system 100 may be shutdown).

[0053] In FIG. 2, the use state corresponding to time period T.sub.1 is referred to as an inactive state of the burner control system 100. In this inactive state the controllable valve 114 is closed with no hydrogen gas being emitted by the burner 110 and no sparks are emitted by the spark plug 140. The burner control system 100 may be in the inactive state of time period T.sub.1 when the heating system with which the burner control system 100 is connected does not require a supply of heat.

[0054] Certain components such as the UV sensor 120 and the controller 105 may nevertheless still be activated in this inactive state of the burner control system 100, thereby allowing the UV sensor 120 to obtain a UV measurement signal and communicate this UV measurement signal to the controller 105. In the inactive state, the UV sensor 120 may sense only very little or no UV light because of the absence of the hydrogen flame 111, which is represented by the signal of the UV sensor 120 being low in the graph of FIG. 2.

[0055] The time period T.sub.2 corresponds to pre-ignition state of the burner control system 100. In this pre-ignition state, the controllable valve 114 remains closed while the spark plug 140 emits sparks under the control of the controller 105. These emitted sparks may be detected by means of the spark detection sensor 121 or, more preferably, by the UV sensor 120. In FIG. 2, it is assumed that these emitted sparks are detected by the UV sensor 120, which is represented by the signal of the UV sensor 120 being elevated.

[0056] The UV sensor 120 may be configured to detect individual sparks emitted by the spark plug 140. For example, the UV sensor 120 may have a sufficiently high sampling rate to detect individual sparks. Sparks may be represented by various characteristics of the signal of the UV sensor 120, for example by a maximum value of individual peaks or an average of spark signal values.

[0057] In certain embodiments of the of the burner control system 100, the spark plug 140 may moreover be utilised to detect a malfunctioning the optical or UV sensor 120. In these embodiments, when the spark plug 140 emits sparks having adequately predefined characteristics (e.g. spark frequency or spark light intensity), the signal of the UV sensor 120 may be compared to a predefined value corresponding to a signal of the UV sensor 120 when there is no malfunction. A malfunction of the UV sensor 120 may then be determined based on a discrepancy between the signal of the UV sensor 120 and the predefined value output by the UV sensor in case if no malfunctioning of the UV sensor 120. Progressive errors or degradation of the UV sensor 120which may manifest in a drift of the signal of the UV sensor 120, may thus be detected over time. The burner control system 100 may respond to such an error or degradation of the UV sensor 120 by entering into a safety procedure as described here above and below, which may include the burner control system 100 entering into a safe or locked state.

[0058] In further embodiments, sparks emitted by the spark plug 140 may even be utilised to calibrate the UV sensor 120, provided that a type of spark plug 140 is used with which the emitted sparks can be controlled to a sufficient degree for this purpose. In certain embodiments of the of the burner control system 100, the controller 105 may be configured to compare the spark detection signal indicative for the pre-ignition state with a pre-determined threshold indicative for the pre-ignition state. This threshold may be lower than the pre-determined threshold indicative for the presence of the hydrogen flame 111 at the initial ignition. However, the present disclosure is not limited thereto. At least in embodiments wherein the burner control system 100 is configured to allow for modulation of the output power, a signal of the UV sensor 120 corresponding to a lowest output power (at which the flame 111 is smallest) may be higher than a signal of the UV sensor 120 detection of the sparks as described here above. Therefore, the pre-determined threshold for the presence of the flame may alternatively be selected to comprise a corresponding lower value.

[0059] Upon successful detection of the sparks during the time period T.sub.2 corresponding to the pre-ignition state by either the UV sensor 120 or the spark detection sensor 121, the controller 105 opens the controllable valve 114 to thereby cause the burner 110 to emit hydrogen gas. During the time period T.sub.3 that corresponds to an ignition state, emitted hydrogen gas is brought to ignition by sparks emitted by the spark plug 140. Upon successful ignition, UV light emitted by the sparks and the resultant hydrogen flame 111 is detected by the UV sensor 120, which is represented in FIG. 2 by the further elevated value of the UV sensor 120 during time period T.sub.3. Upon successful detection of the hydrogen flame 111 by means of the UV sensor 120, the controller 105 may control the spark plug 140 to stop emitting sparks. While not explicitly depicted in FIG. 2, the sensor signal of the UV sensor 120 during time period T.sub.3 may decrease due to the absence of the sparks.

[0060] In accordance with various embodiments of the burner control system 100, successful ignition of hydrogen gas (i.e., presence of flame 111) may be determined by detecting that the sensor signal of the UV sensor 120 comprises a first signal value that corresponds to the presence of both the sparks and the flame 111, after which the spark plug 140 may be controlled to stop emitting sparks. Alternatively, the spark plug 140 may be controlled to stop emitting sparks prior to the determination of a successful ignition, after which said successful ignition is determined based only on a second signal value of the UV sensor 120 that corresponds only to presence of the flame 111, said second value being lower than the aforementioned first value.

[0061] The controller 105 is preferably configured to control the controllable valve 114 to release gas immediately, and exclusively, upon successful detection of the emitted sparks. As such, no hydrogen gas is released during the pre-ignition state in case of, for example, a malfunction of the spark plug 140. Because unignited hydrogen gas may otherwise accumulate within the burner control system 100 or the boiler by which it is comprised, the risk of an unintended hydrogen explosion is reduced significantly.

[0062] In addition, the duration of the time period T.sub.3 of the ignition use state between the emission of sparks, followed by the release of hydrogen gas, ignition, up to successful detection of the hydrogen flame (the combustion state), may be reduced to a minimum. As such, the amount of hydrogen gas released at the time of ignition is likewise reduced to a minimum, resulting in an ignition of the hydrogen gas with only minimal (i.e. generally non-explosive) intensity. Secondly by reducing the time wherein it is allowed to ignite (the time between opening of the gas valve and the detection of the hydrogen flame) to a minimum, the amount of unignited hydrogen gas is also reduced to a minimum in case ignition (and therefore the hydrogen flame) has not been established at the end of the aforementioned time. In case ignition will happen at the end of the aforementioned time, the intensity of ignition of the hydrogen gas can still be limited to an, for the user of the system, acceptable level.

[0063] Time period T.sub.4 corresponds to a combustion use state of the burner control system 100 in which hydrogen gas emitted by the burner 110 is continuously combusted to supply heat to a heating system (not shown) to which the burner control system 100 is connected. The UV sensor 120 may continuously or periodically obtain a measurement signal in this use state to be fed to the controller 105. The controller 105 determines the presence or absence of a hydrogen flame 111 based on this measurement signal, which is indicative for a UV light level, and determines that the burner control system 100 is in the combustion state.

[0064] The controller 105 is preferably configured to determine if the measurement signal indicative for the UV light level is above a pre-determined threshold indicative for a presence of the hydrogen flame 111. This threshold indicative for a presence of the hydrogen flame 111 may be higher than the measurement signals of the UV sensor 120 during the inactive state of time period T.sub.1, the pre-ignition state of time period T.sub.2 and the ignition state of time period T.sub.3. However, as described hereabove the present disclosure is not limited thereto.

[0065] In the event that the hydrogen flame 111 extinguishes in the combustion state of the burner control system 100, the controller 105 may determine that the hydrogen flame 111 is absent based on the measurement signal from the UV sensor 120. In response, the controller 105 may control the burner control system 100 to perform a safety procedure to thereby prevent an accumulation of explosive hydrogen gas from occurring. Actions performed during a safety procedure may be closing of the controllable valve 114 so that no more hydrogen gas is emitted, stopping an operation of a fan comprised by the burner control system, and performing a safety shutdown of the burner control system 100 as a whole.

[0066] The unexpected extinguishing of the hydrogen flame 111 is represented in FIG. 2 by the diminishing measurement value of the UV sensor 120 in time period T.sub.5 that represents a normal use state, wherein the burner is expected to burn.

[0067] Period T.sub.5 also shows an alternative line of an increasing measurement value of the UV sensor 120, that may be indicative on an increased load offered by the burner 110. The load offered by the burner may be modulated to increase or decrease depending on a load that is requested from the burner control system 100. In accordance with preferred embodiments of the burner control system 100, the controller 105 is configured to determine a load of the burner 110 based on the measurement signal of the UV sensor 120 and a known hydrogen gas-air ratio of the hydrogen gas emitted by the burner 111. The UV light 116 emitted by the hydrogen flame 111 may be representative for a theoretical load corresponding to a given known hydrogen gas-air ratio of gas supplied by the burner 110. By comparing the load according to the measurement signal of the UV sensor 120 with a predetermined or predefined load, the operation of the burner control system 100 may be monitored during the combustion state of the burner control system 100. Leakages or blockages of the hydrogen gas conduit, blockage of the combustion air intake, or blockage of the flue gas exhaust system, may be detected by comparing the load as derived from measurement signal of the UV sensor 120 with a predetermined or set load. The burner control system 100 may initiate the here above described safety procedure if the load as derived from measurement signal of the UV sensor 120 does not match the predetermined or set load.

[0068] The burner control system 100 may moreover adjust the load by further opening or closing the controllable valve 114 to thereby adjust the load. In FIG. 2 during the time period T.sub.5, an exemplary increase of the burning load is shown, which is represented by the increasing value of measurement signal of the UV sensor 120 during this period.

[0069] In accordance with certain embodiments of the burner control system 100, wherein the use state of the burner is the inactive state of time period T.sub.1 of FIG. 2, the controller 105 is configured to perform a zero-level signal measurement indicative for a background level of UV light using the UV sensor 120. Because no hydrogen flame 111 is present in this inactive state, the zero-level signal measurement indicative for a background level of UV light comprises only noise and optionally a background level of UV light. The controller 105 may utilize this value to determine the subsequent measurement signals of the UV sensor 120, including those during the use states of time periods T2 to T5. In particular, the controller 105 may determine the values of these signals by subtracting the zero-level signal from these subsequent measurement signals.

[0070] The present disclosure provides a burner control system 100 of or for a heating system, the burner control system 100 comprising the controller 105, the a burner 110 connectable to a hydrogen gas supply 112 and comprising a controllable valve 114 coupled to the controller 105, and a UV sensor 120 disposed at the burner 110 and coupled to the controller 105, wherein the controller 105 is configured to determine a use state of the burner 110 based on a measurement signal of the UV sensor 120 that is indicative for a UV light level, and to selectively control the controllable valve 114 in dependency of said use state of the burner 110.

[0071] The present disclosure moreover provides a method for controlling the herein disclosed burner control system 100.

[0072] The invention presently disclosed is intended as burner control system 100 that can be applied for hydrogen gas-based heating systems or as a burner control system that is otherwise improved relative to known burner control systems in terms of safety and operational reliability.

[0073] It is noted here that the scope of protection for the developments described in the present disclosure are by no means limited to any particular feature of the embodiments described above and illustrated in the appended drawing. In particular the here above described UV sensor 120 may alternatively be an optical sensor 120 configured to detect visible or infrared light. Such a sensor may detect sparks emitted by the spark plug 140 and/or a flame 111 produced by the combustion combustible gasses other than hydrogen. Likewise, it should be understood that at least some of the merits of the present invention may also be achieved when utilising non-hydrogen combustible gasses, and the hereabove description is also applicable for these embodiments of the present invention unless otherwise accounted for.

[0074] Moreover, in the embodiments elucidated here above the ignition means for igniting hydrogen or other types of combustible gas are embodied as the spark plug 140. However, the present disclosure is not limited thereto. Alternatively, an auxiliary burner or pilot light (not shown) may be utilised for this purpose, both of which should be interpreted as examples of what constitutes a spark plug (or ignition means) within the context of the present disclosure. The skilled person will acknowledge that the here above technical principles of the operation and function of the spark plug 140 are, by and large, likewise applicable to such an auxiliary burner or pilot light. In particular, UV or visible light emitted by such an auxiliary burner or pilot light may be sensed by the UV or optical sensor 120, with the resultant sensor signal value then being processed further as described here above.

[0075] The scope of protection is, therefore, exclusively determined based on the limitations of the appended independent claims, but may, in some jurisdictions, even encompass obvious alternatives for features in the independent claims. Other variations for specifically described elements, components and functionalities, that may also be embodied within the scope of the appended claims of the present disclosure, have been at least hinted at in the above embodiment description or the skilled person may be considered to be able to contemplate these variations within the range of this skilled person's general knowledge. This exemplary reference to alternative embodiments substantiates that any limitation to any specific feature, that is not defined as a limitation in the independent claims, is unwarranted.