JP4042133B2 - Combustion safety device - Google Patents

Description

  The present invention relates to a combustion safety device that determines the occurrence or abnormality of combustion conditions in, for example, a boiler or a water heater.

  Conventionally, combustion safety devices have been widely used for judging abnormality of combustion states in boilers, water heaters, and the like. As shown in FIG. 5, for example, a UV sensor (flame detector) 51 is disposed in the vicinity of the main burner 52, and the flame ignited in the main burner 52 is detected by the UV sensor 51. This detected value is taken into the combustion safety device 60. Then, as shown in FIG. 6, the combustion safety device 60 includes a flame signal amplifier 61 that amplifies the output from the UV sensor 51, and a frame relay 65 that turns on when the flame signal amplifier 61 determines that there is a flame. In the A / D converter 62 for A / D converting the flame signal output of the flame signal amplifier 61, the combustion sequence unit 63 for storing the state of the combustion sequence in advance and determining the current combustion state, and the combustion sequence unit 63 An abnormality determination unit 64 that compares the obtained current combustion sequence state with the frame data obtained from the A / D converter 62 to determine whether the combustion state is abnormal is provided (for example, refer to Patent Document 1). .

  As a specific signal processing method, the flame signal obtained from the UV sensor 51 is amplified by the flame signal amplifier 61, digitized by the A / D converter 62, and taken into the abnormality determination unit 64 as frame data. At the same time, the combustion sequence unit 63 determines whether the combustion state is immediately after the ignition trial time, whether it is in a stable combustion state, misfire or in a combustion stop state, etc., and information on this current combustion sequence state is abnormally determined. Inform section 64. When the frame data exceeds the threshold corresponding to this combustion sequence state, it is determined that the combustion state is abnormal. Since such a combustion safety device 60 always grasps the combustion sequence state via the combustion sequence unit 63 and determines the occurrence of an abnormality in the combustion state while capturing the frame data, it has a complicated configuration in the normal combustion safety device. It can be said that it has.

  Note that there are many types of combustion safety devices in which the cost is reduced by using a simple configuration without the combustion sequence unit instead of the combustion safety device 60 having the complicated configuration as described above. In this combustion safety device, the combustion sequence section for judging the sequence state in the above-mentioned conventional combustion safety device and sending it to the abnormality judgment means is omitted, and the flame signal obtained by the flame detector is used as the flame signal amplifier. Is converted by an A / D converter, and an abnormality in the combustion state is determined only from the converted frame data.

JP-A-8-145350 (second page, FIG. 4)

  On the other hand, in addition to the burner 52 having the conventional general structure shown in FIG. 5, a specially shaped burner is gradually being used in the market these days. As an example of such a specially shaped burner, there is a radiant tube burner 70 as shown in FIG. In this radiant tube burner 70, an igniting portion 72 of a burner is inserted into one end portion of a radiant tube 71 made of a circular tube bent into a substantially U shape, and fuel gas is supplied to the radiant tube burner 70 in the igniting portion 72. Burn. And the whole radiant tube is heated by heating the air in a radiant tube, and thereby, for example, boiler water is heated or the air of an air conditioner is heated, and indoor heating etc. are performed.

  Since the radiant tube burner 70 has such a unique structure, the UV sensor 75 can be disposed only in the vicinity of one end opening of the radiant tube 71 provided with the ignition portion 72. Therefore, the UV sensor 75 detects the presence / absence of a flame from the rear side of the flame (left side in the drawing) due to the restriction of the arrangement condition, and the sensor arrangement is quite difficult to detect the presence / absence of the flame.

  In addition to such a radiant tube burner 70, a new type of burner called a surface combustion burner 80 shown in FIG. The surface combustion burner 80 is a ceramic surface combustion plate 81 provided with a fine honeycomb-shaped combustion gas supply section, and a heated object 82 arranged opposite to the surface combustion plate 81 at a predetermined narrow interval. , 83. Since the fuel supply part of the surface combustion plate 81 is formed in a honeycomb plate shape having innumerable honeycomb holes in this way, the size of each flame itself becomes very small, and this infinite number of flames It becomes a special combustion state that spreads over. As shown in the figure, the arrangement location of the UV sensor 85 is limited only to the side portion of the burner body due to structural limitations. Therefore, the restriction on the arrangement of the UV sensor 85 and the small flame spreading on the surface combustion plate 81 described above make the flame detection by the UV sensor 85 difficult.

  In this way, in addition to the general burner described at the beginning, when detecting a flame that is difficult to detect in the radiant tube burner or detecting a small flame in the surface combustion burner, these abnormal combustion conditions are not generated. In addition to the necessity for determination, there is also a desire to determine the abnormal tendency of the combustion state in all these types of burners.

  On the other hand, as in the conventional combustion safety device having the complicated configuration described above, the flame data obtained from the flame signal amplifier 61 via the A / D converter 62 is converted into the combustion sequence state obtained by the combustion sequence unit 63. It is also possible to determine an abnormality in the combustion state related to the above-described radiant tube burner or surface combustion burner while sequentially comparing. However, providing such a complicated and highly functional combustion safety device 60 with such a structure in every burner (combustion device) is problematic in terms of cost.

  Further, the flame signal from the UV sensor 51 is converted into frame data via the flame signal amplifier 61 and the A / D converter 62 without obtaining the above-described sequence state information from the combustion sequence unit 63, and only the frame data is obtained. The conventional simple combustion safety device for judging the abnormality of the combustion state is inexpensive and does not cause a cost problem. However, a combustion stabilization time of, for example, 10 seconds until the combustion of the burner is stabilized, and a flame response time of, for example, 4 seconds from when the flame starts to decrease at the same time when the fuel valve is closed until the combustion is completely stopped and the combustion stops. Frame data fluctuates considerably. For this reason, it is necessary to take some measure so that these times when the combustion is not abnormal are not determined to be abnormal in such a simple combustion safety device.

  In taking such a measure, it is not known only in the flame sequence obtained from the flame signal amplifier 61 via the A / D converter 62 what combustion sequence state is present. It is necessary to set the threshold value to a constant value and determine a sufficient difference between the frame data and the threshold value.

  However, in the radiant tube burner 70 and the surface combustion burner 80 as described above, the UV signals 75 and 85 are arranged in a place where flame detection is difficult, or the flame itself is small, so the flame signal is very small. Become. Therefore, if there is a sufficient difference as described above between the flame data in the steady combustion state of the flame and the threshold value, the radiant tube burner 70 and the surface combustion burner 80 accurately determine the abnormality of the combustion state. It becomes difficult to determine the abnormal tendency of the combustion state.

  Also, the frame data when the frame data at the time of rising and falling is unstable is taken into the abnormality determination unit 64 via the A / D converter, and it is diagnosed that there is an abnormality even though there is no abnormality in the combustion device. There is also a risk of it.

  An object of the present invention is to provide a simple structure that can determine not only the occurrence of an abnormality in a flame combustion state but also an abnormal tendency without taking a complicated structure to determine the state of a flame signal while observing the combustion sequence state. It is to provide a combustion safety device.

  In order to solve the above-described problems, a combustion safety device according to the present invention includes a signal amplifier that performs signal processing of a flame signal from a flame detector in a combustion safety device that determines the occurrence or tendency of an abnormality in a combustion state, and a flame. A frame relay that is turned on / off according to the presence / absence and an arithmetic device provided in the signal amplifier, and the arithmetic device determines whether or not there is an abnormality in the combustion state or an abnormal tendency only while the frame relay is on. And when the total time of the flame signal stabilization time and the frame response timing time has elapsed from the time when the output of the frame relay rises, the determination is sequentially started, and in the determination, from the determination time The difference in combustion state is also obtained by comparing the frame data detected before the frame response timing time with a predetermined threshold value. The generation or abnormal trends is characterized by determining on the determination time.

  When the sum of the flame signal stabilization time and the flame response timing time has elapsed from the time when the output of the frame relay rises, the determination of the occurrence or abnormality of the combustion state is started. It is possible to cancel the determination at a time when a rapid change (rise) of the frame voltage occurs.

  Also, while the frame relay is on, the determination is made based on the frame data before the frame response timing time from the determination time, so the time when the frame voltage rapidly decreases due to misfire or combustion stop The determination at can be canceled.

  Accordingly, it is possible to determine the abnormality of the combustion state with a simple configuration based only on the frame data and the predetermined threshold without requiring information on the state of the combustion sequence.

  In addition, since the determination is performed only when the combustion is stable, the threshold used for the determination can be brought close to the flame voltage in the state where the combustion is stable. Thus, it is possible to determine a so-called abnormal tendency in which a sign of occurrence occurs.

  In particular, the present invention is applied even when the flame sensor such as a radiant tube burner is difficult to detect a flame, or when the size of the flame such as a surface combustion burner is small and the flame sensor is difficult to detect the flame. The combustion safety device according to can reliably determine the abnormal tendency of the combustion state.

  Further, the combustion safety device according to claim 2 of the present invention is the combustion safety device according to claim 1, wherein a predetermined time before the time when the abnormality occurrence or abnormality tendency is determined at the time of occurrence of abnormality or abnormality tendency is determined. It is characterized by outputting the frame data history together.

  By referring to the frame data history for a predetermined time before the time when abnormality occurrence or abnormality tendency is determined, it is possible to accurately determine what kind of abnormality has occurred or what kind of abnormality tends to occur.

  As described above, the combustion safety device according to the present invention has the occurrence or tendency of abnormality in the combustion state when the total time of the flame signal stabilization time and the flame response timing time has elapsed since the output rise time of the flame relay. Therefore, it is possible to cancel the determination at the time when the flame voltage suddenly changes (increases) at the start of combustion.

  Also, while the frame relay is on, the determination is made based on the frame data before the frame response timing time from the determination time, so the time when the frame voltage rapidly decreases due to misfire or combustion stop It is possible to cancel the determination at.

  Accordingly, it is possible to determine the abnormality of the combustion state with a simple configuration based only on the frame data and the predetermined threshold without requiring information on the state of the combustion sequence.

  In addition, since the determination is performed only when the combustion is stable, the threshold used for the determination can be brought close to the flame voltage in the state where the combustion is stable. Thus, it is possible to determine a so-called abnormal tendency in which a sign of occurrence occurs.

  In particular, the present invention is applied even when the flame sensor such as a radiant tube burner is difficult to detect a flame, or when the size of the flame such as a surface combustion burner is small and the flame sensor is difficult to detect the flame. The combustion safety device according to can reliably determine the abnormal tendency of the combustion state.

  Further, the combustion safety device according to claim 2 of the present invention refers to what kind of abnormality has occurred or what kind of abnormality has occurred by referring to the frame data history for a predetermined time before the time when abnormality occurrence or abnormality tendency is determined. It is possible to accurately determine whether such an abnormal tendency exists.

  Hereinafter, a combustion safety device according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a combustion safety device 1 according to an embodiment of the present invention includes a flame signal amplifier 10 that determines the presence or absence of a flame based on an output signal from a UV sensor (flame detector) 35, and a flame signal amplifier. 10 includes a frame relay 15 whose output is turned on when it is determined that a flame is present, and a microcomputer (arithmetic unit) 20 that captures a detection result of the flame signal amplifier 10 and accumulates a history of frame data for a certain period of time. . The microcomputer includes an A / D converter 21 that converts an analog signal of the flame signal amplifier 10 into a digital signal, and a memory 22 that stores a certain amount of the digital signal of the A / D converter 21. Then, the microcomputer 20 determines whether or not there is an abnormality in the combustion state or an abnormal tendency, and issues an external report.

  Further, the microcomputer 20 is additionally provided with an event relay 25. The event relay 25 can report the content of the abnormality to the outside only when a specific abnormality occurs or a specific abnormality tendency is observed during steady combustion. Yes. In addition, since the event relay 25 is not necessarily an essential requirement in the present invention, the event relay 25 is not necessarily provided in the combustion safety device 1.

  Further, the above-described combustion safety device 1 does not include a combustion sequence unit inside, and a combustion safety device 60 of a type that sequentially captures information on the combustion sequence from the combustion sequence unit 63 as shown in FIG. It is an inexpensive type of combustion safety device that is different from the above.

  Next, the function of the microcomputer 20 in the combustion safety device 1 will be described in detail. As shown in FIG. 2, the microcomputer 20 determines the occurrence or tendency of an abnormality in the combustion state only while the frame relay 10 is on, that is, while the UV sensor 35 detects that there is a flame. . Then, the microcomputer 20 waits for the flame signal to stabilize during the start-up of the frame relay 10 as shown in FIGS. 2 and 3 (hereinafter referred to as “combustion stabilization time”). )) And the flame response timing time (time from combustion stop / misfire until flame relay is turned off) Tb, the combustion state abnormality occurrence or abnormality tendency is sequentially determined. Note that the memory 22 stores the past frame data (in this embodiment, 10 seconds) for at least a certain time longer than the frame response timing time Tb from this determination time point. In this determination, determination is made using frame data detected before the frame response timing time from the determination time. Then, the frame data is compared with a predetermined threshold A (see dotted line A in FIG. 2). This threshold value is set as a threshold value that is closer to the flame voltage in the stable combustion state than the threshold value B (see the two-dot chain line B in FIG. 2) in the conventional simplified combustion safety device. When the detected frame data exceeds (below) the threshold value A, the microcomputer 20 issues an abnormality occurrence or abnormality tendency.

  At the same time as the frame relay 10 is turned on, the history of frame data is sequentially stored in the memory 22 of the microcomputer 20 for, for example, the latest 10 seconds. When an abnormality occurs or an abnormal tendency is seen in the combustion state, the history of frame data is output 10 seconds before this determination time, and the frame data is displayed on a display (display means) (not shown) connected to the outside. The history of is displayed as a trend. In this way, it is possible to easily grasp what kind of abnormality has occurred or abnormal tendency has been observed during combustion.

  Subsequently, a specific determination method relating to the occurrence or tendency of abnormality of the combustion state unique to the present invention using such an inexpensive combustion safety device 1 will be described in correspondence with the combustion sequence.

  FIG. 2 is a diagram showing the relationship between the flame voltage detected by the flame detector 35 and the combustion sequence. As is clear from the figure, when the combustion starts, the valve opens and an ignition trial (ignition operation) is performed, and the fuel gas starts to ignite. In the initial state of the start of combustion, the flame grows rapidly, and accordingly, as shown in detail in FIG. 3, the flame voltage corresponding to the flame signal detected by the UV sensor 35 rises while fluctuating with a fine amplitude. (In FIG. 3, fine fluctuations in the rising frame voltage are not shown). In the initial state of the start of combustion, the flame signal amplifier 10 detects an increase in the flame voltage, and the output of the flame relay 10 is turned on. The flame voltage is applied to the flame until it burns stably, and stabilizes after a while. Thereafter, the stabilized combustion state is maintained as shown in FIG. Note that even if the flame is stable, the flame voltage may suddenly drop by a slight value due to gas pressure drop or momentary power interruption (see X and Y in Fig. 2). The frame voltage may gradually decrease by a slight value due to clogging of the filter (see Z in FIG. 2).

  When the valve is closed at a certain point in time, the flame rapidly decreases from this stable combustion state, and the flame voltage also decreases correspondingly as shown in FIGS. When the frame voltage decreases to a certain value, the flame signal amplifier 10 detects this and turns off the output of the frame relay 10.

  Next, the reason why the voltage that approximates the flame voltage in the above-described combustion stabilization state can be used as the determination threshold value even though the combustion safety device 1 has a simple configuration that does not have the combustion sequence unit.

  In this embodiment, the microcomputer 20 has an abnormality in the combustion state from the time when the frame relay 10 is turned on to the time when the combustion stabilization time Ta and the frame response timing time Tb are summed (see the start point of the determination time P in FIGS. 2 and 3). Judgment of occurrence or abnormal tendency has started. In this determination, the frame data obtained before the frame response timing time Tb from the determination time (refer to the starting point of the substantial determination time Q in FIGS. 2 and 3) is compared with a threshold value.

  Therefore, the microcomputer 20 does not determine the occurrence or tendency of abnormality in the combustion state for the time during which the flame voltage increases while the flame voltage immediately after the start of combustion is extremely high, that is, the time until the combustion is stabilized.

  Further, since the frame relay 10 is ON and only the frame voltage before the frame response timing time from the determination time is detected as the frame data in the determination, the flame is caused by the burner misfire or the combustion stop. About the frame voltage only at the time when it disappears, that is, when the frame relay 10 falls (see the end point of the determination time point P in FIGS. 2 and 4) and before the frame response time (see the end point of the determination time point Q in FIGS. 2 and 4). Deciding. That is, in the frame response time when the flame voltage rapidly decreases, the determination of the occurrence or tendency of abnormality in the combustion state is not performed.

  As described above, the combustion safety device 1 according to the present embodiment cancels the determination from the time when the output of the frame relay 10 rises (at the start of combustion) to a point in time after the output of the frame relay 10 is on, and also determines the combustion state. By canceling the determination until a point in time before the certain time (frame response timing time), it is possible to determine the occurrence or tendency of an abnormality in the combustion state from the frame data only when the frame voltage is stabilized Become.

  Therefore, it is possible to make the threshold value A used for determining the occurrence or tendency of abnormality in the combustion state quite close to the flame voltage in the combustion stabilization state. As a result, even when the flame is in a stable combustion state, the flame voltage suddenly drops by a slight value due to a gas pressure drop or a momentary power interruption (see X and Y in FIG. 2), power supply drop and air volume Even if the flame voltage gradually decreases by a small value due to a decrease, filter clogging, etc. (see Z in FIG. 2), the combustion safety device according to the present embodiment is in this way despite the simple configuration. Therefore, it is possible to reliably determine an abnormal tendency of the combustion state.

  In addition, when an abnormality occurs or an abnormal tendency is observed in the combustion state, a history of frame data is output retroactively from this determination time to a certain time (10 seconds in the present embodiment) and connected to the outside. The history of frame data is displayed as a trend on a display (display means) that does not. As a result, it is possible to easily grasp what kind of abnormality has occurred or abnormal tendency has been observed during combustion. As a result, the maintenance staff is freed from the trouble of connecting the recorder to the combustion safety device of the boiler and determining the combustion abnormality while observing the trend of the frame data obtained from the recorder, and the effect is great.

  As described above, the conventional simplified combustion safety device has an abnormality in the combustion state with respect to the flame stabilization time until the combustion state is stabilized and the flame voltage of the flame response time when the flame disappears due to misfire or combustion stop. It was included in the judgment of occurrence or abnormal tendency. For this reason, the threshold value for occurrence of abnormality in the combustion state must be set to a fairly low value with a margin (see threshold value B indicated by a two-dot chain line in FIG. 2). Obviously, it was impossible to determine the trend.

  However, as described above, the combustion safety device according to the present embodiment captures a slight change in the flame voltage in the combustion stabilization state, and makes it possible to determine the occurrence or tendency of abnormality in the combustion state based on this. For this reason, normal combustion conditions such as a radiant tube burner that must detect the flame signal with the flame detector positioned behind the flame, and a surface combustion burner that has a very low flame voltage because the flame itself is very small, are not. However, even in a burner with a small amount of ultraviolet light entering the flame detector, it is possible to reliably determine not only the abnormality of the combustion state but also the abnormal tendency.

  Further, by using the event relay 25 that is selectively added in the present embodiment, it is possible to selectively output the occurrence or abnormality of the combustion state according to the type. Specifically, as described above, a sharp fall of the frame voltage such as a gas pressure drop or a momentary power failure is distinguished from a gradual fall such as a power drop, an air flow drop, or a filter clogging, and these are all within a certain period of time. When it occurs more than a predetermined number of times, the contents can be output from the event relay. It is also possible to output from the event relay by distinguishing whether a combustion state abnormality has occurred or an abnormal tendency depending on the degree of the fall. Furthermore, it is also possible to selectively issue some of these abnormalities according to the types of these abnormal states.

  In the above description, the threshold is set near the lower side of the flame voltage in the combustion stabilization state. However, a new threshold is set near the upper side of the flame voltage in the combustion stabilization state, and the flame is too large. The occurrence or abnormal tendency of combustion at the time may be determined.

  In addition, as described above, it is possible to detect slight combustion abnormalities due to deterioration over time of the burner itself by bringing the threshold value for determining the occurrence or abnormality of the combustion state close to the flame voltage of the normal combustion state. Thus, it can also be used to detect structural deterioration of the burner itself.

  Note that the A / D converter described in the present embodiment is not necessarily required for carrying out the present invention, and it is possible to perform combustion abnormality diagnosis based on the flame voltage obtained from the flame amplifier.

  Various flame sensors other than the above-described UV sensor, such as a visible light flame detector, an infrared flame detector, and a frame rod, can be used as the flame sensor.

  Needless to say, the present invention can be implemented in a combustion safety device that does not include a microcomputer.

  In addition, in the present invention, it was introduced in a mode in which it is determined that there is a flame only while the frame relay is on, but separately from this, a combustion safety device in a mode in which it is determined that there is a flame only while the frame relay is off. Needless to say, the present invention is applicable.

  Needless to say, the frame relay may be an electronic output means as long as it is a means capable of notifying the presence or absence of a flame.

  The present invention is not limited to application to a combustion device such as a boiler or a water heater, for example, but various combustion safety devices that determine the occurrence or tendency of an abnormality in a combustion state using a flame detector, such as a heating device or a combustion furnace It is also applicable to.

1 is a schematic block diagram of a combustion safety device according to a first embodiment of the present invention. It is the figure which showed the flame voltage of the combustion safety device shown in FIG. 1, flame relay output, and the relationship of a combustion sequence state. It is the figure which showed in detail the state from the ignition of the flame in FIG. 2 to stabilization. It is the figure which showed in detail the state until the misfire of the flame in FIG. 2, or a combustion stop. It is the schematic which showed the positional relationship of the conventional burner, a combustion safety device, and a flame sensor. It is the block diagram which showed the conventional combustion safety device. It is the schematic which showed the schematic structure of the radiant tube burner, and the UV sensor with which it was equipped. It is the schematic which showed the schematic structure of the surface combustion burner, and the UV sensor with which it was equipped.

Explanation of symbols

1 Combustion safety device 10 Flame amplifier 15 Frame relay 20 Microcomputer (computing device)
21 A / D converter 22 Memory 25 Event relay 35 UV sensor 51 UV sensor 52 Main burner 60 Combustion safety device 61 Flame signal amplifier 62 A / D converter 63 Combustion sequence part 64 Abnormality judgment part 65 Frame relay 70 Radiant tube burner 71 Radiant tube 72 Burner ignition part 75 UV sensor 80 Surface combustion burner 81 Surface combustion plate 82, 83 Heated object 84 UV sensor 85 UV sensor

Claims (2)

In the combustion safety device that determines the occurrence and tendency of abnormalities in the combustion state,
A signal amplifier that processes a flame signal from a flame detector, a frame relay that is turned on / off in accordance with the presence or absence of a flame, and an arithmetic unit provided in the signal amplifier;
The arithmetic unit is configured to determine whether or not there is a combustion state abnormality or an abnormal tendency only while the frame relay is on, and the flame signal stabilization time and frame response from the output rise time of the frame relay. When the total time with the timing time has elapsed, the determination is sequentially started, and in the determination, the frame data detected before the frame response timing time is compared with a predetermined threshold. A combustion safety device characterized by determining occurrence or abnormality of combustion state at the determination time.   2. The combustion safety device according to claim 1, wherein a frame data history for a predetermined time before the time when the occurrence of an abnormality or an abnormality tendency is determined is output together with the determination of occurrence or abnormality.

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