Flame monitoring device, flame monitoring program, and flame monitoring method

Abstract

To provide a flame intensity monitoring device capable of allowing a user to properly grasp malfunction of a combustion device.SOLUTION: A flame intensity monitoring device includes: an acquisition portion 21A for acquiring voltage values VF1-VF4 indicating intensity of flame of a main burner in each of a plurality of sub-sequences constituting a combustion sequence of a combustion device burning a fuel by igniting the main burner; and an analysis portion 21B for statistically analyzing an aggregate of intensity of the flame of combustion sequences of several times acquired by the acquisition portion 21A by each sub-sequence, and obtaining statistic data of the aggregate as latest statistic data. Further the flame intensity monitoring device includes a comparison portion 21C for comparing the latest statistic data with reference statistic data as a reference, prepared as the statistic data of the aggregate of the intensity of the flame in executing the combustion sequence several times, and outputting each result of the comparison.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a flame monitoring device, a flame monitoring program, and a flame monitoring method for monitoring the flame activity of a burner provided in a combustion device. [Background technology]

[0002] In a combustion device, burners are ignited and combustion is performed by the burners according to a combustion sequence consisting of a number of predefined subsequences. Regarding such a combustion device, Patent Document 1 discloses a technique for monitoring the flame activity (here, flame strength) of the burner for each of a number of subsequences ("pilot trial", "pilot only", "main trial", and "main stable"), and determining that the combustion device is in a malfunction when the flame activity is within a normal range defined for each subsequence but deviates from the normal state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-60573 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 is also useful, but it is difficult for a user to properly grasp, for example, a malfunction tendency of the combustion device (such as a tendency for a malfunction to occur). In addition, with this technology, it is also possible that the combustion device may be determined to be malfunctioning even when, for example, the flame activity becomes abnormal due to a sudden event that is not caused by a malfunction. As described above, it is difficult to say that the technology described in Patent Document 1 allows a user to properly grasp a malfunction of the combustion device.

[0005] An object of the present invention is to provide a flame monitoring device, a flame monitoring program, and a flame monitoring method that allow a user to appropriately grasp malfunctions in a combustion device. [Means for solving the problem]

[0006] In order to solve the above problems, a flame monitoring device according to a first aspect of the present invention comprises an acquisition unit configured to acquire the flame activity of a burner in each of a plurality of subsequences that constitute a combustion sequence of a combustion device that ignites a burner and burns fuel; an analysis unit configured to statistically analyze, for each subsequence, a set of the flame activity of the combustion sequence acquired by the acquisition unit and obtain statistical data of the set as first statistical data; and a comparison unit configured to compare, for each subsequence, the first statistical data with second statistical data that serves as a standard and is prepared as statistical data of the set of the flame activity when the combustion sequence is executed a plurality of times, and output each comparison result.

[0007] The analysis unit may be configured to statistically analyze, for each subsequence, a set of the flame activity of each of the combustion sequences, which is an equal number of the combustion sequences that were executed before a malfunction occurred in the combustion device and before the plurality of the combustion sequences, acquired by the acquisition unit, using the same method as when acquiring the first statistical data, and to acquire statistical data of the set as the second statistical data.

[0008] The first statistical data may include first distribution data indicating a distribution of the number of flame activity levels belonging to each flame activity class, and the second statistical data may include second distribution data indicating a distribution of the number of flame activity levels belonging to each flame activity class.

[0009] The comparison unit may be configured to compare the first statistical data with the second statistical data by graphing the first distribution data and the second distribution data in association with each other, with a first axis representing the class of flame activity and a second axis representing the number of flame activity levels, and output each graph of the first distribution data and the second distribution data in association with each other as the comparison result.

[0010] The comparison unit may be configured to generate a radar chart representing a difference between the first statistical data and the second statistical data, with each of the plurality of subsequences as an item, and to output the generated radar chart as the comparison result.

[0011] The comparison unit may be configured to estimate the presence or absence of a malfunction of the combustion device and, if a malfunction occurs, the type of the malfunction based on a difference between the first statistical data and the second statistical data of each of the plurality of subsequences, and to output a result of the estimation as the comparison result.

[0012] The comparison unit may be configured to, when all of the differences between the first statistical data and the second statistical data for each of the multiple subsequences indicate a tendency for the first statistical data to have a lower flame activity than the second statistical data, estimate that the type of malfunction is at least one of dirt on a window that transmits the electromagnetic waves incident on a flame detector that detects the flame activity of the combustion device using electromagnetic waves from the flame, and a disturbance in the air-fuel ratio of the fuel and air supplied to the burner.

[0013] The comparison unit may be configured to, when there is a difference between the first statistical data and the second statistical data in only some of the subsequences among the plurality of subsequences, estimate that the type of malfunction is that of a device that is used to execute the some of the subsequences among the devices that constitute the combustion device.

[0014] A flame monitoring program according to a second aspect of the present invention causes a computer to execute the following steps: an acquisition step of acquiring the flame activity of a burner in each of a plurality of subsequences that constitute a combustion sequence of a combustion device that ignites a burner and burns fuel; an analysis step of statistically analyzing, for each subsequence, a set of the flame activity of the combustion sequence for a plurality of times acquired in the acquisition step and acquiring statistical data of the set as first statistical data; and a comparison step of comparing, for each subsequence, the first statistical data with second statistical data that serves as a reference and is prepared as statistical data of the set of the flame activity when the combustion sequence is executed a plurality of times and outputting each comparison result.

[0015] A flame monitoring method according to a third aspect of the present invention includes an analysis step of statistically analyzing a set of flame activity of a plurality of subsequences that constitute a combustion sequence of a combustion device that ignites a burner and combusts fuel, and obtaining statistical data of the set as first statistical data, and a comparison step of comparing, for each subsequence, the first statistical data with second statistical data that serves as a reference and is prepared as statistical data of the set of flame activity when the combustion sequence is executed a plurality of times. Effect of the Invention

[0016] According to the present invention, a user can appropriately recognize malfunctions in a combustion device. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a configuration diagram of a combustion system having a flame monitoring device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a timing chart of the combustion sequence executed in the combustion system. [Diagram 3] 4 is a graph showing the progression of flame voltage during a portion of a combustion sequence. [Figure 4] FIG. 4 is a hardware configuration diagram of the flame monitoring device. [Diagram 5] FIG. 5 is a configuration diagram of a flame monitoring device. [Figure 6] FIG. 6 is a flowchart of a voltage value storage process executed by the acquisition unit. [Figure 7] FIG. 7 is a diagram showing an example of data contents of a frame voltage value group. [Figure 8] FIG. 8 is a flowchart of the reference statistical data generation process executed by the analysis unit. [Figure 9] FIG. 9 is a diagram showing an example of data content of the reference distribution data. [Figure 10] FIG. 10 is a graph (frequency line) of the reference distribution data of FIG. [Figure 11] FIG. 11 is a graph (frequency line) of the most recent distribution data and the reference distribution data for each subsequence on the same coordinate plane. [Figure 12] FIG. 12 is an example of a radar chart generated in the modified example. [Figure 13] FIG. 13 is a flowchart of an estimation result output process executed by a comparison unit according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention and its modified examples will be described with reference to the drawings.

[0019] (Embodiment) As shown in Fig. 1, a flame monitoring device 20 according to one embodiment of the present invention is used in a combustion system 10. The flame monitoring device 20 monitors the flame activity of a burner provided in a combustion device 40 (described below) of the combustion system 10, more specifically, a main burner 42 and a pilot burner 43, to detect a malfunction of the combustion device 30. "Malfunction" refers to an abnormality that allows the combustion device 30 to operate but not to the extent that it becomes inoperable, that is, a minor abnormality.

[0020] In addition to the flame monitoring device 20, the combustion system 10 includes a combustion device 30 that performs combustion, and a combustion control device 70 that controls the combustion device 30. Below, the combustion device 30 and the combustion control device 70 will be explained first, and then the flame monitoring device 20 will be explained.

[0021] The combustion device 30 includes a combustion appliance 40, a fuel supply system 50, an air supply system 60, a control motor M, a high opening position sensor HS, and a low opening position sensor LS.

[0022] The combustion equipment 40 burns the fuel gas in the combustion chamber R. The combustion equipment 40 includes a combustion furnace 41 that forms the combustion chamber R, a main burner 42 that burns the fuel gas to heat the inside of the combustion chamber R, a pilot burner 43 that burns the fuel gas to ignite the main burner 42, and an ignition device (igniter) 44 that ignites the pilot burner 43. The pilot burner 43 ignited by the ignition device 44 is used to ignite the main burner 42. Therefore, the ignition device 44 can also be said to be a device used when igniting the main burner 42. The ignition device 44 includes a spark generating unit 44A such as a discharge electrode.

[0023] The combustion equipment 40 further includes a flame detector 45 that detects the flame activity of the main burner 42 and the pilot burner 43, and a temperature sensor 46 that detects the temperature inside the combustion chamber R. The flame activity is a degree that indicates how actively the flame is generated, and in this case, it is the flame intensity.

[0024] The flame detector 45 includes a discharge tube 45A including two electrodes and a package that houses the two electrodes together with a predetermined gas. The flame detector 45 further includes a window 45B that transmits electromagnetic waves (here, ultraviolet rays) radiated from the flame of the main burner 42 or the pilot burner 43 and guides them to the discharge tube 45A. In the discharge tube 45A, when a voltage is applied between the two electrodes and the electromagnetic waves radiated from the flame of the main burner 42 or the pilot burner 43 are incident on the package, a discharge occurs between the two electrodes. This discharge causes an electric signal to be output from the flame detector 45. In this way, the flame detector 45 converts the intensity of the electromagnetic waves radiated from the flame of the main burner 42 or the pilot burner 43, that is, the activity of the flame, into an electric signal (also called a detection signal) and outputs it. Here, the output electric signal is a voltage signal whose voltage value changes according to the activity of the flame, but the electric signal may be a current signal whose current value changes according to the activity of the flame. The voltage signal is also called the flame voltage VF, and the current signal is also called the flame current IF. The voltage value of the flame voltage VF and the current value of the flame current IF indicate the activity of the flame. In the following description, the flame voltage VF and its voltage value can be replaced with the flame current IF and its current value.

[0025] Returning to Fig. 1, the fuel supply system 50 supplies fuel gas from the outside to the combustion appliance 40. The fuel supply system 50 includes a fuel flow path 51 through which the fuel gas supplied to the combustion appliance 40 flows. The fuel flow path 51 includes a main flow path 51A through which the fuel gas is supplied from the outside, and a first flow path 51B and a second flow path 51C branched from the main flow path 51A. The first flow path 51B is connected to the main burner 42, and the second flow path 51C is connected to the pilot burner 43.

[0026] The fuel supply system 50 further includes a gas pressure switch 52 provided in the main flow path 51A, main valves 54A and 54B which are safety shutoff valves provided in the first flow path 51B, and pilot valves 54C and 54D which are safety shutoff valves provided in the second flow path 51C. The gas pressure switch 52 is turned ON when the pressure of the fuel gas supplied from the outside is equal to or higher than a predetermined pressure. The main valves 54A and 54B open and close the first flow path 51B. The pilot valves 54C and 54D open and close the second flow path 51C. The fuel supply system 50 also includes a damper 55 for adjusting the fuel flow rate provided in the main flow path 51A.

[0027] The air supply system 60 supplies air to the combustion appliance 40. The air supply system 60 includes an air flow path 61 through which air to be supplied to the combustion appliance 40 flows, and a blower 62 that supplies air to the air flow path 61. The air flow path 61 includes a main flow path 61A connected to the blower 62, and a first flow path 61B and a second flow path 61C branched from the main flow path 61A. The first flow path 61B is connected to the main burner 42. The second flow path 61C is connected to the pilot burner 43.

[0028] The air supply system 60 further includes an air pressure switch 63 that is provided in the main flow path 61A and turns on when the air pressure from the blower 62 is equal to or higher than a predetermined air pressure. The air supply system 60 further includes a damper 65 for adjusting the air flow rate that is provided in the main flow path 61A.

[0029] The dampers 55 and 65 for adjusting the fuel or air flow rate are driven by a control motor M in a linkage to control the opening of the fuel passage 51 and the air passage 61. Driven by the linkage, the opening of each of the dampers 55 and 65 is controlled so that the air-fuel ratio, which is the ratio of fuel to air supplied to the main burner 42, is maintained at a desired ratio (a ratio within an ideal range for combustion). The amount of fuel and air supplied to the main burner 42 is adjusted by the opening of each of the dampers 55 and 65, and the flame activity of each burner is thereby adjusted, thereby controlling the heating temperature at which the combustion chamber R is heated.

[0030] The high opening position sensor HS detects when the dampers 55 and 65 reach a predetermined high opening position. The low opening position sensor LS detects when the dampers 55 and 65 reach a predetermined low opening position. Each of the sensors HS and LS turns ON when the dampers 55 and 65 reach the high opening position or the low opening position.

[0031] The combustion control device 70 is composed of various computers such as a PLC (Programmable Logic Controller) and a personal computer. The combustion control device 70 is also called a burner controller. The combustion control device 70 monitors the states (ON / OFF) of the gas pressure switch 52, the wind pressure switch 63, the high opening position sensor HS, and the low opening position sensor LS. Various signals are input to the combustion control device 70 from the flame detector 45, the temperature sensor 46, and the like. The combustion control device 70 controls the ignition device 44, the main valves 54A and 54B, the pilot valves 54C and 54D, the blower 62, and the dampers 55 and 65, and the like, based on the monitoring results and various signals.

[0032] The combustion control device 70 controls the operation of the combustion device 30 in accordance with a predetermined combustion sequence. This combustion sequence includes subsequences such as "start check," "pre-purge," "waiting for ignition," "pilot ignition," "pilot only," "main ignition," "main stable," and "steady combustion."

[0033] 2 shows a time chart of the combustion sequence from start-up of the combustion device 30 to steady combustion. When a start-up input is received from the outside (point t1 in chart A), the combustion control device 70 controls the blower 62 to start blowing air into the air flow path 61 (point t1 in chart B), and sends a drive command to the control motor M in the opening direction (point t1 in chart D). The drive command in the opening direction opens the dampers 55 and 65.

[0034] When the wind pressure caused by the air supply from the blower 62 reaches a predetermined wind pressure, the wind pressure switch 63 turns ON (point t2 in chart C). The period P1 from point t1 to point t2 is the "start check" time period.

[0035] When the air pressure switch 63 is turned ON and the high opening position sensor HS detects that the opening positions of the dampers 55 and 65 have reached the high opening position and turns ON (point t3 in Chart E), the combustion control device 70 starts timing the pre-purge time from this point on.

[0036] After the pre-purge time has elapsed, the combustion control device 70 sends a drive command to the control motor M in the closing direction (point t4 in chart D). This causes the dampers 55 and 65 to operate in the closing direction. The period P2 from point t3 to point t4 is the "pre-purge" time period.

[0037] When the low opening position sensor LS detects that the dampers 55 and 65 have reached the low opening position and turns ON (point t5 in chart F), after a predetermined waiting time has elapsed, the combustion control device 70 opens the pilot valves 54C and 54D (point t6 in chart G) and activates the ignition device 44 (point t6 in chart H). The predetermined waiting time is, for example, the time from when the low opening position is detected until the supply of fuel gas starts and the gas pressure switch 52 turns ON. The period P3 from point t4 to point t6 is the "ignition waiting" time zone.

[0038] By opening the pilot valves 54C and 54D, fuel gas is supplied from the fuel supply system 50 to the pilot burner 43, and the pilot burner 43 ejects the fuel gas. In this state, when the ignition device 44 is operated, an ignition spark is generated from the spark generating unit 44A of the ignition device 44, and this ignition spark ignites the fuel ejected from the pilot burner 43. This ignites the pilot burner 43. In this embodiment, air required for combustion of the fuel gas is also supplied from the air supply system 60 to the pilot burner 43, and is ejected from the pilot burner 43. The fuel supply system 50 and the air supply system 60 are configured so that the air-fuel ratio of the fuel and air supplied to the pilot burner 43 becomes the desired ratio (ideal ratio for combustion) when the dampers 55 and 65 are in the low opening position as described above. The pilot burner 43 may be configured to be ignited by the surrounding air.

[0039] The ignition of the pilot burner 43 is detected by the flame detector 45. The flame detector 45 outputs a detection signal indicating the flame activity of the pilot burner 43 to the combustion control device 70. The combustion control device 70 detects the ignition of the pilot burner 43 when it determines that the flame activity indicated by the detection signal has exceeded a predetermined first threshold value. Here, as shown in Chart I, it is assumed that the pilot burner 43 is ignited at point t7 and this ignition is detected.

[0040] When the combustion control device 70 detects ignition of the pilot burner 43, it terminates the operation of the ignition device 44, i.e., the generation of the ignition spark (point t8 in chart H). The period P4 from point t6 to point t8 during which the ignition device 44 is operated is the "pilot ignition" time period. When the combustion control device 70 cannot detect ignition of the pilot burner 43 for a predetermined period of time, it aborts the combustion sequence as a time-out.

[0041] After detecting the ignition of the pilot burner 43 and terminating the operation of the ignition device 44, the combustion control device 70 waits for a predetermined period until point t9. This predetermined period, i.e., period P5 from point t8 to point t9, is the "pilot only" time period during which the pilot burner 43 is burned alone. In "pilot only", the combustion control device 70 monitors the flame activity of the pilot burner 43 based on the detection signal from the flame detector 45. When the flame activity falls below a predetermined intensity during the above-mentioned predetermined period, the combustion control device 70 determines that the pilot burner 43 has misfired and stops the combustion sequence.

[0042] After the above-mentioned predetermined period has elapsed, the combustion control device 70 opens the main valves 54A and 54B (point t9 in chart J). By opening the main valves 54A and 54B, the supply of fuel to the main burner 42 is started. Air is also supplied to the main burner 42 from the air supply system 60. The main burner 42 in a state in which air and fuel are supplied ejects fuel and air, and ignites using the flame of the pilot burner 43 as a pilot flame. The flame detector 45 outputs a detection signal indicating the sum of the flame activity of the main burner 42 and the pilot burner 43 to the combustion control device 70. When the combustion control device 70 determines that the sum of the flame activity indicated by the detection signal exceeds a predetermined second threshold value, it determines that the main burner 42 has ignited. Here, as shown in chart K, it is assumed that the main burner 42 is ignited at point t10, and this ignition is detected.

[0043] When the combustion control device 70 detects the ignition of the main burner 42, it closes the pilot valves 54C and 54D to terminate the combustion of the pilot burner 54 (see point t11 ​​in charts G and I). The period P6 from point t9 to point t11 ​​is the “main ignition” time period during which the main burner 42 is ignited.

[0044] After detecting the ignition of the main burner 42 and closing the pilot valves 54C and 54D, the combustion control device 70 waits for a predetermined period until point t12. This predetermined period, that is, the period P7 from point t11 ​​to point t12, is the "main stable" time period during which the main burner 42 is burned alone. During the "main stable" period, the combustion control device 70 monitors the flame activity of the main burner 42 based on the detection signal from the flame detector 45. If the flame activity falls below a predetermined intensity during the predetermined period, the combustion control device 70 determines that the main burner 42 has misfired and stops the combustion sequence.

[0045] After waiting for the above-mentioned predetermined period, the combustion control device 70 starts feedback control of the control motor M so that the temperature in the combustion chamber R indicated by the detection signal supplied from the temperature sensor 46 becomes a target value, using the temperature as a feedback value (point t12 in chart D). The period from point t12 onwards is a "steady combustion" period in which the main burner 42 performs steady combustion. The specific method of feedback control in steady combustion is arbitrary, but for example, proportional control (P control), proportional-integral control (PI control), or proportional-integral-derivative control (PID control) is adopted. When the gas pressure switch 52 or the wind pressure switch 63 is turned OFF during steady combustion, the combustion control device 70 determines that an abnormality has occurred and stops steady combustion.

[0046] In the combustion sequence, the combustion control device 70 converts the flame voltage VF, which indicates the flame activity outputted sequentially from the flame detector 45, into analog-digital data at a predetermined sampling rate, and sequentially acquires and holds the voltage value of the flame voltage VF. FIG. 3 shows the transition of the flame voltage VF in the "pilot ignition" (period P4), "pilot only" (period P5), "main ignition" (period P6), and "main stable" (period P7) of the combustion sequence. In the "pilot ignition", the pilot burner 43 is ignited, so the flame voltage VF rises. Thereafter, the flame voltage VF is stable until the end of the "pilot only". Thereafter, in the "main ignition", the pilot burner 43 is ignited, so the flame voltage VF further rises. Thereafter, the flame voltage VF is stable until the point t11, which is the start of the "main stable". At the point t11, the pilot valves 54C and 54D are closed, and the pilot burner 43 misfires, so the flame voltage VF drops. After the drop, the flame voltage VF remains constant until the "steady combustion" state is reached. During the "steady combustion" state, the flame voltage VF changes depending on the opening degree of the dampers 55 and 65.

[0047] The combustion control device 70 outputs voltage values ​​VF1 to VF4 indicating the flame activity at each of the timings X1 to X4 of "pilot ignition", "pilot only", "main ignition", and "main stable" among the voltage values ​​acquired sequentially to the flame monitoring device 20. The combustion control device 70 may acquire voltage values ​​at a plurality of predetermined timings in each sequence, and output the average value, maximum value, or minimum value of the acquired plurality of voltage values ​​as the voltage values ​​VF1 to VF4 indicating the flame activity. The voltage values ​​VF1 to VF4 are output one by one in one combustion sequence. The combustion control device 70 may output the voltage values ​​VF1 to VF4 as one set after the four voltage values ​​VF1 to VF4 are collected.

[0048] Next, the flame monitoring device 20 will be described. The flame monitoring device 20 performs a process of monitoring the voltage values ​​VF1 to VF4 from the combustion control device 70, that is, the flame activity detected in the above four subsequences. The flame monitoring device 20 is configured to include various computers such as a personal computer. As shown in FIG. 4, the flame monitoring device 20 includes a processor 21 such as a CPU (Central Processing Unit), a RAM (Random Access Memory) 22 that functions as the main memory of the processor 21, and a non-volatile storage device 23 that stores a combustion monitoring program executed by the processor. The storage device 23 also stores a frame voltage value group, most recent statistical data L to L4, and reference statistical data R1 to R4, which will be described later. The flame monitoring device 20 further includes a display 24 that displays various screens, which will be described later, an operation device 25 operated by a user, and a communication module 26 that allows the processor 21 to communicate with the combustion control device 70.

[0049] In this embodiment, the processor 21 executes a combustion monitoring program stored in the storage device 23 to operate as an acquisition unit 21A, an analysis unit 21B, and a comparison unit 21C shown in FIG.

[0050] Acquirer 21A communicates with combustion control device 70 via communication module 26, acquires voltage values ​​VF1-VF4 output from combustion control device 70 each time a combustion sequence is executed, and stores them in storage device 23. For example, acquirer 21A executes a voltage value storage process each time it acquires a set of voltage values ​​VF1-VF4. An example of the voltage value storage process is shown in FIG. 6. Furthermore, an example of the configuration of a frame voltage value group made up of each set of voltage values ​​VF1-VF4 stored by this voltage value storage process is shown in FIG. 7.

[0051] In the voltage value storage process of FIG. 6, the acquisition unit 21A stores the voltage values ​​VF1 to VF4 in the Nth storage area (initial value is 0) among the storage areas provided in the storage device 23 for storing the voltage values ​​VF1 to VF4 (step S11). After that, the acquisition unit 21A judges whether N is 49 (step S12), and if N is not 49 (Yes), adds 1 to N (step S13). If N is 49 (step S12; No), the acquisition unit 21A initializes N to 0 (step S14). When 50 sets of voltage values ​​VF1 to VF4 of N=0 to 49 are stored in the storage device 23 by such a series of processes, the voltage values ​​VF1 to VF4 obtained thereafter are overwritten starting from N=0. As a result, the latest 50 sets of voltage values ​​VF1 to VF4 are always stored in the storage device 23. The data group of these 50 sets of voltage values ​​VF1 to VF4 is the frame voltage value group. Of the frame voltage value groups, the set of voltage values ​​VF1 for N=0 to 49 is referred to as the first voltage value group, the set of voltage values ​​VF2 for N=0 to 49 is referred to as the second voltage value group, the set of voltage values ​​VF3 for N=0 to 49 is referred to as the third voltage value group, and the set of voltage values ​​VF4 for N=0 to 49 is referred to as the fourth voltage value group.

[0052] The combustion control device 70 may sequentially output the voltage values ​​VF1-VF4 each time it acquires each of the voltage values ​​VF1-VF4. A voltage value storage process as shown in FIG. 6 may be executed for each of the voltage values ​​VF1-VF4. In such a case, N controlled in the voltage value storage process is prepared individually for each of the voltage values ​​VF1-VF4. With this control, the voltage value acquired when the combustion sequence is centered midway is also stored in the storage device 23.

[0053] Returning to FIG. 5, the analysis unit 21B statistically analyzes a set of voltage values ​​VF1 constituting the first voltage value group of the flame voltage value group stored in the storage device 23 in an early period after the manufacture of the combustion device 30, and obtains the statistical data of the set obtained by this analysis as reference statistical data R1. Similarly, the analysis unit 21B statistically analyzes each set of voltage values ​​VF2 to VF4 constituting the second to fourth voltage value groups, respectively, and obtains reference statistical data R2 to R4. In this way, the analysis unit 21B statistically analyzes each set of voltage values ​​VF1 to VF4 for each subsequence such as "pilot ignition", "pilot only", "main ignition", and "main stable", and obtains reference statistical data R1 to R4, which are the statistical data of each set. The reference statistical data R1 to R4 are used as a reference for comparison with the most recent statistical data L1 to L4 described later. The above-mentioned initial period refers to a period when no malfunction occurs in the combustion device 30, and the reference statistical data R1 to R4 are data when no malfunction occurs in the combustion device 30 (that is, data when there is no abnormality before a malfunction occurs).

[0054] After the combustion device 30 is manufactured, the analysis unit 21B starts the reference statistical data generation process shown in Fig. 8 from the initial start of operation to obtain the reference statistical data R1 to R4. The reference statistical data generation process is executed for each subsequence such as "pilot ignition", "pilot only", "main ignition", and "main stable". Below, the reference statistical data generation process for generating the reference statistical data R1 to R4 based on the set of voltage values ​​VF1 for "pilot ignition" will be described. The following description is also applicable to the generation of the reference statistical data R2 to R4.

[0055] 8, analysis unit 21B first monitors each of storage areas N=0 to 49 in storage device 23, and waits until a voltage value VF1 is stored in all of them (step S21). When a voltage value VF1 is stored in each of storage areas N=0 to 49 (step S21; Yes), analysis unit 21B reads out voltage value VF1, that is, a first voltage value group, from each of these storage areas (step S22).

[0056] After that, the analysis unit 21B statistically analyzes the read first voltage value group, that is, a set of 50 voltage values ​​VF1 (step S23), and stores the statistical data of the set of voltage values ​​VF1 obtained by this analysis as reference statistical data R1 in the storage device 23 (step S24). In the statistical analysis in step S24, the number of voltage values ​​VF1 belonging to the same preset class is counted as a frequency, as shown in FIG. 9. The reference statistical data R1 includes distribution data showing the distribution of the number of voltage values ​​VF1 belonging to each class of the voltage value VF1, as shown in FIG. 9. The distribution data is also referred to as reference distribution data below. The class may be the value of the voltage value VF1 itself. For example, when the voltage value VF1 is specified in units of 1 mV and is rounded off to the nearest whole number, each value of 1 mV, 2 mV, 3 mV, etc. that the voltage value VF1 can take may be treated as a class of the voltage value VF1. In this case, to be precise, the range of 0.5 or more and less than 1.5 can be said to be a class, and the above 1, 2, 3, etc. can also be said to be class values. The above classes are set individually for each of the voltage values ​​VF1 to VF4.

[0057] When the reference distribution data shown in Fig. 9 is graphed with the voltage value VF1 classes on the horizontal axis and the number (frequency) of voltage values ​​VF1 on the vertical axis, a graph (frequency line) like that shown in Fig. 10 is obtained. Note that the black circles in the graph in Fig. 10 indicate the class values. As shown in Fig. 10, the graph of the reference distribution data has a Gaussian distribution with a narrow width in the horizontal axis direction, i.e., a small standard deviation. The same applies to the voltage values ​​VF2 to VF4.

[0058] The reference statistical data generation process shown in FIG. 8 may be started before an operational test after the manufacture of the combustion device 30, or may be started after the combustion device 30 goes into full operation after the operational test is completed. The above-mentioned manufacture includes the combustion device 30 being renewed by repairing, servicing, modifying, or replacing the flame detector 45. The reference statistical data generation process may be started at any time when the user wishes to register the reference statistical data. In this case, the user issues an instruction to that effect via the operation device 25. The reference statistical data generation process may be executed when the combustion device 30 is not malfunctioning.

[0059] Returning to FIG. 5, the analysis unit 21B acquires a set of each of the voltage values ​​VF1 to VF4 constituting the frame voltage value group stored in the storage device 23 at any timing after the reference statistical data is obtained. This set is a set of each of the voltage values ​​VF1 to VF4 of the most recently executed 50 times (the most recent 50 times). The analysis unit 21B statistically analyzes each set of the voltage values ​​VF1 to VF4 for each of the voltage values ​​VF1 to VF4, that is, for each of the voltage values ​​VF1 to VF4, namely, for each of the "pilot ignition", "pilot only", "main ignition", and "main stable", and obtains the statistical data of each set obtained by this analysis as the most recent statistical data L1 to L4, respectively, and stores them in the storage device 23. The most recent statistical data L1 to L4 are used for comparison with the reference statistical data R1 to R4. The user considers whether or not a malfunction is occurring in the combustion device 30 based on the result of this comparison. Therefore, when the user wishes to examine whether or not a malfunction has occurred in the combustion device 30, the user inputs an instruction for the above-mentioned comparison into the operation device 25. In response to this input, the analysis unit 21B performs the above-mentioned statistical analysis and obtains the most recent statistical data L1 to L4.

[0060] The analysis unit 21B obtains the most recent statistical data L1-L4 by performing the same analysis method as that used to obtain the reference statistical data R1-R4, for example, by performing the same processing as steps S22-S24 of the reference statistical data generation processing shown in Fig. 7, and stores the most recent statistical data L1-L4 in the storage device 23. The most recent statistical data L1, like the reference statistical data R1, includes distribution data (see also Fig. 8) indicating the distribution of the number of voltage values ​​VF1 belonging to each of the voltage value VF1 classes. Similarly, the most recent statistical data L2-L4, like the reference statistical data R2-R4, each includes distribution data (see also Fig. 8) indicating the distribution of the number of voltage values ​​VF2-VF4 belonging to each of the voltage value VF2-VF4 classes. These distribution data are hereinafter also referred to as most recent distribution data.

[0061] Returning to FIG. 5, when the most recent statistical data is recorded in the storage device 23, the comparison unit 21C reads the most recent statistical data L1 to L4 and the reference statistical data R1 to R4 from the storage device 23, compares them, and outputs the comparison result. The comparison is performed for each of the four subsequences, namely, "pilot ignition", "pilot only", "main ignition", and "main stable". That is, the most recent statistical data L1 is compared with the reference statistical data R1. Similarly, the most recent statistical data L2 to L4 are compared with the reference statistical data R2 to R4, respectively.

[0062] As shown in FIG. 11, the comparison unit 21C compares the most recent statistical data L1-L4 with the reference statistical data R1-R4 for each of the four subsequences by graphing the most recent distribution data L1-L4 and the reference distribution data R1-R4 in association with each other, with the horizontal axis being the amplitude class (class value) and the vertical axis being the frequency. Here, the most recent distribution data and the reference distribution data are graphed in a superimposed manner for each subsequence on a common coordinate plane, so that the two are graphed in association with each other. The comparison unit 21C outputs images of the graphed most recent distribution data and the reference distribution data (images like those in FIG. 11) to the display 24 as the comparison results of the comparison of the most recent statistical data L1-L4 with the reference statistical data R1-R4, respectively, and displays the graphs on the display 24. As shown in FIG. 11, the graphs are displayed side by side.

[0063] When there is no malfunction in the combustion device 30 (before the malfunction occurs), the graph of the most recent distribution data and the graph of the reference distribution data almost overlap, as in the graphs of "pilot ignition," "main ignition," and "main stable" in Fig. 11. On the other hand, when there is a malfunction in the combustion device 30, the two graphs are shifted from each other, as in the graph of "pilot only" in Fig. 11.

[0064] By checking the comparison results displayed on the display 24, that is, the graphs of the four subsequences, the user can grasp that a malfunction has occurred in the combustion device 30 and the type of the malfunction.

[0065] For example, in all four graphs, that is, all four subsequences, if the graph of the most recent distribution data is moving in the direction of lower voltage values ​​VF1 to VF4 than the graph of the reference distribution data, the flame voltage is generally lowered. In such a case, the user can understand that at least one of the following may be occurring: (1) the window 45B of the flame detector 45 is dirty with soot or the like, and (2) the air-fuel ratio is disturbed. The air-fuel ratio is the ratio of fuel gas and air supplied to the main burner 42 and the pilot burner 43. If this ratio is disturbed from the ratio in the ideal range before the malfunction, the flame voltage VF is generally lowered. The disturbance of the air-fuel ratio is caused by clogging of the blower 62, etc. If the window 45B is dirty, the amount of electromagnetic waves entering the flame detector 45 from the flame is reduced, which also causes the flame voltage VF to be lowered. It can be understood that at least one of the following malfunctions is occurring: the electromagnetic waves from the flame are also disturbed. In such a case, the user can perform maintenance on the window 45B and the blower 62, for example, to resolve the malfunction.

[0066] For example, in all four graphs, i.e., all four subsequences, if the graphs of the most recent distribution data are shifted in the direction of higher voltage values ​​VF1 to VF4 than the graphs of the reference distribution data, the flame voltage VF is generally high. In such a case, it is suspected that a malfunction of false discharge has occurred in the flame detector 45. A false discharge is a phenomenon in which a discharge occurs between electrodes even though no electromagnetic waves are incident from the flame, or a discharge occurs in an amount greater than the incident ultraviolet light. In such a case, the user can know that the flame detector 45 may be malfunctioning.

[0067] For example, if there is a difference between the most recent distribution data and the reference distribution data in some of the four graphs, that is, the four subsequences, the user can understand that the type of malfunction occurring in the combustion device 30 may be that the equipment used to execute the above-mentioned subsequence among the equipment constituting the combustion device 30 is malfunctioning. For example, if the graph of the most recent distribution data moves to a lower voltage value VF3 than the graph of the reference distribution data with only the pilot, the flame activity is weakened, and therefore disturbance in the air-fuel ratio of the fuel gas and air supplied to the pilot burner 43 is suspected. In this case, air leakage in the second flow path 61C of the air flow path 61 connected to the pilot burner 43, air leakage in the second flow path 51C of the fuel flow path 51 connected to the main burner 42, etc. are suspected.

[0068] As described above, by comparing the graph of the latest distribution data with the graph of the reference distribution data for each subsequence, if the two graphs are different for at least one subsequence, the user can know that the combustion device 30 is malfunctioning. In addition, the type of malfunction can be known from information on which subsequence the difference is occurring in. In this embodiment, the analysis unit 21B obtains the latest distribution data and the reference distribution data by statistically analyzing each set of the voltage values ​​VF1 to VF4 of the flame voltage VF, that is, each set of the flame activity, and the tendency of the change in the flame activity, that is, the tendency of the malfunction of the combustion device, is likely to be reflected in the comparison result between the latest distribution data and the reference distribution data. Therefore, by checking the comparison result for each subsequence, the user can quickly know the tendency of the malfunction of the combustion device, in other words, that the malfunction is starting to occur in the combustion device 30 (such as the tendency of the malfunction to occur). Furthermore, even if any of the voltage values ​​VF1 to VF4 changes significantly due to an unexpected event not resulting from a malfunction of the combustion device 30, the effect of this change is mitigated by statistical analysis, so the user can know with high accuracy whether or not there is a malfunction in the combustion device 30. As described above, according to this embodiment, the user can properly understand the malfunction of the combustion device 30 by looking at the comparison results, that is, the graphs of the most recent distribution data and the reference distribution data.

[0069] Recovery from an abnormality such as misfire or flame failure of the combustion device 30 takes time due to the complexity of the devices around the main burner 42. In this embodiment, the user can grasp malfunctions of the combustion device 30 that are a sign of an abnormality in the combustion device 30, making it possible to deal with the abnormality before it occurs.

[0070] Furthermore, in the above embodiment, by displaying graphs of the most recent distribution data and the reference distribution data as the comparison results, the user can easily grasp the difference between the most recent distribution data and the reference distribution data and can infer the type of malfunction from this difference. This improves the efficiency of maintenance of the combustion device 30 and makes it easier to identify the location of the malfunction if an abnormality occurs in the combustion device 30.

[0071] The reference statistical data to be compared with the most recent statistical data may be, for example, data prepared as a set of statistical data of flame activity when the combustion sequence is executed multiple times and serves as a reference. For this reason, the reference statistical data may be data obtained in advance from the results of an experiment using a combustion device of the same type as the combustion device 30, but in this embodiment, the reference statistical data R1 to R4 are prepared based on the voltage values ​​VF1 to VF4 measured in an ignition trial actually executed in the combustion device 30. This allows the reference statistical data R1 to R4 to be obtained that reflect the individual characteristics of the combustion devices 30 that are produced in multiple numbers, allowing the user to more appropriately understand malfunctions of the combustion device 30.

[0072] (Modification) The configuration of the above embodiment can be modified as desired. Modifications are shown below as examples. Each modification can be combined with at least a portion of the others.

[0073] (Variation 1) The configuration of the combustion device 30 is arbitrary. For example, the combustion device 30 may be a type having only the main burner 42 without the pilot burner 43. Also, the combustion device 30 may be in a state in which the pilot burner 43 is constantly ignited. In this case, it is preferable to prepare a flame detector for the main burner 42 and a flame detector for the pilot burner 43. The ignition delay time Td may be, for example, a period from an ignition instruction that outputs a signal instructing the ignition or ignition of the pilot burner 43 or the main burner 42 to an ignition detection that detects the ignition of the main burner 42.

[0074] (Variation 2) The comparison unit 21C may graph the most recent distribution data of the most recent statistical data and the reference distribution data of the reference statistical data in association with each other, with the vertical axis representing the class of each of the voltage values ​​VF1 to VF4 and the horizontal axis representing the number of the voltage values ​​VF1 to VF4. The method of graphing the most recent distribution data and the reference distribution data of the reference statistical data in association with each other is not limited to the above-mentioned method of superimposing the graphs on a coordinate plane with a common vertical axis and horizontal axis. For example, each graph may be represented on a different coordinate plane with a common scale of the coordinate axis. In this manner, the method of graphing the most recent distribution data and the reference distribution data may be any method that allows a user to compare the distribution data. By graphing the data in association with each other, the user can grasp the malfunction of the combustion device 30. Among the set of amplitudes S to be subjected to the statistical analysis, the amplitudes S having suddenly abnormal values ​​may be excluded from the analysis target. The comparison unit 21C may output an image in which the most recent distribution data and the reference distribution data are written side by side as the sign information. The user can grasp the sign of a malfunction of the flame detector 45 even from such values.

[0075] (Variation 3) As shown in FIG. 12, the comparison unit 21C may generate a radar chart showing the difference between the most recent statistical data and the reference statistical data, with each of the subsequences as an item, and use the generated radar chart as the comparison result. For example, the most recent statistical data L1 and the reference statistical data R1 include at least one of statistics such as an average value of the voltage value VF1 and a mode or median in the distribution of the number of voltage values ​​VF1 belonging to each class of the voltage value VF1. The comparison unit 21C calculates the difference between the most recent statistical data L1 and the reference statistical data R1, that is, the difference between the average value, the mode, or the median. For the other subsequences, the comparison unit 21C calculates the difference between the most recent statistical data L2 to L4 and the reference statistical data R2 to R4, respectively, as the difference. The comparison unit 21C generates a radar chart showing the calculated difference and displays it on the display 24. In the example of FIG. 12, when the difference is 0, it is set to "5", and when the statistical value of the most recent statistical data is larger, it is set to "6" to "10" depending on the degree of the difference. When the statistical value of the reference statistical data is larger, it is set to "5" to "0" depending on the degree of the difference. Therefore, the radar chart when the combustion device 30 is not malfunctioning is the dotted line chart in FIG. 12. The bold line radar chart in FIG. 12 shows that in each of the four subsequences, the voltage values ​​VF1 to VF4, that is, the flame activity in each subsequence, tends to be large. With such a radar chart, the user can easily understand whether or not the combustion device 30 is malfunctioning and the type of malfunction.

[0076] (Variation 4) The analysis unit 21B may generate the latest most recent statistical data L1-L4, for example, every time new voltage values ​​VF1-VF4 are stored in the storage device 23. Then, as shown in Fig. 13, the comparison unit 21C may estimate the presence or absence of a malfunction in the combustion device 30 and, if a malfunction occurs, the type of the malfunction, based on the differences between the reference statistical data R1-R4 and the most recent statistical data L1-L4, (step S31), and if a malfunction occurs (step S32; Yes), output the result of the estimation as a comparison result (step S33).

[0077] As explained above, if all of the differences between the most recent statistical data L1 to L4 of each of the multiple subsequences and the reference statistical data R1 to R4 show a tendency for the former to have a lower flame activity (voltage values ​​VF1 to VF4) than the latter, the type of malfunction occurring in the combustion device 30 may be at least one of the following: dirt on the window 45B that takes in the electromagnetic waves of the flame detector 45 that detects the flame activity using electromagnetic waves from the flame, and a disturbance in the air-fuel ratio of the fuel and air supplied to the main burner 42 and the pilot burner 43, as mentioned above. When the average value of the voltage values ​​VF1 to VF4, the mode in the distribution of the number of voltage values ​​VF1 belonging to each class of the voltage value VF1, or the median in the distribution is smaller than the former (including the case where the difference is equal to or greater than a predetermined threshold), the comparison unit 21C assumes that the former tends to have a lower flame activity than the latter, and estimates that at least one of the dirt on the window 45B and the disturbance in the air-fuel ratio is the type of malfunction. In this case, the comparison unit 21C displays information that at least one type of malfunction, that is, the dirt on the window 45B and the disturbance in the air-fuel ratio, has occurred on the display 24. Examples of such information include messages such as "The window of the flame detector is dirty," "The air-fuel ratio is disturbed," or "There is a possibility that the window of the flame detector is dirty, the air-fuel ratio is disturbed, or both of these malfunctions have occurred."

[0078] When all the differences between the most recent statistical data L1-L4 of each of the subsequences and the reference statistical data R1-R4 show a tendency that the flame activity (voltage values ​​VF1-VF4) of the former is greater than that of the latter, the type of malfunction occurring in the combustion device 30 may be the occurrence of a false discharge in the flame detector 45, as described above. When the former is greater in any of the average, mode, and median (including the case where the difference is equal to or greater than a predetermined threshold), the comparison unit 21C estimates the occurrence of a false discharge as the type of malfunction. In this case, the comparison unit 21C displays information that a false discharge is occurring in the flame detector 45 on the display 24. Such information may be, for example, a message such as "There is a possibility that a false discharge is occurring in the flame detector."

[0079] When there is a difference between the most recent statistical data and the reference statistical data in only some of the subsequences, the comparison unit 21C estimates that the malfunction of the combustion device 30 is caused by the malfunction of the equipment used to execute the subsequence, and displays a message to that effect on the display 24. For example, when the most recent statistical data L2 shows a tendency for the flame activity (voltage value VF2) to be smaller than that of the reference statistical data R2 only in the pilot only mode, for example, when the former is smaller in the average value, mode value, or median value (including the case where the difference is equal to or greater than a predetermined threshold value), a disturbance in the air-fuel ratio of the fuel gas and air supplied to the pilot burner 43 is suspected. In this case, air leakage in the second flow path 61C of the air flow path 61 connected to the pilot burner 43, air leakage in the second flow path 51C of the fuel flow path 51 connected to the main burner 42, etc. are suspected. The comparison unit 21C outputs a message to that effect. Such messages may include "The air-fuel ratio of the pilot burner 43 is disturbed. Check the fuel or air flow path."

[0080] According to this modification, the user is notified of the presence or absence of a malfunction of the combustion device 30 and, if a malfunction occurs, the type of malfunction. Therefore, the user can more appropriately grasp the malfunction of the combustion device 30.

[0081] (Variation 5) The analysis unit 21B may be configured to statistically analyze a set of flame activity (voltage values ​​VF1 to VF4 in the above) of the burners (both or at least one of the main burner and the pilot burner, etc.) detected in each of a plurality of combustion sequences for each subsequence, and obtain the statistical data of the set as first statistical data (most recent statistical data L1 to L4 in the above), and the analysis method may be arbitrary. Furthermore, the comparison unit 21C may be configured to compare, for each subsequence, the first statistical data with second statistical data that is a reference prepared as statistical data of the set of flame activity when the combustion sequence is executed a plurality of times, and output each comparison result. The comparison method and comparison result may be arbitrary. According to these configurations, the user can grasp the tendency of change in flame activity, that is, the tendency of malfunction of the combustion device 30 (such as a tendency that malfunction is occurring), by statistical analysis, and can quickly grasp the malfunction of the combustion device 30. Furthermore, it is also possible to reduce the impact of the occurrence of a sudden event that significantly changes the flame activity and is not caused by a malfunction of the combustion device 30. Therefore, the user can know with a high degree of accuracy whether or not a malfunction has occurred in the combustion device 30, and thus can appropriately understand the malfunction of the combustion device 30.

[0082] (Variation 6) The flame activity may be indicated by the number of discharges per unit time that occur between the electrodes of the discharge tube 45A of the flame detector 45. When the flame activity is high, for example when the ultraviolet light intensity is high, the number of discharges per unit time increases. In other words, an increase in the number of discharges corresponds to an increase in the voltage value of the flame voltage described above. Note that the number of discharges also increases in the case of false discharges. In such a case, it is advisable to provide the combustion device 70 with a counter that counts the number of discharges and a measuring unit that measures the counting period.

[0083] (Variation 7) The hardware configuration of the flame monitoring device 20 is arbitrary. The acquisition unit 21A, the analysis unit 21B, and the comparison unit 21C may each be composed of one or more computers or control circuits (such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array)). At least a part of each of the units 21A to 21C may be provided in the combustion control device 70. The flame monitoring device 20 may be a server computer, a cloud computer, or the like. The output destination of the comparison result may be a display of a user terminal or the like. The output destination of the comparison result may be a printer, a storage medium, a network, another computer, or the like. Each device such as the flame monitoring device 20 includes a device in which the components of the device are integrated into one housing, as well as a system in which the components of the device are distributed and accommodated in multiple housings.

[0084] (Variation 8) The flame detector 45 may take in electromagnetic waves from the flame through a window provided in the combustion furnace 41. In this case, if this window provided in the combustion furnace 41 becomes dirty with soot or the like, it will cause the combustion device 30 to malfunction. In other words, the dirt on the window 45B of the flame detector 45 will replace the dirt on the window of the combustion furnace 41. The flame detector 45 may be fitted into the through hole of the combustion furnace 41 from the outside, and in this case, the window of the combustion furnace 41 may consist of the window 45B of the flame detector 45.

[0085] (Flame monitoring method) The flame monitoring method includes a statistical analysis and a comparison between the most recent statistical data and the reference statistical data, and at least a part of the method may be performed by an object or person other than the flame monitoring device 20. By checking the comparison result obtained by comparing the most recent statistical data with the reference statistical data, the user can properly grasp the malfunction of the combustion device 30, as described above.

[0086] (Scope of the present invention) Although the present invention has been described above with reference to the embodiments and modifications, the present invention is not limited to the above embodiments and modifications. For example, the present invention includes various modifications to the above embodiments and modifications that can be understood by a person skilled in the art within the scope of the technical concept of the present invention. The configurations listed in the above embodiments and modifications can be appropriately combined within a range without contradiction. [Explanation of symbols]

[0087] 10...combustion system, 20...flame monitoring device, 21...processor, 21A...acquisition section, 21B...analysis section, 21C...comparison section, 23...memory device, 25...operation device, 40...combustion equipment, 42...main burner, 43...pilot burner, 44...ignition device, 44A...spark generating section, 45...flame detector, window...45B, 50...fuel supply system, 60...air supply system, 70...combustion control device.

Claims

1. An acquisition unit configured to acquire flame activity of a burner in each of a plurality of subsequences constituting a combustion sequence of a combustion device that ignites a burner and burns fuel; an analysis unit configured to statistically analyze a set of flame activity of the combustion sequences acquired by the acquisition unit for each of the subsequences, and obtain statistical data of the set as first statistical data; a comparison unit configured to compare, for each of the subsequences, the first statistical data with second statistical data that is prepared as a reference statistical data of a set of flame activity when the combustion sequence is executed a plurality of times, and to output each comparison result; A flame monitoring device comprising:

2. The analysis unit is configured to statistically analyze, for each of the subsequences, a set of flame activity for each of the combustion sequences, which are the same number of times as the plurality of combustion sequences executed before a malfunction occurred in the combustion device and before the plurality of combustion sequences, acquired by the acquisition unit, in the same manner as in acquiring the first statistical data, and acquire the statistical data of the set as the second statistical data.

2. The flame monitor of claim 1.

3. The first statistical data includes first distribution data indicating a distribution of the number of flame activity levels belonging to each flame activity level class, The second statistical data includes second distribution data indicating a distribution of the number of flame activity levels belonging to each flame activity level class.

3. A flame monitor according to claim 1 or 2.

4. The comparison unit is A first axis represents the class of flame activity and a second axis represents the number of flame activity levels, and the first distribution data and the second distribution data are correlated with each other to create a graph, thereby comparing the first statistical data and the second statistical data; and outputting, as the comparison result, each graph of the first distribution data and the second distribution data graphed in association with each other.

4. The flame monitor of claim 3.

5. the comparison unit is configured to generate a radar chart representing a difference between the first statistical data and the second statistical data, with each of the plurality of subsequences as an item, and output the generated radar chart as the comparison result. A flame monitor according to any one of claims 1 to 4.

6. The comparison unit is configured to estimate the presence or absence of a malfunction of the combustion device and, if a malfunction occurs, a type of the malfunction based on a difference between the first statistical data and the second statistical data of each of the plurality of subsequences, and to output a result of the estimation as the comparison result. A flame monitor according to any one of claims 1 to 5.

7. When all of the differences between the first statistical data and the second statistical data for each of the plurality of subsequences indicate a tendency for the first statistical data to have a lower flame activity than the second statistical data, the comparison unit estimates that the type of malfunction is at least one of dirt on a window that transmits the electromagnetic waves incident on a flame detector that detects the flame activity of the combustion device by electromagnetic waves from the flame, and a disturbance in the air-fuel ratio of the fuel and air supplied to the burner.

7. The flame monitor of claim 6.

8. When there is a difference between the first statistical data and the second statistical data in only a portion of the subsequences among the plurality of subsequences, the comparison unit estimates, as the type of malfunction, that a device used to execute the portion of the subsequences among devices constituting the combustion device is malfunctioning. A flame monitor according to claim 6 or 7.

9. On the computer, An acquisition step of acquiring flame activity of a burner in each of a plurality of subsequences constituting a combustion sequence of a combustion device that ignites a burner and burns fuel; an analysis step of statistically analyzing a set of the flame activity of the combustion sequences for each of the subsequences acquired in the acquisition step, and acquiring statistical data of the set as first statistical data; a comparison step of comparing, for each of the subsequences, the first statistical data with second statistical data that is prepared as a reference statistical data of a set of flame activity when the combustion sequence is executed a plurality of times, and outputting each comparison result; A flame monitoring program that executes the

10. an analysis step of statistically analyzing a set of flame activity of a plurality of subsequences constituting a combustion sequence of a combustion device that ignites a burner and combusts fuel, and obtaining statistical data of the set as first statistical data; a comparison step of comparing, for each of the subsequences, the first statistical data with second statistical data that serves as a reference and is prepared as statistical data of a set of flame activity when the combustion sequence is executed a plurality of times; A flame monitoring method comprising:

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