JP7419702B2 - boiler system - Google Patents

Description

The present invention relates to a boiler system.

Conventionally, a heat medium such as thermal oil is heated by combustion in a boiler, and the heated heat medium is circulated between the heat-using parts as load equipment using a circulation pump, thereby supplying heat to the heat-using parts. Boiler systems are known (for example, see Patent Document 1).
Further, it is known that a boiler system is provided with a misfire determination section that determines whether a burner of the boiler has misfired and prevents fuel from accumulating within the boiler body (for example, see Patent Document 2).

JP2017-207258A Japanese Patent Application Publication No. 2016-114311

Patent Document 2 describes a method for detecting burner misfires based on the temperature difference between the temperature of hot water in the upstream part of a heat exchanger provided outside the boiler body and the temperature of hot water in the downstream part of the heat exchanger. A technique for determining is disclosed.
However, if the time required for the heat medium to flow through the flow path in the boiler is not taken into consideration, for example, when there is a temperature fluctuation in the temperature at which the heat medium flows into the boiler, the temperature difference that accurately reflects the combustion state of the burner cannot be calculated. Information is difficult to obtain. In particular, in a heat medium boiler that uses combustion gas generated by a burner to heat the heat medium flowing inside a monotube heat exchanger, it takes a long time for the heat medium to flow from the upstream part to the downstream part. If the time required for the medium to flow through the flow path in the boiler is not taken into account, there will be a large discrepancy in the correspondence between the inflow temperature and outflow temperature of the heat medium into the boiler.

The present invention has been made in view of the above-mentioned problems, and its purpose is to correctly evaluate the correspondence between the inflow temperature and outflow temperature to the boiler, and to adjust the temperature of the fluid to be heated as a heat medium to the inflow temperature to the boiler. An object of the present invention is to provide a boiler that can accurately determine burner misfire even when there are fluctuations.

The present invention includes a burner, a monotube heat exchanger that exchanges heat between a combustion gas generated by the burner and a fluid to be heated, and a primary side temperature of the fluid to be heated on an inlet side of the heat exchanger. comprising a primary side temperature detection section, a secondary side temperature detection section that detects the secondary side temperature of the heated fluid on the outlet side of the heat exchanger, and a control section having a storage section and a misfire determination section, The storage unit stores an arrival reference time corresponding to the time required for the heated fluid to flow from the arrangement position of the primary side temperature detection unit to the arrangement position of the secondary side temperature detection unit, and calculates, as temperature difference information, a difference between information based on the secondary side temperature at a predetermined timing and information based on the primary side temperature at a timing that is earlier than the predetermined timing and the arrival reference time; The present invention relates to a boiler system that determines whether or not the burner has misfired based on temperature difference information.

Further, the control unit of the present invention includes a primary side average temperature calculation unit that calculates an average value of the primary side temperature in a first predetermined time period as a primary side average temperature, and an average value of the secondary side temperature in a second predetermined time period. a secondary side average temperature calculation unit that calculates a value as a secondary side average temperature, and the misfire determination unit is configured to calculate the secondary side average temperature at a predetermined timing and the arrival reference time than the predetermined timing. It is preferable to calculate the difference between the primary side average temperature and the primary side average temperature at a retroactive timing as the temperature difference information, and to determine whether or not the burner has misfired based on the temperature difference information.

Further, in the boiler system of the present invention, it is preferable that the first predetermined time and the second predetermined time are shorter than the arrival reference time.

Further, the control unit of the present invention includes an arrival reference time setting unit that sets the arrival reference time, and the arrival reference time setting unit is configured to set the arrival reference time based on heated fluid information that is information about the heated fluid. It is preferable to set a reference time.

Further, it is preferable that the misfire determination unit of the present invention determines that the burner has misfired when the temperature difference information is less than a predetermined threshold value.

Further, it is preferable that the misfire determination unit of the present invention determines that the burner has misfired when the temperature difference information remains below a predetermined threshold for a third predetermined period of time.

Further, in the boiler system of the present invention, it is preferable that the third predetermined time is longer than the arrival reference time.

Further, the boiler system of the present invention further includes a flame detection means for detecting a flame of the burner, and the misfire determination section is configured to detect the temperature difference information even when the flame detection means detects the flame. It is preferable to determine that the burner has misfired when the value is below a predetermined threshold.

Further, the boiler system of the present invention further includes an exhaust gas outlet temperature detection unit that detects an exhaust gas outlet temperature, and the misfire determination unit is configured to detect that the temperature difference information is below a predetermined threshold value, and the exhaust gas outlet temperature is It is preferable to determine that the burner has misfired when the temperature is equal to or lower than the sum of the next-side average temperature and a predetermined temperature.

Moreover, it is preferable that the misfire determination unit of the boiler system of the present invention starts the process of determining whether or not the burner has misfired after a fourth predetermined time period has elapsed since the start of operation of the boiler.

According to the present invention, the correspondence between the inflow temperature and the outflow temperature into the boiler is correctly evaluated, and burner misfires can be accurately detected even when there are temperature fluctuations in the inflow temperature of the heated fluid as a heat medium into the boiler. A boiler that can be well determined can be provided.

1 is a schematic diagram showing a boiler system according to an embodiment of the present invention. FIG. 3 is a functional block diagram showing a control unit of the embodiment. It is a graph showing a temporal change in the primary side temperature T1 of the heating medium oil and the secondary side temperature T2 of the heating medium oil. It is a graph showing a temporal change in the primary side temperature T1 of the heating medium oil and the secondary side temperature T2 of the heating medium oil. It is a functional block diagram showing a control section in a first modification of the present embodiment. It is a functional block diagram showing a control section in a second modification of the present embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing a boiler system 1 of this embodiment.
As shown in FIG. 1, the boiler system 1 includes a heat medium boiler 2, a heat medium circulation line 3, a fuel supply line 4, an exhaust gas line 5, and a control section 7. The heat medium boiler 2 of this embodiment is a boiler that can supply heat at a higher temperature than steam (for example, 180 degrees to 300 degrees) by using heat medium oil as a heated fluid (heat medium). It is.

The heat medium boiler 2 includes a can body 20, a burner 21, a blower 22 that supplies combustion air to the burner 21, and a heat medium oil heating pipe 23 arranged inside the can body 20 and through which heat medium oil flows. , is provided. The heat medium boiler 2 heats the heat medium oil flowing through the heat medium oil heating pipe 23 by burning fuel with the burner 21 and heating the inside of the can body 20 . Here, the heat medium oil heating tube 23 constitutes a monotube heat exchanger that exchanges heat between the combustion gas generated by the burner and the heat medium oil.
Incidentally, the can body 20 is provided with a flame sensor 24 as a flame detection means for detecting flame when the burner 21 is burning.

The heat medium boiler 2 in this embodiment is a three-position combustion control boiler that can switch the combustion amount to three positions: high combustion, low combustion where combustion is performed with a smaller combustion amount than high combustion, and combustion stop. Here, high combustion is a state in which combustion is performed at a combustion amount such that the thermal output of the heat medium boiler 2 is 100% of the rated output, and low combustion is a state in which the thermal output of the heat medium boiler 2 is 20% of the rated output, for example. % to 50% combustion. In this embodiment, low combustion is defined as a state in which combustion is performed with a combustion amount that is 50% of the rated output.

The fuel supply line 4 is connected to the burner 21 of the heat medium boiler 2 . Fuel is supplied from this fuel supply line 4 to the burner 21 via a fuel adjustment valve 41. In this embodiment, oil is used as the fuel.

The exhaust gas line 5 is connected to the can 20 of the heat medium boiler 2 . Exhaust gas from the heat medium boiler 2 is discharged to the outside of the can body 20 via this exhaust gas line 5.
Note that an exhaust gas outlet temperature detection section 51 is disposed in the exhaust gas line 5 near the outlet of the heat medium boiler 2 to detect the exhaust gas outlet temperature near the outlet of the heat medium boiler 2.

The burner 21 , the blower 22 , the flame sensor 24 , the fuel adjustment valve 41 , and the exhaust gas outlet temperature detection section 51 are electrically connected to the control section 7 via the signal line 9 .

The heat medium circulation line 3 connects the heat medium boiler 2 (heat medium oil heating pipe 23) and the heat use section 200, and supplies the heat medium oil heated by the heat medium boiler 2 to the heat use section 200. A heating medium oil return connecting the supply line 32, the heat using section 200, and the heating medium boiler 2 (thermal oil heating tube 23) to return the heating medium oil whose heat has been used in the heat using section 200 to the heating medium boiler 2. A line 31 is provided.

A primary side temperature detection section 33 is arranged near the inlet of the heat medium boiler 2 (thermal oil heating tube 23) of the heat medium oil return line 31. The primary side temperature detection unit 33 detects the heat medium oil temperature at this position, that is, the temperature on the inlet side of the heat medium oil heating pipe 23 of the heat medium oil circulating in the heat medium circulation line 3, as the primary side temperature T1 of the heat medium oil. Detect.
A secondary side temperature detection section 34 is arranged near the outlet of the heat medium boiler 2 (thermal oil heating tube 23) of the heat medium oil supply line 32. The secondary side temperature detection unit 34 detects the heat medium oil temperature at this position, that is, the temperature at the outlet side of the heat medium oil heating pipe 23 of the heat medium oil circulating in the heat medium circulation line 3 on the secondary side of the heat medium oil. Detect temperature T2.

Further, a circulation pump 35 is arranged in the heat medium oil supply line 32 . In addition, in this embodiment, the circulation pump 35 is installed in the heating medium oil supply line 32 which is the outlet side of the heating medium boiler 2, but it may be installed in the heating medium oil return line 31.
Further, a flow rate detection section 36 is arranged in the heat transfer oil return line 31 . In addition, in this embodiment, the flow rate detection part 36 is installed in the heating medium oil return line 31 which becomes the inlet side of the heating medium boiler 2, but it may be installed in the heating medium oil supply line 32.

The primary temperature detection section 33 , the secondary temperature detection section 34 , the circulation pump 35 , and the flow rate detection section 36 are electrically connected to the control section 7 via the signal line 9 .

By operating the circulation pump 35, the heat medium oil heated within the heat medium oil heating pipe 23 is sent to the heat use section 200 via the heat medium oil supply line 32. The heat medium oil from which heat has been removed in the heat use section 200 is returned to the heat medium boiler 2 via the heat medium oil return line 31. In this manner, by operating the circulation pump 35, the heat medium oil whose temperature has been lowered due to heat removal in the heat use section 200 is configured to be circulated to the heat medium boiler 2 through the heat medium circulation line 3.

The control unit 7 starts combustion in the heat medium boiler 2 in response to turning on a heat medium boiler operation switch (not shown). Further, the control unit 7 stops combustion in the heat medium boiler 2 in response to the heat medium boiler operation switch being turned off.
The control unit 7 starts operating the circulation pump 35 provided in the heat medium circulation line 3 in response to turning on a circulation pump start switch (not shown). Further, the control unit 7 can stop the operation of the circulation pump 35 in response to turning on a circulation pump forced stop switch (not shown).

Next, the control section 7 will be explained in detail with reference to FIG. 2. FIG. 2 is a functional block diagram showing the configuration of the control section 7. As shown in FIG. The control section 7 includes a combustion control section 71 , a misfire determination section 75 , and a storage section 79 .

The combustion control unit 71 controls the combustion state of the heat medium boiler 2 based on the deviation between the preset target temperature and the secondary temperature T2 of the heat medium oil measured by the secondary temperature detection unit 34. . As described above, the heat medium boiler 2 is a three-position combustion control boiler that can switch the combustion amount to three positions: high combustion, low combustion where combustion is performed with a smaller amount than high combustion, and combustion stop.
Therefore, specifically, the combustion control unit 71 determines combustion to be high combustion, low combustion, or combustion stop based on the deviation between the preset target temperature and the secondary temperature T2 of the heat transfer oil. Based on this determination, the combustion control valve 41 has a function of switching the fuel adjustment valve 41 to a high combustion, low combustion, or combustion stop position, and also causes the blower 22 to supply combustion air necessary for the combustion state.

Although the combustion control method of the heat medium boiler 2 is a three-position combustion control method, it is not limited to this. For example, a two-position combustion control method (switching combustion on and off) or an n-position combustion control method (n≧4) in which an intermediate combustion position is provided between a high combustion position and a low combustion position may be applied. Further, a proportional combustion control method that can continuously increase or decrease the combustion amount may be applied.

The storage unit 79 stores an arrival reference time ts corresponding to the time required for the heat transfer oil to flow from the arrangement position of the primary side temperature detection unit 33 to the arrangement position of the secondary side temperature detection unit 34. It also stores information such as a first predetermined time to a fourth predetermined time, which will be described later, and a temperature difference threshold for determining whether or not the burner 21 has misfired.

For example, the control unit 7 calculates the arrival reference time ts based on the flow rate information of the heat medium oil as information on the fluid to be heated, which is actually measured by the flow rate detection unit 36, and stores this in the storage unit 79. Good too. In this case, the arrival reference time ts may be calculated based on the actually measured flow rate information and information such as the flow path length of the heat medium oil heating tube 23. Alternatively, a standard arrival reference time ts based on the model of the heat medium boiler 2, line information of the heat medium oil heating pipe 23, etc. may be stored in the storage unit 79 in advance.

Further, the configuration may be such that the arrival reference time ts can be input through an input unit (not shown), and the input arrival reference time ts may be stored in the storage unit 79 for use in subsequent misfire determination processing.
Further, the configuration is such that information such as the model of the heat medium boiler 2 can be input through an input unit (not shown), and based on the input information, an appropriate arrival reference time ts is read out from the storage unit 79, and this is used for subsequent operations. It may also be used for misfire determination processing.

Examples of the storage unit 79 include random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate (DDR) memory chip, flash memory, and volatile memory. , non-volatile memory, cache memory, buffers, short-term storage memory units, long-term storage memory units, or other suitable memory or storage units.

The misfire determination unit 75 includes information based on the secondary side temperature T2 of the heating medium oil at a predetermined timing, and information based on the primary side temperature T1 of the heating medium oil at a timing later than the predetermined timing by the arrival reference time ts. A misfire of the burner 21 is determined based on this temperature difference information.
Normally, when the heat medium boiler 2 is burning, the temperature of the heat medium oil passing through the heat medium oil heating pipe 23 increases, so the secondary side temperature T2 of the heat medium oil is It becomes higher than the primary side temperature T1. On the other hand, when the heating medium boiler 2 is in a combustion stopped state, although there is an influence of residual heat of the can body 20, etc., the secondary side temperature T2 of the heating medium oil does not become as high as during combustion.
Therefore, when the above-mentioned temperature difference information is less than a predetermined threshold value, it is determined that the burner 21 has misfired.

This point will be explained in detail using FIGS. 3 and 4.
3 and 4 are graphs showing temporal changes in the primary side temperature T1 of the heat transfer oil and the secondary side temperature T2 of the heat transfer oil under predetermined conditions. The vertical axis of the graph is the heat medium temperature T, and the horizontal axis is the time t.

FIG. 3 shows an example of a case where the primary side temperature T1 of the heat transfer oil increases with the passage of time. Such a situation occurs when the amount of heat added to the heat medium oil by the heat medium boiler 2 exceeds the amount of heat consumed by the heat use section 200. In the case of FIG. 3, as the primary temperature T1 of the thermal oil increases, the secondary temperature T2 of the thermal oil also increases.

Here, a method for determining misfire of the burner 21 at timing ta will be described. The secondary side temperature of the heat medium oil at timing ta is temperature T2a, and the primary side temperature of the heat medium oil is temperature T1a. At this time, if the temperature difference (T2a - T1a) between the temperature T2a and the temperature T1a at the timing ta is simply compared with the threshold value ΔTs for determining a misfire of the burner 21, as shown in FIG. If the difference (T2a-T1a) is smaller than the threshold value ΔTs, it is determined that a misfire has occurred.

However, in a situation where the primary side temperature T1 of the heat medium oil flowing into the heat medium boiler 2 changes with time t, the temperature difference (T2a - T1a) between the temperature T2a and the temperature T1a at the timing ta is simply used. If you make a judgment based on this, there is a possibility that the judgment will be incorrect.

Therefore, the misfire determination unit 75 calculates the difference between the secondary side temperature T2a of the heating medium oil at the timing ta and the primary side temperature T1b of the heating medium oil at the timing tb which is earlier than the timing ta by the arrival reference time ts. The temperature difference ΔT is calculated as ΔT (=T2a−T1b), and burner misfire is determined based on this temperature difference ΔT. More specifically, when the temperature difference ΔT is less than the threshold value ΔTs, it is determined that the burner 21 has misfired.

Thereby, the temperature of the heat medium oil in the primary side temperature detection section 33 at the timing tb and the temperature on the secondary side at the timing ta when the heat medium oil flows through the heat medium oil heating pipe 23 and reaches the secondary side temperature detection section 34 are determined. It becomes possible to determine misfire by using the temperature difference between the temperature detection unit 34 and the heat medium oil temperature. Therefore, the correspondence between the inflow temperature and the outflow temperature to the heat medium boiler 2 can be correctly evaluated. Further, by making the determination based on the threshold value, it is possible to easily determine whether or not the burner 21 has misfired.

In the example shown in FIG. 3, there is a temperature difference between the secondary side temperature T2a of the heat transfer oil at timing ta and the primary side temperature T1b of the heat transfer oil at timing tb, which is earlier than the timing ta by the arrival reference time ts. Since ΔT is larger than the threshold value ΔTs, the misfire determination unit 75 determines that the burner 21 has not misfired.

The arrival reference time ts is a standard arrival reference time ts based on pipe line information of the heat medium oil heating pipe 23, and is set to, for example, one minute.
As the threshold value ΔTs for determining misfire of the burner 21, a value smaller than the standard temperature difference that occurs at least at the minimum combustion amount (for example, low combustion) is used, for example, at 5°C or below 5°C. The value is set.
Normally, the standard temperature difference during low combustion is 10°C or more, so by setting such a value, the possibility of false judgments can be reduced and burner misfires can be determined with higher accuracy. can.

FIG. 4 shows an example of a case where the primary side temperature T1 of the heat transfer oil is decreasing as time t passes. Such a situation occurs when the amount of heat added to the heat medium oil by the heat medium boiler 2 is less than the amount of heat consumed by the heat usage section 200. In the case of FIG. 4, as the primary temperature T1 of the heat transfer oil decreases, the secondary temperature T2 of the heat transfer oil also decreases.

Here, a method for determining misfire of the burner 21 at timing ta will be described. The secondary side temperature T2 of the heat transfer oil at the timing ta is the temperature T2a, and the primary side temperature T1 of the heat transfer oil is the temperature T1a. At this time, when simply comparing the temperature difference (T2a - T1a) between temperatures T2a and T1a at timing ta and the threshold value ΔTs for determining misfire of the burner 21, as shown in FIG. -T1a) is larger than the threshold value ΔTs, it is determined that there is no misfire.

However, in a situation where the primary side temperature T1 of the heat medium oil flowing into the heat medium boiler 2 changes with time t, the temperature difference (T2a - T1a) between the temperatures T2a and T1a at timing ta is simply used. If the judgment is made, there is a possibility that the judgment will be incorrect.

Therefore, the misfire determination unit 75 calculates the difference between the secondary side temperature T2a of the heating medium oil at the timing ta and the primary side temperature T1b of the heating medium oil at the timing tb which is earlier than the timing ta by the arrival reference time ts. The temperature difference ΔT is calculated as ΔT, and burner misfire is determined based on this temperature difference ΔT. More specifically, when the temperature difference ΔT is less than the threshold value ΔTs, it is determined that the burner 21 has misfired.

As a result, the secondary side temperature T2a of the heat medium oil at the timing ta and the heat medium oil flowing near the arrangement position of the secondary side temperature detection section 34 at the timing ta are adjusted to the vicinity of the arrangement position of the primary side temperature detection section 33. It becomes possible to determine a misfire by using the temperature difference between the primary side temperature T1b of the heat transfer oil and the temperature T1b at the timing tb when the heat transfer oil was flowing. Therefore, the correspondence between the inflow temperature and the outflow temperature to the heat medium boiler 2 can be correctly evaluated.

In the example shown in FIG. 4, the temperature difference ΔT ( =T2a-T1b) is smaller than the threshold value ΔTs, the misfire determining unit 75 determines that the burner 21 has misfired.

Incidentally, the misfire of the burner 21 may be constantly monitored in real time by setting the timing Ta as the current time.

The misfire determination unit 75 may determine that the burner 21 has misfired when the temperature difference ΔT remains below the threshold value ΔTs for a third predetermined period of time.
This reduces the possibility of erroneous determination due to temporary fluctuations in the flow rate of heat transfer oil or changes in temperature, and makes it possible to determine misfire of the burner 21 with higher accuracy.
Note that this third predetermined time is preferably longer than the arrival reference time ts. For example, when the arrival reference time ts is 1 minute, the third predetermined time is set to be longer than the arrival reference time ts, for example, 5 to 10 minutes.
In this way, by taking a longer third predetermined time and ensuring time for the heat medium oil in the heat medium oil heating tube 23 of the heat medium boiler 2 to be replaced, the possibility of misjudgment is reduced and the burner 21 misfires. can be determined with higher accuracy.

Immediately after the boiler starts operating, the amount of heat added by the burner is consumed to warm the boiler can, making it difficult for the secondary side temperature of the heat transfer oil to rise. There is a possibility that it will become a judgment. Therefore, the misfire determining unit 75 may start the process of determining whether the burner 21 has misfired after a fourth predetermined time period has elapsed since the heating medium boiler 2 started operating. The fourth predetermined time is set to, for example, 5 to 10 minutes.
This makes it possible to prevent erroneous determination immediately after starting the operation of the boiler.

In addition, the boiler system 1 of this embodiment is equipped with the flame sensor 24 as a flame detection means. Here, the misfire determination unit 75 of the present embodiment determines that the burner 21 has misfired when the temperature difference information described above is below a predetermined threshold even if the flame sensor 24 is detecting a flame. You may.

Generally, in a steam boiler, steam is consumed on the load side, so when combustion occurs, water in the boiler body decreases due to evaporation. Therefore, it is possible to determine whether or not the boiler is burning based on the operating status of the water supply pump that keeps the water level in the boiler body constant. Therefore, even if the flame sensor detects combustion in the burner due to false detection, it can be determined that the burner has misfired if the water pump has not been operated for a predetermined period of time. If it is determined that the burner has misfired, fuel supply to the burner can be stopped to prevent fuel from accumulating in the combustion chamber of the boiler.

However, the heat medium boiler 2 like this embodiment circulates the heated fluid between it and the heat use part 200, and the heated fluid is not consumed. Therefore, during normal operation, the fluid to be heated is not supplied from the outside, and it is not possible to determine whether the burner has misfired depending on the operating status of the fluid to be heated supply device. If the flame sensor 24 detects combustion in the burner 21 due to false detection, fuel accumulation may occur in the combustion chamber of the heat medium boiler 2 due to continued fuel supply to the burner 21.

Therefore, when the boiler system 1 is equipped with the flame sensor 24 as in the present embodiment, the misfire determination section 75 uses the above-mentioned temperature difference information even when the flame sensor 24 is detecting a flame. is below a predetermined threshold value, it is determined that the burner 21 has misfired.
As a result, it is normally possible to detect a misfire in the burner 21 by the flame sensor 24, and even if a misfire in the burner 21 cannot be detected due to an erroneous detection by the flame sensor 24, the misfire determination unit 75 However, it is possible to determine whether the burner 21 has misfired based on the above-mentioned temperature difference information.

As described above, according to the present embodiment, even when the time required for the heated fluid to flow from the upstream part to the downstream part of the heat medium oil heating pipe 23 as a heat exchanger is long, the inflow temperature to the boiler It becomes possible to correctly evaluate the correspondence between the temperature and the outflow temperature, and it is possible to accurately determine burner misfire. In addition, when the pipe length of the heat medium oil heating pipe 23 is long, the residence time becomes long, so the time delay becomes noticeable. The time delay is also noticeable when the flow velocity in the heat medium oil heating pipe is slow.

Further, according to the present embodiment, even when there is a temperature fluctuation in the primary side temperature T1 of the heat medium oil as the fluid to be heated due to a fluctuation in the amount of heat used in the heat usage section 200, for example, the average temperature Even if there is a temperature fluctuation that is not a short-term fluctuation due to combustion disturbances that are excluded by the process, it is possible to accurately determine whether the burner 21 has misfired.

FIG. 5 is a functional block diagram showing the configuration of the control section 7 in the first modified example of the present embodiment. The control unit 7 of this modification further includes a primary side average temperature calculation unit 72 and a secondary side average temperature calculation unit 73.

The secondary side average temperature calculation unit 73 calculates the average value of the secondary side temperature T2 of the heat transfer oil at the timing ta for a second predetermined period of time as the secondary side average temperature of the heat transfer oil. For example, the average value of the secondary side temperature T2 of the heating medium oil for 5 seconds before and after the timing ta in FIG. 3, for a total of 10 seconds, is calculated as the secondary side average temperature T2a-ave of the heating medium oil.

The primary side average temperature calculation unit 72 calculates the average value of the primary side temperature T1 of the heating medium oil for a first predetermined period at timing tb, which is the arrival reference time ts earlier than the timing ta, as the primary side average temperature of the heating medium oil. do. For example, the average value of the primary side temperature T1 of the heating medium oil for 5 seconds before and after the timing tb in FIG. 3, for a total of 10 seconds, is calculated as the primary side average temperature T1b-ave of the heating medium oil.

The misfire determination unit 75 calculates, as temperature difference information, the difference between the secondary average temperature T2a-ave at timing ta and the primary average temperature T1b-ave at timing tb, which is earlier than the timing ta by the arrival reference time ts. , based on this temperature difference information, it is determined whether the burner has misfired.

As a result, even when there are disturbances such as short-term fluctuations in the flow rate of heat medium oil due to valve switching or fluctuations in temperature of heat medium oil due to temporary changes in combustion conditions, the effect of the disturbance is alleviated by calculating the average value. can do.

Note that the first predetermined time period for determining the primary side average temperature T1b-ave of the heat medium oil and the second predetermined time period for determining the secondary side average temperature T2a-ave of the heat medium oil are determined from the arrival reference time ts. It is also preferable to make it shorter.
This prevents excessive averaging of the primary side temperature T1 of the heating medium oil and the secondary side temperature T2 of the heating medium oil, and makes it possible to appropriately determine a misfire.

Note that the primary side average temperature T1b-ave of the heating medium oil and the secondary side average temperature T2a-ave of the heating medium oil may be determined as a moving average. In this case, it is also possible to constantly monitor the burner 21 for misfire in real time.

The misfire determining section 75 may determine whether the burner 21 has misfired based on the temperature difference between the exhaust gas outlet temperature and the heating medium temperature detected by the exhaust gas outlet temperature detecting section 51 that detects the exhaust gas outlet temperature.
Specifically, the misfire determination unit 75 determines that the above-mentioned temperature difference information is below a predetermined threshold value, and the exhaust gas outlet temperature is a predetermined temperature (for example, 5° C.), it may be determined that the burner 21 has misfired.

Generally, when the heat medium boiler 2 is burning, the exhaust gas outlet temperature is higher than the secondary side temperature T2 of the heat medium oil. On the other hand, when the heat medium boiler 2 is not burning, the temperature difference between the temperature of the gas flowing through the exhaust gas line 5 and the secondary side temperature T2 of the heat medium oil becomes small. Alternatively, the temperature of the gas flowing through the exhaust gas line becomes lower than the secondary side temperature T2 of the heat transfer oil. Therefore, the above-described determination method using information on the temperature of the heated fluid and the exhaust gas outlet temperature reduces the possibility of erroneous determination and makes it possible to determine burner misfire with higher accuracy.

FIG. 6 is a functional block diagram showing the configuration of the control section 7 in a second modified example of the present embodiment. The control unit 7 of this modification further includes an arrival reference time setting unit 74.

The arrival reference time setting unit 74 sets the arrival reference time ts based on heated fluid information that is information about the heated fluid.
For example, the arrival reference time setting unit 74 calculates the arrival reference time ts based on the flow rate information of the heating medium oil as information on the fluid to be heated, which is actually measured by the flow rate detection unit 36, and calculates the arrival reference time ts. This is set as the arrival reference time ts necessary for calculating temperature difference information for determining misfire. In this case, the arrival reference time ts may be calculated and set based on the actually measured flow rate information and information such as the flow path length of the heat medium oil heating tube 23. Alternatively, table data indicating the correspondence between the flow rate information and the arrival reference time ts may be stored in the storage unit 79. The arrival reference time setting section 74 sets the arrival reference time ts based on the flow rate information actually measured by the flow rate detection section 36 and the table data stored in the storage section 79.
Further, instead of using the flow rate information, the arrival reference time ts may be calculated and set using various types of heated fluid information such as flow velocity information of the heated fluid.

Furthermore, information on the type of fluid to be heated and fluid characteristics such as viscosity can be input as fluid information to be heated from an input unit (not shown), and based on the input fluid information to be heated, the arrival reference time ts can be calculated. This may be estimated and set as the arrival reference time ts necessary for calculating temperature difference information for determining whether the burner 21 has misfired.
The storage unit 79 stores the arrival reference time ts for subsequent processing.
This makes it possible to appropriately set the arrival reference time ts, and as a result, it becomes possible to determine misfire of the burner 21 with higher accuracy.

Note that the determination process by the misfire determination unit of this embodiment is particularly suitably applicable when the fluid to be heated is heat transfer oil; however, the fluid to be heated is not limited to heat transfer oil, but may also be hot water. good.
In addition, in this embodiment, the case where the heat medium boiler 2 is an oil-fired boiler which has a problem of fuel accumulation in the combustion chamber of the boiler has been explained as an example, but the heat medium boiler 2 is a gas-fired boiler. Good too. Even in the case of a gas-fired boiler, misfire of the burner 21 can be accurately determined.

According to the boiler system 1 of the first embodiment described above, the following effects are achieved.

(1) The boiler system 1 of this embodiment includes a burner 21 and a heat medium oil heating device as a monotube heat exchanger that exchanges heat between the combustion gas generated by the burner 21 and the heat medium oil as a heated fluid. A primary side temperature detection section 33 that detects the primary side temperature of the heated fluid on the inlet side of the heat exchanger, and a secondary side temperature detecting section 33 that detects the secondary side temperature of the heated fluid on the outlet side of the heat exchanger. The storage unit 79 includes a temperature detection unit 34 , a control unit 7 having a storage unit 79 and a misfire determination unit 75 , and the storage unit 79 is configured such that the heated fluid is transferred from the arrangement position of the primary side temperature detection unit 33 to the secondary side temperature detection unit 34 . The misfire determining unit 75 stores the arrival reference time ts corresponding to the time required for the flow to reach the arrangement position, and uses information based on the secondary side temperature T2a at the predetermined timing ta and the arrival reference time ts that is shorter than the predetermined timing ta. The difference from the information based on the primary side temperature T1b at the timing tb going back from ts is calculated as temperature difference information (temperature difference ΔT), and misfire of the burner 21 is determined based on the temperature difference information.
Thereby, even when there is a temperature fluctuation in the primary temperature T1 of the heated fluid, it is possible to accurately determine whether or not the burner 21 has misfired.

(2) The control unit 7 of the present embodiment includes a primary side average temperature calculation unit 72 that calculates the average value of the primary side temperature T1 in a first predetermined time as a primary side average temperature, and a primary side average temperature calculation unit 72 that calculates the average value of the primary side temperature T1 in a first predetermined time, and A secondary side average temperature calculation unit 73 calculates the average value of the temperature T2 as a secondary side average temperature, and the misfire determination unit 75 calculates the secondary side average temperature T2a-ave at a predetermined timing ta and a predetermined The difference from the primary side average temperature T1b-ave at the timing tb, which is the arrival reference time ts earlier than the timing ta, is calculated as temperature difference information (temperature difference ΔT), and based on the temperature difference information, a misfire of the burner 21 is determined. .
As a result, even when there are disturbances such as short-term fluctuations in the flow rate of heat medium oil due to valve switching or fluctuations in temperature of heat medium oil due to temporary changes in combustion conditions, the effect of the disturbance is alleviated by calculating the average value. can do.

(3) In the boiler system 1 of this embodiment, the first predetermined time and the second predetermined time are shorter than the arrival reference time ts.
In this way, by making the first predetermined time and the second predetermined time shorter than the attainment reference time ts, it is possible to prevent excessive averaging of the primary side temperature T1 and the secondary side temperature T2, and to appropriately determine a misfire. I can do it.

(4) The control unit 7 of the present embodiment includes an arrival reference time setting unit 74 that sets an arrival reference time ts, and the arrival reference time setting unit 74 is based on heated fluid information that is information on the heated fluid. , set the arrival reference time.
This makes it possible to appropriately set the arrival reference time ts, and as a result, it becomes possible to determine misfire of the burner 21 with higher accuracy.

(5) The misfire determination unit 75 of this embodiment determines that the burner 21 has misfired when the above-mentioned temperature difference information (temperature difference ΔT) is less than a predetermined threshold value ΔTs.
This makes it possible to easily determine whether or not the burner has misfired.

(6) The misfire determination unit 75 of this embodiment determines that the burner 21 has misfired when the above-mentioned temperature difference information (temperature difference ΔT) remains below the predetermined threshold value ΔTs for a third predetermined period of time.
This reduces the possibility of erroneous determination due to temporary fluctuations in the flow rate of heat transfer oil or changes in temperature, and makes it possible to determine misfire of the burner 21 with higher accuracy.

(7) In the boiler system 1 of this embodiment, the third predetermined time is longer than the arrival reference time ts.
In this way, by ensuring time for the heat medium oil in the heat medium oil heating tube 23 of the heat medium boiler 2 to be replaced, the possibility of misjudgment is reduced and misfire of the burner 21 can be determined with higher accuracy. becomes possible.

(8) The boiler system 1 of the present embodiment further includes a flame sensor 24 as a flame detection means for detecting the flame of the burner 21, and the misfire determination unit 75 is in a state where the flame sensor 24 detects the flame. However, if the above-mentioned temperature difference information (temperature difference ΔT) is less than a predetermined threshold value ΔTs, it is determined that the burner 21 has misfired.
As a result, it is normally possible to detect a misfire in the burner 21 by the flame sensor 24, and even if a misfire in the burner 21 cannot be detected due to an erroneous detection by the flame sensor 24, the misfire determination unit 75 However, it is possible to determine whether the burner 21 has misfired.

(9) The boiler system 1 of the present embodiment further includes an exhaust gas outlet temperature detection unit 51 that detects the exhaust gas outlet temperature, and the misfire determination unit 75 determines that the above-mentioned (temperature difference ΔT) is below a predetermined threshold ΔTs, and When the exhaust gas outlet temperature is equal to or lower than the sum of the secondary side average temperature T2a-ave and a predetermined temperature, it is determined that the burner 21 has misfired.
In this way, by using the information on the temperature of the heated fluid and the exhaust gas outlet temperature, it is possible to reduce the possibility of misjudgment and to determine misfire of the burner 21 with higher accuracy.

(10) The misfire determining unit 75 of this embodiment starts the process of determining whether the burner 21 has misfired after a fourth predetermined time has elapsed since the heating medium boiler 2 started operating.
Thereby, it becomes possible to prevent an erroneous determination immediately after the operation of the heat medium boiler 2 is started.

Although preferred embodiments of the boiler of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate.

1 Boiler system 2 Heat medium boiler 21 Burner 23 Heat medium oil heating tube (heat exchanger)
24 Flame sensor (flame detection means)
3 Heat medium circulation line 31 Heat medium oil return line 32 Heat medium oil supply line 33 Primary side temperature detection section 34 Secondary side temperature detection section 35 Circulation pump 36 Flow rate detection section 4 Fuel supply line 41 Fuel adjustment valve 5 Exhaust gas line 51 Exhaust gas Outlet temperature detection section 7 Control section 71 Combustion control section 72 Primary side average temperature calculation section 73 Secondary side average temperature calculation section 74 Attainment reference time setting section 75 Misfire determination section 79 Storage section

Claims (7)

Burna and
a monotube heat exchanger that exchanges heat between the combustion gas generated by the burner and the heated fluid;
a primary side temperature detection unit that detects a primary side temperature of the heated fluid on the inlet side of the heat exchanger;
a secondary side temperature detection unit that detects a secondary side temperature of the heated fluid on the outlet side of the heat exchanger;
A control unit having a storage unit and a misfire determination unit,
The storage unit includes:
storing an arrival reference time corresponding to the time required for the heated fluid to flow from the arrangement position of the primary side temperature detection unit to the arrangement position of the secondary side temperature detection unit;
The misfire determination section includes:
The difference between the information based on the secondary side temperature at a predetermined timing and the information based on the primary side temperature at a timing that is earlier than the predetermined timing by the arrival reference time is calculated as temperature difference information, and the temperature difference is calculated as temperature difference information. A boiler system that determines that the burner has misfired when a state in which information is below a predetermined threshold continues for a third predetermined time longer than the arrival reference time. The control unit includes:
a primary side average temperature calculation unit that calculates the average value of the primary side temperature in a first predetermined time period as a primary side average temperature;
a secondary side average temperature calculation unit that calculates the average value of the secondary side temperature in a second predetermined time period as a secondary side average temperature,
The misfire determination section includes:
The difference between the secondary side average temperature at a predetermined timing and the primary side average temperature at a timing that is earlier than the predetermined reference time is calculated as the temperature difference information, and the temperature difference information is calculated as the temperature difference information at a predetermined time. 2. The boiler system according to claim 1, wherein a misfire of the burner is determined when the state of being below the threshold continues for a third predetermined time longer than the arrival reference time. The boiler system according to claim 2, wherein the first predetermined time and the second predetermined time are shorter than the arrival reference time. The control unit includes an arrival reference time setting unit that sets the arrival reference time,
The boiler system according to any one of claims 1 to 3, wherein the arrival reference time setting unit sets the arrival reference time based on heated fluid information that is information about the heated fluid. Further comprising a flame detection means for detecting the flame of the burner,
The misfire determination section includes:
Even when the flame detection means detects a flame, if the temperature difference information continues to be below a predetermined threshold value for the third predetermined time period , it is determined that the burner has misfired. The boiler system according to any one of items 1 to 4. It further includes an exhaust gas outlet temperature detection section that detects the exhaust gas outlet temperature,
The misfire determination section includes:
When the state in which the temperature difference information is below a predetermined threshold continues for the third predetermined time , and the exhaust gas outlet temperature is equal to or lower than the sum of the secondary side average temperature and the predetermined temperature, the The boiler system according to claim 2 or 3, wherein it is determined that the burner has misfired. The misfire determination section includes:
The boiler system according to any one of claims 1 to 6, wherein the process of determining whether or not the burner has misfired is started after a fourth predetermined time period has elapsed since the start of operation of the boiler.

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