JP2013164177A - Combined combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the backflow of combustion exhaust gas from a combustion machine in a combustion operating state to combustion machines in non-combustion operating states through a collected exhaust pipe.SOLUTION: In a combined combustion device having a plurality of combustion machines 2 each having a burner 4, a blowing fan 5, a collected exhaust pipe 10 and for coupling the plurality of combustion machines 2, and check valves 7 opened by the rotation of the blowing fan 5 for preventing the backflow of the combustion exhaust gas to the respective combustion machines 2 from the collected exhaust pipe 10 in the case that a part of the combustion machines 2 of the plurality of combustion machines 2 is in a combustion operating state and the other combustion machines 2 are continuously in non-combustion operating states for a time not shorter than a predetermined operation stop reference time, the blowing fans 5 of the other combustion machines 2 are rotated in a certain time.

Description

  The present invention relates to a combined combustion apparatus including a plurality of combustors each having a burner and a blower fan, and a collective exhaust pipe connecting the plurality of combustors. In particular, the present invention relates to a composite combustion apparatus capable of preventing a backflow of combustion exhaust from a collective exhaust pipe.

  2. Description of the Related Art Conventionally, there is known a combined combustion apparatus in which a plurality of combustors each having a burner and a blower fan are installed in parallel, and these combustors are connected by a collective exhaust pipe. This type of combined combustion apparatus is controlled so that the number of operating combustors is adjusted according to the load. When the combustion operation is performed, the combustion exhaust from each combustor is discharged to the outside through the collective exhaust pipe by the rotation of the blower fan.

  By the way, in the said composite combustion apparatus, since a required number of combustors are combustion-operated according to load, a combustion operation may be performed only with some combustors among several combustors. Therefore, in the combustor in the combustion operation state, the combustion exhaust is discharged to the collective exhaust pipe by the rotation of the blower fan. However, in the combustor in the non-combustion operation state, the blower fan is not rotated, so the combustion operation state is set via the collective exhaust pipe. There is a possibility that the combustion exhaust gas flows backward from the combustor to the combustor in the non-combustion operation state. As a result, acidic combustion exhaust gas containing nitrogen, sulfur, etc., tends to corrode components such as burners and blower fans in the combustor.

  In view of the above circumstances, it is conceivable to prevent the backflow of the combustion exhaust from the collective exhaust pipe by rotating the blower fan not only in the combustor in the combustion operation state but also in the combustor in the non-combustion operation state. (For example, patent document 1).

  However, the above-described combined combustion apparatus has a problem that it is economically inefficient because of the necessity of rotating the blower fan even in a combustor in a non-combustion operation state, and the operation cost increases. Further, since the burner is not combusted in the combustor in the non-combustion operation state, not only the inside of the combustor is cooled by the rotation of the blower fan, thereby causing heat loss, but also a heat exchanger disposed in the combustor in winter. There is a problem that water in the pipe freezes. In particular, the combined combustion apparatus is a large-sized apparatus and is installed in a low-temperature place such as a boiler room or a basement, so that the above-described freezing problem is likely to occur.

JP 2001-132940 A

  The present invention has been made in view of the above problems, and an object of the present invention is to effectively prevent combustion exhaust flowing backward from a combustor in a combustion operation state to a combustor in a non-combustion operation state through a collective exhaust pipe. The object is to provide a combined combustion apparatus.

According to the present invention, a plurality of combustors each having a burner and a blower fan;
An exhaust stack connecting the plurality of combustors;
A check valve disposed in each combustor and opened by rotation of the blower fan to prevent backflow of combustion exhaust from the collective exhaust pipe into the combustor;
A combined combustion apparatus comprising a control device for controlling operation of the plurality of combustors,
The control device is configured such that when some of the plurality of combustors are in a combustion operation state and other combustors are continuously in a non-combustion operation state for a predetermined operation stop reference time or more, There is provided a composite combustion apparatus that performs intermittent operation for rotating a blower fan of the combustor for a certain period of time.

  According to the above composite combustion apparatus, each combustor has a check valve that is opened by the rotation of the blower fan. Therefore, even if the combustion exhaust is discharged from the combustor in the combustion operation state to the collective exhaust pipe, the non-combustion operation is performed. The backflow of the combustion exhaust gas to the combustor in the state can be prevented. On the other hand, when the check valve is provided, there is a possibility that the sealing performance of the check valve may be deteriorated due to the check valve being caught or foreign matter getting caught in the check valve. However, according to the composite combustion device, when the combustor is in the non-combustion operation state for a predetermined operation stop reference time or longer, intermittent operation is performed to rotate the blower fan for a certain period of time. Even when the air pressure decreases, the air in the combustor can be exhausted to the collective exhaust pipe, thereby suppressing the backflow of the combustion exhaust gas. In addition, if the duration time of the non-combustion operation state is equal to or longer than the predetermined operation stop reference time, intermittent operation is performed to rotate the blower fan, so the combustion exhaust gas is discharged before the combustion exhaust gas flowing back in the combustor increases. can do. Further, in the other combustors in the non-combustion operation state, the blower fan is intermittently rotated, so that the backflow of the combustion exhaust can be prevented more efficiently than in the case where the blower fan is operated continuously, and the non-combustion operation is performed. Freezing in the combustor in the state can also be prevented.

In the above composite combustion apparatus,
The check valve preferably includes a first valve that opens by rotating the blower fan at a high rotational speed, and a second valve that opens by rotating the blower fan at a low rotational speed. .

  According to the above composite combustion apparatus, the check valve has the second valve that is opened by rotating the blower fan at a low rotational speed, so that the backflow of the combustion exhaust can be efficiently prevented. Further, since the check valve has the first valve that opens by rotating the blower fan at a high rotational speed, the exhaust of the combustion exhaust is not hindered during the combustion operation.

In the above composite combustion apparatus,
Each of the combustors includes a backflow detection unit that detects a backflow of combustion exhaust,
When the backflow of the combustion exhaust is detected by the backflow detection unit,
The control device preferably rotates the blower fan of the other combustor for a predetermined time even when the other combustor is in the non-combustion operation state for less than the operation stop reference time.

  If each combustor has a backflow detection unit that detects the backflow of combustion exhaust, it is possible to directly detect that a certain amount of combustion exhaust has flowed back into the combustor. Even if the blower fan of the combustor in the non-combustion operation state is rotated at regular intervals, if the backflow of the combustion exhaust is detected by the backflow detection unit, the check valve has a sealing performance due to the check valve being caught, etc. There is a possibility that the amount of combustion exhaust gas that has decreased and flows back into the combustor has increased. Therefore, even if the non-combustion operation state is less than the operation stop reference time, if the blower fan of another combustor in the non-combustion operation state is rotated, the combustion exhaust gas that has flowed back into the combustor can be reliably discharged. it can.

In the above composite combustion apparatus,
Each of the combustors includes a backflow detection unit that detects a backflow of combustion exhaust,
When the backflow of the combustion exhaust is detected by the backflow detection unit,
The control device may shorten the operation stop reference time.

  If each combustor has a backflow detection unit that detects the backflow of combustion exhaust, it is possible to directly detect that a certain amount of combustion exhaust has flowed back into the combustor. Even if the blower fan of the combustor in the non-combustion operation state is rotated at regular intervals, if the backflow of the combustion exhaust is detected by the backflow detection unit, the check valve has a sealing performance due to the check valve being caught, etc. There is a possibility that the amount of combustion exhaust gas that has decreased and flows back into the combustor has increased. Therefore, if the operation stop reference time for determining that the combustor is in the non-combustion operation state is shortened, the combustion exhaust that has flowed back into the combustor at an early stage can be discharged.

In the above composite combustion apparatus,
After reducing the operation stop reference time, when the backflow of the combustion exhaust is detected by the backflow detection unit,
The control device may notify abnormality.

  If the backflow detection unit detects a backflow of combustion exhaust even if the operation stop reference time is shortened and the rotation frequency of the blower fan is increased, simply turning the blower fan will cause the check valve to catch the check valve. It may not be possible to repair the deterioration of the sealing performance. Therefore, according to the composite combustion apparatus, it is possible to make the user recognize an abnormality caused by the backflow of the combustion exhaust at an early stage.

  As described above, according to the present invention, in a combined combustion apparatus including a plurality of combustors each having a burner and a blower fan, and a collective exhaust pipe connecting the plurality of combustors, combustion in a combustion operation state It is possible to effectively prevent the combustion exhaust flowing backward from the engine to the combustor in the non-combustion operation state via the collective exhaust pipe.

FIG. 1 is a schematic configuration diagram showing an example of a combined combustion apparatus according to an embodiment of the present invention. FIG. 2 is a schematic sectional view showing a check valve according to the embodiment of the present invention. FIG. 3 is a control flow diagram showing the operation of the combined combustion apparatus according to the embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing an example of a combined combustion apparatus according to another embodiment of the present invention.

  FIG. 1 is a schematic configuration diagram showing an example of a combined combustion apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the combined combustion apparatus according to the present embodiment includes, for example, three combustors 2, 2,... That are hot water heaters, and a collective exhaust pipe 10 that connects these combustors 2. Is a so-called forced exhaust type combined combustion apparatus.

  Each combustor 2 has a can body 20 in which an air supply port 21 to which combustion air is supplied and an exhaust port 22 from which combustion exhaust gas is discharged is formed. 3, and a burner 4 is disposed below it. In addition, a blower fan 5 is disposed below the can body 20. In addition, in this Embodiment, the combustor 2 which has the same combustion capability is used, However, The combustor 2 which has a different combustion capability may be used according to a usage pattern.

  A gas circuit 41 is connected to the burner 4, and a gas proportional solenoid valve 42 is inserted into the gas circuit 41. The opening degree of the gas proportional solenoid valve 42 is controlled by a combustion amount signal from the control device C described later, and thereby the gas amount to the burner 4 is increased or decreased. An igniter and a thermocouple (not shown) are disposed adjacent to the burner 4.

  The heat exchanger 3 includes an endothermic tube 3a and a plurality of fins 3b arranged to intersect the endothermic tube 3a. The heat absorption pipe 3a is connected to the water supply pipe 31 on the inlet side and is connected to the hot water discharge pipe 32 on the outlet side. The water supply pipe 31 is provided with a water amount sensor 33 and a water supply temperature thermistor 34, and the hot water discharge pipe 32 is provided with a hot water temperature thermistor 35. The water amount detected by the water amount sensor 33, the feed water temperature detected by the feed water temperature thermistor 34, and the hot water temperature detection signal detected by the hot water temperature thermistor 35 are output to the control device C.

  The blower fan 5 is connected to a fan motor 6, and the fan motor 6 is driven by applying a voltage corresponding to a combustion amount signal from the control device C. Further, the rotational speed of the blower fan 5 and the combustion amount signal are in a proportional relationship, and the rotational speed of the blower fan 5 is increased as the combustion amount increases. Thus, when the combustion operation is performed, combustion air is supplied into the combustor 2 and combustion exhaust generated by the burner 4 burning is discharged out of the combustor 2. Furthermore, the rotational speed of the blower fan 5 is detected by the rotational speed sensor 51, and the detected fan rotational speed detection signal is output to the control device C.

  An air supply side passage 23 for supplying indoor air outside the combustor 2 into the can body 20 as combustion air is connected to the air supply port 21 of the can body 20 by rotation of the blower fan 5. Yes. Further, an exhaust side passage 24 for exhausting combustion exhaust in the combustor 2 to the outside through the collective exhaust cylinder 10 by the rotation of the blower fan 5 is connected to the exhaust port 22 of the can body 20. .

  The downstream end of the exhaust side passage 24 is connected to the collective exhaust pipe 10. Further, the exhaust side passage 24 is provided with a check valve 7 for communicating and blocking the exhaust side passage 24. Thereby, even if combustion exhaust is discharged from the combustor 2 in the combustion operation state to the collective exhaust pipe 10, the check valve 7 can prevent the backflow of the combustion exhaust into the combustor 2 in the unburned operation state. .

  As shown in FIG. 2, in the present embodiment, a large-diameter first valve 71 having through holes 73, 73 in the central portion and the outer periphery thereof, and a small-diameter second valve inserted in the through-hole 73 in the central portion. 72, and a double valve type check valve 7 is used. Specifically, when the blower fan 5 is not rotating, due to its own weight, the lower surface of the first valve 71 is engaged with the engaging portion 25 provided in the exhaust side passage 24, and the lower surface of the second valve 72 is the first valve. The exhaust side passage 24 is shut off by contacting the upper surface of 71. Further, when the rotational speed of the blower fan 5 is equal to or higher than a predetermined low rotational speed, the first valve 71 is closed and the second valve 72 is separated from the first valve 71 and opened. As a result, a narrow gap is formed between the first valve 71 and the second valve 72, and the exhaust side passage 24 communicates with the through holes 73 and 73. Furthermore, when the rotational speed of the blower fan 5 becomes equal to or higher than a predetermined high rotational speed, the first valve 71 is separated from the engaging portion 25 and opened. As a result, a wide gap is formed between the first valve 71 and the exhaust side passage 24, and the exhaust side passage 24 communicates.

  Returning to FIG. 1, a CO sensor 8 that detects the concentration of carbon monoxide in the combustor 2 is disposed near the exhaust port 22 in the upper part of the can body 20 as a backflow detection unit for detecting the backflow of combustion exhaust gas. It is installed. A detection signal of the carbon monoxide concentration detected by the CO sensor 8 is always output to the control device C.

  The collective exhaust pipe 10 branches to connect to the exhaust side passage 24 of each combustor 2 and communicates with the outdoors at the downstream end thereof. Thereby, the combustion exhaust generated from the combustor 2 during the combustion operation is discharged to the outside through the collective exhaust pipe 10.

  The combined combustion apparatus includes, as the control device C, a control unit Cc that controls the operation of each combustor 2 and a connecting unit Cp that controls the operation of these control units Cc. Although not shown, the control unit Cc includes a combustion operation control unit that performs the combustion operation of the combustor 2 and a fan control unit that controls the operation of the blower fan. The connection unit Cp performs the combustion operation according to the load. An operation control unit that determines the required number of combustors 2 to perform, and instructs each control unit Cc to perform a combustion operation; an intermittent blower operation control unit that instructs a combustor 2 in a non-combustion operation state; A memory, a timer, and the like in which programs for performing these operations are stored are provided. The control unit Cc of each combustor 2 includes an igniter, a thermocouple, a gas proportional solenoid valve 42, a water amount sensor 33, a feed water temperature thermistor 34, a hot water temperature thermistor 35, a fan motor 6, a rotation speed sensor 51, a CO sensor 8, and the like. These detection signals are output to the connecting unit Cp. The connecting unit Cp is electrically connected to the control unit Cc, a remote controller R provided indoors, and the like.

  The operation control unit of the connection unit Cp determines the number of combustion operations of the combustors 2 according to the load, the amount of water detected by the water amount sensor 33, the feed water temperature detected by the feed water temperature thermistor 34, and the hot water temperature thermistor 35. Based on the tapping temperature detected in step 1, the required amount of combustion of the burner 4 is calculated using a predetermined arithmetic expression or the like. Further, the combustion operation control unit of the control unit Cc generates an appropriate amount of combustion air corresponding to the required required combustion amount based on an instruction from the operation control unit of the connecting unit Cp during combustion of the burner 4. The target rotational speed of the blower fan 5 for supplying air to the burner 4 in 2 is set. Then, the fan motor 6 is feedback-controlled so that the fan rotational speed detected by the rotational speed sensor 51 provided in the blower fan 5 matches the target rotational speed. Further, in order to supply the burner 4 with an amount of gas that matches the amount of combustion air supplied to the burner 4 by the blower fan 5, a gas proportional solenoid valve according to the fan rotation speed detected by the rotation speed sensor 51. The energization amount to 42 is determined, and the gas proportional solenoid valve 42 is energized and controlled by the energization amount. As a result, an amount of gas that matches the amount of combustion air supplied to the burner 4 is supplied to the burner 4. In addition, the carbon monoxide concentration detected by the CO sensor 8 in the combustor 2 in the combustion operation state is constantly monitored, and the connecting unit Cp is a combustor having a predetermined carbon monoxide concentration in at least one combustor 2. When the concentration exceeds the operation reference concentration, it is determined that a combustion failure has occurred, the abnormality is notified, the supply of gas to the burner 4 is stopped, and the combustion operation is stopped.

  The intermittent blower operation control unit of the connection unit Cp activates a timer when the combustion operation control unit of the control unit Cc does not perform the combustion operation, and the combustor 2 is in the non-combustion operation state. Measure time. Then, when the combustor 2 is continuously in the non-combustion operation state for a predetermined operation stop reference time or longer, the intermittent blower operation control unit of the connection unit Cp instructs the control unit Cc to perform the intermittent operation of the blower fan 5, The fan control unit of the control unit Cc rotates the blower fan 5 of the combustor 2 in the non-combustion operation state at a minimum rotation speed for a certain time. Note that the rotation time of the blower fan 5 in the intermittent blower operation is appropriately selected in consideration of the volume inside the combustor 2 and the blower capacity of the blower fan 5. Further, when the carbon monoxide concentration detected by the CO sensor 8 in the combustor 2 in the non-combustion operation state becomes equal to or higher than a predetermined non-combustion operation reference concentration, the combustor 2 is less than the operation stop reference time, Even in the operating state, as described above, the blower fan 5 is rotated at the minimum rotation speed for a certain period of time, and the operation stop reference time for judging that the combustor 2 is in the non-combustion operation state for a predetermined time is shortened. To do. Further, the connection unit Cp has a check valve 7 having a sealing property when the carbon monoxide concentration detected by the CO sensor 8 becomes equal to or higher than the non-combustion operation reference concentration after the operation stop reference time is shortened. It judges that it fell, and while alert | reporting abnormality, supply of the gas to the burner 4 is stopped and combustion operation is stopped.

  Next, the control operation for preventing the backflow of the combustion exhaust in the combined combustion apparatus of the present embodiment will be described based on FIG.

  When the operation of the system is started and the connecting unit Cp determines the required number of the combustors 2 to perform the combustion operation, the control unit Cc instructed to perform the combustion operation starts the above-described combustion operation in the combustor 2, The connecting unit Cp determines whether or not each combustor 2 is performing a combustion operation (step ST1). When only some of the combustors 2 are in the combustion operation state and the other combustors 2 are in the non-combustion operation state, the intermittent blower operation control unit of the connection unit Cp And the stop time of the blower fan 5 in the combustor 2 in the non-combustion operation state is measured (step ST2). That is, when the combustor 2 is in the non-combustion operation state, it is not necessary to rotate the blower fan 5, and therefore the duration time of the non-combustion operation state is measured by measuring the stop time of the blower fan 5. Can do. In addition, you may judge the continuation time of a non-combustion driving | running state from the combustion time of the burner 4 detected by a thermocouple etc.

  Next, the carbon monoxide concentration output from the CO sensor 8 is monitored, and is the carbon monoxide concentration in the combustor 2 in the non-combustion operation state equal to or higher than a predetermined non-combustion operation reference concentration (for example, 50 ppm)? Whether or not is confirmed (step ST3). As a result, it is possible to determine that the sealing performance of the check valve 7 has deteriorated and the combustion exhaust has flowed back into the combustor 2 in the non-combustion operation state via the collective exhaust pipe 10.

  When the carbon monoxide concentration in the combustor 2 is less than the non-combustion operation reference concentration (No in step ST3), the intermittent air blow operation control unit stops the blower fan 5 of the combustor 2 in the non-combustion operation state. It is confirmed whether the time is equal to or longer than a predetermined initial operation stop reference time (for example, 3 minutes) (step ST4).

  When the blower fan 5 is stopped for the initial operation stop reference time or longer (Yes in step ST4), the blower fan 5 of the combustor 2 in the non-combustion operation state is at a minimum rotation speed for a certain time (for example, 3 seconds). ), And the timer is reset (step ST5). As a result, the second valve 72 of the check valve 7 disposed in the exhaust side passage 24 is opened, and the air in the combustor 2 is discharged to the collective exhaust pipe 10. Therefore, even when the combustion exhaust gas having a carbon monoxide concentration lower than the non-combustion operation reference concentration flows backward into the combustor 2 in the non-combustion operation state, the combustion exhaust gas can be discharged out of the combustor 2 at an early stage. Further, even when the sealing performance of the check valve 7 is deteriorated, the air in the combustor 2 can be discharged to the exhaust side passage 24 at every fixed operation stop reference time, so that the back flow of the combustion exhaust can be suppressed. it can. Furthermore, since the blower fan 5 is rotated only for a short time, it is possible to efficiently prevent the backflow of the combustion exhaust as compared with the case where the blower fan 5 is continuously operated, and freezing in the combustor 2 in the non-combustion operation state in winter. Can also be prevented.

  When the rotation of the blower fan 5 is completed, confirmation of the non-combustion operation state, measurement of the stop time of the blower fan 5, and confirmation of the carbon monoxide concentration in the combustor 2 are repeated (steps ST1 to ST3).

  When the carbon monoxide concentration in the combustor 2 becomes equal to or higher than a predetermined non-combustion operation reference concentration even though the combustor 2 is in the non-combustion operation state (Yes in step ST3), the blower fan 5 being measured Even if the stop time is less than the initial operation stop reference time, the blower fan 5 is rotated for a certain time (for example, 3 seconds), and the timer is reset (step ST6). Thereby, the increase in the combustion exhaust gas flowing back into the combustor 2 can be suppressed.

  Next, it is determined whether or not the operation stop reference time is an initial value (step ST7). If the operation stop reference time is the initial value (Yes in step ST7), the operation stop reference time for determining the non-combustion operation state of the combustor 2 is shortened (for example, 2 minutes) (step ST8). That is, in the combustor 2 in the non-combustion operation state, since the blower fan 5 is not originally rotating, the exhaust side passage 24 is blocked by the check valve 7 and the backflow of combustion exhaust from the collective exhaust pipe 10 is prevented. Yes. Nevertheless, the fact that carbon monoxide of a certain concentration or more is detected in the combustor 2 in the non-combustion operation state means that the check valve 7 is caught or foreign matter is caught in the check valve 7. It is conceivable that the combustion exhaust easily flows back into the combustor 2. Therefore, if the operation stop reference time for determining that the combustor 2 is in the non-combustion operation state is shortened, the combustion exhaust that has flowed back into the combustor 2 at an early stage can be discharged.

  After the operation stop reference time is shortened, confirmation of the non-combustion operation state, measurement of the stop time of the blower fan 5, and confirmation of the carbon monoxide concentration in the combustor 2 are repeated (steps ST1 to ST3). When the carbon monoxide concentration in the combustor 2 in the non-combustion operation state becomes equal to or higher than the non-combustion operation reference concentration again (Yes in step ST3), the blower fan 5 is rotated for a certain period of time as described above. (Step ST6). At this time, since the operation stop reference time has already been shortened (No in step ST7), it is considered that the reverse flow of the combustion exhaust cannot be prevented only by intermittently rotating the blower fan 5 at short intervals. Accordingly, the connecting unit Cp notifies the abnormality due to the backflow of the combustion exhaust from the remote controller R or the like, and stops the combustion operation (step ST9).

  The detection of the carbon monoxide concentration is continued while the combustor 2 is in the non-combustion operation state. When the required load change increases the number of combustors 2 that need to perform a combustion operation and the combustion operation is started in the non-combustion operation state of the combustor 2 (Yes in step ST1), CO It is determined whether the carbon monoxide concentration in the combustor 2 output from the sensor 8 is equal to or higher than the combustion operation reference concentration (for example, 500 ppm) (step ST10). Note that the combustion operation reference concentration is such that gas is combusted by the burner 4 by the combustion operation, and the carbon monoxide concentration in the combustor 2 becomes higher than that in the combustor 2 in the non-combustion operation state. A value higher than the reference density is set.

  While the combustor 2 is performing the combustion operation, the carbon monoxide concentration is monitored. If the carbon monoxide concentration during the combustion operation becomes equal to or higher than the combustion operation reference concentration (Yes in step ST10), there is a high possibility that a combustion failure has occurred in the combustor 2, so that the remote controller R or the like is similar to the above. Is notified of the abnormality and the combustion operation is stopped (step ST11). Thereby, the combustion failure at the time of combustion operation can be prevented at an early stage.

(Other embodiments)
(1) In the above embodiment, the forced exhaust type combined combustion apparatus having the collective exhaust cylinder 10 has been described. 11 is also applicable to a forced combustion type combined combustion apparatus connected at 11. In this forced supply / exhaust type combined combustion apparatus, combustion air is supplied from the outside to each combustor 2 via a collective supply cylinder. The control configuration of the intermittent ventilation operation in the forced supply / exhaust type combined combustion device is the same as that in the forced exhaust type combined combustion device.

(2) In the above embodiment, the blower fan 5 is rotated at the minimum rotational speed in order to prevent the backflow of the combustion exhaust. However, in order to shorten the rotational time of the blower fan 5, the rotation is higher than the minimum rotational speed. You may rotate a ventilation fan by a number.

(3) In the above embodiment, the check valve 7 is provided in the exhaust side passage 24, but may be provided in the supply side passage 23.

(4) In the above embodiment, the double valve type check valve 7 is provided, but a single valve type check valve may be used. Moreover, when using a double valve, you may use the check valve 7 which incorporated two or more springs from which elastic force differs.

2 Combustor 4 Burner 5 Blower fan 7 Check valve 71 First valve 72 Valve 2 valve 8 CO sensor (backflow detection unit)
10 Collective stack C Controller

Claims (5)

A plurality of combustors each having a burner and a blower fan;
An exhaust stack connecting the plurality of combustors;
A check valve disposed in each combustor and opened by rotation of the blower fan to prevent backflow of combustion exhaust from the collective exhaust pipe into the combustor;
A combined combustion apparatus comprising a control device for controlling operation of the plurality of combustors,
The control device is configured such that when some of the plurality of combustors are in a combustion operation state and other combustors are continuously in a non-combustion operation state for a predetermined operation stop reference time or more, Combustion apparatus that performs intermittent operation for rotating a blower fan of a combustor for a certain period of time. The combined combustion apparatus according to claim 1,
The check valve includes a first valve that opens by rotating the blower fan at a high rotational speed, and a second combustion valve that opens by rotating the blower fan at a low rotational speed. . The combined combustion apparatus according to claim 1 or 2,
Each of the combustors includes a backflow detection unit that detects a backflow of combustion exhaust,
When the backflow of the combustion exhaust is detected by the backflow detection unit,
The said control apparatus is a compound combustion apparatus which rotates the ventilation fan of the said other combustor for a fixed time, even if the said other combustor is in the non-combustion operation state for less than the said operation stop reference time. The combined combustion apparatus according to any one of claims 1 to 3,
Each of the combustors includes a backflow detection unit that detects a backflow of combustion exhaust,
When the backflow of the combustion exhaust is detected by the backflow detection unit,
The said control apparatus is a compound combustion apparatus which shortens the said operation stop reference time. The combined combustion apparatus according to claim 4, wherein
After reducing the operation stop reference time, when the backflow of the combustion exhaust is detected by the backflow detection unit,
The control device is a combined combustion device that notifies abnormality.

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