JP7265757B2 - Multi-stage combustion device - Google Patents

Description

The present invention relates to a multistage combustion apparatus installed in a boiler or the like.

2. Description of the Related Art As a combustion device, a multi-stage combustion device including means for burning an air-fuel mixture with a high fuel concentration and means for burning an air-fuel mixture with a low fuel concentration is known, for example, from Japanese Unexamined Patent Application Publication No. 2002-200013. Further, as a multi-stage combustion device, there is known one in which a fuel supply path to a burner is provided with a plurality of valves that are turned on and off. For example, a low combustion valve capable of supplying fuel corresponding to the low combustion when the burner is low combustion and a high combustion valve capable of supplying fuel corresponding to the high combustion when the burner is high combustion are provided. By turning on only the low combustion valve during low combustion and turning on both the low and high combustion valves during high combustion, it is possible to realize multi-stage combustion of low and high combustion. can. Alternatively, multistage combustion of low combustion and high combustion can be realized by switching on/off of the low combustion valve and the high combustion valve during low combustion and high combustion.

As a multi-stage combustion device known so far, as described above, the high-combustion valve is switched on and off while the low-combustion valve is kept on, thereby switching between high-combustion and low-combustion. Some have achieved combustion. The switching timing is set based on the opening of the damper, which supplies combustion air to the burner, because the opening of the damper corresponds to the combustion amount of the burner. That is, when changing the opening of the damper to switch between low combustion and high combustion, by switching on and off the high combustion valve at the timing when the damper reaches a predetermined opening, low combustion to high combustion, or from high combustion to low combustion.

Japanese Patent Application Laid-Open No. 2002-295811

However, in the above-described conventional configuration, even if the transition from low combustion to high combustion can be performed satisfactorily, smoke and flame extinguishment may occur during the transition from high combustion to low combustion. Even if the transition from low combustion to low combustion can be performed satisfactorily, smoke and flame extinction often occur during the transition from low combustion to high combustion. In other words, it is often difficult to smoothly transition from low combustion to high combustion and from high combustion to low combustion.

SUMMARY OF THE INVENTION Accordingly, the present invention solves such problems, and enables a multi-stage combustion apparatus to smoothly perform both the transition from low combustion to high combustion and the transition from high combustion to low combustion. The purpose is to

In order to achieve this object, the first multi-stage combustion device of the present invention comprises:
a first valve for low combustion of the burner and a second valve for high combustion of the burner provided in the fuel supply to the burner;
a damper for adjusting the amount of air provided in the combustion air supply path to the burner;
A control device for controlling the opening of the damper and the on/off of at least the second valve for switching between low combustion and high combustion of the burner,
The control device controls to gradually change the damper opening between the damper opening during low combustion and the damper opening during high combustion when the burner is switched between low combustion and high combustion. and the control device is
The operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion when the damper opening is gradually changed is changed from high combustion to low combustion. is set to a lower combustion side or a higher combustion side than the operating point of the off operation of the second valve when the
The operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion, and the OFF operation of the second valve when shifting the combustion of the burner from high combustion to low combustion. The operating point is characterized in that it is set at a combustion amount that deviates from the combustion amount at which smoke or flame extinguishing occurs when the ON operation or OFF operation is performed.

According to the first multistage combustion device of the present invention,
further comprising one or more third valves for medium combustion of one or more stages of the burner, provided in the fuel supply to the burner;
The controller is
burner firing from a low firing side comprising low firing and either single or multiple stages of medium firing to a high firing side comprising either single or multiple stages of medium firing and high firing; The operating point of the ON operation of the third valve when shifting is closer to the lower combustion side than the operating point of the OFF operation of the third valve when shifting the combustion of the burner from the high combustion side to the low combustion side, or Along with setting toward the high combustion side,
an operating point at which the third valve is turned on when the combustion of the burner is shifted from the low combustion side to the high combustion side; It is preferable that the operating point of the off-operation of the valve 3 is set at a combustion amount that deviates from the amount of combustion at which smoke or flame extinguishing occurs when the on-operation or off-operation is performed.

A second multi-stage combustion device of the present invention comprises:
a first valve for low combustion of the burner and a second valve for high combustion of the burner provided in the fuel supply to the burner ;
a damper for adjusting the amount of air provided in the combustion air supply path to the burner;
A control device for controlling the opening of the damper and the on/off of at least the second valve for switching between low combustion and high combustion of the burner,
The control device controls to gradually change the damper opening between the damper opening during low combustion and the damper opening during high combustion when the burner is switched between low combustion and high combustion. and furthermore
The controller controls the combustion of the burner from low combustion to high combustion when the burner is rich in combustion air relative to fuel compared to when the burner is rich in fuel than combustion air. set the operating point of the ON operation of the second valve when shifting to low combustion, and set the operating point of the OFF operation of the second valve when shifting the combustion of the burner from high combustion to low combustion. It is characterized in that it is set closer to combustion .

According to the second multistage combustion device of the present invention,
further comprising one or more third valves for medium combustion of one or more stages of the burner, provided in the fuel supply to the burner;
The controller classifies burner combustion as low combustion when the burner is richer in combustion air than in fuel than when the burner is richer in fuel than combustion air. Turning on the third valve when transitioning from a low fire side including either a stage or multiple stages of medium combustion to a high fire side including either a single stage or multiple stages of medium combustion and high combustion The operating point of the operation is set closer to the low combustion side, and the operating point of the off operation of the third valve when shifting the combustion of the burner from the high combustion side to the low combustion side is set closer to the high combustion side. It is preferable to have

A first method for controlling a multi-stage combustion apparatus of the present invention comprises:
A method for controlling a staged combustion system comprising a first valve for low firing of the burner and a second valve for high firing of the burner in a fuel supply to the burner, comprising:
Regarding the damper for adjusting the air amount provided in the combustion air supply path to the burner, when switching the burner between low combustion and high combustion, the damper opening at low combustion and the damper opening at high combustion Gradually change the damper opening within a predetermined time between
When the damper opening is gradually changed,
The operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion, and the operating point of the OFF operation of the second valve when shifting the combustion of the burner from high combustion to low combustion. , the operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion, and the combustion of the burner from high combustion to low combustion. The operating point for turning off the second valve when transitioning to combustion is set at a combustion amount that deviates from the amount of combustion at which smoke or flame extinguishing occurs when the on or off operation is performed. Characterized by

According to the first method for controlling a multistage combustion apparatus of the present invention ,
The multi-stage combustion device further comprises one or more third valves for intermediate combustion of one or more stages of the burner, provided in the fuel supply path to the burner,
When the damper opening is gradually changed,
burner firing from a low firing side comprising low firing and either single or multiple stages of medium firing to a high firing side comprising either single or multiple stages of medium firing and high firing; The operating point of the ON operation of the third valve when shifting is closer to the low combustion side than the operating point of the OFF operation of the third valve when shifting the combustion of the burner from the high combustion side to the low combustion side. Or set it closer to the high combustion side,
A third valve ON operation point when shifting the combustion of the burner from the low combustion side to the high combustion side, and a third valve when shifting the combustion of the burner from the high combustion side to the low combustion side It is preferable to set the operating point of the off-operation of the valve at a combustion amount outside the amount of combustion at which smoke or flame extinguishing occurs when the on-operation or off-operation is performed.

A second method for controlling a multi-stage combustion apparatus of the present invention includes:
A method for controlling a staged combustion system comprising a first valve for low firing of the burner and a second valve for high firing of the burner in a fuel supply to the burner, comprising:
Regarding the damper for adjusting the air amount provided in the combustion air supply path to the burner, when switching the burner between low combustion and high combustion, the damper opening at low combustion and the damper opening at high combustion Gradually change the damper opening within a predetermined time between
When the damper opening is gradually changed, when the burner is richer in combustion air than in fuel, the burner is more fuel-rich than in combustion air. The operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion is set closer to low combustion, and the second valve when shifting the combustion of the burner from high combustion to low combustion is characterized by setting the operating point of the off-operation of is set closer to high combustion .

According to the second method of controlling a multi-stage combustion apparatus of the present invention,
As a multi-stage combustion device, a device further comprising one or more third valves for intermediate combustion of single or multiple stages of the burner , provided in the fuel supply path to the burner ,
When the damper opening is gradually changed,
When the burner is richer in combustion air than in fuel, the combustion of the burner is classified as lower combustion, single or multiple stages, than when the burner is rich in fuel than combustion air. The operating point of the ON operation of the third valve when transitioning from the low combustion side including any of medium combustion to the high combustion side including any of single or multiple stages of medium combustion and high combustion is set to the low combustion side, and the operating point of the off operation of the third valve when shifting the combustion of the burner from the high combustion side to the low combustion side is set to the high combustion side.

According to the present invention, the operating point of the ON operation of the second valve when shifting the combustion amount of the burner from low combustion to high combustion can be set to a favorable point where no smoke or flame extinguishment occurs, The operating point for turning off the second valve when shifting the combustion amount of the burner from high combustion to low combustion can also be set to a good point where no smoke or quenching occurs. Both the transition from high combustion to low combustion can be performed well.

FIG. 4 is a diagram illustrating a mode of switching valves in the multi-stage combustion apparatus according to the embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which illustrates the structure of the multistage combustion apparatus of embodiment of this invention. FIG. 3 is a diagram illustrating an aspect of valve switching in a conventional multi-stage combustion device; FIG. 10 is a diagram illustrating a mode of switching valves in a multi-stage combustion apparatus according to another embodiment of the present invention; FIG. 10 is a diagram illustrating a mode of switching valves in a multi-stage combustion apparatus according to still another embodiment of the present invention; FIG. 6 is a diagram illustrating the configuration of a multi-stage combustion device that performs the switching of FIG. 5; FIG. 10 is a diagram illustrating the configuration of a multi-stage combustion apparatus according to still another embodiment of the present invention, which uses liquid fuel; FIG. 10 is a diagram illustrating the configuration of a multi-stage combustion apparatus according to still another embodiment of the present invention, which uses gaseous fuel; FIG. 9 is a diagram illustrating an aspect of valve switching when the air is rich in the multi-stage combustion apparatus shown in FIGS. 7 and 8; FIG. 9 is a diagram illustrating an aspect of valve switching when the fuel is rich in the multi-stage combustion apparatus shown in FIGS. 7 and 8;

FIG. 2 illustrates the configuration of the multi-stage combustion device according to the embodiment of the invention. 11 is a boiler provided with the burner 12 here. A fuel supply line 13 from a fuel pump and a combustion air supply line 14 are connected to the burner 12 . The fuel supply line 13 is bifurcated before the burner 12, one of which forms a fuel supply line 15 for low combustion and the other forms a fuel supply line 16 for high combustion. A low combustion fuel supply line 15 is provided with a low combustion valve 17 , and a high combustion fuel supply line 16 is provided with a high combustion valve 18 . A safety valve 19 is provided at a portion of the fuel supply line 13 upstream of the branched portion. The combustion air supply line 14 is provided with a blower 20 for blowing air and an air damper 21 for adjusting the amount of air. A control device 22 is connected to a detection signal line 23 for the temperature and pressure of steam generated in the boiler 11, and a signal/control line 24 between the valves 17, 18, 19 and the air damper 21. It is connected.

As shown in FIG. 1, the air damper 21 includes a damper shaft or a motor shaft or the like 26 interlocked with the damper shaft (hereinafter, the damper shaft or the motor shaft or the like interlocked with the damper shaft may be abbreviated as "damper shaft or the like"). is provided, and the rotation angle of the damper shaft or the like 26 corresponds to the opening degree of the damper 21 . A plurality of arbitrary number (i) of cams 27(1), 27(2), . ing. Detection switches 28(1), 28(2), . 28(i-1) and 28(i) are provided respectively.

The graph shown in FIG. 1 represents the relationship between the opening degree of the air damper 21, that is, the rotation angle of the damper shaft 26, and the load factor of the boiler 11, that is, the combustion amount of the burner 12. FIG. The angle of the damper shaft or the like 26 can be changed in the range of 0 degrees to 90 degrees . configured to be the largest. The air damper 21 having the characteristics shown in FIG. 1 can arbitrarily set the angle of the damper shaft and the like 26 at low combustion opening, that is, at low combustion (for example, 10 degrees). In addition, the angle of the damper shaft and the like 26 at high combustion opening, ie, high combustion, can be arbitrarily set (for example, 80 degrees).

As shown in FIG. 1, the degree of opening of the air damper 21 and the amount of combustion of the burner 12, that is, its load factor, correspond one-to-one.

When the opening of air damper 21 is "low combustion opening", cam 27(1) operates detection switch 28(1), thereby detecting the opening of air damper 21. FIG. Similarly, when the opening of the air damper 21 is "high combustion opening", the cam 27(i) operates the detection switch 28(i), whereby the opening of the air damper 21 is detected.

In the graph of FIG. 1, there is a smoke/extinguishing generation zone 30 . This smoke/extinguishing generation zone 30 exists in a certain range of opening degree between low combustion opening and high combustion opening, that is, in a certain range of load factor between low combustion and high combustion. do. If switching from low combustion to high combustion or from high combustion to low combustion is performed in this zone 30, the combustion state deteriorates, and the possibility of smoke emission and flame extinction in the burner 12 increases.

Therefore, as shown in FIG. 1, at the time of switching from low combustion to high combustion, or from high combustion to low combustion, the smoke/extinguishing zone 30 when the damper shaft or the like 26 is rotating is At the avoidable timing, switching between low combustion and high combustion is performed. During low combustion, the low combustion valve 17 is turned on and the high combustion valve 18 is turned off. On the other hand, during high combustion, both the low combustion valve 17 and the high combustion valve 18 are turned on. Specifically, when switching from low combustion to high combustion, the switching operating point is set before the smoke/flame generation zone 30 when the opening of the air damper 21 increases, and the cam 27 (2) is activated. The timing is sensed when the detector switch 28(2) is actuated, which causes the controller 22 of FIG. 2 to turn on the high burn valve 18. FIG. By doing so, it is possible to switch from low combustion to high combustion without causing smoke or flame extinction. Similarly, when switching from high combustion to low combustion, the switching operating point is set before the smoke/flame generation zone 30 when the opening degree of the air damper 21 is reduced, and the cam 27 (i-1) is set. actuates detection switch 28(i-1), which causes controller 22 of FIG. 2 to turn off valve 18 for high burn.

Although there are counterexamples to be described later, in general, the operating point for switching from high combustion to low combustion is set to a higher combustion side than the smoke/extinguishing zone 30, and then similarly low combustion to high combustion is set. The operating point for switching to combustion is also set to the higher combustion side than the smoke/extinguishing zone 30, or conversely, the operating point for switching from low combustion to high combustion is set to the lower combustion side than the smoke/extinguishing zone 30. If, after setting, the operating point for switching from high combustion to low combustion is also set to the lower combustion side than the smoke/extinguishing zone 30, the operating points will shift too much, and good switching will not be possible. Can not. Therefore, both switching from low combustion to high combustion and switching from high combustion to low combustion are satisfactorily performed at one operating point deviating from the smoke/extinguishing zone 30 to the low combustion side or the high combustion side. It is difficult and impractical to do

FIG. 3 shows an example of switching modes of conventional valves. In the case of FIG. 3 , switching from low combustion to high combustion and switching from high combustion to low combustion are performed at only one operating point in the smoke/extinguishing zone 30 . Therefore, both switching from low combustion to high combustion and switching from high combustion to low combustion are likely to cause smoke and flame extinction at the time of switching, and it is difficult to perform good switching. .

FIG. 4 shows a mode of valve switching in another embodiment of the present invention. Here, it is assumed that the rotational speed of the damper shaft 26 of the air damper 21 is a known speed such as a constant value. In that case, for example, if the damper shaft 26 starts rotating from when the opening of the air damper 21 is "low combustion opening" to "high combustion opening", the cam 27 (1 ) actuates detect switch 28(1). At this time, if the rotational speed of the damper shaft etc. 26 is known as described above, after the cam 27(1) actuates the detection switch 28(1), the rotational angle of the damper shaft etc. 26 changes from low combustion to low combustion. The timing for switching to high combustion, that is, the time required to reach the operating point for switching, can be known in advance. Therefore, the control device 22 shown in FIG. 2 determines that the point in time when this time has elapsed is the operating point, and switches from low combustion to high combustion at that time.

Similarly, switching from high combustion to low combustion can be performed. That is, when the damper shaft 26 starts to rotate so that the opening of the air damper 21 changes from the "high combustion opening" to the "low combustion opening", the cam 27(2) switches to the detection switch 28(2). is detected by activating , and the time from the time of detection until the rotational angle of the damper shaft 26 reaches the timing of switching from high combustion to low combustion, that is, the switching operating point, is known in advance. , it is possible to switch from high to low combustion at a desired operating point.

Thus, switching from low combustion to high combustion and switching from high combustion to low combustion by the method shown in FIG. , cams 27(1), . . . , 27(i) and detection switches 28(1), . In some cases, one of switching from low combustion to high combustion and switching from high combustion to low combustion is performed by the method shown in FIG. It can also be done in other ways.

FIG. 6 shows the configuration of a multi-stage combustion device according to still another embodiment of the present invention. Here, in addition to the low-combustion valve 17 of the low-combustion fuel supply line 15 and the high-combustion valve 18 of the high-combustion fuel supply line 16, a medium-combustion fuel supply line 31 and a A medium combustion valve 32 is provided. Other configurations are the same as those of the apparatus in FIG.

FIG. 5 shows how the valves 17, 18, and 32 are switched in the multi-stage combustion apparatus of FIG. The mode of switching shown in FIG. 5 is a development of the mode of switching shown in FIG. That is, in FIG. 5, regarding the opening degree of the air damper 21, one or more stages of "middle combustion opening" are set between the above-described "low combustion opening" and "high combustion opening". , which burns in three or more stages. In the specific example shown in FIG. 5, it is assumed that combustion is performed in three stages, and that the intermediate combustion opening is adjusted to the amount of combustion corresponding to the load factor of 65% in the burner 12 of FIG. It is assumed that the middle combustion opening of the air damper 21 is adjusted to 45 degrees by the rotation angle of the damper shaft and the like 26 . In FIG. 5, the low combustion opening and the high combustion opening are the same as those shown in FIGS.

Even in the embodiment shown in FIG. 5, there is a smoke/extinguishing zone. Specifically, there is a first smoke/extinguishing zone 30A between the low combustion opening and the medium combustion opening, and a second smoke/extinguishing zone 30A between the medium combustion opening and the high combustion opening. There is a generation zone 30B. A cam 27 (2, . A detection switch 28 (2, . . . , i-1) is provided which is actuated by i-1). The reference numerals for the cams and detection switches described above are for a general case where the middle combustion opening is in multiple stages. On the other hand, in the specific embodiment shown in FIG. 5, the intermediate combustion opening is one step, so i=3 in the above reference.

Also in the embodiment shown in FIG. 5, similarly to the embodiment shown in FIG. After a predetermined set time has passed since the damper shaft 26 started rotating, the low combustion is switched to the medium combustion at an operating point outside the first smoke/flame generation zone 30A. The same applies to switching from medium combustion to low combustion, switching from medium combustion to high combustion, and switching from high combustion to medium combustion.

Here, during low combustion, the low combustion valve 17 is on, and the intermediate combustion valve 32 and the high combustion valve 18 are off. During medium combustion, the low combustion valve 17 and the medium combustion valve 32 are on, and the high combustion valve 18 is off. During high combustion, the low combustion valve 17, the intermediate combustion valve 32, and the high combustion valve 18 are all on. Alternatively, instead of such control, only the low combustion valve 17 is turned on during low combustion, only the intermediate combustion valve 32 is turned on during medium combustion, and only the high combustion valve 18 is turned on during high combustion. Controls, other on/off controls, etc. may also be employed.

The relationship between the combustion in the burner 12 and the smoke/flame extinguishing zones 30, 30A, 30B will be described in detail. In the burner 12, the internal pressure is lower during low combustion than during high combustion. Therefore, during low combustion, the pressure of the air sent from the combustion air supply line 14 to the burner is higher than the internal pressure of the burner 12, and the difference between the two is relatively large. Therefore, when switching from low combustion to high combustion, if fuel is not quickly supplied to the burner 12, there is a risk of flame extinction. Therefore, as shown in FIG. 1 and the like, when switching from low combustion to high combustion, switching is performed at an operating point on the lower combustion side than the smoke/flame extinction zone 30, thereby increasing the amount of fuel at an early stage and extinguishing the flame. preventing it from occurring.

Also, the pressure inside the burner 12 is higher during high combustion than during low combustion. Therefore, the difference between the pressure of the air sent to the burner from the combustion air supply line 14 and the internal pressure of the burner 12 becomes small. Therefore, when switching from high combustion to low combustion, if the amount of fuel supplied to the burner 12 is not reduced early, there is a risk of excessive fuel and smoke. Therefore, as shown in FIG. 1 and the like, when switching from high combustion to low combustion, switching is performed at an operating point on the higher combustion side than the smoke/flame extinguishing zone 30, thereby reducing the amount of fuel at an early stage and reducing smoke emission. preventing it from occurring.

In some cases, the difference between the pressure of the air sent from the combustion air supply line 14 to the burner and the internal pressure of the burner 12 may become relatively small during low combustion. At that time, it may be more convenient to switch from low combustion to high combustion at an operating point on the high combustion side of the smoke/flame extinguishing zone 30 . Conversely, during high combustion, the difference between the pressure of the air sent from the combustion air supply line 14 to the burner and the internal pressure of the burner 12 may become relatively large. at an operating point on the lower combustion side of the smoke-extinguishing zone 30.

As described above, FIG. 5 and FIG. 6 illustrate the case of three-stage combustion, but multi-stage combustion of four or more stages can also be carried out in the same manner.

FIG. 7 shows the configuration of an apparatus in which liquid fuel is used as the fuel and the burner 12 performs four-stage combustion. A fuel pump 33 is provided in the fuel supply line 13 . The burner 12 is provided with four nozzles 34 for injecting a mixed fluid of fuel and air, four fuel supply lines 35 corresponding to each nozzle 34, and a valve 36 provided in each fuel supply line 35. It is 37 is an air chamber in the burner 12 . Other configurations are the same as those shown in FIG. 2 and the like. The number of nozzles 34 may be singular instead of being plural as described above.

FIG. 8 shows the configuration of an apparatus in which gaseous fuel is used as fuel and burner 12 performs four-stage combustion. A safety valve 19 is provided in the fuel supply line 13 . In this FIG. 8 device, the nozzle 34 is singular. Other configurations are similar to the device shown in FIG.

FIG. 9 shows an example of the operation of the valves (No. 1-No. 4) 36 when the combustion air is richer than the fuel in the system shown in FIG. 7 or FIG. In the figure, the solid line shows how the operating point changes when switching from the low combustion side to the high combustion side, and the dashed line shows how the operating point changes when switching from the high combustion side to the low combustion side. It is a line showing the state of change. No. for low combustion. 1 shows that the low combustion operating point is also the ignition and shutdown operating point. These operating points are similar to those shown in FIG. is set on the lower combustion side than the operating point of

FIG. 10 shows an example of operation of the valves (No. 1 to No. 4) 36 in the system shown in FIG. 7 or 8 when the fuel is richer than the combustion air. As in the case of FIG. 9, the solid line shows how the operating point changes when switching from the low combustion side to the high combustion side, and the dashed line shows the switching from the high combustion side to the low combustion side. It is a line showing how the operating point changes. In FIG. 10, contrary to the case of FIG. 9, the operating point for switching from the low combustion side to the high combustion side is the operating point for switching from the high combustion side to the low combustion side. It is set on the higher combustion side than Since the fuel is rich, an appropriate amount of fuel can be burned by turning on the valve 36 on the high combustion side compared to the case of FIG. Also, compared to the case of FIG. 9, the valve 36 is turned off on the low combustion side.

Claims (8)

a first valve for low combustion of the burner and a second valve for high combustion of the burner provided in the fuel supply to the burner;
a damper for adjusting the amount of air provided in the combustion air supply path to the burner;
A control device for controlling the opening of the damper and the on/off of at least the second valve for switching between low combustion and high combustion of the burner,
The control device controls to gradually change the damper opening between the damper opening during low combustion and the damper opening during high combustion when the burner is switched between low combustion and high combustion. and the control device is
The operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion when the damper opening is gradually changed is changed from high combustion to low combustion. is set to a lower combustion side or a higher combustion side than the operating point of the off operation of the second valve when the
The operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion, and the OFF operation of the second valve when shifting the combustion of the burner from high combustion to low combustion. A multi-stage combustion apparatus characterized in that the operating point is set at a combustion amount that deviates from the combustion amount at which smoke or flame extinguishment occurs when ON operation or OFF operation is performed. further comprising one or more third valves for medium combustion of one or more stages of the burner, provided in the fuel supply to the burner;
The controller is
burner firing from a low firing side comprising low firing and either single or multiple stages of medium firing to a high firing side comprising either single or multiple stages of medium firing and high firing; The operating point of the ON operation of the third valve when shifting is closer to the lower combustion side than the operating point of the OFF operation of the third valve when shifting the combustion of the burner from the high combustion side to the low combustion side, or Along with setting toward the high combustion side,
an operating point at which the third valve is turned on when the combustion of the burner is shifted from the low combustion side to the high combustion side; 3. The operating point of the off-operation of the valve of 3 is set at a combustion amount that deviates from the combustion amount at which smoke or flame extinguishing occurs when the on-operation or off-operation is performed . Item 1. The multi-stage combustion apparatus according to item 1 . a first valve for low combustion of the burner and a second valve for high combustion of the burner provided in the fuel supply to the burner;
a damper for adjusting the amount of air provided in the combustion air supply path to the burner;
A control device for controlling the opening of the damper and the on/off of at least the second valve for switching between low combustion and high combustion of the burner,
The control device controls to gradually change the damper opening between the damper opening during low combustion and the damper opening during high combustion when the burner is switched between low combustion and high combustion. and furthermore
The controller controls the combustion of the burner from low combustion to high combustion when the burner is rich in combustion air relative to fuel compared to when the burner is rich in fuel than combustion air. set the operating point of the ON operation of the second valve when shifting to low combustion, and set the operating point of the OFF operation of the second valve when shifting the combustion of the burner from high combustion to low combustion. A multi-stage combustion device characterized in that it is set closer to combustion . further comprising one or more third valves for medium combustion of one or more stages of the burner, provided in the fuel supply to the burner;
The controller classifies burner combustion as low combustion when the burner is richer in combustion air than in fuel than when the burner is richer in fuel than combustion air. Turning on the third valve when transitioning from a low fire side including either a stage or multiple stages of medium combustion to a high fire side including either a single stage or multiple stages of medium combustion and high combustion The operating point of the operation is set closer to the low combustion side, and the operating point of the off operation of the third valve when shifting the combustion of the burner from the high combustion side to the low combustion side is set closer to the high combustion side. 4. The multi-stage combustion system according to claim 3 , wherein: A method for controlling a staged combustion system comprising a first valve for low firing of the burner and a second valve for high firing of the burner in a fuel supply to the burner, comprising:
Regarding the damper for adjusting the air amount provided in the combustion air supply path to the burner, when switching the burner between low combustion and high combustion, the damper opening at low combustion and the damper opening at high combustion Gradually change the damper opening within a predetermined time between
When the damper opening is gradually changed,
The operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion, and the operating point of the OFF operation of the second valve when shifting the combustion of the burner from high combustion to low combustion. , the operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion, and the combustion of the burner from high combustion to low combustion. The operating point for turning off the second valve when transitioning to combustion is set at a combustion amount that deviates from the amount of combustion at which smoke or flame extinguishing occurs when the on or off operation is performed. A control method for a multi-stage combustion device characterized by : As a multi-stage combustion device, a device further comprising one or more third valves for intermediate combustion of single or multiple stages of the burner, provided in the fuel supply path to the burner,
When the damper opening is gradually changed,
burner firing from a low firing side comprising low firing and either single or multiple stages of medium firing to a high firing side comprising either single or multiple stages of medium firing and high firing; The operating point of the ON operation of the third valve when shifting is closer to the low combustion side than the operating point of the OFF operation of the third valve when shifting the combustion of the burner from the high combustion side to the low combustion side. Or set it closer to the high combustion side,
A third valve ON operation point when shifting the combustion of the burner from the low combustion side to the high combustion side, and a third valve when shifting the combustion of the burner from the high combustion side to the low combustion side 6. The operating point of the off-operation of the valve is set at a combustion amount that deviates from the combustion amount at which smoke or flame extinguishing occurs when the on-operation or off-operation is performed. A control method for a multi-stage combustion device. A method for controlling a staged combustion system comprising a first valve for low firing of the burner and a second valve for high firing of the burner in a fuel supply to the burner, comprising:
Regarding the damper for adjusting the air amount provided in the combustion air supply path to the burner, when switching the burner between low combustion and high combustion, the damper opening at low combustion and the damper opening at high combustion Gradually change the damper opening within a predetermined time between
When the damper opening is gradually changed, when the burner is richer in combustion air than in fuel, the burner is more fuel-rich than in combustion air. The operating point of the ON operation of the second valve when shifting the combustion of the burner from low combustion to high combustion is set closer to low combustion, and the second valve when shifting the combustion of the burner from high combustion to low combustion A control method for a multi-stage combustion device, characterized in that the operating point of the OFF operation of is set closer to high combustion . As a multi-stage combustion device, a device further comprising one or more third valves for intermediate combustion of single or multiple stages of the burner, provided in the fuel supply path to the burner,
When the damper opening is gradually changed,
When the burner is richer in combustion air than in fuel, the combustion of the burner is classified as lower combustion, single or multiple stages, than when the burner is rich in fuel than combustion air. The operating point of the ON operation of the third valve when transitioning from the low combustion side including any of medium combustion to the high combustion side including any of single or multiple stages of medium combustion and high combustion is set to the low combustion side, and the operating point of the off operation of the third valve when shifting the combustion of the burner from the high combustion side to the low combustion side is set to the high combustion side 8. A control method for a multi-stage combustion device according to Item 7.

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