JP2018151097A - Burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burner with a high turndown ratio capable of forming stable flames with a relatively simple structure.SOLUTION: A burner is configured such that a throat 5 having a truncated conical-shaped trunk is connected to a tip opening part of a burner body 2, and a flame holding plate 10 whose diameter is substantially identical to an inner diameter of the burner body 2, and a fuel injection nozzle 8 are provided so as to freely advance/retreat integrally in a longitudinal direction of the burner body 2. Also, the burner includes: a static pressure sensor 20 configured to detect a static pressure in the burner body; and a static pressure/flame holding plate adjustment controller 21 configured to make the flame holding plate 10 advance/retreat so that a detected static pressure value is kept into a predetermined value, to thereby adjust an interval between an inner peripheral wall of a throat trunk part 5a and a flame holding plate outer edge part 10a as a flow passage for secondary air.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure spray burner for liquid fuel, and more particularly to a burner used for an aggregate heating dryer or the like in an asphalt plant.

  In recent years, when producing asphalt mixture, from the viewpoint of effective use of resources, asphalt pavement waste material (hereinafter referred to as "waste material") generated by road construction etc. is mixed with a new aggregate at a predetermined rate. In many cases, the mixing ratio is as high as about 70 to 80%. When producing an asphalt mixture in which waste materials are mixed in a high proportion as described above, the amount of new aggregates in the asphalt mixture is relatively reduced, and the burner burn amount of the new aggregate heating dryer is accordingly The burner of the new aggregate heating dryer has a large turndown ratio (the ratio of the minimum combustion amount to the maximum combustion amount) because it is necessary to significantly reduce the amount of combustion during normal operation without mixing waste materials. Things (for example, about 1: 8) are often required.

  However, in such a burner with a high turndown ratio, if the combustion is performed near the minimum combustion amount, the amount of combustion air will be extremely less than normal, resulting in a decrease in the flow velocity of the combustion air. Depending on the situation, there is a concern that the fuel oil and the combustion air cannot be sufficiently agitated and mixed, making it difficult to form a stable flame.

  On the other hand, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 9-310813) and Patent Document 2 (Japanese Patent Laid-Open No. 2009-41816), an annular secondary air flow has a double cylinder structure. This burner is provided with a flow rate adjusting damper for adjusting the amount of secondary air passing therethrough, and the flow rate adjusting damper is controlled to open and close according to the burner combustion amount. Has been. According to the burner, even at the time of low combustion where the amount of combustion air decreases, the flow rate of combustion air (primary air) passing around the fuel injection nozzle is suppressed by restricting the secondary air flow path. Therefore, a stable flame can be formed without degrading the stirring and mixing performance of the fuel oil and the combustion air.

Japanese Patent Laid-Open No. 9-310813 JP 2009-41816 A

  However, in the conventional burner, since the secondary air flow path has an annular structure, a plurality of flow rate adjusting dampers for opening and closing the flow path are arranged at predetermined intervals along the annular flow path. In addition, each damper is connected by, for example, a link mechanism, and the opening and closing control is performed while synchronizing each damper, which is somewhat complicated in structure and somewhat disadvantageous in terms of manufacturing cost and maintenance. It has become.

  An object of the present invention is to provide a burner having a high turn-down ratio capable of forming a stable flame with a relatively simple configuration in view of the above points.

  In the burner according to the first aspect of the present invention, the small-diameter side of the throat having a hollow and substantially truncated cone-shaped body is connected to the tip opening of the single-cylinder burner body, and the inner diameter of the burner body An annular flame holding plate having substantially the same diameter and a fuel injection nozzle located behind the flame holding plate are provided so as to be integrally movable along the longitudinal direction of the burner body, and static pressure in the burner body is provided. A flow path for secondary air by providing a static pressure sensor for detection, and advancing and retracting the flame holding plate within the range of the throat body so that the static pressure value detected by the static pressure sensor is maintained at a predetermined value; And a static pressure / flame holding plate adjustment controller that adjusts the gap distance between the outer edge of the flame holding plate and the inner peripheral wall of the throat barrel.

  In the burner according to claim 2, a predetermined static pressure value that enables at least stable combustion is set in the static pressure / flame holding plate adjustment controller, and the static pressure value detected by the static pressure sensor is The flame holding plate is advanced and retracted so as to be maintained at the predetermined static pressure value when the value falls below a predetermined static pressure value, and the gap interval between the outer edge portion of the flame holding plate and the inner peripheral wall of the throat body is adjusted.

  In the burner according to claim 3, a flow rate sensor for detecting a flow rate of a fuel supply pipe for supplying fuel to the fuel injection nozzle, and an air volume sensor for detecting an air flow rate of a blower for supplying combustion air to the burner body. And an air flow rate adjusting means for adjusting the air flow rate of the blower, a set air flow rate corresponding to a predetermined air ratio with respect to a fuel supply amount detected by the flow rate sensor, and an actual air flow rate detected by the air flow rate sensor. And a fuel / air flow rate adjustment controller that adjusts the air flow rate of the blower through the air flow rate adjusting means based on the difference value amount.

  According to the burner of the first aspect of the present invention, the small-diameter side of the throat having a substantially frustoconical body is connected to the tip opening of the burner body, and has the same diameter as the inner diameter of the burner body. A flame holding plate and a fuel injection nozzle are provided so as to be integrally movable along the longitudinal direction of the burner body, and a static pressure sensor for detecting the static pressure in the burner body is provided, which is detected by the static pressure sensor. The static pressure / maintenance is adjusted by moving the flame holding plate forward and backward so as to maintain the static pressure value to be maintained at a predetermined value, thereby adjusting the clearance between the outer edge of the flame holding plate and the inner peripheral wall of the throat body, which is a flow path for secondary air. Since the flame plate adjustment controller is provided, even in the low combustion area where the amount of combustion air is reduced, the flame holding plate is advanced and retracted to narrow the flow path of the secondary air on the flame holding plate outer edge side, and within the burner body By maintaining the static pressure value at a predetermined value, the area around the fuel injection nozzle is Also the injection flow rate of the combustion air is injected spent kept substantially constant, thus enabling stable flame formed with a relatively simple configuration.

  According to the burner of claim 2, the static pressure / flame holding plate adjustment controller is set with a predetermined static pressure value that enables at least stable combustion, and the static pressure value detected by the static pressure sensor. Is less than the predetermined static pressure value, the flame holding plate is advanced and retracted to adjust the gap interval between the flame holding plate outer edge and the inner peripheral wall of the throat body so that the predetermined static pressure value is maintained. As the pressure value, for example, if the static pressure value at the time of combustion near the minimum level where stable flame formation is possible without restricting the flow path of the secondary air on the outer edge side of the flame holding plate, flame formation The flame holding plate can be advanced and retracted only within the low combustion region where it becomes unstable, which makes it possible to make more effective use of the adjustment margin for the flame holding plate to advance and retreat, making fine adjustment possible and stable. Flame formation is possible.

  According to the burner of claim 3, the flow rate sensor for detecting the flow rate of the fuel supply pipe for supplying the fuel to the fuel injection nozzle, and the detection amount of the blower for supplying the combustion air to the burner body. An air volume sensor, an air volume adjusting means for adjusting the air volume of the blower, and a set air volume corresponding to a predetermined air ratio with respect to a fuel supply amount detected by the flow sensor, and an actual air volume detected by the air volume sensor. Since it has a fuel / air flow rate adjustment controller that adjusts the air flow rate of the blower based on the amount of difference from the air flow rate, the gap between the flame holding plate outer edge and the throat barrel inner peripheral wall is adjusted to narrow. Even if the air flow that is actually supplied is less than the predetermined air ratio with respect to the fuel supply amount, the increase in air resistance accompanying The lack of phase And you can adjust the blowing rate of the successive blower to compensate for the amount of air thus enabling stable flame formation.

It is a schematic explanatory drawing which shows one Example of the burner which concerns on this invention. It is sectional drawing which shows the position of the flame-holding board at the time of the maximum combustion amount. It is sectional drawing which shows the position of the flame-holding board at the time of the minimum combustion amount.

  In the burner according to the present invention, a burner body having a single cylinder structure and a blower for supplying combustion air are connected by a blower duct. The small-diameter portion of the throat having a hollow and substantially truncated cone-shaped body is connected to the tip opening of the burner body so as to have a tapered structure in which the inner diameter gradually expands. Also, a fuel flame that is substantially the same diameter as the inner diameter of the burner body and an annular flame holding plate, and is disposed at a predetermined interval behind the flame holding plate (on the burner body side) and injects liquid fuel such as A heavy oil. An injection nozzle is provided so as to be integrally movable along the longitudinal direction of the burner body.

  An appropriate means can be adopted as the advancing / retreating means for advancing and retracting the flame holding plate and the fuel injection nozzle integrally. For example, a hollow rod member incorporating a fuel supply pipe and a return pipe is used as the burner body. And a drive motor such as a stepping motor that moves the rod member forward and backward on the base end side while attaching the fuel injection nozzle and the flame holding plate to the tip end portion of the rod member. The thing etc. which were done can be employ | adopted suitably.

  Further, a static pressure sensor for detecting the static pressure in the burner body, and the flame holding plate within the range of the throat barrel so that the static pressure value detected by the static pressure sensor is maintained at a predetermined value. A static pressure / flame holding plate adjustment controller is provided that adjusts the clearance between the outer edge of the flame holding plate, which is a flow path for secondary air, and the inner peripheral wall of the throat barrel, by moving forward and backward.

  The length of the throat barrel relative to the total length of the throat may be determined as appropriate. For example, if the throat barrel is formed to have a longer length, the outer peripheral edge of the flame holding plate and the inner wall of the throat barrel having a tapered structure As a result, it is possible to secure a large margin for adjusting the gap interval between the two and fine adjustment.

  Preferably, a predetermined static pressure value that enables at least stable combustion is set in advance in the static pressure / flame holding plate adjustment controller, and the static pressure value detected by the static pressure sensor is the predetermined static pressure. If the value is less than the value, the flame holding plate may be advanced and retracted so as to be maintained at the predetermined static pressure value, and the clearance between the outer edge of the flame holding plate and the inner peripheral wall of the throat body may be adjusted. By adopting such control, if the static pressure value at the minimum combustion amount at which stable flame formation is possible, for example, is set as the predetermined static pressure value, high combustion capable of sufficiently stable flame formation is set. While the flame holding plate does not advance or retreat from the region to the vicinity of the intermediate combustion region, the flame holding plate advances and retracts only within the low combustion region where the flame formation becomes unstable. This makes it possible to make fine adjustments by making effective use of the advancement and retraction adjustments.

  Preferably, a flow rate sensor for detecting a flow rate of a fuel supply pipe for supplying fuel to the fuel injection nozzle, a flow rate sensor for detecting a flow rate of the blower, and an air flow rate of the blower, for example, an inverter type The difference between the air flow rate adjusting means such as the air blower and the set air flow rate corresponding to a predetermined air ratio with respect to the fuel supply amount detected by the flow rate sensor and the actual air flow rate detected by the air flow sensor A fuel / air flow rate adjustment controller that adjusts the air flow rate of the blower via the air flow rate adjusting means may be provided.

  If it does in this way, from the increase in air resistance accompanying adjustment to the direction where the clearance gap between a flame-holding board outer edge part and a throat body part inner peripheral wall narrows, it cannot blow to a burner main part according to a set air volume with a blower. Even when the amount of air supplied is less than the predetermined air ratio, the amount of air blown from the blower can be corrected sequentially so that the air amount corresponding to the shortage can be compensated, and stable flame formation becomes possible. .

  When the burner having the above-described configuration is operated, first, a predetermined static pressure value (for example, a static pressure value at the maximum combustion amount) is set in the static pressure / flame holding plate adjustment controller. And, for example, when the burner combustion amount is lowered from the high to intermediate combustion region to the low combustion region, the static pressure in the burner main body is lowered along with the blown amount from the blower accordingly, but when the static pressure sensor detects that, Retract the flame holder. Since the inner diameter of the throat barrel is tapered so that the diameter gradually decreases toward the rear (burner body side), the clearance between the outer edge of the flame holding plate and the inner peripheral wall of the throat barrel gradually increases as the flame holding plate moves backward. Then, the static pressure increases and is maintained at the predetermined value set in advance.

  As a result, even in the vicinity of the minimum combustion amount where the amount of combustion air is extremely reduced, the injection flow rate of the combustion air injected from the burner body can be maintained at the same level as at the time of high to intermediate combustion, A stable flame can be formed without deteriorating the stirring and mixing properties with the combustion air.

  Thus, while connecting the small diameter portion side of the throat having a hollow and substantially frustoconical body portion to the tip opening of the burner body, the flame holding plate having the same diameter as the inner diameter of the burner body is connected to the throat body portion. The flame holding plate is advanced and retracted so that the static pressure value in the burner body is maintained substantially constant, and the clearance between the outer edge of the flame holding plate and the inner peripheral wall of the throat barrel is adjusted. Even when burned in a low combustion area, the combustion air injection flow rate from the burner body is kept substantially constant, even with a high turndown ratio burner. A stable combustion state can be maintained from the combustion region to the minimum combustion region.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  Reference numeral 1 in the figure denotes a burner having a high turndown ratio according to the present invention installed in an aggregate heating dryer of an asphalt plant, for example, a burner body 2 having a single cylinder structure and a blower 3 for supplying combustion air. Are connected by a blower duct 4. A small-diameter portion side of a throat 5 having a hollow and substantially frustoconical trunk portion 5a is connected to the tip opening of the burner body 2 so as to have a tapered structure in which the inner diameter gradually expands. A hollow rod member 6 containing a fuel supply pipe and a return pipe (not shown) is inserted through the substantially central portion (cylindrical shaft core portion) of the burner body 2. It is sandwiched by a plurality of guide rollers 7 from above and below, and is supported so as to be able to advance and retreat along the longitudinal direction of the burner body 2 as indicated by the thick arrows in FIG.

  A fuel injection nozzle 8 is disposed at the front end of the rod member 6 and is disposed at a predetermined interval in front of the fuel injection nozzle 8 via a mounting bracket 9. The rod member 6 has an annular shape substantially the same as the inner diameter of the burner body 2. The flame holding plate 10 is fixed. The interval between the fuel injection nozzle 8 and the flame holding plate 10 may be appropriately determined so that an appropriate flame shape is formed through a combustion test or the like while considering an oil spray angle or the like.

  On the other hand, the fuel supply pipe 12 and the fuel are connected to the rod base end part 11 which penetrates the rear end part of the burner body 2 and protrudes rearward so as to be connected to the fuel supply pipe and the return pipe in the rod member 6, respectively. An advancing / retreating means 14 is provided for connecting the return pipe 13 and advancing / retreating the rod member 6 along the longitudinal direction of the burner body 2.

  The advancing / retreating means 14 may adopt an appropriate configuration. For example, as shown in FIG. 1, a support body 15 extending rearward from the rear end portion of the burner body 2 and a shaft support parallel to the support body 15 are supported. A screw shaft 16 and a stepping motor 17 that rotationally drives the screw shaft 16 can be suitably employed. Reference numeral 18 in the figure denotes a connecting piece for connecting the rod base end portion 11 and the screw shaft 16, and a groove portion (threaded with the screw groove of the screw shaft 16) is formed on the connecting portion inner surface side of the connecting piece 18. The rod member 6 is moved to a predetermined position along the longitudinal direction of the burner body 2 through the connecting piece 18 by rotating the screw shaft 16 forward and backward by the stepping motor 17. It is possible to advance and retreat.

  Reference numeral 19 in the figure denotes an airtight state for preventing high-pressure combustion air from being blown out of the burner body 2 from a clearance of a through hole (not shown) at the base end portion of the burner body 2 through which the rod member 6 passes. In the present embodiment, the sealing member has a bellows structure that can be expanded and contracted, for example, so as not to hinder the forward and backward movement of the rod member 6.

  In the figure, 20 is a static pressure sensor for detecting the static pressure in the burner body 2, 21 is a static pressure / flame holding plate adjustment controller 21, and the static pressure / flame holding plate adjustment controller 21 includes the static pressure sensor. The static pressure value detected at 20 is sequentially taken in, and the rod is passed through the advancing / retreating means 14 so that the acquired static pressure value is maintained at a predetermined value, for example, a static pressure value at the maximum combustion amount (for example, about 300 mmAq). The flame holding plate 10 at the tip of the member 6 is advanced and retracted within the range of the throat barrel 5a to adjust the gap A between the flame holding plate outer edge 10a and the inner peripheral wall of the throat barrel 5a, which are secondary air flow paths. Like to do.

  A predetermined static pressure value that enables at least stable combustion is set in advance in the static pressure / flame holding plate adjustment controller 21, and the static pressure value detected by the static pressure sensor 20 is the predetermined static pressure value. The flame holding plate 10 is advanced and retracted so as to return to and maintain the predetermined static pressure value, and the gap between the flame holding plate outer edge 10a and the inner peripheral wall of the throat barrel 5a, which is a flow path for secondary air. It is also possible to control to adjust the A interval. By adopting the control, it is possible to form a stable flame without reducing the flow path of the secondary air on the flame holding plate outer edge portion 10a side, which is found through, for example, a combustion test as the predetermined static pressure value. If a static pressure value (for example, about 200 mmAq) at the amount of combustion near the minimum limit is set, the flame holding plate 10 advances and retreats from the high combustion region capable of sufficiently stable flame formation to the vicinity of the intermediate combustion region. While the operation is not performed, the flame holding plate 10 is moved back and forth only within the range of the low combustion region where the flame formation becomes unstable, and the adjustment margin of the flame holding plate 10 is utilized more effectively. Adjustment is possible.

  Further, the fuel supply pipe 12 for supplying fuel oil such as A heavy oil or kerosene to the rod member 6 has a fuel supply pump 22 and a flow sensor 23 interposed therebetween, and the other end is connected to the fuel tank 24. On the other hand, the fuel return pipe 13 provided is connected to the fuel supply pipe 12 on the upstream side of the fuel supply pump 22 with a flow rate adjustment valve 25 interposed in the middle, and the flow rate adjustment is performed by a control motor 26. By adjusting the opening amount of the valve 25 and adjusting the return amount of the fuel oil, only the injection amount can be adjusted without significantly changing the injection speed of the fuel oil from the fuel injection nozzle 8 at the tip of the rod member 6. Yes.

  Further, an intake pipe 28 having a substantially straight pipe structure is connected to the intake port 27 of the blower 3, and an air quantity sensor 29 for detecting an air quantity is provided in the middle of the intake pipe 28, and a drive motor 30 of the blower 3 is provided. Is provided with an inverter 31 for controlling the rotational speed, which is an air flow adjusting means, and by adjusting the rotational speed of the drive motor 30 with the inverter 31, the burner combustion amount without requiring an air flow adjusting damper or the like. It is possible to supply the burner main body 2 with an air volume suitable for the above.

  In the figure, 32 is a fuel / air flow rate adjustment controller. The fuel / air flow rate adjustment controller 32 adjusts the flow rate adjusting valve 25 and sequentially takes in the fuel supply amount detected by the flow rate sensor 23. Then, a set air flow rate corresponding to a predetermined air ratio (for example, about 1.2) set in advance with respect to the taken fuel supply amount is calculated, and the calculated set air flow rate and the actual air volume sensor 29 detect It is preferable to adjust the amount of air supplied from the blower 3 via the inverter 31 based on the amount of difference from the amount of air supplied.

  By carrying out like this, from the increase in air resistance accompanying adjustment to the direction where the space | interval of the clearance gap A of a flame-holding board outer edge part 10a and the throat trunk | drum 5a inner periphery narrows, it blows according to setting airflow volume with the air blower 3. Even when the actual blown air amount is less than the predetermined air ratio, the blower amount of the blower 3 can be corrected sequentially so as to compensate for the shortage air amount. This makes it possible to prevent the above problem and to form a stable flame.

  When the burner 1 having the above configuration is operated, for example, when the burner combustion amount is increased, the static pressure inside the burner body 2 is increased along with the blown amount from the blower 3, but when the static pressure sensor 20 detects it, The static pressure / flame holding plate adjustment controller 21 indicates the flame holding plate 10 at the tip of the rod member 6 via the stepping motor 17 of the advance / retreat means 14 as indicated by a thick arrow in FIG. Move forward (to the left).

  Since the inner diameter of the throat body 5a has a substantially tapered structure that gradually expands forward (leftward in the figure), the flame holding plate outer edge portion 10a and the throat cylinder are accompanied by the forward movement of the flame holding plate 10. The interval of the gap A with the inner peripheral wall of the portion 5a gradually increases, and the static pressure in the burner body 2 decreases with it. When the static pressure returns to a predetermined value (for example, about 300 mmAq), the flame holding plate 10 is stopped at that position.

  At this time, on the front side of the flame holding plate 10 where the burner flame is formed, as shown in FIG. 2, combustion air (primary air) that passes around the fuel injection nozzle 8 and escapes to the central opening B of the flame holding plate 10. ) And secondary air passing through the gap A between the outer edge 10a of the flame holding plate and the inner peripheral wall of the throat body 5a is supplied, and stable flame formation becomes possible.

  On the other hand, when the burner combustion amount is reduced, the static pressure inside the burner body 2 is lowered along with the blown amount from the blower 3, but when the static pressure sensor 20 detects this, the static pressure / flame holding plate adjustment controller. 21 retreats the flame holding plate 10 at the tip of the rod member 6 via the stepping motor 17 of the advance / retreat means 14 as indicated by the thick arrow in FIG. 3 (to the right in the figure).

  As the flame holding plate 10 moves backward, the gap A between the flame holding plate outer edge portion 10a and the inner peripheral wall of the throat barrel portion 5a is gradually reduced, and the static pressure in the burner body 2 is increased. To go. When the static pressure returns to a predetermined value, the flame holding plate 10 is stopped at that position.

  If the burner combustion amount is reduced to near the minimum combustion amount, the flame holding plate 10 moves backward to a position that fits in the burner body 2 as shown in FIG. At this time, the flame holding plate outer edge portion 10a and the inner peripheral wall of the throat barrel portion 5a are in close contact with each other without any gap, that is, the gap A, which is a flow path for the secondary air, is almost closed. On the front side, the passage is limited to a flow path that passes exclusively around the fuel injection nozzle 8 and exits to the center opening B of the flame holding plate 10, and the static pressure value in the burner body 2 returns to a predetermined value as described above. Maintained.

  As a result, in the burner having a high turndown ratio, even when the combustion air amount is near the minimum combustion amount that is extremely smaller than that at the maximum combustion amount, the combustion air injected from the burner body 2 is injected. The flow velocity can be maintained at a level equivalent to that at the time of high to intermediate combustion, and combustion can be performed satisfactorily without deteriorating the stirring and mixing properties of the fuel oil and the combustion air.

  In addition, since the flame holding plate 10 and the fuel injection nozzle 8 are configured to advance and retreat integrally while maintaining the distance therebetween, for example, the flame holding plate 10 is moved forward and backward according to the burner combustion amount. In addition, the influence on the oil spray angle and the flame shape can be minimized.

  The present invention can be widely used for a pressure spray type burner for liquid fuel.

DESCRIPTION OF SYMBOLS 1 ... Burner 2 ... Burner main body 3 ... Air blower 4 ... Air blow duct 5 ... Throat 5a ... Throat trunk | drum 6 ... Rod member 8 ... Fuel injection nozzle 10 ... Flame holding plate 10a ... Flame holding plate outer edge 12 ... Fuel supply piping 13 ... Fuel return pipe 14 ... Advance / retreat means 20 ... Static pressure sensor 21 ... Static pressure / flame holding plate adjustment controller 23 ... Flow rate sensor 29 ... Air volume sensor 31 ... Inverter (air flow rate adjustment means)
32 ... Fuel / air flow adjustment controller

Claims (3)

  A small-diameter portion side of a throat having a hollow and substantially frustoconical body portion is connected to a tip opening portion of a burner body having a single cylinder structure, an annular flame holding plate having the same diameter as the inner diameter of the burner body, A fuel injection nozzle located behind the flame holding plate is provided so as to be integrally movable along the longitudinal direction of the burner body, and further includes a static pressure sensor for detecting a static pressure in the burner body, the static pressure sensor The flame holding plate is moved forward and backward within the range of the throat barrel so that the static pressure value detected at the predetermined value is maintained, and the outer edge of the flame holding plate and the inner peripheral wall of the throat barrel are secondary air flow paths. A burner comprising a static pressure / flame holding plate adjustment controller for adjusting a gap interval between the burner and the flame.   In the static pressure / flame holding plate adjustment controller, at least a predetermined static pressure value that enables stable combustion is set, and if the static pressure value detected by the static pressure sensor falls below the predetermined static pressure value, the predetermined static pressure value is set. The burner according to claim 1, wherein the flame holding plate is advanced and retracted so as to be maintained at a pressure value to adjust a gap interval between the outer edge of the flame holding plate and the inner peripheral wall of the throat body.   A flow rate sensor for detecting a flow rate of a fuel supply pipe that supplies fuel to the fuel injection nozzle, an air volume sensor for detecting an air flow rate of a blower that supplies combustion air to the burner body, and an air flow rate of the blower are adjusted. Based on the difference between the air flow rate adjusting means and the actual air flow rate detected by the air flow sensor and the set air flow rate corresponding to a predetermined air ratio with respect to the fuel supply amount detected by the flow rate sensor. The burner according to claim 1 or 2, further comprising a fuel / air flow rate adjustment controller that adjusts the air flow rate of the blower through the air flow rate adjusting means.

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