JP2007147154A - Combustion apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide operation using a blower with a small capacity by reducing a pressure necessary for supply air, in a combustion apparatus preventing malfunction such as oscillating combustion while maintaining compactness of a wind box. <P>SOLUTION: The combustion apparatus has a burner having a cylindrical burning tube 3, the wind box 9 coaxial with the burning tube 3 and having a diameter larger than the burning tube 3, the blower carrying out supply of combustion air, and a draft duct 10 connecting the blower and the wind box 9, and combustion is carried out while pushing in the combustion air from the blower. The draft duct 10 is connected in a tangential direction of a wind box circumferential wall 7, and since an air flow having entered the wind box from a draft duct connecting part flows along the wind box circumferential wall, a swirl flow of air is formed in the wind box. In the wind box 9, a tapered plate 8 is provided such that a wind box inner diameter gradually becomes smaller toward the burning tube. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a combustion apparatus configured to send air to a combustion section after air is swirled in a wind box.

  Japanese Patent Application Laid-Open No. 2004-125183 discloses a burner having a cylindrical combustion cylinder, a wind box connected to the upstream side of the combustion cylinder, an air passage for sending air into the wind box, and air rectified by the wind box. In the combustion apparatus that uses the combustion, the wind box has a cylindrical shape having a diameter larger than that of the combustion cylinder, the air passage is connected in the tangential direction of the wind box, and the root end of the combustion cylinder is winded. There is described a wind box structure of a combustion apparatus in which the inside of the wind box is divided into an outer swirl chamber and a center rectification chamber by extending into the box.

The present invention provides a swirl chamber in the wind box and swirls air in the wind box to increase the air pressure in the root portion of the wind box and cause problems such as vibration combustion due to a pressure difference with the combustion section. Is to prevent the occurrence of. Although this structure was suitable for a relatively small combustion apparatus, when the combustion apparatus having the structure described in Japanese Patent Application Laid-Open No. 2004-125183 is scaled up to a large combustion apparatus with a combustion amount exceeding 1500 kW, Since the blast volume increases, the pressure loss at the inlet of the combustion cylinder increases. Therefore, there has been a problem that air having a higher pressure has to be supplied from the air passage or that the wind box has to be enlarged. In order to increase the supply air pressure, a large capacity blower is required, and when a large capacity blower is used, the amount of power used is increased and the generated noise is also increased. Therefore, a structure that can prevent the occurrence of vibration combustion or the like by a low-capacity blower without increasing the size of the wind box even when the combustion amount is increased has been studied.
JP 2004-125183 A

  The problem to be solved by the present invention is to prevent the occurrence of problems such as vibration combustion while maintaining the compactness of the wind box, reducing the pressure required for the supply air, and reducing the capacity of the blower It is to enable operation by.

  The invention according to claim 1 is a burner having a cylindrical combustion cylinder, a wind box coaxial with the combustion cylinder and having a larger diameter than the combustion cylinder, a blower for supplying combustion air, and a blower In the combustion apparatus having a blower passage connecting the wind box and the combustion air is pushed in from the blower, the blower passage is connected in the tangential direction of the peripheral wall of the windbox, and enters the windbox from the blower passage connecting portion. The air flow flows along the peripheral wall of the wind box so as to form a swirling flow of air in the wind box, so that the inner diameter of the wind box gradually decreases toward the combustion cylinder in the wind box. A taper plate is provided on the surface.

  According to a second aspect of the present invention, in the combustion apparatus described above, the air flow that has entered the wind box from the air passage connection portion reaches the front of the air passage connection portion again after making one round in the wind box. In order to prevent this, a shielding plate that shields the swivel portion in the wind box and the air passage connection portion is provided.

According to a third aspect of the present invention, in the above combustion apparatus, the shielding plate has a plate shape extending from the wind box peripheral wall surface toward the wind box central axis direction, and the wind box peripheral wall surface side root of the shielding plate A length A from the center to the windbox central axis side tip has a shielding plate enlarged portion that is larger than a length a from the peripheral wall surface of the windbox to the combustion cylinder connecting portion.

  According to a fourth aspect of the present invention, in the above-described combustion apparatus, the shielding is performed so that the downstream side of the air swirl flow in the wind box is directed forward so that the swirl flow of the air can easily flow toward the combustion cylinder direction. It is characterized by the fact that the board is inclined.

  By implementing the present invention, a swirling air flow having a high pressure can be supplied to the tip of the combustion cylinder, and problems such as vibration combustion can be prevented by increasing the pressure of the air near the tip of the combustion cylinder. . In addition, by reducing the pressure loss in the wind box part, the pressure required for the supply air is reduced while maintaining the compactness of the wind box, so it is possible to operate with a blower with a smaller capacity than before, Power consumption and generated noise could be reduced by reducing the fan capacity.

  An embodiment of the present invention will be described with reference to the drawings. 1 is a cross-sectional perspective view of a combustion apparatus according to an embodiment of the present invention, FIG. 2 is a perspective cross-sectional view of a combustion apparatus according to a second embodiment, and FIG. 3 is a perspective cross-sectional view of the combustion apparatus according to a third embodiment. .

  The burner portion is provided with a fuel injection nozzle 1 at the center, a cylindrical primary air cylinder 2 around the combustion injection nozzle 1, and a cylindrical combustion cylinder 3 further outside the primary air cylinder 2. A wind box 9 is provided upstream of the primary air cylinder 2 and the combustion cylinder 3, and the primary air flow path 4 is provided inside the primary air cylinder 2, and the secondary air flow is provided between the primary air cylinder 2 and the combustion cylinder 3. It is assumed that the road 5 is used. The downstream air end face of the secondary air flow path 5 is provided with a secondary air outlet 6 arranged at a predetermined interval, and the surfaces other than the secondary air outlet are closed. The primary air cylinder 2 extends to the inside of the wind box 9, and the upper end of the primary air cylinder 2 is close to the upper surface of the wind box. A gap is formed between the upper surface of the wind box 9 and the upper end of the primary air cylinder 2 so that part of the air enters the primary air flow path 4 from the upper end opening of the primary air cylinder 2.

  The wind box portion is coaxial with the combustion cylinder 3 and has a cylindrical shape having a diameter larger than that of the combustion cylinder 3, and the upper portion of the combustion cylinder 3 is connected to the bottom surface of the wind box 9. Connected to the upper portion of the windbox peripheral wall 7 is a blower passage 10 for sending air from a blower (not shown) to the windbox. The air passage 10 is connected in the tangential direction of the wind box peripheral wall, and the air from the air passage 10 is made to flow along the inner surface of the wind box peripheral wall 7.

  In the wind box 9, a tapered plate 8 that connects the middle of the wind box peripheral wall 7 to the connecting portion between the wind box 9 and the combustion cylinder 3 is provided over the entire circumference of the wind box 9. The taper plate 8 is easy to understand if it is assumed that a funnel is installed in the wind box 9, and the bottom of the wind box 9 has a conical shape. The air passage 10 is connected to the upper part of the wind box 9, and the combustion cylinder 3 is connected to the lower part of the wind box 9, and the air flow in the wind box flows from the upper part to the lower part. It can also be said that the diameter becomes smaller toward the downstream side of the.

  Since the airflow that has entered the windbox 9 from the air passage 10 flows along the windbox peripheral wall 7, the airflow swirls in the windbox 9. Further, since the air flow flows toward the secondary air flow path 5, the air flow in the wind box 9 also includes a component that flows downward. Therefore, the air flow in the wind box 9 flows downward while turning. At this time, since the taper plate 8 is provided in the lower portion of the wind box 9, the air flow flows along the taper plate 8 while turning, and the air flow naturally moves toward the central axis of the wind box 9. It will turn while converging.

  When the taper plate 8 is not provided, the airflow circulates along the windbox peripheral wall 7 and reaches the bottom surface of the windbox, and the direction of the flow is greatly changed at the corners of the peripheral wall and the bottom surface of the windbox to connect the combustion tube 3 It was flowing to. After reaching the bottom surface of the wind box, the air flow flowing toward the connection portion of the combustion cylinder 3 along the bottom surface is obstructed by the air flow swirling in the wind box 9, A large pressure loss occurred in the air flow toward the combustion cylinder 3. However, since the taper plate 8 is provided, the air flow does not reach the corner of the wind box 9 and flows smoothly from the wind box peripheral wall 7 to the secondary air flow path 5 along the taper plate 8. The pressure loss of the air flow can be greatly reduced.

  Further, a shielding plate 11 is provided in the wind box 9 near the portion where the air passage 10 is connected. The shielding plate 11 has a shape standing from the windbox peripheral wall 7 toward the central axis of the windbox. The shielding plate 11 is for preventing the air flow that has entered the wind box 9 from the air passage connection portion from reaching the front of the air passage connection portion again after making one turn along the wind box peripheral wall 7. is there. The shielding plate 11 has the same length in the vertical direction as the height in the wind box, and covers the space from the top surface to the bottom surface in the wind box 9. The length of the shielding plate 11 from the window box peripheral wall 7 to the tip of the shielding plate 11 is longer at the upper portion than the lower portion of the shielding plate 11, and the shielding plate enlarged portion 12 is provided on the upper portion of the shielding plate 11. Yes.

  In the upper part of the wind box 9 to which the air passage 10 is connected, the length A from the wind box peripheral wall 7 to the tip of the shielding plate 11 is a length A, and the length A is the length from the wind box peripheral wall 7 to the connecting portion of the combustion cylinder 3. Make it longer than a. In the embodiment, the length from the windbox peripheral wall 7 to the tip of the shielding plate 11 at the lower part in the windbox 9 is made equal to the length a from the windbox peripheral wall 7 to the connecting portion of the combustion cylinder 3. In addition, although the length to the shielding plate 11 front-end | tip in the lower part of the shielding plate 11 may differ from the length a to the combustion cylinder 3 connection part, in the part which has provided the shielding board expansion part 12 of the shielding board upper part. It is shorter than the length A.

  The shielding plate enlarged portion 12 is set to the length B from the upper part of the shielding plate 11, and the vertical length B of the shielding plate enlarged portion 12 is set to be longer than the inner diameter height b of the air passage 10. The shielding plate notch portion 13 is formed by not providing the shielding plate enlargement portion 12 below the shielding plate 11. That is, the shielding plate 11 is the shielding plate enlarged portion 12 for the length B from the upper side, and the shielding plate notch portion 13 is provided below the length B.

  The combustion air supplied from the air passage 10 flows while diffusing when entering the wind box 9, and since the air passage 10 is connected in the tangential direction of the wind box, the air flow from the air passage 10 is winded. It turns along the inner surface of the box peripheral wall 7. Some air enters the secondary air flow path 5 and the primary air flow path 4 until it makes a round in the wind box 9, but the remaining air flow makes a round in the air wind box 9 and shields 11. It reaches near. Since the shielding plate enlarged portion 12 is longer than the length a from the wind box peripheral wall 7 to the connecting portion of the combustion cylinder 3 and longer than the longitudinal length b of the air passage 10, the shielding plate enlarged portion 12 circulates in the wind box 9. The traveling direction of the air flow that has changed varies along the shielding plate 11.

  When the shielding plate 11 is not installed, the air flow swirling in the wind box reaches the connecting portion of the air blowing path 10 as it is, and in this case, the swirling air flow is the opening of the air blowing path. Therefore, the flow of the air that is going to enter the wind box 9 from the air passage is obstructed. However, since the shielding plate 11 is installed, the air flow that has made a round along the peripheral wall 7 of the windbox flows along the shielding plate 11, and the shielding plate 11 has a shielding plate notch on the lower end side. 13 is provided, the air flow reaching the shielding plate 11 flows to the shielding plate notch 13. For this reason, the swirling air flow does not reach the air passage connecting portion on the back side of the shielding plate 11, and the air flow entering the wind box 9 from the air blowing passage 10 is blocked by the swirling air flow. Therefore, the pressure loss when air enters the wind box 9 from the air blowing path 10 can be reduced.

  Further, the air flow that has made a round in the wind box 9 and reaches the portion of the shielding plate 11 is obstructed by the shielding plate 11, but the shielding plate 11 has a shielding plate notch 13 at the bottom. The airflow flows in the direction of the shielding plate notch 13. Since the airflow passes through the shielding plate notch 13 on the windbox central axis side, it flows while converging to the vicinity of the central axis in the lower part of the windbox 9. Further, since the air passes through the shielding plate notch 13, the air flow continues to turn. If the shielding plate 11 does not have the shielding plate cutout portion 13 and the shielding plate having a length A extends to the bottom surface in the wind box, the swirling air flow collides with the shielding plate 11 and then shields it. It flows downward along the surface of the plate 11. In this case, the swirl force of the air flow is lost and pressure loss occurs in the air flow. However, the shielding plate 11 is provided with the shielding plate notch 13 so that the air flow swirling in the wind box 9 can escape to the shielding plate notch 13 so that the air flow continues to turn. And pressure loss can be reduced.

  The air flow enters the secondary air flow path 5 while turning, and flows downward while turning also in the secondary air flow path 5. In the process in which the air flow enters the wind box from the blower passage 10 and further flows into the secondary air flow path, elements that cause pressure loss are removed as much as possible, so that the static air flow in the secondary air flow path is reduced. The pressure can be kept high. The air that has reached the vicinity of the tip of the secondary air flow path 5 is jetted downward from the secondary air outlets 6 provided on the end surface of the secondary air flow path 5. Further, the air flow that has entered the primary air flow path 4 in the primary air cylinder is also jetted downward from the tip of the primary air flow path 4. The fuel injected from the fuel injection nozzle 1 is first mixed with the primary air that has passed through the primary air flow path 4 and burned. At this time, the combustion is incomplete because the amount of air is insufficient with only the primary air, and then mixed with the secondary air injected from the secondary air outlet 6 through the secondary air flow path 5 to complete the combustion. It becomes combustion. When the amount of primary air is reduced and air is supplied in two stages, the local flame temperature peak formed in the vicinity of the burner can be reduced, so that the amount of NOx generated can be reduced.

  To reduce the stability of combustion in order to reduce the amount of NOx generated, the air flow is swirled in the secondary air flow path, and combustion is achieved by increasing the air pressure in the secondary air flow path. This is solved by ensuring a pressure difference with the part. By securing the pressure difference, the combustion surface of the flame combusting at the tip of the fuel injection nozzle 1 can be stabilized, and stable combustion can be performed without causing problems such as vibration combustion. In the invention described in the prior art, vibration combustion is eliminated by increasing the pressure of the airflow in the upper part of the windbox. However, the airflow is swirled in the secondary air flow path 5, and It was confirmed that the combustion of the flame can also be stabilized by increasing the pressure of the air flow in the secondary air flow path 5. And the pressure in the front-end | tip part of the secondary air flow path 5 is low even if the pressure of the air supplied from the ventilation path 10 is made lower pressure by reducing pressure loss, maintaining the compactness of a wind box. A sufficient height can be maintained. Therefore, the capacity required for the blower is less than before without increasing the size of the burner to increase the amount of combustion, and by reducing the capacity of the blower, power consumption and generated noise can be reduced. It was. If the supply pressure can be reduced, the power reduction effect has the effect of the third power of the supply pressure reduction. Therefore, in the actual combustion apparatus, the capacity of the blower motor can be reduced by about 30%. A great effect was obtained.

  FIG. 2 shows a second embodiment, which is different from FIG. 1 in that the shielding plate 11 is inclined. The shielding plate 11 in FIG. 2 is installed with the downstream side of the air swirl flow in the wind box inclined forward so that the swirl flow of air can easily flow toward the combustion cylinder. In this case, the swirling air flow that enters the wind box 9 from the air passage 10 and reaches the shielding plate 11 by swirling along the wind box peripheral wall 7 passes through the shielding plate notch 13. 11 is inclined, the swirling air flow naturally flows toward the shielding plate notch 13 by flowing along the shielding plate 11, and is smoother than the flow.

  Further, the shielding plate 11 may be composed of only the shielding plate enlarged portion 12 as shown in FIG. The purpose of the shielding plate 11 is to prevent the airflow swirling along the windbox peripheral wall 7 from reaching the front of the connection portion of the air passage 10, and therefore the lower portion is not necessarily required. The shield plate 11 has a length A from the windbox peripheral wall 7 to the tip of the shield plate 11 longer than a length a from the windbox peripheral wall 7 to the connection part of the combustion cylinder 3, and a length from the upper end to the lower end of the shield plate 11. B can prevent the swirling air flow from reaching the front of the connecting portion of the air passage by making it longer than the inner diameter height b of the air passage 10. Also in this case, the air flow that has made one turn along the windbox peripheral wall 7 passes through the lower part of the shielding plate 11. Thereafter, the air flow swirls in the wind box 9 along the taper plate 8 and enters the secondary air flow path 5 while swirling.

The cross-sectional perspective view of the combustion apparatus in one Example of this invention Sectional perspective view of the combustion apparatus in the second embodiment of the present invention Sectional perspective view of the combustion apparatus in the third embodiment of the present invention

Explanation of symbols

1 Fuel injection nozzle
2 Primary air cylinder
3 Combustion cylinder
4 Primary air flow path
5 Secondary air flow path
6 Secondary air outlet
7 Windbox wall
8 Tapered plate 9 Wind box 10 Blower passage 11 Shield plate 12 Shield plate enlarged portion 13 Shield plate notch

Claims (4)

  A burner with a cylindrical combustion cylinder, a wind box that is coaxial with the combustion cylinder and has a larger diameter than the combustion cylinder, a blower that supplies combustion air, and an air passage that connects the blower and the wind box In the combustion apparatus that performs combustion while pushing the combustion air from the blower, the air passage is connected in a tangential direction of the wind box peripheral wall, and the air flow that has entered the wind box from the air passage connection portion is applied to the wind box peripheral wall surface. A swirl flow of air is formed in the wind box by flowing along, and a tapered plate is provided in the wind box so that the inner diameter of the wind box gradually decreases toward the combustion cylinder. Combustion device characterized.   2. The combustion apparatus according to claim 1, wherein an air flow entering the wind box from the air passage connection portion is prevented from reaching the front of the air passage connection portion again after having made one round in the wind box. A combustion apparatus comprising a shielding plate that shields the swivel part in the box and the air passage connection part.   3. The combustion apparatus according to claim 2, wherein the shielding plate has a plate shape extending from a wind box peripheral wall surface toward a wind box central axis direction, and the wind box extends from a root portion on the wind box peripheral wall surface side. A combustion apparatus characterized in that a length A up to the central axis side tip has a shielding plate enlarged portion that is larger than a length a from the peripheral wall surface of the windbox to the combustion cylinder connection.   4. The combustion apparatus according to claim 2, wherein the shielding plate is disposed so that the downstream side of the air swirl flow in the wind box is directed forward so that the air swirl flow easily flows toward the combustion cylinder. Combustion device characterized by being inclined.

Images