JP2015004483A - Fuel two-stage combustion type burner device, and fuel two-stage combustion method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel two-stage combustion method for augmenting the ratio of a secondary fuel supply amount/a primary fuel supply amount without deteriorating a combustion stability in a primary combustion area, and for increasing the excess ratio of burning air without increasing the generation quantity of nitrogen oxides.SOLUTION: A primary fuel (F1) of a primary fuel injection port (11) is fed in a burner throat (13) to a burning air flow (A). Dam portions (20) are arranged between a secondary fuel injection port (12) and an outlet opening (14), and are protruded onto a furnace inner surface (W). The directivity of a secondary fuel (F2) is varied by the dam portions (20). The secondary fuel is mixed with an in-furnace combustion gas (EG). Via an in-furnace combustion gas recirculation passage (30) formed between the dam portions, the in-furnace combustion gas circulation flow is fed to the burning air flow (A). The burning air is diluted with the in-furnace combustion gas. The secondary fuel mixed with the in-furnace combustion gas and the combustion air diluted are mixed in contact, so that a secondary combustion flame (C2) is created in an in-furnace region (V) thereby to improve the NOx reducing effect.

Description

  The present invention relates to a fuel two-stage combustion burner apparatus and a fuel two-stage combustion method, and more specifically, supplies fuel to combustion air in two stages and burns a circulating flow of combustion gas in the furnace. TECHNICAL FIELD The present invention relates to a fuel two-stage combustion burner device and a fuel two-stage combustion method for carrying out a fuel two-stage combustion method (fuel staging method) in which the oxygen concentration of combustion air is reduced by mixing with the combustion air.

  As a low NOx combustion method, a fuel two-stage combustion method is known in which fuel is divided into two stages and supplied to combustion air. FIG. 8 illustrates the configuration of a burner apparatus that performs the two-stage fuel combustion method. As shown in FIG. 8, the burner device includes a primary fuel nozzle 101 and a secondary fuel nozzle 102 for supplying a primary fuel F1 and a secondary fuel F2, respectively. The entire amount of combustion air A including the excess air amount (theoretical air amount + excess air amount) is supplied to the burner throat 103. The primary fuel nozzle 101 is disposed at the center of the burner throat 103, and injects the primary fuel F1 at the center of the combustion air flow A to form a primary combustion flame C1. The secondary fuel nozzle 102 is disposed on a furnace inner surface W such as a burner tile, a furnace wall, or a hearth, and injects the secondary fuel F2 into the combustion air flow A in the vicinity of the outlet portion of the burner throat 103.

  The in-furnace combustion gas EG generated in the in-furnace region V is attracted by the combustion air flow A jetted into the in-furnace region V and mixed with the combustion air flow A. Therefore, the combustion air stream A is mixed with the primary combustion gas generated by the primary combustion and diluted, and mixed with the in-furnace combustion gas EG, so that the oxygen concentration of the combustion air stream A is reduced. To do. The secondary fuel F2 injected by the secondary fuel nozzle 102 is mixed with the in-furnace combustion gas EG in the jet region J, mixed with and brought into contact with the combustion air flow A with a reduced oxygen concentration, and the second fuel F2 injected by the slow in-core combustion reaction. The next combustion flame C2 is formed in the in-furnace region V.

  In such a fuel two-stage combustion method, after combusting the primary fuel F1 in an air excess state with a relatively high air ratio, the combustion air, the primary combustion gas, the in-furnace combustion gas EG, and the secondary fuel F2 are mixed. And a slow secondary combustion reaction is advanced to the furnace region. This type of fuel two-stage combustion method is described in, for example, Japanese Patent Application Laid-Open No. 6-159613 (Patent Document 1), Japanese Patent Application Laid-Open No. 8-145315 (Patent Document 2) and the like relating to the application of the present applicant. .

JP-A-6-159613 JP-A-8-145315

  In such a fuel two-stage combustion method, increasing the ratio of the secondary fuel supply amount to the primary fuel supply amount (secondary fuel supply amount / primary fuel supply amount) reduces the generation of nitrogen oxides (NOx). Desirable for suppression. This point has already been found by recent studies.

  However, as a result of increasing the ratio of the secondary fuel supply amount, if the ratio of the primary fuel supply amount is relatively reduced, the air ratio in the primary combustion zone increases and the primary combustion reaction becomes a combustion reaction in an extremely excessive air environment. Therefore, it is difficult to ensure the stable combustibility in the primary combustion region as desired. Therefore, in the conventional fuel two-stage combustion method, priority is given to or priority is given to ensuring the combustion stability in the primary combustion region. There are circumstances where it is difficult to increase the ratio of the supply amount as desired. This means that the ratio of the secondary fuel supply amount / primary fuel supply amount that sacrifices the NOx reduction effect to some extent must be adopted as the operating condition.

  Also, in certain types of combustion furnaces, heating furnaces, etc., it is necessary to employ operating conditions in which the excess rate of combustion air is increased in order to lower the furnace temperature or the like. Under such operating conditions such as a combustion furnace, oxygen that does not participate in the combustion reaction increases quantitatively, so that the amount of nitrogen oxide generated tends to increase.

  The present invention has been made in view of such circumstances, and its purpose is to increase the ratio of the secondary fuel supply amount / primary fuel supply amount without impairing the combustion stability in the primary combustion region. In addition, an object of the present invention is to provide a fuel two-stage combustion burner apparatus and a fuel two-stage combustion method capable of increasing the excess ratio of combustion air without increasing the amount of nitrogen oxides generated.

In order to achieve the above object, the present invention comprises a burner throat opened on the inner wall surface, hearth surface or top surface of a furnace, a primary fuel injection port for supplying primary fuel and secondary fuel to combustion air in stages, and A secondary fuel injection port, and mixing the combustion gas circulation flow in the furnace with the combustion air to reduce the oxygen concentration of the combustion air, and then the combustion air and the secondary fuel are mixed in the secondary combustion zone. In the fuel two-stage combustion burner device to be mixed,
It is arranged between the secondary fuel injection port located on the inner surface of the furnace and the outlet opening of the burner throat, and has a weir protruding from the inner surface of the furnace so as to surround the outlet opening,
The weir causes the outer surface to change the direction of the secondary fuel jet injected by the secondary fuel injection port, and the combustion gas circulation flow in the furnace to flow along the furnace inner surface toward the opening edge of the outlet opening. Provided is a fuel two-stage combustion burner device having an in-furnace combustion gas recirculation path.

The present invention also supplies a combustion air flow from a burner throat opened to the furnace inner wall surface, the furnace floor surface, or the furnace top surface to the furnace inner region, and mixes the circulation flow of the furnace combustion gas with the combustion air. Combusting air is used to reduce the oxygen concentration in the combustion air, and to convert the primary fuel injection port disposed in the burner throat and the secondary fuel in the secondary fuel injection port disposed on the inner surface of the furnace into combustion air. In the fuel two-stage combustion method to supply automatically,
By placing a weir between the secondary fuel injection port located on the furnace inner surface and the outlet opening of the burner throat, and surrounding the outlet opening by the weir protruding from the furnace inner surface, Change the direction of the secondary fuel jet injected by the fuel injection port,
An in-furnace combustion gas recirculation path is formed in the weir to cause the in-furnace combustion gas circulation flow to flow along the inner surface of the furnace toward the opening edge of the outlet opening and to flow out from the outlet opening to the in-furnace region. A fuel two-stage combustion method is provided, wherein a combustion gas in a furnace is mixed with the combustion air.

  Preferably, a plurality of dam portions constituting the dam are arranged at intervals along an outer edge portion of the outlet opening, and the in-furnace combustion gas recirculation path is formed by a separation region between adjacent dam portions. More preferably, the weir portion has a generally arcuate and convex curved shape so as to bulge toward the outlet opening, and each of the weir portions can collide with a plurality of secondary fuel jets equally. It has an arcuate and concave outer surface.

  In this specification, “weir” refers to a bank, a ridge, a ridge, a protruding portion, a protruding portion, a partition wall, etc. that can stay or deflect while preventing the flow of fluid flowing along the furnace inner surface. It is a concept that includes The “dam portion” means a constituent unit or a component of the “dam”, and the “dam” can be formed by connecting or separating a plurality of “dam portions”.

  According to the above configuration of the present invention, the influence of the combustion gas circulation flow in the furnace on the primary combustion flame can be mitigated or hindered by the failure of the weir, so that the combustion gas circulation flow in the furnace is hydrodynamically converted into the primary combustion flame. Thus, stable combustion in the primary combustion region can be improved, and as a result, the ratio of secondary fuel supply amount / primary fuel supply amount can be increased. Increasing the ratio of secondary fuel supply / primary fuel supply means that more fuel can be mixed with the in-furnace combustion gas before the combustion reaction (thus, the fuel two-stage combustion burner device and the fuel two-stage combustion method) It is possible to improve the NOx reduction effect.

  Further, according to the above configuration of the present invention, the in-furnace combustion gas circulation flow is supplied to the combustion air flow through the in-furnace combustion gas recirculation path, and is mixed with the combustion air. Combustion air is diluted with the combustion gas in the furnace immediately after flowing out from the outlet opening of the burner throat, the oxygen concentration is lowered, and then mixed with the secondary fuel. On the other hand, the secondary fuel injected from the secondary fuel injection port is turned or turned to the inside of the furnace outside the weir and is effectively mixed with the combustion gas in the furnace. Therefore, according to the above configuration of the present invention, the combustion air is diluted early with a relatively large amount of combustion gas in the furnace (that is, immediately after the primary combustion) and then mixed with a relatively large amount of combustion gas. Mixing contact with fuel can cause a slow secondary combustion reaction. That is, according to the present invention, a slow secondary combustion reaction can be caused by mixing contact between the combustion air having a reduced oxygen concentration and the secondary fuel sufficiently mixed with the in-furnace combustion gas. The NOx reduction effect of the two-stage combustion type burner device and the fuel two-stage combustion method can be improved.

  In addition, according to the present invention, generation of nitrogen oxides can be suppressed by such an improvement in NOx reduction effect, so that the excess ratio of combustion air can be increased.

  According to the fuel two-stage combustion type burner device and the fuel two-stage combustion method of the present invention, the ratio of the secondary fuel supply amount / primary fuel supply amount is increased without impairing the combustion stability in the primary combustion zone, The excess rate of combustion air can be increased without increasing the amount of oxide generated.

FIG. 1 is a front view schematically showing the structure of a fuel two-stage combustion burner apparatus according to the present invention. 2 is a cross-sectional view taken along the line II of FIG. 3 is a cross-sectional view taken along line II-II in FIG. 4A is a schematic perspective view showing the action of the weir shown in FIGS. 1 to 3, and FIG. 4B is a diagram of a burner device provided with a cylindrical or annular weir without a separation region. FIG. 4C is a schematic perspective view showing a configuration of a burner apparatus that does not include a weir as a comparative example. 5A is a partially enlarged cross-sectional view taken along the line II of FIG. 1, and FIG. 5B is a partially enlarged cross-sectional view taken along the line II-II of FIG. FIG. 6 is a partial longitudinal sectional view of a combustion furnace or a heating furnace showing an embodiment of a combustion furnace or a heating furnace in which the low NOx burner device according to the present invention is disposed in the hearth part. 7 is a cross-sectional view taken along line III-III in FIG. FIG. 8 is a cross-sectional view illustrating the configuration of a conventional low NOx burner apparatus that implements the fuel two-stage combustion method.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  1 to 3 are a front view, a cross-sectional view taken along a line II, and a cross-sectional view taken along a line II-II, schematically and conceptually showing the configuration of a fuel two-stage combustion burner apparatus according to the present invention.

  The fuel two-stage combustion type burner device 1 (hereinafter referred to as “burner device 1”) includes a primary fuel nozzle 11 that injects or discharges primary fuel F1 in a burner throat 13, and a burner tile, a furnace wall, or a hearth. A secondary fuel nozzle 12 for injecting or discharging the secondary fuel F2 from the furnace inner surface W to the furnace inner region V, and a plurality of weir portions 20 protruding from the furnace inner surface W are provided. The primary fuel nozzle 11 is disposed at the center of the burner throat 13.

  Combustion air A is supplied to the burner throat 13. The combustion air A is an air flow of a theoretical air amount and an excess air amount (total air amount) required for the combustion reaction of the burner device 1. The primary fuel F <b> 1 injected by the primary fuel nozzle 11 is mixed with the combustion air A and causes a combustion reaction to form a primary combustion flame C <b> 1 at the outlet of the burner throat 13.

  As shown in FIG. 2, the outlet opening 14 of the burner throat 13 has a true circular contour centered on the central axis of the burner throat 13. The dam portions 20 are arranged at intervals in the circumferential direction along the outer periphery of the outlet opening 14, and form a dam that entirely surrounds the outlet opening 14. The secondary fuel nozzle 12 is disposed outside the dam portion 20, and the dam portion 20 forms a partition that separates the nozzles 11, 12 between the outer edge of the outlet opening 14 and the secondary fuel nozzle 12.

  As shown in FIG. 1, four secondary fuel nozzles 12 having the same structure and the same shape are arranged on the furnace inner surface W with an angular interval of 90 degrees in the circumferential direction, and four bodies having the same structure and the same shape are arranged. The weir portions 20 are disposed on the furnace inner surface W with an angular interval of 90 degrees. Each secondary fuel nozzle 12 is a multi-nozzle type fuel nozzle having a plurality of fuel injection ports, and injects the secondary fuel F2 with a predetermined opening angle. As shown in FIG. 1, each dam portion 20 has a generally curved shape so as to bulge toward the outlet opening 14, and is a concave arc shape in which the jet of the secondary fuel F <b> 2 can collide evenly. An outer surface 21 is provided. The arcuate outer surface 21 is an arcuate surface having a radius of curvature r1 with the center of curvature O as the center. The center of curvature O is located on the central axis of the weir portion 20 (indicated by the one-dot chain line in FIG. 1), and the center of the secondary fuel nozzle 12 is the center of the weir portion 20 between the arcuate outer surface 21 and the center of curvature O. Located on the axis. The weir portion 20 has a convex arcuate inner surface 22 proximate to the opening edge of the outlet opening 14 at a proximity point 23 on the central axis. The arcuate inner surface 22 is an arcuate surface having a radius of curvature r2 with the center of curvature O as the center.

  Each dam portion 20 is formed in an angle range of an angle α with respect to the center of the outlet opening 14, and forms a separation region 30 spaced from each other in an angle range of an angle β. Preferably, the ratio of the diameter D of the outlet opening 14 to the opening width S of the separation region 30, that is, S / D is set to a value in the range of 0.2 to 0.5. The separation region 30 constitutes an in-furnace combustion gas recirculation path for mixing the in-furnace combustion gas EG generated in the in-furnace region V with the combustion air flow A.

  As shown in FIGS. 2 and 3, the weir portion 20 protrudes from the furnace inner surface W by the protrusion dimension H to the inside of the furnace. Preferably, the ratio between the diameter D and the protrusion dimension H, that is, H / D is set within a range of 0.2 to 2.0 (however, 40 mm or more).

  4A is a schematic perspective view showing the operation of the dam portion 20 shown in FIGS. 1 to 3, and FIG. 4B includes a cylindrical or annular dam 120 that does not include the separation region 30. 4C is a schematic perspective view showing the configuration of the burner device as a reference example, and FIG. 4C is a schematic perspective view showing the configuration of the burner device without the dam portion 20 as a comparative example. 5A is a partially enlarged cross-sectional view taken along the line II of FIG. 1, and FIG. 5B is a partially enlarged cross-sectional view taken along the line II-II of FIG. FIG. 5 shows an enlarged view of the weir portion 20.

  As shown in FIG. 4 (C), in the burner device that does not include the dam portion 20, the primary fuel F1 injected or discharged by the primary fuel nozzle 11 is mixed and contacted with the combustion air flow A to form the primary combustion flame C1 ( 8) is formed in the vicinity of the outlet opening 14, and the in-furnace combustion gas EG attracted to the combustion air flow A is mixed into the combustion air flow A from all directions of the outlet opening 14, and the secondary fuel nozzle 12 is obtained. The secondary fuel F2 injected or discharged by is mixed with the in-furnace combustion gas EG. The secondary fuel F2 mixed with the in-furnace combustion gas EG is mixed and contacted with the combustion air flow A mixed with the in-furnace combustion gas EG to reduce the oxygen concentration, and the secondary combustion flame C2 (FIG. 8) is brought into the furnace. It produces | generates to the area | region V (FIG. 8).

  The burner device having this structure is of the conventional structure described with reference to FIG. 8, and when the ratio of the secondary fuel supply amount / primary fuel supply amount is increased to improve the NOx reduction effect, the burner device is stabilized in the primary combustion region. There are circumstances where it is difficult to ensure combustibility as desired. The reason why the stable combustibility is impaired is mainly due to the fact that the overall behavior or hydrodynamic action of a relatively large amount of the combustion gas circulation flow flowing in the furnace region affects the primary combustion flame C1 as a disturbance. Conceivable.

  On the other hand, as shown in FIG. 4 (B), a cylindrical or annular integral weir 120 is arranged on the outer periphery of the outlet opening 14 to reduce the influence of the furnace combustion gas circulation flow on the primary combustion flame C1. Can be considered. According to such a configuration, since the mixing contact between the secondary fuel F2 and the combustion air flow A is transiently blocked by the weir 120, the secondary fuel F2 is sufficiently mixed with the in-furnace combustion gas EG. Thus, it is considered that the NOx reduction effect can be improved to some extent. However, not only is the mixing of the in-furnace combustion gas EG and the combustion air flow A transiently blocked by the weir 120, but many of the secondary fuels F2 directed upward along the outer peripheral surface of the weir 120 are: Before the in-furnace combustion gas EG is mixed with the combustion air stream A, it mixes with the combustion air stream A. That is, most of the secondary fuel F2 is mixed and contacted with combustion air containing a relatively large amount of oxygen (combustion air before being mixed with the in-furnace combustion gas) to bring the secondary combustion flame C2 into the in-furnace region. Since it produces | generates, it is difficult to ensure a desired NOx reduction effect.

  On the other hand, as shown in FIG. 4A, in the burner device provided with the above-described weir portion 20, the influence of the combustion gas circulation flow in the furnace on the primary combustion flame C1 (FIGS. 2 and 3) is mitigated, The mixing contact between the secondary fuel F2 and the combustion air flow A is not only transiently hindered by the weir part 20, but the separation region 30 formed between the weir parts 20 functions as a furnace combustion gas recirculation path. Therefore, as shown by the arrows in FIGS. 4A and 5B, the in-furnace combustion gas EG flows inward in the radial direction from the separation region 30 toward the outlet opening 14, and enters the combustion air flow A at an early stage. To mix. Therefore, the combustion air flow A is reliably and regularly diluted by the in-furnace combustion gas EG in the vicinity of the outlet opening 14.

  In addition, as shown in FIG. 5A, the secondary fuel F2 injected from the plurality of fuel injection ports is turned or turned upward by the arc-shaped outer surface 21 and is directed to the secondary combustion region. It diffuses or disperses in the form of a film on the surface of the side surface 21, and flows upward as a thin-film jet. For this reason, the secondary fuel F2 is effectively mixed with the in-furnace combustion gas EG and mixed and contacted with the combustion air after dilution in the secondary combustion region, so that the NOx reduction effect can be improved. it can. As shown in FIG. 5A, the arcuate inner side surface 22 of the dam portion 20 is desirably formed as a tapered surface that expands downstream.

  FIG. 6 is a partial longitudinal sectional view of a combustion furnace or a heating furnace showing an embodiment of a combustion furnace or a heating furnace in which the burner device 1 having the above-described configuration is disposed in the hearth part, and FIG. It is sectional drawing in an III line.

  A burner tile 16 constituting the burner throat 13 of the burner device 1 is fixed to the hearth 50 of the combustion furnace or heating furnace, and the burner device 1 is oriented so as to discharge the combustion air flow A vertically upward. Has been. A gas combustion type burner gun 15 provided with a primary fuel nozzle 11 is disposed in the center of the burner throat 13, and a pilot burner 17 is disposed in the vicinity of the burner gun 15. A plurality of secondary fuel nozzles 12 are disposed on the upper surface W <b> 1 of the burner tile 16 at intervals in the circumferential direction. The primary fuel nozzle 11, the secondary fuel nozzle 12, and the pilot burner 17 are connected to a fuel supply source (not shown) such as a fuel gas supply source through fuel supply pipes 11a, 12a, and 17a. An air casing 18 forming a combustion air flow path is fixed to the hearth 50, and an air supply duct 19 is connected to a side portion of the air casing 18. The air supply duct 19 is connected to an air supply fan (not shown), and ambient air (at high temperature) outside air or air is supplied into the air casing 18 as a combustion air flow A under the air supply pressure of the air supply fan. Sent.

  The upper surface W1 of the burner tile 16 is positioned about 20 mm above the upper surface W2 of the hearth 50, but the upper surfaces W1 and W2 can be considered as the in-furnace surface W at substantially the same level. A weir portion 20 corresponding to each secondary fuel nozzle 12 is integrally attached to the upper surface W1 at a predetermined interval in the circumferential direction, and protrudes vertically upward from the upper surface W1. A separation region 30 having an opening width S is formed on the upper surface W1 as an in-furnace combustion gas recirculation path for mixing the in-furnace combustion gas EG generated in the in-furnace region V with the combustion air flow A.

  In this example, the diameter D of the outlet opening 14 is about 300 mm, and the angles α and β and the opening width S of the weir portion 20 and the separation region 30 are about 70 °, about 20 °, and about 100 mm, respectively. The protrusion dimension H (height) of the weir part 20 is about 150 mm. The value of S / D is about 1/3, and the value of S / H is about 1/2.

  In this example, the radii of curvature r1 and r2 of the arcuate outer surface 21 and the arcuate inner surface 22 are about 330 mm and about 430 mm, respectively. The proximity point 23 is located at the opening edge of the outlet opening 14. The arcuate outer surface 21 stands perpendicular to the upper surface W <b> 1 and extends parallel to the central axis of the burner throat 13. On the other hand, the arc-shaped inner side surface 22 is formed in a tapered or frustoconical surface slightly expanding upward and outward. The inclination angle θ of the arc-shaped inner surface 22 is set to about 10 ° with respect to the central axis of the burner throat 13. As shown in FIG. 6, the separation region 30 also has a profile that is slightly widened upward in accordance with the shape of the dam portion 20.

  The primary fuel F1 injected by the primary fuel nozzle 11 is mixed and contacted with the combustion air stream A to form a primary combustion flame (not shown). The in-furnace combustion gas EG attracted by the combustion air flow A flows radially inward from the separation region 30 toward the outlet opening 14 and mixes with the combustion air flow A. Therefore, the combustion air flow A is In the vicinity of the outlet opening 14, it is diluted by the furnace combustion gas EG. The secondary fuel F2 injected from each injection port of the secondary fuel nozzle 12 is deflected upward by the arc-shaped outer surface 21 and directed to the in-furnace region V, and is diffused or filmed on the surface of the arc-shaped outer surface 21. Disperses and flows upward as a thin film jet. The secondary fuel F2 is effectively mixed with the in-furnace combustion gas EG. Therefore, the secondary fuel F2 mixed with the in-furnace combustion gas EG and the combustion air diluted by the in-furnace combustion gas EG (air flow A ) And a combustion reaction in the secondary combustion zone.

  According to the inventor's experiment using such a burner device 1, the flame holding performance of the burner gun 15 is maintained even when the ratio of the secondary fuel supply amount / primary fuel supply amount is set to 90/10. Therefore, the combustion stability of the primary flame C1 (FIGS. 2 and 3) is ensured. Moreover, according to the configuration of the burner device 1, the mixing of the secondary fuel F2 and the in-furnace combustion gas EG is promoted, and the mixing of the in-furnace combustion gas EG and the combustion air (air flow A) is promoted. As a result, it has been found by experiments of the present inventors that a sufficient NOx reduction effect can be obtained. Further, in the experiment of the present inventor using the burner device 1, it has been found that the NOx value in the combustion exhaust gas does not increase greatly even in the continuous operation state in which the excess air ratio is increased. Thus, according to the above-described configuration of the burner device 1, a low NOx burner device capable of setting the ratio of the secondary fuel supply amount / primary fuel supply amount in the range of 80/20 to 95/5 in the rated combustion state is provided. be able to.

As described above, the superiority of the burner device 1 is considered to be mainly due to the following matters.
(1) Since the inflow position of the circulating flow of the combustion gas EG in the furnace is limited by the weir portion 20 and the separation region 30, the flow of the fluid in the vicinity of the primary combustion flame C1 is rectified and stabilized. Combustion stability is improved, and the ambient air of the primary combustion flame C1 effectively increases in temperature and reduces its oxygen concentration.
(2) Since the secondary fuel F2 collides with the weir portion 20 and turns or turns toward the secondary combustion zone, and the secondary fuel F2 is dispersed or diffused, the secondary fuel F2 becomes the combustion gas EG in the furnace. Uniformly and efficiently.
(3) The flow of the in-furnace combustion gas EG circulating in the primary combustion zone and the flow of the in-furnace combustion gas EG circulating in the secondary combustion zone are separated or divided by the weir portion 20 and the separation region 30, and these flows Can be effectively regulated or controlled, so that the combustion air flow A is diluted by the in-furnace combustion gas EG, the secondary fuel F2 and the in-furnace combustion gas EG are mixed, and the secondary fuel F2 and the combustion air flow A. The three processes of mixing contact can be performed individually or stepwise.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and various modifications or changes can be made within the scope of the present invention described in the claims. Is possible.

  For example, in the above embodiment, the outlet opening of the burner throat is a perfect circle, but it may have a rectangular, rectangular, polygonal, elliptical or the like outline. It is designed in an arrangement and shape corresponding to the shape of the outlet opening.

  In the above-described embodiments and examples, a plurality of dam portions are arranged at intervals in the circumferential direction, but the separated dam portions are integrated or interconnected by a bridging member or the like to stabilize the structure. Alternatively, as shown in FIG. 4B, an integral annular weir or the like is disposed at the outlet opening of the burner throat, and an opening is formed at an appropriate position of the weir, and the inner surface of the weir is disposed downstream of the combustion air flow. By forming it as a tapered or frustoconical surface that expands toward the side, it is possible to design a configuration equivalent to the above-described configuration in which a plurality of weir portions are spaced apart.

  Further, in the above embodiment, the burner device is arranged upward on the hearth portion, but the configuration of the present invention is adopted in the burner device arranged horizontally or downward on the furnace wall portion or the top portion of the furnace. Also good.

  Moreover, in the said embodiment and Example, although the burner apparatus is a thing of the structure which used normal temperature air as combustion air, the burner apparatus which can apply the structure of this invention is the high temperature pre-heated with the thermal storage body etc. It may have a configuration in which combustion air or ultrahigh-temperature combustion air preheated to 800 ° C. or higher is mixed with fuel.

  The present invention is preferably applied to a fuel two-stage combustion type burner apparatus and a fuel two-stage combustion method such as a low NOx burner apparatus and a low NOx combustion method for carrying out a fuel two-stage combustion method. According to the present invention, the combustion air can be increased without increasing the ratio of the secondary fuel supply amount / primary fuel supply amount without increasing the stability of combustion in the primary combustion region, and without increasing the amount of nitrogen oxides generated. Since the excess ratio of can be increased, its practical value is remarkable.

DESCRIPTION OF SYMBOLS 1 Fuel two-stage combustion type burner apparatus 11 Primary fuel nozzle 12 Secondary fuel nozzle 13 Burner throat 14 Outlet opening 15 Burner gun 16 Burner tile 20 Weir part (weir)
21 Arc-shaped outer side surface 22 Arc-shaped inner side surface 23 Proximity point 30 Separation region (furnace combustion gas recirculation path)
50 hearth A air flow for combustion V in-furnace area W in-furnace surface EG in-furnace combustion gas F1 primary fuel F2 secondary fuel C1 primary combustion flame C2 secondary combustion flame

Claims (6)

A burner throat opened on the inner wall surface, the hearth surface or the top surface of the furnace, and a primary fuel injection port and a secondary fuel injection port for supplying the primary fuel and the secondary fuel to the combustion air in stages, In the fuel two-stage combustion burner device, in which the internal combustion gas circulation flow is mixed with the combustion air to reduce the oxygen concentration of the combustion air, and then the combustion air and the secondary fuel are mixed in the secondary combustion zone.
It is arranged between the secondary fuel injection port located on the inner surface of the furnace and the outlet opening of the burner throat, and has a weir protruding from the inner surface of the furnace so as to surround the outlet opening,
The weir causes the outer surface to change the direction of the secondary fuel jet injected by the secondary fuel injection port, and the combustion gas circulation flow in the furnace to flow along the furnace inner surface toward the opening edge of the outlet opening. A fuel two-stage combustion type burner device comprising an in-furnace combustion gas recirculation path.   A plurality of dam portions constituting the dam are arranged at intervals along an outer edge portion of the outlet opening, and the in-furnace combustion gas recirculation path is formed by a separation region of adjacent dam portions. The fuel two-stage combustion type burner device according to claim 1.   The dam portions have a generally arcuate and convex curved shape so as to bulge toward the outlet opening, and each dam portion has an arc shape in which a plurality of the secondary fuel jets can collide evenly. The fuel two-stage combustion type burner device according to claim 2, further comprising a concave outer surface. Combustion air flow is supplied from the burner throat opened to the furnace inner wall surface, furnace floor surface, or furnace top surface to the furnace area, and the circulation flow of the combustion gas in the furnace is mixed with the combustion air to produce oxygen in the combustion air. A fuel that reduces the concentration and supplies the primary fuel at the burner throat and the secondary fuel at the secondary fuel injection port arranged on the furnace surface to the combustion air in stages. In the two-stage combustion method,
By placing a weir between the secondary fuel injection port located on the furnace inner surface and the outlet opening of the burner throat, and surrounding the outlet opening by the weir protruding from the furnace inner surface, Change the direction of the secondary fuel jet injected by the fuel injection port,
An in-furnace combustion gas recirculation path is formed in the weir to cause the in-furnace combustion gas circulation flow to flow along the inner surface of the furnace toward the opening edge of the outlet opening and to flow out from the outlet opening to the in-furnace region. A fuel two-stage combustion method, wherein an in-furnace combustion gas is mixed with the combustion air.   The in-furnace combustion gas recirculation path is formed by separating the plurality of weir portions along the outer edge portion of the outlet opening, and forming the in-furnace combustion gas recirculation path by a separation region between adjacent weir portions. 5. The fuel two-stage combustion method according to 4.   The dam portion is curved in an arc shape and a convex shape so as to bulge toward the outlet opening, and a plurality of secondary fuel jets are caused to collide evenly with the arc-shaped and concave outer surface of the dam portion. 6. The fuel two-stage combustion method according to claim 5, wherein

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