JP5082505B2 - boiler - Google Patents

Description

  The present invention relates to a boiler. More specifically, the present invention relates to a boiler capable of reducing harmful substances that are burned by switching between liquid fuel such as kerosene and heavy fuel oil A and gas fuel.

  Conventionally, a boiler having a can having a group of water tubes arranged in an annular shape is well known, and in such a boiler, a burner is generally arranged at the center of the water tube group. . In other words, in the boiler having such a configuration, the inner side of the annular water tube group functions as a combustion chamber for burning the fuel supplied from the burner.

  Proposals have also been made regarding techniques for reducing harmful substances (NOx, CO, soot, etc.) in boilers that switch between this type of liquid fuel and gaseous fuel (see, for example, Patent Document 1).

By the way, in the boiler comprised using the can which has the water pipe group arranged in the above-mentioned ring shape, the gas exhaust port of a combustion chamber is 1 in the side surface of a combustion chamber like the can called the (omega) flow. In a can body provided with a bias in the circumferential direction, the gas ejected from the burner tends to be pulled in a specific direction (mainly the direction in which the gas discharge port is provided), that is, not axially symmetric. For this reason, the gas during the combustion reaction from the burner contacts the inner surface of the can body, and the gas ejected from the burner flows out from the vicinity of the burner at the gas outlet through a short path, thereby adversely affecting the combustion performance of the burner. In addition, it has been difficult to reduce the amount of exhausted NOx.

  Further, in a boiler that switches between liquid fuel and gaseous fuel and burns, it is necessary to satisfy the NOx emission standard in any combustion.

JP 11-108308 A

  The problem to be solved by the present invention is to provide a boiler that can realize reduction of harmful substances such as NOx during combustion of both liquid fuel and gaseous fuel.

The present invention has been made to solve the above problems, and the invention according to claim 1 is arranged in a can body in which a combustion chamber is formed using a plurality of water pipes, and an upper portion of the can body. A boiler provided with a gas discharge port of the combustion chamber on a side surface of the combustion chamber, wherein the burner is a burner used by switching between liquid fuel and gaseous fuel, with the liquid fuel nozzle portion being the center. A gas fuel supply pipe having a substantially annular flow passage arranged and having gas outlets formed on the inner peripheral surface and the outer peripheral surface, and a cylindrical shape arranged coaxially with the gas fuel supply pipe outside the gas fuel supply pipe An air register, a first air passage formed between the liquid fuel nozzle portion and the gaseous fuel supply pipe and having a first baffle plate at a tip thereof; and between the gaseous fuel supply pipe and the air register. Second empty formed and provided with a second baffle plate at the tip Is constituted by a flow path, the Second baffle secondary air injection portion formed in the plate, Bei give a flow control means for controlling the direction away a flow of gas injected from the gas outlet, the flame of the burner The detector is arranged above the secondary air ejection portion located on the gas discharge port side .

According to the first aspect of the present invention, the gas generated by the burner moves away from the gas discharge port by the function of the secondary air nozzle in both liquid fuel combustion and gaseous fuel combustion. Since it is controlled, deterioration of combustibility due to short path outflow from the gas discharge port can be suppressed, and harmful substances such as NOx can be reduced, and gas fuel combustion and liquid fuel combustion of the burner are possible. There is an effect that the flame detection at the time can be more reliably performed.

  A second aspect of the present invention is the secondary air nozzle according to the first aspect, wherein the flow control means is formed in a rectangular tube shape including a plate-like member that guides the ejected gas in a direction away from the gas discharge port. It is characterized by that.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, there is an effect that the flow of gas generated by the burner can be controlled with certainty.

  According to a third aspect of the present invention, there is provided an external exhaust gas recirculation means capable of selecting whether the exhaust gas discharged from the can body is supplied to the burner or stopped in the burner according to the first or second aspect, and the gas It is characterized in that exhaust gas is supplied to the burner during fuel combustion.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, there is an effect that it is possible to easily clear the regulation value of the gaseous fuel whose exhaust gas regulation is severe.

Further, according to a fourth aspect of the present invention, in the first or second aspect, the flow control means is formed in a cylindrical shape, and an ignition pilot burner for gaseous fuel combustion is provided inside the gaseous fuel supply pipe. The flame detector detects the flame of the pilot burner through a flame detection hole formed in the rectifying plate on the inlet side of the first air flow path and a flame detection hole formed in the first baffle plate. It is characterized by the construction.

According to invention of Claim 4, in addition to the effect by the invention of Claim 1 or 2, there exists an effect that the flame of the said pilot burner can also be detected with the said flame detector.

  According to the present invention, the gas generated by the burner can suppress deterioration of combustibility due to a short path flowing out from the gas discharge port, and NOx can be obtained both in liquid fuel combustion and in gas fuel combustion. A boiler capable of reducing harmful substances such as can be obtained.

  Before describing embodiments of the present invention, terms used in the present application will be described.

  In the present application, when simply referred to as “gas”, the gas is a concept including at least one of a gas during a combustion reaction and a gas for which the combustion reaction has been completed, and may also be referred to as a combustion gas. In other words, the gas includes both the gas in the combustion reaction and the gas in which the combustion reaction is completed, the gas in the combustion reaction only, or the gas in which the combustion reaction is completed only. It is a concept that includes. Hereinafter, the same concept is used unless otherwise described.

Further, the exhaust gas means a gas in which the combustion reaction is completed or almost completed. Further, unless otherwise specified, exhaust gas means either or both of the gas that passes through the boiler body and reaches the chimney and the gas that circulates in the body.

  Further, the gas temperature means the temperature of the gas during the combustion reaction unless otherwise specified, and is synonymous with the combustion temperature or the combustion flame temperature. Further, the suppression of the gas temperature means that the maximum value of the gas (combustion flame) temperature is kept low. In general, the combustion reaction is extremely small in the above-mentioned “gas for which the combustion reaction has been completed”, but continues, so “completion of the combustion reaction” means 100% completion of the combustion reaction. It is not a thing.

  Hereinafter, embodiments of the present invention will be described.

  First, a boiler according to the present embodiment includes a can body in which a combustion chamber is formed using a plurality of water pipes, and a burner disposed at an upper portion of the can body, and a gas discharge port of the combustion chamber is provided on a side surface of the combustion chamber. In the boiler provided in the above, the burner is a burner that switches between liquid fuel and gaseous fuel and has a substantially annular flow passage arranged around the liquid fuel nozzle portion, and has an inner periphery at the tip portion. A gas fuel supply pipe having gas jets formed on the surface and the outer peripheral surface; a cylindrical air register arranged coaxially with the gas fuel supply pipe; and the liquid fuel nozzle section and the gas fuel supply A first air passage formed between the pipe and the first baffle plate provided at the tip; and a second air formed between the gaseous fuel supply pipe and the air register and provided with the second baffle plate at the tip. And the second battery. The secondary air injection portion formed in the Le plate, and a flow control means for controlling the direction away a flow of gas injected from the gas outlet.

  According to such a configuration, during the liquid fuel combustion and the gas fuel combustion, the flow control action of the flow control means causes the jet gas from the burner to short-pass from the burner vicinity of the gas discharge port. Outflow is suppressed. As a result, it is possible to improve the combustion performance of the burner and reduce harmful substances. That is, when the liquid fuel is combusted, by suppressing the short path, gas drift from the burner is suppressed, so that the self-recirculation flow in the vicinity of the burner is improved, and the self-recirculation gas flows uniformly. Preevaporation and premixing of the fuel droplets are performed uniformly. As a result, pre-evaporation and premixing can suppress the generation of local low air ratio and high temperature fields, leading to low NOx. Further, even when the gas fuel is burned, the self-recirculation gas flows uniformly, so that the generation of a local low air ratio and high temperature field can be suppressed, leading to low NOx. Furthermore, since the gas show path flowing out from the gas discharge port is suppressed, it is possible to suppress the discharge of unburned components such as CO and soot (smoke). In addition, NOx reduction and suppression of unburned component outflow can be realized without substantially changing the structure of the burner.

  Next, each component of this embodiment will be described. This embodiment is preferably implemented for a can called a ω flow. The reason is that the flow control means has a large effect because the gas discharge port of the combustion chamber is at one place and the gas flow from the burner is relatively remarkable. The ω flow can body includes an inner water tube group (inner water tube wall) in which a large number of water tubes are arranged in an annular shape, and an outer water tube group (outer water tube wall) in which a large number of water tubes are arranged outside the inner water tube group. A combustion chamber is provided inside the inner water tube wall, and a first gas discharge port of the combustion chamber is provided at one place on the side surface of the inner water tube wall. Provide two gas outlets. In this can body, the gas flows out of the combustion chamber from the first gas discharge port, flows in two directions in an annular gas passage between the inner water tube wall and the outer water tube wall, It merges at the second gas discharge port and flows out of the can body.

However, the can body is not limited to the ω flow can body, and the can body that is easy to flow out by short-passing from the vicinity of the burner of the gas discharge port formed on the side of the combustion chamber, the gas ejected from the burner, The gas exhaust port of the combustion chamber includes a can other than the ω flow can that is formed at a plurality of locations on the side surface of the combustion chamber. Here, the fact that the gas discharge ports are formed unevenly means that the gas does not flow out almost uniformly from the entire side surface of the combustion chamber, but the gas flows out only from a specific position in the circumferential direction of the side surface of the combustion chamber. This means that the gas discharge port is formed at a specific position.

  The burner is a burner that can be used by switching between liquid fuel and gaseous fuel (which can be referred to as a switching exclusive combustion burner), and has a substantially annular cross-section with a liquid fuel nozzle portion for liquid fuel as a center. A gas fuel supply pipe in which gas outlets are formed on the inner peripheral surface and outer peripheral surface of the tip, a cylindrical air register disposed coaxially with the gas fuel supply pipe, A first air flow path formed between the liquid fuel nozzle portion and the gaseous fuel supply pipe and provided with a first baffle plate at the distal end; and formed between the gaseous fuel supply pipe and the air register; It is a premixing type burner provided with the 2nd air flow path which provided the two baffle board. The secondary air ejection part formed on the second baffle plate is provided with a flow control means for controlling the flow of the ejection gas in a direction away from the gas discharge port.

  This burner is a self-recirculating burner. The self-recirculating burner is a NOx gas by drawing a gas having a low oxygen concentration in the combustion chamber into the burner base by the gas ejected from the secondary air ejection section (including only air) and mixing it with the combustion air. A type of burner that suppresses generation. By combining the self-recirculation function of this self-recirculation burner with the flow control function of the flow control means, not only the CO and dust reduction effect but also the NOx reduction due to the improvement effect of the self-recirculation flow is achieved. This is a remarkable effect.

  Six to eight secondary air ejection portions are formed at intervals in the circumferential direction. The flow rate of the gas from the secondary air ejection part (secondary air ejection port) is preferably set in the range of 45 to 55 m / s. The reason is to ensure dust reduction and ignitability.

  The first aspect of the flow control means is configured to include 6 to 8 secondary air nozzles that guide the air ejected from the secondary air ejection section in a direction away from the gas exhaust port. These secondary air nozzles are preferably formed in a rectangular tube shape, and all the air nozzles are inclined toward the anti-gas discharge port side by inclining the constituent wall surface of the rectangular tube on the gas discharge port side. The air ejected from the next air ejection section can be guided in a direction away from the gas exhaust port. However, only the constituent wall surface of the secondary air nozzle on the gas outlet side may be inclined toward the anti-gas outlet side. The air nozzle can be configured to guide the air ejected from the air ejection portion in a direction away from the gas exhaust port by inclining the nozzle itself.

  The second aspect of the flow control means includes a guide for guiding at least a part of the air ejected from the secondary air ejection portion in a direction away from the gas discharge port, and a jet provided from the air ejection portion without the guide. And a diffusing portion that promotes diffusion of air. The guide is preferably formed in a U-shaped cross section.

  According to such a configuration, since not only the guide but also the diffusion portion is provided, the mixing state of the fuel and air injected from the liquid fuel nozzle portion is partially made uneven in the immediate vicinity of the burner. Can do. That is, according to the burner having such a configuration, the mixing state is not simply made good, but the gas temperature is lowered by forming a partly intentionally non-uniform mixing state by the diffusion portion, and NOx. The value can be reduced.

The first baffle plate has a first opening facing the liquid fuel nozzle portion at the center, a plurality of second openings arranged concentrically around the first opening, and used for ignition at the time of gas fuel combustion. And a third opening for ignition facing the pilot burner. The second opening is preferably formed at a position corresponding to the secondary air ejection portion as the same number as the secondary air ejection portion.

  An inner jet port as a gas jet port is formed in the vicinity of the upstream side of the first baffle plate on the inner peripheral surface of the distal end portion of the cylindrical gas fuel supply pipe, and the upstream side of the second baffle plate on the outer peripheral surface is formed. An outer jet port as a gas jet port is formed near the side. The inner jet port may be formed so as to be positioned between the adjacent second opening and the second opening, and the outer jet port may be formed corresponding to the secondary air jet part.

  The liquid fuel nozzle section is preferably composed of a first nozzle that sprays fuel necessary for low combustion during low combustion and a second nozzle that sprays fuel necessary for high combustion during high combustion. In this case, the central axis of the liquid fuel nozzle portion preferably coincides with the central axis of the tubular gaseous fuel supply pipe, the second nozzle is on the side close to the gas discharge port, and the first nozzle is It can be the anti-gas discharge side.

  In addition, the liquid fuel nozzle section may be composed of a first nozzle that sprays fuel at the time of low combustion and high combustion and a second nozzle that sprays fuel only at the time of high combustion, or the spray amount is adjusted by one nozzle. Can be configured. The central axis of the liquid fuel nozzle portion can be biased toward the anti-gas outlet side (in a direction away from the gas outlet) with respect to the central axis of the first cylinder member, that is, the central axis of the combustion chamber. Thereby, the gas from the said burner can be shifted to the whole anti-gas discharge port side, and the combustibility deterioration by providing the said gas discharge port biasing can be suppressed. The liquid fuel nozzle part can be referred to as a nozzle pipe.

  In this embodiment, it is preferable that an external exhaust gas recirculation unit capable of selecting supply and stop of exhaust gas discharged from the can body to the burner is provided, and exhaust gas is supplied to the burner during combustion of the gaseous fuel. Configure to supply.

  This external exhaust gas recirculation means is provided in the exhaust gas recirculation passage that communicates the exhaust cylinder of the can body and the burner, and whether or not the exhaust gas recirculation passage is provided in the exhaust gas recirculation passage (supply of exhaust gas). And a damper as a control means for controlling the above. One end of the exhaust gas recirculation path is connected to the suction side of a blower for sending combustion air to the burner. If necessary, another exhaust fan is provided in the exhaust gas recirculation path to the burner or the combustion chamber. It can be configured to supply exhaust gas.

  By adopting such a configuration, in addition to the low NOx action due to the performance of the burner during gas fuel combustion, a low NOx action due to exhaust gas recirculation can be added, and the NOx emission reference value is high (the reference NOx value is low). The standard value of the gas fired boiler can be easily cleared. This exhaust gas recirculation is only used for gaseous fuel combustion. When exhaust gas recirculation is performed during liquid fuel combustion, corrosion of the exhaust gas recirculation path due to sulfuric acid components contained in the exhaust gas is avoided, and during liquid fuel combustion. This is because the NOx emission standard value is relatively low. However, the exhaust gas recirculation can be performed as needed even during liquid fuel combustion. In this embodiment, instead of the exhaust gas recirculation, NOx reduction means such as water spray other than the exhaust gas recirculation can be combined.

In the embodiment described above, it is preferable that a flame at the time of gas fuel combustion and a flame at the time of liquid fuel combustion of the burner are detected by a common flame detector. The flame detector of the burner is preferably arranged above the secondary air jet port located on the gas discharge port side. The secondary air jets located on the gas discharge side are a plurality of secondary air jets formed at a predetermined interval on the side close to the gas discharge port and on the other side (the anti-gas discharge port side). When divided, it refers to a secondary air outlet located on the side close to the gas outlet.

  By adopting such a configuration, the following effects can be obtained. That is, the flow control means can improve that the flame of the burner is biased toward the gas discharge port, but cannot be a completely axisymmetric flame. Therefore, by providing the flame detector above the secondary air outlet located on the gas discharge side, the amount of the flame detection signal compared to the case provided above the secondary air outlet on the anti-gas discharge side. Therefore, it is possible to more reliably detect the flame at the time of burning the gas fuel and the liquid fuel of the burner.

  When detecting the flame of the pilot burner provided inside the gaseous fuel supply pipe with the same flame detector, the flame detection hole formed in the rectifying plate on the inlet side of the first air flow path and the first The flame detector is configured to detect the flame of the pilot burner through a flame detection hole formed in one baffle plate. More specifically, the position and size of each flame detection hole are adjusted. This size is restricted by the flow rate control because the rectifying plate and the first baffle plate have a function of controlling the flow rate of the primary air.

  In order for the flame detector to flame the pilot burner, two flame detector detection lines (a path through which a flame signal is connected between the flame of the pilot burner and the sensor part of the flame detector) The flame detection hole needs to be present. Further, it is necessary to make adjustments such as shortening the length so that the gaseous fuel supply pipe does not obstruct the detection line (so as not to get in the way). The detection line is set so as not to be blocked by the liquid fuel nozzle portion and the pilot burner.

  The present invention is not limited to the above-described embodiment. When the gas discharge port is formed up to the lower end of the burner or close to the flame formation start position, the gas may be prevented to prevent the short path. Shielding means (blocking means) for closing the upper part of the discharge port can be provided. As a specific form of the shielding means, when the gas discharge port is formed as a gap between the water pipe and the water pipe, a shielding plate for shielding the upper end portion of the gap is used. The length of the shielding plate in the vertical direction is about 250 mm to 400 mm. In this aspect, the shielding part which has the function similar to the said shielding board can be comprised with the said water pipe by forming the upper part of a water pipe in flat shape. The shielding plate can form an opening in a part thereof so as not to impair the effect of suppressing the short path. Moreover, it can also consist of a plurality of shielding plates.

  In this short path prevention configuration, when the gas discharge port is wider than the outer diameter of one water pipe, one or a plurality of water pipes are arranged at the gas discharge port so that a gap between adjacent water pipes is removed from the gas discharge port. It can be configured as an outlet, and the upper part of the gap is closed by the shielding plate. The shielding plate is preferably a metal, but can be made of a refractory material such as castable. When using a castable, it can comprise so that the upper part of the said gas exhaust port may be filled up.

  Further, in such a configuration in which a water pipe is arranged at the gas discharge port, the water pipe is narrowed at the outer diameter of the lower part, and the upper part of the gas discharge port is closed by contacting the water pipe and the adjacent water pipe at the upper part. Accordingly, the burner and the gas discharge port can be configured to be separated from each other. In this case, gas flows out from a gap formed in the lower part between this water pipe and the adjacent water pipe, and functions as a gas outlet. According to such a configuration, since the width of the shielding plate can be narrowed, deformation due to thermal stress of the shielding plate can be reduced, and the durability of the shielding plate can be improved.

  Hereinafter, the boiler concerning Example 1 of the present invention is explained based on a drawing.

  FIG. 1 is a schematic diagram of a boiler according to a first embodiment of the present invention. Here, FIG. 1 shows an explanatory view of a longitudinal section of the boiler according to the first embodiment. Moreover, FIG. 2 has shown explanatory drawing of the cross section which follows the II-II line | wire of FIG. 3 and 4 are schematic views of a burner provided in the boiler according to the first embodiment. Here, FIG. 3 shows an explanatory view of a longitudinal section of the burner according to the first embodiment, and FIG. 4 shows a bottom view of the burner shown in FIG. Further, FIG. 5 is a diagram for explaining the gas ejection position in the first embodiment, and FIG. 6 is a diagram showing a schematic diagram of the combustion state (gas flow) of the boiler according to the first embodiment.

  As shown in FIGS. 1 and 2, a boiler 1 according to the first embodiment includes a can body 10 having a water tube group arranged in an annular shape, and an upper portion of the can body 10 at a central portion of the water tube group. The self-recirculation type is provided and is configured using a burner 20 that switches between combustion of gaseous fuel and combustion of liquid fuel. A wind box 50 for supplying combustion air to the burner 20 is provided above the burner 20.

  The can body 10 is configured by standing a plurality of water pipe groups (an inner water pipe group 13 and an outer water pipe group 14) between an upper header 11 and a lower header 12. Each of the water tube groups 13 and 14 is arranged in a substantially concentric annular shape, and an outer water tube group 14 is provided at a predetermined interval from the inner water tube group 13, and between the inner water tube group 13 and the outer water tube group 14. An annular gas flow path 15 is formed at the end. Further, in the first embodiment, the inside of the annular water pipe groups 13 and 14 functions as the combustion chamber 16, and the burner 20 is provided above the combustion chamber 16. .

  Further, the inner water tube group 13 is configured as an annular water tube wall in a state where the inner water tubes 13a are in close contact with each other or in a state where the adjacent inner water tubes 13a are connected by inner fin portions 13b. A gas discharge port 17 is provided in a part. The gas discharge port 17 is opened along the longitudinal direction of the water pipe and functions to guide the gas generated in the combustion chamber 16 inside the inner water pipe group 13 to the annular gas flow path 15.

  The outer water tube group 14 is formed in an annular shape with a substantially uniform predetermined interval between the outer water tubes 14a, and a gap between adjacent outer water tubes 14a is formed between the outer water tubes 14a. Outer fin portions 14b connected to be eliminated are provided. A part of the outer water tube group 14 is provided with an outer opening (second gas discharge port) 19, and the outer opening 19 allows a gas whose combustion reaction has been almost completed to flow outside the can body 10. Functions as a discharge unit for discharging. That is, the gas generated by the burner 20 is collected in the outer opening 19 and then discharged to the outside of the can body 10 through the exhaust cylinder 18 provided at a position below the can body 10.

  As shown in FIGS. 3 and 4, the burner 20 is installed on a wind box wall 51 as air supply means for supplying combustion air to the burner 20. Specifically, the mounting plate 21 constituting the burner 20 is mounted on the wall 51 from above, and the mounting plate 21 is fastened to the wall 51 by fastening means (not shown) such as bolts. Thus, the burner 20 is installed in the wind box 50.

As shown in FIGS. 3 and 4, the burner 20 according to the first embodiment includes a liquid fuel nozzle portion 22 at the center thereof, and a gaseous fuel supply pipe having a flow passage having a substantially annular cross section around the nozzle portion 22. 23 and a cylindrical air register 24 are arranged coaxially. A first air passage 25 through which primary air flows is formed between the nozzle portion 22 and the gaseous fuel supply pipe 23, and secondary air flows between the gaseous fuel supply pipe 23 and the air register 24. A second air flow path 26 is formed. The combustion air is supplied by a blower 27 that supplies air into the wind box 50. The ratio of primary air to secondary air is set to 5 to 15% for primary air and 85 to 95% for secondary air. The liquid fuel and the gas fuel are alternatively switched and supplied.

  The liquid fuel nozzle portion 22 includes a first liquid fuel nozzle 22a for low combustion and a second liquid fuel nozzle 22b for high combustion. That is, the liquid fuel is sprayed from the second liquid fuel nozzle during high combustion, and the liquid fuel is sprayed from the first fuel nozzle 22a during low combustion. A first baffle plate 28 is provided at the tip of the first air flow path 25, that is, at a downstream position of the liquid fuel nozzle portion 22. The first baffle plate 28 includes a first opening 29 in the center, eight second openings 30, 30,... Around the first opening 29, and a third opening 32 into which the tip of the pilot burner 31 is inserted. ing. The inlet side and upper end of the first air passage 25 are closed by a rectifying plate 25A, an opening through which the liquid fuel nozzle portion 22 penetrates and an opening through which a pilot burner 31 (described below is omitted) and primary air An opening (not shown) for adjusting the amount is formed.

  An annular second baffle plate 33 is provided at the tip of the second air flow path 26. As shown in FIG. 4, the second baffle plate 33 is provided with eight secondary air ejection portions 34 (34 a to 34 h) substantially evenly in the circumferential direction, and the air supplied from the wind box 50 is Not only the first opening 29 and the second opening 30 but also the secondary air ejection portion 34 is ejected to the combustion chamber 16 side. And by making secondary air distribute | circulate to each this secondary air ejection part 34 (flow velocity is 45-55 m / s), and dividing | segmenting secondary air by this each secondary air ejection part 34, and supplying to fuel, A split flame is formed so that low NOx can be realized.

  At the tip of the gaseous fuel supply pipe 23, a plurality of outer jets 35, 35,... For jetting gaseous fuel outward, and a plurality of inner jets 36, 36,. Is provided. A plurality of these outer jets 35 and inner jets 36 are provided at intervals in the circumferential direction so that the total opening area of the outer jets 35 is larger than the total opening area of the inner jets 36. ing. Reference numeral 37 denotes a gaseous fuel introduction pipe for supplying gaseous fuel to the gaseous fuel supply pipe 23. Although only one inner jet port 36 is shown in FIG. 3, it is formed from a plurality of small hole groups. In addition, a plurality (two in the first embodiment) of the outer jets 35 are formed.

  Each outer ejection port 35 is formed so that gas is ejected at a position corresponding to each secondary air ejection portion 34, as shown by the solid arrows in FIG. Moreover, each said inner side ejection port 36 is formed so that gas may spout between adjacent said 2nd opening 30 and said 2nd opening 30, as shown by the double line arrow of FIG.

  As shown in FIGS. 3 and 4, the secondary air ejection portion 34 is provided around the liquid fuel nozzle portion 22. The secondary air ejection portion 34 is configured so that the gas generated by the burner 20 does not cause a short path from the gas discharge port 17 provided in the can 10. It is comprised so that the flow of the air ejected from may be controlled.

  That is, in the secondary air ejection part 34, the air ejected from each secondary air ejection part 34 (first secondary air ejection part 34 a to eighth secondary air ejection part 34 h) is supplied to the gas exhaust port 17. A secondary air nozzle 38 (first secondary air nozzle portion 38a to eighth secondary air nozzle portion 38h) that has a rectangular tube shape that leads in a direction away from the main body.

More specifically, in the first embodiment, the second baffle plate (secondary air supply plate) 33 is used.
Eight substantially trapezoidal through-holes 39 (first through-hole 39a to eighth through-hole 39h) are perforated, and the secondary air nozzle 38 (first air nozzle 38a to eighth-eighth) is inserted into each through-hole 39. An air nozzle 38h) is connected.

  Each of the secondary air nozzles 38 includes a first secondary air nozzle 38a to an eighth secondary air nozzle 38h to guide the air ejected from each secondary air ejection section 34 in a direction away from the gas exhaust port 17. The first cylinder constituting wall 40a to the eighth cylinder constituting wall 40h on the side close to the gas outlet 17 are inclined (inclined in the opposite direction to the gas outlet 17 ("right side" in FIG. 3)). Yes. More specifically, the first secondary air nozzle 38a, the second secondary air nozzle 38b, the seventh secondary air nozzle 38g, and the eighth secondary air nozzle 38h on the left side of the two-dot chain line in FIG. The first cylinder constituting wall 40a, the second cylinder constituting wall 40b, the seventh cylinder constituting wall 40g, and the eighth cylinder constituting wall 40h on the side far from the liquid fuel nozzle portion 22 are inclined. Further, the third secondary air nozzle 38c, the fourth secondary air nozzle 38d, the fifth secondary air nozzle 38e, and the sixth secondary air nozzle 38f on the right side of the two-dot chain line in FIG. The third cylinder constituting wall 40c, the fourth cylinder constituting wall 40d, the fifth cylinder constituting wall 40e, and the sixth cylinder constituting wall 40f on the side close to the fuel nozzle portion 22 are inclined. It is preferable that the inclination angle θ (attachment angle) of the first to eighth cylinder constituting walls is about 5 ° to 30 °. Of course, the inclination angle θ is set so that the gas in the flame state does not contact the inner water pipe 13a.

  Further, referring to FIG. 1, the boiler 1 according to the first embodiment includes an external exhaust gas recirculation means 41 that supplies a part of the exhaust gas flowing through the exhaust pipe 18 to the burner 20.

  The external exhaust gas recirculation means 41 is provided in the exhaust gas recirculation path 42 that connects the exhaust cylinder 18 of the can 10 and the intake port (reference number omitted) of the blower 27, and the exhaust gas recirculation path 42. The first damper 43 as control means is configured to control whether or not to perform exhaust gas recirculation (exhaust gas supply). In the first embodiment, the first damper 43 is configured to open during gas fuel combustion to supply exhaust gas, and close during liquid fuel combustion to stop supply of exhaust gas. The second damper 45 provided in the combustion air flow path 44 that communicates the blower 27 and the wind box 50 has a function of switching between a low combustion air amount and a high combustion air amount. The air volume switching between the low combustion and the high combustion can be performed by using an inverter as a rotation speed control device of the blower 27.

  The operation of the boiler 1 configured as described above and according to the first embodiment will be described with reference to the drawings.

(When burning liquid fuel)
First, the operation of liquid fuel combustion will be specifically described below with reference to FIG. 6 in addition to FIGS. FIG. 6 is a schematic diagram showing the gas flow in the can during low combustion. In FIG. 6, the gas flow state diagram (gas F0) indicated by the broken line is different from the first embodiment in the burner structure, and the gas shape (flame shape) when the air from the burner is ejected in a substantially vertical manner. A gas flow state diagram (gas F1) indicated by a solid line indicates a gas shape (flame shape) formed by the burner 20 according to the first embodiment.

  When the burner 20 according to the first embodiment is operated in a low combustion state, first, a liquid fuel valve (not shown) that controls supply and stop of liquid fuel to the liquid fuel nozzle portion 22 is opened, and the gas A gaseous fuel valve (not shown) for controlling supply and stop of gaseous fuel to the fuel introduction pipe 37 is closed. Then, with the first damper 43 closed, the blower 27 is driven to supply air to the first air flow path 25 and the second air flow path 26 via the wind box 50. Next, a spark rod (not shown) as an igniter is energized, gaseous fuel is supplied to the pilot burner 31 and burned, and liquid fuel is sprayed from the first liquid fuel nozzle 22a to burn it. Start.

  That is, in the first embodiment, the first opening 29, the second opening 30, and the secondary air ejection portion 34, that is, the second air ejection portion 34, that is, the first air passage 25 and the second air passage 26, respectively. Air is ejected from the secondary air nozzle 38, and mixing of the air and the liquid fuel sprayed from the first liquid fuel nozzle 22a is performed. Then, the flame formed by the pilot burner 31 ignites the liquid fuel mixed with air. By this ignition, the liquid fuel sprayed from the first liquid fuel nozzle 22a is combusted, and the low combustion state is maintained as long as the liquid fuel is continuously sprayed from the first liquid fuel nozzle 22a. Further, when the liquid fuel is supplied from the second liquid fuel nozzle 22b, the burner 20 is in a high combustion state.

  In the burner 20 according to the first embodiment, the fuel supply state in the liquid fuel nozzle portion 22 is appropriately switched (on / off control), thereby switching to any one of the stopped state, the low combustion state, and the high combustion state. Is possible. That is, when the combustion state continues, switching from low combustion to high combustion or from high combustion to low combustion is possible.

  The amount of combustion air supplied to the burner 20 is adjusted using the second damper 45. And this combustion air is supplied corresponding to the supply amount of liquid fuel. For example, in a burner configured using two nozzle tips having similar fuel supply performance, the amount of air supplied when the liquid fuel is sprayed from the first liquid fuel nozzle 22a (during low combustion) is set to “1”. ", The amount of air supplied when the liquid fuel is sprayed from the second liquid fuel nozzle 22b (at the time of high combustion) is set to" 2. " In the first embodiment, such adjustment of the air amount is performed using the second damper 45.

  Now, in the boiler 1 configured and functioning as described above, as shown in FIG. 6, when the burner 20 is in a low combustion state, the inside of the can 10 is substantially uniform with the central portion of the combustion chamber 16 as a substantially center. A gas F <b> 1 (solid line) that spreads out is formed. The gas F1 having such a shape is formed because the secondary air ejection part 34 provided around the liquid fuel nozzle part 22 devise the secondary air nozzle 38, thereby The flow of the air ejected from the secondary air ejection section 34 is controllable so that the gas generated in the burner 20 from the gas exhaust port 17 provided in the body 10 does not short-path. Because.

  If the secondary air nozzle 38 as in the first embodiment is not provided, the gas generated in the burner 20 is pulled toward the gas discharge port 17 so that the inside of the combustion chamber 16 The gas formed in is as shown by a gas F0 indicated by a broken line in FIG. In other words, the conventionally known boiler is not provided with the secondary air nozzle 38 for controlling the gas flow as shown in the first embodiment so as to be away from the gas discharge port 17. It is considered that the gas F0 having such a shape was formed in the chamber 16. In such a case, the gas is pulled toward the gas discharge port 17 in the combustion chamber 16, so that problems such as hindering the exhaust gas circulation flow in the combustion chamber 16 occur.

  However, in the first embodiment, as described above, by providing the secondary air nozzle 38, the gas F1 spread uniformly in the combustion chamber 16 can be formed. Therefore, according to the first embodiment, the following effects can be obtained.

That is, the gas generated in the burner 20 is prevented from being short-passed from the gas discharge port 17 provided in the combustion chamber 16 by the secondary air nozzle 38, so that the combustion performance of the burner 20 is achieved. Can be achieved, and reduction of harmful substances can be realized. That is, the drift of the gas from the burner 20 is suppressed (the gas is suppressed from being pulled toward the gas discharge port 17), the self-recirculation flow in the vicinity of the burner 20 is improved, and the self-recirculation is uniformly performed. Gas flows in, pre-evaporation and pre-mixing are performed uniformly, and an appropriate split flame is formed. As a result, the pre-evaporation and premixing of the fuel droplets suppress the generation of a local low air ratio / high temperature field, and the formation of an appropriate split flame increases the surface area of the gas F1 and increases the gas temperature. descend. Thereby, low NOx can be realized. Further, since the gas show path flowing out from the gas discharge port 17 is suppressed, the discharge of unburned components such as CO and soot can be suppressed.

(At the time of gas fuel combustion)
Next, the operation at the time of gaseous fuel combustion will be described. With reference to FIG. 1, when operating the burner 20 according to the first embodiment in a low combustion state, the blower 27 is driven with the liquid fuel valve closed and the first damper 43 open. Air is supplied to the first air passage 25 and the second air passage 26 through the window box 50. And after igniting the pilot burner 31 using the spark rod, the gaseous fuel valve is opened to a low combustion state.

  In the burner 20 according to the first embodiment, by switching the gaseous fuel supply amount to the gaseous fuel introduction pipe 37, switching to any of the stopped state, the low combustion state, and the high combustion state is possible. . That is, when the combustion state continues, switching from low combustion to high combustion or from high combustion to low combustion is possible.

  The operation at the time of low combustion during the gaseous fuel combustion will be described. Since the operation during high combustion is basically the same as that during low combustion, the description thereof is omitted. Referring to FIG. 3, gaseous fuel is ejected from the outer ejection port 35 and the inner ejection port 36, and the gaseous fuel ejected from the inner ejection port 36 is mixed with primary air from the first air flow path 25. A small flame is formed at a downstream position of the first baffle plate 28. This small flame acts as a seed flame and improves flame holding properties. The gaseous fuel ejected from the outer ejection port 35 is mixed with the secondary air from the second air flow path 26, and ejected from the secondary air nozzles 38 a to 38 h, and downstream of the second baffle plate 29. A large flame is formed at the position. Secondary air was divided and supplied by each of the secondary air nozzles 38a to 38h to form a divided flame, and at the same time, low NOx could be achieved by self-recirculation.

  Also during the gaseous fuel combustion, the gas generated in the burner 20 is discharged from the gas discharge port 17 provided in the combustion chamber 16 by the secondary air nozzle 38, as in the liquid fuel combustion described above. Since short-passing is suppressed, the combustion performance of the burner 20 can be improved and NOx reduction can be realized.

  In the first embodiment described above, the flow rate of secondary air from each of the secondary air nozzles 38a to 38h is set to a relatively high value of 45 to 55 m / s, thereby reducing dust during oil combustion. can do.

  Further, a part of the exhaust gas discharged from the exhaust pipe 18 by the exhaust gas recirculation by the exhaust gas recirculation means 41 is sucked by the blower 27 through the exhaust gas recirculation path 42, and the wind box 50 Supplied to. As a result, the combustion became slow due to the decrease in the oxygen concentration, the flame temperature formed by the burner 20 was suppressed, and NOx was reduced, so that a further reduction in NOx could be achieved.

  This invention is not limited to the said Example 1, The said secondary air ejection part 34 can be comprised like FIG.

  The secondary air ejection part 34 of the second embodiment has at least a part of air ejected from each secondary air ejection part 34 (first secondary air ejection part 34a to eighth secondary air ejection part 34h). Guides 46 (first guide 46a to eighth guide 46h) guided in a direction away from the gas discharge port 17, and secondary air ejection portions 34 (first secondary air ejection portion 34a to eighth secondary air ejection portion 34h). ) Has a diffusion part 47 (first diffusion part 47a to eighth diffusion part 47h) that promotes diffusion of air ejected from.

  In the second embodiment, as in the first embodiment, eight substantially trapezoidal through holes 39 (first through hole 39a to sixth through hole 39h) are drilled. The difference from the first embodiment is that the guide 46 (first guide 46a to sixth guide) is formed using a plate-like member on the side of the gas discharge port 17 in each through hole 39 ("left side" in FIG. 7 of this embodiment). A guide 46h) is constructed. The guide 46 is configured to cover a part of each of the through holes 39. In the second embodiment, a portion not covered by the guide 46 is ejected from the secondary air ejection portion 34. It functions as a diffusion part 47 (first diffusion part 47a to eighth diffusion part 47h) that promotes the diffusion of the air.

  Each guide 46 keeps at least a part of air ejected from each secondary air ejection portion 34 (mainly, air in a region covered by the guide 46 of the through hole 39) away from the gas discharge port 17. In order to guide in the direction, the plate-like member is inclined (inclined in the direction opposite to the gas discharge port 17 ("right side" in FIG. 7)). In this case, the inclination angle θ (mounting angle) is preferably about 5 ° to 30 °.

  Further, the height of each guide 46 is set so that the liquid fuel sprayed in a cone shape (triangular pyramid shape with the nozzle portion 22 as a vertex) from the liquid fuel nozzle portion 22 does not contact each guide 46. Has been. In the second embodiment, the fifth guide 46e illustrated on the right side of FIG. 7 is provided at a position where the fifth guide 46e is in contact with the liquid fuel more easily than the first guide 46a illustrated on the left side. Is provided lower than the first guide 46a. This is because the fuel injection angle by the burner 22 is wider than that in the first embodiment.

  As described above, the diffusion portion 47 (the first diffusion portion 47a to the eighth diffusion portion 47h) is a portion of the through hole 39 that is not covered with the guide 46 (a region surrounded by a broken line in FIG. 7). It is. Since this part (diffusion part 47) is not provided with an element for rectifying the air supplied via the second air flow path 26 such as the guide 46 or the like, it is ejected from the diffusion part 47. The air will expand rapidly.

  Therefore, in the burner 20 of the second embodiment, the air ejected from the secondary air ejecting portion 34 is guided in the direction away from the gas exhaust port 17 by the guide 46 and a part thereof is the diffusing portion. The diffusion is promoted by 47.

  Also in the boiler 1 according to the second embodiment, although not shown, basically, the central portion of the combustion chamber 16 in the can 10 is substantially the same as in FIG. A gas F1 (solid line) spread uniformly as a center is formed. The gas F <b> 1 having such a shape is formed by the secondary air ejection portion 34 provided around the liquid fuel nozzle portion 22 from the gas exhaust port 17 provided in the combustion chamber 16. This is because the flow of air ejected from the secondary air ejecting section 34 is configured to be controllable so that the gas generated by the burner 20 does not short pass.

Further, the secondary air ejection part 34 constituting the burner 20 according to the second embodiment has the diffusion part 47 together with the guide 46 that exhibits the various effects described above. As described above, the diffusion portion 47 is a portion of the through hole 39 that is not covered with the guide 46 (see FIG. 7). In other words, since the diffusion portion 47 is not provided with an element for rectifying air, such as the guide 46, the air ejected from the diffusion portion 47 flows into the edge portion of the diffusion portion 46 (the A sudden enlargement occurs at the edge portion of the through-hole 39. Then, in the immediate vicinity of the burner 20, a small turbulence occurs in the air, and the mixing state of the liquid fuel sprayed from the liquid fuel nozzle portion 22 and the air can be made partially uneven. Since the burner 20 according to the second embodiment has such a diffusing portion 47, the mixing state is not simply improved, and a partly intentionally uneven mixing state can be formed. That is, in the second embodiment, by providing the diffusing portion 47, it becomes possible to form a light and dark combustion state in the vicinity of the burner 20, so that the gas temperature can be lowered and the NOx value can be reduced. it can.

  As described above, the boiler 1 according to the second embodiment is appropriately formed in the can body 10 by reducing the gas temperature by sufficiently expanding the gas F1 in the combustion chamber 16 of the can body 10. NOx reduction is achieved by the synergistic effect of the gas temperature decrease due to the exhaust gas circulation flow, the gas temperature decrease due to the formation of an appropriate split flame, and the gas temperature decrease due to the concentration combustion formed by the diffusion portion 47. Can be planned.

  Next, Embodiment 3 of the present invention will be described with reference to FIG. The third embodiment is basically the same as the first embodiment, and differs from the first embodiment in that an ejection pipe 48 is provided at each outer ejection port 35 of the first embodiment as shown in FIG. is there. By adopting such a configuration, it was possible to reduce the exhausted NOx value as compared with Example 1. The reason is that by providing the ejection pipe 48, the flame can be expanded in the radial direction, the surface area of the flame is increased, the flame temperature is lowered, and NOx is reduced. The ejection pipe 48 of the third embodiment can also be applied to the second embodiment.

  One or a plurality of the ejection pipes 48 may be provided for each of the first secondary air nozzle 38a to the eighth secondary air nozzle 38h. Further, the outer jet port 35 provided with the jet pipe 48 and the outer jet port 35 provided with no jet pipe 48 can be provided. Further, preferably, as shown in FIG. 9, the ejection pipe 48 includes the first secondary air nozzle 38a, the second secondary air nozzle 38b, and the seventh secondary air near the gas discharge port 17. The numbers of the air nozzles 38g and the eighth secondary air nozzle 38h are determined based on the third secondary air nozzle 38c, the fourth secondary air nozzle 38d, the fifth secondary air nozzle 38e on the side far from the gas discharge port 17. And more than the sixth secondary air nozzle 38f (in FIG. 9, the number of the ejection pipes 48 on the near side is two and the number on the far side is zero). Furthermore, the protruding lengths and tube diameters of the plurality of ejection pipes 48, 48,... Can be varied as required.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the fourth embodiment, the flame at the time of gas fuel combustion by the burner 20, the flame at the time of liquid fuel combustion and the flame by the pilot burner 31 in the first embodiment are detected by one common flame detector 52. It is configured. FIG. 10 is an explanatory view of a longitudinal section of the main part of the fourth embodiment in a state in which the liquid fuel nozzle portion 22 and the pilot burner 31 are omitted, and FIG. 11 shows the wind box 50 in FIG. FIG. 12 is a sectional view taken along line XII-XII in FIG. 10, FIG. 13 is an enlarged sectional view taken along line XIII-XIII in FIG. 10, and FIG. It is expansion explanatory drawing of the bottom face seen from the downward direction.

The fourth embodiment has a smaller boiler as a whole compared to the first embodiment, but basically has the same configuration as the first embodiment, and the length of the gaseous fuel supply pipe 23 is The configuration for detecting three flames by a single flame detector 52 is different from that of the first embodiment. Hereinafter, different parts will be mainly described, and common parts will be denoted by the same reference numerals, and description thereof will be omitted. Moreover, the component of the said Example 1 which is not demonstrated is also provided.

  The flame detector 52 has a known structure with a built-in sensor unit 53 made of a CdS cell, and is fixed to the upper wall 54 of the window box 50. The mounting position is above the secondary air ejection portion 34b located on the gas discharge port 17 side. Here, the secondary air ejection part located on the side of the gas exhaust 17 means the first secondary air ejection part 34a to the eighth secondary air ejection part 34h as shown in FIG. 12 and FIG. When divided into the side closer to the outlet 17 (left side of the two-dot chain line in FIGS. 12 and 14) and the other side (antigas outlet 17) (right side of the two-dot chain line in FIGS. 12 and 14) In the fourth embodiment, the secondary air ejection part 34b is used as the second secondary air ejection part 34b. The gas discharge port 17 is formed at the tip of the arrow X direction in FIGS.

  Further, in the fourth embodiment, the pilot burner 31 shown in FIGS. 13 and 14 is disposed so as to be located behind the liquid fuel nozzle portion 22 in FIG. The flame of the pilot burner 31 is detected by the same flame detector 52. That is, through the first flame detection hole 55 formed in the upper wall 54, the second flame detection hole 56 formed in the rectifying plate 25A, and the third flame detection hole 57 formed in the first baffle plate 28, the A flame detector 52 is configured to detect a flame formed by the pilot burner 31.

  In order to achieve this, in the fourth embodiment, the position and size of each flame detection hole are adjusted. These sizes are adjusted within the limits of flow rate control because the rectifying plate 25A and the first baffle plate 28 have a function of controlling the flow rate of primary air.

  In order for the flame detector 52 to flame the pilot burner 31, as shown in FIG. 10, the first flame detection hole 55 formed in the wind box 50, and the second current formed in the rectifying plate 25A. The flame detection hole 56 and the third flame detection hole 57 formed in the first baffle plate 28 are paths through which flame light connects the flame part of the pilot burner 31 and the sensor part 53 of the flame detector 52. It is configured to be positioned on the first detection line 58A. Further, the length of the gaseous fuel supply pipe 23 is shorter than that of the embodiment of FIG. 1 so as not to block the first detection line 58A. Further, the first detection line (optical path) 58 </ b> A is formed so as not to be blocked by the liquid fuel nozzle portion 22 and the pilot burner 31.

  Further, the flame at the time of gas fuel combustion by the burner 20 and the flame at the time of liquid fuel combustion are detected in the optical path of the second detection line 58B passing through the first flame detection hole 55 and the second through hole 39b. It is comprised so that it may be detected with the instrument 52.

  Referring to FIG. 11, in addition to the first flame detection hole 55, the upper wall 54 has a fourth opening 59 through which the pilot burner 31 passes and a fifth opening 60 through which the liquid fuel nozzle part 22 passes. 60 is formed.

  Referring to FIG. 12, in addition to the second flame detection hole 56, the rectifying plate 25A has a sixth opening 61 through which the pilot burner 31 passes and a seventh opening through which the liquid fuel nozzle portion 22 passes. 62 and 62 are formed, and an eighth opening 63 through which primary air flows is formed.

Further, referring to FIGS. 13 and 14, the first baffle plate 28 has a large ninth through which the liquid fuel nozzle portion 22 and the parrot burner 31 penetrate in addition to the third flame detection hole 57. An opening 64 and a tenth opening 65 as an air hole are formed. Reference numeral 66 denotes an ignition insulator. The ninth opening 64 and the tenth opening 65 are formed with the intention of expanding the setting range of the first detection line 58A.

  The operation of the fourth embodiment having the above configuration will be described. The flame at the time of burning the liquid fuel of the burner 20 is formed as shown by F1 in FIG. The flame is detected by the flame detector 52 through the second detection line 58B shown in FIG.

  The flame at the time of gas fuel combustion is detected by the flame detector 52 in substantially the same manner as at the time of liquid fuel combustion. At the time of this gaseous fuel combustion, the pilot burner 31 is ignited and the main flame is controlled. The flame of the pilot burner 31 is detected through the first detection line 58A shown in FIG.

  According to the fourth embodiment, it is formed by improving the bias toward the gas discharge port 17 side by the flow control action of the secondary air ejection portion 34, but it cannot be a perfectly axisymmetric flame. . However, since the flame detector 52 is provided above the secondary air ejection part 34b located on the gas discharge 17 side, it is compared with the case where it is provided above the secondary air ejection part on the anti-gas discharge 17 side. As a result, the amount of the flame detection signal is increased, and the flame detection at the time of gas fuel combustion and liquid fuel combustion of the burner 20 can be performed more reliably.

  Further, since the secondary air ejection portion 34 is formed in a cylindrical shape, it is impossible to detect the flame of the pilot burner 31 through the second through hole 39b. However, according to the fourth embodiment, the flame of the pilot burner 31 is reliably detected through the first detection line 58A even if the installation position of the pilot burner 31 is arranged on the side opposite to the gas discharge port 17. And ignitability can be improved.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made as necessary within a range that can be adapted to the spirit of the present invention. Both are included in the technical scope of the present invention. For example, in Example 1 and Example 2 mentioned above, each component wall 40a-40h of the said secondary air nozzle 38 provided in each secondary air ejection part 34 and the said guide 46 are the same in the same direction. Although the case where it is provided to be inclined at an angle has been described, the present invention is not limited to this configuration. Therefore, for example, the installation inclination angles of the respective constituent walls 40a to 40h and the guides 46a to 46h may be appropriately changed.

  Further, in the above-described second embodiment, the case where the guide 46 is configured using a plate-shaped member (scoop type) having a U-shaped cross section has been described, but the present invention is not limited to this configuration, Any configuration may be employed as long as at least a part of the air ejected from the secondary air ejecting portion 34 can be guided away from the gas discharge port 17. Therefore, for example, the guide 46 may be configured by using a single flat plate member. Specifically, a flat plate-like member may be provided on the “one side” of the through hole 39 that forms each secondary air ejection portion 34 closest to the gas discharge port 17 so as to be inclined. Even with such a configuration, it is possible to guide at least a part of the air ejected from the secondary air ejecting portion 34 in a direction away from the gas exhaust port 17, thereby obtaining the various effects described above. be able to.

In the first and second embodiments described above, the center between the second liquid fuel nozzle 22b for high combustion and the first liquid fuel nozzle 22a for low combustion overlaps the central axis of the gaseous fuel supply pipe 23. However, the second liquid fuel nozzle 22b is disposed on the central axis of the gaseous fuel supply pipe 23, and the first liquid fuel nozzle 22a is moved away from the gas discharge port 17 with respect to the central axis. It can be spaced apart on the side. The present invention can also be applied to a burner that switches between a low combustion amount and a high combustion amount by a single nozzle (not shown).

  Further, in each of the above embodiments, the type of liquid fuel was not particularly described, but the present invention is not limited to a specific liquid fuel or gas fuel, and liquids such as kerosene, A heavy oil, B heavy oil, C heavy oil, etc. About fuel, it is applicable about gaseous fuels, such as 13A, LPG, and 12A.

It is explanatory drawing of the longitudinal cross-section of the boiler concerning Example 1 of this invention. It is explanatory drawing of the cross section which follows the II-II line | wire of FIG. It is explanatory drawing of the longitudinal cross-section of the burner concerning the present Example 1. FIG. FIG. 4 is a bottom view of the burner shown in FIG. 3. It is a figure explaining the gas ejection position of the present Example 1. It is the schematic which shows the flow of the gas at the time of low combustion. It is explanatory drawing of the longitudinal cross-section corresponding to FIG. 3 of the boiler concerning the other Example 2 of this invention. It is explanatory drawing of the longitudinal cross-section corresponding to FIG. 3 of the boiler concerning the other Example 3 of this invention. FIG. 6 is a schematic view seen from the lower surface of a burner in a modification of Example 3. It is explanatory drawing of the principal part longitudinal cross-section of the present Example 4. In FIG. 10, it is explanatory drawing of the plane which looked at the wind box 50 from the upper direction. It is the XII-XII sectional view taken on the line in FIG. It is the XIII-XIII line expanded sectional view in FIG. It is expansion explanatory drawing of the bottom face which looked at the burner 20 of the present Example 4 from the downward direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Boiler 10 ... Can body 16 ... Combustion chamber 17 ... Gas discharge port 18 ... Exhaust pipe 20 ... Burner 22 ... Liquid fuel nozzle part 22a ... First liquid fuel nozzle part 22b ... Second liquid fuel nozzle part 23 ... Gas fuel supply Pipe 24 ... Air register 25 ... First air flow path 25A ... Rectifying plate 26 ... Second air flow path 28 ... First baffle plate 33 ... Second baffle plate 34 ... Secondary air ejection portions 34a to 34h ... First secondary Air ejection part to eighth secondary air ejection part 38 ... secondary air nozzles 38a to 38f ... first secondary air nozzle to eighth secondary air nozzle 40a to 40h ... first cylinder constituting wall to eighth cylinder constituting wall 46 ... Guide 46a-46h ... First guide-Eighth guide 47 ... Diffusion part 47a-47h ... First diffusion part-Eighth diffusion part 50 ... Wind box 52 ... Flame detector 55, 56, 57 ... Flame detection hole

Claims (4)

In a boiler comprising a can body in which a combustion chamber is formed using a plurality of water pipes, and a burner disposed at an upper portion of the can body, and a gas discharge port of the combustion chamber is provided on a side surface of the combustion chamber,
The burner is a burner that switches between liquid fuel and gaseous fuel, and has a substantially annular cross-sectional flow passage disposed around the liquid fuel nozzle portion, and gas outlets on the inner and outer peripheral surfaces. The formed gas fuel supply pipe, a cylindrical air register arranged coaxially with the gas fuel supply pipe, and the liquid fuel nozzle part and the gas fuel supply pipe are formed at the tip. A first air flow path provided with a first baffle plate, and a second air flow path formed between the gaseous fuel supply pipe and the air register and provided with a second baffle plate at the tip,
Wherein the second baffle plate to form the secondary air injection unit, Bei give a flow control means for controlling the direction away a flow of gas injected from the gas outlet,
The boiler according to claim 1, wherein the flame detector of the burner is disposed above a secondary air ejection portion located on the gas discharge port side . 2. The boiler according to claim 1, wherein the flow control means is a secondary air nozzle formed in a rectangular tube shape including a plate-like member that guides the jet gas in a direction away from the gas discharge port. The exhaust gas discharged from the can body is provided with an external exhaust gas recirculation means capable of selecting supply and stop of supply to the burner, and exhaust gas is supplied to the burner during combustion of the gaseous fuel. The boiler according to claim 1 or claim 2. The flow control means is formed in a cylindrical shape, and includes a pilot burner for ignition at the time of gaseous fuel combustion inside the gaseous fuel supply pipe,
The flame detector is configured to detect the flame of the pilot burner through a flame detection hole formed in the rectifying plate on the inlet side of the first air flow path and a flame detection hole formed in the first baffle plate. The boiler according to claim 1 or 2 , characterized by the above.