JP2019211095A - Oil-fired burners and multitube once-through boiler - Google Patents

Abstract

To provide a an oil-fired burner which can provide a high turndown ratio.SOLUTION: An oil-fired burner 100 comprises: a plurality of spray nozzles 14 for injecting fuel, each of which includes two low combustion nozzles 14a, a medium combustion nozzle 14b, and a high combustion nozzle 14c; a combustion cylinder 12 which houses the plurality of spray nozzles and allows combustion air to flow therein; a flame holding plate 16 provided inside the combustion cylinder and having a central opening 16a and a plurality of slits 16b provided outside the central opening; and a plurality of swirling blades 17 provided at front side of the spray nozzles 14 with an interval in the circumferential direction and configured to swirl the combustion air transmitted toward the flame holding plate 16. The low combustion nozzles 14a are opposed to one another with a burner central axis 10x interposed between them. The medium combustion nozzle 14b, and a high combustion nozzle 14c are opposed to each other with the burner central axis 10x interposed between them.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an oil-fired burner and a multi-tube once-through boiler provided with the same, and more particularly to an oil-fired burner capable of improving the turndown ratio and a multi-tube once-through boiler provided with the same.

  Conventionally, an oil-burning burner is known as a combustion device used for a hot water machine or a steam boiler. Some oil burning burners are provided with a plurality of fuel spray nozzles including a high combustion nozzle and a low combustion nozzle. In such an oil burning burner, multistage combustion can be performed by appropriately selecting a nozzle for spraying fuel and adjusting the spray amount (for example, Patent Document 1).

  There is also known a multi-tube type once-through boiler in which a combustion chamber surrounded by a plurality of water tubes is provided in front of the combustion device so that a fluid flowing in the water tube can be heated by the combustion device (for example, Patent Documents). 2). The oil-fired burner can be used as a combustion device for a multi-tube once-through boiler.

JP 2013-167366 A Japanese Patent Laying-Open No. 2015-135218 JP 2009-41816 A

  In an oil-burning burner, it is required to stabilize combustion and improve the turndown ratio while reducing the amount of fuel sprayed at the time of low combustion. Here, the turndown ratio is the ratio of the rated fuel flow rate or rated combustion amount of the combustion device to the controllable minimum fuel flow rate or minimum combustion amount. For example, at a turndown ratio of 1: 3, 1 is the rated combustion amount. / 3 is the minimum combustion amount.

  In water heaters and steam boilers, the burner may repeatedly stop and burn in a low load range below the minimum combustion amount. Before the burner stops and starts the ignition operation again, a scavenging operation is required, and the operation efficiency decreases as the frequency of starting and stopping increases. On the other hand, when the turndown ratio is large and the minimum combustion amount is low, the burner can be continuously operated without stopping. Further, since the load range is widened, the burner is prevented from stopping. For this reason, the scavenging operation required at the time of re-ignition of the burner becomes unnecessary and the operation efficiency is improved, so that the running cost can be reduced.

  However, in the configuration of the conventional oil-burning burner, it is difficult to ensure the stability of combustion at the time of low combustion due to the spray position of the low combustion nozzle and the turndown ratio may not be increased. Further, particularly at the time of low combustion, if mixing of the sprayed fuel and the combustion air is not sufficient, there may be a problem in ignition or the combustion stability may be lowered. Furthermore, when using the above oil-burning burner as a combustion device of a multi-tube once-through boiler, the present inventor has found that the combustion performance may be lowered due to the arrangement relationship between the spray nozzle and the water pipe.

  The present invention has been made to solve the above problems, and provides an oil-fired burner that has a plurality of spray nozzles and can realize a high turndown ratio, and a multi-tube once-through boiler using the same. That is the purpose.

  An oil-burning burner according to an embodiment of the present invention is a plurality of spray nozzles for injecting fuel, and includes a plurality of spray nozzles including two low combustion nozzles, a medium combustion nozzle, and a high combustion nozzle. A combustion cylinder configured to contain the plurality of spray nozzles and flow combustion air, and a flame holding plate provided inside the combustion cylinder, and does not cover the spray ports of the plurality of spray nozzles A flame opening plate having a central opening provided in this manner and a plurality of slits provided outside the central opening, and a gap in the circumferential direction on the front side of the spray nozzles inside the combustion cylinder A plurality of swirl vanes arranged to swirl the combustion air toward the flame holding plate, the two low combustion nozzles sandwiching the burner central axis Facing and said A combustion nozzle and the nozzle for high combustion are provided so as to face each other across the central axis of the burner.

  In one embodiment, the oil-burning burner further includes a current plate provided between the plurality of swirl blades and the flame holding plate inside the combustion cylinder.

  In a certain embodiment, the diameter of the said baffle plate is set to 1.4 to 1.6 times the diameter of the said center opening part provided in the said flame-holding board.

  In one embodiment, a diameter of a tip circle of the plurality of swirling blades when viewed from the burner central axis direction and a diameter of a circle in which tips of the plurality of slits provided in the flame holding plate are located are substantially equal. Are the same.

  In one embodiment, a distance in the burner central axis direction between the flame holding plate and the plurality of swirling blades is set to 0.8 to 0.9 times a diameter of a tip circle of the plurality of swirling blades. Yes.

  In one embodiment, the two low combustion nozzles, the middle combustion nozzle, and the high combustion nozzle are disposed at equidistant and point symmetrical positions with respect to the burner central axis, and the burner center It is provided at equal intervals in the circumferential direction around the shaft.

  In one embodiment, low combustion is performed by spraying fuel simultaneously from the two low combustion nozzles, and medium combustion is spraying fuel simultaneously from the two low combustion nozzles and the medium combustion nozzle. The high combustion is performed by simultaneously spraying fuel from the two low combustion nozzles, the medium combustion nozzle and the high combustion nozzle, and spraying each of the two low combustion nozzles. The amount is 10% of the rating, the spray amount of the middle combustion nozzle is 30% of the rating, the spray amount of the high combustion nozzle is 50% of the rating, and the turndown ratio is 1: 5. .

  A multitubular once-through boiler according to an embodiment of the present invention is any one of the above oil-burning burners and an inner water tube row arranged so as to surround a combustion chamber of the oil-burning burner, and a large number of water tubes are annularly formed. An inner water tube row that is arranged and connects adjacent water tubes to form the circular combustion chamber inward, and is disposed outside the inner water tube row, and connects the adjacent water tubes to each other with the inner water tube row. An outer water pipe row that forms an annular exhaust gas passage therebetween, the inner water pipe row has an exhaust gas combustion chamber outlet that communicates the combustion chamber and the exhaust gas passage, and the outer water pipe row When viewed from the burner central axis direction, an exhaust gas main body outlet is formed at the position opposite to the exhaust gas combustion chamber outlet at a position 180 ° opposite to the exhaust gas combustion chamber outlet, and when viewed from the burner central axis direction. The exhaust gas combustion chamber An exhaust gas outlet direction defined by a straight line connecting the mouth and the flue gas main outlet, placed opposite direction of the two low combustion nozzle of the oil-fired burner intersect at an angle of 40 to 50 °.

  In one embodiment, when viewed from the burner central axis direction, an angle of 40 to 50 degrees between the facing arrangement direction of the middle combustion nozzle and the high combustion nozzle of the oil burning burner and the exhaust gas outlet direction Intersect.

  In an embodiment, the exhaust gas outlet direction and the opposing arrangement direction of the two low combustion nozzles of the oil burning burner intersect at an angle of approximately 45 °.

  According to the oil-burning burner according to the embodiment of the present invention, the turndown ratio can be improved by improving the stability particularly in the low combustion, and the multi-tube once-through boiler according to the embodiment of the present invention has a combustion performance. Can be improved.

It is a figure which shows the whole structure of the oil burning burner by embodiment of this invention. It is typical sectional drawing which shows the combustion part of the oil burning burner by embodiment of this invention. It is a figure which expands and shows the structure of the combustion part of the oil burning burner by embodiment of this invention, (a) is a top view when it sees from a burner central-axis direction, (b) is AA of (a). It is sectional drawing along a line. It is a schematic diagram which shows the vicinity of the combustion part of the oil burning burner by embodiment of this invention, (a) is a side view inside a burner, (b) is a top view. 1 is a schematic view showing a multitubular once-through boiler provided with an oil burning burner according to an embodiment of the present invention. It is a top view which shows arrangement | positioning of the inner side water pipe row | line | column and outer side water pipe row | line | column, and the arrangement | positioning of the spray nozzle of an oil burning burner in the multi-tube type once-through boiler shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

  FIG. 1 is a schematic diagram showing an oil burning burner 100 according to an embodiment of the present invention. The oil-burning burner 100 of the present embodiment sprays atomized fuel oil without using an atomizing medium such as air or steam by injecting high-pressure fuel oil from a nozzle, and is a pressure spray type oil-burning burner. (Hydraulic spray combustion apparatus) 100.

  As shown in FIG. 1, the oil burning burner 100 supplies a combustion unit 10 including a plurality of fuel spray nozzles 14, a fuel supply line 20 for supplying fuel to the combustion unit 10, and combustion air to the combustion unit 10. And a combustion air supply line 30.

  The fuel supply line 20 includes a strainer 22 that communicates with the fuel oil storage unit 21, a fuel injection pump 24 that pressurizes the fuel oil cleaned by the strainer 22, and an original shut-off connected to the downstream side of the fuel injection pump 24. And an electromagnetic valve 26 for operation. Further, three branched sub supply lines 28a, 28b, and 28c for low combustion, medium combustion, and high combustion are connected to the downstream side of the original shutoff solenoid valve 26, and each sub supply line is connected to each sub supply line. Solenoid valves 29a, 29b, and 29c are provided, respectively.

  The combustion air supply line 30 is provided with a blower 31, an air pipe connected to the blower 31, and an air damper 39 for adjusting the air volume of the combustion air.

  The combustion section 10 has a configuration in which two low combustion nozzles 14a, one medium combustion nozzle 14b, and one high combustion nozzle 14c are arranged inside the combustion cylinder 12. These spray nozzles 14 are not return flow type nozzles but are on / off control nozzles (full-quantity type nozzles or non-return type nozzles) that do not include a flow rate adjusting mechanism. The spray nozzle 14 can spray the fuel in a conical shape, and the spray angle is set to, for example, 30 ° to 60 ° (45 ° in the present embodiment).

  Fuel oil is supplied to the two low combustion nozzles 14a through a supply line branched from the low combustion sub supply line 28a. Further, the fuel oil is supplied to the middle combustion nozzle 14b by the middle combustion sub supply line 28b, and the high combustion nozzle 14c is supplied by the high combustion sub supply line 28c. Further, the combustion air whose air volume is adjusted in the combustion air supply line 30 is supplied to the inside of the combustion cylinder 12.

  In the combustion unit 10, the pressurized fuel oil is sprayed from the spray nozzle 14, mixed with the combustion air supplied from the combustion air supply line 30, and combusted by igniting the mixed gas. The fuel spray amount is adjusted by controlling the opening and closing of the electromagnetic valves 29a, 29b, and 29c by a control device (not shown), and the supply amount of the combustion air is controlled by controlling the opening degree of the air damper 39 by the control device. Adjusted to fit. In the oil spray burner 100 configured as described above, the fuel oil supply pressure is maintained at a substantially constant pressure regardless of the amount of spray, and the pressure is, for example, 0.5 to 2.0 MPa. It is.

  The oil-burning burner 100 of this embodiment can perform combustion in four stages (four positions): combustion stop, low combustion, medium combustion, and high combustion. In the low combustion, the fuel is sprayed simultaneously from the two low combustion nozzles 14a, and the fuel is not sprayed from the middle combustion nozzle 14b and the high combustion nozzle 14c (that is, only the original shut-off solenoid valve 26 and the solenoid valve 29a). Can be executed. In the middle combustion, the fuel is sprayed simultaneously from the two low combustion nozzles 14a and the middle combustion nozzle 14b, and the fuel is not sprayed from the high combustion nozzle 14c (that is, the original shutoff solenoid valve 26, the solenoid valve 29a and the solenoid valve 29a). It can be executed by opening the solenoid valve 29. In the high combustion, fuel is sprayed simultaneously from all four spray nozzles 14 (two low combustion nozzles 14a, medium combustion nozzles 14b, and high combustion nozzles 14c) (ie, the original shut-off solenoid valve 26 and all This can be done by opening the solenoid valves 29a, 29b, 29c).

  2, 3 (a), and 3 (b) are diagrams showing a specific configuration of the combustion unit 10 of the oil-burning burner 100. 2 is a schematic cross-sectional view illustrating an exemplary configuration of the combustion unit 10, FIG. 3A is a plan view illustrating the arrangement of four spray nozzles 14, and FIG. It is sectional drawing along the AA of (a).

  As shown in FIG. 2, the combustion unit 10 is provided with a window box 32 communicating with the combustion air supply line 30, a viewing window 33 provided in the window box 32, a flame monitor 34, and the like. A rectifying pipe 35 is provided inside the wind box 32, and a blast pipe (also called a draft tube) 36 is provided inside the rectifying pipe 35.

  In the present embodiment, a frame funnel 37 is connected to the tip of the blast pipe 36. In the present specification, the blast pipe 36 and the frame funnel 37 are sometimes referred to as the combustion cylinder 12 (FIG. 1 and the like), and the cylinder arranged so as to surround the outside of the spray nozzle 14 is widely referred to as the combustion cylinder 12. I will do it.

  The combustion air supplied to the wind box 32 passes through the rectifying pipe 35 and the blast pipe 36 and is rectified and supplied toward the frame funnel 37 as indicated by white arrows in the figure. The frame funnel 37 may have a shape whose inner diameter increases toward the distal direction. Further, a ring-shaped throttle member 37A (see FIG. 4A) may be provided at the outlet of the frame funnel 37.

  Four spray nozzles 14 are accommodated inside the combustion cylinder 12 constituted by the blast pipe 36 and the frame funnel 37. In FIG. 2, only one spray nozzle 14 is shown for the sake of simplicity, but actually four spray nozzles 14 are provided as shown in FIGS. 1 and 3A. The fuel supply pipe 15 connected to the spray nozzle 14 is provided so as to extend in parallel with the burner central axis 10x, and is supported by a centering rod 15a. The fuel supply pipe 15 is connected to a fuel supply line 20 (see FIG. 1), and is configured such that high-pressure fuel oil flows through the inside thereof as indicated by a black arrow.

  As shown in FIG. 3A, the oil-burning burner 100 of the present embodiment includes two low combustion nozzles 14a, a middle combustion nozzle 14b, and a high combustion nozzle 14c at the center of the burner. It is provided around the shaft 10x (the central axis of the combustion cylinder 12). In addition, a tip portion of the ignition rod 18 for ignition is located in the vicinity of one of the low combustion nozzles 14a.

  These four spray nozzles 14 are surrounded by the combustion cylinder 12. Further, inside the combustion cylinder 12, a flame holding plate 16 having a central opening 16 a provided at a position corresponding to the spray nozzle 14 is provided in front of the spray nozzle 14. Fuel is sprayed forward through the opening 16a. The central opening 16a typically has a circular planar shape, but is not limited thereto, and may have a polygonal planar shape.

  The flame holding plate 16 is also provided with a plurality of radially provided slits 16b, here, eight slits 16b and a slit cover 16c. The plurality of slits 16b are provided so as to extend outward from the central opening 16a, and the slit cover 16c is provided so as to open one edge of each slit 16b. In this configuration, the combustion air (primary air) can be supplied so as to make a swirl flow in front of the flame holding plate 16 through the central opening 16a and each slit 16b. Thereby, the fuel sprayed from the spray nozzle 14 is agitated by the combustion air, and the sprayed fuel and the combustion air are easily mixed uniformly.

  The number of slits 16b provided for swirling the combustion air may be, for example, 4 to 12. In addition, the slit 16b is typically formed in a form connected to the central opening 16a so as to extend outward from the central opening 16a, but may be provided separately from the central opening 16a. .

  In addition, secondary air is supplied from the gap between the combustion cylinder 12 and the flame holding plate 16, and the oil-burning burner 100 swirls the primary air more effectively as shown in FIG. A plurality of swirl vanes 17 are provided on the back side of the flame holding plate 16. Details of the swirl vane 17 will be described later.

  The configuration of the spray nozzle 14 will be described with reference to FIGS. 3 (a) and 3 (b) again. In the present embodiment, the two low combustion nozzles 14a are provided to face each other with the burner central axis 10x interposed therebetween. Similarly, the middle combustion nozzle 14b and the high combustion nozzle 14c are provided to face each other with the burner central axis 10x interposed therebetween. More specifically, the four spray nozzles 14 are arranged at positions that are equidistant and point-symmetric with respect to the burner central axis 10x, and are equally spaced in the circumferential direction around the burner central axis 10x (that is, , At a position rotated by 90 °).

  In this embodiment, the spray amount (nozzle diameter etc.) of the two low combustion nozzles 14a is designed to be equal. On the other hand, the spray amount of the middle combustion nozzle 14b is designed to be larger than the spray amount of the low combustion nozzle 14a. Similarly, the spray amount of the high combustion nozzle 14c is also designed to be larger than the spray amount of the low combustion nozzle 14a. The spray amount of the high combustion nozzle 14c may be set larger than the spray amount of the medium combustion nozzle 14b.

  As a more specific example, the spray amount of each of the two low combustion nozzles 14a is set to, for example, about 10.0% of the rating, and the spray amount of the medium combustion nozzle 14b is, for example, about 30.0 of the rating. %, And the spray amount of the high combustion nozzle 14c is set to about 50.0% of the rating, for example. In this example, the minimum combustion amount is 20% of the rated combustion amount, and the turndown ratio is 1: 5 (the following Example No. 1).

  Table 1 below shows various Example Nos. 1-No. 6 shows the spray amounts of the two low combustion nozzles 14a, the middle combustion nozzle 14b, and the high combustion nozzle 14c, and the realized turndown ratio. In Table 1, the spray amount is shown as a ratio (%) to the maximum (rated) spray amount, and when the fuel is sprayed from all the nozzles 14a, 14b, 14c, the maximum spray amount is 100%.

As shown in Table 1, the spray amount of the two low combustion nozzles 14a is set to, for example, 10% to 15%, and the spray amount of the medium combustion nozzle 14b is set to, for example, 20% to 40%. The spray amount of the nozzle 14c is set to 40% to 50%, for example. However, the spray amount of each nozzle is not limited to these.

  As described above, in the oil-burning burner 100 of the present embodiment, the two low combustion nozzles 14a are disposed opposite to the burner central axis 10x so that fuel is sprayed simultaneously from the two nozzles. Combustion stability can be ensured even when the fuel spray amount is low as compared with the case of using one nozzle. Further, even in low combustion, high-pressure fuel oil can be sprayed from the two low combustion nozzles 14a, and fuel can be atomized appropriately, so that combustion can be performed stably. Therefore, a high turndown ratio as described above can be realized. According to the oil burning burner of this embodiment, it is possible to realize a turndown ratio of 1: 5 or more (the minimum combustion amount is 1/5 or less of the rated combustion amount).

  As shown in FIG. 4A, the combustion unit 10 of the oil-burning burner 100 according to the present embodiment includes a plurality of swirl blades 17 for swirling combustion air inside the combustion cylinder 12. Patent Document 3 (Japanese Patent Laid-Open No. 2009-41816) discloses a pressure spray burner having swirl vanes.

  In the oil-burning burner 100 of the present embodiment, the swirl vane 17 surrounds the fuel supply pipe 15 so as to surround the fuel supply pipe 15 in front of the four spray nozzles 14, more specifically, near the roots of the four spray nozzles 14. It is provided on the back side (upstream side) of the plate 16. In the illustrated embodiment, the six swirl vanes 17 are arranged at intervals of 60 ° with a gap in the circumferential direction. However, the number of swirl vanes 17 is, for example, 4 to 12 sheets. Good. Moreover, the angle of the blade surface of each swirl blade 17 may be provided so as to be inclined, for example, 30 to 60 ° (preferably 40 ° to 50 °) with respect to the burner central axis direction. Each swirl blade 17 may have an arbitrary shape as long as the swirl of air can be appropriately performed.

  Here, as can be seen from FIGS. 4A and 4B, the diameter Ds of the tip circles of the plurality of swirling blades 17 when viewed from the burner central axis direction, and a plurality of provided on the flame holding plate 16. The diameter Db of the circle C1 where the tip of the slit 16b is located is set to be substantially the same (within 10% error). Thus, the combustion air that passes through the swirl vane 17 and further passes through the slit 16b of the flame holding plate 16 and flows in front of the spray nozzle 14 can be swirled effectively.

  On the other hand, the combustion air (secondary air) flowing through the inside of the combustion cylinder 12 through the outside of the swirl vane 17 and the flame holding plate 16 is not easily affected by the swirl by the swirl vane 17. For this reason, unlike the primary air, the secondary air is smoothly supplied along the wall surface of the combustion cylinder 12 to the combustion chamber in front of the nozzle.

  As described above, in this embodiment, the primary air is swirled in front of the flame holding plate 16 in advance by the swirl vanes 17 so that the fuel sprayed from the spray nozzle 14 can be more uniformly mixed. At the same time, secondary air can be smoothly supplied in a direct current manner. For this reason, it is possible to perform stable combustion with good ignition stability and flame holding properties. Moreover, since uniform mixing of fuel and primary air is promoted, smoke generation during ignition can be suppressed, and incomplete combustion can be suppressed to reduce NOx generation amount and CO generation amount.

  As shown in FIG. 4A, the combustion unit 10 of the oil-burning burner 100 according to the present embodiment includes a rectifying plate 19 disposed around the burner central axis inside the combustion cylinder 12. The current plate 19 is located between the swirl vane 17 and the flame holding plate 16. The rectifying plate 19 may be, for example, a plate member provided with a large number of holes, or a rectifying plate having a lattice shape or a honeycomb structure. The rectifying plate 19 may have an arbitrary shape as long as it can rectify the combustion air passing therethrough. If such a rectifying plate 19 is used, the turbulence of the swirling flow formed by the swirling blades 17 is suppressed, and in particular, the combustion air passing through the central opening 16a of the flame holding plate 16 can be rectified. The sprayed fuel and primary air can be mixed more uniformly in front of the flame plate 16.

  Moreover, in this embodiment, as shown to Fig.4 (a) and (b), the diameter Dh of the baffle plate 19 is 1.4-1 of the diameter Da of the center opening part 16a provided in the flame holding plate 16. As shown in FIG. It is set to 6 times. Although the shape of the rectifying plate 19 is circular, by setting the diameter as described above, it is possible to effectively suppress smoke generation and blow-off during ignition and to improve the ignition stability. Furthermore, in this embodiment, the distance Hs between the flame holding plate 16 and the swirl vane 17 in the burner central axis direction is set to 0.8 to 0.9 times the diameter Ds of the tip circles of the swirl vanes 17. ing. As a result, it is possible to further improve the mixing of fuel and air during low combustion.

  As described above, according to the oil-burning burner 100 of the present embodiment, the fuel can be stably sprayed even at low combustion using the two low combustion nozzles arranged opposite to each other, and swirling of the primary air mixed with the sprayed fuel Therefore, stable combustion with improved ignitability and flame holding performance can be performed. Thereby, a high turndown ratio of 1: 5 or more can be realized.

  Hereinafter, the multi-tube once-through boiler 200 according to the present embodiment configured using the oil burning burner 100 including the four spray nozzles 14 will be described.

  FIG. 5 is a diagram showing a configuration of the multi-tube once-through boiler 200. The multi-tube once-through boiler 200 includes an inner water tube row 40 that forms a circular combustion chamber 41 inward so as to surround a combustion space in front of the combustion unit 10 of the oil burning burner 100 shown in FIG. It has an outer water tube row 42 provided concentrically with a gap outside the row 40. An exhaust gas passage 43 for flowing exhaust gas from the combustion chamber 41 is formed between the inner water tube row 40 and the outer water tube row 42.

  As shown in FIG. 6, the inner water tube row 40 is formed by arranging a large number of water tubes 40 a in a ring shape and connecting adjacent water tubes 40 a in a sealed manner by strip plate-like fin members 40 b except for a part. It is configured. The outer water tube row 42 has a large number of water tubes 42a arranged in an annular shape at an outer position of the inner water tube row 40, and with the exception of some of the water tubes 42a, the adjacent water tubes 42a are hermetically sealed by strip plate-like fin members 42b. It is configured by connecting. FIG. 6 also shows the arrangement of two low combustion nozzles 14a, middle combustion nozzles 14b, and high combustion nozzles 14b provided in the central portion of the combustion chamber 41.

  Referring to FIG. 5 again, annular upper header 44 and lower header 45 are connected to the upper end and lower end of each of water tubes 40a, 42a constituting inner water tube row 40 and outer water tube row 42, respectively. The upper header 44 and the lower header 45 are formed in an annular shape having a rectangular cross section, and the upper and lower ends of the water pipes 40a and 42a are connected to both the headers 44 and 45, respectively. ing.

  The water flowing through the upper header 44, the water pipe rows 40 and 42, and the lower header 45 is heated by heat from the combustion chamber 41 and heat from high-temperature exhaust gas exhausted from the combustion chamber 41. In this embodiment, the combustion part 10 is arrange | positioned above the inner side water pipe row | line | column 40 and the outer side water pipe row | line | column 42 which are arrange | positioned so that it may extend in the orthogonal | vertical direction, for example, and burns inside the combustion chamber 41 formed below. It is configured. Although not shown, the upper header 44 may be connected to a steam pipe and a steam separator, and the lower header 45 may be connected to a return pipe, a feed pipe, a feed pump, and the like from the steam separator. May be connected.

  In the multitubular once-through boiler 200 configured in this way, as shown in FIG. 6, the exhaust gas G from the combustion chamber 41 passes through the exhaust gas combustion chamber outlet 47 which is a break of the inner water tube row 40, and the inner water tube row 40. Through the annular exhaust gas passage 43 formed between the outer water pipe row 42 and the outer water pipe row 42, and then flows to the flue 49 through the exhaust gas main body outlet 48 which is a break of the outer water pipe row 42. In the inner water tube row 40, the exhaust gas combustion chamber outlet 47 is formed over substantially the entire length of the water tube 40a, and in the outer water tube row 42, the exhaust gas body outlet 48 is formed over substantially the entire length of the water tube 42a. ing.

  More specifically, the exhaust gas G generated in the combustion chamber 41 by the combustion of the burner combustion unit 10 flows into the annular exhaust gas passage 43 from the exhaust gas combustion chamber outlet 47 formed in the inner water tube row 40, and here, in two directions The exhaust gas passage 43 is divided into approximately half a circumference in the circumferential direction, and the heat retained in the exhaust gas G is heated to the water pipes 40a, 42a of the inner water pipe row 40 and the outer water pipe row 42 by convection heat transfer (contact heat transfer) during that period. The exhaust gas G, which has been separated in two directions, joins at the exhaust gas body outlet 48 and is discharged from here to the flue 49. This type of multi-pipe once-through boiler is sometimes called the ω flow type.

  In the present embodiment, the exhaust gas combustion chamber outlet 47 provided in the inner water tube row 40 and the exhaust gas body outlet 48 provided in the outer water tube row 42 are opposite to each other by 180 ° when viewed from the burner central axis direction. It is provided at the side position. When viewed from the burner central axis direction, the exhaust gas outlet direction D1 defined by a straight line connecting the exhaust gas combustion chamber outlet 47 and the exhaust gas body outlet 48 and the two low combustion nozzles 14a of the oil burning burner 100 are opposed to each other. It arrange | positions so that arrangement | positioning direction D2 may cross | intersect at angle (theta) 1 of 40-50 degrees, more specifically about 45 degrees. Similarly, the exhaust gas outlet direction D1 and the opposed arrangement direction D3 of the middle combustion nozzle 14b and the high combustion nozzle 14c (here, the direction orthogonal to the opposed arrangement direction D2 of the low combustion nozzle 14a) are 40 to 40. They are arranged so as to intersect at an angle θ2 of 50 °, more specifically at approximately 45 °.

  In the above configuration, the distance between the spray nozzle 14 (more specifically, one of the low combustion nozzle 14a and the middle combustion nozzle 14b) and the exhaust gas combustion chamber outlet 47 can be made relatively large to prevent a short path. It was found that good combustion can be performed.

  As shown in FIG. 6, in each of the inner water tube row 40 and the outer water tube row 42, the adjacent water tubes 40 a and 42 a closer to the exhaust gas combustion chamber outlet 47 are connected closer to each other and the exhaust gas body outlet 48 is connected. The adjacent water pipes 40a and 42a on the near side may be connected further apart. Further, the thickness of the fin member 42b near the exhaust gas combustion chamber outlet 47 may be larger than the thickness of the fin member 42b near the exhaust gas body outlet 48. If comprised in this way, since heat can be transmitted to more water in the vicinity of the exhaust gas G which is higher temperature, heat transfer efficiency can be improved and energy utilization efficiency can be improved.

  Although the embodiments of the present invention have been described above, various modifications can be made. For example, although the configuration in which four spray nozzles are provided has been described above, five or more spray nozzles may be provided, and in this case as well, two (or four or more even numbers) low combustion are provided. It is preferable that the nozzles are disposed to face each other with the burner central axis interposed therebetween. Further, as described in Patent Document 2, the inner water tube row 40 and the outer water tube row 42 are provided with water tubes 40a and 42a in a zigzag array along the circumferential direction in at least a part of the exhaust gas. It may be configured to increase the turbulent flow of the exhaust gas G flowing through the passage 43 and increase the heat absorption of the exhaust gas retained heat.

  The oil-burning burner according to the embodiment of the present invention is suitably used as a combustion device used in various steam boilers, hot water heaters, and the like, for example, as a combustion device of a multi-tube once-through boiler.

DESCRIPTION OF SYMBOLS 10 Combustion part 12 Combustion cylinder 14 Spray nozzle 14a Low combustion nozzle 14b Medium combustion nozzle 14c High combustion nozzle 15 Fuel supply pipe 16 Flame holding plate 16a Central opening 16b Slit 17 Swirling blade 18 Ignition rod 19 Rectification plate 20 Fuel supply Line 21 Fuel oil storage unit 22 Strainer 24 Ejection pump 26 Original shutoff solenoid valve 28a, 28b, 28c Sub supply line 29a, 29b, 29c Solenoid valve 30 Combustion air supply line 31 Blower 32 Wind box 35 Rectifier pipe 36 Blast pipe ( Combustion cylinder 12)
37 flame funnel (combustion cylinder 12)
39 Air damper 40 Inner water tube row 41 Combustion chamber 42 Outer water tube row 44 Upper header 45 Lower header 47 Exhaust gas combustion chamber outlet 48 Exhaust gas body outlet 49 Flue 100 Oil fired burner 200 Multi-tube once-through boiler

Claims (10)

A plurality of spray nozzles for injecting fuel, the plurality of spray nozzles including two low combustion nozzles, a medium combustion nozzle, and a high combustion nozzle;
A combustion cylinder configured to contain the plurality of spray nozzles and flow combustion air;
A flame holding plate provided on the inner side of the combustion cylinder, the central opening provided so as not to cover the spray ports of the plurality of spray nozzles, and a plurality of slits provided outside the central opening. A flame holding plate having,
A plurality of swirl blades arranged with gaps in the circumferential direction on the front side of the plurality of spray nozzles inside the combustion cylinder, the plurality of swirl blades configured to swirl the combustion air toward the flame holding plate With swirling vanes and
The two low combustion nozzles face each other across the burner central axis, and the middle combustion nozzle and the high combustion nozzle face each other across the burner central axis Burner.   The oil-burning burner according to claim 1, further comprising a baffle plate provided between the plurality of swirl vanes and the flame holding plate inside the combustion cylinder.   The oil-burning burner according to claim 2, wherein a diameter of the current plate is set to 1.4 to 1.6 times a diameter of the central opening provided in the flame holding plate.   The diameters of the tip circles of the plurality of swirling blades when viewed from the burner central axis direction are substantially the same as the diameters of the circles where the tips of the plurality of slits provided in the flame holding plate are located. The oil-burning burner according to any one of claims 1 to 3.   The distance in the burner center axis direction of the flame-holding plate and the plurality of swirling blades is set to 0.8 to 0.9 times the diameter of the tip circle of the plurality of swirling blades. To 4. The oil-burning burner according to any one of 1 to 4.   The two low combustion nozzles, the middle combustion nozzle, and the high combustion nozzle are disposed at equidistant and point-symmetrical positions with respect to the burner central axis, and around the burner central axis. The oil-burning burner according to any one of claims 1 to 5, which is provided at equal intervals in the direction. Low combustion is performed by spraying fuel simultaneously from the two low combustion nozzles, and medium combustion is performed by spraying fuel simultaneously from the two low combustion nozzles and the middle combustion nozzle, High combustion is performed by spraying fuel simultaneously from the two low combustion nozzles, the middle combustion nozzle and the high combustion nozzle,
The spray amount of each of the two low combustion nozzles is 10% of the rating, the spray amount of the medium combustion nozzle is 30% of the rating, and the spray amount of the high combustion nozzle is 50% of the rating. The oil-burning burner according to any one of claims 1 to 6, wherein the burner has a turndown ratio of 1: 5. An oil-burning burner according to any one of claims 1 to 7,
An inner water tube line arranged so as to surround the combustion chamber of the oil burning burner, wherein a plurality of water tubes are arranged in an annular shape and adjacent water tubes are connected to form an inner circular combustion chamber. Columns,
An outer water pipe row that is disposed outside the inner water pipe row and connects adjacent water pipes to form an annular exhaust gas passage between the inner water pipe row;
With
The inner water tube row is formed with an exhaust gas combustion chamber outlet for communicating the combustion chamber and the exhaust gas passage. An exhaust gas main body outlet for communicating the exhaust gas passage and the flue is formed at the opposite position,
When viewed from the burner central axis direction, the exhaust gas outlet direction defined by a straight line connecting the exhaust gas combustion chamber outlet and the exhaust gas main body outlet, and the opposing arrangement direction of the two low combustion nozzles of the oil burning burner Is a multi-tube once-through boiler that intersects at an angle of 40-50 °.   When viewed from the burner central axis direction, the opposing arrangement direction of the middle combustion nozzle and the high combustion nozzle of the oil burning burner and the exhaust gas outlet direction intersect at an angle of 40 to 50 °. A multi-tube once-through boiler according to claim 8.   The multi-pipe once-through boiler according to claim 8 or 9, wherein the exhaust gas outlet direction and the opposing arrangement direction of the two low combustion nozzles of the oil burning burner intersect at an angle of approximately 45 °.