JP2015148393A - Burner device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burner device capable of effectively cooling a throat surface even if a burner combustion amount is throttled and capable of restricting occurrence of red heat.SOLUTION: A midway part of a surrounding air supply duct 12 for supplying surrounding atmosphere acting as combustion air to a burner device 1 is arranged circumferentially along an outer periphery of a throat 14 at the extremity end of the burner so as to pre-heat the surrounding atmosphere acting as combustion air while cooing the surface of the throat 14 by the surrounding atmosphere sucked from the surrounding air supply duct 12. Then, when the burner device 1 is ignited, the throat 14 exposed to high temperature flame can be effectively cooled with the surrounding atmosphere to enable disadvantages such as red heat or thermal deformation to be restricted to occur and at the same time upon pre-heating the surrounding atmosphere acting as combustion air, it can be supplied to the burner device 1 and an effect of energy saving can also be expected.

Description

  The present invention relates to, for example, a burner device for generating hot air disposed in a dryer or the like that heats and drys aggregates that are materials of asphalt mixtures.

  Conventionally, for example, as a burner device for generating hot air disposed in a dryer or the like for heating and drying a new aggregate or waste material which is a material of an asphalt mixture, there is one having a throat for forming a flame at the tip of the burner. . In the throat, the fuel oil injected from the fuel injection nozzle and the combustion air (outside air) supplied via the combustion air supply fan are combusted while being efficiently mixed to form a stable flame. . At this time, the inner surface of the throat is exposed to a high-temperature flame, but is appropriately cooled and protected by the outside air sucked into the throat as combustion air.

  By the way, when manufacturing asphalt mixture, from the viewpoint of effective use of resources, it is manufactured by mixing asphalt pavement waste material (hereinafter referred to as “waste material”) generated by road construction etc. in a new aggregate with a predetermined ratio. In many cases, the mixing ratio is recently as high as about 70 to 80%. In this way, when the mixing ratio of waste materials is high, it is necessary to relatively reduce the amount of heat treatment of the new aggregate, and accordingly, the amount of combustion of the burner device for the new aggregate heat treatment is greatly reduced from the normal time. Since it is necessary, the burner device has a large turndown ratio (ratio of the minimum combustion amount to the maximum combustion amount) as disclosed in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2009-41816). Is often adopted.

  However, if the combustion amount is reduced to near the minimum combustion amount with such a high turn-down ratio burner device, the amount of combustion air (outside air amount) sucked into the throat becomes extremely small, so the throat is sufficiently removed from the flame. In some cases, the surface of the throat is heated to a high temperature so as to be reddish, and thermal deformation such as distortion or cracking may occur. In the burner device described in Patent Document 1, a heat shield is attached to the inner surface of the throat, and a passage through which cooling air (outside air) flows is formed on the inner and outer surfaces of the throat, and cooling is performed in the passage. The throat is cooled by flowing air (outside air) to prevent the generation of red heat.

JP 2009-41816 A

  As described above, in order to prevent the red heat of the throat that may be generated by reducing the amount of combustion air when the amount of combustion is reduced in a burner device for generating hot air, particularly a burner device having a high turn-down ratio, Although a means such as an example may be adopted, the present inventors have examined whether there is another effective means that can effectively cool the throat surface and suppress defects such as red heat.

  This invention makes it a subject to provide the burner apparatus which can cool the throat surface effectively and can suppress generation | occurrence | production of red heat even when the burner combustion amount is reduced in view of the above points.

  In order to solve the above problems, the burner device according to claim 1 according to the present invention includes an outside air supply duct for supplying outside air as combustion air to a combustion air supply fan of a burner for generating hot air, Circulating the outside air supply duct along the outer periphery of the throat at the tip of the burner, while cooling the throat surface by exchanging heat between the outside air sucked from the outside air supply duct and the throat surface of the burner Further, the present invention is characterized in that the outside air that is the combustion air is preheated.

  Further, in the burner device according to claim 2, a plurality of projecting pieces project from the outer periphery of the throat, and turbulent flow is generated by the projecting pieces in the outside air flowing along the outer periphery of the throat, thereby improving heat exchange efficiency. It is characterized by being configured as described above.

  According to the burner device of the first aspect of the present invention, the outside air supply duct for supplying outside air as combustion air to the burner is provided so as to extend along the throat outer periphery of the burner tip, and the outside air supply duct. The throat surface is cooled by the outside air that is sucked in more and the outside air that is the combustion air is preheated, so the throat can be cooled effectively even when the burner combustion amount is reduced, and red heat, thermal deformation, etc. The occurrence of defects can be suppressed. Moreover, after preheating the outside air as combustion air, it can be supplied to the burner, and an energy saving effect can be expected.

  In addition, according to the burner device of the second aspect, a plurality of protruding pieces project from the outer periphery of the throat, and turbulent flow is generated by the protruding pieces in the outside air flowing along the outer periphery of the throat, thereby improving the efficiency of heat exchange. Since it comprised so that it might raise, the throat surface can be cooled more effectively and the suppression effect of red heat can be improved. In addition, the preheating efficiency of the outside air can be increased, and the energy saving effect can be expected.

It is a schematic explanatory drawing of the dryer which heat-drys the aggregate which employ | adopted the burner apparatus which concerns on this invention. FIG. 3 is a partially omitted cross-sectional view of an outside air supply duct provided around the throat outer periphery of the burner device. It is the perspective view which partly cut off the external air supply duct provided in the throat outer periphery of the burner device.

  The burner device according to the present invention includes an outside air supply duct that supplies outside air as combustion air to the combustion air supply fan of the burner, and the outside air supply duct is arranged along the outer periphery of the throat at the tip of the burner. The outside air sucked from the outside air supply duct circulates along the outer periphery of the throat, and heat is exchanged with the hot throat surface during that time, while cooling the throat surface, The outside air, which is air, is preheated to some extent and then supplied to the burner. In addition, a plurality of projecting pieces are provided on the outer peripheral surface of the throat whose outer periphery is surrounded by the outside air supply duct to generate a turbulent flow that prevents the circulating ambient air from flowing around. It is intended to increase the efficiency of heat exchange with the throat surface by generating turbulence and stirring appropriately.

  When the burner device having the above-described configuration is burned, the inner surface of the throat is exposed to the flame. However, the throat surface is effectively cooled by the outside air supplied as combustion air, for example, a burner having a high turndown ratio. Even when the amount of combustion is reduced to the vicinity of the minimum combustion amount in the apparatus, it is possible to suppress the occurrence of problems such as throat red heat and thermal deformation, and it is possible to preheat the outside air as the combustion air, and an energy saving effect can be expected. Moreover, since the outer peripheral part of the throat which can become so high that red heat is generated is covered with the outside air supply duct, it is preferable in terms of work safety.

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

  Reference numeral 1 in the figure denotes a burner device according to the present invention, which is disposed at one end of a dryer 2 for heating and drying a new aggregate, which is a material of an asphalt mixture, so that the amount of combustion can be greatly reduced. The turndown ratio is used. The dryer 2 rotatably supports a cylindrical drum 3 having a large number of scraping blades (not shown) on the inner periphery thereof on a machine base (not shown) to drive a motor (see FIG. The hot air is supplied into the drum 3 from the burner device 1 disposed in the hot hopper 4 on one end side of the drum 3, while the cold hopper on the other end side of the drum 3 is rotated at a predetermined speed. A high-temperature gas flow passing through the drum 3 is maintained by suction with an exhaust fan 7 interposed downstream of an exhaust duct 6 connected to 5.

  An aggregate hopper (not shown) for storing new aggregates of various particle sizes is installed in the vicinity of the dryer 2, and aggregates discharged from the aggregate hopper are placed in the drum 3 via the belt conveyor 8. While the aggregate is rolling down in the drum 3, the aggregate is brought into contact with the high-temperature gas flow and heated to a desired temperature, and is sequentially discharged from the discharge port below the hot hopper 4. Further, a dust collector 9 such as a bag filter for collecting dust in the exhaust gas is provided downstream of the exhaust duct 6, and the downstream end thereof is connected to the chimney 11 via the air volume adjusting damper 10 and the exhaust fan 7. The exhaust gas purified by the dust collector 9 is discharged from the chimney 11 to the atmosphere.

  Reference numeral 12 in the figure denotes an outside air supply duct for supplying outside air, which is combustion air, to the combustion air supply fan 13 of the burner device 1, and the outside air supply duct 12 is disposed in the middle of the throat 14 at the tip of the burner device 1. Around the outer periphery, it is formed in a substantially annular shape, and a part of the flow path is blocked by the partition plate 15, and as indicated by the alternate long and short dash line in FIGS. 2 and 3, the outside air introduction port The outside air A sucked from 16 is circulated along the outer periphery of the throat 14 and then supplied to the downstream burner device 1. At this time, heat exchange is performed while the sucked outside air A is in contact with the surface of the hot throat 14 for a certain period of time, and the surface of the throat 14 is cooled, while the outside air that is combustion air is preheated.

  Reference numeral 17 in FIG. 3 denotes a turbulent flow generation piece, which is approximately when the outside air A sucked from the outside air introduction port 16 circulates and passes through the annular outside air supply duct 12 formed on the outer periphery of the throat 14. A plurality of projecting pieces 17 arranged in a staggered manner disturb the flow to generate turbulent flow, so that heat exchange between the outside air A and the surface of the hot throat 14 can be performed more efficiently. ing. It should be noted that the shape, size, number of installations, and arrangement of the protruding pieces 17 are not limited to those shown in the figure, and may be appropriately selected and adjusted according to the actual heat exchange efficiency and the like. . Moreover, you may make it project toward the throat 14 side not on the outer peripheral surface of the throat 14, but on the annular outer air supply duct 12 inner peripheral surface. Further, the outside air supply duct 12 may be provided in a substantially spiral shape so as to circulate a plurality of times along the outer peripheral surface of the throat 14, and in that case, the contact time between the outside air A and the surface of the throat 14 is extended to perform heat exchange. It is possible to further increase the efficiency of.

  When the burner device 1 configured as described above is burned and supplied with hot air into the downstream drum 3 to heat-dry the new aggregate that is the material of the asphalt mixture, the new aggregate supplied into the drum 3 is used. The burner combustion amount is adjusted in accordance with the supply amount and the property thereof, and outside air as combustion air is supplied from the outside air supply duct 12 to the burner device 1 based on the combustion amount. And the external air supplied to the burner apparatus 1 is sent out to the throat 14, and it burns, mixing with fuel oil, and forms a flame.

  At this time, the inner surface of the throat 14 is exposed to the flame, but the surface of the throat 14 is effectively cooled by the outside air that is combustion air that passes through the outer air supply duct 12 provided around the outer periphery of the throat 14. In the burner apparatus 1 with a high turndown ratio as employed in the present embodiment, even when the combustion amount is reduced to near the minimum combustion amount in accordance with the processing amount of the new aggregate, the red heat and heat of the throat 14 Occurrence of defects such as deformation can be suppressed. Moreover, the external air supplied to the burner apparatus 1 as combustion air can be preheated, the combustion efficiency can be increased, and an energy saving effect can be expected.

  According to the test data conducted by the present inventors, the surface temperature of the throat 14, which becomes so high as to generate red heat (approximately 500 ° C.) depending on the burner combustion amount, is the outside air A passing through the outside air supply duct 12. Can be reduced by about 100 ° C. by heat exchange with the throat 14, and can be further reduced by about 50 ° C. as the heat exchange efficiency is improved by the addition of the projecting piece 17, thereby preventing the occurrence of red heat and the throat 14. The effect of reducing the heat load on was confirmed.

DESCRIPTION OF SYMBOLS 1 ... Burner apparatus 2 ... Dryer 3 ... Drum 12 ... Outside air supply duct 13 ... Combustion air supply fan (burner) 14 ... Throat (burner)
17 ... Projection piece

Claims (2)

  An external air supply duct that supplies external air as combustion air to the combustion air supply fan of the burner for generating hot air is provided, and a part of the external air supply duct is provided so as to be along the outer periphery of the throat at the end of the burner. The burner apparatus is characterized in that heat is exchanged between the outside air sucked from the outside air supply duct and the throat surface of the burner to cool the throat surface while preheating the outside air as combustion air.   A plurality of projecting pieces projecting from the outer periphery of the throat, and turbulent flow is generated by the projecting pieces in the outside air flowing along the outer periphery of the throat so as to increase the efficiency of heat exchange. The burner device according to 1.

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