JP3524682B2 - Pulverized fuel combustion device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulverized fuel combustion apparatus used in boiler furnaces, chemical industrial furnaces, and the like. 2. Description of the Related Art The present applicant has previously proposed a pulverized fuel combustion apparatus which is configured to stably ignite a flame-retardant fuel to improve flammability (Japanese Patent Application Laid-Open No. 7-1995). 19848
No. 6). The pulverized fuel combustion device will be described with reference to FIGS. FIG. 2 is a side view of a boiler according to the embodiment, FIG. 3 is a perspective view showing a configuration of a wind box of the burner in the above embodiment, FIG. 4 is a plan view showing a burner in the embodiment, and FIG. FIG. 6 is a diagram schematically illustrating a combustion state in a furnace in the above embodiment, and FIG. 6 is a longitudinal sectional view showing a structure of a burner in the above embodiment. First, as shown in FIG. 2, a burner nozzle 2 in a pulverized fuel combustion apparatus according to this embodiment is disposed on a furnace wall of a boiler furnace 1 so as to be inclined downward, and the injected air-fuel mixture ignites to generate buoyancy. As a result, a U-shaped flame 3 is formed. Next, as shown in FIG. 3, in the configuration of the wind box in the combustion apparatus of the present embodiment, ports A for combustion auxiliary air and ports FD and FL for jetting fuel alternately overlap in the vertical direction. The ports for ejecting the fuel are each provided with two ports FD of a mixture with a high concentration and ports FL of a mixture with a low concentration in a lateral direction. As shown in FIG. 4, in the combustion apparatus of the present embodiment, high-concentration fine powder is introduced toward the inside of the swirling flame vortex 4, and low-concentration fine powder is introduced toward the outside of the vortex. . Then, as shown in FIG. 5, a stable high-density combustion zone 5 is formed at the center of the furnace. [0007] The structure of the burner in the combustion apparatus of this embodiment is as shown in FIG. 6, and the pulverized fuel conveyed by the primary air is separated into a rich mixture and a light mixture by the cyclone separator 7, and the inside of the furnace It ignites and burns. [0008] As described above, FIG.
6, the cyclone separator 7 is provided between the burner nozzle 2 and the pulverized fuel supply pipe.
To separate the high-concentration fine powder and the low-concentration fine powder, while supplying each fine powder to the burner nozzle 2 and throwing the high-concentration fine powder toward the inside of the vortex; By arranging the burner nozzle 2 so as to be charged toward the fuel, stable ignition is possible even in the case of a flame-retardant fuel, and the combustibility is improved. [0009] Further, in the combustion apparatus, since the vicinity of the furnace side wall is in an oxidizing atmosphere with a sufficient amount of air, reduction corrosion of the furnace wall tube and adhesion and deposition of minerals in fuel on the furnace wall are prevented. . In particular, when burning difficult-to-ignite pulverized fuel, it is important to make the flow velocity as low as possible at the burner nozzle ejection part, but there is a limit from the viewpoint of preventing accumulation and the like. SUMMARY OF THE INVENTION It is an object of the present invention to provide a pulverized fuel combustion apparatus which can further promote ignition of a difficult-to-ignite pulverized fuel and perform more excellent stable combustion. [0011] In order to solve the above-mentioned problems, the present invention provides a plurality of burner nozzles such that a flame swirls in a furnace to form a vortex and has a U-shaped vertical section. Is arranged on the furnace wall, a fine powder fuel supply pipe is connected to the burner nozzle via a cyclone separator, and the fine powder fuel is separated into high-concentration fine powder and low-concentration fine powder by the cyclone separator. And a high-concentration fine powder is supplied toward the inside of the vortex, and the burner nozzle is disposed such that the low-concentration fine powder is supplied toward the outside of the vortex. The configuration is adopted in which the ejection port surface is inclined at an angle with respect to the ejection direction axis so as to be the same plane parallel to the inner surface of the furnace over the entire surface. In the pulverized fuel combustion apparatus according to the present invention, as described above, the pulverized fuel injection port is formed over the entire surface.
As a result, the cross-sectional area of the jetting portion is substantially increased, and the jetting flow velocity is decreased by forming a configuration inclined at an angle to the jetting direction axis so as to be on the same plane parallel to the inner surface of the furnace. Further, the heat receiving surface area of the fuel jet increases, and the temperature of the fuel increases. Therefore, in the pulverized fuel combustion device according to the present invention, ignition of the hardly ignitable pulverized fuel can be promoted and stable combustion can be performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a pulverized fuel combustion device according to the present invention will be specifically described based on one embodiment shown in FIG. FIG. 1 shows a burner structure in a pulverized fuel combustion device according to one embodiment of the present invention, and is a longitudinal sectional view similar to FIG. In the pulverized fuel combustion apparatus shown in FIG.
The tip 2a of the burner nozzle 2 is inclined at an angle with respect to the jet direction axis such that the jet outlet surface is parallel to the boiler furnace inner surface 1a and forms the same surface. In the pulverized fuel combustion apparatus according to the present embodiment, the other structure is the same as that of the pulverized fuel combustion apparatus except that the injection port surface of the tip 2a of the burner 2 is formed so as to be parallel to the furnace inner surface 1a and to form the same surface. The structure is the same as that of the pulverized fuel combustion device shown in FIGS. 2 to 6, and the description thereof will be omitted. In the pulverized fuel combustion device according to the present embodiment, as described above, by making the ejection surface of the burner nozzle 2 parallel to the inner surface of the furnace, the burner nozzle 2 is once ejected downward to form a U-shaped flame. If the gas blows up in the furnace, the substantial ejection speed can be reduced. In this way, it is possible to promote the ignition of the non-ignitable pulverized fuel and perform stable combustion. As described above, in the pulverized fuel combustion apparatus of the present invention, the injection surface of the burner nozzle of the pulverized fuel is made to be the same plane parallel to the inner surface of the furnace over the entire surface. By setting the angle to the axis of the ejection direction, the substantial sectional area of the ejection portion is increased, the ejection velocity is reduced, and the ignition is stabilized. Further, the heat receiving surface area of the fuel jet is increased, and the temperature of the fuel is raised, so that ignition can be promoted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a burner structure in a pulverized fuel combustion device according to an embodiment of the present invention. FIG. 2 is a side view of an example of a boiler provided with a conventional pulverized fuel combustion device. FIG. 3 is a configuration diagram of a wind box of a burner in one embodiment of a conventional pulverized fuel combustion device. FIG. 4 is a plan view of a burner in one embodiment of a conventional pulverized fuel combustion device. FIG. 5 is a schematic view of a combustion state in a furnace in an embodiment of a conventional pulverized fuel combustion device. FIG. 6 is a longitudinal sectional view of a burner structure in one embodiment of a conventional pulverized fuel combustion device. [Description of Signs] 1 Boiler furnace 2 Burner nozzle 3 Flame 4 Swirling flame vortex 5 High concentration combustion zone 7 Cyclone separator FD Rich mixture port FL Light mixture port A Combustion auxiliary air port

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Claims (1)

Claims: 1. A plurality of burner nozzles are arranged on a furnace wall such that a flame swirls in a furnace to form a vortex and has a U-shaped vertical section. A fine powder fuel supply pipe is connected via a cyclone separator, the fine powder fuel is separated into high-concentration fine powder and low-concentration fine powder by the cyclone separator, each fine powder is supplied to the burner nozzle, and high-concentration fine powder is supplied. was charged toward the inside of the vortex, a pulverized fuel combustion apparatus in which the burner nozzle is arranged so as to put toward the low concentration fines outside the vortex, spout surface of the burner nozzle is over the entire surface A pulverized fuel combustion device characterized in that the angle is inclined with respect to the ejection direction axis so as to be on the same plane parallel to the inner surface of the furnace.