JP3680002B2 - Fine powder fuel combustion system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulverized fuel combustion apparatus applied to a boiler furnace for thermal power generation, a chemical industrial furnace, or the like.
[0002]
[Prior art]
FIG. 6 is a horizontal sectional view showing an example of a conventional pulverized fuel combustion apparatus. In the figure, (1) is a burner nozzle, (2) is a burner nozzle opening surface, (3) is a pulverized fuel supply pipe, (4) is a combustion auxiliary air supply path, (5) is a wind box, and (6) is a furnace A wall pipe, (7) is a furnace side surface, and (11) is an extended surface of the furnace side surface.
[0003]
The mixed flow of the pulverized fuel and the carrier air passes through the pulverized fuel supply pipe (3), is guided to the burner nozzle (1), and is ejected from the burner nozzle opening surface (2) toward the furnace. The combustion auxiliary air passes through the combustion auxiliary air supply passage (4), is guided to the burner nozzle (1), and is ejected from the burner nozzle opening surface (2) into the furnace in the same manner as the pulverized fuel and the carrier air. .
[0004]
The vertical planes passing through these ejection direction axes (8) are not orthogonal to the furnace side surface (7) but are inclined. The finely pulverized fuel, the carrier air, and the combustion auxiliary air that are ejected form a flame while being diffused and mixed in the furnace. At this time, if a flame collides with the furnace wall tube (6) or a phenomenon such as licking the furnace wall surface (6) occurs, the flame is cooled by the furnace wall tube (6), and the unburned ash content is reduced. There is a possibility that a combustible deterioration such as an increase or a so-called clinker trouble that the clinker adheres to the furnace wall pipe (6) may occur.
[0005]
Therefore, conventionally, in order to prevent the flame from colliding with the furnace wall pipe (6), the furnace wall pipe located in the vicinity of the burner nozzle (1) is disposed on the extension surface (11) of the furnace side surface. In consideration of the spread of the flame, as shown by reference numeral (26), it was arranged so as to be aligned with the furnace side surface (7) and an angle α toward the wind box (5) side.
[0006]
The jetting direction axis line in which the combustion auxiliary air is jetted into the furnace is coaxial with the jetting direction axis (8) in which the pulverized fuel and the carrier air are jetted into the furnace. The cross-sectional shape of the burner nozzle (1) is symmetrical with respect to a vertical plane passing through the ejection direction axis (8) as a symmetry plane.
[0007]
FIG. 7 shows a structural conceptual diagram of a furnace wall tube (6) arranged around the conventional pulverized fuel combustion apparatus, a so-called burner panel structural conceptual diagram (plan view). Each line element shown in the figure means one furnace wall pipe (6).
[0008]
[Problems to be solved by the invention]
The conventional pulverized fuel combustion apparatus has an angle α with respect to the furnace side surface (7) as shown in the reference (26) in consideration of prevention of an increase in unburned ash content and prevention of clinker trouble. It is arranged so as to be lined up toward the box (5) side, and has a structure that can fully demonstrate its performance. However, by adopting such a structure, the following problems have arisen and improvement has been required. That is,
1) Since a part (26) of the furnace wall tube is not located in the same plane as the furnace side surface (7) or the extended surface (11) of the furnace side surface, it is not easy to work on the furnace wall tube panel or the burner panel.
[0009]
2) The furnace wall support structure has a complicated structure.
[0010]
3) In the case of a large-capacity burner and a large-capacity boiler, the length L of the furnace wall tube row indicated by reference numeral (26) in FIG. May be difficult to access, which may cause inconvenience to maintenance.
[0011]
4) Since the burner nozzle (1) is relatively disposed on the outside of the furnace, maintenance is easily impaired.
[0012]
[Means for Solving the Problems]
In order to solve the above-described conventional problems, the present inventor is provided on a side surface of a vertical prismatic furnace and is connected to the burner nozzle that ejects a mixed flow of pulverized fuel and air. A fine powder fuel supply pipe that supplies fine powder fuel and air; and a wind box that forms a combustion auxiliary air supply passage around the fine powder fuel supply pipe, and a vertical plane passing through the jet direction axis of the mixed flow in pulverized fuel combustion apparatus that is not orthogonal to the side of the furnace, the shape of the burner nozzle is asymmetrical with respect to the vertical plane, and the end opening surface side and the same plane of the furnace of the burner nozzle The present invention proposes a pulverized fuel combustion device that is located inside.
[0013]
The pulverized fuel combustion apparatus of the present invention has the above-described configuration, and the shape of the burner nozzle is asymmetrical with respect to the vertical plane passing through the jet direction axis of the mixed flow of pulverized fuel and air, and the tip of the burner nozzle the opening surface is positioned within the side and the same plane of the furnace, pulverized fuel and the carrier air, as well as mixed flow of the combustion auxiliary air ejected from the opening of the burner nozzles, furnace side and the extension surface or these surfaces thereof A flame can be formed on the inner side of the furnace than in the vicinity of.
Therefore, it is possible to prevent a phenomenon in which the flame collides with the furnace wall tube or licks the furnace wall tube.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a horizontal sectional view showing a pulverized fuel combustion apparatus according to a first embodiment of the present invention. In the figure, (1) is a burner nozzle, (2) is a burner nozzle opening surface, (3) is a pulverized fuel supply pipe, (4) is a combustion auxiliary air supply path, (5) is an air box, and (6) is A furnace wall pipe, (7) shows a furnace side surface.
[0015]
A jetting direction axis (8) through which finely pulverized fuel and carrier air are jetted into the furnace is coaxial with a jetting direction axis through which combustion auxiliary air is jetted into the furnace, and the vertical plane passing through these axes is the side surface of the furnace (7 ) Is not vertical but inclined. The shape of the burner nozzle (1) is asymmetrical with respect to the vertical plane passing through the ejection direction axis (8), unlike the conventional one shown in FIG.
[0016]
By adopting such a shape, the burner nozzle opening surface (2) can be located in the same plane as the furnace side surface (7), and the furnace wall tube is angled with respect to the furnace side surface as in the prior art. Even if it does not arrange | position toward a box side, it can be made to burn without producing the phenomenon that a flame collides with a furnace wall pipe (6) or licks a furnace wall pipe (6).
[0017]
FIG. 2 is a structural conceptual diagram of a furnace wall pipe (6) disposed around the pulverized fuel combustion apparatus of the present embodiment, that is, a so-called burner panel structural conceptual diagram (plan view). As compared with the conventional case shown in FIG. 7, it can be seen that the burner panel structure can be greatly simplified by the present invention.
[0018]
FIG. 3 is a diagram schematically illustrating the flow state in the vicinity of the burner portion in the present embodiment. In this figure, (15) is a schematic diagram of a pulverized fuel supply pipe or combustion auxiliary air supply path, (16) is a schematic diagram of a burner nozzle, and (17) is an interior of a furnace of pulverized fuel and carrier air or combustion auxiliary air. (18) is a schematic diagram of a furnace wall tube arranged toward the wind box at an angle α with respect to the side surface of the furnace, and an arrow (19) is a schematic diagram of a swirling flame in the furnace. .
[0019]
The pulverized fuel combustion apparatus according to the present embodiment differs from the conventional burner in basic flow characteristics in the vicinity of the burner. First, as shown in FIG. 3 (a), the burner nozzle opening surface (2) has an angle of β with respect to a surface perpendicular to the axis (8) of the pulverized fuel and carrier air into the furnace. In the form, in the burner nozzle wall surface (20) in which the flow path of the pulverized fuel and the jet flow of the carrier air or the combustion auxiliary air becomes long, the opposite wall surface, that is, the flow path of the jet flow of the pulverized fuel and the carrier air or combustion auxiliary air Since the pressure loss of the jet becomes larger than that of the burner nozzle wall surface (21) whose length becomes shorter, the jet direction of the jet is actually deviated from the axis (8) as indicated by the arrow (22) on the wall surface (21) side. To deflect. The degree of deflection varies depending on the angle β and the frictional resistance coefficient of the inner surfaces of the wall surfaces (20) and (21).
[0020]
Further, as shown in FIG. 3B, in the conventional pulverized fuel combustion apparatus, the jet flows along the axis line (18) due to the influence of the furnace wall pipe (18) arranged toward the wind box side at an angle α with the furnace side surface. 8) to (23) tend to be deflected. However, in this embodiment, since the arrangement of the furnace wall tube is different from that of the furnace wall tube (18), the degree of deflection is reduced. The jet is as shown in (24).
[0021]
Thus, the burner jet in the present embodiment (finally) due to the influence of the swirling flame in the furnace (19) on the jet, together with the influence of the difference in the flow mode in the vicinity of the burner part from the conventional pulverized fuel combustion apparatus. 22) It is estimated that the jetting direction of 22) is actually deflected by a maximum of 15 to 20 degrees from the axis (8).
[0022]
FIG. 4 is a horizontal sectional view showing a pulverized fuel combustion apparatus according to the second embodiment of the present invention. In this embodiment, the swirl type dispersion device (13) is provided on the bent nozzle (1) side of the bent portion (12) or the bent portion (12) where the pulverized fuel supply pipe (3) is connected to the burner nozzle (1). It is an example of the pulverized fuel combustion apparatus which is a pulverized fuel supply pipe (3) which is installed and a core type density separator (14) is installed in the vicinity of the burner nozzle (1).
[0023]
In this figure, the mixed flow of the pulverized fuel and the carrier air that has flowed into the bent portion (12) from the direction of the arrow produces a density distribution due to the centrifugal force in the bent portion (12), and the concentration of the pulverized fuel becomes the bent portion. It becomes darker on the outer peripheral side of (12) and conversely thinner on the inner peripheral side.
[0024]
This density distribution is dispersed so that the distribution is uniform by the action of the swirler type disperser (13). Thereafter, the mixed stream having a uniform concentration is subjected to concentration separation so as to obtain an optimum combustion state by a core-type concentration separator (14), and is jetted into the furnace through a burner nozzle (1).
[0025]
FIG. 5 is a front view of the pulverized fuel combustion apparatus according to the third embodiment of the present invention as seen from inside the furnace.
In the present embodiment, the wind box is separated from each other by a plurality of unit wind boxes (two sets in the illustrated example) composed of two pulverized fuel supply pipes (3) and five combustion auxiliary air supply paths (4). Is formed. In this figure, the burner nozzle opening surface (2) has a plurality of types of shapes such as a triangle, a rectangle, and a combination of a semicircle and a straight line.
[0026]
【The invention's effect】
The following effects can be obtained by the present invention.
1) The furnace wall tube and burner panel can be easily constructed.
2) A furnace wall support structure having a simple structure with low cost can be adopted.
3) Even in the case of a large-capacity burner and a large-capacity boiler, it is possible to easily access the periphery of the furnace wall and to improve the maintainability.
4) The position of the burner nozzle can be arranged on the inner side of the furnace more than before, and the maintenance property can be improved.
[Brief description of the drawings]
FIG. 1 is a horizontal sectional view showing a pulverized fuel combustion apparatus according to a first embodiment of the present invention.
FIG. 2 is a structural conceptual diagram of a furnace wall tube according to the embodiment.
FIG. 3 is a diagram schematically illustrating a flow state in the vicinity of a burner portion in the embodiment.
FIG. 4 is a horizontal sectional view showing a pulverized fuel combustion apparatus according to a second embodiment of the present invention.
FIG. 5 is a front view showing a pulverized fuel combustion apparatus according to a third embodiment of the present invention.
FIG. 6 is a horizontal sectional view showing an example of a conventional pulverized fuel combustion apparatus.
FIG. 7 is a structural conceptual diagram of a furnace wall tube related to the conventional pulverized fuel combustion apparatus.
[Explanation of symbols]
(1) Burner nozzle (2) Burner nozzle opening surface (3) Fine powder fuel supply pipe (4) Combustion auxiliary air supply path (5) Wind box (6) Furnace wall pipe (7) Furnace side face (8) Fine powder fuel And the jet direction axis of the carrier air (11) Extension surface of the furnace side surface (12) Bending part of fine powder fuel supply pipe (13) Swirler type distributor (14) Core type density separator (15) Fine powder fuel or combustion auxiliary Air supply pipe schematic diagram (16) Burner nozzle schematic diagram (17) Ejection direction velocity distribution (18) Schematic diagram of furnace wall tube arranged on the windbox side from the furnace side surface (19) Schematic of swirling flame in the furnace Figure (20) Burner nozzle wall surface (21) with longer jet flow path length Burner nozzle wall surface (22) with shorter jet flow path length Deflection jet flow direction (23) Deflection jet in conventional burner ( 24) In the burner of the present invention Deflection jet (26) Furnace wall tube placed on the wind box side at an angle α with the furnace side

Claims (1)

A burner nozzle that is provided on a side surface of a vertical rectangular cylindrical furnace and ejects a mixed flow of pulverized fuel and air; a pulverized fuel supply pipe that is connected to the burner nozzle and supplies pulverized fuel and air; A pulverized fuel combustion apparatus comprising a wind box forming a combustion auxiliary air supply passage around the pulverized fuel supply pipe, wherein a vertical plane passing through the jet direction axis of the mixed flow is not orthogonal to a side surface of the furnace, the shape of the burner nozzle is asymmetrical with respect to the vertical plane, and pulverized fuel combustion apparatus end opening face of the burner nozzle, characterized in that located in the side surface and the same plane of the furnace.

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