JP2009204256A - Pulverized coal burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulverized coal burner capable of stably igniting pulverized coal fuel without complicating a device structure and securing a long reduction time of NOx generated by combustion. <P>SOLUTION: The pulverized coal burner 1 is provided with a mixed fluid supply passage 11 for supplying mixed fluid 101 of pulverized coal fuel and air; a combustion air supply passage 12 for supplying combustion air 102; a combustion nozzle 13 injecting the mixed fuel 101 and the combustion air 102 to burn the pulverized coal fuel; two splits 21a, 21b arranged approximately symmetrically to a central axis of the mixed fluid supply passage 11 and branching a flow passage of the mixed fluid 101; and combustion air injection parts 23a, 23b injecting the combustion air 102 branched from the combustion air supply passage 12 toward a region 31 sandwiched between the splits 21a, 21b. A flow passage area of the region 31 is set to contract toward the downstream direction of the mixed fluid 101. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pulverized coal burner used in a pulverized coal burning boiler that generates steam mainly using pulverized coal as a fuel.

  In order to increase the capacity of a pulverized coal-fired boiler, in order to increase the amount of combustion, it is necessary to increase the number of burners attached to the boiler or increase the capacity per burner. Here, when increasing the number of burners, since the number of burners on the horizontal cross section of the boiler furnace body is determined, the number of burner installation stages increases. Along with this, the height of the boiler increases and the construction cost of the boiler increases.

  On the other hand, when the capacity per burner is increased, the flow rate of the mixed fluid obtained by mixing the pulverized coal fuel and air ejected from the nozzle increases, and the pulverized coal flame collides with the inner wall of the furnace, causing slugging. And there is a problem that it is difficult to stably ignite pulverized coal fuel.

For the above problem, the mixed fluid supply path is divided into a plurality of right and left parts, and the mixed fluid is divided and blown to the virtual circle center side and the furnace wall side in the horizontal cross section in the furnace, and to the furnace wall side. A technique is known in which a concentration separator for reducing the concentration of pulverized coal fuel in a mixed fluid to be blown is disposed (see, for example, Patent Document 1).
Japanese Patent No. 3679998

  However, according to the above-described technique, it is necessary to dispose a light / dark separation device in each burner, which leads to complication of the device and an increase in cost. Further, since the combustion air is injected toward the outside of the mixed fluid ejection port, combustion in the vicinity of the burner is delayed, and there is a disadvantage that a long reduction time of NOx cannot be secured.

  The present invention has been made to solve the above-described problems, and can stably ignite pulverized coal fuel without having a complicated apparatus configuration, and can ensure a long reduction time of NOx generated by combustion. The purpose is to provide a charcoal burner.

In order to solve the above problems, the present invention employs the following means.
The present invention provides a mixed fluid supply path that supplies a mixed fluid of pulverized coal fuel and air, a combustion air supply path that is formed so as to surround the mixed fluid supply path and supplies combustion air, and the mixed fluid A combustion nozzle that injects the mixed fluid supplied from the supply passage and the combustion air supplied from the combustion air supply passage to burn the pulverized coal fuel, and a central axis of the mixed fluid supply passage Two splits arranged substantially symmetrically and branching the flow path of the mixed fluid, and a region provided in the split and sandwiching the combustion air branched from the combustion air supply path between the two splits A pulverized coal burner configured to reduce the flow path area of the region sandwiched between the splits in the downstream direction of the mixed fluid.

  According to the present invention, the flow path of the mixed fluid supplied from the mixed fluid supply path is branched by the split, and the flow path area of the region sandwiched between the splits is reduced in the downstream direction of the mixed fluid. Thereby, the density | concentration of the pulverized coal fuel of this area | region is raised, and combustion air is injected toward this area | region by the combustion air injection part. As a result, a high concentration region of the pulverized coal fuel is formed near the center of the mixed fluid supply path, and combustion air is injected into the high concentration region, so that the pulverized coal fuel is well ignited even near the center of the combustion nozzle. Can be done. As a result, since combustion air can be injected inward from the combustion nozzle, the combustion speed of the pulverized coal fuel is increased, and a reduction time of NOx generated by the combustion can be ensured for a long time.

  In the above invention, the split may have a triangular cross section with the upstream side of the mixed fluid as an apex in the longitudinal section of the mixed fluid supply path.

  Since the split has a triangular cross section with the upstream side of the mixed fluid as a vertex, the downstream direction of the mixed fluid not only in the region sandwiched between the two splits but also in the region sandwiched between the split and the mixed fluid supply path Accordingly, the flow path area is reduced. As a result, in the region sandwiched between the two splits and the region sandwiched between the split and the mixed fluid supply path, the pulverized coal fuel can be made high in concentration, and the combustion air injection unit and the combustion nozzle can be connected to these regions. By supplying combustion air, ignition of the pulverized coal fuel can be promoted.

In the above invention, the split may be provided with a protrusion on the surface.
By providing protrusions on the surface of the split, turbulent flow is generated in the flow of the mixed fluid, and ignition can be promoted by dispersing the pulverized coal fuel.

In the above invention, a connection member for connecting the two splits may be provided, and the connection member may have a triangular cross section with the upstream side of the mixed fluid as a vertex in the longitudinal section of the mixed fluid supply path.
The connecting member that connects the two splits has a triangular cross-section with the upstream side of the mixed fluid as a vertex, so that in the region sandwiched between the connecting member and the mixed fluid supply path, the flow path area according to the downstream direction of the mixed fluid Will be reduced. Thereby, since the high concentration area | region of pulverized coal fuel can be formed not only with a split but with a connection member, ignition of pulverized coal fuel can be accelerated | stimulated.

The said invention WHEREIN: It is good also as providing the combustion air adjustment part which adjusts the flow volume of the said combustion air injected from the said combustion nozzle.
The size of the combustion flame of pulverized coal can be adjusted by adjusting the flow rate of the combustion air injected from the combustion nozzle by the combustion air adjusting unit. Further, the direction of the combustion flame of pulverized coal can be adjusted by locally adjusting the flow rate of the combustion air injected from the combustion nozzle. For example, in a corner-fired boiler with four burners arranged at the corner, increasing the flow rate of combustion air supplied to the furnace wall increases the oxygen concentration on the furnace wall and reduces sulfur corrosion on the furnace wall. Can be prevented.

  According to the present invention, it is possible to stably ignite pulverized coal fuel without having a complicated device configuration and to ensure a long reduction time of NOx generated by combustion.

Hereinafter, one embodiment of the pulverized coal burner of the present invention will be described with reference to the drawings.
1 to 3 show a schematic configuration of a pulverized coal burner 1 according to the present embodiment, FIG. 1 is a longitudinal sectional view, FIG. 2 is a view taken along the line AA in FIG. 1, and FIG. It is a BB arrow line view.
As shown in FIG. 1, the pulverized coal burner 1 is formed so as to surround a mixed fluid supply path 11 that supplies a mixed fluid 101 of pulverized coal fuel and air, and the mixed fluid supply path 11. Combustion air supply passage 12 to be supplied, combustion nozzle 13 for injecting mixed fluid 101 supplied from mixed fluid supply passage 11 and combustion air 102 supplied from combustion air supply passage 12, and mixed fluid supply passage 11, two splits 21a and 21b that branch the flow path of the mixed fluid 101, and combustion air injection sections 23a and 23b provided in the splits 21a and 21b.

  The mixed fluid supply path 11 has a curved portion 15 that bends the flow path at a substantially right angle, and a reflection that reflects the pulverized coal fuel flowing through the mixed fluid 101 at a substantially right angle on the outer peripheral side of the curved portion 15. A portion 25 is provided. Thereby, the pulverized coal fuel in the mixed fluid 101 is prevented from being unevenly distributed. Moreover, the mixed fluid supply passage 11 is not provided with a throttle portion, so that the influence of abrasion caused by the pulverized coal fuel in the mixed fluid 101 is reduced.

  The combustion nozzle 13 injects the mixed fluid supplied from the mixed fluid supply passage 11 and injects the combustion air 102 supplied from the combustion air supply passage 12 toward the central axis of the mixed fluid supply passage 11. The pulverized coal fuel is combusted at the nozzle outlet.

The splits 21 a and 21 b are arranged substantially symmetrically with respect to the central axis of the mixed fluid supply path 11, and have a triangular cross section with the upstream side of the mixed fluid 101 as a vertex in the longitudinal section of the mixed fluid supply path 11. ing. By having such a shape, the flow path area of the region 31 sandwiched between the split 21 a and the split 21 b is reduced in the downstream direction of the mixed fluid 101.
As shown in FIG. 2, the splits 21 a and 21 b extend in a direction substantially orthogonal to the flow direction of the mixed fluid supply path 11, and are in contact with the wall surface of the mixed fluid supply path 11 for combustion. Holes 27 a and 27 b communicating with the air supply path 12 are provided. The combustion air 102 in the combustion air supply path 12 is supplied into the splits 21a and 21b from the holes 27a and 27b.

  As shown in FIG. 3, the combustion air injection sections 23a and 23b inject the combustion air 102 branched from the combustion air supply path 12 toward a region 31 sandwiched between the split 21a and the split 21b. It has become.

The effect | action of the pulverized coal burner 1 which has the said structure is demonstrated below.
When the mixed fluid 101 is supplied from the mixed fluid supply path 11 to the combustion nozzle 13, the flow path of the mixed fluid 101 is branched by the splits 21a and 21b. Here, since the flow path area of the region 31 sandwiched between the split 21a and the split 21b is configured to be reduced in the downstream direction of the mixed fluid 101, the pulverized coal fuel in the mixed fluid 101 in the region 31 is reduced. Concentration is increased. Then, the combustion air 102 is injected into the region 31 by the combustion air injection units 23a and 23b, and the combustion of the pulverized coal fuel in the region 31 is promoted.

  Further, since the splits 21a and 21b have a triangular cross section with the upstream side of the mixed fluid 101 as the apex in the longitudinal section of the mixed fluid supply path 11, the splits 21a and 21b are sandwiched between the splits 21a and 21b and the mixed fluid supply path 11. Also in the regions 33a and 33b, similarly to the region 31, the flow path area decreases in the downstream direction of the mixed fluid 101. The combustion air 102 is also injected from the combustion nozzle 13 to the regions 33a and 33b, and the combustion of the pulverized coal fuel is promoted.

  As described above, according to the pulverized coal burner 1 according to the present embodiment, the flow path of the mixed fluid 101 supplied from the mixed fluid supply path 11 is branched by the splits 21a and 21b and sandwiched between the split 21a and the split 21b. Since the flow path area of the region 31 is configured to be reduced in the downstream direction of the mixed fluid 101, the concentration of the pulverized coal fuel in the region 31 is increased, and the combustion air injection unit is directed toward the region 31. Combustion air 102 is injected by 23a and 23b. As a result, a high concentration region of pulverized coal fuel is formed near the center of the mixed fluid supply passage 11, and the combustion air 102 is injected into the high concentration region, so that the pulverized coal fuel also flows near the center of the combustion nozzle 13. Ignition can be performed satisfactorily. As a result, the combustion air 102 can be injected inward from the combustion nozzle 13, so that the combustion speed of the pulverized coal fuel is increased and the reduction time of NOx generated by the combustion can be ensured for a long time.

  In addition, since the splits 21a and 21b have a triangular cross section with the upstream side of the mixed fluid 101 in the longitudinal section of the mixed fluid supply path 11, the split 21a and 21b have not only the region 31 sandwiched between the split 21a and the split 21b, Also in the regions 33 a and 33 b sandwiched between the splits 21 a and 21 b and the mixed fluid supply path 11, the flow path area is reduced in the downstream direction of the mixed fluid 101. Thereby, the pulverized coal fuel can be made high in the regions 31, 33a, 33b, and the combustion air 102 is supplied to the regions 31, 33a, 33b from the combustion air injection sections 23a, 23b and the combustion nozzle 13. By doing so, ignition of the pulverized coal fuel can be promoted.

Moreover, in the pulverized coal burner 1 described above, as shown in FIG. 4, projections 41a and 41b may be provided on the surfaces of the splits 21a and 21b.
By providing the protrusions 41a and 41b on the surfaces of the splits 21a and 21b, it is possible to generate turbulence in the flow of the mixed fluid 101 and promote ignition by dispersing the pulverized coal fuel.

Further, in the pulverized coal burner 1 described above, as shown in FIG. 5, protrusions 43a and 43b may be provided at the downstream ends of the splits 21a and 21b.
By providing the protrusions 43a and 43b at the downstream ends of the splits 21a and 21b, turbulence can be generated in the flow of the mixed fluid 101, and ignition can be promoted by dispersing the pulverized coal fuel.

Moreover, in the pulverized coal burner 1 described above, as shown in FIG. 6 and FIG. 7, the pulverized coal burner 1 includes a connecting member 51 that connects the split 21a and the split 21b. It may have a triangular cross section with the upstream side of the mixed fluid 101 as an apex. Here, FIG. 7 is a CC arrow view of FIG.
Since the connecting member 51 has a triangular cross section with the upstream side of the mixed fluid 101 as the apex, a region 53 sandwiched between the connecting member 51 and the mixed fluid supply path 11 and a region 31 sandwiched between the connecting members 51. , The flow path area is reduced in the downstream direction of the mixed fluid 101. Thereby, since the high concentration area | region of pulverized coal fuel can be formed not only by split 21a, 21b but by the connection member 51, ignition of pulverized coal fuel can be promoted.

Moreover, in the pulverized coal burner 1 described above, as shown in FIGS. 8 and 9, only the holes 27 a and 27 b that connect the mixed fluid supply passage 11 and the combustion air supply passage 12 are provided as means, and the pulverized coal burner 1 can Combustion air 102 may be supplied into the splits 21a and 21b.
By injecting the combustion air 102 supplied from one direction from the combustion air injection sections 23a and 23b, the flow rate of the combustion air 102 injected from the combustion nozzle 13 can be locally adjusted, and the pulverized coal The direction of the combustion flame 8 can be adjusted. For example, as shown in FIG. 10, in the corner firing boiler 5 in which the four pulverized coal burners 1 are arranged at the corners, the flow rate of the combustion air 102 supplied to the furnace wall 6 side is increased, whereby the arrow 7 Air flow as shown in can be created. Thereby, the oxygen concentration by the side of the furnace wall 6 can be raised, and the sulfide corrosion of the furnace wall 6 can be prevented.

Moreover, in the pulverized coal burner 1 mentioned above, as shown in FIG. As a specific method for adjusting the flow rate of the combustion air 102, the combustion air adjusting unit 61 can be configured to be swingable, and the angle θ formed with the wall of the mixed fluid supply path 11 may be changed. It is good also as a structure which can insert / extract the air adjustment part 61 for use.
By adjusting the flow rate of the combustion air 102 injected from the combustion nozzle 13 by the combustion air adjusting unit 61, the size of the combustion flame of pulverized coal can be adjusted, and fine combustion control becomes possible.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, in the above-described embodiment, the splits 21a and 21b have been described as having a triangular cross section with the upstream side of the mixed fluid 101 in the longitudinal section of the mixed fluid supply path 11, but the split 21a and the split 21b have It suffices if the flow path area of the sandwiched region 31 is configured to be reduced in the downstream direction of the mixed fluid 101, and may be, for example, a trapezoidal section or a convex section.

It is a longitudinal cross-sectional view which shows the whole structure of the pulverized coal burner which concerns on one Embodiment of this invention. It is an AA arrow line view of FIG. It is a BB arrow line view of FIG. It is a schematic block diagram which shows the modification of FIG. It is a schematic block diagram which shows the modification of the split of FIG. It is a schematic block diagram which shows the modification of FIG. It is CC arrow line view of FIG. It is a schematic block diagram which shows the modification of FIG. It is a schematic block diagram which shows the modification of FIG. It is a cross-sectional view which shows the whole structure of a boiler provided with the pulverized coal burner of FIG. It is a schematic block diagram which shows the modification of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pulverized coal burner 5 Boiler 6 Furnace wall 11 Mixed fluid supply path 12 Combustion air supply path 13 Combustion nozzle 21a, 21b Split 23a, 23b Combustion air injection part 27a, 27b Hole 28a, 28b Hole 31 Area 33a, 33b Area 41a , 41b Protrusions 43a, 43b Protrusions 51 Connecting members 53 Region 61 Combustion air adjusting unit 101 Mixed fluid 102 Combustion air

Claims (5)

A mixed fluid supply passage for supplying a mixed fluid of pulverized coal fuel and air;
A combustion air supply passage which is formed so as to surround the mixed fluid supply passage and supplies combustion air;
A combustion nozzle for injecting the mixed fluid supplied from the mixed fluid supply passage and the combustion air supplied from the combustion air supply passage to burn the pulverized coal fuel;
Two splits arranged substantially symmetrically with respect to the central axis of the mixed fluid supply path and branching the mixed fluid flow path;
A combustion air injection unit that is provided in the split and injects the combustion air branched from the combustion air supply path toward a region sandwiched between the two splits;
A pulverized coal burner configured such that a flow path area of a region sandwiched between the splits is reduced in a downstream direction of the mixed fluid.   2. The pulverized coal burner according to claim 1, wherein the split has a triangular cross section having an upstream side of the mixed fluid as an apex in a longitudinal section of the mixed fluid supply path.   The pulverized coal burner according to claim 1 or 2, wherein a projection is provided on a surface of the split. A connecting member for connecting the two splits;
The pulverized coal burner according to any one of claims 1 to 3, wherein the connecting member has a triangular cross section whose apex is the upstream side of the mixed fluid in a longitudinal section of the mixed fluid supply path.   The pulverized coal burner according to any one of claims 1 to 4, further comprising a combustion air adjusting unit that adjusts a flow rate of the combustion air injected from the combustion nozzle.

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