JP7429501B2 - powder injection device - Google Patents

Description

The present invention relates to a powder injection device.

The following Patent Document 1 discloses a pulverized coal burner attached to a coal-fired boiler as an example of a powder injection device (see FIG. 6 of Patent Document 1). In a pulverized coal burner, a coal pulverizer pulverizes coal into pulverized coal, which is mixed with combustion air, and this mixed fluid is injected from a burner nozzle into a furnace to burn the pulverized coal. In such a pulverized coal burner, a good combustion state can be maintained by making the particle concentration of pulverized coal uniform at the injection port of the burner nozzle.

Japanese Patent Application Publication No. 2009-131793

In a pulverized coal burner, in order to maintain good combustion performance, it is necessary to eliminate unevenness in pulverized coal concentration at the nozzle outlet. Conventionally, a duct was used to flow pulverized coal from a tangent to the nozzle, and a baffle plate was provided on the inner circumferential surface of the nozzle to suppress swirling inside. The baffle plate extends parallel to the main flow direction of the mixed fluid and stops swirling of the pulverized coal to evenly distribute the pulverized coal near the inner peripheral surface of the nozzle.

However, there was a concern that the pulverized coal would not sufficiently collide with the baffle plate, resulting in uneven particle concentration of the pulverized coal. As a result, if a region with an extremely low or high particle concentration is formed, there is a problem in that flame stability decreases and exhaust gas contaminants (NO, CO, etc.) increase.
Furthermore, if the operating conditions change and the flow rates of pulverized coal and combustion air decrease, there has been concern that the momentum of the swirling flow of the mixed fluid will weaken and the particle concentration of pulverized coal will become non-uniform.

The present invention has been made in view of the above problems, and aims to provide a powder injection device that can evenly distribute powder near the inner circumferential surface of a nozzle regardless of operating conditions.

In order to solve the above problems, the present invention includes a nozzle that injects a mixed fluid of powder and gas, and supplies the mixed fluid along the inner peripheral surface of the nozzle to generate a swirling flow of the mixed fluid. A powder injection device is employed, in which the nozzle has a baffle plate extending in a direction crossing the main flow direction of the mixed fluid on an inner circumferential surface thereof.

Further, in the present invention, the baffle plate has a configuration in which a plurality of protrusions are formed at intervals in the mainstream direction.

Further, in the present invention, a configuration is adopted in which the baffle plate is formed in a spiral shape.

Further, in the present invention, a configuration is adopted in which the baffle plate is formed in a spiral shape that is reversely wound to the swirling flow.

Further, in the present invention, the nozzle includes an outer sleeve forming the inner circumferential surface, and an inner sleeve disposed inside the outer sleeve, and the inner sleeve has the turning surface on its outer circumferential surface. A configuration is adopted in which a sloped protrusion that guides the flow to the inner circumferential surface is provided, and the sloped protrusion is provided in a region where the baffle plate is arranged in the main flow direction.

In the present invention, the baffle plate provided on the inner peripheral surface of the nozzle is arranged to intersect with the main flow direction of the mixed fluid. When the flow rate of the mixed fluid increases or decreases, the number of times the mixed fluid turns before it is injected from the nozzle increases or decreases, but the flow of the mixed fluid in the mainstream direction (the axial direction along which the nozzle extends) does not change. Therefore, no matter what the operating conditions are, the powder always collides with the baffle plate, and the powder is evenly distributed near the inner peripheral surface of the nozzle.
Therefore, according to the present invention, it is possible to obtain a powder injection device that can evenly distribute powder near the inner circumferential surface of a nozzle regardless of operating conditions.

FIG. 1 is a perspective view showing the configuration of a pulverized coal burner in an embodiment of the present invention. FIG. 2 is a sectional view taken along the line AA in FIG. 1. FIG. 2 shows (a) an analytical model of a pulverized coal burner in an embodiment of the present invention, and (b) an analytical result of the particle concentration of pulverized coal using the analytical model. As a comparative example, (a) an analytical model of a conventional pulverized coal burner equipped with a baffle plate parallel to the main flow direction, and (b) an analytical result of the particle concentration of pulverized coal using the analytical model. It is a sectional view showing the composition of the baffle plate in another embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the powder injection device of this invention is demonstrated with reference to drawings. In addition, in the following description, a pulverized coal burner is illustrated as one embodiment of a powder injection device.

FIG. 1 is a perspective view showing the configuration of a pulverized coal burner 1 in an embodiment of the present invention. FIG. 2 is a sectional view taken along arrow AA in FIG.
The pulverized coal burner 1 injects a mixed fluid F of pulverized coal (powder) and combustion air (gas) into a furnace (not shown) to combust the pulverized coal. The pulverized coal burner 1 of this embodiment includes a nozzle 10, a mixed fluid supply section 20, and a wind box 30.

The nozzle 10 has an injection port 11 for ejecting the mixed fluid F, and a conveyance channel 12 for the mixed fluid F that reaches the injection port 11. The nozzle 10 is formed in a cylindrical shape, and has an injection port 11 formed at one end thereof. The conveyance channel 12 extends substantially linearly along the axis C1 of the nozzle 10 to the injection port 11. In this embodiment, the injection port 11 side of the nozzle 10 is constricted so that the mixed fluid F can be injected toward the axis C1.

The nozzle 10 has a cylindrical inner sleeve 13 and an outer sleeve 14 that are provided concentrically, and has a double-tube structure. The inner sleeve 13 has a diameter that gradually decreases from approximately the midpoint in the longitudinal direction toward the distal end, and has a constricted portion at the distal opening that rapidly decreases in diameter toward the distal end. The outer sleeve 14 is disposed concentrically around the outer circumference of the inner sleeve 13, has a substantially similar shape to the inner sleeve 13, and has a constricted portion whose diameter rapidly decreases toward the tip.

An oil burner (not shown) is inserted inside the inner sleeve 13. The oil burner is inserted into the axial position of the inner sleeve 13 and is connected to an air cylinder (not shown) so as to be movable along the axial direction. The oil burner protrudes from the inner sleeve 13 and injects oil when ignited, and retreats into the inner sleeve 13 during combustion to prevent burnout. A tertiary air pipe (not shown) that supplies tertiary air is connected to the inner sleeve 13 .

The conveyance channel 12 is formed between the inner sleeve 13 and the outer sleeve 14. That is, the conveyance channel 12 is formed in a ring shape. Specifically, the inner edge of the conveyance channel 12 is formed by the outer peripheral surface 15 of the inner sleeve 13. Further, the outer edge of the conveyance channel 12 is formed by the inner circumferential surface 16 of the outer sleeve 14.

The mixed fluid supply section 20 is connected to the side of the nozzle 10, as shown in FIG. The mixed fluid supply section 20 supplies the mixed fluid F to the conveyance channel 12. The mixed fluid supply section 20 supplies the mixed fluid F in a tangential direction along the inner circumferential surface 16 of the nozzle 10 (outer sleeve 14) to form a swirling flow S of the mixed fluid F. A pulverized coal supply device and a blower device (not shown) are provided upstream of the mixed fluid supply section 20, and a mixed fluid F in which pulverized coal and combustion air (primary air) are mixed in advance is introduced. come.

The wind box 30 mixes secondary air with the mixed fluid F injected from the nozzle 10, and is provided so as to surround the injection port 11 of the nozzle 10. This wind box 30 includes a plurality of air registers (not shown) disposed to surround the injection port 11 in a circular manner, and a plurality of inner vanes (not shown) disposed circumferentially inside the air register. ) and has. The air register adjusts the flow rate of secondary air, and the inner vane provides a swirling force to the secondary air supplied through the air register.

Pulverized coal pulverized by a coal pulverizer (not shown) is mixed with combustion air and supplied to the nozzle 10 via the mixed fluid supply section 20 . The mixed fluid F of pulverized coal and combustion air is supplied in the tangential direction of the inner circumferential surface 16 at the rear end side of the nozzle 10 to form a swirling flow S, and swirls in the circumferential direction along the inner circumferential surface 16 while flowing toward the tip side. and is injected from the injection port 11. The mixed fluid F injected from the injection port 11 is mixed with secondary air supplied from the wind box 30 and combusted.

The nozzle 10 includes a baffle plate 40 that evenly distributes the pulverized coal contained in the mixed fluid F near the inner circumferential surface 16 in order to improve flame stability. The baffle plate 40 stands up against the inner peripheral surface 16 of the nozzle 10 and collides with the mixed fluid F flowing along the inner peripheral surface 16. The baffle plate 40 has a rectangular cross section along the axis C1 shown in FIG. Note that the cross-sectional shape of the baffle plate 40 may be triangular or other polygonal, or may be rounded.

As shown in FIG. 2, the baffle plate 40 extends in a direction intersecting the mainstream direction of the mixed fluid F (the direction along the axis C1 along which the nozzle 10 extends). This baffle plate 40 intersects at an angle α with a reference plane C2 perpendicular to the axis C1. The angle α is preferably 10° or less, more preferably 5° or less. The baffle plate 40 of this embodiment extends in a direction substantially perpendicular to the axis C1, and the angle α is set to, for example, 3.5°.

The baffle plate 40 has a plurality of protrusions 41 formed at intervals in the mainstream direction. It is preferable that there are four or more protrusions 41, and more preferably five to seven protrusions. In this embodiment, six protrusions 41 are arranged at equal intervals.

The baffle plate 40 is formed in a spiral shape in which a plurality of protrusions 41 are connected. As shown in FIG. 2, this baffle plate 40 is formed in a spiral shape that is counter-wound to the swirling flow S of the mixed fluid F. That is, when the swirling flow S is clockwise around the axis C1, the baffle plate 40 swirls counterclockwise around the axis C1. Further, when the swirling flow S is counterclockwise around the axis C1, the baffle plate 40 swirls clockwise around the axis C1.

The nozzle 10 has an inclined protrusion 50 that guides the swirling flow S to the inner circumferential surface 16 where the baffle plate 40 described above is provided. The inclined protrusion 50 is formed in an annular shape on the outer peripheral surface 15 of the inner sleeve 13 . This inclined protrusion 50 is provided within a region X where the baffle plate is arranged in the mainstream direction of the mixed fluid F. The inclined protrusion 50 has an inclined surface 51 that becomes higher toward the tip side of the nozzle 10, and causes the pulverized coal contained in the mixed fluid F that has gathered at the center of the nozzle 10 to collide with the baffle plate 40.

Next, the operation of the pulverized coal burner 1 including the baffle plate 40 having the above configuration will be explained with reference to FIGS. 3 and 4.
FIG. 3 shows (a) an analytical model 100 of a pulverized coal burner according to an embodiment of the present invention, and (b) an analysis result of the particle concentration of pulverized coal using the analytical model 100. As a comparative example, FIG. 4 shows (a) an analytical model 200 of a conventional pulverized coal burner equipped with baffles parallel to the mainstream direction, and (b) an analysis of the particle concentration of pulverized coal using the analytical model 200. This is the result.

The analytical model 200 shown in FIG. 4(a) differs from the analytical model 100 shown in FIG. 3(a) in that it includes a baffle plate 240 parallel to the mainstream direction of the mixed fluid, and is the same in other respects. ing. As a result of analysis using this analytical model 200 under conditions where the flow rate of the mixed fluid F is reduced, as shown in FIG. It was confirmed that it was formed in a circular patch shape. For this reason, there is a concern that flame stability may deteriorate.

On the other hand, as a result of analysis using the analytical model 100 shown in FIG. 3(a) under the same conditions with a lower flow rate of mixed fluid F, as shown in FIG. 3(b), there was no region with abnormally high particle concentration. It was confirmed that a substantially uniform particle concentration was obtained in the vicinity of the inner circumferential surface 16 of the nozzle 10 along the circumferential direction. That is, in this embodiment, as shown in FIG. 2, the baffle plate 40 provided on the inner circumferential surface 16 of the nozzle 10 is arranged to intersect with the main flow direction of the mixed fluid F. When the flow rate of the mixed fluid F increases or decreases, the number of times the mixed fluid F turns before it is injected from the nozzle 10 increases or decreases, but the flow of the mixed fluid F in the mainstream direction (the axial direction in which the nozzle 10 extends) does not change. Therefore, regardless of the operating conditions, the pulverized coal always collides with the baffle plate 40, so that the pulverized coal is evenly distributed near the inner circumferential surface 16 of the nozzle 10.

In this embodiment, the baffle plate 40 forms a plurality of protrusions 41 at intervals in the mainstream direction. According to this configuration, the pulverized coal contained in the mixed fluid F collides with the baffle plate 40 multiple times in the mainstream direction, so that the effect of uniformizing the particle concentration near the inner circumferential surface 16 of the nozzle 10 is enhanced. The analysis results show that the particle concentration is made uniform in stages up to 4 protrusions 41, and when the number of protrusions 41 reaches 5 to 7, the particle concentration is sufficiently uniform, and when the number of protrusions 41 becomes 8 When the number exceeds 1, there is almost no improvement after that. Therefore, the number of protrusions 41 is preferably four or more, more preferably five to seven.

Moreover, in this embodiment, the baffle plate 40 is formed in a spiral shape. If the baffle plate 40 has a spiral shape, the protrusions 41 will overlap the entire circumferential direction of the inner circumferential surface 16 when viewed from the axial direction of the nozzle 10, so that the mixed fluid F will not reach any of the protrusions 41. A non-colliding path route is not formed. The pulverized coal burner 1 periodically cleans the pulverized coal deposited on the inner circumferential surface 16 of the nozzle 10, and when cleaning, only air is injected from the nozzle 10 to clean the inner circumferential surface 16. The accumulated pulverized coal is being discharged. Here, if the baffle plate 40 has a spiral shape, the pulverized coal will not accumulate at the base of the baffle plate 40, and the pulverized coal will be discharged from the injection port 11 while swirling in the circumferential direction along the inner circumferential surface 16. Therefore, maintenance becomes easier.

Moreover, the baffle plate 40 of this embodiment is formed in a spiral shape that is reversely wound with respect to the swirling flow S. According to this configuration, the baffle plate 40 easily collides with the mixed fluid F forming the swirling flow S, so that the effect of uniformizing the particle concentration near the inner circumferential surface 16 of the nozzle 10 is enhanced. Further, the inner sleeve 13 of the nozzle 10 is provided with an inclined protrusion 50 on its outer circumferential surface 15 that guides the swirling flow S to the inner circumferential surface 16, and the inclined protrusion 50 has a baffle plate 40 disposed in the mainstream direction. Since the pulverized coal contained in the mixed fluid F that has gathered at the center of the nozzle 10 collides with the baffle plate 40, the particle concentration near the inner circumferential surface 16 of the nozzle 10 is further reduced. Uniformity can be ensured.

As described above, according to the present embodiment described above, the nozzle 10 injects the mixed fluid F of pulverized coal and combustion air, and the mixed fluid F is supplied along the inner circumferential surface 16 of the nozzle 10, and the mixed fluid a mixed fluid supply section 20 that forms a swirling flow S of the mixed fluid F, and the nozzle 10 has a baffle plate 40 on its inner peripheral surface 16 that extends in a direction intersecting the mainstream direction of the mixed fluid F. By employing this, it is possible to obtain a pulverized coal burner 1 that can evenly distribute pulverized coal near the inner circumferential surface 16 of the nozzle 10 regardless of operating conditions.

Although preferred embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the above embodiments. The various shapes and combinations of the constituent members shown in the above-described embodiments are merely examples, and can be variously changed based on design requirements and the like without departing from the gist of the present invention.

FIG. 5 is a sectional view showing the configuration of a baffle plate 40A in another embodiment of the present invention. In addition, in FIG. 5, the same reference numerals are attached to the same or equivalent configurations as those in the above-described embodiment, and the description thereof will be simplified or omitted.
The baffle plate 40A shown in FIG. 5 is formed in a ring shape. A plurality of baffle plates 40A are arranged at intervals in the mainstream direction of the mixed fluid F. Further, the baffle plate 40A extends along the inner circumferential surface 16 in a direction perpendicular to the mainstream direction of the mixed fluid F.

Also in the baffle plate 40A shown in FIG. 5, the pulverized coal contained in the mixed fluid F collides with the baffle plate 40A multiple times in the mainstream direction, so that the particle concentration near the inner circumferential surface 16 of the nozzle 10 can be made uniform. I can do it. However, since it is necessary to arrange a plurality of baffle plates 40A, it takes more effort to adjust the intervals between the baffle plates 40A than in the embodiment described above. Note that a notch may be formed in the baffle plate 40A so that accumulated pulverized coal can be discharged during cleaning. The cutouts are preferably arranged so as not to overlap when viewed from the axial direction of the nozzle 10 so that a path route is not formed.

Further, for example, in the above embodiment, a configuration in which the powder injection device of the present invention is applied to the pulverized coal burner 1 has been described, but the present invention is not limited to this configuration. It can also be applied to cold spray equipment that forms a coating layer on the surface of an object. Further, the present invention can be applied not only to the above-mentioned industrial fields but also to powder injection devices in general that jet powder in the same way in the food and pharmaceutical fields.

1 Pulverized coal burner 10 Nozzle 13 Inner sleeve 14 Outer sleeve 16 Inner circumferential surface 20 Mixed fluid supply section 40 Baffle plate 41 Projection 50 Inclined projection C1 Axial center F Mixed fluid S Swirling flow X region

Claims (2)

a nozzle that sprays a mixed fluid of powder and gas;
a mixed fluid supply unit that supplies the mixed fluid along the inner circumferential surface of the nozzle to form a swirling flow of the mixed fluid,
The nozzle has a baffle plate on its inner peripheral surface that extends in a direction intersecting the mainstream direction of the mixed fluid,
The baffle plate has 5 to 7 protrusions formed at intervals in the mainstream direction, and is formed in a spiral shape that is opposite to the swirling flow in which the 5 to 7 protrusions are connected. A powder injection device characterized by: The nozzle includes an outer sleeve forming the inner peripheral surface, and an inner sleeve disposed inside the outer sleeve,
The inner sleeve has an inclined protrusion on its outer circumferential surface that guides the swirling flow to the inner circumferential surface,
The powder injection device according to claim 1 , wherein the inclined protrusion is provided in a region where the baffle plate is arranged in the mainstream direction.

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