WO2019022059A1

WO2019022059A1 - Powder fuel burner

Info

Publication number: WO2019022059A1
Application number: PCT/JP2018/027644
Authority: WO
Inventors: 貴弘小崎; 誠越前屋; 恵美大野; 隆政伊藤
Original assignee: 株式会社Ihi
Priority date: 2017-07-25
Filing date: 2018-07-24
Publication date: 2019-01-31

Abstract

This powder fuel burner (1) comprises: a nozzle (4) that delivers air and powder fuel along a nozzle axis line; and a powder fuel guidance unit (6) that is erected on the inner circumferential face of the nozzle (4) toward the inside in the radial direction of the nozzle (4) and that guides at least some of the powder fuel flowing in the nozzle (4) toward the inside in the radial direction.

Description

Powder fuel burner

The present disclosure relates to a powder fuel burner.
Priority is claimed on Japanese Patent Application No. 201-143,502, filed July 25, 2017, the content of which is incorporated herein by reference.

For example, in Patent Document 1, a flame holder is installed between the inner center and the outer peripheral portion of the powder fuel jet hole (pulverized coal jet hole), and the flame holder is made of powder fuel (dust coal). A combustion device (powder fuel burner) is disclosed which causes the concentrate stream to collide. In the combustion by such a powder fuel burner, a large amount of nitrogen oxides are discharged, so it is required to reduce the discharged nitrogen oxides.

Japanese Patent Application Laid-Open No. 8-135919

By the way, in a powder fuel burner, at the center of a flame to be formed, a reduction region is formed in which the oxygen concentration is low and nitrogen oxides are reduced. However, in the conventional powder fuel burner, the powder fuel (pulverized coal) spreads radially outward in response to the swirl of the transfer air and the internal circulation flow from the inside of the furnace. Therefore, the powdered fuel is not sufficiently supplied to the reduction region, and it is difficult to reduce the emission amount of nitrogen oxides.

The present disclosure has been made in view of the above-described problems, and aims to reduce the emission amount of nitrogen oxides by supplying a powdered fuel to a reduction region.

The powder fuel burner according to one aspect of the present disclosure is provided so as to stand radially inward of the nozzle portion from the inner circumferential surface of the nozzle portion that discharges air and powdered fuel along the nozzle axis, and the nozzle portion. And a powder fuel guide portion for guiding at least a part of the powder fuel flowing inside the nozzle portion radially inward.

In the powder fuel burner according to the above aspect, the powder fuel guide portion is provided radially inward from the opening end of the nozzle portion, and a plurality of the powder fuel guide portions are arranged at intervals in the circumferential direction of the nozzle portion. It may have a current plate.

In the powder fuel burner of the above aspect, the powder fuel guide portion is provided on the inner peripheral surface of the nozzle portion, and protrudes toward the flow direction of the powder fuel and supports the flow straightening plate. You may have.

The powder fuel burner according to the above aspect may further include a gap adjusting unit configured to adjust the width of the gap between the straightening vanes.

In the powder fuel burner of the above one aspect, the powder fuel may be pulverized coal.

According to the present disclosure, there is provided a powder fuel guiding portion for guiding at least a part of the powder fuel flowing inside the nozzle portion radially inward. Thus, the powder fuel flowing on the inner wall side of the nozzle portion can be guided radially inward, and the concentration of the powder fuel on the center side of the nozzle portion can be increased. Therefore, the powder fuel burner of the present disclosure can sufficiently supply the powdered fuel to the reduction region at the center of the flame, and can reduce the emission of nitrogen oxides.

1 is a cross-sectional view including a portion of a pulverized coal burner and a furnace in accordance with an embodiment of the present disclosure. It is a front view of the baffle plate with which the pulverized coal burner in one embodiment of the present disclosure is provided. It is a perspective view which shows the support part of the baffle plate with which the pulverized coal burner in one embodiment of this indication is provided. It is a front view which shows the clearance gap adjustment part with which the pulverized coal burner in one embodiment of this indication is provided.

Hereinafter, an embodiment of a powder fuel burner according to the present disclosure will be described with reference to the drawings. In the present embodiment, a pulverized coal burner using pulverized coal as a powdered fuel will be described as an example of the powdered fuel burner. However, powdered fuel is not limited to pulverized coal. For example, the powder fuel burner according to the present disclosure may be a biomass fuel burner using biomass fuel such as finely crushed wood pellets as powder fuel.

FIG. 1 is a cross-sectional view including a pulverized coal burner 1 (powder fuel burner) and a part of a furnace wall 100 in the present embodiment.

As shown in FIG. 1, a furnace opening 110 communicating the inside with the outside is formed in a furnace wall 100 provided with the pulverized coal burner 1 in the present embodiment. A throat is formed in the furnace opening 110 so as to expand in diameter toward the inside of the furnace wall 100.

The pulverized coal burner 1 is an apparatus which burns pulverized coal which is powdered coal and forms a flame inside the furnace wall 100. The pulverized coal burner 1 is provided adjacent to the furnace opening 110 of the furnace wall 100, and the pulverized coal supply pipe 2 (powder fuel supply pipe), the oil gun 3, the burner nozzle 4 (nozzle portion), and air It has the supply part 5 and the pulverized coal guide part 6 (powder fuel guide part).

The pulverized coal supply pipe 2 is vertically connected to the burner nozzle 4 as shown in FIG. The pulverized coal supply pipe 2 is connected to a pulverized coal mill (not shown), and the pulverized coal supply flow path R1 (powder fuel supply flow) which circulates in a state where the pulverized coal and the primary air are mixed in the inside of the pipe Road is formed. Pulverized coal is supplied to the burner nozzle 4 via the pulverized coal supply flow path R1.

The oil gun 3 is a cylindrical tube formed around the nozzle axis L, and is disposed toward the furnace opening 110 of the furnace wall 100. The oil gun 3 is connected to a tank (not shown) in which liquid fuel such as heavy oil or light oil is stored, and the liquid fuel flows inside. The oil gun 3 discharges atomized liquid fuel toward the furnace opening 110 of the furnace wall 100 for ignition in the early stage of combustion of pulverized coal. Further, an ignition device (not shown) is provided in the vicinity of the discharge port of the oil gun 3, and the liquid fuel discharged from the oil gun 3 is ignited by the ignition device. The oil gun 3 is movable along the nozzle axis L direction. Normally, the open end of the oil gun 3 is disposed so as to be inside the open end of the burner nozzle 4, and the open end of the oil gun 3 is protruded toward the furnace wall 100 when discharging liquid fuel. .

The burner nozzle 4 is a pipe formed concentrically with the oil gun 3 around the nozzle axis L outside the oil gun 3. Further, the opening of the burner nozzle 4 is disposed toward the furnace opening 110 of the furnace wall 100. A pulverized coal discharge flow path R2 (powder fuel discharge flow path) is formed between the inner peripheral surface of the burner nozzle 4 and the outer wall surface of the oil gun 3. Pulverized coal and primary air supplied from the pulverized coal supply pipe 2 flow toward the inside of the furnace wall 100 through the pulverized coal discharge flow path R2.

The air supply unit 5 is a device for supplying secondary air to the flame, and has a windbox 5a, an outer throat 5b, an inner throat 5c, a main air adjusting mechanism 5d, and an auxiliary air adjusting mechanism 5e. doing. The wind box 5 a is a box-like member provided outside the burner nozzle 4 and near the discharge port of the oil gun 3. The secondary air is supplied to the wind box 5a in a heated state. The outer throat 5 b connects the wind box 5 a and the furnace opening 110, and the diameter is reduced from the wind box 5 a toward the furnace opening 110.

The inner throat 5 c is a substantially annular member provided between the outer throat 5 b and the burner nozzle 4. The inner throat 5 c is reduced in diameter toward the furnace opening 110. Further, an air discharge flow path R3 for supplying secondary air (air for combustion) to the furnace wall 100 is formed between the outer throat 5b and the inner throat 5c. In addition, between the inner throat 5 c and the burner nozzle 4, an auxiliary air discharge flow path R 4 for supplying secondary air to the furnace wall 100 is formed.

The main air adjustment mechanism 5d is provided upstream of the air discharge flow passage R3 and the auxiliary air discharge flow passage R4. The main air adjustment mechanism 5d has a vane and a drive device such as a motor for rotating the vane, and the air flowing into the air discharge passage R3 and the auxiliary air discharge passage R4 by adjusting the direction of the vanes. Adjust the turning force of. The auxiliary air adjustment mechanism 5e is provided on the upstream side of the auxiliary air discharge flow passage R4, and finely adjusts the swirling force of the secondary air flowing to the auxiliary air discharge flow passage R4 by the vanes. The swirling force of the secondary air supplied to the furnace wall 100 is adjusted by the main air adjustment mechanism 5d and the auxiliary air adjustment mechanism 5e.

The pulverized coal guide portion 6 has a straightening vane portion 6 a provided at an end portion of the burner nozzle 4, a support portion 6 b, and a gap adjustment portion 6 c. As shown in FIG. 2, the current plate portion 6 a is provided at an end portion of the burner nozzle 4, and an annular frame portion 6 a 1 disposed on the inner wall of the burner nozzle 4 and the frame portion 6 a 1 at the inner periphery of the frame portion 6 a 1 It is a comb-like annular member having a plurality of (in this embodiment, 10) flow straightening plates 6a2 arranged in parallel and at equal intervals in the circumferential direction of the burner nozzle 4.
The straightening vane 6a2 is formed in a flat plate shape surrounded by two sides extending in the radial direction of the frame 6a1 and two sides in an arc shape, and is erected inward in the radial direction of the burner nozzle 4. The surface of the straightening vane 6a2 which is disposed on the upstream side in the direction of pulverized coal flow is joined to the support portion 6b over the entire surface.

As shown in FIG. 3, the support portion 6 b is a substantially triangular prism-shaped member provided on the upstream side of the flow direction of the pulverized coal of the flow control plate 6 a 2 of the flow control plate portion 6 a. One surface of the support 6 b is joined to the straightening vane 6 a 2, and the other surface of the support 6 b is joined to the inner circumferential surface of the burner nozzle 4. The support portion 6 b is disposed such that a taper is formed so as to protrude from the downstream side of the pulverized coal flow direction toward the upstream side. Thereby, while stably supporting the straightening vane 6a2 from the upstream side, the resistance of the pulverized coal and the primary air by the straightening vane portion 6a is reduced, and the pulverized coal is prevented from being deposited inside the straightening vane 6a2. There is.

As shown in FIG. 4, the gap adjusting portion 6c has a movable straightening plate portion 6c1 and a projection 6c2. The movable straightening plate portion 6c1 has an annular frame portion 6c3 and a ring shape having a plurality of plate portions 6c4 arranged at equal intervals to the installation intervals of the straightening vanes 6a2 of the straightening plate portion 6a on the inner periphery of the frame portion 6c3. It is a member. The movable straightening vane portion 6c1 is disposed parallel to the straightening vane 6a2 on the downstream side of the flow direction of the pulverized coal with respect to the straightening vane 6a2. In the frame portion 6c3, a plurality of groove portions 6c5 are formed in an arc shape along the circumferential direction of the burner nozzle 4. The protruding portion 6c2 is attached so as to protrude in the direction along the nozzle axis L from the surface of the frame portion 6a1 of the straightening vane 6a2 which is disposed on the downstream side of the pulverized coal flow direction. The protrusion 6c2 is engaged with the groove 6c5 of the movable straight plate portion 6c1 and is movable along the groove 6c5.

Subsequently, the operation of the pulverized coal burner 1 having the above-described configuration will be described with reference to FIGS. 1 and 4.
When the pulverized coal and the primary air having passed through the pulverized coal supply pipe 2 flow into the burner nozzle 4, they move toward the furnace wall 100 along the tube wall of the burner nozzle 4 inside the burner nozzle 4 and are moved to the furnace wall 100. Supplied. The pulverized coal supplied from the burner nozzle 4 to the furnace wall 100 is ignited in a state of being mixed with the secondary air supplied from the air supply unit 5.

A portion of the pulverized coal passing through the burner nozzle 4 flows along the slope (taper surface) of the support portion 6b, and is discharged to the outside from the gap between the flow straightening plates 6a2 arranged side by side. The remaining pulverized coal passing through the burner nozzle 4 is guided radially inward of the burner nozzle 4 (central portion of the burner nozzle 4) by the support portion 6b and the straightening vane 6a2, and from the circular opening inside the straightening vane portion 6a. It is discharged.

Further, the movable straightening plate portion 6c1 of the gap adjusting portion 6c is rotated according to the amount of combustion required in the pulverized coal burner 1, and the plate portion 6c4 of the movable straightening plate portion 6c1 is made of the straightening plate 6a2 as shown in FIG. Overlap in the gap. Thus, the width of the gap between the straightening vanes 6a2 in plan view can be changed, and the flow distribution of pulverized coal at the discharge port of the burner nozzle 4 can be changed. When the width of the gap between the straightening vanes 6a2 is narrowed, the amount of pulverized coal in the vicinity of the inner wall of the burner nozzle 4 becomes lower, and the concentration of pulverized coal in the central portion of the burner nozzle 4 becomes higher.

According to the pulverized coal burner 1 in the present embodiment, the pulverized coal guiding portion 6 is provided. The flow control plate 6a2 of the pulverized coal guide portion 6 prevents the pulverized coal from collecting near the inner peripheral surface (radial direction outer side) of the burner nozzle 4 and allows the pulverized coal to flow to the central portion (radially inner side) of the burner nozzle 4 Can be guided to. Thus, when the pulverized coal is discharged from the burner nozzle 4, a large amount of pulverized coal can be supplied to the reduction region formed in the center of the flame. Therefore, the pulverized coal burner 1 can reduce many nitrogen oxides in the reduction region, and can suppress the discharge amount of nitrogen oxides.

In addition, the pulverized coal burner 1 in the present embodiment includes a support portion 6b that supports the straightening vane 6a2 of the straightening vane portion 6a from the upstream side. The support portion 6 b disperses the pressure of the pulverized coal and the primary air flowing at high speed from the upstream side toward the current plate 6 a 2 to stably support the current plate 6 a 2. Further, the support portion 6b of the present embodiment is formed into a tapered shape that protrudes toward the upstream side from the straightening vane 6a2 to reduce the resistance of the pulverized coal and the primary air, and the pulverized coal is straightened along the tapered surface. It can be guided towards the gap between each other.

Furthermore, according to the pulverized coal burner 1 in the present embodiment, the width of the gap between the straightening vanes 6a2 can be changed by the gap adjusting unit 6c. As a result, the width of the gap between the straightening vanes 6a2 is changed between the case where it is desired to burn stably and the case where the amount of nitrogen oxide emissions is reduced, and the space is supplied to the outer region and the central region of the flame. The amount (percentage) of pulverized coal can be changed.

The preferred embodiments of the present disclosure have been described above with reference to the drawings, but the present disclosure is not limited to the above-described embodiments. The shapes, combinations, and the like of the constituent members shown in the above-described embodiment are merely examples, and various changes can be made based on design requirements and the like without departing from the spirit of the present disclosure.

In the above embodiment, the pulverized coal guide portion 6 of the pulverized coal burner 1 is configured to be provided with the gap adjusting portion 6c for adjusting the gap between the straightening vanes 6a2 of the straightening vane portion 6a, but the present disclosure is not limited thereto . It is also possible not to provide the gap adjustment part 6c. Further, the number of installed straightening vanes 6a2 of the straightening vane portion 6a and the width of the gap between the straightening vanes 6a2 can be changed according to the characteristics of the pulverized coal burner 1, the amount of combustion, and the like.

Moreover, in the said embodiment, although the support part 6b was joined to the baffle plate 6a2, and was made into the taper shape which protrudes toward the upstream side, this indication is not limited to this. The support portion 6 b may be inclined radially inward and downstream in the flow direction of pulverized coal so as to guide the pulverized coal radially inward of the burner nozzle 4.

The straightening vane 6a2 may have a configuration in which the straightening vane 6a2 is directly joined to the burner nozzle 4 without the frame 6a1. Furthermore, the installation position of the straightening vane 6a2 is not limited to the above embodiment, and the burner nozzle 4 may be installed more upstream than the above embodiment.

The straightening vane 6a2 and the support portion 6b can also be integrally formed as a casting.

According to the present disclosure, the amount of nitrogen oxide emissions can be reduced by supplying the powdered fuel to the reduction region.

1 Pulverized coal burner (powder fuel burner)
2 Pulverized coal supply piping (powder fuel supply piping)
Reference Signs List 3 oil gun 4 burner nozzle 5 air supply portion 5a wind box 5b outer throat 5c inner throat 5d main air adjustment mechanism 5e auxiliary air adjustment mechanism 6 pulverized coal guide portion (powder fuel guide portion)
6a Flow straightening plate portion 6a1 Frame portion 6a2 Flow straightening plate 6b Support portion 6c Gap adjustment portion 6c1 Movable flow straightening plate portion 6c2 Projection portion 6c3 Frame portion 6c4 Plate portion 6c5 Groove portion 100 Fire wall 110 Fire wall opening

Claims

A nozzle unit that discharges air and powdered fuel along a nozzle axis;
Powder fuel that is erected radially inward of the nozzle portion from an inner peripheral surface of the nozzle portion, and guides at least a portion of the powder fuel flowing inside the nozzle portion in the radial direction A guidance unit,
Powder fuel burner comprising.
The powder fuel guide portion has straightening vanes erected inward in the radial direction from the opening end of the nozzle portion and provided with a plurality of flow guide plates spaced apart in the circumferential direction of the nozzle portion. Powder fuel burner.
The powder fuel burner according to claim 2, wherein the powder fuel guide portion is provided on an inner peripheral surface of the nozzle portion, and has a support portion protruding in the flow direction of the powder fuel and supporting the straightening vane. .
The powder fuel burner according to claim 2 or 3, further comprising a gap adjusting unit configured to adjust a width of a gap between the straightening vanes.
The powder fuel burner according to any one of claims 1 to 4, wherein the powder fuel is pulverized coal.