JP6837759B2 - Fluidized bed boiler - Google Patents

Description

The present disclosure relates to a fluidized bed boiler, and more particularly to an improvement of a fuel supply device for supplying fuel to a combustion chamber by a fuel chute method.

In recent years, a fluidized bed boiler that uses recycled fuel and has excellent environmental compatibility has been widely used as an alternative to fossil fuel. For example, in a bubble-type fluidized bed boiler, a fluidized bed (fluidized bed) is formed by blowing a fluidized material (glass sand) filled in the bottom of a combustion chamber into a fluidized state by blowing a high-pressure fluidized gas from below. The fuel charged into the fluidized bed is instantly dried and incinerated. Recycled fuels include woody biomass such as wood chips, waste tires, sludge, and RPF (Refuse Paper and Plastic Fuel). Compared to fossil fuels, they have a relatively large amount of water, and their shape, size, and weight. There is also a difference such as irregularity.

By the way, fuel is supplied to the combustion chamber of the fluidized bed boiler by various methods such as a fuel chute method and a spreader method. In any of these fuel supply methods, fuel is supplied to the entire fluidized bed formed in the combustion chamber. Has been devised to supply the fuel uniformly (Patent Document 1). This is because the variation in the fuel input amount in the entire fluidized bed directly leads to the fluctuation in the temperature of the combustion gas and the variation in the oxygen (O ₂ ) concentration in the combustion gas, and generates harmful gases such as dioxins and NOx. This is because it causes it. In particular, when the O ₂ concentration decreases, a large amount of carbon monoxide (CO) is generated, which also causes the generation of dioxins having a high correlation with the CO concentration. Specifically, in the fuel chute method, fuel is supplied from a plurality of locations on the wall surface of the combustion chamber by a distributor. For example, in Patent Document 1, a dispersion plate is provided near the fuel supply port of a transport pipe that conveys fuel toward the fuel supply port of the combustion chamber, and a large number of branch channels are formed by a large number of partition walls formed on the dispersion plate. The fuel is configured to be evenly distributed. Further, in the spreader method, the fuel arrival position (flying distance) in the fluidized bed is changed by a rotary blade (rotor) to uniformly supply the fuel to the entire fluidized bed. In addition, as in Patent Document 2, the tip of the fuel supply pipe that faces the combustion chamber from above the fluidized bed and supplies fuel may be configured to swing in a desired direction at regular intervals. ..

Further, the fuel of Patent Document 1 is coal, but there are, for example, Patent Documents 3 to 4 as a fluidized bed boiler using recycled fuel. In Patent Document 3, in order to enable dispersed supply of highly water-containing residues such as sludge to the fluidized bed, which is difficult to supply evenly with a conventional spreader rotor, a blade having the same uneven shape is provided on the outer periphery of the spreader rotor. It is disclosed that a plurality of rotors are provided at a predetermined pitch in the circumferential direction of the rotor. In Patent Document 4, a structure provided so as to project from the fuel supply port on the wall surface of the combustion chamber toward the fluidized bed allows fuel having a low density such as wood chips and waste plastic to be blown out from the fluidized bed upward. It is disclosed that it prevents the fluid from being wound up by air and ensures that the fluid and fuel are mixed.

Japanese Unexamined Patent Publication No. 59-173626 Jikkai Sho 59-139743 Japanese Unexamined Patent Publication No. 02-21369 Japanese Unexamined Patent Publication No. 2004-85064

As mentioned above, there are various fuel supply methods to the fluidized bed. For example, the spreader method is suitable for coal fuel, but when recycled fuel is used, it has a large amount of water and irregular size. There is concern about fuel clogging caused by this. On the other hand, the fuel chute method is most suitable in terms of adaptation to such various fuels and simplification of equipment, but because it is a supply method by gravity drop, it covers the entire fluidized bed compared to the spreader method. On the other hand, it is difficult to supply fuel uniformly.
In order to solve this problem, a method of providing a dispersion plate having a branch flow path in the fuel chute as in Patent Document 1 can be considered, but it is caused by the above-mentioned properties of the recycled fuel as in the spreader method. Therefore, there is a concern that the fuel may be clogged in the branch channel. Further, when the number of fuel chute paths is increased, it becomes possible to uniformly supply fuel to the entire fluidized bed, while fuel supply and transportation equipment such as a fuel chute path and a conveyor connected to each fuel chute path, respectively. It is desirable that the number of fuel chute paths be as small as possible because the equipment cost of the fuel will increase significantly.

In view of the above circumstances, at least one embodiment of the present invention provides a fluidized bed boiler capable of more uniformly supplying fuel to the entire fluidized bed and reducing costs such as manufacturing and operation in the fuel chute method. The purpose is to provide.

(1) The fluidized bed boiler according to at least one embodiment of the present invention is
A combustion chamber that forms a fluidized bed inside by supplying fluidized gas,
A fuel supply port provided on the wall surface of the combustion chamber and
A fuel chute that is connected to the fuel supply port and for supplying fuel to the inside of the combustion chamber through the fuel supply port, and the slope of the bottom surface of the fuel chute path is connected to the fuel supply port. A fuel chute path that faces the combustion chamber horizontally or downwards with respect to the horizontal.
It is provided below the fuel supply port on the wall surface of the combustion chamber, and includes an indoor injection unit that injects a transport gas horizontally or upward with respect to the combustion chamber.

According to the configuration of (1) above, below the fuel supply port on the wall surface of the fluidized floor boiler, an indoor injection section for injecting the transport gas toward the combustion chamber is provided, and is provided through the fuel chute path. The fuel supplied from the fuel supply port to the combustion chamber falls onto the transport gas injected from the indoor injection unit. At this time, in order to transport the fuel toward a distance, the transport gas is injected horizontally or above the horizontal, not downward, which supports the fall of the fuel. For this reason, fuel with irregular weight and size (recycled fuel) is carried to the transport gas injected from the indoor injection section by the flight distance according to the size and weight of the fuel, and falls into the fluidized bed. To do. As a result, the fuel can be supplied more uniformly over the entire fluidized bed. As a result, more uniform combustion of fuel in the fluidized bed can be realized, and the generation of NOx and CO can be suppressed. Further, in the case of uniformly supplying fuel to the entire fluidized bed, for example, it is cheaper to install the indoor injection section than to install a plurality of fuel chute paths on the wall surface of the combustion chamber, and the fuel chute paths and each of them are installed. Since the scale of fuel supply and transportation equipment such as a conveyor connected to the fuel chute and a distribution unit for distributing fuel to the fuel chute can be reduced, the cost required for manufacturing and operation (maintenance) of a fluidized bed boiler can be reduced. Can also be significantly reduced.

(2) In some embodiments, in the configuration of (1) above,
The transport gas is steam generated in the fluidized bed boiler.
According to the configuration of (2) above, the steam (self-steam) of the fluidized bed boiler does not contribute to the combustion reaction in the combustion chamber, so that it does not burn and disappear during the transportation of fuel. Therefore, the fuel can be dispersed and supplied over the entire fluidized bed more reliably than injecting air from the indoor injection unit.

(3) In some embodiments, in the above configurations (1) and (2),
The indoor injection unit includes a plurality of injection ports arranged horizontally adjacent to each other on the wall surface.
According to the configuration of (3) above, on the wall surface of the combustion chamber, a plurality of injection ports are arranged horizontally adjacent to each other below the fuel supply port. As a result, it is possible to form a state in which the transport gas having the momentum of injection exists in a wider range below the fuel supply port, so that the fuel that jumps out from the fuel supply port can be more reliably transferred to the transport gas. It can be dropped and transported.

(4) In some embodiments, in the configuration of (1) or (2) above,
The indoor injection unit
An upper injection port group consisting of a plurality of injection ports arranged horizontally adjacent to each other on the wall surface, and
It is composed of a lower injection port group consisting of a plurality of injection ports arranged horizontally adjacent to each other below the upper injection port group.
Each of the injection ports constituting the upper injection port group is configured to inject the transport gas at the first injection speed.
Each of the injection ports constituting the lower injection port group is configured to inject the transport gas at a second injection speed, which is an injection speed force higher than the first injection speed.
According to the configuration (4) above, the injection speed (second injection speed) of the transport gas from each injection port constituting the lower injection port group is from each injection port constituting the upper injection port group. It is stronger than the injection speed of the transport gas (first injection speed). In this way, by increasing the injection speed of the lower stage than the upper stage in the vertical direction, the fuel can be dispersed and supplied over the entire fluidized bed by the indoor injection unit.

(5) In some embodiments, in the configurations (3) to (4) above,
Each of the plurality of injection ports is configured such that the ejection ranges of the transport gas injected from the injection ports adjacent to each other have overlaps with each other on the horizontal plane.
According to the configuration of (5) above, the gap generated between the transport gases ejected from each of the plurality of injection ports can be reduced, and the state in which the transport gas exists can be formed in a wider range. The fuel that jumps out from the fuel supply port can be reliably dropped onto the transport gas and transported.

(6) In some embodiments, in the configurations (3) to (5) above,
Further provided is an injection speed control device for periodically changing the injection force of the transport gas from each of the plurality of injection ports.
According to the configuration of (6) above, when the injection force is large, the fuel can be conveyed farther than when the injection force is small, and the fuel is accompanied by such a periodic change in the injection force. The flight distance of fuel from the supply port can be changed. This allows the fuel to be better dispersed and supplied throughout the fluidized bed.

(7) In some embodiments, in the configurations (1) to (6) above,
An in-passage injection port for injecting a mixing gas is formed on the bottom surface of the fuel chute path in a direction orthogonal to the bottom surface of the fuel chute path or in a direction lower than the direction orthogonal to the bottom surface.
According to the configuration of (7) above, the massive fuel can be destroyed by the mixing gas injected from the injection port in the path, and the fuel can be dispersed (dispersed) inside (space) of the fuel chute. .. The fuel in which the lump state is eliminated and scattered inside the fuel chute can be easily transported by the transport gas, so that the fuel can be better dispersed and supplied over the entire fluidized bed.

(8) In some embodiments, in the configurations (1) to (7) above,
A protrusion is formed on the bottom surface of the fuel chute path.
According to the configuration of (8) above, when the fuel chute is dropped, the mass fuel can be broken by the momentum caused by passing through the protrusion, and the fuel is dispersed inside (space) of the fuel chute (space). Can be dispersed). The fuel in which the lump state is eliminated and scattered inside the fuel chute can be easily transported by the transport gas, so that the fuel can be better dispersed and supplied over the entire fluidized bed.

(9) In some embodiments, in the configurations (1) to (8) above,
On the bottom surface of the fuel chute path, a drop direction convex portion extending over a predetermined range along the fall direction of the fuel is formed.
The convex portion in the falling direction inclines downward from the top toward both sides in the cross-sectional shape.
According to the configuration of (9) above, the convex portion in the falling direction has a top portion and an inclined portion that is inclined downward from the top portion toward both sides. The fuel traveling straight on the fuel chute path passes through the inclined portion of the convex portion in the falling direction, and receives a force in the left-right direction with respect to the falling direction due to the inclination of the inclined portion. As a result, when the fuel jumps out from the fuel supply port into the combustion chamber, the fuel can be dispersed so as to spread to the left and right, and the fuel can be better dispersed and supplied over the entire fluidized bed. Further, the number of fuel chute paths can be reduced by ejecting the fuel from the fuel supply port so as to spread to the left and right.

(10) In some embodiments, in the configuration of (9) above,
The drop direction convex portion is configured such that the height of the top portion gradually increases toward the lower side in the fall direction of the fuel over the predetermined range.
According to the configuration of (10) above, the convex portion in the falling direction is the bottom surface of the fuel chute path so as not to cause a step at the connection point between the upstream end of the fuel chute path and the bottom surface of the fuel chute path. It can be smoothly connected to the fuel chute and can prevent the fuel chute from being clogged with fuel.

According to at least one embodiment of the present invention, in the fuel chute method, a fluidized bed boiler capable of more uniformly supplying fuel to the entire fluidized bed and reducing costs such as manufacturing and operation is provided.

FIG. 5 is a schematic cross-sectional view of the combustion chamber of the fluidized bed boiler according to the embodiment of the present invention as viewed from the side with respect to the wall surface provided with the fuel supply port. It is a figure which shows. It is a schematic cross-sectional view which looked at the combustion chamber of the fluidized bed boiler which concerns on one Embodiment of this invention from the side with respect to the wall surface provided with the fuel supply port, and is the figure which shows the Embodiment using steam as a transport gas. Is. It is a schematic view which shows a part of the wall surface of the combustion chamber provided with the fuel supply port which concerns on one Embodiment of this invention, is the figure which was seen from the direction A of FIGS. It is composed of an injection port. It is a schematic view which shows a part of the wall surface of the combustion chamber provided with the fuel supply port which concerns on one Embodiment of this invention, is the figure which is seen from the direction A of FIGS. It is composed of an injection port. It is a schematic view of the cross section (BB cross section) which cut the combustion chamber which concerns on one Embodiment of this invention in a horizontal plane passing through an indoor ejection part, and looked at the lower part of an arbitrary fuel chute path from the B direction of FIGS. 1A-1B. It is a figure. It is a schematic diagram which shows a part of the wall surface of the combustion chamber provided with the fuel supply port which concerns on one Embodiment of this invention, and shows a plurality of injection ports including the upper stage injection port group and the lower stage injection port group. It is a schematic diagram which shows a part of the wall surface of the combustion chamber provided with the fuel supply port which concerns on one Embodiment of this invention, and the upper stage injection port group and the lower stage injection port group each consist of one injection port. It is a schematic diagram which shows the cross section of a part of the fuel chute passage connected to the combustion chamber which concerns on one Embodiment of this invention, and is the figure which enlarged the vicinity of the connection part. It is a schematic diagram which looked at a part of the bottom surface of the fuel chute path connected to the combustion chamber which concerns on one Embodiment of this invention from above. It is a figure for demonstrating the protrusion formed in the fuel chute path which concerns on one Embodiment of this invention, and is the schematic view which looked at the cross section of a part of the fuel chute path from the front of the combustion chamber. It is a figure for demonstrating the protrusion formed in the fuel chute path which concerns on one Embodiment of this invention, and is the schematic view which looked at the cross section of a part of the fuel chute path from the front of the combustion chamber. It is a schematic view for demonstrating the drop direction convex part provided in the fuel chute path which concerns on one Embodiment of this invention, and becomes (a) front view, (b) side view, (c) bottom plan view. ..

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention to this, but are merely explanatory examples. Absent.
For example, expressions that represent relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" are exact. Not only does it represent such an arrangement, but it also represents a state of relative displacement with tolerances or angles and distances to the extent that the same function can be obtained.
For example, expressions such as "same", "equal", and "homogeneous" that indicate that things are in the same state not only represent exactly the same state, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the state of existence.
For example, an expression representing a shape such as a quadrangular shape or a cylindrical shape not only represents a shape such as a quadrangular shape or a cylindrical shape in a geometrically strict sense, but also an uneven portion or chamfering within a range in which the same effect can be obtained. The shape including the part and the like shall also be represented.
On the other hand, the expressions "equipped", "equipped", "equipped", "included", or "have" one component are not exclusive expressions that exclude the existence of other components.

FIG. 1A is a schematic cross-sectional view of the combustion chamber 2 of the fluidized bed boiler 1 according to the embodiment of the present invention as viewed from the side with respect to the wall surface 21 provided with the fuel supply port 3, and is a transfer gas G1. It is a figure which shows the embodiment using a fluidized gas Ga. FIG. 1B is a schematic cross-sectional view of the combustion chamber 2 of the fluidized bed boiler 1 according to the embodiment of the present invention as viewed from the side with respect to the wall surface 21 provided with the fuel supply port 3, and is a transfer gas G1. It is a figure which shows the embodiment using steam. 2A to 2B are schematic views showing a part of the wall surface 21 of the combustion chamber 2 provided with the fuel supply port 3, and correspond to the views seen from the direction A of FIGS. 1A to 1B. Further, FIG. 3 is a schematic view of a cross section (BB cross section) of the combustion chamber 2 according to the embodiment of the present invention cut in a horizontal plane passing through the indoor injection section 5, and is a view below an arbitrary fuel chute path 4. Corresponds to the view from the B direction of FIGS. 1A to 1B. The fluidized bed boiler 1 of FIGS. 1A to 3 is a bubble type fluidized bed boiler.

As shown in FIGS. 1A to 3, the fluidized bed boiler 1 includes a combustion chamber 2, a fuel supply port 3, a fuel chute path 4, and an indoor injection section 5. As will be described later, the fuel supply to the fluidized bed boiler 1 is performed by the fuel chute method, and the fuel F is supplied from the fuel supply port 3 to the combustion chamber 2 through the fuel chute path 4. Further, in the fluidized bed boiler 1, the fuel F is burned at a low air ratio in the fluidized bed L formed by the primary air (fluidized gas Ga) in order to suppress the generation of harmful gases such as NOx, CO and dioxin. At the same time, the exhaust gas generated by the combustion in the fluidized bed L is burned at a high air ratio by the secondary air Gb supplied from above the fluidized bed L to the combustion chamber 2. The high-temperature exhaust gas discharged from the combustion chamber 2 is heat-exchanged by a heat transfer tube group 12 such as a superheater or an economizer arranged after the combustion chamber 2, and the heat energy recovered from the heat exchange is generated. It is used for such purposes. The superheater may be installed in the fluidized bed L, and the superheater exchanges heat with heat generated by combustion in the fluidized bed L. Then, the heat energy recovered from the heat exchange is used for power generation and the like. For example, the steam generated by the superheater is sent to a turbine (not shown) or the like.
Hereinafter, each of the above-described configurations included in the fluidized bed boiler 1 will be described. In the drawing, the lower part of the vertical direction V coincides with the direction of gravity, and the horizontal direction H is the direction of the horizontal plane orthogonal to the vertical direction V.

The combustion chamber 2 forms a fluidized bed L inside by being supplied with the fluidized gas Ga. As illustrated in FIGS. 1A to 1B, the combustion chamber 2 is installed so as to be upright, and contains a predetermined amount of a fluid material (inert particles such as silica sand or a desulfurizing agent such as limestone). Further, an air nozzle (not shown) for supplying fluidized gas Ga (primary air) is provided at the bottom 22 of the combustion chamber 2. Then, by supplying the fluidized gas Ga from the bottom 22 of the combustion chamber 2 so as to blow up into the inside of the combustion chamber 2, the fluidized material floats to a predetermined height and forms a fluidized bed L (fluid bed) while moving violently. To do. The supplied fluidized gas Ga may be blown up through an air chamber (not shown) or a perforated plate provided on the bottom portion 22.

In the embodiment shown in FIGS. 1A to 3, in the combustion chamber 2, the fluidized bed L is brought into a reduced state (a state of low oxygen) and a temperature of 800 ° C. to 850 ° C. (° C.) by the fluidized gas Ga. By keeping it, the generation of NOx is suppressed, and by supplying the secondary air Gb from above the fluidized bed L, CO is removed by the temperature range of 800 degrees or more formed above the fluidized bed L, and the generation of harmful substances is generated. Is suppressed. Further, the fluidized gas Ga is supplied to the combustion chamber 2 via the primary air supply pipe 13. The secondary air Gb is supplied to the secondary air introduction nozzle 15 provided on the wall surface 21 of the combustion chamber 2 by the secondary air supply pipe 14 branched from the primary air supply pipe 13, and the secondary air introduction nozzle 15 Is supplied to the inside of the combustion chamber 2. Although one secondary air introduction nozzle 15 is shown in FIGS. 1A to 1B, a plurality of secondary air introduction nozzles 15 are provided on the wall surface (wall surface 21, facing wall surface 23, etc.) of the combustion chamber. Then, the secondary air Gb may be supplied as overfire air (OFA) or additional air (AA).

The fuel supply port 3 is provided on the wall surface 21 of the combustion chamber 2. In other words, the fuel supply port 3 is an opening formed in the wall surface 21 so as to communicate the inside and the outside of the combustion chamber 2. The fuel supply port 3 is provided above the upper surface of the fluidized bed L formed inside the combustion chamber 2 by about 1 to 2 m or the like, and the fuel F is supplied from the fuel supply port 3 to the inside of the combustion chamber 2. Will be done. The fuel F of the fluidized bed boiler 1 is composed of woody biomass such as wood chips, waste tires, sludge, RPF (Refuse Paper and Plastic Fuel), and the like (recycled fuel). The fuel F supplied from the fuel supply port 3 to the combustion chamber 2 violently collides with the fluidized material in the fluidized bed L and burns effectively. In the embodiment shown in FIGS. 1A to 3, the fuel supply port 3 has an elliptical shape for connecting the cylindrical fuel chute path 4 as described later, and the long axis of the ellipse is in the vertical direction V. It is provided on the wall surface 21 of the combustion chamber 2 along the same line (see FIGS. 2A to 2B).

The fuel chute 4 is a passage connected to the fuel supply port 3 and for supplying the fuel F to the inside of the combustion chamber 2 through the fuel supply port 3. As shown in FIGS. 1A to 3, the fuel chute 4 has a cavity inside to form a passage for fuel F. Further, as shown in FIGS. 1A to 3, the gradient of the bottom surface 41 of the fuel chute 4 is horizontal or downward with respect to the combustion chamber 2 at the connection portion 31 with the fuel supply port 3. .. More specifically, the fuel chute 4 extends linearly upward from a connecting portion (connecting portion 31) connected to the edge of the fuel supply port 3 at a predetermined installation angle θs with respect to the horizontal direction H. , Is connected to the wall surface 21 of the combustion chamber 2. As a result, the fuel chute 4 has a gradient with respect to the horizontal direction H, and the gradient of the bottom surface 41 of the fuel chute 4 is directed toward the combustion chamber 2 at the connection portion 31 with the fuel supply port 3. It is designed to face downward with respect to the horizontal. In other words, in the side view as shown in FIGS. 1A to 1B, when the extension line 41e along the bottom surface 41 of the fuel chute 4 is drawn toward the inside of the combustion chamber 2, the extension line 41e is in the horizontal direction. It faces downward with respect to H. In this way, the fuel chute 4 is installed on the wall surface 21 of the combustion chamber 2 at an oblique angle, so that the fuel F charged from the inlet on the upstream side of the fuel chute 4 (not shown) is shown in FIGS. 1A to 1A. As shown by the arrow (falling direction Fd) in FIG. 1B, the fuel falls by gravity so as to slide down the inside of the fuel chute 4, and is supplied to the inside of the combustion chamber 2 from the fuel supply port 3 on the downstream side. The installation angle θs of the fuel chute 4 is an angle at which the fuel F falls on the fuel chute 4 without being clogged in consideration of the properties and shape of the fuel F. In the embodiment shown in FIGS. 1A to 3, the fuel chute 4 has a cylindrical shape, the cross section of the bottom surface 41 of the fuel chute 4 has an arc shape, and the extension line 41e is , The fuel chute 4 is pulled along the lower end 41b (the lowermost end of the vertical direction V) of the bottom surface 41 having an arcuate cross section. Further, one end of the fuel chute 4 is processed into an elliptical shape because it has a shape cut diagonally at the installation angle θs in order to connect with the fuel supply port 3 at the installation angle θs.

The indoor injection unit 5 is provided above the fluidized bed L and below the fuel supply port 3 on the wall surface 21 of the combustion chamber 2, and is horizontally or horizontally toward the combustion chamber 2 and upward with respect to the transport gas G1. Is injected. In other words, the indoor injection unit 5 is an opening formed in the wall surface 21 so as to communicate the inside and the outside of the combustion chamber 2, and falls from the fuel supply port 3 into the combustion chamber 2 so as to pop out. In order to transport the coming fuel F to a position farther away from the fuel supply port 3 (to fly farther), the transport gas G1 is injected. Further, by directing the injection direction of the transport gas G1 horizontally or upward with respect to the horizontal, the fuel F can be transported farther without the transport gas G1 pushing the fall of the fuel F. It is possible. More specifically, as shown in FIGS. 1A to 1B, the fuel F gravitationally falls toward the fluidized bed L in the direction of falling down the fuel chute 4 and protruding from the fuel supply port 3. At this time, since the transport gas G1 is injected above the fluidized bed L, the transport gas G1 injected from the indoor injection unit 5 is ejected before reaching the fluidized bed L (described later). To reach. As a result, the fuel F is blown along the injection direction of the transport gas G1 further away from the drop point of the fluidized bed L when there is no transport gas G1, and the fuel F falls in the fluidized bed L. The point will be changed by the transport gas G1.

In the embodiment shown in FIGS. 1A to 3, the injection direction and injection force are adjusted so that the fuel F can be blown to the vicinity of the facing wall surface 23 of the wall surface 21 provided with the fuel supply port 3. There is. This eliminates the need to provide the fuel chute 4 on the facing wall surface 23. Therefore, the fuel chute path 4 is not provided on the facing wall surface 23 (see FIGS. 1A to 1B). Further, the transport gas G1 is prepared by connecting the primary air supply pipe 13 for supplying the fluidized gas Ga to the combustion chamber 2 and the indoor injection unit 5 via the gas transport pipe 52 (). See FIG. 1A).

Further, in the embodiment shown in FIGS. 1A to 3, as shown in FIGS. 2A and 3, the indoor injection unit 5 is composed of a plurality of injection ports 5a. Further, as shown in FIG. 2A, a plurality of injection ports 5a are arranged on the wall surface 21 of the combustion chamber 2 adjacent to the horizontal direction H (three in the examples of FIGS. 2A and 3). More specifically, in the example of FIG. 3, the plurality of injection ports 5a are provided within the range from the end of the short axis of the elliptical fuel supply port 3 to the lower end, and below the fuel supply port 3. The entire area is covered by the ejection range R of the transport gas G1. Further, a gas transport pipe 52 for supplying the transport gas G1 is connected to each injection port 5a. In the example of FIG. 3, the gas transport pipe 52, which was one halfway, is branched from the middle by the number of injection ports 5a provided in the combustion chamber 2 and is connected to all the injection ports 5a. The transport gas G1 is configured to flow through the gas transport pipe 52 to the injection port 5a and then to be ejected from each injection port 5a. By injecting the transport gas G1 from the plurality of injection ports 5a in this way, it is possible to form a state in which the transport gas G1 having the momentum of injection exists below the fuel chute 4 over a wide range. , The fuel F that jumps out from the fuel supply port 3 can be more reliably dropped onto the transport gas G1 and transported. The number of injection ports 5a may be 1 or more. For example, when the number of injection ports 5a is one, as shown in FIG. 2B, in the indoor injection unit 5, the ejection range R of the transport gas G1 from one injection port 5a is the fuel supply port 3. It may be provided so as to cover the entire area below the.

Further, in the embodiment shown in FIGS. 1A to 3, one or more injection ports 5a constituting the indoor injection unit 5 are each composed of outlets of nozzles (indoor injection nozzles 51), and the gas transfer pipe 52. It is configured to inject the transport gas G1 supplied from the chamber injection nozzle 51 into the combustion chamber 2. The injection direction, injection amount, and injection speed of the transport gas G1 are adjusted according to the shape of the indoor injection nozzle 51, the installation angle, and the like. In some other embodiments, the transport gas G1 may be horizontally injected from the injection port 5a without providing the indoor injection nozzle 51. The injection angle of the injection port 5a with respect to the horizontal direction H may be set to any angle in the range of 0 degrees to 45 degrees, and the above 45 degrees is theoretically the farthest flight in a simple model. It is a value exemplified as a possible angle. As a result, especially in a bubble-type fluidized bed boiler, by making the injection angle too large, a relatively small fuel among various large and small fuels supplied from the fuel supply port 3 is blown up by the transport gas G1. By preventing the occurrence of such a situation, it is possible to prevent a decrease in combustion efficiency.

Further, the injection amount and the injection speed of the transport gas G1 from the indoor injection unit 5 may be adjusted by another method regardless of the presence or absence of the indoor injection nozzle 51. For example, a damper 55 (valve) may be provided in the gas transport pipe 52 and adjusted according to the opening degree of the damper 55. The gas transfer pipe 52 may be provided with a blower (not shown) for blowing the transfer gas G1 toward the indoor injection unit 5, and the output of the blower may be adjusted. Alternatively, the fluidized bed boiler 1 may further include an injection control device 56 capable of controlling the injection of the transport gas G1 from the indoor injection unit 5 (each of the plurality of injection ports 5a) (see FIG. 3). For example, the injection control device 56 is connected to a device such as the damper 55 or a blower (not shown) that can adjust the injection amount and the injection speed from the indoor injection unit 5 (damper 55 in FIG. 3), and the damper 55 is connected. For example, the opening degree and the output of the blower (not shown) may be changed periodically. When the injection speed is high, the fuel can be transported farther than when the injection speed is low, and the flight distance of the fuel F from the fuel supply port 3 is changed according to the periodic change of the injection speed. be able to. Further, when the injection amount is large, a larger amount of fuel can be conveyed than when the injection amount is small, and the amount of fuel F conveyed from the fuel supply port 3 is increased as the injection amount changes periodically. Can be changed. Alternatively, by combining a plurality of these, the injection amount and the injection speed of the transport gas G1 of the indoor injection unit 5 may be adjusted.

Although one fuel chute path 4 is shown in FIGS. 1A to 3, the number of fuel chute paths 4 connected to the combustion chamber 2 may be 1 or more. When a plurality of fuel chute paths 4 are provided, a plurality of fuel supply ports 3 are provided on the wall surface 21 of the combustion chamber 2, and the fuel chute paths 4 are connected to each of the plurality of fuel supply ports 3. Further, the wall surface 21 on which the fuel supply port 3 and the fuel chute 4 are provided is not limited to one, and may be provided on two opposing surfaces, two adjacent surfaces, or all surfaces. good. The number that can be installed on one wall surface 21 of the fuel chute 4 also depends on the size of the combustion chamber 2. For example, in the embodiment shown in FIGS. 1A to 3, in the fluidized bed boiler 1, four fuel supply ports 3 are arranged on one wall surface 21 of the combustion chamber 2 at the same position in the vertical direction V, in the horizontal direction H, and the like. The fuel chute paths 4 are connected to the fuel supply ports 3 at intervals. Further, one or more indoor injection portions 5 are provided below each of the four fuel supply ports 3, whereby the fuel F can be dispersed and supplied over a wider area over the entire fluidized bed. It becomes.

According to the above configuration, below the fuel supply port 3 on the wall surface 21 of the fluidized bed boiler 1, an indoor injection section 5 for injecting the transport gas G1 toward the combustion chamber 2 is provided, and a fuel chute path is provided. The fuel F supplied from the fuel supply port 3 to the combustion chamber 2 via the 4 falls onto the transport gas G1 injected from the indoor injection unit 5. At this time, the transport gas G1 is injected horizontally or above the horizontal in order to transport the fuel F toward a distance, not downward so as to support the fall of the fuel F. Therefore, the fuel F (recycled fuel) having irregular weight and size is carried to the transport gas G1 injected from the indoor injection unit 5 by a flight distance according to the size and weight of the fuel F. It will fall into the fluidized bed L. In this way, the indoor injection unit 5 can disperse and supply the fuel F over a wider area over the entire fluidized bed, and can achieve a more uniform supply of the fuel to the entire fluidized bed. As a result, more uniform combustion of the fuel F in the fluidized bed L can be realized, and the generation of NOx and CO can be suppressed. Further, in the case of uniformly supplying fuel to the entire fluidized bed, for example, it is cheaper to install the indoor injection section 5 than to install a plurality of fuel chute paths 4 on the wall surface 21 of the combustion chamber 2, and the fuel Since the scale of the fuel supply / transport facility such as the conveyor connected to the chute path 4 and each fuel chute path 4 and the distribution unit for distributing the fuel F to the fuel chute path can be reduced, the fluidized bed boiler 1 is manufactured. It is also possible to significantly reduce the cost required for operation (maintenance).

Further, in the embodiments shown in FIGS. 1A to 3, as described above, the transport gas G1 is prepared by branching the gas transport pipe 52 from the primary air supply pipe 13 (see FIG. 1A). .. In some other embodiments, a portion of the secondary air Gb is used as the transport gas G1 by branching the gas transport pipe 52 from the secondary air supply pipe 14 branched from the gas transport pipe 52. Is also good. In this way, by using the fluidized gas Ga and the secondary air Gb as the transport gas G1, the transport gas G1 can be prepared relatively easily.

In some other embodiments, as shown in FIG. 1B, the transport gas G1 is the steam (self-steam) produced in the fluidized bed boiler 1. That is, steam is generated by exchanging heat with the superheater provided in the fluidized bed boiler 1 from the exhaust gas generated by the combustion of the fuel F in the combustion chamber 2. In this way, the steam generated by the fluidized bed boiler 1 is connected to the gas transfer pipe 52 by branching the pipe from the heat transfer tube group 12, so that the self-steam is used as the transfer gas G1. In the embodiment shown in FIG. 1B, the gas transfer pipe 52 is branched from the heat transfer pipe group 12 arranged in the subsequent stage of the combustion chamber 2. According to this configuration, since the steam of the fluidized bed boiler 1 does not contribute to the combustion reaction in the combustion chamber 2, it does not burn and disappear during the transportation of the fuel F. Therefore, the fuel F can be dispersed and supplied over the entire fluidized bed more reliably than injecting air from the indoor injection unit 5.

Further, in the embodiments shown in FIGS. 1A to 3, as shown in FIG. 2A, the plurality of injection ports 5a constituting the indoor injection unit 5 are arranged in a row in the horizontal direction H. In some other embodiments, as shown in FIGS. 4A-4B, the chamber injection portions 5 provided below the fuel supply port 3 on the wall surface 21 of the combustion chamber 2 are arranged in the horizontal direction H1. The above injection port 5a may be set as one stage, and may consist of a plurality of stages provided along the vertical direction V. 4A to 4B are schematic views showing a part of the wall surface 21 of the combustion chamber 2 provided with the fuel supply port 3 according to the embodiment of the present invention, respectively, and are the upper injection port group 54a and the lower injection port. The indoor injection unit 5 composed of the group 54b is shown. As shown in FIG. 4A, the indoor injection unit 5 includes an upper injection port group 54a composed of a plurality of injection ports 5a arranged on the wall surface 21 of the combustion chamber 2 adjacent to the horizontal direction H, and an upper injection port group 54a. It may be composed of a lower injection port group 54b including a plurality of injection ports 5a arranged on the wall surface 21 of the combustion chamber 2 adjacent to the horizontal direction H below the above. Alternatively, as shown in FIG. 4B, the indoor injection unit 5 may include one injection port 5a for each of the upper injection port group 54a and the lower injection port group 54b. Further, each of the one or more injection ports 5a constituting the upper injection port group 54a is configured to inject the transport gas G1 at the first injection speed, and one or more of the one or more injection ports constituting the lower injection port group 54b. Each of the injection ports 5a may be configured to inject the transport gas G1 at a second injection speed, which is a higher injection speed than the first injection speed.

In the embodiment shown in FIG. 4A, the upper injection port group 54a and the lower injection port group 54b are each composed of three injection ports 5a, and as a whole, a total of six injection ports 5a are the wall surfaces of the combustion chamber 2. 21 is provided. Further, in the upper injection port group 54a and the lower injection port group 54b, the injection ports 5a belonging to each group are arranged so as to be linearly arranged in the horizontal direction H at the same position in the vertical direction V. However, the arrangement of the upper injection port group 54a and the lower injection port group 54b is not limited to this embodiment. For example, the upper injection port group 54a and the lower injection port group 54b have injection ports 5a belonging to each group. , At the same position in the vertical direction V, they do not have to be arranged in a straight line in the horizontal direction H, and may be arranged so as to be shifted in the horizontal direction. Further, the indoor injection unit 5 may be composed of a plurality of stages of three or more.

According to the above configuration, the injection speed (second injection speed) of the transport gas G1 from each injection port 5a constituting the lower injection port group 54b is from each injection port 5a constituting the upper injection port group. It is faster than the injection speed of the transport gas (first injection speed). In this way, by increasing the injection force of the lower stage than the upper stage in the vertical direction, the fuel can be dispersed and supplied over the entire fluidized bed by the indoor injection unit 5. In some other embodiments, the first injection speed and the second injection speed may be the same, or the second injection speed may be slower than the first injection speed, and even in these cases. The transport gas G1 can disperse and supply the fuel F over the entire fluidized bed.

Further, in some embodiments, as shown in FIG. 3, each of the plurality of injection ports 5a constituting the indoor injection unit 5 described above is a transport gas G1 injected from the injection ports 5a adjacent to each other. The ejection ranges R are configured to overlap each other on the horizontal plane. Normally, when the transport gas G1 is injected from the injection port 5a in a predetermined injection direction, it advances in the injection direction while spreading up, down, left and right in the injection direction and losing momentum according to the distance from the injection port 5a. .. Here, the ejection range R indicates a range in which the momentum when ejected from the injection port 5a is not completely lost. In the embodiment shown in FIGS. 1A to 3, as shown in FIG. 3, three injection ports 5a are horizontally arranged on the wall surface 21 of the combustion chamber 2 by three indoor injection nozzles 51 (51a to 51c). It is provided so as to be arranged at equal intervals along H, and the ejection ranges R (Ra to Rc) of adjacent indoor injection nozzles 51 (51a to 51c) (adjacent injection ports 5a) overlap at least in a part. There is. Specifically, the ejection range Ra of the first chamber injection nozzle 51a is the ejection range of the adjacent second chamber injection nozzle 51b at the right end in the injection direction on the tip side away from the first chamber injection nozzle 51a (wall surface 21). It overlaps with the left end on the tip side of Rb, and an overlapping portion Po is formed. Further, the ejection range Rb of the second chamber injection nozzle 51b overlaps with the left end of the ejection range Rc of the adjacent third chamber injection nozzle 51c at the right end of the injection direction on the tip side of the second chamber injection nozzle 51b. The overlapping portion Po is formed.

On the contrary, a gap S is formed between the two adjacent indoor injection nozzles 51 (between 51a and 51b and between 51b and 51c) on the wall surface 21 side of the overlapping portion Po of the ejection range R. .. The gap S becomes narrower as the overlap between adjacent ejection ranges R increases. As the gap S becomes narrower, the proportion of the fuel F that falls into the gap S naturally decreases, and the proportion of the fuel F that falls into the fluidized bed L as it is without being sprayed with the transport gas G1 is reduced.

According to the above configuration, the gap S generated between the transport gas G1 ejected from each of the plurality of indoor injection nozzles 51 can be reduced, and the transport gas G1 can be discharged from the indoor injection unit 5 (injection port 5a). The fuel F ejected from the fuel supply port 3 can be more reliably dropped into the injection range R to be injected.

Next, some other embodiments relating to the fuel chute 4 in the above configuration will be described. FIG. 5 is a schematic view showing a partial cross section of the fuel chute path 4 connected to the combustion chamber 2 according to the embodiment of the present invention, and is an enlarged view of the vicinity of the connecting portion 31. FIG. 6 is a schematic view of a part of the bottom surface 41 of the fuel chute 4 connected to the combustion chamber 2 according to the embodiment of the present invention as viewed from above. 7A to 7B are schematic views for explaining the protrusions 7 formed in the fuel chute 4 according to the embodiment of the present invention, respectively, and a cross section of a part of the fuel chute 4 is shown in a combustion chamber. It is a figure seen from the front of 2. Further, FIG. 8 is a schematic view for explaining the falling direction convex portion 8 provided in the fuel chute 4 according to the embodiment of the present invention, in which (a) a front view, (b) a side view, and (1) c) It is a plan view of the bottom surface. Each of the embodiments described below is configured to disperse (disperse) the fuel F inside (space) of the fuel chute 4.

In some embodiments, as shown in FIG. 5, the bottom surface 41 of the fuel chute 4 has a mixing gas in a direction orthogonal to the bottom surface 41 of the fuel chute 4, or downward from the direction orthogonal to the bottom surface 41. An in-passage injection port 6 for injecting G2 is formed. The injection of the mixing gas G2 is sprayed onto the fuel F passing through the inside of the fuel chute 4 to break the mass of the fuel F before the fuel F reaches the fuel supply port 3 and break the mass of the fuel F into the inside of the fuel chute 4. The purpose is to disperse (disperse) the fuel F in the above. The fuel F is destroyed and dispersed by being blown by the mixing gas G2 and colliding with the impact or the wall of the fuel chute 4 or other fuel F in the vicinity. As the mixing gas G2, for example, a fluidized gas Ga, a secondary air Gb, a transport gas G1 or the like may be used, and the primary air supply pipe 13 for supplying the fluidized gas Ga or the transport gas G1 may be used. The mixing gas G2 may be supplied to the in-passage injection port 6 by branching the pipe 63 from at least one of the gas transport pipe 52 to be supplied and the secondary air supply pipe 14 to supply the secondary air Gb. ..

In the embodiment shown in FIG. 5, a nozzle (in-passage injection nozzle 61) is provided on the bottom surface 41 of the fuel chute path 4, and the mixing gas G2 is introduced from the in-passage injection nozzle 61 to the inside of the fuel chute path 4. It is configured to inject into. Further, as described above, the fuel chute path 4 is provided so as to be inclined diagonally upward with respect to the wall surface 21 of the combustion chamber 2 at a predetermined installation angle θs, but as shown in FIG. 5, the path is viewed from the side. The inner injection nozzle 61 is directed downward by a predetermined angle θ1 with respect to the direction of the normal line N (orthogonal direction) of the bottom surface 41 of the fuel chute path 4 or the normal line N. In this way, the injection angle from the in-passage injection port 6 cannot be directed upward with respect to the normal line N of the bottom surface 41 of the fuel chute path 4, so that the momentum of the fuel F falling down the fuel chute path 4 It is configured to achieve its purpose without diminishing.

Further, in the embodiment shown in FIG. 5, as shown in FIG. 5, a plurality of in-passage injection ports 6 (in-passage injection nozzle 61 in FIG. 5) are formed at the lower ends of the bottom surface 41 of the cylindrical fuel chute path 4. In 41b, they are arranged at intervals along the longitudinal direction of the fuel chute 4 (the falling direction Fd of the fuel F). Further, each of the plurality of in-passage injection ports 6 is configured to inject the mixing gas G2 at the same injection angle. However, the present invention is not limited to this embodiment, and in some other embodiments, the injection angles θ1 of each of the plurality of in-passage injection ports 6 do not have to be the same. The number of in-passage injection ports 6 may be 1 or more.

Further, as shown in FIGS. 6A to 6B, at least one of the plurality of in-passage injection ports 6 may be arranged in the lateral direction (passage width direction) of the fuel chute path 4. good. Specifically, in FIG. 6A, the two in-road injection ports 6 are arranged side by side in the width direction with the center of the passage (the lower end 41b when the cross section has an arc shape). In FIG. 6B, two pairs of in-road injection ports 6 arranged in the width direction across the center of the passage are arranged in the longitudinal direction of the fuel chute path 4, and the two pair of in-road injection ports are injected. One in-road injection port 6 is arranged between the ports 6. In this case, the amount of the mixing gas G2 to be sprayed can be different between the fuel F traveling in the center of the bottom surface 41 of the fuel chute 4 and the fuel F traveling in a position distant from the center in the width direction. Further, in FIG. 6 (c), the injection speed at the position in the width direction is adjusted as in FIG. 6 (b) by changing the shape of one in-passage injection port 6 in the width direction of the passage. In FIG. 6C, the in-passage injection port 6 has an opening that increases in the width direction from the center of the passage, and is configured to have the fastest injection speed at the center. It should be noted that, with the configurations shown in FIGS. 6A to 6C as a set, these sets are spaced at equal intervals along the longitudinal direction of the fuel chute 4 (the falling direction Fd of the fuel F). It may be provided open.

According to the above configuration, the mass of the fuel F can be broken by the mixing gas G2 injected from the in-passage injection port 6, and the fuel F is dispersed (dispersed) inside (space) of the fuel chute 4. Can be done. Further, the fuel F dispersed inside the fuel chute 4 is supplied from the fuel supply port 3 to the inside of the combustion chamber 2 and is transported by the transport gas G1 to transport the fuel F over the entire fluidized bed. Can be distributed and supplied.

In some other embodiments, a protrusion 7 is formed on the bottom surface 41 of the fuel chute 4, as shown in FIGS. 7A-7B. The protrusion 7 extends along a direction intersecting the falling direction Fd of the fuel F. In other words, the bottom surface 41 of the fuel chute 4 extends so as to cross the falling direction Fd. In the embodiment shown in FIGS. 7A to 7B, the fuel F drops the fuel chute 4 toward the fuel supply port 3 along the longitudinal direction of the cylindrical fuel chute 4 (the fall direction Fd of the fuel F). However, the bottom surface 41 of the fuel chute 4 is formed as a protruding portion 7 provided along the longitudinal direction. Therefore, when the fuel F passes through the protrusion 7 of the fuel chute 4, the fuel F may change its direction in various ways due to collision with the protrusion 7 and may fall while bouncing on the bottom surface 41 of the fuel chute 4. Will be higher. In the embodiment shown in FIG. 7A, the protrusion 7 is formed by a plurality of uneven mountain portions (convex portions) of the uneven undulations 7a. In the embodiment shown in FIG. 7B, the projecting portion 7 is formed by projecting a plurality of plate-shaped members 7b from the bottom surface 41 of the fuel chute 4 at intervals, and the plate-shaped members 7b are horizontal. It is formed on the bottom surface 41 of the fuel chute 4 so as to face downward with respect to the fuel chute. The undulations 7a and the plate-shaped member 7b constituting the protrusion 7 may be 1 or more, and the protrusion 7 may be provided on at least a part of the bottom surface 41 of the fuel chute 4. As a result, the mass of the fuel F can be broken, and the fuel F can be dispersed (dispersed) inside (space) of the fuel chute 4. Further, the fuel scattered in the fuel chute 4 is supplied from the fuel supply port 3 into the combustion chamber 2 and is conveyed by the transport gas G1 to disperse the fuel F over the entire fluidized bed. Can be supplied.

In some other embodiments, as shown in FIGS. 7A-7B, the in-passage injection port 6 and the protrusion 7 described above may be formed together with the bottom surface 41 of the fuel chute 4. In the embodiment shown in FIGS. 7A to 7B, the protrusion 7 is also provided at the position where the in-passage injection port 6 is provided on the bottom surface 41 of the fuel chute path 4. In FIG. 7A, the in-passage injection port 6 is provided in a part of a plurality of valley portions (concave portion) of the plurality of undulations 7a forming the protrusion 7, but is provided in all the valley portions. Each may be provided, or may be provided at least in a part of a plurality of mountain portions of the protrusion 7. In FIG. 7B, the in-passage injection port 6 is provided in a portion where the plate-shaped member 7b is not provided so as not to prevent the mixing gas G2 injected from the in-passage injection port 6 from breaking the mass of the fuel F. Is provided. Further, the in-passage injection port 6 may be provided at a portion of the bottom surface 41 of the fuel chute path 4 where the protrusion 7 is not provided. When provided at the same position, a plurality of in-passage injection ports 6 are provided at predetermined intervals along the longitudinal direction with respect to the protrusions 7 provided on the bottom surface 41 of the fuel chute 4 along the longitudinal direction. It may be provided.

In some other embodiments, as shown in FIG. 8, the bottom surface 41 of the fuel chute 4 has a drop direction protrusion 8 extending over a predetermined range Ps along the fall direction Fd of the fuel F. It is formed. As shown in FIG. 8A, the falling direction convex portion 8 has a top portion 81 located at the center of the fuel chute 4 and an inclined portion inclined downward from the top portion 81 toward both sides in the cross-sectional shape. 82 and. In the embodiment shown in FIG. 8, the convex portion 8 in the falling direction is formed by a plate-shaped dispersion plate, and as shown in FIG. 8A, the dispersion plate has a convex shape (dogleg shape) in the cross-sectional shape. Two plate-shaped members are fixed at an angle, or one plate-shaped member is bent so as to have a shape (shape). Further, the cross-sectional shape of the cylindrical fuel chute 4 is circular, and the top 81 of the convex dispersion plate is formed downward in the vertical direction from the center of the circle, and the inclined portion 82 is the top. The 81 and the bottom surface 41 of the fuel chute 4 are connected. In FIG. 8A, the falling direction convex portion 8 has a dogleg shape in the cross-sectional shape, but the present invention is not limited to this, and in other embodiments, the falling direction convex portion 8 is formed. The cross-sectional shape may be an arc shape, or may have a flat portion at the top 81. The falling direction convex portion 8 may be formed by processing the bottom surface 41 of the fuel chute 4 so as to crush it toward the inside of the passage.

Further, the drop direction convex portion 8 is provided from the connection portion 31 between the fuel chute path 4 and the fuel supply port 3 to a predetermined range Ps along the longitudinal direction of the fuel chute path 4 (FIGS. 8B). c) See). In the embodiment shown in FIG. 8, as shown in FIG. 8B, the fuel F falls downward in the falling direction Fd with reference to the bottom surface 41 of the fuel chute 4 over a predetermined range Ps. The height T of the convex portion 8 in the falling direction is gradually increased. In the embodiment shown in FIG. 8B, the drop direction convex portion 8 is located between the connecting portion 31 between the fuel supply port 3 and the fuel chute 4 and a position separated from the connecting portion 31 by a predetermined range Ps. It is provided in. Here, the height T of the convex portion 8 in the falling direction is at the lower end 41b of the bottom surface 41 of the fuel chute 4 from the lower end 41b to the top 81 with reference to the lower end 41b of the bottom surface 41 of the fuel chute path 4. The distance is along the normal direction. In other words, as shown in FIG. 8B, in the side view, the height T of the convex portion 8 in the falling direction is the fuel supply port from the most upstream connection position C with the bottom surface 41 of the fuel chute path 4. The height gradually increases toward 3 (connecting portion 31), and reaches the maximum at the end on the connecting portion 31 side. Similarly, the distance between the lower end 41b of the bottom surface 41 of the fuel chute 4 and the connection position C between the inclined portion 82 and the bottom surface 41 of the fuel chute 4 is also large. As a result, the drop direction convex portion 8 is designed so that there is no step generated at the end (the end on the upstream side of the fuel chute 4) separated from the fuel supply port 3 in the longitudinal direction of the fuel chute 4 by a predetermined range Ps. It is smoothly connected to the bottom surface 41 of the fuel chute 4 so as to be small, and the situation where the fuel F is clogged in the fuel chute 4 is prevented. More specifically, as shown in FIG. 8C, the connection position C between the arcuate bottom surface 41 of the fuel chute 4 and the inclined portion 82 becomes larger as the fuel chute 4 is directed toward the fuel supply port 3. , The top 81 is separated from the fuel chute 4 in the lateral direction (the direction intersecting the falling direction Fd of the fuel F).

Further, the surface (fuel passing surface) through which the fuel F of the inclined portion 82 of the convex portion 8 in the falling direction passes is formed on a flat surface or a curved surface. For example, the fuel F is formed on the fuel passing surface of the inclined portion 82. If a partition wall is provided along the longitudinal direction of the fuel chute path 4 in order to guide the fall of the fuel, fuel F such as recycled fuel having a relatively large amount of water and irregular shape, size, weight, etc. is placed between the partition walls. It may get clogged. In that respect, in the present embodiment, the fuel chute 4 is prevented from being clogged with the fuel F by not forming a partition wall or the like on the inclined portion 82 of the convex portion 8 in the falling direction.

According to the above configuration, the falling direction convex portion 8 has a top portion 81 and an inclined portion 82. Further, the fuel F that has traveled straight through the fuel chute 4 receives a force in the lateral direction that is left and right with respect to the falling direction Fd due to the inclination by passing through the inclined portion 82 of the falling direction convex portion 8. As a result, when the fuel F jumps out from the fuel supply port 3 into the combustion chamber 2, the fuel F can be dispersed so as to spread to the left and right, and the fuel F can be better dispersed and supplied over the entire fluidized bed. it can. Further, the number of fuel chute paths 4 can be further reduced by projecting the fuel F from the fuel supply port 3 so as to spread to the left and right.

The present invention is not limited to the above-described embodiment, and includes a modified form of the above-described embodiment and a combination of these embodiments as appropriate.
For example, although the bubble type fluidized bed boiler has been described as the fluidized bed boiler 1, the present invention is not limited to this, and can be applied to, for example, a circulating fluidized bed boiler.
Further, in the above description, the fuel chute 4 is described as having a cylindrical shape, but the present invention is not limited to this, and if it has a cavity inside, its cross section may be elliptical or polygonal. It may have a shape that has another shape.

1 Flow bed boiler 12 Heat transfer pipe group 13 Primary air supply pipe 14 Secondary air supply pipe 15 Secondary air introduction nozzle 2 Combustion chamber 21 Wall surface 22 Bottom 23 Opposing wall surface 3 Fuel supply port 31 Connection part 4 Fuel chute path 41 Fuel chute Bottom of the road 41b Lower end of the bottom of the fuel chute 41e Extension line 5 Indoor injection part 51 Indoor injection nozzle 51a First indoor injection nozzle 51b Second indoor injection nozzle 51c Third indoor injection nozzle 52 Gas transfer pipe 54a Upper injection port group 54b Lower injection port group 55 Damper 56 Injection control device 6 In-pass injection port 61 In-pass injection nozzle 63 Piping 7 Protruding part 8 Falling direction convex part 81 Top 82 Inclined part C Connection position between the bottom surface of the fuel chute and the inclined part F Fuel G1 Transport gas G2 Mixing gas Ga Fluidized gas (primary air)
Gb Secondary air L Fluidized bed N Normal Po Overlapping part Ps Predetermined range R Ejection range S Gap H Horizontal direction V Vertical direction Fd Fall direction θs Fuel chute installation angle θ1 Injection angle

Claims (10)

A combustion chamber that forms a fluidized bed inside by supplying fluidized gas,
A fuel supply port, which is an opening formed in the wall surface of the combustion chamber so as to communicate the inside and the outside of the combustion chamber,
One end is connected to the fuel supply port, and the fuel chute path for supplying fuel from the fuel supply port to the inside of the combustion chamber, and the slope of the bottom surface of the fuel chute path is connected to the fuel supply port. A fuel chute path that faces the combustion chamber horizontally or downwards with respect to the horizontal.
An indoor injection unit provided below the fuel supply port on the wall surface of the combustion chamber and injecting a transport gas horizontally or upward with respect to the combustion chamber is provided.
On the bottom surface of the fuel chute path, a drop direction convex portion extending over a predetermined range along the fall direction of the fuel is formed.
The fluidized bed boiler is characterized in that the convex portion in the falling direction is configured to incline downward from the top toward both sides in a cross-sectional shape. The fluidized bed boiler according to claim 1, wherein the transport gas is steam generated in the fluidized bed boiler. The fluidized bed boiler according to claim 1 or 2, wherein the indoor injection unit includes a plurality of injection ports arranged horizontally adjacent to each other on the wall surface. The indoor injection unit
An upper injection port group consisting of a plurality of injection ports arranged horizontally adjacent to each other on the wall surface, and
It is composed of a lower injection port group consisting of a plurality of injection ports arranged horizontally adjacent to each other below the upper injection port group.
Each of the injection ports constituting the upper injection port group is configured to inject the transport gas at the first injection speed.
Each of the injection ports constituting the lower injection port group is configured to inject the transport gas at a second injection speed which is a faster injection speed than the first injection speed. The fluidized bed boiler according to claim 1 or 2. Claim 3 or 4 is characterized in that each of the plurality of injection ports is configured such that the ejection ranges of the transport gas injected from the injection ports adjacent to each other have overlap with each other on a horizontal plane. The fluidized bed boiler described in. The fluidized bed according to any one of claims 3 to 5, further comprising an injection control device for periodically changing the injection speed of the transport gas from each of the plurality of injection ports. boiler. The bottom surface of the fuel chute path is characterized in that an in-passage injection port for injecting a mixing gas in a direction orthogonal to the bottom surface of the fuel chute path or in a direction lower than the direction orthogonal to the bottom surface is formed. The fluidized bed boiler according to any one of claims 1 to 6. The fluidized bed boiler according to any one of claims 1 to 7, wherein a protrusion is formed on the bottom surface of the fuel chute path. The claim is characterized in that the falling direction convex portion is configured such that the height of the falling direction convex portion gradually increases toward the lower side in the falling direction of the fuel with reference to the bottom surface of the fuel chute path. Item 2. The fluidized bed boiler according to any one of Items 1 to 8. A combustion chamber that forms a fluidized bed inside by supplying fluidized gas,
A fuel supply port provided on the wall surface of the combustion chamber and
A fuel chute that is connected to the fuel supply port and for supplying fuel to the inside of the combustion chamber through the fuel supply port, and the slope of the bottom surface of the fuel chute path is connected to the fuel supply port. A fuel chute path that faces the combustion chamber horizontally or downwards with respect to the horizontal.
An indoor injection unit provided below the fuel supply port on the wall surface of the combustion chamber and injecting a transport gas horizontally or upward with respect to the combustion chamber is provided.
On the bottom surface of the fuel chute path, a drop direction convex portion extending over a predetermined range along the fall direction of the fuel is formed.
The fluidized bed boiler is characterized in that the convex portion in the falling direction is configured to incline downward from the top toward both sides in a cross-sectional shape.

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