JP7353133B2 - fuel supply system - Google Patents

Description

The present invention relates to a fuel supply system for supplying granular fuel such as wood chips, and in particular to a technique for supplying fuel to a fluidized bed furnace such as an internal circulation fluidized bed boiler.

An internal circulation fluidized bed boiler (ICFB), which is an example of a circulating fluidized bed boiler, supplies fuel to a fluidized bed formed in a combustion furnace and combusts the fuel. It is a fluidized bed furnace that generates steam by boiling. The fuel used is primarily granular combustible materials such as wood chips.

The fuel is stored in a silo and fed to the combustion furnace of the internal circulation fluidized bed boiler by an input conveyor. The input conveyor has a hopper that receives the fuel sent from the silo, and is configured to input an appropriate amount of fuel depending on the heat load from the hopper to the combustion furnace. The fuel introduced into the combustion furnace is rapidly combusted while being fluidized by the fluidized bed. In such a combustion furnace, the input conveyor is required to supply fuel quantitatively depending on the heat load.

Japanese Unexamined Patent Publication No. 132230/1983

However, fuel consisting of particulate material such as wood chips may form bridges within the hopper. When a bridge is formed, the input conveyor cannot deliver fuel to the combustion furnace. One solution to avoid bridging is to reduce the amount of fuel stored in the hopper. However, if the amount of fuel stored in the hopper is small, the input conveyor cannot supply the required amount of fuel when required, and stable combustion in the combustion furnace cannot be achieved.

Therefore, it has been conventional practice to install a bridge breaker in the hopper to destroy the bridge (see, for example, Patent Document 1). However, bridge breakers not only require the use of utilities such as air and electricity, which is costly, but also have the problem that they cannot effectively eliminate bridges and cannot significantly increase the storage amount (storage level). there were.

Therefore, the present invention provides a fuel supply system that can quantitatively and stably supply fuel without forming a fuel bridge.

In one embodiment, there is provided a fuel supply system for supplying fuel to a fluidized bed furnace, the system comprising: a silo for storing fuel; an input conveyor for inputting fuel into the fluidized bed furnace; the silo and the input conveyor; a storage conveyor disposed between the storage conveyor, the input conveyor having an input hopper for receiving fuel conveyed from the silo via the storage conveyor, and the storage conveyor a storage hopper that temporarily stores fuel to be stored, and a drag chain conveyor that is connected to the storage hopper and transports the fuel in the storage hopper, and the drag chain conveyor is configured to move along the fuel transport direction. The storage hopper includes an endless drag chain inclined upward, the storage hopper having an end wall having an opening, the drag chain inclined upward toward the opening, and the end wall comprising: A fuel supply system is provided that is inclined upward from the opening in a direction opposite to the conveying direction with respect to the vertical direction .

In one aspect, the angle of inclination of the end wall with respect to the vertical direction is within a range of 5° to 20°.
In one embodiment, the angle of inclination of the drag chain with respect to the horizontal direction is within a range of 10° to 20°.

In one aspect, the input conveyor includes a screw feeder connected to the input hopper.
In one aspect, a first level detector that detects a fuel storage level in the storage hopper, a second level detector that detects a fuel storage level in the input hopper, and a sensor from the silo to the storage hopper. The operation control unit further includes a fuel transfer device that transfers fuel, and an operation control unit that controls operations of the fuel transfer device and the drag chain conveyor, and the operation control unit is configured to control the operation of the storage hopper detected by the first level detector. controlling the operation of the fuel transfer device such that the storage level in the input hopper is maintained at a predetermined first value, and the storage level in the input hopper as detected by the second level detector is The drag chain conveyor is configured to control operation of at least the drag chain conveyor so as to maintain the drag chain conveyor at a second value.

According to the invention, the storage conveyor is arranged between the silo and the input conveyor. Since the storage conveyor includes a storage hopper, a certain amount of fuel can be temporarily stored in the storage hopper. Therefore, the input hopper of the input conveyor only needs to store the amount of fuel required for quantitative supply, and the storage capacity (storage level) of the input hopper can be reduced. As a result, bridging of fuel within the charging hopper of the charging conveyor can be prevented, and the charging conveyor can quantitatively supply fuel to the fluidized bed furnace.

The fuel is forced against the end wall of the storage hopper, dragged entirely by the drag chain, and further moves upward along the end wall. Since the drag chain is inclined, a portion of the fuel that has moved upward along the end wall is discharged from the storage hopper through the opening, and the remaining fuel collapses to the rear of the storage hopper. In this way, since the fuel flows (swirls) within the storage hopper, it is possible to prevent the fuel from forming bridges. Therefore, the storage hopper can store a certain amount of fuel without forming a bridge. As a result, the storage conveyor can stably send fuel to the input conveyor.

1 is a schematic diagram showing an embodiment of a combustion system with a fuel supply system and an internal circulation fluidized bed boiler; FIG. FIG. 1 is a schematic diagram showing one embodiment of a storage conveyor. It is a top view showing a part of a drag chain. FIG. 7 is a schematic diagram showing another embodiment of the storage conveyor. FIG. 2 is a diagram illustrating an embodiment of an input conveyor. FIG. 3 is a schematic diagram showing another embodiment of the combustion system.

Embodiments of the present invention will be described below with reference to the drawings.
In the embodiments described below, an internal circulation fluidized bed boiler is employed as the fluidized bed furnace, but the present invention is not limited to the following embodiments, and may be applied to other types of fluidized bed furnaces such as external circulation fluidized bed boilers. can also be applied.

FIG. 1 is a schematic diagram showing one embodiment of a combustion system comprising a fuel supply system and an internal circulation fluidized bed boiler. As shown in FIG. 1, the combustion system includes an internal circulation fluidized bed boiler 1, which is an example of a fluidized bed furnace, and a fuel supply system 2 for supplying fuel to the internal circulation fluidized bed boiler 1.

The internal circulation fluidized bed boiler 1 includes a combustion furnace 3 having a floor plate 4 therein, and heat transfer tubes 5 extending inside the combustion furnace 3. The floor plate 4 is connected to an air supply line 7, and air is supplied to the floor plate 4 through the air supply line 7. The floor plate 4 has a plurality of air diffusers (not shown), and air is injected upward into the combustion furnace 3 from these air diffusers. A fluidized medium made of silica sand or the like is stored in the combustion furnace 3 in advance. The fluidized medium is fluidized by jets of air introduced from the air diffuser openings of the bed plate 4 to form a fluidized bed 10.

Fuel is supplied from the fuel supply system 2 into the combustion furnace 3 and burned in the fluidized bed 10. The heat exchanger tubes 5 are located on the sides of the fluidized bed 10. Water is supplied to the heat exchanger tubes 5. The water flowing through the heat exchanger tubes 5 is heated by the heat generated when the fuel is combusted, and becomes steam. Steam is sent from the heat transfer tube 5 to a steam turbine (not shown) or the like.

Next, one embodiment of the fuel supply system 2 will be described. As shown in FIG. 1, the fuel supply system 2 is arranged between a silo 15 for storing fuel, an input conveyor 20 for inputting fuel into the internal circulation fluidized bed boiler 1, and between the silo 15 and the input conveyor 20. A storage conveyor 30 is provided. The main raw material of the fuel is wood chips such as cut chips and crushed chips. Cutting chips are thin pieces of wood created by cutting wood, and crushed chips are elongated strips of wood chips created by crushing wood. Shredded waste tires or coal may be mixed with wood chips as a combustion aid.

The fuel is put into the silo 15 and stored therein. The fuel supply system 2 further includes a cutting device 16 connected to the lower part of the silo 15 and a replenishment conveyor 50 disposed between the storage conveyor 30 and the input conveyor 20. The cutting device 16 is comprised of a quantitative feeding device such as a screw feeder. The cutting device 16 is configured to cut (discharge) a requested amount of fuel from the silo 15 . The storage conveyor 30 is arranged below the silo 15 and the cutting device 16. One end of the replenishment conveyor 50 is located below the storage conveyor 30, and the other end of the replenishment conveyor 50 is located above the input conveyor 20. The replenishment conveyor 50 comprises an inclined flex belt conveyor or flow conveyor and is configured to convey fuel upwardly. However, the configuration of the replenishment conveyor 50 is not limited to this embodiment, and other types of conveyors may be provided.

The input conveyor 20 includes an input hopper 21 and a screw feeder 22 connected to the input hopper 21. The input conveyor 20 is a quantitative supply device for quantitatively inputting fuel into the internal circulation fluidized bed boiler 1 . The storage conveyor 30 includes a storage hopper 31 and a drag chain conveyor 32 connected to the storage hopper 31. The storage conveyor 30 is a temporary storage conveyor that has the function of temporarily storing the fuel transferred from the silo 15 and securing the fuel to be transferred to the input conveyor 20.

The fuel is put into the storage hopper 31 of the storage conveyor 30 by the cutting device 16 . In this embodiment, the cutting device 16 constitutes a fuel transfer device that transfers fuel from the silo 15 to the storage hopper 31 of the storage conveyor 30. Fuel is stored in the storage hopper 31. Drag chain conveyor 32 discharges fuel from storage hopper 31 and sends it to replenishment conveyor 50. In this embodiment, fuel falls from the drag chain conveyor 32 onto the replenishment conveyor 50. In order to prevent impact on the replenishment conveyor 50 due to falling fuel, a leveling conveyor 40 (screw feeder, paddle type crusher) or the like may be disposed between the drag chain conveyor 32 and the replenishment conveyor 50. In this case, fuel is sent from drag chain conveyor 32 to replenishment conveyor 50 via leveling conveyor 40.

The fuel is conveyed to the input conveyor 20 by the replenishment conveyor 50 and is input into the input hopper 21 of the input conveyor 20. The fuel is received by the charging hopper 21 and stored within the charging hopper 21 . The screw feeder 22 discharges fuel from the input hopper 21 and sends it to the combustion furnace 3 of the internal circulation fluidized bed boiler 1 . Generally, the screw feeder 22 has better quantitative performance than the drag chain conveyor 32, but it is more likely to form a fuel bridge in the charging hopper 21. From this point of view, in order to prevent fuel bridging within the input hopper 21, the storage capacity (storage level) of the input hopper 21 is set lower than the storage capacity (storage level) of the storage hopper 31.

According to this embodiment, the storage conveyor 30 is arranged between the silo 15 and the input conveyor 20. Since the storage conveyor 30 includes the storage hopper 31, a certain amount of fuel can be stored in the storage hopper 31. Therefore, the input hopper 21 of the input conveyor 20 only needs to store the amount of fuel required for quantitative supply, and the storage capacity of the input hopper 21 can be reduced (lower storage level). As a result, fuel bridging within the charging hopper 21 of the charging conveyor 20 can be prevented, and the charging conveyor 20 can quantitatively supply fuel to the internal circulation fluidized bed boiler 1.

The storage conveyor 30 includes a level detector 41 that detects the level of fuel stored in the storage hopper 31. The level detector 41 is fixed to the upper part of the storage hopper 31. In this embodiment, the level detector 41 includes an ultrasonic level sensor that can continuously detect (measure) the fuel storage level. The level detector 41 made of an ultrasonic level sensor can detect the level of fuel stored in the storage hopper 31 from above the fuel without contacting it. However, the level detector 41 is not limited to the ultrasonic level sensor, and may be composed of other types of level sensors as long as they can continuously and accurately detect the fuel storage level.

The fuel supply system 2 further includes an operation control section 60 connected to the cutting device 16 and the level detector 41. The operation control unit 60 is configured to control the operation of the cutting device 16 based on the fuel storage level in the storage hopper 31. More specifically, the operation control unit 60 controls the operation of the cutting device 16 so that the storage level in the storage hopper 31 detected by the level detector 41 is maintained at a predetermined first value. It is configured. The operation control section 60 is also connected to the drag chain conveyor 32, and the operation control section 60 is configured to control the operation of the drag chain conveyor 32.

The input conveyor 20 includes a level detector 42 that detects the level of fuel stored in the input hopper 21. The level detector 42 is fixed to the upper part of the input hopper 21. In this embodiment, the level detector 42, like the level detector 41, is configured of an ultrasonic level sensor that can continuously detect (measure) the fuel storage level. The level detector 42 consisting of an ultrasonic level sensor can detect the level of fuel stored in the input hopper 21 from above the fuel without contacting it. However, the level detector 42 is not limited to the ultrasonic level sensor, and may be constructed from other types of level sensors as long as they can continuously and accurately detect the fuel storage level.

The operation control unit 60 is connected to the drag chain conveyor 32 and the replenishment conveyor 50, and is configured to control the operation of the drag chain conveyor 32 and the replenishment conveyor 50 based on the fuel storage level in the input hopper 21. ing. More specifically, the operation control unit 60 controls the drag chain conveyor 32 and the supply conveyor 50 so that the storage level in the input hopper 21 detected by the level detector 42 is maintained at a predetermined second value. Configured to control operation.

Although the screw feeder 22 can supply fuel more quantitatively than the drag chain conveyor 32, it has the aspect that fuel bridging is more likely to occur. Therefore, in order to prevent fuel bridging within the charging hopper 21, the second value indicating the fuel storage level within the charging hopper 21 is changed from the second value indicating the fuel storage level within the storage hopper 31. Set to a value smaller than 1. If the fuel storage level is low, fuel bridges are less likely to form.

According to this embodiment, the storage conveyor 30 secures a certain amount of fuel in the storage hopper 31 even when the cutting (discharge) of fuel from the silo 15 is not stable, so that the fuel can be stably supplied to the conveyor 20. On the other hand, the input conveyor 20 with the screw feeder 22 can supply fuel quantitatively to the combustion furnace 3 of the internal circulation fluidized bed boiler 1 . Therefore, the fuel supply system 2 can stably and quantitatively supply fuel to the internal circulation fluidized bed boiler 1.

The operation control section 60 is also connected to the screw feeder 22. The operation control unit 60 controls the operation of the screw feeder 22 so as to supply the optimum fuel to the combustion furnace 3 according to the heat load in the internal circulation fluidized bed boiler 1 .

The operation control unit 60 includes at least one computer. The operation control section 60 includes therein a storage device 60a and a calculation device 60b. The arithmetic device 60b includes a CPU (central processing unit), a GPU (graphics processing unit), or the like that performs arithmetic operations according to instructions included in a program stored in the storage device 60a. The storage device includes a main storage device (eg, random access memory) that can be accessed by the computing device 60b, and an auxiliary storage device (eg, a hard disk drive or solid state drive) that stores data and programs.

Next, the configuration of the storage conveyor 30 will be described with reference to FIG. 2. FIG. 2 is a schematic diagram showing one embodiment of the storage conveyor 30. The lower end of the storage hopper 31 is open, and the drag chain conveyor 32 is connected to the lower end of the storage hopper 31 . Therefore, the fuel present at the lower end of the storage hopper 31 contacts the drag chain conveyor 32, and the drag chain conveyor 32 can withdraw the fuel.

The drag chain conveyor 32 includes an endless drag chain 33, a driving sprocket 35, a driven sprocket 37, and an electric motor 39 connected to the driving sprocket 35 via a torque transmission mechanism 38. The electric motor 39 has an inverter (not shown) that makes its rotation speed variable. The torque transmission mechanism 38 is composed of a combination of a belt and a pulley, or a combination of a chain and a sprocket, but its composition is not particularly limited. The drag chain 33 is hung around a driving sprocket 35 and a driven sprocket 37.

When electric motor 39 rotates drive sprocket 35, drag chain 33 circulates. The driven sprocket 37 supports the drag chain 33 and rotates as the drag chain 33 circulates. The electric motor 39 is connected to an operation control section 60 , and the rotation speed of the electric motor 39 , that is, the conveyance speed of the drag chain conveyor 32 is controlled by the operation control section 60 .

The storage hopper 31 has a fuel inlet 46 at its upper part. Fuel is introduced into the storage hopper 31 through the fuel injection port 46 . The level detector 41 is fixed to the upper part of the storage hopper 31 and is arranged to face the inside of the storage hopper 31. The level detector 41 is connected to the operation control section 60 and is configured to send a signal indicating the storage level of fuel in the storage hopper 31 to the operation control section 60 .

Storage hopper 31 has an end wall 45 with an opening 44 . End wall 45 extends upward from drag chain 33, and opening 44 is provided at the bottom of end wall 45. The drag chain 33 is inclined upward along the fuel transport direction. That is, the drag chain 33 is inclined upward toward the opening 44. The inclination angle α of the drag chain 33 with respect to the horizontal direction is preferably within the range of 10° to 20°. In this embodiment, the inclination angle α of the drag chain 33 with respect to the horizontal direction is 15°. The opening 44 is located near the upper end of the drag chain 33. Drag chain 33 transports the fuel in storage hopper 31 upward toward opening 44 .

FIG. 3 is a top view showing a portion of the drag chain 33. The drag chain 33 includes side plates 34A arranged in parallel, a cylindrical roller 34B extending between these side plates 34A, and a pin 34C extending inside the roller 34B. The side plate 34A is rotatable around the pin 34C. A space is formed between the side plates 34A on both sides.

Returning to FIG. 2, the drag chain conveyor 32 has a bottom plate 47 inclined at the same angle as the drag chain 33. This bottom plate 47 is arranged between an upper portion 33a of the drag chain 33 that moves toward the opening 44 and a lower portion 33b of the drag chain 33 that moves in a direction away from the opening 44. When the electric motor 39 operates to circulate the drag chain 33, the upper portion 33a of the drag chain 33 moves diagonally upward toward the opening 44 above the bottom plate 47. The fuel in the storage hopper 31 is dragged by the drag chain 33 and conveyed obliquely upward on the bottom plate 47.

Storage conveyor 30 includes an exit chute 48 connected to end wall 45 . The outlet chute 48 has a fuel outlet 48A facing downward. The end of the outlet chute 48 is arranged to surround the opening 44, and the interior of the outlet chute 48 communicates with the opening 44. As the drag chain 33 circulates, the fuel is discharged from the storage hopper 31 through the opening 44, further passes through the outlet chute 48, and is discharged downward from the fuel discharge port 48A.

The lower end of the storage hopper 31 is closed by a drag chain conveyor 32. More specifically, the lower end of the storage hopper 31 is closed by a bottom plate 47 disposed below the upper portion 33a of the drag chain 33. In such a configuration, when the drag chain 33 circulates, the entire lower part of the fuel in the storage hopper 31 is dragged diagonally upward by the drag chain 33. Therefore, the fuel in the storage hopper 31 is initially accumulated as shown by the dotted line in FIG. Move toward wall 45. Note that, since it is preferable that the fuel is allowed to fall into the space created after being moved, the fuel inlet 46 is preferably installed at the rear of the storage hopper 31 than in the middle thereof.

In this way, the drag chain conveyor 32 can move the fuel more generally than the screw feeder, so it is less likely to form fuel bridges. There is a rotary table feeder that uses the same bottom pulling method, but this type of feeder requires a circular hopper and cannot increase the hopper capacity. In this respect, in the drag chain conveyor 32, since the storage hopper 31 can be made into a square shape, the capacity of the storage hopper 31 can be increased. Furthermore, compared to a rotary table feeder, the drag chain conveyor 32 has the advantage that it is less likely to form bridges because it can move the fuel throughout.

A portion of the fuel is discharged from storage hopper 31 through opening 44 by drag chain conveyor 32 . The other part of the fuel is dragged by the drag chain 33 and pressed against the end wall 45 of the storage hopper 31. The fuel pressed against the end wall 45 moves upward along the end wall 45. Since the drag chain 33 is inclined, the fuel that has moved upward along the end wall 45 collapses to the rear of the storage hopper 31. In this way, as shown by the black arrow in FIG. 2, as the drag chain 33 circulates, most of the fuel flows (swivels) within the storage hopper 31, which prevents the fuel from forming bridges. can do. In particular, the storage conveyor 30 according to this embodiment can prevent fuel bridging without using a bridge breaker. In this specification, the rear of the storage hopper 31 is the direction opposite to the end wall 45 of the storage hopper 31, and the direction opposite to the fuel conveyance direction.

As shown in FIG. 4, in one embodiment, the end wall 45 of the storage hopper 31 in which the opening 44 is formed may be inclined toward the rear of the storage hopper 31 with respect to the vertical direction. The rearwardly inclined end wall 45 has the effect of returning the fuel that has moved upward along the end wall 45 to the rear of the storage hopper 31. As a result, the fuel flows (swirls) within the storage hopper 31 as shown by the arrow in FIG. 4, and the formation of bridges can be more effectively prevented.

The inclination angle β of the end wall 45 with respect to the vertical direction is within the range of 5° to 20°, preferably within the range of 10° to 20°. If the inclination angle β of the end wall 45 is too small, the effect of returning the fuel to the rear of the storage hopper 31 will be weakened. On the other hand, if the inclination angle β of the end wall 45 is too large, the amount of fuel that can be stored will decrease. From these viewpoints, the inclination angle β of the end wall 45 is determined to be within the range of 5° to 20°, preferably within the range of 10° to 20°.

FIG. 5 is a diagram showing one embodiment of the input conveyor 20. As shown in FIG. The input conveyor 20 includes an input hopper 21 and a screw feeder 22. The input hopper 21 has a fuel input port 28 at its upper part. Fuel is introduced into the input hopper 21 through the fuel input port 28 . The lower end of the charging hopper 21 is open, and the screw feeder 22 is connected to the lower end of the charging hopper 21 . The fuel present at the lower end of the charging hopper 21 flows into the screw feeder 22. Although the charging conveyor 20 of this embodiment includes only one screw feeder 22, a plurality of screw feeders 22 may be connected to the lower end of the charging hopper 21.

The screw feeder 22 includes a screw housing 24, a screw 25 disposed within the screw housing 24, and an electric motor 27 connected to the screw 25 via a torque transmission mechanism 26. The electric motor 27 has an inverter (not shown) that makes its rotation speed variable. The electric motor 27 is connected to an operation control section 60 , and the rotation speed of the electric motor 27 , that is, the conveyance speed of the screw feeder 22 is controlled by the operation control section 60 . The torque transmission mechanism 26 is composed of a combination of a belt and a pulley, or a combination of a chain and a sprocket, but its composition is not particularly limited.

The screw housing 24 has an inlet 24a communicating with the lower end of the charging hopper 21, and a fuel outlet 24b located at the lower part of the screw housing 24. The fuel outlet 24b is connected to the combustion furnace 3 of the internal circulation fluidized bed boiler 1 shown in FIG. The level detector 42 is fixed to the upper part of the input hopper 21 and is arranged facing inside the input hopper 21. The level detector 42 is connected to the operation control unit 60 and is configured to send a signal indicating the level of fuel stored in the charging hopper 21 to the operation control unit 60.

When the electric motor 27 rotates the screw 25, the fuel in the charging hopper 21 moves into the screw housing 24 through the inlet 24a. Fuel is moved within the screw housing 24 by the rotating screw 25 and is discharged through the fuel outlet 24b. The screw feeder 22 can convey fuel quantitatively compared to the drag chain conveyor 32. Therefore, the screw feeder 22 can supply the optimum fuel to the combustion furnace 3 according to the heat load in the internal circulation fluidized bed boiler 1.

FIG. 6 is a schematic diagram showing another embodiment of the fuel supply system 2. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to FIGS. 1 to 5, and therefore, redundant description thereof will be omitted.

This embodiment is the same as the embodiment described above in that the storage conveyor 30 is arranged between the silo 15 and the input conveyor 20, but the storage conveyor 30 is arranged between the supply conveyor 50 and the input conveyor 20. They are different in that they are That is, one end of the replenishment conveyor 50 is arranged below the silo 15, and the other end of the replenishment conveyor 50 is arranged above the storage hopper 31 of the storage conveyor 30. The input conveyor 20 is arranged below the storage conveyor 30.

The fuel is cut out from the silo 15 by the cutting device 16, falls onto the replenishment conveyor 50, and is conveyed into the storage hopper 31 of the storage conveyor 30 by the replenishment conveyor 50. Fuel is stored in the storage hopper 31 and is directly supplied from the storage hopper 31 into the input hopper 21 of the input conveyor 20 by the drag chain conveyor 32. The input hopper 21 may be connected to the storage conveyor 30. Fuel is quantitatively supplied from the charging hopper 21 to the combustion furnace 3 of the internal circulation fluidized bed boiler 1 by means of a screw feeder 22 .

In this embodiment, the cutting device 16 and the replenishment conveyor 50 constitute a fuel transfer device that transfers fuel from the silo 15 to the storage hopper 31 of the storage conveyor 30. Similar to the embodiment described with reference to FIGS. 1 to 5, the storage hopper 31 of the storage conveyor 30 is provided with a level detector 41, and the input hopper 21 of the input conveyor 20 is provided with a level detector 42. It is being Level detector 41 , level detector 42 , cutting device 16 , supply conveyor 50 , drag chain conveyor 32 , and screw feeder 22 are connected to operation control section 60 .

The operation control unit 60 controls the cutting device 16, which is a fuel transfer device, and the cutting device 16, which is a fuel transfer device, so that the fuel storage level in the storage hopper 31 of the storage conveyor 30 detected by the level detector 41 is maintained at a predetermined first value. Controls the operation of the replenishment conveyor 50. Further, the operation control unit 60 controls the operation of the drag chain conveyor 32 so that the fuel storage level in the input hopper 21 of the input conveyor 20 detected by the level detector 42 is maintained at a predetermined second value. control.

The embodiments described above have been described to enable those skilled in the art to carry out the invention. Various modifications of the above embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the invention is not limited to the described embodiments, but is to be construed in the broadest scope according to the spirit defined by the claims.

1 Internal circulation fluidized bed boiler 2 Fuel supply system 3 Combustion furnace 4 Floor plate 5 Heat transfer tube 7 Air supply line 10 Fluidized bed 15 Silo 16 Cutting device (fuel transfer device)
20 Input conveyor 21 Input hopper 22 Screw feeder 24 Screw housing 25 Screw 26 Torque transmission mechanism 27 Electric motor 28 Fuel inlet 30 Storage conveyor 31 Storage hopper 32 Drag chain conveyor 33 Drag chain 34A Side plate 34B Roller 34C Pin 35 Drive sprocket 37 Driven Sprocket 38 Torque transmission mechanism 39 Electric motor 40 Leveling conveyor 41 Level detector 42 Level detector 44 Opening 45 End wall 46 Fuel inlet 47 Bottom plate 48 Exit chute 48A Fuel outlet 50 Replenishment conveyor 60 Operation control section

Claims (5)

A fuel supply system for supplying fuel to a fluidized bed furnace, the system comprising:
A silo for storing fuel,
an input conveyor for inputting fuel into the fluidized bed furnace;
comprising a storage conveyor disposed between the silo and the input conveyor,
The input conveyor has an input hopper that receives fuel conveyed from the silo via the storage conveyor,
The storage conveyor is
a storage hopper that stores fuel supplied from the silo;
A drag chain conveyor connected to the storage hopper and conveying the fuel in the storage hopper,
The drag chain conveyor includes an endless drag chain that slopes upward along the fuel conveyance direction ,
The storage hopper has an end wall with an opening,
the drag chain is inclined upward toward the opening;
In the fuel supply system , the end wall is inclined in a direction opposite to the conveyance direction with respect to the vertical direction as it goes upward from the opening . The fuel supply system according to claim 1 , wherein an inclination angle of the end wall with respect to the vertical direction is within a range of 5° to 20°. The fuel supply system according to claim 1 or 2 , wherein the inclination angle of the drag chain with respect to the horizontal direction is within a range of 10° to 20°. The fuel supply system according to any one of claims 1 to 3 , wherein the input conveyor includes a screw feeder connected to the input hopper. a first level detector that detects the storage level of fuel in the storage hopper;
a second level detector that detects the fuel storage level in the input hopper;
a fuel transfer device that transfers fuel from the silo to the storage hopper;
further comprising an operation control unit that controls operations of the fuel transfer device and the drag chain conveyor,
The operation control unit controls the operation of the fuel transfer device so that the storage level in the storage hopper detected by the first level detector is maintained at a predetermined first value, and 2. The method of claim 1, wherein the storage level in the input hopper detected by a two-level detector is configured to control the operation of at least the drag chain conveyor so that the storage level in the input hopper is maintained at a predetermined second value. 5. The fuel supply system according to any one of 4 to 5 .

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