JP2721872B2 - Method and apparatus for recovering heat from a fluidized bed - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for efficiently recovering heat from a fluidized bed by controlling the combustion temperature when burning fuel such as municipal solid waste, industrial waste, and coal in a fluidized bed. It is.

[0002]

2. Description of the Related Art It is well known that a heat transfer tube is provided in a fluidized bed so that the combustion temperature of the fluidized bed becomes a predetermined temperature. As a method of separately performing a region where a heat transfer tube is provided and a region where a heat transfer tube is not provided in a fluidized bed, a method of not providing a partition plate in both regions is disclosed in JP-A-59-173608. The method of providing a partition plate in both areas is disclosed in JP-A-49-95470 and JP-A-62-272.
No. 089.

[0003]

The fluidized bed combustion temperature depends on the purpose. For example, in a method using limestone as a desulfurizing agent, the temperature is designed to be about 750 to 900 ° C. because there is an optimum temperature for desulfurization. Temperature is set. With fuel containing chlorine, such as municipal solid waste, HCl generated during combustion corrodes the heat transfer tubes, so that the heat transfer tubes cannot be provided directly in the fluidized bed. For this reason, it was necessary to develop a fluidized bed in which the combustion section and the heat collection section were separated.

[0004] In the fluidized bed combustion furnace disclosed in Japanese Patent Laid-Open No. 62-27289, the gas flow rate difference between a region a where a heat transfer tube is not provided in a fluidized bed and a region b where a heat transfer tube is provided in a fluidized bed, specifically, Is to make the gas flow rate in the area a faster than the gas flow rate in the area b and circulate the fluid material between the area a and the area b. The area a is a fuel combustion area, and depends on the fuel supply amount. Since the supplied air is supplied, the gas flow rate cannot be changed significantly. Further, the circulation amount can be changed by changing the gas flow rate in the region b, but has the following disadvantages.

That is, if the gas flow velocity in the heat recovery area b is increased, the heat transfer characteristics of the heat transfer tube are improved, but the relative speed with respect to the area a is reduced, the circulation amount is reduced, and the heat collection amount can be greatly increased. However, there is a drawback that the heat transfer tube wear increases as the gas flow rate increases. Further, when the gas flow rate is slow, the fluidization of the heat recovery area b is partially stopped or becomes unstable, so that there is a disadvantage that the temperature of the combustion area a fluctuates greatly and the amount of recovered heat fluctuates greatly. . In the worst case, when unburned material in the fuel enters the heat recovery chamber along with the fluidized material, the unburned material burns in the area with poor fluidization, and the temperature rises to a high level, causing the fluidized particles to clump. So-called clinker trouble occurs.

Further, as shown in FIG. 5, there is a limit to the distance in which the fluid material scatters from the combustion area a and reaches the heat recovery area b. Therefore, the width L of the heat recovery area b shown in FIG. Even when the heat transfer tube is provided, the high-temperature fluid material does not scatter, so that the heat transfer effect of the heat transfer tube is reduced, and the heat transfer tube cannot be arranged effectively. This problem can be solved by increasing the depth of the fluidized bed, but has the disadvantage of increasing the pressure loss.

The present invention has been made in view of the above points, and an object of the present invention is to supply air to an incombustible discharge pipe,
It is an object of the present invention to provide a method and apparatus for controlling the fluidized bed temperature of a combustion chamber by adjusting the amount of supplied air. Another object of the present invention is to provide a heat recovery area b in which a heat transfer tube is provided.
It is an object of the present invention to provide a method and apparatus for controlling the temperature of a fluidized bed in a combustion chamber while increasing the amount of heat recovery by minimizing an increase in pressure loss by making the fluidized bed only deep.

[0008]

The gas flow rate in the heat recovery area b is set to a relatively high flow rate at which partial fluidization does not occur, and the gas flow in the combustion area a is provided on the partition plate in the combustion area a side. A separate air supply section c is provided which is separated from the box. By changing the amount of air supply to change the amount of flowing particles moving to the heat recovery area b, the air is cooled from the heat recovery area and circulated to the combustion area. By changing the amount of flowing fluid particles, the combustion area a
To control the combustion temperature.

FIG. 3 shows that the combustion zone “a” is set to 3
At twice the gas flow rate, the heat recovery area b is set to 1.
This shows a state in which fluidization is performed at a gas flow rate five times and the amount of air in c is stopped, and areas a and b are fluidized but air is not supplied from c. The circulation of fluid material has stopped. Region d shows this stop layer.

From this state, by changing the amount of air from the air supply unit c, the amount of circulation in the combustion area a and the heat recovery area b changes as shown in FIG. Therefore, the flow rate of the fluid that is cooled in the heat recovery area b and returns to the combustion area a changes, so that the combustion temperature in the combustion area a can be controlled to a predetermined temperature.

In order to achieve the above object, the method of recovering heat from a fluidized bed according to the present invention comprises the steps of: forming a fluidized bed fluidized by air blown upward from a bottom portion; Partitioned into a combustion chamber and a heat recovery chamber by a partition member having an opening above the height of the stationary layer,
In a method in which independent wind boxes are provided below the combustion chamber and the heat recovery chamber to recover heat from the fluidized bed, an incombustible discharge pipe is provided through the combustion chamber wind box. By blowing air, the flowing material of the combustion chamber flows into the heat recovery chamber from the upper opening of the partition member, and the circulating flow of flowing the flowing material of the heat recovery chamber into the combustion chamber from the lower opening of the partition member is formed. Further, the invention is characterized in that the fluidized bed temperature of the combustion chamber is controlled by adjusting the amount of air supplied to the incombustible discharge pipe. In the above method, the fluid material containing incombustible material discharged from the incombustible material discharge conduit is classified, separated into coarse incombustible material and fluid material, and the coarse incombustible material is discharged outside the system, Preferably, the material is circulated to the combustion chamber.

An apparatus for recovering heat from a fluidized bed according to the present invention comprises:
A fluidized bed formed by air blown upward from an air distribution plate, and a chamber provided with the fluidized bed are separated by a partition member having an opening at a lower end portion and an upper portion of the fluidized bed above the stationary bed height. A fluidized bed consisting of a heat recovery chamber in which the formed combustion chamber and heat transfer tube are buried in the layer, and a wind box provided with an independent air blowing amount adjustment mechanism respectively provided below the combustion chamber and the heat recovery chamber The apparatus for recovering heat further includes an incombustible discharge pipe provided through the wind box of the combustion chamber, an air supply pipe having flow rate control means connected to the incombustible discharge pipe, and a flow of the combustion chamber. A temperature control means connected to the bed is provided, and the flow rate control means of the air supply pipe is connected to the temperature control means so that the fluidized bed temperature of the combustion chamber is controlled by the amount of air supplied to the incombustible discharge pipe. The feature is that To have. In the above device, the lower opening of the partition member is provided below the air distribution plate of the combustion chamber, or the air distribution plate is inclined so as to become lower toward the upper opening of the incombustible discharge pipe. It is preferable to provide them.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. However, the shapes of the components described in this embodiment, the relative arrangement thereof, and the like are not intended to limit the scope of the present invention to them only, unless otherwise specified, and are merely illustrative examples. It's just Embodiment 1 An embodiment of a method and an apparatus for recovering heat from a fluidized bed according to the present invention will be described with reference to FIG. Reference numeral 1 denotes an apparatus main body which is manufactured with a water-cooled tube structure (a refractory material structure is also possible). Reference numeral 2 denotes a fluidized bed combustion chamber, for example, a calorific value of 4000 kcal / kg from the fuel supply port 18.
Industrial waste will be supplied. The fluidized bed is fluidized by air supplied from a wind box 7 provided at the lower part of the fluidized bed combustion chamber 2 through the air distribution plate 6 to burn waste.
In the main body 1, a fluidized bed heat recovery chamber 4 separate from the combustion chamber fluidized bed is divided by a partition member 3, and a heat transfer tube 5 is provided in the bed. The fluidized bed is fluidized by air supplied from the lower wind box 8 via the air distribution plate 6, and the fluid in the heat transfer tube 5 absorbs heat. The heat transfer tube 5 is a superheater tube (or a reheat tube,
A water-cooled tube may be used).

An air supply port 11 is provided in an incombustible discharge pipe 13 provided below the partition member 3 and penetrating through the wind box 7 of the combustion chamber 2. The air supply pipe 12 provided with a valve (or damper) 30 is connected. The fluidized material particles are composed of particles of about 0.5 to 1 mm, and limestone, dolomite, etc. are supplied as a desalinating agent or desulfurizing agent as needed. The fuel is fluidized at about 3 to 5 times the superficial velocity to burn the fuel. The temperature of the combustion chamber is generally about 550 to 900 ° C.
For example, the temperature is designed to be a predetermined temperature such as about 550 to 700 ° C. under the condition of performing desalination, and about 750 to 850 ° C. under the condition of performing desulfurization. If the calorific value of the fuel is high, the combustion temperature increases. Therefore, a part of the heat generated by the combustion is collected by the heat transfer tube 5 of the heat recovery chamber 4 so as to reach a predetermined combustion temperature. The heat recovery chamber 4 is provided with necessary heat transfer tubes 5 designed and calculated in advance.

A high-temperature fluid substance is transferred from the combustion chamber 2 to the heat recovery chamber through an upper opening 19 of the partition member 3 having a water-cooled pipe structure (or a refractory material structure), preferably at least as high as the stationary layer. 4, the heat is removed by the heat transfer pipe 5 and cooled, and the cooled fluid is circulated to the combustion chamber 2 from the lower opening 20 provided at the lower part of the partition member. The circulation of the fluid material is performed by the superficial velocity of the partition member 19 on the combustion chamber side,
That is, the superficial velocity near the upper opening 14 of the incombustible discharge pipe 13 is higher than the superficial velocity of the partition member 3 on the heat recovery chamber side. Generally, the superficial velocity near the upper opening 14 of the incombustible discharge pipe 13 is set to 3 to 5 times the fluidization start flow velocity, and the superficial velocity at the heat recovery chamber side of the partition member 3 is changed from the fluidization start flow velocity to the flow velocity. The circulation of the fluid material is performed within a range of about twice the flow rate at the start of the formation.

The temperature of the fluidized bed in the combustion chamber 2 is controlled by adjusting a control valve 30 for supplying air to the incombustible discharge pipe 13. When the air supplied from the incombustible discharge pipe 13 is stopped, fluidization of the fluidized bed portion of the incombustible discharge pipe 13 stops, and the fluidized bed portion becomes stationary.
From 0, the movement of the fluid substance stops. In the upper opening 19 of the partition member 3, the fluid substance alternately moves between the combustion chamber 2 and the heat recovery chamber 4, but the amount thereof is small, and the heat is hardly removed from the combustion chamber 2. As described above, when it is not necessary to remove heat from the combustion chamber 2, for example, at the time of startup, the air in the heat recovery chamber 4 may be stopped.

When the flow rate of the air from the incombustible discharge pipe 13 is increased to be in a fluidized state, the flowable substance in the heat recovery chamber 4 moves from the lower opening 20 of the partition member 3 to the combustion chamber 2 and thereby moves upward. The high-temperature fluid material in the combustion chamber 2 moves from the opening 19 to the heat recovery chamber 4, and the fluid material receives heat by the heat transfer tube 5, is cooled, and circulates to the combustion chamber 2. If the superficial velocity of the combustion chamber 2 and the heat recovery chamber 4 is constant, it increases as the flow rate of the air supplied to the incombustible discharge pipe 13 increases. As described above, the temperature of the combustion chamber 2 is controlled to a predetermined fluidized bed temperature by adjusting the amount of air supplied to the incombustible discharge pipe 13.
Further, by adjusting the flow rate of the air supplied to the incombustible discharge pipe 13, the amount of heat recovered in the heat recovery chamber 4 can be controlled.

The air distribution plate 6 is inclined so as to become lower toward the upper opening 14 of the incombustible discharge pipe 13. Therefore, the movement and discharge of the fluid material and the like are performed more smoothly. Reference numeral 31 denotes a temperature instruction control unit connected to the fluidized bed of the combustion chamber 2.
Is connected to the flow rate control valve 30. The fluid material containing the incombustible material extracted from the incombustible discharge pipe 13 is separated into coarse incombustible material and fluid material by a classification means 15 such as a sieve, and the coarse incombustible material is discharged outside the system. The exhausted fluid material is circulated to the combustion chamber 2 and reused. 41 and 42 are air flow control valves (or dampers).

Embodiment 2 In this embodiment, as shown in FIG.
Is provided below the air distribution plate 6 of the combustion chamber 2 so that the fluidized bed of the heat recovery chamber 4 is deepened, the number of heat transfer tubes 5 to be stored is increased, and the amount of heat collected is further increased. It is composed. Also in this case, the air distribution plate 6 is inclined so as to become lower toward the upper opening 14a of the incombustible discharge pipe 13. Other configurations and operations are the same as those of the first embodiment.

[0020]

As described above, the present invention has the following effects. (1) By adjusting the amount of air supplied to the incombustible discharge pipe, the amount of circulating fluid can be controlled, so that the temperature of the fluidized bed in the combustion chamber can be controlled to a desired predetermined temperature. In addition, the amount of heat recovered in the heat recovery chamber can be controlled. (2) When only the fluidized bed of the heat recovery chamber is formed deeply,
An increase in heat loss can be achieved by minimizing an increase in overall pressure loss.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an apparatus for recovering heat from a fluidized bed according to the present invention.

FIG. 2 is a schematic configuration diagram showing another embodiment of the apparatus for recovering heat from a fluidized bed according to the present invention.

FIG. 3 is an explanatory diagram in a case where air is not supplied from an air supply unit c to an incombustible discharge pipe in the apparatus of the present invention.

FIG. 4 is a graph showing a relationship between a fluidized bed superficial velocity by air from an air supply unit c and a circulating amount of a fluid substance.

FIG. 5 is a graph showing a relationship between a distance from a partition plate and a scattered amount of a fluid substance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Device main body 2 Combustion chamber 3 Partition member 4 Heat recovery chamber 5 Heat transfer tube 6 Air distribution plate 7 Wind box 8 Wind box 11 Air supply port 12 Air supply pipe 13 Noncombustible discharge pipe 14 Upper opening 14a Upper opening 15 Classifier 18 Fuel Supply port 19 Upper opening 20 Lower opening 30 Air flow control valve 41 Air flow control valve 42 Air flow control valve

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuo Abe 2-4-1 Hamamatsucho, Minato-ku, Tokyo Kawasaki Heavy Industries, Ltd. Tokyo Head Office (56) References JP-A-62-272089 (JP, A)

Claims (5)

(57) [Claims] 1. A fluidized bed for fluidizing a fluidized material by air blown upward from a bottom portion, a combustion chamber and heat recovery by a partition member having openings at a lower end portion and an upper portion of the fluidized bed above the stationary bed height. A method of recovering heat from a fluidized bed by providing independent wind boxes below the combustion chamber and the heat recovery chamber, and providing an incombustible discharge pipe through the combustion chamber wind box; By blowing air into the incombustible discharge pipe, the fluid in the combustion chamber flows into the heat recovery chamber from the upper opening of the partition member, and the fluid in the heat recovery chamber flows into the combustion chamber from the lower opening of the partition member. By forming a circulating flow and adjusting the amount of air supplied to the incombustible discharge pipe,
A method for recovering heat from a fluidized bed, comprising controlling the temperature of the fluidized bed in a combustion chamber. 2. A fluid material containing an incombustible substance discharged from a noncombustible substance discharge conduit is classified, separated into a coarse incombustible substance and a fluid substance, and the coarse incombustible substance is discharged out of the system. The method for recovering heat from a fluidized bed according to claim 1, wherein the material is circulated to the combustion chamber. 3. A fluidized bed formed by air blown upward from an air distribution plate, and a partition provided with a chamber provided with the fluidized bed, each having an opening at a lower end portion and an upper portion of the fluidized bed above the height of the stationary bed. A heat recovery chamber in which a combustion chamber and a heat transfer tube formed separately by members are embedded in a layer; and a wind box provided with independent air blowing amount adjustment mechanisms provided below the combustion chamber and the heat recovery chamber, respectively. An apparatus for recovering heat from a fluidized bed comprising: a non-combustible discharge pipe provided through a wind box of a combustion chamber; and an air supply pipe including a flow control means connected to the non-combustible discharge pipe. Temperature control means connected to the fluidized bed of the combustion chamber, and connecting the flow rate control means of the air supply pipe and the temperature control means, and controlling the combustion chamber by the amount of air supplied to the incombustible discharge pipe. So that fluidized bed temperature is controlled An apparatus for recovering heat from a fluidized bed. 4. The apparatus for recovering heat from a fluidized bed according to claim 3, wherein the opening at the lower part of the partition member is provided below the air distribution plate of the combustion chamber. 5. The apparatus for recovering heat from a fluidized bed according to claim 3, wherein the air distribution plate is inclined so as to become lower toward the upper opening of the incombustible discharge pipe.