JPH1019206A - Circulation amount control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circulation amount control device which can prevent an inflow of particles to a cyclone separator even when an amount of particles stacked in a stand pipe is small thus enabling a smooth circulation of particles. SOLUTION: Particles fed from a combustion chamber is separated frown gas in a cyclone separator, wherein the gas is discharged outside and particles are accumulated in a stand pipe 3. A lower portion of the stand pipe 3 is made of an inclined pipe 23 and the inclined pipe 23 is connected with a hot recycle line 6. The inclined pipe 23 is provided with a cold recycle line 5 which vertically extends downwardly from the inclined pipe 23. The inclined pipe 23 is communicated with the cold recycle line 5 by way of a particle extracting tube 15 which is disposed within the cold recycle line 5. Air blown from a blower 14d enters the hot recycle line 6 by way of a seal pot 4 and reduces a pressure in the lower portion of the stand pipe 3. While the particles are fed to the hot recycle line 6, the particles are also fed to the cold recycle line 5 by way of the particle extracting tube 15 making use of gravity. The amount of particles extracted through the particle extracting tube 15 can be regulated by a particle extracting amount regulating valve 16. Accordingly, fluidization of particles in the stand pipe 3 can be prevented so that the particles are smoothly circulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a device for controlling the amount of circulating particles in a circulating fluidized-bed boiler.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a circulating fluidized bed boiler. In the figure, 1 is a combustion chamber, 2 is a cyclone, 3 is a stand pipe, 4 is a seal pot, 5 is a cold recycle line, 6 is a hot recycle line, 7 is a fluidized bed heat exchanger, 8 is a convection heat transfer surface, 9 Is a bag filter, 10 is an induction fan, 11 is a chimney, 12 is an ash extraction device, 13 is an ash extraction valve, and 14a, 14b, 14c and 14d are blowers.

[0003] As described above, the circulating fluidized bed boiler includes the combustion chamber 1, the cyclone 2, the stand pipe 3, the seal pot 4, and the main parts of the fluidized bed heat exchanger 7,
Combustion air is supplied from the blowers 14a and 14b to form a fluidized state called a high-speed fluidized bed, in which fuel is burning.

[0004] Fluid material such as silica sand exists in the combustion chamber 1, and a system formed from the combustion chamber 1, the cyclone 2, the stand pipe 3, the seal pot 4, and the fluidized bed heat exchanger 7 together with unburned fuel. Circulating inside.

[0005] The combustion gas and the fluidized material are separated by the cyclone 2, and the gas is discharged from the chimney 11 through the convection heat transfer surface 8, the bag filter 9 and the induction fan 10.

On the other hand, the fluidized material separated in the cyclone 2 is circulated to the combustion chamber 1 by the seal pot 4 using the air from below in the hot recycle line 6.
After being cooled by the fluidized bed heat exchanger 7, the combustion chamber 1
Divided into cold recycling lines 5
Recirculate each. Particles remaining in the combustion chamber 1 are discharged out of the system by an ash extraction device 12 as necessary.

FIG. 2 is an enlarged view of a conventional apparatus for controlling the amount of circulating particles in the circulating fluidized-bed boiler described above. In FIG. 2, particles jumping out of the upper combustion chamber 1 (not shown) are collected by the cyclone 2 and deposited on the stand pipe 3.

Air is injected into the deposited particles from below the stand pipe 3 by a blower 14 d, and the particles are discharged from the ash extraction valve 13 to the cold recycling line 5 by the pressure of the air. The amount of discharged particles is adjusted by the opening of the ash extraction valve 13.

On the other hand, the other side of the seal pot 4 is filled with air for hot recycling from below.
Here too, the particles are discharged to the hot recycling line 6 by the pressure of air.

[0010]

In recent years, as the size of an external circulating fluidized bed boiler has increased, the area of a combustor has increased, and the size of a cyclone has also increased. However, considering the cost, the height of the combustor cannot be increased, and as a result,
The length of the standpipe under the cyclone is also reduced. A device for controlling the amount of circulating particles, called a seal pot below the standpipe, acts to separate particles into hot recycling and cold recycling by air from below. Here, the following problems arise due to the short stand pipe.

(1) In some cases, the pressure on the combustor side cannot be sealed due to a decrease in the amount of particles deposited on the stand pipe.

(2) The amount of particles deposited on the standpipe is reduced, and the particles deposited on this portion may flow due to air from below, and the particles may not be discharged to the cold recycle.

(3) In the above (2), when the particles flow in the seal pot portion, the injected air flows into the cyclone, and the cyclone efficiency may be reduced.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides the following means capable of eliminating a defective particle discharge due to a decrease in the amount of particles deposited on a standpipe. .

[0015] Particles ejected from the combustion chamber of the fluidized-bed boiler are separated from the gas by a cyclone, deposited on a standpipe under the cyclone, and air is sent from the lower part to be recirculated from the hot recycle line and the cold recycle line to the combustion chamber. In the apparatus for controlling the amount of circulated particles to be controlled, an inclined portion having an angle is provided at a lower portion of the stand pipe and connected to the hot recycle line side, and the collected particles are guided to the hot recycle line side, and the inclined portion is inclined. A circulation amount control device, wherein a vertical pipe is attached to the section to discharge a part of the particles to the cold recycling line.

According to the present invention, as described above, the inclined layer having an angle on the stand pipe lengthens the deposited layer of the particles, guides the particles to the hot recycle side, and pressurizes the particles by the pressure of air from below. Discharge to In addition, since a vertical pipe is attached to the inclined portion below the stand pipe for discharging to the cold recycling line, some of the particles are discharged by gravity without using air by the vertical pipe. In addition, the amount of cold recycle can be adjusted by the degree of opening by providing a particle discharge adjustment valve below the cold recycle discharge pipe.

According to the present invention, as described above, by providing the stand pipe with the inclined portion, the particle deposition layer can be lengthened. Further, since only the hot recycle line is used for air, the pressure under the cyclone can be made lower than before and the blower capacity can be made smaller. Further, since the discharge to the cold recycling line is caused to fall naturally by gravity, defective discharge does not occur.

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a configuration diagram of a circulation amount control device in a circulating fluidized bed boiler according to one embodiment of the present invention. In FIG. 1, reference numerals 3 to 6, 1
Since 4d is a member having the same function as the conventional example shown in FIG. 2, detailed description will be omitted and will be referred to as it is, but the characteristic portions of the present invention are portions denoted by reference numerals 15, 16, and 23.
Hereinafter, these features will be described in detail.

In FIG. 1, when the particles scattered from the upper combustion furnace are recirculated separately to the hot recycling line 6 and the cold recycling line 5, the lower part of the stand pipe 3 is formed as an angled pipe 23, and the hot recycling is performed. The particles are guided to a position for discharging the line, and discharged to the hot recycling line 6 by the pressure of air from below.

On the other hand, for discharging the particles to the cold recycling line 5, a particle extraction pipe 15 is provided vertically at an angled pipe 23 below the stand pipe 3, and the particles are vertically discharged by gravity. 5
Discharge to

The amount of particles discharged to the cold recycle line 5 is controlled by a particle discharge adjusting valve 16 below the particle discharge pipe 15.
Is adjusted by the opening degree of the adjustment valve 16.

The angle of the pipe 23 below the stand pipe 3 varies depending on the installation condition of the boiler. However, when the angle of repose is larger than the angle of repose of the circulating particles, a better particle flow can be obtained.

In the above embodiment, the following effects can be obtained.

(1) Since the lower part of the stand pipe 3 below the cyclone 2 is angled to form the pipe 23, the deposited layer of particles can be lengthened.

(2) As for the air, since the pipe 23 is connected to the lower part of the hot recycling line 6, only the hot recycling line 6 is used, so that the pressure below the cyclone 2 can be made lower than before. This can prevent particles from flowing in the stand pipe 3.
Further, the capacity of the blower 14d can be reduced.

(3) Since the particles are discharged to the cold recycling line 5 by gravity and naturally dropped by the vertically provided discharge pipe 15, no discharge failure occurs.

[0027]

As described above, according to the present invention, in the apparatus for controlling the circulation of particles in a fluidized-bed boiler, an inclined portion having an angle is provided at the lower portion of the stand pipe so that the particles can be disposed on the side of the hot recycling line. And a vertical pipe is attached to the inclined portion to discharge the particles to the cold recycling line by gravity. Therefore, the following advantageous effects of solving the conventional problems in the external circulating fluidized bed boiler can be obtained.

(1) Even if the particle layer deposited on the stand pipe is low, the particles can be circulated well.

(2) Since no air is introduced into the cold recycle line, the flow of air into the cyclone can be suppressed, and the blower capacity can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a circulation amount control device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional circulation amount control device.

FIG. 3 is a configuration diagram of a circulating fluidized bed boiler to which the circulating amount control device is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Cyclone 3 Stand pipe 4 Seal pot 5 Cold recycle line 6 Hot recycle line 14a-14d Blower 15 Particle extraction tube 16 Particle extraction adjustment valve 23 Pipe

Claims (1)

[Claims] 1. Particles ejected from a combustion chamber of a fluidized-bed boiler are separated from gas by a cyclone, deposited on a standpipe below the gas, and air is sent from a lower part to the combustion chamber from a hot recycling line and a cold recycling line. In the particle circulation amount control device to be recirculated, an angled inclined portion is provided at a lower portion of the stand pipe and connected to the hot recycling line side, and the collected particles are guided to the hot recycling line side, A circulation amount control device, wherein a vertical pipe is attached to the inclined portion and a part of the particles is discharged to the cold recycling line.