JP2000227210A - Circulating fluidized bed furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it unnecessary to decrease the amount of combustion matter to be supplied, even if the combustion matter with a large amount of inorganic portion is supplied, by providing an ash discharging device at the lower part of a cyclone which separates fluid medium and ash from combustion gas to circulate it through the main body of a furnace. SOLUTION: A cyclone 3 separates fluid medium B and ash E from combustion gas D which has passed through a furnace main body 2 to circulate it through the furnace main body 2. The upward side part is connected with the upward side part of the furnace main body 2, and the upper part is connected with heat recovery equipment and flue gas treatment equipment. A loop seal 7 is provided between the lower part of the cyclone 3 and the median side part of the furnace main body 2. An ash discharging device 4 is provided at the lower part of the cyclone 3 to separate the ash E and discharge it, and an extraction pipe 10 is provided at the bottom part of the loop seal 7 in such a manner that it directly communicates with the lower part of the cyclone 3 to extract the part of the fluid medium B and the ash E from the lower part of the cyclone 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, municipal solid waste,
Industrial waste, sludge (sewage sludge, industrial waste sludge), RD
The present invention relates to an improvement in a circulating fluidized bed furnace (including a circulating fluidized bed boiler) used for incinerating combustion products such as F and coal.

[0002]

2. Description of the Related Art Conventionally, as a circulating fluidized bed furnace of this kind,
For example, one described in Japanese Patent Application Laid-Open No. 10-103641 is known. The circulating fluidized bed furnace basically includes a furnace body for fluidizing and burning a combustion material and a fluid medium (circulating medium), and a furnace for separating a fluid medium and ash from combustion gas passing through the furnace body. And a cyclone circulated through the body. In such a case, when ash accumulates on the furnace bottom (the bottom of the furnace body), the movement of the fluidized medium is hindered and the combustion deteriorates. Therefore, an ash discharging device is provided at the bottom of the furnace body. After that, the ash deposited on the bottom of the furnace is extracted together with the flowing medium and separated into the flowing medium and the ash. Then, the flowing medium is returned to the furnace (inside the furnace body, inside the furnace body), and the ash is removed. Was to be discarded.

[0003]

However, such an apparatus is provided with an ash discharging device at the bottom of the furnace body, but when a large amount of ash is generated due to the supply of a combustion substance having a high inorganic content. However, the ash discharging device alone was not enough to process and was insufficient. In addition, ash with a low specific gravity stays in the furnace and is crushed, then discharged from the cyclone along with the combustion gas and sent to the exhaust gas treatment equipment and heat recovery equipment. The particles stay in the furnace and are not discharged out of the furnace until they have a particle size discharged from the cyclone. For this reason, the ash remaining in the furnace hinders the circulation of the fluid medium, so that it is necessary to increase the pressure of the fluid blower and the induction fan in order to maintain proper circulation. However, these pressures were limited and exceeding the capabilities of the blowers and fans required a reduction in the amount of combustion input. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in order to solve the above problem. It is an object of the present invention to provide a circulating fluidized bed furnace which is not necessary and can be operated stably.

[0004]

The circulating fluidized bed furnace of the present invention basically comprises a furnace body for fluidizing and burning a combustion product and a fluidized medium, and a fluidized medium from combustion gas passing through the furnace body. In a circulating fluidized bed furnace having a cyclone for separating ash and circulating the ash to the furnace body, an ash discharging device for separating and discharging ash is provided below the cyclone.

[0005] The combustion material supplied to the furnace body is fluidized together with a fluid medium by combustion air and burned. The combustion gas generated in the furnace body is sent to a cyclone, in which a fluid medium and ash are separated and circulated to the furnace body. The combustion gas separated by the cyclone is sent to an exhaust gas treatment facility and a heat recovery facility. The fluid medium and the ash reaching the lower part of the cyclone are separated into the fluid medium and the ash by the ash discharging device, and the ash is discharged out of the system. The fluid medium separated by the ash discharging device is returned to the inside of the furnace main body. Since the ash discharging device that separates and discharges the ash is provided at the lower part of the cyclone, the ash remaining in the furnace main body is not reduced and the circulation of the fluid medium is not hindered.

[0006] An ash discharging device for separating and discharging ash may be provided on a side portion of the furnace body. In this way, as in the case described above, the ash remaining in the furnace body does not decrease and the circulation of the fluid medium is not hindered.

[0007] The ash discharger may use air for fluidization and separation of the flowing medium and ash. In this case, combustion air can be used. In this case, there is no need to provide a dedicated air supply source, which is reasonable.

[0008] A control device for controlling the ash discharging device based on the pressure under the cyclone may be provided. In this way, the ash discharge can be automatically controlled, and the circulating fluidized bed furnace can be operated stably.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a circulating fluidized bed furnace according to a first example of the present invention. FIG. 2 is an enlarged view of a main part of FIG.

The main part of the circulating fluidized-bed furnace 1 is composed of a furnace body 2, a cyclone 3, and an ash discharging device 4.

The furnace main body 2 fluidizes and burns a combustion material A and a fluid medium (circulating medium) B. In this example, the furnace body 2 has a vertically long cylindrical shape, and the combustion material A is provided on a lower side portion. A supply device 5 for supplying is provided, and an aeration device provided with a wind box and a nozzle (not shown) and an ash discharge device for discharging ash are provided at the bottom. A pushing blower 6 for supplying combustion air C is connected to the air diffuser.
As the fluid medium B, sand such as silica sand is used.

The cyclone 3 separates the fluid medium B and the ash E from the combustion gas D passing through the furnace main body 2 and circulates the ash E through the furnace main body 2. In this example, the upper side is the upper side of the furnace main body 2. And is connected to a heat recovery facility or an exhaust gas treatment facility although the upper part is not shown.

A loop seal 7 is provided between the lower part of the cyclone 3 and the middle side of the furnace body 2. The loop seal 7 is a separation part between the cyclone 3 and the furnace main body 2 and is for returning the fluid medium B and the ash E from the cyclone 3 to the furnace main body 2 while sealing them, and has a partition and an overflow part. It comprises a sealed discharger 8 having a trap structure, and an air diffuser 9 provided with a wind box and a nozzle for fluidizing and separating the fluid medium B and ash E accumulated therein. The push-in blower 6 is connected to the wind box of the air diffuser 9.

The ash discharging device 4 is provided below the cyclone 3 and separates and discharges the ash E. In this example,
An extraction pipe 10 provided at the bottom of the loop seal 7 so as to pass directly through the lower part of the cyclone 3 to extract a part of the fluid medium B and the ash E from the lower part of the cyclone 3, and a partition connected to the lower part of the extraction pipe 10. A sealed discharger 11 having a trap structure for discharging the fluid medium B and the ash E from the cyclone 3 while blocking the outside from the outside with a spill portion, and a wind medium and a nozzle provided at a lower portion thereof. It comprises an air diffuser 12 for fluidizing and separating B and ash E, and a vibrating sieve 13 for classifying the fluid medium B and ash E from the sealed discharger 11. What consists of a sealed discharger 11 and an air diffuser 12
It has the same structure as the loop seal 7.

The air box of the air diffuser 12 includes an air damper 14.
, A combustion blow-in blower 6 and a dedicated compressor are connected, and normal-temperature air is supplied and injected from a nozzle. The injection flow rate may be equal to or higher than the flow start velocity of the fluid medium B. When the fluid medium B is silica sand, the injection velocity is 0.2 to 1.
m / s. The vibrating sieve 13 has a mesh width of about 0.5 to 1
A sieving plate having a diameter of 2 mm is provided and classified into ash E having large particles and a fluid medium B having small particles. The ash E classified by the vibrating sieve 13 is transferred to the silo 16 by the transfer conveyor 15 and stored. The fluid medium B classified by the vibrating sieve 13 is returned to the inside of the furnace main body 2 from the middle side by the circulation conveyor 17.

Next, the operation will be described based on such a configuration. Combustion material A supplied to the furnace main body 2 by the supply device 5
Is fluidized together with the fluid medium B by the combustion air C from the air diffuser provided at the bottom of the furnace body 2 and burned. The fluid medium B and the ash E that flew up while being stirred together with the combustion gas D inside the furnace main body 2 are sent to the cyclone 3 and the fluid medium B and the ash E are separated from the combustion gas D. Fluid medium B and ash E separated in cyclone 3 are:
The furnace body 2 is circulated from below the cyclone 3 through the loop seal 7 to the inside from the middle side of the furnace body 2. The combustion gas D separated by the cyclone 3 is sent from above the cyclone 3 to an exhaust gas treatment facility or a heat recovery facility.

The fluid medium B and a part of the ash E reaching the lower part of the cyclone 3 are withdrawn from the extraction pipe 10 of the ash discharging device 4 and sent to the sealed discharger 11. In the sealed discharger 11, the fluidized medium B and the ash E are fluidized and separated by the air diffuser 12, and are discharged while being sealed as much as they are fed. The fluid medium B and the ash E discharged from the sealed discharger 11 are sent to the vibrating sieve 13 and classified into the fluid medium B and the ash E. The ash E classified by the vibrating sieve 13 is discharged to and stored in the silo 16 by the conveyor 15 and is discharged outside the system. The fluid medium B classified by the vibrating sieve 13 is returned to the inside of the furnace main body 2 from the middle side by the circulation conveyor 17. Since the ash discharging device 4 for discharging the ash E is provided below the cyclone 3, the ash E remaining in the furnace main body 2 does not decrease and the circulation of the fluid medium B is not hindered. As a result, there is no need to reduce the supply amount of the combustion product A,
A predetermined amount of incineration is obtained.

Next, an experimental example will be described. In the circulating fluidized bed furnace 1, the heat input to the furnace was set at 300,000 kcal / h,
Dry sludge having a moisture content of 20%, a combustible content of 40% DS, and a calorific value of 1500 kcal / kg was burned as the combustion product A. Conventionally, when 200 kg / h of the combustion product A is supplied and burned, the pressure difference between the standard furnace lower part and the furnace top part (400 to
600mmH with ₂ O) is 800~1000mmH ₂ O, the pressure fluctuations in the furnace will not be stable combustion beyond ± 50 mm H ₂ O, but had to reduce to less than half the feed rate, the present embodiment Then, the pressure difference between the furnace lower part and the furnace top part was stabilized at 600 mmH ₂ O, and the pressure fluctuation was also stabilized at ± 10 mmH ₂ O, whereby the supply amount of the combustion product A could exceed 200 kg / h. .

Next, a second embodiment of the present invention will be described with reference to FIG. In the second example, an ash discharging device 4 for separating and discharging ash E is provided on a side portion of the furnace body 2. The ash discharge device 4 is provided at a predetermined angle (30 to 40 degrees) on the middle side of the furnace body 2.
Fluid medium B and ash E in the furnace body 2
Pipe 10 for extracting a part of the fluid medium B, which is connected to a lower part of the pipe 10 and has a partition and an overflow portion to shut off the fluid medium B from the outside.
Discharging device 11 having a trap structure for discharging ash E
And an air diffuser 12 provided below and having a wind box and a nozzle for fluidizing and separating fluid medium B and ash E.
And a vibrating sieve 13 for classifying the fluid medium B and the ash E from the sealed discharger 11. An exhaust pipe 18 is provided above the overflow portion of the sealed discharger 11 and connected to the inlet of the combustion push-in blower 6. Therefore, the air that has passed through the fluid medium B is returned to the furnace without leaking out of the system.

In such a case, the combustion gas D
A part of the fluid medium B and the ash E that flew up while being stirred together with the ash is extracted by the extraction pipe 10 of the ash discharging device 4 and sent to the sealed discharger 11. That is, the downflow of the fluid medium B and the ash E is present on the side wall surface of the furnace body 2, and a part of the downflow flows to the extraction pipe 10. In the sealed discharger 11, the fluidized medium B and the ash E are fluidized and separated by the air diffuser 12, and are discharged while being sealed in an amount corresponding to the supplied amount. Fluid medium B and ash E discharged from sealed discharger 11
Is sent to a vibrating sieve 13 and classified into a fluid medium B and ash E. The ash E classified by the vibrating sieve 13 is not shown, but is discharged and stored in a silo by a transport conveyor,
The fluid medium B, which is discharged outside the system and classified by the vibrating sieve 13, is returned to the inside from the middle side of the furnace main body 2 by the circulation conveyor. An ash discharging device 4 for separating and discharging the ash E is provided on the side of the furnace main body 2.
Does not hinder the circulation of the fluid medium B due to the reduction of the ash E remaining in the fluid. As a result, there is no need to reduce the supply amount of the combustion products A, and a predetermined incineration amount can be obtained. Also in this example, when the same experiment as the previous example was performed, the result was not much different from the previous example.

Next, a third embodiment of the present invention will be described with reference to FIG. In the third example, a control device 19 for controlling the ash discharging device 4 based on the pressure under the cyclone 3 is provided. The control device 19 controls the pressure detector 20 for detecting the pressure at the lower portion of the cyclone 3, and controls the air damper 14, the motor of the vibrating sieve 13, the motor of the conveyor 15, and the motor of the circulation conveyor 17 based on the pressure detector 20. And a controller (sequence) 21 for controlling. Controller 2
1 is, when the ash discharging device 4 is started, “transport conveyor / circulation conveyor operation” → “vibration sieve operation” → “air damper open”
In addition, the control is performed in the reverse order of the startup at the time of stop. Further, as the pressure at the bottom of the cyclone 3 activates the ash discharge device 4 by -50mmH ₂ O or more, it is the manner to stop the ash discharge device 4 by -200mmH ₂ O.

Normally, the lower part of the cyclone 3 has a circulating medium
-50 ~ -200mmH _TwoWith a negative pressure of about O
Therefore, monitor this pressure, detect the amount of change, and
You can see the change in the amount of circulation. Pressure is positive
The level of the circulating medium rises to the pressure monitoring level.
-50mmH_TwoAsh discharge equipment at O or higher
Start device 4 and -200mmH_TwoStop at O.
That is, the pressure at the lower part of the cyclone 3 is set to -50 to -200.
mmH_TwoStabilize in the range of O, fuel with a lot of inorganic
Stable operation of a circulating fluidized bed furnace for ceramics
You. This will increase the pressure at the bottom of the furnace,
Ash removal while monitoring the pressure difference (total pressure difference) at the furnace top
Extraction of ash is quicker and more appropriate than when performing
Done. Because the pressure at the bottom of the furnace and the total differential pressure increase
・ If it starts to fluctuate, ash has already accumulated in the furnace,
Extracting ash in a state is slow as a measure, and extracting ash
This is because it was necessary to delay the supply of combustion products.
In this example, the experiment was performed under the same conditions as in the first example.
Differential pressure between lower part and furnace top is 600mmH_TwoO stable and pressure
± 10mmH force fluctuation_TwoO stabilized.

In the above example, the ash discharging device 4 is provided at the lower part of the cyclone 3 and at the side of the furnace main body 2. However, the present invention is not limited to this, and for example, the lower part of the cyclone 3 and the side part of the furnace main body 2 may be provided. May be provided in both. The ash discharge device 4 does not include the exhaust pipe 18 in the first example, and includes the exhaust pipe 18 in the second example. However, the present invention is not limited to this.
8 or the exhaust pipe 18 may be omitted in the second example.

[0024]

As described above, according to the present invention, as described above,
The following excellent effects can be obtained. (1) A circulating fluidized bed furnace including a furnace body for fluidizing and burning a combustion product and a fluid medium, and a cyclone for separating the fluid medium and ash from the combustion gas passing through the furnace body and circulating the ash to the furnace body. In the above, since an ash discharging device for separating and discharging ash was provided at the lower part of the cyclone or at the side of the furnace body,
Even if a combustion product containing a large amount of inorganic substances is supplied, it is not necessary to reduce the supply amount of the combustion product, and stable operation is possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a circulating fluidized bed furnace according to a first example of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an enlarged view of a main part showing a circulating fluidized bed furnace according to a second example of the present invention.

FIG. 4 is a schematic diagram showing a circulating fluidized bed furnace according to a third example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Circulating fluidized bed furnace, 2 ... Furnace main body, 3 ... Cyclone, 4 ...
Ash discharge device, 5 supply device, 6 push-in blower, 7 ...
Loop seal, 8, 11 ... sealed discharger, 9, 12 ... diffuser, 10 ... extraction pipe, 13 ... vibrating sieve, 14 ... air damper, 15 ... transport conveyor, 16 ... silo, 17 ... circulation conveyor, 18 ... Exhaust pipe, 19 ... Control device, 20 ... Pressure detector, 21 ... Controller, A ... Combustion material, B ... Flow medium, C ...
Combustion air, D: Combustion gas, E: Ash.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Munechika Ito 2-2-233 Kinrakuji-cho, Amagasaki City, Hyogo Prefecture Inside of Takuma Co., Ltd. (72) Haruo Nogami 2-233, Kinraku-cho, Amagasaki City, Hyogo Prefecture No. F-term in Takuma Co., Ltd. (reference) 3K064 AB01 AB03 AC13 AD05 AD08 BA07 BA19

Claims (4)

[Claims] 1. A circulating flow comprising: a furnace body for fluidizing and burning a combustion product and a flowing medium; and a cyclone for separating a flowing medium and ash from combustion gas passing through the furnace body and circulating the ash to the furnace body. A circulating fluidized bed furnace, wherein an ash discharging device for separating and discharging ash is provided below the cyclone in the bed furnace. 2. A circulating flow comprising: a furnace body for fluidizing and burning a combustion product and a flowing medium; and a cyclone for separating a flowing medium and ash from combustion gas passing through the furnace body and circulating the ash to the furnace body. A circulating fluidized-bed furnace, wherein an ash discharging device for separating and discharging ash is provided at a side portion of the furnace body in the bed furnace. 3. The circulating fluidized-bed furnace according to claim 1, wherein the ash discharging device uses air for fluidizing and separating the fluid medium and the ash. 4. The circulating fluidized bed furnace according to claim 1, further comprising a control device for controlling the ash discharging device based on the pressure under the cyclone.