JP3016913B2 - Operating method of pressurized fluidized bed combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized fluidized bed combustion apparatus for coal, which drives a gas turbine and a steam turbine to perform combined power generation, and more particularly, to a fluidized bed height control apparatus for coping with load fluctuations. methods relating to the operation of the pressurized fluidized bed combustion equipment.

[0002]

2. Description of the Related Art In a pressurized fluidized bed combustion furnace, the height of a fluidized bed is increased or decreased to cope with a change in load. That is, for a decrease in the load, the fluid medium in the combustion furnace is extracted from the furnace and stored in a separate medium container. Conversely, for an increase in the load, the fluid medium is removed from the medium container. It is supplied into the furnace deeply buried depth of the heat transfer tubes, increasing the amount of steam generated by increasing the heat transfer area
It is.

Conventionally, for example, in Japanese Patent Application Laid-Open No. 1-217108, in order to extract a fluid medium from a furnace into a medium container, one end is opened to the bottom of a fluidized bed combustion furnace and the other end is opened to the combustion furnace space. A suction pipe for the medium that penetrates the tower and opens to the dust separator above the medium vessel is provided to connect the fluidized bed combustion furnace to the medium vessel. The means connected to the outer space of the pressure vessel via a conduit having a valve is shown.

In the above means, by adjusting and opening the valve of the conduit connecting the storage container and the external space, the pressure in the storage container becomes lower than that in the combustion furnace, and the gas in the combustion furnace passes through the suction conduit. At the same time, the fluid medium is extracted into the in-furnace medium container.

[0005]

However, according to the above prior art, the flowing medium is melted in the medium container.
The problem of agglomeration has occurred.
This is because the fluidized medium flows back into the storage vessel with a gas with high oxygen concentration and unburned coal particles from a conduit provided at the lower part of the medium vessel provided for supplying the fluidized medium to the combustion furnace, and the unburned coal particles It is presumed that the adiabatic fuel was burned adiabatically in the state of being stored in the container, the temperature was excessively raised, and the flowing medium was melted.

Also, it is difficult to quantitatively extract the medium particles in the combustion furnace by adjusting the valve of the conduit because the pressure in the combustion furnace and the medium container is as high as 10 kg / cm ² . Further, when increasing the load, that is, when transferring the medium particles from the medium container to the fluidized bed combustion furnace, since the temperature of the medium particles is lower than the particle temperature in the fluidized bed combustion furnace, the predetermined medium particle flow rate is reduced. The transfer causes a problem that the temperature of the fluidized bed combustion furnace is significantly reduced.

[0007] The flow rate of the medium particles must be supplied in accordance with the load change speed, and the speed is as large as 4 to 5% / min. For example, when the load change is 50%, the load change is performed in about 12 minutes. . Therefore, when the temperature of the particles in the medium container is slightly lower than that of the fluidized bed combustion furnace, the temperature of the fluidized bed combustion furnace decreases. When the temperature in the furnace decreases, not only the property of the combustion exhaust gas cannot maintain a predetermined value, but also toxic gas (CO, SO ₂ , NH _3, etc.) is generated.

In particular, the optimum temperature condition for the desulfurization reaction is 83
The temperature is limited to 0 to 870 ° C., and outside this range, the desulfurization rate is remarkably reduced, and a large amount of SO ₂ is generated. Further, there is a problem that the unburned loss from the furnace also increases, and a predetermined steam generation amount cannot be obtained.

In the prior art, the temperature inside the medium container is high (8
(00 ° C. or more) and high pressure (10 atm or more), the medium level of the medium container cannot be detected, so that the amount of the fluidized bed medium held cannot be determined, and troubles such as loss and overfill of the fluidized bed medium often occur. When the medium in the medium container is deficient, the medium particles in the fluidized bed combustion furnace flow into the medium container, causing not only a clinker trouble in the medium container but also a failure in load control itself.

Further, when the medium particles in the medium container overflow, problems such as blockage of the transport pipe due to the medium particles occur. To solve these problems, in the related art, there is a method of installing a plurality of thermometers in a medium container and detecting a particle level from a temperature difference between the medium particles and the gas.

However, this method can measure while the medium is moving, but when the particles in the medium container are stopped, the temperature of the gas and the particles becomes uniform, and the detection of the particle level is performed. Becomes impossible. Generally, when the load is maintained at a predetermined value, a long-time operation is often performed under that condition, so that the particles in the medium container do not move, so that a phenomenon occurs in which the temperature difference between the particles and the gas disappears. . Furthermore, since the particles in the medium container are completely stopped at a constant load,
There is also the problem of clinker formation of particles in the media container.

The present invention solves the above-mentioned drawbacks of the prior art, cancels clinker generation of particles in the medium container, continuously detects the particle level in the medium container, and further moves the medium container to the fluidized bed combustion furnace. Operation of a pressurized fluidized bed combustion system equipped with a fluidized bed height control device that can maintain the temperature of the fluidized bed combustion furnace constant during transfer of medium particles and satisfactorily adjust the exhaust gas properties when the load changes. It is intended to provide a method .

[0013]

In order to achieve the above object,
Therefore, the first invention has a fluidized bed in which a heat transfer tube is buried.
A fluidized bed combustion furnace, a medium container for storing a fluidized medium,
Withdraw the fluidized medium from the fluidized bed combustion furnace and place it in the medium container
Fluidized bed combustion from medium container to transfer medium extraction medium container
Medium return means for returning the flowing medium to the furnace;
It has a fluidized bed combustion furnace and a pressure vessel for containing the medium vessel.
And a medium flowing into a medium container by the medium extracting means.
To the fluidized bed combustion furnace by the medium return means
The height of the fluidized bed in the fluidized bed combustion furnace
Operation of pressurized fluidized-bed boiler adjusted to cope with load fluctuation
In law, the height direction of the medium container to the side wall of the medium container
A plurality of differential pressure gauges are provided along the
Enables continuous detection of the particle level of the fluid medium in the container
Of the fluidized medium between the fluidized bed furnace and the medium vessel
It is characterized in that the ring is always continuously performed.
In order to achieve the above object, a second aspect of the present invention is to embed a heat transfer tube.
Fluidized bed combustion furnace with submerged fluidized bed and its fluidized bed combustion
High temperature inside the container that stores the fluid medium extracted from the furnace
Medium container and withdrawing the fluidized medium from the fluidized bed combustion furnace
Medium extracting means for transferring the medium to the medium container, and a medium
Medium return to return fluidized medium directly from vessel to fluidized bed furnace
Means, at least the fluidized bed combustion furnace and the medium container
And a pressure vessel for accommodating, in the medium withdrawal means
Withdrawing the flowing medium into the medium container and returning the medium
Return of the fluidized medium to the fluidized bed furnace by
Adjusting the fluidized bed height in a moving bed combustion furnace to respond to load fluctuations
Method of operating a pressurized Doso boiler, even when a constant load
Withdrawing the flowing medium by the medium extracting means;
The return of the fluidized medium by the medium return means is performed by a fluidized bed combustion furnace.
And the media container at all times, and a fluidized bed combustion furnace
Make sure that the temperature difference between the particles in the medium container does not exceed a predetermined value.
Is designed to regulate the circulation amount of the fluid medium.
It is characterized by the following.

[0014]

The particle temperature in the medium vessel is kept substantially the same as the particle temperature in the fluidized bed combustion furnace by continuously circulating particles between the fluidized bed combustion furnace and the medium vessel even during steady operation with a constant load. be able to. Therefore, when the particles in the medium vessel are returned to the fluidized bed in order to increase the load, the temperature difference between the fluidized bed combustion furnace and the medium vessel is small, so that the temperature of the fluidized bed combustion furnace does not decrease.

Furthermore, since the particles in the medium container are constantly moving during the steady operation, there is no local overheating and no clinker of the particles is generated. Further, by constantly moving the medium particles in the medium container, a differential pressure proportional to the particle layer level in the medium container is generated above and below the container, and the pressure difference is measured by two or more pairs of differential pressure gauges installed in the medium container. Thus, the particle level in the medium container can be continuously detected.

[0016]

FIG. 1 shows an embodiment of the present invention. The fluidized bed combustion furnace 1, the medium container 11, the cyclone 41, and the medium transport pipe and equipment according to the present invention are housed in a pressure container 101.
The fluidized bed combustion furnace 1 is provided at its bottom with a dispersion plate 2 of combustion air 8, on which a fluidized medium (particles) 3 is filled. The fluidized medium 3 generates bubbles 7 by the combustion air 8 supplied through the dispersion plate 2 to form a fluidized bed 5. The coal 10 is supplied into the fluidized bed 5 by the coal feed pipe 9 and burned. Heat transfer tubes 4 are arranged in the fluidized bed 5 and absorb the heat of combustion to generate steam.

A moving bed downcomer 21 is provided at the bottom of the side wall of the fluidized bed combustion furnace 1 so as to open. The moving bed downcomer 21 extends vertically from an inclined state to become an L valve 22.
The air valve 19 is supplied to the L valve 22 through the valve 20. Further, the air flow transport pipe 2 is connected from the L valve 22 to the empty tower 13 of the medium container 11.
3 is connected, and a control valve 2 is connected from a lower end thereof.
Airflow transport gas 24 is supplied through 5.

The lower end of the medium container 11 is conically narrowed to form a moving bed tube 14 and an L valve 15, which is opened and connected to the lower part of the side wall of the fluidized bed combustion furnace 1.
An air rate gas 17 is supplied to the L valve 15 with a flow rate adjusted by a control valve 18. Medium container 1
1 is a fluidized bed medium 1 extracted from a fluidized bed combustion furnace 1
2 are accumulated. The side wall of the medium container 11 is shown in the figure.
The pressure measuring seat 28 along the height direction of the medium container 11
29 and pressure gauges 30, 31 are installed.

Signals from the pressure gauges 30 and 31 are guided to an arithmetic unit 34 for calculating the particle level in the medium container 11 and a control box 35 for operating a control valve. Further, the signal of the control box 35 is transmitted to the valve 37 of the particle extraction tube 26 provided below the L valve 15 and the empty column 13 of the medium container 11.
Is connected to a flow control valve 36 of a limestone or fluid medium hopper installed in the hopper.

The combustion furnace empty tower section 6 and the medium vessel empty tower section 13 are
It is connected by a conduit 33 provided with a valve 32. Further, a cyclone 41 is connected to the combustion furnace empty tower section 6, and fine particles in the combustion gas are removed and supplied as a clean gas 44 to a gas turbine in the next step. The separated fine particles are discharged out of the system through the conduit 42.

In the above apparatus, the pressure of the combustion furnace 1 is 1
A range of 0 to 20 atm, a combustion temperature of 800 to 900 ° C, and a superficial gas velocity of the combustion furnace of 0.5 to 1.5 m / s are employed. Limestone particles having a maximum diameter of about 3 mm are used as the fluidized medium and the in-bed desulfurizing agent. The control of the steam generation amount can be performed as follows.

For example, when the fluidized bed is at a height at which all the heat transfer tubes 4 are buried, the fluidized medium 3 is moved from the moving bed downcomer 2
1, the medium container 1 through the L valve 22 and the airflow pipe 23
1 and the height of the fluidized bed in the combustion furnace is 5 '
, A part of the heat transfer tube group 4 is exposed from the fluidized bed 5 ′, the heat transfer area buried in the fluidized bed 3 is reduced, and the steam generation amount can be reduced.

Conversely, from the state where the fluidized bed in the combustion furnace 1 is 5 ', the fluidized medium 12 in the medium vessel 11 is moved to the moving bed tube 14,
By returning the heat transfer tubes 4 to the fluidized bed to a certain level by returning the heat transfer tubes 4 to the fluidized bed combustion furnace 1 through the L valve 15 and increasing the heat transfer area, the amount of generated steam is increased as desired. be able to.

The load is changed as described above. According to the present invention, particularly when the load is increased by increasing the height of the fluidized bed of the furnace, stable bed temperature control becomes possible and load control becomes easy. Become. That is, by performing the particle circulation even at a constant load, the particle temperature in the medium container can be maintained without lowering than the particle temperature in the furnace. This can be easily achieved by circulating the particles between the fluidized bed combustion furnace and the medium vessel using the L valves 22, 15 and the air flow transport pipe 23 at a constant load.

When the medium particles are transferred into the furnace while the temperature of the medium particles is lower than that in the furnace, the fluidized bed combustion furnace 1
The temperature of the particles inside drops sharply. In order not to lower the particle temperature in the fluidized bed combustion furnace 1, an operation in which the amount of particles transferred from the inside of the medium container is significantly reduced is performed. This causes a problem that the load change speed cannot maintain a desired value. Therefore, the medium container 11 and the fluidized bed combustion furnace
By performing the particle circulation between 1, without reducing the temperature of the fluidized bed combustion furnace 1, it corresponds to the time of load change.

The amount of circulating particles at this time is adjusted so that the temperature difference between the particles in the fluidized-bed combustion furnace 1 and the medium container does not exceed 40 ° C., whereby stable load control can be achieved when the load changes. . In actual operation, the particle circulation amount is controlled while detecting the particle temperature in the medium container 11, but the particle temperature in the medium container can be maintained with a smaller particle circulation amount than when the load changes.

Further, since the particles are constantly circulated, continuous detection of the particle level in the medium container can be performed by the differential pressure gauge provided on the side wall in the medium container 11. Medium container 11
There is a feature that the particle level detection inside can be detected continuously regardless of the circulation amount of the particles.

In the operation of the pressurized fluidized bed combustion furnace, it is necessary to keep the particle level in the medium container at a predetermined level at all times. As the particle level increases, the particles overflow the media container, causing clogging of the transport tube and the like. On the other hand, when the particle level decreases, the load cannot be changed because particles are not supplied into the fluidized bed combustion furnace. Whether or not the media particles are balanced in a pressurized fluidized bed combustion furnace has characteristics that differ significantly depending on the properties of the fuel.

In general, when coal is used as a fuel, the balance of the medium particles is determined by the ash content, the fuel ratio, the S content and the like in the coal. For example, coal having a large amount of ash and S tends to increase the amount of medium particles, and conversely, coal having a small amount of ash and S has a characteristic that the medium particles decrease.

Therefore, in the former case, the medium particles are extracted from the system, and in the latter case, an operation of supplying the medium particles (limestone, fluidized sand, etc.) into the system is required.
Although particle balance conceptually tends to be as described above,
Quantitatively relying on the actual operation in many cases, it is important to detect the particle level in the medium container. In the drawing, 27 is a particle supply pipe, 33 is a conduit, and 38 and 39 are media.

[0031]

As described above, according to the present invention,
Since the particle level in the fluidized bed combustion furnace can be continuously detected when the load changes, the clinker trouble in the medium container can be eliminated, and stable and reliable load control can be performed.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing an embodiment of a pressurized fluidized bed combustion furnace of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluidized bed combustion furnace 2 Dispersion plate 3 Fluidized bed 4 Heat transfer tube 5 Fluidized bed height 6 Combustion furnace empty tower 7 Bubbles 8 Combustion air 9 Coal supply pipe 10 Coal 11 Medium container 12 Medium 13 Empty tower 14 Moving bed pipe 15 L valve 17 Air rate gas 18 Control valve 19 Air rate gas 20 Control valve

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Taro Sakata 6-9 Takara-cho, Kure-shi, Hiroshima Pref. Inside the Kure Plant Co., Ltd. (72) Inventor Kodai Nonaka 6-9 Takara-cho, Kure-shi, Hiroshima Pref. (72) Inventor Akio Nishiyama 6-9 Takara-cho, Kure-shi, Hiroshima Babkotsukitsu Kure Factory (56) References JP-A-56-64212 (JP, A) JP-A-62 -94705 (JP, A) JP-A-59-225209 (JP, A) JP-A-2-1000031 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F22B 1/02 F23C 10/16 F23C 10/28

Claims (3)

(57) [Claims] 1. A fluidized bed having a fluidized bed in which a heat transfer tube is buried.
A combustion furnace, a medium container for storing a fluidized medium, and the fluidized bed
Withdrawing the flowing medium from the combustion furnace and transferring it to the medium container
Media extraction means, and flow from the media container to the fluidized bed combustion furnace.
Medium return means for returning a moving medium, and at least the flow
A bed combustion furnace and a pressure vessel for accommodating the medium container, wherein the medium withdrawing means removes the flowing medium to the medium container.
And the flow to the fluidized bed combustion furnace by the medium return means.
Adjusting the height of the fluidized bed in the fluidized bed combustion furnace by returning the moving medium
Operating method of pressurized fluidized bed boiler corresponding to load fluctuation
In this case, a plurality of media containers are provided on the side wall of the media container along the height direction of the media container.
Differential pressure gauge, and the flow in the media container
Flow to enable continuous detection of media particle levels
Continuous circulation of fluidized medium between the bed combustion furnace and the medium vessel
Of a pressurized fluidized bed combustion device characterized by performing
Method. 2. A fluidized bed having a fluidized bed in which a heat transfer tube is buried.
Combustion furnace and fluidized medium extracted from the fluidized bed combustion furnace
A medium container having a high-temperature state in the container to be stored;
Withdraw the fluidized medium from the furnace and transfer it to the medium container
Flow from the medium container to the fluidized bed combustion furnace
Medium return means for directly returning the medium;
It has a moving bed combustion furnace and a pressure vessel for containing the medium vessel.
And extracting the fluid medium into the medium container by the medium extracting means.
And the flow to the fluidized bed combustion furnace by the medium return means.
Adjusting the height of the fluidized bed in the fluidized bed combustion furnace by returning the moving medium
Operating method of pressurized fluidized bed boiler corresponding to load fluctuation
Here, even at a constant load , the flow of the flowing medium by the medium extracting means is performed.
Extraction and return of the fluid medium by the medium return means
Is always and continuously performed between the fluidized bed combustion furnace and the medium container.
The temperature difference between the particles in the fluidized bed combustion furnace and the
Adjust the circulation amount of the fluid medium so that
Pressurized fluidized bed combustion apparatus characterized in that
Driving method. 3. The method according to claim 2 , wherein
Pressurized flow characterized in that the upper limit of the temperature difference is 40 ° C.
The operation method of the moving bed combustion device.