JP2000266315A - Controller and controlling method for fluidized bed boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for recovering a good satisfactory state by detecting faulty fluidity of a medium caused by a low melting point compound produced through reaction of ash in fuel and limestone as a fluidity medium, in the early stage. SOLUTION: In this control method for a fluidized bed boiler comprising a fluidized bed 6 for combusting a fossil fuel supplied from a fuel supply mean 4, means 3 for supplying the fluidized bed with fluidizing/combusting air, and means 21 for extracting the ] medium from the fluidized bed, local incomplete fluidity at the lower part of the fluidized bed is detected by means for detecting the gas pressure loss in the height direction of the fluidized bed or the temperature at a plurality of points at the lower part of the fluidized bed. The fluidizing medium is then added to recover the fluid state and the ascending bed height is kept within a predetermined range by withdrawing the rough granular fluidizing medium from faulty fluidity part.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling a fluidized-bed boiler, and more particularly to a method for optimizing the properties of a fluidized medium in a fluidized bed to prevent a fluidized state and a combustion state from deteriorating. The present invention relates to a fluidized bed boiler control method and apparatus for reducing harmful components in the fluidized bed and keeping the fluidized bed temperature within a set value.

[0001]

2. Description of the Related Art In recent years, emission control of environmental pollutants has become stricter as a global environmental problem. Research and development of thermal power generation, which burns fossil fuels to generate power, has been conducted to improve environmental performance and power generation efficiency. Among them, attention has been focused on power generation by a pressurized fluidized bed boiler in which a boiler is placed in a pressure vessel to burn coal by pressurization and generate power.

In a pressurized fluidized bed boiler, power generation efficiency is improved by combined power generation using a gas turbine and a steam turbine, and desulfurization equipment is omitted by performing in-furnace desulfurization using limestone forming a fluidized bed. There is a merit that combustion can be performed at a relatively low temperature and that the NOx (nitrogen oxide) concentration at the outlet of the fluidized bed can be reduced by a reduction reaction with a reducing substance such as carbon in the fluidized bed. However, in the prior art, when a new fluidized medium (BM) is used (during a trial run of a new plant, etc.), a high concentration of NOx is emitted for a long time until sulfurization is completed. Problems could arise.

FIG. 10 shows a conventional pressurized fluidized bed boiler system. Combustion air 55 introduced by the compressor 12 is introduced into the fluidized-bed boiler 2 in the pressure vessel 1 through the furnace inlet pipe 18, and a paste fuel (Coal Wat) composed of coal, water and in-furnace desulfurization limestone.
er Paste (hereinafter, referred to as CWP).

On the other hand, CWP is a pulverized coal slurry supplied from a pulverized coal slurry (mixture of pulverized coal and water) 125,
And limestone for in-furnace desulfurization supplied from a limestone hopper 123, stirred with water by a kneader 122, stored in a CWP tank 121, and stored in a CWP pump 121.
0 discharges through a CWP supply nozzle 119 into a fluidized medium forming a fluidized bed.

The exhaust gas generated by the combustion is introduced into the gas turbine 13 through the furnace outlet pipe 9, and generates electric power by a generator connected to the turbine, and at the same time, serves as a driving source of the compressor 12. Exhaust gas leaving the gas turbine 13 has a high gas temperature of about 400 ° C.
After the heat recovery by 10, it is discharged from the chimney 16.

In the pressurized fluidized bed boiler system, NO
The device for reducing x is sprayed by a non-catalytic denitration device that performs denitration by ammonia sprayed from an ammonia injection nozzle 118 sent into a furnace outlet pipe 9 and an ammonia injection nozzle 113 provided in a economizer 110. It is only a catalytic denitration device that performs denitration by using ammonia and a denitration catalyst 111, and thereby reduces NOx in exhaust gas at the chimney inlet to an environmental regulation value or less.

In a conventional fluidized bed combustion apparatus, a bed is formed of silica sand, limestone, or the like, and fuel is supplied to the bed fluidized with a supporting gas or the like. If the bed is maintained at or above the ignition temperature of the fuel, the fuel will burn mainly in the fluidized bed and the temperature of the fluidized bed can be maintained. When a fossil fuel such as coal is burned by such a fluidized bed combustion device, a part of non-combustible components (eg, ash in coal) contained in the fuel accumulates in the fluidized bed. Further, particles initially filled for forming a layer are crushed and worn by the flow of the layer. Therefore, the particle size distribution of the fluid medium changes over time. In particular, when coarse particles are contained in the non-combustible component in the fuel or when the non-combustible component and the fluidized medium generate coarse particles, the coarse particles that do not flow under normal operating conditions increase with time. There was a problem of doing.

FIG. 11 shows a conventional fluid medium supply / replenishment device for supplying / replenishing a fluid medium to a furnace fluidized bed. Normal,
Limestone that forms a fluidized bed and also functions as a desulfurizing agent is used as the fluidized medium. The fluid medium is filled into the fluid medium tank 210 from the fluid medium bunker 201 by the fluid medium transport blower 202 via the fluid medium transport pipe 203 and the fluid medium replenishing hopper 207 during the initial filling of the fluidized bed. The fluidized medium is supplied from the fluidized medium tank 210 to the fluidized-bed boiler 2 by the fluidized medium supply line 212 to form a fluidized bed. During operation, when the scattering amount increases due to fluctuations in load or the like and the bed height cannot be maintained, the fluid medium is quickly supplied to the furnace 2 from the fluid medium replenishing hopper 207 via the fluid medium tank 210, and the bed height is increased. To maintain.

The fluid medium is supplied to the kneading machine 122 through a supply pipe 216, and is kneaded with the coal supplied from the coal supply line 25 and the water from the water supply line 218, thereby forming a CWP (Coal Water Paste).
Is injected into the fluidized bed combustion device 2 as fuel.
However, the conventional fluid medium supply / replenishment device can maintain the bed height in the short term when the powdered medium of the fluid medium to be replenished has a high powdering property, but the fluid medium to be replenished is immediately scattered. Can't respond. In addition, scattering of limestone as a fluid medium is necessary to some extent for increasing the ash particle diameter at the furnace exit from desulfurization performance and dust removal, and when the fluidized medium with low powderability has too little scattered fluid medium Cannot take appropriate measures to improve the fluid medium scattering property.

When the limestone has low powderability, it is necessary to increase the amount of supplied limestone in order to increase the amount of limestone effective for desulfurization. However, in this case, the bed height rises due to limestone that is not powdered, and it is necessary to extract limestone from the fluidized bed in order to maintain the bed height, and limestone is wasted. That is, in the conventional fluid medium supply / replenishment device, no consideration has been given to desulfurization and an increase in the ash particle size at the furnace outlet.

FIG. 12 shows the concept of a boiler furnace to which the temperature control device for a boiler according to the present invention is applied. The fuel 51 is injected into the fluidized bed 6 of the boiler furnace 2 by the nozzle 119, and reacts with oxygen in the combustion and fluidization air supplied through the dispersion plate 5 to generate reaction heat. The reaction heat is absorbed by the heat transfer tube bundle 17 installed in the fluidized bed 6, and in a static state, the reaction heat and the absorption heat balance with the sensible heat brought in by the fluidized air or the sensible heat taken out of the combustion gas. The temperature and bed temperature of the fluidized bed 6 are determined at this balance point.
It is necessary to maintain the temperature and bed temperature of the fluidized bed 6 at about 860 ° C. from the viewpoint of suppressing emissions or protecting the heat transfer tube structural material.
When the temperature rises above 0 ° C., the flow rate of the fuel 1 decreases, and when the bed temperature falls below the set value, the flow rate of the fuel 1 increases.

As described above, Japanese Patent Application Laid-Open No. 05-180402 (bed temperature control device for fluidized-bed boiler) and Japanese Patent Application Laid-Open No. JP-A-59-001913 (a method for controlling a fuel flow rate of a combustion furnace having a fluidized bed) is known. However, in these methods, a bed temperature measurement value at a specific location in the fluidized bed is adopted as a bed temperature to be compared with a set value and to follow the set value.
In this case, since the heat transfer tube bundles are dense, it is not always possible to set a sufficient number of layer temperature measurement points, or when the heat transfer tube bundles are so dense that fuel mixing or heat transfer is easily hindered. Is the bed temperature indicated by the measured value at a specific location represents the average value of the bed temperature over the entire fluidized bed area,
There is no guarantee.

Therefore, Japanese Patent Application Laid-Open No. 6-257715 (fuel flow control device for pressurized fluidized bed boiler)
Incorporating a physical model of combustion in the control device, so that the distribution of calculated output values by the model is uniform inside the fluidized bed,
The fuel flow from the plurality of fuel nozzles is individually controlled.
At this time, various constant values included in the fluidized bed are tuned from time to time so as to match the measured bed temperature values at a plurality of points in the fluidized bed with the corresponding output values of the combustion model. The output value will be used for control. However, this model is a model that gives a three-dimensional distribution in a fluidized bed of combustion, and takes the mixed diffusion coefficient of particles in the depth, height and width directions of the furnace as a constant to be tuned. Therefore, the physical inverse combustion model becomes a trial and error problem, and when the number of times of convergence increases, it may be difficult to control the fuel flow rate in real time.

[0014]

A first problem to be solved by the present invention is to detect a local flow defect due to an increase in coarse particles in a fluidized bed combustion apparatus at an early stage during operation, and The purpose is to maintain stable operation for a long time while taking measures to recover the condition. By the way, in the prior art shown in FIG. 10, the fluid medium forming the fluidized bed is limestone, and CaCO ₃ in the limestone component is thermally decomposed (decarbonated) at normal pressure to generate CaO. In this case, no CaO generation reaction occurs. CaO has a high catalytic action, and under a condition where the bed temperature is high and the furnace pressure is low, such as in a start-up process of a fluidized bed boiler, a large amount of CaO is generated in a new fluidized medium in which CaCO ₃ occupies most of components in the fluidized medium. NOx generation reaction by the catalytic action of CaO

[0015]

Embedded image Reduction reaction of NO 3 with NH ₃ + 5 / 4O ₂ → NO + 3 / 2H ₂ O

[0016]

## STR2 ## NO → 1 / 2N ₂ + 1 / 2O ₂ is simultaneously promoted. However, since the NOx formation reaction rate is much higher than the reduction reaction rate, a new (before sulfidation) fluid medium containing a large amount of CaO is used. If used, NOx will increase as a result.

On the other hand, the fluidized medium functions as a desulfurizing agent for reducing sulfur oxides (hereinafter referred to as SOx) generated from sulfur contained in coal in CWP, but the mechanism of desulfurization in the pressurized fluidized bed is based on the limestone component. CaCO ₃ reacts directly with SOx. For this reason, it is necessary to reduce CaO, which is a catalyst substance that causes an increase in NOx, at an early stage. However, the above-mentioned conventional technology reduces NOx in exhaust gas by a non-catalytic denitration device and a catalytic denitration device, and is below the environmental regulation value. Since the gas is discharged from the chimney in a low load zone where the gas temperature is low, there is a limit to the denitration performance, and operation using a new fluid medium (during trial operation of a new plant, etc.)
In the above, there was a possibility that the environmental regulation value could not be kept against NOx increasing due to the above reasons.

A second object of the present invention is to eliminate the above problems and to reduce NOx by accelerating the reduction of CaO as a catalyst substance at an early stage. In the prior art shown in FIG. 11, the function of stabilizing the properties of carbon in view of maintaining bed height, desulfurization performance, and increasing the ash particle size at the furnace outlet and reducing the amount of BM (fluid medium) used are taken into consideration. It is not possible to supply and replenish the fluid medium to maintain the bed height and maintain the desulfurization property and the dedusting performance of the downstream dust remover, so it cannot be expected to promptly stabilize the fluidized bed. There's a problem.

[0019] A third object of the present invention is to eliminate the above-mentioned problems, to maintain the bed height during operation, to improve desulfurization performance, to stabilize dust removal performance, and to reduce the amount of fluidized medium used rapidly. An object of the present invention is to provide a fluid medium replenishing device capable of supplying and replenishing a medium. Further, in the prior art shown in FIG. 12, a bed temperature measured value at a specific location in a fluidized bed is adopted as a bed temperature to be compared with a set value and to be followed. In this case, since the heat transfer tube bundles are dense, it is not always possible to set a sufficient number of bed temperature measurement points. When the heat transfer tube bundle is dense and the fuel mixing or heat transfer is likely to be hindered, the bed temperature indicated by the measured value at a specific location is the average value of the bed temperature over the entire area of the fluidized bed. Representing,
There is no guarantee. This situation is not remarkable when the fuel is sufficiently mixed in the stationary state and the heat transfer is also performed steadily. However, when the load is changed, the fuel amount is also changed. In this case, for example, the temporal change of the bed temperature differs depending on whether it is near or far from the fuel nozzle. It is not clear whether to represent the average value or to take the bed temperature measurement at a point far from the fuel nozzle.

Therefore, it is not necessary to perform an excessive over / under operation to focus on the layer temperature measured value at a point where the response is expected to be fast and follow the set value. If the bed temperature does not respond easily, and if a point far from the fuel nozzle has a slow response as a representative, excessive over / under operation occurs, and near the fuel nozzle,
For example, there is a possibility that a layer temperature excessive rise that may cause damage to the structural material may occur. In order to avoid this, it was not quantitatively clear how to average the layer temperature measurements installed in each area of the furnace and what weighting should be applied.

A fourth object of the present invention is to solve the above-mentioned problem and estimate how a bed temperature value to be made to follow a bed temperature set value is calculated as a weighted average of bed temperature measurement values at each point. An object of the present invention is to provide a boiler temperature control device capable of quantifying power to be applied without complicated calculations.

[0022]

SUMMARY OF THE INVENTION In order to solve the above-mentioned first problem, the present invention monitors the flow state, particularly the flow state in the lower part of a fluidized bed in which coarse particles are liable to accumulate, and detects signs of flow deterioration. A medium having a particle size that can be normally fluidized when detected is positively supplied to the fluidized bed. As a result, the height of the fluidized bed increases,
The fluid medium is withdrawn from the vicinity of the bottom of the fluidized bed in which it is most likely that coarse particles can be withdrawn so as to maintain a predetermined bed height. The supply and withdrawal of the fluid medium is continued or intermittently repeated until the fluid state returns to the initial good fluid state. In the present invention, in order to solve the second problem, in a pressurized fluidized-bed boiler, when a new fluidized medium is used, a sulfur component is mixed into fuel supplied to the fluidized bed, and calcium oxide in the fluidized medium is removed. Promotes the sulfurization of nitrogen, thereby suppressing an increase in nitrogen oxides.

In the present invention, in order to solve the third problem, during the operation of the pressurized fluidized-bed boiler, a large-diameter fluidized medium having a particle size equal to or larger than the scattered particle size is provided. By independently supplying and replenishing two types of small-diameter fluidized media having a particle size, the particle size of the fluidized media in the fuel to be introduced into the boiler furnace is adjusted, or supplied to the boiler furnace fluidized bed. Adjust the particle size of the flowing medium.

In order to solve the fourth problem, the degree of heat transfer in the fluidized bed is estimated on the basis of at least two or more measured bed temperatures, and the temperature of the fluidized bed is adjusted accordingly. What is necessary is just to calculate a volume average value. For example, the fuel flow rate is controlled so that the volume average value of the bed temperature follows the bed temperature set value,
It should be adjusted. This makes it possible to appropriately set the bed temperature representative of the fluidized bed even when the fuel mixing is poor and the bed temperature deviation in the furnace fluidized bed is large, especially when the load changes. Even when the bed temperature distribution is obtained, the bed temperature control does not focus on only a specific point in the fluidized bed, and the entire area of the fluidized bed can be more appropriately maintained at the set temperature. That is, even when the load changes, the thermal balance does not significantly deteriorate.

That is, the invention claimed in the present application is as follows. (1) Fluidized bed for burning fossil fuel, means for supplying a supporting gas for burning the fuel to the fluidized bed, means for supplying a fluidized medium to the fluidized bed, and fluidized medium from the fluidized bed A fluidized-bed boiler control method comprising the steps of: monitoring a local fluidized state at a lower portion of the fluidized bed, and adding a fluidized medium to recover the fluidized state when the fluidized state deteriorates. As a result, a fluidized-bed boiler control method characterized by maintaining a rising bed height in a predetermined range by extracting a fluidized medium from a lower portion of the fluidized bed.

(2) The method for controlling a fluidized bed boiler according to the above (1), wherein the local fluidized state of the lower part of the fluidized bed is detected by a local gas pressure loss in the height direction of the fluidized bed. Characteristic control method of fluidized bed boiler. (3) The method for controlling a fluidized-bed boiler according to the above (1), wherein a local fluidized state of the lower part of the fluidized bed is detected at a plurality of positions in the lower part of the fluidized bed. Method.

(4) A fluidized bed for burning a fossil fuel, a means for burning the fuel and supplying gas for flowing the fluidized bed, and a means for supplying a new fluidized medium to the fluidized bed. In the fluidized bed boiler control device, when the new fluidized medium is used, a sulfur component is mixed into the fluidized bed to accelerate the sulfidation of calcium oxide in the new fluidized medium and increase nitrogen oxides in the exhaust gas. A control device for a fluidized-bed boiler, characterized by comprising means for suppressing the occurrence of turbidity.

(5) A fluidized bed for burning the fuel, means for supplying the fluidized bed with gas for burning the fuel and fluidizing the fluidized bed, and supplying a fluidized medium to the fluidized bed. A replenishing means for adjusting the bed height and desulfurization performance of the fluidized bed, wherein the fluid medium supply / replenishing means comprises two types of fluidized media having different particle diameters or different types of fluidized media. A fluidized-bed boiler control device formed for each type of fluidized medium.

(6) In the control apparatus for a fluidized-bed boiler according to (5), one of the fluid medium supply / replenishment means is a coarse fluid medium having a scattered particle diameter or more with respect to the superficial velocity. Limestone or other means for supplying and replenishing a fluid medium such as silica stone and alumina, and supplying and supplying another type of fluid medium containing limestone having a particle diameter equal to or less than the above-mentioned dispersed particle size.
A control device for a fluidized-bed boiler, wherein the control device is a replenishing means.

(7) In the control apparatus for a fluidized-bed boiler according to the above (6), the superficial superficial velocity is approximately 1 m / s,
The means for supplying and replenishing the above two types of fluid mediums is 0.3 to 3
A control apparatus for a fluidized bed boiler, comprising means for supplying and replenishing coarse limestone having a particle size range of 0.3 mm and fine limestone having a particle size range of 0.3 mm or less.

(8) In the control apparatus for a fluidized-bed boiler according to any one of the above (5) to (7), a bunker for a fluid medium having a large particle size and a bunker for a fluid medium having a small particle size are provided. Means for kneading the fluid medium taken out of the bunker in normal times with fuel and water and supplying the fluid medium to the fluidized bed as means for supplying and replenishing the fluid medium, and the fluid medium during short-term fluctuations including load changes. A control apparatus for a fluidized-bed boiler, comprising means for directly supplying a fluidized medium taken out of a bunker to a fluidized-bed.

(9) A heat transfer tube bundle is provided in the fluidized bed provided with a fluidized bed, and the bed temperature at which the bed temperature should follow a set value by the flow rate of fuel to the fluidized bed is increased in the fluidized bed. In the control apparatus for a fluidized bed boiler, which is calculated as a fluidized bed volume average value of a temperature distribution, a thermal conductivity in which the bed temperature distribution in the fluidized bed takes different values depending on three directions of depth, height and width of the furnace fluidized bed. A control device for a fluidized-bed boiler, wherein the control device is calculated by heat conduction calculation by a computer.

(10) In the control apparatus for a fluidized-bed boiler according to the above (9), the thermal conductivity values in the three directions are obtained by dividing the thermal conductivity values in the three directions of the design plan value by the same magnification in each direction. A control device for a fluidized-bed boiler, wherein the control value is a multiplied value. (11) The control apparatus for a fluidized-bed boiler according to the above (9) or (10), further comprising means for measuring at least two points of the temperature of each part of the fluidized-bed boiler. .

(12) The value of the same magnification described in (10) above is used to calculate the standard deviation by volume average of the layer temperature portion obtained by the heat conduction calculation described in (9) from the measured layer temperature. A fluidized-bed boiler control device, which is back calculated and set to be equal to a standard deviation value. (13) The control apparatus for a fluidized-bed boiler according to any one of (9) to (12), further including a circuit that measures at least two points of each temperature of the fluidized bed and calculates a standard deviation from the measured temperatures. A control device for a fluidized-bed boiler, characterized in that: In the present invention, a pressurized fluidized-bed boiler can be used as the fluidized-bed boiler.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention, in which a fluidized bed combustion device 2 is installed inside a pressure vessel 1 and air as a fluidizing gas and a supporting gas is supplied to the pressure vessel 1.
It is supplied from the inside to the bottom of the fluidized bed combustion device 2 via the flow rate controller 3. Further, the air is made uniform by the distribution plate 5 and supplied to the fluidized bed 6. On the other hand, the fuel is supplied from the fuel supply device 4 to a lower portion of the fluidized bed 6, and most of the fuel is burned in the fluidized bed 6. A heat transfer tube 17 is provided above the fluidized bed 6 to collect heat generated by combustion. The combustion gas is guided from the upper part of the fluidized bed combustion device 2 to the outside of the pressure vessel 1 by the pipe 9, and after removing particles accompanying the combustion gas by the dust removal device 15, the pressure is reduced to the atmospheric pressure by the gas turbine 13. It is cooled by the cooler 10 and discharged from the chimney 16 to the atmosphere. The compressor 12 is coaxially coupled to the gas turbine 13.
The air 55 is sucked from the atmosphere, and the pressure
Is supplied with pressurized air. If the power recovered by the turbine 13 exceeds the required power of the compressor 12, power can be generated by the generator 14. The fluidized medium can be supplied from the medium holding tank 210 to the lower portion of the fluidized bed 6, and the fluidized medium can be discharged from the bottom of the fluidized bed 2 to the outside of the system.

Below the fluidized bed 6, a detection device 22 for monitoring the fluidized state is installed. Although the detection device 22 is not limited to a specific structure, for example, there is a differential piezoelectric transmitter that measures the pressure loss of the flowing gas in a local portion of the fluidized bed 6 of about 1 m or less.

FIG. 2 illustrates the principle of detecting the flow state using a differential piezoelectric transmitter. The superficial velocity of the fluid flowing through a specific layer (the gas flow rate is determined by the cross-sectional area of the vessel in the absence of a fluid medium). In the non-fluid state (left side of the figure), the pressure loss increases with the superficial velocity, whereas when the superficial velocity increases when the bed fluidizes, The pressure loss hardly changes. The superficial velocity at which the fluidized state transitions from the non-fluidized state to the fluidized state is called the fluidization start velocity. If the fluidized gas state (temperature, pressure, etc.) is the same, the larger the particle size, the higher the fluidization start velocity Having. Considering particles of different sizes at the same superficial velocity, the pressure loss is reduced when the particle diameter becomes coarse and does not flow sufficiently as compared with the state where the particle diameter is finely flowing. Therefore, the flow state can be evaluated by monitoring the temporal change of the pressure loss.

For example, in a fluidized-bed boiler using coal as a fuel and limestone as a fluid medium, there is a possibility that ash in the coal reacts with limestone to produce a low melting point compound. The generated low melting point compound slightly melts even at the order of 800 ° C., and acts to aggregate the fluidized media to form coarse particles. When coarse particles are generated in the fluidized bed, the coarse particles gradually fall to the lower part of the fluidized bed and accumulate. It is preferable to monitor the loss.

When a poor flow is detected, coarse particles causing the poor flow are accumulated in the lower part of the fluidized bed. The coarse particles accumulated in this portion are extracted by the extracting means 21 and flow is compensated for. If the medium is additionally supplied from the medium holding tank 210, it is possible to eliminate the poor flow. The removed fluid medium can be sent to the medium holding tank 210 for reuse after removing coarse particles if necessary.

FIG. 3 shows another embodiment of the present invention, in which a plurality of thermometers are used for the flow state detecting means 23. In a fluidized bed in a good fluidized state, the inside of the bed has a relatively uniform temperature distribution due to intense mixing of particles. As described above, when coarse particles that do not flow sufficiently occur in the fluidized bed during operation, the movement of the particles stagnates, resulting in an uneven temperature distribution. Even if this principle is used, poor flow can be detected similarly, and coarse particles are extracted from the bottom of the fluidized bed in the same manner as in the embodiment of FIG. Operation can be maintained for a long time.

A second embodiment of the present invention will be described with reference to FIG. The solid sulfur used in the fluidized medium (limestone) sulfuration acceleration treatment is supplied from a sulfur hopper 126 to a kneader 122, mixed with pulverized coal slurry, limestone for in-furnace desulfurization, and water, and stirred. 1
Through the CWP nozzle 119, the fluid is supplied to the fluidized bed boiler 2. The sulfuration reaction of the fluid medium is accelerated by the sulfur content in the CWP, and the sulfuration is completed in about one day from the start of operation as shown in FIG. When the continuous operation is performed without performing the sulfidation acceleration treatment of the fluid medium, it takes at least about 2 to 3 weeks to complete the sulfidation.

The operation of accelerating the sulfidation of the fluid medium is performed from the start of the boiler, and normal operation (in a full load zone) can be performed early after the completion of the sulfuration. FIG. 5 is a comparison of NOx before and after BM (fluid medium) sulfurization acceleration processing, and shows that NOx is reduced by performing sulfurization acceleration processing. FIG.
Fig. 4 shows the change over time of NOx in continuous operation, and shows that NOx is reduced early by the sulfurization acceleration treatment of the fluid medium.

The acceleration treatment for reducing CaO by mixing solid sulfur in CWP works as follows. The solid sulfur mixed in the CWP is supplied to a fluid medium forming a fluidized bed, becomes SO ₂ by combustion, and further reacts with CaO as a catalyst substance to form CaSO ₄ (gypsum) as shown in a reaction formula (1). Generate and stabilize.

[0044]

Embedded image CaO + ／ O ₂ + SO ₂ → CaSO ₄ (1) Further, S generated from sulfur contained in coal in CWP
In the desulfurization reaction for reducing Ox, CaCO ₃ directly reacts with SOx according to the equations (1) and (2) in a state before pressurization such as at start-up, and according to the equation (2) in a pressurized state, and CaS
Generate O ₄ .

[0045]

## STR00004 ## CaCO ₃ + SO ₂ + 1 / 2O ₂ → CaSO ₄ + CO ₂ (2) By the reaction represented by the formulas (1) and (2), CaO as the catalyst substance in the fluidized medium before sulfurization and the desulfurizing material CaCO ₃ is simultaneously sulfided. However, even if CaCO ₃ is reduced by performing the sulfurization acceleration treatment with solid sulfur, if CaCO ₃ is maintained at an amount required for desulfurization performance, SOx
It does not affect environmental regulation values. Even after the sulfurizing treatment of the fluidized medium, the limestone for in-furnace desulfurization is always supplied to the fluidized bed as CWP, so that there is no problem in desulfurization performance.

By mixing solid sulfur into CWP, the sulfurization of the fluid medium is accelerated, CaO as a catalyst substance is rapidly reduced, and CaCO ₃ as a source of CaO ₃ is reduced to a range where there is no problem in desulfurization performance. In addition, NOx can be reduced as shown in FIG.

A third embodiment of the present invention will be described with reference to FIG. A fluid medium having a large particle size (BM (Bed Material)
real)) is a fluidized bed as a CWP through the kneading machine 122 by the BM transport conveyor 425 and the BM supply pipe 216 by adjusting the amount adjusted from the large particle size BM bunker 401 from the small particle size BM bunker 422, respectively. It is supplied to the combustion device 2. The performance of the fluidized bed can be maintained by supplying BM having an appropriate particle size.

Short-term fluctuations such as a load change are dealt with by supplying BM from the BM replenishing hoppers 207a and 207b. The BM having a large particle size is converted from the large BM bunker 401 to the large B
The M hopper 207b is filled. When the bed height is reduced, the large particle size BM replenishing hopper 207b filled with the large particle size BM is pressurized by the pressurizing line 205b,
The large particle size BM is replenished to the large particle size BM tank 210b with the M tank 210b in a pressure equalized state. The large-particle-size BM is supplied to the furnace through the BM supply line 212b, and recovers a decrease in bed height to maintain a predetermined bed height.

On the other hand, the small particle size BM is a small particle size BM bunker 42.
2 to the small particle size BM replenishing hopper 207a. When the desulfurization performance is reduced or the dust removal performance is reduced due to a decrease in the ash particle size at the furnace outlet, the small particle size BM replenishing hopper 207a filled with the small particle size BM is pressurized by the pressurizing line 205a, The small particle size BM is replenished to the small particle size BM tank 207a while keeping the small BM tank 207a in a pressure equalized state. The small particle size BM is supplied to the fluidized bed combustion device 2 through the BM supply line 212a, and recovers the desulfurization performance and the dust removal performance. The BM tanks 210b and 210a are two 50% capacity tanks of the conventional system in order to supply the large particle size BM and the small particle size BM to the combustion device 2 independently.

As an example in a fluidized bed with a superficial velocity of about 1 m / s, the distribution of limestone having a particle diameter of 3 mm or less and a terminal velocity of 0.3 mm or less corresponding to the superficial velocity is about 50%. The desulfurization rate is 100 while the bed height is maintained with the adjusted particle size distribution.
%, It was possible to operate to obtain a high desulfurization performance. That is, at a superficial velocity of 0.9 m / s, limestone having a particle diameter of 0.3 mm or less directly contributes to desulfurization, and a limestone of 0.3 mm or more contributes to maintaining the bed height. In the fluidized bed of s, the above-mentioned two types of BM can be achieved by using one type of limestone of 0.3 mm or less and the other type of limestone of 0.3 mm or more.

The two types of BM having different particle sizes supplied by the CWP during operation or replenished directly to the furnace through the BM tank operate as follows. In order to increase the desulfurization performance and the outlet ash particle size of the fluidized bed, it is necessary to scatter limestone used as the BM to some extent, and it is necessary to suppress the amount of limestone to maintain the bed height. In order to control the amount of limestone scattered, it is necessary to use limestone having an appropriate particle size distribution depending on the flow characteristics such as the superficial velocity of the furnace.

By supplying two kinds of limestones having different particle diameters, large and small, independently, and adjusting the supply amount of each, limestone having an appropriate particle diameter can be supplied to the furnace as BM. . In the BM supplied to the fluidized bed, the particle diameter of particles having a particle diameter smaller than the superficial velocity and the terminal velocity of the particles is set to the scattered particle diameter. The above-mentioned large particle size means a particle size equal to or larger than the scattered particle size, and a small particle size means a particle size equal to or smaller than the scattered particle size.

Further, since the appropriate amount of small limestone required for desulfurization can be supplied, unnecessary limestone which does not contribute to desulfurization is eliminated, and the supply amount of limestone can be reduced. Also, with respect to fluctuations in the amount of scattered limestone due to a load change or the like, the amount of scattered limestone can be reduced by replenishing limestone having a large particle diameter into the furnace.

It should be noted that one type of BM is limestone having low pulverizability or, for example, silica sand which does not function for desulfurization but is less pulverizable than limestone is used as the BM for maintaining the layer height, and the layer height decreases. In this case, the height of the layer can be recovered by replenishing the layer. As another type of BM, on the contrary, the amount of limestone scattered in the formation decreased, the desulfurization performance deteriorated, and the ash particle diameter at the furnace outlet became smaller, and the performance of the downstream dust removal device deteriorated. In this case, limestone having a high degree of powdering or limestone having a small particle diameter may be used, and BM for improving the desulfurization and dedusting performance may be replenished in the layer to restore the desulfurization and dedusting performance.

A fluidized-bed boiler provided with a boiler temperature control device according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a system diagram of a fluidized-bed boiler provided with the boiler temperature control device. The bed temperature is measured at two or more points in the fluidized bed, which are 101a to 101z.
These layer temperature measurement values k are input to the layer temperature averaging device 200, and the layer temperature averaging device 200 outputs a volume average value 102 of the layer temperature as a calculation result. The flow rate of the fuel is adjusted by the control device 105 such that the volume average value 102 of the layer temperature follows the set value 104. That is, the setting value 1
04 and the volume average value 102 of the layer temperature are converted into a deviation 107 by a subtractor 106, which is input to a controller 105 to output a demand 108 for a fuel amount.

Next, FIG.
Indicates the contents of 0. The layer temperature volume average processing device 200 includes a standard deviation calculation device 301, a scalar magnification calculation device 302, and a layer temperature volume average processing device 306, and has the following functions.

First, the standard deviation calculating device 301 calculates the standard deviation of the measured values 101a to 101z of the bed temperature of each part of the fluidized bed. This quantifies the degree of deviation across the boiler furnace. Next, in the scalar magnification back calculation device 302, the relationship between the thermal conductivity that physically represents the heat transfer of the furnace fluidized bed and the standard deviation of the bed temperature due to the thermal conductivity is built in a chart or a graph. It was easy to graph this way because the thermal conductivity was 3
This is due to the fact that the layer temperature distribution can be expressed only by the scalar magnification in the same direction. In this apparatus, the thermal conductivity is set to take different values in three directions of the furnace fluidized bed, that is, each of the depth (x direction), the height (y) and the width (z). Rate plan value 3
03x, 303y, and 303z. Therefore, the built-in charts or graphs in this device provide scalar magnification values that indicate how much these thermal conductivity plans should actually be modified and the calculation of the bed temperature standard deviation corresponding to each magnification value. The relationship with the expected value is given. Therefore, if the standard deviation 103 is given as information from the measured value, it is easy to estimate the scalar magnification value. This is the output from the device 302, the scalar magnification 304. Further, the previous thermal conductivity plan values 303x, 303y and 30
3z are each doubled by this scalar magnification 304,
Or reduced thermal conductivity settlement values 305x, 305y
And 305z. The heat transfer calculation is performed by the bed temperature volume averaging device 306 using the settled value, and the bed temperature 3
The dimensional distribution, and finally the volume average 102 of the layer temperature obtained by volume averaging them, is obtained and output from the apparatus. The fuel control device 105 controls the fuel amount demand 108 so that the volume average value follows the bed temperature set value 104 (see FIG. 8).

Next, in the above embodiment,
The theory of bed temperature control of a fluidized bed boiler will be described. First, taking a fluidized bed boiler as an example, 1) a method of calculating a three-dimensional bed temperature distribution in a fluidized bed using a heat conduction physical model will be described below, and 2) a fluidized bed using bed temperature measurement values. Estimation of thermal conductivity, that is, relating the standard deviation obtained from multiple layer temperature measurements to thermal conductivity, and determining how many times the thermal conductivity value in the design plan is a scalar magnification factor To be determined. Using the calculated value of the thermal conductivity, 3) calculation of the bed temperature volume average value by the heat conduction equation, and 4) control and adjustment method of the fuel flow rate.

1) 3 in the fluidized bed according to the heat conduction physical model
Method of calculating the three-dimensional layer temperature distribution Explanation of symbols: C: Specific heat [kcal / (kg · ° C)] D: Particle mixing diffusion coefficient [m ² / s] F: Heat flow vector [kcal / (m ² · s)] func *: general function G: mass flow vector [kcal / (m ² · s)] k: thermal conductivity magnification [-] N: number of layer temperature measurement points [pieces] Q: heat generation or absorption [ kcal / (m ³ · s)] T: Temperature [° C.] u: Superficial velocity vector [m / s] V: Volume [m ³ ] x: Furnace depth coordinate [m] y: Furnace height coordinate [m] z: Furnace width coordinate [m] Greek letter λ: Thermal conductivity [kcal / (ms · ° C.)] ρ: Density [kg / m ³ ] ∇: Gradient vector [l / m] Subscript air: Fluidized air B: Fluidized bed dist: Dispersion plate F: Furnace g: Combustion gas gen: Heat generation Hsink: Heat transfer tube Heat: layer surface x: furnace depth direction y: furnace height direction z: furnace width direction Superscript 0: design plan value av: volume average Fluidized: fluidized state set: set value *: measured value #: Estimated value

Heat conduction physical model The heat flow in the fluidized bed is given by the following vector: F (x, y, z) = − λ · ΔT _B (x, y, z) + c _B
T _B (x, y, z) · G (x, y, z) where G (x, y, z) = ρ _g · u. Since this heat flow is balanced by the heat generation of the fuel and the heat absorption by the heat transfer tube, the following balance equation holds: -∇ · F (x, y, z) + Q _gen (x, y, z) -Q
_Hsink (x, y, z) = 0 Further, the thermal conductivity tensor λ is anisotropic, and its value is different in each direction of the furnace; (λ) _xx = λ _x (λ) _yy = λ _y (Λ) _zz = λ _z Others are zero.

This balance equation is expressed by the following boundary condition F (x, y = y _dist , z) = c _air · T _air · G (x,
y = y _dist, z) F (x, y = y _surf , z) = c _g T _g G (x, y =
Solving under y _surf, z) yields a three-dimensional distribution of bed temperature T _B (x, y, z) over the furnace fluidized bed.

The volume average value T _B ^{AV of the} three-dimensional distribution calculation value
Given by the standard deviation? T _{B ^{and; T B AV = 1 / V}} F · ∫∫∫dx · dy · dzT B (x,
y, z) δT _B = 1 / V _F · sqrt (∫∫∫dx · d
y · dz (T _B (x, y, z−T _B ^AV ) ² ) The average value and the standard deviation value are determined according to the thermal conductivity, and T _B ^AV = func1 (λ _x , λ _y , λ _z ) ΔT _B = func2 (λ _x , λ _y , λ _z ). The standard deviation? T _B as estimated above 1) of the fluidized bed heat conductivity using 2) layer temperature measured is determined as a function of the thermal conductivity. On the other hand, the standard deviation can be calculated using a plurality of bed temperature measurements.

Here, the thermal conductivity used in the calculation is a scalar multiple of the thermal conductivity value in the design plan as described below, and the thermal conductivity value in the base design plan is the depth of the furnace. , Height and width, respectively.

Explaining the above, the thermal conductivity value in the design plan is calculated by the following equation: λ ⁰ = c · ρ ^{Fluidised, 0} · D ⁰ where the mixing of the flowing medium or the input fuel is determined depending on the heat transfer tube arranged in the furnace, in the case where the heat transfer tube axis are arranged in the depth direction, towards the particle mixture of the depth is larger than the width direction, alpha> as 1, D _x ⁰ = Α · D _z ⁰ . The height direction is horizontal (depth and width)
_Dy ⁰ = β · D _x ⁰ where β ≒ 10, which is about one digit larger. That is, the furnace particle mixing diffusion coefficient D takes different values in three directions of the depth, height and width of the furnace. As a result, the thermal conductivity λ ⁰ given by the above equation also has different values in three directions.

Next, even if the flow state in the furnace changes due to, for example, a change in load or bed height, the above-mentioned situation hardly changes. The relative relationship between the directional values hardly changes. Therefore, ^{_{λ x = k · λ x 0}} λ y = k · λ y 0 λ z = k · λ z 0 regardless of the flow state is established. The reason is as follows.

[0066] λ _y ⁰ = a ^{_{β · λ z 0 λ x 0}} = α · λ z 0, if the relationship with λ _z = k · λ _x ⁰ between the numerical value, λ _y = β · λ _x = Β · (k · λ _x ⁰ ) = k · (β · λ _x
⁰ ) = k · λ _y ⁰ . The same applies to the width direction.

The standard deviation δT _{B of the} layer temperature and the thermal conductivity (λ _x ,
The scalar magnification can be determined from the function func2 that associates λ _y , λ _z ). This will be described below. As the bed temperature measurement value N (> = 2) was pieces, which T _B ^* 1, ......, represented by T _B ^{* N.} At this time, the standard deviation is δT _B ^{* 1} = 1 / (N−1) · sqrt (Σ _1-1 ^N (T _B
^* 1 is a -T _B ^av *) ^2).

Meanwhile, the thermal conductivity value is assumed to be a scalar k times the design plan _{value; λ x = k · λ x} 0 λ y = k · λ y 0 λ z = k · λ z 0 In this case, the standard calculated by heat conduction physical model of deviation is a function of the scalar ratio k _{only, δT B = func2 (λ x} , λ y, λ z) = func2 (k · λ x 0 · k · λ y 0 · k · λ _z ⁰ ) = func3 (k). Since this function means that the heat transfer becomes easier when the scalar magnification value k increases, the standard deviation δT _B
Decreases such that δT _B increases when the k value decreases.
It is a monotonically increasing function of the variable.

Therefore, the scalar magnification value k can be easily obtained by replacing the left side in the above equation with δT _B ^* calculated from the measured value.
K ^# = func4 (δT _B ^* ) This function func4 is an inverse function of func3, and uniquely obtains k ^# since it is a single-valent function. 3) Calculation of the layer temperature volume average value by the heat conduction equation Since the scalar magnification value k has been determined as described above, the thermal conductivity in the design plan can be converted and calculated into the thermal conductivity in the actual machine, and λ _x ^# = k ^{_{# · λ x 0 λ y #}} = k # · λ y 0 λ z # = k therefore ^# · ^λ _z ^0, these give a volume average value of the bed temperature ^{_{with; T B av # = func1 (}} λ x # ^{_{, λ y #, λ z #}} ) 4) the fuel flow rate control and adjustment method on the bed temperature volume average value T _B ^{av #} of, it is considered that a layer temperature representing the fluidized layer the entire region, the fuel flow rate may be controlled, adjusted to the bed temperature volume average value T _B ^{av #} follows the set value T _B ^{the set.} That is, these deviations (T _B
^{av #} -T _B ^set) is may feedback as zero.

[0070]

According to the present invention, a local fluid defect in a fluidized bed is detected at an early stage, and the fluid medium is replaced until the fluid defect can be eliminated. Can be driven.

Further, according to the present invention, even when a new fluidized medium (limestone) is used, such as during a trial operation of a new plant,
By performing sulfurization acceleration treatment of the fluid medium with sulfur,
NOx emissions from the fluidized bed combustion device can be reduced at an early stage. Further, according to the present invention, the bed height of the fluidized bed combustion apparatus can be stably maintained, and the desulfurization performance of the fluidized medium can be kept high. In addition, it is possible to quickly recover the bed height even if the bed height changes transiently during operation.

Further, according to the present invention, the bed temperature of the fluidized bed can be made to appropriately follow the set value. This makes it possible to appropriately set the bed temperature representative of the fluidized bed even when the fuel mixing is poor and the bed temperature deviation in the furnace fluidized bed is large, especially when the load changes. Even when the bed temperature distribution is obtained, the bed temperature control does not focus on only a specific point in the fluidized bed, and the entire area of the fluidized bed can be more appropriately maintained at the set temperature. In other words, there is an effect that the heat balance is not largely lost even when the load changes. In addition, all that is required is to read a simple scalar magnification value from the graph, which has effects such as simple calculation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a fluidized state determination method based on fluidized bed pressure loss.

FIG. 3 is a diagram showing another example of the first embodiment.

FIG. 4 is a diagram showing a second embodiment of the present invention.

FIG. 5: NO of exhaust gas before and after sulfurizing treatment of a new fluid medium
FIG. 7 is a comparison diagram of x concentration.

FIG. 6 is a graph comparing the NOx concentration of exhaust gas with and without the sulfurization acceleration treatment of a new flowing medium.

FIG. 7 is a diagram showing a third embodiment of the present invention.

FIG. 8 is a diagram showing a fourth embodiment of the present invention.

9 is an explanatory diagram of a layer temperature averaging device in the temperature control device according to the embodiment shown in FIG. 8;

FIG. 10 is an overall view of a pressurized fluidized-bed boiler according to the related art.

FIG. 11 is a supply system diagram of a fluidized medium and a fuel of a pressurized fluidized-bed boiler according to a conventional technique.

FIG. 12 is a schematic view of a fluidized-bed boiler according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pressure vessel, 2 ... Fluidized bed combustion apparatus (furnace), 3 ... Flow controller, 4 ... Fuel supply apparatus, 5 ... Dispersion plate, 6 ... Fluidized bed,
7: fluid medium replenishing hopper, 9, 11: high-temperature gas pipe, 1
0: Heat exchanger (cooler), 12: Compressor, 13: Gas turbine, 14: Generator, 15: Dust remover, 16: Chimney,
17: heat transfer pipe, 18: fluidized gas pipe, 21: fluid medium extraction pipe, 22: flow state monitoring device by pressure loss,
23: flow state monitoring device based on temperature distribution, 25: coal supply line, 55: combustion air, 101: bed temperature measurement value, 10
2: bed temperature volume average value, 103: standard deviation, 104: bed temperature set value, 105: (fuel) controller, 106: subtractor,
107: deviation, 108: fuel demand, 109: gas turbine outlet duct, 110: economizer, 111: denitration catalyst, 113, 118: ammonia injection nozzle, 114 ...
Ammonia dilution air, 115 ... ammonia vaporizer, 11
6 ammonia booster fan 117 ammonia diluted air (pressurized) 119 CWP supply nozzle 120 CW
P pump, 121: CWP tank, 122: Kneader, 1
23: limestone hopper, 125: pulverized coal slurry tank, 1
26: sulfur hopper, 200: bed temperature and volume averaging apparatus, 2
01: flowing medium bunker, 202: flowing medium conveying blower
203: fluid medium conveying pipe, 204: hopper inlet valve, 2
05: pressurizing line, 206: decompression line, 207: fluid medium replenishing hopper, 207a: small particle size fluid medium replenishing hopper, 207b: large particle size fluidizing medium replenishing hopper, 210: fluid medium tank, 210a: small particle size fluid Medium tank, 21
0b: Large-diameter fluidized-medium tank, 211: Fluid-medium return line, 212: Fluid-medium supply line, 216 ... Fluid-medium supply line, 218 ... Water supply line, 301: Standard deviation calculator, 302: Scalar magnification reverse calculator, 303: thermal conductivity plan value, 304: scalar magnification, 305: thermal conductivity settlement value, 306: bed temperature volume average processing apparatus, 401: large particle size fluidized medium bunker, 422: small particle size fluidized medium bunker,
425 ... Conveyor for transporting a fluid medium.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoyuki Asanuma 6-9 Takara-cho, Kure-shi, Hiroshima Pref. Inside the Kure Factory (72) Inventor Susumu Yoshioka 3-36 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi, Ltd. Inside Kure Research Laboratory (72) Inventor Mamoru Mizumoto 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Tetsuro Itami 3-36 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi, Ltd. (72) Inventor Kodai Nonaka 6-9 Takaracho, Kure City, Hiroshima Prefecture Inside Babcock Hitachi Kure Factory (72) Inventor Shuhei Akimoto 6-9 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Kure Factory F term (reference) 3K064 AA01 AA08 AA15 AA18 AA20 AB01 AC01 AC07 AC12 AC13 AD01 AD05 AF03 BA11 BA13 BA17 BA24 BB01 BB03 BB05

Claims (13)

[Claims] 1. A fluidized bed for burning a fossil fuel, means for supplying a supporting gas for burning the fuel to the fluidized bed, means for supplying a fluidized medium to the fluidized bed, and A method for controlling a fluidized-bed boiler, comprising means for extracting a fluidized medium, wherein a fluidized state is monitored so as to recover a fluidized state when the fluidized state deteriorates. , And as a result, the rising bed height is maintained in a predetermined range by extracting the fluidized medium from the lower part of the fluidized bed, thereby controlling the fluidized bed boiler. 2. The method for controlling a fluidized-bed boiler according to claim 1, wherein a local fluidized state under the fluidized bed is detected by a local gas pressure loss in a height direction of the fluidized bed. Fluidized bed boiler control method. 3. The fluidized-bed boiler control method according to claim 1, wherein the local fluidized state of the lower part of the fluidized bed is detected at a plurality of temperatures in the lower part of the fluidized bed. Control method. 4. A fluidized bed for burning a fossil fuel, a means for burning the fuel and supplying gas for flowing the fluidized bed, and a means for supplying a new fluidized medium to the fluidized bed. In the control device of the fluidized bed boiler, when the new fluidized medium is used, a sulfur component is mixed into the fluidized bed to accelerate the sulfidation of calcium oxide in the new fluidized medium to increase nitrogen oxides in the exhaust gas. A control device for a fluidized-bed boiler, comprising a control unit. 5. A fluidized bed for burning fuel, and said fluidized bed comprises:
Means for supplying a gas for burning the fuel and fluidizing the fluidized bed, and supplying a fluidized medium to the fluidized bed;
A replenishing means for adjusting the bed height and desulfurization performance of the fluidized bed, wherein the fluid medium supply / replenishing means comprises two types of fluidized media having different particle diameters or different types of fluidized media. A fluidized-bed boiler control device formed for each type of fluidized medium. 6. The control apparatus for a fluidized-bed boiler according to claim 5, wherein one of the fluid medium supply / replenishment means is provided.
The type is a coarse fluid medium having a scattered particle diameter or more with respect to the superficial velocity, and is a supply and replenishing means for a limestone or other fluid medium such as silica stone and alumina. A control device for a fluidized-bed boiler, comprising a supply / replenishment means for a fluidized medium containing: 7. The control apparatus for a fluidized-bed boiler according to claim 6, wherein the superficial superficial velocity is approximately 1 m / s.
The supply and replenishment means for the various types of fluid medium is a supply and replenishment means for coarse limestone having a particle size range of 0.3 to 3 mm and fine limestone having a particle size range of 0.3 mm or less. Fluidized bed boiler control device. 8. The control apparatus for a fluidized-bed boiler according to claim 5, further comprising a bunker for a fluid medium having a large particle size and a bunker for a fluid medium having a small particle size, and supplying the fluid medium. Means for kneading the fluid medium taken out of the bunker with fuel and water as normal replenishing means and supplying the mixture to the fluidized bed with fuel and water; and taking out the fluid medium bunker during short-term fluctuations including load changes. A control apparatus for a fluidized-bed boiler, comprising means for directly supplying a fluidized medium to a fluidized bed. 9. A bed comprising a fluidized bed and a heat transfer tube bundle disposed in the fluidized bed, wherein the bed temperature at which the bed temperature should follow a set value by the flow rate of fuel to the fluidized bed is the bed temperature over the fluidized bed. In the control apparatus for a fluidized-bed boiler calculated as a fluidized-bed volume average value of the distribution, a bed temperature distribution in the fluidized bed is determined by a thermal conductivity having different values depending on three directions of depth, height and width of the furnace fluidized bed. A fluidized-bed boiler control device characterized by being estimated by heat conduction calculation. 10. The controller for a fluidized-bed boiler according to claim 9, wherein the thermal conductivity values in the three directions are obtained by multiplying the thermal conductivity values in the three directions of the design plan value by the same magnification in each direction. A fluidized-bed boiler control device characterized in that the value is a value. 11. The fluidized bed boiler control device according to claim 9, further comprising means for measuring at least two points of each temperature of the fluidized bed in the fluidized bed boiler. 12. The value of the same magnification according to claim 10, wherein
The standard deviation based on the volume average of the layer temperature portion obtained by the heat conduction calculation according to claim 9 is back calculated and set to be equal to the value of the standard deviation calculated from the measured layer temperature. A controller for a fluidized-bed boiler. 13. The fluidized bed boiler control device according to claim 9, further comprising a circuit for measuring at least two points of each temperature of the fluidized bed and calculating a standard deviation from the measured temperatures. Characteristic control device for fluidized bed boiler.