JPH06272813A - Fluidized bed type combustion facility and its operating method - Google Patents

Abstract

PURPOSE:To reduce NOx without making an inside part of a fluidized bed complex and without reducing a total performance of a fluidized bed type combustion device. CONSTITUTION:A fluidized bed type combustion device is comprised of a plurality of air supplying nozzles 4 distributed and arranged in a horizontal direction at a lower part of a fluidized bed 2 and a plurality of air flow rate adjusting valves 15 for adjusting each of flow rates of air fed to these nozzles. A control device 5 has a function 6 for calculating a distribution of air ratio for calculating an air ratio distribution in a horizontal direction of the fluidized bed 2 with reference to an air ratio of the discharged gas sampled with a plurality of gas concentration measuring ends 17a dispersed and arranged in a horizontal direction at an upper part of the fluidized bed 2, and a function 7 for setting each of air flow rates of air passing through a plurality of air flow rate adjusting valves 15 in such a manner that the obtained air ratio distribution may become a uniform air ratio distribution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed combustion facility for supplying a fuel such as coal and air into a fluidized bed for fluidized combustion.
And its operating method.

[0002]

2. Description of the Related Art A fluidized bed combustor supplies fuel such as coal into a solid particle bed, and air supplied from the bottom of the bed causes
This layer fluidizes and burns fuel. In this fluidized bed combustor, even if a sufficient amount of air is supplied with a large amount of air and a large air flow rate is provided, the residence time of fuel in the combustion section can be increased and high combustion efficiency can be provided. There is a feature called. On the other hand, since it is necessary to supply a certain amount of air or more to maintain the fluidized state, the fuel will be burned in an oxidizing atmosphere, and when a fuel containing nitrogen such as coal is used, NOx is generated. The problem arises that the quantity increases. This N
Reducing the amount of Ox generated is an important technical issue in terms of commercialization of fluidized bed combustors.

Examples of conventional NOx emission reduction methods at the combustor outlet of a coal-fired fluidized bed combustor include (1) multi-stage combustion,
Methods such as (2) injection of denitration agent, (3) denitration by solid carbon, etc. are known. As the method of (1), for example, two upper and lower dispersion plates are installed in a furnace, primary air is below the lower dispersion plate, secondary air is below the upper dispersion plate, and tertiary air is above the upper dispersion plate. Is supplied to make the lower fluidized bed (the layer between the upper dispersion plate and the lower dispersion plate) a reducing atmosphere suitable for denitration, and desulfurize and improve the combustion efficiency of the upper fluidized bed (the upper layer of the upper dispersion plate). There is a method of making an oxidizing atmosphere suitable for (Japanese Patent Laid-Open No. 58-40411).

As the method (2), for example, ammonia is used as a denitration agent, and in order to avoid generation of NOx due to oxidation of ammonia in a fluidized bed at a high temperature in an oxidizing atmosphere, secondary air is provided in the freeboard. At the same time, there is a method of spraying ammonia (JP-A-62-169917).
As the method (3), there is known a method of performing denitration by using carbon in char produced in the combustion process from coal as a fuel. In this method, solid carbon itself is used for the reaction of reducing NOx and the reaction of reducing NOx by CO using char as a catalyst. As a known technique, there is a method of activating char using an internal circulation type fluidized bed and increasing the residence time of char in the layer to accelerate the denitration reaction (Japanese Patent Laid-Open No. 2-282601).

These are techniques that focus on one purpose of reducing NOx during steady combustion, and both are techniques that divide the inside of the combustor by combustion state and reaction environment.

By the way, in the coal-fired fluidized bed boiler, NOx
In addition to the reduction, performances such as reduction of SOx by using in-layer desulfurizing agent, improvement of combustion efficiency, and prevention of corrosion of materials such as heat transfer tubes are required. As a characteristic of these performances, the performance is improved in an oxidizing atmosphere rich in oxygen, and the performance is deteriorated in a reducing atmosphere lacking oxygen. That is, since an environment opposite to that for reducing NOx is required, practical fluidized bed combustors often perform combustion under oxygen conditions (air ratio) that are optimal for both performances. At this time, it is desirable that the state in the fluidized bed has an optimum air ratio in the entire region, but if fuel is supplied from the outside of the fluidized bed (fluidized bed side wall, fluidized bed top, bottom), The amount of fuel present in the bed becomes uneven, and when the combustor is used under partial load or when the load changes, uneven distribution of fuel in the fluidized bed and local unevenness of the air ratio are likely to occur. This causes problems such as emission of high-concentration NOx, melting of ash due to local hot spots, and material deterioration.

Therefore, as a method for operating a practical fluidized bed combustor, there has been required a technique for homogenizing the inside of the fluidized bed in order to obtain good combustion characteristics. Such techniques include (4) fluidized bed agitation by a stirring member, (5) fluidized bed mixing promotion by an air supply method, and (6) fuel diffusion by a fuel supply method.

As the method (4), a device for vibrating the bed is provided in the fluidized bed to make the combustion and reaction in the bed uniform.
There is a method of preventing the abnormal occurrence of NOx (Japanese Patent Laid-Open No. 60-21).
6836). As the method (5), air is supplied into the fluidized bed in two directions, upward and sideways, to promote mixing of fuel and air (Japanese Patent Laid-Open No. 63-2824).
No. 04), or a method of generating swirling flow in the fluidized bed by supplying two kinds of air having a high flow velocity and a slow flow velocity from the fluidized bed bottom dispersion plate (Japanese Patent Laid-Open No. 2-195104).
As the method (6), there is a method in which a fuel supply pipe is inserted from the bottom of the fluidized bed and a burner head having swirl vanes is provided at the tip of the supply pipe in the fluidized bed to promote mixing and diffusion of fuel.
(JP-A-55-143308).

[0009]

In the above-mentioned conventional technique, the following points are raised as technical problems. First, there are the following issues regarding technologies that focus on low NOx emissions. Regarding the multi-stage combustion of (1), since the combustion is performed in a reducing atmosphere, there is a problem of progress of corrosion of the metal material. In particular, when a reducing atmosphere is created in the fluidized bed, there is a great fear that the heat exchanger and the like will be corroded by sulfur.

Regarding the injection of the denitration agent of (2), there is a problem of ammonia leakage. When ammonia, which is a harmful substance, is used as a denitration agent, after being used in the denitration reaction,
Unreacted ammonia must be prevented from leaking out of the combustion facility. For this reason, in addition to the ammonia supply facility, it is necessary to provide a facility for ammonia recovery or strictly control the amount of injected ammonia, which leads to a large facility and a large increase in facility cost.

Regarding the denitration by solid carbon of (3),
There is a problem of the effect of the desulfurization agent. In a reducing atmosphere suitable for reducing NOx, the desulfurization rate decreases because the desulfurization reaction with limestone, which is a desulfurizing agent, consumes oxygen. Therefore, from the viewpoint of desulfurization, it is not desirable to place the fluidized bed in a reducing atmosphere. In addition, limestone (CaCO3) is 800-900
In the fluidized bed at a high temperature of ℃, decarboxylation occurs and it exists as CaO. It is known that this CaO acts as a catalyst to accelerate the oxidation reaction of nitrogen compounds released from coal and increase the amount of NOx generated (eg, GJVogel, Annual Repo
rt of ANL / ES-CEN1007,1974). Therefore, there is a limit to increase the denitration efficiency in a fluidized bed containing a large amount of desulfurizing agent. That is, as described above, if the focus is simply on the reduction of NOx, other performance required as a combustor is sacrificed.

Next, there are the following problems regarding the technique of uniformizing the fluidized bed for improving the overall performance of the combustor. (4)
With respect to fluidized bed agitation by the stirring member and (6) diffusion of fuel by the fuel supply method, since the stirring member and the like are used, the combustor structure becomes complicated. Fluidized bed combustor
A simple feature of the combustor structure is a great feature, which is an advantage. On the other hand, the conventional technology that complicates the inside of the fluidized bed combustor has problems such as complicated maintenance, large combustor size, and increased equipment cost. Moreover, when a special member is provided in the fluidized bed, it is difficult to prevent wear and corrosion of the member.

Regarding (4) to (6), mechanical stirring of the fluidized bed or stirring by causing a swirling flow in the fluidized bed slows down the response in an unsteady state such as load fluctuation. There's a problem. One of the reasons for the long fuel residence time in a fluidized bed combustor is that the solid particles containing fuel are flowing at a slow velocity. Generally, the movement of particles in the fluidized bed is mainly in the vertical direction, and the moving speed in the horizontal direction is small. The particles flow upward in the gas to reach the surface of the layer, and then are extruded in the lateral direction to form a downward flow. The velocity of the vertical flow is also very slow compared to the gas velocity, and the volume of solid particles accompanying the gas is about one-quarter compared to the volume velocity of gas transfer (eg PN Rowe et al., Trans.Inst. .Chem.Engrs., 43, T
157, 1965). Therefore, in the method of uniformizing the bed using the flow, a large amount of gas passes through the non-uniform layer before the uneven distribution of the fuel in the bed due to load fluctuation is eliminated by the flow.
Combustion and reaction occur, and the effect of performance improvement is reduced.

The present invention has been made by paying attention to the above-mentioned conventional problems, and it goes without saying that NOx is reduced (1)
Provided a fluidized bed combustion facility that does not reduce the overall performance of the fluidized bed combustor, (2) does not complicate the fluidized bed, and (3) can respond to unsteady state in the fluidized bed in a short time, and its operating method. The purpose is to do.

[0015]

In a fluidized bed combustion equipment for achieving the above object, an air ratio distribution grasping means for grasping a horizontal air ratio distribution in a fluidized bed and various grasped air ratio distributions are provided. An air supply amount distribution adjusting means for adjusting a horizontal air supply amount distribution of the air supplied into the fluidized bed so that a target air ratio distribution predetermined according to conditions is obtained. It is what

Here, the air supply amount distribution adjusting means is
A plurality of air supply ports in which the locations for supplying the air are horizontally dispersed in the fluidized bed; and a plurality of air flow rate adjusting means for adjusting the flow rate of the air sent to each of the plurality of air supply ports. An air flow rate that determines each air flow rate adjusted by the plurality of air flow rate adjusting means so that the air ratio distribution grasped by the air ratio distribution grasping means becomes a target air ratio distribution predetermined according to various conditions. It may be configured to have setting means.

Further, in another fluidized bed combustion equipment for achieving the above object, a plurality of air supply ports for supplying air into the fluidized bed are horizontally dispersed, and in the vicinity of a portion to which fuel is supplied. Is characterized in that it is arranged more than other places.

[0018]

With the device having the air ratio distribution grasping means, the air ratio distribution in the horizontal direction in the fluidized bed can be grasped. The air supply amount distribution adjusting unit adjusts the horizontal air supply amount distribution of the air supplied into the fluidized bed so that the grasped air ratio distribution becomes a predetermined target air ratio distribution. In this way, since the air ratio distribution in the horizontal direction in the fluidized bed is controlled to reach the target air ratio, NOx can be reduced without lowering the overall performance of the combustor.

Further, even if a plurality of air supply ports are dispersed in the horizontal direction and are arranged in the vicinity of a place to which fuel is supplied more than other places, many are present in a place where the fuel existence rate is high. NOx can be reduced without degrading the overall performance of the combustor because the air is supplied and the air ratio distribution in the fluidized bed in the horizontal direction becomes nearly uniform.

Further, in the present invention, since the deviation of the air ratio distribution due to the deviation of the fuel distribution in the fluidized bed is dealt with by making the distribution of the air supply amount uneven, it is possible to stir the fluid medium. As a result of eliminating the need for equipment, the inside of the fluidized bed is not complicated. Therefore, reliability is enhanced, maintenance is facilitated, and manufacturing cost can be reduced. Furthermore, since the moving speed of air is much faster than the moving speed of the fluidized medium, in the present invention in which the air supply amount at each position of the fluidized bed is changed, rather than forcedly circulating or stirring the fluidized medium, The time required to reach the target air-fuel ratio in the fluidized bed can be shortened.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments according to the present invention will be described below with reference to the drawings. First, a first embodiment according to the present invention will be described with reference to FIGS.

In this embodiment, as shown in FIG. 1, in a power plant, a fluidized bed combustion equipment and a gas turbine 1 driven by a high temperature and high pressure gas sent from the fluidized bed combustion equipment.
2 and a generator 13 driven by the gas turbine 12. The fluidized bed combustion equipment includes a fluidized bed combustor 1 in which a fluidized bed 2 is formed, a cyclone 20 for removing dust and the like from exhaust gas from the fluidized bed combustor 1, a pressure vessel 14 for covering these, and a gas. An air compressor 11 driven by a turbine 12 and a controller 5 for controlling these are provided.

As described above, the fluidized bed combustor 1 is stored in the pressure vessel 14 and is operated under pressure by the air sent from the air compressor 11. Fuel 10 is combustor 1
It is supplied to the lower portion of the fluidized bed 2 through a fuel supply pipe 8 provided on the side wall of the. The fluidized bed 2 is formed on the air dispersion plate 3. As shown in FIG. 2, the air dispersion plate 3 is provided with a plurality of air supply nozzles (air supply ports) 4, 4, ... For supplying the air for flow and combustion. Air dispersion plate 3
A plurality of divided air boxes 16, 16, ... Are provided below the air box, and air flow control valves 15, 15, ... For independently supplying air 9 to the air boxes 16, 16 ,. Is provided. The flow rate of the air supplied from each of the air supply nozzles 4, 4, ... Provided in the dispersion plate 3 is the flow rate of the air supplied to the wind box 16, 16 ,. That is, it is determined by the flow rate of air passing through the air flow rate control valves 15, 15, ... Connected to the wind boxes 16, 16 ,. Therefore, the air amount distribution on the dispersion plate 3 can be controlled by adjusting the air flow rate adjusting valves 15, 15, .... By the way, the fuel 10 supplied from the fuel supply pipe 8 provided on the side wall of the combustor has a distribution that is biased in the horizontal direction in the fluidized bed 2, as described later. Therefore, the compartments of the wind boxes 16, 16, ... Are divided perpendicularly to the fuel supply direction (horizontal direction in the drawing) so as to cope with such an uneven fuel distribution. In addition, this division corresponds to the fuel distribution generated between the fuel supply pipes 10 or from the viewpoint of the strength of the wind box 16, and is also divided in parallel with the fuel supply direction (depth direction in the drawing) to form a grid pattern. You may divide into.

Immediately above the fluidized bed 2, a plurality of gas concentration measuring ends 17a, 17a, ... Are installed in a horizontally dispersed manner. Since the exhaust gas rises almost vertically in the fluidized bed combustor 1, the exhaust gas sampled at each of the measurement ends 17a, 17a, ... Reflects the combustion state at a position immediately below the measurement end. These gas concentration measuring ends 17
The exhaust gas from the fluidized bed 2 sampled by a, 17a, ... Is sent to the gas concentration measuring device 17, where the gas composition at each position is measured. Gas concentration measuring instrument 17
Then, the air ratio at each position is obtained from the predetermined relationship between the gas composition and the air ratio. At the same time, the NOx concentration, the SOx concentration, etc. are also obtained. The measurement result is sent to the control device 5 as a signal.

In the control device 5, the air ratio distribution calculating function 6 for obtaining the air ratio distribution in the horizontal direction of the fluidized bed 2 and the air ratio distribution calculating function 6 are obtained based on the measurement result by the gas concentration measuring device 17. Compare the air ratio distribution with the target air ratio distribution (the air ratio distribution is uniform and the air ratio is 1.2),
So that the air ratio distribution of the fluidized bed 2 approaches the target air ratio distribution,
An air flow rate setting function 7 that determines the air flow rate at each of the air flow rate control valves 15, 15 ,. In the air flow rate setting function 7, first, the basic air flow rate in each control valve 15, 15, ... Is determined from the current fuel supply amount obtained from the fuel supply meter 19, and the air ratio distribution calculation function 6 obtains it. From the difference between the obtained air ratio distribution and the target air ratio distribution, the correction amount for this basic air flow rate is determined, and the final air flow rate is determined. However, this air flow rate is such that the flow velocity in the fluidized bed 2 is equal to or higher than the fluidization start velocity of the fluid medium particles (minimum air flow velocity at which the particle layer is in a fluidized state) and the final velocity (particles are blown away by air). Needless to say, it is controlled within a range that is less than or equal to the air flow rate). The air flow rate of each of the control valves 15, 15, ... Determined in this way is transmitted from the control device 5 to each of the control valves 15, 15, ... As a valve opening control signal 18 of each of the control valves 15, 15 ,. To be done.

Next, the operation and effect of this embodiment will be described. 3 and 4 are predictions of the distribution of the fuel existing amount and the air ratio distribution generated in the fluidized bed 2. In addition,
Here, it is assumed that the distance between the wall where the fuel supply port of the fluidized bed combustor 1 is located and the facing wall is 4 meters. Also, FIG.
Represents the initial stage (state A) of the unsteady state when the amount of air supplied from each air supply nozzle 4, 4, ... Is the same, and assumes an exponential curve as the fuel distribution. The steady state (state B) when the amount of air supplied from the nozzles 4, 4, ... Is the same is shown, and a linear straight line is assumed as the fuel distribution.

When the load of the combustor 1 is increased, the fluidized bed 2
When the amount of fuel fed into the inside of the fluidized bed increases, or when the fuel injection output is weak at the time of low load operation, the amount of fuel existing is large in the portion close to the fuel supply port in the fluidized bed 2 and decreases as the distance from the supply port increases, that is, , The fuel distribution is biased. As shown in FIG. 3, this bias is large in the initial stage (state A) of the unsteady state, and is gradually eliminated by the movement of particles in the fluidized bed 2 as time passes. However, as shown in FIG. 4, even if the fuel supply amount becomes constant and enters the steady state (state B), the fuel 10 is always supplied from the fuel supply port. The bias of will never be completely eliminated.

Here, the movement of particles in the fluidized bed 2 will be specifically considered. The air inflow velocity of the fluidized bed combustor 1 is
In order to secure the fluidized state, the superficial velocity is operated at around 1 meter per second. Since the porosity in the fluidized bed 2 is approximately 0.5, air rises in the fluidized bed 2 at 2 meters per second, and when the bed height is 4 meters, the residence time of air is about 2 seconds. The movement of particles occurs in a form in which air is accompanied by bubbles formed, and the velocity thereof is about 1/4 of air and is about 0.5 meters per second. Therefore, it takes a minimum of 16 seconds for one circulation in which the particles supplied to the bottom of the fluidized bed are carried to the top of the fluidized bed, diffused in the lateral direction, and descend again to the bottom of the bed.

Thus, the moving speed of the particles in the fluidized bed 2 is slow, and it takes a long time to reach a steady state.
Once in the unsteady state, the fuel is burned for a long time with the fuel distribution being largely biased. Therefore, assuming that air is uniformly supplied in the fluidized bed 2 in the horizontal direction, the air ratio distribution also becomes uneven as shown in FIG.

By the way, the relationship between the air ratio and the exhausted NOx is represented by a curve as shown in FIG. That is, NOx emissions
Is rapidly increased from the air ratio of about 1.3, and decreases when the air ratio is about 3. Therefore, FIG. 3 and FIG.
As shown in (1), in the case of the uneven air ratio distribution, the exhausted NOx becomes much larger than in the case where the air ratio distribution is uniform and the air ratio is 1.2.

Therefore, in this embodiment, first, the air ratio at each position in the upper part of the fluidized bed 2 is measured by the gas concentration measuring device 17, and the air ratio distribution calculation function 6 of the control device 5 is used.
The air ratio distribution in the horizontal direction is calculated. And
The valve opening of each of the flow rate control valves 15, 15, ... Is adjusted so that the air ratio distribution becomes a target air ratio distribution (air ratio distribution is uniform and air ratio is 1.2).

Therefore, NOx can be reduced without lowering the overall performance of the fluidized bed combustor 1. Further, since the deviation of the air ratio distribution due to the deviation of the fuel distribution is dealt with by making the distribution of the air supply amount uneven, it is not necessary to install equipment for agitating the fluidized medium, which facilitates maintenance. At the same time, the manufacturing cost can be reduced.

Further, the gas generated as a result of combustion in an unsteady state passes through the fluidized bed in about 2 seconds when the fluidized bed has the above-mentioned conditions, so that the deviation of the air ratio distribution can be grasped in a short time. Further, since the air flow rate of each air flow rate control valve 15, 15, ... Is controlled to cope with the deviation of the air ratio distribution, it is far more than forcibly circulating or stirring the fluid medium by some method. The air ratio distribution can be adjusted quickly. Therefore, the time from when the air ratio distribution becomes unsteady and the air ratio distribution becomes biased until the air ratio distribution becomes constant can be made extremely short.

Here, the NOx reduction effect will be specifically described with reference to FIG. FIG. 6 shows the result of predicting the exhausted NOx concentration in the state A, the state B, and the state C in which the air ratio is 1.2 over the entire fluidized bed using the NOx concentration curve shown in FIG.
111 ppm in state A and 24 pp in state B compared to state C
m, NOx emissions are large. For this reason, even if the non-steady state A is reached, the state C can be immediately brought into the state C, so that a large amount of NOx can be reduced.

In this embodiment, the target air ratio distribution is set to have a uniform air ratio distribution and an air ratio of 1.2. However, this is not always necessary. Specifically, for example, since the combustion temperature is generally low near the outer wall of the fluidized bed combustor 1, the target air ratio near the outer wall of the fluidized bed combustor 1 is set to 1. Alternatively, the target air-fuel ratio at other locations may be set to 1.2. Also, the supplied fuel has a much lower temperature than the burning fuel. Therefore, in the vicinity of the fuel supply port where the fuel existence rate is high, the temperature becomes lower than in other parts. This is remarkable in the non-steady state when the fuel supply amount changes rapidly. Therefore, in order to deal with such temperature distribution,
Different target air ratio distributions may be set in advance according to operating conditions, and the air ratio distribution may be adjusted for each operating condition.

Further, in this embodiment, the fuel supply pipe 8 is provided on the side wall of the fluidized bed combustor 1 so that the fuel is supplied from the side portion of the fluidized bed 2, but the present invention is not limited to this. For example, even when the fuel supply pipe 8 provided on the side wall of the fluidized bed combustor 1 is extended to the vicinity of the central portion of the fluidized bed 2 to supply the fuel to the central portion of the fluidized bed 2. ,
The present invention can be applied. In this case, since the fuel existence rate in the central portion of the fluidized bed 2 becomes high, the air supply amount distribution is set so that the air supply amount in the central portion of the fluidized bed 2 increases.

Next, a second embodiment according to the present invention will be described with reference to FIG. In the present embodiment, the plurality of air supply pipes 28, 28, 28
... are provided. In this example,
In order to support the fluidized bed 2, a layer support plate 30 is provided instead of the air dispersion plate. A plurality of air supply pipes 28, 2
, ... are fuel supply pipes 28 provided on the combustor side wall 21.
Is provided in the vertical direction (parallel to the combustor side wall 21). Each of the air supply pipes 28 is provided with a plurality of air supply nozzles 29, 29, ... In addition, an air flow control valve 15 that is independent for each supply pipe is provided at an inlet portion for sending air to each air supply pipe 28.
Is provided, and the distribution of the air supply amount can be provided in the horizontal direction in the fluidized bed. The flow rate of the air 9 supplied to each air supply pipe 29 is determined by controlling the air flow rate control valve 15 according to the valve opening control signal 18. Further, other configurations are similar to those of the first embodiment.

As described above, also in this embodiment, since the distribution of the air supply amount can be provided in the horizontal direction in the fluidized bed, basically the same effect as that of the first embodiment can be obtained. .

Next, a third embodiment according to the present invention will be described with reference to FIG. The figure shows a state in which the air dispersion plate 3a is viewed from the inside of the fluidized bed combustor.
The air distribution plate 3a has a plurality of air supply nozzles 4, 4, ...
Are provided, and these air supply nozzles 4, 4, ...
Part of the air supply nozzle with valve (black in the figure) 2
2, 22, ... The air supply nozzle 22 with a valve is provided with a flow rate control valve 23 in a portion of the tube below the dispersion plate 3. The flow rate control valve 23 is controlled according to the valve opening control signal 18. Therefore, the flow rate of the air supplied from each valve-equipped nozzle 22, 22, ... Can be adjusted independently for each nozzle, and a distribution in the horizontal direction in the fluidized bed is generated in the supply amount of the air 9 to obtain the target air ratio distribution. Under combustion can be realized.

Next, a fourth embodiment according to the present invention will be described with reference to FIG. In this embodiment, the air dispersion plate 3 is used.
On the b side, a plurality of air supply nozzles 4, 4, ... Are densely provided in a portion near the fuel supply pipe 8 provided on the combustor side wall 21,
The distant parts are sparsely arranged. That is, in the present embodiment, the air supply nozzles 4 are densely arranged in advance under the portion where a large amount of fuel exists, and the air supply amount is increased so that combustion can be performed under the target air ratio distribution. Is.

This embodiment is effective in the case where the combustor structure has a substantially constant fuel distribution regardless of high load, low load, and load fluctuation, and a plurality of air supply nozzles 4, 4 are provided. , ... It becomes unnecessary to control the air flow rate for each, and the manufacturing cost can be reduced.

Next, a fifth embodiment according to the present invention will be described with reference to FIG. In this embodiment, as in the fourth embodiment, a plurality of air supply nozzles 4, 4, ... Are arranged on the air distribution plate 3b densely in a portion close to the fuel supply pipe 8 and sparsely in a far portion. In addition, a part of the supply nozzles of the densely arranged portion is the valve-equipped air supply nozzle 22. The structure of the valve-equipped air supply nozzle 22 is the same as that described in the third embodiment, and the flow control valve 23 is provided in the pipe of the valve-equipped air supply nozzle 22 located below the dispersion plate 3b.
Is provided. Even with such a structure, it is possible to give a distribution to the air supply amount in the fluidized bed and adjust the distribution.

Next, a sixth embodiment according to the present invention will be described with reference to FIGS. This embodiment relates to grasping the air ratio distribution, while the second to fifth embodiments relate to the air supply mechanism. Note that this embodiment is the same as the first embodiment except for the configuration of the air ratio distribution.

In this embodiment, one gas concentration measuring end 17b is provided at the outlet of the combustor 1, and this gas concentration measuring end 17b is provided.
The air ratio distribution in the horizontal direction of the fluidized bed 2 is grasped from the exhaust gas sampled in b. Gas concentration measuring end 1
The exhaust gas sampled at 7b is sent to the gas concentration measuring device 17, as in the first embodiment, where the air ratio, NOx concentration, etc. are obtained.

As will be described later, since there is a certain correlation between the air ratio distribution and the NOx concentration, if this correlation is known in advance, based on the measurement result by the gas concentration measuring device 17, the fluidized bed 2 The air ratio distribution in the horizontal direction can be obtained. Therefore, in the present embodiment, the correlation between the air ratio distribution and the NOx concentration is stored in advance in the air ratio distribution calculation function 6a of the control device 5a, and the air ratio distribution calculation function 6 is stored.
a obtains the air ratio distribution from this correlation.

For example, as shown in FIG. 13, there is a proportional relationship between the distance from the fuel supply port and the existing fuel amount, the fuel ratio at the fuel supply port is W1, and the fuel ratio at the position farthest from the fuel supply port is set. Is W2 and the ratio of both fuel ratios is the fuel uneven distribution ratio (W1 / W2), the relationship between the fuel uneven distribution ratio and the exhausted NOx concentration is as shown in FIG.

That is, as shown in FIG.
x concentration monotonically increases until the fuel uneven distribution ratio reaches 10, and the emission N
If one Ox concentration is determined, one fuel uneven distribution ratio is determined. By the way, the fuel uneven distribution ratio also indirectly indicates the air ratio distribution from the above definition, and therefore, if one exhaust NOx concentration is determined, one air ratio distribution is determined. In this embodiment, the relationship between the exhausted NOx concentration and the air ratio distribution is found, and this relationship is used to grasp the air ratio distribution of the fluidized bed 2 from the NOx concentration at one location.

Next, a seventh embodiment according to the present invention will be described with reference to FIG. In the present embodiment, a plurality of measuring ends 27a, 27a, ... Of the temperature measuring device 27 are horizontally dispersed in the fluidized bed 2, and the temperature at each measuring end 27a, 27a ,. This is to grasp the air distribution. The temperature measuring device 27 includes measuring ends 27a, 27a, ...
The temperature is measured at the position, and the result is sent to the control device 5b.

Generally, the fuel 10 burns well in a large amount of air. Therefore, the temperature becomes high where the air ratio is large. Therefore, if the temperature distribution is known, the air ratio distribution can be grasped. Therefore, in the present embodiment, the air ratio distribution calculating function 6b of the control device 5b causes the measuring ends 27 to
The temperature distribution in the fluidized bed 2 is obtained from the temperatures at the positions a, 27a, ... And the air ratio distribution in the fluidized bed 2 is obtained from this temperature distribution.

In the present embodiment, the plurality of measuring ends 27a, 27a, ... Of the temperature measuring device 27 are arranged inside the fluidized bed 2, but they are arranged on the side wall of the combustor 1 and the fluidized bed 2 is arranged.
The temperature distribution inside may be obtained. Alternatively, the temperature distribution in the fluidized bed 2 may be optically measured directly.

Next, an eighth embodiment according to the present invention will be described with reference to FIG. In this embodiment, the air ratio distribution of the fluidized bed 2 is grasped from the operating state of the fluidized bed combustor 1. Generally, there is a correlation between the operating state of the fluidized bed combustor 1 and the air ratio distribution of the fluidized bed 2. Therefore, the control device 5c of the present embodiment is provided with a correlation storage function 26 in which the correlation data between the operating condition obtained from the test operation result or the simulation calculation and the air ratio distribution is stored. Further, in order to grasp the current operating conditions of the fluidized bed combustor 1, an air flow meter 24 and a pressure gauge 25 are provided in the air supply section to the combustor 1, and a fuel supply meter 19 is provided in the fuel supply section. A gas concentration measuring device 17 is provided at the outlet of the combustor 1. The measurement data obtained by these measuring devices is sent to the air ratio distribution calculating function 6c of the control device 5c, and the air ratio distribution calculating function 6c causes the correlation relationship stored in the correlation storing function 26 with these data. From this, the air ratio distribution of the fluidized bed 2 is obtained.

[0052]

According to the present invention, the horizontal air ratio distribution in the fluidized bed can be immediately brought close to the target air ratio distribution even during low load operation or load fluctuation, and basically the target is always maintained. Since the air ratio distribution can be maintained, NOx generation can be suppressed without degrading the overall performance of the combustor.

Further, since the deviation of the air ratio distribution due to the deviation of the fuel distribution in the fluidized bed is dealt with by making the distribution of the air supply amount uneven, it is not necessary to install equipment for stirring the fluidized medium. As a result, the inside of the fluidized bed is not complicated, the reliability is enhanced, maintenance is facilitated, and the manufacturing cost can be reduced. Further, since the moving speed of air is much faster than the moving speed of the fluidized medium, the present invention which changes the air supply amount at each position of the fluidized bed is more effective than forced circulation or stirring of the fluidized medium. The time required to reach the target air-fuel ratio in the fluidized bed can be shortened.

[Brief description of drawings]

FIG. 1 is a system diagram of a fluidized bed combustor facility according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of an air supply mechanism of the first embodiment according to the present invention.

FIG. 3 is an explanatory diagram showing a fuel distribution and an air ratio distribution in an initial stage (state A) in which the inside of a fluidized bed is in an unsteady state when the amount of air supplied from each air supply nozzle is the same.

FIG. 4 is an explanatory diagram showing a fuel distribution and an air ratio distribution when the amount of air supplied from each air supply nozzle is the same and the inside of the fluidized bed is in a steady state (state B).

FIG. 5 is a graph showing the relationship between air ratio and exhaust NOx concentration.

FIG. 6 is an explanatory diagram showing the relationship between various states and exhausted NOx concentration.

FIG. 7 is an explanatory diagram showing a configuration of an air supply mechanism of a second embodiment according to the present invention.

FIG. 8 is an explanatory diagram showing a configuration of an air supply mechanism according to a third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing the configuration of an air supply mechanism of a fourth embodiment according to the present invention.

FIG. 10 is an explanatory diagram showing a configuration of an air supply mechanism of a fifth embodiment according to the present invention.

FIG. 11 is a system diagram of fluidized bed combustion equipment according to a sixth embodiment of the present invention.

FIG. 12 is a graph showing a relationship between a fuel uneven distribution ratio and exhaust NOx concentration.

FIG. 13 is a graph showing the relationship between the distance from the fuel supply pipe and the fuel ratio.

FIG. 14 is a system diagram of fluidized bed combustion equipment according to a seventh embodiment of the present invention.

FIG. 15 is a system diagram of fluidized bed combustion equipment according to an eighth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fluidized bed combustor, 2 ... Fluidized bed, 3, 3a, 3b ... Air dispersion plate, 4 ... Air supply nozzle, 5, 5a, 5b, 5c ...
Control device, 6, 6a, 6b, 6c ... Air ratio distribution calculation function, 7 ... Air flow rate setting function, 8 ... Fuel supply pipe, 9 ... Air, 10 ... Fuel, 11 ... Air compressor, 12 ... Gas turbine, 13 ... Generator, 14 ... Pressure vessel, 15 ... Air flow rate control valve, 16 ... Wind box, 17 ... Gas concentration measuring device, 17a,
17b ... Gas concentration measuring end, 18 ... Valve opening control signal, 19
... Fuel supply meter, 20 ... Cyclone, 21 ... Combustor side wall, 22 ... Air supply nozzle with valve, 23 ... Flow control valve, 2
4 ... Air flow meter, 25 ... Pressure gauge, 26 ... Correlation memory recording function, 27 ... Temperature measuring device, 27a ... Temperature measuring end, 30
… Layer support plate.

Front Page Continuation (72) Inventor Takeshi Suzumura 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory

Claims (13)

[Claims] 1. A fluidized bed combustion facility comprising a fluidized bed combustor having a fluidized bed formed of a fluidized medium formed therein, and supplying fuel and air into the fluidized bed to burn the fuel. The air ratio distribution grasping means for grasping the horizontal air ratio distribution in the bed, and the air ratio distribution grasped means for supplying the air ratio distribution into the fluidized bed so as to become a target air ratio distribution predetermined according to various conditions. A fluidized bed combustion facility comprising: an air supply amount distribution adjusting means for adjusting an air supply amount distribution in the horizontal direction of air. 2. The air supply amount distribution adjusting means sends to each of a plurality of air supply ports in which the locations for supplying the air in the fluidized bed are horizontally dispersed, and a plurality of the air supply ports. A plurality of air flow rate adjusting means for adjusting the flow rate of the air, and a plurality of the air ratio distribution means for grasping the air ratio distribution grasping means to obtain a predetermined target air ratio distribution according to various conditions. The fluidized bed combustion equipment according to claim 1, further comprising: an air flow rate setting unit that determines each air flow rate adjusted by the flow rate adjusting unit. 3. A fluidized bed combustion facility comprising a fluidized bed combustor having a fluidized bed formed of a fluidized medium formed therein, and supplying fuel and air into the fluidized bed to burn the fuel. Fluidized bed combustion characterized in that a plurality of air supply ports for supplying the air into the bed are dispersed in the horizontal direction, and are arranged in the vicinity of the location to which the fuel is supplied more than other locations. Facility. 4. An air flow rate adjusting means for adjusting a flow rate of air sent to at least one of the plurality of air supply ports, and an air ratio distribution grasp for grasping a horizontal air ratio distribution in the fluidized bed. Means and air flow rate setting means for determining the air flow rate adjusted by the air flow rate adjusting means so that the grasped air ratio distribution approaches a predetermined target air ratio distribution according to various conditions. The fluidized bed combustion facility according to claim 3. 5. The air ratio distribution grasping means has a plurality of sampling units arranged horizontally in the upper space of the fluidized bed or in the fluidized bed so as to sample the exhaust gas from the fluidized bed. Then, from the air ratio measuring means for measuring the air ratio of each of the exhaust gases sampled by a plurality of sampling units, and the air ratio of each of the exhaust gases sampled by a plurality of sampling units, The fluidized bed combustion equipment according to claim 1, 2 or 4, further comprising: an air ratio distribution calculating means for obtaining an air ratio distribution in a horizontal direction. 6. The air ratio distribution grasping means samples the exhaust gas from the fluidized bed and measures the concentration of the component gas in the exhaust gas, and the predetermined component gas. And a horizontal air ratio distribution in the fluidized bed, and an air ratio distribution calculating means for obtaining a horizontal air ratio distribution in the fluidized bed from the measured concentration of the component gas. It has, The fluidized bed combustion equipment of Claim 1, 2 or 4 characterized by the above-mentioned. 7. The air ratio distribution grasping means obtains a temperature distribution grasping means for grasping a horizontal temperature distribution of the fluidized bed, and obtains a horizontal air ratio distribution of the fluidized bed from the grasped temperature distribution. The fluidized bed combustion equipment according to claim 1, 2 or 4, further comprising: an air ratio distribution calculating means. 8. An operating state grasping means for grasping an operating state of the fluidized bed combustor, wherein the air ratio distribution grasping means is configured to determine a predetermined operating state and a horizontal air ratio distribution of the fluidized bed. And an air ratio distribution calculating means for obtaining a horizontal air ratio distribution of the fluidized bed based on the above relationship and the operating conditions grasped by the operating condition grasping means. Or a fluidized bed combustion facility according to 4. 9. The fluidized bed according to claim 1, 2 or 4, wherein the target air ratio distribution is an air ratio distribution in which air ratios at respective locations in the horizontal direction of the fluidized bed are substantially uniform. Combustion equipment. 10. The target air ratio distribution is an air ratio distribution in which the air ratio at each location in the horizontal direction of the fluidized bed is equal to or greater than the theoretical air ratio. Fluidized bed combustion equipment. 11. A method for operating a fluidized bed combustion facility, comprising a fluidized bed combustor having a fluidized bed formed of a fluidized medium formed therein, and supplying fuel and air into the fluidized bed to burn the fuel. A method for operating a fluidized bed combustion facility, comprising supplying more air to a portion having a high fuel abundance in the horizontal direction in the fluidized bed than to supplying a portion having a low fuel abundance. 12. A method of operating a fluidized bed combustion facility, comprising a fluidized bed combustor having a fluidized bed formed of a fluidized medium formed therein, and supplying fuel and air into the fluidized bed to burn the fuel. Ascertaining the horizontal air ratio distribution in the fluidized bed, the horizontal direction of the air supplied to the fluidized bed so that the grasped air ratio distribution becomes a target air ratio distribution that is predetermined according to various conditions. A method for operating a fluidized bed combustion equipment, which comprises adjusting an air supply amount distribution in a fuel cell. 13. An air ratio distribution measuring device for measuring an air ratio distribution in a fluidized bed, comprising: a gas concentration measuring means for measuring a concentration of a component gas in exhaust gas from the fluidized bed; An air ratio distribution for calculating the air ratio distribution of the fluidized bed from the correlation between the predetermined component gas concentration and the air ratio distribution of the fluidized bed, and the concentration of the component gas measured by the gas concentration estimating means. An air ratio distribution measuring device comprising: a calculating unit.