JPH08121711A - Pulverized coal combsition method and pulverized coal combustion device and pulverized coal burner - Google Patents

Abstract

PURPOSE: To provide a combustion device provided with a pulverized coal burner being able to decrease a generation quantity of NOx during usage of a plurality of coal kinds. CONSTITUTION: Coal is fractionated according to a nitrogen content including quantity through an ultimate anabysis, and a supplying to pulverized coal burners 52, 53 is executed respectively. Coal having a large nitrogen content is supplied to the pulverized coal burner 52 injecting pulverized coal to a region having an air ratio less than 1 in a combustion room 11, and less nitrogen content including coal is supplied to the pulverized coal burner 53 injecting pulveized coal to a region having an air ratio of 1 and more. By this, NOx generating quantity is, in a reduction region, receive no influence from a nitrogen content of coal. Therefore, if coal having a large nitrogen content is supplied, in the reduction region having an air ratio being less then than 1, reducing type nytrogen compounds such as NH3 , HCN and the like are largely produced and NOx generation quantity can be largely decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulverized coal combustion method, a pulverized coal combustion device, and a pulverized coal burner used in the pulverized coal combustion device, and more particularly to nitrogen oxidation of a pulverized coal combustion device using a plurality of coal species. The present invention relates to a combustion method and a combustion means for reducing the amount of substances.

[0002]

2. Description of the Related Art So-called fossil fuel contains nitrogen components in addition to fuel components such as carbon and hydrogen. Nitrogen oxides (NOx) produced by the oxidation of this nitrogen component during combustion are air pollutants and are desired to be reduced as much as possible.
Particularly in the combustion of coal, the content of nitrogen in the fuel is higher than that of other gas fuels and liquid fuels. Therefore, the amount of NOx produced during combustion of coal depends on the amount of NOx produced during combustion of gaseous fuel or the like.
It is more than x production amount, and its reduction is an important issue.

The NOx generated during combustion of various fuels depends on the generation factors of thermal NOx and fuel NOx.
Be sorted into Thermal NOx is a compound produced by oxidizing nitrogen in combustion air in a high temperature atmosphere.
On the other hand, fuel NOx is a compound produced by oxidizing the nitrogen content contained in fuel. In the case of pulverized coal combustion, nearly 80% of the NOx generated is fuel NOx.
Therefore, reduction of fuel NOx is important for reducing NOx as a whole.

Combustible components in coal can be roughly classified into volatile components and solid components. The combustion mechanism of pulverized coal includes a thermal decomposition process in which volatile components are released from the coal and a combustion process of combustible solid components, that is, char. Among these, the volatile components burn in the initial stage of combustion. The nitrogen content contained in coal is divided into volatile components and those remaining in char, like other combustible components.

Volatile nitrogen is a component of the early stages of combustion and
In the oxygen-deficient combustion region, NH ₃, HCN and other nitrogen
It is known to be a compound. Nitrogen compounds are oxygen
Reacts with NOx and reacts with NOx to NOx
Causes a reduction reaction that decomposes nitrogen into nitrogen. Has this reducibility
NOx reduction reaction by nitrogen compounds
It's easy to progress.

On the other hand, as a method for reducing NOx generated from the nitrogen content remaining in the char, the nitrogen content in the char is once released as a gas, and NOx
The method of reducing what is released as nitrogen to nitrogen is effective. To release nitrogen in char as gas,
It is necessary to completely burn the char. Therefore, complete combustion is an essential element in low NOx combustion of pulverized coal.

As described above, as a method for reducing the NOx emission amount during the combustion of pulverized coal, a combustion method in which a reducing nitrogen compound and char coexist with NOx and NOx is reduced to nitrogen by the reducing nitrogen compound Is effective.

A combustion method in which fuel is divided and supplied based on such a policy is described in, for example, Japanese Patent Publication No. 55-21922. In this combustion method, a plurality of pulverized coal burners are used to perform two-stage combustion of fuel. The two-stage combustion method includes a step of burning a pulverized coal mixture jetted from the main pulverized coal burner at an air ratio of 1 or more, and NOx.
To supply fuel from the second stage pulverized coal burner to form a reduction region with an air ratio of less than 1, and to supply air from the air inlet to completely burn excess fuel. Become.

Further, Japanese Examined Patent Publication No. 4-47204 discloses means for clearly distinguishing a reducing region having an air ratio of less than 1 and a region having an air ratio of 1 or more in a single pulverized coal burner. . In this combustion method, by making the reduction region wide, a large amount of reducing nitrogen compounds such as NH ₃ and HCN are generated in this reduction region to reduce NOx.

[0010]

By the way, in general, N
Since attempts to reduce the Ox emission amount tend to increase the release of the unburned component, it is important to form the reduction region so as to reduce the NOx emission amount and the unburned component at the same time. In particular, in recent years, coal types used in pulverized coal combustion have diversified, and there is an increasing demand for simultaneous combustion of multiple coal types. When burning multiple coal types simultaneously, N in the reduction region
It tends to be difficult to balance the amount of reducing nitrogen compounds such as H ₃ and HCN generated with the amount of NOx, which may lead to a rapid increase in NOx emissions.

An object of the present invention is to provide NH in the reduction region formed in the flame in a combustion device using a plurality of coal species.
₃ , a pulverized coal combustion method and a pulverized coal combustion apparatus and a pulverized coal combustion apparatus which generate a large amount of reducing nitrogen compounds such as HCN and significantly reduce NOx emissions by the reducing action of these reducing nitrogen compounds The purpose is to provide a pulverized coal burner.

[0012]

In order to achieve the above object, the present invention provides a pulverized coal combustion method in which coals of a plurality of coal types are individually supplied to a plurality of pulverized coal burners and burned. Of coal is preliminarily fractionated according to the nitrogen content obtained by elemental analysis, and the air ratio (= the ratio of the actual input air amount to the air amount necessary for complete combustion of pulverized coal) is 1
The pulverized coal burner that injects a mixture of pulverized coal and air into the area below is supplied with coal having a high nitrogen content among the separated coal, and the air ratio of 1 or more A pulverized coal combustion method is proposed in which pulverized coal burner for ejecting air-fuel mixture is supplied with coal having a small nitrogen content among the fractionated coals.

In order to achieve the above object, the present invention also provides a pulverized coal combustion method in which coals of a plurality of coal types are individually supplied to and burned by a plurality of pulverized coal burners. The pulverized coal burner, which was previously fractionated according to the nitrogen content obtained by the analysis and whose air ratio was set to less than 1, was supplied with coal having a high nitrogen content among the fractionated coals, and the air ratio was changed. For the pulverized coal burner set to 1 or more, a pulverized coal combustion method is proposed in which coal having a small nitrogen content content among the fractionated coals is supplied.

Further, in order to achieve the above object, the present invention further supplies coals of a plurality of coal types to a plurality of pulverized coal burners individually and finally supplies excess air from an air charging port to load the coals. In the pulverized coal combustion method for complete combustion,
According to the content of nitrogen content obtained by elemental analysis of coal of multiple coal species in advance, the pulverized coal burner located away from the air inlet, the content of nitrogen content of the fractionated coal It proposes a pulverized coal combustion method in which a large amount of coal is supplied and a pulverized coal burner located near the air inlet is supplied with coal having a small nitrogen content among the separated coal.

In any of the above pulverized coal combustion methods,
Until the specified load is reached after the pulverized coal burner is activated, only coal with a low nitrogen content is supplied to the pulverized coal burner and the coal with a low nitrogen content is supplied above the specified load. Alternatively, coal having a high nitrogen content may be supplied in parallel to each pulverized coal burner.

Further, the combustion state is monitored, and when the combustion state satisfies a predetermined condition, a part of the separated coal can be mixed and supplied to at least one of the pulverized coal burners.

Furthermore, when the coal is fractionated according to the nitrogen content, the relative difference in the average nitrogen content obtained by elemental analysis is set to 0.1 (wt%) or more.

In order to achieve the above-mentioned object, the present invention has a plurality of pulverized coal burners in the vertical direction or the opposite direction, and supplies fine coal powder of a plurality of coal types to the plurality of pulverized coal burners individually for combustion. In a charcoal combustor, a coal storage yard that preliminarily separates and stores coal of multiple coal types according to the nitrogen content obtained by elemental analysis, a pulverized coal machine that individually pulverizes the separated coal, and an air ratio. With a ratio of less than 1 for supplying a pulverized coal burner for injecting a mixture of pulverized coal and air to the pulverized coal burner having a high nitrogen content in the pulverized coal burner; The present invention proposes a pulverized coal combustion apparatus including means for supplying pulverized coal having a small nitrogen content in the pulverized coal burner for ejecting an air-fuel mixture.

In order to achieve the above object, the present invention further comprises a plurality of pulverized coal burners in the vertical direction or the opposite direction, and coals of a plurality of coal types are individually supplied to the plurality of pulverized coal burners and burned. In the pulverized coal combustion apparatus, a coal storage place for preliminarily fractionating and storing coal of a plurality of coal types according to the nitrogen content obtained by elemental analysis, and a pulverized coal machine for individually pulverizing the fractionated coal, A means for supplying the pulverized coal burner with an air ratio set to less than 1 with a high nitrogen content in the pulverized coal burner, and a pulverized coal burner with an air ratio set to 1 or more have a nitrogen content in the pulverized coal burner. The present invention proposes a pulverized coal combustion apparatus provided with a means for supplying pulverized coal having a low content.

In order to achieve the above object, the present invention further has a plurality of pulverized coal burners in the vertical direction or the opposite direction, and supplies coal of a plurality of coal types to the plurality of pulverized coal burners individually. In a pulverized coal combustor that injects excess air from the air inlet to completely burn coal, a coal storage yard that separates and stores coal of multiple coal types in advance according to the nitrogen content obtained by elemental analysis, and Pulverized coal machine for individually pulverizing the pulverized coal, a means for supplying pulverized coal with a high nitrogen content of the pulverized coal to a pulverized coal burner located at a position away from the air inlet, and an air inlet The present invention proposes a pulverized coal combustion device provided with a means for supplying pulverized coal having a small nitrogen content in the pulverized coal burner located at a close position.

In any of the pulverized coal combustion apparatuses, a plurality of pulverized coal burners provided in opposite directions are arranged so that flames formed by the pulverized coal burners having different air ratios or coal types collide with each other. You may incline and arrange with respect to the furnace wall surface.

In order to achieve the above object, the present invention comprises a plurality of pulverized coal burners which are arranged concentrically and eject a mixture of pulverized coal and air, and means for supplying combustion air to the periphery thereof. In a pulverized coal combustion device that has a plurality of coal types and supplies them to multiple pulverized coal burners individually and burns them, the coals of multiple coal types are separated in advance according to the nitrogen content obtained by elemental analysis. The coal yard that stores and stores, the pulverized coal machine that pulverizes the separated coal individually, and the pulverized coal burner inside the concentric pulverized coal burner It proposes a pulverized coal combustion device provided with a means for supplying and a means for supplying pulverized coal having a small nitrogen content in the pulverized coal to the outer pulverized coal burner of the concentric pulverized coal burners. is there.

At the center of the concentric circles, it is possible to provide an auxiliary fuel nozzle for supplying liquid or gaseous auxiliary fuel to the jet region of the air-fuel mixture.

In order to achieve the above object, the present invention provides a first pulverized coal burner for ejecting a mixture of pulverized coal and air, and a pulverized coal of a coal type different from that of the pulverized coal arranged close to and above and below the first pulverized coal burner. A second pulverized coal burner for ejecting an air-fuel mixture and means for supplying combustion air, which are arranged vertically above and below the second pulverized coal burner, are provided to individually supply coal of a plurality of coal types to a plurality of pulverized coal burners. In a pulverized coal combustion device that burns, a coal storage place that preliminarily sorts and stores coal of multiple coal types according to the nitrogen content obtained by elemental analysis, and a pulverized coal machine that individually pulverizes the sorted coal. A means for supplying the first pulverized coal burner with pulverized coal having a high nitrogen content in the pulverized coal, and a means for supplying the second pulverized coal burner with a pulverized coal having a low nitrogen content. To propose a pulverized coal combustion device equipped with That.

In any of the above pulverized coal combustion devices,
A means for monitoring the load of the pulverized coal burner is provided, and only the means for supplying pulverized coal with a low nitrogen content to the pulverized coal burner is activated until the prescribed load is reached after the pulverized coal burner is activated. When the load is higher than, the means for supplying the pulverized coal burner with a low nitrogen content and the means for supplying the pulverized coal with a high nitrogen content can be operated in parallel.

Further, a means for monitoring the combustion state and a means for mixing a part of the pulverized coal having different coal types are provided. When the combustion state satisfies a predetermined condition, a part of the pulverized coal having a different coal type is provided. It can be mixed and fed to at least one of the pulverized coal burners.

Further, when the coal is sorted according to the nitrogen content and stored in the coal stock yard, the relative difference in the average nitrogen content obtained by elemental analysis is 0.1 (wt%) or more. Is desirable.

In order to achieve the above object, the present invention provides a pulverized coal burner of a pulverized coal combustion apparatus for individually supplying and burning coals of a plurality of types of coal, and the mixture of pulverized coal and air arranged concentrically. A plurality of primary fuel nozzles for ejecting air, a secondary air nozzle arranged on the outer periphery of the primary fuel nozzle for supplying combustion air, a swirl flow generator for forming a swirl flow in the air from the secondary air nozzle, and a concentric circle The primary fuel supply pipe that supplies the pulverized coal having a high nitrogen content among the pulverized coal to the inner primary fuel nozzle and the concentric outer primary fuel nozzle to The present invention proposes a pulverized coal burner provided with a primary fuel supply pipe for supplying a small amount of pulverized coal and a sleeve formed at the outlet of the primary fuel nozzle and expanding toward the combustion chamber side of the pulverized coal burner.

In order to achieve the above-mentioned object, the present invention also jets a mixture of pulverized coal and air in a pulverized coal burner of a pulverized coal combustion apparatus which individually supplies and burns coal of plural types of coal. Inner primary fuel nozzle and inner 1
The secondary fuel nozzle is arranged concentrically with the primary fuel nozzle facing the combustion chamber and protruding from the primary fuel nozzle on the inner side to eject a mixture of pulverized coal and air. Secondary air nozzle for supplying air and 2
A swirling flow generator that forms a swirling flow in the air from the secondary air nozzle, and a primary fuel supply pipe that supplies pulverized coal with a high nitrogen content in the pulverized coal to the concentric inner primary fuel nozzle. , A combustion of a pulverized coal burner formed at a primary fuel supply pipe for supplying pulverized coal having a small nitrogen content in the pulverized coal to the concentric outer primary fuel nozzle and an outlet of the outer primary fuel nozzle The present invention proposes a pulverized coal burner including a sleeve that widens toward the room side.

In these pulverized coal burners, it is possible to equip the central portion of the concentric circle with an auxiliary fuel nozzle for supplying the liquid or gaseous auxiliary fuel to the jetting region of the air-fuel mixture.

[0031]

In analyzing the combustion of pulverized coal, the inventors paid attention to the relationship between the amount of nitrogen contained in coal and the air ratio in the gas phase. Here, the air ratio represents the ratio between the actual air amount and the air amount required to completely burn the fuel. Further, the gas phase air ratio represents the ratio of the actual air amount to the air amount required to completely burn the volatile components in the coal.

According to the experiments conducted by the inventors, in a high-temperature reducing atmosphere, regardless of the combustion temperature, the coal particle size, and the coal properties (particularly the nitrogen content), the gas phase air ratio was used as an index. It became clear that the amount of NOx produced is determined.

FIG. 1 is a diagram showing an example of the results of an experiment conducted by the inventors for obtaining the relationship between the gas phase air ratio and the amount of NOx produced in a laminar flow combustion furnace. In this case, as the fuel, as shown in Table 1, four types of coal having a fuel ratio of 0.9 to 2.5 and a nitrogen content of 1.0 to 2.2 wt% were used. ing.

[0034]

[Table 1]

As is clear from FIG. 1, when the air ratio in the gas phase exceeds 0.9, that is, when it is 1 or more, the amount of NOx produced is large depending on the amount of nitrogen contained in the coal. different. However, when the gas-phase air ratio is 0.9 or less, NO is determined based on only the gas-phase air ratio regardless of the amount of nitrogen content contained in the coal, that is, regardless of the type of coal.
The amount of x generated can be specified. From this experimental result, when the air ratio is 1 or more, the NOx production amount increases when coal having a large nitrogen content is used. On the other hand, in the reduction region where the air ratio is less than 1, it can be concluded that the NOx production amount is not affected by the nitrogen content of coal.

Therefore, in the present invention, in a combustion apparatus using a plurality of coal species, the coal is fractionated in advance according to the nitrogen content obtained by elemental analysis, and the coal is supplied to individual pulverized coal burners. At this time, coal having a large nitrogen content is supplied to the reduction region having an air ratio of less than 1. In the reduction region where the air ratio is less than 1, the NOx emission amount is not affected by the amount of nitrogen content contained in coal. Further, coal having a low nitrogen content is supplied to a region having an air ratio of 1 or more. In the region where the air ratio is 1 or more, the NOx emission amount changes depending on the amount of nitrogen content contained in coal.

Conventionally, when coal with a large amount of nitrogen contained in coal was mixed and burned, the NOx emission amount was also increased. On the other hand, according to the present invention, when coal is separated according to the nitrogen content and coal with a large nitrogen content is supplied to a region where the air ratio is less than 1, the NOx emission amount can be reduced.

The first element of the present invention is that, in the process of storing and supplying pulverized coal, the coal is separated according to the content of nitrogen content obtained by elemental analysis, and separately stored, crushed and transported. .

The second element of the present invention is to supply coal having a large nitrogen content among coal classified according to the nitrogen content to a region where the air ratio in the flame is less than 1, Is to supply coal with a small content of min to a region where the air ratio in the flame is 1 or more.

[0040]

EXAMPLES Examples of a pulverized coal combustion method, a pulverized coal combustion apparatus, and a pulverized coal burner used in the pulverized coal combustion apparatus according to the present invention will now be described with reference to FIGS.

<< First Embodiment >> FIG. 2 is a diagram showing a system configuration of a first embodiment of a combustion apparatus according to the present invention having pulverized coal burners provided in upper and lower two stages. In the first embodiment, coal is
It is sorted according to the nitrogen content, and stored in the coal storage stations 41, 42. The coal in the coal storage yard 41, 42 is separately supplied to the pulverized coal machines 45, 46 from the hoppers 43, 44, respectively,
Pulverized. The pulverized coal is blower 47,48
It is carried to the pulverized coal burners 52 and 53 together with the carrier air from. On the other hand, the combustion air is supplied by the blower 49.

When coals of a plurality of coal types are simultaneously burned, the coals are previously fractionated according to the nitrogen content obtained by elemental analysis of the coals, and each of the pulverized coal burners 5 is separated.
Supply to 2,53. In the combustion device, excess air is finally contained in the combustion chamber 11 for the purpose of completely burning the coal.
It is introduced from the air inlet 54. Therefore, even when the air ratios of the respective stages are the same, the actual air ratio becomes higher in the pulverized coal burner 53 in the upper stage near the air inlet 54. Therefore, the pulverized coal burner 52 in the lower stage is supplied with coal having a higher nitrogen content among the coals classified according to the nitrogen content, and the pulverized coal burner 53 in the upper stage contains the nitrogen content. Among the coals sorted according to the amount, coal with a low nitrogen content is supplied.

As is clear from the experimental results of the inventors already described with reference to FIG. 1, the NOx amount produced is not affected by the nitrogen content of coal in the reduction region where the air ratio is less than 1. Therefore, coal having a low nitrogen content is supplied to the region where the air ratio in which the amount of NOx produced is affected by the nitrogen content is 1 or more. In addition, in the reduction region where the air ratio is less than 1, which is not affected by the nitrogen content of coal,
Supply coal with a high nitrogen content. In this way, the amount of NOx generated as a whole can be suppressed low.

To show the effect of the first embodiment of FIG. 2, FIG. 3 shows the relationship between the difference in the nitrogen content of coal and the difference between the NOx amount discharged by the conventional method and the NOx amount discharged by the present invention. It is a characteristic diagram. That is, in the combustion device of the first embodiment of the present invention having the upper and lower pulverized coal burners shown in FIG. 2, the fuel ratio is 0.9 to 2.5, and the nitrogen content is 1.0 to 1.0.
The results of experiments using four types of 2.2 (wt%) coal are shown.

In this experiment, the air ratio of each pulverized coal burner was set to the same, but as described above, the actual air ratio of each stage is different, and the pulverized coal burner 53 in the upper stage has an air ratio of 1. It was 0, and it was 0.8 in the lower pulverized coal burner 52. The horizontal axis of FIG.
It shows the difference in the average nitrogen content of each coal type used when a plurality of coal types having different nitrogen contents were burned. The vertical axis of FIG. 3 indicates the combustion device outlet 5 when the coals of a plurality of coal types are premixed and burned and when the coals of a plurality of coal types are separately burned by the combustion method of the present invention.
5 shows the difference in NOx emission amount in No. 5.

For example, the nitrogen content is 1.4 (wt%)
Consider the case of burning the coal A and the coal C having a nitrogen content of 1.9 (% by weight). At this time, in the case of the conventional method in which coal A and coal C are mixed and supplied in advance,
The amount of NOx produced in the upper pulverized coal burner 53 is about 53
It becomes 0 ppm (6% O ₂ ).

On the other hand, in the case of the present invention in which coal is separated according to the nitrogen content and coal A having a relatively low nitrogen content is supplied to the region where the air ratio is less than 1, fine powder in the upper stage is used. The nitrogen content of the coal supplied to the charcoal burner 53 is 1.4.
(Wt%), NOx production is about 410ppm (6%
O ₂ ). That is, compared with the conventional method, the amount of NOx generated in the upper pulverized coal burner 53 is about 120 ppm (6%
O ₂ ).

On the other hand, in the reducing region where the air ratio is less than 1, the amount of NOx produced is not affected by the nitrogen content of coal and is determined only by the air ratio. Lower pulverized coal burner flame 56
When the air ratio is 0.8, the amount of NOx produced does not change depending on the nitrogen content of the coal and is about 100 ppm (6% O ₂ ). Therefore, in the conventional method in which coal composed of a plurality of coal types is mixed in advance and supplied, NOx at the combustor outlet 55 is used.
The amount will be about 320 ppm (6% O ₂ ).

On the other hand, in the combustion method according to the present invention, the NOx emission amount is about 260 ppm (6% O ₂ ), which is about 6 ppm.
It is about 0 ppm (6% O ₂ ) lower.

As shown in FIG. 3, even in the case where the relative nitrogen content of a plurality of coal types is 0.1 (wt%), the same effect can be obtained. Under the combustion conditions shown, the NOx emission amount is about 20 ppm (6% O ₂ ) lower.

Further, if the air ratio of the mixture of coal and air ejected from the pulverized coal burner 53 in the upper stage is made lower than the air ratio of the mixture of coal and air ejected from the pulverized coal burner 52 in the lower stage, NOx emissions are reduced. It is even more effective in reducing the amount.

In the embodiment shown in FIG. 2, the setting of the air ratio of each pulverized coal burner was the same and the actual air ratio in the flame was different. However, the setting of the air ratio of the pulverized coal burner was changed. In this case, it will be apparent that the present invention can be similarly applied.

<Second Embodiment> FIG. 4 is a diagram showing a system configuration of a second embodiment of a combustion apparatus in which a sensor for monitoring a combustion state and a pulverized coal mixer are additionally installed in the first embodiment of FIG. Is. The sensor 50 provided in the combustion chamber 11 is configured to detect the oxygen concentration, carbon monoxide concentration, NOx concentration,
The combustion state such as the unburned amount in the coal and the flame temperature in the combustion chamber 11 is monitored. The pulverized coal mixer 51 provided in the pulverized coal supply path is based on the combustion state measured by the sensor 50.
This is a means for separating a part of pulverized coal which is separated according to the content of nitrogen in the coal and conveyed in a plurality of systems. If at least one of the pulverized coal burner 52 and the pulverized coal burner 53 is supplied with the pulverized coal in which the coal species to be conveyed to another pulverized coal burner is mixed by the pulverized coal mixer 51, the combustion state of each pulverized coal burner can be improved. It is possible to adjust and adjust the NOx emission amount generated as a whole.

<< Third Embodiment >> FIG. 5 is a diagram showing a system configuration of a third embodiment of a combustion apparatus according to the present invention in which pulverized coal burners are arranged to face each other. The first embodiment shown in FIG. 2 was a front combustion type combustion device having a plurality of pulverized coal burners in the vertical direction, but the present invention is also applied to the case of the opposed combustion type combustion device shown in FIG. Therefore, the NOx emission amount at the combustion device outlet 55 can be further reduced.

That is, in the case of the third embodiment, the flames formed by the pulverized coal burners having different air ratios or coal types can be made to collide with each other. The reducing nitrogen compound generated in the flame formed by one of the pulverized coal burners 52 with a low air ratio is set to the pulverized coal burner 5 with a high air ratio.
It is directly mixed with NOx produced in the flame formed in 3. In this case, the reducing nitrogen compound does not come out of the flame and is therefore difficult to be oxidized, so that a reducing reaction with NOx is likely to occur. As a result, the NOx emission amount is further reduced as compared with the case where the flames do not collide with each other.

<Fourth Embodiment> FIG. 6 is a diagram showing a system configuration of a fourth embodiment of a combustion apparatus in which a sensor for monitoring a combustion state and a pulverized coal mixer are additionally installed in the third embodiment of FIG. Is. The sensor 50 provided in the combustion chamber 11 is configured to detect the oxygen concentration, carbon monoxide concentration, NOx concentration,
The combustion state such as the unburned amount in the coal and the flame temperature in the combustion chamber 11 is monitored. The pulverized coal mixer 51 provided in the pulverized coal supply path is based on the combustion state measured by the sensor 50.
This is a means for separating a part of pulverized coal which is separated according to the content of nitrogen in the coal and conveyed in a plurality of systems. If at least one of the pulverized coal burner 52 and the pulverized coal burner 53 is supplied with the pulverized coal in which the coal species to be conveyed to another pulverized coal burner is mixed by the pulverized coal mixer 51, the combustion state of each pulverized coal burner can be improved. It is possible to adjust and adjust the NOx emission amount generated as a whole.

<Fifth Embodiment> FIG. 7 is a diagram showing a system configuration of a fifth embodiment of a combustion apparatus according to the present invention in which a pulverized coal burner is arranged so as to be inclined with respect to a furnace wall surface. The first embodiment shown in FIG. 2 was a front combustion type combustion apparatus having a plurality of pulverized coal burners in the vertical direction. However, the pulverized coal burners are arranged so as to be inclined with respect to the wall surface of the furnace, and are placed in the combustion chamber 11. The invention of the present application can be similarly applied to the case of the combustion method of forming the swirling flow, and the NOx emission amount at the combustion device outlet 55 can be further reduced.

That is, in the case of the fifth embodiment, the flames formed by the pulverized coal burners having different air ratios or coal types can be made to collide with each other. The reducing nitrogen compound generated in the flame 70 formed by the pulverized coal burner 52 with a low air ratio is set to the pulverized coal burner 5 with a high air ratio.
It is directly mixed with NOx generated in the flame 71 formed in 3. In this case, the reducing nitrogen compound does not come out of the flame and is therefore difficult to be oxidized and easily causes a reducing reaction with NOx. As a result, the NOx emission amount is further reduced as compared with the case where the flames do not collide with each other.

<< Sixth Embodiment >> FIG. 8 is a diagram showing a system configuration of a sixth embodiment of a combustion apparatus according to the present invention for suppressing the NOx emission amount by burning pulverized coal of a plurality of coal types in each burner unit. Is. Also in the sixth embodiment, coal is sorted according to the content of nitrogen and stored in the coal storage sites 41, 42. The coals in the coal stockyards 41 and 42 are separately supplied from the hoppers 43 and 44 to the pulverized coal machines 45 and 46 to be pulverized. The pulverized coal is conveyed to the pulverized coal burner 10 together with the carrier air from the blowers 47 and 48. On the other hand, the combustion air is supplied by the blower 49.

When a plurality of coal types are burned at the same time, the coal is preliminarily fractionated according to the nitrogen content obtained by elemental analysis of the coal, and the fine powder described later with reference to FIGS. 9 to 11 will be described in detail. The charcoal burners 10 are supplied separately.
The air ratio in which the NOx production amount is affected by the nitrogen content is 1
Supplying coal with a low nitrogen content to the above areas,
The NOx emission amount is reduced by supplying coal having a large nitrogen content to the reduction region where the air ratio is less than 1 and which is not affected by the nitrogen content of the coal.

The sixth embodiment also has a plurality of coal supply systems. Therefore, the load per pulverized coal machine 45, 46 can be reduced. After the start-up, up to a predetermined load, only the coal supply system having a small nitrogen content in the separated coal may be used and the coal supply system having a large nitrogen content may be stopped. By doing so, it is possible to widen the combustion load range of the pulverized coal burner while reducing the NOx emission amount.

FIG. 9 is a sectional view showing an example of the structure of a pulverized coal burner which is installed in the sixth embodiment of FIG. 8 and burns pulverized coal of a plurality of coal types in units of individual burners, and FIG. It is a figure which shows the structure which looked at the pulverized coal burner of FIG. 9 from the AA direction. The pulverized coal burner 10 shown in FIG. 9 is attached to a furnace wall 12 forming a combustion chamber 11 through an opening 13.
The furnace wall 12 is made of a heat insulating material and prevents heat in the combustion chamber 11 from diffusing to the outside. Pulverized coal burner 10
Is used as a steam generating boiler, a water tube group for heat exchange is installed on the furnace wall 12.

An auxiliary fuel nozzle 14 is installed at the center of the pulverized coal burner 10. The auxiliary fuel is used to preheat the combustion chamber 11 at the start of the combustion device and ignite the pulverized coal, and when the flame of the pulverized coal becomes stable, the supply of the auxiliary fuel is stopped. Liquid or gas fuel is usually used as the auxiliary fuel.

An inner cylinder 15 is provided on the outer periphery of the auxiliary fuel nozzle 14.
A fuel nozzle is installed between the inner wall of the fuel tank and the outer wall of the auxiliary fuel nozzle 14. In the sixth embodiment, a plurality of fuel nozzles are installed concentrically. 1 installed concentrically
The secondary fuel nozzles 32 and 33 are connected to separate primary fuel supply pipes 34 and 35, respectively, and can supply fuel independently. In the primary fuel nozzles 32 and 33, pulverized coal and air for carrying the pulverized coal are flowed. In this specification, this mixed fluid is referred to as a primary fuel. A sleeve 19 may be provided at the outlets of the primary fuel nozzles 32 and 33 so as to widen toward the combustion chamber 11 side of the pulverized coal burner 10. By providing the sleeve 19 in this way, the effect of holding the flame and expanding the reduction region where the air ratio is less than 1 is obtained.

A secondary air nozzle 21 for ejecting combustion air is installed on the outer periphery of the primary fuel nozzle 33.
The secondary air nozzle 21 is formed by the outer wall of the inner cylinder 15 and the inner wall of the outer cylinder 22. In this specification, the air flowing through the secondary air nozzle 21 is referred to as secondary air. The secondary air is supplied to the wind box 24 through the secondary air supply pipe 23,
A swirl flow is generated by the swirl flow generator 25 and is supplied into the combustion chamber 11.

A tertiary air nozzle 26 for ejecting combustion air is installed on the outer periphery of the secondary air nozzle 21.
The tertiary air nozzle 26 is formed by the outer wall of the outer cylinder 22 and the opening 13 of the furnace wall 12. In this specification, the air flowing through the tertiary air nozzle 26 is referred to as tertiary air. The tertiary air is supplied to the wind box 28 through the tertiary air supply pipe 27, becomes a swirl flow by the swirl flow generator 29, and the combustion chamber 11
Supplied within.

In the sixth embodiment, the secondary air, the tertiary air, and the combustion air are supplied concentrically, and the swirling flow generating means and the like are further installed, so that the primary fuel and the air are Is delayed in mixing. Therefore, a reducing region 31 having an air ratio of less than 1 is formed in the center of the flame 30. In the reducing region 31 where the air ratio in the flame is less than 1, the nitrogen content contained in the coal produces reducing nitrogen compounds such as HCN and NH ₃ . This reducing nitrogen compound causes a reduction reaction that reduces NOx to nitrogen, and reduces the NOx emission amount.

When a plurality of types of coal are simultaneously burned, they are separated according to the content of nitrogen content obtained by elemental analysis and supplied from the primary fuel supply pipes 34 and 35. At this time, among the coals sorted according to the nitrogen content of the coal, the nozzle 3 provided inside has coal with a large nitrogen content.
2 is ejected, and coal having a low nitrogen content is ejected from the nozzle 33 provided outside. That is, from the pulverized coal burner 10, a coal having a high nitrogen content is mainly ejected, and a coal having a low nitrogen content is ejected from the outside so as to surround the coal having a high nitrogen content. Let

The secondary air and the tertiary air which occupy most of the combustion air are mixed with the fuel from the outside of the primary fuel nozzles 32 and 33. Therefore, the air-fuel mixture on the outside that is easily mixed with the combustion air has a high air ratio. On the other hand, since the center of the air-fuel mixture is difficult to mix with the combustion air, the air ratio is 1
The reduction region is less than. That is, the coal having a large nitrogen content passing through the nozzle 32 is supplied to the reduction region 31 in which the air ratio in the flame 30 is less than 1 as shown by an arrow 36. Coal with a low nitrogen content passing through the nozzle 33 is
As shown by the arrow 37, the reduction region 3 in the flame 30
The air ratio formed around 1 is supplied to a region having an air ratio of 1 or more.

As is clear from the results of the experiments conducted by the inventors, the N produced is reduced in the reduction region where the air ratio is less than 1.
The Ox amount is not affected by the nitrogen content of coal. Therefore, coal having a low nitrogen content is supplied to the region where the air ratio in which the amount of NOx produced is affected by the nitrogen content is 1 or more. Further, coal having a large nitrogen content is supplied to the reduction region in which the air ratio is less than 1 and is not affected by the nitrogen content of the coal. By this combustion method, the NOx emission amount as a whole can be reduced.

When coal having a high nitrogen content is supplied to the reducing region where the air ratio is less than 1, the amount of reducing nitrogen compound produced increases. Therefore, N by the reducing nitrogen compound
The reduction reaction of Ox also progresses, and the NOx emission amount becomes even lower.

Further, when the air ratio of the mixture of coal and air ejected from the nozzle 32 is made lower than the air ratio of the mixture of coal and air ejected from the nozzle 33, the amount of reducing nitrogen compound produced further increases. However, it becomes more effective in reducing the NOx emission amount.

FIG. 11 is a sectional view showing another example of the structure of the pulverized coal burner which is installed in the sixth embodiment of FIG. 8 and burns the pulverized coal of a plurality of coal types in each burner unit. FIG.
In the first example, the fuel supply pipes 34,
35 joins in the middle of the straight pipe part of the pulverized coal burner 10. In this case, in order to delay the mixing of coals of a plurality of coal types, it is desirable that the flow rates of the primary fuels flowing through the fuel supply pipes 34 and 35 be equal.

In the example of FIG. 11, since the outlet of the pulverized coal burner 10 is not a double pipe, the structure of the pulverized coal burner is simplified, and the diameter of the pulverized coal burner can be reduced with respect to the combustion load amount. Further, the flow of pulverized coal at the outlet of the pulverized coal burner becomes quick, and there is no risk of blockage due to flashback or ash adhesion.

In the sixth embodiment shown in FIG. 8, the pulverized coal burner 10 is shown as a single combustion device. However, even when the pulverized coal burner 10 is composed of a plurality of combustion devices, it is the same as in the sixth embodiment. The effect is obtained.

<< Seventh Embodiment >> FIG. 12 is a diagram showing a system configuration of a seventh embodiment of a combustion apparatus in which a sensor for monitoring a combustion state and a pulverized coal mixer are additionally installed in the sixth embodiment of FIG. Is. The sensor 50 provided in the combustion chamber 11 is configured to detect the oxygen concentration, carbon monoxide concentration, NOx concentration,
The combustion state such as the unburned amount in the coal and the flame temperature in the combustion chamber 11 is monitored. The pulverized coal mixer 51 provided in the pulverized coal supply path is based on the combustion state measured by the sensor 50.
This is a means for separating a part of pulverized coal which is separated according to the content of nitrogen in the coal and conveyed in a plurality of systems. At least one of the primary fuel supply pipes 34, 35 is provided with the pulverized coal mixer 5
If the pulverized coal mixed with the coal species to be conveyed in the other primary fuel supply pipe in 1 is supplied, it becomes possible to adjust the combustion state in the flame 30 and the reduction region 31 and the NOx emission amount produced as a whole.

<Eighth Embodiment> FIG. 13 is a diagram showing a system configuration of an eighth embodiment of the combustion apparatus according to the present invention for suppressing the NOx emission amount by burning pulverized coal of a plurality of coal types in each burner unit. FIG. 14 shows the pulverized coal burner of FIG.
It is a figure which shows the structure seen from the -B direction. The pulverized coal burner of the eighth embodiment comprises rectangular nozzles and pipes, as is clear from FIG. At the center, a fuel nozzle 61 for ejecting pulverized coal and carrier air, and the fuel nozzle 61
There is a fuel supply pipe 62 leading to the. Next to the fuel nozzle 61 and the fuel supply pipe 62, a fuel nozzle 63 and a fuel supply pipe 64 are provided.
And are arranged. Further, next to the fuel nozzle 63 and the fuel supply pipe 64, a combustion air supply pipe 66 formed by the outer wall of the inner cylinder 65 and the inner wall of the outer cylinder 67 is provided to supply combustion air to the combustion chamber 11. To do. In the eighth embodiment, the fuel nozzle 63, the fuel supply pipe 64, and the combustion air supply pipe 66 are the fuel nozzle 61 and the fuel supply pipe 62.
It is provided on both sides of the. Thus, the combustion air is supplied separately, so that the mixing of the fuel and the combustion air at the pulverized coal burner outlet is delayed. Therefore, a reduction region 31 having an air ratio of less than 1 is formed near the outlet of the nozzle 61.

When coals of a plurality of coal species are simultaneously burned, the coals are preliminarily separated according to the nitrogen content obtained by elemental analysis, and the coals are supplied from the fuel supply pipes 62 and 64.
At this time, among the plurality of fuel nozzles, the nozzle 61 provided on the inner side ejects the coal having a large nitrogen content among the coals sorted according to the nitrogen content. Coal having a low nitrogen content is ejected from the nozzle 63 provided outside. That is, coal with a high nitrogen content is ejected from the center of the pulverized coal burner, and coal with a low nitrogen content is ejected from the outside so as to surround the coal with a high nitrogen content. Let

The combustion air is ejected from the combustion air supply pipe 66 located outside the fuel nozzle 63 and mixes with the fuel. Therefore, the mixture air ejected from the fuel nozzle 63 which is easily mixed with the combustion air is air. The ratio becomes higher. Further, the air-fuel mixture ejected from the fuel nozzle 61 is difficult to mix with the combustion air, so that a reducing region having an air ratio of less than 1 is formed. That is, the coal having a high nitrogen content passing through the nozzle 61 is supplied to the reducing region 31 of the flame 30 in which the air ratio is less than 1 as shown by the arrow 36. Coal having a low nitrogen content passing through the nozzle 63 is heated by the flame 3 as shown by an arrow 37.
Within 0, the air ratio formed around the reduction region 31 is 1
It is supplied to the above area.

As is clear from the above experimental results of the inventors, the NOx production amount is not affected by the nitrogen content of coal in the reduction region where the air ratio is less than 1. Therefore,
Also in the eighth embodiment, coal having a low nitrogen content is supplied to the region where the NOx generation amount is influenced by the amount of nitrogen content contained in the coal and the air ratio is 1 or more. Further, coal having a large nitrogen content is supplied to the reduction region where the air ratio is less than 1 and is not affected by the nitrogen content of the coal. By this method, the NOx emission amount as a whole can be suppressed. Further, if the air ratio of the mixture of coal and air ejected from the nozzle 61 is made lower than the air ratio of the mixture of coal and air ejected from the nozzle 63, it will be more effective in reducing the NOx emission amount.

In the pulverized coal burner consisting of the rectangular nozzle and pipe shown in FIGS. 13 and 14, the side wall 68 is provided.
On the side, the fuel nozzle is not sandwiched by air nozzles or other fuel nozzles, so the jet from the fuel nozzle is
It is easy to form a large circulation flow on the side wall 68 side. The circulation flow formed in this way is effective for promoting ignition and stabilization of pulverized coal. When the ignition is promoted, the reduction region 31 formed in the flame 30 approaches the pulverized coal burner outlet and further increases, so that the NOx emission amount can be further reduced.

[0082]

EFFECTS OF THE INVENTION According to the present invention, in a pulverized coal combustion apparatus using a plurality of coal species, coal is preliminarily fractionated according to the content of nitrogen content obtained by elemental analysis, and the NOx production amount is equal to the content of nitrogen content. Coal with a high nitrogen content is supplied to the reduction region where the air ratio is less than 1 and is not affected by the content, and NO
Coal having a low nitrogen content is supplied to the region where the air ratio in which the x generation amount is affected by the nitrogen content is 1 or more. As a result, conventionally, when coal with a high nitrogen content in the coal was mixed, the NOx production amount also tended to increase, whereas in the present invention, a coal with a high nitrogen content was reduced in the reduction region. The NOx emission amount can be reduced because it is supplied to.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between a gas phase air ratio and a generated NOx concentration in a laminar flow combustion furnace which is a basis of a pulverized coal combustion method according to the present invention.

FIG. 2 is a diagram showing a system configuration of a first embodiment of a combustion apparatus according to the present invention in which pulverized coal burners are provided in upper and lower two stages.

3 is a characteristic diagram showing the relationship between the difference between the NOx amount discharged by the conventional method and the NOx amount discharged by the present invention with respect to the difference in the nitrogen content of coal in order to show the effect of the first embodiment of FIG. is there.

FIG. 4 is a diagram showing a system configuration of a second embodiment of a combustion apparatus in which a sensor for monitoring a combustion state and a pulverized coal mixer are additionally installed in the first embodiment of FIG.

FIG. 5 is a diagram showing a system configuration of a third embodiment of a combustion apparatus according to the present invention in which pulverized coal burners are arranged so as to face each other.

FIG. 6 is a diagram showing a system configuration of a fourth embodiment of a combustion apparatus in which a sensor for monitoring a combustion state and a pulverized coal mixer are additionally installed in the third embodiment of FIG.

FIG. 7 is a diagram showing a system configuration of a fifth embodiment of a combustion apparatus according to the present invention in which a pulverized coal burner is arranged so as to be inclined with respect to a furnace wall surface.

FIG. 8 is a diagram showing a system configuration of a sixth embodiment of a combustion apparatus according to the present invention, in which pulverized coal of a plurality of coal types is burned in each burner unit to suppress NOx emission amount.

9 is a cross-sectional view showing an example of the structure of a pulverized coal burner which is installed in the sixth embodiment of FIG. 8 and burns pulverized coal of a plurality of coal types in each burner unit.

10 is a diagram showing the structure of the pulverized coal burner of FIG. 9 seen from the AA direction.

FIG. 11 is a cross-sectional view showing another example of the structure of the pulverized coal burner installed in the sixth embodiment of FIG. 8 and burning the pulverized coal of a plurality of coal types in each burner unit.

FIG. 12 is a diagram showing a system configuration of a seventh embodiment of a combustion apparatus in which a sensor for monitoring a combustion state and a pulverized coal mixer are additionally installed in the sixth embodiment of FIG.

FIG. 13 is a diagram showing a system configuration of an eighth embodiment of the combustion apparatus according to the present invention, which burns pulverized coal of a plurality of coal types for each burner unit to suppress NOx emission amount.

FIG. 14 is a view showing a structure of the pulverized coal burner of FIG. 13 as seen from the BB direction.

[Explanation of symbols]

 10 Pulverized Coal Burner 11 Combustion Chamber 12 Furnace Wall 13 Opening 14 Auxiliary Fuel Nozzle 15 Inner Cylinder 19 Sleeve 21 Secondary Air Nozzle 22 Outer Cylinder 23 Secondary Air Supply Pipe 24 Wind Box 25 Swirling Flow Generator 26 Tertiary Air Nozzle 27 Tertiary air supply pipe 28 Wind box 29 Swirling flow generator 30 Combustion flame 31 Reduction area 32,33 Primary fuel nozzle 34,35 Primary fuel supply pipe 36,37 Arrow (fuel flow) 41 Coal storage plant (small nitrogen content) ) 42 coal storage yard (large nitrogen content) 43,44 hopper 45,46 pulverized coal machine 47,48,49 blower 50 sensor 51 pulverized coal mixer 52,53 pulverized coal burner 54 air inlet 55 combustion chamber outlet 56,57 flame 61,63 Fuel Nozzle 62,64 Fuel Supply Pipe 65 Inner Cylinder 66 Combustion Air Supply Pipe 67 Outer Cylinder 68 Side Wall

Front Page Continuation (72) Inventor Masayuki Taniguchi 7-1 Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory Ltd. (72) Inventor Kiyoshi Narato 7-1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd., Hitachi Research Laboratory (72) Inventor, Go Kono, 7-1, 1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Research Laboratory, (72) Inventor Shigeki Morita 6-9 Takaracho, Kure-shi, Hiroshima Prefecture No. Babcock Hitachi Kure Factory (72) Inventor Shunichi Tsumura No. 6-9 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Kure Factory

Claims (19)

[Claims] 1. In a pulverized coal combustion method in which coals of a plurality of coal types are individually supplied to a plurality of pulverized coal burners and burned, coals of a plurality of coal types are burned according to the content of nitrogen content obtained by elemental analysis. Pulverized coal burner for preliminarily fractionating and injecting a mixture of pulverized coal and air into a region where the air ratio (= the ratio of the actual input air amount and the air amount required to completely burn the pulverized coal) is less than 1 In the pulverized coal burner for supplying a coal having a high nitrogen content among the fractionated coals and injecting a mixture of pulverized coal and air into the region where the air ratio is 1 or more, the fractionated coals Among them, a pulverized coal combustion method characterized by supplying coal having a low nitrogen content. 2. A pulverized coal combustion method in which a plurality of pulverized coal burners are individually supplied to a plurality of pulverized coal burners and burned, according to the nitrogen content obtained by elemental analysis of the plurality of coal types. In the pulverized coal burner which has been fractionated in advance and the air ratio (= the ratio of the actual input air amount and the air amount required for complete combustion of the pulverized coal) set to less than 1, the nitrogen content of the fractionated coal is Mining coal is supplied, and the pulverized coal burner in which the air ratio is set to 1 or more is supplied with coal having a low nitrogen content among the fractionated coals. Combustion method. 3. A pulverized coal combustion method in which coals of a plurality of coal types are individually supplied to a plurality of pulverized coal burners and excess air is introduced from an air inlet to completely burn the coals. According to the content of nitrogen content obtained by elemental analysis in advance, to the pulverized coal burner located away from the air inlet, the coal with a high nitrogen content of the fractionated coal is supplied. However, in the pulverized coal burner located near the air inlet,
A pulverized coal combustion method comprising supplying coal having a low nitrogen content among the separated coals. 4. The pulverized coal combustion method according to any one of claims 1 to 3, wherein the pulverized coal burner has a predetermined load after the pulverized coal burner is activated until a predetermined load is reached. Supplying only coal with a low content of nitrogen, and above the predetermined load, coal with a low content of nitrogen and coal with a high content of nitrogen are supplied in parallel to each of the pulverized coal burners. A pulverized coal combustion method characterized by: 5. The pulverized coal combustion method according to any one of claims 1 to 4, wherein the combustion state is monitored, and when the combustion state satisfies a predetermined condition, a part of the separated coal Is mixed and supplied to at least one of the pulverized coal burners. 6. The pulverized coal combustion method according to claim 1, wherein an average nitrogen content obtained by elemental analysis is obtained when the coal is separated according to the nitrogen content. A pulverized coal combustion method, characterized in that the relative difference in amount is 0.1 (wt%) or more. 7. A pulverized coal combustion apparatus which has a plurality of pulverized coal burners in an up-down direction or an opposite direction and which individually supplies coal of a plurality of coal types to the plurality of pulverized coal burners and burns the coal. Coal storage area for preliminarily fractionating and storing the coal according to the nitrogen content obtained by elemental analysis, pulverized coal machine for individually pulverizing the fractionated coal, and air ratio (= actual input air amount A pulverized coal burner for injecting a mixture of pulverized coal and air into a region where the ratio of the amount of air required to completely burn the pulverized coal is less than 1 Means for supplying charcoal, and means for supplying pulverized coal having a small nitrogen content in the pulverized coal to a pulverized coal burner for ejecting a mixture of pulverized coal and air to the region where the air ratio is 1 or more. Pulverized coal combustion equipment characterized by having . 8. A pulverized coal combustion apparatus which has a plurality of pulverized coal burners in an up-down direction or an opposite direction and which individually supplies coal of a plurality of pulverized coal burners to the plurality of pulverized coal burners and burns them. Coal storage area for preliminarily fractionating and storing the coal according to the nitrogen content obtained by elemental analysis, pulverized coal machine for individually pulverizing the fractionated coal, and air ratio (= actual input air amount A ratio of the amount of air required to completely burn the pulverized coal) less than 1 to a pulverized coal burner for supplying pulverized coal having a high nitrogen content in the pulverized coal burner; And a means for supplying pulverized coal having a low nitrogen content of the pulverized coal to the pulverized coal burner set to 1 or more. 9. A coal having a plurality of pulverized coal burners in a vertical direction or a facing direction, wherein coals of a plurality of coal types are individually supplied to the plurality of pulverized coal burners and excess air is introduced from an air introduction port. In a pulverized coal combustion device that completely burns the coal, a coal storage yard that preliminarily sorts and stores coals of a plurality of coal types according to the nitrogen content obtained by elemental analysis, and a pulverized powder that individually pulverizes the sorted coals. A coal machine, a means for supplying pulverized coal with a high nitrogen content in the pulverized coal to the pulverized coal burner located at a position distant from the air charging port, and a pulverized coal burner located at a position near the air charging port. And a means for supplying pulverized coal having a low nitrogen content in the pulverized coal. 10. The pulverized coal combustion apparatus according to claim 7, wherein the plurality of pulverized coal burners provided in the facing direction are the pulverized coal burners having different air ratios or coal types. A pulverized coal combustion apparatus, which is arranged so as to be inclined with respect to a furnace wall surface of the pulverized coal combustion apparatus so that the formed flames collide with each other. 11. A plurality of pulverized coal burners which are arranged concentrically and eject a mixture of pulverized coal and air, and means for supplying combustion air which are arranged on the outer periphery of the pulverized coal burner are provided. In a pulverized coal combustion apparatus that individually supplies and burns to the plurality of pulverized coal burners, a coal storage place for preliminarily fractionating and storing coal of a plurality of coal types according to the nitrogen content obtained by elemental analysis, and the fractionation. A pulverized coal machine for individually pulverizing the coal, a means for supplying pulverized coal having a high nitrogen content in the pulverized coal to the inner pulverized coal burner of the concentric pulverized coal burners, A pulverized coal combustion apparatus comprising: means for supplying pulverized coal having a smaller nitrogen content of the pulverized coal to an outer pulverized coal burner of the concentric pulverized coal burners. 12. The pulverized coal combustion apparatus according to claim 11, wherein an auxiliary fuel nozzle for supplying an auxiliary fuel of liquid or gas to the jetting region of the air-fuel mixture is provided in the central portion of the concentric circles. Pulverized coal combustion equipment. 13. A first pulverized coal burner for ejecting an air-fuel mixture of pulverized coal and air and a second pulverized coal burner for ejecting an air-fuel mixture of pulverized coal having a coal type different from that of the pulverized coal arranged vertically above and below it. A pulverized coal burner having a means for supplying combustion air that is disposed close to and above and below the pulverized coal burner, and individually supplies coal of a plurality of coal types to the plurality of pulverized coal burners and burns them, A coal storage yard for preliminarily fractionating and storing coal of a plurality of coal types according to the nitrogen content obtained by elemental analysis, a pulverized coal machine for individually pulverizing the fractionated coal, and the first pulverized coal burner And means for supplying pulverized coal having a high nitrogen content in the pulverized coal, and means for supplying pulverized coal having a low nitrogen content in the pulverized coal to the second pulverized coal burner. A pulverized coal combustion device characterized in that 14. The pulverized coal combustion apparatus according to claim 7, further comprising means for monitoring a load of the pulverized coal combustion apparatus, wherein a predetermined load is reached after the pulverized coal burner is activated. Up to the operation of only means for supplying pulverized coal having a low nitrogen content to the pulverized coal burner, and above the predetermined load, supplying pulverized coal having a low nitrogen content to the pulverized coal burner, respectively. A pulverized coal combustion apparatus characterized in that the pulverized coal combustion device and the means for supplying pulverized coal having a high nitrogen content are operated in parallel. 15. The pulverized coal combustion apparatus according to any one of claims 7 to 14, comprising means for monitoring the combustion state and means for mixing a part of the pulverized coal having different coal types. When the combustion state satisfies a predetermined condition, a part of the pulverized coal having a different coal type is mixed and supplied to at least one of the pulverized coal burners. 16. The pulverized coal combustion apparatus according to claim 7, wherein when the coal is separated according to the content of the nitrogen content and stored in the coal storage yard, it is obtained by elemental analysis. A pulverized coal combustion apparatus, characterized in that the relative difference in the average content of the generated nitrogen content is 0.1 (% by weight) or more. 17. A pulverized coal burner of a pulverized coal combustion apparatus that individually supplies and burns coal of a plurality of types of coal, and a plurality of primary fuel nozzles arranged concentrically to eject a mixture of pulverized coal and air. A secondary air nozzle disposed on the outer periphery of the secondary air nozzle for supplying combustion air; a swirl flow generator for generating a swirl flow in the air from the secondary air nozzle; Of the pulverized coal, the pulverized coal having a low nitrogen content is supplied to the primary fuel supply pipe for supplying the pulverized coal having a high nitrogen content and the concentric outer primary fuel nozzle. A pulverized coal burner, which comprises: a primary fuel supply pipe, and a sleeve that is formed at the outlet of the primary fuel nozzle and that widens toward the combustion chamber side of the pulverized coal burner. 18. A pulverized coal burner of a pulverized coal combustion device for individually supplying and burning coal of a plurality of types of coal, an inner primary fuel nozzle for ejecting a mixture of pulverized coal and air, and the inner 1 The secondary fuel nozzle is arranged concentrically with the primary fuel nozzle on the outer side, which projects toward the combustion chamber and protrudes from the primary fuel nozzle on the inner side, and injects a mixture of pulverized coal and air. A secondary air nozzle that supplies air, a swirl flow generator that forms a swirl flow in the air from the secondary air nozzle, and a concentric inner primary fuel nozzle that contains a nitrogen content of the pulverized coal. A primary fuel supply pipe for supplying a large amount of pulverized coal, and a primary fuel supply pipe for supplying a pulverized coal having a small nitrogen content in the pulverized coal to the concentric outer primary fuel nozzles, Primary combustion of the outside Pulverized coal burner, characterized in that a sleeve is formed in the nozzle outlet becomes divergent toward the combustion chamber side of the pulverized coal burner. 19. The pulverized coal burner according to claim 17 or 18, wherein an auxiliary fuel nozzle for supplying an auxiliary fuel of liquid or gas to the jetting region of the air-fuel mixture is provided in the central portion of the concentric circles. Pulverized coal burner.