JP2007192475A - Boiler device and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler device and its operation method capable of achieving effect of reducing CO concentration and NOx concentration without impairing combustion performance of solid fuel such as coal in a furnace. <P>SOLUTION: This boiler device is composed of a burner 6 of one or more stage for reducing combustion, an after air port 7 of one or more stage jetting the combustion air short in the burner 6, and a mixing promoting port 8 for supplying a part of boiler exhaust gas discharged from the boiler, between the burner 6 and the after air port 7. The burners 6, the after air ports 7 and the mixing promoting ports 8 are respectively disposed on a pair of opposite wall surfaces of the furnace, the mixing promoting ports 8 of each stage are respectively disposed at opposite positions on the same horizontal faces of the opposite furnace wall surfaces, or positions shifted from the opposite positions, and when the mixing promoting ports 8 are disposed in plural stages, the mixing promoting port 8 of each stage is disposed on an intermediate position of the mixing promoting port 8 of the adjacent stage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a combustion apparatus such as a coal-fired boiler and an operation method thereof, and more particularly to a combustion apparatus suitable for reducing nitrogen oxides and carbon monoxide in exhaust gas and an operation method thereof.

  Conventionally, thermal power generation is the main power generation in Japan, and thermal power generation is still responsible for basic power generation even when nuclear power generation is spreading. Petroleum is the fuel for thermal power generation, but since the oil shock, especially since the 1980s, demand for cheap overseas coal-fired boilers has increased. When fossil solid fuel such as coal is burned at a thermal power plant, there are problems related to reduction of environmental pollutants such as nitrogen oxides and increase in plant efficiency due to improvement of combustion rate. Various techniques have been invented for these problems since the 1980s.

For example, Japanese Patent No. 2954643 divides the furnace into a combustion region, a reduction region, and a recombustion region, and shows a nitrogen oxide (NOx) reduction effect in the reduction region.
Currently, in such a combustion zone, fuel is burned at a stoichiometric air ratio or less, and nitrogen oxides generated from the nitrogen content in the fuel are reduced in a reduction region with a low oxygen concentration, and the amount of nitrogen oxides at the furnace outlet is reduced. The two-stage combustion method has become mainstream. As another nitrogen oxide reduction method, there is a method in which a denitration device is provided downstream of the boiler and is physically reduced by a catalyst or the like.
Japanese Patent Laid-Open No. 9-126212 Japanese Patent No. 2954643 No. 62-194229 (No. 01-101011) No. Microfilm JP 58-219308 A JP 59-24106 A

Patent Documents 1 to 3 disclose that relatively low-temperature furnace outlet exhaust gas can be supplied into the furnace from the furnace wall between the burner and the after-air port to suppress the generation amounts of thermal NOx and fuel NOx. Yes.
However, even in the methods described in these patent documents, gases in different combustion states in the furnace cannot be sufficiently uniformly mixed, and the effect of reducing the CO concentration and NOx concentration in the combustion gas is insufficient.

  The subject of this invention is providing the boiler apparatus which can achieve the reduction effect of CO concentration and NOx concentration in combustion gas, and its operating method, without impairing the combustibility of solid fuels, such as coal, in a furnace. .

The above-described problems of the present invention are solved by the following configuration.
According to the first aspect of the present invention, in a boiler apparatus for burning a solid fuel containing coal in a furnace, a plurality of burners for burning the solid fuel with an air amount equal to or less than the theoretical air ratio are provided in one stage in the combustion gas flow direction. A plurality of after-air ports are provided downstream of the burner and for injecting combustion air, which is insufficient for solid fuel combustion in the burner, into the furnace, and at least one stage in the combustion gas flow direction. A plurality of mixing promotion ports for supplying a part of boiler exhaust gas discharged from the boiler to the downstream side of the burner and upstream of the after-air port, and one or more stages in the combustion gas flow direction, The burner, after-air port, and mixing promotion port are arranged on a pair of opposing wall surfaces of the furnace, and each mixing promotion port of each stage has the same water content on the opposing furnace wall surface. It is arranged at a position that is opposite to or opposite to the opposite position (this arrangement mode of the burner, after-air port, or mixing promotion port may be hereinafter referred to as a staggered arrangement), and the mixing promotion port is a gas When there are a plurality of stages in the flow direction, each mixing promotion port in each stage is a boiler device arranged at an intermediate position between two adjacent mixing promotion ports in adjacent stages.

  According to the first aspect of the present invention, when a plurality of mixing promotion ports are provided, each mixing promotion port of each stage is disposed at an intermediate position between two adjacent mixing promotion ports of the adjacent stage in the vertical direction (burner These arrangements, including after-airports, may also be referred to hereinafter as a staggered arrangement.), Which has the effect of promoting mixing of the combustion gas region formed by the burner in the furnace with other unburned gas regions. In addition, the unburned portion in the combustion gas from the burner is completely burned, and the combustion efficiency of the boiler is improved as compared with the conventional one.

  Also, by blowing the combustion gas at a high speed from the mixing promotion port into the gas in a state where the combustion gas region formed by the burner flame and other unburned gas regions coexist, the flow state of the gas in the furnace is changed and combustion is performed. It has the effect of promoting the mixing of gas and unburned matter.

  Further, by blowing the mixing promotion gas from the mixing promotion port, the mixing of the carbon monoxide remaining in the combustion gas region and the unburned gas is promoted, so that the oxidation action due to the residual oxygen concentration existing in the unburned gas region is promoted. As a result, carbon monoxide is converted into carbon dioxide as a final product.

  The invention according to claim 2 is the boiler apparatus according to claim 1, wherein the mixing promotion port is provided on the furnace wall where the mixing promotion gas can be blown into a region where the combustion of the fuel in the uppermost burner becomes slow. .

  According to the second aspect of the present invention, the gas is mixed without destroying the flame of the uppermost burner by injecting the mixing promotion gas from the mixing promotion port when the combustion of the fuel in the uppermost burner becomes slow. In addition, by maintaining the distance from the mixing promotion port to the after-air port, the reduction promotion effect after making the gas flow in the furnace uniform can be sufficiently obtained. In addition, by blowing the combustion gas jet from the mixing promotion port at the position where the combustion of the uppermost burner becomes slow, the mixing of the combustion gas in the furnace and the unburned gas region is promoted, and the mixed gas has a uniform NOx concentration. Thus, a sufficient reduction action is obtained in the reduction region up to the after-airport, and a low NOx concentration is obtained at the furnace outlet. There is a similar effect on the CO concentration in the gas in the furnace. That is, by promoting the mixing of the carbon monoxide remaining in the combustion gas region and the unburned gas, carbon monoxide is the final product due to the oxidation action due to the residual oxygen concentration existing in the unburned gas region. Is converted to

  In the invention according to claim 3, the mixing promotion port is not two opposing wall surfaces of the furnace in which the burner and the after-air port are arranged, but two opposing side wall surfaces that connect both ends of the two opposing wall surfaces. It is a boiler apparatus of Claim 1 or 2 arrange | positioned.

  According to the third aspect of the present invention, in the opposed combustion method in which the burner is disposed on the two furnace walls facing each other, the incomplete combustion region is particularly located in the vicinity of the two side walls connecting the two end portions of the two front and rear furnace walls. Since it is easy to form, mixing promotion of the gas in a furnace can be aimed at by arrange | positioning a mixing promotion port not to the furnace wall which has arrange | positioned the burner but to the said side wall.

  According to a fourth aspect of the present invention, there is provided the boiler device according to any one of the first to third aspects, wherein the mixing promotion port includes a swirling portion that forms a swirling flow of the mixing promoting gas and supplies the mixing promoting gas into the furnace. It is.

According to the invention of claim 4, by introducing the mixing promotion gas supplied from the mixing promotion port in a swirling flow, the unburned portion near the front and rear walls of the furnace is accompanied by the jet from the mixing promotion port, and the combustion gas and The effect of promoting unmixed content is obtained.
The swirl force of the swirl flow is such that the ratio of swirl speed component / axial speed component is in the range of 0.2 to 0.8, thereby increasing the amount of exhaust gas entrainment in the vicinity of the wall surface and increasing the flow at the center of the furnace. Has the effect of promoting mixing. When the swirl speed component / shaft speed component ratio is 1.0 or more, the amount of entrained gas near the wall surface increases, but the penetration force to the center of the furnace is reduced, so the mixing promotion at the center of the furnace is worsened. By applying a swirl force to the mixing promoting gas, the amount of exhaust gas entrained in the vicinity of the furnace wall surface increases more than the straight flow. However, if the mixing promoting gas has a swirling force, the amount of entrainment in the vicinity of the furnace wall surface is too large, and the exhaust gas cannot reach the center of the furnace.

  According to a fifth aspect of the present invention, there is provided the gas dividing member according to any one of the first to third aspects, wherein a gas dividing member that divides the gas blown out from the mixing promoting port into the furnace in the horizontal direction is provided at the outlet of the mixing promoting port. It is a boiler device.

  The invention according to claim 6 is the boiler apparatus according to claim 5, wherein the gas dividing member has a shape such that the directions of the gases blown out from the mixing promotion port into the furnace are not the same direction.

  According to the invention described in claim 5 and the invention described in claim 6, the gas jetted into the furnace is divided into a plurality of parts in the horizontal direction and the jetting direction is changed, thereby forming a wide jet in the horizontal cross section and the burner. Can promote the mixing of the combustion gas from the exhaust gas, and has the effect of reducing the NOx concentration and CO concentration in the exhaust gas.

  According to the seventh aspect of the present invention, the plurality of burners at the uppermost stage are arranged on the same horizontal plane with a pair of opposing furnace wall surfaces and are shifted from positions facing each other. The airports are respectively disposed on the same horizontal plane with a pair of opposing furnace wall surfaces, and the lowermost after-airports provided on the same wall surface downstream of the uppermost burner are adjacent to each other in the uppermost burners. It is a boiler apparatus in any one of Claim 1 thru | or 6 arrange | positioned above the intermediate position of two burners.

  According to the seventh aspect of the present invention, the combustion gas containing the unburned portion in the burner portion is well mixed in the furnace.

  The invention according to claim 8 is characterized in that at least one stage of each after-air port is disposed above an intermediate position between two adjacent burners in a plurality of burners at the uppermost stage provided on the same wall surface on the upstream side. It is a boiler apparatus in any one of 1 thru | or 6.

  According to the eighth aspect of the present invention, the combustion gas containing the unburned portion in the burner portion rises near the outlet of the after-air port, so that combustion of the unburned portion can be promoted.

  The invention according to claim 9 is the boiler apparatus according to claim 7 or 8, wherein each after-air port of each stage is arranged at an intermediate position between two after-air ports adjacent to each other in the upper and lower stages.

  According to the ninth aspect of the invention, even if the combustion gas containing the unburned portion in the burner portion diffuses, it rises near the outlet of the after-air port, so that the combustion of the unburned portion can be promoted.

  In the invention described in claim 10, the amount of boiler combustion gas blown into the furnace from the mixing promotion port of the boiler device according to any one of claims 1 to 9 is 10% or less of the total combustion air amount, and after mixing This is a method of operating a boiler apparatus in which the air ratio is equal to or less than the theoretical air ratio.

According to the invention described in claim 10, the gas introduced from the mixing promotion port is introduced so that the air ratio after the injection becomes equal to or lower than the theoretical air ratio, and the unburned gas is not burned without impairing the reduction action from the burner to the after-air port. The flammability of the minute can be maintained. If a high oxygen concentration gas such as air is used as the mixing promotion gas and the air ratio after the injection is higher than the theoretical air ratio, a combustion reaction occurs due to mixing with the unburned components in the furnace, and the after air port from the burner This will impair the reduction action.
Further, when the amount of boiler combustion gas introduced from the mixing promotion port exceeds 10% of the amount of combustion air, there arises a problem that the combustibility deteriorates and the unburned content in the exhaust gas increases.

  The invention according to claim 11 is the operation method of the boiler apparatus according to claim 10, wherein the flow rate of gas blown out from the mixing promotion port into the furnace is 50 m / s or more.

  According to the eleventh aspect of the present invention, by introducing the mixing promoting gas from the mixing promoting port with a high-speed jet, the surrounding gas is entrained, and the effect of promoting the mixing can be obtained with a small amount of gas.

  According to the first aspect of the present invention, there is an effect of promoting the mixing of the combustion gas flow region formed by the burner in the furnace with the mixing promoting gas and the other unburned gas region, and the unburned gas in the combustion gas from the burner is not mixed. The fuel is completely burned, the combustion efficiency of the boiler is improved, and the carbon monoxide concentration and the nitrogen oxide concentration in the exhaust gas at the furnace outlet are reduced.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, a reduction promoting effect after making the gas flow in the furnace uniform can be sufficiently obtained.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, an effect of further promoting the mixing of the combustion gas and the unburned content can be obtained.

  According to the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, the effect of promoting the mixing of the combustion gas and the unburned content can be obtained.

  According to the invention described in claim 5 and the invention described in claim 6, in addition to the effect of the invention described in any one of claims 1 to 3, the combustion gas from the burner is formed by forming a wide jet in the horizontal section of the furnace. And the unburned content can be promoted, and the NOx concentration and CO concentration in the exhaust gas are reduced.

  According to the invention of claim 7, in addition to the effect of the invention of any one of claims 1 to 6, the combustion gas containing unburned components in the burner part is well mixed in the furnace, and further The effect of promoting the mixing of combustion gas and unburned matter is obtained.

  According to the eighth aspect of the invention, in addition to the effect of the invention according to any one of the first to sixth aspects, there is a further combustion promotion effect of unburned content.

  According to the ninth aspect of the invention, in addition to the effect of the seventh or eighth aspect of the invention, there is a further combustion promoting effect of the unburned portion rising near the outlet of the after airport.

  According to the invention described in claim 10, the combustibility can be maintained without impairing the reducing action from the burner to the after airport.

  According to the eleventh aspect of the invention, in addition to the effect of the tenth aspect, by introducing the mixing promotion gas from the mixing promotion port with a high-speed jet, the surrounding gas is entrained and burned with a small amount of gas. The effect of promoting the mixing of gas and unburned content is obtained.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a system diagram of a coal fired boiler according to this embodiment.
The flow rate of coal supplied from the bunker 11 is adjusted by a feeder 12 and conveyed to the pulverized coal production apparatus (mill) 2 by primary air. Coal (pulverized coal) pulverized into fine powder by the mill 2 is conveyed through the coal feeding pipe 10 by the PAF 3, supplied to the burner 6 provided on the furnace wall surface, and burned in the furnace 1. Combustion air that is introduced by the FDF 9 and burns pulverized coal becomes high-temperature air of about 300 to 400 ° C. in the heat exchanger 4, and is burned from the wind box 5 provided on the furnace wall surface to the outer periphery of the burner 6 and the after-air port 7. Air is introduced into the furnace 1.

  The exhaust gas generated by the combustion of coal in the boiler furnace 1 is sent to the denitration device 13, after the nitrogen oxides are reduced by the denitration device 13, the gas temperature is lowered by the heat exchanger 4 and the dust is removed by the electric dust collector 14. Is done. The exhaust gas after dedusting is released from the chimney 16 to the atmosphere with sulfur oxides reduced by the desulfurization device 15.

  The furnace front and rear walls between the burner 6 provided in the lower area of the front wall and the rear wall of the furnace 1 and the after air port 7 provided in the upper area of the front wall and the rear wall of the furnace 1 A mixing promotion port 8 is provided for promoting the mixing of the gas flow. Boiler exhaust gas sucked by the GRF 17 is fed into the mixing promotion port 8 as a high-speed jet.

  In FIG. 2, a branch exhaust gas passage is provided in the exhaust gas circulation passage for sucking a part of the exhaust gas discharged from the boiler furnace by the GRF 17 and recirculating it to the bottom of the furnace, and the tip of the branch exhaust passage is connected to the side wall of the furnace. The structure connected to the some mixing promotion port 8 provided in (the wall surface which connected each both ends of a furnace front wall and a rear wall) is shown.

  FIG. 3 shows the change in the NOx concentration (average value) in the horizontal cross section of each different part in the gas flow direction in the furnace when the mixing promotion port 8 is provided on the furnace wall. By providing the mixing promotion port 8, the NOx reduction rate in the reduction region is accelerated, and the nitrogen oxide concentration at the furnace outlet is reduced.

  FIG. 4 shows the amount of gas entrained in the vicinity of the wall surface (the amount of ambient gas taken into the AAP jet) when the penetration force is the same for the swirl flow and the straight flow of the combustion gas ejected from the mixing promotion port 8. Here, x / Y is a value obtained by making the distance x from the mixing promotion port 8 in the furnace direction dimensionless by the distance Y from the wall surface to the furnace center, and Me / M0 is the entrained amount Me at the point x in the furnace center. This is a value made dimensionless by the surrounding gas amount M0 entrained by the straight flow.

  When the penetration force of the gas ejected from the mixing promotion port 8 into the furnace 1 is constant, the swirling flow has a small x / Y, that is, the entrainment amount of the surrounding gas by the swirling flow near the wall surface Compared with the amount of gas entrained, the amount of entrained gas by the straight flow increases as the straight flow increases in x / Y, that is, toward the center of the furnace. FIG. 4 also shows the change in the entrainment amount when the swirl velocity component / axial velocity component (Sw number) of the swirl flow introduced from the mixing promotion port 8 is varied.

  As the Sw number increases, the amount of exhaust gas entrained near the wall surface of the swirl flow increases, but the amount of entrainment in the center of the furnace decreases. When the Sw number is 1.0 or more, the entrainment amount of the swirling flow at the center of the furnace becomes smaller than the entrainment amount of the straight flow. This is because the penetrating force of the swirling flow becomes weak because the swirling force is strong. Therefore, as the strength of the turning force, the Sw number is preferably in the range of 0.2 to 0.8.

  FIG. 5 shows an example of a longitudinal sectional view of the mixing promotion port 8. From the center of the mixing promotion port 8, a straight flow of the combustion promoting combustion gas and a swirling flow of the combustion gas are introduced into the furnace from the outer periphery. The ratio between the center straight flow and the outer peripheral swirl flow can be adjusted by the register structure 18 provided in the outer peripheral flow path.

  The combustion gas is blown from the mixing promotion port 8 at a high speed into an atmosphere in which the combustion gas region formed by the flame from the burner 6 and the unburned gas region containing a large amount of air are mixed, thereby changing the flow state in the furnace. And promotes mixing of unburned gas. It is desirable to blow combustion gas from the mixing promotion port 8 in the vicinity of the slow combustion of the uppermost burner 6. By blowing a swirling jet of high-speed combustion gas from the mixing promotion port 8 at a position where the combustion of the uppermost burner 6 has become slow, mixing of the combustion gas region in the furnace and the unburned gas region is promoted, and in the exhaust gas The NOx concentration in the exhaust gas becomes uniform, a sufficient reduction action is obtained in the reduction region up to the after-airport 7, and the NOx concentration in the exhaust gas becomes low at the furnace outlet.

The combustion gas introduced from the mixing promotion port 8 is preferably a small amount of high-speed jet. The mixing promotion port 8 is for uniformizing the flow state in the furnace, and it is desirable not to involve a chemical reaction such as an oxidation reaction. Although it is difficult to promote the mixing of the fluid state in the furnace 1 with a small amount of blowing, by blowing with a high-speed swirling jet, the surrounding exhaust gas is involved, and the action of improving the gas mixing state in the furnace 1 occurs. .
Therefore, by using the furnace recirculation exhaust gas of the boiler as the combustion gas introduced from the mixing promotion port, there is an effect of suppressing a chemical reaction in the reduction region.

  In addition, blowing a high-speed swirling jet of combustion gas from the mixing promotion port 8 also has the effect of reducing the CO concentration in the exhaust gas. The reason for this is that carbon monoxide remaining in the combustion gas region in the furnace reacts with residual oxygen in the unburned gas region and becomes carbon dioxide, which is the final product, by promoting mixing with the unburned gas region. It is.

In the case of the opposed combustion method, an incompletely combusted region with high CO concentration is formed in the vicinity of the side wall above the burner (a pair of furnace side walls connecting both ends of the front and rear walls of the furnace) (FIG. 17). , See FIG. Therefore, the mixing promotion port 8 is installed in the region where the CO concentration is high. FIG. 17 shows a vertical distribution diagram of the O ₂ concentration in the combustion exhaust gas (FIG. 17A) and a horizontal cross-sectional distribution diagram (FIG. 17) by the opposed arrangement of the burners 6 of the conventional opposed combustion type boiler apparatus. 17 (b)) and FIG. 18 is a distribution diagram of the CO concentration in the combustion exhaust gas in the horizontal cross section of the same furnace shown in FIG. 17 (b).

  FIG. 6 is a side view showing the arrangement of the burner 6, the mixing promotion port 8 and the after-air port 7 provided on the front wall 1a or the rear wall 1b of the furnace, and FIG. 7 shows the installation state of the mixing promotion port 8 on the furnace wall surface. FIG.

  The burner 6 and the after-air port 7 are arranged at the opposed positions on the front wall of the furnace and the rear wall of the furnace. However, as shown in FIG. 7, the mixing promotion ports 8 are staggered on the front wall 1a and the rear wall 1b. To do. The mixing promotion port 8 is at a position closer to the burner 6 side than an intermediate position between the burner 6 and the after air port 7 which are adjacent to each other.

  By arranging the mixing promotion port 8 at a position closer to the burner 6 than the after air port 7, the residence time until the mixing promotion gas composed of the combustion gas ejected from the mixing promotion port 8 reaches the after air port 7 can be increased. The reduction effect of NOx due to the promotion of mixing of the promotion gas and after air is further increased.

  FIG. 19 shows the NOx concentration distribution in the furnace of the prior art, FIG. 8 shows the NOx concentration distribution in the furnace when the mixing promotion port 8 is arranged at the opposed position of the furnace front wall 1a and the rear wall 1b, and FIG. The NOx concentration distribution in the furnace when the promotion port 8 is staggered with respect to each other at positions shifted from the opposed positions of the furnace front wall 1a and the rear wall 1b is shown.

  The high NOx concentration region and the low NOx concentration region formed by the uppermost burner 6 are not mixed, and the combustion exhaust gas rises in the furnace, and in the prior art, there is a concentration deviation until it is mixed at the after air port 7. However, in the case where the mixing promotion port 8 is disposed at the opposed position of the furnace front wall 1a and the furnace rear wall 1b between the burner 6 and the after-air port 7 shown in FIG. Although the deviation is eliminated, the high NOx concentration region and the low NOx concentration region are not mixed and rise to the after airport 7.

  Further, when the mixing promotion ports 8 are arranged in a staggered manner on the opposing wall surfaces as shown in FIG. 9, there are a high NOx concentration region and a low NOx concentration region in the furnace inner region near the furnace wall mounting portion of the mixing promotion port 8. By mixing, the NOx concentration in the furnace inner region in the vicinity of the furnace wall mounting portion has the effect of making it uniform.

FIG. 10 shows changes in the NOx concentration and unburned ash content when the combustion exhaust gas discharged from the furnace 1 as the mixing promotion fluid is supplied from the mixing promotion port 8.
As is clear from FIG. 10, the unburned ash concentration in the ash at the boiler outlet when the amount of boiler combustion gas input from the mixing promotion port 8 is changed is 20% of the amount of combustion air. Increase rapidly. Further, the combustion gas temperature at the corresponding combustion gas input position is lowered by the increase of the input combustion gas amount. Furthermore, if the amount of combustion gas to be input exceeds 10% of the amount of combustion air, the combustion gas temperature will decrease by 100 ° C or more, leading to a decrease in thermal efficiency, and further NOx reduction reaction may be delayed. Even so, the effect of reducing NOx by promoting the mixing of the combustion gas into the combustion air is not so great. Therefore, it is desirable that the amount of boiler combustion gas introduced from the mixing promotion port 8 is 10% or less of the amount of combustion air.

  Further, as shown in FIG. 11, the mixing promotion gas flow path in the mixing promotion port 8 may be divided into a plurality of parts so that the mixing promotion gas can be supplied into the furnace. 11A shows a vertical sectional view of the mixing promotion port 8, and FIG. 11B shows a horizontal sectional view.

Since the mixing promotion port 8 has two partition plates 20 and 20 disposed in the center of the port 8 toward the inside of the furnace to divide the mixing promotion gas flow path into three, the center of the port 8 Is formed into the main flow 21 and the side flows 22 and 22 on both sides thereof. The flow path for the side flow 22 formed between the partition plates 20, 20 and the inner wall of the mixing promotion port 8 becomes a narrow passage toward the outlet side of the mixing promotion port 8. A flow path contracting member 29 is arranged on the inner peripheral side of the mixing promotion port 8 toward the outlet side. Further, a main flow inflow hole 24 and a subflow inflow hole 25 are provided at the base of the port 8, and the opening area of the inflow holes 24, 25 can be adjusted by sliding the flow rate regulators 26, 27.
Thus, by dividing the jet flow ejected from the mixing promotion port 8 into the furnace in the horizontal direction, there is an effect of promoting uniform mixing of the combustion gas from the burner 6 in the furnace.

  In FIG. 12, the mixing promotion port 8 in which the NOx concentration and the CO concentration in the furnace gas when the jet flow ejected from the mixing promotion port 8 into the furnace is divided into three in the horizontal direction is not divided into three in the horizontal direction is used. It shows how it falls compared to the case.

Further, in the burner portion having a plurality of stages, the burners 6 are not arranged in opposed positions (sometimes referred to as opposed arrangement) in the same row in the vertical direction of the furnace front wall 1a and the rear wall 1b. As shown in the schematic structural view of the furnace viewed from the side wall 1c side and the side view of the front wall surface or the rear wall surface of the furnace in FIG. 13B, at least the uppermost burner 6 faces the front wall 1a and the rear wall facing each other. By arranging the 1b uppermost burners 6 in a staggered arrangement with each other, the combustion gas containing unburned components in the burner portion is well mixed.
At this time, the mixing promotion port 8 is for making the flow state in the furnace uniform, and it is desirable to blow in as little as possible. For that purpose, if the mixing promotion port 8 is installed in the furnace side wall 1c as shown in FIG. 13, the mixing in the vicinity of the side wall 1c can be promoted.

FIG. 14 shows the result of confirming the NOx reduction effect in the combustion exhaust gas due to the difference between the staggered arrangement and the opposed arrangement of the burners 6 by numerical analysis.
15A shows the case where all the burners 6 are arranged opposite to each other (see FIG. 15B), the case where the uppermost burners 6 are arranged in a staggered manner (see FIG. 15C), and the uppermost burner 6 The results of confirming the NOx reduction effect and the CO reduction effect in the combustion exhaust gas in the exhaust gas when the and the after airports 7 are arranged in a staggered manner by numerical analysis are shown.

  However, the jet including pulverized coal from the uppermost burner 6 on one wall does not collide with the burner jet from the opposing wall at the center in the furnace, and rises in a curved manner at a position close to the opposing wall from the center. Therefore, as shown in the perspective view of the furnace of FIG. 16, the after air ports 7 provided on the front wall 1a and the rear wall 1b facing each other are arranged in a staggered arrangement opposite to the uppermost burner 6 (immediately above the burner 6 on the same wall surface). Without arranging the after-air port 7, an arrangement in which the pulverized coal jet from the burner 6 and the air jet from the after-air port 7 on the opposite wall face each other) Mixing is promoted by hitting a curved rising jet directly.

  Industrial applicability is high as a boiler device capable of reducing the NOx concentration and the CO concentration in the exhaust gas.

It is a systematic diagram which shows one Example of the boiler apparatus system which becomes an Example of this invention. It is a systematic diagram which shows one Example of the boiler apparatus system which becomes an Example of this invention. It is a figure which shows transition of the average NOx density | concentration of the boiler height direction of the boiler apparatus which becomes an Example of this invention. It is the figure which showed the difference of the surrounding gas entrainment amount in the wall vicinity of the swirling flow of the mixing promotion port and the straight flow of the mixing promotion port in the boiler apparatus which becomes an Example of this invention, and a furnace center part. It is a longitudinal cross-sectional view of the mixing promotion port of the boiler apparatus which becomes an Example of this invention. It is a side view which shows arrangement | positioning of the burner arrange | positioned on the furnace wall of the boiler apparatus which becomes an Example of this invention, an after air port, and a mixing promotion port. It is a horizontal sectional view of the mixing promotion port installation part of the furnace wall of the boiler apparatus which becomes an Example of this invention. It is a figure which shows NOx density | concentration distribution in a furnace at the time of arrange | positioning a mixing promotion port facing with the boiler apparatus which becomes an Example of this invention. It is a figure which shows NOx density | concentration distribution in a furnace at the time of making a mixing promotion port into a staggered arrangement | sequence with the boiler apparatus which becomes an Example of this invention. It is a figure which shows the relationship between the combustion gas input from the mixing promotion port of the boiler apparatus which becomes an Example of this invention, the combustion gas temperature in a furnace exit, the NOx density | concentration in combustion gas, and the unburned part in ash. It is sectional drawing (FIG. 11 (a)) of the vertical direction of the mixing promotion port of the boiler apparatus which becomes an Example of this invention, and sectional drawing (FIG.11 (b)) of a horizontal direction. It is a figure which shows a mode that the NOx density | concentration and CO density | concentration in the gas in a furnace at the time of using the mixing promotion port of FIG. 11 fall compared with the case where the mixing promotion port which is not divided into 3 in the horizontal direction is used. It is the schematic structure figure (FIG.13 (a)) of the furnace seen from the side wall side of the boiler apparatus which becomes an Example of this invention, and the side view (FIG.13 (b)) of a furnace front wall surface or a rear wall surface. It is a figure which shows the result of having confirmed the NOx reduction effect in combustion exhaust gas by the difference in the staggered arrangement | sequence of the burner of a boiler apparatus which becomes an Example of this invention, and opposing arrangement | sequence by numerical analysis. The figure (FIG. 15 (a)) which shows the result which confirmed the NOx reduction effect and CO reduction effect in combustion exhaust gas by the staggered arrangement of the burner of the boiler apparatus which becomes an Example of this invention, and opposing arrangement | sequence by numerical analysis, all burners It is the top view (FIG.15 (b)) made into the opposing arrangement | sequence, and the top view (FIG.15 (c)) which made the uppermost stage burner arranged in the dust. It is a furnace perspective view of the boiler apparatus which becomes an Example of this invention. FIG. 17 is a vertical distribution diagram (FIG. 17A) and a horizontal sectional distribution diagram (FIG. 17B) of the O ₂ concentration in the combustion exhaust gas by the opposed arrangement of the burners of the opposed combustion type boiler apparatus. It is a distribution map of CO density | concentration in the combustion exhaust gas in the same furnace horizontal cross section shown in FIG.17 (b). It is the figure which showed NOx concentration distribution in the furnace of the boiler apparatus of a prior art.

Explanation of symbols

1 furnace 1a front wall 1b rear wall 1c side wall 2 mill 3 PAF
4 Heat exchanger 5 Air box 6 Burner 7 After air port 8 Mixing promotion port 9 FDF
DESCRIPTION OF SYMBOLS 10 Coal feeding pipe 11 Bunker 12 Feeder 13 Denitration device 14 Electric dust collector 15 Desulfurization device 16 Chimney 17 GRF
18 register 20 partition plate 21 mixing promotion gas main flow 22 mixing promotion gas subflow 24 main flow inflow hole 25 subflow inflow holes 26 and 27 mixing promotion gas flow rate regulator 29 flow path contraction member

Claims (11)

In a boiler device that burns solid fuel containing coal in a furnace,
A plurality of burners for burning solid fuel with an air amount less than the theoretical air ratio are provided for each stage, and one or more burners are provided in the combustion gas flow direction.
A plurality of after-air ports, each downstream of the burner, for injecting combustion air that is insufficient for solid fuel combustion in the burner into the furnace, and one or more stages in the combustion gas flow direction;
A plurality of mixing promotion ports for supplying a part of boiler exhaust gas discharged from the boiler downstream of the burner and upstream of the after-air port, and one or more mixing promotion ports are provided in the combustion gas flow direction; And the after-air port and the mixing promotion port are arranged on a pair of opposing wall surfaces of the furnace,
When each mixing promotion port of each stage is arranged at the same horizontal position on the opposite furnace wall surface, at a position opposed to each other or at a position deviated from the facing position, and when there are a plurality of mixing promotion ports in the gas flow direction, Each mixing promotion port of each stage is disposed at an intermediate position between two adjacent mixing promotion ports of adjacent stages.   The boiler device according to claim 1, wherein the mixing promotion port is provided on a furnace wall at a location where the mixing promotion gas can be blown into a region where fuel combustion in the uppermost burner becomes slow.   The mixing promotion port is not disposed on the two opposing wall surfaces of the furnace in which the burner and the after-air port are disposed, but is disposed on two opposing side wall surfaces that connect both ends of the two opposing wall surfaces. The boiler device according to claim 1 or 2.   The boiler device according to any one of claims 1 to 3, wherein the mixing promotion port includes a swirling portion that forms a swirling flow of the mixing promoting gas and supplies the mixing promoting gas into the furnace.   The boiler device according to any one of claims 1 to 3, wherein a gas dividing member that divides a gas blown into the furnace from the mixing promotion port in a horizontal direction is provided at an outlet portion of the mixing promotion port.   6. The boiler apparatus according to claim 5, wherein the gas dividing member has a shape such that the directions of gases blown from the mixing promotion port into the furnace are not the same direction.   The plurality of burners at the uppermost stage are respectively disposed on the same horizontal plane with the pair of opposed furnace wall surfaces and shifted from the opposed positions, and the plurality of after-air ports at each stage are arranged at the pair of opposed furnaces. Each of the lowermost after-airports arranged on the same horizontal plane on the wall and provided on the same wall on the downstream side of the uppermost burner is above the intermediate position of two adjacent burners in the plurality of uppermost burners. The boiler device according to any one of claims 1 to 6, wherein the boiler device is arranged in a vertical direction.   The at least one stage of each after-air port is disposed above an intermediate position between two adjacent burners among a plurality of uppermost burners provided on the same wall surface on the upstream side. The boiler apparatus in any one of 6.   The boiler device according to claim 7 or 8, wherein each after-air port of each stage is arranged at an intermediate position between two after-air ports adjacent to each other in the upper and lower stages.   The amount of boiler combustion gas blown into the furnace from the mixing promotion port of the boiler device according to any one of claims 1 to 9 is 10% or less of the amount of combustion air, and the air ratio after mixing is equal to or less than the theoretical air ratio. A method for operating a boiler device, comprising:   The operating method of the boiler apparatus according to claim 10, wherein a gas flow rate blown out from the mixing promotion port into the furnace is 50 m / s or more.

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