JP2005291534A - Combustion equipment and method of biomass fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide combustion equipment and a combustion method of biomass fuel, capable of reducing a CO<SB>2</SB>exhaust quantity, by attaining low NOx and high efficiency combustion of combustion exhaust gas, even if the biomass fuel is mixedly burnt with coal as auxiliary fuel in the combustion equipment such as a conventional coal burning boiler. <P>SOLUTION: This combustion equipment of the biomass fuel has a pulverized coal fuel supply flow passage and a biomass fuel supply flow passage for respectively supplying pulverized coal and fine powder of the biomass fuel crushed for inputting and mixedly burning coal in a furnace 1 together with the crushed pulverized coal with woody biomass fuel as sub-fuel in a separate system, a biomass fuel injection nozzle 4 arranged on the tip of the biomass fuel supply flow passage and jetting the fine powder of the biomass fuel 11 into the combustion equipment, a biomass fuel combustion air nozzle arranged on the outer peripheral side of the biomass fuel jetting nozzle, and a flame holder 9 arranged on the tip of the biomass fuel jetting nozzle 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

TECHNICAL FIELD The present invention relates to a technique for reducing CO ₂ emissions by using a biomass fuel as an auxiliary fuel to achieve low NOx and high-efficiency combustion of combustion exhaust gas in a coal burning combustion apparatus.

  Biomass fuel as used in the present invention is a plant-based fuel other than fossil fuels, and the type thereof is not limited to a specific one. It shall mean a plant-based fuel having a calorific value that can be a fuel containing a next processed product.

In recent years, wood-based biomass co-firing technology has attracted attention as one of the measures for reducing CO ₂ emissions in boilers that use fossil fuel as the main fuel.

In particular, in Europe and North America, woody biomass fuel is often mixed and introduced into an existing coal pulverizer, mixed and pulverized, and then supplied together with pulverized coal into a coal-fired boiler furnace for combustion. As wood-based biomass fuels, those that have been finely pulverized and pelletized before being transported to the location of the boiler, and those that are in the form of wood chips with a particle size of about 50 mm or less are distributed. ing. As another example of co-firing wood-based biomass fuel and coal, the wood-based biomass fuel is pulverized by a dedicated pulverizer and then fed to the pulverized coal transport line to mix them and co-fire in the furnace A lot of technology is also done.
Japanese Patent Laid-Open No. 2002-241761

  As described above, when pelletizing the woody biomass fuel, the woody biomass fuel is finely pulverized to produce pellets. In this process, very large pulverization power is required. Compared with the pulverization power required for coal used in ordinary coal-fired thermal power, it is known that 10 times or more power is required to obtain the same particle size with woody biomass fuel. For example, in coal, when a roller mill is used as a pulverizer, it is 10 to 20 kWh / t, whereas when biomass fuel is used as an impact mill (used most for pulverizing biomass fuel) as a pulverizer The power is normally 100 to 200 kwh / t. However, since biomass fuel is easier to burn than coal if the particle size is the same, the pulverized particle size can be made coarser than pulverized coal. That is, in the pulverization of biomass fuel, it is preferable in terms of operation that the pulverized particle size is coarsened to a combustible limit.

  The next problem is the location of biomass fuel. When coarse particles are put into the furnace, if the terminal sedimentation rate of the coarse particles is faster than the combustion gas rising speed in the furnace, the coarse particles do not get on the rising flow of the combustion gas and fall to the furnace bottom. . In particular, when biomass fuel is introduced below the furnace of a coal-fired boiler, a circulatory flow of combustion gas is formed as a downward flow in the hopper at the bottom of the furnace, and the downflow is accompanied by coarse particles and the fall becomes significant. . Therefore, it is desirable to put biomass fuel above the furnace as much as possible.

  However, in a coal-fired boiler in which combustion exhaust gas is reduced in NOx, two-stage combustion is normally performed, and an air outlet OFA (Over Firing Air) port is provided above the furnace. When biomass fuel is introduced in the vicinity of this OFA, it interferes with the combustion air from the OFA and is likely to be rapidly mixed. This makes it difficult to burn the biomass fuel at a low air ratio, thus increasing the NOx concentration in the exhaust gas. It will be. Moreover, since the combustion time of biomass fuel is insufficient, the amount of unburned fuel also increases.

  Therefore, it is desirable to supply biomass fuel between the burner and OFA from the furnace wall, which is separated to some extent, into the furnace. The change is difficult, and biomass fuel cannot be co-fired as a secondary fuel in a conventional coal-fired boiler at the existing burner position.

An object of the present invention is to achieve low NOx and high-efficiency combustion of combustion exhaust gas and reduce CO ₂ emissions even when a conventional combustion apparatus such as a boiler dedicated to coal is co-fired with coal using biomass fuel as an auxiliary fuel. It is an object of the present invention to provide a combustion apparatus and a combustion method for biomass fuel.

  When wood biomass fuel is used as a secondary fuel and mixed with pulverized coal that has been pulverized into a furnace and co-fired, the effect of reducing NOx emissions from biomass fuel can be expected. It is not enough to blow into the interior, and it is necessary to devise in order to accelerate the ignition of biomass fuel.

That is, the object of the present invention is achieved by the following solution means.
The invention according to claim 1 is a biomass fuel combustion apparatus in which coal is used as a main fuel, biomass fuel is used as a secondary fuel, and the combustion air is supplied into the furnace and burned. A pulverized coal fuel supply channel and a biomass fuel supply channel, a biomass fuel injection nozzle for injecting fine powder of biomass fuel provided at the tip of the biomass fuel supply channel into the combustion device, and the biomass A combustion apparatus for biomass fuel comprising a combustion air nozzle for biomass fuel provided on the outer peripheral side of the fuel injection nozzle and a flame holder provided at the tip of the biomass fuel injection nozzle.

  According to a second aspect of the present invention, there is provided a pulverized coal injection portion connected to the pulverized coal fuel supply flow channel for injecting the pulverized coal, the biomass fuel injection nozzle being provided separately from the pulverized coal injection portion, and the biomass The combustion air nozzle which supplies the combustion air which burns biomass fuel to the outer peripheral side of a fuel injection nozzle is arranged, The flame holder of the step-like expansion structure provided in the front-end | tip of the said biomass fuel injection nozzle was provided. It is a combustion apparatus of the described biomass fuel.

  Invention of Claim 3 is a combustion apparatus of the biomass fuel of Claim 1 which provided the turning apparatus in the combustion air nozzle for the said biomass fuel.

  According to a fourth aspect of the present invention, there is provided a heat insulating material that blocks heat transfer from the combustion air side between the biomass fuel injection nozzle and a combustion air nozzle for biomass fuel provided on the outer peripheral side of the nozzle. The biomass fuel combustion apparatus according to claim 1.

  According to a fifth aspect of the present invention, a biomass fuel ejection nozzle that ejects fine powder of biomass fuel is disposed at the center side, a pulverized coal ejection nozzle that ejects pulverized coal is disposed on the outer peripheral side of the biomass fuel ejection nozzle, and the fine powder A combustion air nozzle for supplying combustion air for burning biomass fuel and pulverized coal fuel is disposed on the outer peripheral side of the coal ejection nozzle, and a flame stabilizer having a stepped enlarged structure provided at the tip of the pulverized coal ejection nozzle. The biomass fuel combustion apparatus according to claim 1 provided.

  The invention according to claim 6 is the biomass fuel combustion apparatus according to claim 1, wherein the furnace is a coal fired boiler that generates steam.

  The invention according to claim 7 is a biomass fuel combustion method in which coal is used as a main fuel, biomass fuel is used as a secondary fuel, and combustion air is supplied into the furnace and combusted. In this method, pulverized pulverized coal is supplied into the furnace. The biomass fuel that is supplied to the furnace and burned together with the biomass fuel fines so that the local air ratio when the biomass fuel fines are burned in the furnace from a system different from the pulverized coal is 0.6 or less. It is a combustion method.

  The invention according to claim 8 is the combustion of biomass fuel according to claim 7, wherein the combustion air of the biomass fuel is jetted into the furnace from the outside of the jet flow of the biomass fuel at a speed faster than the flow velocity of the biomass fuel transfer air. Is the method.

  The invention according to claim 9 is the biomass fuel combustion method according to claim 7, wherein the furnace is a coal-fired boiler that generates steam.

According to the first, second, fifth, and seventh aspects of the present invention, stable combustion of woody biomass fuel is possible, and the reduction effect of unburned fuel by using volatile biomass fuel and the reduction range of biomass fuel Since there is a reducing action on NO by HCN, NH _{3 and the} like generated by combustion of NO, it is possible to enhance the denitration effect in the furnace and contribute to safety and CO ₂ emission reduction (preventing global warming).

  According to the inventions of claims 2 and 5, since the flame holder has a step-like enlarged structure, a stagnation region of the biomass fuel is formed inside the furnace of the flame holder, the ignitability is good, and the biomass fuel is stable. Combustion is obtained.

  According to the third aspect of the present invention, since the swirl device is provided in the combustion air nozzle for biomass fuel, the ignitability of the stagnation region of the biomass fuel is further promoted, and stable combustion of the biomass fuel can be obtained.

  According to the fourth aspect of the present invention, since the heat insulating material for blocking heat transfer from the combustion air side is provided between the biomass fuel injection nozzle and the combustion air nozzle for biomass fuel, supply of biomass fuel is provided. Is stopped, it is difficult for heat to be transmitted to the biomass fuel deposited inside the burner, so that the deposited biomass fuel can be prevented from spontaneous ignition.

  According to the sixth and ninth aspects of the invention, it is possible to diversify boiler fuel by using the biomass fuel combustion apparatus as a furnace for a coal fired boiler.

  According to the eighth aspect of the present invention, the combustion air for biomass fuel is jetted into the furnace from the outside of the jet flow of the biomass fuel at a speed faster than the flow velocity of the biomass fuel transport air. Mixing of a gas such as hydrocarbons produced in the above and a combustion gas from the combustion of coal is promoted, which is effective for NOx reduction.

  According to the ninth aspect of the present invention, it is possible to reduce the NOx combustion of the fuel in a coal-fired boiler using coal as the main fuel compared to the conventional one.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of a coal-fired boiler using pulverized coal obtained by finely pulverizing coal as the main fuel and using biomass fuel as an auxiliary fuel.

  FIG. 1 shows a structure in which three stages of burners 3 in a wind box 5 provided on a furnace wall surface of a coal-fired boiler are arranged to face each other. In the case of this coal-fired boiler, six coal pulverizers (not shown) are installed, and one coal pulverizer is provided for each burner stage, for a total of three pulverizers. The pulverized coal thus supplied is supplied to the burners 3a, 3b, and 3c of each stage by airflow conveyance. When biomass fuel is used as an auxiliary fuel, a biomass fuel pulverizer is provided instead of one of the three coal pulverizers.

  The finely pulverized biomass fuel from the biomass fuel pulverizer is air-flowed to the burner for burning the fuel, and the burner is used as a burner exclusively for biomass fuel, and the pulverized coal burner 3 for burning coal. There are cases where a pulverized coal and biomass fuel pulverized powder are supplied and burned together with combustion air into a furnace for combustion.

  As described above, in order to reduce the pulverization power of the biomass fuel, it is desirable to reduce the degree of pulverization of the biomass fuel and supply it into the furnace 1 in the form of coarse particles. When the terminal sedimentation rate of the coarse particles is faster than the ascending speed, the coarse particles do not ride on the upward flow and fall to the furnace bottom. Therefore, in order to minimize the risk of the coarse particles falling to the bottom of the furnace without riding on the upward flow, the burner 3a of the uppermost burner stage of the three burners 3a, 3b, 3c provided in FIG. Biomass fuel is input to

  FIG. 2 shows a structural diagram of the biomass fuel-burning burner 3a, and FIG. 7 shows a structural diagram of a mixed-burning burner 3d of biomass fuel and pulverized coal. Moreover, the installation which grind | pulverizes biomass fuel and supplies it to the burner provided in the furnace in FIG. 3 is shown.

  First, FIG. 3 will be described. The biomass fuel carried in from the outside is once stored in the biomass storage facility 14. Usually, it is stored in a primary storage station or equipment in a power plant premises equipped with a coal-fired boiler. Biomass fuel is supplied from many production areas, the situation of the primary pulverization equipment in each production area varies, and the characteristics of the biomass fuel vary depending on the season and weather. In particular, since the shape of the biomass fuel supplied to the power plant is indefinite, a crusher 15 such as a tab grinder dedicated to wood may be required. Biomass fuel is crushed to a medium particle size of about 15 mm in diameter by the crusher 15, and the magnetic metal is removed by the magnetic separator 16 and supplied to the receiving hopper 17.

  Biomass fuel is fed from the receiving hopper 17 through the flow path 18 into the storage bin 19 and then supplied to the fine pulverizer 20 for pulverization to a particle size capable of floating combustion in the furnace. The predetermined particle size in the pulverizer 20 varies depending on the type of raw material of the biomass fuel, but is finely pulverized to, for example, 2 to 3 mm. Since the fine powder from the fine pulverizer 20 includes dust, it is once collected by the bag filter 21 and then supplied to the biomass combustion apparatus provided in the furnace and burned.

  Another reason for using the bag filter 21 is that when the biomass fuel is supplied directly to the combustion device without removing the moisture contained in the biomass fuel, the moisture is brought into the furnace, so that the combustion efficiency of the boiler is increased. It will be reduced. Therefore, moisture in the gas phase is collected by the bag filter 21. The reason why a simple collector such as a cyclone is not used especially using the bag filter 21 is that it is difficult to effectively collect fine dust particles with the simple collector.

  Although not shown, if the cyclone of the simple collector is installed in front of the bag filter 21 and the two-stage dust removing method is adopted, the load of the bag filter 21 can be reduced.

  FIG. 2 shows a biomass fuel burning burner 3a of this embodiment. In FIG. 2, the biomass fuel 11 flows into the burner 3 a from below, flows in the horizontal direction through the center nozzle 4, which is a flow path at the center of the burner 3 a, and moves in a direction to be ejected into the furnace 1. A flame holder 9 having an enlarged portion in a stepwise manner with respect to the flow direction is provided at the tip of the central nozzle 4. Further, a heat insulating sleeve 7 can be provided on the outer periphery of the central nozzle 4 which is a flow path of the biomass fuel 11.

  The flame holder 9 has a rapidly expanding portion with respect to the flow of the biomass fuel, and the flame holder 9 and the biomass fuel 11 against the jet flow of the biomass fuel 11 into the furnace, that is, the biomass fuel 11 into the furnace. The stagnation region of the biomass fuel particles is stably formed at the contact portion with the jet of the gas, and this stagnation region becomes an ignition source, and the biomass fuel can be burned stably and continuously. Further, by expanding the shape of the flame holder 9 stepwise, a region where the stagnation region can exist in a steady state is formed, and the shape of the flame holder 9 has a rapidly expanding portion toward the inside of the furnace 1. As a result, stagnation of large biomass fuel particles can be formed.

  Further, a swirler 13 is provided so that the combustion air 12 can be supplied while swirling from the outer periphery of the central nozzle 4 which is the flow path of the biomass fuel 11. The swirler 13 is an axial flow swirler that swirls the combustion air 12. The amount of air for transporting the biomass fuel 11 is determined as the minimum flow rate at which the biomass fuel 11 can be transported, and the air ratio during combustion of the biomass fuel can be adjusted mainly by adjusting the amount of air for combustion. In this example, the burner air ratio in the combustion of biomass fuel was set to 0.6.

  In the example shown in FIG. 2, the periphery of the central nozzle 4 that supplies the biomass fuel 11 is covered with a heat insulating material 7. The combustion air supplied to the burner 3a for burning the biomass fuel 11 is supplied by branching a part of the combustion air used for the combustion of pulverized coal, which hinders combustion in the furnace 1. In order to reduce the moisture content of 50% to 60% of the woody biomass fuel to the target 20%, the temperature is set to 300 ° C. or higher. On the other hand, it is known that biomass fuel is pyrolyzed at 180 degrees or more, and especially when the supply of biomass fuel is stopped, the combustion air is about 1000 ° C. from the furnace inside the portion facing the furnace of the burner. In order to prevent overheating damage due to radiation of high-temperature combustion gas, the minimum flow rate is flowing at a temperature of 300 ° C or lower, but the biomass fuel deposited even in a small amount inside the burner is transferred from the combustion air side Since it is considered that spontaneous combustion occurs at a high temperature due to this, it is important to provide a heat insulating structure between the biomass fuel flow path and the combustion air flow path to prevent this.

  Further, when the particle size of the biomass fuel is adjusted to, for example, about 3 mm, a drift occurs inside the piping of the biomass fuel supply channel. When the center nozzle 4 which is the flow path at the center of the burner 3a is moved in the horizontal direction toward the furnace 1 in a state of drifting, and the biomass fuel is jetted into the furnace 1, the biomass fuel combustion burner 3a starts from the tip. The formed flame is also biased in the furnace, and stable combustion may not be continued. In addition, it is difficult to detect the flame by the flame detector 8 that monitors the formation of the flame by optically analyzing the light emission from a part of the flame in the figure using an optical fiber or the like, and the misfire is caused. A signal can be emitted. For this reason, in FIG. 2, as a measure for preventing the drift of the biomass fuel 11, the dispersion device 10 is provided in the center of the center nozzle 4, and the biomass fuel flowing in a biased direction flows toward the inner peripheral wall surface of the center nozzle 4. These are mixed with each other so as to make the concentration of biomass fuel substantially uniform.

  A venturi 6 for preventing flashback is provided upstream of the central nozzle 4 and a guide for causing the biomass fuel particles to collide with the dispersing device 10 along with a function of increasing the flow rate of fuel for preventing flashback. It also plays a role.

FIG. 7 shows a structural diagram of a mixed burner 3d of biomass fuel and pulverized coal.
This burner 3d can adopt a combustion method in which a flame is formed with pulverized coal and the biomass fuel 11 is introduced into this flame as compared with the biomass fuel burner 3a. Compared with the exclusive burner 3a for biomass fuel, it is possible to cope with a wide range of mixed combustion ratios (ratio of each input heat amount of pulverized coal and biomass fuel).

  As shown in FIG. 7, the biomass fuel 11 is supplied into the furnace 1 from a central nozzle 31 that is a burner central channel. The pulverized coal is supplied toward the inside of the furnace from the flow path 32 on the outer periphery thereof, and ignited by the flame holder 9 to form a stable flame.

  The combustion air 12 supplied to the wind box 5 to the burner of FIG. 7 is turned into a swirling flow by the swirlers 13 and 22 and is supplied to the furnace 1. In addition, an eccentric fluid 23 is provided at the tip of the outer peripheral surface of the center nozzle 31. The uneven fluid 23 forms a concentrated pulverized coal flow on the inner peripheral side of the pulverized coal flow path 32 and promotes ignition and flame holding in the vicinity of the flame holder 9.

  If the biomass fuel 11 is not supplied from the central nozzle 31 of the burner central flow path in this state, a pulverized coal flame is formed, but an unignited region still remains in the furnace on the downstream side of the burner in the central portion of the burner. become. That is, an ignition delay occurs in the center portion of the burner. If this state is significant, the amount of NOx generated increases due to an increase in unburned content and a reduction in the reduction region in the furnace on the downstream side of the burner. 11 and the biomass fuel is more easily pyrolyzed than pulverized coal, so the biomass fuel 11 injected into the furnace 1 ignites rapidly, and the flame temperature rises in the furnace on the downstream side of the burner. The ignition delay is reduced, the reduction region can be expanded, and unburned matter and NOx generation amount are reduced as compared with the combustion of pulverized coal alone.

  Further, with respect to a coal fired boiler consisting of only pulverized coal burners 3b and 3c, it is possible to replace a part of the burner of the coal fired boiler with the biomass combustion burner 3a or the mixed fired burner 3d of this embodiment.

  For example, when the biomass combustion burner 3a or the mixed combustion burner 3d of the present embodiment is used, a fuel with a high volatile content can be used, and the generated flame region has an advantageous feature that the reduction region is large, and these feature points are utilized. Therefore, it is possible to improve the denitration effect in the furnace by performing an operation in which the air ratio of the burners 3a and 3d is lowered compared with the air ratio of the pulverized coal-burning burners 3b and 3c.

The low NOx combustion effect by the biomass combustion burner 3a of a present Example is demonstrated using FIG. 4 and FIG.
FIG. 4 shows the result of a combustion test in which a biomass fuel-burning burner 3a (FIG. 2) is installed separately from the pulverized coal burners 3b and 3c in a test apparatus for pulverized coal combustion.

As for the arrangement of the burners, the pulverized coal burner 3b, the biomass fuel-burning burner 3a, and the OFA 2 were arranged in order from the lower stage to the upper stage. In the test that expected the denitration effect in the furnace, the gas residence time (arrival time) from the biomass fuel-burning burner 3a to the OFA 2 was set to 0.8 seconds. When the biomass fuel and the OFA 2 interfered with each other, an amount of air corresponding to the amount of biomass fuel and the amount of air for two-stage combustion was supplied from the biomass fuel-burning burner 3a.
Biomass fuel consisting of pine wood was used as a raw material. FIG. 4 shows the relationship between the heat ratio and the NOx concentration.
The mixed combustion rate is a value obtained by dividing the input heat amount of biomass fuel by the total input heat amount of pulverized coal and biomass fuel.

  Based on the case where pulverized coal and biomass fuel are supplied at the same air ratio, NOx decreases in proportion to the co-firing rate when the air ratio at the time of combustion of biomass fuel is reduced to 0.6 in consideration of the denitration effect, When the amount of air for two-stage combustion is supplied together with biomass fuel, NOx increases as the mixed combustion rate increases. This is because NOx regeneration in the OFA2 portion increases. This result shows that in a coal fired boiler in which two-stage combustion is performed, there is an appropriate position for supplying biomass fuel by the biomass fuel-burning burner 3a.

  Therefore, for the purpose of experimentally clarifying the flame holding effect, the biomass-burning burner 3a without the flame holder 9 shown in FIG. 5 is installed, and the pulverized coal burner 3b and the flame holder are not provided in order from the lower stage to the upper stage. A combustion test was conducted with the configuration of the biomass combustion burner 3a and OFA2, and the results were compared with the test results. The mixed firing rate was fixed at 15%. The result added to the data of FIG. 4 is shown in FIG. In the case of no flame holder, the NOx concentration was close to that when the two-stage combustion air was supplied from the biomass fuel-burning burner 3a of FIG. 4 (when the air ratio was increased).

  From these results, it was experimentally clarified that biomass fuel should be supplied to a position where it does not interfere with the flow surface of the OFA 2 and the combustion gas in the furnace, and that the biomass fuel needs to be ignited rapidly.

INDUSTRIAL APPLICABILITY The present invention can be used as a combustion technique such as a coal-fired boiler that achieves low NOx and high-efficiency combustion of combustion exhaust gas and reduces CO ₂ emission by using biomass fuel as an auxiliary fuel.

It is a boiler furnace sectional view to which the present invention is applied. It is sectional drawing of the biomass fuel combustion burner of the Example of this invention. It is a block diagram of the biomass fuel pre-processing apparatus of the Example of this invention. It is a figure which shows the relationship between the NOx density | concentration obtained by carrying out the combustion test by installing separately the combustion burner and pulverized coal burner of the biomass fuel of the Example of this invention, and a mixed combustion rate. It is sectional drawing of the biomass fuel combustion burner without a flame holder as the comparative example of this invention. It is a figure which shows the relationship between the NOx density | concentration obtained by the combustion test of the biomass burner without a flame holder as a comparative example of this invention, and a mixed combustion rate. It is sectional drawing of the co-firing burner of the biomass fuel and pulverized coal of the Example of this invention.

Explanation of symbols

1 furnace 2 air outlet (OFA)
3 Burner 3a Biomass fuel exclusive burner 3b, 3c Pulverized coal burner 3d Coal fired burner of biomass fuel and pulverized coal 4 Center nozzle 5 Wind box 6 Venturi 7 Heat insulation sleeve 8 Flame detector 9 Flame holder 10 Dispersing device 11 Biomass fuel 12 Combustion air 13 Swivel 14 Biomass storage equipment 15 Crusher 16 Magnetic separator 17 Receiving hopper 18 Channel 19 Storage bin 20 Fine crusher 21 Bag filter 22 Swivel 23 Differential fluid 31 Center nozzle 32 Pulverized coal flow channel

Claims (9)

In a combustion apparatus for biomass fuel, in which coal is the main fuel, biomass fuel is used as a secondary fuel, and the combustion air is supplied into the furnace and burned.
The pulverized coal fuel supply channel and biomass fuel supply channel for supplying the pulverized pulverized coal and biomass fuel pulverized powder in separate systems, respectively, and the biomass fuel fine powder provided at the tip of the biomass fuel supply channel in the combustion device A biomass fuel jet nozzle that jets into the biomass fuel, a combustion air nozzle for biomass fuel provided on the outer peripheral side of the biomass fuel jet nozzle, and a flame holder provided at the tip of the biomass fuel jet nozzle Biomass fuel combustion device. Connected to the pulverized coal fuel supply flow path and arranged with a pulverized coal ejection section for ejecting pulverized coal,
In addition to the pulverized coal ejection part, the biomass fuel ejection nozzle is arranged,
Arranging a combustion air nozzle for supplying combustion air for burning biomass fuel on the outer peripheral side of the biomass fuel ejection nozzle,
The biomass fuel combustion apparatus according to claim 1, further comprising a flame holder having a step-like enlarged structure provided at a tip of the biomass fuel ejection nozzle.   The biomass fuel combustion apparatus according to claim 1, wherein a swirl device is provided in the combustion air nozzle for biomass fuel.   The heat insulating material which interrupts | blocks the heat transfer from the said combustion air side was provided between the said biomass fuel injection nozzle and the combustion air nozzle for biomass fuel provided in the outer peripheral side of this nozzle, It is characterized by the above-mentioned. The biomass fuel combustion apparatus according to 1. A biomass fuel injection nozzle that ejects fine powder of biomass fuel is arranged on the center side,
Combustion air for supplying pulverized coal injection nozzles for injecting pulverized coal to the outer peripheral side of the biomass fuel injection nozzle and supplying combustion air for burning biomass fuel and pulverized coal fuel to the outer peripheral side of the pulverized coal injection nozzle Arrange the nozzle,
The biomass fuel combustion apparatus according to claim 1, further comprising a flame stabilizer having a step-like enlarged structure provided at a tip of the pulverized coal ejection nozzle.   The biomass fuel combustion apparatus according to claim 1, wherein the furnace is a coal-fired boiler that generates steam. In the method of burning biomass fuel, coal is used as the main fuel, and biomass fuel is used as the auxiliary fuel in the furnace together with the combustion air.
When the pulverized pulverized coal is supplied into the furnace and the biomass fuel pulverized powder is burned in the furnace from a system different from the pulverized coal, the local air ratio (combustion of biomass fuel into the amount of biomass fuel transported) (The value obtained by dividing the amount of air added by the theoretical amount of air for combustion of biomass fuel) is 0.6 or less, and is supplied to the furnace together with the fine powder of biomass fuel for combustion. Biomass fuel combustion method.   8. The biomass fuel combustion method according to claim 7, wherein the biomass fuel combustion air is jetted into the furnace from the outside of the jet flow of the biomass fuel at a speed faster than the flow rate of the biomass fuel transfer air.   The biomass fuel combustion method according to claim 7, wherein the furnace is a coal-fired boiler that generates steam.

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