JP4576365B2 - Coal / biomass mixed combustion system and mixed combustion method - Google Patents

Description

  The present invention relates to a coal / biomass co-firing system and a co-firing method provided with a co-fired boiler using coal powder obtained by pulverizing coal using a vertical pulverizer and biomass powder obtained by pulverizing biomass such as wood chips. The present invention relates to a coal / biomass co-firing system and a co-firing method capable of stable operation with high fuel supply reliability against changes in the properties of biomass.

In recent years, coal-fired thermal power has been reviewed as a fuel for power generation, and in addition to complying with laws and regulations (RPS law) that require electric utilities to use electricity generated from new energy, etc. over a certain percentage The spread of new energy (biomass (organic matter derived from animals and plants) power generation, etc.) is being promoted.
Further, the amount of CO ₂ produced inhibition, since it is available to turn CO ₂ emissions trading, biomass utilization promotion is achieved.

  The biomass power generation system has a coal-biomass co-firing technology in which coal and biomass are mixed and burned. This co-firing technology includes a single pulverization method in which coal and biomass are pulverized independently, and coal and biomass. A mixing and pulverizing method is known in which pulverized particles are mixed and then pulverized.

  As the former single pulverization method, the technique disclosed in Patent Document 1 is known. As shown in FIG. 9, the wood material is supplied onto the pulverization table 312 from the supply pipe 310 and pulverized by the pulverization roller 314. It is known that the object to be crushed is discharged to the outer periphery of the pulverizing table 312 and conveyed upward by an air flow 316 ejected from the lower periphery of the table 312 to classify the object to be pulverized into fine powder and coarse powder. Yes. This method makes it possible to effectively use a conventional coal pulverizer as a wood raw material pulverizer by setting the flow rate of the air flow and the diameter of the pulverization table in an optimal relationship.

As the latter mixing and pulverization method, techniques shown in Patent Documents 2 and 3 are known. A general mixing and grinding method is shown in FIG. Biomass accumulated in the receiving hopper 102 by the transport vehicle 101 is temporarily stored in the biomass storage tank 103 and is quantitatively supplied from the biomass storage tank 103. The biomass fuel supplied from the biomass storage tank 103 is mixed with the coal supplied in a fixed amount from the coal silo 104, and the mixed fuel 105 is put into the fuel hopper 106. The mixed fuel 105 charged into the pulverizer 107 from the fuel hopper 106 is pulverized by the pulverizer 107 and then supplied to the boiler furnace 108 as a mixed powder fuel.
The furnace main body 110 of the boiler furnace 108 is provided with a fuel supply nozzle 111 and a burner (not shown) that cooperates therewith. Further, a heat transfer tube 112 corresponding to a heater, an evaporator, a economizer, or the like is installed in the furnace. The combustion exhaust gas generated by the combustion of the mixed powder fuel supplied into the furnace heats the heat transfer tube 112 and is sent to the flue. An air heater (AH) 113 is disposed in the middle of the flue provided at the furnace outlet of the furnace body 110, and the combustion exhaust gas passing through the air heater 113 is released into the atmosphere through an exhaust gas treatment facility such as an ash collector. Is done. Further, hot air heated by the air heater 113 is supplied to the pulverizer 107 to dry the object to be crushed.

  In such a mixed pulverization method, the mixing rate of biomass is set to an upper limit of about 3 wt% with respect to coal due to the limitation of the pulverizer capacity. This is because when wood dust and coal are mixed and pulverized by a vertical pulverizer, a mill trip (power upper limit) is reached due to an increase in the thickness of the coal layer on the rotary table. Since wood waste is not a brittle material like coal, it is difficult to crush with the pressure and shearing force of the vertical crusher, the amount of internal stagnant wood waste and coal increases, and the thickness of the coal bed on the rotary table is compared to the normal coal grinding operation state. Greatly increase the operating power of the crusher. FIG. 11 shows a mill characteristic diagram when mixed and pulverized by a conventional pulverizing mill. FIG. 11A shows the relationship between the wood chip / waste wood mixing rate and the mill power ratio, and FIG. 11B shows the relationship between the wood waste / waste wood mixing rate and the fineness. The mill power increased by + 70% simply by mixing and grinding wood chips and the like with a heat input ratio of 5%. The drive load of a normal existing coal mill does not allow a 70% margin, indicating that this increase in mill power leads to a mill trip. As described above, when the mixing ratio of wood chips and the like is increased, the mill power is significantly increased and the fineness is reduced. The fineness indicates the degree of fineness of the pulverized particles, and a high fineness indicates that there are many particles having a small particle size. Therefore, it can be seen that the particle size of the pulverized material increases when the mixing ratio of wood chips and the like is increased.

JP-A-2005-113125 JP 2004-347241 A Japanese Patent No. 3712691

The problem with the mixed pulverization method is that biomass fuel, which is an elastoplastic material, is difficult to pulverize compared to coal pulverization. There is a problem that the diameter increases.
In addition, even a slight change in the type and properties of the biomass used as fuel causes the operation state of the pulverizer to fluctuate, which hinders the amount of fuel supplied and, in turn, affects the operation of the mixed-fired boiler.
On the other hand, in the single pulverization method, it is necessary to newly install a pulverizer having a structure and operation method for using biomass as a pulverization target, which increases costs. In addition, when the coal pulverizer is used for biomass single operation, the processing capacity is about 25% of the coal pulverization capacity, so it is necessary to install a plurality of pulverization mills or a large-capacity coal pulverizer. Arise.

  Therefore, in view of the above-mentioned problems of the prior art, the present invention provides a coal / biomass co-firing system and co-firing with high reliability of fuel supply against changes in the properties of biomass and enabling stable operation of vertical pulverizers and co-firing boilers. It aims to provide a method.

In order the present invention is to solve the above problems, the solid fuel placed on grinding table rotated by a motor, a plurality of the ground by pressing by a roller which operates in conjunction with the rotation of the table vertical type crusher (hereinafter referred grinder), and a height direction in the boiler furnace in which the fuel supply nozzle in a plurality of stages are arranged, pulverized fuel obtained by a pulverizer of the respective is corresponding each a coal-biomass co-firing system that will be supplied to the fuel supply nozzle of the stage,
Separately pulverizing biomass separately from pulverizer (hereinafter referred to as second pulverizer) that performs dedicated pulverization of coal or mixed pulverization of coal and biomass (hereinafter also referred to as pulverized coal including mixed pulverized product). And a sensor for detecting the moisture content of the biomass on the supply upstream side for supplying biomass to the first pulverizer,
And a controller configured to select a corresponding fuel supply nozzle from a plurality of fuel supply nozzles in a height direction based on a detection value of the sensor .

Preferably, when the moisture content of the biomass is high, the controller supplies the pulverized biomass to the fuel supply nozzle on the lower stage side of the boiler furnace, and supplies the fuel supply nozzle to the other fuel supply nozzle located on the upper stage side of the fuel supply nozzle. Supplying coal pulverized material,
On the other hand, when the moisture content of the biomass is low, the biomass pulverized product is supplied to the upper fuel supply nozzle of the boiler furnace, and the coal pulverized product is supplied to another fuel supply nozzle located on the lower side of the fuel supply nozzle. The controller may be configured to supply and burn the biomass pulverized material and the coal pulverized material to a separate fuel supply nozzle in the boiler furnace.

  According to the present invention, by providing the first pulverizer for pulverizing biomass alone as a dedicated system, the biomass mixing rate in other mixed pulverizers can be greatly reduced. Therefore, the influence which fluctuation | variation of biomass kind and a property has on a mixing grinder is minimized, and stability and reliability in operating a boiler are remarkably improved. Further, since the biomass mixing ratio in the mixing and grinding machine can be reduced, it is possible to prevent a significant increase in mill power and to reduce the particle size of the pulverized product.

Further, the fuel supply nozzle is provided in a plurality of stages in the height direction of the boiler furnace, and the biomass powder is obtained on the basis of the particle size (moisture content of biomass) of the biomass powder obtained by the first pulverizer. Control means for selecting a fuel supply nozzle to be supplied is provided.
In the present invention, the height position at which the biomass powder is charged into the boiler furnace can be arbitrarily set. When using hard-pulverizable biomass as fuel, the biomass particle size at the crusher outlet becomes relatively large, so that the residence time can be increased by supplying biomass powder from the fuel supply nozzle below the boiler furnace. In the case of biomass that can be easily pulverized, it may be supplied from a fuel supply nozzle on the middle or upper side. As described above, since the pulverizer can be appropriately operated according to the pulverization property of the biomass to be received, complete combustion of the pulverized fuel can be achieved and unburned loss can be reduced.

Furthermore, a detection means for detecting the moisture content of the biomass supplied to the first pulverizer (average particle diameter) is provided, and the fuel supply nozzle is selected by the control means based on the detection value of the detection means. It is characterized by doing so.
Biomass moisture content before pulverization is to greatly affect the particle size after grinding. That is, biomass having a high water content has a large particle size after pulverization, and similarly, if the average length of biomass before pulverization is large, the particle size after pulverization also increases. Therefore, by detecting the moisture content of the biomass before pulverization, it is possible to estimate the particle size of the readily pulverized. Here, the average particle diameter of the biomass refers to the average length at the short side of the primary crushed biomass chip.

Also, a plurality of vertical pulverizers (hereinafter referred to as pulverizers) for pressing and pulverizing the solid fuel placed on the pulverization table that is rotationally driven by a motor by a roller that operates in conjunction with the rotation of the table, A boiler furnace having a plurality of stages of fuel supply nozzles arranged in the height direction is prepared so that the pulverized fuel obtained from each of the pulverizers is supplied to the corresponding fuel supply nozzles of the respective stages. In addition to a pulverizer for exclusive coal pulverization or mixed pulverization of coal and biomass (hereinafter referred to as a second pulverizer), a pulverizer for pulverizing biomass alone (hereinafter referred to as a first pulverizer). Provided with a sensor for detecting the moisture content of the biomass on the upstream side of supplying the biomass to the first pulverizer, and the height direction based on the detection value of the sensor Select fueling nozzle of stages corresponding the fuel supply nozzle in a plurality of stages, and wherein the feeding and burning the pulverized biomass and coal pulverized in a separate stage fuel supply nozzle in the boiler furnace To do.

Further, when the moisture content of the biomass is high, the biomass pulverized product is supplied to the fuel supply nozzle on the lower stage side of the boiler furnace, and the pulverized coal product is supplied to another fuel supply nozzle located on the upper stage side of the fuel supply nozzle. On the other hand, when the moisture content of the biomass is low, the biomass pulverized product is supplied to the fuel supply nozzle on the upper stage side of the boiler furnace, and the other fuel supply nozzle located on the lower stage side of the fuel supply nozzle The coal pulverized product is supplied, and the biomass pulverized product and the coal pulverized product are supplied to a fuel supply nozzle in a separate stage and burned in the boiler furnace.

As described above, according to the present invention, the second pulverizer is provided by providing the first pulverizer for pulverizing biomass separately from the second pulverizer that performs pulverization exclusively for coal or mixed pulverization of coal and biomass. Can greatly reduce the biomass mixing ratio in the plant, minimizing the effects of changes in biomass type and properties, and greatly improving the stability and reliability of boiler operation. Further, since the biomass mixing ratio in the mixing and grinding machine can be reduced, it is possible to prevent a significant increase in mill power and to reduce the particle size of the pulverized product.
In addition, since the biomass powder can be arbitrarily set to the boiler, the proper pulverizer can be operated according to the pulverizability of the biomass to be received.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
1 is an overall configuration diagram of a system to which the present invention is applied , FIG. 2 is a side sectional view showing a schematic configuration of a vertical pulverizer, FIG. 3 is a diagram for explaining an operation pattern of the pulverizer, and FIG. overall configuration diagram of a system according to an embodiment, FIG. 5 is a graph showing the particle size of the grinder outlet for biomass moisture content, FIGS. 6 and 7 diagram for explaining the amount of heat input ratio supplied from the fuel supply nozzle, Figure 8 is turning It is a plane sectional view showing nozzle arrangement which forms a flow.

As shown in FIG. 1, the system to which the present invention is applied includes a coal storage facility 1 that stores coal 10 that has been primarily crushed (coarsely crushed) to a predetermined particle size or less as necessary, as well as coarsely crushed and dried. Obtained by the biomass storage facility 2 for storing the produced biomass 11, the vertical pulverizers 3a to 3c having the hoppers 4a to 4c to which the coal 10 or the biomass 11 is supplied, and the vertical pulverizers 3a to 3c A boiler furnace 5 to which the supplied pulverized fuel is supplied.
A plurality of vertical crushers 3a to 3c are provided, a first crusher 3a that crushes biomass 11 supplied from biomass storage facility 2, and a second that crushes coal 10 supplied from coal storage facility 1. And crushers 3b and 3c. Each of the first and second vertical crushers is composed of one or a plurality of units, but preferably includes one first crusher 3a and a plurality of second crushers 3b and 3c. Configure. Moreover, when applying to the existing pulverized coal cooking boiler system, the vertical crusher installed as a spare machine is good also as the 1st grinder 3a.

The biomass pulverizer (first pulverizer) 3a and the coal pulverizers (second pulverizer) 3b and 3c have the same configuration. A specific configuration of the vertical crusher 3 (3a to 3c) will be described with reference to FIG.
A substantially circular trapezoidal crushing table 32 is provided at the lower part of the cylindrical housing 31. The crushing table 32 is driven by a motor 36 installed at the lower part of the housing 31 and rotates at a low speed via a speed reducer. Is configured to do. A dam ring 33 is erected on the outer peripheral edge of the crushing table 32 so that the object to be crushed can form a deposited layer having a predetermined thickness on the crushing table 32. Further, a load is applied to the upper surface of the outer peripheral portion of the pulverizing table 32 at equal intervals in the circumferential direction by hydraulic pressure or a spring or the like, and the object to be pulverized while rotating in conjunction with the rotation of the pulverizing table 32. A crushing roller 34 that crushes the object to be crushed by applying a pressing force is provided.
The crushing roller 34 is supported so as to be rotatable around the end of the roller arm, and controls the pressing force for pressing the object to be crushed by adjusting the load such as the hydraulic pressure or the spring.

The material to be crushed supplied from the hopper 4 through the supply pipe 41 to the central portion of the pulverizing table 32 moves on the pulverizing table 32 in the outer peripheral direction by centrifugal force, and between the pulverizing race 37 and the pulverizing roller 34. It is bitten and crushed. The biomass supply pipe 41 is provided with a supply amount detection unit 42 for detecting the supply amount, and the supply amount is monitored.
A part 15 of the exhaust gas after combustion is guided to the lower part of the housing 31 through the exhaust gas recirculation path 16 by the exhaust gas circulation blower 7. The pulverized powder is dried by the exhaust gas. Of the powder conveyed to the upper part of the housing 31, the coarse powder falls on the crushing table 32 by gravity and is pulverized again. A fixed classifier or a rotary classifier 35 is provided on the upper portion of the housing 31 and is classified again. Fine powder having a particle size smaller than the predetermined particle size is carried out by a blown-up air stream and conveyed to the boiler furnace 5. Coarse powder larger than the predetermined particle size that has not penetrated the classifier 35 falls on the crushing table 32 and is pulverized again.

  As shown in FIG. 1, the furnace main body 51 of the boiler furnace 5 includes fuel supply nozzles 52a to 52c provided in a plurality of stages in the height direction, air nozzles, and burners (not shown) that cooperate with these nozzles. It is arranged. A heat transfer tube group 53 corresponding to a heater, an evaporator, a economizer, or the like is installed in the furnace. The combustion exhaust gas generated by the combustion of the pulverized fuel supplied into the furnace heats the heat transfer tube group 53 and is sent to the flue. An air heater 6 is arranged in the middle of the flue provided at the furnace outlet of the furnace main body 51, and the combustion exhaust gas in the flue is drawn by an induction fan and released into the atmosphere from the chimney through the air heater and the ash collector. The The high-temperature air 14 obtained by heating the outside air 13 with the air heater 6 is supplied to the coal pulverizers 3b and 3c and used for drying the coal. The combustion exhaust gas 15 partially branched from the outlet of the boiler furnace 5 is supplied to the biomass pulverizer 3a by the induction fan 7 via the combustion exhaust gas supply path 16, and is used for drying the biomass.

In this embodiment, the fuel supply nozzles 52a to 52c are provided corresponding to the pulverizers 3a to 3c, and are connected by independent supply pipes. When a plurality of fuel supply nozzles are installed at the same height, it is preferable that all the fuel supply nozzles positioned at the same height are connected to one pulverizer. For example, the biomass powder obtained by the biomass pulverizer 3a is supplied into the furnace from the fuel supply nozzle 52a, and the coal powder obtained by the coal pulverizers 3b and 3c is different from the fuel supply nozzle 52b, It is supplied into the furnace from 52c.
Biomass powder and coal powder separately supplied into the furnace from each fuel supply nozzle are mixed and burned in the furnace.

As another system to which the present invention is applied, separately from the biomass pulverizer 3a as the first pulverizer, biomass and coal are supplied to the mixed pulverizers 3b and 3c as the second pulverizer, and mixed and pulverized. The configuration is as follows. The biomass powder obtained by the biomass pulverizer 3a is supplied into the boiler furnace 5 from the fuel supply nozzle 52a, and the coal / biomass mixed powder obtained by the mixed pulverizers 3b and 3c is supplied by the fuel supply nozzles 52b and 52c. More, it is supplied into the furnace, and these are mixed and burned in the furnace.

FIG. 3 shows an operation example when six pulverizers A to F are installed. 3A is a coal boiler as a conventional example, FIG. 3B is a mixed-fired boiler as a system to which the present invention is applied , and coal and biomass pulverization are respectively used, and FIG. When mixed pulverization and biomass single pulverization are used in a mixed combustion boiler as a system to be used, (d) is a mixed combustion boiler as a comparative example, (e) is a mixed combustion boiler as a comparative example, This is a case of using mixed grinding using a spare machine.
The case of the conventional coal boiler is shown to Fig.3 (a). According to this, coal is pulverized by five pulverizers A to E, and the coal powder obtained from each pulverizer is supplied from the fuel supply nozzle of the boiler body 51 into the furnace. At this time, the grinder F is used as a spare machine. Assuming that the total heat supplied to the boiler body 51 is 100, the heat input is evenly distributed by five pulverizers, and the required heat input ratio per pulverizer is 20. The amount of coal supplied to the pulverizer is set so that this heat input is obtained.

On the other hand, the case of a coal / biomass co-fired boiler is shown in FIGS.
As shown in FIG. 3B, in the system to which the present invention is applied , the pulverizer F is used for biomass single pulverization, and the five pulverizers A to E are used for coal single pulverization. The heat input ratio (coal heat input / biomass heat input) is 19/0 for the pulverizers A to E and 0/5 for the pulverizer F with respect to the total heat amount 100. The amount of coal and biomass supplied to the pulverizer is set so that this heat input ratio can be obtained.
Further, as shown in FIG. 3 (c), the system the present invention is applied to pulverizer A~E used mixing and grinding of the coal and biomass, the grinder F may be used in the biomass alone grinding. Thus, by providing the pulverizer F dedicated to biomass and using the five pulverizers A to E for mixing and pulverization, the heat input ratio of the mixed pulverizers A to E is 19 / 0.2. As long as biomass is mixed, the biomass mixing rate per unit can be reduced. Therefore, a significant increase in power can be avoided and stable operation can be achieved.

On the other hand, FIG. 3D and FIG. 3E show cases where biomass and coal are mixed and pulverized by the pulverizers A to E and F without the biomass single pulverization.
(D) is an example in which a biomass pulverizer is not provided as a comparative example and a spare machine is not used, and (e) is an example in which a biomass pulverizer is not provided as a comparative example and a spare machine is also used for mixing and pulverization. . Since the comparative example shown in (d) does not include a biomass grinder, coal and biomass are supplied to the grinders A to E so that the heat input ratio is 19/1. In the comparative example shown in (e), coal and biomass are respectively supplied to the pulverizers A to F so that the ratio of heat input to the boiler is 15.8 / 0.8. Thus, when a biomass pulverizer is not installed, the mixing rate of biomass in the mixing pulverizer becomes high, the power is greatly increased, and the particle size of the obtained pulverized product becomes large.
As described above, according to the system to which the present invention is applied, the first pulverizer that pulverizes the biomass independently is provided as a dedicated system separately from the second pulverizer that performs coal pulverization or mixed pulverization. Regardless of the type and properties of the fuel, the fuel can be stably supplied, and the stability and reliability in operating the boiler are remarkably improved.

It shows an overall configuration diagram of a biomass co-firing system of the present embodiment in FIG. Hereinafter, detailed description of the same configuration as the system to which the present invention is applied will be omitted.
As shown in the drawing, the system according to the present embodiment includes a coal storage facility 1, and biomass storage facilities 2, a vertical grinder 3a~3f having a hopper 4a-4f, and a boiler furnace 5. Here, a configuration including six vertical crushers will be described as an example, but the number of crushers installed is not limited.
The present embodiment includes a coal supply line 18 that supplies the coal 10 from the coal storage facility 1 to the hoppers 4a to 4f, and a biomass supply line 19 that supplies the biomass 11 from the biomass storage facility 2 to the hoppers 4a to 4f. Valves 21 a to 21 f are provided on the coal supply line 18, and valves 22 a to 22 f are provided on the biomass supply line 19. The opening / closing control of these valves is performed by the control device 8 so that only one of the coal 10 and the biomass 11 is supplied to one hopper.

A plurality of stages of fuel supply nozzles 52 a to 52 f are installed on the side wall of the boiler furnace 5 in the height direction. The fuel supply nozzles 52a to 52f correspond to a single fuel supply nozzle for one pulverizer. The coal powder or biomass powder obtained by the pulverizer is connected to each fuel supply nozzle via a supply pipe.
In the present embodiment, the input height of the biomass pulverizer to the boiler furnace 5 can be arbitrarily set according to the particle size of the biomass powder. Preferably, the height position of the fuel supply nozzle that supplies biomass powder is selected based on the biomass moisture content or average length.
For example, when biomass 11 that is difficult to grind and requires a large amount of power for fine grinding is mixed, the biomass particle size at the outlet of the grinder becomes relatively large, so that the grinding is connected to the lowest fuel supply nozzle that can take a large furnace residence time. The machine is used as the first pulverizer for biomass pulverization and the other pulverizer is used as the second pulverizer for coal pulverization.
On the other hand, when the biomass 11 that can be easily pulverized is co-fired, the pulverizer connected to the middle or lower fuel supply nozzle is used as the first pulverizer for biomass pulverization. Thereby, according to the grindability of the biomass to accept, proper operation of a grinder becomes possible.

As described above, the selection of the input height of the biomass powder is performed based on the particle size of the biomass powder. The particle size of the biomass powder can biomass moisture content or we estimate before pulverization.
In FIG. 4, as an example, a humidity sensor 9 for detecting the moisture content of biomass is provided on the upstream side of the pulverizer. The relationship between the moisture content of biomass and the particle size of the pulverized product is shown in FIG. As shown in the figure, the higher the moisture content of the biomass, the harder it becomes and the particle size of the pulverized product becomes larger. Accordingly, the moisture content of the biomass before pulverization is detected by the humidity sensor 9, and the valves 21a to 21f and 22a to 22f are switched and controlled by the control device 8 according to the moisture content, and connected to the fuel supply nozzle of a predetermined height. The biomass is supplied to the grinding machine.

For example, when the moisture content of the biomass detected by the humidity sensor 9 is high, the particle size of the biomass powder obtained by the pulverizer becomes large. Thus, as the biomass 11 is fed to the crusher 3a connected to the lower side of the fuel supply nozzle 52a as shown in FIG. 6, the control unit 8 controls the opening and closing of the valve. Then, coal is supplied to the pulverizers B to F (3b to 3f) so that the heat input ratio is (19/0), and the pulverizer A (3a) has a heat input ratio of (0/5). To supply such biomass.
When the moisture content is low, biomass is supplied to the pulverizer 3f connected to the middle or upper fuel supply nozzle 52f as shown in FIG. Then, coal is supplied to the pulverizers A to E (3a to 3e) so that the heat input ratio is (19/0), and the heat input ratio is (0/5) to the pulverizer F (3f). To supply such biomass.
Similarly, a detection sensor for detecting the average length of the biomass 11 may be provided as an alternative to the humidity sensor 9 described above. Here, the average length of the biomass 11 refers to the average length of the long sides of the primary crushed biomass chip.

Further, in the above-described embodiment, as shown in FIG. 8, the fuel supply nozzles 52a to 52f of the boiler furnace 5 are supplied in a tangential direction with respect to the virtual circle in the furnace so as to form the swirl flow 62 in the furnace. You may comprise.
Thereby, the residence time of biomass powder becomes long, combustion in a furnace is accelerated | stimulated, and unburned loss can be reduced.

  According to the coal / biomass mixed combustion system and the mixed combustion method of the present invention, a first pulverizer that performs single pulverization of biomass is provided separately from a second pulverizer that performs single pulverization of coal or mixed pulverization of coal and biomass. Because of the configuration, stable operation can be performed regardless of changes in biomass properties, and the pulverizer power can be suppressed and pulverization can be performed, which is beneficial when applied to existing facilities.

1 is an overall configuration diagram of a system to which the present invention is applied . It is a sectional side view which shows schematic structure of a vertical crusher. It is a figure explaining the operation pattern of a pulverizer, (a) is a case of a coal boiler as a conventional example, (b) is a case where coal and biomass pulverization are respectively used in a mixed-fired boiler as a system to which the present invention is applied. (C) is a mixed-fired boiler as a system to which the present invention is applied , when mixed pulverization and single biomass pulverization are used, (d) is a comparative example when mixed pulverization is used in a mixed-fired boiler, (e) Is a case where mixed pulverization using a spare machine is used in a mixed-fired boiler as a comparative example. It is an overall configuration diagram of a system according to an embodiment of the present invention. It is a graph which shows the particle size of the grinder exit with respect to biomass moisture content. It is a figure explaining the heat input amount ratio supplied from a fuel supply nozzle, (a) is a top view, (b) is a side view. It is a figure which shows the example of the heat input ratio different from FIG. It is a plane sectional view showing nozzle arrangement which forms a swirl flow. It is side sectional drawing which shows the conventional grinder of a single grinding | pulverization system. It is a whole block diagram which shows the conventional mixed combustion system. A graph showing mill characteristics during mixing and pulverization, and when the wood chip mixing ratio is increased to 0 to 15% (heat input ratio) (horizontal axis), (a) is a pulverizer power ratio, and (b) is a graph showing fineness. It is.

DESCRIPTION OF SYMBOLS 1 Coal storage facility 2 Biomass storage facility 3, 3a-3f Vertical crusher 4, 4a-4f Hopper 5 Boiler furnace 7 Exhaust gas circulation blower 8 Controller 9 Humidity sensor 10 Coal 11 Biomass 18 Coal supply line 19 Biomass supply line 21a 21f Coal supply valve 22a-22f Biomass supply valve 32 Grinding table 34 Grinding roller 51 Furnace body 52a-52f Fuel supply nozzle

Claims (4)

The solid fuel placed on grinding table rotated by a motor, a plurality of vertical pulverizing machine for grinding by pressing by a roller which operates in conjunction with the rotation of the table (referred to hereinafter grinder), height A boiler furnace in which a plurality of fuel supply nozzles are arranged in the direction,
The pulverized fuel obtained by a pulverizer each is a corresponding said coal-biomass co-combustion system that will be supplied to the fuel supply nozzle in each stage,
Separately pulverizing biomass separately from pulverizer (hereinafter referred to as second pulverizer) that performs dedicated pulverization of coal or mixed pulverization of coal and biomass (hereinafter also referred to as pulverized coal including mixed pulverized product). A machine (hereinafter referred to as the first crusher),
On the supply upstream side for supplying biomass to the first crusher, a sensor for detecting the moisture content of the biomass is provided,
A coal / biomass co-firing system comprising a controller configured to select a corresponding fuel supply nozzle from a plurality of fuel supply nozzles in a height direction based on a detection value of the sensor . When the moisture content of the biomass is high, the controller supplies the pulverized biomass to a fuel supply nozzle on the lower side of the boiler furnace, and pulverizes the coal to another fuel supply nozzle located on the upper side of the fuel supply nozzle. Supply things,
On the other hand, when the moisture content of the biomass is low, the biomass pulverized product is supplied to the upper fuel supply nozzle of the boiler furnace, and the coal pulverized product is supplied to another fuel supply nozzle located on the lower side of the fuel supply nozzle. 2. The coal / biomass mixed combustion system according to claim 1, wherein the system is a controller for supplying and burning the pulverized biomass and the pulverized coal to a separate fuel supply nozzle in the boiler furnace . A plurality of vertical pulverizers (hereinafter referred to as pulverizers) that press and pulverize solid fuel placed on a pulverization table that is rotationally driven by a motor by means of a roller that operates in conjunction with the rotation of the table; Prepare a boiler furnace with multiple stages of fuel supply nozzles in the direction,
The pulverized fuel obtained from each of the pulverizers is a coal / biomass mixed combustion method in which the fuel is supplied to the corresponding fuel supply nozzle of each stage,
In addition to a pulverizer (hereinafter referred to as a second pulverizer) that performs dedicated coal pulverization or mixed pulverization of coal and biomass, a pulverizer that pulverizes biomass alone (hereinafter referred to as a first pulverizer) is provided.
On the supply upstream side for supplying biomass to the first crusher, a sensor for detecting the moisture content of the biomass is provided,
Based on the detection value of the sensor, a corresponding stage fuel supply nozzle is selected from a plurality of stages of fuel supply nozzles in the height direction, and the biomass pulverized product and the coal pulverized product are separated into fuel in separate stages in the boiler furnace. coal, biomass co-combustion way to, characterized in that feeding and burning a supply nozzle. When the moisture content of the biomass is high, the pulverized biomass is supplied to the fuel supply nozzle on the lower side of the boiler furnace, and the pulverized coal is supplied to another fuel supply nozzle located on the upper side of the fuel supply nozzle. ,
On the other hand, when the moisture content of the biomass is low, the biomass pulverized product is supplied to the upper fuel supply nozzle of the boiler furnace, and the coal pulverized product is supplied to another fuel supply nozzle located on the lower side of the fuel supply nozzle. 4. The coal / biomass mixed combustion method according to claim 3 , wherein the biomass pulverized product and the coal pulverized product are supplied to a separate fuel supply nozzle and burned in the boiler furnace .

Images