JP4801552B2 - Biomass crusher and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biomass crushing apparatus and its control method, capable of keeping its crushing performance even for biomass with large variation in moisture content, achieving stable operation of a crusher and reducing crushing power. <P>SOLUTION: This biomass crushing apparatus provided with a crushing table 34 where biomass is placed, a roller 35 for crushing the biomass by applying a pressing force to the biomass, and an air supply means for supplying air to the crusher 3, is constituted to include a moisture content detection means for detecting the moisture content of the biomass in the crusher 3, and a moisture content regulation means 15 regulating the detected moisture content to be less than a fiber saturated point and more than a particle temperature rising point. In the concrete, the moisture content of the biomass at the outlet of the crusher is detected by a humidity sensor 10, the heating temperature of the supply air is controlled by controlling the air supply means based on the moisture content, to keep the moisture content in the crusher within the above ranges. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a biomass pulverization apparatus and its control method for pulverizing biomass such as wood chips using a vertical pulverizer, and in particular, the pulverization performance can be maintained even when the moisture content of the biomass fluctuates, and the stability of the pulverizer The present invention relates to a biomass pulverization apparatus capable of achieving operation and reducing pulverization power and a control method thereof.

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.
In addition, the use of biomass is promoted because it can be used for CO ₂ emission trading because of the suppression of CO ₂ generation.

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

  As the former mixing and pulverizing method, techniques shown in Patent Documents 1 and 2 are known. Patent Document 1 discloses a pulverizer that pulverizes coal, a coal supply device that includes a coal supply pipe and a coal bunker that supplies coal to the pulverizer, and a biomass supply that quantitatively supplies biomass to the coal supply pipe. And a configuration in which the operation state of the pulverizer is stabilized by adjusting the supply of biomass from the biomass quantitative supply means. In Patent Document 2, wood chips crushed to a predetermined size in advance are mixed with coal, and then the mixture is pulverized by a pulverizer. An operating method for increasing the load and reducing the roller load is disclosed.

  As the latter single pulverization method, a technique disclosed in Patent Document 3 is known. As shown in FIG. 7, the wood material is supplied from the supply pipe 310 onto the pulverizing table 312 and pulverized by the pulverizing roller 314. The pulverized material is discharged to the outer periphery of the pulverizing table 312 and ejected from below the outer periphery of the table 312. In this method, the material to be crushed is classified into fine powder and coarse powder by being conveyed upward by the air flow 316. This method makes it possible to effectively use a conventional coal pulverizer as a wood raw material pulverizer by setting an optimal relationship between the air flow rate and the pulverization table diameter.

A general coal / biomass co-firing system employing such a single pulverization method is shown in FIG. Biomass such as wood chips is sized to a certain extent and stored as biomass chips in the biomass storage facility 101 and then supplied to the biomass hopper 102. The biomass chips are supplied from the biomass hopper 102 to the pulverizer 103 and pulverized by the pulverization table 104 and the pulverization roller 105.
In addition to the biomass pulverizer 103, coal pulverizers 111a and 111b including coal hoppers 110a and 110b are provided. The pulverized biomass powder and coal powder are supplied to the boiler furnace 112, and the biomass powder and the coal powder are mixed and burned in the boiler furnace 112.

  The furnace body 113 of the boiler furnace 112 is provided with a fuel supply nozzle and a burner that cooperates therewith. The combustion exhaust gas generated by the combustion heats the heat transfer tube 114 disposed in the furnace and is sent to the flue. An air heater (AH) 115 is arranged in the middle of the flue provided at the furnace outlet of the furnace body 113, and the combustion exhaust gas passing through the air heater 115 is released into the atmosphere through an exhaust gas treatment facility such as an ash collector. Is done. High-temperature air 117 generated by heating the outside air 116 by the air heater 115 is supplied to the coal pulverizers 3b and 3c and used for drying the coal. A part of the combustion exhaust gas is supplied to the biomass crusher 103 by an attracting fan and used for drying the biomass.

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

However, in the biomass crushing apparatus as described above, unlike the case of crushing coal, the biomass has a large fluctuation in moisture content, and the processing capacity of the crusher greatly fluctuates or the crushing power greatly increases. There was a problem of disturbing stable operation. In particular, in the single pulverization method, since only biomass is pulverized, the water fluctuation greatly affects the operation of the pulverizer.
Therefore, in view of the problems of the prior art described above, the present invention can maintain the pulverization performance even for biomass having a large fluctuation in water content, achieve stable operation of the pulverizer, and reduce the pulverization power. An object of the present invention is to provide a biomass crushing apparatus and a control method thereof.

In general, when biomass is pulverized in a high moisture state, the pulverized powder is re-agglomerated inside the pulverizer, making it difficult to discharge to the outside of the pulverizer system, and it becomes difficult to pulverize with high material elasticity. The power to grind to the particle size increases and the processing capacity decreases.
FIG. 5 shows the relationship between the moisture content of wood, the processing capacity of the pulverizer, and the power ratio. Here, the power ratio means the pulverization power unit (kWh / t).
The (I) toughness reduction region in the figure is a dry state in which moisture exists only inside the wood, has low fracture stress, and is easily pulverized. The water content is about 20% or less. In this region, as the water content decreases, the treatment capacity increases and the power ratio decreases. (II) The dead zone is a state where surface moisture and free water exist in addition to internal moisture. The moisture content is in the range of about 20-40%, and the change in the treatment capacity and power ratio is small. (III) In the agglomeration zone, in addition to the above-described water form, water permeation into the adhering water and fiber gaps is observed. These waters cause the pulverized powder to aggregate and increase the elasticity of the material. The water content is about 40% or more, the treatment capacity is reduced, and the power ratio is increased. Moreover, it will be in the state where a grinding | pulverization becomes difficult by the elasticity increase of biomass particles.
From this graph, it can be seen that the toughness reduction region, that is, the fiber saturation point and below is a moisture content suitable for pulverization.

FIG. 6 is a characteristic diagram showing the drying characteristics of wood. In the figure, the broken line indicates the case where the wood is naturally dried, and the solid line indicates the case where the wood is forcibly dried by hot air or the like. A one-dot chain line represents a dangerous temperature range with respect to the drying time. The dangerous temperature range is the temperature of wood when it spontaneously ignites. Section i is a free water drying area, section ii is a weakly bound water drying area, and section iii is a strongly bound water drying area.
When the biomass is forcibly dried, the moisture inside the biomass first evaporates, and the biomass particles themselves heat up after most of the moisture evaporates. Excessive drying beyond the particle temperature rise point can cause spontaneous ignition and is dangerous. Region A is a safe drying region that does not involve particle temperature rise, and region B is a dangerous drying region that involves particle temperature rise.
Therefore, it can be seen that it is important from the viewpoint of safety and efficiency to maintain the water content above the particle temperature rising point.

Therefore, in view of the above characteristics of biomass,
The present invention includes a grinding table on which biomass to be supplied to a vertical crusher is placed, a roller that operates in conjunction with the rotationally driven table and crushes the biomass by applying a pressing force, and the crusher In the biomass crushing apparatus provided with air supply means for supplying air to
Water content detection means for detecting the moisture content of biomass inside the pulverizer, and water content adjustment control means for adjusting the detected water content to be below the fiber saturation point and above the particle temperature rise point It is characterized by that.

This is because the moisture content of the biomass inside the pulverizer is below the fiber saturation point, that is, by performing pulverization in the (I) toughness reduction region shown in FIG. Can do. Therefore, the pulverizer can be efficiently operated at a low running cost.
In addition, by setting the moisture content of the biomass inside the pulverizer to be equal to or higher than the particle temperature rising point, the natural oxidation of the biomass can be suppressed and the risk of spontaneous ignition can be avoided.
Thus, according to the present invention, by adjusting the moisture content of biomass in the pulverizer to an appropriate value (region C in FIG. 6), stable operation of the pulverizer can be achieved and pulverization power can be reduced. .

Further, the moisture content adjustment control means controls the air supply means based on the moisture content detected by the moisture content detection means to adjust the heating temperature of the supply air.
Thus, by adjusting the heating temperature of the supply air, it becomes possible to adjust the moisture content of the biomass in the pulverizer to an appropriate value.

Further, at least a part of the air supplied by the air supply means is combustion exhaust gas obtained by burning fuel containing biomass powder obtained by the pulverizer, and the air supply means is heated to supply heated air. An air supply line, a room temperature air supply line that supplies room temperature air, and a damper that is installed on each line and adjusts the gas supply amount.
The moisture content adjustment control means adjusts the heating temperature of the supply air by opening and closing the damper.
As described above, heated air is introduced into the biomass pulverizer in order to maintain the pulverization property by drying the biomass. However, the biomass particles themselves have remarkable natural oxidation temperature rise characteristics in a high-temperature atmosphere, which may cause a fire in the pulverizer. There is concern about becoming. Therefore, natural oxidation of biomass can be suppressed by mixing low oxygen gas such as combustion exhaust gas into heated air.

Furthermore, a predrying device that is installed on the front side of the pulverizer and dries the biomass, and a second moisture content detection unit that is installed between the predrying device and the pulverizer and detects the moisture content of the biomass, Switching control means for switching the air supply means based on the detected moisture content,
The switching control means is characterized in that when the moisture content detected by the second moisture content detecting means is equal to or lower than a reference value, the heating of the supply air is stopped and the operation is switched to the normal temperature operation.
According to the present invention, it is possible to reduce the moisture content of biomass inside the pulverizer by providing a pre-drying device, thereby making it possible to dry the biomass particles by the heat of pulverization, thereby eliminating the need for introducing heated air. be able to.

Further, a biomass pulverizer for supplying biomass to a vertical pulverizer and pulverizing the biomass placed on a pulverization table that is driven to rotate in the pulverizer by a roller that operates in conjunction with the rotation of the table. In the control method of
The moisture content of biomass in the pulverizer is detected and adjusted so that the moisture content is not more than the fiber saturation point and not less than the particle temperature rising point.
Furthermore, the moisture content of the biomass inside the pulverizer is adjusted by the heating temperature of the air supplied to the pulverizer.

As described above, according to the present invention, by adjusting the moisture content of biomass in the pulverizer to an appropriate value, it is possible to increase the processing capacity, achieve stable operation of the pulverizer, and reduce the pulverization power.
In addition, by adjusting the heating temperature of the supply air, it becomes possible to adjust the moisture content of biomass in the pulverizer to an appropriate value.
Furthermore, natural oxidation of biomass can be suppressed by using at least a part of the supply air as combustion exhaust gas.

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.
FIG. 1 is an overall configuration diagram of a system according to Embodiment 1 of the present invention, FIG. 2 is a side sectional view showing a schematic configuration of a vertical crusher, and FIG. 3 is a correlation between moisture content of biomass particles at the crusher outlet and inside. FIG. 4 is an overall configuration diagram of a system according to Embodiment 2 of the present invention.

  As shown in FIG. 1, the system according to the present embodiment is supplied with a biomass storage facility 1 that stores primary biomass (coarse) and dried biomass 51 to a predetermined particle size or less as needed, and biomass 51. The biomass pulverizer 3 provided with the hopper 2, the coal pulverizers 4 a and 4 b provided with the hoppers 5 a and 5 b for receiving coal, the biomass powder obtained by the biomass pulverizer 3 and the coal pulverizers 4 a and 4 b A boiler furnace 6 to which the coal powder obtained in this way is supplied.

A specific configuration of the biomass crusher 3 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 biomass 51 can form a deposited layer having a predetermined thickness on the crushing table 32. Furthermore, pressure is applied to the biomass while rotating in conjunction with the rotation of the crushing table 32 by applying a load with hydraulic pressure or a spring or the like on the upper surface of the outer peripheral portion of the crushing table 32 at equal intervals in the circumferential direction. A crushing roller 34 is provided for crushing by acting.

The biomass supplied from the hopper 2 through the supply pipe 21 to the center of the crushing table 32 moves on the crushing table 32 in the outer peripheral direction by centrifugal force, and is held between the crushing race 37 and the crushing roller 34. It is rarely crushed. The biomass supply pipe 21 is provided with a supply amount detection unit 22 for detecting the supply amount, and the supply amount is monitored.
Air is supplied from the lower part of the housing 31 through an air supply line 54, and a blown airflow is formed in the housing. The pulverized biomass powder is conveyed to the upper part of the housing by this blow-up airflow. 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. When heated air is supplied from the air supply line 54, it is also used for drying biomass.

As shown in FIG. 1, the furnace main body 61 of the boiler furnace 6 includes fuel supply nozzles 62 a to 62 c provided in a plurality of stages in the height direction, air nozzles, and burners (not shown) that cooperate with these nozzles. Is arranged. A heat transfer tube group 63 corresponding to a heater, an evaporator, a economizer, and the like is installed in the furnace.
The biomass powder and the coal powder supplied into the furnace from the fuel supply nozzles 62a to 62c are mixed and burned in the furnace. The combustion exhaust gas generated by the combustion heats the heat transfer tube group 63 and is sent to the flue. An air heater 7 is arranged in the middle of the flue provided at the furnace outlet of the furnace body 61, and the flue gas in the flue is drawn by an induction fan and released from the chimney through an air heater and an ash collector. The The high temperature air obtained by heating the outside air 55 by the air heater 7 is supplied to the coal pulverizers 4 b and 4 c through the air supply line 57.

Further, the combustion exhaust gas 56 partially branched from the outlet of the boiler furnace 6 is supplied to the biomass pulverizer 3 through the air supply lines 53 to 54 by the induction fan 8 by adding outside air 58 as necessary.
The air supply line 53 for guiding the combustion exhaust gas is branched into a cold air supply line 53a and a warm air supply line 53b, and the air heater 13 is provided on the warm air supply line 53b. Dampers 12 and 14 for adjusting the air supply amount are provided on the air supply lines 53a and 53b, respectively, so that the air passing through the dampers 12 and 14 is introduced into the pulverizer 3 via the air supply line 54. It has become.

  Furthermore, the biomass pulverizer 3 of this embodiment includes a moisture content detecting means for detecting the moisture content of the biomass in the pulverizer, and a moisture content adjustment control means 15 for adjusting the moisture content, and thereby the biomass inside the pulverizer. The water content is controlled to be below the fiber saturation point and above the particle temperature rising point. By setting the moisture content to be equal to or lower than the fiber saturation point, it is possible to improve the biomass grindability, to increase the processing capacity and to lower the power ratio. On the other hand, the natural oxidation of biomass can be suppressed and the risk of spontaneous ignition can be avoided by setting it to the particle temperature rising point or higher. Preferably, the moisture content of the biomass in the pulverizer is 3 to 23%.

  As an example of the moisture content detecting means, there is a humidity sensor 10 provided on a biomass powder supply line 52 as shown in FIG. The moisture sensor 10 detects the moisture content of biomass at the pulverizer outlet, and estimates the moisture content inside the pulverizer from the detected moisture content. This estimation is performed by the control device 15. In the control device 15, the correlation between the moisture content of the biomass at the pulverizer outlet and the moisture content of the biomass inside the pulverizer is inputted in advance, and the moisture content inside the pulverizer is determined from the moisture content at the exit of the pulverizer by the correlation. The rate is derived. A graph of this correlation is shown in FIG. For example, in the case of having the correlation shown in FIG. 3, in order to set the moisture content of biomass in the pulverizer inside to 3 to 23%, the control device 15 so that the moisture content of biomass at the pulverizer outlet becomes 2 to 10%. To adjust the heating temperature of the supply air.

The control means 15 adjusts the heating temperature of the air supplied to the pulverizer 3 based on the moisture content inside the pulverizer. The heating temperature can be adjusted to an appropriate temperature by controlling the opening and closing of the damper 12 and the damper 14 and adjusting the mixing ratio of cold air and hot air.
Moreover, it is preferable to provide the temperature sensor 11 in the biomass powder supply line 52. The temperature sensor 11 is used to keep biomass particles in a constant temperature region at the crusher outlet.

As described above, according to the present embodiment, by maintaining the moisture content of the biomass in the pulverizer at an appropriate value, stable operation of the pulverizer can be achieved and the pulverization power can be reduced.
Further, by adjusting and controlling the temperature of the heated air supplied to the pulverizer based on the moisture content of the biomass, the biomass moisture inside the pulverizer can be maintained at a moisture content suitable for pulverization.
Furthermore, natural oxidation of biomass can be suppressed by using at least a part of the supply air as combustion exhaust gas.

FIG. 4 shows an overall configuration diagram of the biomass co-firing system according to the second embodiment. Hereinafter, detailed description of the same configuration as that of the first embodiment will be omitted.
As shown in the figure, the system according to the second embodiment includes a biomass storage facility 1, a biomass crusher 3 provided with a hopper 2, coal pulverizers 4a and 4b provided with hoppers 5a and 5b, and a boiler furnace. 6.
The pulverized fuel obtained by the biomass pulverizer 3 and the coal pulverizers 4a and 4b is supplied from the fuel supply nozzles 62a to 62c into the boiler furnace 6 and mixed and burned.

In the present embodiment, a preliminary dryer 17 is provided on the upstream side of the biomass crusher 3. A humidity sensor 18 is provided between the preliminary dryer 17 and the pulverizer 3.
Based on the moisture content of the biomass detected by the humidity sensor 18, the controller 19 controls the temperature of the preliminary dryer 17, the processing time, and the like. Furthermore, when the detected moisture content is below the reference value, the controller 19 stops heating the air supplied to the pulverizer 3 and switches to normal temperature operation. In FIG. 4, the air supply lines 53 to 54 shown in FIG. 1 are omitted.
According to the second embodiment, the biomass is conditioned (dried) in advance by the preliminary dryer 17, so that the finish drying can be performed only by the heat of pulverization by the pulverizer. As a result, the facility and control for supplying combustion exhaust gas as described in Embodiment 1 can be eliminated. In addition, since it is not necessary to supply heated air, spontaneous ignition in the pulverizer can be prevented.

  According to the coal / biomass pulverization apparatus and the control method thereof of the present invention, even if the processing target is biomass with a large amount of moisture fluctuation, the pulverization performance can be maintained and stable operation of the pulverizer can be achieved, and the pulverization power can be reduced. It is also useful when applied to existing equipment.

1 is an overall configuration diagram of a system according to Embodiment 1 of the present invention. It is a sectional side view which shows schematic structure of a vertical crusher. It is a graph which shows the correlation of the moisture content of the biomass in a crusher exit and an inside. It is a whole block diagram of the system which concerns on Example 2 of this invention. It is a graph which shows the relationship between the process capacity ratio with respect to a wood moisture content, and a power ratio. It is a characteristic view showing the drying characteristic of wood. 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 mixed combustion system by the conventional independent grinding | pulverization system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Biomass storage equipment 2 Hopper 3 Biomass grinder 4a, 4b Coal grinder 6 Boiler furnace 10 Temperature sensor 11 Humidity sensor 12, 14 Damper 13 Air heater 15 Moisture content adjustment control device 17 Preliminary dryer 18 Humidity sensor 19 Control device 53 54 Air supply line 53a Cold air supply line 53b Hot air supply line

Claims (6)

A crushing table on which biomass to be supplied to the vertical crusher is placed, a roller that operates in conjunction with the rotationally driven table and applies a pressing force to the biomass, and supplies air to the crusher In the biomass pulverizing apparatus provided with the air supply means for
Water content detection means for detecting the moisture content of biomass inside the pulverizer, and water content adjustment control means for adjusting the detected water content to be below the fiber saturation point and above the particle temperature rise point A biomass crusher characterized by that.   The said moisture content adjustment control means adjusts the heating temperature of supply air by controlling the said air supply means based on the moisture content detected by the said moisture content detection means. Biomass crusher. At least a part of the air supplied by the air supply means is combustion exhaust gas obtained by burning fuel containing biomass powder obtained by the pulverizer, and the air supply means supplies heated air for supplying heated air. A line, a room temperature air supply line that supplies room temperature air, and a damper that is installed on each line and adjusts the gas supply amount,
The biomass pulverization apparatus according to claim 1 or 2, wherein the moisture content adjustment control means adjusts the heating temperature of the supply air by opening and closing the damper. A pre-drying device for drying biomass installed on the front side of the pulverizer; a second moisture content detecting means for detecting the moisture content of biomass installed between the pre-drying device and the pulverizer; Switching control means for switching the air supply means based on the moisture content,
3. The switching control means, when the moisture content detected by the second moisture content detection means is below a reference value, stops heating the supplied air and switches to normal temperature operation. Or the biomass grinding | pulverization apparatus of 3 description. Control of a biomass crusher that supplies biomass to a vertical crusher and crushes biomass placed on a crushing table that is driven to rotate in the crusher by a roller that operates in conjunction with rotation of the table. In the method
A control method for a biomass pulverizer, wherein the moisture content of biomass in the pulverizer is detected and adjusted so that the moisture content is below the fiber saturation point and above the particle temperature rising point.   6. The method for controlling a biomass pulverizer according to claim 5, wherein the moisture content of the biomass inside the pulverizer is adjusted by a heating temperature of air supplied to the pulverizer.

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