JP2015114046A - Biomass fuel pretreatment dryer and combustion plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretreatment dryer capable of drying a vegetable biomass fuel relatively in a short time while preventing carbonization.SOLUTION: A wood chip dryer includes: a cylindrical dry room 1; an agitation device 7 arranged coaxially with the dry room 1; a wood chip inlet 5 arranged on one end of the dry room 1; a wood chip discharge port 6 arranged on the other end of the dry room 1; first to third slits 13, 14, and 15 arranged on the other end of the dry room 1 and serving as air intake ports; and an exhaust port 4 arranged on one end of the dry room 1. Wood chips put into the dry room 1 from the wood chip inlet 5 move from one end to the other end of the dry room 1 by agitating blades 9 of the rotating agitation device 7. Hot air fed from the first to third slits 13, 14, and 15 forms a swirl flow and flows in the dry room 1 from the other end to one end.

Description

  The present invention relates to a pretreatment dryer used for pretreatment of biomass fuel such as wood chips and a combustion plant using the same.

  Recently, plant biomass fuel has attracted attention as an alternative fuel in order to cope with rising prices of fossil fuels and environmental impacts. Plant-based biomass fuels include wood chips made by crushing thinned wood and waste wood. Wood chips are obtained from forestry waste such as wood scraps, thinned wood and bark, and construction waste such as construction waste, so they contribute to the recycling of resources and are expected to spread. Yes.

  When the wood chip is made of raw material, the moisture content is relatively high at 50 wt% or more, and therefore it is necessary to perform a drying treatment before using it as a fuel to reduce the moisture content to about 10 wt%. Conventionally, rotary kilns are widely used as dryers for drying wood chips. This type of rotary kiln includes a rotary furnace in which wood chips are introduced from one end, and the introduced wood chips are agitated by rotating operation to the other end, and a burner that operates with fossil fuel and emits flame into the rotary furnace. (For example, refer to Patent Document 1).

JP 2002-088373 A

  However, in the rotary kiln, when the wood chips fall from the inner wall surface of the rotary furnace as the rotary furnace rotates, the wood chips come into contact with the high temperature air in the rotary furnace and the drying proceeds. The amount of contact with is relatively small. Therefore, in order to dry the wood chip to the extent that it can be used as fuel, a relatively long drying time is required, and there is a problem that the operation time of the burner becomes long and the fuel cost increases. Further, when the heating value of the burner is increased in order to shorten the drying time, there is a problem that carbonization proceeds from the surface of the wood chip. Furthermore, performing a drying process for using wood chips as a fuel using fossil fuels has problems in terms of resource recycling and causes a cost increase.

  Therefore, an object of the present invention is to provide a pretreatment dryer capable of drying biomass fuel in a relatively short time while preventing carbonization without using fossil fuel, and a combustion plant using the same.

In order to solve the above problems, the pretreatment dryer of the present invention is a pretreatment dryer for performing pretreatment drying of a vegetable biomass fuel,
A cylindrical drying chamber;
An inlet provided on one end side in the axial direction of the drying chamber, and into which an object to be processed which is the biomass fuel is charged,
A discharge port that is provided on the other end side in the axial direction of the drying chamber, and discharges the workpiece;
An air supply port that is provided on the other end side in the axial direction of the drying chamber, and supplies drying air in a tangential direction of the drying chamber;
An exhaust port that is provided on one end side in the axial direction of the drying chamber and exhausts air in a tangential direction from the drying chamber;
A rotating shaft that is arranged coaxially with the central axis of the drying chamber and is driven to rotate;
A stirring blade spirally disposed on the outer peripheral surface of the rotating shaft,
The moving direction of the air in the drying chamber and the moving direction of the workpiece are opposite to each other in the axial direction of the drying chamber,
The drying air is air heated by the combustion heat of the object to be processed.

  According to the said structure, the vegetable biomass fuel which is a to-be-processed object is thrown into the cylindrical-shaped drying chamber from the inlet provided in the axial direction one end side of the drying chamber. A rotating shaft arranged coaxially with the central axis is rotationally driven, and the workpiece in the drying chamber is stirred from one end of the drying chamber by a stirring blade spirally arranged on the outer peripheral surface of the rotating shaft. Move towards the other end. The object to be processed that has reached the other end side in the axial direction of the drying chamber is discharged from the discharge port. On the other hand, drying air is supplied in a tangential direction of the drying chamber to an air supply port provided on the other end side in the axial direction of the drying chamber. The drying air is preferably at a temperature suitable for drying the object to be processed, for example, a temperature of 150 ° C. or higher and 350 ° C. or lower. The drying air supplied into the drying chamber flows in a swirling manner in the drying chamber and is discharged in a tangential direction of the drying chamber from an exhaust port provided on one end side in the axial direction of the drying chamber. As described above, the air flows in a swirling manner in the drying chamber, and the moving direction of the air in the drying chamber and the moving direction of the object to be processed are opposite to each other in the axial direction. More than the rotary kiln in which the workpiece falls in the rotary furnace. Accordingly, the object to be processed can be dried more efficiently than before, so that the time required for drying can be shortened. As a result, the fuel cost for heating the drying air can be reduced. Further, since the object to be processed is dried by bringing the object to be processed and air into contact with each other more than before, the temperature of the air can be made lower than before. Therefore, drying can be performed while preventing carbonization of the workpiece. In addition, since air heated by the combustion heat of the object to be processed is used as drying air, the heat of combustion when the object to be processed is used as fuel can be used effectively without using fossil fuel. Recycling can be used. Moreover, the cost increase by using a fossil fuel can be prevented. Here, examples of the plant biomass fuel that is the object to be treated include wood chips and wood chips, but the plant biomass fuel is not limited to these as long as it is a plant material that can be used for the fuel. Other plant biomass fuels include, for example, mowing grass, rice husk, straw, bacus, coconut bunches, soybean husk, soybean pomace, buckwheat husk, cotton husk, sunflower seed husk, jatroba (south ocean) Various plant biomass such as oil paulownia husk and roasted coffee crumbs (chaff) can be used. In addition, the air heated by the combustion heat of the object to be processed is the combustion gas generated by burning the plant biomass fuel as the object to be processed and the air heated by heat exchange with the combustion gas. Both are applicable.

  In the biomass fuel pretreatment dryer according to an embodiment, at least a part of the stirring blade is provided with a forward pitch for propelling the workpiece from one end side to the other end side of the rotating shaft.

  According to the above embodiment, the object to be processed is propelled from one end side to the other end side of the rotating shaft by the stirring blades provided with the forward pitch when the rotating shaft is rotationally driven. Despite flowing in the opposite direction in the axial direction, the workpiece can be moved effectively. Here, the pitch refers to a twist angle with respect to the rotation axis. Specifically, this is an angle at which the main surface of the stirring blade is inclined with respect to a surface perpendicular to the rotation axis, and an angle that gives a propulsive force in a direction parallel to the rotation axis.

  In the biomass fuel pretreatment dryer according to one embodiment, a part of the stirring blade is provided with a reverse pitch for propelling the workpiece from the other end side to the one end side of the rotating shaft.

  According to the embodiment described above, the forward pitch is provided in a part of the stirring blades, and the reverse pitch is provided in the other part, whereby the object to be processed in the drying chamber is connected to one end of the rotating shaft. Both the force propelled from the side to the other end side and the force propelled from the other end side to the one end side of the rotating shaft are received. Thereby, since mixing of a to-be-processed object is accelerated | stimulated, the to-be-processed object in a drying chamber dries evenly. Here, the stirring blade provided with the reverse pitch is preferably located in the vicinity of the center in the axial direction of the rotating shaft. The vicinity of the axial center of the rotating shaft can be defined as a range corresponding to one third of the entire length of the rotating shaft with the axial center of the rotating shaft as the center. Moreover, the number of the stirring blades provided with the reverse pitch is one or more and less than half the number of all the stirring blades.

  In the biomass fuel pretreatment dryer according to an embodiment, the stirring blade is formed in a scoop shape.

  According to the embodiment, the object to be processed in the drying chamber can be effectively scooped and stirred and moved by the scoop-like stirring blade. Here, the scoop shape refers to a shape in which the portions on both sides in the width direction of the blade body protrude toward the other end side of the rotating shaft from the center portion.

  In the biomass fuel pretreatment dryer according to an embodiment, a plurality of the air supply ports are provided side by side in the axial direction of the drying chamber.

  According to the above-described embodiment, a plurality of air supply ports that supply air in the tangential direction of the drying chamber are provided side by side in the axial direction of the drying chamber, so that a swirling flow of air is effectively formed in the drying chamber. The

  In the biomass fuel pretreatment dryer according to an embodiment, the air supply port includes a flow rate adjusting unit that adjusts a flow rate of the drying air supplied to the drying chamber.

  According to the above embodiment, by adjusting the flow rate of the drying air supplied to the drying chamber to a flow rate corresponding to the moisture content or amount of the object to be processed supplied to the drying chamber by the flow rate adjusting means, The object to be processed can be stably dried to a predetermined moisture content. Here, as the flow rate adjusting means, one including a door driven so as to open and close the air supply port can be adopted. Further, a flow rate adjusting valve interposed in an air supply pipe connected to the air supply port can be employed.

  In the biomass fuel pretreatment dryer according to one embodiment, the swirling direction of the swirling flow of air formed in the drying chamber and the rotating direction of the rotating shaft are the same.

  According to the above embodiment, the swirling direction of the swirling flow of air formed in the drying chamber and the rotating direction of the rotating shaft whose center axis coincides with the drying chamber are the same as each other. Further, the resistance force applied to the stirring blades having a normal pitch from the swirling flow of air can be reduced. Moreover, since the air swirling in the drive direction of the rotating shaft is caused to flow, the resistance force that the rotating shaft receives from the air can be reduced. Therefore, it is possible to reduce the load acting on the rotating shaft drive device.

  In the biomass fuel pretreatment dryer according to one embodiment, the object to be treated has a moisture content of 30 wt% or more and 70 wt% or less.

According to the said embodiment, the to-be-processed object which has a moisture content of 30 wt% or more and 70 wt% or less can be dried effectively, and a moisture content can be 10 wt% or less. Examples of such objects to be processed include wood chips and wood chips manufactured from raw wood. Here, the moisture content is a percentage of a value obtained by dividing the mass of all water contained in the material by the mass before drying of the material, and is a so-called wet-based moisture content. That is, the moisture content u is a value obtained by the following equation (1).
u = ((W1-W2) / W1) × 100 (1)
Here, u is the moisture content (wt%), W1 is the mass (g) of the material before drying, and W2 is the mass (g) of the material after drying. In addition, wt% is a mass percent.

  In the biomass fuel pretreatment dryer according to one embodiment, the object to be treated is a wood chip formed by crushing a raw tree.

  According to the said embodiment, although the wood chip formed by crushing a raw tree has a moisture content of 30 wt% or more and 70 wt% or less in many cases, it can be effectively hydrated by using the pretreatment dryer of the present invention. The rate can be reduced, and the amount of heat when burned can be effectively improved. Therefore, the wood chip | tip of the raw tree which was difficult to use as a fuel conventionally can be used as a fuel, and effective utilization of resources can be aimed at.

  In one embodiment of the pretreatment dryer for biomass fuel, the object to be treated is a used fungal bed made of wood chips.

  According to the above embodiment, the moisture content is effectively reduced by drying the used waste microbial bed, which often has a moisture content of 30 wt% to 70 wt%, using the pretreatment dryer of the present invention. can do. Therefore, the waste microbial bed, which has a high water content and has been difficult to reuse, can be used as fuel. Here, the waste microbial bed dried by the pretreatment dryer may be burned as fuel as it is, or may be formed into pellets and burned as fuel.

The combustion plant of the present invention includes a biomass fuel pretreatment dryer,
A combustion apparatus that uses vegetable biomass fuel dried by the pretreatment dryer as fuel,
Combustion gas generated by burning vegetable biomass fuel in the combustion apparatus is supplied to the pretreatment dryer as drying air.

  According to the embodiment, the pretreatment drying of the vegetable biomass fuel is performed by the pretreatment dryer, and the plant biomass fuel subjected to the pretreatment drying is burned by the combustion device. Combustion gas generated by burning biomass fuel in this combustion apparatus is supplied to the pretreatment dryer as drying air. In this way, pretreatment drying of biomass fuel is carried out by reusing the heat of the combustion device using biomass fuel, so compared with the case where pretreatment drying is carried out using fossil fuel, resource recycling is utilized. It can be done effectively.

It is a side view which shows the pre-processing dryer of embodiment of this invention. It is a longitudinal cross-sectional view which shows a pre-processing dryer. It is a cross-sectional view at the exhaust port of the pretreatment dryer. It is a cross-sectional view at the air supply port of the pretreatment dryer. It is a top view which shows the air supply apparatus of a pre-processing dryer. It is a plane sectional view showing an air supply device of a pretreatment dryer. It is a front view which shows a hexagonal stirring blade. It is a side view which shows a hexagonal stirring blade. It is a front view which shows a scoop-like stirring blade. It is a side view which shows a scoop-like stirring blade. It is a mimetic diagram showing a combustion plant of an embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 is a side view showing a wood chip dryer as a biomass fuel pretreatment dryer according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing the wood chip dryer. FIG. 3 is a cross-sectional view at the exhaust port of the wood chip dryer, and FIG. 4 is a cross-sectional view at the air supply port of the wood chip dryer.

  This wood chip dryer is a dryer for drying wood chips as vegetable biomass fuel as a pretreatment before using them as fuel. This wood chip dryer includes a cylindrical casing 2 having a cylindrical drying chamber 1 therein, a wood chip inlet 5 provided on one end side in the axial direction of the drying chamber 1, and other axial directions of the drying chamber 1. It has a wood chip discharge port 6 provided on the end side. The wood chip inlet 5 is formed of a cylindrical member extending in the radial direction of the drying chamber 1 and is provided at the top of the cylindrical casing 2. The wood chip inlet 5 is connected to a cutting device of a fixed quantity feeder that stores the wood chips and supplies them to the wood chip dryer via a rotary valve. The wood chip discharge port 6 is formed of a rectangular cross-section tube extending in the tangential direction of the inner wall surface of the drying chamber 1 and is provided at the bottom of the cylindrical casing 2.

  On the other end side in the axial direction of the drying chamber 1, a first slit 13 as an air supply port for supplying hot air as drying air in a tangential direction of the drying chamber 1, a second slit 14, and a third slit 15 is provided. The first to third slits 13, 14, 15 have a flat rectangular shape having a dimension in the axial direction larger than a dimension in the circumferential direction of the drying chamber 1 in a longitudinal sectional view of the drying chamber 1. Hot air is supplied to the first to third slits 13, 14, and 15 by the air supply device 3, and the hot air is blown out tangentially to the drying chamber 1 as indicated by an arrow W <b> 1 in FIG. 4. . Each of the first to third slits 13, 14, 15 is provided with an opening / closing door (not shown) that is driven to open and close. The open / close door is a sliding shutter that adjusts the flow rate of hot air by adjusting the opening of the first to third slits 13, 14, and 15 according to the amount of wood chips thrown into the drying chamber 1 and the moisture content. To do. On the one end side in the axial direction of the drying chamber 1, an exhaust port 4 for exhausting air from the drying chamber 1 in a tangential direction is provided at a position closer to the end surface of the drying chamber 1 than the wood chip insertion port 5. The exhaust port 4 is formed of a rectangular cross-section tube extending in the tangential direction of the inner wall surface of the drying chamber 1, and is provided on a side portion of the cylindrical casing 2.

  FIG. 5A is a plan view showing the air supply device 3, and FIG. 5B is a plan sectional view showing the air supply device 3. The air supply device 3 includes a distribution box 32 to which hot air generated by a combustion device (not shown) is supplied, and first to third supply air that guides the hot air from the distribution box 32 to the first to third slits 13, 14, and 15, respectively. It has trachea 33, 34, 35. The combustion device that generates hot air supplied to the distribution box 32 operates using the wood chips dried by the wood chip dryer as fuel, and corresponds to, for example, a burner or a boiler. The distribution box 32 is formed in a flat trapezoidal columnar shape whose depth becomes shallower from the other end side to the one end side of the drying chamber 1 in plan view. A supply duct 31 that guides hot air generated by the combustion device is connected to the upper surface of the other end side where the depth of the distribution box 32 is deepest. As shown in FIGS. 4 and 5B, the first to third air supply pipes 33, 34, and 35 are formed in a tapered shape whose cross-sectional area is narrowed from the distribution box 32 side toward the drying chamber 1 side. Specifically, the first to third air supply pipes 33, 34, and 35 are inclined so that the side surfaces approach each other from the distribution box 32 side toward the drying chamber 1 side, while the bottom surface is in the tangential direction of the drying chamber 1. It extends and is inclined so that the top surface approaches the bottom surface. With this air supply device 3, the hot air guided by the supply duct 31 can be uniformly supplied to the first to third slits 13, 14, and 15, and can be uniformly supplied from the first to third slits 13, 14, and 15. Hot air having a proper flow rate and flow rate can be supplied to the drying chamber 1. Further, hot air can be stably blown out from the first to third slits 13, 14, 15 in the tangential direction of the drying chamber 1.

  In the drying chamber 1, a stirring device 7 that is driven to rotate and stirs the wood chip and sends it from one end side to the other end side of the drying chamber 1 is accommodated. The stirring device 7 includes a cylindrical rotary shaft 8 disposed coaxially with the central axis of the drying chamber 1 and a plurality of stirring blades 9 spirally disposed on the outer peripheral surface of the rotary shaft 8. Both ends of the rotary shaft 8 are connected to a support shaft 10, and the support shaft 10 is rotatably supported by a bearing 11. The rotational force of a motor (not shown) serving as a drive device is input to one of the support shafts 11 so that the rotary shaft 8 rotates and the stirring device 7 is rotationally driven.

  FIG. 6A is a front view showing a hexagonal stirring blade 9 attached to the stirring device 7, and FIG. 6B is a side view showing the hexagonal stirring blade 9. The stirring blade 9 includes a hexagonal blade body 91, a column portion 92 that supports the blade body 91, and a spiral cut portion 93 provided at the base end portion of the column portion 92. The stirring blade 9 is fixed to the rotary shaft 8 by screwing a spiral cut portion 93 into a spiral hole provided in the rotary shaft 8 and fastening a double nut screwed into the spiral cut portion 93. The stirring blades 9 attached to the rotary shaft 8 are radially arranged at positions at equal angles of 60 ° when viewed in the axial direction of the rotary shaft 8. The blade body 91 of the stirring blade 9 is formed in a shape in which both sides of the tip edge located on the side far from the spiral cut portion 93 of the column portion 92 are chamfered at the corners. Thereby, the stirring device 7 can be rotated in a state in which the tip edge of the blade body 91 of the stirring blade 9 is close to the cylindrical inner surface of the drying chamber 1.

  The stirring blade 9 of the stirring device 7 is provided with a forward pitch for propelling the wood chip from one end side to the other end side of the rotating shaft 8 when being driven to rotate. Specifically, as shown in FIG. 3, when the rotation direction of the rotation shaft 8 when the rotation shaft 8 is viewed from one end side is counterclockwise as indicated by an arrow R, the stirring blade 9 In the side view, a counterclockwise forward pitch is provided. Here, the stirring blade 9 </ b> A located in the center in the axial direction of the rotating shaft 8 is provided with a clockwise reverse pitch in a side view of the rotating shaft 8. By arranging the reverse pitch stirring blades 9A together with the plurality of forward pitch stirring blades 9, the forward pitch stirring blades 9 move the wood chips from one end side to the other end side when the stirring device 7 is driven to rotate. On the other hand, the stirring blade 9A having the reverse pitch moves the wood chip from the other end side of the rotating shaft 8 to one end side. In this way, most of the wood chips are moved from one end side to the other end side of the rotary shaft 8 and a part of the wood chips are moved in the opposite direction to effectively stir and mix the wood chips. Reduces temperature bias. The reverse pitch stirring blade 9A is not limited to the center in the axial direction of the rotating shaft 8, but can be disposed at a desired position where the wood chip is to be stirred and mixed, but it is disposed in the vicinity of the center in the axial direction of the rotating shaft 8. preferable. Specifically, it can be disposed within a range corresponding to one third of the entire length of the rotary shaft 8 with the center in the axial direction of the rotary shaft 8 as the center. In addition, the number of the stirring blades 9A having the reverse pitch is not limited to one, and a plurality of stirring blades 9A may be provided, but the number is less than half of the total number of all the stirring blades 9 and 9A.

  On the side surface of the cylindrical casing 2 of the wood chip dryer, a plurality of openings for performing maintenance and inspection of the drying chamber 1 and the stirring device 7 are provided, and opening / closing doors 17, 17,. It is attached. The cylindrical casing 2 is supported horizontally by support legs 18 and 18 provided at both end portions in the axial direction.

  The wood chip dryer having the above configuration operates as follows.

  First, a combustion device (not shown) is activated, and hot air is supplied to the distribution box 32 of the air supply device 3 through the supply duct 31 as indicated by an arrow W0. The temperature of the hot air is set according to the moisture content of the wood chip, but is preferably 150 ° C. or higher and 350 ° C. or lower. The hot air supplied to the distribution box 32 passes through the first to third air supply pipes 33, 34, and 35 and enters the drying chamber 1 from the first to third slits 13, 14, and 15 as shown by an arrow W1. Supplied in the direction. The flow velocity of the hot air supplied from the first to third slits 13, 14, 15 to the drying chamber 1 is preferably 20 m / s or more and 30 m / s or less. The flow rate and flow rate of the hot air are adjusted by controlling the opening degree of the opening and closing doors of the first to third slits 13, 14, and 15 according to the amount of wood chips and moisture content introduced into the drying chamber 1. The hot air supplied from the first to third slits 13, 14, 15 into the drying chamber 1 flows along the wall surface of the drying chamber 1 to form a swirling flow as indicated by an arrow WR. Proceed from the end side toward the one end side.

  When hot air is supplied and the inside of the drying chamber 1 is heated, the introduction of the wood chips into the drying chamber 1 is started. That is, the cutting device of the quantitative feeder is activated and the rotary valve is opened, and the wood chip is inserted into the wood chip insertion port 5 as indicated by the arrow P1. At the same time, the motor is started, a rotational force is input to the support shaft 10, and the stirring device 7 is rotationally driven. The wood chip introduced into the drying chamber 1 from the wood chip inlet 5 is sent from one end side of the drying chamber 1 to the other end side by the stirring blade 9 of the stirring device 7. The driving speed of the stirring device 7 is preferably set so that the circumferential speed of the tip portion of the stirring blade 9 is 0.5 m / s or more and 1.5 m / s or less.

  While the wood chip moves from the one end side to the other end side in the drying chamber 1, the wood chip comes into contact with the swirling flow of hot air flowing from the other end side toward the one end side. The wooden chip that has reached the other end of the drying chamber 1 is discharged in the tangential direction of the drying chamber 1 from the wooden chip discharge port 6 as indicated by an arrow P2. The hot air that has reached one end of the drying chamber 1 is discharged from the exhaust port 4 in the tangential direction of the drying chamber 1 as indicated by an arrow W2.

  In this way, in the drying chamber 1, a swirling flow of hot air is formed from the other end side to the one end side, and the wooden chip is moved from the one end side to the other end side in the axial direction of the drying chamber 1. The movement of hot air and the movement of wood chips are opposite to each other. As a result, the amount of contact between the wood chip and the hot air is larger than when the object to be treated falls in rotation in the rotary kiln, so that the wood chip is dried with higher efficiency than the rotary kiln. be able to. As a result, even if the moisture content exceeds 50 wt%, such as a wood chip made from raw wood, the moisture content can be dried to 10 wt% or less in a shorter time than conventional, which is suitable for fuel. Wood chips are obtained.

  Further, by forming a hot air swirl flow in the drying chamber 1, the drying chamber 1 can be filled with hot air having a high speed and a high flow rate. Therefore, a larger amount of hot air can be brought into contact with the wood chip than when a burner is installed in the drying chamber like a rotary kiln and the flame is sprayed linearly, and the wood chip can be dried efficiently.

  Further, the stirring device 7 for sending the wood chips has the stirring blades 9 provided with the forward pitch and the stirring blades 9A provided with the reverse pitch. It can be sent from the side toward the other end. Therefore, the temperature deviation of the wood chip in the drying chamber 1 can be reduced. Moreover, the residence time of the wood chip in the drying chamber 1 can be increased, and the drying of the wood chip can be promoted.

  Further, the wood chip dryer of this embodiment has a larger amount of hot air in contact with the wood chips than the conventional rotary kiln, so that the wood chips can be sufficiently dried even if the temperature of the hot air is lower than that of the conventional one. it can. Therefore, drying can be performed while preventing carbonization of the wood chip.

  The wood chip dryer of this embodiment is attached to the rotating shaft 8 because the swirling direction WR of the swirling flow of hot air formed in the drying chamber 1 and the rotating direction R of the rotating shaft 8 are the same. Further, the resistance force that the stirring blades A of the normal pitch receive from the swirling flow of hot air can be reduced. Moreover, since the hot air which turns in the drive direction R of the rotating shaft 8 is flowed, the resistance force which the rotating shaft 8 receives from air can be made small. Therefore, the load acting on the motor that rotationally drives the rotating shaft 8 can be effectively reduced.

  The wood chip dryer according to the present embodiment can dry wood chips made from various wood materials such as thinned wood, pruned wood, mill ends, waste wood, and building waste. In particular, a wood chip having a moisture content of more than 50 wt%, such as a wood chip formed from raw materials, can be quickly dried while preventing carbonization. In addition, a wood chip formed of a material having a low water content such as building waste can be effectively dried with a small amount of fuel consumption by hot air at a relatively low temperature.

  Moreover, the wood chip dryer of this embodiment can dry various wood wastes using wood chips. Wood waste includes waste fungus beds used for fungal cultivation. For example, some waste fungi beds used for the cultivation of mushrooms have a water content exceeding 30 wt% and reaching about 70 wt%. Therefore, when disposing of the waste microbial bed, it is often subjected to incineration disposal using fossil fuel, and there is a problem that the cost burden and the environmental impact are large. Under such circumstances, the moisture content can be reduced to 10 wt% or less while preventing carbonization by performing a drying process on the waste microbial bed using the wood chip dryer of this embodiment. The waste microbial bed dried to a moisture content of 10 wt% or less can be used as a material for wood pellets as a recycled resource material. Wood pellets formed using a waste fungus bed or other wood chips with a moisture content reduced to 10 wt% or less can generate a calorific value of 12.6 MJ / kg (3000 kcal / kg) or more. As described above, according to the wood chip dryer of the present embodiment, it is possible to reuse and recycle the wood waste that has been discarded and incinerated.

  In the above embodiment, the flow rate of hot air supplied to the drying chamber 1 is adjusted by a shutter as an open / close door provided in the first to third slits 13, 14, 15, but the first to third supply pipes 33, 34 are used. , 35 may be provided with a flow rate adjusting valve, and the flow rate of the hot air supplied to the drying chamber 1 may be adjusted by adjusting the flow rate of the first to third supply pipes 33, 34, 35 with this flow rate adjusting valve.

  Moreover, in the said embodiment, although the hexagonal stirring blades 9 and 9A were provided in the stirring apparatus 7, you may use a scoop-shaped stirring blade as shown to the front view of FIG. 7A, and the side view of FIG. 7B. As shown in FIGS. 7A and 7B, the scoop-like stirring blade 109 includes a blade body 94 in which both side portions in the width direction in front view protrude from the center portion, a column portion 92 that supports the blade body 94, and a column A spiral cut 93 is provided at the proximal end of the portion 92. The blade main body 94 has a scooping portion 95 whose front end is curved toward the front side, and side wall portions 96, 96 erected on both sides of the scooping portion 95. The rake portion 95 corresponds to the central portion. By using the scoop-like stirring blade 109, the wood chip in the drying chamber 1 can be effectively scooped and stirred and moved.

  Moreover, in the said embodiment, although the cylindrical casing 2 was supported horizontally and the drying chamber 1 was arrange | positioned horizontally, the drying chamber 1 may be inclined and arrange | positioned.

  In the above embodiment, the hot air supplied to the wood chip dryer is generated by the combustion device using the wood chips dried by the wood chip dryer as fuel, but is generated using waste heat of various factories. May be.

  FIG. 8 is a diagram schematically showing a combustion plant according to an embodiment of the present invention. This combustion plant is a hot water boiler plant that uses a wood chip as a vegetable biomass fuel to produce hot water. This hot water boiler plant 100 includes a wood chip dryer 103 according to an embodiment of the present invention and a heat exchanger integrated combustion furnace 101 that generates warm water using the wood chips dried by the wood chip dryer 103 as fuel. The combustion gas generated in the heat exchanger integrated combustion furnace 101 and heated with water is reused as drying air for the wood chip dryer 103.

  The hot water boiler plant 100 includes a heat exchanger integrated combustion furnace 101, a hot water storage tank for storing water heated in the heat exchanger integrated combustion furnace 101, and combustion discharged from the heat exchanger integrated combustion furnace 101. A wood chip dryer 103 to which gas is supplied, a first fixed amount supply device 104 for supplying undried wood chips to the wood chip dryer 103, and wood chips dried by the wood chip dryer 103 are temporarily stored. Operation of the hot water boiler plant 100, the second fixed-quantity feeder 102 that supplies the heat exchanger integrated combustion furnace 101, the cyclone dust collector 105 that collects the exhaust discharged from the wood chip dryer 103, and The control part 108 which controls is provided.

  The heat exchanger-integrated combustion furnace 101 is connected to a combustion unit 202 corresponding to a combustion device that burns fuel, and the combustion unit 202, and combustion gas generated in the combustion unit 202 is supplied to heat the water. The first heat exchanging unit 203 that exchanges the water and the combustion gas that is connected to the first heat exchanging unit 203 and that has exchanged heat with the first heat exchanging unit 203 are guided to exchange heat between the water and the combustion gas. The second heat exchanging unit 204 further performs the above.

  In the combustion part 202, a rectangular parallelepiped combustion chamber 208 is formed in a box-like combustion chamber casing whose side is defined by a wall formed of a heat insulating material and a castable refractory. A bottom air chamber 213 to which combustion air is supplied from the blower 264 via a bottom air supply pipe 215 is provided below the combustion chamber 208, and air formed on the bottom surface of the combustion chamber 208 from the bottom air chamber 213. Combustion air is supplied to the combustion chamber 208 through the supply hole. Wood chips as fuel conveyed by the supply conveyor 113 of the second metering feeder 102 are fed into the combustion chamber 208 from an opening formed in the wall of the casing. An upper air chamber 228 surrounding the outside of the wall of the combustion chamber 208 is provided at the upper portion of the combustion chamber 208, and combustion air is supplied to the upper air chamber 228 from the blower 264 through the upper air supply pipe 229. The combustion air supplied to the upper air chamber 228 is supplied to the combustion chamber 208 from a plurality of air injection pipes that pass through the wall between the upper air chamber 228 and the combustion chamber 208. The air injection pipes are arranged so as to surround the upper part of the combustion chamber 208, and the combustion air injected from these air injection pipes creates turbulent flow in the combustion chamber 208, thereby mixing the combustion gas. It is formed so as to promote the combustion of fuel in the combustion chamber 208.

  The first heat exchanging unit 203 includes a rectangular parallelepiped combustion gas chamber 235 connected to an upper portion of the combustion chamber 208 of the combustion unit 202, and a water jacket 232 surrounding the combustion gas chamber 235. The water supplied to the water jacket 232 from the hot water storage tank through the water supply pipe 270 is heated by exchanging heat with the combustion gas introduced from the combustion chamber 208 into the combustion gas chamber 235. The water heated by the water jacket 232 is guided to the water chamber 242 of the second heat exchange unit 204. The combustion gas obtained by heating the water in the water jacket 232 is guided from the combustion gas chamber 235 to the smoke chamber provided in the second heat exchange unit 204.

  The second heat exchange unit 204 is a multitubular water heat exchanger, and includes a smoke pipe 243 through which the combustion gas guided from the combustion gas chamber 235 flows. The smoke pipes 243 are arranged in a water chamber 242 through which water heated by the water jacket 232 is guided, and the combustion gas passes through a plurality of smoke chambers provided at both ends in the extending direction of the smoke pipe 243. The direction of flow is changed. For example, a three-pass water heat exchanger that passes through three smoke chambers can be used. The bottom surface of the water chamber 242 of the second heat exchange unit 204 faces the combustion gas chamber 235 of the first heat exchange unit 203. The water in the water chamber 242 is heated by exchanging heat between the combustion gas in the combustion gas chamber 235 and the combustion gas flowing in the smoke pipe 243 and returned to the hot water storage tank through the drain pipe 271. The combustion gas that has exchanged heat with the water in the water chamber 202 by the second heat exchange unit 204 is discharged from the smoke pipe 243 and guided to the wood chip dryer 103 through the supply duct 31.

  The combustion gas guided to the wood chip dryer 103 is blown tangentially into the drying chamber 1 by the air supply device 3 and flows in the drying chamber 1 in a swirling manner to dry the wood chips. The combustion gas obtained by drying the wood chips in the drying chamber 1 is discharged from the exhaust port 4 and guided to the cyclone dust collector 105.

  The cyclone dust collector 105 includes a cylindrical portion 151 provided with a combustion gas suction port on a side surface, an inverted conical separation portion 152 that forms a swirling flow inside the cylindrical portion 151, and a lower portion. The exhaust tube 153 is disposed coaxially inside the cylindrical portion 151 and the separation portion 152, and the upper portion protrudes upward from the cylindrical portion 151. The cyclone dust collector 105 sucks the combustion gas obtained by drying the wood chip with the wood chip dryer 103 from the suction port of the cylindrical portion 151, and forms a swirling flow of the combustion gas between the cylindrical portion 151 and the separation portion 152. The dust contained in the combustion gas is separated by the centrifugal force of the swirling flow. The combustion gas from which the dust has been separated is sucked into the induction fan 106 through the exhaust pipe 153 and released to the atmosphere. As the attracting fan 106, a centrifugal blower can be used.

  Raw wood chips that have a moisture content of more than 50 wt% before being dried by the wood chip dryer 103 are stored in the hopper of the first fixed amount feeder 104. On the upper part of the hopper of the first metering feeder 104, a stirring blade for stirring the wood chip to prevent the formation of a bridge is provided. Raw wood chips stored in the hopper of the first metering feeder 104 are supplied to the wood chip dryer 103 by the supply conveyor 110. A rotary valve 111 is provided between the supply conveyor 110 and the wood chip dryer 103 to prevent the backflow of combustion gas when the wood chip dryer 103 performs a drying operation.

  The wood chips dried by the wood chip dryer 103 and having a moisture content of 10 wt% or less are sent to the second fixed amount feeder 102 via the rotary valve 112 connected to the wood chip discharge port 6. The dried wood chips stored in the hopper of the second constant supply machine 102 are supplied to the heat exchanger integrated combustion furnace 101 by the supply conveyor 113.

  The control unit 108 controls the hot water boiler plant 100 as follows. First, the water levels in the water chamber 242 and the hot water storage tank are confirmed based on the detection information of the water level sensors provided in the water chamber 242 and the hot water storage tank. When the water level in the water chamber 242 and the hot water storage tank is lower than the reference value, water is supplied to the hot water storage tank. When the water levels in the water chamber 242 and the hot water storage tank satisfy the reference value, the circulation pump provided in the water supply pipe 270 is activated, the induction fan 106 and the blower 264 are activated, and the supply conveyor 113 is activated. . By starting the circulation pump, the water in the hot water storage tank is sent to the water jacket 232 of the first heat exchange unit 203. By starting the blower 264, combustion air is supplied to the upper air chamber 228 through the upper air supply pipe 229, and combustion air is supplied to the bottom air chamber 213 through the bottom air supply pipe 215. By starting the supply conveyor 113, the wood chip of the fuel is unwound from the hopper of the fixed-quantity feeder 102, and the fuel is charged into the combustion chamber 208. Subsequently, a flame by an ignition burner is injected from an ignition port provided on the wall surface of the combustion chamber 208, the fuel charged into the combustion chamber 208 is ignited, and combustion of the fuel is started. Combustion gas generated in the combustion chamber 208 includes the combustion gas chamber 235 of the first heat exchange unit 203, the smoke pipe 243 of the second heat exchange unit 204, the supply duct 31, and the drying chamber 1 of the wood chip dryer 103. , The water in the hot water storage tank flows through the water supply pipe 270, the water jacket 232 of the first heat exchange unit 203, the water chamber 242 of the second heat exchange unit 204, and the drain pipe 271. Flowing.

  When hot air of combustion gas is supplied to the drying chamber 1 of the wood chip dryer 103 and a swirling flow of hot air is formed in the drying chamber 1 and the temperature in the drying chamber 1 rises, the control unit 108 includes a rotary valve 112, The stirrer 7 of the wood chip dryer 103, the rotary valve 111, and the supply conveyor 110 of the quantitative feeder 104 are sequentially activated, and the wood chips are put into the wood chip inlet 5. As a result, the wood chip moves in the drying chamber 1 in the direction opposite to the hot air in the axial direction while contacting the swirling flow of the hot air, and the wood chip contacts the hot air for a predetermined time in the drying chamber 1 and dries. The dried wood chip is put into the hopper of the second fixed quantity feeder 102.

  The control unit 108 detects the temperature of the combustion gas detected by the gas temperature sensor T1 provided in the uppermost smoke chamber of the second heat exchange unit 204 and the water temperature sensor T2 provided in the water supply pipe 270. Based on the inlet temperature of the hot water and the outlet temperature of the hot water detected by the water temperature sensor T3 provided in the drain pipe 271, the operation of the supply conveyor 113 is controlled, and the amount of fuel supplied to the combustion chamber 208 is controlled. At the same time, the operation of the induction fan 106 and the blower 264 is controlled to control the amount of combustion air supplied to the combustion chamber 208. When the inlet temperature of the hot water is lower than the reference value, the control unit 108 increases the amount of fuel supplied to the combustion chamber 208 by the supply conveyor 113 and increases the amount of air blown by the blower 264 to burn into the combustion chamber 208. Increase air supply. Further, the suction amount of the induction fan 106 is increased, and the amount of combustion gas sucked from the heat exchanger integrated combustion furnace 101 via the wood chip dryer 103 is increased. As a result, the amount of heat generated by burning the fuel in the combustion chamber 208 increases, the amount of heat exchanged with water in the water jacket 232 and the water chamber 242 increases, the temperature of the circulating water rises, and the inlet The temperature rises. Here, it is confirmed whether the temperature of the combustion gas in the smoke chamber detected by the gas temperature sensor T1 has reached an abnormally high temperature, and the temperature of the combustion gas from the second heat exchange unit 204 detected by the temperature sensor T4. Check if the temperature has reached an abnormally high temperature. When the inlet temperature detected by the water temperature sensor T2 reaches a predetermined temperature, the control unit 108 reduces the amount of fuel supplied by the supply conveyor 113 and reduces the amount of air blown by the blower 264 to burn into the combustion chamber 208. Reduce air supply. At the same time, the suction amount of the induction fan 106 is reduced to reduce the amount of combustion gas sucked from the heat exchanger integrated combustion furnace 101, and the water supply amount of the circulation pump of the water supply pipe 270 is reduced.

  Thus, according to the hot water boiler plant 100 of this embodiment, the wood chip dryer 103 performs pretreatment drying on the wood chips of raw wood as fuel to be burned in the heat exchanger integrated combustion furnace 101. This wood chip dryer 103 reuses the combustion gas generated in the heat exchanger integrated combustion furnace 101 and used to heat water in the first heat exchange unit 203 and the second heat exchange unit 204 as drying air. To do. Therefore, compared with the case where pretreatment drying is performed using fossil fuel, it is possible to effectively use resources for recycling and to effectively reduce running costs.

  In the above embodiment, the drying air supplied to the wood chip dryer is one that reuses the combustion gas of a hot water boiler, but may be one that reuses the combustion gas of another boiler such as a steam boiler. In addition, the present invention is not limited to a boiler, and may use combustion heat generated by another combustion device such as a burner. That is, the present invention can be applied not only to a hot water boiler plant but also to various combustion plants having a combustion device.

  Moreover, in the said embodiment, although combustion gas was used as the air for drying a wood chip, you may use the air heated with the combustion gas by heat exchange as drying air.

  In the above embodiment, wood chips are used as the vegetable biomass fuel. It is also possible to use various plant biomass such as cotton husk, sunflower seed husk, jatroba husk, and roasted coffee crumb (chaff).

DESCRIPTION OF SYMBOLS 1 Drying chamber 2 Cylindrical casing 3 Air supply apparatus 4 Exhaust port 5 Wood chip insertion port 6 Wood chip discharge port 7 Stirrer 8 Rotating shaft 9 Agitation blade 13 1st slit 14 2nd slit 15 3rd slit

Claims (11)

A pretreatment dryer for pretreatment drying of plant biomass fuel,
A cylindrical drying chamber;
An inlet provided on one end side in the axial direction of the drying chamber, and into which an object to be processed which is the biomass fuel is charged,
A discharge port that is provided on the other end side in the axial direction of the drying chamber, and discharges the workpiece;
An air supply port that is provided on the other end side in the axial direction of the drying chamber, and supplies drying air in a tangential direction of the drying chamber;
An exhaust port that is provided on one end side in the axial direction of the drying chamber and exhausts air in a tangential direction from the drying chamber;
A rotating shaft that is arranged coaxially with the central axis of the drying chamber and is driven to rotate;
A stirring blade spirally disposed on the outer peripheral surface of the rotating shaft,
The moving direction of the air in the drying chamber and the moving direction of the workpiece are opposite to each other in the axial direction of the drying chamber,
The biomass fuel pretreatment dryer, wherein the drying air is air heated by combustion heat of the workpiece. In the biomass fuel pretreatment dryer according to claim 1,
At least a part of the stirring blade is provided with a forward pitch for propelling the object to be processed from one end side to the other end side of the rotating shaft. In the biomass fuel pretreatment dryer according to claim 2,
A biomass fuel pretreatment dryer, wherein a part of the stirring blade is provided with a reverse pitch for propelling the object to be processed from the other end side to the one end side of the rotating shaft. In the biomass fuel pretreatment dryer according to any one of claims 1 to 3,
The biomass fuel pretreatment dryer, wherein the stirring blade is formed in a scoop shape. In the biomass fuel pretreatment dryer according to any one of claims 1 to 4,
A biomass fuel pretreatment dryer, wherein a plurality of the air supply ports are provided side by side in the axial direction of the drying chamber. In the biomass fuel pretreatment dryer according to any one of claims 1 to 5,
The biomass fuel pretreatment dryer, wherein the air supply port has a flow rate adjusting means for adjusting a flow rate of drying air supplied to the drying chamber. In the biomass fuel pretreatment dryer according to claim 2,
A biomass fuel pretreatment dryer, wherein a swirling direction of a swirling flow of air formed in the drying chamber and a rotating direction of the rotating shaft are the same. In the biomass fuel pretreatment dryer according to any one of claims 1 to 7,
The said to-be-processed object has a moisture content of 30 wt% or more and 70 wt% or less, The biomass fuel pretreatment dryer characterized by the above-mentioned. In the biomass fuel pretreatment dryer according to any one of claims 1 to 8,
The pretreatment dryer for biomass fuel, wherein the object to be treated is a wood chip formed by crushing a raw tree. In the biomass fuel pretreatment dryer according to any one of claims 1 to 8,
A biomass fuel pretreatment dryer, wherein the object to be treated is a used fungal bed made of wood chips. A biomass fuel pretreatment dryer according to any one of claims 1 to 10,
A combustion apparatus that uses vegetable biomass fuel dried by the pretreatment dryer as fuel,
A combustion plant, wherein combustion gas generated by burning plant biomass fuel in the combustion device is supplied to the pretreatment dryer as drying air.

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