阅读说明：本技术 干燥方法以及干燥装置 (drying method and drying apparatus ) 是由 关本贤一 小菅克志 小水流广行 谷奥亘 铃木淳 于 2017-12-20 设计创作，主要内容包括：本发明提供干燥方法以及干燥装置。该干燥方法是至少具有流化室(12)和混合室(14)的干燥装置(1)中的使含有水分的被干燥物(W3)干燥的方法,其中,使对被干燥物(W3)预先干燥而得到的预干燥物(W1),在供给到流化室(12)内的状态下,进一步流化而成为流化预干燥物(W2),在使流化预干燥物(W2)移动到与流化室(12)通过分隔件(13)划分开并且通过形成于分隔件(13)的下部的贯通孔(13a)相互连通的混合室(14)内的状态下,从比贯通孔(13a)靠上方朝流化预干燥物(W2)中混合被干燥物(W3)。(The invention provides a drying method and a drying apparatus. The drying method is a method for drying a dried object (W3) containing moisture in a drying device (1) at least comprising a fluidizing chamber (12) and a mixing chamber (14), wherein a predried object (W1) obtained by predrying the dried object (W3) is further fluidized to become a fluidized predried object (W2) in a state of being supplied into the fluidizing chamber (12), and the dried object (W3) is mixed from above the through hole (13a) into the fluidized predried object (W2) in a state of moving the fluidized predried object (W2) into the mixing chamber (14) which is partitioned from the fluidizing chamber (12) by a partition (13) and is communicated with each other through the through hole (13a) formed at the lower part of the partition (13).)

1. A drying method for drying a material to be dried containing moisture in a drying apparatus having at least a fluidizing chamber and a mixing chamber,

Fluidizing the pre-dried material obtained by pre-drying the object to be dried in a state of being supplied into the fluidizing chamber to obtain a fluidized pre-dried material,

The fluidized predryed object is moved into the mixing chamber partitioned from the fluidizing chamber by a partition and communicating with each other through a through hole formed in a lower portion of the partition, and the object to be dried is mixed with the fluidized predryed object from above the through hole.

2. The drying method according to claim 1,

The predried object is fluidized by supplying a drying gas flowing from below to above to the predried object.

3. Drying method according to claim 2,

The material to be dried is mixed with the fluidized predried material from above or from the side.

4. Drying method according to any of claims 1 to 3,

The predried object is obtained from a 3 rd chamber which is divided from the mixing chamber by a 2 nd partition and is communicated with the mixing chamber through a 2 nd through hole formed in the 2 nd partition.

5. Drying method according to any of claims 1 to 4,

The pre-dried large-diameter product having a particle diameter of a reference value or more is dried while being fluidized to form the fluidized pre-dried product.

6. Drying method according to claim 5,

The pre-dried large-diameter material is dried while being fluidized by a reference ratio to obtain the fluidized pre-dried material.

7. A drying device for drying an object to be dried containing moisture, comprising:

A drying chamber having at least a fluidizing chamber and a mixing chamber partitioned from the fluidizing chamber by a partition and communicating with each other through a through-hole formed in a lower portion of the partition;

A pre-dried material supply unit configured to supply a pre-dried material obtained by pre-drying the object to be dried into the fluidizing chamber;

A fluidizing unit for fluidizing the predried object supplied into the drying chamber in the fluidizing chamber to obtain a fluidized predried object; and

And a dried material supply unit for mixing the dried material with the fluidized predried material moving from the fluidizing chamber to the mixing chamber through the through hole from above the through hole.

8. Drying apparatus according to claim 7,

The fluidizing section supplies a drying gas flowing from below to above to the pre-dried object supplied into the drying chamber, thereby fluidizing the pre-dried object.

9. Drying apparatus according to claim 8,

The dried material supplying section mixes the dried material with the fluidized predried material from above or from the side.

10. Drying apparatus according to any one of claims 7 to 9,

The drying chamber has a 3 rd chamber which is divided from the mixing chamber by a 2 nd partition and is communicated with the mixing chamber through a 2 nd through hole formed in the 2 nd partition,

The end of the pre-dried object supply part is connected with the side plate of the 3 rd chamber.

11. Drying apparatus according to any one of claims 7 to 10,

The drying device includes a classifying unit that classifies the pre-dried material dried in the drying chamber based on particle size and supplies a pre-dried large-diameter material having a particle size of a reference value or more among the pre-dried material to the pre-dried material supply unit.

12. Drying apparatus according to claim 11,

The classifying part is a screening classifier.

13. Drying apparatus according to claim 11 or 12,

The drying device includes a classifying coal flow rate adjusting unit that supplies a reference proportion of the pre-dried large diameter object to the pre-dried object supply unit.

Technical Field

The present invention relates to a drying method and a drying apparatus.

Background

Conventionally, a drying method for drying a drying object such as coal or sludge containing moisture has been studied.

When drying a high-moisture powdery object in a drying chamber, the object may adhere to or stay in the drying chamber, and the inlet of the drying chamber may be clogged. Therefore, a method of introducing a cleaning gas to a portion to which the object to be dried is attached to suppress the attachment of the object to be dried is adopted.

However, this method requires introduction of a cleaning gas to a plurality of portions of the drying chamber, which leads to an increase in facility cost and running cost.

Therefore, in the drying method disclosed in patent document 1, a part of the dried material (pre-dried material) obtained by drying the brown coal (dried material) in the drying chamber is returned to the supply line and the supply hopper, and then supplied to the drying chamber. This reduces the moisture content of the lignite and the dried matter supplied to the drying chamber as a whole. As a result, the lignite is less likely to adhere to the drying chamber, and clogging of the inlet of the drying chamber can be suppressed.

On the other hand, in the drying chamber, the fluidized steam is introduced into the lignite to cause the lignite to flow, thereby forming a fluidized bed. Further, the lignite is dried by a heat transfer member provided in the drying chamber. The dried brown coal is used as product coal and is used as a raw material for boilers and the like. Further, a part of the dried brown coal is supplied to the drying chamber as the dried matter.

Disclosure of Invention

Problems to be solved by the invention

however, in the drying method of patent document 1, it is also conceivable that the lignite is adhered to or stays in the fluidized bed depending on the amount of moisture contained in the lignite and the amount of treated lignite. In this case, the lignite charged into the drying chamber may be accumulated in the drying chamber, and a part of the lignite may not be dried.

The present invention has been made in view of the above problems, and an object thereof is to provide a drying method and a drying apparatus capable of uniformly drying an object to be dried regardless of the amount of moisture contained in the object to be dried and the amount of processing of the object to be dried.

Means for solving the problems

In order to solve the above problems, the present invention proposes the following means.

(1) The drying method of the present invention is a drying method for drying a drying object containing moisture in a drying apparatus having at least a fluidizing chamber and a mixing chamber, characterized in that,

Fluidizing the pre-dried material obtained by pre-drying the object to be dried in a state of being supplied into the fluidizing chamber to obtain a fluidized pre-dried material,

The fluidized predryed object is moved into the mixing chamber partitioned from the fluidizing chamber by a partition and communicating with each other through a through hole formed in a lower portion of the partition, and the object to be dried is mixed with the fluidized predryed object from above the through hole.

(2) The drying device of the present invention is a drying device for drying an object to be dried containing moisture, and is characterized by comprising:

A drying chamber having at least a fluidizing chamber and a mixing chamber partitioned from the fluidizing chamber by a partition and communicating with each other through a through-hole formed in a lower portion of the partition;

A pre-dried material supply unit configured to supply a pre-dried material obtained by pre-drying the object to be dried into the fluidizing chamber;

A fluidizing unit for fluidizing the predried object supplied into the drying chamber in the fluidizing chamber to obtain a fluidized predried object; and

And a dried material supply unit for mixing the dried material with the fluidized predried material moving from the fluidizing chamber to the mixing chamber through the through hole from above the through hole.

According to these inventions, the fluidized predrying material is a dried material obtained by predrying a material to be dried and further fluidizing and drying the material. Therefore, by mixing the object to be dried into the fluidized predried object, the object to be dried is efficiently fluidized, and the object to be dried in a fluidized state is dried. In addition, the material to be dried is mixed with the fluidized predried material in the mixing chamber in a state where the fluidized predried material is more reliably fluidized in the fluidizing chamber.

(3) in the drying method, the predried object may be fluidized by supplying a drying gas flowing upward from below to the predried object.

(4) In the drying apparatus, the fluidizing unit may fluidize the pre-dried object by supplying a drying gas flowing from below to above to the pre-dried object supplied into the drying chamber.

According to these inventions, the predried object may adhere to the lower part of the drying chamber or the like due to its own weight. By supplying the pre-dried object with the drying gas flowing upward from below, an external force directed upward acts on the object to be dried attached to the lower portion of the drying chamber or the like.

(5) In the drying method, the material to be dried may be mixed with the fluidized predried material from above or from the side.

(6) In the drying device, the object-to-be-dried may be mixed with the fluidized predried object from above or from the side by the object-to-be-dried supply unit.

According to these inventions, the direction of supplying the drying gas to the predried object is different from the direction of mixing the object to be dried into the fluidized predried object.

(7) In the drying method, the predried object may be obtained from a 3 rd chamber partitioned from the mixing chamber by a 2 nd partition and communicating with each other through a 2 nd through-hole formed in the 2 nd partition.

(8) In the drying apparatus, the drying chamber may include a 3 rd chamber partitioned from the mixing chamber by a 2 nd partition and communicating with each other through a 2 nd through hole formed in the 2 nd partition, and an end of the predried object supply portion may be connected to a side plate of the 3 rd chamber.

According to these inventions, the object to be dried is mixed with the fluidized predryed object in the mixing chamber in a state where the fluidized predryed object is more reliably fluidized in the fluidizing chamber.

(9) in the drying method, the pre-dried large-diameter product having a particle diameter of a reference value or more in the pre-dried product may be further fluidized and dried to be the fluidized pre-dried product.

the inventor finds that: in the predried object, the predried object having a large particle size contains a larger proportion of water than the predried object having a small particle size. When the proportion of the moisture contained is small, the temperature of the predried object tends to rise when the predried object is heated.

(10) In the drying method, the pre-dried large-diameter product may be dried while being fluidized in an amount corresponding to a reference ratio to obtain the fluidized pre-dried product.

(11) The drying device may further include a classifying unit that classifies the pre-dried material dried in the drying chamber based on a particle size and supplies a pre-dried large-diameter material having the particle size of a reference value or more among the pre-dried material to the pre-dried material supply unit.

(12) In the drying device, the classifying unit may be a screen classifier.

(13) The drying device may further include a classifying coal flow rate adjusting unit that supplies the pre-dried material supply unit with a reference ratio of the pre-dried large diameter material.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the drying method described in the above (1) and the drying apparatus described in the above (2), the object to be dried can be uniformly dried regardless of the amount of moisture contained in the object to be dried and the amount of the object to be dried to be processed. In addition, the object to be dried can be mixed in a state where the fluidized predried object is more reliably fluidized.

According to the drying method described in the above (3) and the drying apparatus described in the above (4), the predried object can be efficiently fluidized.

according to the drying method described in the above (5) and the drying apparatus described in the above (6), the object to be dried mixed in the fluidized predried object is less likely to cause an obstacle to the drying gas supplied to the predried object.

According to the drying method described in the above (7) and the drying apparatus described in the above (8), the object to be dried can be mixed with the fluidized preliminary mixture in the mixing chamber in a state where the fluidized preliminary dried object is more reliably fluidized.

According to the drying methods described in the above (9) and (10), it is possible to suppress the temperature of the pre-dried large diameter material or the like from becoming excessively high due to the decrease in the proportion of moisture in the pre-dried large diameter material.

According to the drying apparatus described in the above (11) to (13), the ratio of the pre-dried large diameter material to be fluidized pre-dried can be adjusted, and the temperature of the pre-dried large diameter material and the like can be more effectively adjusted.

Drawings

fig. 1 is a diagram schematically showing the configuration of a drying apparatus according to embodiment 1 of the present invention.

FIG. 2 is a view showing a state in which dry coal is fluidized.

FIG. 3 is a view showing a state where the dried coal is not fluidized.

Fig. 4 is a front view showing a main part of a drying apparatus according to embodiment 2 of the present invention.

Fig. 5 is a graph showing the relationship between the cumulative mass of LY coal dried in the drying apparatus and the particle diameter.

Fig. 6 is a graph showing the relationship between the adhesion force of LY coal dried by the drying apparatus and the moisture content.

Fig. 7 is a graph showing the detection results of the respective temperature sensors with respect to the elapsed time in the experimental results of the example in which LY coal was dried using this drying device.

Fig. 8 is a graph showing the detection results of the respective temperature sensors with respect to the elapsed time in the experimental results of the comparative example in which LY coal was dried using the drying device.

Fig. 9 is a diagram schematically showing the configuration of the drying apparatus according to embodiment 3 of the present invention.

Fig. 10 is a diagram illustrating an image of contained water based on classification of contained water of LY coal.

Fig. 11 is a graph showing changes in the cumulative ratio of coal with respect to particle size at the ratio of each moisture in coal.

Fig. 12 is a graph showing changes in the ratio of the average particle size to moisture.

FIG. 13 is a graph showing changes in the proportion of undersize weight ratio of 0.6mm or less to moisture.

Fig. 14 is a graph showing the change in the cumulative proportion of lignite having a moisture content of 60% with respect to the particle size.

Fig. 15 is a graph showing changes in the cumulative proportion of lignite dried to an average moisture content of 20% with respect to the particle size.

Detailed Description

(embodiment 1)

Hereinafter, embodiment 1 of the drying device according to the present invention will be described with reference to fig. 1 to 3. The drying apparatus is used for continuously drying coal (drying object) with high water content such as brown coal.

As shown in fig. 1, a drying device 1 of the present embodiment includes: a drying chamber 11; a return pipe (pre-dried material supply unit) 21 for supplying dried coal (pre-dried material) W1 obtained by pre-drying coal to the drying chamber 11; a fluidizing unit 26 for fluidizing and drying the dried coal W1 supplied into the drying chamber 11 to obtain fluidized coal (fluidized predried coal) W2; and a supply hopper (dried material supply unit) 31 for mixing coal W3 with fluidized coal W2.

The drying chamber 11 has: a 1 st chamber (fluidizing chamber) 12; a 2 nd chamber (mixing chamber) 14 partitioned from the 1 st chamber 12 by a partition 13; and a 3 rd chamber 16 partitioned from the 2 nd chamber 14 by a partition 15. The 1 st chamber 12, the 2 nd chamber 14, and the 3 rd chamber 16 are arranged in parallel along a horizontal plane, for example. The bottom plates of the 1 st chamber 12, the 2 nd chamber 14, and the 3 rd chamber 16 use a dispersion plate 17. The dispersion plate 17 is formed with a plurality of communication holes 17a penetrating in the vertical direction. For example, one communication hole 17a is formed below each of the chambers 12, 14, and 16.

A through hole 13a is formed in the lower portion of the separator 13. The 1 st chamber 12 and the 2 nd chamber 14 communicate with each other through the through hole 13a of the partition 13. Similarly, a through hole 15a is formed in a lower portion of the separator 15. The 2 nd chamber 14 and the 3 rd chamber 16 communicate with each other through the through hole 15a of the partition 15.

A first end of the return pipe 21 is connected to, for example, a side plate (not shown) of the 1 st chamber 12 on the side opposite to the 2 nd chamber 14. A second end portion of the return pipe 21 is connected to an intermediate portion along the longitudinal direction of a product conveying pipe 36 described later. The return pipe 21 supplies the dry coal W1 into the 1 st chamber 12.

The fluidizing portion 26 has: a drying gas generator 27 for generating a drying gas W6; and a drying gas chamber 28 provided below the dispersion plate 17 and supplied with the drying gas W6 generated by the drying gas generator 27. In addition, although water vapor is used as the drying gas W6 in the present embodiment, high-temperature air or the like may be used as the drying gas W6.

As the drying gas generator 27, a known device such as a boiler can be used. As the drying gas generator 27, a heat exchanger or the like provided in a cooling device 37 or the like described later may be used. The dried coal W1 is cooled by the cooling water in the heat exchanger, and the cooling water is heated to obtain the drying gas W6.

The top plate of the drying gas chamber 28 is the dispersion plate 17 described above. In the present embodiment, an example is shown in which the drying gas chamber 28 is divided into 3 chambers corresponding to the respective chambers 12, 14, and 16. The drying gas chamber 28 communicates with the chambers 12, 14, and 16 through the communication holes 17a of the dispersion plate 17.

The supply hopper 31 is connected to the ceiling of the 2 nd chamber 14.

A first end of the product delivery pipe 36 is connected to a side plate of the 3 rd chamber 16 opposite to the 2 nd chamber 14. A second end of the product delivery pipe 36 is connected to a cooling device 37. A first end of a steam pipe 39 is connected to a ceiling of the 3 rd chamber 16. The second end of the steam pipe 39 is connected to a dust collecting device 40.

A first end of a connection pipe 41 is connected to the dust collecting device 40. A second end of the connecting pipe 41 is connected to an intermediate portion of the product conveying pipe 36.

Next, a drying method of the present embodiment using the drying device 1 configured as described above will be described.

As described later, the coal W3 was dried in advance to obtain dried coal W1. The return pipe 21 supplies the dry coal W1 into the 1 st chamber 12.

The drying gas generator 27 of the fluidizing portion 26 generates a drying gas W6. The drying gas W6 is supplied to the drying gas chamber 28, and is supplied to the chambers 12, 14, and 16 of the drying chamber 11 through the communication holes 17a of the dispersion plate 17.

in the 1 st chamber 12, a drying gas W6 flowing upward from below is supplied to the dried coal W1 through the communication holes 17a of the dispersion plate 17. Thus, the dried coal W1 is further dried while being fluidized. In this way, the dried coal W1 was further fluidized and dried to obtain fluidized coal W2.

The dry coal W1 may adhere to the dispersion plate 17 or the like in the lower portion of the 1 st chamber 12 or the like due to its own weight. By supplying the drying gas W6 flowing upward from below to the dried coal W1, an external force directed upward acts on the coal W3 adhering to the dispersion plate 17.

The drying gas W6 is supplied not only into the 1 st chamber 12 but also into the 2 nd chamber 14 and the 3 rd chamber 16 so as to flow upward from below.

The term "fluidization" as used herein means a state in which coal or the like flows without being attached to a room or a pipe. Specifically, when the dry coal W1 is fluidized by the drying gas W6 in the 1 st chamber 12, the dry coal W1 flows without adhering to the dispersion plate 17, the side plate, and the like in the lower part of the 1 st chamber 12, as shown in fig. 2. The fluidized coal W2 formed a fluidized bed in which the dried coal W1 floated in the drying gas W6.

On the other hand, when the dry coal W1 is not fluidized by the drying gas W6, as shown in fig. 3, the dry coal W1 does not flow in the 1 st chamber 12 and adheres to the dispersion plate 17 and the like due to the self weight of the dry coal W1, the adhesion of the dry coal W1, and the like.

In this way, the fluidizing portion 26 supplies the drying gas W6 flowing upward from below to the dried coal W1 supplied into the 1 st chamber 12, thereby fluidizing the dried coal W1 in the 1 st chamber 12. In a state where the dry coal W1 was supplied into the 1 st chamber 12, the dry coal W1 was changed to fluidized coal W2.

the fluidized coal W2 moves from the 1 st chamber 12 to the 2 nd chamber 14 through the through-hole 13a formed in the partition 13. The feed hopper 31 mixes the fluidized coal W2 moved to the 2 nd chamber 14 with the coal W3. That is, the fluidized coal W2 was moved into the 2 nd chamber 14, and the coal W3 was mixed with the fluidized coal W2. At this time, the supply hopper 31 mixes the fluidized coal W2 with the coal W3 from above.

The fluidized coal W2 is coal obtained by drying coal W3 in advance and further drying the coal while fluidizing the coal. Therefore, the coal W3 is mixed with the fluidized coal W2 in the 2 nd chamber 14, whereby the coal W3 is efficiently fluidized and the fluidized coal W3 is dried. In the drying apparatus 1, the direction of supplying the drying gas W6 to the dried coal W1, i.e., the direction from the bottom toward the top, is different from the direction of supplying the coal W3 to the fluidized coal W2, i.e., the direction from the top toward the bottom. Since the drying chamber 11 includes the 1 st chamber 12, the partition 13, and the 2 nd chamber 14, the coal W3 is mixed into the fluidized coal W2 in the 2 nd chamber 14 in a state where the fluidized coal W2 is more reliably fluidized in the 1 st chamber 12.

In addition, the fluidized coal W2 is further fluidized and dried by the drying gas W6 in the 2 nd chamber 14.

the fluidized coal W2 and the coal W3 move from the inside of the 2 nd chamber 14 to the 3 rd chamber 16 through the through-holes 15a formed in the partition 15. The fluidized coal W2 and the coal W3 were further fluidized and dried by the drying gas W6 in the 3 rd chamber 16. A part of the dried coal W1 obtained from the dried fluidized coal W2 and the coal W3 is transported by the product transport pipe 36 and supplied to the cooling device 37.

The cooling device 37 is provided with, for example, a heat exchanger not shown. The dried coal W1 was cooled by the heat exchanger. The heat exchanger may contain cooling water.

The dried coal W1 cooled by the cooling device 37 is transported from the cooling device 37 and used as product coal W7 as a raw material for boilers and the like.

The other part of the dried coal W1 obtained from the fluidized coal W2 and the coal W3 in the 3 rd chamber 16 is transported through the return pipe 21 and supplied into the 1 st chamber 12 of the drying chamber 11.

on the other hand, the wet gas W8 obtained from the dried fluidized coal W2 and the coal W3 is discharged from the upper portion of the 3 rd chamber 16. The wet gas W8 is a gas containing dried coal W3 powder in steam. The dust collector 40 recovers the coal W3 powder from the wet gas W8. The recovered coal W3 powder is supplied to the cooling device 37 through the connection pipe 41 and the product conveyance pipe 36, and turns into product coal W7. On the other hand, the wet gas W8 treated by the dust collector 40 is discharged to the outside.

As described above, according to the drying apparatus 1 and the drying method of the present embodiment, the fluidized coal W2 is coal obtained by drying the coal W3 in advance, fluidizing the coal and drying the coal at the same time. Therefore, by mixing the coal W3 with the fluidized coal W2, the coal W3 is efficiently fluidized, and the fluidized coal W3 is dried. Therefore, the coal W3 can be dried uniformly regardless of the amount of moisture contained in the coal W3 or the treatment amount of the coal W3.

The drying gas W6 flowing upward from below was supplied to the dried coal W1 to fluidize the dried coal W1. The dry coal W1 may adhere to the lower portion of the drying chamber 11 by its own weight. By supplying the drying gas W6 flowing upward from below to the dried coal W1, an external force directed upward acts on the dried coal W1 attached to the lower portion of the drying chamber 11. This enables the dried coal W1 to be efficiently fluidized.

The direction of supplying the drying gas W6 to the dried coal W1, i.e., the direction from below to above, and the direction of supplying the coal W3 to the fluidized coal W2, i.e., the direction from above to below, are different. Therefore, the coal W3 supplied from above to below hardly interferes with the drying gas W6 supplied from below to above.

Since the drying chamber 11 includes the 1 st chamber 12, the partition 13, and the 2 nd chamber 14, the coal W3 is mixed into the fluidized coal W2 in the 2 nd chamber 14 in a state where the fluidized coal W2 is more reliably fluidized in the 1 st chamber 12. Therefore, the coal W3 can be fluidized more reliably.

in the present embodiment, the supply hopper 31 supplies the coal W3 to the fluidized coal W2 transferred from the 1 st chamber 12 to the 2 nd chamber 14. However, the supply hopper 31 may supply the coal W3 to the fluidized coal W2 moving from the 1 st chamber 12 to the 3 rd chamber 16 through the 2 nd chamber 14. The 1 st chamber 12 and the 3 rd chamber 16 are partitioned by two partitions 13 and 15, and communicate with each other through holes 13a and 15a of the partitions 13 and 15 and the 2 nd chamber 14. In this case, the 3 rd chamber 16 corresponds to a mixing chamber.

The drying chamber 11 has three chambers, i.e., a 1 st chamber 12, a 2 nd chamber 14, and a 3 rd chamber 16. However, the number of chambers included in the drying chamber 11 is not limited to this, and may be two, or four or more.

in order to stably fluidize the coal W3, it is necessary to cover the surface of the high-moisture coal W3 (wet coal) which has high adhesion and is difficult to fluidize with the recycled dry coal W1. When dry coal W1 and coal W3 were supplied to one chamber at the same time, the dispersing effect of mixing dry coal W1 and coal W3 could not be exhibited properly, and segregation of coal W3 could occur. Therefore, the number of chambers included in the drying chamber 11 is preferably two or more.

The supply hopper 31 is connected to the ceiling of the 2 nd chamber 14. However, the supply hopper 31 may be connected to a side plate of the 2 nd chamber 14. In this case, the supply hopper 31 supplies the coal W3 from the side direction fluidized coal W2.

(embodiment 2)

Next, embodiment 2 of the present invention will be described with reference to fig. 4 to 8, but the same parts as those in the above embodiment are given the same reference numerals, and the description thereof will be omitted, and only the differences will be described. The drying apparatus of the present embodiment is used for batch-wise drying the coal W3. As shown in fig. 4, the drying device 2 of the present embodiment includes a drying chamber 51 formed in a square tube shape. The drying chamber 51 is disposed such that its axis extends in the vertical direction.

The lower end of the drying chamber 51 is connected to a drying gas chamber 62 via a dispersion plate 61. A drying gas W6 is supplied from a drying gas generator 27, not shown, to the drying gas chamber 62. In the present embodiment, steam is used as the drying gas W6. The fluidizing portion 63 is formed by the drying gas chamber 62 and the drying gas generator 27.

In the drying chamber 51, a coal discharge pipe 53, an observation window 54, a coal supply pipe (pre-drying object supply part, object-to-be-dried supply part) 55, and a steam pipe 39 are provided in this order from below toward above. The coal discharge pipe 53 is a pipe for taking out the dried coal W1 produced in the drying chamber 51 to the outside. The observation window 54 is a window for visually checking the inside of the drying chamber 51. The coal supply pipe 55 is a pipe for supplying the dry coal W1 and the coal W3 into the drying chamber 51. An opening of an upper end portion of the drying chamber 51 is sealed by a cover member 56.

Next, a drying method of the present embodiment using the drying device 2 configured as described above will be described. In the initial state of the drying apparatus 2, the drying gas W6 is not supplied through the fluidizing portion 63.

First, dry coal W1 is supplied into the drying chamber 51 through the coal supply pipe 55. The amount of dry coal W1 laid (disposed) on the dispersion plate 61 can be confirmed through the observation window 54.

Next, a drying gas W6 is supplied to the dried coal W1 from below through the fluidizing portion 63. The drying gas W6 flows upward through communication holes, not shown, formed in the dispersion plate 61. Thus, the dried coal W1 in the drying chamber 51 is fluidized and dried, and becomes fluidized coal W2 (not shown). The state of fluidization of the fluidized coal W2 can be confirmed through the observation window 54.

Next, coal W3 is supplied into the drying chamber 51 through the coal supply pipe 55. By supplying the coal W3 to the fluidized coal W2 fluidized in the drying chamber 51, the coal W3 is efficiently fluidized and the fluidized coal W3 is dried. The coal W3 dried in the drying chamber 51 becomes dry coal W1.

The dry coal W1 is taken out to the outside from the coal discharge pipe 53.

According to the drying device 2 of the present embodiment configured as described above, the coal W3 can be dried uniformly regardless of the amount of moisture contained in the coal W3 or the treatment amount of the coal W3.

(examples)

hereinafter, examples of the present invention and comparative examples are specifically shown and described in detail, but the present invention is not limited to the following examples.

first, LY coal used as coal dried by the drying device 2 will be explained. The LY coal is brown coal collected by the lay Yang, and in the present embodiment, is used in a state of being pulverized. Fig. 5 is a graph showing the relationship between the cumulative mass of coal and the particle size. In fig. 5, the horizontal axis represents the particle diameter (mm) of coal, and the vertical axis represents the cumulative mass (%) of coal. For example, in this coal, the mass of coal having a particle size of 1.7mm or less is 40.9% with respect to the mass of the whole coal. The relation of the cumulative mass with respect to each particle diameter was determined as an approximate curve L1. From the approximate curve L1, it was found that the particle diameter was 2.1mm relative to the cumulative mass of 50%.

FIG. 6 shows the relationship between the adhesion of LY coal and the moisture content. In fig. 6, the horizontal axis represents moisture (mass%) contained in LY coal, and the vertical axis represents adhesion of LY coal (g/cm2 is 100 Pa). Based on the specifications of the Japan powder Industrial technology Association, SAP 15-13: 2013. adhesion was measured by the Jenike cell method described in the powder one-side shear test method.

Therefore, the following steps are carried out: when the moisture content was changed from 55 mass% to 60 mass%, the adhesion of LY coal was drastically enhanced.

in the drying apparatus 2, the size of the dispersion plate 61 was set to 180mm × 110 mm. The dispersion plate 61 has communication holes formed at a pitch of 21 mm. The aperture ratio of the dispersion plate 61 was 8.74%.

in the experiment, as shown in fig. 4, three temperature sensors 66, 67, and 68 were installed in the drying chamber 51 from below toward above. The lower temperature sensor 66 is installed at a height corresponding to the coal discharge pipe 53. The middle temperature sensor 67 is installed at a height corresponding to the lower end portion of the observation window 54. The upper temperature sensor 68 is mounted at a height corresponding to the intermediate portion between the coal supply pipe 55 and the steam pipe 39.

Further, steam was used as the drying gas W6 supplied to the drying chamber 51, and the temperature of the steam was set to 70 ℃.

As examples, the following experiments were performed.

2kg of LY coal having a moisture content of 55% was fluidized and dried beforehand with a drying gas W6 having a flow rate of 150Nm3/h (standard cubic meter/hour) and a flow velocity of 2.1m/s (meter/second) over the dispersion plate 61. As shown in FIG. 6, the adhesion of LY coal having a moisture content of 55% was about 2g/cm 3. 2kg of LY coal was fluidized to become fluidized coal W2.

Fig. 7 shows the detection results of the temperature sensors 66, 67, and 68 with respect to the elapsed time after fluidizing LY 2kg of coal. The horizontal axis of fig. 7 represents the elapsed time (minutes) after fluidization of LY coal, and the vertical axis represents the temperature (deg.c) of the detection results of the temperature sensors 66, 67, 68. The broken line L6 indicates the detection result of the lower temperature sensor 66. Similarly, a two-dot chain line L7 indicates the detection result of the middle temperature sensor 67, and a solid line L8 indicates the detection result of the upper temperature sensor 68.

At time t1 when the elapsed time was 1 minute, 4kg of LY coal having a moisture content of 63% was supplied from above the fluidized coal W2 through the coal supply pipe 55. The adhesion of LY coal having a moisture content of 63% was about 4.8g/cm3 (see FIG. 6).

In a constant temperature drying section R1 in which the elapsed time is about 0 minute to 80 minutes, the temperature sensors 66, 67, and 68 are maintained at about 35 ℃. In the decreasing rate drying section R2 after about 80 minutes, the temperatures detected by the temperature sensors 66, 67, and 68 gradually increase. Therefore, the following steps are carried out: the detected temperatures are a lower temperature sensor 66, a middle temperature sensor 67, and an upper temperature sensor 68 in order of temperature from high to low.

Therefore, the following steps are carried out: the initially supplied 2kg of LY coal and the additionally supplied 4kg of LY coal were fluidized in both of the constant-temperature drying zone R1 and the reduction-rate drying zone R2. The fluidization of LY coal was also confirmed visually through the observation window 54.

As a result, it was found that: the LY coal is stably fluidized in the drying chamber 51, and the LY coal does not adhere to the drying chamber 51.

On the other hand, as comparative examples, the following experiments were performed.

6kg of LY coal having a moisture content of 63% was charged into the dispersion plate 61. The LY coal was fluidized by supplying the drying gas W6 to the LY coal from below through the fluidizing portion 63. Fig. 8 shows the detection results of the temperature sensors 66, 67, and 68 with respect to the elapsed time after the supply of the drying gas W6. The abscissa of fig. 8 represents the elapsed time (minutes) after the supply of the drying gas W6, and the ordinate represents the temperature (deg.c) of the detection results of the temperature sensors 66, 67, 68.

In the example of FIG. 8, the flow rate of the drying gas W6 was set to 150Nm3/h, and the flow velocity on the dispersion plate 61 was set to 2.1 m/s. The broken line L11 indicates the detection result of the lower temperature sensor 66. Similarly, a two-dot chain line L12 indicates the detection result of the middle temperature sensor 67, and a solid line L13 indicates the detection result of the upper temperature sensor 68.

As described above, LY coal having a moisture content of 63% has relatively strong adhesion. Thus, it can be seen that: even if the drying gas W6 is supplied, LY coal is deposited on the dispersion plate 61 and blocks the communication holes of the dispersion plate 61. As a result, it was found that: the temperatures detected by the temperature sensors 67 and 68 are lower than the temperature sensor 66, and the LY coal does not fluidize.

Further, although experiments were carried out while increasing the flow rate of the drying gas W6 to 5.0m/s, it was found that: LY coal still accumulates on the dispersion plate 61 without being fluidized.

Therefore, the following steps are carried out: by drying the LY coal in advance to a moisture content of about 55% as described above, the adhesion of the LY coal is relatively weak, and the LY coal is easily fluidized.

(embodiment 3)

Next, embodiment 3 of the present invention will be described with reference to fig. 9 to 15, but the same parts as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted, and only the differences will be described.

As shown in fig. 9, the drying device 3 of the present embodiment includes a screen classifier (classifying unit) 71 and a classified coal flow rate adjusting unit 72 in addition to the respective configurations of the drying device 1 of embodiment 1.

The screen classifier 71 classifies the dried coal W1 dried in the drying chamber 11 based on the particle diameter (particle diameter) of the dried coal W1. The classifying/sieving machine 71 is provided at a connection portion between the product conveying pipe 36 and the return pipe 21. The screen classifier 71 supplies only the dry large-diameter coal (pre-dry large-diameter material) W10 having a particle diameter of not less than a reference value among the dry coal W1 to the return pipe 21. For example, the reference value is 1mm in terms of d50 (median particle diameter). For example, in the classifying/sieving machine 71, the reference value can be adjusted by selecting the size of the mesh.

The screen classifier 71 supplies only the dried small-diameter coal W11 having a particle size smaller than the reference value among the dried coals W1 to the cooling device 37. As described later, in the dry coal, the moisture content is higher in the coal having a larger particle size than in the coal having a smaller particle size.

the ratio of the dry large-diameter coal W10 to the coal supplied to the return pipe 21 by the screen classifier 71 is not limited to 100%. That is, the coal supplied to the return pipe 21 by the screen classifier 71 is basically made of the dry large-diameter coal W10, but the coal may contain the dry small-diameter coal W11.

The classifying coal flow rate adjusting unit 72 supplies the amount of the dried large diameter coal W10 at the reference ratio to the drying chamber 11 via the return pipe 21. The graded coal flow rate adjusting portion 72 is provided at an intermediate portion of the return pipe 21. A first end of the 2 nd connecting pipe 73 is connected to the graded coal flow rate adjusting unit 72. The second end of the 2 nd connecting pipe 73 is connected to the middle of the connecting pipe 41. For example, the graded coal flow rate adjusting unit 72 can adjust the amount of the reference ratio by using a valve, not shown, that adjusts the opening degree of the return pipe 21, a valve, not shown, that adjusts the opening degree of the 2 nd connecting pipe 73, and the like. The amount of the reference ratio is appropriately set according to the material balance of the coal W3 supplied to the drying chamber 11, the dried large-diameter coal W10, the dried coal W1 obtained in the drying chamber 11, and the like.

The fractionated coal flow rate adjusting unit 72 supplies the amount of the dry large diameter coal W10 supplied to the fractionated coal flow rate adjusting unit 72 through the return pipe 21 to the 2 nd connecting pipe 73, the amount being other than the reference ratio.

The second end of the 2 nd connecting pipe 73 may be connected between the second end and the portion of the product conveying pipe 36 where the classifying/sieving machine 71 is provided.

The reference ratio is, for example, 10 to 20%.

It is also possible to try to adjust the above reference ratio while confirming the state of adhesion of coal (hereinafter referred to as "mixed coal") obtained by mixing the coal W3 with the dry large-diameter coal W10 in the drying chamber 11. However, for example, the reference ratio can be appropriately set by evaluating the repose angle (the maximum angle at which the slope on which the mixed coal is deposited is stable without collapsing) of the mixed coal.

For example, Carr is known to classify the angle of repose according to the flow characteristics (Carr, R.L. "Evaluating flow properties of solids" chem.Eng.1965; 72: p.163-168). This classification was made by classifying the degree of fluidity into 7 grades so as to be extremely good, … …, slightly poor, and extremely poor, corresponding to the angle of repose. In this classification, the degree of fluidity ranges from extremely good to slightly poor at a repose angle of 0 ° to 55 °.

By adjusting the reference ratio so that the repose angle of the mixed coal is 0 ° to 55 °, the fluidity of the mixed coal can be improved, and the mixed coal can be prevented from adhering to the drying chamber 11.

Here, classification of water contained in LY coal will be described with reference to fig. 10. The water content of the typical LY coal is 50 to 60% (hereinafter, "%", and hereinafter, all means% by weight). In making fig. 10, reference is made to the following documents.

Japan energy society, "science and technology of Coal-future energy connection", Corona D.J. Allardic "The Water in Brown Coal Chapter 3"

In a state where the water contained in (a) is bulk water (bulk water), water V is present in macroscopic gaps S1 such as between the plurality of coal particles W15. The moisture content in the coal particles W15 in this state was about 40% or more.

When the moisture content in the coal particles W15 is less than about 40%, the water V in the gap S1 evaporates, and the water V remains in the gap S2 and at positions S3 and S4, which will be described later.

In the state where the water contained in (b) is capillary condensed water, condensed water V is present in the gap S2 formed in the capillary W16 of the coal particle W15. The moisture content of the coal particles W15 in this state is about 15 to 40%.

When the moisture content in the coal particles W15 is less than about 15%, the water V in the gap S2 evaporates, and the water V remains at positions S3 and S4, which will be described later.

In the state where the water-containing layer (c) contains a plurality of layers of water, water V at position S3 held by weak hydrogen bonds is present in a layer (not shown) of water adsorbed on the surface of the coal particles W15 as a single layer. The moisture content in the coal particles W15 in this state is about 7 to 15%. The image in the state (c) is, for example, an image in which the range R3, which is the surface of the coal particle W15, is enlarged in the state (b).

When the water content in the coal particles W15 becomes less than about 7%, the water V at the position S3 evaporates, and the water V at the position S4 described later remains.

In the state where the contained water of (d) is a single layer of water, there are oxygen-containing functional groups W18 on the surface of the coal particles W15, and water V at the position S4 held by single layer adsorption. The moisture content in the coal particles W15 in this state was less than about 7%. The image in the state (d) is, for example, an image in which the range R4, which is the boundary between the surface of the coal particle W15 and the water V held by the weak hydrogen bond, is enlarged in the state (c).

As the moisture in the coal particles W15 evaporates in this manner, the coal particles W15 are crushed (pulverized) and the particle size of the coal particles W15 is reduced.

Next, a drying method of the present embodiment using the drying device 3 configured as described above will be described.

The dried coal W1 obtained in the 3 rd chamber 16 of the drying chamber 11 is conveyed through the product conveying pipe 36 and supplied to the classifying and sieving machine 71. The screen classifier 71 supplies the dry large-diameter coal W10 out of the dry coal W1 to the classified coal flow rate adjusting unit 72 on the downstream side of the return pipe 21, and supplies the dry small-diameter coal W11 to the cooling device 37.

The classified coal flow rate adjusting unit 72 supplies a reference proportion of the dry large-diameter coal W10 supplied from the screen classifier 71 into the 1 st chamber 12 of the drying chamber 11 via the return pipe 21.

The classified coal flow rate adjusting unit 72 supplies the amount of the dry large-diameter coal W10 other than the standard ratio to the 2 nd connecting pipe 73. The dry large-diameter coal W10 supplied to the 2 nd connecting pipe 73 is joined to the powder of the coal W3 recovered by the dust collecting device 40 and flowing through the connecting pipe 41 and the dry small-diameter coal W11 classified by the sieve classifier 71 to form the product coal W7.

on the other hand, the dried large-diameter coal W10 of the reference ratio supplied into the 1 st chamber 12 is further fluidized and dried in the 1 st chamber 12 to become fluidized coal W2. The dried large diameter coal W10 contained a larger amount of water than the dried small diameter coal W11. Therefore, the temperature is less likely to rise when the large-diameter coal W10 is heated than when the small-diameter coal W11 is heated by the heat of vaporization of water in the coal. Further, by adjusting the amount of the dry large-diameter coal W10 supplied into the 1 st chamber 12 by the classifying coal flow rate adjusting unit 72, it is possible to more effectively adjust the temperature of the dry large-diameter coal W10 and the like heated in the drying chamber 11 while suppressing a decrease in the production amount of the product coal W7 due to an excessive recirculation amount.

In the drying device 1 of embodiment 1, since the dried coal W1 dried in the drying chamber 11 is returned to the drying chamber 11 again, a part of the dried coal W1 may be dried in the drying chamber 11 a plurality of times. Since the drying device 3 of the present embodiment includes the screen classifier 71, the return of the dried coal to the drying chamber 11 can be suppressed.

(verification of relationship between particle diameter of coal and proportion of moisture contained in coal in laboratory level test)

In the laboratory level test (laboratory test), LY coal as lignite was used as coal. The initial moisture proportion of the coal was 60%. The measurement of the particle size distribution of the coal and the drying of the coal by a constant temperature bath at a temperature of 107 ℃ were alternately repeated. The moisture content in the dried coal was reduced in the order of 55%, 45%, 35%, 30%, 18%, and 7%. Further, a sample having a moisture content of 64% was prepared by adding water to coal having an initial moisture content of 60%.

Fig. 11 shows changes in the cumulative ratio of coal with respect to particle size in each moisture ratio of coal. In fig. 11, the horizontal axis represents the particle diameter of coal, and the vertical axis represents the cumulative proportion of coal. From fig. 11, the average particle diameter (intersection with line L16 representing d50) in each moisture ratio can be obtained.

Fig. 12 shows the change in the moisture ratio of coal relative to the average particle size of coal. In fig. 12, the horizontal axis represents the moisture content of coal, and the vertical axis represents the average particle size of coal. Fig. 12 shows a range Ra indicating the state of the bulk water. Similarly, a range Rb indicating the state of capillary condensate, a range Rc indicating the state of multi-layer water, and a range Rd indicating the state of single-layer water are shown.

From the coal to which water has been added to the initial coal, there is a region R6 where the average particle size decreases as the moisture content decreases. In the range of the water content ratio less than that of the region R6, in the range of the water content ratio of 30-60%, even if the water content ratio is reduced, the region R7 with the average grain diameter of 1.8-2.0 mm is approximately constant exists. In the range where the moisture content is smaller than that in the region R7, there is a region R8 where the average particle diameter becomes smaller as the moisture content becomes smaller.

As described above, as the moisture content in the coal decreases, the average particle diameter decreases without increasing.

As is clear from FIG. 12, the average particle diameter of coal having a moisture content of 20% was about 1.5 mm. For example, when 1.5mm is used as the reference value of the particle size classified by the sieve classifier 71, about 50% of the dried coal having a moisture content of 20% or less can be removed.

FIG. 13 shows the change in the ratio of the undersize mass (weight) of 0.6mm or less to the moisture content of coal. The undersize ratio of 0.6mm or less means a ratio of the mass of the coal having an outer diameter of 0.6mm or less and passing through the screen to the total mass of the coal subjected to screening. In FIG. 13, the horizontal axis represents the moisture content of coal, and the vertical axis represents the undersize mass ratio of 0.6mm or less. Fig. 13 shows the ranges Ra to Rd described above.

From the coal to which water has been added to the coal having a moisture content of about 55%, there is a region R10 in which the undersize mass ratio of 0.6mm or less becomes larger as the moisture content becomes smaller. In the range where the moisture ratio is smaller than that of the region R10, there is a region R11 where the mass ratio under the sieve of 0.6mm or less is approximately constant at about 30% even if the moisture ratio is smaller. In the range where the moisture proportion is smaller than that in the region R11, there is a region R12 where the undersize mass ratio of 0.6mm or less becomes larger as the moisture proportion becomes smaller.

As described above, as the moisture content in the coal decreases, the undersize mass ratio of 0.6mm or less increases without decreasing.

(verification in bench test)

The test was carried out using a drying apparatus as a bench test apparatus capable of handling 500kg of coal per hour. Lignite having an initial moisture proportion of 60% was dried to an average moisture proportion of 20%, and the particle size distribution was measured.

Fig. 14 shows the experimental results when lignite having a moisture content of 60% was used. In fig. 14, the horizontal axis represents the particle diameter of lignite, and the vertical axis represents the cumulative proportion of lignite. The symbol "o" in the figure indicates the result of each experiment. For example, the cumulative proportion of lignite having a particle diameter of 1.4mm is 27%.

Fig. 15 shows the experimental results in the case of using brown coal dried to an average moisture content of 20%. The horizontal axis and the like of fig. 15 are the same as those of fig. 14. For example, the cumulative proportion of lignite having a particle diameter of 1.4mm is 54%.

That is, when the moisture content in the lignite is small in comparison between before and after drying the lignite, the particle size of the lignite is small.

Table 1 shows the results of obtaining the ratio of particle size of 1.5mm or more and the average particle size of lignite dried to an average moisture ratio of 20% and lignite having a moisture ratio of 60%.

The reason why the term "average moisture content" is given in table 1 is that, as described later, the moisture content is determined for each particle diameter range in lignite dried to an average moisture content of 20%.

[ TABLE 1 ]

	Average moisture ratio (%)	The ratio (%) of particle diameter of 1.5mm or less	average particle diameter (d50) (mm)
				Initial coal	60	27.7	2.7
Dried coal	20	54.9	1.1

The lignite having a water content of 60% had a particle size of 1.5mm or less of 27.7% and an average particle size (d50) of 2.7 mm. The lignite dried so that the average moisture content was 20% had a particle size of 54.9% or less at a particle size of 1.5mm or less and an average particle size (d50) of 1.1 mm. By reducing the moisture ratio, the average particle diameter is thereby reduced to a value of about 41% (1.1/2.7).

In this way, when the lignite is dried, the proportion of smaller particle size increases, and the average particle size decreases.

Further, table 2 shows the results of obtaining the water content ratio in the lignite having a particle size of 1.5mm or less and the lignite having a particle size of 5.0mm or more with respect to the lignite dried to an average water content of 20%.

[ TABLE 2 ]

Moisture proportion of dried lignite

Particle diameter of 1.5mm or less (%)	The particle diameter is 5.0mm or more (%)
		17.6	24.0

The moisture content in the brown coal having a particle size of 1.5mm or less was 17.6%, and the moisture content in the brown coal having a particle size of 5.0mm or more was 24.0%.

In this way, even in the same lignite, the proportion of water contained in lignite having a large particle diameter is larger than the proportion of water contained in lignite having a small particle diameter.

For example, in the brown coal dried to an average moisture content of 20%, the proportion of particles having a diameter of 1.5mm or less is 54.9%. When the lignite dried to an average moisture ratio of 20% is classified using a mesh of 1.5mm and the lignite remaining on the screen is used, about 55% of the lignite dried to a moisture ratio of 20% or less can be removed.

As described above, according to the drying device 3 and the drying method of the present embodiment, the coal can be uniformly dried regardless of the amount of moisture contained in the coal and the amount of coal to be processed.

Further, the drying device 3 includes a screen classifier 71. The inventor finds that: in the dried coal W1, the lignite having a large particle size contains a larger amount of water than the lignite having a small particle size. When the proportion of the contained moisture is small, the temperature of the dried coal W1 is likely to rise when the dried coal W1 is heated. Therefore, the moisture content in the dried large-diameter coal W10 can be prevented from decreasing and the temperature for drying the large-diameter coal W10 can be prevented from becoming too high.

The drying device 3 includes a classified coal flow rate adjusting unit 72. This makes it possible to adjust the ratio of the dried large-diameter coal W10 to fluidized coal W2, suppress a decrease in the production amount of product coal W7 due to an excessive recirculation amount, and more effectively adjust the temperature of the dried large-diameter coal W10 and the like.

In the present embodiment, the classifying unit is a screen classifier 71. However, the classifying portion is not limited to this, and may be a dry classifier such as a cyclone separator or a fluidized bed.

The drying device 3 may not include the classifying coal flow rate adjusting unit 72, for example, when the amount of the large diameter coal W10 to be dried is small.

While embodiments 1 to 3 of the present invention have been described in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and modifications, combinations, deletions, and the like of the configurations are also included without departing from the scope of the present invention. Furthermore, it is needless to say that the configurations described in the embodiments can be used in combination as appropriate.

For example, in embodiments 1 to 3, the object to be dried is coal, but the object to be dried is not limited thereto, and may be sludge or the like.

Description of the symbols

1. 2, 3: a drying device; 11. 51: a drying chamber; 12: a 1 st chamber (fluidizing chamber); 13. 15: a separator; 13a, 15 a: a through hole; 14: 2 nd chamber (mixing chamber); 16: a 3 rd chamber; 17: a dispersion plate; 17 a: a communicating hole; 21: a return pipe (predryed material supply unit); 27: a drying gas generating device; 28: a gas chamber for drying; 26. 63: a fluidizing section; 31: a supply hopper (dried material supply unit); 36: product conveying piping; 37: a cooling device; 39: a steam piping; 40: a dust collecting device; 71: a screen classifier (classifying section); 72: a graded coal flow rate adjusting section; w1: drying coal (predried); w2: fluidized coal (fluidized predried); w3: coal (dried material); w6: drying with a gas; w7: producing coal; w8: a humidified gas; w10: drying the large diameter coal (predrying the large diameter material).