CN112154296A - Drying device and drying method - Google Patents

Drying device and drying method Download PDF

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Publication number
CN112154296A
CN112154296A CN201980031638.2A CN201980031638A CN112154296A CN 112154296 A CN112154296 A CN 112154296A CN 201980031638 A CN201980031638 A CN 201980031638A CN 112154296 A CN112154296 A CN 112154296A
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China
Prior art keywords
drying
dried
drying chambers
chambers
heating
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Granted
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CN201980031638.2A
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Chinese (zh)
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CN112154296B (en
Inventor
关本贤一
小菅克志
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Nippon Steel Engineering Co Ltd
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Nippon Steel and Sumikin Engineering Co Ltd
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Publication of CN112154296A publication Critical patent/CN112154296A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/10—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by fluid currents, e.g. issuing from a nozzle, e.g. pneumatic, flash, vortex or entrainment dryers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
    • F26B3/08—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
    • F26B3/08—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed
    • F26B3/084—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed with heat exchange taking place in the fluidised bed, e.g. combined direct and indirect heat exchange

Abstract

The present invention relates to a drying apparatus and a drying method. The drying device is provided with: a plurality of drying chambers arranged in a row along a conveying direction of the object to be dried; a partition that divides the drying chambers adjacent to each other in the conveying direction and communicates the drying chambers adjacent to each other in the conveying direction through the through hole; a dried object supply unit configured to supply a dried object into the drying chamber at an upstream end in the transport direction; a direct heating unit that directly heats the object to be dried in the plurality of drying chambers with a heating gas; an indirect heating unit that indirectly heats the object to be dried in the plurality of drying chambers; a detection unit for detecting the temperature of the object to be dried; and a control unit that adjusts the amount of heat applied by the indirect heating unit to the drying object in the plurality of drying chambers based on the detection result of the detection unit, and that adjusts the amount of heat applied by the indirect heating unit to the plurality of drying chambers such that the temperature of the drying object in the plurality of drying chambers is lower than a temperature threshold value.

Description

Drying device and drying method
Technical Field
The present invention relates to a drying apparatus and a drying method.
This application is based on Japanese application No. 2018-094350 filed in Japan at 5/16/2018 and claims priority, and this content is incorporated by reference into this application.
Background
In recent years, studies have been made to efficiently use low-quality coal (dried material) (hereinafter, referred to as low-quality coal) such as brown coal or subbituminous coal, which has a large storage amount but a large water content and a low calorific value, as a fuel. For example, the following methods were developed: after the low-quality coal is dried by a fluidized bed type drying apparatus (hereinafter, referred to as a fluidized bed drying apparatus) to remove moisture (dehydration), the dried low-quality coal is used in a power generation facility or the like.
In the fluidized bed drying apparatus, in order to appropriately dry the low-quality coal, it is important to appropriately control the residence time of the low-quality coal. For example, in patent document 1, a partition plate (partition member) is provided in a fluidized bed drying apparatus to divide the inside of the fluidized bed drying apparatus into a plurality of drying chambers. Each partition plate has a passage opening through which low-quality coal can pass. The area of the passage opening can be adjusted by the adjusting plate. The residence time of the low-quality coal in each drying chamber is controlled by adjusting the area of the passage opening.
In the fluidized bed drying apparatus disclosed in patent document 2, the rotation speed of the rotary valve at the outlet of the drying apparatus is adjusted based on information on the bed height detected by the moisture sensor for detecting the moisture content of the low-quality coal and the bed height sensor for detecting the bed height of the fluidized bed. Thus, the bed height in the drying device is adjusted so that the low-quality coal has an appropriate moisture content (retention time).
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2013-108699
Patent document 2: japanese laid-open patent publication No. 2015-017742
Disclosure of Invention
Problems to be solved by the invention
However, the inventors have found the following: even if the retention time of low-quality coal and the bed height of the fluidized bed are detected and controlled as in the drying devices of patent documents 1 and 2, volatile gas is released from the coal when the coal is oxidized, and the material of the coal may change.
The present invention has been made in view of the above problems, and an object thereof is to provide a drying apparatus and a drying method capable of drying an object to be dried while suppressing a change in material 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.
The drying device of the present invention is a drying device for drying an object to be dried containing moisture, the drying device including: a plurality of drying chambers arranged in a row along a conveying direction in which the object to be dried is conveyed; a partition that divides each of a pair of the drying chambers adjacent to each other in the conveying direction among the plurality of drying chambers, and that communicates each of the pair of the drying chambers adjacent to each other in the conveying direction through a through hole formed in the partition; a dried object supply unit configured to supply the dried object into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers; a direct heating unit that directly heats the object to be dried in each of the plurality of drying chambers with a heating gas to fluidize the object to be dried; an indirect heating unit that indirectly heats the object to be dried in each of the plurality of drying chambers; a detection unit that detects the temperature of the object to be dried in each of the plurality of drying chambers; and a control unit that adjusts an amount of heat applied to the drying object in the plurality of drying chambers by the indirect heating unit based on a detection result of the detection unit, wherein the control unit adjusts the amount of heat applied to the plurality of drying chambers by the indirect heating unit such that a temperature of the drying object in each of the plurality of drying chambers detected by the detection unit is lower than a predetermined threshold value that suppresses generation of a volatile gas from the drying object, and the indirect heating unit includes: a heat transfer pipe extending in a direction intersecting the conveyance direction and through which a heating medium flows; and an adjusting valve capable of adjusting a flow rate of the heating medium flowing in the heat transfer pipe by adjusting an opening degree, wherein the control unit controls the adjusting valve to maximize the opening degree of the adjusting valve of the indirect heating unit that heats the object to be dried in the drying chamber in which only the object to be dried in a constant-speed drying state is stored, to close the adjusting valve of the indirect heating unit that heats the object to be dried in the drying chamber in which only the object to be dried in a deceleration drying state is stored, and to adjust the adjusting valve of the indirect heating unit that heats the object to be dried in the drying chamber in which the object to be dried in the constant-speed drying state and the object to be dried in the deceleration drying state are stored to a predetermined opening degree.
The drying method of the present invention is a drying method for drying an object to be dried containing moisture, characterized in that the object to be dried is supplied into one of a plurality of drying chambers arranged in a row along a transport direction in which the object to be dried is transported, the drying chambers being provided with a partition that divides each of a pair of the drying chambers adjacent in the transport direction and communicates with each other in the pair of the drying chambers adjacent in the transport direction through a through hole formed in the partition, the object to be dried in each of the plurality of drying chambers is fluidized by directly heating the object to be dried in each of the plurality of drying chambers with a heating gas, the object to be dried in each of the plurality of drying chambers is indirectly heated, and a heating amount for indirectly heating the object to be dried is adjusted using an adjustment valve capable of adjusting an opening degree, the opening degree of the regulating valve is set to the maximum when the object to be dried in the drying chamber accommodating only the object to be dried in a constant-speed drying state is indirectly heated, the regulating valve is closed when the object to be dried in the drying chamber accommodating only the object to be dried in a decelerated drying state is indirectly heated, and the regulating valve is regulated to a predetermined opening degree when the object to be dried in the drying chamber accommodating the object to be dried in a constant-speed drying state and the object to be dried in the drying chamber accommodating the object to be dried in a decelerated drying state respectively is indirectly heated.
According to these inventions, when the object to be dried is conveyed toward the downstream side in the conveying direction between the plurality of drying chambers through the through-holes of the partition, the object to be dried is fluidized by being directly heated by the heating gas and is further indirectly heated. Since the pair of drying chambers adjacent to each other in the conveying direction are partitioned by the partition, the drying object is dried while keeping the quality of the drying object constant in each drying chamber.
At this time, the heating amount for indirectly heating the object to be dried is adjusted so that the temperature of the object to be dried in each of the plurality of drying chambers becomes equal to or lower than the temperature threshold value. Therefore, the release of the volatile gas from the object to be dried can be suppressed, and the object to be dried can be dried while suppressing the change in the material of the object to be dried.
In addition, in the object to be dried in the constant-speed drying state, even if the amount of heating is increased, the amount of water evaporated from the surface of the object to be dried is increased and the temperature of the object to be dried is hard to be increased. Since the drying object in the speed-reduction drying state is less likely to have moisture evaporated from the surface of the drying object and the temperature of the drying object is likely to be high, the heating by the indirect heating section is stopped by closing the regulating valve, and the temperature increase of the drying object can be suppressed. In a drying chamber in which an object to be dried in a constant-speed drying state and an object to be dried in a deceleration drying state are respectively accommodated, the object to be dried is appropriately heated by adjusting an adjusting valve to a predetermined opening degree.
Accordingly, the object to be dried can be efficiently and indirectly heated by the case where the object to be dried stored in the drying chamber is in only the constant-speed drying state, the case where the object to be dried is in only the deceleration drying state, and the case where both the constant-speed drying state and the deceleration drying state exist.
Another drying apparatus according to the present invention is a drying apparatus for drying an object to be dried containing moisture, the drying apparatus including: a plurality of drying chambers arranged in a row along a conveying direction in which the object to be dried is conveyed; a partition that divides each of the pair of drying chambers adjacent to each other in the conveying direction among the plurality of drying chambers, and that communicates each of the pair of drying chambers adjacent to each other in the conveying direction through a through hole formed in the partition; a dried object supply unit configured to supply the dried object into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers; a direct heating unit that directly heats the object to be dried in each of the plurality of drying chambers with a heating gas to fluidize the object to be dried; an indirect heating unit that indirectly heats the object to be dried in each of the plurality of drying chambers; a detection unit that detects the temperature of the object to be dried in each of the plurality of drying chambers; and a control unit configured to adjust an amount of heat applied to the drying object in the plurality of drying chambers by the indirect heating unit based on a detection result of the detection unit, wherein the control unit adjusts the amount of heat applied to the drying chambers by the indirect heating unit such that a temperature of the drying object in each of the plurality of drying chambers detected by the detection unit is lower than a temperature threshold value, which is a predetermined threshold value for suppressing generation of a volatile gas from the drying object, and wherein the control unit adjusts the amount of heat applied to the drying object in each of the plurality of drying chambers by the indirect heating unit when all of the drying objects in the plurality of drying chambers are in a constant-speed drying state.
Further, another drying method of the present invention is a drying method for drying an object to be dried containing moisture, characterized in that the object to be dried is supplied into one of a plurality of drying chambers arranged in line along a conveyance direction in which the object to be dried is conveyed, the drying chambers being provided with a partition that divides each of a pair of the drying chambers adjacent in the conveyance direction and communicates with each other in the pair of the drying chambers adjacent in the conveyance direction through a through hole formed in the partition, the object to be dried in each of the plurality of drying chambers is fluidized by directly heating the object to be dried in each of the plurality of drying chambers with a heating gas, the object to be dried in each of the plurality of drying chambers is indirectly heated, and a heating amount for indirectly heating the object to be dried is adjusted, the temperature of the drying object in each of the plurality of drying chambers is set to be lower than a predetermined threshold value that suppresses generation of volatile gas from the drying object, and the amount of heat of the drying object in each of the plurality of drying chambers is adjusted by indirectly heating the drying object when all the drying objects in the plurality of drying chambers are in a constant-speed drying state.
According to these inventions, when the object to be dried is conveyed toward the downstream side in the conveying direction between the plurality of drying chambers through the through-holes of the partition, the object to be dried is fluidized by being directly heated by the heating gas and is further indirectly heated. Since the pair of drying chambers adjacent to each other in the conveying direction are partitioned by the partition, the drying object is dried while keeping the quality of the drying object constant in each drying chamber.
At this time, the heating amount for indirectly heating the object to be dried is adjusted so that the temperature of the object to be dried in each of the plurality of drying chambers becomes equal to or lower than the temperature threshold value. Therefore, the release of the volatile gas from the object to be dried can be suppressed, and the object to be dried can be dried while suppressing the change in the material of the object to be dried.
Further, since the drying object in the decelerated drying state is not present in the plurality of drying chambers, the heating amount of the drying object in each of the plurality of drying chambers can be adjusted to a desired amount by the indirect heating unit.
Another drying apparatus according to the present invention is a drying apparatus for drying an object to be dried containing moisture, the drying apparatus including: a plurality of drying chambers arranged in a row along a conveying direction in which the object to be dried is conveyed; a partition that divides each of a pair of the drying chambers adjacent to each other in the conveying direction among the plurality of drying chambers, and that communicates each of the pair of the drying chambers adjacent to each other in the conveying direction through a through hole formed in the partition; a dried object supply unit configured to supply the dried object into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers; a direct heating unit that directly heats the object to be dried in each of the plurality of drying chambers with a heating gas to fluidize the object to be dried; an indirect heating unit that indirectly heats the object to be dried in each of the plurality of drying chambers; a detection unit that detects the temperature of the object to be dried in each of the plurality of drying chambers; and a control unit configured to adjust an amount of heat applied to the drying object in the plurality of drying chambers by the indirect heating unit based on a detection result of the detection unit, wherein the control unit adjusts the amount of heat applied to the drying chambers by the indirect heating unit such that a temperature of the drying object in each of the plurality of drying chambers detected by the detection unit is lower than a predetermined threshold value that suppresses generation of volatile gas from the drying object, and wherein the control unit adjusts the amount of heat applied to the drying object in a deceleration drying state by the indirect heating unit when a part of the drying object in the plurality of drying chambers is in a constant-speed drying state and another part of the drying object in the plurality of drying chambers is in a deceleration drying state.
Further, another drying method of the present invention is a drying method for drying an object to be dried containing moisture, characterized in that the object to be dried is supplied into one of a plurality of drying chambers arranged in line along a conveyance direction in which the object to be dried is conveyed, the drying chambers being provided with a partition that divides each of a pair of the drying chambers adjacent in the conveyance direction and communicates with each other in the pair of the drying chambers adjacent in the conveyance direction through a through hole formed in the partition, the object to be dried in each of the plurality of drying chambers is fluidized by directly heating the object to be dried in each of the plurality of drying chambers with a heating gas, the object to be dried in each of the plurality of drying chambers is indirectly heated, and a heating amount for indirectly heating the object to be dried is adjusted, the heating amount of the drying object in the decelerated drying state is adjusted by indirectly heating the drying object in a case where a part of the drying object in the plurality of drying chambers is in a constant-speed drying state and another part of the drying object in the plurality of drying chambers is in a decelerated drying state so that the temperature of the drying object in each of the plurality of drying chambers is lower than a predetermined threshold value that suppresses generation of volatile gas from the drying object.
According to these inventions, when the object to be dried is conveyed toward the downstream side in the conveying direction between the plurality of drying chambers through the through-holes of the partition, the object to be dried is fluidized by being directly heated by the heating gas and is further indirectly heated. Since the pair of drying chambers adjacent to each other in the conveying direction are partitioned by the partition, the drying object is dried while keeping the quality of the drying object constant in each drying chamber.
At this time, the heating amount for indirectly heating the object to be dried is adjusted so that the temperature of the object to be dried in each of the plurality of drying chambers becomes equal to or lower than the temperature threshold value. Therefore, the release of the volatile gas from the object to be dried can be suppressed, and the object to be dried can be dried while suppressing the change in the material of the object to be dried.
In addition, in the object to be dried in the constant-speed drying state, even if the amount of heating is increased, the amount of water evaporated from the surface of the object to be dried is increased, and the temperature of the object to be dried is hard to be increased. Thus, for example, the object to be dried in the constant-speed drying state is heated by the maximum heating amount, while the object to be dried in the deceleration drying state is adjusted in the heating amount, and both the objects to be dried can be heated efficiently.
In the drying device, the indirect heating unit may include: a heat transfer pipe extending in a direction intersecting the conveyance direction and through which a heating medium flows; and an adjusting valve capable of adjusting the flow rate of the heating medium flowing in the heat transfer pipe by adjusting the opening degree, and controlled by the control unit.
According to the present invention, the indirect heating unit can be simply configured by the heat transfer pipe and the regulating valve.
In the drying device, the oxygen concentration of the heated gas may be lower than the oxygen concentration of air.
According to the present invention, the object to be dried is less likely to be oxidized by the heating gas than when air is used as the heating gas. Therefore, the temperature threshold can be increased as compared with the temperature threshold in the case of using air as the heating gas, and the control of the drying device becomes easy.
In the drying device, the detection unit may include a moisture sensor that detects a moisture content of the object to be dried or a temperature sensor that detects a temperature in the plurality of drying chambers, and the detection unit may detect the temperature of the object to be dried based on a detection result of the moisture sensor or a detection result of the temperature sensor.
According to the present invention, the detection unit can detect the temperature of the object to be dried based on the detection result of the moisture sensor or the detection result of the temperature sensor.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the drying apparatus and the drying method of the present invention, the drying object can be dried while suppressing the change in the material of the drying object.
Drawings
Fig. 1 is a partially broken overall view showing a schematic configuration of a drying apparatus according to embodiment 1 of the present invention.
Fig. 2 is a vertical cross section showing measurement points of the respective sensors of the drying apparatus.
Fig. 3 is a vertical cross section showing the measurement points of the respective sensors of the drying apparatus in a direction different from that of fig. 2.
Fig. 4 is an overall view showing an outline of the configuration of the fluidized bed drying apparatus used in the experiment.
Fig. 5 is a graph illustrating a drying curve of coal obtained by an experiment.
Fig. 6 is a graph showing the results of measuring the concentration of CO gas generated from coal with respect to the temperature of coal.
Fig. 7 is a graph showing the measurement results of the heating amount by the direct heating section, the heat exchange amount by the indirect heating section, and the temperature of the coal in each drying chamber of the drying apparatus of the example.
Fig. 8 is a graph showing the measurement results of the heating amount by the direct heating section, the heat exchange amount by the indirect heating section, and the temperature of the coal in each drying chamber of the drying apparatus of the example.
Detailed Description
Hereinafter, an embodiment of the drying apparatus according to the present invention will be described with reference to fig. 1 to 8.
As shown in fig. 1, the drying apparatus 1 of the present embodiment is an apparatus for continuously drying coal (drying target) W1 containing moisture. Coal W1 is coal having a high water content such as brown coal.
The drying device 1 includes a plurality of drying chambers 11A, 11B, 11C, and 11D, separators 16A, 16B, and 16C, a coal supply unit (dried object supply unit) 21, a direct heating unit 26, an indirect heating unit 36, a detection unit 51 (see fig. 2), and a control unit 66.
Hereinafter, the drying chambers 11A, 11B, 11C, and 11D are also simply referred to as drying chambers 11A to 11D. The same applies to the separators 16A, 16B, 16C, the later-described dispersion plates 12A, 12B, 12C, 12D, and the like. The detection section 51 is not shown in fig. 1.
The drying apparatus 1 includes 4 drying chambers 11A to 11D. The drying chambers 11A to 11D are arranged in series along the conveying direction in which the coal W1 is conveyed in the drying chambers 11A to 11D. The conveying direction is, for example, a linear direction substantially along the horizontal plane, and is a direction slightly inclined with respect to the horizontal plane gradually downward toward the downstream side in the conveying direction. The conveying direction may be a direction curved in a circumferential direction around a predetermined axis or the like.
The drying chambers 11A to 11D are formed in a rectangular parallelepiped box shape. The drying chamber 11A is a drying chamber at an upstream end in the conveyance direction among the drying chambers 11A to 11D.
The bottom plates of the drying chambers 11A to 11D use dispersion plates 12A, 12B, 12C, and 12D, respectively. The dispersion plates 12A to 12D extend in the conveyance direction as a whole. The dispersion plates 12A to 12D are formed with communication holes (not shown) penetrating in the vertical direction.
The separators 16A to 16C are formed in a plate shape extending in the vertical direction. Specifically, the partition 16A partitions between the drying chambers 11A to 11D adjacent to each other in the conveying direction, i.e., between the drying chambers 11A and 11B. A through hole 17A is formed in the lower end of the separator 16A. The lower end of the through hole 17A reaches the lower end of the separator 16A. The through-hole 17A communicates the drying chamber 11A and the drying chamber 11B adjacent to each other in the conveying direction.
Likewise, the partition 16B divides between the drying chambers 11B and 11C adjacent in the conveying direction. The through hole 17B formed in the lower end portion of the partition 16B allows the drying chamber 11B and the drying chamber 11C adjacent to each other in the conveying direction to communicate with each other. The partition 16C partitions between the drying chambers 11C and 11D adjacent in the conveying direction. The through hole 17C formed in the lower end portion of the partition 16C allows the drying chamber 11C and the drying chamber 11D adjacent to each other in the conveying direction to communicate with each other.
The number of drying chambers provided in the drying apparatus 1 is not particularly limited as long as it is a plurality of chambers. The number of drying chambers provided in the drying apparatus 1 may be 2, 3, or 5 or more.
The coal supply portion 21 is formed in a square tubular shape having an axis extending in the vertical direction, for example. The lower end of the coal supply portion 21 is fixed to a side plate of the drying chamber 11A on the opposite side to the drying chamber 11B. The internal space of the coal supply unit 21 communicates with the inside of the drying chamber 11A. The coal supply unit 21 supplies coal W1 disposed in the internal space of the coal supply unit 21 into the drying chamber 11A.
A coal discharge portion 22 is fixed to a side plate of the drying chamber 11D on the opposite side to the drying chamber 11C. The coal discharge unit 22 conveys the coal W1 dried in the drying chamber 11D, i.e., the dried coal (dry coal) W2, to the outside of the drying chamber 11D.
Exhaust ports 18A, 18B, 18C, and 18D are formed in the ceiling of the drying chambers 11A to 11D, respectively. Exhaust gas W9 containing air W6 and the like described later is discharged from the exhaust ports 18A to 18D and is sent through the duct 23.
The exhaust gas W9 sent through the duct 23 is used to recover the scattered coal W10 by the bag filter 24. The exhaust gas W9 from which the scattered coal W10 was recovered was discharged to the atmosphere from the exhaust tower 25. The scattered coal W10 collected by the bag filter 24 is mixed with the dry coal W2 delivered to the outside from the coal discharge unit 22.
The direct heating unit 26 includes a blower 27, a preheater 28, and gas chambers 29A, 29B, 29C, and 29D.
The blower 27 sends air (heated air) W6 outside the drying device 1 toward the preheater 28 at a predetermined flow rate. The preheater 28 heats the air W6 sent from the preheater 28 by the steam W7 or the like. The air W6 heated by the preheater 28 is sent to the gas chambers 29A to 29D through the distribution pipe 30.
The gas chambers 29A to 29D are disposed below the drying chambers 11A to 11D, and are attached to the dispersion plates 12A to 12D of the drying chambers 11A to 11D, respectively. The air W6 sent into the gas chamber 29A flows upward through the communication holes of the dispersion plate 12A and is supplied into the drying chamber 11A. The coal W1 in the drying chamber 11A is fluidized by the air W6 supplied into the drying chamber 11A. The air W6 sent into the gas chambers 29B to 29D is also supplied into the drying chambers 11B to 11D, respectively.
The direct heating section 26 directly heats the coal W1 in the drying chambers 11A to 11D with air W6 to fluidize the coal W1. The fluidized bed is formed by the fluidized coal W1.
The indirect heating unit 36 includes a steam supply source 37, heat transfer pipe assemblies 38A, 38B, 38C, and 38D, and flow rate control valves (control valves) 39A, 39B, 39C, and 39D.
The steam supply source 37 is connected to an end of the main pipe 41. The steam supply source 37 supplies steam (heating medium) using waste heat to the main pipe 41, for example.
The heat transfer pipe assembly 38A includes a plurality of heat transfer pipes 42A. The plurality of heat transfer pipes 42A extend, for example, in a direction intersecting the conveyance direction and in a direction along a horizontal plane.
The plurality of heat transfer tubes 42A are arranged in a staggered manner when viewed in the direction in which the plurality of heat transfer tubes 42A extend. The end portions of the plurality of heat transfer tubes 42A are connected to each other by, for example, a manifold not shown. The plurality of heat transfer pipes 42A are connected to the main pipe 41 via the distribution pipe 44A. The water vapor supplied from the water vapor supply source 37 flows into the plurality of heat transfer tubes 42A through the main pipe 41 and the distribution pipe 44A.
The heat transfer pipe aggregate 38A is disposed in a lower portion in the drying chamber 11A. In the example shown in fig. 1, almost no gap is formed between the heat pipe aggregate 38A and the dispersion plate 12A, and the center portion of the heat pipe aggregate 38A in the vertical direction and the upper end of the through hole 17A coincide with each other in the vertical direction.
As shown in fig. 2, a gap may be formed between the heat exchanger tube aggregate 38A and the dispersion plate 12A in the vertical direction. In this example, the lower end portion of the heat exchanger tube assembly 38A is arranged above the upper end of the through hole 17A.
The number of the heat transfer tubes 42A included in the heat transfer tube aggregate 38A is not limited to a plurality of tubes, and may be 1 tube.
As shown in fig. 1, the heat exchanger tube assemblies 38B to 38D are configured and arranged in the same manner as the heat exchanger tube assembly 38A. That is, the heat exchanger tube assemblies 38B to 38D include a plurality of heat exchanger tubes 42B, 42C, and 42D, respectively.
The plurality of heat transfer pipes 42B, the plurality of heat transfer pipes 42C, and the plurality of heat transfer pipes 42D are connected to the main pipe 41 via the distribution pipe 44B, the distribution pipe 44C, and the distribution pipe 44D, respectively.
The flow rate adjustment valve 39A is provided in the distribution pipe 44A. Although not shown, the flow rate control valve 39A includes, for example, a body and a needle valve.
The main body is formed with an opening through which water vapor flows. The needle valve is movable relative to the opening in a reciprocating manner in a predetermined direction. When the needle valve moves to one side of the body in a predetermined direction and comes into contact with the peripheral edge of the opening of the body, the needle valve completely closes the opening. At this time, the opening degree of the flow rate adjustment valve 39A is minimized, and the flow rate adjustment valve 39A is in a closed state. No water vapor flows in the distribution pipe 44A.
On the other hand, as the needle valve moves toward the other side in the predetermined direction with respect to the body, the proportion of the portion of the opening that is blocked by the needle valve gradually decreases. At this time, the opening degree of the flow rate control valve 39A gradually increases, and the steam gradually flows through the distribution pipe 44A. When the needle valve reaches the other end in the predetermined direction in the movement range of the needle valve, the opening degree of the flow rate adjustment valve 39A becomes maximum.
In this way, the flow rate control valve 39A can control the flow rate of the steam flowing through the plurality of heat transfer tubes 42A by controlling the opening degree.
The flow rate control valves 39B to 39D are configured in the same manner as the flow rate control valve 39A. The flow rate control valves 39B to 39D are provided in the distribution pipes 44B to 44D, respectively.
The flow rate control valves 39A to 39D are connected to the control unit 66 via cables, not shown, and controlled by the control unit 66.
The indirect heating unit 36 indirectly heats the coal W1 in the drying chambers 11A to 11D via the heat transfer pipes 42A to 42D.
As shown in fig. 2 and 3, the detection unit 51 includes, for example, the 1 st temperature sensors (temperature sensors) 52A, 52B, 52C, and 52D, the 2 nd temperature sensors (temperature sensors) 53A, 53B, 53C, and 53D, the 3 rd temperature sensors (temperature sensors) 54A, 54B, 54C, and 54D, the 1 st pressure sensors 55A, 55B, 55C, and 55D, the 2 nd pressure sensors 56A, 56B, 56C, and 56D, and the 3 rd pressure sensors 57A, 57B, 57C, and 57D.
The 1 st temperature sensor 52A and the 1 st pressure sensor 55A detect the temperature and the pressure at a measurement point P1A located immediately above the heat transfer pipe aggregate 38A in the drying chamber 11A, respectively. When the coal W1 fluidized in the drying chamber 11A to form a fluidized bed, the measurement point P1A was located in the upper end of the fluidized bed. The 1 st temperature sensor 52A and the 1 st pressure sensor 55A detect the temperature of the coal W1 (the temperature in the drying chamber 11A) at the measurement point P1A and the pressure in the drying chamber 11A, respectively.
The 2 nd temperature sensor 53A and the 2 nd pressure sensor 56A detect the temperature and the pressure at the measurement point P2A located between the ceiling of the drying chamber 11A and the upper end of the fluidized bed of the coal W1, respectively.
The 3 rd pressure sensor 57A measures the pressure at a measurement point P3A (see fig. 3) located between the heat transfer pipe aggregate 38A and the dispersion plate 12A in the drying chamber 11A. The 3 rd temperature sensor 54A measures the temperature at a measurement point P4A located in the gas chamber 29A.
The 1 st temperature sensors 52B to 52D and the 1 st pressure sensors 55B to 55D are configured in the same manner as the 1 st temperature sensor 52A and the 1 st pressure sensor 55A, and detect the temperatures and pressures at the measurement points P1B to P1D in the drying chambers 11B to 11D, respectively. The 1 st temperature sensors 52A to 52D constitute 1 group of temperature sensors corresponding to the drying chambers 11A to 11D.
The 2 nd temperature sensors 53B to 53D and the 2 nd pressure sensors 56B to 56D are configured in the same manner as the 2 nd temperature sensor 53A and the 2 nd pressure sensor 56A, and detect the temperature of the coal W1 and the pressure in the drying chambers 11B to 11D at the measurement points P2B to P2D in the drying chambers 11B to 11D, respectively.
The 3 rd pressure sensors 57B to 57D are configured in the same manner as the 3 rd pressure sensor 57A, and detect the pressures at the measurement points P3B to P3D in the drying chambers 11B to 11D, respectively. The 3 rd temperature sensors 54B to 54D are configured similarly to the 3 rd temperature sensor 54A, and detect the temperatures of the measurement points P4B to P4D in the gas chamber 29A, respectively.
The detection unit 51 preferably further includes moisture sensors 59 and 60 shown in fig. 2.
The moisture sensor 59 detects the moisture content of the coal W1 in the coal supply portion 21. The moisture sensor 60 detects the moisture content of the coal W1 in the coal discharge portion 22.
The temperature sensors 52A to 52D, 53A to 53D, and 54A to 54D, the pressure sensors 55A to 55D, 56A to 56D, and 56A to 56D (hereinafter, simply referred to as the temperature sensors 52A to 52D, the pressure sensors 55A to 55D, and the like), and the moisture sensors 59 and 60 are connected to the control unit 66, and send the detection results to the control unit 66.
Although not shown, the control unit 66 includes a control circuit and a memory. The control circuit includes a CPU (Central Processing Unit) and the like. The memory is, for example, a ram (random Access memory). The memory stores a control program for controlling the control circuit, a predetermined temperature threshold value, and the like. The temperature threshold is a temperature at which generation of CO gas from the coal is suppressed when the temperature of the coal is lower than the temperature. The temperature threshold may also be a temperature at which CO gas is not generated from the coal when the temperature of the coal is below the temperature.
The temperature threshold is determined in correspondence with the oxygen concentration of the heating gas. For example, in the case where the heating gas is air (oxygen concentration is 21%), the temperature threshold is 60 ℃. In the case where the heating gas is an exhaust gas having an oxygen concentration of 10% or less, the temperature threshold is about 90 ℃.
The control unit 66 adjusts the opening degrees of the flow rate adjustment valves 39A to 39D based on the detection result of the detection unit 51, thereby adjusting the amount of heat of the coal W1 in the drying chambers 11A to 11D by the indirect heating unit 36.
The drying device 1 may not include the flow rate control valves 39A and 39B, and the control unit 66 may be configured to control only the amount of heat of the coal W1 in the drying chambers 11C and 11D by the indirect heating unit 36. In this manner, the target of the adjustment of the heating amount by the indirect heating unit 36 is not limited to the coal W1 in the 4 drying chambers 11A to 11D, and may be the coal W1 in 1 to 3 drying chambers on the downstream side in the conveying direction.
Here, before describing the drying method of the present embodiment, several experimental results performed in advance will be described.
(Experimental result 1)
The following experiments were performed: a drying curve when a low Yang coal (hereinafter, referred to as LY coal), which is brown coal, was dried was obtained.
1. Conditions of the experiment
Table 1 shows the properties of the coal used.
[ Table 1]
Figure BDA0002771492550000121
Figure BDA0002771492550000122
The analyses and measurements in table 1 were performed according to the following specifications.
Industrial analysis: JIS M8812-coal and coke-industrial analysis method
Elemental analysis: JIS M8819-coal and coke-elemental analysis method by device analysis apparatus
JIS M8813-coal and coke-element analysis method
Measurement of total calorific value: JIS M8814-methods for measuring total calorific value of coals and cokes based on bomb calorimeter and methods for calculating lower calorific value
For example, as a result of industrial analysis, the moisture content (TM) of coal was 56.8 wt%.
As a result of elemental analysis, the content of carbon (C) in the coal was 70.2daf wt%.
An experiment was performed using the batch-type fluidized bed drying apparatus 101 shown in fig. 4. The bottom plate of the drying chamber 11 uses a dispersion plate 12. A gas chamber 29 is installed on the dispersion plate 12 of the drying chamber 11. A heat transfer pipe assembly 38 including a plurality of heat transfer pipes 42 is disposed above the dispersion plate 12 in the drying chamber 11. The air W6 is sent by the blower 27, and is supplied into the gas room 29 after being heated by the preheater 28. The preheater 28 is of the heater type and heats the air W6 to a maximum of 120 ℃. The flow rate of the air W6 supplied into the drying chamber 11 is controlled by bypassing a part of the air W6 sent from the blower 27.
The coal W1 fed into the drying chamber 11 is directly heated by the air W6, fluidized on the dispersion plate 12, and forms a fluidized bed.
Oil as a heat medium is contained in the oil tank 102. This oil is supplied to the oil pump 103 and flows through the plurality of heat transfer tubes 42 of the heat transfer tube assembly 38. The coal W1 fluidized on the dispersion plate 12 is indirectly heated by the oil through the plurality of heat transfer pipes 42. The exhaust gas W9 discharged from the drying chamber 11 is released into the atmosphere after the scattered coal W10 is collected by the bag filter 24.
The coal is periodically taken out from a sampling port, not shown, in the lower part of the fluidized bed, and the moisture content in the coal during drying is measured.
The amount of coal treated by the fluidized bed drying apparatus 101 was set to 6 kg/batch. The temperature of hot air used for drying LY coal is 90 ℃, and the flow rate is 100Nm3The flow rate of the hot air in the fluidized bed was 1.1 m/s.
Fig. 5 shows the results of determining the drying curve of coal. The horizontal axis of fig. 5 represents the drying time (min.)) of the coal. The left vertical axis represents the temperature (. degree. C.) of the coal and the water content (%) of the coal. The vertical axis on the right side represents the water content of coal. The water content is defined as the mass of water (kg-H) contained in the coal2O) relative to drying the coalThe ratio of 1kg of dry coal (kg-dry).
The line L1, whose legend is labeled "good" represents the temperature of the coal. The line L2 marked with a "Δ" indicates the moisture content in the coal. Line L3, with the legend labeled "□", represents the water content of the coal.
LY coal was in a constant-rate-dried state because the temperature of the coal was constant until the moisture content in the coal became about 25%, and it was found that coal having a moisture content in the range R1 of 25% to 60%. In the case where the drying chamber is of a continuous type, the range in which the coal in a constant-speed drying state is stored in the drying chamber is a constant-speed drying section. In the coal in the constant-rate drying state, even if the amount of heating is increased, the amount of water evaporated from the surface of the coal increases and the temperature of the coal is hard to increase, and the temperature of the coal is substantially constant regardless of the amount of heating.
On the other hand, when the moisture content in the coal is 25% or less, the temperature of the coal gradually increases, and therefore it is found that the coal having the moisture content in the range R2 of 25% or less is in a decelerated dry state. In the case where the drying chamber is of a continuous type, the range in which the coal in a speed-reduction drying state is stored in the drying chamber is a speed-reduction drying section. In the case of the coal in the reduced velocity drying state, even if the amount of heating is increased, the amount of water evaporated from the surface of the coal is less likely to increase, and the temperature of the coal is likely to increase.
The temperature of the coal at the boundary between the constant-rate drying state and the deceleration drying state may be set, for example, in the relationship between the drying time of the coal and the temperature of the coal, between a point at which the temperature starts to increase by exceeding +10 ℃ with respect to the temperature of the coal at the start of drying and a point at which the temperature starts to increase by exceeding the temperature of the coal at the start of drying.
By detecting the temperature of the coal in this manner, it is possible to determine which of the constant-speed drying state and the deceleration drying state the coal dried by heating is in.
(Experimental result 2)
The amount of carbon monoxide (CO) gas (volatile gas) generated from the coal was measured with respect to the temperature of the coal.
1. Conditions of the experiment
The gas generated from the coal was subjected to a compositional analysis at a predetermined temperature of 20 ℃ intervals from the normal temperature (60 ℃) to 180 ℃ of the coal.
(1) A25 g sample of coal which had been previously vacuum-dried was put into a ceramic tube, and both ends of the tube were sandwiched by coal wool.
(2) After the inside of the tube was sufficiently purged with nitrogen gas, the temperature of the coal was raised to a predetermined temperature while flowing air at 100 ml/min. Gases generated from coal were collected and subjected to compositional analysis. Gas chromatography (GC-TCD method) was used in the component analysis.
(3) As a sample, Adaro coal (hereinafter, referred to as "E coal") was used as subbituminous coal, and LY coal was used as lignite.
2. Results of the experiment
Fig. 6 shows the measurement results. The horizontal axis of fig. 6 represents the temperature (c) of coal, and the horizontal axis represents the concentration (ppm) of CO gas. The line L6, labeled "●", represents the experimental results for E coals, and the line L7, labeled ". diamond-solid" for instances, represents the experimental results for LY coals.
In LY coal, it is known that CO gas is generated from coal when the temperature of the coal becomes 60 ℃. Similarly, in the case of the E coal, when the temperature of the coal becomes 60 ℃ or higher, CO gas is generated from the coal. The generation of gas from coal means: pyrolysis occurs in the coal and the coal begins to undergo oxidation reactions.
More specifically, the temperature threshold of the coal for suppressing the generation of CO gas from the coal can be set to a temperature detected at 5ppm to 20ppm of CO gas, preferably at 5ppm to 15ppm, and more preferably at 5ppm to 10 ppm. From the above, the temperature threshold of the coal for suppressing the generation of CO gas from the coal may be set to 60 to 80 ℃, and in the example, 60 ℃.
Next, a drying method of the present embodiment for drying the coal W1 will be described.
First, in the supply step (step S1), coal W1 is supplied into the drying chamber 11A. In the supply step S1, the coal supply unit 21 may be used. When the supply process S1 ends, the process proceeds to step S3.
Next, in the direct heating step (step S3), the coal W1 is fluidized by directly heating the coal W1 in each of the drying chambers 11A to 11D with air W6. For supplying the air W6 into the drying chambers 11A to 11D, for example, the blower 27, the preheater 28, and the gas chambers 29A to 29D as the direct heating unit 26 can be used.
The coal W1 fluidized in the drying chamber 11A is fed to the drying chamber 11B through the through-holes 17A of the partition 16A. Similarly, the coal W1 fluidized in the drying chambers 11B and 11C is fed to the drying chambers 11C and 11D through the through holes 17B and 17C of the partitions 16B and 16C, respectively. The coal W1 dried in the drying chambers 11A to 11D is sent to the outside from the coal discharge portion 22.
The temperature sensors 52A to 52D, the pressure sensors 55A to 55D, and the moisture sensors 59 and 60 of the detection unit 51 periodically transmit the detection results of the temperature, the pressure, and the moisture content to the control unit 66. The control unit 66 determines which of the constant-speed drying state and the deceleration drying state each of the drying chambers 11A to 11D is in, for example, based on the detection results of the temperature of the coal W1 by the 1 st temperature sensors 52A to 52D.
For example, the control unit 66 determines the constant-speed drying state and the deceleration drying state of the coal W1 as follows. That is, only the coal W1 in the constant-speed drying state is stored in the drying chamber 11A. The coal W1 in a constant-speed drying state and the coal W1 in a speed-reduction drying state are stored in the drying chamber 11B. In the drying chambers 11C and 11D, only the coal W1 in the decelerated and dried state is stored.
When the process S3 is directly heated, the process proceeds to step S5.
Next, in the indirect heating step (step S5), the coal W1 in each of the drying chambers 11A to 11D is indirectly heated. For indirectly heating the coal W1, for example, the steam supply source 37, the heat transfer pipe assemblies 38A to 38D, and the flow rate control valves 39A to 39D, which are the indirect heating unit 36, may be used. When the indirect heating process S5 ends, the process proceeds to step S7.
Next, in the heating amount adjusting step (step S7), the control unit 66 adjusts the amount of heat applied to the coal W1 in the drying chambers 11A to 11D by the indirect heating unit 36 so that the temperature of the coal W1 in the drying chambers 11A to 11D becomes lower than the temperature threshold value. The temperature of the coal W1 in each of the drying chambers 11A to 11D may be any value such as the values detected by the 1 st temperature sensors 52A to 52D, the 2 nd temperature sensors 53A to 53, and the 3 rd temperature sensors 54A to 54D of the detection unit 51, and the average value of these values.
In the heating amount adjusting step S7, the control unit 66 maximizes the opening degree of the flow rate adjusting valve 39A of the indirect heating unit 36 that heats the coal W1 in the drying chamber 11A. The flow rate control valve 39B of the indirect heating section 36 that heats the coal W1 in the drying chamber 11B is adjusted to a predetermined opening degree. The predetermined opening degree is an opening degree between a maximum opening degree and a minimum opening degree. The flow rate control valves 39C, 39D of the indirect heating section 36 that heats the coal W1 in the drying chambers 11C, 11D are closed.
That is, in the drying chamber 11A in which only the coal W1 in the constant-speed drying state is stored, the coal W1 is dried at once by using both the direct heating unit 26 and the indirect heating unit 36. On the other hand, in the drying chambers 11C and 11D in which only the coal W1 in the speed-reduction dried state is stored, the direct heating section 26 is used, but the heating amount by the indirect heating section 36 is reduced to lower the temperature of the coal W1 to the temperature threshold value.
In the present embodiment, the supply step S1, the direct heating step S3, the indirect heating step S5, and the heating amount adjustment step S7 are performed simultaneously.
The exhaust gas W9 discharged from the exhaust ports 18A to 18D of the drying chambers 11A to 11D is sent by the duct 23. The exhaust gas W9 is obtained by recovering the scattered coal W10 from the bag filter 24 and is released to the atmosphere from the exhaust tower 25. The scattered coal W10 collected by the bag filter 24 is mixed with the dry coal W2 delivered to the outside from the coal discharge unit 22.
As described above, according to the drying device 1 and the drying method of the present embodiment, when the coal W1 is conveyed toward the downstream side in the conveyance direction between the drying chambers 11A to 11D through the through holes 17A to 17C of the partitions 16A to 16C, the coal W1 is directly heated by the air W6 to be fluidized, and is further indirectly heated by the steam. Since the pair of drying chambers 11A to 11D adjacent to each other in the conveying direction are partitioned by the partitions 16A to 16C, the coal W1 is dried while the quality of the coal W1 is kept constant in each of the drying chambers 11A to 11D.
At this time, the heating amount of the indirect heating coal W1 is adjusted so that the temperature of the coal W1 in each of the drying chambers 11A to 11D becomes equal to or lower than the temperature threshold value. Therefore, emission of volatile gas such as CO gas from the coal W1 can be suppressed, and changes in the material quality of the coal W1 can be suppressed.
Since the indirect heating unit 36 includes the plurality of heat transfer tubes 42A to 42D and the flow rate control valves 39A to 39D, the indirect heating unit 36 can be simply configured by the plurality of heat transfer tubes 42A to 42D and the flow rate control valves 39A to 39D.
The controller 66 maximizes the opening degree of the flow rate control valve 39A in the drying chamber 11A in which only the coal W1 in the constant-speed drying state is stored. Further, the flow rate control valve 39B for heating the coal W1 in the drying chamber 11B in which the coal W1 in the constant-speed drying state and the coal W1 in the speed-reduction drying state are respectively stored is adjusted to a predetermined opening degree. The flow rate control valves 39C, 39D for heating the coal W1 in the drying chambers 11C, 11D in which only the coal W1 in the decelerated and dried state is stored are closed.
In the coal W1 in the constant-speed drying state, even if the amount of heating is increased, the amount of water evaporated from the surface of the coal W1 is increased, and the temperature of the coal W1 is hard to increase, so that the coal W1 can be heated with a large amount of heating, and the coal W1 can be dried safely and efficiently in the drying chamber 11A. Since the coal W1 in the speed-reduction dried state is difficult to evaporate water from the surface of the coal W1 and the temperature of the coal W1 is likely to increase, the heating of the indirect heating section 36 is stopped by closing the flow rate control valves 39C and 39D, and the temperature increase of the coal W1 can be suppressed. The coal W1 is appropriately heated by adjusting the control valve to a predetermined opening degree in the drying chamber 11B containing the coal W1 in the constant-speed drying state and the coal W1 in the speed-reduction drying state.
In this way, the coal W1 can be efficiently heated by the indirect heating unit 36 when the coal W1 stored in the drying chambers 11A to 11D is in the constant-speed drying state only, in the deceleration drying state only, or in both the constant-speed drying state and the deceleration drying state.
The detection unit 51 includes the 1 st temperature sensors 52A to 52D that detect the temperatures in the drying chambers 11A to 11D, and the detection unit 51 detects the temperature of the coal W1 based on the detection result of the 1 st temperature sensor 52A. Therefore, the detection unit 51 can detect the temperature of the coal W1 based on the detection results of the 1 st temperature sensors 52A to 52D.
The drying apparatus 1 and the drying method according to the present embodiment can be variously modified in configuration and process as described below.
As the heating gas, exhaust gas W9 may be used instead of the air W6. The exhaust gas W9 is preferably an exhaust gas obtained by burning coal or the like in air. The oxygen concentration of the exhaust gas W9 is lower than that of air. The oxygen concentration of the exhaust gas W9 is, for example, 10% or less. With this configuration, the coal W1 is less likely to be oxidized by the heating gas than when air W6 is used as the heating gas. Therefore, the temperature threshold can be increased as compared with the temperature threshold in the case where air is used as the heating gas, and the control of the drying device 1 becomes easy.
For example, the following is described in "the relationship between the initial spontaneous combustion of coal and the oxygen concentration in air" (the agency of the field, other 2 names, journal of the japan mining association, 1969): although it is also related to the type of coal, the CO gas is generated in proportion to about 0.4 to 0.6 power of the oxygen concentration. As can be seen from this description, as the oxygen concentration of the heating gas becomes lower, CO gas gradually becomes less likely to be generated, and the temperature threshold can be increased.
When all the coals W1 in the drying chambers 11A to 11D are in the constant-speed drying state, the control unit 66 may adjust the heating amount of the coal W1 in each of the drying chambers 11A to 11D by the indirect heating unit 36. Since the coal W1 in the speed-reduction dried state is not present in the drying chambers 11A to 11D, the heating amount of the coal W1 in the drying chambers 11A to 11D can be adjusted to a desired amount by the indirect heating section 36.
When a part of the coal W1 in the drying chambers 11A to 11D is in the constant-speed drying state and another part of the coal W1 in the drying chambers 11A to 11D is in the speed-reduction drying state, the control unit 66 may adjust the heating amount of the coal W1 in the speed-reduction drying state by the indirect heating unit 36. For example, the coal W1 in the constant-speed drying state is heated by the maximum heating amount, while the coal W1 in the deceleration drying state is heated by a desired amount, whereby two kinds of coals W1 can be efficiently heated.
While one embodiment of the present invention has been described above with reference to the drawings, the specific configuration is not limited to the embodiment, and modifications, combinations, deletions, and the like of the configuration are included within the scope not departing from the spirit of the present invention.
For example, in the above embodiment, the detection unit 51 may not include the 1 st pressure sensors 55A to 55D, the 2 nd pressure sensors 56A to 56D, and the 3 rd pressure sensors 57A to 57D. In this case, the detection unit 51 may include at least 1 of the 3 sets of temperature sensors, i.e., the 1 st temperature sensors 52A to 52D, the 2 nd temperature sensors 53A to 53D, and the 3 rd temperature sensors 54A to 54D.
The drying device 1 may be provided with moisture sensors in the drying chambers 11A to 11D instead of the 1 st temperature sensors 52A to 52D, and may detect the temperature of the coal W1 in the drying chambers 11A to 11D based on the detection results of these moisture sensors.
The drying object is coal, but the drying object is not limited to this, and may be sludge or the like.
The present invention will be described in more detail by specifically illustrating examples thereof, but the present invention is not limited to the examples below.
In the drying apparatus shown in FIG. 1, E-coal was used as the coal, the treatment rate of the coal was 500kg/h, and the flow rate of air W6 as the heating gas was 2300Nm3/h, and an experiment was performed.
In the operating condition 1, the temperature of the air W6 was set to 120 ℃, and the temperatures of the heat transfer pipes 42A to 42D were set to 100 ℃. Fig. 7 shows the measurement results of the amount of heating by the direct heating section 26, the amount of heating by the indirect heating section 36, and the temperature of the coal W1 of the coal W1 in the drying chambers 11A to 11D of the drying device. The horizontal axis of fig. 7 represents each drying chamber. The left vertical axis represents the heating amount by the direct heating unit 26 and the indirect heating unit 36, and the right vertical axis represents the temperature of the coal W1. The lower part of the bar graph shows the amount of heating by the indirect heating unit 36, and the upper part thereof shows the amount of heating by the direct heating unit 26 in an integrated manner. The broken line in the figure shows the measurement result of the temperature of coal W1.
The upper part of the bar chart in fig. 7 shows the moisture content of the coal W1 in the drying chambers 11A to 11D.
In this example, the flow rate control valves 39C and 39D in the drying chambers 11C and 11D are closed to stop the heating of the indirect heating unit 36. As a result, the temperature of the coal W1 in the drying chambers 11B to 11D can be lowered to 60 ℃ and the moisture content of the coal W1 can be finally 10% or less (7%).
In operating condition 2, the temperature of the air W6 is set to 80 ℃, the temperatures of the heat transfer tubes 42A and 42B are set to 100 ℃, and the temperatures of the heat transfer tubes 42C and 42D are set to normal temperatures. Fig. 8 shows the measurement results of the amount of heating by the direct heating section 26, the amount of heating by the indirect heating section 36, and the temperature of the coal W1 in the drying chambers 11A to 11D of the drying device.
The temperature of the coal W1 in the drying chambers 11A to 11D continuously increased, but finally the temperature of the coal W1 in the drying chamber 11D was lower than 60 ℃.
Further, the operation conditions 1 and 2 are examples of the drying apparatus.
Industrial applicability
The drying apparatus and the drying method of the present embodiment can be suitably used for drying an object to be dried by suppressing a change in material of the object to be dried.
Description of the symbols
1: a drying device; 11A, 11B, 11C, 11D: a drying chamber; 16A, 16B, 16C: a separator; 17A, 17B, 17C: a through hole; 21: a coal supply unit (dried material supply unit); 26: a direct heating section; 36: an indirect heating section; 39A, 39B, 39C, 39D: a flow rate adjusting valve (adjusting valve); 42A, 42B, 42C, 42D: a heat transfer tube; 51: a detection unit; 52A, 52B, 52C, 52D: 1 st temperature sensor (temperature sensor); 53A, 53B, 53C, 53D: 2 nd temperature sensor (temperature sensor); 54A, 54B, 54C, 54D: a 3 rd temperature sensor (temperature sensor); 66: a control unit; w1: coal (dried material); w6: air (heating gas).

Claims (9)

1. A drying device for drying an object to be dried containing moisture, comprising:
a plurality of drying chambers arranged in a row along a conveying direction in which the object to be dried is conveyed;
a partition that divides each of a pair of the drying chambers adjacent to each other in the conveying direction among the plurality of drying chambers, and that communicates each of the pair of the drying chambers adjacent to each other in the conveying direction through a through hole formed in the partition;
a dried object supply unit configured to supply the dried object into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers;
a direct heating unit that directly heats the object to be dried in each of the plurality of drying chambers with a heating gas to fluidize the object to be dried;
an indirect heating unit that indirectly heats the object to be dried in each of the plurality of drying chambers;
a detection unit that detects the temperature of the object to be dried in each of the plurality of drying chambers; and
a control unit for adjusting the amount of heat of the object to be dried in the plurality of drying chambers by the indirect heating unit based on the detection result of the detection unit,
the control unit adjusts the amount of heat applied to the plurality of drying chambers by the indirect heating unit so that the temperature of the object to be dried in each of the plurality of drying chambers detected by the detection unit becomes lower than a predetermined threshold value that suppresses generation of volatile gas from the object to be dried,
the indirect heating unit includes:
a heat transfer pipe extending in a direction intersecting the conveyance direction and through which a heating medium flows; and
an adjusting valve capable of adjusting the flow rate of the heating medium flowing in the heat transfer pipe by adjusting the opening degree and controlled by the control unit,
the control part is used for controlling the operation of the motor,
the opening degree of the control valve of the indirect heating unit that heats the object to be dried in the drying chamber in which only the object to be dried in a constant-speed drying state is stored is set to be maximum,
closing the control valve of the indirect heating unit that heats the drying object in the drying chamber containing only the drying object in a decelerated and dried state,
the control valve of the indirect heating unit that heats the object to be dried in the drying chamber in which the object to be dried in the constant-speed drying state and the object to be dried in the deceleration drying state are respectively accommodated is adjusted to a predetermined opening degree.
2. A drying device for drying an object to be dried containing moisture, comprising:
a plurality of drying chambers arranged in a row along a conveying direction in which the object to be dried is conveyed;
a partition that divides each of a pair of the drying chambers adjacent to each other in the conveying direction among the plurality of drying chambers, and that communicates each of the pair of the drying chambers adjacent to each other in the conveying direction through a through hole formed in the partition;
a dried object supply unit configured to supply the dried object into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers;
a direct heating unit that directly heats the object to be dried in each of the plurality of drying chambers with a heating gas to fluidize the object to be dried;
an indirect heating unit that indirectly heats the object to be dried in each of the plurality of drying chambers;
a detection unit that detects the temperature of the object to be dried in each of the plurality of drying chambers; and
a control unit for adjusting the amount of heat of the object to be dried in the plurality of drying chambers by the indirect heating unit based on the detection result of the detection unit,
the control unit adjusts the amount of heat applied to the plurality of drying chambers by the indirect heating unit so that the temperature of the object to be dried in each of the plurality of drying chambers detected by the detection unit becomes lower than a predetermined threshold value that suppresses generation of volatile gas from the object to be dried,
in the case where all the objects to be dried in the plurality of drying chambers are in a constant-speed drying state, the control unit adjusts the amount of heat applied to the objects to be dried in each of the plurality of drying chambers by the indirect heating unit.
3. A drying device for drying an object to be dried containing moisture, comprising:
a plurality of drying chambers arranged in a row along a conveying direction in which the object to be dried is conveyed;
a partition that divides each of a pair of the drying chambers adjacent to each other in the conveying direction among the plurality of drying chambers, and that communicates each of the pair of the drying chambers adjacent to each other in the conveying direction through a through hole formed in the partition;
a dried object supply unit configured to supply the dried object into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers;
a direct heating unit that directly heats the object to be dried in each of the plurality of drying chambers with a heating gas to fluidize the object to be dried;
an indirect heating unit that indirectly heats the object to be dried in each of the plurality of drying chambers;
a detection unit that detects the temperature of the object to be dried in each of the plurality of drying chambers; and
a control unit for adjusting the amount of heat of the object to be dried in the plurality of drying chambers by the indirect heating unit based on the detection result of the detection unit,
the control unit adjusts the amount of heat applied to the plurality of drying chambers by the indirect heating unit so that the temperature of the object to be dried in each of the plurality of drying chambers detected by the detection unit becomes lower than a predetermined threshold value that suppresses generation of volatile gas from the object to be dried,
when a part of the objects to be dried in the plurality of drying chambers is in a constant-speed drying state and another part of the objects to be dried in the plurality of drying chambers is in a deceleration drying state, the control unit adjusts the heating amount of the objects to be dried in the deceleration drying state by the indirect heating unit.
4. The drying apparatus according to claim 2 or 3,
the indirect heating unit includes:
a heat transfer pipe extending in a direction intersecting the conveyance direction and through which a heating medium flows; and
and an adjusting valve capable of adjusting the flow rate of the heating medium flowing in the heat transfer pipe by adjusting the opening degree, and controlled by the control unit.
5. The drying apparatus according to any one of claims 1 to 4,
the oxygen concentration of the heated gas is lower than that of air.
6. The drying apparatus according to any one of claims 1 to 5,
the detection unit includes a moisture sensor for detecting a moisture content of the object to be dried or a temperature sensor for detecting a temperature in the plurality of drying chambers,
the detection unit detects the temperature of the object to be dried based on a detection result of the moisture sensor or a detection result of the temperature sensor.
7. A drying method for drying an object to be dried containing moisture, wherein,
supplying the object to be dried into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers arranged in line along the transport direction in which the object to be dried is transported, the partition dividing a pair of the drying chambers adjacent to each other in the transport direction among the plurality of drying chambers and communicating the pair of drying chambers adjacent to each other in the transport direction through a through hole formed in the partition,
directly heating the drying object in each of the plurality of drying chambers by a heating gas to fluidize the drying object,
indirectly heating the drying object in each of the plurality of drying chambers,
adjusting a heating amount for indirectly heating the object to be dried by using an adjusting valve capable of adjusting an opening degree so that a temperature of the object to be dried in each of the plurality of drying chambers becomes lower than a predetermined threshold value for suppressing generation of a volatile gas from the object to be dried,
when the drying object in the drying chamber only containing the drying object in a constant-speed drying state is indirectly heated, the opening degree of the regulating valve is set to be maximum,
closing the regulating valve when indirectly heating the drying object in the drying chamber containing only the drying object in a decelerated drying state,
the control valve is adjusted to a predetermined opening degree when indirectly heating the object to be dried in the drying chamber in which the object to be dried in the constant-speed drying state and the object to be dried in the deceleration drying state are respectively accommodated.
8. A drying method for drying an object to be dried containing moisture, wherein,
supplying the object to be dried into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers arranged in line along the transport direction in which the object to be dried is transported, the partition dividing a pair of the drying chambers adjacent to each other in the transport direction among the plurality of drying chambers and communicating the pair of drying chambers adjacent to each other in the transport direction through a through hole formed in the partition,
directly heating the drying object in each of the plurality of drying chambers by a heating gas to fluidize the drying object,
indirectly heating the drying object in each of the plurality of drying chambers,
adjusting a heating amount for indirectly heating the object to be dried so that a temperature of the object to be dried in each of the plurality of drying chambers becomes lower than a predetermined threshold value for suppressing generation of volatile gas from the object to be dried,
when the drying objects in the plurality of drying chambers are all in a constant-speed drying state, the heating amount of the drying objects in each of the plurality of drying chambers is adjusted by indirectly heating the drying objects.
9. A drying method for drying an object to be dried containing moisture, wherein,
supplying the object to be dried into the drying chamber at an upstream end in the transport direction among the plurality of drying chambers arranged in line along the transport direction in which the object to be dried is transported, the partition dividing a pair of the drying chambers adjacent to each other in the transport direction among the plurality of drying chambers and communicating the pair of drying chambers adjacent to each other in the transport direction through a through hole formed in the partition,
directly heating the drying object in each of the plurality of drying chambers by a heating gas to fluidize the drying object,
indirectly heating the drying object in each of the plurality of drying chambers,
adjusting a heating amount for indirectly heating the object to be dried so that a temperature of the object to be dried in each of the plurality of drying chambers becomes lower than a predetermined threshold value for suppressing generation of volatile gas from the object to be dried,
when a part of the drying objects in the plurality of drying chambers is in a constant-speed drying state and another part of the drying objects in the plurality of drying chambers is in a deceleration drying state, the heating amount of the drying objects in the deceleration drying state is adjusted by indirectly heating the drying objects.
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WO2019220720A1 (en) 2019-11-21
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