Drying device, and method of estimating moisture content

Abstract

To highly accurately estimate the moisture content of slurry stored in a container.SOLUTION: A drying device 100 comprises a container 110 storing slurry, a heating device 170 heating the inside of the container 110, a rotation shaft 120 rotatably disposed in the container 110 to extend in the horizontal direction or in an approximately horizontal direction, one or a plurality of blades 140 attached to the rotation shaft 120, a driving device 180 rotating the rotation shaft 120, a moisture sensor 190 disposed in the container 110, and a calculation unit estimating the moisture content of the slurry according to the output value of the moisture sensor 190 during a stop period when the slurry stored in the container 110 is heated by the heating device 170 and the rotation of the rotation shaft 120 by the driving device 180 is stopped.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a drying device and a method for estimating moisture content. [Background technology]

[0002] Conventionally, sludge discharged from sewage treatment facilities has been transported to coasts, lakes, rivers, etc. and dumped in landfills. However, this has presented problems such as the difficulty of securing landfill sites and the burden it places on the environment.

[0003] Therefore, in recent years, technologies have been developed to utilize dried sludge obtained by drying sludge as biomass fuel. For example, Patent Document 1 discloses a technology in which sludge is dried in a dryer for a fixed drying time, and the dried sludge discharged from the dryer is divided into two types: one for use as biomass fuel and the other for use as a heat source for the dryer, based on the moisture content of the dried sludge. In the technology of Patent Document 1, the amount of dried sludge for use as a heat source and the amount of air supplied to the dryer are adjusted based on the moisture content of the dried sludge for use as a heat source, among the dried sludge discharged from the dryer, to maintain the moisture content of the dried sludge within a predetermined range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-199449 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional technology disclosed in the above Patent Document 1, which controls the dryer based on the moisture content of the dried sludge after it is discharged from the dryer, there is a large delay in the control of the dryer.

[0006] For this reason, there is a need to develop a technology that can estimate the moisture content of a slurry such as sludge while it is contained in a container of a dryer.

[0007] In view of these problems, the present disclosure aims to provide a drying device and a method for estimating moisture content that are capable of estimating the moisture content of a slurry contained in a container with high accuracy. [Means for solving the problem]

[0008] In order to solve the above problem, a drying device according to one embodiment of the present disclosure includes a container for storing slurry, a heating device for heating the inside of the container, a rotating shaft rotatably arranged within the container and extending horizontally or approximately horizontally, one or more blades arranged on the rotating shaft, a driving device for rotating the rotating shaft, a moisture sensor arranged within the container, and a calculation unit for estimating the moisture content of the slurry based on the output value of the moisture sensor during a stop period when the slurry stored in the container is heated by the heating device and the rotation of the rotating shaft by the driving device is stopped.

[0009] The drying device may also include a control unit that controls the drive device to switch the rotation direction of the rotating shaft between a first direction and a second direction that is opposite to the first direction, and the stop period may be an interval period between switching the rotation direction of the rotating shaft.

[0010] The calculation unit may calculate the transition of the moisture content of the slurry based on the output value of the moisture sensor during a plurality of stop periods.

[0011] The moisture sensor may be provided below the rotation axis.

[0012] The moisture sensor may be a capacitance type moisture sensor or an electrical resistance type moisture sensor.

[0013] At least a part of the slurry may be dried to form a powder.

[0014] In order to solve the above problem, one embodiment of the present disclosure provides a method for estimating the moisture content of a slurry in a drying device having a container for storing slurry, a heating device for heating the inside of the container, a rotating shaft rotatably mounted within the container and extending horizontally or approximately horizontally, one or more blades mounted on the rotating shaft, a drive device for rotating the rotating shaft, and a moisture sensor mounted within the container, the method including estimating the moisture content of the slurry based on the output value of the moisture sensor during a stop period when the slurry stored in the container is heated by the heating device and the rotation of the rotating shaft by the drive device is stopped. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to estimate the moisture content of a slurry contained in a container with high accuracy. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram illustrating a drying device according to an embodiment. [Figure 2] FIG. 2 is a block diagram illustrating an example of a functional configuration of the control device according to the embodiment. [Figure 3] FIG. 3 is a flowchart showing the process flow of the drying method according to the embodiment. [Figure 4] FIG. 4 is a flowchart showing the flow of the during-drying process according to the embodiment. [Figure 5] FIG. 5 is a first flowchart showing the flow of the during-drying process according to the first modified example. [Figure 6] FIG. 6 is a second flowchart showing the flow of the during-drying process according to the first modified example. [Figure 7] FIG. 7 is a diagram illustrating an approximation formula calculated by a calculation unit according to the first modified example. [Figure 8] FIG. 8 is a flowchart showing the flow of the during-drying process according to the second modified example. [Figure 9] FIG. 9 is a graph showing estimated values ​​and approximate expressions according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation. Elements not directly related to the present disclosure are not shown.

[0018] [Drying equipment 100] FIG. 1 is a diagram illustrating a drying apparatus 100 according to this embodiment. The drying apparatus 100 according to this embodiment dries, for example, a slurry to convert at least a portion of the slurry into powder. The slurry is a solid-liquid mixture of solids and water. Examples of the slurry include sludge and food waste generated in sewage treatment facilities, wastewater treatment facilities, mining and manufacturing facilities, agricultural and fishery facilities, food processing facilities, etc.

[0019] 1, the drying device 100 includes a container 110, a rotating shaft 120, an arm 130, a blade 140, a heating device 170, a driving device 180, a moisture sensor 190, a control device 200, and a display device 220. In FIG. 1 of this embodiment, an X-axis (horizontal direction) and a Y-axis (horizontal direction) that intersect perpendicularly are defined as shown.

[0020] The vessel 110 contains a slurry. The vessel 110 includes, for example, an outer cylinder 112 and an end plate 114. The outer cylinder 112 is, for example, a cylindrical hollow member. The outer cylinder 112 may be any hollow member, and may be, for example, a rectangular cylindrical member. The end plate 114 is a flat plate that seals openings formed at both ends of the outer cylinder 112. In this embodiment, the vessel 110 is installed, for example, so that its axial direction is horizontal (±X-axis directions in FIG. 1) or approximately horizontal. The approximately horizontal direction is a direction in which the inclination angle with respect to the horizontal direction (±X-axis directions in FIG. 1) is within a range of, for example, ±5 degrees.

[0021] A supply pipe 112a, a discharge pipe 112b, and an exhaust pipe 112c are connected to the outer cylinder 112. The supply pipe 112a is connected to the upper part of the outer cylinder 112. The slurry before drying is introduced into the container 110 through the supply pipe 112a. An on-off valve 116a is provided on the supply pipe 112a.

[0022] Discharge pipe 112b communicates with the lower part of outer cylinder 112, at approximately the center in the X-axis direction and the Y-axis direction in Figure 1. The dried powder is discharged from container 110 through discharge pipe 112b. Discharge pipe 112b is provided with an on-off valve 116b.

[0023] The exhaust pipe 112c communicates with the upper part of the outer cylinder 112, at approximately the center in the X-axis direction and the Y-axis direction in FIG. 1. A check valve 116c is provided in the exhaust pipe 112c. Steam generated by drying the slurry is exhausted to the outside through the exhaust pipe 112c.

[0024] The rotating shaft 120 is rotatably provided within the container 110. The rotating shaft 120 is provided within the container 110 so as to extend in the extension direction of the outer cylinder 112. That is, the rotating shaft 120 extends in a horizontal direction (±X-axis directions in FIG. 1) or a substantially horizontal direction. The substantially horizontal direction has an inclination angle with respect to the horizontal direction (±X-axis directions in FIG. 1) within a range of, for example, ±5 degrees. In this embodiment, the rotating shaft 120 is provided within the container 110 so that the central axis of the rotating shaft 120 substantially coincides with the central axis of the outer cylinder 112. The rotating shaft 120 is rotated in a first direction or a second direction by a driving device 180, which will be described later. In FIG. 1, arrow A indicates the first direction, and arrow B indicates the second direction.

[0025] The arms 130 extend upright from the rotating shaft 120. In this embodiment, a plurality of arms 130 are provided on the rotating shaft 120. The arms 130 are provided on the rotating shaft 120 at regular intervals in the circumferential direction of the rotating shaft 120 and in the direction in which the rotating shaft 120 extends.

[0026] One or more blades 140 are attached to the rotating shaft 120 via arms 130. In this embodiment, the blades 140 are attached to the tips of the multiple arms 130. The blades 140 are spiral-shaped flat plates that are curved in the rotation direction of the rotating shaft 120. In this embodiment, the blades 140 are attached to the arms 130 at a distance from the rotating shaft 120. The blades 140 move the slurry toward approximately the center of the rotating shaft 120 as the rotating shaft 120 rotates. In this embodiment, the blades 140 include a first blade unit 150 and a second blade unit 160.

[0027] The first blade unit 150 is provided from one end of the rotary shaft 120 (the left side in FIG. 1 ) to approximately the center of the rotary shaft 120. In this embodiment, the first blade unit 150 includes a first outer blade 152 and a first inner blade 154. The first inner blade 154 is provided closer to the rotary shaft 120 than the first outer blade 152. The first inner blade 154 has a spiral winding direction opposite to that of the first outer blade 152.

[0028] The second blade unit 160 is provided from the other end of the rotary shaft 120 (the right side in FIG. 1 ) to approximately the center of the rotary shaft 120. In this embodiment, the second blade unit 160 includes a second outer blade 162 and a second inner blade 164, similar to the first blade unit 150. The second outer blade 162 has a spiral winding direction opposite to that of the first outer blade 152. The second inner blade 164 is provided closer to the rotary shaft 120 than the second outer blade 162. The second inner blade 164 has a spiral winding direction opposite to that of the second outer blade 162. In other words, the first outer blade 152 and the second inner blade 164 have the same spiral winding direction. Furthermore, the first inner blade 154 and the second outer blade 162 have the same spiral winding direction.

[0029] The heating device 170 heats the inside of the container 110. The heating device 170 is, for example, an electric heater. In this embodiment, the heating device 170 heats the container 110 and the rotating shaft 120, thereby indirectly heating the slurry contained in the container 110. For ease of understanding, the heating device 170 that heats the rotating shaft 120 is not shown in FIG. 1 .

[0030] The driving device 180 rotates the rotating shaft 120. The driving device 180 includes, for example, a motor. In this embodiment, the driving device 180 rotates the rotating shaft 120 in a first direction and a second direction. The second direction is a rotation direction opposite to the first direction.

[0031] For example, when the drive device 180 rotates the rotary shaft 120 in a first direction (direction A shown in FIG. 1, counterclockwise when viewed from the +X side in FIG. 1), the first outer blade 152 of the first blade unit 150 moves the slurry in the −X axis direction (toward the left end plate 114). The first inner blade 154 of the first blade unit 150 moves the slurry in the +X axis direction (toward approximately the center of the vessel 110). Meanwhile, the second outer blade 162 of the second blade unit 160 moves the slurry in the +X axis direction (toward the right end plate 114). The second inner blade 164 of the second blade unit 160 moves the slurry in the −X axis direction (toward approximately the center of the vessel 110).

[0032] Furthermore, when the driving device 180 rotates the rotating shaft 120 in a second direction (direction B shown in FIG. 1, clockwise when viewed from the +X side in FIG. 1), the first outer blade 152 of the first blade unit 150 moves the slurry in the +X axis direction (toward approximately the center of the container 110). The first inner blade 154 of the first blade unit 150 moves the slurry in the -X axis direction (toward the left end plate 114). Meanwhile, the second outer blade 162 of the second blade unit 160 moves the slurry in the -X axis direction (toward the approximately center of the container 110). The second inner blade 164 of the second blade unit 160 moves the slurry in the +X axis direction (toward the right end plate 114).

[0033] The control unit 214, which will be described later, controls the drive device 180 to alternately switch the rotation direction of the rotary shaft 120 between the first direction and the second direction. This reverses the flow direction of the slurry caused by the blades 140. Therefore, the blades 140 can efficiently agitate the slurry.

[0034] This increases the frequency of contact between the container 110 heated by the heating device 170 and the slurry, and between the rotating shaft 120 heated by the heating device 170 and the slurry. This allows the drying device 100 to efficiently dry the slurry.

[0035] The moisture sensor 190 is provided inside the container 110. The moisture sensor 190 is, for example, a capacitance-type moisture sensor or an electrical resistance-type moisture sensor.

[0036] The moisture sensor 190 is provided, for example, below the rotation axis 120 inside the container 110. In this embodiment, the moisture sensor 190 is provided on the end plate 114. For example, the moisture sensor 190 is provided between the point 112d of the end plate 114 that is located vertically lowest and the center of the end plate 114. Hereinafter, the point 112d of the end plate 114 that is located vertically lowest may be referred to as the "lowest point 112d."

[0037] For example, as shown in FIG. 1, if the protruding width of moisture sensor 190 (width in the ±X-axis directions in FIG. 1) is larger than the gap (clearance) between blade 140 and end plate 114, moisture sensor 190 is provided at a position closer to rotating shaft 120 than blade 140 and at a position closest to lowest point 112d. On the other hand, if the protruding width of moisture sensor 190 is smaller than the gap between blade 140 and end plate 114, moisture sensor 190 is provided at a position a predetermined distance from lowest point 112d. The predetermined distance is, for example, 10% to 20% of the shortest distance between rotating shaft 120 and lowest point 112d.

[0038] The control device 200 has one or more processors 202 and one or more memories 204 connected to the processors 202. The processor 202 includes, for example, a CPU (Central Processing Unit). The memory 204 includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM is a storage element that stores programs used by the CPU, calculation parameters, etc. The RAM is a storage element that temporarily stores data such as variables and parameters used in processing executed by the CPU.

[0039] In this embodiment, the memory 204 stores, for example, moisture content information. The moisture content information is information in which the output value of the moisture sensor 190 is associated with the measured value of the moisture content of the slurry. The moisture content information is, for example, a calibration curve. The moisture content information is stored in advance in the memory 204 by conducting a test or the like.

[0040] The control device 200 communicates with each device provided in the drying device 100, such as the on-off valve 116a, the on-off valve 116b, the heating device 170, the driving device 180, the moisture sensor 190, and the like.

[0041] 2 is a block diagram showing an example of the functional configuration of the control device 200 according to this embodiment. For example, as shown in FIG. 2, the control device 200 also functions as an acquisition unit 210, a calculation unit 212, and a control unit 214.

[0042] The acquisition unit 210 acquires output values ​​of various sensors provided in the drying device 100. The acquisition unit 210 acquires the output value of the moisture sensor 190, for example.

[0043] The calculation unit 212 estimates the moisture content of the slurry contained in the container 110 based on the output value of the moisture sensor 190. In this embodiment, the calculation unit 212 estimates the moisture content of the slurry based on the output value of the moisture sensor 190 during an interval during which the slurry is heated by the heating device 170 and the rotation of the rotating shaft 120 by the driving device 180 is stopped. Details of the processing by the calculation unit 212 will be described later.

[0044] The control unit 214 controls the operation of, for example, the on-off valves 116a and 116b, the heating device 170, the driving device 180, etc. In this embodiment, the control unit 214 controls the driving device 180 to switch the rotation direction of the rotating shaft 120 between a first direction and a second direction opposite to the first direction. During the interval period while the rotation direction of the rotating shaft 120 is switched, the rotation of the rotating shaft 120 by the driving device 180 is stopped. The interval period is, for example, 30 seconds.

[0045] 1, the display device 220 is configured with a liquid crystal display, an organic EL (Electro Luminescence) display, etc. The display device 220 displays, for example, the results of calculations by the calculation unit 212 (for example, an estimated value Res, which will be described later).

[0046] [Drying method] Next, a description will be given of a drying method using the drying device 100 according to this embodiment. Fig. 3 is a flowchart showing the process flow of the drying method according to this embodiment.

[0047] 3, the drying method according to this embodiment includes a drying start process S110, a drying in-progress process S120, and a drying end process S130. Each process will be described below.

[0048] [Drying start process S110] In the drying start process S110, for example, the on-off valve 116b is closed and the on-off valve 116a is opened in response to a control command from the control unit 214. Then, the slurry is supplied into the container 110 through the supply pipe 112a. When the supply of the slurry is completed, the on-off valve 116a is closed. Next, in response to a control command from the control unit 214, the drive device 180 starts rotating the rotating shaft 120, and heating is started by the heating device 170. Note that the rotation direction of the rotating shaft 120 may be either the first direction or the second direction. When the drying start process S110 is completed, the control unit 214 shifts the process to the drying in progress process S120.

[0049] [Drying process S120] In the during-drying process S120, the control device 200 switches the rotation direction of the rotating shaft 120 to promote drying of the slurry and estimates the moisture content of the slurry. In this embodiment, the during-drying process S120 corresponds to a method for estimating the moisture content. When the moisture content of the slurry estimated in the during-drying process S120 becomes equal to or less than a first target value Rtg1 described below, the control unit 214 proceeds to the drying termination process S130. Details of the during-drying process S120 will be described later.

[0050] [Drying end process S130] In the drying termination process S130, the on-off valve 116b is opened in response to a control command from the control unit 214. Furthermore, in response to a control command from the control unit 214, the rotation direction of the rotating shaft 120 is switched to a second direction, and the powder is collected approximately in the center of the container 110 and discharged to the outside through the discharge pipe 112b.

[0051] [Details of the S120 mid-drying process] Fig. 4 is a flowchart showing the flow of the during-drying process S120 according to this embodiment. As shown in Fig. 4, the during-drying process S120 includes a moisture content determination process S120-1, a rotation time elapse determination process S120-3, a rotation stop process S120-5, an output value acquisition process S120-7, an interval period elapse determination process S120-9, a switching process S120-11, and an estimated value calculation process S120-13. Each process will be described below.

[0052] [Moisture content determination process S120-1] In the moisture content determination process S120-1, the control unit 214 determines whether the estimated moisture content Res calculated in the estimated value calculation process S120-13 described below exceeds a first target value Rtg1. The first target value Rtg1 is determined depending on the application of the powder produced by drying the slurry with the drying apparatus 100. The first target value is, for example, 15% or more and 25% or less.

[0053] As a result, if it is determined that the estimated value Res exceeds the first target value Rtg1 (YES in S120-1), the control unit 214 proceeds to the rotation time elapse determination process S120-3. On the other hand, if it is determined that the estimated value Res does not exceed the first target value Rtg1 (NO in S120), that is, is equal to or less than the first target value Rtg1, the control unit 214 proceeds to the drying termination process S130.

[0054] If the estimated value calculation process S120-13 has not yet been performed and the estimated value Res has not yet been calculated, the control unit 214 proceeds to the rotation time elapse determination process S120-3.

[0055] [Rotation time elapse determination process S120-3] In the rotation time elapse determination process S120-3, the control unit 214 determines whether a predetermined rotation time has elapsed since the drying start process S110 or the switching process S120-11 was performed. The rotation time is, for example, 10 minutes. The control unit 214 then repeats the rotation time elapse determination process S120-3 until the rotation time has elapsed (NO in the rotation time elapse determination process S120-3), and when it determines that the rotation time has elapsed (YES in the rotation time elapse determination process S120-3), it proceeds to the rotation stop process S120-5.

[0056] [Rotation stop processing S120-5] In the rotation stop process S120-5, the control unit 214 controls the drive device 180 to stop the rotation of the rotary shaft 120.

[0057] [Output value acquisition process S120-7] In the output value acquisition process S120-7, the acquisition unit 210 acquires the output value of the moisture sensor 190. The acquisition unit 210 may acquire the output value of the moisture sensor 190 after a predetermined time has elapsed since the rotation of the rotating shaft 120 was stopped. The predetermined time is, for example, 5 seconds.

[0058] [Interval period elapsed determination process S120-9] In the interval period elapsed determination process S120-9, the control unit 214 determines whether or not the interval period has elapsed since the rotation stop process S120-5 was performed. If it is determined that the interval period has not elapsed (NO in the interval period elapsed determination process S120-9), the control unit 214 returns the process to the output value acquisition process S120-7. On the other hand, if it is determined that the interval period has elapsed (YES in the interval period elapsed determination process S120-9), the control unit 214 shifts the process to the switching process S120-11.

[0059] [Switching process S120-11] In the switching process S120-11, the control unit 214 controls the drive device 180 to switch the rotation direction of the rotating shaft 120 from the first direction to the second direction or from the second direction to the first direction, and restarts the rotation of the rotating shaft 120.

[0060] [Estimated value calculation process S120-13] In the estimated value calculation process S120-13, the calculation unit 212 calculates an estimated value Res of the moisture content of the slurry based on the output value of the moisture sensor 190 acquired in the output value acquisition process S120-7. In this embodiment, the calculation unit 212 calculates the estimated value Res of the moisture content of the slurry based on, for example, the average value of multiple output values ​​acquired within one interval period. Specifically, the calculation unit 212 refers to the moisture content information stored in the memory 204 and sets the moisture content of the slurry associated with the average value as the estimated value Res.

[0061] When the calculation unit 212 has finished calculating the estimated value Res, the control unit 214 returns the process to the moisture content determination process S120-1.

[0062] As described above, the drying apparatus 100 according to this embodiment includes a container 110 for storing slurry, a heating device 170 for heating the inside of the container 110, a rotating shaft 120 rotatably mounted within the container 110 and extending horizontally or approximately horizontally, one or more blades 140 mounted on the rotating shaft 120, a driving device 180 for rotating the rotating shaft 120, a moisture sensor 190 mounted within the container 110, and a calculation unit 212 for estimating the moisture content of the slurry based on the output value of the moisture sensor 190 during a stop period when the slurry stored in the container 110 is heated by the heating device 170 and the rotation of the rotating shaft 120 by the driving device 180 is stopped.

[0063] The inventors of the present application have found that there is a correlation between the output value of the moisture sensor 190 and the moisture content of the slurry. Therefore, the drying apparatus 100 according to the present embodiment and the method for estimating the moisture content using the same are capable of estimating the moisture content of the slurry in real time by installing the moisture sensor 190 in the container 110 that contains the slurry and estimating the moisture content of the slurry based on the output value of the moisture sensor 190.

[0064] Furthermore, while the rotating shaft 120 is rotating, the impeller 140 causes the slurry to flow vigorously within the container 110. As a result, the contact area between the sensing surface of the moisture sensor 190 and the slurry fluctuates while the rotating shaft 120 is rotating. If the contact area between the sensing surface of the moisture sensor 190 and the slurry fluctuates, the output value of the moisture sensor 190 will fluctuate even if the moisture content of the slurry is constant. As a result, variations occur in the output value of the moisture sensor 190 while the rotating shaft 120 is rotating.

[0065] On the other hand, while the rotating shaft 120 is stopped, the fluidity of the slurry is lower than when the rotating shaft 120 is rotating, and the contact area between the sensing surface of the moisture sensor 190 and the slurry hardly changes. Also, the contact area between the sensing surface of the moisture sensor 190 and the slurry increases. This stabilizes the output value of the moisture sensor 190.

[0066] Therefore, the drying apparatus 100 and the moisture content estimation method using the drying apparatus 100 according to the present embodiment estimate the moisture content of the slurry based on the output value of the moisture sensor 190 during a stop period in which the slurry contained in the container 110 is heated by the heating device 170 and the rotation of the rotary shaft 120 by the driving device 180 is stopped. Thus, the drying apparatus 100 and the moisture content estimation method using the drying apparatus 100 according to the present embodiment estimate the moisture content of the slurry based on the output value of the moisture sensor 190 during a stop period in which the output value of the moisture sensor 190 is stable. Therefore, the drying apparatus 100 and the moisture content estimation method using the drying apparatus 100 according to the present embodiment can estimate the moisture content of the slurry with high accuracy. The drying apparatus 100 and the moisture content estimation method using the drying apparatus 100 according to the present embodiment can estimate the moisture content of the slurry with high accuracy, for example, to within approximately ±10% of the actual measured value.

[0067] Furthermore, as described above, the drying apparatus 100 according to this embodiment includes the control unit 214 that controls the drive device 180 to switch the rotation direction of the rotating shaft 120 between a first direction and a second direction opposite to the first direction, and the stop period is preferably an interval period between switching the rotation direction of the rotating shaft 120. This eliminates the need for the drying apparatus 100 to provide a stop period for estimating the moisture content, and allows the drying apparatus 100 to efficiently dry the slurry while accurately estimating the moisture content of the slurry.

[0068] Furthermore, as described above, in the drying apparatus 100 according to this embodiment, the moisture sensor 190 is preferably provided below the rotating shaft 120 within the container 110. As the drying of the slurry progresses, the volume of the slurry within the container 110 decreases. However, during periods when the rotation of the rotating shaft 120 is stopped, the slurry accumulates in the lower part of the container 110 due to its own weight. Therefore, by providing the moisture sensor 190 below the rotating shaft 120 within the container 110, the drying apparatus 100 according to this embodiment can expose the sensing surface of the moisture sensor 190 to the slurry, thereby increasing the contact area between the sensing surface of the moisture sensor 190 and the slurry. Therefore, the drying apparatus 100 according to this embodiment can estimate the moisture content of the slurry with even higher accuracy.

[0069] Furthermore, in the drying apparatus 100 according to this embodiment, the heating device 170 heats the container 110. Therefore, as the drying of the slurry progresses, powder may accumulate or adhere to the lower part of the container 110. The inventors of the present application have found that the correlation between the output value of the moisture sensor 190 and the moisture content of the slurry weakens as the moisture content decreases. Therefore, by providing the moisture sensor 190 between the lowest point 112d of the container 110 and the rotation shaft 120, the drying apparatus 100 according to this embodiment can suppress contact between the sensing surface of the moisture sensor 190 and powder having a lower moisture content than the slurry, thereby enabling the moisture content of the slurry located above the powder to be estimated with higher accuracy.

[0070] As described above, in the drying apparatus 100 according to this embodiment, the moisture sensor 190 is preferably a capacitance moisture sensor or an electrical resistance moisture sensor. In the drying apparatus 100 according to this embodiment, at least a portion of the slurry is dried to form powder. Because powder reflects light, when detecting the moisture content of a slurry containing powder, an optical moisture sensor has lower detection accuracy than a capacitance moisture sensor or an electrical resistance moisture sensor. Therefore, by using a capacitance moisture sensor or an electrical resistance moisture sensor as the moisture sensor 190, the drying apparatus 100 according to this embodiment can estimate the moisture content of the slurry with higher accuracy.

[0071] [First Modification] In the embodiment described above, the calculation unit 212 estimates the moisture content of the slurry in the during-drying process S120. However, the calculation unit 212 may calculate the transition of the moisture content of the slurry based on the output value of the moisture sensor 190 during multiple stop periods.

[0072] In the during-drying process S220 according to the first modified example, the control device 200 switches the rotation direction of the rotating shaft 120 to promote drying of the slurry, estimates the moisture content of the slurry, and calculates the transition of the moisture content based on the estimated moisture content value Res. In the first modified example, the during-drying process S220 corresponds to the method for estimating the moisture content.

[0073] Fig. 5 is a first flowchart showing the flow of the during-drying process S220 according to the first modified example. Fig. 6 is a second flowchart showing the flow of the during-drying process S220 according to the first modified example.

[0074] 5 and 6, the during-drying process S220 according to the first modified example includes a time flag determination process S220-1, a remaining time determination process S220-3, a timer subtraction process S220-5, a rotation time elapse determination process S120-3, a rotation stop process S120-5, an output value acquisition process S120-7, an interval period elapse determination process S120-9, a switching process S120-11, an estimated value calculation process S120-13, a transition calculation process S220-7, a moisture content determination process S220-9, and a remaining time calculation process S220-11. Note that processes that are substantially the same as those in the during-drying process S120 according to the above embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted. The following describes the time flag determination process S220-1, remaining time determination process S220-3, timer subtraction process S220-5, transition calculation process S220-7, moisture content determination process S220-9, and remaining time calculation process S220-11, which are different from the drying process S120 according to the above embodiment.

[0075] [Time flag determination process S220-1] When the drying start process S110 is completed, the control unit 214 performs a time flag determination process S220-1. In the time flag determination process S220-1, the control unit 214 determines whether or not a time flag F, which is set in a remaining time calculation process S220-11 described below, is set to 1. As a result, if the time flag F is set to 1 (YES in the time flag determination process S220-1), the control unit 214 proceeds to a remaining time determination process S220-3. On the other hand, if the time flag F is not set to 1 (NO in the time flag determination process S220-1), the control unit 214 proceeds to a rotation time elapse determination process S120-3. The time flag F is set to zero when the drying method is started.

[0076] [Remaining time determination process S220-3] In the remaining time determination process S220-3, the control unit 214 determines whether the timer value Tr that counts the remaining time, which was set in the remaining time calculation process S220-11, is equal to or less than 0. As a result, if it is determined that the timer value Tr is equal to or less than 0 (YES in S220-3), the control unit 214 shifts the process to the drying termination process S130. On the other hand, if it is determined that the timer value Tr is not equal to or less than 0 (NO in S220-3), that is, is greater than 0, the control unit 214 shifts the process to the timer subtraction process S220-5.

[0077] [Timer subtraction process S220-5] In the timer subtraction process S220-5, the control unit 214 subtracts the value Tr of the timer that counts the remaining time, which was set in the remaining time calculation process S220-11.

[0078] [Transition calculation processing S220-7] 6, in the first modified example, when the above-described estimated value calculation process S120-13 is completed, a transition calculation process S220-7 is performed. In the transition calculation process S220-7, the calculation unit 212 calculates the transition of the moisture content of the slurry based on the output values ​​of the moisture sensor 190 over multiple interval periods. In other words, the calculation unit 212 calculates a time-series change in the moisture content of the slurry. For example, the calculation unit 212 calculates an approximation formula for the multiple estimated values ​​Res calculated in the estimated value calculation process S120-13 each time an interval period occurs.

[0079] Fig. 7 is a diagram illustrating an approximation formula calculated by the calculation unit 212 according to the first modified example. In Fig. 7, the vertical axis represents the moisture content [%], and the horizontal axis represents the drying time. Also, in Fig. 7, black diamonds represent estimated values ​​Res, and the solid line represents the approximation formula.

[0080] The calculation unit 212 calculates an estimated value Res based on the output value of the moisture sensor 190 each time an interval period occurs. As shown in FIG. 7, the estimated value Res decreases as the drying time elapses. In the first modified example, the calculation unit 212 calculates an approximation formula for the multiple estimated values ​​Res calculated each time an interval period occurs. Note that, since a new estimated value Res is calculated each time an interval period occurs, the calculation unit 212 updates the approximation formula each time the transition calculation process S220-7 is performed.

[0081] In the first modified example, the display device 220 displays a graph representing the estimated value Res and the approximate formula as shown in Fig. 7. Note that the display device 220 updates the display of the graph every time the approximation formula is updated by the calculation unit 212.

[0082] [Moisture content determination process S220-9] Returning to FIG. 6, in the moisture content determination process S220-9, the control unit 214 determines whether the moisture content estimate Res calculated in the estimate value calculation process S120-13 is equal to or less than the second target value Rtg2 and whether the time flag F is set to zero. The second target value Rtg2 is greater than the first target value Rtg1. The second target value Rtg2 is, for example, 40%. As a result, if the control unit 214 determines that the estimate Res is equal to or less than the second target value Rtg2 and the time flag F is set to zero (YES in S220-9), the control unit 214 proceeds to the remaining time calculation process S220-11. On the other hand, if the estimate Res is not equal to or less than the second target value Rtg2 or the time flag F is not set to zero (NO in S220-9), the control unit 214 proceeds to the time flag determination process S220-1 (see FIG. 5).

[0083] [Remaining time calculation process S220-11] In remaining time calculation processing S220-11, the calculation unit 212 calculates the remaining time until the moisture content of the slurry reaches the first target value Rtg1 based on the transition of the moisture content of the slurry calculated in transition calculation processing S220-7. Then, the control unit 214 sets the time flag F to 1 and sets the calculated remaining time to the value Tr of the timer that counts the remaining time. When remaining time calculation processing S220-11 is completed, the control unit 214 proceeds to time flag determination processing S220-1 (see FIG. 5).

[0084] As described above, the calculation unit 212 according to the first modified example calculates the transition of the moisture content of the slurry based on the output values ​​of the moisture sensor 190 during multiple stop periods (interval periods). As a result, the drying apparatus 100 according to the first modified example and the moisture content estimation method using the same can estimate the moisture content of the slurry with high accuracy, for example, to within about ±1% of the actual measured value.

[0085] Furthermore, in the first modified example, the display device 220 updates the display of the graph every time the approximation formula is updated by the calculation unit 212. This allows the operator of the drying device 100 to visually recognize the progress of drying of the slurry.

[0086] [Second Modification] In the above first modified example, the case where the transition calculation process S220-7 is repeatedly performed has been described. However, the transition calculation process S220-7 may be performed only once. Fig. 8 is a flowchart showing the flow of the during-drying process S220 according to the second modified example.

[0087] 8, in the second modified example, the estimated value calculation process S120-13 is performed, followed by the moisture content determination process S220-9. If the moisture content determination process S220-9 determines that the estimated value Res is equal to or less than the second target value Rtg2 and that the time flag F is set to zero (YES in S220-9), the control unit 214 proceeds to the transition calculation process S220-7.

[0088] In the transition calculation process S220-7 according to the second modified example, the calculation unit 212 calculates the transition (approximation formula) of the water content of the slurry based on the multiple estimated values ​​Res calculated in the estimated value calculation process S120-13 until the estimated value Res reaches the second target value Rtg2.

[0089] After the transition calculation process S220-7 is performed, the control unit 214 advances the process to the remaining time calculation process S220-11.

[0090] As described above, the calculation unit 212 according to the second modified example performs the transition calculation process S220-7 only once, as compared to the first modified example. As a result, the drying apparatus 100 according to the second modified example and the moisture content estimation method using the same can estimate the moisture content of the slurry with high accuracy, for example, to within about ±1% of the actual measured value, while reducing the processing load on the calculation unit 212.

[0091] [Example] An estimated value Res of the moisture content and an approximation formula for the estimated value Res were created using the above-described drying apparatus 100. In addition, the moisture content of the slurry was actually measured by taking the slurry out of the container 110 multiple times. Furthermore, the approximation formula was created based on the actual measured values ​​of the moisture content of the slurry.

[0092] Fig. 9 is a graph showing the estimated value Res and the approximation formula according to the example. In Fig. 9, the vertical axis represents the moisture content [%], and the horizontal axis represents the drying time. In Fig. 9, the black diamonds represent the estimated value Res, the solid line represents the approximation formula for the estimated value Res, and the dashed line represents the approximation formula for the actually measured value.

[0093] As shown in Figure 9, it was confirmed that the estimated value Res decreases as the drying time elapses. It was also confirmed that there is almost no difference between the approximation formula for the estimated value Res and the approximation formula for the actual measured value.

[0094] From the above results, it was confirmed that there is a strong correlation between the output value of the moisture sensor 190 and the moisture content of the slurry.

[0095] Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0096] For example, in the above embodiment, the blade 140 is provided on the rotating shaft 120 via the arm 130. However, the blade 140 may be provided directly on the rotating shaft 120.

[0097] In the above-described embodiment, the first modified example, and the second modified example, the calculation unit 212 calculates the estimated value Res based on the output value of the moisture sensor 190 each time an interval period occurs. However, the calculation unit 212 may calculate the estimated value Res based on the output value of the moisture sensor 190 each time one or more interval periods occur among a plurality of interval periods. For example, in the case of the drying apparatus 100 in which the slurry moves to one side of the container 110 when the rotating shaft 120 is rotated in a first direction and moves to the other side of the container 110 when the rotating shaft 120 is rotated in a second direction, and the moisture sensor 190 is provided on one side of the container 110, the calculation unit 212 may calculate the estimated value Res based on the output value of the moisture sensor 190 during the interval period when the rotation direction is switched from the first direction to the second direction. In this case, the acquisition section 210 does not need to acquire the output value of the moisture sensor 190 during the interval period when switching from the second direction to the first direction.

[0098] Furthermore, in the above-described embodiment, first modified example, and second modified example, the calculation unit 212 estimates the moisture content of the slurry based on the output value of the moisture sensor 190 during an interval period between switching the rotation direction of the rotating shaft 120. However, the stop period is not limited to the interval period as long as the calculation unit 212 can estimate the moisture content of the slurry based on the output value of the moisture sensor 190 during a stop period during which the slurry contained in the container 110 is heated by the heating device 170 and the rotation of the rotating shaft 120 by the driving device 180 is stopped. For example, if a stop period during which the rotation of the rotating shaft 120 is stopped is provided while the rotation direction of the rotating shaft 120 is not switched, the calculation unit 212 may estimate the moisture content of the slurry based on the output value of the moisture sensor 190 during that stop period.

[0099] In the above embodiment, the moisture sensor 190 is provided on the end plate 114. However, the moisture sensor 190 may be provided below the rotation axis 120 inside the container 110. For example, the moisture sensor 190 may be provided on the outer cylinder 112. In this case, the moisture sensor 190 may be provided between the rotation axis 120 and the point of the outer cylinder 112 that is located vertically lowest.

[0100] In the above embodiment, the moisture sensor 190 is a capacitance type moisture sensor or an electrical resistance type moisture sensor. However, the moisture sensor 190 may be a moisture sensor other than a capacitance type moisture sensor or an electrical resistance type moisture sensor. The moisture sensor 190 may be a microwave type moisture sensor or an optical type moisture sensor.

[0101] In the above embodiment, an example has been given in which at least a part of the slurry is dried by the drying apparatus 100 to become a powder. However, the slurry supplied to the drying apparatus 100 may be a slurry that does not become a powder even when dried.

[0102] In the above embodiment, the drying apparatus 100 is of a batch type, but the drying apparatus 100 may be of a continuous type.

[0103] The drying apparatus 100 and the method for estimating the moisture content according to the above-described embodiment, first modification, and second modification can also be applied to a reaction apparatus in which the moisture content of a slurry changes (e.g., increases) due to a reaction of the slurry caused by heating. For example, a reaction apparatus is provided, the reaction apparatus comprising: a container for accommodating a slurry; a heating device for heating the inside of the container; a rotating shaft rotatably provided within the container and extending horizontally or substantially horizontally; one or more blades provided on the rotating shaft; a driving device for rotating the rotating shaft; a moisture sensor provided within the container; and a calculation unit for estimating the moisture content of the slurry based on an output value of the moisture sensor during a stop period in which the slurry accommodated in the container is heated by the heating device and the rotation of the rotating shaft by the driving device is stopped. [Explanation of symbols]

[0104] 100 Drying equipment 110 Container 120 Rotational Axis 140 Feather 170 Heating device 180 Drive Unit 190 Moisture Sensor 212 Arithmetic section 214 Control Unit

Claims

1. a vessel for containing the slurry; a heating device for heating the inside of the container; a rotation shaft rotatably provided within the container and extending horizontally or substantially horizontally; one or more blades provided on the rotating shaft; a drive device that rotates the rotation shaft; a moisture sensor provided in the container; a calculation unit that estimates the moisture content of the slurry based on an output value of the moisture sensor during a stop period in which the slurry contained in the container is heated by the heating device and the rotation of the rotary shaft by the driving device is stopped; and A drying device comprising:

2. a control unit that controls the drive device to switch the rotation direction of the rotation shaft between a first direction and a second direction that is a rotation direction opposite to the first direction, The drying device according to claim 1 , wherein the stop period is an interval period between switching of the rotation direction of the rotary shaft.

3. The drying device according to claim 1 , wherein the calculation unit calculates a transition in the moisture content of the slurry based on output values ​​of the moisture sensor during a plurality of the stop periods.

4. The drying device according to claim 1 or 2, wherein the moisture sensor is provided below the rotation shaft.

5. 3. The drying device according to claim 1, wherein the moisture sensor is a capacitance type moisture sensor or an electrical resistance type moisture sensor.

6. The drying device according to claim 5 , wherein at least a portion of the slurry is dried to form a powder.

7. A method for estimating a moisture content of a slurry in a drying device including a container for accommodating a slurry, a heating device for heating the inside of the container, a rotating shaft rotatably provided in the container and extending in a horizontal or substantially horizontal direction, one or more blades provided on the rotating shaft, a driving device for rotating the rotating shaft, and a moisture sensor provided in the container, comprising: A method for estimating a moisture content of the slurry, the method comprising: estimating the moisture content of the slurry based on an output value of the moisture sensor during a stop period in which the slurry contained in the container is heated by the heating device and rotation of the rotating shaft by the driving device is stopped.

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