Method for measuring moisture content, moisture content measuring device, humidity control method, and method for producing coke.

Abstract

To provide a technique that enables highly accurate and stable moisture measurement without performing measurement of bulk density or layer thickness when performing moisture measurement by using a microwave for a measurement object conveyed on a conveyor.SOLUTION: A moisture measurement method for measuring the moisture of a measurement object conveyed on a conveyor includes: a conveyance amount measurement step of measuring a conveyance weight per unit time of the measurement object conveyed on the conveyor; a microwave transmission step of transmitting a microwave toward the measurement object as a transmission wave; a microwave reception step of receiving the microwave which has been transmitted in the microwave transmission step and has passed through the measurement object as a reception wave; a microwave change amount calculation step of calculating a change amount by comparing the transmission wave and the reception wave; and a moisture content calculation step of calculating a moisture content of the measurement object on the basis of the change amount calculated in the microwave change amount calculation step and the conveyance weight per unit time of the measurement object measured in the conveyance amount measurement step.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for measuring moisture content, a moisture content measuring device, a humidity control method, and a method for producing coke. [Background technology]

[0002] In steel mills, coal, the raw material for coke, is transported by conveyor belts, dried in humidity control units, and then fed into coke ovens. Generally, the lower the moisture content of the raw coal, the better the quality of the coke. However, if the moisture content is too low, it can lead to problems such as increased dust generation during transport, increased risk of ignition, and clogging of the coke oven. Therefore, it is necessary to control the moisture content within a specified range.

[0003] Therefore, there are techniques that use microwaves to measure the moisture content of coal. For example, Patent Documents 1 to 3 propose a technique in which microwaves are irradiated onto coal on a conveyor belt, and the moisture content of the coal is measured from the change in the propagation characteristics of the microwaves in the coal.

[0004] Specifically, Patent Document 1 proposes a technique for measuring moisture content using microwaves after leveling the surface of coal on a belt conveyor belt using a leveling plate (scraper) to physically uniformize the bulk density. Patent Document 2 proposes a moisture measuring device that includes a distance meter for measuring the layer thickness and a weighing machine for measuring the weight, and performs corrections on the data measured by a microwave moisture meter based on the layer thickness and the bulk density obtained from the layer thickness and weight. Patent Document 3 proposes a method for measuring moisture content without being affected by fluctuations in bulk density by embedding a microwave moisture meter in the coal seam.

[0005] Furthermore, Patent Document 4 proposes a technique for measuring both the density and water content of an object by measuring the attenuation and phase difference between microwaves that have not passed through the object and microwaves that have passed through the object. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-55726 [Patent Document 2] Japanese Patent Application Publication No. 6-129980 [Patent Document 3] Japanese Patent Publication No. 2014-112053 [Patent Document 4] Japanese Patent Publication No. 2019-70535 [Overview of the project] [Problems that the invention aims to solve]

[0007] Traditional microwave-based moisture measurement techniques require information on bulk density and layer thickness. Bulk density is often measured using a method that utilizes the property that gamma rays, a type of radiation, are weakened as they pass through a material. However, gamma rays are strictly regulated, and methods using gamma rays to measure bulk density incur significant management costs.

[0008] On the other hand, the technologies described in Patent Documents 1 to 4 do not use gamma ray measurement of bulk density, so the above-mentioned inconveniences do not occur, but they have the following problems. Specifically, in the technology of Patent Document 1, the surface of coal on the belt conveyor is leveled with a fixed leveling plate (scraper) without measuring bulk density, and the bulk density is made physically uniform. However, in this case, the variation in layer thickness due to fluctuations in the amount of material being measured is large, and if the surface of the material being measured is below the range of motion of the leveling plate (scraper), correction becomes impossible. In addition, there is a problem that the material being measured is bounced off by the leveling plate (scraper), causing it to fall off the belt conveyor. The technology disclosed in Patent Document 3 also has a similar problem in that the material being measured is bounced off by a box equipped with a microwave moisture meter and falls off the belt conveyor. In the technology described in Patent Document 2, the layer thickness and bulk density are measured and used to correct the moisture meter, but a distance meter for measuring the layer thickness must be additionally installed. Furthermore, in techniques such as Patent Document 4, which measure the density of a substance from attenuation and phase, it is difficult to measure the bulk density with high accuracy for various types of coal.

[0009] This invention provides a technology that enables highly accurate and stable moisture measurement of objects being transported on a conveyor, particularly coal, using microwaves, without the need to measure bulk density or layer thickness. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides the following means [1] to

[13] .

[0011] [1] A method for measuring the moisture content of an object being transported on a conveyor, A conveying volume measurement step for measuring the conveying weight per unit time of an object to be measured being transported on the conveyor, A microwave transmission step of transmitting microwaves as a transmitted wave toward the object to be measured, A microwave receiving step, which receives the microwaves transmitted in the microwave transmission step and after they have passed through the object to be measured as received waves, A microwave change amount calculation step of comparing the transmitted wave and the received wave to calculate a change amount; A moisture content calculation step of calculating the moisture content of the object to be measured based on the change amount calculated in the microwave change amount calculation step and the conveyance weight per unit time of the object to be measured measured in the conveyance amount measurement step; A moisture measurement method comprising the above.

[0012] The moisture measurement method according to [1], wherein the object to be measured is coal.

[0013] The moisture measurement method according to [1] or [2], wherein the change amount calculated in the microwave change amount calculation step includes one or both of a phase difference and an attenuation rate.

[0014] The moisture measurement method according to [1] or [2], wherein a plurality of frequencies are used as the microwave.

[0015] The moisture measurement method according to [1] or [2], further comprising a leveling step of pressing the object to be measured on the conveyor before the microwave transmission step to level the surface unevenness of the object to be measured.

[0016] A moisture measurement device for measuring the moisture content of an object to be measured conveyed on a conveyor, A conveyance amount measurement unit that measures the conveyance weight per unit time of the object to be measured conveyed on the conveyor; A microwave transmission unit that transmits microwaves as transmitted waves toward the object to be measured; A microwave reception unit that receives the microwaves transmitted from the microwave transmission unit and transmitted through the object to be measured as received waves; A microwave change amount calculation unit that compares the transmitted wave and the received wave to calculate a change amount; A moisture content calculation unit that calculates the moisture content of the object to be measured based on the change amount calculated by the microwave change amount calculation unit and the conveyance weight per unit time of the object to be measured measured by the conveyance amount measurement unit; A moisture measurement device comprising the above.

[0017] [7] The object to be measured is coal, as described in [6].

[0018] [8] A moisture measuring device according to [6] or [7], further comprising a leveling mechanism upstream of the position on the conveyor from which the microwaves of the conveyor pass through the object to be measured, for pressing down on the object to be measured on the conveyor to level out surface irregularities of the object to be measured.

[0019] [9] The moisture measuring device according to [8], wherein the leveling mechanism is a roller that moves up and down in accordance with the thickness of the layer of the object to be measured on the conveyor.

[0020]

[10] The moisture measuring device according to [8], wherein the leveling mechanism has a sled-shaped weight having a bottom surface that moves up and down in accordance with the fluctuation of the surface height of the object to be measured on the conveyor, and an inclined surface that curves upward from the bottom surface on the upstream side in the direction of travel of the conveyor.

[0021]

[11] A humidity control method comprising measuring the moisture content of the object to be measured by the moisture measurement method described in [1] above, and adjusting the humidity by drying or adding water based on the measured moisture content so that the moisture content of the object to be measured falls within a set range.

[0022]

[12] The object to be measured is coal, the humidity control method according to

[11] .

[0023]

[13] A method for producing coke, comprising charging coal, which is the object to be measured, which has been dehumidified by the dehumidification method described in

[12] above, into a coke oven to produce coke. [Effects of the Invention]

[0024] According to the present invention, the moisture content of the object being measured is calculated based on the measurement of the transport weight per unit time of the object being transported on the conveyor and the calculation of the change in the transmitted and received microwave waves. This enables highly accurate and stable moisture measurement without the need to measure bulk density or layer thickness. In other words, conventional microwave moisture measurement of coal requires bulk density and layer thickness to obtain high measurement accuracy, but highly accurate moisture measurement can be achieved by using the transport weight per unit time of the object being measured instead of bulk density and layer thickness. Furthermore, since no fixed leveling plates are used, the object being measured does not fall from the conveyor, enabling stable moisture measurement. In addition, it is low-cost because there is no need to install measuring devices with high management costs such as gamma rays or additional layer thickness measuring devices. When coal is used as the object being measured, the conveyor scale (transport amount measuring device) that is often installed on coal transport conveyors can be used as is to measure the transport weight per unit time, further reducing costs. [Brief explanation of the drawing]

[0025] [Figure 1] This is a schematic side view showing a moisture measuring device according to the first embodiment of the present invention. [Figure 2] Figure 1 is a flowchart showing the method for measuring moisture content using the moisture measuring device. [Figure 3] This is a schematic side view showing a moisture measuring device according to a second embodiment of the present invention. [Figure 4] Figure 3 is a schematic side view showing the leveling mechanism included in the moisture measurement device. [Figure 5] Figure 4 is a cross-sectional view of the leveling mechanism, seen from the direction opposite to the conveying direction of the belt conveyor. [Figure 6] This is a schematic side view illustrating another example of a leveling mechanism. [Figure 7] Figure 6 is a cross-sectional view of the leveling mechanism, seen from the opposite direction to the conveying direction of the belt conveyor. [Figure 8] This is a schematic side view illustrating yet another example of a leveling mechanism. [Figure 9]Figure 8 is a cross-sectional view of the leveling mechanism, taken from a direction perpendicular to the conveying direction of the belt conveyor. [Figure 10] This figure shows the relationship between the moisture content of coal obtained by the drying method and the moisture content of coal obtained by microwave measurement used in the first embodiment of the present invention. (a) shows the case where no correction for the amount of coal transported is made to the moisture content on the vertical axis, and (b) shows the case where a correction for the amount of coal transported is made to the moisture content on the vertical axis. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described below with reference to the attached drawings.

[0027] <First Embodiment> Figure 1 is a schematic side view showing a moisture measuring device according to the first embodiment of the present invention.

[0028] The moisture content measuring device 1 measures the moisture content of coal C, which is transported on the belt conveyor B shown in Figure 1 in the direction of arrow V in the figure. Coal C is cut from hopper H and transported by belt conveyor B to the humidity control equipment, where it is dried (or hydrated) based on the moisture content measured by the moisture content measuring device 1 so that the moisture content falls within the set range. After that, the coal with adjusted moisture content is charged into a coke oven to produce coke. Although Figure 1 shows an example where the moisture content measuring device 1 is installed before the humidity control equipment, the moisture content measuring device 1 may also be installed after the humidity control equipment, or it may be installed both before and after the humidity control equipment. Even if the moisture content measuring device 1 is installed only after the humidity control equipment, if the moisture content measured by the moisture content measuring device 1 deviates from the set range, the drying (or hydration) intensity will be adjusted in a direction that brings the moisture content within the set range.

[0029] The moisture content measuring device 1 comprises a transport volume measuring unit 2, a microwave transmitting unit 31, a microwave receiving unit 32, a microwave change amount calculation unit 33, and a moisture content calculation unit 4.

[0030] The conveyance volume measuring unit 2 is a device that continuously measures the conveyance weight (hereinafter referred to as conveyance volume) of coal C being transported on the belt conveyor B per unit time. The conveyance volume measuring unit 2 comprises a load detection unit 21, a speed detection unit 22, and a conveyance volume calculation unit 23.

[0031] The load detection unit 21 is a device that measures the weight Wc (kg) of coal within a measurement range L (m) in front of and behind the load detection unit 21 on the belt conveyor B, and consists of, for example, rollers and load cells installed on the underside of the belt conveyor B to receive the load of coal. The speed detection unit 22 is a device that measures the moving speed v (m / s) of the belt conveyor B, and consists of, for example, a roller encoder. The conveying amount calculation unit 23 is a calculation device that continuously calculates the conveying amount Q (t / h) from the coal weight measured by the load detection unit 21 and the moving speed of the belt conveyor B measured by the speed detection unit 22. The conveying amount Q of coal at a given moment is calculated as Q = 3.6 × Wc × v / L.

[0032] The microwave transmitting unit 31 transmits microwaves as a transmission wave toward the coal seam on the belt conveyor B. Specifically, it transmits microwaves with a predetermined power and phase. The microwave receiving unit 32 receives the microwaves transmitted from the microwave transmitting unit 31 and after they have passed through the coal C as a reception wave. The microwave transmitting unit 31 and the microwave receiving unit 32 each consist of, for example, a horn antenna and are positioned downstream of the conveying amount measuring unit 2 on the belt conveyor B, facing each other with the coal C in between.

[0033] The microwave change amount calculation unit 33 is connected to the microwave transmission unit 31 and the microwave reception unit 32 via cables, respectively, and calculates the change amount by comparing the transmission wave transmitted from the microwave transmission unit 31 and the reception wave received by the microwave reception unit 32. More precisely, the reception wave in the state where there is no coal C on the belt conveyor B is measured in advance, and the change amount is calculated by comparing it with the reception wave in the state where there is coal C. The change amount may include one or both of the phase difference and the attenuation rate (power ratio). In addition to calculating the change amount of the microwave, the microwave change amount calculation unit 33 also controls the operations of the microwave transmission unit 31 and the microwave reception unit 32.

[0034] Note that conditions such as the wavelength of the microwave to be used and the distance between the microwave transmission unit 31 and the microwave reception unit 32 can be appropriately set according to the brand and type of coal C, etc. Further, the transmission wave and the reception wave may be compared with microwaves of a plurality of frequencies (wavelengths) to obtain the change amount (i.e., frequency characteristics) for each frequency.

[0035] The moisture content calculation unit 4 calculates the moisture content of the coal C by using the change amount between the transmission wave and the reception wave of the microwave W calculated by the microwave change amount calculation unit 33 and the conveyance amount of the coal C calculated by the conveyance amount calculation unit 23. Specifically, when the phase difference is Φ (deg), the attenuation rate is A (dB), and the conveyance amount is Q (t / h), the moisture content M (mass %) of the coal C is calculated by the following formula (1) by the moisture content calculation unit 4. M=(K Φ ×Φ / Q)+(K A ×A / Q)+K C ···(1) Here, K Φ 、K A 、K C are coefficients preset according to the brand and type of coal C, the distance between the microwave transmission unit 31 and the microwave reception unit 32, the material and thickness of the belt conveyor B, etc.

[0036] Also, the coefficients K Φ 、K A 、K CThe coefficient K may be a coefficient predetermined using a large number of pre-prepared coal C samples. Specifically, the coefficient K can be determined using the following procedure. Φ , K A , K C This can be determined in advance. Specifically, the moisture content M is calculated for several samples (at least three samples of coal C) prepared in advance, based on the JIS standard (analytical moisture) JIS M 8811:2000 Coal and coke - Method for measuring total moisture content of a lot. In addition, the phase difference Φ, decay rate A, and transport volume Q are also measured for these samples. Then, based on the moisture content M, phase difference Φ, decay rate A, and transport volume Q for these samples, the coefficient K in equation (1) above is calculated. Φ , K A , K C To decide.

[0037] In Figure 1, coal C is measured by microwave W after passing through the conveyance amount measurement unit 2, but the conveyance amount may also be measured by the conveyance amount measurement unit 2 after the measurement by microwave W. In either order, the moisture content calculation unit 4 aligns the measurement data so that the position measured by microwave W and the position measured for conveyance amount coincide.

[0038] Next, we will explain the method for measuring moisture content using the moisture measuring device 1 configured in this way. Figure 2 is a flowchart showing the moisture measurement method using the moisture measuring device shown in Figure 1. First, the amount of coal C being transported on the belt conveyor B is measured (transport amount measurement process; step ST1). The amount of coal C being transported is measured by the load detection 21 of the transport amount measurement unit 2, which measures the weight of coal within the measurement range L, the speed detection unit 22, which measures the moving speed of the belt conveyor B, and the transport amount calculation unit 23 which multiplies the measured weight of coal with the moving speed of the belt conveyor B.

[0039] Next, microwaves are transmitted as a transmitted wave towards the coal C on the belt conveyor B (microwave transmission process; step ST2). Microwave transmission is performed by a microwave transmitting unit 31, which consists of, for example, a horn antenna. The microwave transmitting unit 31 transmits microwaves W of predetermined power and phase.

[0040] Then, the microwaves that have been transmitted and passed through coal C are received as received waves (microwave reception process; step ST3). Microwave reception is performed by a microwave receiving unit 32, which consists of, for example, a horn antenna.

[0041] Next, the transmitted wave and the received wave are compared to calculate the amount of change (microwave change amount calculation step; step ST4). This step is performed by the microwave change amount calculation unit 33. The amount of change may include either or both of the phase difference and the attenuation rate (power ratio).

[0042] Next, the moisture content of coal C is calculated based on the change in microwaves calculated in step ST4 and the amount of coal C transported measured in step ST1 (moisture content calculation step; step ST5). This step is performed by the moisture content calculation unit 4. The moisture content is calculated at this time based on equation (1) described above.

[0043] As described above, the moisture content of coal C on the belt conveyor B can be measured by performing steps ST1 to ST5 in order. However, the conveying amount measurement process in step ST1 may be performed after the calculation of microwave change amounts in steps ST2 to ST4.

[0044] According to this embodiment, by performing the conveyance amount measurement process in step ST1, the moisture content of coal C on the belt conveyor B can be measured with high accuracy without measuring the bulk density or layer thickness of the coal.

[0045] In conventional technology, the formula for calculating the moisture content of coal C includes bulk density and layer thickness as variables, requiring the measurement or keeping constant of at least one of these. However, in this embodiment, the amount of coal transported is used as a variable in the formula for calculating the moisture content of coal C, eliminating the need to measure bulk density or layer thickness. Therefore, there is no need to install high-cost measuring equipment such as gamma ray equipment for measuring bulk density, or additional equipment for measuring layer thickness, thus reducing equipment costs and allowing for a simpler equipment design.

[0046] Furthermore, in this embodiment, since there is no need for a fixed leveling plate (scraper) or the like to maintain a constant bulk density, stable moisture measurement can be performed without the coal C being thrown off the belt conveyor B.

[0047] <Second Embodiment> Figure 3 is a schematic side view showing an example of a moisture content measuring device according to a second embodiment of the present invention. The moisture content measuring device according to the second embodiment is the same as the moisture content measuring device of the first embodiment with the addition of a leveling mechanism. Since the moisture content measuring device of the second embodiment is the same as the first embodiment except for the addition of the leveling mechanism, other components are denoted by the same reference numerals as in the first embodiment and their descriptions are omitted.

[0048] Figure 4 is a schematic side view showing an example of the leveling mechanism of the second embodiment, and Figure 5 is a cross-sectional view of the leveling mechanism of Figure 4 viewed from the opposite direction of the conveying direction V (downstream side of conveyor B). As shown in these figures, the leveling mechanism 5 of this example is a mechanism that pre-compacts the coal C on the belt conveyor B to level out surface irregularities, and moves up and down in accordance with the variation in the thickness of the coal C layer. The leveling mechanism 5 consists of a roller 51 for pre-compacting the coal C on the belt conveyor B and a pair of arms 52 that hold it. As shown in Figure 5, the rotation axis 51a of the roller 51 is arranged parallel to the width direction of the belt conveyor B. The rotation axis 51a of the roller 51 is held by the arms 52. The arms 52 extend diagonally upward from the rotation axis 51a, and their upper ends are rotatably held on a shaft 53, and are configured to swing relative to the shaft 53 as shown in Figure 4. As the arms 52 swing, the roller 51 can move up and down. The roller 51 presses down on the coal C being transported on the belt conveyor B from above, leveling the surface of the coal C. The roller 51 also moves up and down in accordance with fluctuations in the surface height of the coal C. Since this pressing by the roller 51 is performed by the roller 51's own weight, it is preferable to use a roller 51 that has sufficient weight to level the surface of the coal C.

[0049] Figure 6 is a schematic side view showing another example of a leveling mechanism, and Figure 7 is a cross-sectional view of the leveling mechanism of Figure 6 viewed from the opposite direction of the conveying direction V (downstream side of conveyor B). The leveling mechanism 5' in this example has a weight 54 having a surface for compacting the coal C, and a pair of first arms 55a and a pair of second arms 55b for holding the weight 54.

[0050] The weight 54 has a curved shape, with a bottom surface that is in contact with the coal C on the belt conveyor B and kept parallel to the belt conveyor B, and an inclined surface 54c that curves upward from the bottom surface on the upstream side in the direction of travel of the belt conveyor B (direction of arrow V in the figure). The inclined surface 54c guides the transported coal C to the lower part of the weight 54.

[0051] A pair of first arms 55a are rotatably connected to the weight 54 via a shaft 54a at their lower ends, and a pair of second arms 55b are rotatably connected to the weight 54 via a shaft 54b at their lower ends. The first arms 55a and the second arms 55b extend diagonally upward parallel to each other from their lower ends connected by shafts 54a and 54b. The upper ends of the pair of first arms 55a are held by a first shaft 56a, and the upper ends of the pair of second arms 55b are held by a second shaft 56b. The first arms 55a and the second arms 55b are configured to swing relative to the first shaft 56a and the second shaft 56b, and the swinging of the first arms 55a and the second arms 55b allows the weight 54 to move up and down while keeping its bottom surface parallel to the belt conveyor B. The weight 54 presses down on the coal C being transported on the belt conveyor B, compressing it and leveling the surface of the coal C, while moving up and down in accordance with the fluctuations in the surface height of the coal C. Since this compression by the weight 54 is performed by the weight of the weight 54 itself, it is preferable to use a weight 54 that has sufficient weight to compress the coal C. The load may also be adjusted by adding an additional weight on top of the weight 54.

[0052] Figure 8 is a schematic side view showing yet another example of the leveling mechanism, and Figure 9 is a cross-sectional view of the leveling mechanism of Figure 8 viewed from the opposite direction of the conveying direction V (downstream side of conveyor B). The leveling mechanism 5″ in this example has a plate 57 that functions as a weight to pre-compact the coal C on the belt conveyor B, and a shaft 58 that swingably supports the plate 57.

[0053] The plate 57 has a curved shape with a bottom surface that is in contact with the coal C on the belt conveyor B and is nearly parallel to the belt conveyor B, and an inclined surface 57a that curves upward from the bottom surface on the upstream side in the direction of travel of the belt conveyor B (direction of arrow V in the figure). The inclined surface 57a guides the transported coal C to the lower part of the plate 57. The upstream end of the plate 57 is held by the shaft 58 and is designed to swing relative to the shaft 58. The plate 57 presses down on the coal C being transported on the belt conveyor B from above, compressing it and leveling the surface of the coal C, while moving up and down in accordance with the fluctuations in the surface height of the coal C. Since this compression by the plate 57 is performed by the weight of the plate 57 itself, it is preferable to use a plate 57 that has sufficient weight to compress the coal C. The load may be adjusted by adding an additional weight on top of the plate 57.

[0054] In this embodiment, by providing one of the leveling mechanism 5, leveling mechanism 5', or leveling mechanism 5'' in the first embodiment, the surface irregularities of the coal C are leveled and made flat. As a result, refraction and scattering at the surface of the coal C are suppressed when microwaves W pass through the coal C, and the fluctuations in the change amount (phase difference, attenuation rate) calculated by the microwave change amount calculation unit 3 become smaller, resulting in the effect of stabilizing moisture measurement.

[0055] Although embodiments of the present invention have been described above, these should be considered merely illustrative and not restrictive. The above embodiments may be omitted, substituted, or modified in various ways without departing from the spirit of the present invention.

[0056] For example, in the above embodiment, coal was used as an example of an object to be measured for moisture content, but it is not limited to coal as long as the moisture content can be measured. Also, in Figures 1 and 3, a belt conveyor B was used that is continuous from hopper H to the position through which microwaves W penetrate, but coal C may be transported by moving between multiple belt conveyors.

[0057] In addition, there are cases where a feeder is used that controls the speed v of the belt conveyor B directly below the hopper H based on the measurement value of the conveying amount measuring unit 2 so that the amount of coal C conveyed Q remains constant (conveying amount setting value Qs). In this case, the conveying amount setting value Qs may be used instead of the conveying amount Q (measured value) in the calculation formula (1) of the moisture content M in the moisture content calculation unit 4.

[0058] Furthermore, while three examples of leveling mechanisms were shown in the second embodiment, the mechanism is not limited to these, as long as it can level the surface of the coal while compressing it from above. [Examples]

[0059] The following describes some examples. Here, the effect of the conveying amount measurement process in the moisture content measuring device of the first embodiment was confirmed. Figure 10 shows the relationship between the moisture content of coal by the drying method and the moisture content of coal measured by microwave measurement used in the first embodiment of the present invention, where (a) shows the case where no correction for the conveying amount of coal is made to the moisture content on the vertical axis, and (b) shows the case where the conveying amount of coal is made to the moisture content on the vertical axis.

[0060] Specifically, the vertical axis of Figure 10(a) represents the moisture content calculated using a calibration curve created by performing multiple regression analysis according to equation (1) above, without considering the amount of coal transported Q, which is assumed to be a constant value. The vertical axis of Figure 10(b) represents the moisture content calculated using a calibration curve created by performing multiple regression analysis according to equation (1) above, taking into account the amount of coal transported Q. In the drying method used in this example, approximately 5g of coal sample was dried at 110°C for several minutes until there was no change in weight, and the moisture content was calculated from the weight change before and after drying. The data on the horizontal axis is the average moisture content obtained by performing this measurement three times. Furthermore, the moisture content measured by microwave measurement on the vertical axis was evaluated using the leave-one-out cross-validation method. That is, each data point is a value calculated using a calibration curve created by multiple regression analysis from the other data. Furthermore, the diagonal dashed lines in the plots in Figures 10(a) and (b) represent lines where the water content on the vertical axis and the horizontal axis are equal.

[0061] As shown in Figure 10, when the amount of coal transported was not considered (Figure 10(a)), the standard deviation of the difference between the moisture content measured by the drying method and the moisture content measured by microwave measurement was 1.05%, but when the amount of coal transported was considered (Figure 10(b)), the standard deviation was 0.55%. In other words, it was confirmed that the accuracy of moisture measurement is improved by using a calibration curve (Equation (1)) that includes the amount of coal transported. [Explanation of Symbols]

[0062] 1. Moisture measuring device 2. Conveying volume measurement unit 4 Moisture content calculation section 5, 5', 5" leveling mechanism 21 Load detection unit 22 Speed ​​detection unit 23. Conveyance Amount Calculation Unit 31 Microwave Transmitter 32 Microwave Receiver 33. Microwave change amount calculation unit 51 Rollers 51a Rotation axis 52, 55a, 55b arms 53, 56a, 56b, 58 shafts 54 weights 54a, 54b axis 57 Plates B Belt conveyor C Coal H Hopper

Claims

1. A method for measuring the moisture content of an object being transported on a conveyor, A conveying volume measurement step for measuring the conveying weight per unit time of an object to be measured being transported on the conveyor, A microwave transmission step of transmitting microwaves as a transmitted wave toward the object to be measured, A microwave receiving step, which receives the microwaves transmitted in the microwave transmission step and after they have passed through the object to be measured as received waves, A microwave change amount calculation step that compares the transmitted wave and the received wave and calculates a change amount that includes either or both of the phase difference and the attenuation rate, A moisture content calculation step, which calculates the moisture content of the object to be measured using the following formula (1) based on the amount of change calculated in the microwave change calculation step and the weight of the object to be measured per unit time measured in the transport amount measurement step, A method for measuring moisture content, comprising the following features. M = (K Φ × Φ / Q) + (K A × A / Q) + K C ... (1) Here, M is the water content (mass%), Φ is the phase difference (deg), A is the decay rate (dB), Q is the conveying weight per unit time (t / h), and KΦ, KA, and KC are predetermined coefficients.

2. The moisture content measurement method according to claim 1, wherein the object to be measured is coal.

3. The moisture measurement method according to claim 1 or claim 2, wherein multiple frequencies are used as the microwaves.

4. The moisture content measurement method according to claim 1 or 2, further comprising a leveling step of pressing down on the object to be measured on the conveyor to smooth out surface irregularities of the object to be measured, prior to the microwave transmission step.

5. A moisture measuring device for measuring the moisture content of an object being transported on a conveyor, A conveying amount measuring unit that measures the conveying weight per unit time of the object to be measured being transported on the conveyor, A microwave transmitting unit that transmits microwaves as a transmitted wave toward the object to be measured, A microwave receiving unit that receives the microwaves transmitted from the microwave transmitting unit and transmitted through the object to be measured as received waves, A microwave change amount calculation unit that compares the transmitted wave and the received wave and calculates a change amount that includes either or both of the phase difference and the attenuation rate, A moisture content calculation unit calculates the moisture content of the object to be measured using the following formula (1), based on the amount of change calculated by the microwave change amount calculation unit and the weight of the object to be measured per unit time measured by the transport amount measurement unit. A moisture measuring device equipped with the following features. M = (K Φ × Φ / Q) + (K A × A / Q) + K C ... (1) Here, M is the water content (mass%), Φ is the phase difference (deg), A is the decay rate (dB), Q is the conveying weight per unit time (t / h), and KΦ, KA, and KC are predetermined coefficients.

6. The moisture measuring device according to claim 5, wherein the object to be measured is coal.

7. The moisture measuring device according to claim 5 or 6, further comprising a leveling mechanism upstream of the position where the microwaves of the conveyor pass through the object to be measured, which presses down on the object to be measured on the conveyor to level out surface irregularities of the object to be measured.

8. The moisture measuring device according to claim 7, wherein the leveling mechanism is a roller that moves up and down in accordance with the layer thickness of the object to be measured on the conveyor.

9. The moisture measuring device according to claim 7, wherein the leveling mechanism has a weight that is shaped like a sled, having a bottom surface that moves up and down in accordance with the fluctuation of the surface height of the object to be measured on the conveyor, and an inclined surface that curves upward from the bottom surface on the upstream side in the direction of travel of the conveyor.

10. A humidity control method comprising measuring the moisture content of an object to be measured using the moisture measurement method described in claim 1, and adjusting the humidity by drying or adding water based on the measured moisture content so that the moisture content of the object to be measured falls within a set range.

11. The humidity control method according to claim 10, wherein the object to be measured is coal.

12. A method for producing coke, comprising charging coal, which is the object to be measured, which has been dehumidified by the dehumidification method described in claim 11, into a coke oven to produce coke.

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