Moisture measurement method, moisture measurement apparatus, 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 moisture measuring method, a moisture measuring device, a moisture adjustment method, and a coke manufacturing method. [Background technology]

[0002] In steel plants, coal, which is the raw material for coke, is transported on a conveyor belt, dried by a moisture control machine, and then loaded into the coke oven. Generally, the lower the moisture content of the raw coal, the higher the quality of the coke. However, if the moisture content is too low, problems such as increased coal dust generation during transportation, risk of fire, and clogging of the coke oven occur. For this reason, 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 techniques in which microwaves are irradiated onto coal on a belt conveyor and the moisture content of the coal is measured from changes in the propagation characteristics of the microwaves in the coal.

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

[0005] Furthermore, Patent Document 4 proposes a technology for measuring both the density and moisture content of an object to be measured from the amount of attenuation and phase 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] JP 2014-112053 A [Patent Document 4] JP 2019-70535 A Summary of the Invention [Problem to be solved by the invention]

[0007] Conventionally, moisture measurement techniques using microwaves require information on bulk density and layer thickness. Among these, bulk density is often measured using a method that utilizes the property that gamma rays, a type of radiation, are weakened when they pass through a material. However, the handling of gamma rays is strictly regulated, and the method of measuring bulk density using gamma rays requires high management costs.

[0008] On the other hand, the techniques described in Patent Documents 1 to 4 do not use gamma ray bulk density measurement, so the above-mentioned inconvenience does not occur, but they have the following problems. That is, in the technique of Patent Document 1, the surface of the coal on the belt conveyor is leveled with a fixed leveling plate (scraper) without measuring the bulk density, and the bulk density is physically uniformed. In that case, if the layer thickness varies greatly due to the fluctuation in the transport amount of the measured object, and the surface of the measured object is below the movable range of the leveling plate (scraper), correction becomes impossible. In addition, there is a problem that the measured object falls from the belt conveyor because the leveling plate (scraper) bounces the measured object. The technique disclosed in Patent Document 3 also has a similar problem that the measured object is bounced by a box with a microwave moisture meter installed inside and falls from the belt conveyor. In the technique 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, with the technology of measuring the density of a measurement object from the amount of attenuation and the amount of phase as in Patent Document 4, it is difficult to measure the bulk density with high accuracy for various coal brands.

[0009] The present invention provides a technology that enables highly accurate and stable moisture measurement using microwaves on an object to be measured, particularly coal, transported on a conveyor, without measuring bulk density or layer thickness. [Means for solving the problem]

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

[13] .

[0011] [1] A moisture measurement method for measuring the moisture content of a test object transported on a conveyor, comprising the steps of: a conveyance amount measuring step of measuring a conveyance weight per unit time of the objects to be measured conveyed on the conveyor; a microwave transmitting step of transmitting a microwave as a transmission wave toward the object to be measured; a microwave receiving step of receiving, as a received wave, the microwave transmitted in the microwave transmitting step and having passed through the object to be measured; a microwave change amount calculation step of calculating a change amount by comparing the transmitted wave with the received wave; a moisture content calculation step of calculating a moisture content of the object based on the change amount calculated in the microwave change amount calculation step and the transported weight per unit time of the object measured in the transport amount measurement step; A moisture measurement method comprising:

[0012] [2] The moisture measurement method according to [1], wherein the object to be measured is coal.

[0013] [3] The moisture measurement method according to [1] or [2], wherein the change calculated in the microwave change calculation step includes one or both of a phase difference and an attenuation rate.

[0014] [4] The moisture measurement method described in [1] or [2], wherein the microwaves used are of multiple frequencies.

[0015] [5] The moisture measurement method according to [1] or [2], further comprising a smoothing step of pressing down the objects to be measured on the conveyor prior to the microwave transmission step to smooth out any surface irregularities of the objects to be measured.

[0016] [6] A moisture measuring device for measuring the moisture content of a test object transported on a conveyor, comprising: a conveyance amount measuring unit that measures a conveyance weight per unit time of the object to be measured conveyed on the conveyor; a microwave transmission unit that transmits a microwave as a transmission wave toward the object to be measured; a microwave receiving unit that receives the microwave transmitted from the microwave transmitting unit and transmitted through the object to be measured as a received wave; a microwave change amount calculation unit that compares the transmitted wave with the received wave to calculate an amount of change; a moisture content calculation unit that calculates a moisture content of the object to be measured based on the amount of change calculated by the microwave change amount calculation unit and the transported weight per unit time of the object to be measured measured by the transport amount measurement unit; A moisture measuring device comprising:

[0017] [7] The moisture measuring device according to [6], wherein the object to be measured is coal.

[0018] [8] A moisture measuring device as described in [6] or [7], further comprising a smoothing mechanism, upstream of the position on the conveyor where the microwaves pass through the objects to be measured, for pressing down the objects on the conveyor and smoothing out any surface irregularities on the objects to be measured.

[0019] [9] The moisture measuring device described in [8], 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.

[0020]

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

[0021]

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

[0022]

[12] The humidity control method according to

[11] , wherein the object to be measured is coal.

[0023]

[13] A method for producing coke, comprising charging the coal to be measured, the moisture of which has been adjusted by the moisture adjustment method described in

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

[0024] According to the present invention, the weight of the object to be measured transported on the conveyor per unit time is measured, and the change in the transmitted and received microwave waves is calculated, and the moisture content of the object to be measured is calculated based on these. This allows for highly accurate and stable moisture measurement without measuring the bulk density or layer thickness. That is, in conventional moisture measurement of coal, which is the object to be measured, using the bulk density and layer thickness to obtain high measurement accuracy, but highly accurate moisture measurement can be achieved by using the weight of the object to be measured transported per unit time instead of the bulk density and layer thickness. Furthermore, since no fixed leveling plate or the like is used, the object to be measured does not fall from the conveyor, and stable moisture measurement is possible. In addition, since there is no need to install a measuring device with high management costs such as gamma rays or an additional layer thickness measuring device, the method is low cost. When coal is used as the object to be measured, a conveyor scale (conveyance amount measuring device) that is often installed on coal conveyors can be used as is to measure the weight of the object to be measured per unit time, thereby achieving further cost reduction. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a side view that illustrates a schematic view of a moisture measuring device according to a first embodiment of the present invention. [Diagram 2] 2 is a flowchart showing a moisture measuring method using the moisture measuring device of FIG. [Diagram 3] FIG. 4 is a side view that illustrates a schematic view of a moisture measuring device according to a second embodiment of the present invention. [Figure 4] 4 is a side view showing a schematic diagram of a leveling mechanism included in the moisture measuring device of FIG. 3. [Diagram 5] 5 is a cross-sectional view of the leveling mechanism of FIG. 4 as viewed from the opposite direction to the conveying direction of the belt conveyor. [Figure 6] FIG. 11 is a side view showing a schematic diagram of another example of the leveling mechanism. [Figure 7] 7 is a cross-sectional view of the leveling mechanism of FIG. 6, viewed from the opposite direction to the conveying direction of the belt conveyor. [Figure 8] FIG. 13 is a side view illustrating a schematic diagram of still another example of the leveling mechanism. [Figure 9]9 is a cross-sectional view of the leveling mechanism of FIG. 8 as viewed from a direction perpendicular to the conveying direction of the belt conveyor. [Figure 10] FIG. 1 shows the relationship between the moisture content of coal measured by a 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 the moisture content on the vertical axis is not corrected for the amount of coal transported, and (b) shows the case where the moisture content on the vertical axis is corrected for the amount of coal transported. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0027] <First embodiment> FIG. 1 is a side view that illustrates a moisture measuring device according to a first embodiment of the present invention.

[0028] The moisture measuring device 1 measures the moisture content of coal C, which is a measurement object transported on a belt conveyor B shown in FIG. 1 in the direction of the arrow V in the figure. The coal C is cut from a hopper H and transported to a moisture control facility by the belt conveyor B, where it is dried (or hydrated) so that the moisture content falls within a set range based on the moisture content measured by the moisture measuring device 1. The coal with the adjusted moisture content is then charged into a coke oven to produce coke. Note that FIG. 1 shows an example in which the moisture measuring device 1 is installed in the upstream stage of the moisture control facility, but the moisture measuring device 1 may be installed in the downstream stage of the moisture control facility, or may be installed in both the upstream and downstream stages of the moisture control facility. Even if the moisture measuring device 1 is installed only in the downstream stage of the moisture control facility, if the moisture content measured by the moisture measuring device 1 deviates from the set range, the intensity of drying (or hydration) is adjusted in the direction in which the moisture content falls within the set range.

[0029] The moisture measuring device 1 includes a transport amount measuring section 2, a microwave transmitting section 31, a microwave receiving section 32, a microwave change amount calculating section 33, and a moisture content calculating section 4.

[0030] The conveying amount measuring unit 2 is a device that continuously measures the conveyed weight per unit time (hereinafter referred to as the conveying amount) of coal C conveyed on the belt conveyor B. The conveying amount measuring unit 2 includes a load detecting unit 21, a speed detecting unit 22, and a conveying amount calculating unit 23.

[0031] The load detection unit 21 is a device that measures the coal weight Wc (kg) in a measurement range L (m) before and after the load detection unit 21 on the belt conveyor B, and is composed of, for example, a roller and a load cell that are installed under the belt conveyor B and 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 is composed of, for example, a roller encoder. The transport amount calculation unit 23 is an arithmetic device that continuously calculates the transport 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 coal transport amount Q at a certain moment is calculated as Q = 3.6 × Wc × v / L.

[0032] The microwave transmitting unit 31 transmits microwaves as transmission waves toward the coal layer on the belt conveyor B. Specifically, it transmits microwaves of a predetermined power and phase. The microwave receiving unit 32 receives the microwaves transmitted from the microwave transmitting unit 31 and transmitted through the coal C as received waves. The microwave transmitting unit 31 and the microwave receiving unit 32 are each formed of, for example, a horn antenna, and are positioned downstream of the transport 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, and calculates the amount of change by comparing the transmission wave transmitted from the microwave transmission unit 31 with the reception wave received by the microwave reception unit 32. More precisely, the reception wave in a state where there is no coal C on the belt conveyor B is measured in advance, and the amount of change is calculated by comparing the reception wave with the reception wave in a state where there is coal C. The amount of change may include one or both of the phase difference and the attenuation rate (power ratio). In addition to calculating the amount of change in the microwave, the microwave change amount calculation unit 33 also controls the operation of the microwave transmission unit 31 and the microwave reception unit 32.

[0034] Conditions such as the wavelength of the microwaves used and the distance between the microwave transmitting unit 31 and the microwave receiving unit 32 can be set appropriately depending on the brand and type of coal C. Furthermore, a comparison of transmitted and received microwaves of a plurality of frequencies (wavelengths) may be performed to obtain the amount of change for each frequency (i.e., frequency characteristics).

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

[0036] In addition, the coefficient K Φ , K A , K Cmay be a coefficient that is determined in advance using many samples of coal C prepared in advance. Specifically, the coefficient K is determined by the following procedure. Φ , K A , K C can be determined in advance. That is, for a plurality of samples (at least three or more samples of coal C) prepared in advance, the moisture content M is calculated based on the JIS standard (analytical moisture content) JIS M 8811: 2000 Coals and cokes - Method for determining total moisture content of a lot. In addition, the phase difference Φ, attenuation factor A, and transport amount Q are also measured for these samples. Then, the coefficient K in the above formula (1) is calculated based on the moisture content M, phase difference Φ, attenuation factor A, and transport amount Q for these samples. Φ , K A , K C Determine.

[0037] In Fig. 1, the coal C is measured by the microwave W after passing through the conveyed amount measuring unit 2, but the conveyed amount may be measured by the conveyed amount measuring unit 2 after the measurement by the microwave W. In either order, the moisture content calculation unit 4 aligns the measurement data so that the position where the measurement was made by the microwave W coincides with the position where the conveyed amount was measured.

[0038] Next, a moisture measuring method using the moisture measuring device 1 configured as above will be described. FIG. 2 is a flowchart showing a moisture measuring method using the moisture measuring device of FIG. First, the transport amount of coal C on the belt conveyor B is measured (transport amount measurement process; step ST1). The transport amount of coal C can be measured by measuring the coal weight in the measurement range L by the load detection 21 of the transport amount measurement unit 2, measuring the movement speed of the belt conveyor B by the speed detection unit 22, and multiplying the measured coal weight by the movement speed of the belt conveyor B in the transport amount calculation unit 23.

[0039] Next, microwaves are transmitted as transmission waves toward the coals C on the belt conveyor B (microwave transmission step; step ST2). The microwaves are transmitted by a microwave transmitter 31 made of, for example, a horn antenna. The microwave transmitter 31 transmits microwaves W of a predetermined power and phase.

[0040] Then, the microwaves that have been transmitted and passed through the coal C are received as received waves (microwave receiving step; step ST3). The microwaves are received by the microwave receiving unit 32, which is made up 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 one or both of a phase difference and an attenuation rate (power ratio).

[0042] Next, the moisture content of the coal C is calculated based on the change in the microwave calculated in step ST4 and the transport amount of the coal C 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 based on the above-mentioned formula (1).

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

[0044] According to this embodiment, by performing the conveyance amount measuring step of step ST1, the moisture content of the 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 the conventional technology, the formula for calculating the moisture content of coal C includes the bulk density and layer thickness as variables, and at least one of these needs to be measured or kept constant, but in the present embodiment, the conveyed amount is used as a variable in the formula for calculating the moisture content of coal C, so there is no need to measure the bulk density or layer thickness. Therefore, there is no need to install a measuring device with high management costs, such as a gamma ray facility for measuring bulk density, or an additional device for measuring layer thickness, which reduces the cost of the device and simplifies the device itself.

[0046] In addition, in this embodiment, there is no need for a fixed scraper or the like to keep the bulk density constant, so the coal C is not thrown off the belt conveyor B and stable moisture measurement can be performed.

[0047] <Second embodiment> 3 is a side view showing a schematic diagram of an example of a moisture measuring device according to a second embodiment of the present invention. The moisture measuring device according to the second embodiment is obtained by adding a leveling mechanism to the moisture measuring device according to the first embodiment. The moisture measuring device according to the second embodiment is the same as the first embodiment except for the addition of the leveling mechanism, so that the other components are denoted by the same reference numerals as in the first embodiment and will not be described.

[0048] FIG. 4 is a side view showing an example of the smoothing mechanism of the second embodiment, and FIG. 5 is a cross-sectional view of the smoothing mechanism of FIG. 4 seen from the opposite direction of the conveying direction V (downstream side of the conveyor B). As shown in these figures, the smoothing mechanism 5 of this example is a mechanism for smoothing the surface unevenness by pre-pressing the coal C on the belt conveyor B, and moves up and down following the fluctuation of the layer thickness of the coal C. The smoothing mechanism 5 is composed of a roller 51 for pre-pressing the coal C on the belt conveyor B and a pair of arms 52 for holding it. As shown in FIG. 5, the roller 51 is arranged with its rotation shaft 51a parallel to the width direction of the belt conveyor B. The rotation shaft 51a of the roller 51 is held by the arm 52. The arm 52 extends obliquely upward from the rotation shaft 51a, and its upper end is rotatably held by the shaft 53, and is configured to be swingable with respect to the shaft 53 as shown in FIG. Then, the roller 51 can move up and down by swinging the arm 52. The rollers 51 compress the coal C transported on the belt conveyor B from above to level the surface of the coal C. The rollers 51 move up and down in accordance with the fluctuations in the surface height of the coal C. Since the compression by the rollers 51 is performed by the own weight of the rollers 51, it is preferable to use rollers 51 that have a sufficient weight to level the surface of the coal C.

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

[0050] The weight 54 is shaped like a warp, with a bottom surface that is in contact with the coal C on the belt conveyor B and is 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 traveling direction of the belt conveyor B (the direction of the arrow V in the figure). The inclined surface 54c guides the conveyed coal C to the bottom of the weight 54.

[0051] The pair of first arms 55a have their lower ends rotatably connected to the weight 54 via the shaft 54a, and the pair of second arms 55b have their lower ends rotatably connected to the weight 54 via the shaft 54b. The first arm 55a and the second arm 55b extend parallel to each other obliquely upward from their lower ends connected by the shafts 54a and 54b. The upper ends of the pair of first arms 55a are held by the first shaft 56a, and the upper ends of the pair of second arms 55b are held by the second shaft 56b. The first arm 55a and the second arm 55b are configured to be swingable relative to the first shaft 56a and the second shaft 56b, and by swinging the first arm 55a and the second arm 55b, the weight 54 can move up and down while keeping the bottom surface of the weight 54 parallel to the belt conveyor B. The weight 54 presses down on the coal C transported on the belt conveyor B from above to compress it and level the surface of the coal C, while moving up and down in accordance with the fluctuation in the surface height of the coal C. Since the compression by the weight 54 is performed by the weight of the weight 54 itself, it is preferable to use a weight 54 that is heavy enough to compress the coal C. The load may be adjusted by adding an additional weight on top of the weight 54.

[0052] Fig. 8 is a side view showing a schematic diagram of yet another example of the leveling mechanism, and Fig. 9 is a cross-sectional view of the leveling mechanism of Fig. 8 as viewed from the opposite direction to the conveying direction V (the downstream side of the conveyor B). The leveling mechanism 5" of this example has a plate 57 that functions as a weight for pre-pressing the coal C on the belt conveyor B, and a shaft 58 that supports the plate 57 so that it can swing.

[0053] The plate 57 is curved with a bottom surface that is in contact with the coal C on the belt conveyor B and is approximately parallel to the belt conveyor B, and an inclined surface 57a that curves upward from the bottom surface on the upstream side of the traveling direction of the belt conveyor B (the direction of the arrow V in the figure), and the inclined surface 57a guides the coal C being transported to the bottom of the plate 57. The upstream tip of the plate 57 is held by the shaft 58 and is adapted to swing relative to the shaft 58. The plate 57 moves up and down following the fluctuation of the surface height of the coal C while pressing down and compressing the coal C transported on the belt conveyor B from above and leveling the surface of the coal C. The plate 57 is pressed down by its own weight, so it is preferable to use a plate 57 that has a weight sufficient to compress the coal C. The load may be adjusted by adding an additional weight on the plate 57.

[0054] In this embodiment, by providing any one of the leveling mechanism 5, the leveling mechanism 5', and the leveling mechanism 5" to the first embodiment, the unevenness of the surface of the coal C is leveled and made flat, thereby suppressing refraction and scattering on the surface of the coal C when the microwave W passes through the coal C, and reducing fluctuations in the value of the change amount (phase difference, attenuation rate) calculated by the microwave change amount calculation unit 3. As a result, there is an effect of stabilizing the moisture measurement.

[0055] Although the embodiments of the present invention have been described above, these are merely examples and should not be considered as limiting. 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 is used as an example of the measurement object for measuring moisture content, but the measurement object is not limited to coal as long as the moisture content can be measured. Also, in Fig. 1 and Fig. 3, the belt conveyor B is continuous from the hopper H to the position where the microwave W passes through, but the coal C may be transported by transferring between multiple belt conveyors.

[0057] In some cases, a feeder is used in which the speed v of the belt conveyor B immediately below the hopper H is controlled based on the measured value of the conveying amount measuring unit 2 so that the conveying amount Q of the coal C is constant (conveying amount set value Qs). In this case, in the calculation formula (1) of the moisture content M in the moisture content calculation unit 4, the conveying amount set value Qs may be used instead of the conveying amount Q (measured value).

[0058] Furthermore, in the second embodiment, three examples of the leveling mechanism are shown, but the mechanism is not limited to these as long as it can level the surface of the coal while pressing down and compressing the coal from above. EXAMPLES

[0059] Examples will be described below. Here, we confirmed the effect of the transport amount measurement process in the moisture measuring device of the first embodiment. Fig. 10 is a diagram showing the relationship between the moisture content of coal measured 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 the moisture content on the vertical axis is not corrected by the transport amount of coal, and (b) shows the case where the moisture content on the vertical axis is corrected by the transport amount of coal.

[0060] Specifically, the vertical axis of FIG. 10(a) is the moisture content calculated from the calibration curve created by performing multiple regression analysis according to the above formula (1) on the microwave phase difference, attenuation rate, and moisture content measured by the drying method, without considering the coal transport amount Q as a constant value, and the vertical axis of FIG. 10(b) is the moisture content calculated from the calibration curve created by performing multiple regression analysis according to the above formula (1) while taking into account the coal transport amount Q. In addition, in the drying method used in this embodiment, a coal sample of about 5 g was dried at 110°C for several minutes until there was no weight change, and the moisture content was calculated from the weight change before and after drying. The data on the horizontal axis is the moisture content averaged over three measurements. In addition, the moisture content measured by microwave measurement on the vertical axis was evaluated using a leave-one-out cross-validation method. In other words, each data is a value calculated from a calibration curve created by multiple regression analysis from other data. In addition, the diagonal dashed lines in the plots of Figures 10(a) and (b) indicate the lines where the moisture contents on the vertical and horizontal axes are equal.

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

[0062] 1. Moisture measuring device 2. Transport amount measurement section 4 Moisture content calculation section 5, 5´, ​​5″ leveling mechanism 21 Load detection unit 22 Speed ​​detection section 23 Transport amount calculation unit 31 Microwave transmitter 32 Microwave receiving section 33 Microwave change amount calculation section 51 Roller 51a Rotation axis 52, 55a, 55b Arms 53, 56a, 56b, 58 Shaft 54 Weight 54a, 54b axis 57 Plate B Belt conveyor C Coal H Hopper

Claims

1. A moisture measurement method for measuring the moisture content of a test object transported on a conveyor, comprising the steps of: a conveyance amount measuring step of measuring a conveyance weight per unit time of the objects to be measured conveyed on the conveyor; a microwave transmitting step of transmitting a microwave as a transmission wave toward the object to be measured; a microwave receiving step of receiving, as a received wave, the microwave transmitted in the microwave transmitting step and having passed through the object to be measured; a microwave change amount calculation step of calculating a change amount by comparing the transmitted wave with the received wave; a moisture content calculation step of calculating a moisture content of the object based on the change amount calculated in the microwave change amount calculation step and the transported weight per unit time of the object measured in the transport amount measurement step; A moisture measurement method comprising:

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

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

4. The moisture measuring method according to claim 1 or 2, wherein a plurality of frequencies are used as the microwaves.

5. 3. The moisture measuring method according to claim 1, further comprising a smoothing step of pressing down the objects on the conveyor to smooth out surface irregularities of the objects prior to the microwave transmitting step.

6. A moisture measuring device for measuring the moisture content of a test object transported on a conveyor, comprising: a conveyance amount measuring unit that measures a conveyance weight per unit time of the object to be measured conveyed on the conveyor; a microwave transmission unit that transmits a microwave as a transmission wave toward the object to be measured; a microwave receiving unit that receives the microwave transmitted from the microwave transmitting unit and transmitted through the object to be measured as a received wave; a microwave change amount calculation unit that compares the transmitted wave with the received wave to calculate an amount of change; a moisture content calculation unit that calculates a moisture content of the object to be measured based on the amount of change calculated by the microwave change amount calculation unit and the transported weight per unit time of the object to be measured measured by the transport amount measurement unit; A moisture measuring device comprising:

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

8. 8. The moisture measuring device according to claim 6, further comprising a smoothing mechanism for pressing down the objects to be measured on the conveyor and smoothing out surface irregularities of the objects to be measured, the smoothing mechanism being provided upstream of the position on the conveyor where the microwaves pass through the objects to be measured.

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

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

11. A moisture control method comprising: measuring the moisture content of the object to be measured by the moisture measurement method described in claim 1; and controlling the moisture content of the object to be measured by drying or adding water based on the measured moisture content so that the moisture content of the object falls within a set range.

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

13. A method for producing coke, comprising charging the coal, which is the object to be measured and whose humidity has been adjusted by the humidity adjustment method according to claim 12, into a coke oven to produce coke.

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