Method for Measuring Moisture Content, Moisture Content Measuring Device, and Method for Producing Coke

Abstract

Provided are: a water content measurement method capable of reliably measuring a water content of a measured object, even when a layer thickness of the measured object fluctuates; a water content measurement device; and a manufacturing method for coke.　The water content measurement method includes: a microwave measurement step of, when transmitted microwaves are transmitted to a measured object S by a microwave transmission unit 11 that moves relative to the measured object S, receiving, by using a microwave reception unit 12, the transmitted microwaves that have passed through the measured object S as received microwaves, and finding the attenuation thereof and the phase difference between the transmitted microwaves and the received microwaves; a bulk density calculation step of calculating an amount of the measured object S, a movement speed of the measured object S relative to the microwave transmission unit 11, and the bulk density of the measured object S on the basis of the layer thicknesses of the measured object S; and a water content calculation step of calculating a water content of the measured object S using the phase difference, the attenuation, and the bulk density measured by a microwave evaluation unit 13.

Description

Technical Field

[0001] The present invention relates to a water content measurement method and a water content measurement device for measuring the water content of an object to be measured using microwaves, and a method for manufacturing coke.

Background Art

[0002] In a steel mill, coal used as a raw material for coke is transported by a belt conveyor, dried by a humidifying machine, and then charged into a coke oven. Generally, the lower the water content of the coal, the better the quality of the coke. However, if the water content of the coal is too low, problems such as an increase in the amount of coal dust generated during transportation, the risk of ignition, and clogging of the coke oven may occur. Therefore, it is necessary to control the water content of the coal within a predetermined range.

[0003] As a technique for measuring the water content of coal, a technique using microwaves is known. In this technique, coal on a belt conveyor is irradiated with microwaves, and the water content of the coal is measured based on changes in the propagation characteristics of the microwaves in the coal. In addition, in this technique for measuring the water content of coal using microwaves, information on the bulk density of the coal is required. Usually, the bulk density is measured by utilizing the property that gamma rays, which are a type of radiation, are attenuated when passing through a substance. However, gamma rays are strictly regulated in terms of handling, and the method of measuring the bulk density using gamma rays incurs high management costs.

[0004] Therefore, a method has been proposed in which the water content is measured by microwaves in a state where the bulk density of the coal is physically made constant (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses that a scraper is used to physically level the surface of the coal on a belt conveyor to make the bulk density uniform. Patent Document 2 discloses a method of measuring the water content of coal without being affected by fluctuations in the bulk density by using a water meter embedded in the coal layer.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 7-55726 [Patent Document 2] Japanese Patent No. 6075044 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] In both cases of Patent Documents 1 and 2, it is premised that the layer thickness of the object to be measured has a layer thickness of a certain value or more. That is, when the layer thickness of the object to be measured is too thin, there is a possibility that the scraper does not hit the coal and the bulk density cannot be made constant, or the moisture meter does not come into contact with the object to be measured. On the other hand, when the layer thickness of the object to be measured is too thick, there is a possibility that the scraper or the measuring device collides with the object to be measured, and the collided object to be measured falls from the belt conveyor.

[0007] An object of the present invention is to provide a moisture content measuring method, a moisture content measuring device, and a method for producing coke that can surely measure the moisture content of an object to be measured even when the layer thickness of the object to be measured varies in order to solve the above problems. [Means for Solving the Problems]

[0008] [1] A moisture content measuring method for measuring the moisture content of an object to be measured, comprising: a microwave measuring step of transmitting a transmitted microwave to the object to be measured by a microwave transmitting unit that moves with respect to the object to be measured, receiving the transmitted microwave that has passed through the object to be measured as a received microwave by a microwave receiving unit, and obtaining a phase difference and an attenuation rate between the transmitted microwave and the received microwave; a bulk density calculating step of calculating the bulk density of the object to be measured based on the amount of the object to be measured, the moving speed of the object to be measured with respect to the microwave transmitting unit, and the layer thickness of the object to be measured; and a moisture content calculating step of calculating the moisture content of the object to be measured based on the phase difference and the attenuation rate between the transmitted microwave and the received microwave and the bulk density. [2] The bulk density is Q (kg / m3 ) Let the phase difference between the transmitted microwave and the received microwave be φ (deg), the attenuation rate be A (dB), the layer thickness of the object to be measured be D (m), and the coefficient be K φ , K A , K C When the moisture content W (mass %) of the object to be measured S is calculated by the following formula (2), it is the moisture content measurement method described in [1]. W = (K φ ×φ + K A ×A) / (Q×D) + K C ···(2) [3] The object to be measured is coal, and it is the moisture content measurement method described in [1] or [2]. [4] Measure the moisture content of coal by the moisture content measurement method described in any one of [1] to [3], and based on the measured moisture content, dry the coal so that the moisture content falls within the set range, transport the dried coal to a coke oven, and charge the dried coal into the coke oven for carbonization to produce coke. It is a method for producing coke. [5] A moisture content measurement device for measuring the moisture content of an object to be measured, which is configured to move relative to the object to be measured, and includes a microwave transmission unit that transmits a transmitted microwave to the object to be measured, a microwave reception unit that receives the transmitted microwave transmitted through the object to be measured as a received microwave, and a microwave evaluation unit that obtains the phase difference and attenuation rate between the transmitted microwave and the received microwave. A microwave evaluation unit, a bulk density calculation unit that calculates the bulk density of the object to be measured based on the amount of the object to be measured, the moving speed of the object to be measured relative to the microwave transmission unit, and the layer thickness of the object to be measured, and the phase difference and attenuation rate measured by the microwave evaluation unit. And a moisture content calculation unit that calculates the moisture content of the object to be measured based on the bulk density calculated by the bulk density calculation unit. It is a moisture content measurement device.

Advantages of the Invention

[0009] According to the present invention, even when the layer thickness of the object to be measured fluctuates, the moisture content can be reliably measured.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a preferred embodiment of the water content measuring device of the present invention. The water content measuring device 1 in FIG. 1 measures the water content of coal, which is an object to be measured S supplied onto the belt conveyor 3 from, for example, a cutting device 2. The coal whose water content has been measured is conveyed by the belt conveyor 3 to a humidifying machine (not shown) located on the downstream side of the water content measuring device 1 in the conveying direction. In the humidifying machine, the coal is dried so that the water content of the coal falls within a set range based on the water content measured by the water content measuring device 1 shown in FIG. 1. Thereafter, the dried coal is charged into a coke oven (not shown) and coked to produce coke. In the embodiment of the present invention, the belt conveyor 3 is exemplified as an example of the conveying device, but it is not limited thereto, and a roller conveyor may be used.

[0012] The water content measuring device 1 includes a microwave evaluation unit 10, a bulk density calculation unit 20, and a water content calculation unit 30. The microwave evaluation unit 10 transmits microwaves to the object to be measured S, and obtains the phase difference and attenuation rate between the transmitted microwaves and the microwaves transmitted through the object to be measured S. The bulk density calculation unit 20 calculates the bulk density of the object to be measured S. The water content calculation unit 30 calculates the water content of the object to be measured S. Specifically, the microwave evaluation unit 10 includes a microwave transmission unit 11, a microwave reception unit 12, and a microwave evaluation unit 13. The microwave transmission unit 11 irradiates transmitted microwaves to the object to be measured S on the belt conveyor 3. The microwave reception unit 12 receives the transmitted microwaves transmitted through the object to be measured S as received microwaves. The microwave evaluation unit 13 obtains the phase difference and attenuation rate between the transmitted microwaves and the received microwaves.

[0013] The microwave transmission unit 11 and the microwave reception unit 12 each consist of, for example, an antenna, and are positioned at positions facing each other with the object to be measured S in between. The wavelength of the microwaves and the distance between the microwave transmission unit 11 and the microwave reception unit 12, etc. can be appropriately set according to the type of the object to be measured S (the brand of coal). The microwave evaluation unit 13 consists of, for example, hardware resources such as a computer. The microwave evaluation unit 13 is connected to the microwave transmission unit 11 and the microwave reception unit 12 via cables respectively, and controls the operations of the microwave transmission unit 11 and the microwave reception unit 12. Specifically, the microwave evaluation unit 13 causes the microwave transmission unit 11 to transmit transmitted microwaves with a predetermined energy and a predetermined phase. Also at that time, it acquires the phase and energy of the received microwaves received by the microwave reception unit 12. Then, the microwave evaluation unit 13 calculates the phase difference and attenuation rate between the transmitted microwaves and the received microwaves.

[0014] The bulk density calculation unit 20 consists of hardware resources such as a computer. The bulk density calculation unit 20 acquires the supply amount of the object S to be measured to the belt conveyor 3, the conveyance speed of the object S to be measured by the belt conveyor 3, and the layer thickness of the object S to be measured on the belt conveyor 3, and calculates the bulk density of the object S to be measured based on these. The bulk density calculation unit 20 acquires the supply amount of the object S to be measured from, for example, the cutting device 2 that supplies the object S to be measured onto the belt conveyor 3. Also, the bulk density calculation unit 20 acquires the conveyance speed of the object S to be measured from, for example, the conveyance control device that controls the belt conveyor 3. The conveyance speed of the object S to be measured by the above-described belt conveyor 3 corresponds to the moving speed of the object to be measured in the present embodiment.

[0015] The layer thickness of the object S to be measured on the belt conveyor 3 is measured by the layer thickness measuring device 21. The layer thickness measuring device 21 is installed above the object S to be measured and, for example, upstream of the microwave transmitting unit 11 and the microwave receiving unit 12 in the belt conveyor 3. That is, in the conveyance direction of the object S to be measured by the belt conveyor 3, the cutting device 2, the layer thickness measuring device 21, and the microwave transmitting unit 11 are installed in this order from the upstream side. The layer thickness measuring device 21 irradiates the object S to be measured on the belt conveyor 3 with ultrasonic waves, lasers, etc. from above, and measures the distance from the layer thickness measuring device 21 to the object S to be measured in a non-contact manner. Specifically, the distance to the belt conveyor 3 is stored in the layer thickness measuring device 21. Then, the layer thickness measuring device 21 calculates the layer thickness of the object S to be measured on the belt conveyor 3 using the distance from the layer thickness measuring device 21 to the belt conveyor 3 and the distance from the layer thickness measuring device 21 to the object S to be measured.

[0016] The bulk density calculation unit 20 uses the cut-off amount M (kg / s) per unit time of the object S to be measured, the conveyance speed V (m / s) of the object S to be measured by the belt conveyor 3, the layer thickness D (m) of the object S to be measured, and the width Wcb (m) of the belt conveyor 3 to obtain the bulk density Q (kg / m 3 ) of the object S to be measured on the belt conveyor 3 based on the following formula (1). Although not shown in detail, the following formula (1) is for the bulk density Q (kg / m 3) is calculated. That is, the width of the object S to be measured on the belt conveyor 3 is approximately the same as the width Wcb of the belt conveyor 3.

[0017] Q = M / (V × D × Wcb) ···(1)

[0018] When the belt conveyor 3 is a three-roll curved belt conveyor 3' as shown in FIG. 2, the width of the object S to be measured is considered to be approximately proportional to the approximate layer thickness D'. The approximate layer thickness D' means the layer thickness at the center of the object S to be measured in the width direction of the belt conveyor 3'. Therefore, the following formula (1') is adopted instead of formula (1).

[0019] Q = M / {V × D' × (α × D')} ···(1')

[0020] However, α is a proportional coefficient determined by the cross-sectional shape of the curved belt conveyor 3', and (α × D') is the equivalent width when the cross-section of the object S to be measured on the curved belt conveyor 3' is replaced with a rectangle having the same cross-sectional area and a height of D'. Hereinafter, the layer thickness D of the object to be measured and the approximate layer thickness D' are used as the layer thickness D without distinction.

[0021] The moisture content calculation unit 30 is composed of hardware resources such as a computer, for example, and calculates the moisture content of the object S to be measured using the phase difference measured by the microwave evaluation unit 13, the attenuation rate, and the bulk density Q calculated by the bulk density calculation unit 20. Here, when the layer thickness of the object S to be measured is D (m), the phase difference is φ (deg), the attenuation rate is A (dB), and the bulk density is Q (kg / m 3 ) and the moisture content W (mass%) of the object S to be measured is calculated by the following formula (2).

[0022] W = (K φ × φ + K A × A) / (Q × D) + K C ···(2)

[0023] The K in formula (2) φ , K A , and K Cis a coefficient, which is preset according to the type of the object to be measured S (the brand of coal), the distance between the microwave transmitting unit 11 and the microwave receiving unit 12, the material of the belt conveyor 3, the thickness of the belt conveyor 3, and the like. Thereby, even when the layer thickness D of the object to be measured S varies greatly, the moisture content W of the object to be measured S can be surely measured without dropping the object to be measured S from the belt conveyor 3. Note that the above K φ , K A , and K C are determined in advance by measuring JIS analysis moisture, phase difference φ, attenuation rate A (dB), bulk density Q, etc. for a coal sample whose moisture content has been measured in advance a plurality of times (three or more points, the same number as the variables).

[0024] With reference to FIG. 1, the operation of the preferred embodiment of the moisture content measurement method of the present invention will be described. First, the object to be measured S is cut out onto the belt conveyor 3 from the cutting device 2 and is transported, for example, toward the humidifying machine. At this time, in the bulk density calculation unit 20, the supply amount M of the object to be measured S to the belt conveyor 3 and the transport speed V of the object to be measured S by the belt conveyor 3 are acquired at any time. Further, when the object to be measured S is transported to the position of the layer thickness measuring device 21, the layer thickness D of the object to be measured S on the belt conveyor 3 is measured by the layer thickness measuring device 21. Then, based on the supply amount (cut-out amount) M of the object to be measured S, the transport speed V of the object to be measured S by the belt conveyor 3, the layer thickness D, and the width Wcb of the belt conveyor 3, the bulk density Q of the object to be measured S on the belt conveyor 3 is calculated (bulk density calculation step).

[0025] In this embodiment, the layer thickness measuring device 21 is located on the downstream side of the cutting device 2 in the conveying direction of the object S to be measured by the belt conveyor 3. Therefore, there is a time lag between the time when the object S to be measured is supplied by the cutting device 2 onto the belt conveyor 3 and the time when the layer thickness D of the object S to be measured on the belt conveyor 3 is measured by the layer thickness measuring device 21. Accordingly, the above-mentioned respective time points, the time lag, and the conveying speed V of the object S to be measured by the belt conveyor 3 are input as tracking information to the bulk density calculation unit 20. Then, based on the tracking information, the bulk density Q of the object S to be measured calculated by the bulk density calculation unit 20 is corrected. Alternatively, considering the above-mentioned time lag, the layer thickness D of the object S to be measured on the belt conveyor 3 is measured by the layer thickness measuring device 21, and the measured value is input to the bulk density calculation unit 20.

[0026] Next, the object S to be measured on the belt conveyor 3 whose bulk density Q has been measured is irradiated with transmitted microwaves by the microwave transmitting unit 11, and the transmitted microwaves that have passed through the object S to be measured are received as received microwaves by the microwave receiving unit 12. Then, the phase difference φ and the attenuation rate A between the transmitted microwaves and the received microwaves are obtained (microwave measurement step). Thereafter, in the moisture content calculation unit 30, using the phase difference φ and the attenuation rate A measured by the microwave evaluation unit 13 and the bulk density Q calculated by the bulk density calculation unit 20, the moisture content W of the object S to be measured is calculated by the above formula (2) (moisture content calculation step).

[0027] The microwave transmitter 11 and the microwave receiver 12 are located on the downstream side of the cutting device 2 and the layer thickness measuring device 21 in the conveying direction of the object S to be measured by the belt conveyor 3. Therefore, there is a time lag between the time when the layer thickness D of the object S to be measured on the belt conveyor 3 is measured by the layer thickness measuring device 21 and the time when the transmitted microwave is transmitted and received by the microwave transmitter 11 and the microwave receiver 12. Accordingly, each of the above-described time points, the time lag, and the conveying speed V of the object S to be measured by the belt conveyor 3 are input to the moisture content calculation unit 30 as tracking information. Then, based on the tracking information, the moisture content W of the object S to be measured calculated by the moisture content calculation unit 30 is corrected. Alternatively, the moisture content calculation unit 30 calculates the moisture content W by transmitting the transmitted microwave from the microwave transmitter 11 to the object S to be measured in consideration of the above-described time lag.

[0028] According to the present embodiment, the bulk density Q of the object S to be measured can be calculated in real time based on each tracking information and the layer thickness D of the object S to be measured on the belt conveyor 3 measured non - contact. Then, the water content W can be calculated or measured based on the measured bulk density Q. Therefore, it is not necessary to physically perform a process of making the bulk density Q of the object S to be measured constant. That is, according to the water content measurement method and the water content measurement device 1 according to the present embodiment, even when the layer thickness D of the object S to be measured on the belt conveyor 3 is small, the water content W can be surely and accurately measured. Specifically, in the method described in Patent Document 1 mentioned above, when the layer thickness of the coal placed on the belt conveyor is small and the upper end of the coal does not contact the scraper, the bulk density cannot be made uniform. Therefore, it may not be possible to accurately measure the water content of the coal. However, in the water content measurement method and the water content measurement device 1 according to the present embodiment, the water content W can be accurately measured regardless of the layer thickness D of the object S to be measured. Also, in the water content measurement method and the water content measurement device 1 according to the present embodiment, since there is no need to provide a scraper, the coal does not collide with the scraper. Therefore, the object S to be measured does not fall from the belt conveyor 3, or the fall of the object S to be measured can be suppressed, and in that state, a highly accurate water content measurement result can be continuously obtained. Then, the coal is transported by the belt conveyor 3 to a humidifying machine (not shown). And in the humidifying machine, based on the water content measured by the water content measurement device 1 shown in FIG. 1, the coal is dried so that the water content of the coal falls within the set range. The coal thus dried is charged into a coke oven (not shown) and coked to produce coke. Note that the above - described coke production method corresponds to the coke production method in the present embodiment.

Example

[0029] An example conducted to confirm the accuracy of the moisture content measured by the moisture content measuring device 1 in Fig. 1 will be described. In the example, the moisture content of coal was measured using a measuring device that simulated a state in which about 6 kg of coal was cut out on a belt conveyor 3 with a conveying speed of 3 m / s. Specifically, a container with a width of 30 cm was prepared and placed on waste materials that would serve as a substitute for the belt conveyor 3. Then, 6 kg of coal was loaded into the container using a device that simulated the cutting device 2, and the distance to the bottom of the container and the distances to the surfaces of the coal at the four corners of the container were measured by the layer thickness measuring device 21. The layer thicknesses of the coal at the four corners of the container were calculated, and the average value of the layer thicknesses at the four corners was taken as the overall layer thickness. Then, the bulk density was calculated by the bulk density calculation unit 20 using the conveying speed, layer thickness, and weight.

[0030] On the other hand, the microwave transmitting unit 11 and the microwave receiving unit 12 were arranged so as to sandwich the container containing coal and the waste materials, and microwave transmission and reception were performed. Then, the phase difference and the attenuation rate were calculated by the microwave evaluation unit 13. And in the moisture content calculation unit 30, the moisture content W was calculated based on the above formula (2).

[0031] Fig. 3 is a graph showing the relationship between the moisture content measured using the simulation device of the moisture content measuring device in Fig. 1 and the moisture content measured by the JIS analysis method. In Fig. 3, the moisture contents of 6 coal grades used in coke production as the object to be measured S were determined by the above method. As shown in Fig. 3, the moisture content measured by the moisture content measuring device 1 in Fig. 1 was almost the same as the moisture content determined by the JIS analysis method, and it was confirmed that high-precision moisture content measurement was possible.

[0032] Embodiments of the present invention are not limited to the above embodiments and various modifications can be made. In the above embodiment, transmitted microwaves are transmitted to the object S being conveyed by the belt conveyor 3 to measure the water content W of the object S being measured. However, alternatively, the object S being measured may be placed substantially linearly on a predetermined placement portion, and the microwave transmitting unit 11 and the microwave receiving unit 12 may be moved along the length direction of the object S placed substantially linearly to measure the water content of the object S being measured. That is, it is sufficient that the object S being measured, the microwave transmitting unit 11, and the microwave receiving unit 12 are configured to be relatively movable. Even with such a configuration, substantially the same operations and effects as those of the above-described embodiment can be obtained. Further, for example, in the above embodiment, the object S being measured is coal, and the case of measuring the water content in the process of producing coke is exemplified, but it is not limited thereto. The object S being measured may be, for example, any material including water other than iron ore and sintered ore.

Explanation of Signs

[0033] 1 Water content measuring device 2 Cutting device 3, 3’ Belt conveyor 10 Microwave evaluation unit 11 Microwave transmitting unit 12 Microwave receiving unit 13 Microwave evaluation unit 20 Bulk density calculation unit 21 Layer thickness measuring device 30 Water content calculation unit S Object being measured

Claims

1. A moisture content measurement method for measuring the moisture content of a measurement object cut out onto a belt conveyor from a cutting device, comprising: When a transmission microwave is transmitted to the measurement object by a microwave transmission unit moving with respect to the measurement object, the transmission microwave transmitted through the measurement object is received as a reception microwave by a microwave reception unit, and a microwave measurement step of obtaining a phase difference and an attenuation rate between the transmission microwave and the reception microwave; A bulk density calculation step of calculating the bulk density of the measurement object based on the amount of the measurement object, the moving speed of the measurement object with respect to the microwave transmission unit, the layer thickness of the measurement object, and the width of the belt conveyor; A moisture content calculation step of calculating the moisture content of the measurement object based on the phase difference and the attenuation rate between the transmission microwave and the reception microwave and the bulk density; In the bulk density calculation step, a moisture content measurement method in which the cut-out amount of the measurement object per unit time cut out onto the belt conveyor from the cutting device is obtained from the cutting device and used as the amount of the measurement object.

2. Let the bulk density be Q (kg / m ３ ), the phase difference between the transmitted microwave and the received microwave be φ (deg), the attenuation rate be A (dB), the layer thickness of the object to be measured be D (m), and the coefficients be Kφ, KA, and KC. The water content W (mass %) of the object to be measured S is calculated by the following formula (2). The water content measurement method according to claim 1. W = (Kφ×φ + KA×A) / (Q×D) + KC... (2)

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

4. Measuring the moisture content of coal by the moisture content measurement method described in claim 1, Based on the measured moisture content, drying the coal so that the moisture content falls within a set range, Transporting the dried coal to a coke oven, A method for producing coke, comprising charging the dried coal into a coke oven and carbonizing it to produce coke.

5. Measuring the moisture content of coal by the moisture content measurement method described in claim 2, Based on the measured moisture content, drying the coal so that the moisture content falls within a set range, Transporting the dried coal to a coke oven, A method for producing coke, comprising charging the dried coal into a coke oven and carbonizing it to produce coke.

6. Measuring the moisture content of coal by the moisture content measurement method described in claim 3, Based on the measured moisture content, drying the coal so that the moisture content falls within a set range, Transporting the dried coal to a coke oven, A method for producing coke, comprising charging the dried coal into a coke oven and carbonizing it to produce coke.

7. A moisture content measurement device for measuring the moisture content of a measurement object cut out onto a belt conveyor from a cutting device, comprising: A microwave evaluation unit configured to move relative to the object to be measured, comprising a microwave transmitter that transmits a transmission microwave to the object to be measured, a microwave receiver that receives the transmission microwave transmitted through the object to be measured as a reception microwave, and a microwave evaluation unit that obtains a phase difference and an attenuation rate between the transmission microwave and the reception microwave. A bulk density calculation unit that calculates the bulk density of the object to be measured based on the amount of the object to be measured, the moving speed of the object to be measured relative to the microwave transmitter, the layer thickness of the object to be measured, and the width of the belt conveyor. A moisture content calculation unit that calculates the moisture content of the object to be measured based on the phase difference and the attenuation rate measured by the microwave evaluation unit and the bulk density calculated by the bulk density calculation unit. In the bulk density calculation unit, a moisture content measuring device that obtains the amount of the object to be measured cut out per unit time from the cutting device onto the belt conveyor from the cutting device and uses it as the amount of the object to be measured.

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