A coal moisture content detection and control system and method based on a microwave method for a mine conveyor

Abstract

The application discloses a coal moisture content detection and control system and method based on a microwave method on a mine conveyor. The application adopts a microwave detection means, transmits a microwave signal to the conveyor, receives and converts the detection signal into a voltage signal for processing, has good reliability, high precision, strong anti-interference ability, and is easy to realize non-contact, real-time and lossless rapid detection of coal. The moisture content model takes the microwave voltage and the material level voltage as inputs, estimates the moisture content, and compensates the influence of the coal height on the moisture content estimation result. By fusing moisture content data of multiple positions, the average moisture content result in the detection interval is obtained, which can more accurately reflect the average level of the moisture content in the detection interval. When the coal moisture content is lower than the lower limit requirement of the coal moisture content, the spraying time model is used to calculate the spraying time, and the moisture content in the detection interval is accurately controlled. The application realizes real-time detection and control of the coal moisture content on the mine conveyor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal moisture content detection and control on mine conveyors, and particularly relates to a coal moisture content detection and control system and method based on a microwave method on mine conveyors. BACKGROUND

[0002] The belt conveyor is the most important transport machinery in a coal mine enterprise and belongs to a key fireproof part. Once a fire breaks out, the entire system including the conveyor, control cable, etc. will be scrapped, and even casualties will occur. Coal spontaneous combustion is one of the main causes of conveyor fires. In the production and transportation process, coal forms various oxygen-containing free radicals. Oxygen in the air will react with these free radicals in a physical and chemical manner, thereby releasing a large amount of heat. The moisture in the coal plays a role in isolating oxygen in the air, reduces the oxidation reaction of the coal, and reduces the heat accumulated by the coal, thereby reducing the temperature of the coal. Therefore, maintaining a certain coal moisture content can effectively reduce the probability of a conveyor belt fire accident.

[0003] Therefore, it is of great significance to detect the coal moisture content on the conveyor in real time and complete effective control actions. At present, the detection methods of coal moisture content mainly include the drying method, the electric parameter method, and the near-infrared spectroscopy method.

[0004] The drying method adopts a way of drying and weighing the coal sample, calculates the change in the weight of the coal sample before and after drying, and then obtains the coal moisture content. This method is accurate and reliable, but needs to be completed in a laboratory and has a long cycle, and is not suitable for online detection in the coal mine transportation process. The electric parameter method is designed by using the change of the resistance or capacitance of the coal with the different moisture contents. However, this method needs to process the shape of the coal, and the electric parameter method is easily disturbed by the environment, and has a large measurement error for low moisture content. The near-infrared spectroscopy method uses infrared light to irradiate the coal mine, and converts the coal moisture content by detecting the transmitted light energy. However, the coal contains other substances that easily absorb infrared light, which will obviously interfere with the detection of the moisture content.

[0005] It can be seen that the current several detection methods of coal moisture content all have certain defects when detecting the coal moisture content.

[0006] The microwave method is mainly based on the principle of microwave attenuation. At the microwave frequency, the dielectric constant of water is much larger than that of other substances. The dielectric constant of the coal obviously increases after being mixed with water. The microwave is obviously attenuated after being transmitted through the coal-water mixture. Therefore, the amount of water in the coal can be obtained by detecting the energy of the attenuated microwave. The microwave detection method has the advantages of fast detection speed, easy dynamic detection, high sensitivity, and small environmental sensitivity, and can be applied to the relatively harsh conveyor environment. SUMMARY

[0007] The coal moisture content detection and control system based on the microwave method is used for detecting the coal moisture content by means of the microwave method, and when the coal moisture content is detected to be lower than the lower limit requirement of the coal moisture content, the coal is controlled to be sprayed, and finally the real-time detection and control of the coal moisture content on the mine conveyor are realized.

[0008] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0009] The coal moisture content detection and control system based on the microwave method comprises a detection mechanism, a signal collector, a controller, a weighing mechanism and a spraying mechanism.

[0010] The detection mechanism comprises a plurality of groups of identical detection units, and each group of the detection units comprises a microwave emission module, an isolator, a transmitting antenna, a receiving antenna, a detector, a voltage stabilizing amplifier and an ultrasonic level sensor.

[0011] The microwave emission module, the isolator and the transmitting antenna are sequentially connected; the receiving antenna, the detector and the voltage stabilizing amplifier are sequentially connected, and the voltage stabilizing amplifier and the ultrasonic level sensor are connected with the signal collector.

[0012] The transmitting antenna in each group of the detection units is arranged above the conveyor, and the antenna port of the transmitting antenna faces downward and is vertically aligned with the upper surface of the conveyor; all the transmitting antennas are uniformly arranged in a "one" shape along the direction perpendicular to the transmission of the conveyor.

[0013] The receiving antenna in each group of the detection units is arranged below the conveyor, and the antenna port of the receiving antenna faces upward and is vertically aligned with the lower surface of the conveyor; all the receiving antennas are uniformly arranged in a "one" shape along the direction perpendicular to the transmission of the conveyor.

[0014] The antenna port of the transmitting antenna and the antenna port of the receiving antenna in the same group of the detection units are vertically aligned.

[0015] The ultrasonic level sensor in each group of the detection units is installed at a position parallel to the vertical center line of the transmitting antenna in the same group of the detection units and at a preset distance away from the vertical center line, and the emission head of the ultrasonic level sensor is perpendicular to the upper surface of the conveyor.

[0016] The weighing mechanism comprises a belt conveyor and a weighing instrument; the belt conveyor is located downstream of the conveyor and is used for receiving the coal blocks transmitted by the conveyor; and the weighing instrument is installed at the bottom of the supporting leg of the belt conveyor and is used for weighing the weight of the coal blocks on the belt conveyor.

[0017] The spraying mechanism comprises a water supply pipeline, a water pump, a spraying pipeline and a spray head.

[0018] One end of the water supply pipeline is a water source connection end, the other end is connected with the spray pipeline, and the water pump is arranged on the water supply pipeline; the spray pipeline extends to the upper side of the belt conveyor, and the arrangement direction is perpendicular to the conveying direction of the belt conveyor;

[0019] A plurality of spray heads are arranged on the spray pipeline, and each spray head is vertically oriented to the upper surface of the belt conveyor; all the spray heads are uniformly arranged in a "one" shape along the direction perpendicular to the conveying direction of the belt conveyor;

[0020] The signal collector, the weighing instrument in the weighing mechanism and the water pump in the spraying mechanism are connected with the controller respectively.

[0021] In addition, on the basis of the coal moisture content detection and control system on the mine conveyor based on the microwave method, the application also provides a coal moisture content detection and control method on the mine conveyor based on the microwave method, which adopts the following technical scheme:

[0022] The coal moisture content detection and control method on the mine conveyor based on the microwave method comprises the following steps:

[0023] Step 1. The controller reads the data of the signal collector, including all the microwave voltage data and ultrasonic level voltage data, estimates the coal moisture content at multiple positions through the moisture content model;

[0024] Step 2. The controller reads the data of the signal collector according to a fixed sampling period;

[0025] Step 3. The controller calculates the moisture content of all the microwave voltages and level voltages at N sampling times, fuses the calculated moisture contents to obtain the average coal moisture content result in the detection interval;

[0026] Wherein, N represents the sampling number of the controller in the detection interval;

[0027] Step 4. When the average coal moisture content result in the detection interval is normal, i.e. higher than the lower limit requirement of the coal moisture content, the controller outputs a low voltage signal, and sends the low voltage signal to the water pump, and the water pump remains in a stop state;

[0028] When the average coal moisture content result in the detection interval is lower than the lower limit requirement of the coal moisture content, the controller outputs a high voltage signal, and sends the high voltage signal to the water pump, and the water pump starts to run;

[0029] At the same time, the controller calculates the spraying time of the spraying mechanism according to the spraying time model;

[0030] The controller counts the spraying time calculated by the spraying time model, and once the counting time is reached, the controller outputs a low voltage signal, and sends the low voltage signal to the water pump, and the water pump stops working, thereby completing the control of the coal moisture content.

[0031] The present application has the following advantages:

[0032] As described above, the present application relates to a coal moisture content detection and control system and method on a mine conveyor based on a microwave method. In the present application, a microwave detection method is adopted, microwave signals are emitted to the conveyor, detection signals are received and converted into voltage signals for processing. Compared with existing detection technologies, the microwave detection method has good reliability, high precision, strong anti-interference ability, and is easy to realize non-contact, real-time and non-destructive rapid detection of coal, safe operation and no radiation danger. In addition, the moisture content model designed in the present application takes microwave voltage and level voltage as input to estimate the moisture content, and compensates the influence of coal height on the moisture content estimation result. The present application detects the moisture content data of multiple positions at several sampling times, and obtains the average moisture content result in the detection interval by fusing the moisture content data of multiple positions. The average moisture content result can more accurately reflect the average level of the moisture content in the detection interval. In addition, when the detected coal moisture content is lower than the lower limit requirement of the coal moisture content, the spraying time model in the controller is used to calculate the spraying time, so that the moisture content in the detection interval can be accurately controlled. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a composition block diagram of the coal moisture content detection and control system on the mine conveyor based on the microwave method in the present application.

[0034] Figure 2 It is an installation schematic diagram of the coal moisture content detection and control system on the mine conveyor based on the microwave method in the present application.

[0035] Figure 3 It is a flow chart of the coal moisture content detection and control method based on the microwave method in the present application.

[0036] Among them, 1-detection mechanism, 2-signal collector, 3-controller, 4-weighing mechanism, 5-spraying mechanism, 6-detection unit, 7-microwave emission module, 8-isolator, 9-emission antenna, 10-receiving antenna;

[0037] 11-detector, 12-stabilized amplifier, 13-ultrasonic level sensor, 14-conveyor, 15-belt conveyor, 16-weighing instrument, 17-water pump, 18-spraying pipeline, 19-spraying head, 20-stabilized power supply. DETAILED DESCRIPTION

[0038] The present application will be further described in detail below in combination with the drawings and specific embodiments:

[0039] Example 1

[0040] As Figure 1 and Figure 2As shown, the embodiment describes a coal moisture content detection and control system based on microwave method, which comprises a detection mechanism 1, a signal collector 2, a controller 3, a weighing mechanism 4 and a spraying mechanism 5.

[0041] The detection mechanism 1 comprises a plurality of groups of the same detection unit 6.

[0042] Taking one group of the detection unit 6 as an example, the detection unit 6 comprises a microwave transmitting module 7, an isolator 8, a transmitting antenna 9, a receiving antenna 10, a detector 11, a voltage stabilizing amplifier 12 and an ultrasonic level sensor 13.

[0043] The microwave transmitting module 7 is used for transmitting microwave signals. The microwave transmitting module 7 specifically adopts a microwave semiconductor device, which generates and transmits microwave resonance signals by exciting a resonance circuit.

[0044] The core of the microwave transmitting module 7 is an HMC530Lp5 chip, and the generated microwave resonance signal frequency range is 9.5-10.8GHz, the output power is 8-14dBm, and the phase noise is-110dBc / 100kHz.

[0045] The present application adopts a tuning voltage of 5V, and the output power is near 10dB, which ensures that the microwave signal frequency is near 9.8GHz.

[0046] The isolator 8 is connected with the microwave transmitting module 7, which is used for isolating other interference signals and ensuring that only microwave signals pass through. The isolator 8 preferably adopts an isolator with a model of GL-T-80120-20-20, and its characteristics are as follows:

[0047] Full bandwidth, insertion loss is 0.5dB, isolation is 20dB, standing wave is 1.25, forward power is 20W, and reverse power is 5W.

[0048] The transmitting antenna 9 is connected with the isolator 8. The microwave signal transmitted by the microwave transmitting module 7 is first filtered by the isolator 8, and the transmitting antenna 9 receives the microwave signal transmitted by the isolator 8 and transmits the signal outward.

[0049] As shown in the figure, Figure 2 The specific arrangement of the transmitting antenna in each group of the detection unit 6 is as follows:

[0050] The transmitting antenna 9 in each group of the detection unit is arranged above the conveyor 14, and the antenna port of each transmitting antenna 9 faces downward and is vertically aligned with the upper surface of the conveyor 14, so as to transmit signals to the conveyor 14.

[0051] All the transmitting antennas 9 in the detection unit are uniformly arranged in the "one" shape along the direction perpendicular to the transmission direction of the conveyor.

[0052] The transmitting antenna 9 is a horn antenna, which converts the coaxial transmission microwave into microwave in a specific space and dielectric material. The horn opening can improve the matching of the microwave in the waveguide and the free space, and radiate most of the energy in the waveguide into the space.

[0053] The antenna model used by the transmitting antenna 9 in the embodiment is, for example, LB-90-20-C-SF, which has a working frequency of 8.2-12.4 GHz, an antenna opening of 138*107 mm, and a waveguide opening inlaid with polytetrafluoroethylene material.

[0054] In addition, in order to ensure that the microwave signals emitted by any two adjacent transmitting antennas 9 do not interfere with each other, the embodiment also designs the minimum distance that needs to be maintained between adjacent transmitting antennas 9, and the calculation formula is as follows:

[0055]

[0056] In the formula, L0 is the minimum distance between adjacent transmitting antennas, S is the speed of light (S = 3*10 8 m / s), and f is the designed microwave frequency, which is f = 9.8 GHz here.

[0057] Through the above formula, it can be effectively ensured that the microwave signals emitted by any two adjacent transmitting antennas 9 do not interfere with each other.

[0058] As shown in FIG. 6, the specific arrangement of the receiving antennas 10 in each group of detection units 6 is as follows: Figure 2

[0059] The receiving antennas 10 in each group of detection units are arranged below the conveyor 14, and the antenna openings of each receiving antenna 10 are upward and vertically aligned with the lower surface of the conveyor 14, for receiving the transmitted microwave signals.

[0060] All the receiving antennas 10 are uniformly arranged in a "one" shape along the direction perpendicular to the transmission direction of the conveyor 14. Moreover, the antenna openings of the transmitting antennas 9 and the antenna openings of the receiving antennas 10 in the same group of detection units are vertically aligned.

[0061] The receiving antennas 10 are of the same type and material as the transmitting antennas 9, and details are described above, which will not be repeated here.

[0062] The detector 11 is connected with the receiving antenna 10, for converting the microwave signal into a direct current voltage signal. The detector 11 is a zero-bias Schottky detector, which is of the model JBQ-20180-NZ, has a frequency range of 2-18 GHz, and has a voltage sensitivity of 500 Nv / mW.

[0063] ​The voltage stabilizing amplifier 12 is connected with the detector 11, and the detector 11 converts the microwave signal into a direct current voltage, but the voltage value is small, measured in mV, and the weak direct current voltage signal is amplified to 0-10V by the voltage stabilizing amplifier 12.

[0064] The voltage stabilizing amplifier 12 is connected with the signal collector 2, for example, by a wired connection, and the voltage stabilizing amplifier 12 sends the amplified microwave voltage signal to the signal collector 2 through the wired connection.

[0065] As shown in Figure 2 , the specific arrangement of the ultrasonic level sensor 13 in each group of detection units 6 is as follows:

[0066] The ultrasonic level sensor 13 in the same group of detection units is installed at a position parallel to the vertical center line of the transmitting antenna 9 of the group of detection units and at a preset distance, and the transmitting head of the ultrasonic level sensor is perpendicular to the upper surface of the conveyor.

[0067] The transmitting head of the ultrasonic level sensor is not blocked by the transmitting antenna, and the model used is UB1000-18GM75-I-V1, the detection range is 50-1000mm, the blind area is 0-50mm, and the resolution is 0.35mm.

[0068] The ultrasonic level sensor 13 detects the height of the coal at the corresponding position on the conveyor 14.

[0069] The ultrasonic level sensor 13 is connected with the signal collector 2, for example, by a wired connection, and the ultrasonic level sensor 13 is used to send the detected level voltage signal to the signal collector 2 through the wired connection.

[0070] The signal collector 2 is connected with the controller 3, for example, by 485 communication connection, and the signal collector 2 receives multiple voltage signals through wired connection and then sends data to the controller 3 through 485 communication.

[0071] In this embodiment, the signal collector 2 preferably uses a DAQM-4200 type signal collector, which has 8 channels of analog input, a resolution of 16 bits, and a precision level of 0.05%.

[0072] As shown in Figure 1 and Figure 2 , the weighing mechanism 4 includes a belt conveyor 15 and a weighing instrument 16. The belt conveyor 15 is the same width as the conveyor and is located downstream of the conveyor 14 and is used to receive the coal blocks transmitted by the conveyor 14.

[0073] The belt conveyor 15 is closely connected with the conveyor 14, and both have the same running speed and running direction. The weighing instrument 16 is installed at the bottom of the supporting leg of the belt conveyor 15, and is used to weigh the weight of the coal blocks on the belt conveyor.

[0074] The supporting legs of the belt conveyor in the embodiment have multiple (for example, four as shown in the figure) and one weighing instrument 16 is arranged at the bottom of each supporting leg. Each weighing instrument 16 is connected with the controller 3. Figure 2

[0075] Since the weighing instruments 16 are multiple, the data of the multiple weighing instruments 16 are added to obtain the total weight of the belt conveyor and the coal.

[0076] The spraying mechanism 5 includes a water supply pipeline, a water pump 17, a spraying pipeline 18 and a spray head 19.

[0077] One end of the water supply pipeline (not shown) is a water source connection end for connecting with a water source, and the other end is connected with the spraying pipeline 18. The water pump 17 is arranged on the water supply pipeline and is connected with the controller 3.

[0078] The spraying pipeline 18 extends to the upper side of the belt conveyor 15, and the extending direction is perpendicular to the conveying direction of the belt conveyor 15.

[0079] The power of the water pump 17 is 100 W, the spraying speed reaches 8 L / min, and the number of the spray heads 19 is designed according to the width of the belt conveyor. The purpose is to ensure that the spraying surface covers the entire belt conveyor and to minimize the overlapping part of the spraying bouquet.

[0080] Each spray head 19 is arranged on the spraying pipeline 18, and the spray head 19 is vertically directed to the upper surface of the belt conveyor 15. All the spray heads 19 are uniformly arranged in a "one" shape along the direction perpendicular to the conveying direction of the belt conveyor.

[0081] When the controller 3 detects that the coal moisture content result is normal, the output is a "0" signal, and the water pump 17 does not work. If the moisture content result is lower than the lower limit requirement of the coal moisture content, the output is a "1" signal, and the water pump works. The spray head 19 sprays water at a fixed rate. When the duration reaches the spraying time, the controller outputs a "0" signal, and the water pump 17 stops working.

[0082] The controller 3 periodically reads the data of the signal collector 2, including all the microwave voltage data and ultrasonic level voltage data. The coal moisture content at multiple positions is estimated through the moisture content model stored in the controller 3, and the multiple coal moisture content data are fused to obtain the average moisture content result in the detection interval. At the same time, it is determined whether the average moisture content is lower than the lower limit requirement.

[0083] ​If the average moisture content is lower than the preset lower limit of coal moisture content, the controller 3 calculates the spraying time length through the internally stored spraying time model and controls the opening and closing of the spraying mechanism 5 in a wired manner.

[0084] In addition, the coal moisture content detection and control system on the mine conveyor further comprises a stabilized power supply 20.

[0085] The stabilized power supply 20 is connected to the microwave emission module 7 and the ultrasonic level sensor 13 respectively, and is used to provide the required stable voltage, such as 5V and 12V, for the microwave emission module 7 and the ultrasonic level sensor 13.

[0086] Embodiment 2

[0087] This embodiment 2 describes a coal moisture content detection and control method based on the microwave method on the mine conveyor, which is implemented based on the coal moisture content detection and control system based on the microwave method on the mine conveyor in the above embodiment 1.

[0088] The idea of the coal moisture content detection and control method based on the microwave method on the mine conveyor is as follows:

[0089] The controller 3 reads the data of the signal collector 2 at a fixed period, including all the microwave voltage data and the level voltage data, and imports the data into the moisture content model to calculate the moisture content data of each detection position at several sampling times, and fuse these moisture content data to obtain the average moisture content result in the detection interval; the controller determines whether the average moisture content result is lower than the lower limit requirement, if it is within the normal range, the output is "0" signal, i.e. low voltage signal, then the water pump 17 does not work, if it is lower than the lower limit, the difference between the current moisture content result and the lower limit is calculated, and the coal weight data sent by the weighing mechanism 4 is imported into the spraying time model together to obtain the spraying time length, and the controller outputs "1" signal, i.e. high voltage, then the water pump works, the spray head sprays continuously at the fixed position above the conveyor until the spraying time length is reached, then the controller outputs "0" signal, and the water pump stops working.

[0090] As shown in Figure 3 The coal moisture content detection and control method based on the microwave method on the mine conveyor comprises the following steps:

[0091] Step 1. The controller reads the data of the signal collector, including all the microwave voltage data and the ultrasonic level voltage data, and estimates the coal moisture content of multiple positions through the moisture content model.

[0092] The expression of the moisture content model is as follows:

[0093]

[0094] In the formula, X is the moisture content of coal, U is the microwave voltage, H is the ultrasonic level voltage, and {a1, a2, …, a6} is the model coefficient.

[0095] On the one hand, the attenuation of microwave transmission has a nonlinear relationship with the moisture content, and the higher the moisture content, the greater the attenuation, and the overall trend is monotonous. Since the attenuation is inversely related to the detected microwave voltage, it is reasonable for the present application to use the polynomial function as shown above to describe the relationship between the moisture content and the microwave voltage.

[0096] On the other hand, the attenuation of microwave transmission is inversely proportional to the measured thickness, and the thicker the measured thickness, the greater the attenuation. At the same time, the coal thickness is proportional to the level voltage, so the attenuation of microwave transmission is inversely proportional to the level voltage. Therefore, it is reasonable for the present application to use the polynomial function as shown above to describe the relationship between the moisture content and the level voltage.

[0097] Step 2. The controller reads the data of the signal collector according to a fixed sampling period; the sampling period is designed according to the following formula:

[0098]

[0099] In the formula, T is the sampling period, L is the length of the belt conveyor, V is the transport rate of the conveyor, and N represents the number of samples in the detection interval.

[0100] The design of the sampling period can meet the requirement that when the controller collects N samples, the moisture content detection of the detection interval part with a transport length of L on the conveyor has been completed, and the coal in the detected detection interval part is removed to the belt conveyor for weighing.

[0101] Step 3. The controller calculates the moisture content of all microwave voltages and level voltages at N sampling times, and fuses the calculated moisture content to obtain the average moisture content of coal in the detection interval.

[0102] The average moisture content of coal in the detection interval is calculated according to the following formula:

[0103]

[0104] In the formula, is the average moisture content of coal in the detection interval, X i is the moisture content estimation data corresponding to the i-th group of detection units, and n is the number of groups of detection units.

[0105] Step 4. When the average moisture content of coal in the detection interval is normal, i.e. higher than the lower limit requirement of coal moisture content, the controller outputs a low voltage signal, and sends the low voltage signal to the water pump, and the water pump remains in a stopped state.

[0106] When the average moisture content of the coal in the detection interval is lower than the lower limit of the coal moisture content, the controller outputs a high voltage signal and sends the high voltage signal to the water pump 17, and the water pump is started.

[0107] Meanwhile, the controller calculates the spraying duration of the spraying mechanism according to the spraying time model. The spraying time model is as follows:

[0108]

[0109] In the formula, t is the spraying duration, is the difference between the current moisture content and the lower limit requirement, W i is the data from the i-th weighing instrument, and m is the number of the weighing instruments.

[0110] W0 is the weight of the belt conveyor, is the weight of the coal; and V0 is the fixed volume flow rate of the spraying.

[0111] The controller counts the time according to the spraying duration calculated by the spraying time model. Once the time reaches the counted time, the controller outputs a low voltage signal and sends the low voltage signal to the water pump, and the water pump stops working, thereby completing the control of the coal moisture content.

[0112] Of course, the above description is only for the preferred embodiments of the present application, and the present application is not limited to the above-described embodiments. It should be noted that any person skilled in the art, under the teaching of the present application, can make all equivalent substitutions and obvious modifications, which fall within the scope of the present application, and should be protected by the present application.

Claims

1. A coal moisture content detection and control system on a mine conveyor based on a microwave method, characterized in that, The detection mechanism, the signal collector, the controller, the weighing mechanism and the spraying mechanism are included. The detection mechanism includes multiple groups of identical detection units, and each group of the detection units includes a microwave transmitting module, an isolator, a transmitting antenna, a receiving antenna, a detector, a voltage stabilizing amplifier and an ultrasonic level sensor. The microwave transmitting module, the isolator and the transmitting antenna are sequentially connected; the receiving antenna, the detector and the voltage stabilizing amplifier are sequentially connected, and the voltage stabilizing amplifier and the ultrasonic level sensor are respectively connected with the signal collector. The transmitting antenna in each group of the detection units is arranged above the conveyor, and the antenna port of the transmitting antenna faces downward and is vertically aligned with the upper surface of the conveyor; all the transmitting antennas are uniformly arranged in a "I" shape along a direction perpendicular to the transmission direction of the conveyor. The receiving antenna in each group of the detection units is arranged below the conveyor, and the antenna port of the receiving antenna faces upward and is vertically aligned with the lower surface of the conveyor; all the receiving antennas are uniformly arranged in a "I" shape along a direction perpendicular to the transmission direction of the conveyor. The antenna port of the transmitting antenna and the antenna port of the receiving antenna in the same group of the detection units are vertically aligned. The ultrasonic level sensor in each group of the detection units is installed at a position parallel to the vertical center line of the transmitting antenna in the same group of the detection units and at a preset distance from the vertical center line, wherein the transmitting head of the ultrasonic level sensor is perpendicular to the upper surface of the conveyor. The weighing mechanism includes a belt conveyor and a weighing instrument; the belt conveyor is located downstream of the conveyor and is used to receive the coal blocks transmitted by the conveyor, and the weighing instrument is installed at the bottom of the supporting leg of the belt conveyor and is used to weigh the weight of the coal blocks on the belt conveyor. The spraying mechanism includes a water supply pipeline, a water pump, a spraying pipeline and a spray head. One end of the water supply pipeline is a water source connection end, the other end is connected with the spraying pipeline, and the water pump is arranged on the water supply pipeline; the spraying pipeline extends above the belt conveyor, and the arrangement direction thereof is perpendicular to the conveying direction of the belt conveyor. A plurality of spray heads are arranged on the spraying pipeline, and each spray head faces vertically toward the upper surface of the belt conveyor; all the spray heads are uniformly arranged in a "I" shape along a direction perpendicular to the transmission direction of the conveyor. The signal collector, the weighing instrument in the weighing mechanism and the water pump in the spraying mechanism are respectively connected with the controller.

2. The coal moisture content detection and control system on the mine conveyor based on the microwave method according to claim 1, characterized in that the coal moisture content detection and control system on the mine conveyor further comprises a voltage stabilizing power supply. The voltage stabilizing power supply is connected with the microwave transmitting module and the ultrasonic level sensor respectively, and is used to provide the required stable voltage for the microwave transmitting module and the ultrasonic level sensor.

3. The coal moisture content detection and control system on the mine conveyor based on the microwave method according to claim 1, characterized in that the transmitting antenna and the receiving antenna are both horn antennas.

4. The coal moisture content detection and control system on the mine conveyor based on the microwave method according to claim 1, characterized in that a minimum distance is maintained between adjacent transmitting antennas to ensure that the microwave signals do not interfere with each other, and the minimum distance is calculated by the following formula: In the formula, L0 is the minimum distance between adjacent transmitting antennas, S is the speed of light, and f is the designed microwave frequency. ​ ​ ​ 5.The coal moisture content detection and control system based on microwave method on mine conveyor according to claim 1, characterized in that, the support legs of the belt conveyor are multiple, and a load cell is arranged at the bottom of each support leg. 6.A coal moisture content detection and control method based on microwave method on mine conveyor, using the coal moisture content detection and control system based on microwave method on mine conveyor according to any one of claims 1 to 5, characterized in that, the coal moisture content detection and control method based on microwave method on mine conveyor comprises the following steps: Step 1. The controller reads the data of the signal collector, including all microwave voltage data and ultrasonic level voltage data, estimates the coal moisture content at multiple positions through the moisture content model; Step 2. The controller reads the data of the signal collector according to a fixed sampling period; Step 3. The controller calculates the moisture content of all microwave voltages and level voltages at N sampling times, fuses the calculated moisture content, and obtains the average coal moisture content result in the detection interval; wherein N represents the number of samples in the detection interval controlled by the controller; Step 4. When the average coal moisture content result in the detection interval is normal, i.e. higher than the lower limit requirement of coal moisture content, the controller outputs a low voltage signal, and sends the low voltage signal to the water pump, and the water pump remains in a stopped state; When the average coal moisture content result in the detection interval is lower than the lower limit requirement of coal moisture content, the controller outputs a high voltage signal, and sends the high voltage signal to the water pump, and the water pump starts to operate; At the same time, the controller calculates the spraying time of the spraying mechanism according to the spraying time model; The controller counts the spraying time calculated by the spraying time model, and once the counting time is reached, the controller outputs a low voltage signal, and sends the low voltage signal to the water pump, and the water pump stops working, completing the control of the coal moisture content. 7.The coal moisture content detection and control method on mine conveyor according to claim 6, characterized in that, in the step 1, the expression of the moisture content model is as follows: wherein X is the coal moisture content, U is the microwave voltage, H is the ultrasonic level voltage, and {a1, a2, …, a6} are model coefficients. 8.The coal moisture content detection and control method on mine conveyor according to claim 6, characterized in that, in the step 2, the sampling period is designed according to the following formula: wherein T is the sampling period, L is the length of the belt conveyor, and V is the transportation rate of the conveyor. 9.The coal moisture content detection and control method on mine conveyor according to claim 6, characterized in that, in the step 3, the average coal moisture content result in the detection interval is calculated according to the following formula: In the formula, is the average moisture content of the coal in the detection interval; X i is the moisture content estimation data corresponding to the i-th group of detection units, and n is the number of groups of detection units. 10.The coal moisture content detection and control method on mine conveyor according to claim 6, characterized in that, in the step 4, the spraying time model formula is as follows: In the formula, t is the spraying time length, W is the difference between the water content in the current detection interval and the lower limit requirement i m is the number of the weighing instruments; W0 is the weight of the belt conveyor, is the weight of the coal; V0 is the fixed volume flow of the spray.

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