A method and device for detecting the moisture content of briquettes
By establishing a mapping model between the humidity gradient of coal blocks and the venting time underground, and using infrared sensing technology to measure the venting time, the problems of detection result deviation and insufficient real-time performance in existing technologies are solved, and high-precision, real-time detection of coal block humidity underground is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA UNIV OF MINING & TECH (BEIJING)
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-29
Smart Images
Figure CN122108935A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal lump humidity detection technology, and in particular to a method and apparatus for detecting coal lump humidity. Background Technology
[0002] Top coal caving is a core technology for efficient mining of thick coal seams, and the moisture content of the coal lumps is a key parameter determining the efficiency of top coal release and the safety of mining. Excessive moisture content leads to a significant increase in coal lumps' stickiness, causing blockages at the coal release port and scraper conveyors, severely impacting mining continuity. Conversely, excessively low moisture content exacerbates coal dust emissions, threatening the health of underground workers. Therefore, real-time and accurate acquisition of the actual moisture content of underground coal lumps is of irreplaceable significance for optimizing coal release parameters and mitigating production risks.
[0003] In current coal lump moisture detection technology, most detection methods rely on bringing the sample back to the laboratory to complete the final measurement. During the transportation and waiting for testing, the sample will still experience moisture loss or abnormal changes, resulting in a significant deviation between the measurement results and the actual moisture content underground. At the same time, the detection cycle is too long and the data lacks real-time timeliness, which cannot effectively guide the technical problems of top coal caving mining operations.
[0004] In view of the problems of the prior art, those skilled in the art urgently need a method and device for detecting the moisture content of coal blocks. Summary of the Invention
[0005] The purpose of this invention is to provide a method and apparatus for detecting the humidity of coal blocks, so as to solve the problems existing in the prior art. It can be used to detect coal block humidity in the underground working environment, and the humidity of coal blocks can be determined by detecting the venting time, thereby shortening the detection cycle and ensuring the authenticity and real-time nature of the data.
[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for detecting the humidity of coal blocks, comprising the following steps: pre-establishing a mapping model between the humidity gradient of standard coal blocks and the venting time; collecting coal samples on-site in real time, and sieving the coal samples to obtain sieved coal samples with particle sizes below the standard particle size; weighing the sieved coal samples to obtain a standard mass of the sieved coal samples; venting the standard mass of the sieved coal samples through a measuring port in a measuring chamber, and measuring the actual venting time; obtaining the corresponding actual coal block humidity based on the actual venting time and the mapping model; wherein, the mass of the standard coal block is the standard mass and the particle size of the standard coal block is below the standard particle size.
[0007] In some implementations, the step of "pre-establishing a mapping model between the humidity gradient of standard coal blocks and the venting time" includes: selecting multiple mines to collect coal samples and recording environmental data at the sampling points; transferring the collected coal samples to a laboratory environmental simulation chamber and adjusting the parameters within the laboratory environmental simulation chamber to match the environmental data at the sampling points; sieving the collected coal samples to obtain coal samples with particle sizes below the standard particle size, and preparing multiple sets of known humidity standard samples with fixed humidity gradient differences from the sieved coal samples; venting each set of known humidity standard samples of standard mass through the measuring port in the measuring chamber and recording the venting time of each set of known humidity standard samples; and establishing the mapping model between the humidity gradient of the standard coal blocks and the venting time based on the venting times of the multiple sets of known humidity standard samples.
[0008] In some embodiments, in the step of "weighing the screened coal sample to obtain a standard mass of the screened coal sample": the feed gate is opened to control the screened coal sample to enter the weighing bin; the mass of the screened coal sample entering the weighing bin is detected by a dynamic weighing sensor; when the detection result reaches the standard mass, the feed gate is closed; after confirming that the detection result is the standard mass in a static state, the discharge gate is opened to allow the standard mass of the screened coal sample to enter the measuring chamber.
[0009] In some embodiments, the step of "measuring the actual emptying time of the falling coal sample" includes: starting a timer when the screened coal sample begins to fall through the measuring port and the infrared beam emitted by the infrared transmitter to the infrared receiver changes from a through state to a blocked state; when a standard mass of the screened coal sample falls through the measuring port and the infrared beam emitted by the infrared transmitter to the infrared receiver returns from a blocked state to a through state, controlling the timer to stop timing, thereby obtaining the actual emptying time; wherein the infrared transmitter and the infrared receiver are located at the measuring port.
[0010] In some embodiments, the measuring cavity includes a flow-limiting channel that narrows from bottom to top. The flow-limiting channel includes two opposing sidewalls with different angles to the horizontal plane. In the step of "the standard mass of the screened coal sample falling and emptying through the measuring port in the measuring cavity": when the screened coal sample passes through the flow-limiting channel, the two sidewalls of the flow-limiting channel exert unbalanced pressure on the screened coal sample, causing the screened coal sample to pass through the measuring port continuously and without arching.
[0011] In some implementations, the step of “establishing the mapping model of humidity gradient and venting time of the standard coal block based on the venting time of multiple sets of known humidity standard samples” includes: drawing multiple mapping curves of humidity gradient and venting time of the standard coal block based on test data from multiple mines, and performing weighted average calibration on the multiple mapping curves to obtain a standard card comparison table of humidity gradient and venting time of the standard coal block.
[0012] In some embodiments, the method further includes: performing repeated experiments on each group of known humidity standard samples multiple times to remove abnormal time data.
[0013] In some embodiments, the measuring cavity is located below the weighing chamber, and the measuring port is offset from the vertical axis of the weighing chamber.
[0014] The present invention also provides a coal lump humidity detection device for implementing the above-mentioned coal lump humidity detection method, comprising a screen, a weighing chamber, a measuring cavity, and a sensing timing module; the screen is used to screen the coal sample to obtain a screened coal sample with a particle size below the standard particle size, the weighing chamber is used to weigh the screened coal sample to obtain a standard mass of the screened coal sample, and the sensing timing module is used to measure the actual emptying time of the falling coal sample.
[0015] In some embodiments, the measuring cavity includes a flow-limiting channel and a bottom wall. The flow-limiting channel is narrowed from bottom to top, and the bottom end of the flow-limiting channel is connected to the bottom wall. The bottom wall has a measuring port. The flow-limiting channel includes two opposing side walls, and the two side walls have different angles with the horizontal plane. The measuring port is offset relative to the vertical axis of the fixed weight chamber.
[0016] The present invention achieves the following technical effects compared to the prior art: The coal lump humidity detection method and apparatus of the present invention transforms the difficult-to-perceive humidity variable into a highly quantifiable venting time characteristic. By pre-establishing a mapping model between humidity gradient and venting time, the actual venting time of a standard-quality screened coal sample is obtained at the underground operation site. By comparing the actual venting time with the mapping model, the actual coal lump humidity can be obtained. The present invention completes the sampling, quantification, detection, and result output at the underground operation site, enabling the coal sample to complete the detection process without leaving the underground environment. This avoids moisture changes caused by coal sample transportation and eliminates the main source of error in existing technologies. Therefore, the present invention can obtain humidity data that is closer to the actual state of underground coal lumps and achieve real-time output of detection results, significantly improving the accuracy and real-time performance of humidity detection and shortening the detection cycle. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a flowchart of the main steps of the coal lump moisture detection method in some embodiments of the present invention; Figure 2 This is a schematic diagram of the structure of the coal lump moisture detection device in some embodiments of the present invention; Figure 3 This is a schematic diagram of the detection process of the coal lump moisture detection device in some embodiments of the present invention; Figure 4 This is a flowchart of a method for detecting the humidity of coal blocks in some embodiments of the present invention; In the diagram: 1-Feeding hopper; 2-Screen; 3-Infeed gate; 4-Fixing bin; 5-Discharge gate; 6-Inclined sidewall; 7-Vertical sidewall; 8-Measuring port; 9-Collection box; 10-Screened coal sample. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] The purpose of this invention is to provide a method and apparatus for detecting the humidity of coal blocks, so as to solve the problems existing in the prior art. It can be used to detect coal block humidity in the underground working environment, and the humidity of coal blocks can be determined by detecting the venting time, thereby shortening the detection cycle and ensuring the authenticity and real-time nature of the data.
[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0022] Example 1 This embodiment provides a method for detecting the moisture content of coal blocks, such as... Figure 1 As shown, the main steps include the following: Step S1: Establish a mapping model between the humidity gradient of standard coal blocks and the venting time in advance; Step S2: Collect coal samples on-site immediately and screen the coal samples to obtain 10 screened coal samples with a particle size below the standard particle size; Step S3: Weigh the screened coal sample 10 to obtain a standard mass of screened coal sample 10; Step S4: The standard mass of the screened coal sample 10 falls into the measuring chamber through the measuring port 8 and is emptied, and the actual emptying time is measured. Step S5: Obtain the corresponding actual coal lump moisture content based on the actual venting time and mapping model.
[0023] It should be noted that the standard coal block of this invention has a standard mass and a particle size below the standard particle size, thus ensuring that the pre-tested standard coal block is consistent with the coal sample tested at the operation site in terms of mass and particle size. Consequently, the actual venting time is consistent with the venting time on the mapping model. This invention transforms the difficult-to-perceive humidity variable into a venting time feature that can be measured with high precision, and enables the coal sample to complete the testing process without leaving the underground environment, significantly improving the authenticity and real-time performance of humidity detection, and shortening the testing cycle.
[0024] In some embodiments, step S1 includes: Step S11: Select multiple mines to collect coal samples and record the environmental data of the sampling points; Step S12: Transfer the collected coal sample to the laboratory environment simulation chamber and adjust the parameters in the laboratory environment simulation chamber to be consistent with the environmental data of the sampling point; Step S13: The collected coal samples are sieved to obtain coal samples with a particle size below the standard particle size, and the sieved coal samples are made into multiple sets of known humidity standard samples with fixed humidity gradient differences. Step S14: Empty each set of known humidity standard samples of standard mass through the measuring port in the measuring chamber, and record the emptying time of each set of known humidity standard samples. Step S15: Based on the evacuation time of multiple sets of known humidity standard samples, establish a mapping model between the humidity gradient and evacuation time of standard coal blocks.
[0025] In some implementations, such as Figure 2 and Figure 3 As shown, the screened coal sample 10 is dynamically weighed using a fixed-weighing bin 4, and the fixed-weighing bin 4 includes a feed gate 3, a discharge gate 5, and a dynamic weighing sensing element; in the above step S3: Coal sample 10 is screened and enters the weighing bin 4 through the feed gate 3; The mass of the screened coal sample 10 entering the fixed weight bin 4 is detected by a dynamic weighing sensor. When the detection result reaches the standard mass, the feed gate 3 is closed. After confirming that the test result is of standard quality in a static state, open the discharge gate 5 to allow the standard quality screened coal sample 10 to enter the measuring chamber.
[0026] In some embodiments, an inductive timing module is used to measure the actual emptying time of the fall. The inductive timing module includes an infrared transmitter and an infrared receiver disposed at the measuring port 8. The step of "measuring the actual emptying time of the fall" in step S4 above includes: When the screened coal sample 10 begins to fall through the measuring port 8, and the infrared beam emitted by the infrared transmitter to the infrared receiver changes from a through state to a blocked state, the timer is started. When the standard quality screened coal sample 10 falls from the measuring port 8 and is discharged, the infrared beam emitted by the infrared transmitter to the infrared receiver returns from the blocked state to the open state, and the control timer stops timing to obtain the actual discharge time.
[0027] In some implementations, such as Figure 2 As shown, the measuring chamber includes a flow-limiting channel that narrows from bottom to top. The flow-limiting channel includes two opposing sidewalls with different angles to the horizontal plane. In the step of "the standard mass of the screened coal sample 10 falling and being discharged through the measuring port 8 within the measuring chamber": When the screened coal sample 10 passes through the flow-limiting channel, the two side walls of the flow-limiting channel exert unbalanced pressure on the screened coal sample 10, so that the screened coal sample 10 passes through the measuring port 8 continuously and without arching.
[0028] In some embodiments, step S15 includes: Based on test data from multiple mines, several mapping curves between the humidity gradient of standard coal blocks and the venting time were plotted. These curves were then calibrated by weighted averaging to obtain a standard card comparison table of the humidity gradient and venting time of standard coal blocks. This invention can utilize the least squares method for regression analysis to plot the "venting time - coal block humidity" mapping curve.
[0029] In some embodiments, the method further includes: For each group of known humidity standard samples, the experiment was repeated multiple times to remove abnormal time data. This invention can use residual analysis to eliminate abnormal time data caused by accidental caking.
[0030] In some embodiments, the measuring cavity is located below the weighing chamber 4, and the measuring port 8 is offset from the vertical axis of the weighing chamber 4.
[0031] The specific steps for establishing the mapping model in step S1 of the present invention are as follows: In-situ environmental background data collection in multiple mines: Select multiple mines with representative geological conditions and ventilation environments, collect coal samples underground, and use instruments to monitor and record real-time environmental data such as air humidity, wind speed and temperature at the sampling points to provide accurate working condition background files for subsequent experiments.
[0032] Simulation and Replication of Equivalent Environment System in the Laboratory: Coal samples collected underground are quickly transferred to the laboratory using sealed containers. Based on the recorded data, the parameters of the laboratory environment simulation chamber are adjusted to strictly restore the environmental conditions consistent with the corresponding mine, eliminating data distortion caused by changes in the liquid bridging force on the surface of the coal sample due to sudden environmental changes.
[0033] Preparation of standard samples with known humidity gradients: Under simulated equivalent environment, coal samples with a particle size of 5 mm or less were artificially prepared into multiple standard samples with known humidity gradients. The humidity of the multiple standard samples ranged from 2% to 20%, with each 1% representing a gradient. The samples were then left to stand under constant temperature and humidity conditions to ensure that the moisture penetrated evenly and remained stable on the surface of the coal particles.
[0034] Standardized hourglass drop physical experiment test: 2kg standard samples under various humidity gradients were sequentially placed into the coal lump humidity detection device of this invention for drop experiments. Under equivalent environmental interference, the emptying time of each group of samples completely passing through the measuring port 8 was recorded, and the experiment was repeated multiple times for each group of humidity samples. Abnormal time data caused by accidental arching was eliminated by residual analysis.
[0035] Data fitting and generation of a general standard card comparison table: Test data from multiple representative mine backgrounds are summarized, regression analysis is performed using the least squares method, a mapping curve of venting time and coal moisture is plotted, and multiple curves are calibrated by weighted average. Finally, a standard card comparison table with wide applicability is generated, which can be used as a machine nameplate for on-site inspection and reference.
[0036] like Figure 4 As shown, the coal lump moisture detection method of the present invention is implemented through the following specific steps: On-site sampling and screening pretreatment: Fresh coal samples are collected immediately at the underground work site and fed into the feed hopper 1 at the top of the device for screening. Large pieces of coal and stone are filtered out using a standard screen, such as a 5mm aperture screen, and only the fine coal fragments that pass through the screen are collected. This process aims to eliminate the physical obstruction of the flow path by large pieces of material and ensure the standardization of particle size in subsequent experimental samples.
[0037] Precise Quantification and Sequential Cut-off: The screened coal sample enters the weighing bin 4 for dynamic weighing. When the material mass in the bin reaches a set threshold, such as 2 kg, the control system first drives the upper feed gate 3 to close rapidly. The action logic of the feed gate 3 takes precedence over the discharge gate 5, its purpose being to cut off the remaining material falling through the air at this time, strictly locking the mass of the coal sample participating in the test at the set threshold, such as 2 kg. After confirming that the feed gate 3 is completely closed and the material in the bin is static, the quantification process is completed.
[0038] Automatic timing and release mechanism: The operator triggers a release command or the system automatically opens the discharge gate 5 at the bottom of the fixed-weight bin 4. A sample of coal of a set mass passes through the asymmetric measuring chamber below under gravity. The moment the first batch of coal samples passes through the constricted throat (measuring port 8), the infrared sensor beam is interrupted. The system detects this signal and immediately starts a millisecond-level timer. During this process, the unbalanced pressure generated by the asymmetric inner wall disrupts the force balance of the wet coal, forcing the coal sample to pass through the throat continuously and without arching.
[0039] Flow monitoring and timing termination: Infrared sensors continuously monitor the material flow at the throat. As the sample coal in the weighing bin 4 is completely emptied, when the last coal particle leaves the throat and the infrared beam returns from blocked to continuous, the controller detects the optical path restoration signal and immediately stops the timing. At this time, the digital display screen will directly lock and display the total emptying time of this experiment.
[0040] Data mapping and humidity acquisition: The operator records the evacuation time displayed on the screen and directly consults the standardized calibration reference table (standard card) affixed to the machine casing. Based on the mapping relationship between evacuation time and humidity, the corresponding percentage value is read to complete the on-site closed-loop detection of downhole humidity.
[0041] The technical principle of this invention is based on the evolution law of internal friction in granular mechanics: the free water on the surface of the coal sample particles will generate liquid bridge force, which will significantly enhance the viscous resistance between particles. During the falling process, the greater the humidity of the coal sample, the greater its internal shear resistance, which is macroscopically manifested as a longer total time for the coal flow to pass through the measuring port.
[0042] This invention proposes a calibration system that transforms in-situ underground operating parameters into laboratory calibration backgrounds to generate a mapping standard card for venting time and humidity. The core of this scheme lies in collecting background data such as air humidity, wind speed, and temperature from different mines and then using a laboratory environmental simulation system to perform a 1:1 reconstruction, thereby calibrating the outflow time of standard quality coal samples under equivalent operating conditions. This method solves the data distortion problem caused by changes in moisture migration characteristics in high-humidity, windy underground environments using traditional calibration curves, ensuring the initial accuracy and authenticity of the standard reference table in field applications, and providing the data foundation for accurate detection.
[0043] This invention transforms the difficult-to-perceive humidity variable into a highly measurable evacuation time characteristic by locking in the physical parameters of the material. The core logic of this method is to standardize the particle size using a sieve and forcibly lock the experimental mass benchmark (e.g., 2 kg) using a sequentially linked double-gate mechanism. Then, infrared sensing technology is used to capture the start and end moments of the coal sample flowing through the throat. This process of first standardizing and quantifying, then automating the timing, eliminates interference from differences in sample coal size, dynamic material overweight, and human reaction delays on the detection results. It does not rely on easily damaged electronic weighing sensors or optical detectors, but instead uses the contribution of the liquid bridge force on the coal surface to the flow resistance to invert humidity, significantly improving the operational stability and measurement repeatability of the device in underground high-dust and high-vibration environments.
[0044] This invention employs a unique asymmetric inner wall design in the constriction section of the measurement chamber to address the problem of arching and clogging that easily occurs during the descent of wet, sticky coal samples. The core function of this structure lies in its unequal inclination angles on both side walls, and the slight offset between the throat's central axis and the feed centerline. This asymmetric geometry is not merely for simple material guidance, but rather utilizes the unbalanced lateral pressure generated during material descent to forcibly disrupt the stable stress arch bridge formed by the wet coal particles at the constriction. This design, without any external dynamic interference, induces shear flow in the coal sample through the structure itself, fundamentally eliminating the risk of throat clogging at a physical level. This is a physical prerequisite for ensuring the continuity of the testing process and obtaining effective experimental parameters.
[0045] This invention designs a mechanical control sequence for precise quantitative analysis. Through the interlocking linkage of the upper feed gate 3 and the lower discharge gate 5, the initial mass of the coal sample is forcibly locked. The core value of this mechanism lies in solving the problem of weight overshoot during dynamic feeding. The feed gate 3 closes instantaneously upon sensing a 2kg load, using physical blocking to intercept the inertial residual material between the feeding channel and the bin opening. This logic of first intercepting the material, then confirming stillness, and finally opening and releasing ensures that the weight of each batch of coal samples tested is strictly controlled within the error range, eliminating the interference of falling material inertia on the experimental benchmark. This is the core mechanical structure that guarantees the stability of testing accuracy.
[0046] This invention integrates an infrared sensing module at the asymmetric throat, utilizing the interruption and recovery signals of the light beam by the material flow to automatically convert physical flow behavior into high-precision digital characteristics. This system is not a simple photoelectric switch, but rather uses an infrared probe to capture the level transition signals at the beginning and end of the material flow, driving a timer to achieve millisecond-level automatic start and stop. This non-contact acquisition method not only completely eliminates the reaction time error when the operator presses the stopwatch, but also, because it only extracts the edge trigger state of the signal, possesses extremely strong resistance to dust interference and light fluctuations, significantly improving the device's environmental adaptability and operational stability in harsh underground environments with high dust and high vibration.
[0047] This invention proposes a vertical, layered, in-situ underground detection process that integrates graded screening, precise quantification, and flow detection. The core significance of this process lies in the real-time and accurate data output. By completing the entire process from coarse screening to result output directly at the coal discharge point, the coal sample does not need to leave the underground working environment, completely eliminating moisture loss and property changes that inevitably occur during sealed transfer, transport to the surface, and waiting in the laboratory. This closed-loop process not only significantly shortens the detection cycle but also ensures that the obtained data accurately reflects the original moisture state of the top coal, providing the most reliable decision-making basis for real-time optimization of coal discharge parameters.
[0048] Example 2 This embodiment provides a coal lump moisture detection device for implementing the coal lump moisture detection method of Embodiment 1 above, such as... Figure 2 and Figure 3 As shown, the detection device includes a screen 2, a weighing chamber 4, a measuring cavity, and a timing module. The weighing chamber 4 is located below the screen 2, and the measuring cavity is located below the weighing chamber 4. The timing module includes a timer, an infrared transmitter, and an infrared receiver, with the infrared transmitter and receiver positioned at the measuring port 8 of the measuring cavity. The weighing chamber 4 includes an inlet gate 3, an outlet gate 5, and a dynamic weighing sensing element. The screen 2 is used to screen the coal sample to obtain a screened coal sample 10 with a particle size below the standard particle size. The weighing chamber 4 is used to weigh the screened coal sample 10 to obtain a standard mass of screened coal sample 10. The timing module is used to measure the actual emptying time of the falling coal sample.
[0049] In some embodiments, the measuring cavity includes a flow-limiting channel and a bottom wall. The flow-limiting channel is narrowed from bottom to top, and the bottom end of the flow-limiting channel is connected to the bottom wall. A measuring port 8 is provided on the bottom wall. The flow-limiting channel includes two opposing side walls, and the two side walls have different angles with the horizontal plane. The measuring port 8 is offset relative to the vertical axis of the fixed weight chamber 4.
[0050] The longitudinal cross-section of the bottom wall of the measuring cavity of the present invention is approximately conical, and a measuring port 8 is provided at the lowest point of the bottom wall; for example Figure 2 As shown, the flow restriction channel includes an inclined sidewall 6 and a vertical sidewall 7 arranged opposite to each other; a feeding funnel 1 is provided above the screen 2, and a collection box 9 is provided below the measuring chamber.
[0051] The detection device of this invention adopts a modular, vertically arranged mechanical structure. Through the combination of physical geometric features and photoelectric sensing technology, it achieves accurate detection of coal sample moisture. Its specific structural composition is as follows: Pre-treatment grading and screening module: The top of the device is equipped with an open-top feeding funnel 1, below which is a reinforced metal screen with a standard aperture of 5mm. The main function of this module is to perform preliminary screening of the raw coal samples collected underground, allowing only coal samples with a particle size smaller than the standard aperture to enter subsequent stages, automatically removing large pieces of coal or debris that may cause mechanical blockage at the throat, and ensuring the uniformity of the coal sample particle size.
[0052] Sequentially Linked Double-Gate Weighing Chamber 4: A weighing chamber 4 is located below the screen 2. This chamber is equipped with a high-precision dynamic weighing sensor and two linked gates. Upper Feed Gate 3: When the weight of the coal sample in the weighing chamber 4 reaches the set mass, such as 2kg, the feed gate 3 will quickly close. Its function is to completely block the falling path of subsequent coal samples, preventing the remaining material falling in the air at the moment of weighing trigger from entering the chamber, thus strictly locking the mass of the coal sample to be tested in the chamber at the set mass. Lower Discharge Gate 5: Located at the bottom of the weighing chamber 4, it is responsible for opening and releasing after the feed gate 3 is completely closed and the weight is confirmed. This module ensures that the mass of the coal sample is completely consistent in each experiment by first cutting off the feed and then opening and releasing, eliminating the interference of mass variables on the test results.
[0053] Asymmetric Anti-clogging Measurement Chamber: Below the fixed-weight chamber 4 lies the core physical chamber of this device, namely the asymmetric measurement chamber. The lower constriction section of this chamber employs a special asymmetric geometry design, with two opposing sidewalls distributed at unequal angles to the horizontal plane. This design aims to break up the stress arch bridge that wet coal particles easily form at the constriction point through unbalanced lateral pressure. When the coal sample passes through the throat, i.e., the measurement port 8, it undergoes unbalanced shear flow induced by the asymmetric sidewalls, thus fundamentally solving the problem of wet coal arching and clogging at a physical level, ensuring the continuity of the coal sample's descent.
[0054] Infrared Automatic Timing Module: A pair of infrared transmitters and receivers are installed at the constriction throat of the asymmetric cavity. Automatic Start Timing: When the discharge gate 5 opens and the first batch of coal sample passes through the throat, it blocks the infrared beam. The controller detects the blocking signal and automatically starts the high-precision timing. Automatic Stop Timing: As the coal sample gradually flows out, when no more coal sample passes through the throat and the infrared beam returns to its continuous state, the timer automatically stops. This module uses infrared photoelectric signals to replace manual start and stop of the stopwatch, eliminating errors caused by human reaction delays and improving the measurement accuracy of the emptying time to the millisecond level.
[0055] Support frame and data display unit: The entire device is supported by a high-strength metal frame to ensure stability in the underground vibration environment. A digital LCD screen is mounted on the side of the device. The screen displays the venting time collected by the infrared module in real time. Operators can quickly determine the corresponding percentage of coal sample moisture at that time by comparing it with a standard card.
[0056] The coal lump moisture detection method and apparatus of the present invention have the following effects: This invention integrates sampling, quantification, detection, and result output all underground, allowing coal samples to complete the testing process without leaving the underground environment. This avoids moisture changes caused by coal sample transportation, eliminating the main source of error in existing technologies. Therefore, this invention can obtain humidity data that more closely reflects the actual state of coal blocks underground and achieves real-time output of test results, significantly improving the accuracy and real-time performance of humidity detection.
[0057] This invention introduces fixed-weight quantitative processing into the testing procedure, ensuring that all coal samples entering the testing stage are under a uniform quality standard. Furthermore, an hourglass-like structure provides consistent mechanical constraints during the coal sample's descent, making sample moisture the primary variable influencing its physical behavior. Through this design, the invention effectively reduces multivariate interference, ensuring that the testing results of coal samples from different batches and locations are within the same comparative standard, significantly improving the stability and repeatability of the test results.
[0058] This invention does not rely directly on electronic sensing of humidity. Instead, it induces the natural fall and confined flow response of coal samples under gravity through an hourglass-shaped confined structure, and indirectly characterizes the humidity state using these physical behavioral characteristics. Since the detection mechanism is mainly determined by the mechanical structure and gravity conditions, it is not sensitive to the complex underground environment, thus significantly improving the reliability and adaptability of the device during long-term underground operation, and reducing maintenance difficulty and operating costs.
[0059] In some alternative embodiments, the hourglass-shaped detection body of the present invention guides the coal sample to complete a restricted descent under gravity through a narrowing flow-limiting channel, inducing a humidity-based flow resistance response in the coal sample. While maintaining the technical objective of achieving a unified descent path and mechanical constraints, the flow-limiting channel structure of the present invention can be replaced by other equivalent flow-limiting channel structures, such as a tapered channel, a stepped-diameter narrowing channel, or a descent channel structure with a turbulent inner wall. Although these alternative structures differ in appearance from the hourglass structure, they all create a stable and repeatable physical environment during the coal sample's descent, causing the coal sample to produce a humidity-related physical response, thereby achieving the same detection objective as the present invention.
[0060] In some alternative implementations, the present invention uses a fixed-weight quantification module to ensure consistent coal sample quality upon entering the testing stage, thereby eliminating the impact of sample size differences on the test results. While maintaining the core technical objective of achieving uniform coal sample quality, the fixed-weight processing can be implemented using other mechanical or structural methods, such as quantification through volume-density conversion or by using a multi-stage screening structure to remove excess coal samples. Although the specific implementation methods differ, all of the above alternative solutions ensure that the coal samples entering the testing body are under uniform quality standards, thus ensuring that humidity becomes the primary variable affecting the physical behavior of the coal sample, consistent with the technical concept of this invention.
[0061] In some alternative implementations, the humidity of the coal block can be determined by the evacuation time, flow rate fluctuation per unit time, or angle of repose during the coal sample's descent. Without altering the detection mechanism based on physical behavior response to characterize humidity, humidity determination can also be based on equivalent assessments of changes in flow resistance, changes in packing state, or stable descent time characteristics of the coal sample within a confined channel. These different parameter forms essentially all stem from the influence of coal sample humidity on its physical behavior characteristics, achieving the same humidity determination effect as this invention.
[0062] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.
Claims
1. A method for detecting the moisture content of coal blocks, characterized in that, Includes the following steps: A mapping model between the humidity gradient of standard coal blocks and the venting time is established in advance; Coal samples were collected on-site immediately and screened to obtain sieved coal samples with particle sizes below the standard particle size. The screened coal sample is weighed to obtain a standard mass of the screened coal sample; The standard quality sieved coal sample falls and empties through the measuring port in the measuring chamber, and the actual emptying time of the falling and emptying is measured; Based on the actual venting time and the mapping model, the corresponding actual coal lump humidity is obtained; The standard coal block has a standard mass and a particle size below the standard particle size.
2. The method for detecting the moisture content of coal blocks according to claim 1, characterized in that, The steps for "pre-establishing a mapping model between the humidity gradient of standard coal blocks and the venting time" include: Coal samples were collected from multiple mines and environmental data at the sampling points were recorded. The collected coal samples were transferred to a laboratory environmental simulation chamber, and the parameters inside the laboratory environmental simulation chamber were adjusted to be consistent with the environmental data of the sampling point. The collected coal samples were sieved to obtain coal samples with a particle size below the standard particle size, and the sieved coal samples were made into multiple sets of known humidity standard samples with fixed humidity gradient differences. Each set of known humidity standard samples of standard quality is dropped into the measurement chamber through the measurement port and emptied, and the emptying time of each set of known humidity standard samples is recorded. Based on the venting time of multiple sets of known humidity standard samples, a mapping model between the humidity gradient and venting time of the standard coal block is established.
3. The method for detecting the moisture content of coal blocks according to claim 1, characterized in that, In the step of "weighing the screened coal sample to obtain a standard mass of the screened coal sample": Open the feed gate to control the screening coal sample to enter the weighing bin; The mass of the screened coal sample entering the fixed-weight bin is detected by a dynamic weighing sensor. When the detection result reaches the standard mass, the feed gate is closed. After confirming that the test result is of standard quality in a static state, the discharge gate is opened to allow the standard quality sieved coal sample to enter the measuring chamber.
4. The method for detecting the moisture content of coal blocks according to claim 1, characterized in that, The steps for "measuring the actual emptying time during the fall" include: When the screened coal sample begins to fall through the measuring port and the infrared beam emitted by the infrared transmitter to the infrared receiver changes from a through state to a blocked state, the timer is started. When the standard mass of the screened coal sample falls and is emptied from the measuring port, and the infrared beam emitted by the infrared transmitter to the infrared receiver returns from the blocked state to the through state, the timer is controlled to stop timing, and the actual emptying time is obtained. The infrared transmitter and the infrared receiver are located at the measurement port.
5. The method for detecting the moisture content of coal blocks according to claim 1, characterized in that, The measuring cavity includes a flow-limiting channel that narrows from bottom to top. The flow-limiting channel includes two opposing sidewalls, and the two sidewalls have different angles with respect to the horizontal plane. In the step of "the standard mass of the screened coal sample falling into the measuring chamber through the measuring port and being discharged": When the screened coal sample passes through the flow-limiting channel, the two sidewalls of the flow-limiting channel exert unbalanced pressure on the screened coal sample, so that the screened coal sample passes through the measuring port continuously and without arching.
6. The method for detecting the moisture content of coal blocks according to claim 2, characterized in that, The steps of "establishing a mapping model between the humidity gradient and the venting time of the standard coal block based on the venting time of multiple sets of known humidity standard samples" include: Based on test data from multiple mines, multiple mapping curves between the humidity gradient and venting time of the standard coal block were plotted, and the multiple mapping curves were calibrated by weighted average to obtain a standard card comparison table of humidity gradient and venting time of the standard coal block.
7. The method for detecting the moisture content of coal blocks according to claim 2, characterized in that, The method further includes: The experiment was repeated multiple times for each group of known humidity standard samples to remove outlier time data.
8. The method for detecting the moisture content of coal blocks according to claim 3, characterized in that, The measuring cavity is located below the weighing chamber, and the measuring port is offset from the vertical axis of the weighing chamber.
9. A coal lump moisture detection device, characterized in that, A method for implementing the coal lump moisture detection method according to any one of claims 1-8, comprising a screen, a weighing bin, a measuring chamber, and a timing module; The screen is used to screen the coal sample to obtain a screened coal sample with a particle size below the standard particle size. The weighing bin is used to weigh the screened coal sample to obtain a standard mass of the screened coal sample. The induction timing module is used to measure the actual emptying time of the falling coal sample.
10. The coal lump moisture detection device according to claim 9, characterized in that, The measuring cavity includes a flow-limiting channel and a bottom wall. The flow-limiting channel is designed to narrow from bottom to top, and the bottom end of the flow-limiting channel is connected to the bottom wall. The measuring port is provided on the bottom wall. The flow-limiting channel includes two opposing sidewalls, and the two sidewalls have different angles with the horizontal plane. The measuring port is offset relative to the vertical axis of the fixed weight bin.