Method and device for detecting flowability of raw coal in raw coal bunker

Abstract

The application provides a raw coal flowability detection method and device in a raw coal bin, and relates to the technical field of electromagnetic detection. The method solves the technical problem that the existing technology cannot timely determine whether coal blocking occurs in the raw coal bin. The method comprises the following steps: detecting the flow of raw coal in a detection area near the outlet of the raw coal bin; determining whether the detected flow is abnormal; if yes, determining whether cleaning and unblocking are needed; if yes, controlling the unblocking device to start and / or sending an alarm instruction. The application uses flowability detection to determine whether the coal flow in the cross section of the storage bin is poor or stagnant. Through detection and analysis, the problem is found and corresponding measures are taken in time to eliminate the coal blocking hazard, thereby ensuring stable operation of the unit.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic detection technology, and in particular to a method and apparatus for detecting the fluidity of raw coal in a raw coal bunker. Background Technology

[0002] Thermal power plants typically operate continuously without interruption, and coal conveyor belts are generally not designed for 24-hour continuous operation. Therefore, an intermediate storage device is essential—the raw coal bunker. These bunkers are widely used; however, material blockages often occur during the discharge process, severely impacting normal equipment operation. This is particularly true in large thermal power plants equipped with direct-fired pulverizing systems. If a blockage occurs in the raw coal bunker, the unit is forced to reduce output and reduce load, or experience unstable boiler combustion leading to excessive oil injection. In severe cases, this can cause boiler flameout and unplanned unit shutdown. Large power plant boilers are generally equipped with several raw coal bunkers per boiler, for example, six. During belt conveyor operation, these six bunkers are replenished, with each bunker's storage capacity generally sufficient to meet the consumption of the corresponding coal feeder's rated output for 12 hours. Once each bunker is filled to the required level, belt conveyor operation is stopped.

[0003] A typical optimized structure for modern raw coal storage silos is a cylindrical upper section, a frustum-shaped middle section, and a hyperbolic conical lower section. (See also...) Figure 1 The top opening is large, and the bottom opening is small, with raw coal falling from top to bottom by its own weight. As the raw coal flows downwards within the conical coal bunker, the surface area gradually decreases, creating greater pressure on the coal itself. This increases the external force and probability of fine coal dust adhering to the inner wall of the bunker. Since the raw coal flows from the inner wall towards the central drop pipe, it doesn't significantly scour the inner wall. Therefore, under normal conditions, fine coal dust easily adheres to the inner wall of the bunker. Once adhered, the coefficient of friction increases rapidly, leading to layered accumulation of coal dust on the inner wall, further increasing friction and causing blockages.

[0004] The flow state of coal within a raw coal bunker (such as monolithic flow, funnel flow, or center flow) is determined not only by the bunker's apex angle and cross-sectional shrinkage rate but also, and perhaps more importantly, by the coal quality itself. Under design conditions, the coal flow within the raw coal bunker is monolithic. However, after changes in coal quality (increased moisture and enhanced agglomeration due to the blending of coal slime), the flow of coal within the raw coal bunker changes from monolithic flow to funnel flow or center flow. The probability of blockage in a center flow raw coal bunker is much higher than in a monolithic flow raw coal bunker.

[0005] Particle kinematics theory indicates that for dry particles, the opening size of the silo to prevent bridging must be at least three times the characteristic size of the particles, while for wet particles, the opening size must be at least four times the characteristic size. Although silo designs have considered and mitigated clogging factors, variations in impurity content and viscosity in raw coal, coupled with the tendency for wet materials to clump together during the rainy season and freeze easily in cold winters, all contribute to this problem. Especially with increasing moisture content, the coal's agglomeration rate increases dramatically. As the coal flows downwards within the silo, the pressure exerted by the silo walls increases, causing initially loose particles to clump together, resulting in significantly larger characteristic sizes. When the characteristic size of the coal clump reaches a certain critical value, clogging occurs. Furthermore, the adhesion and caking of wet coal on the inner walls of the discharge port further narrows the opening, increasing the likelihood of clogging.

[0006] Different types of coal exhibit varying degrees of agglomeration. This agglomeration directly impacts the coal blockage situation in raw coal bunkers. Coal moisture content is also a significant factor influencing blockage; increased moisture enhances coal agglomeration, leading to a larger dynamic angle of repose and decreased fluidity. In actual production, it has been observed that when the coal moisture content (external moisture) reaches 8%, some poorly designed raw coal bunkers (rectangular bunkers, center-flow bunkers) begin to experience blockage and bridging. When the moisture content reaches 10%, the pressure generated by the coal's own weight on the downward sliding of coal particles increases, increasing inter-particle adhesion and reaching a peak in particle compression. This makes the coal easily compacted and adhered to the inner wall of the hopper, resulting in poor overall fluidity and severe blockage. When the moisture content reaches 12%, blockage and bridging occur frequently, and coal freezing is also likely to occur in winter. Specifically, under the existing conditions of coal bunker and coal slime moisture content, the proportion of coal slime blended in should not exceed 30%. When the blending ratio is 40% to 50%, the frequency of coal blockage in the coal bunker will increase exponentially. In addition to continuously operating the loosening device, it is also necessary to regularly empty the coal bunker to ensure safe coal delivery in the short term.

[0007] Common methods for clearing blockages in raw coal bunkers include manual unblocking, using a bunker wall vibrator, using an air cannon, using a loosening machine, and installing stainless steel or PU board linings on the inner bunker walls.

[0008] The applicant has discovered that the prior art has at least the following technical problems:

[0009] Currently, the presence of coal blockage is determined by the amount of raw coal flowing out of the coal bunker. If the amount of raw coal flowing out of the bunker decreases, measures to clear the blockage are taken. However, the location of the blockage or bridging within the coal bunker is uncertain, resulting in low efficiency in clearing the blockage. Furthermore, the method of determining whether a blockage has occurred based on the amount of raw coal flowing out of the bunker assumes that a blockage has already occurred, meaning that it cannot predict potential blockages within the coal bunker in a timely manner. Summary of the Invention

[0010] The purpose of this invention is to provide a method and apparatus for detecting the fluidity of raw coal in a raw coal bunker, so as to solve the technical problem in the prior art that it is difficult to timely determine the possibility of coal blockage in a raw coal bunker. 。 The preferred technical solutions among the many technical solutions provided by this invention can produce a variety of technical effects, which are described in detail below.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] The present invention provides a method for detecting the flowability of raw coal in a raw coal bunker, comprising: detecting the flow of raw coal in a detection area near the outlet of the raw coal bunker; determining whether the detected flow is abnormal; if so, determining whether unblocking treatment is required; if so, controlling the start of the unblocking device and / or controlling the issuance of an alarm indication.

[0013] Furthermore, the flow of raw coal in the detection area near the outlet of the raw coal bunker is detected, including: using a detector to detect the flow velocity of raw coal in the area near the outlet of the raw coal bunker; establishing a flow state diagram inside the raw coal bunker based on the detector detection signal; wherein, the detector can emit and receive electromagnetic waves or sound waves.

[0014] Furthermore, a testing zone is formed 1-3 meters above the raw coal bunker outlet.

[0015] Further, determining whether unblocking is necessary includes the following: determining whether there is a significant decrease in coal flow rate or stagnation in a localized area of ​​the raw coal bunker; if so, unblocking is necessary.

[0016] Furthermore, if it is determined that unblocking is necessary: ​​identify areas where the coal flow rate is significantly reduced or stagnant; display the location of the areas that need unblocking.

[0017] Furthermore, it also includes: recording the congestion clearing situation in each area; calculating the frequency of congestion clearing in each area; and displaying the statistical results.

[0018] Furthermore, it also includes: determining whether there are foreign objects in the detection area; if so, controlling the system to issue an alarm indication.

[0019] The present invention provides an apparatus comprising: a detection module for detecting the flow of raw coal in a detection area near the outlet of a raw coal bunker; an analysis module for determining whether the detected flow is abnormal and whether unblocking is required; and an execution module for controlling the start of the unblocking device and / or controlling the issuance of an alarm indication.

[0020] The preferred technical solution of this invention can produce at least the following technical effects: During the downward flow of raw coal in a coal bunker under gravity, coal flow stagnation may occur in certain areas due to coal quality characteristics or bunker structure, leading to coal feeder interruption and impacting the safe and stable production of the unit. Based on this, this invention proposes a method for detecting the flowability of raw coal in a coal bunker. By detecting flowability, it identifies instances of obstructed or stagnant coal flow in the bunker cross-section. Through detection and analysis, the problem is identified, and corresponding measures are taken in a timely manner to eliminate the risk of coal flow interruption, thereby ensuring the stable operation of the unit. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0022] Figure 1 This is a simplified view of the existing raw coal bunker;

[0023] Figure 2 This is a schematic diagram showing coal bridging inside an existing raw coal bunker;

[0024] Figure 3 A schematic diagram showing a detector installed on the raw coal bunker;

[0025] Figure 4 This is a flowchart of the method for detecting the fluidity of raw coal in a raw coal bunker provided by the present invention;

[0026] Figure 5 This is a control process framework diagram provided by the present invention.

[0027] In the diagram: 1. Raw coal bunker; 2. Detector; 3. Void. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] See Figure 5 This invention provides a method for detecting the fluidity of raw coal in a raw coal bunker, including...

[0030] The flow of raw coal in the detection area near the outlet inside the raw coal bunker is monitored;

[0031] Determine if the detected flow is abnormal;

[0032] If so, determine whether clearing the blockage is necessary;

[0033] If so, then control the activation of the unblocking device and / or control the issuance of an alarm indication.

[0034] During the downward flow of raw coal in a coal bunker under gravity, coal flow stagnation can occur in certain areas due to coal quality characteristics or bunker structure, leading to coal feeder interruptions and impacting the safe and stable operation of the unit. Based on this, this invention proposes a method for detecting the flowability of raw coal in a coal bunker. This method identifies instances of obstructed or stagnant coal flow at the bunker's cross-section. Through detection and analysis, the problem is identified, and corresponding measures are taken promptly to eliminate the potential coal flow interruption hazard, thereby ensuring the stable operation of the unit.

[0035] "Detecting the flow of raw coal in the detection area near the outlet of the raw coal bunker" means that the present invention uses flowability detection to detect abnormalities in the flowability of raw coal (material) in advance, and then take effective measures to deal with them.

[0036] Upon discovering areas of stagnant or cavitary coal flow, unblocking measures should be implemented as needed. Targeted unblocking devices should be activated promptly to eliminate stagnation and cavities, ensuring normal coal feeding and meeting required quantities. Once the stagnation or cavities are cleared, the unblocking devices should be shut down and placed in standby mode. Alternatively, manual intervention can be used. When unblocking is deemed necessary, an alarm can be triggered, and operators can adjust the operation of the corresponding coal mills and feeders. For example, the feeder can be temporarily stopped; if the coal supply is severe, the coal mill can be further stopped, and the operation should be handled according to the operating procedures. Once the coal supply is restored and normal coal feeding has resumed, the pulverizing system can be restarted.

[0037] In addition, it should be noted that the present invention is provided for detecting the flow of raw coal in a raw coal bunker, but it can also be applied to detecting the flowability of materials in other storage tanks.

[0038] Regarding "monitoring the flow of raw coal in the testing area near the outlet of the raw coal bunker," the specific details are as follows:

[0039] The flow rate of raw coal in the area near the outlet of the raw coal bunker is detected by a detector;

[0040] A flow state diagram inside the raw coal bunker is established based on the detector signals.

[0041] The detector can emit and receive electromagnetic waves or sound waves.

[0042] Electromagnetic waves or ultrasonic waves can penetrate metal silo walls and reinforced concrete building cylinder walls. Appropriate detection methods can be selected for different solid particulate materials and silo structures.

[0043] "Using detectors to detect the flow velocity of raw coal in the area near the outlet of the raw coal bunker" involves using electromagnetic waves or ultrasonic waves of a specific wavelength to probe the internal structure of raw coal or solid particle storage devices, such as raw coal bunkers and storage tanks. Finally, by analyzing the transmitted and reflected waves, a two-dimensional or three-dimensional flow pattern inside the storage bunker is generated. Electromagnetic wave detection technology and ultrasonic detection technology are currently widely used and mature industrial technologies, and will not be described in detail here.

[0044] In addition, a flow status diagram of the raw coal bunker is established based on the detection signals of the detectors. By observing the status diagram, staff can actively control the unblocking device or take other corresponding measures to eliminate the risk of coal shortage, thereby ensuring the stable operation of the unit.

[0045] See Figure 3 The diagram illustrates detector 2 on the raw coal bunker 1. There can be at least one, two, or three detectors, evenly spaced along the circumference of the raw coal bunker 1. The detectors simultaneously transmit and receive echoes (reflected waves). Alternatively, the detectors can have single-transmit and single-receive capabilities; in this case, at least two detectors are used, one as a transmitter and the other as a receiver.

[0046] The detectors can be fixed and mounted on the silo wall, or they can move along the silo wall with corresponding guide rails. For mobile detectors, a reference point is set up to locate the mobile detector. By locating the mobile detector itself, the location of abnormal coal flow and the location of voids and coal bridging within the raw coal silo can be more accurately determined.

[0047] See Figure 4 The diagram illustrates the control process framework of each device.

[0048] Determine if the coal feeder is running;

[0049] If so, the detector will start and continue to operate, and the detector will send a signal to the controller.

[0050] If it is determined that the coal feeder has not started, then the detector is controlled to be in a disabled state;

[0051] The controller analyzes the signals transmitted from the detector and processes the signals.

[0052] If the system determines that unblocking is required, the unblocking device will be activated; otherwise, the detector will continue to operate and detect.

[0053] Regarding "determining whether congestion clearing is necessary," the following content is included:

[0054] Determine whether there is a significant decrease or stagnation in the coal flow rate in a localized area within the raw coal bunker;

[0055] If so, then it is determined that the blockage needs to be cleared.

[0056] When the coal flow is in a normal state within the silo, the velocity range and distribution of the raw coal flowing out of the silo are known. By analyzing the echoes, if it is found that the flow velocity in the solid particle area of ​​the silo is significantly slowed down, or the flow pattern of particles in certain areas is significantly different from that under normal conditions, it can be determined that unblocking treatment is required. At this time, the unblocking device that can be applied to the area can be activated in a timely and targeted manner to eliminate the stagnation of the coal flow, maintain the normal coal feeding from the silo, and ensure that the coal feed rate meets the requirements.

[0057] Regarding the monitoring of "significant decrease in coal flow rate", this can be achieved by limiting relevant parameters, and since it is possible using existing technology, we will not go into too much detail here.

[0058] When the coal flow stagnates and expands within the raw coal bunker, it creates internal cavities, commonly known as coal bridging. These cavities can be quite large, and if they form across the entire cross-section of the bunker, they will severely impact the smooth flow of coal from the feeding equipment. Therefore, when localized coal flow stagnation or cavities appear within the raw coal bunker, it is deemed necessary to clear the blockage. Clearing these blockages will eliminate the stagnation, ensuring normal coal flow and meeting the required coal feeding rate.

[0059] Preferably, a detection zone is formed in the area 1 to 3 meters above the raw coal bunker outlet.

[0060] In reality, the vast majority of coal shed locations are within the contraction section of the raw coal bunker, specifically within 2 to 3 meters above the bunker's outlet. Scanning this area using electromagnetic waves or ultrasound of specific wavelengths detects the coal flow velocity, allowing for the timely identification of points with abnormal velocity along the cross-section within the detection range.

[0061] Preferably, if it is determined that unblocking is required: identify areas where the coal flow rate is significantly reduced or stagnant; display the location of the areas that need unblocking.

[0062] If the specific location and size of the area within the coal bunker that needs to be cleared can be determined, targeted measures can be taken manually to improve the efficiency of clearing the blockage.

[0063] Preferably, the method for detecting the fluidity of raw coal in a raw coal bunker further includes:

[0064] Record the congestion clearing status in each area;

[0065] Statistics on the frequency of traffic congestion clearing in each area;

[0066] The statistical results are displayed.

[0067] By analyzing the blockage areas inside the raw coal bunker, if a blockage occurs frequently in a certain area, the bunker can be emptied for internal inspection, or other measures can be taken to eliminate the blockage, improve the flowability of the raw coal particles in that area, and thus completely eliminate this hidden danger and defect.

[0068] Preferably, the method for detecting the fluidity of raw coal in a raw coal bunker further includes:

[0069] Determine if there are foreign objects in the detection area;

[0070] If so, the control will issue an alarm indication.

[0071] If there are metal objects mixed in with the solid coal particles in the raw coal bunker, the foreign objects mixed in with the coal can be detected because the response of raw coal particles and metal objects to waves is significantly different. These foreign objects may include detached liners or metal parts carried by the coal conveyor. This alerts the operators to pay attention to the operating status of the coal mill and avoid problems such as excessive vibration in the mill.

[0072] An apparatus includes: a detection module for detecting the flow of raw coal in a detection area near the outlet of a raw coal bunker;

[0073] The analysis module determines whether the detected flow is abnormal and whether unblocking is necessary.

[0074] The execution module controls the start-up of the unblocking device and / or controls the issuance of alarm indications.

[0075] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments of the related methods described above, and will not be elaborated upon here.

[0076] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0077] In the description of this invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0078] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] Any process or method description in the flowchart or otherwise herein can be understood as: representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0080] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0081] Those skilled in the art will understand that all or part of the steps of the methods described in the above embodiments can be implemented by a program instructing related hardware, and the program can be stored in a computer-readable storage medium. When executed, the program includes one or a combination of the steps of the method embodiments.

[0082] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0083] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0084] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "a particular example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0085] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for detecting the fluidity of raw coal in a raw coal bunker, characterized in that, include The flow of raw coal in the detection area near the outlet inside the raw coal bunker is monitored; Determine if the detected flow is abnormal; If so, determine whether clearing the blockage is necessary; If so, then control the activation of the unblocking device and / or control the issuance of an alarm indication; Determining whether unblocking is necessary includes the following: Determine whether there is a significant decrease in coal flow velocity or stagnation in a localized area within the raw coal bunker; If so, then it is determined that the blockage needs to be cleared; Record the congestion clearing status in each area; Statistics on the frequency of traffic congestion clearing in each area; The statistical results are displayed.

2. The method for detecting the fluidity of raw coal in a raw coal bunker according to claim 1, characterized in that, Monitoring the flow of raw coal in the detection area near the outlet of the raw coal bunker, including: The flow rate of raw coal in the area near the outlet of the raw coal bunker is detected by a detector; A flow state diagram inside the raw coal bunker is established based on the detector signals. The detector can emit and receive electromagnetic waves or sound waves.

3. The method for detecting the fluidity of raw coal in a raw coal bunker according to claim 2, characterized in that, A testing zone is formed 1-3 meters above the raw coal bunker outlet.

4. The method for detecting the fluidity of raw coal in a raw coal bunker according to claim 1, characterized in that, If it is determined that clearing the blockage is necessary: Identify areas where the coal flow rate decreases significantly or stagnates. This displays the location of the area that needs to be cleared.

5. The method for detecting the fluidity of raw coal in a raw coal bunker according to claim 1, characterized in that, Also includes: Determine if there are foreign objects in the detection area; If so, the control will issue an alarm indication.

6. An apparatus for implementing the method for detecting the fluidity of raw coal in a raw coal bunker as described in any one of claims 1-5, characterized in that, include: The detection module detects the flow of raw coal in the detection area near the outlet inside the raw coal bunker. The analysis module determines whether the detected flow is abnormal and whether unblocking is necessary. The execution module controls the start-up of the unblocking device and / or controls the issuance of alarm indications.

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