Coal inflow furnace metering and on-line monitoring system

Abstract

The application discloses a coal inflow stove metering and online monitoring system, which comprises a coal inflow stove module, a data acquisition module and a control module.The coal inflow stove module can deliver raw coal to a boiler for combustion.The data acquisition module acquires data of the coal inflow to the stove module.The control module meters the coal inflow to the stove according to the data information analysis of the data acquisition module and controls the equipment of the coal inflow stove module.The coal inflow quantity of the boiler is calculated through raw coal metering and stone coal metering, so that the precision of the coal inflow metering of the boiler is improved.The coal flow process is monitored, and when an abnormality occurs, the abnormality is judged and an alarm is given, so that the stability of the coal inflow to the stove is improved and the stability of the boiler load is improved.

Description

Technical Field

[0001] This invention relates to the field of coal inflow metering technology, and more specifically to a coal inflow metering and online monitoring system for furnaces. Background Technology

[0002] In my country, coal is the primary fuel source for thermal power generation, and this will remain the dominant energy source for a considerable period. Future coal-fired power units will develop towards higher efficiency, energy conservation, blended combustion, and ultra-low emissions. During boiler coal combustion, operators are particularly concerned about the actual amount of coal fed into the furnace at the bottom layer and the stability of the coal flow process. Currently, the equipment in the coal flow process is like a black box for operators; the internal conditions are difficult to monitor in real time, hindering operational adjustments. Meanwhile, switching to lower-priced coal or blended coal has become a primary measure for thermal power units to reduce costs. However, using lower-priced coal and blended coal increases impurities, leading to greater deviations in boiler load calculations when using only the coal feeder.

[0003] Therefore, how to further measure the coal flow and maintain the stability of coal transportation is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a coal inflow metering and online monitoring system, which improves the accuracy of raw coal inflow metering by metering the coal feeder and the stone coal; and improves the stability of coal flow operation by detecting the material level in the raw coal hopper and the pulverized coal silo.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] Preferably, the above-mentioned coal inflow metering and online monitoring system includes:

[0007] The coal inlet module is able to transport raw coal to the boiler for combustion;

[0008] The data acquisition module collects data on the coal flow of the coal inflow furnace module;

[0009] The control module analyzes the data information from the data acquisition module, measures the amount of coal flowing into the furnace, and controls the equipment of the coal inflow module.

[0010] Preferably, in the above-mentioned coal inflow metering and online monitoring system, the coal inflow module includes:

[0011] The raw coal hopper is used to store raw coal, and a first valve is installed at its outlet to control the opening degree of the outlet.

[0012] A coal feeder is used to transport raw coal, and its conveyor belt corresponds to the coal outlet of the raw coal hopper.

[0013] A coal mill grinds raw coal into powder and separates impurities; its inlet is connected to the outlet of the coal feeder.

[0014] The stone coal hopper has its inlet connected to the stone coal outlet of the coal mill to temporarily collect the stone coal produced from the raw coal, and a second valve is installed at its outlet.

[0015] A collection box is connected to the coal outlet of the stone and coal hopper to collect the stone and coal particles produced from the raw coal.

[0016] The coal powder bin has its inlet connected to the outlet of the coal mill to collect the generated coal powder;

[0017] The coal feeder has its inlet connected to the outlet of the coal powder bin, and sends the coal powder into the boiler for combustion via primary air.

[0018] Preferably, in the above-mentioned coal inflow metering and online monitoring system, the data acquisition module includes:

[0019] The first distance sensor is installed at the top of the raw coal hopper to measure the distance from the raw coal to the top of the raw coal hopper;

[0020] The first weighing device is installed below the conveyor belt of the coal feeder to weigh and measure the raw coal transported by the belt.

[0021] The second weighing device is installed below the collection box to detect the weight of the stones and coal inside the collection box;

[0022] The second distance sensor is installed at the top of the pulverized coal silo to measure the distance from the pulverized coal to the top of the pulverized coal silo.

[0023] Preferably, in the above-mentioned coal inflow metering and online monitoring system, the control module includes:

[0024] Storage unit: stores raw coal at a high threshold, stores raw coal at a low threshold, and stores pulverized coal at a low threshold.

[0025] The metering unit acquires data information from the first weighing device and the second weighing device to measure the coal flowing into the furnace;

[0026] The raw coal control unit acquires data information from the first ranging sensor, compares and analyzes it with the raw coal high threshold and the raw coal low threshold, and issues an early warning and makes adjustments to the quantity of raw coal in the raw coal bunker.

[0027] The coal powder control unit acquires data information from the second ranging sensor, compares and analyzes it with the low threshold of coal powder, and issues an early warning and makes adjustments to the amount of coal powder in the coal powder bin.

[0028] The alarm unit compares and analyzes the data from the second ranging sensor and the second weighing device to determine whether a blockage has occurred in the coal flow.

[0029] Preferably, in the above-mentioned coal inflow metering and online monitoring system, the metering unit specifically performs the following process:

[0030] Step 1: Obtain the data information of the first weighing device and calculate the cumulative coal amount of the coal feeder within a preset time period as the first weight;

[0031] Step 2: At the end of the preset time period, open the second valve to allow the stones and coal in the stone and coal hopper to flow into the collection box;

[0032] Step 3: Obtain the data information from the second weighing sensor and calculate the weight of the stones and coal generated within a preset time period as the second weight;

[0033] Step 4: Calculate the weight of the coal powder entering the coal powder silo based on the first weight and the second weight.

[0034] Preferably, in the above-mentioned coal inflow metering and online monitoring system, the raw coal control unit specifically operates as follows:

[0035] Step 1: Obtain the data information from the first ranging sensor and convert the data information into digital information as the distance to the raw coal.

[0036] Step 2: When the distance to the raw coal is less than the low threshold of the raw coal, generate a low raw coal warning message;

[0037] Step 3: Upon receiving the low raw coal warning information, replenish the raw coal in the raw coal hopper;

[0038] Step 4: When the distance to the raw coal is greater than the high threshold of the raw coal, generate a high-altitude coal early warning information;

[0039] Step 5: Upon receiving the high-altitude coal early warning information, stop replenishing the raw coal hopper.

[0040] Preferably, in the above-mentioned coal inflow metering and online monitoring system, the pulverized coal control unit specifically operates as follows:

[0041] Step 1: Acquire the data information from the second ranging sensor and convert the data information into digital information as the distance between coal powder particles;

[0042] Step 2: When the distance between the coal dust particles and the coal dust particles is less than the low threshold for coal dust particles, a low coal dust particle warning message is generated.

[0043] Step 3: Upon receiving the low coal powder warning information, adjust the opening of the first valve and simultaneously increase the transmission speed of the coal feeder belt;

[0044] Step four: After determining that the pulverized coal distance has remained stable, stop adjusting the first valve and the coal feeder.

[0045] Preferably, in the above-mentioned coal inflow metering and online monitoring system, the alarm unit specifically operates as follows:

[0046] If the historical data of the second weighing device is obtained and the data of the second weighing device does not change or the change value deviates significantly after the second valve is opened, it is determined that the stone and coal outlet is blocked, and a stone and coal blockage alarm is generated.

[0047] Historical data from the second ranging sensor is acquired. When the opening of the powder feeder outlet and the opening of the first valve remain unchanged, the distance detected by the second ranging sensor continues to shorten, indicating that the powder feeder is blocked, and a powder feed blockage alarm is generated.

[0048] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] 1. By measuring raw coal and stone coal, the accuracy of boiler coal feed rate is improved.

[0050] 2. By monitoring the coal flow process, abnormalities are identified and alarms are triggered when they occur, which improves the stability of coal flow into the furnace and enhances the stability of boiler load. Attached Figure Description

[0051] 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0052] Figure 1 The attached figure is a schematic diagram of the system composition of the present invention.

[0053] Figure 2 The attached figure is a schematic diagram of the coal flow metering process of the present invention. Detailed Implementation

[0054] 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 a part of the embodiments of the present invention, and not all of them. 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.

[0055] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be 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.

[0056] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0057] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. 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.

[0058] like Figure 1 As shown in the figure, an embodiment of the present invention discloses a coal inflow metering and online monitoring system, comprising:

[0059] The coal inlet module is able to transport raw coal to the boiler for combustion;

[0060] The data acquisition module collects data on the coal flow into the furnace module;

[0061] The control module analyzes the data from the data acquisition module, measures the amount of coal flowing into the furnace, and controls the equipment in the coal inflow module.

[0062] The control module can be a PLC or a remote service module, which is existing technology.

[0063] The beneficial effects of the above embodiments are as follows: by measuring the raw coal and the stone coal, the accuracy of the boiler coal feed rate is improved; by monitoring the coal flow process, abnormalities are identified and alarms are triggered when they occur, thereby improving the stability of coal flow into the furnace and improving the stability of the boiler load.

[0064] In one embodiment, the coal inflow furnace module in the above-mentioned coal inflow furnace metering and online monitoring system includes:

[0065] The raw coal hopper is used to store raw coal, and a first valve is installed at its outlet to control the opening degree of the outlet.

[0066] A coal feeder is used to transport raw coal, and its conveyor belt corresponds to the coal outlet of the raw coal hopper.

[0067] A coal mill grinds raw coal into powder and separates impurities; its inlet is connected to the outlet of a coal feeder.

[0068] The stone coal hopper has its inlet connected to the stone coal outlet of the coal mill to temporarily collect the stone coal produced from the raw coal. A second valve is installed at its outlet.

[0069] The collection box is connected to the coal outlet of the gravel and coal hopper to collect the gravel and coal produced from the raw coal.

[0070] The pulverized coal bin has its inlet connected to the outlet of the coal mill to collect the generated pulverized coal.

[0071] The coal feeder has its inlet connected to the outlet of the coal powder silo, and uses primary air to send coal powder into the boiler for combustion.

[0072] Both the first valve and the second valve are existing technologies.

[0073] The working principle in the above embodiment is as follows: the raw coal in the raw coal hopper falls onto the conveyor belt of the coal feeder. The first valve set at the coal outlet controls the flow rate of raw coal by adjusting the opening of the first valve. The coal feeder transports the raw coal to the coal mill, which crushes the raw coal into powder and separates the coking coal. The coking coal enters the coking coal hopper for temporary storage. After receiving the information, the second valve is opened to transport the coking coal to the collection box. The coal powder in the coal mill enters the coal powder silo and is transported to the coal feeder, where it is blown into the boiler by primary air.

[0074] In one embodiment, the data acquisition module of the above-mentioned coal inflow metering and online monitoring system includes:

[0075] The first distance sensor is fixedly connected to the top of the raw coal hopper by bolts to measure the distance from the raw coal to the top of the raw coal hopper;

[0076] The first weighing device is installed below the conveyor belt of the coal feeder to weigh and measure the raw coal transported by the belt.

[0077] The second weighing device is located below the collection box to detect the weight of the stones and coal inside the collection box.

[0078] The second distance sensor is installed on the top of the pulverized coal silo to measure the distance from the pulverized coal to the top of the silo.

[0079] Among them, the first and second ranging sensors are preferably laser ranging sensors, which are existing technologies; the first and second weighing devices are preferably electromagnetic force weighing sensors, which are existing technologies; all the above devices are connected to a signal converter via wires to convert data information into digital information, the signal converter is connected to a signal transmitter, and the detected data information is sent to the control module through the signal transmitter.

[0080] In one embodiment, the control module of the above-mentioned coal inflow metering and online monitoring system includes:

[0081] Storage unit, storing raw coal with a high threshold, storing raw coal with a high threshold, storing pulverized coal with a low threshold;

[0082] The metering unit acquires data from the first and second weighing devices to measure the coal flowing into the furnace;

[0083] The raw coal control unit acquires data from the first ranging sensor, compares and analyzes it with the high and low thresholds for raw coal, and provides early warnings and adjustments to the quantity of raw coal in the raw coal bunker.

[0084] The coal powder control unit acquires data from the second ranging sensor, compares and analyzes it with the low threshold of coal powder, and issues an early warning and makes adjustments to the amount of coal powder in the coal powder silo.

[0085] The alarm unit compares and analyzes the data from the second ranging sensor and the second weighing device to determine whether a blockage has occurred in the coal flow.

[0086] Among them, the high threshold for raw coal, the high threshold for raw coal, and the low threshold for pulverized coal are all preset values, and the specific values ​​can be changed through the human-machine interface of the control module.

[0087] In one embodiment, in the above-mentioned coal inflow furnace metering and online monitoring system, the metering unit specifically operates as follows:

[0088] Step 1: Obtain data information from the first weighing device and calculate the cumulative coal quantity of the coal feeder within a preset time period as the first weight;

[0089] Step 2: At the end of the preset time period, open the second valve to allow the stones and coal in the stone and coal hopper to flow into the collection box;

[0090] Step 3: Obtain data from the second weighing sensor and calculate the weight of the stones and coal generated within the preset time period as the second weight;

[0091] Step 4: Based on the first and second weights, the coal flow measurement within the preset time period is used to calculate the weight of coal entering the coal powder silo.

[0092] It should be noted that a boiler unit can correspond to multiple coal feeders. For example, a 300MW boiler unit is generally equipped with 6 medium-speed coal mills, 5 of which are in operation and 1 is on standby. Some units are also equipped with 5 medium-speed coal mills, 4 of which are in operation and 1 is on standby. Each coal mill corresponds to one coal feeder.

[0093] The first weight is the total amount of raw coal conveyed by all coal feeders, and the second weight is the total amount of stone coal produced by all coal mills.

[0094] The collection box is connected to the stone coal outlet of all the coal mills in the boiler, so the second weight calculated by the second weighing sensor is the total amount of stone coal produced by the corresponding coal mill in the boiler.

[0095] The preset time period is the coal flow measurement unit time. The coal flow is measured once every unit time, forming a closed-loop measurement. The measurement data is updated in real time to the human-machine interface of the control module.

[0096] The beneficial effects of the above embodiments are: by measuring raw coal and stone coal, the accuracy of coal flow measurement is improved;

[0097] In one embodiment, the raw coal control unit in the above-mentioned coal inflow metering and online monitoring system for furnaces operates as follows:

[0098] Step 1: Acquire data from the first ranging sensor and convert the data into digital information, namely the distance to the raw coal.

[0099] Step 2: When the distance to raw coal is less than the low threshold for raw coal, a low raw coal warning message is generated;

[0100] Step 3: Upon receiving the low raw coal warning information, replenish the raw coal in the raw coal bin;

[0101] Step 4: When the distance to the raw coal exceeds the high threshold of the raw coal, generate a high-altitude coal early warning information;

[0102] Step 5: Upon receiving the high-altitude coal warning information, cease replenishing the raw coal bins.

[0103] The above embodiments monitor the amount of raw coal in the raw coal hopper, thereby improving the stability of coal flow operation.

[0104] In one embodiment, the coal powder control unit in the above-mentioned coal inflow metering and online monitoring system for a furnace operates as follows:

[0105] Step 1: Acquire data from the second ranging sensor and convert the data into digital information, namely the distance between coal dust particles;

[0106] Step 2: When the distance between the coal dust particles and the low coal dust particle threshold is less than the low coal dust particle threshold, a low coal dust particle warning message is generated.

[0107] Step 3: Upon receiving the low pulverized coal warning information, adjust the opening of the first valve and simultaneously increase the transmission speed of the feeder belt.

[0108] Step four: After confirming that the pulverized coal distance has stabilized, stop adjusting the first valve and the coal feeder.

[0109] The above embodiment describes how the DCS system adjusts the boiler load and regulates the opening of the pulverized coal feeder outlet, which simultaneously causes the pulverized coal level in the pulverized coal silo to drop, disrupting the stability of the coal flow. The system also regulates the coal flow rate from the raw coal hopper, sets up a safety adjustment unit, and verifies the changes in the pulverized coal silo after each adjustment of the first valve. If the silo remains unstable, the first valve is adjusted again until the pulverized coal level in the silo stabilizes, thus improving the stability of the coal flow.

[0110] In one embodiment, the alarm unit in the above-mentioned coal inflow metering and online monitoring system for furnaces operates as follows:

[0111] If the historical data of the second weighing device is obtained and the data of the second weighing device does not change or the change value deviates significantly after the second valve is opened, it is determined that the stone and coal outlet is blocked and a stone and coal blockage alarm is generated.

[0112] Historical data from the second ranging sensor is acquired. When the opening of the powder feeder outlet and the opening of the first valve remain unchanged, the distance detected by the second ranging sensor continues to shorten, indicating that the powder feeder is blocked, and a powder feeder blockage alarm is generated.

[0113] Blockages can occur during coal flow. By analyzing historical data, blockages can be identified in a timely manner, reducing the occurrence of malfunctions and improving the stability of coal flow operation.

[0114] It should be noted that the above embodiments are merely illustrative examples of the division of functional modules. In practical applications, the functions described above can be assigned to different functional modules as needed, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiments can be merged into one module, or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are merely for distinguishing the various modules or steps and are not considered as an improper limitation of the present invention.

[0115] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0116] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0117] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention is also intended to include these modifications and variations in the above description of the disclosed embodiments, enabling those skilled in the art to implement or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, this invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A coal inflow metering and online monitoring system, characterized in that, include: The coal inlet module is able to transport raw coal to the boiler for combustion; The data acquisition module collects data on the coal flow of the coal inflow furnace module; The control module analyzes the data information from the data acquisition module, measures the amount of coal flowing into the furnace, and controls the equipment of the coal inflow module. The coal inflow module includes: The raw coal hopper is used to store raw coal, and a first valve is installed at its outlet to control the opening degree of the outlet. A coal feeder is used to transport raw coal, and its conveyor belt corresponds to the coal outlet of the raw coal hopper. A coal mill grinds raw coal into powder and separates impurities; its inlet is connected to the outlet of the coal feeder. The stone coal hopper has its inlet connected to the stone coal outlet of the coal mill to temporarily collect the stone coal produced from the raw coal, and a second valve is installed at its outlet. A collection box is connected to the coal outlet of the stone and coal hopper to collect the stone and coal particles produced from the raw coal. The coal powder bin has its inlet connected to the outlet of the coal mill to collect the generated coal powder; The coal feeder has its inlet connected to the outlet of the coal powder bin, and sends the coal powder into the boiler for combustion through primary air. The data acquisition module includes: The first distance sensor is installed at the top of the raw coal hopper to measure the distance from the raw coal to the top of the raw coal hopper; The first weighing device is installed below the conveyor belt of the coal feeder to weigh and measure the raw coal transported by the belt. The second weighing device is installed below the collection box to detect the weight of the stones and coal inside the collection box; The second ranging sensor is installed at the top of the pulverized coal silo to measure the distance from the pulverized coal to the top of the pulverized coal silo. The control module includes: Storage unit: stores raw coal at a high threshold, stores raw coal at a low threshold, and stores pulverized coal at a low threshold. The metering unit acquires data information from the first weighing device and the second weighing device to measure the coal flowing into the furnace; The raw coal control unit acquires data information from the first ranging sensor, compares and analyzes it with the raw coal high threshold and the raw coal low threshold, and issues an early warning and makes adjustments to the quantity of raw coal in the raw coal hopper. The coal powder control unit acquires data information from the second ranging sensor, compares and analyzes it with the low threshold of coal powder, and issues an early warning and makes adjustments to the amount of coal powder in the coal powder bin. The alarm unit compares and analyzes the data from the second ranging sensor and the second weighing device to determine whether a blockage has occurred in the coal flow.

2. The coal inflow metering and online monitoring system according to claim 1, characterized in that, The metering unit operates as follows: Step 1: Obtain the data information of the first weighing device and calculate the cumulative coal amount of the coal feeder within a preset time period as the first weight; Step 2: At the end of the preset time period, open the second valve to allow the stones and coal in the stone and coal hopper to flow into the collection box; Step 3: Obtain the data information from the second weighing device and calculate the weight of the stones and coal generated within the preset time period as the second weight; Step 4: Calculate the weight of the coal powder entering the coal powder silo based on the first weight and the second weight.

3. The coal inflow metering and online monitoring system according to claim 1, characterized in that, The specific process of the raw coal control unit is as follows: Step 1: Obtain the data information from the first ranging sensor and convert the data information into digital information as the distance to the raw coal. Step 2: When the distance to the raw coal is less than the low threshold of the raw coal, generate a low raw coal warning message; Step 3: Upon receiving the low raw coal warning information, replenish the raw coal in the raw coal hopper; Step 4: When the distance to the raw coal is greater than the high threshold of the raw coal, generate a high-altitude coal early warning information; Step 5: Upon receiving the high-altitude coal early warning information, stop replenishing the raw coal hopper.

4. The coal inflow metering and online monitoring system according to claim 1, characterized in that, The specific process of the pulverized coal control unit is as follows: Step 1: Acquire the data information from the second ranging sensor and convert the data information into digital information as the distance between coal powder particles; Step 2: When the distance between the coal dust particles and the coal dust particles is less than the low threshold for coal dust particles, a low coal dust particle warning message is generated. Step 3: Upon receiving the low coal powder warning information, adjust the opening of the first valve and simultaneously increase the transmission speed of the coal feeder belt; Step four: After determining that the pulverized coal distance has remained stable, stop adjusting the first valve and the coal feeder.

5. The coal inflow metering and online monitoring system according to claim 1, characterized in that, The alarm unit operates as follows: If the historical data of the second weighing device is obtained and the data of the second weighing device does not change or the change value deviates significantly after the second valve is opened, it is determined that the stone and coal outlet is blocked, and a stone and coal blockage alarm is generated. Historical data from the second ranging sensor is acquired. When the opening of the powder feeder outlet and the opening of the first valve remain unchanged, the distance detected by the second ranging sensor continues to shorten, indicating that the powder feeder is blocked, and a powder feed blockage alarm is generated.

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