Environment-friendly dust removal system for concrete mixing plant and control method thereof

Abstract

The application discloses an environment-friendly dust removal system for a concrete mixing station and a control method thereof, and the system comprises dust suppression, dust collection, hierarchical filtration, ash recycling devices and a locally deployed control unit. The dust suppression device and the dust collection device are cooperatively arranged at each dust generation point of aggregate feeding, conveying, powder storage, weighing, mixing and unloading; the control unit receives working condition signals in real time, starts and stops the dust suppression and dust collection devices of the corresponding points, and removes dust on demand. The hierarchical filtration device adopts a series connection of a primary settling chamber and a secondary bag-type dust collector, and the collected dust is transported back to the weighing system through the ash recycling device. The control method further comprises dynamically adjusting a spraying strategy according to environmental humidity and material moisture content, and predicting filter bag life and generating a maintenance warning based on equipment operation data. The application solves the problems of independent operation, lack of cooperation and intelligent control of various dust removal devices in the prior art, and has the advantages of energy saving and environmental protection, reliable operation and high automation degree.

Description

Technical Field

[0001] This invention relates to the field of environmental dust removal in concrete mixing plants, and more particularly to an environmental dust removal system and its control method for concrete mixing plants. Background Technology

[0002] Concrete, as a fundamental material for modern construction, plays an irreplaceable role in infrastructure development. However, concrete mixing plants generate significant amounts of dust during production, becoming a major source of air pollution. The dust from concrete mixing plants primarily originates from various stages, including aggregate feeding, conveying, powder storage, weighing, mixing, and unloading. Specifically, the main pollution sources include dust generated when the loader unloads material from the bucket, dust generated by the height difference when the aggregate conveyor throws aggregate, dust leakage from the powder silo due to pressure release during tanker loading, and the large amount of dust generated during the mixing unit's feeding process.

[0003] Currently, the dust removal technologies used in concrete mixing plants mainly employ the following methods: First, baghouse dust collectors, which filter dust-laden gas through filter bags, but suffer from problems such as easy clogging of filter bags, high maintenance costs, and high energy consumption; second, spray dust suppression, which suppresses dust by spraying water mist, but traditional spraying equipment is difficult to control precisely, easily resulting in excessively high material moisture content and affecting concrete quality; and third, silo top dust collectors, used for dust removal from the top of powder silos, but when the vibrator malfunctions, the filter element is easily clogged, causing compressed air to be directly discharged into the atmosphere through the safety pressure relief valve.

[0004] The aforementioned technical solutions have played a significant role in their respective application scenarios, but they generally suffer from the following problems: Each solution operates independently, lacking systematic coordination. Existing technologies often use a single device to handle multiple dust points, or although multiple dust collection devices are installed, they operate independently, making it difficult to achieve coordinated control across the entire process and multiple dust sources. There is a lack of intelligent control mechanisms based on operating condition signals. Existing systems largely rely on timed control or manual operation, failing to make intelligent adjustments based on the actual operating conditions of the dust-generating points (such as whether material is being fed, the type of material being fed, and the dust concentration).

[0005] Therefore, there is an urgent need for an environmentally friendly dust removal system and its control method for concrete mixing plants that can be systematically coordinated, linked and controlled, and intelligently adjusted. Summary of the Invention

[0006] To address the problems of independent operation and lack of coordination and intelligent control in existing dust removal technologies for concrete batching plants, this invention provides an environmentally friendly dust removal system and its control method for concrete batching plants. The specific technical details are as follows:

[0007] An environmentally friendly dust removal system for a concrete mixing plant, the concrete mixing plant including an aggregate feeding system, an aggregate conveying system, a powder storage system, a weighing system, a mixing system, and a discharging system, the environmentally friendly dust removal system comprising:

[0008] A dust suppression device is installed at at least one dust generation point in the concrete mixing plant to suppress the spread of dust at the source of dust generation.

[0009] The dust collection device, which is configured in conjunction with the dust suppression device, is used to create a negative pressure at the corresponding dust generation point, and to draw the dust-laden gas in a specific direction and transport it to the graded filtration device.

[0010] A graded filtration device includes at least two filtration units. The graded filtration device includes an air inlet and a dust outlet. The air inlet of the graded filtration device is connected to each of the dust collection devices through multiple independent dust conveying pipes.

[0011] The dust recovery and reuse device is connected to the dust discharge port of the graded filtration device and is used to transport the dust collected by filtration back to the weighing system of the concrete mixing plant.

[0012] It also includes a locally deployed control unit, which is signal-connected to the dust suppression device, the dust collection device, the graded filtration device and the ash recycling device, respectively;

[0013] The system achieves full-process coordinated operation through the control unit. The control unit receives the operating condition signals of each dust generation point in real time, controls the coordinated start-up and shutdown sequence of the corresponding dust suppression device and dust collection device according to the operating condition signals, and controls the dust cleaning process of the graded filtration device and the dust return process of the dust return and reuse device.

[0014] Furthermore, the dust suppression device includes a spray assembly and a dust monitoring device. The spray assembly is used to spray atomized droplets onto the dust generation point to suppress dust dispersion. The control unit adjusts the start / stop of the spray assembly and the spray flow rate according to the dust concentration fed back by the dust monitoring device.

[0015] Furthermore, the dust collection device includes a negative pressure generating component and an airflow guiding component. The negative pressure generating component is a variable frequency fan. The airflow guiding component includes a dust collection hood and a dust conveying pipe. The dust collection hood is located at the corresponding dust generation point. One end of the dust conveying pipe is connected to the dust collection hood, and the other end is connected to the air inlet of the graded filtration device.

[0016] Furthermore, the dust generation points are distributed in at least two subsystems of the aggregate feeding system, aggregate conveying system, powder storage system, weighing system, mixing system and unloading system of the concrete mixing plant, and the dust suppression device and the dust collection device are respectively installed at each of the dust generation points.

[0017] Furthermore, the dust generation points corresponding to the aggregate feeding system include the loader unloading port and the aggregate receiving hopper; the dust generation points corresponding to the aggregate conveying system include the belt conveyor transfer drop point and the aggregate temporary storage bin inlet; the dust generation point corresponding to the powder storage system includes the top of the powder silo; the dust generation point corresponding to the weighing system includes the powder weighing hopper; the dust generation point corresponding to the mixing system includes the feeding port of the mixing host; and the dust generation point corresponding to the unloading system includes the receiving port of the mixer truck.

[0018] Furthermore, both the powder weighing hopper and the mixing host are equipped with air replenishment devices, which are used to introduce external air to maintain air pressure balance when the dust collection device is working.

[0019] Furthermore, the graded filtration device includes a primary settling chamber and a secondary bag filter. The air inlet of the primary settling chamber is connected to each of the dust conveying pipes, the air outlet of the primary settling chamber is connected to the air inlet of the secondary bag filter, and the ash discharge ports of the primary settling chamber and the secondary bag filter are respectively connected to the ash recycling device.

[0020] The dust conveying pipeline includes a main pipeline and multiple branch pipelines. The first end of each branch pipeline is connected to the corresponding dust collection device, and the second end of each branch pipeline is connected to the main pipeline. The main pipeline is connected to the air inlet of the graded filtration device, and each branch pipeline is equipped with an independently controllable valve.

[0021] A control method for the aforementioned environmental dust removal system includes the following steps:

[0022] Step S1: The control unit monitors the operating condition signals of each dust generation point in real time;

[0023] Step S2: When any dust generation point is detected to be activated, the control unit activates the dust suppression device corresponding to the dust generation point to suppress dust emission at the dust generation source.

[0024] Step S3: After the dust suppression device is activated, the control unit turns on the dust collection device corresponding to the dust generation point, forms a negative pressure at the corresponding dust generation point, and draws the dust-laden gas in a direction and transports it to the graded filtration device.

[0025] Step S4: When the dust generation point is detected to have stopped, the control unit delays the shutdown of the dust collection device and shuts down the dust suppression device after a preset time.

[0026] Furthermore, the control unit acquires ambient humidity signals and material moisture content signals in real time; and the control unit dynamically adjusts the spray strategy of the dust suppression device based on the ambient humidity signals and the material moisture content signals: when the ambient humidity is lower than the first preset humidity threshold, the micro-mist dust suppression mode is used first; when the ambient humidity is higher than the second preset humidity threshold, it automatically switches to the negative pressure dust collection mode with the dust collection device as the main component.

[0027] Furthermore, the control unit records the running time, start-stop frequency, and differential pressure change data of each device; based on the running time, start-stop frequency, and differential pressure change data, it predicts the remaining lifespan of the filter bags in the graded filtration device; when the remaining lifespan of the filter bags is predicted to be lower than a preset lifespan threshold, the control unit automatically adjusts the dust removal strategy to reduce the running time of the graded filtration device under high load conditions and generates maintenance warning information.

[0028] The beneficial effects of this invention are as follows: By coordinating the dust suppression device and the dust collection device, this invention suppresses dust at the source of dust generation while simultaneously collecting uncaptured dust-laden gas under negative pressure, effectively solving the problem of independent operation and lack of coordination among existing dust removal devices. The control unit can receive real-time operating condition signals from each dust generation point and selectively start and stop the corresponding dust suppression and dust collection devices based on these signals, achieving an intelligent operation mode of on-demand dust removal and precise control, avoiding energy waste caused by continuous high-load operation of equipment during dust-free periods. Simultaneously, the system transports the collected dust-laden gas to a graded filtration device for two-stage filtration via a dust conveying pipeline, and the filtered dust is transported back to the weighing system via a dust return and reuse device, reducing dust emissions while achieving resource recycling. Furthermore, the control unit can dynamically adjust the spray strategy based on ambient humidity and material moisture content, and predict the remaining lifespan of the filter bags and generate maintenance warnings based on equipment operating data, further improving the system's adaptability and operational reliability, and extending the equipment's service life. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the overall system architecture of an embodiment of the present invention.

[0030] Figure 2 This is a flowchart illustrating the start-up and shutdown sequence of the dust suppression device and the dust collection device according to an embodiment of the present invention.

[0031] Figure 3 This is a flowchart illustrating the strategy switching process driven by environmental humidity in an embodiment of the present invention.

[0032] Figure 4 This is a flowchart illustrating the differential pressure monitoring and lifespan prediction process according to an embodiment of the present invention.

[0033] Figure 5This is a flowchart illustrating the dust classification filtration and ash recycling process according to an embodiment of the present invention.

[0034] Figure 6 This is a flowchart illustrating the control system signal flow and execution path in an embodiment of the present invention. Detailed Implementation

[0035] To make the objectives and technical solutions of this invention clearer, the specific embodiments of this invention will be described in detail below with reference to the accompanying drawings and examples.

[0036] like Figure 1 As shown, an environmentally friendly dust removal system for a concrete mixing plant is disclosed. The concrete mixing plant includes an aggregate feeding system, an aggregate conveying system, a powder storage system, a weighing system, a mixing system, and a discharge system. The environmentally friendly dust removal system includes: a dust suppression device installed at at least one dust generation point in the concrete mixing plant to suppress dust emission at the dust generation source; a dust collection device installed in conjunction with the dust suppression device to create negative pressure at the corresponding dust generation point, directionally drawing in and conveying the dust-laden gas to a graded filtration device; and a graded filtration device including at least two filtration units, comprising an air inlet and an ash outlet, wherein the air inlet of the graded filtration device passes through multiple... An independent dust conveying pipeline is connected to each of the dust collection devices; the ash return and reuse device is connected to the ash discharge port of the graded filtration device, and is used to transport the filtered and collected dust back to the weighing system of the concrete mixing plant; it also includes a locally deployed control unit, which is connected to the dust suppression device, the dust collection device, the graded filtration device and the ash return and reuse device respectively; the system achieves full-process coordinated operation through the control unit: the control unit receives the operating condition signals of each dust generation point in real time, controls the coordinated start and stop sequence of the corresponding dust suppression device and dust collection device according to the operating condition signals, and controls the ash cleaning process of the graded filtration device and the ash return process of the ash return and reuse device.

[0037] like Figure 6 As shown, preferably, the control unit adopts a PLC programmable logic controller; the operating signals include equipment operating status switch signals, material level analog signals, and dust concentration 4-20mA signals (it should be noted that the 4-20mA signal is an internationally recognized analog signal transmission standard, which uses the magnitude of the current to represent the dust concentration value); the control unit is connected to each device via an RS485 wired bus (RS485 is an industrial communication standard suitable for stable data exchange between devices in long-distance, multi-node, and electromagnetic interference environments), and also has a 4G IoT module to support wireless remote communication, which can be remotely monitored through a mobile APP or computer web interface.

[0038] Preferably, the dust suppression device includes a spray assembly and a dust monitoring device. The spray assembly is used to spray atomized droplets onto the dust generation point to suppress dust dispersion. The spray assembly mainly includes a dry fog dust suppression host, ultrasonic dry fog nozzles, an air compressor, an air tank, and a water supply system. The spray assembly contains eight ultrasonic dry fog nozzles arranged in a ring above the dust generation point. The droplet size range is 1μm-10μm, and the spray coverage angle is 120°. 0.5% by mass of dust suppressant is added to the spray water. The dust suppressant is a composite dust suppressant that reduces the surface tension of the droplets and forms a protective film on the dust surface to prevent dust from flying away after drying. The control unit, based on the dust concentration feedback from the dust monitoring device (which uses a laser particulate sensor installed inside the dust collection hood), uses a PID control algorithm to control the start and stop of the spray assembly and adjust the spray flow rate in real time according to the dust concentration. The actuator is an electric regulating valve.

[0039] Preferably, the dust collection device includes a negative pressure generating component and an airflow guiding component. The negative pressure generating component is a variable frequency fan, and the airflow guiding component includes a dust collection hood and a dust conveying pipe. The dust collection hood is located at the corresponding dust generation point. One end of the dust conveying pipe is connected to the dust collection hood, and the other end is connected to the air inlet of the graded filtration device. The dust collection hood is an umbrella-shaped hood. The variable frequency fan is selected according to the maximum dust generation, with an air volume range of 5000-15000 m³ / h and a negative pressure value range of 2000-4000 Pa. The dust conveying pipe is made of Q235 carbon steel, and the pipe diameter is calculated and determined based on the air volume of each branch at an economical wind speed of 12-15 m / s.

[0040] Preferably, the dust generation points are distributed in at least two subsystems of the aggregate feeding system, aggregate conveying system, powder storage system, weighing system, mixing system and unloading system of the concrete mixing plant, and the dust suppression device and the dust collection device are respectively installed at each of the dust generation points.

[0041] Preferably, the dust generation points corresponding to the aggregate feeding system include the loader unloading port and the aggregate receiving hopper; the dust generation points corresponding to the aggregate conveying system include the belt conveyor transfer drop point and the aggregate temporary storage bin inlet; the dust generation point corresponding to the powder storage system includes the top of the powder silo; the dust generation point corresponding to the weighing system includes the powder weighing hopper; the dust generation point corresponding to the mixing system includes the feeding port of the mixing host; and the dust generation point corresponding to the unloading system includes the receiving port of the mixer truck. The powder weighing hopper and the mixing host are relatively enclosed spaces. When the dust collection device (exhaust fan) is working, the air inside these two enclosed spaces can only be extracted in one direction, thereby generating negative pressure. Negative pressure directly affects the accuracy of powder weighing, leading to deviations in concrete mix proportions and impacting finished product quality. Therefore, both the powder weighing hopper and the mixing host are equipped with air replenishment devices. It's important to note that the application of air replenishment devices in the environmental dust removal systems of concrete mixing plants is a conventional and mature technology. The industry has extensive experience and standardized implementation plans, including clear engineering practice guidelines for the opening size of the air replenishment holes (φ250mm, φ200mm, etc.), the selection of filter bag material (permeable, easy-to-clean dust removal cloth), and the installation location. Therefore, the specific design details and installation process of the air replenishment device will not be elaborated upon here.

[0042] like Figure 5As shown, preferably, the graded filtration device includes a primary settling chamber and a secondary bag filter. The air inlet of the primary settling chamber is connected to each of the dust conveying pipes, the air outlet of the primary settling chamber is connected to the air inlet of the secondary bag filter, and the ash discharge ports of the primary settling chamber and the secondary bag filter are respectively connected to the ash recycling device. The primary settling chamber is equipped with a buffer cap and a baffle plate to extend the residence time of dust-laden gas; the secondary bag filter uses fiberglass membrane filter media, with 120 filter bags and a filtration area of ​​approximately 200 m² calculated based on a filtration velocity of 0.8-1.2 m / min. The pulse jet cleaning system has a jet pressure of 0.5-0.6 MPa, a jet cycle of 60-120 s, a pulse width of 0.1-0.2 s, and a gas storage tank volume of 2 m³. (It should be noted that the pulse jet cleaning system itself is integrated into the secondary bag filter in this embodiment as a basic component of the secondary bag filter, and it is a relatively mature industrial application in the existing technology, so no further explanation is given.) The dust recovery and reuse device employs a combination of a pneumatic butterfly valve and a dust recovery pipeline. The pneumatic butterfly valve is installed in the dust recovery pipeline, which is connected to a powder weighing hopper (part of the weighing system, where dust is collected for immediate proportioning and use, rather than being returned to the storage silo). The pneumatic butterfly valve uses compressed air as a power source and is opened and closed by a pneumatic actuator that drives the butterfly plate to rotate, controlling the flow of the dust recovery pipeline. When dust recovery is needed, the butterfly valve opens, allowing the collected dust to flow smoothly through the pipeline into the powder weighing hopper. When dust recovery is not needed or maintenance is required, the butterfly valve closes, blocking the flow of the medium. In the dust recovery system, the pneumatic butterfly valve also prevents the reverse flow of gas and dust, avoiding the positive or negative pressure in the weighing hopper from affecting the pressure balance inside the dust collector. Furthermore, the dust collector includes a dust hopper, and a pneumatic conveying device (such as a material sealing pump, screw pump, or dual-compartment pump; in this embodiment, a material sealing pump is used) is installed below the dust hopper. The dust is fluidized by compressed air and then conveyed to the weighing hopper via a return dust pipe. An airlock is installed at the connection between the return dust pipe and the weighing hopper to prevent dust leakage.

[0043] Preferably, the dust conveying pipeline includes a main pipeline and multiple branch pipelines. The first end of each branch pipeline is connected to the corresponding dust collection device, and the second end of each branch pipeline is connected to the main pipeline. The main pipeline is connected to the air inlet of the graded filtration device. Each branch pipeline is equipped with an independently controllable valve (electric butterfly valve). The diameters of the main pipeline and branch pipelines are determined by hydraulic calculation based on the airflow requirements at each dust generation point (in the field of ventilation and dust removal engineering, professionals usually refer to calculations such as pipeline resistance and diameter determination as "hydraulic calculation" or "ventilation duct hydraulic calculation," which is a term borrowed from water conservancy engineering. This is to avoid misunderstanding). Electric butterfly valves are used. The branch pipelines are connected to the main pipeline at a 45° angle to reduce resistance. A dust removal port is installed every 8m on the main pipeline.

[0044] A control method applied to the aforementioned environmental dust removal system, characterized by comprising the following steps:

[0045] Step S1: The control unit monitors the operating condition signals of each dust generation point in real time. The operating condition signals include the equipment start / stop status switch signal, the material level analog signal, and the dust concentration 4-20mA analog signal; the sampling frequency is once per second; the signal transmission adopts a combination of RS485 digital communication and 4-20mA analog signal.

[0046] like Figure 2 As shown, in step S2: when any dust generation point is detected to be activated, the control unit activates the dust suppression device corresponding to that dust generation point to suppress dust emission at the dust generation source. The basis for detecting "activation" is the receipt of a switch signal indicating that the device has been activated. When activating the dust suppression device, the initial spray flow rate is set to 50% of the rated flow rate, and the spray pressure is 0.6 MPa. The response time requirement is ≤0.5 seconds.

[0047] like Figure 2 As shown, in step S3: after the dust suppression device is activated, the control unit turns on the dust collection device corresponding to the dust generation point, forming a negative pressure at the corresponding dust generation point, and directionally sucking and transporting the dust-laden gas to the graded filtration device. The dust collection device is turned on after a 1-second delay after the dust suppression device is activated; when the dust collection device is turned on, the initial frequency of the variable frequency fan is set to 25Hz, and the initial air volume is 50% of the rated air volume; the negative pressure value inside the dust collection hood is controlled within the range of 200-500Pa.

[0048] Step S4: When the dust generation point is detected to have stopped, the control unit delays the shutdown of the dust collection device and shuts down the dust suppression device after a preset time. The basis for detecting "stop" is receiving a switch signal indicating that the equipment has stopped, and the dust concentration drops below 10mg / m³ for 5 seconds. The delay time for shutting down the dust collection device is 5 seconds. The preset time for shutting down the dust suppression device is 20 seconds. The different delay times are set to ensure that the residual dust is completely collected and to prevent the small amount of dust remaining after the equipment stops from escaping.

[0049] like Figure 3As shown, preferably, the control unit acquires the ambient humidity signal and the material moisture content signal in real time; and the control unit dynamically adjusts the spray strategy of the dust suppression device according to the ambient humidity signal and the material moisture content signal: when the ambient humidity is lower than the first preset humidity threshold, the micro-mist dust suppression mode is preferentially adopted; when the ambient humidity is higher than the second preset humidity threshold, it automatically switches to the negative pressure dust collection mode with the dust collection device as the main component. The ambient humidity signal is acquired through a temperature and humidity sensor, and the material moisture content signal is acquired through an online moisture content detector; the first preset humidity threshold is 45%, and the second preset humidity threshold is 75%; in the micro-mist dust suppression mode, the droplet size is controlled at 1-5μm, and the spray volume is reduced by 30%; in the negative pressure dust collection mode, the frequency of the variable frequency fan is increased by 15%, and the negative pressure value of the dust collection hood is increased to 500-800Pa.

[0050] like Figure 4 As shown, preferably, the control unit records the running time, number of start-stop cycles, and differential pressure change data of each device; based on the running time, number of start-stop cycles, and differential pressure change data, it predicts the remaining lifespan of the filter bags in the graded filtration device; when the remaining lifespan of the filter bags is predicted to be lower than a preset lifespan threshold, the control unit automatically adjusts the dust removal strategy to reduce the running time of the graded filtration device under high load conditions and generates maintenance warning information.

[0051] like Figure 4 As shown, runtime, start / stop count, and differential pressure change data are stored in the local memory of the control unit and simultaneously uploaded to the cloud server; the remaining lifespan of the filter bags is predicted using a linear regression model based on the differential pressure change trend; the preset lifespan threshold is when the remaining lifespan is less than 72 hours or the differential pressure exceeds 1200 Pa; the specific measures for automatically adjusting the dust removal strategy are: reducing the total system processing air volume by 10% and improving gravity settling efficiency by extending the residence time of dust-laden gas in the primary settling chamber, which is equivalent to transferring the filtration load of the secondary bag filter to the primary settling chamber, thereby slowing down the filter bag clogging speed.

[0052] It should be noted that the differential pressure measurement method in this embodiment is the differential pressure method. Specifically, to monitor the clogging status of the filter bags in the secondary bag filter, a differential pressure transmitter is installed between the inlet and outlet of the secondary bag filter to monitor the pressure difference across the filtration device in real time. The differential pressure transmitter converts the differential pressure signal into an electrical signal and transmits it to the control unit. However, since the secondary bag filter in this embodiment uses periodic pulse dust removal, the differential pressure data here is not for triggering the pulse, but for monitoring the filtration life of the secondary bag filter. The specific logic is detailed later.

[0053] The following section details how the system works collaboratively, using a complete workflow as an example. Figure 1-6 .

[0054] I. Intelligent Monitoring and Signal Acquisition

[0055] The control unit (PLC) connects to a 4G IoT module via an RS485 bus to monitor the operating conditions of each dust-generating point in real time, with a sampling frequency of once per second. The monitored signals include:

[0056] Equipment start / stop status switch signals: to determine whether each production equipment is in operation;

[0057] Analog level signal: Monitors changes in material level in equipment such as powder silos and weighing hoppers;

[0058] Dust concentration 4-20mA analog signal: Dust concentration data is fed back in real time through a laser particulate sensor installed inside the dust collection hood.

[0059] Meanwhile, the control unit acquires ambient humidity signals through temperature and humidity sensors and material moisture content signals through an online moisture content detector, providing a basis for subsequent dynamic adjustment of the spraying strategy.

[0060] II. Activate the dust suppression device first.

[0061] When the control unit detects the activation of any dust generation point (based on the receipt of a switch signal indicating device activation), it immediately activates the dust suppression device corresponding to that dust generation point. The dust suppression device includes a spray assembly and a dust monitoring device. The spray assembly contains eight ultrasonic dry fog nozzles arranged in a ring above the dust generation point, with droplet sizes ranging from 1μm to 10μm and a spray coverage angle of 120°.

[0062] When activated:

[0063] The initial spray flow rate is set to 50% of the rated flow rate;

[0064] The spray pressure is 0.6 MPa;

[0065] Response time requirement: ≤0.5 seconds;

[0066] The spray water has been mixed with 0.5% by mass of a compound dust suppressant.

[0067] Step S3 (Dust collection device starts after delay):

[0068] After the dust suppression device is activated, the control unit delays for 1 second before activating the dust collection device corresponding to the dust generation point. The dust collection device consists of a variable frequency fan (airflow range 5000-15000 m³ / h, negative pressure range 2000-4000 Pa) and an umbrella-shaped dust collection hood. Upon activation:

[0069] The initial frequency of the variable frequency fan is set to 25Hz;

[0070] The initial air volume is 50% of the rated air volume;

[0071] The negative pressure value inside the dust collection hood is controlled within the range of 200-500 Pa.

[0072] Logic Explanation: The dust suppression device activates first, using spray to initially suppress dust at its source. One second later, the dust collection device activates, creating negative pressure at the dust generation point to directionally draw in any remaining dust-laden gas. Source suppression and negative pressure suction are activated sequentially, not simultaneously, to ensure that dust is captured by the spray before it can dissipate.

[0073] III. Dynamic Spray Adjustment Mechanism

[0074] During continuous operation of the dust suppression device, the control unit, based on dust concentration data fed back by the dust monitoring device (laser particulate sensor), employs a PID control algorithm (a commonly used automatic control algorithm in industry; the specific calculation principle is not elaborated here) to control the start and stop of the spray components and adjust the spray flow rate in real time. The actuator is an electric regulating valve. When the dust concentration increases, the spray flow rate automatically increases; when the dust concentration decreases, the spray flow rate automatically decreases, achieving precise, on-demand spraying.

[0075] IV. Strategy Switching Driven by Ambient Humidity

[0076] The control unit acquires ambient humidity and material moisture content signals in real time, and dynamically adjusts the dust removal strategy according to the following logic:

[0077] When the ambient humidity is below 45%, the micro-mist dust suppression mode should be used first. The droplet size is controlled at 1-5μm (fineer), and the spray volume is reduced by 30%. This uses more precise micro-mist particles to efficiently adsorb dust and avoids excessive humidification that could increase the moisture content of the material.

[0078] When the ambient humidity is higher than 75%, the system automatically switches to a negative pressure dust collection mode, primarily using the dust collection device. The frequency of the variable frequency fan is increased by 15%, and the negative pressure value of the dust collection hood is increased to 500-800Pa, enhancing the negative pressure suction capacity to compensate for the decrease in spray efficiency in humid environments.

[0079] V. Dust Conveying and Classified Filtration

[0080] The dust collection device draws in dust-laden gas in a specific direction, then transports it through a dust conveying pipeline to a graded filtration device. The dust conveying pipeline consists of a main pipeline and multiple branch pipelines.

[0081] The first end of each branch pipe is connected to the corresponding dust collection device, and an independently controllable electric butterfly valve is installed in the branch pipe.

[0082] The second end of each branch pipe is connected to the main pipe at a 45° angle to reduce resistance;

[0083] The main pipeline is connected to the air inlet of the graded filtration device, and a dust removal port is installed every 8m on the main pipeline.

[0084] The tiered filtration system consists of a primary settling chamber and a secondary bag filter.

[0085] Primary settling chamber: It is equipped with a buffer cap and a flow guide baffle to extend the residence time of dust-laden gas, so that large dust particles settle naturally under the action of gravity.

[0086] Two-stage bag filter: It uses fiberglass membrane filter media, with 120 filter bags and a filtration area of ​​about 200m² (calculated based on a filtration velocity of 0.8-1.2m / min) to perform fine filtration of particulate dust.

[0087] After pretreatment in the primary settling chamber (where large dust particles settle, and the large dust particles collected in the primary settling chamber are connected to the ash return and reuse device through the bottom ash discharge port, and transported back to the weighing system together with the fine dust collected in the secondary bag filter), the dust-laden gas enters the secondary bag filter from the outlet for further purification, and finally meets the emission standards.

[0088] VI. Timed pulse backflushing for dust removal

[0089] The two-stage bag filter has a built-in pulse jet cleaning system and adopts a fixed-cycle timed control mode.

[0090] The blowing cycle is 60-120 seconds (depending on the parameters set by the host computer).

[0091] The blowing pressure is 0.5-0.6 MPa;

[0092] The pulse width is 0.1-0.2 seconds;

[0093] The gas storage tank has a volume of 2m³.

[0094] When the timer reaches the set cycle, the control unit sends a signal to the corresponding pulse valve, driving compressed air to be injected into the inside of the filter bag in a pulsed manner, causing the dust adhering to the outer surface of the filter bag to fall into the ash hopper. The system cleans each group of filter bags in turn in sequence to ensure uninterrupted dust removal. The cleaning cycle is fixed and does not rely on differential pressure signal triggering, but the system monitors the differential pressure change trend in real time. When it is predicted that the differential pressure will exceed the reasonable range, the control unit determines that the filter bag is nearing the end of its service life. At this time, it no longer attempts to reduce the differential pressure by adjusting the cleaning process, but instead reduces the load to extend the final service life of the filter bag and issues a warning.

[0095] VII. Dust Collection and Ash Recycling

[0096] The dust removed by the pulse jet cleaning falls into the ash hopper of the secondary bag filter. When the ash level in the hopper reaches the high limit (determined by an analog level signal), the control unit initiates the ash recycling program.

[0097] Pneumatic conveying: The material sealing pump below the dust collector hopper starts, using compressed air to fluidize the dust and make it flowable;

[0098] Ash return pipeline conveying: The fluidized dust is conveyed to the powder weighing hopper through the ash return pipeline;

[0099] Pneumatic butterfly valve control: At the connection between the ash return branch and the weighing hopper, the pneumatic butterfly valve opens upon receiving a command from the control unit. Powered by compressed air, it rotates the butterfly plate via a pneumatic actuator to control the opening and closing of the ash return pipeline. This valve also prevents the reverse flow of gas and dust, avoiding any positive or negative pressure within the weighing hopper from affecting the pressure balance within the dust collector.

[0100] Airlock protection: An airlock is installed at the final inlet of the weighing hopper to prevent dust from leaking into the environment during the dust return process.

[0101] 8. Coordinated shutdown of dust suppression and dust collection devices

[0102] When the control unit detects that the dust generation point has stopped (based on receiving a switch signal indicating that the equipment has stopped, and the dust concentration has dropped below 10mg / m³ for 5 seconds), the following delayed shutdown logic is executed:

[0103] First, turn off the dust collection device: The dust collection device has a 5-second delay before shutting off to ensure that residual dust is completely collected;

[0104] Then shut down the dust suppression device: After the dust collection device is shut down, the dust suppression device will be shut down for another 20 seconds to prevent any remaining dust from escaping after the equipment stops.

[0105] Logical explanation: Dust collection is turned off first, followed by dust suppression, with a time difference between the two actions. The 5-second delay in the dust collection device is to ensure all residual dust-laden gas in the pipeline is removed; the additional 20-second delay in the dust suppression device is to continue spraying to suppress dust during the time window when a small amount of dust may still escape after the equipment stops.

[0106] IX. Intelligent Maintenance and Early Warning

[0107] The control unit continuously records the operating time, start-stop frequency, and differential pressure changes of each device. This data is stored locally and simultaneously uploaded to a cloud server. Based on this data, the control unit uses a linear regression model based on differential pressure change trends to predict the remaining lifespan of the filter bags in the secondary baghouse dust collector.

[0108] When the remaining lifespan of the filter bag is predicted to be less than 72 hours, or the pressure difference exceeds 1200 Pa, the control unit automatically performs the following adjustments:

[0109] The filtration load of the secondary bag filter is transferred to the primary settling chamber (by appropriately reducing the total air volume of the system, extending the residence time of the dust-laden gas in the primary settling chamber, improving the gravity settling efficiency, and thus reducing the amount of dust entering the secondary bag filter).

[0110] Reduce the air volume of the dust collector by 10% to slow down the clogging of the filter bags (the control unit can reduce the air volume of the secondary bag filter, allowing more dust-laden gas to stay in the primary settling chamber for a longer time, and utilize gravity settling to allow more dust to settle down).

[0111] Simultaneously, maintenance warning information is generated and pushed to the manager's mobile APP or computer web interface to remind them to check or replace the filter bags.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An environmentally friendly dust removal system for a concrete mixing plant, the concrete mixing plant comprising an aggregate feeding system, an aggregate conveying system, a powder storage system, a weighing system, a mixing system, and a discharging system, characterized in that, The environmental protection dust removal system includes: A dust suppression device is installed at at least one dust generation point in the concrete mixing plant to suppress the spread of dust at the source of dust generation. The dust collection device, which is configured in conjunction with the dust suppression device, is used to create a negative pressure at the corresponding dust generation point, and to draw the dust-laden gas in a specific direction and transport it to the graded filtration device. A graded filtration device includes at least two filtration units. The graded filtration device includes an air inlet and a dust outlet. The air inlet of the graded filtration device is connected to each of the dust collection devices through multiple independent dust conveying pipes. The dust recovery and reuse device is connected to the dust discharge port of the graded filtration device and is used to transport the dust collected by filtration back to the weighing system of the concrete mixing plant. It also includes a locally deployed control unit, which is signal-connected to the dust suppression device, the dust collection device, the graded filtration device and the ash recycling device, respectively; The system achieves full-process coordinated operation through the control unit. The control unit receives the operating condition signals of each dust generation point in real time, controls the coordinated start-up and shutdown sequence of the corresponding dust suppression device and dust collection device according to the operating condition signals, and controls the dust cleaning process of the graded filtration device and the dust return process of the dust return and reuse device.

2. The environmental dust removal system according to claim 1, characterized in that: The dust suppression device includes a spray assembly and a dust monitoring device. The spray assembly is used to spray atomized droplets onto the dust generation point to suppress dust dispersion. The control unit adjusts the start and stop of the spray assembly and the spray flow rate according to the dust concentration fed back by the dust monitoring device.

3. The environmental dust removal system according to claim 1, characterized in that: The dust collection device includes a negative pressure generating component and an airflow guiding component. The negative pressure generating component is a variable frequency fan. The airflow guiding component includes a dust collection hood and a dust conveying pipe. The dust collection hood is set at the corresponding dust generation point. One end of the dust conveying pipe is connected to the dust collection hood, and the other end is connected to the air inlet of the graded filtration device.

4. The environmental dust removal system according to claim 1, characterized in that: The dust generation points are distributed in at least two subsystems of the aggregate feeding system, aggregate conveying system, powder storage system, weighing system, mixing system and unloading system of the concrete mixing plant, and the dust suppression device and the dust collection device are respectively installed at each of the dust generation points.

5. The environmentally friendly dust removal system according to claim 4, characterized in that: The dust generation points corresponding to the aggregate feeding system include the loader unloading port and the aggregate receiving hopper; the dust generation points corresponding to the aggregate conveying system include the belt conveyor transfer drop point and the aggregate temporary storage bin inlet; the dust generation point corresponding to the powder storage system includes the top of the powder silo; the dust generation point corresponding to the weighing system includes the powder weighing hopper; the dust generation point corresponding to the mixing system includes the feeding port of the mixing host; and the dust generation point corresponding to the unloading system includes the receiving port of the mixer truck.

6. The environmental dust removal system according to claim 5, characterized in that: Both the powder weighing hopper and the mixing host are equipped with air replenishment devices, which are used to introduce external air to maintain air pressure balance when the dust collection device is working.

7. The environmental dust removal system according to claim 1, characterized in that: The graded filtration device includes a primary settling chamber and a secondary bag filter. The air inlet of the primary settling chamber is connected to each of the dust conveying pipes, the air outlet of the primary settling chamber is connected to the air inlet of the secondary bag filter, and the ash discharge ports of the primary settling chamber and the secondary bag filter are respectively connected to the ash recycling device. The dust conveying pipeline includes a main pipeline and multiple branch pipelines. The first end of each branch pipeline is connected to the corresponding dust collection device, and the second end of each branch pipeline is connected to the main pipeline. The main pipeline is connected to the air inlet of the graded filtration device, and each branch pipeline is equipped with an independently controllable valve.

8. A dust control method for a concrete mixing plant, applied to the environmental dust removal system described in claim 1, characterized in that, Includes the following steps: Step S1: The control unit monitors the operating condition signals of each dust generation point in real time; Step S2: When any dust generation point is detected to be activated, the control unit activates the dust suppression device corresponding to the dust generation point to suppress dust emission at the dust generation source. Step S3: After the dust suppression device is activated, the control unit turns on the dust collection device corresponding to the dust generation point, forms a negative pressure at the corresponding dust generation point, and draws the dust-laden gas in a direction and transports it to the graded filtration device. Step S4: When the dust generation point is detected to have stopped, the control unit delays and shuts down the dust collection device, and shuts down the dust suppression device after a preset time.

9. The dust control method according to claim 8, characterized in that, The control unit acquires ambient humidity signals and material moisture content signals in real time; and the control unit dynamically adjusts the spray strategy of the dust suppression device according to the ambient humidity signals and the material moisture content signals: when the ambient humidity is lower than the first preset humidity threshold, the micro-mist dust suppression mode is used first; when the ambient humidity is higher than the second preset humidity threshold, it automatically switches to the negative pressure dust collection mode with the dust collection device as the main component.

10. The dust control method according to claim 9, characterized in that, The control unit records the running time, number of start-stop cycles, and differential pressure change data of each device; based on the running time, number of start-stop cycles, and differential pressure change data, it predicts the remaining lifespan of the filter bags in the graded filtration device; when the remaining lifespan of the filter bags is predicted to be lower than a preset lifespan threshold, the control unit automatically adjusts the dust removal strategy to reduce the running time of the graded filtration device under high load conditions and generates maintenance warning information.

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