Desulfurizing agent efficient internal circulation system and method based on low-pressure conveying and precise grading

Abstract

The invention discloses a desulfurizing agent efficient internal circulation system and method based on low-pressure conveying and precise grading, and relates to the technical field of industrial flue gas purification. According to the desulfurizing agent efficient internal circulation system based on low-pressure conveying and precision grading, continuous conveying and two-stage grading integrated treatment of desulfurized fly ash are achieved, the fly ash conveying system stably conveys the desulfurized fly ash to the two-stage precision sorting unit at the preset pressure, the first-stage pre-separator conducts primary coarse separation on the desulfurized fly ash, most of coarse particle desulfurization by-products are removed, and the desulfurized fly ash is subjected to secondary coarse separation through the second-stage pre-separator; the subsequent grading load is reduced; the secondary dynamic airflow classifier precisely classifies airflow containing fine powder, high-activity desulfurizing agent fine powder is precisely separated out and fed into the desulfurizing agent bin, coarse particles and medium-particle-size powder are fed into the desulfurized fly ash bin, and the integrated structure avoids flow redundancy caused by separation of a conveying and sorting system in a traditional scheme. The compactness and the separation effect of the system are improved, and efficient internal recycling of the desulfurizing agent is realized.

Description

Technical Field

[0001] This invention relates to the field of industrial flue gas purification technology, specifically to a high-efficiency internal circulation system and method for desulfurizing agents based on low-pressure transportation and precise classification. Background Technology

[0002] Calcium-based dry desulfurization technology is a common process for treating low-temperature flue gas in industries such as steel, power, and building materials. Its principle involves spraying highly active calcium hydroxide powder into the flue to react with sulfur dioxide, generating desulfurization ash mainly composed of calcium sulfite, calcium sulfate, and unreacted calcium hydroxide. To improve the utilization rate of the desulfurizing agent, the recycling and reuse of unreacted calcium hydroxide in the desulfurization ash has become an industry consensus. Currently, desulfurization ash recycling mainly adopts two methods: one is to transport all the desulfurization ash collected by the bag filter to the ash silo for temporary storage via a traditional pneumatic conveying system, and then separate it through an external independent sorting system; the other is to install a simple cyclone separator at the flue outlet or before the dust collector for coarse classification and recycling of the desulfurization ash.

[0003] In existing technologies, traditional pneumatic conveying systems typically employ high-pressure (greater than 0.4 MPa) intermittent conveying to push all desulfurization ash into the ash silo, where centrifugal or vortex separators are then used for subsequent separation. While this approach achieves centralized processing of desulfurization ash, high-pressure conveying consumes a lot of energy, causes severe wear on pipes and valves, and the conveying and sorting systems are relatively independent, resulting in a long process and a large footprint. While using a simple cyclone separator for online sorting eliminates some conveying steps, the cyclone separator itself has limited grading accuracy, making it difficult to effectively distinguish between unreacted calcium hydroxide and desulfurization byproducts of similar particle sizes. This leads to high impurity content and low activity in the recovered material, making it unsuitable for direct reuse in the desulfurization system. Furthermore, fine powder tends to accumulate in the system, causing blockages in subsequent equipment and affecting the long-term stable operation of the system. Therefore, achieving high-precision separation and efficient internal circulation of highly active components in desulfurization ash with low energy consumption and low wear has become a pressing technical problem in this field. To address the shortcomings of existing technologies, this invention provides a high-efficiency internal circulation system and method for desulfurizing agents based on low-pressure conveying and precise grading to solve the aforementioned problems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-efficiency internal circulation system and method for desulfurizing agents based on low-pressure conveying and precision classification. By employing a structural design combining an ash conveying system with a two-stage precision sorting unit consisting of a primary pre-separator and a secondary dynamic airflow classifier connected in series, continuous conveying and integrated two-stage classification of desulfurized ash are achieved. The ash conveying system smoothly conveys the desulfurized ash to the two-stage precision sorting unit at a preset pressure. The primary pre-separator performs initial coarse separation of the desulfurized ash, removing most of the coarse particles of desulfurization byproducts and reducing the load on subsequent classification. The secondary dynamic airflow classifier precisely classifies the airflow containing fine powder, accurately separating the highly active desulfurizing agent fine powder and sending it to the desulfurizing agent silo. Coarse and medium-sized particles are sent to the desulfurized ash silo. This integrated structure avoids the process redundancy caused by the separation of the conveying and sorting systems in traditional solutions, improves system compactness and separation effect, and achieves efficient internal circulation of the desulfurizing agent.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-efficiency internal circulation system for desulfurizing agents based on low-pressure transportation and precise grading, comprising: The ash conveying system is used to continuously convey desulfurization ash at a preset pressure; The two-stage precision sorting unit has its inlet connected to the outlet of the ash conveying system and is used to classify the desulfurization ash in two stages, including a first-stage pre-separator and a second-stage dynamic airflow classifier arranged in series. The desulfurizing agent silo is connected to the fine powder outlet of the secondary dynamic airflow classifier and is used to receive and store the sorted high-activity desulfurizing agent fine powder. The desulfurization ash silo is connected to the coarse material outlet of the primary pre-separator and the coarse material outlet of the secondary dynamic airflow classifier, and is used to receive and store the sorted coarse desulfurization ash particles.

[0006] Preferably, the ash conveying system is a low-pressure continuous conveying system with an operating pressure of 0.08 MPa to 0.15 MPa. It includes a pneumatic conveying pump and a conveying pipeline connected to the outlet of the pneumatic conveying pump. The ash conveying system is used to steadily convey desulfurization ash in a dense phase form.

[0007] Preferably, the two-stage dynamic airflow classifier includes: A grading shell, which is provided with the feed inlet, the fine powder outlet and the coarse material outlet; The grading wheel is rotatably mounted inside the grading housing; A variable frequency motor is connected to the classifying wheel drive and is used to change the cutting particle size of the classifying wheel by adjusting the rotation speed, thereby achieving precise separation of powders of different particle sizes.

[0008] Preferably, the system further includes a push-suction composite power system consisting of a front-end push unit and a rear-end suction unit; The front-end pushing unit includes the ash conveying system, which is used to push the desulfurization ash to the two-stage precision sorting unit; The downstream suction unit includes a dust collector fan connected to the desulfurizing agent silo, which is used to create negative pressure in the secondary dynamic airflow classifier and guide the airflow containing fine powder through.

[0009] Preferably, the downstream suction unit further includes a local suction force generated by the high-speed rotating classifying wheel inside the secondary dynamic airflow classifier. The local suction force works in conjunction with the system negative pressure generated by the dust collector fan to draw fine powder that meets the particle size requirements into the classifying wheel and discharge it from the fine powder outlet.

[0010] Preferably, the primary pre-separator is a cyclone separator, and the feed inlet of the primary pre-separator is tangentially connected to the outlet of the ash conveying system, which is used to achieve primary separation of coarse desulfurization ash particles and dust-laden airflow under centrifugal force.

[0011] Preferably, the feed inlet of the secondary dynamic airflow classifier is connected to the air outlet of the primary pre-separator through an air guide pipe, and the direction of the air guide pipe is configured to allow the airflow to enter the classification zone where the classifier wheel is located from bottom to top.

[0012] Preferably, the coarse material outlet of the primary pre-separator and / or the coarse material outlet of the secondary dynamic air classifier are connected to a mechanical conveying device via pipelines, and the outlet of the mechanical conveying device is connected to the desulfurization ash silo.

[0013] Preferably, the speed adjustment range of the variable frequency motor is 800-1800 r / min, which is used to sort out highly active calcium hydroxide fine powder with different particle size thresholds.

[0014] This invention also discloses a method for the high-efficiency internal circulation system of desulfurizing agent based on low-pressure transportation and precise classification, the method comprising the following steps: Step S1, Low-pressure conveying: The desulfurization ash from the desulfurization reactor is continuously conveyed to the two-stage precision sorting unit in a low-pressure, dense-phase form through an ash conveying system with an operating pressure of less than 0.2 MPa. Step S2, primary coarse separation: Desulfurization ash enters the primary pre-separator, where it undergoes primary separation under centrifugal force. The separated coarse desulfurization ash particles are discharged into the desulfurization ash silo, while the airflow containing unreacted desulfurizing agent fine powder enters the next stage. Step S3, Secondary Fine Separation: The dust-laden airflow enters the secondary dynamic airflow classifier. By adjusting the rotation speed of the classifying wheel, a controllable centrifugal force field is generated, causing the highly active ultrafine desulfurizing agent powder, whose airflow drag force is greater than the centrifugal force, to be drawn into the classifying wheel and discharged from the fine powder outlet. Step S4, recycling: The high-activity desulfurizing agent fine powder discharged from the fine powder outlet is sent to the desulfurizing agent silo for reuse in the desulfurization reactor, while the medium-sized powder discharged from the medium and coarse material outlet is sent to the desulfurization ash silo.

[0015] The technical effects and advantages of this invention are as follows: 1. This high-efficiency internal circulation system for desulfurizing agents based on low-pressure conveying and precision classification adopts a structural design combining an ash conveying system with a two-stage precision sorting unit consisting of a primary pre-separator and a secondary dynamic airflow classifier connected in series. This achieves continuous conveying and integrated two-stage classification of desulfurized ash. The ash conveying system smoothly conveys the desulfurized ash to the two-stage precision sorting unit at a preset pressure. The primary pre-separator performs initial coarse separation of the desulfurized ash, removing most of the coarse particles of desulfurization byproducts and reducing the load on subsequent classification. The secondary dynamic airflow classifier performs precision classification of the airflow containing fine powder, accurately separating the highly active desulfurizing agent fine powder and sending it to the desulfurizing agent silo. Coarse particles and medium-sized particles are sent to the desulfurized ash silo. This integrated structure avoids the process redundancy caused by the separation of the conveying and sorting systems in traditional solutions, improves the system compactness and separation effect, and achieves efficient internal circulation of the desulfurizing agent.

[0016] 2. This high-efficiency internal circulation system for desulfurizing agents based on low-pressure conveying and precision grading designs the ash conveying system as a low-pressure continuous conveying system with a working pressure of 0.08MPa to 0.15MPa and adopts a dense-phase conveying structure, which significantly reduces the gas-solid ratio and flow rate during the conveying process, reduces wear on pipelines and valves, and extends the service life of the equipment. At the same time, the low-pressure operation reduces energy consumption compared to the traditional high-pressure silo pump conveying system, and controls operating costs, demonstrating the advantages of energy saving and consumption reduction.

[0017] 3. This high-efficiency internal circulation system for desulfurizing agents based on low-pressure conveying and precision classification constructs a push-suction composite power system consisting of a front-end pushing unit and a rear-end suction unit. Specifically, the front-end ash conveying system pushes the desulfurized ash to the two-stage precision sorting unit, while the dust collector fan connected to the rear-end desulfurizing agent silo creates negative pressure within the two-stage dynamic airflow classifier, guiding the airflow containing fine powder to pass smoothly. Combined with the local suction force generated by the high-speed rotation of the classifying wheel, the two work together to ensure that the fine powder is accurately drawn into the classifying wheel. This structural design solves the problems of unstable airflow and insufficient power in multi-stage processing with a single power source, ensuring the continuity and stability of the classification process, and further improving the sorting accuracy and system reliability. Attached Figure Description

[0018] 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.

[0019] Figure 1 This is a diagram of the overall system architecture of the present invention; Figure 2 This is a schematic diagram of the push-pull combined power system of the present invention; Figure 3 This is a flowchart of the method steps of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] This embodiment discloses a high-efficiency internal circulation system for desulfurizing agents based on low-pressure transportation and precise grading, according to the appendix. Figure 1 To be continued Figure 3 As shown, the system includes an ash conveying system, a two-stage precision sorting unit, a desulfurizing agent silo, and a desulfurization ash silo. The ash conveying system is used to continuously convey desulfurization ash at a preset pressure. The inlet of the two-stage precision sorting unit is connected to the outlet of the ash conveying system, and is used to perform two-stage classification on the conveyed desulfurization ash. It includes a first-stage pre-separator and a second-stage dynamic airflow classifier arranged in series. The desulfurizing agent silo is connected to the fine powder outlet of the second-stage dynamic airflow classifier, and is used to receive and store the sorted high-activity desulfurizing agent fine powder. The desulfurization ash silo is connected to the coarse material outlet of the first-stage pre-separator and the coarse material outlet of the second-stage dynamic airflow classifier, and is used to receive and store the sorted coarse-particle desulfurization ash. This system achieves efficient separation of desulfurization ash and internal recycling of desulfurizing agent through the organic combination of low-pressure conveying and precision classification.

[0022] Furthermore, the ash conveying system is a low-pressure continuous conveying system with an operating pressure set between 0.08 MPa and 0.15 MPa. It includes a pneumatic conveying pump and a conveying pipeline connected to the outlet of the pneumatic conveying pump. The ash conveying system is used to steadily convey desulfurization ash in a dense phase form. Dense phase conveying refers to the conveying of materials in the pipeline with a high solid-to-gas ratio. The materials flow in a pulsating dune or plunger-like manner. Compared with dilute phase conveying, this conveying method has advantages such as low flow velocity, low energy consumption, and less pipeline wear. The pneumatic conveying pump is preferably a low-pressure Roots blower combined with a jet pump or a low-pressure silo pump. The conveying concentration and speed can be controlled by adjusting the air supply. The conveying pipeline is made of wear-resistant materials, and the pipeline route should avoid sharp bends as much as possible to reduce the scouring and wear of the pipe wall by the material.

[0023] Furthermore, the two-stage dynamic airflow classifier includes a classifying shell, a classifying wheel, and a variable frequency motor. The classifying shell is equipped with a feed inlet, a fine powder outlet, and a coarse material outlet. The classifying wheel is rotatably installed inside the classifying shell. The variable frequency motor is connected to the classifying wheel drive and is used to change the cutting particle size of the classifying wheel by adjusting the rotation speed, thereby achieving precise separation of powders of different particle sizes. The working principle of the classifying wheel is based on the balance between centrifugal force and airflow drag: when the airflow containing solid particles enters the classifying wheel area, the particles are simultaneously subjected to radial airflow drag pointing towards the center of the classifying wheel and centrifugal force pointing towards the outer edge of the classifying wheel. For particles with smaller particle sizes, their mass and inertia are small, and the airflow drag is dominant, so they are sucked into the classifying wheel and discharged from the fine powder outlet. For particles with larger particle sizes, centrifugal force is dominant, and they are thrown towards the outer edge of the classifying wheel and discharged from the coarse material outlet. By steplessly adjusting the rotation speed of the classifying wheel by the variable frequency motor, the cutting particle size d50 can be precisely controlled to adapt to the requirements of the recovered fine powder particle size under different working conditions.

[0024] Furthermore, the system also includes a push-suction composite power system consisting of a front-end pushing unit and a rear-end suction unit. The front-end pushing unit includes an ash conveying system used to push the desulfurization ash to the two-stage precision sorting unit. The rear-end suction unit includes a dust collector fan connected to the desulfurizing agent silo, used to create negative pressure in the two-stage dynamic airflow classifier and guide the airflow containing fine powder through. The design of this composite power system breaks through the limitations of traditional single power sources and solves the problems of power attenuation and unstable airflow during long-distance transportation or multi-stage classification. The pushing force of the front section ensures that the material can overcome pipeline resistance and reach the sorting unit smoothly, while the suction force of the rear section ensures that the dust-laden airflow can pass smoothly through the two-stage sorting equipment. The two work together to form a stable flow field.

[0025] It is worth noting that the downstream suction unit also includes a local suction force generated by the high-speed rotating classifying wheel inside the two-stage dynamic airflow classifier. The local suction force works in conjunction with the system negative pressure generated by the dust collector fan to draw fine powder that meets the particle size requirements into the classifying wheel and discharge it from the fine powder outlet. The classifying wheel itself is a high-speed rotating impeller structure. When the classifying wheel rotates, it forms a local negative pressure zone around the wheel, generating a suction effect similar to that of a fan. This local suction force is superimposed on the main negative pressure of the system, which on the one hand enhances the directional movement of fine powder into the classifying wheel, and on the other hand helps to prevent fine powder from accumulating on the outer wall of the classification area, ensuring the continuous and stable classification process.

[0026] It needs to be specifically disclosed that the primary pre-separator is a cyclone separator. The feed inlet of the primary pre-separator is tangentially connected to the outlet of the ash conveying system. It is used to achieve the primary separation of coarse desulfurization ash particles and dust-laden airflow under the action of centrifugal force. The cyclone separator has a simple structure, no moving parts, and is easy to maintain, making it suitable as a pre-separation device. After the dust-laden airflow enters the cyclone separator tangentially, it forms a high-speed rotating airflow inside the cylinder. The solid particles are thrown against the wall of the separator under the action of centrifugal force, settle along the wall surface, and are discharged from the bottom coarse material outlet. The purified airflow containing fine powder is discharged upward from the central air outlet and enters the next stage of sorting equipment. In this embodiment, the separation particle size of the cyclone separator is designed to be 20-30μm to ensure that most of the desulfurization by-product particles are separated at this stage.

[0027] It is particularly important to emphasize that the feed inlet of the secondary dynamic air classifier is connected to the air outlet of the primary pre-separator via an air guide pipe. The air guide pipe is designed to allow the airflow to enter the classification zone where the classifier wheel is located from bottom to top. This bottom-in, top-out airflow organization method is conducive to the natural settling of particles in the gravitational field. Coarse particles have a reduced velocity during the upward process and are more easily thrown out by the classifier wheel. At the same time, it can avoid the problem of particle deposition and blockage in the horizontal or downward pipe. The length of the air guide pipe should be shortened as much as possible, and the number of bends should be reduced as much as possible to reduce system resistance.

[0028] It is particularly important to emphasize that the coarse material outlet of the primary pre-separator and / or the coarse material outlet of the secondary dynamic air classifier are connected to the mechanical conveying equipment via pipelines. The outlet of the mechanical conveying equipment is connected to the desulfurization ash silo. The mechanical conveying equipment can be a buried scraper conveyor or a screw conveyor. The mechanical conveying equipment has a low conveying speed and good sealing performance, making it suitable for conveying highly abrasive desulfurization ash. An airlock discharge valve can be installed at the coarse material outlet to prevent external air from entering the system and disrupting the negative pressure balance.

[0029] Furthermore, the variable frequency motor has a speed adjustment range of 800-1800 r / min, which is used to sort out highly active calcium hydroxide fine powder with different particle size thresholds. The speed is inversely proportional to the cutting particle size: the higher the speed, the greater the centrifugal force, the smaller the maximum particle size that the classifying wheel can pass through, and the finer the recovered fine powder. According to the requirements of different desulfurization processes on the activity of desulfurizing agents, the optimal speed can be determined by experiment. For example, when it is necessary to recover ultrafine calcium hydroxide powder with d50≤10μm, the speed of the classifying wheel can be adjusted to above 1500 r / min; when the recovery requirements are more lenient, the speed can be appropriately reduced.

[0030] In addition, the system also includes an automatic control system, which includes a PLC controller, pressure sensors, temperature sensors, and a frequency converter driver. The pressure sensors are installed in the ash conveying pipeline and the inlet and outlet of the classifier to monitor system pressure changes in real time; the temperature sensors are installed in key parts to monitor material temperature; the frequency converter driver is electrically connected to the frequency converter motor and receives control signals from the PLC controller to realize automatic adjustment of the classifier wheel speed. The PLC controller automatically adjusts the air supply pressure of the ash conveying system and the classifier wheel speed according to the preset classification parameters and real-time feedback signals to realize fully automatic operation of the system.

[0031] To improve the reliability of system operation, a buffer silo can be set between the outlet of the ash conveying system and the inlet of the two-stage precision sorting unit to balance the fluctuation of material flow. The buffer silo is equipped with high and low level gauges. When the material level is too high or too low, the control system adjusts the ash conveying speed or issues an alarm signal accordingly.

[0032] Both the desulfurizing agent silo and the desulfurization ash silo are equipped with dust collectors on the silo top and level gauges. The dust collectors on the silo top are used to filter the gas inside the silo and prevent dust from leaking out. The level gauges are used to monitor the material storage in the silo in real time, which facilitates the arrangement of conveying and transfer operations. The bottom of the desulfurizing agent silo is equipped with a discharge device to quantitatively transport the recovered high-activity desulfurizing agent fine powder back to the desulfurization reactor. The bottom of the desulfurization ash silo is equipped with a discharge device to discharge the waste desulfurization ash from the system, which can be further utilized as a resource.

[0033] The workflow of this system will be described in detail below with reference to specific embodiments.

[0034] Example 1: This example uses a flue gas desulfurization system for a steel sintering machine as an example, combined with the attached... Figure 1 To be continued Figure 3 Detailed workflow description: A steel plant has installed a calcium-based dry desulfurization system to support its sintering machine. The flue gas treatment capacity is 600,000 Nm³ / h. The desulfurizing agent is highly active calcium hydroxide powder. The desulfurization ash collected in the bag filter dust hopper was tested and found to contain approximately 25% unreacted calcium hydroxide, with the remainder being calcium sulfite, calcium sulfate, and a small amount of fly ash.

[0035] The workflow is as follows: Step S1, Low-pressure conveying: Desulfurization ash enters the low-pressure continuous conveying system through the ash hopper outlet. The system uses a Roots blower as the air source, and the working pressure is set to 0.12MPa. The pneumatic conveying pump mixes the desulfurization ash with low-pressure air to form a dense phase fluidized material, which is then smoothly conveyed to the two-stage precision sorting unit through a DN150 conveying pipeline. The conveying distance is about 80 meters.

[0036] Step S2, Primary coarse separation: The desulfurization ash first enters the cyclone separator. After the material enters the separator tangentially, it undergoes primary separation under the action of centrifugal force. Coarse desulfurization byproducts (mainly calcium sulfite, calcium sulfate, and unreacted coarse particles) are discharged from the bottom coarse material outlet, fall into the buried scraper conveyor through the airlock discharge valve, and are transported to the desulfurization ash silo for temporary storage. The airflow containing unreacted calcium hydroxide fine powder is discharged from the top air outlet of the cyclone separator and enters the secondary dynamic airflow classifier from bottom to top through the air guide pipe.

[0037] Step S3, Secondary Separation: The dust-laden airflow enters the dynamic airflow classifier. The classifying wheel rotates at 1200 r / min driven by a variable frequency motor. Under the combined action of centrifugal force and airflow drag, the high-activity calcium hydroxide fine powder with a particle size of less than 15 μm is drawn into the classifying wheel due to the greater airflow drag than the centrifugal force and is discharged from the fine powder outlet. Meanwhile, the medium-sized powder with a larger particle size (mainly partially reacted calcium hydroxide and fine particulate by-products) is thrown out and discharged from the coarse material outlet, and then sent to the desulfurization ash silo by a screw conveyor.

[0038] Step S4, Recycling: The highly active calcium hydroxide fine powder discharged from the fine powder outlet is sent into the desulfurizing agent silo through a pneumatic conveying system. After being mixed with fresh desulfurizing agent at a ratio of 1:3, it is sprayed back into the desulfurization reactor for use. After testing, the calcium hydroxide content in the recovered fine powder reaches 68%, and the activity is well maintained, which effectively improves the utilization rate of desulfurizing agent.

[0039] Example 2: This example uses the adjustment of the speed of the staged wheel under different working conditions as an example, combined with the attached... Figure 2 Detailed workflow description: Due to changes in raw materials, the unreacted calcium hydroxide content in the desulfurization ash of a cement plant fluctuates significantly (15%–35%), and the fineness distribution is unstable. To adapt to this change, this system fully utilizes the advantages of frequency conversion regulation to dynamically adjust the speed of the classifying wheel according to the characteristics of different batches of desulfurization ash.

[0040] When the desulfurization ash contains a high content of fine powder and has a fine particle size (d50 of about 8μm), the control system adjusts the speed of the classifying wheel to 1600r / min to increase the centrifugal force field strength, ensuring that only the finest and most active calcium hydroxide particles can pass through the classifying wheel, avoiding the mixing of some medium-sized powders with lower activity into the recycled material, and ensuring the quality of recycling.

[0041] When the fine powder content in the desulfurization ash is low and the particles are relatively coarse (d50 is about 18μm), the control system adjusts the speed of the classifying wheel to 900r / min, appropriately reduces the centrifugal force, expands the range of recovered particle sizes, and increases the total amount recovered to meet the system's demand for desulfurizing agent replenishment.

[0042] Through this dynamic adjustment, the system can maintain a stable recovery effect under different operating conditions, reduce the consumption of desulfurizing agent by 22%, and significantly improve the economic efficiency of system operation.

[0043] Example 3: This example uses system startup / shutdown and fault handling as examples, combined with the appendix. Figure 1 To be continued Figure 3 Detailed workflow description: When starting the system, follow the principle of starting first and then feeding: first start the dust collector fan on the top of the desulfurizing agent silo to establish negative pressure in the system; after the negative pressure stabilizes, start the variable frequency motor of the secondary dynamic airflow classifier and set the initial speed to 1000 r / min; then start the Roots blower and pneumatic conveying pump of the low-pressure continuous conveying system to gradually increase the air supply and feed rate, so that the system can smoothly transition to normal operation.

[0044] When the system is shut down normally, follow the principle of stopping first and then shutting down: first stop the pneumatic conveying pump to feed material, and then turn off the Roots blower after the material in the conveying pipeline has been blown clean; then stop the classifier wheel motor; and finally turn off the dust collector blower on the top of the silo after the airflow in the classifier has stabilized.

[0045] When a system malfunctions, such as an abnormal increase in pressure in the conveying pipeline, the control system automatically executes a protection procedure: immediately stops feeding, keeps the Roots blower running to purge the pipeline, and simultaneously issues an alarm signal to prompt the operator to check and handle the issue. After the fault is cleared, the system can automatically resume operation or be manually reset and restarted.

[0046] The above three embodiments fully demonstrate the adaptability and reliability of this system under different working conditions. Through the combination of low-pressure conveying and precision classification, as well as the design of the push-suction composite power system, this system achieves efficient separation of desulfurization ash and internal recycling of desulfurizing agent, and has the advantages of energy saving and consumption reduction, low wear, high recovery accuracy and stable operation.

[0047] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-efficiency internal circulation system for desulfurizing agents based on low-pressure conveying and precise grading, characterized in that, include: The ash conveying system is used to continuously convey desulfurization ash at a preset pressure; The two-stage precision sorting unit has its inlet connected to the outlet of the ash conveying system and is used to classify the desulfurization ash in two stages, including a first-stage pre-separator and a second-stage dynamic airflow classifier arranged in series. The desulfurizing agent silo is connected to the fine powder outlet of the secondary dynamic airflow classifier and is used to receive and store the sorted high-activity desulfurizing agent fine powder. The desulfurization ash silo is connected to the coarse material outlet of the primary pre-separator and the coarse material outlet of the secondary dynamic airflow classifier, and is used to receive and store the sorted coarse desulfurization ash particles.

2. The high-efficiency internal circulation system for desulfurizing agent based on low-pressure conveying and precise grading according to claim 1, characterized in that, The ash conveying system is a low-pressure continuous conveying system with an operating pressure of 0.08 MPa to 0.15 MPa. It includes a pneumatic conveying pump and a conveying pipeline connected to the outlet of the pneumatic conveying pump. The ash conveying system is used to steadily convey desulfurization ash in a dense phase form.

3. The high-efficiency internal circulation system for desulfurizing agent based on low-pressure conveying and precise grading according to claim 1, characterized in that, The two-stage dynamic airflow classifier includes: A grading shell, which is provided with the feed inlet, the fine powder outlet and the coarse material outlet; The grading wheel is rotatably mounted inside the grading housing; A variable frequency motor is connected to the classifying wheel drive and is used to change the cutting particle size of the classifying wheel by adjusting the rotation speed, thereby achieving precise separation of powders of different particle sizes.

4. The high-efficiency internal circulation system for desulfurizing agent based on low-pressure conveying and precise grading according to claim 1, characterized in that, The system also includes a push-suction composite power system consisting of a front-end push unit and a rear-end suction unit; The front-end pushing unit includes the ash conveying system, which is used to push the desulfurization ash to the two-stage precision sorting unit; The downstream suction unit includes a dust collector fan connected to the desulfurizing agent silo, which is used to create negative pressure in the secondary dynamic airflow classifier and guide the airflow containing fine powder through.

5. The high-efficiency internal circulation system for desulfurizing agent based on low-pressure conveying and precise grading according to claim 1, characterized in that, The rear suction unit also includes a local suction force generated by the high-speed rotating classifying wheel inside the secondary dynamic airflow classifier. The local suction force works in conjunction with the system negative pressure generated by the dust collector fan to draw fine powder that meets the particle size requirements into the classifying wheel and discharge it from the fine powder outlet.

6. The high-efficiency internal circulation system for desulfurizing agent based on low-pressure conveying and precise grading according to claim 1, characterized in that, The primary pre-separator is a cyclone separator. The feed inlet of the primary pre-separator is tangentially connected to the outlet of the ash conveying system, and is used to achieve primary separation of coarse desulfurization ash particles and dust-laden airflow under centrifugal force.

7. The high-efficiency internal circulation system for desulfurizing agent based on low-pressure conveying and precise grading according to claim 1, characterized in that, The feed inlet of the secondary dynamic airflow classifier is connected to the air outlet of the primary pre-separator through an air guide pipe, and the direction of the air guide pipe is configured to allow the airflow to enter the classification zone where the classifier wheel is located from bottom to top.

8. The high-efficiency internal circulation system for desulfurizing agent based on low-pressure conveying and precise grading according to claim 1, characterized in that, The coarse material outlet of the primary pre-separator and / or the coarse material outlet of the secondary dynamic air classifier are connected to a mechanical conveying device via pipelines, and the outlet of the mechanical conveying device is connected to the desulfurization ash silo.

9. The high-efficiency internal circulation system for desulfurizing agent based on low-pressure conveying and precise grading according to claim 3, characterized in that, The variable frequency motor has a speed adjustment range of 800-1800 r / min, which is used to sort out highly active calcium hydroxide fine powder with different particle size thresholds.

10. A method based on the high-efficiency internal circulation system for desulfurizer based on low-pressure conveying and precise grading as described in any one of claims 1 to 9, characterized in that, The method includes the following steps: Step S1, Low-pressure conveying: The desulfurization ash from the desulfurization reactor is continuously conveyed to the two-stage precision sorting unit in a low-pressure, dense-phase form through an ash conveying system with an operating pressure of less than 0.2 MPa. Step S2, primary coarse separation: Desulfurization ash enters the primary pre-separator, where it undergoes primary separation under centrifugal force. The separated coarse desulfurization ash particles are discharged into the desulfurization ash silo, while the airflow containing unreacted desulfurizing agent fine powder enters the next stage. Step S3, Secondary Fine Separation: The dust-laden airflow enters the secondary dynamic airflow classifier. By adjusting the rotation speed of the classifying wheel, a controllable centrifugal force field is generated, causing the highly active ultrafine desulfurizing agent powder, whose airflow drag force is greater than the centrifugal force, to be drawn into the classifying wheel and discharged from the fine powder outlet. Step S4, recycling: The high-activity desulfurizing agent fine powder discharged from the fine powder outlet is sent to the desulfurizing agent silo for reuse in the desulfurization reactor, while the medium-sized powder discharged from the medium and coarse material outlet is sent to the desulfurization ash silo.

Images