Low-energy-consumption high-stability circulating fluidized bed back feeding system and control method thereof

Abstract

The present application relates to circulating fluidized bed combustion, gasification, chemical reaction equipment manufacturing and operation technical field, aims at solving the problems of material flow dead zone, poor dredging accuracy, high ventilation energy consumption, unstable system operation and lack of automatic regulation, provides a low energy consumption, high stability circulating fluidized bed return material system and its control method, containing downcomer, down curve channel, horizontal section, rising channel, also set air distribution device, loose air, pressure monitoring and control system; The pressure monitoring system is provided with a plurality of pressure measuring points at different heights of the downcomer, the control system is electrically connected with the former two and adjusts the loose air volume according to the pressure data. The control method determines the material flow condition by collecting data, automatically controls the opening and closing of the air distribution and loose air regulating valve, and realizes real-time monitoring and automatic pressure relief control of the high-pressure fan. The present application has the advantages of stable material flow, no dead zone, accurate air distribution and low energy consumption, stable system operation, intelligent control and self-adaptation.

Description

Technical Field

[0001] This invention relates to the field of manufacturing and operation technology of circulating fluidized bed combustion, gasification, and chemical reaction equipment. Specifically, it relates to a low-energy-consumption, high-stability circulating fluidized bed material return system and its control method. Background Technology

[0002] In the field of circulating fluidized bed combustion, gasification, and chemical reaction equipment manufacturing and operation, the return system is the core system of the circulating fluidized bed device. Its core function is to stably return the high-temperature material captured by the separation system to the furnace, reactor, or riser, maintain the stable operation of the material circulation loop, and at the same time maintain the gas sealing on both sides of the system inlet and outlet to prevent gas short circuits. The system mainly consists of the return device body, measuring device, and ventilation system. The existing return device body uses right-angle turns to connect the descending, horizontal, and ascending channels. The ventilation system is equipped with high-pressure blowers, air ducts, and zoned air distribution plates, and adopts a fixed air volume operation mode under different circulating material volume conditions.

[0003] The existing material return system has many technical defects. Right-angle turns are prone to forming dead zones in material flow, which seriously affects the stability of material return. The air distribution plate has a large area and insufficient precision in unblocking position. To alleviate the dead zone, the bottom ventilation volume needs to be increased, resulting in high ventilation energy consumption. At the same time, high air volume operation will reduce the gas-solid separation efficiency of the upstream cyclone separator, affecting the overall operational stability of the system. Moreover, the fixed air volume operation control method lacks automatic adjustment performance and cannot achieve timely automatic optimization of the operating status, resulting in a low level of intelligent operation of the system. Summary of the Invention

[0004] The present invention aims to provide a low-energy-consumption, high-stability circulating fluidized bed material return system and its control method to solve the problems in the prior art, such as easy formation of flow dead zones during material return, poor dredging accuracy, high ventilation energy consumption, large air volume affecting the overall stability of the system, and lack of automatic adjustment in operation control.

[0005] The embodiments of the present invention are implemented as follows: This invention provides a low-energy-consumption, high-stability circulating fluidized bed recirculation system, which includes a descending channel, a horizontal section, an ascending channel, and a unique descending curve channel connected in sequence. The aforementioned descending curve channel is located between the aforementioned descending channel and the aforementioned horizontal segment. The inclination angle of the aforementioned descending curve channel gradually and smoothly decreases from 90° and smoothly connects with the aforementioned horizontal segment. It also includes a ventilation system, a loosening air device, a pressure monitoring system, and a control system; The aforementioned loosening air device includes upper loosening air, middle loosening air, and bottom loosening air arranged in the aforementioned descending channel, the aforementioned descending curve channel, and the aforementioned horizontal section material easy accumulation area; The aforementioned pressure monitoring system includes measuring points P1, P2, and P3 arranged at different heights in the aforementioned descent channel; The aforementioned control system is electrically connected to the aforementioned air distribution system, air loosening device, and pressure monitoring system, respectively.

[0006] This embodiment discloses a low-energy-consumption, high-stability circulating fluidized bed material return system. By designing the connection between the aforementioned descending channel and the aforementioned horizontal section as a descending curved channel with an inclination angle smoothly decreasing from 90° and smoothly connecting to the aforementioned horizontal section, it structurally eliminates the material flow dead zone easily formed by traditional right-angle turns. Relying on the material's own gravity, it achieves smooth turning, significantly improving the continuity and stability of material flow. Simultaneously, the loosening air device is precisely positioned in the material-prone areas of the descending channel, the descending curved channel, and the horizontal section, abandoning the traditional large-area bottom air distribution method, achieving localized precise unblocking, reducing the total amount of fluidizing air used, and effectively reducing ventilation energy consumption and system resistance. Furthermore, the arrangement of the aforementioned P1, P2, and P3 measuring points at different heights in the descending channel constitutes a... The pressure monitoring system, in conjunction with the control system that is electrically connected to both the aforementioned air distribution system and the pressure monitoring system, can determine the material flow conditions in real time through pressure detection data and precisely adjust the air volume of loosening air in each area, forming a closed-loop control of pressure acquisition, condition determination, and air volume adjustment. This achieves intelligent and adaptive operation of the material return system, further optimizing energy consumption while ensuring smooth material flow. The system as a whole possesses both high stability and low energy consumption characteristics, and its structural design is more in line with the material circulation requirements of the circulating fluidized bed. The reliability and adaptability of operation are greatly improved, resulting in a low-energy-consumption, high-stability circulating fluidized bed material return system with the beneficial effects of stable material flow without dead zones, precise air distribution and dredging with low ventilation energy consumption, overall system stability, and intelligent adaptive control.

[0007] Optionally, the above-mentioned upper loosening air, the above-mentioned middle loosening air and the above-mentioned bottom loosening air are all ducts arranged in a dot matrix or ring, and are arranged in a ring dot matrix along the material flow section at the easily blocked or bridging positions of the above-mentioned descending channel, the above-mentioned descending curve channel, and the bottom wall-attached area of ​​the above-mentioned horizontal section.

[0008] This configuration, with its upper, middle, and bottom loosening airflows, precisely matches the key locations where materials are prone to clogging and bridging. It replaces the traditional large-area bottom air distribution, achieving efficient unblocking through point-type or ring-shaped localized air distribution. This significantly reduces the total amount of fluidizing air used, lowers ventilation energy consumption and system resistance, and avoids interference with material flow caused by ineffective air distribution, further improving the material flow stability and operational reliability of the return material system.

[0009] Optionally, the material inlet and outlet of the recycling system can be configured as a single-in-single-out, single-in-multiple-out, or multiple-in-single-out structure.

[0010] With this configuration, the material inlet and outlet of the recycling system can be configured in multiple ways to flexibly adapt to the material circulation requirements of different application scenarios such as coal-fired fluidized bed boilers, gasifiers, and chemical loop combustion devices. This allows for diverse combinations of the aforementioned descending and ascending channels, significantly improving the scenario adaptability and application versatility of the recycling system. At the same time, the channel layout can be optimized according to actual working conditions to further ensure the smoothness of material circulation and the stability of system operation.

[0011] Optionally, the above-mentioned air distribution system further includes an air distribution chamber connected to the high-pressure blower, a first control valve, a second control valve, a third control valve, and a fourth control valve. The first control valve, the second control valve, the third control valve, and the fourth control valve are respectively connected to the air distribution chamber, the upper loosening air, the middle loosening air, and the bottom loosening air. The high-pressure blower provides a fluidizing medium for the loosening air device. The control system is electrically connected to the high-pressure blower, the first control valve, the second control valve, the third control valve, and the fourth control valve.

[0012] This configuration allows the control system to precisely and independently adjust the airflow at different clog-prone locations based on the working conditions, achieving refined and intelligent air distribution. This ensures effective material unblocking while avoiding airflow waste, further reducing ventilation energy consumption and improving the accuracy and stability of the material return system.

[0013] Optionally: the radius of curvature of the aforementioned descending curve channel is 1.5 to 3 times the channel diameter, the overall material flow velocity of the return system is 0.1 m / s to 0.8 m / s, the average particle size of the material is 50 μm to 300 μm, and the operating temperature is 500℃ to 1200℃.

[0014] With this setting, the parameters are designed to define the optimal operating range for the material return system, which can be adapted to the material characteristics and operating environment of the circulating fluidized bed under normal operating conditions. This ensures the continuity and stability of the material flow in the channel, while also maximizing the efficiency of the loosening air device. It avoids problems such as material accumulation and increased energy consumption caused by parameter mismatch, ensuring that the material return system operates with low resistance, high efficiency and stability under the design conditions.

[0015] Optionally, the inner walls of the channels in the circulating fluidized bed return system are lined with heat-insulating and wear-resistant materials.

[0016] With this design, the heat-insulating and wear-resistant material lining the inner wall of the channel can effectively resist the erosion and wear of material flow under high-temperature conditions, while reducing heat loss from the system. It is suitable for the high-temperature operating environment of the return material system from 500℃ to 1200℃, extending the service life of the equipment and reducing heat loss.

[0017] Optionally: The above control system is a PLC control device with built-in control logic and is electrically connected to the online pressure measuring device. The online pressure measuring device is connected to measuring points P1, P2 and P3.

[0018] This setup enables real-time acquisition, transmission, and automatic analysis of pressure data. Built-in control logic directly drives the air distribution system, eliminating manual intervention and improving the automation and intelligence of the material return system. Simultaneously, it forms a closed-loop control system encompassing pressure acquisition, logic analysis, and airflow regulation, ensuring accurate condition assessment and timely, precise airflow adjustment. This effectively avoids material accumulation and increased energy consumption caused by delays or errors in manual operation, further enhancing the stability and efficiency of the material return system.

[0019] In one embodiment of this invention, a control method for a low-energy-consumption, high-stability circulating fluidized bed recirculation system is also provided. Based on the circulating fluidized bed recirculation system, the method includes the following steps: Step 1: Real-time pressure data at different heights in the descent channel is collected through the P1, P2 and P3 measuring points of the pressure monitoring system, and the data is transmitted to the control system. Step 2: The above control system determines the material accumulation height, flow smoothness, and whether local bridging occurs based on the positive and negative pressure values ​​of measuring points P1, P2, and P3. Step 3: Based on the judgment results, the above control system automatically adjusts the opening and closing states of the first control valve, the second control valve, the third control valve and the fourth control valve in the air distribution system to achieve precise control of the loosening air volume in different easy-to-accumulate areas, thereby reducing the total amount of high-pressure fluidizing air used while ensuring smooth material flow.

[0020] Optionally: The rules for determining the positive and negative values ​​of pressure in step 2 and the corresponding valve control rules in step 3 are as follows: When the values ​​of measuring points P1, P2 and P3 are all negative, it is determined that the material stacking height in the descending channel is low and the material flow is normal. Only the first control valve is opened and the other valves are closed. When the value of measuring point P1 is positive and the values ​​of measuring points P2 and P3 are negative, it is determined that the material height is slightly high and the flow resistance is too large. Keep the first control valve open, open the fourth control valve at the same time, and close the second and third control valves. When the values ​​of measuring points P1 and P2 are positive and the value of measuring point P3 is negative, it is determined that the material accumulation height is too high and the flow resistance is too large. The first control valve, the third control valve, and the fourth control valve are opened, and the second control valve is closed. When the values ​​of measuring points P1, P2 and P3 are all positive, it is determined that the material accumulation height is seriously too high and the flow is not smooth. The first control valve, the second control valve, the third control valve and the fourth control valve are all opened. When the value of measuring point P1 is negative and the values ​​of measuring points P2 and P3 are positive, it is determined that a partial bridging has occurred in the descent channel. The first control valve remains open, while the second control valve is opened and the third and fourth control valves are closed.

[0021] This setup establishes clear operating condition judgment rules and corresponding valve control logic through the positive and negative value combinations of measuring points P1, P2, and P3. It enables precise and rapid judgment of operating conditions such as material accumulation height, flow resistance, and local bridging in the recycling system. Furthermore, it allows for the on-demand opening and closing of corresponding regulating valves based on different operating conditions, ensuring on-demand and precise control of loosening air. This guarantees smooth material flow under various operating conditions while avoiding energy waste caused by ineffective air distribution. Simultaneously, these rules and logic make the automatic control system more targeted and operable, further improving the closed-loop control of pressure acquisition, logic analysis, and airflow regulation. This significantly enhances the automation and precision of the recycling system's operation control, effectively avoiding the lag and errors of manual operation, and ensuring long-term stable and low-energy operation of the system.

[0022] Optionally, the control method for the circulating fluidized bed return system also includes the operation control of the high-pressure blower in the air distribution system. Based on the real-time monitoring data of the outlet pressure and air volume of the high-pressure blower, when the outlet pressure exceeds the set value, the blower automatically depressurizes to ensure stable ventilation air volume and normal system operation.

[0023] This configuration ensures timely pressure relief when the outlet pressure exceeds the set value, guaranteeing a stable supply of ventilation air to the air distribution system and meeting the demand for loosening air under different operating conditions. It also avoids increased energy consumption and equipment damage caused by overpressure operation of the blower, extending the blower's service life. At the same time, this control method works in conjunction with the valve regulation logic to improve the automatic control system of the entire air distribution system, further enhancing the overall stability, safety, and energy efficiency of the return material system, and ensuring that the system can operate with low resistance and high efficiency under various operating conditions.

[0024] In summary, the low-energy-consumption, high-stability circulating fluidized bed material return system and its control method disclosed in this invention have the beneficial effects of stable material flow without dead zones, precise air distribution and dredging with low ventilation energy consumption, overall stable system operation, and intelligent adaptive control. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1This is a schematic diagram of a low-energy-consumption, high-stability circulating fluidized bed material return system according to an embodiment of the present invention; Figure 2 This is an operation control diagram of the material return system in an embodiment of the present invention.

[0027] Icons: 1-Descending channel, 2-Horizontal section, 3-Ascending channel, 4-Descending curve channel, 5-Air distribution system, 6-Pressure monitoring system, 7-Control system, 8-Loosening air device, 10-High pressure fan, 12-P1 measuring point, 13-P2 measuring point, 14-P3 measuring point, 16-Control logic, 17-Online pressure measurement device, 18-Air distribution chamber, 19-Upper loosening air, 20-Middle loosening air, 21-Bottom loosening air, 22-First control valve, 23-Second control valve, 24-Third control valve, 25-Fourth control valve. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] Example 1 See Figure 1 and Figure 2 This embodiment proposes a low-energy-consumption, high-stability circulating fluidized bed material return system, which includes a descending channel 1, a horizontal section 2, an ascending channel 3 and a unique descending curve channel 4 connected in sequence. The descending curve channel 4 is located between the descending channel 1 and the horizontal segment 2. The tilt angle of the descending curve channel 4 gradually decreases smoothly from 90° and connects smoothly with the horizontal segment 2. It also includes a ventilation system 5, a loosening air device 8, a pressure monitoring system 6, and a control system 7; The loosening air device 8 has an upper loosening air 19, a middle loosening air 20, and a bottom loosening air 21 arranged in the material accumulation area of ​​the descending channel 1, the descending curve channel 4, and the horizontal section 2. The pressure monitoring system 6 includes P1 measuring point 12, P2 measuring point 13 and P3 measuring point 14 arranged at different heights in the descent channel 1 to realize real-time monitoring of the operating pressure at different locations; The control system 7 is electrically connected to the air distribution system 5, the loosening air device 8, and the pressure monitoring system 6, respectively, and is used to adjust the air volume of the air distribution system 5 and the loosening air device 8 according to the detection data of the pressure monitoring system 6.

[0031] This embodiment discloses a low-energy-consumption, high-stability circulating fluidized bed material return system. By designing the connection between the descending channel 1 and the horizontal section 2 as a descending curved channel 4 with a smoothly decreasing inclination angle from 90° and a smooth connection to the horizontal section 2, it structurally eliminates the dead zones in material flow that are easily formed by traditional right-angle turns. Relying on the material's own gravity, it achieves smooth turning, significantly improving the continuity and stability of material flow. Simultaneously, the loosening air device 8 is precisely positioned in the material-prone areas of the descending curved channel 4 and the horizontal section 2, abandoning the traditional large-area bottom air distribution method and achieving precise local unblocking, reducing the total amount of fluidizing air used and effectively lowering ventilation energy consumption and system resistance. Furthermore, by arranging measuring points P1 12, P2 13, and P3 at different heights in the descending channel 1... The pressure monitoring system 6, together with the control system 7 which is electrically connected to both the air distribution system 5 and the pressure monitoring system 6, can determine the material flow conditions in real time through pressure detection data and accurately adjust the air volume of loosening air in each area, forming a closed-loop control of pressure acquisition, condition determination, and air volume regulation. This realizes the intelligent and adaptive operation of the material return system, further optimizing energy consumption while ensuring smooth material flow. The system as a whole has both high stability and low energy consumption characteristics, and its structural design is more in line with the material circulation requirements of the circulating fluidized bed. The reliability and adaptability of operation are greatly improved. As a result, a low-energy-consumption, high-stability circulating fluidized bed material return system has the beneficial effects of stable material flow without dead zones, precise air distribution and dredging with low ventilation energy consumption, overall stable system operation, and intelligent adaptive control.

[0032] See Figure 1 and Figure 2 The upper loosening air 19, middle loosening air 20, and bottom loosening air 21 are all ducts arranged in a dot matrix or ring pattern. They are arranged in a ring pattern along the material flow section at the easily blocked or bridging locations in the bottom wall area of ​​the descending channel 1, descending curve channel 4, and horizontal section 2. The arrangement of the upper loosening air 19, middle loosening air 20, and bottom loosening air 21 precisely matches the key locations where materials are easily blocked or bridging, replacing the traditional large-area bottom air distribution. It achieves efficient unblocking with point or ring-shaped local air distribution, significantly reducing the total amount of fluidizing air used, reducing ventilation energy consumption and system resistance, and avoiding interference of ineffective air distribution with material flow, further improving the material flow stability and operational reliability of the return material system.

[0033] The material inlet and outlet configuration of the recycling system can be single-in-single-out, single-in-multiple-out, or multiple-in-single-out structures. That is, one or N descending channels 1 are connected to one ascending channel 3, or one descending channel 1 is divided into one or N ascending channels 3. The multi-form configuration structure of the material inlet and outlet of the recycling system can flexibly adapt to the material circulation requirements of different application scenarios such as coal-fired fluidized bed boilers, gasifiers, and chemical loop combustion devices. It can realize diversified combination design of descending channel 1 and ascending channel 3, which greatly improves the scenario adaptability and application versatility of the recycling system. At the same time, the channel layout can be optimized according to the actual working conditions to further ensure the smoothness of material circulation and the stability of system operation.

[0034] See Figure 1 and Figure 2 The air distribution system 5 also includes an air distribution chamber 18 connected to the high-pressure blower 10, a first control valve 22, a second control valve 23, a third control valve 24, and a fourth control valve 25. The first control valve 22, the second control valve 23, the third control valve 24, and the fourth control valve 25 are respectively connected to the air distribution chamber 18, the upper loosening air 19, the middle loosening air 20, and the bottom loosening air 21. The high-pressure blower 10 provides a fluidizing medium for the loosening air device 8. The control system 7 is electrically connected to the high-pressure blower 10, the first control valve 22, the second control valve 23, the third control valve 24, and the fourth control valve 25. This allows the control system 7 to accurately and independently adjust the loosening air volume at different easily clogged locations according to the working conditions, achieving refined and intelligent air distribution. This ensures the material unblocking effect, avoids air volume waste, further reduces ventilation energy consumption, and improves the accuracy and stability of the return material system operation.

[0035] The radius of curvature of the descending curve channel 4 is 1.5 to 3 times the channel diameter. The overall material flow velocity of the return system is 0.1 m / s to 0.8 m / s, the average particle size of the material is 50 μm to 300 μm, and the operating temperature is 500℃ to 1200℃. These parameters define the optimal operating range for the return system, which can adapt to the material characteristics and operating environment of the circulating fluidized bed under normal operating conditions. This ensures the continuity and stability of the material flow in the channel, while also maximizing the efficiency of the loosening air device 8. This avoids problems such as material accumulation and increased energy consumption caused by parameter mismatch, ensuring that the return system operates with low resistance, high efficiency, and stability under the design conditions.

[0036] See Figure 1 and Figure 2 The inner walls of the channels in the circulating fluidized bed return system are all lined with heat-insulating and wear-resistant materials (not shown in the figure). The heat-insulating and wear-resistant materials lining the inner walls of the channels can effectively resist the scouring and wear of material flow under high temperature conditions, while reducing the heat loss of the system. It is suitable for the high temperature operating environment of the return system from 500℃ to 1200℃, extending the service life of the equipment and reducing heat loss.

[0037] The control system 7 is a PLC control device with built-in control logic 16, which is electrically connected to the online pressure measurement device 17. The online pressure measurement device 17 is connected to measuring points P1 12, P2 13, and P3 14, enabling real-time acquisition, transmission, and automatic analysis and judgment of pressure data. Relying on the built-in control logic 16, it directly drives the air distribution system 5 for regulation, eliminating manual intervention and improving the automation and intelligence level of the return material system's operation control. At the same time, it forms a closed-loop control system of pressure acquisition, logic analysis, and air volume regulation, ensuring the accuracy of working condition judgment and the timeliness and precision of air volume adjustment. This effectively avoids material accumulation and increased energy consumption caused by lag or error in manual operation, further improving the stability and efficiency of the return material system's operation.

[0038] See Figure 1 and Figure 2 In one embodiment of this invention, a control method for a low-energy-consumption, high-stability circulating fluidized bed recirculation system is also provided. Based on the circulating fluidized bed recirculation system, the method includes the following steps: Step 1: Real-time pressure data at different heights of the descent channel 1 is collected through the pressure monitoring system 6 at measuring points P1 12, P2 13 and P3 14, and the data is transmitted to the control system 7. Step 2: The control system 7 determines the material accumulation height, flow smoothness, and whether local bridging occurs based on the positive and negative pressure values ​​of measuring points P1 12, P2 13, and P3 14. Step 3: Based on the judgment result, the control system 7 automatically adjusts the opening and closing states of the first control valve 22, the second control valve 23, the third control valve 24 and the fourth control valve 25 in the air distribution system 5 to achieve precise control of the loosening air volume in different easy-to-accumulate areas, thereby reducing the total amount of high-pressure fluidizing air used while ensuring smooth material flow.

[0039] In step 2, the rules for determining the positive and negative values ​​of pressure and the corresponding valve control rules in step 3 are as follows: When the values ​​of measuring points P1112, P213 and P314 are all negative, it is determined that the material stacking height in the descending channel 1 is low and the material flow is normal. Only the first control valve 22 is opened and the other valves are closed. When the value of measuring point 12 of P1 is positive and the values ​​of measuring points 13 of P2 and 14 of P3 are negative, it is determined that the material height is slightly high and the flow resistance is too large. Keep the first control valve 22 open, open the fourth control valve 25 at the same time, and close the second control valve 23 and the third control valve 24. When the values ​​of measuring points P112 and P213 are positive and the value of measuring point P314 is negative, it is determined that the material accumulation height is too high and the flow resistance is large. The first control valve 22, the third control valve 24, the fourth control valve 25 are opened, and the second control valve 23 is closed. When the values ​​of measuring points P1112, P213 and P314 are all positive, it is determined that the material accumulation height is seriously too high and the flow is not smooth. The first control valve 22, the second control valve 23, the third control valve 24 and the fourth control valve 25 are all opened. When the value at measuring point P1 (12) is negative, and the values ​​at measuring points P2 (13) and P3 (14) are positive, it is determined that partial bridging has occurred in the descending channel 1. The first control valve 22 remains open, while the second control valve 23 is opened, and the third control valve 24 and the fourth control valve 25 are closed. By establishing clear operating condition judgment rules and corresponding valve control logic through the positive and negative value combinations of measuring points P1 (12), P2 (13), and P3 (14), accurate and rapid judgment of operating conditions such as material accumulation height, flow resistance, and partial bridging in the return material system is achieved. Furthermore, the corresponding valves can be opened and closed as needed according to different operating conditions. The first control valve 22, the second control valve 23, the third control valve 24, and the fourth control valve 25 ensure on-demand and precise control of the loosening air, guaranteeing smooth material flow under various operating conditions while avoiding energy waste caused by ineffective air distribution. At the same time, this rule and logic make the automatic control of the control system 7 more targeted and operable, further improving the closed-loop control of pressure acquisition, logic analysis, and air volume regulation, significantly enhancing the automation and precision of the return material system's operation control, effectively avoiding the lag and errors of manual operation, and ensuring long-term stable and low-energy operation of the system.

[0040] See Figure 1 and Figure 2 The control method for the circulating fluidized bed recirculation system also includes the operation control of the high-pressure blower 10 in the air distribution system 5. Based on the real-time monitoring data of the outlet pressure and air volume of the high-pressure blower 10, when the outlet pressure exceeds the set value, the blower automatically depressurizes to ensure stable ventilation volume and normal system operation. Timely depressurization when the outlet pressure exceeds the set value not only ensures a stable supply of ventilation volume in the air distribution system 5 to meet the demand for loosening air under different working conditions, but also avoids increased energy consumption and equipment damage caused by blower overpressure operation, thus extending the service life of the blower. At the same time, this control method works in conjunction with the valve control logic to improve the automatic control system of the entire process of the air distribution system 5, further enhancing the overall stability, safety, and energy efficiency of the recirculation system, and ensuring that the system can operate with low resistance and high efficiency under various working conditions.

[0041] The fluidizing medium introduced into the air distribution system 5 can be air, steam, pyrolysis gas, nitrogen, or high-purity CO2. The appropriate fluidizing medium is selected based on the application scenario of the circulating fluidized bed, which greatly improves the scenario adaptability and application versatility of the material return system. At the same time, the appropriate fluidizing medium can be selected according to the process requirements and media usage requirements of each scenario, effectively avoiding the adverse effects of incompatible media on process reactions and product quality, ensuring the coordinated and stable operation of the material return system and the main process system in various application scenarios, and giving full play to the technical advantages of low energy consumption and high stability of the material return system.

[0042] See Figure 1 and Figure 2 The control method is applied to the oxygen carrier particle circulation loop of coal-fired circulating fluidized bed boilers, biomass circulating fluidized bed gasifiers, or chemical loop combustion systems, significantly improving the scenario adaptability and application versatility of the material return system control scheme. It can meet the personalized requirements of material circulation, process reaction, and media use in various scenarios, ensuring the coordinated and stable operation of the material return system and each main process system. It can give full play to the technical advantages of low energy consumption and high stability in different application scenarios, effectively improving the overall operating efficiency and economy of each process system.

[0043] Example 2 See Figure 1 and Figure 2 Based on Example 1, this example is further optimized so that the control method is applied to a 350MW-class coal-fired circulating fluidized bed boiler: To address the large material circulation volume characteristic of large boilers, three "single-in, double-out" return feeders are designed. The descending channel 1 smoothly transitions to the horizontal section 2 using a circular arc curve with a radius of curvature of R1500mm, completely replacing the traditional two right-angle bends. Thirty-six loosely spaced air caps are evenly distributed in a matrix on the outer wall of the descending section curve and above the starting end of the horizontal section 2. The traditional bottom air vents are eliminated. An automatic operation control system 7 is employed to adjust the airflow under different operating conditions.

[0044] Operating parameters and results: Under rated load, the apparent flow velocity of material in the return feeder is approximately 0.3 m / s, and the operation is stable. Due to the elimination of the bulky bottom air distribution device, the volume of a single return feeder is reduced by approximately 22%, resulting in a more optimized overall boiler layout. The required total fluidizing / loosening air volume is reduced from approximately 12,500 Nm³ / h to approximately 9,500 Nm³ / h, a reduction of approximately 3,000 Nm³ / h (24%). Correspondingly, the power consumption of the high-pressure fluidizing blower is significantly reduced.

[0045] Beneficial effects: The reduced size decreases the amount of steel used and manufacturing costs; the reduced operating air volume directly reduces plant power consumption, and the average annual operating cost is expected to be reduced by more than 500,000 RMB.

[0046] Example 3 See Figure 1 and Figure 2 Based on Example 1, this example is further optimized so that when the control method is applied to a biomass circulating fluidized bed gasifier: Currently, in gasification processes, to maintain material circulation, introducing excessive amounts of ambient air or nitrogen (N2) as return air dilutes the syngas produced during gasification, significantly reducing its calorific value and quality. Therefore, in engineering practice, pyrolysis gas or superheated steam is often used as the return medium, which leads to system complexity, high safety risks (explosiveness, coking), and huge energy consumption in steam preparation.

[0047] The embodiment uses the curved channel return feeder of the present invention. The side wall of the descending section adopts an annular jacketed loosening air duct. Point loosening is carried out by a small amount of controllable medium-pressure steam (or partially purified circulating air), and the intelligent operation control method of the present invention is adopted.

[0048] Beneficial effects: Gas quality assurance: Due to the reduction in the required loose air volume, the interference and dilution of inert gas or steam on the main gasification reaction zone are greatly reduced, effectively ensuring the concentration and calorific value of the syngas.

[0049] Safety and Energy Consumption: The significant reduction in steam consumption directly lowers the load on the boiler or electric heater, resulting in a substantial decrease in system operating energy consumption. Simultaneously, due to the smaller required medium flow rate, the piping and control systems are simplified, reducing potential leakage and deflagration risks, thus simultaneously improving safety and reliability.

[0050] Economic efficiency: It reduces the consumption of high-quality steam, directly lowers the operating cost of the gasification unit, and improves the overall economic efficiency.

[0051] Example 4 See Figure 1 and Figure 2 Based on Example 1, this example is further optimized so that when the control method is applied to the oxygen carrier particle circulation loop of a chemical looping combustion system: Currently, chemical looping combustion requires isolating the air reactor from the fuel reactor to obtain a high-purity CO2 product gas stream. In traditional recirculation systems, to prevent air from entering the high-purity CO2 flue gas and reducing its purity, high-purity CO2 recirculation gas or steam is typically used as the fluidizing sealing medium. This not only requires additional gas compression, purification, or steam generation equipment, making the system extremely complex, but also results in a high proportion of the total system energy consumption being consumed by the medium circulation or preparation.

[0052] This embodiment employs the feeder system of the present invention, which utilizes the good flowability of the oxygen carrier particles to design a smoother descent curve. Only a very small flow rate of high-pressure CO2 (or steam) is introduced at key locations as a sealing and loosening medium. The automatic operation control of the present invention is used to minimize the amount of loosening gas used.

[0053] Beneficial effects: The flow requirements for high-pressure sealing or fluidizing media are reduced by approximately 50% to 70%, compressor / steam boiler energy consumption is reduced by more than 50%, gas pipelines are thinner, and initial investment is significantly reduced. The extremely low external medium flow rate minimizes the dilution of the high-concentration CO2 gas flow on the fuel reactor side, which is beneficial for subsequent CO2 capture and storage.

[0054] Improved economics: The dual reduction in equipment investment costs and operating energy consumption significantly enhances the overall economics and commercial application potential of chemical looping combustion technology.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-energy-consumption, high-stability circulating fluidized bed material return system, characterized in that: It includes a descending channel (1), a horizontal segment (2), an ascending channel (3), and a unique descending curve channel (4) that are connected in sequence. The descending curve channel (4) is located between the descending channel (1) and the horizontal segment (2). The tilt angle of the descending curve channel (4) gradually decreases smoothly from 90° and is smoothly connected to the horizontal segment (2). It also includes a ventilation system (5), a loosening air device (8), a pressure monitoring system (6), and a control system (7); The loosening air device (8) has an upper loosening air (19), a middle loosening air (20), and a bottom loosening air (21) arranged in the material accumulation area of ​​the descending channel (1), the descending curve channel (4), and the horizontal section (2); The pressure monitoring system (6) includes P1 measuring point (12), P2 measuring point (13) and P3 measuring point (14) arranged at different heights in the descent channel (1); The control system (7) is electrically connected to the air distribution system (5), the loosening air device (8), and the pressure monitoring system (6), respectively.

2. The low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 1, characterized in that: The upper loosening air (19), the middle loosening air (20) and the bottom loosening air (21) are all ducts arranged in a dot matrix or ring, and are arranged in a ring dot matrix along the material flow section at the easy-to-block or bridging positions of the bottom wall area of ​​the descending channel (1), the descending curve channel (4) and the horizontal section (2).

3. The low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 1, characterized in that: The material inlet and outlet configuration of the recycling system can be single inlet and single outlet, single inlet and multiple outlets, or multiple inlet and single outlet.

4. The low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 1, characterized in that: The air distribution system (5) also includes an air distribution chamber (18) connected to the high-pressure blower (10), a first control valve (22), a second control valve (23), a third control valve (24), and a fourth control valve (25). The first control valve (22), the second control valve (23), the third control valve (24), and the fourth control valve (25) are respectively connected to the air distribution chamber (18), the upper loosening air (19), the middle loosening air (20), and the bottom loosening air (21). The high-pressure blower (10) provides fluidizing medium for the loosening air device (8). The control system (7) is electrically connected to the high-pressure blower (10), the first control valve (22), the second control valve (23), the third control valve (24), and the fourth control valve (25).

5. The low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 1, characterized in that: The radius of curvature of the descending curve channel (4) is 1.5 to 3 times the channel diameter, the overall material flow velocity of the return system is 0.1 m / s to 0.8 m / s, the average particle size of the material is 50 μm to 300 μm, and the operating temperature is 500℃ to 1200℃.

6. The low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 1, characterized in that: The inner walls of the channels in the circulating fluidized bed return system are all lined with heat-insulating and wear-resistant materials.

7. The low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 1, characterized in that: The control system (7) is a PLC control device with built-in control logic (16) and is electrically connected to the pressure online measuring device (17). The pressure online measuring device (17) is connected to measuring point P1 (12), measuring point P2 (13) and measuring point P3 (14).

8. The control method for a low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 1, based on the circulating fluidized bed material return system according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Real-time pressure data of different heights of the descent channel (1) is collected through the pressure monitoring system (6) at measuring points P1 (12), P2 (13) and P3 (14), and the data is transmitted to the control system (7). Step 2, the control system (7) determines the material accumulation height, flow smoothness and whether local bridging occurs based on the positive and negative pressure values ​​of measuring points P1 (12), P2 (13) and P3 (14); Step 3: The control system (7) automatically adjusts the opening and closing states of the first control valve (22), the second control valve (23), the third control valve (24) and the fourth control valve (25) in the air distribution system (5) according to the judgment result, so as to achieve precise control of the loosening air volume in different easy-to-accumulate areas and reduce the total amount of high-pressure fluidizing air while ensuring smooth material flow.

9. The control method for a low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 8, characterized in that: In step 2, the rules for determining the positive and negative values ​​of pressure and the corresponding valve control rules in step 3 are as follows: When the values ​​of measuring points P1 (12), P2 (13) and P3 (14) are all negative, it is determined that the material stacking height in the descending channel (1) is low and the material flow is normal. Only the first control valve (22) is opened and the other valves are closed. When the value of measuring point P1 (12) is positive and the values ​​of measuring points P2 (13) and P3 (14) are negative, it is determined that the material height is slightly high and the flow resistance is too large. Keep the first control valve (22) open, open the fourth control valve (25) at the same time, and close the second control valve (23) and the third control valve (24). When the values ​​of measuring points P1 (12) and P2 (13) are positive and the value of measuring point P3 (14) is negative, it is determined that the material accumulation height is too high and the flow resistance is large. The first control valve (22), the third control valve (24), and the fourth control valve (25) are opened, and the second control valve (23) is closed. When the values ​​of measuring points P1 (12), P2 (13) and P3 (14) are all positive, it is determined that the material accumulation height is seriously too high and the flow is not smooth. The first control valve (22), the second control valve (23), the third control valve (24) and the fourth control valve (25) are all opened. When the value of measuring point P1 (12) is negative and the values ​​of measuring points P2 (13) and P3 (14) are positive, it is determined that a partial bridging has occurred in the descent channel (1). The first control valve (22) is kept open, the second control valve (23) is opened at the same time, and the third control valve (24) and the fourth control valve (25) are closed.

10. The control method for a low-energy-consumption, high-stability circulating fluidized bed material return system according to claim 8, characterized in that: The control method of the circulating fluidized bed return system also includes the operation control of the high pressure fan (10) in the air distribution system (5). According to the real-time monitoring data of the outlet pressure and air volume of the high pressure fan (10), when the outlet pressure exceeds the set value, the fan will automatically depressurize to ensure stable ventilation air volume and normal operation of the system.

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