Dry slagging machine furnace bottom air leakage regulation system and regulation method thereof

Abstract

The application discloses a dry slag discharging machine furnace bottom air leakage regulation system, which comprises a dry slag discharging machine, wherein an air inlet area, a dry slag machine conventional air leakage area and a dry slag machine cooling air inlet area are sequentially arranged from the air inlet of the dry slag discharging machine to the furnace bottom; the dry slag machine cooling air inlet area is provided with a linear air volume adjusting door; a temperature sensor is arranged at a slag bucket position of the furnace chamber and is used for acquiring the temperature of the furnace bottom air; an image recognition processing system is used for collecting image information of slag in the furnace chamber in real time; the image recognition processing system is used for calculating the slag falling amount according to the volume of the slag and the preset density of the slag; and a control system is used for acquiring the slag falling amount, the shape and size of the slag and the temperature of the furnace bottom air in real time and adjusting the air volume of the air inlet area adjusting door. The dry slag discharging machine furnace bottom air leakage regulation system and the regulation method thereof solve the problems of high time delay, untimely regulation, poor air leakage amount regulation and the like.

Description

Technical Field

[0001] This invention relates to the field of boiler combustion technology, and in particular to a dry ash discharge machine bottom air leakage control system and its control method. Background Technology

[0002] There are currently two main types of bottom ash removal systems for coal-fired boilers: one is a water-cooled wet ash removal system, and the other is an air-cooled dry ash removal system. The dry ash removal system has been rapidly adopted due to its energy-saving and water-saving advantages, and the comprehensive utilization value of dry ash is higher; its sales price as a power generation by-product is 3 to 5 times that of wet ash. During normal boiler operation, hot ash falling from the cold ash hopper is conveyed via the bottom ash removal device to the stainless steel conveyor belt of a variable-speed dry ash removal machine. Cooling air enters the machine through adjustable air inlets on both sides and the head of the machine casing, gradually cooling the hot ash on the stainless steel conveyor belt. After heat exchange between the cold air and the high-temperature slag, the air temperature rises to 300℃-400℃ before entering the furnace (equivalent to the boiler's hot secondary air inlet temperature), accounting for approximately 1% of the total boiler air volume. The slag temperature gradually decreases to around 150℃. The system structure is shown in the attached figure. Figure 1 As shown. However, in the application of a large number of dry ash removal systems, the cooling air volume required to maintain the normal operation of dry ash removal causes air leakage at the furnace bottom, which directly affects the rise in flue gas temperature. Given that the boiler ash volume is a difficult variable to monitor, and the dry ash removal machine is highly sensitive to the ash morphology, the actual cooling air volume (air leakage) often reaches 1.5% to 2.0%, and even exceeds 3.0% when handling defects.

[0003] Researchers' comparative measurements of dry ash removal systems with and without bottom air intake show that bottom air leakage in dry ash removal systems increases flue gas temperature by 3°C to 5°C. However, compared to wet ash removal systems, which use water cooling and have unsaturated water vapor in the flue gas, resulting in significant heat loss due to latent heat of vaporization and substantial heat loss from bottom ash and radiant heat from the furnace bottom, dry ash removal systems can recover most of the heat from the furnace bottom. Therefore, considering the overall flue gas loss, dry ash removal can still improve boiler thermal efficiency. Furthermore, under the same load, the larger the ash volume, the greater the positive impact of dry ash removal on boiler thermal efficiency. To further improve boiler thermal efficiency, the flue gas temperature needs to be reduced, requiring control of air volume and temperature. Other studies have shown that when the ash hopper cross-sectional temperature is above 250°C, boiler thermal efficiency can be improved by recovering ash heat; when the cross-sectional temperature is below 250°C, boiler thermal efficiency decreases due to the increased flue gas temperature.

[0004] Given the unknown and uncontrollable status of cooling air volume and ash volume of dry ash discharge machine in thermal power units, it is necessary to conduct correlation analysis on boiler operating conditions, ash discharge conditions, and cooling air volume of ash discharge machine, study online monitoring technology for air leakage rate of dry ash discharge machine and ash discharge image recognition technology, develop a real-time online air leakage and ash discharge monitoring system, monitor the operating status of dry ash discharge machine in real time, and reduce air leakage at the bottom of dry ash discharge machine. Summary of the Invention

[0005] Based on the above-mentioned technical defects, the present invention provides a dry slag discharge machine furnace bottom air leakage control system and control method, which solves the problems of high delay, untimely control, and poor air leakage control.

[0006] This invention provides a dry slag discharge machine furnace bottom air leakage control system, comprising, from its air inlet to the furnace bottom, an air inlet area, a conventional air leakage area, and a cooling air inlet area, wherein the cooling air inlet area is equipped with a linear airflow regulating gate; a temperature sensor located at the slag hopper position in the furnace to acquire the temperature of the air entering the furnace bottom; an image recognition processing system located at the slag hopper position in the furnace, wherein the image recognition processing system is used to acquire image information of the slag in the furnace in real time, the image information including the volume and shape of the slag; the image recognition processing system is used to calculate the amount of slag falling based on the volume and preset density of the slag; and a control system used to acquire the amount of slag falling, the shape and size of the slag, and the temperature of the air entering the furnace bottom in real time and adjust the airflow of the regulating gate in the air inlet area.

[0007] In one embodiment of the present invention, the image information further includes the shape and size of the slag; the image recognition processing system is used to determine whether the slag is large slag based on the shape and size of the slag and a preset threshold, that is, if the shape and size of the slag exceeds the preset threshold, the slag is large slag.

[0008] In one embodiment of the present invention, the control system is configured to receive a large slag signal, increase the air volume of the regulating valve in the air inlet area according to the large slag signal; calculate the average slag amount and the rate of change of the average slag amount in the current period compared to the average slag amount in the previous period according to a time period; increase or decrease the air volume of the regulating valve in the air inlet area whenever the rate of change of the average slag amount exceeds a preset value; and calculate the average temperature of the furnace air and the rate of change of the average temperature of the furnace air in the current period compared to the average temperature of the furnace air in the previous period according to a time period, and increase or decrease the air volume of the regulating valve in the air inlet area whenever the rate of change of the average temperature of the furnace air exceeds a preset value.

[0009] In one embodiment of the present invention, the control system is further configured to set the relationship between the amount of coal burned and the opening of the air inlet regulating door under normal conditions, and according to the relationship of the discontinuous function, increase or decrease the air volume of the air inlet regulating door under normal conditions.

[0010] In one embodiment of the present invention, the image recognition processing system includes a camera device for acquiring an image of the slag; and a computer for acquiring and processing the image of the slag transmitted by the camera device.

[0011] In one embodiment of the present invention, the camera device includes a sliding guide rail installed at the bottom of the furnace and extending from outside the furnace into the furnace; a high-temperature pinhole lens installed on the sliding guide rail; and a high-temperature resistant camera. The high-temperature pinhole lens can transmit the image of the slag inside the furnace to the high-temperature resistant camera through light reflection. The high-temperature resistant camera acquires the image information of the slag inside the furnace and converts it into a video signal for output to the computer.

[0012] The present invention also provides a control method for a dry slag discharge machine furnace bottom air leakage control system, comprising the following steps: real-time acquisition of image information of slag in the furnace and temperature of the furnace bottom air, wherein the image information includes the volume and shape of the slag; processing the image information, including calculating the current slag amount based on the volume and preset density of the slag; and adjusting the air volume of the regulating valve in the air inlet area based on the slag amount, the shape and size of the slag, and the temperature of the furnace bottom air.

[0013] In one embodiment of the present invention, the step of adjusting the air volume of the air inlet regulating door according to the shape and size of the slag includes determining whether the slag is large slag based on the shape and size of the slag and a preset threshold. That is, if the shape and size of the slag exceeds the preset threshold, the slag is considered large slag. If the slag is large slag, the air volume of the air inlet regulating door is increased.

[0014] In one embodiment of the present invention, the step of adjusting the air volume of the regulating gate in the air inlet area according to the slag amount includes calculating the average slag amount and the rate of change of the average slag amount of the current period compared with the average slag amount of the previous period according to a time period; when the rate of change of the average slag amount exceeds a preset value, the air volume of the regulating gate in the air inlet area is increased or decreased; the step of adjusting the air volume of the regulating gate in the air inlet area according to the temperature of the furnace bottom air includes calculating the average temperature of the furnace bottom air and the rate of change of the average temperature of the furnace bottom air compared with the average temperature of the furnace bottom air of the previous period according to a time period; when the rate of change of the average temperature of the furnace bottom air exceeds a preset value, the air volume of the regulating gate in the air inlet area is increased or decreased.

[0015] In one embodiment of the present invention, the control method of the dry slag discharge machine furnace bottom air leakage control system further includes the following steps: setting a non-continuous function relationship between the amount of coal burned under normal conditions and the opening of the air inlet area regulating door, and increasing or decreasing the air volume of the air inlet area regulating door under normal conditions according to the non-continuous function relationship.

[0016] Beneficial effects: The dry ash discharger furnace bottom air leakage control system and its control method of the present invention can timely grasp the air leakage situation of the dry ash discharger furnace bottom, laying the foundation for subsequent air leakage control; timely identify ash quantity and ash shape as feedforward for air leakage control; effectively control the air leakage of the dry ash discharger furnace bottom, reduce the air leakage of the dry ash discharger furnace bottom, improve boiler thermal efficiency, and reduce unit coal consumption. Attached Figure Description

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0018] Figure 1 This is a schematic diagram of the soot blowing system for dry slag discharge according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the camera device installed in the furnace according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the air intake device according to an embodiment of the present invention.

[0021] Figure 4 This is an external structural diagram of the linear airflow regulating door according to an embodiment of the present invention.

[0022] Figure 5 This is a structural diagram of the internal structure of the linear airflow regulating door according to an embodiment of the present invention, mainly showing the structure of the fixed baffle and the rotating baffle.

[0023] Figure 6 The image shows the waveform of the large slag signal output by the slag image recognition system under typical working conditions in an embodiment of the present invention.

[0024] The components include: 1. Slag discharge machine; 2. Slag hopper; 3. Furnace; 4. Air inlet device; 103. Air inlet area; 102. Conventional air leakage area of ​​dry slag machine; 101. Cooling air inlet area of ​​dry slag machine; 41. Air inlet duct; 42. Air inlet grille; 411. Front section of air inlet duct; 412. Rear section of air inlet duct; 51. Sliding guide rail; 52. High-temperature pinhole lens; 53. High-temperature resistant camera; 54. Temperature sensor; 6. Linear air volume regulating gate; 61. Fixed baffle; 62. Rotating baffle; 7. Air volume measuring device; 8. Computer. Detailed Implementation

[0025] 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.

[0026] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. It should be noted that if any directional indication (such as up, down, left, right, front, back, etc.) is involved in the embodiments of this invention, such directional indication is only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0027] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0028] like Figure 1 As shown, this embodiment provides a dry slag discharge machine furnace bottom air leakage control system, including an air inlet area, a conventional air leakage area, and a cooling air inlet area 101 of the dry slag discharge machine, which are arranged sequentially from the air inlet to the furnace bottom. The cooling air inlet area 101 is equipped with a linear air volume regulating gate. A temperature sensor 54 is located at the slag hopper position in the furnace to obtain the temperature of the air entering the furnace bottom. An image recognition processing system is located at the slag hopper position in the furnace. The image recognition processing system is used to collect image information of the slag in the furnace in real time. The image information includes the volume and shape of the slag. The image recognition processing system is used to calculate the amount of slag falling based on the volume and preset density of the slag. A control system is used to obtain the amount of slag falling, the shape and size of the slag, and the temperature of the air entering the furnace bottom in real time and adjust the air volume of the regulating gate in the air inlet area.

[0029] like Figure 1 As shown, Figure 1 This is a structural diagram of a dry ash discharger 1, mainly showing the distribution of air leakage areas. The air leakage areas are the air inlet area 103, the conventional air leakage area 102, and the cooling air inlet area 101. During normal boiler operation, hot ash falling from the cold ash hopper is conveyed to the stainless steel conveyor belt of the dry ash discharger 1 via the bottom ash discharge device. Cooling air enters the interior of the dry ash discharger 1 through both sides of the casing (conventional air leakage area 102) and the adjustable air inlet at the head (air inlet area 103), gradually cooling the hot ash on the stainless steel conveyor belt. After heat exchange between the cold air and the high-temperature slag, the air enters the furnace 3. The cooling air accounts for approximately 1% of the total boiler air volume. Therefore, this embodiment provides a bottom air leakage monitoring system for a dry ash discharger, including the dry ash discharger 1 and a monitoring controller. The dry slag discharge machine 1 includes, from its air inlet to the furnace bottom, an air inlet area 103, a conventional air leakage area 102, and a cooling air outlet area 101.

[0030] like Figure 2As shown, the air inlet area 103 is equipped with an air inlet device 4 and an air volume measuring device 7 installed inside the air inlet device 4. The air inlet device 4 includes an air inlet duct 41, the rear section 412 of which is installed to the dry slag discharge machine 1. The air volume measuring device 7 is installed on the air inlet duct 41. The air inlet area 103 is designed for real-time monitoring of the cooling airflow rate of the dry slag discharge machine, requiring online monitoring of the inlet airflow of the electric cooling damper at the head of the dry slag discharge machine. The original site layout of the electric cooling damper was close to the air inlet and bend, making it difficult to install online air volume measuring elements. A dual-duct air inlet grille type online air volume measuring device was designed, such as... Figure 2 As shown, the air duct is extended at the air inlet, and a gradually narrowing and widening air duct section is set up. That is, the opening of the front section 411 of the air inlet duct gradually decreases from front to back, which increases the differential pressure amplification factor and improves the accuracy of air volume measurement. At the same time, the front section 411 of the air inlet duct is equipped with an air intake grille to rectify the flow field upstream of the air measuring element. The multi-point back-to-back pipe measuring points are connected in pairs to achieve a completely equidistant connection, minimizing the measurement error introduced by the pressure transmission pipeline.

[0031] like Figure 3 As shown, the cooling air vent area 101 of the dry slag machine is equipped with a linear air volume regulating gate 6. The cold air volume of the cooling air vent area 101 of the dry slag machine is a first air volume, and the first air volume is linearly related to the opening degree of the linear air volume regulating gate 6. Figure 4 As shown, the linear airflow regulating gate 6 in this embodiment includes at least one fixed baffle 61 (two sets in this embodiment, one set consisting of two fixed baffles 61) and at least one rotating baffle (two sets in this embodiment, one set consisting of one rotating baffle 62). The fixed baffles 61 are fixed inside the air duct of the cooling air outlet area 101 of the dry slag machine; the rotating baffle 62 extends into the air duct of the cooling air outlet area 101 of the dry slag machine through a transmission mechanism. The deviation between the opening ratio and the flow ratio of the linear airflow regulating gate 6 and the first airflow is within 5%. The structural design method and structure of the linear airflow regulating gate 6 can refer to existing design points. The focus of this embodiment is to provide an example to explain the linear relationship between the opening of the linear damper and the cold airflow. As shown in Table 1 below, Table 1 shows the flow characteristics of commonly used airflow regulating gates in coal-fired power plants. In actual use, when the baffle is adjusted in the first half of its stroke, the change in airflow area is significantly lower than the change in the baffle opening, resulting in a smaller change in air volume and poor linearity. This often leads to poor automatic control adjustment quality, poor lag in air volume adjustment in the first half of the stroke, and over-adjustment is likely to occur in the second half of the stroke.

[0032] Among them, the air volume of commonly used single-baffle air volume regulating dampers and double-baffle (reverse) air volume regulating dampers changes slowly within the opening range of 0 to 50%. When the damper opening is 50%, the flow rate percentage is only 26%. In contrast, the flow rate of double-baffle (same direction) air volume regulating dampers is linearly improved. When the damper opening is 50%, the flow rate percentage is 39%, as shown in Table 1.

[0033] Table 1 Flow characteristics of commonly used air volume regulating valves in coal-fired power plants

[0034]

[0035] To more accurately determine the air intake volume of the small cooling air inlets on both sides of the dry slag machine casing, this project developed a linear damper. Through a special damper baffle structure design, the flow regulation linearity of the air volume regulating damper is improved.

[0036] After repeated structural dimension optimization designs, the numerical simulation results of the optimized flow characteristics are shown in Table 2. It can be seen that the optimized irregular linear damper has good flow linearity, and the opening percentage and flow percentage are relatively consistent, with a deviation within 5 percentage points.

[0037] Table 2. Flow Characteristics of Linear Air Volume Adjustment Gates for Small Cooling Air Vents on Both Sides of Dry Slag Machine Casing

[0038]

[0039] The emergency slag discharge port at the tail of the dry slag discharge machine should be tightly sealed during non-emergency slag discharge. Air leakage at this location (the normal air leakage area 102 of the dry slag discharge machine) is significant, and the leaked air directly enters the furnace 3, resulting in minimal heat exchange with the slag and a substantial impact on boiler economics. Air leakage is typically found at the maintenance doors of the emergency slag discharge ports at the tail and head of the dry slag discharge machine.

[0040] To enhance the sealing of the emergency slag discharge port inspection doors at the tail and head of the dry slag discharge machine, a flexible, high-temperature resistant sealant is thickly brushed along the edges of the inspection doors and inspection holes. After solidification, it forms a chamfered sealing strip that tightly adheres to the edges of the inspection doors and inspection holes, ensuring a good seal for the inspection doors at the tail and head of the dry slag discharge machine without affecting the daily opening and closing of the doors. This treatment minimizes the proportion of air leakage in the dry slag discharge machine that cannot be quantified and controlled. After the modification, the cold air volume in the conventional air leakage zone 102 of the dry slag discharge machine is the second air volume, which is a test-determined value. That is, the change in the cold air volume in the conventional air leakage zone 102 of the modified dry slag discharge machine is very small and negligible, generally a fixed value, which can be obtained through experimentation.

[0041] The image recognition processing system includes a camera device and a computer 8. The camera device is used to acquire images of the slag; the computer 8 is used to acquire and process the images of the slag transmitted by the camera device. The image recognition processing system is located at the slag hopper 2 in the furnace 3. The image recognition processing system is used to collect image information of the slag inside the furnace 3 in real time. The image information includes the volume and shape / size of the slag. The image recognition processing system is used to calculate the amount of slag falling based on the volume and preset density of the slag. The image recognition processing system is used to determine whether the slag is large slag based on its shape / size and a preset threshold; that is, if the shape / size of the slag exceeds the preset threshold, the slag is considered large slag.

[0042] Appendix Figure 1 This is a schematic diagram of a dry ash removal system provided in this embodiment. After soot blowing in the furnace 3, 80%–90% of the ash detached from the heating surface tube wall will be carried away by the flue gas as fly ash, and 10%–20% of the ash will fall to the bottom of the boiler as slag. The output of the dry ash removal system in this example is designed to be no less than the maximum slag production under the boiler's BMCR conditions, with a design margin of approximately 200% or more. The normal output of the dry ash removal system is 7t / h–15t / h, and the maximum output is 40t / h. It can operate continuously. The ash removal machine 1 (air-cooled) in the ash removal system has an inclined section with an angle of 30°. The ash removal machine 1 is connected to the boiler ash outlet via a slag well, which is independently supported. The volume of the slag well can at least meet the slag production of the boiler under 4-hour slag production conditions for the verification coal type 2 (maximum slag production coal type). The bottom of the slag well is equipped with a hydraulic shut-off valve, allowing the dry ash removal machine 1 to be shut down for 4 hours in case of failure without affecting the safe operation of the boiler. Each boiler is equipped with one 80t / h slag crusher and one steel slag bin with a diameter of Ф8m and an effective volume of not less than 250m³. 3 It can store at least 35 hours' worth of slag for the designed coal type when the boiler is at full load (approximately 20 hours for check coal type 1 and approximately 17 hours for check coal type 2). An operating room is located 2.5m above the slag bin. The bottom of the slag bin has two discharge outlets, each equipped with a manual gate, a manual flow regulating gate, a pneumatic gate, and a discharge pipe for direct loading and transport to the comprehensive utilization user. In this embodiment, there are three cold slag hoppers 2, installed at the slag well. Figure 5 As shown, the camera device in this embodiment includes a sliding guide rail 51, a high-temperature pinhole lens 52, a high-temperature resistant camera 53, and a temperature sensor 54. The sliding guide rail 51 is installed at the bottom of the furnace 3 and extends from the outside of the furnace 3 into the furnace 3; the high-temperature pinhole lens 52 is installed on the sliding guide rail 51; the high-temperature pinhole lens 52 can transmit the image of the slag inside the furnace 3 to the high-temperature resistant camera 53 through light reflection, and the high-temperature resistant camera 53 acquires the image information of the slag inside the furnace 3 and converts it into a video signal for output to the computer 8.

[0043] In this embodiment, the high-temperature resistant camera 53 is a SEU-F5C starlight-level high-temperature resistant air-cooled cylindrical network camera, used for monitoring the slag falling from the slag hopper 2. This high-temperature resistant camera 53 is made of a double-layer stainless steel cylinder, possessing high corrosion resistance and capable of use in environments with high temperature, dust, and strong corrosive gases. All wiring is located in the rear cover plate. Cooling compressed air passes through the interlayer to cool the camera and lens installed in the inner layer, achieving the purpose of temperature reduction. A spiral air curtain is formed at the front of the device to prevent dust and blow away heat radiation. Each high-temperature resistant camera 53 uses a double-layer stainless steel cylinder to form a protective shell, with gaps for ventilation and cooling. The front viewing window is 5mm thick and made of tempered glass, allowing light to pass through, enabling the camera's internal components to acquire images while protected. The total weight is 8kg. The rear of the shell has two cable outlet holes, M20×1.5, for signal and power cable connections. After installation in the corresponding positions, a protective shell is added to the entire device.

[0044] The protective shells are all made of stainless steel, and their size is adapted to the site conditions. Their main function is to protect the equipment from external impacts and the effects of routine power plant flushing, ensuring the safe and stable operation of the equipment. The specific structure of the high-temperature resistant camera 53 can also refer to existing structural designs and is not a key point of this invention, therefore it will not be described in detail.

[0045] The high-temperature resistant camera 53 operates within a temperature range of -20℃ to 50℃. To improve its applicability in field applications and prevent overheating of the dry ash discharge machine 1 under high boiler loads, a cooling system was added. The cooling air source is compressed air from the power plant. To ensure safe equipment operation and prevent corrosion from oil and water in the compressed air, the compressed air must be filtered before entering the cooling system. Therefore, an oil-water separator was added to filter the air.

[0046] Cooling requires compressed air with a pressure of not less than 0.4 MPa to be supplied from the power plant's compressed air pipe to the oil-water separator. After passing through the oil-water separator's pressure control valve and filter, the gas pressure is adjusted between 0.1 MPa and 0.4 MPa before entering the equipment's protective casing through the air inlet for cooling. After cooling, the gas forms a spiral air curtain at the front of the equipment, serving to prevent dust and remove heat radiation. Considering seasonal temperature variations, to ensure safe and stable operation of the equipment, the supply air pressure must be greater than 0.3 MPa when the ambient temperature is above 32℃; greater than 0.2 MPa when the ambient temperature is above 25℃; and greater than 0.1 MPa when the ambient temperature is below 25℃. The temperature sensor 54 is located at the lens of the high-temperature resistant camera 53.

[0047] The high-temperature pinhole lens 52 transmits the image inside the furnace to the outside and focuses it onto the target surface of the high-temperature resistant camera 53. The high-temperature resistant camera 53 converts the color image into a video signal and transmits the video signal via a coaxial cable. Since this case mainly monitors the size of the slag inside the furnace and obtains the slag volume based on multiple images of the slag from different angles, the amount of slag falling can be calculated based on the slag density. In processing the image information, the high-temperature resistant camera 53 converts the acquired image information into a digital image signal through an A / D (analog-to-digital) converter, then sends it to a digital signal processing chip (DSP) for video encoding and compression, and then transmits it via a network cable. The backend can directly access and decode the video via a computer or display it through a decoding device, as shown in the attached diagram. Figure 6 As shown.

[0048] Appendix Figure 6 This is the large slag signal output by the slag falling image recognition system under typical operating conditions. Under these conditions, the large slag signal occurs frequently, and on-site observation confirms that large pieces of slag are frequently falling from the three slag hoppers. The large slag signal output by the slag falling image recognition system enables rapid identification of large slag falling from the boiler.

[0049] The existing automatic control logic for the electric cooling damper at the head of the dry slag discharger only uses PID logic to automatically control the damper based on the set and measured values ​​of the slag inlet temperature. However, because this temperature measurement point lags significantly (approximately 20 minutes) compared to the actual control parameters such as the amount and type of slag at the bottom of the furnace, the adjustment of the electric cooling damper in the cooling vent area 101 of the dry slag discharger cannot function when the bottom slag reaches the slag bin inlet.

[0050] To enable the cooling airflow of the dry slag discharger to be adjusted as needed and to respond promptly to special situations such as high slag volume or large slag, this invention integrates real-time online monitoring of cooling airflow rate, slag volume, and slag shape, further optimizing the operation of the dry slag discharger and the adjustment of the cooling dampers, thus achieving automatic control of the electric cooling dampers in the cooling air outlet area 101 of the dry slag discharger. Based on different control objectives, the control logic of the electric cooling dampers in the cooling air outlet area 101 of the dry slag discharger is divided into three parts, as shown in Table 3.

[0051] 1) Basic setting of damper opening: This refers to the initial setting curve of the damper opening. Using the boiler load (coal consumption) as the control signal, it provides the opening response curve of the cooling damper under different boiler loads. This serves as the primary control loop for the cooling damper, fully utilizing the adjustment capability of the electric cooling damper under different loads, especially minimizing the cooling air consumption under medium and low loads, thus improving the boiler's operating economy. Simultaneously, under normal operating conditions, it can maintain the cooling air volume near the optimal air volume, avoiding pulsating adjustments and reducing overshoot and undershoot.

[0052] 2) Optimization of basic damper settings: This refers to the optimization of the initial damper opening setting. Based on the comparison of the feedback value and the measured value of the slag temperature at the head slag bin inlet, the damper opening setting logic is optimized. This part serves as a supplement to the overall control logic to prevent excessive changes in slag dropping characteristics after significant changes in coal quality, and to prevent insufficient adjustment effects of the primary control loop and feedforward optimization bias module.

[0053] 3) Damper opening offset optimization: A feedforward optimization offset module is added to adjust the cooling damper setpoint in real time based on the large slag signal, the rate of change of slag discharge, and the rate of change of furnace bottom inlet air temperature. In situations such as large slag falling, excessively rapid slag increase, or excessively high furnace bottom inlet air temperature rise rate, the module can respond quickly by increasing the electric damper offset to increase the airflow and achieve rapid cooling. Conversely, when the corresponding damper opening conditions disappear, the increased damper offset is removed to reduce the impact of cooling airflow on the boiler.

[0054] Taking a dry ash removal machine in a power plant as an example, the damper in the cooling air inlet area 101 of the dry ash removal machine was modified to a linear damper. Simultaneously, an airflow measurement device and ash discharge quantity and shape measurement equipment were added to the electric damper. The head damper control strategy is shown in Table 3. Under rated load, with the head cooling damper closed, the total cooling airflow is 12.0 t / h, the total air volume is 2076.0 t / h, and the dry ash removal machine cooling air ratio is 0.58%. With the head cooling damper fully open, the total cooling airflow is 16.2 t / h, the total air volume is 2068.0 t / h, and the dry ash removal machine cooling air ratio is 0.78%. Compared with the original cooling air ratio of 1.13%–1.24%, the average cooling air ratio of the dry ash removal machine decreased by 42.9%, the flue gas temperature increased by 3.6℃, ​​and coal consumption decreased by approximately 1.0 g / kWh.

[0055] Table 3 Closed-loop control strategy for the head damper

[0056]

[0057]

[0058] The present invention also provides a control method for a dry ash discharge machine furnace bottom air leakage control system, comprising the following steps:

[0059] The image information of the slag inside the furnace and the temperature of the air entering the furnace bottom are collected in real time. The image information includes the volume and shape of the slag.

[0060] Processing the image information includes calculating the current slag amount based on the volume of the slag and the preset density of the slag.

[0061] The airflow of the regulating valve in the air inlet area is adjusted based on the amount of slag, the shape and size of the slag, and the temperature of the air entering the furnace from the bottom. The step of adjusting the airflow of the regulating valve in the air inlet area based on the shape and size of the slag includes determining whether the slag is large slag based on a preset threshold for the shape and size of the slag. That is, if the shape and size of the slag exceeds the preset threshold, the slag is considered large slag. If the slag is large slag, the airflow of the regulating valve in the air inlet area is increased. The step of adjusting the airflow of the regulating valve in the air inlet area according to the slag amount includes calculating the average slag amount over a time period and the rate of change of the average slag amount of the current period compared to the average slag amount of the previous period; when the rate of change of the average slag amount exceeds a preset value, the airflow of the regulating valve in the air inlet area is increased or decreased; the step of adjusting the airflow of the regulating valve in the air inlet area according to the temperature of the furnace bottom air includes calculating the average temperature of the furnace bottom air over a time period and the rate of change of the average temperature of the furnace bottom air over a time period compared to the average temperature of the furnace bottom air over a time period; when the rate of change of the average temperature of the furnace bottom air exceeds a preset value, the airflow of the regulating valve in the air inlet area is increased or decreased.

[0062] The control method of the dry slag discharge machine furnace bottom air leakage control system further includes the following steps: setting the relationship between the amount of coal burned under normal conditions and the opening of the air inlet area regulating door as a discontinuous function, and increasing or decreasing the air volume of the air inlet area regulating door under normal conditions based on the relationship of the discontinuous function.

[0063] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A dry ash discharge machine furnace bottom air leakage control system, characterized in that, include: The dry slag discharge machine includes, from its air inlet to the furnace bottom, an air inlet area, a conventional air leakage area of ​​the dry slag machine, and a cooling air outlet area of ​​the dry slag machine. The cooling air outlet area of ​​the dry slag machine is equipped with a linear air volume regulating gate. A temperature sensor, located in the slag hopper of the furnace, is used to obtain the temperature of the air entering the furnace from the bottom. An image recognition and processing system is located in the slag hopper of the furnace. The image recognition and processing system is used to acquire image information of the slag in the furnace in real time. The image information includes the volume and shape of the slag. The image recognition and processing system is used to calculate the amount of slag falling based on the volume of the slag and the preset density of the slag. The control system is used to acquire the amount of slag falling, the shape and size of the slag, the temperature of the air entering the furnace bottom, and adjust the air volume of the regulating valve in the air inlet area in real time. The image information also includes the shape and size of the slag; the image recognition processing system is used to determine whether the slag is large slag based on the shape and size of the slag and a preset threshold, that is, if the shape and size of the slag exceeds the preset threshold, the slag is large slag. The control system is used to receive large slag signals and increase the air volume of the regulating door in the air inlet area according to the large slag signals. The average amount of slag falling is calculated according to the time period, as well as the rate of change of the average amount of slag falling in the current period compared to the average amount of slag falling in the previous period; when the rate of change of the average amount of slag falling exceeds a preset value, the air volume of the regulating damper in the air inlet area is increased or decreased; and The average temperature of the furnace air is calculated according to the time period, and the rate of change of the average temperature of the furnace air in the current period compared with the average temperature of the furnace air in the previous period is calculated. When the rate of change of the average temperature of the furnace air exceeds the preset value, the air volume of the regulating damper in the air inlet area is increased or decreased. The control system is also used to set the relationship between the amount of coal burned and the opening of the regulating door in the air inlet area under normal conditions as a discontinuous function. Based on this discontinuous function relationship, the air volume of the regulating door in the air inlet area is increased or decreased under normal conditions. The image recognition processing system includes: A camera device for acquiring an image of the slag; and A computer is used to acquire and process images of the slag transmitted by the camera device; The camera device includes: A sliding guide rail is installed at the bottom of the furnace chamber and extends from outside the furnace chamber into the furnace chamber; High-temperature pinhole lens, mounted on a sliding guide rail; A high-temperature resistant camera, wherein the high-temperature pinhole lens can transmit the image of slag inside the furnace to the high-temperature resistant camera through light reflection, and the high-temperature resistant camera acquires the image information of the slag inside the furnace and converts it into a video signal for output to the computer; The cold air volume in the cooling air outlet area of ​​the dry slag machine is the first air volume. The first air volume is linearly related to the opening of the linear air volume regulating damper. The opening percentage and the flow rate percentage are relatively consistent, with a deviation within 5 percentage points. The control method of the dry ash discharge machine furnace bottom air leakage control system includes the following steps: Real-time acquisition of image information of slag inside the furnace and temperature of air entering the furnace bottom; the image information includes the volume and shape of the slag. Processing the image information includes calculating the current amount of slag falling based on the volume of the slag and the preset density of the slag; Adjust the airflow of the regulating valve in the air inlet area according to the amount of slag, the shape and size of the slag, and the temperature of the air entering the furnace from the bottom of the furnace; The step of adjusting the airflow of the air inlet regulating door according to the shape and size of the slag includes: determining whether the slag is large slag based on the shape and size of the slag and a preset threshold. That is, if the shape and size of the slag exceeds the preset threshold, the slag is large slag. If the slag is large slag, the airflow of the air inlet regulating door is increased. The steps for adjusting the airflow of the regulating damper in the air inlet area based on the amount of slag falling include: The average amount of slag falling is calculated according to the time period, as well as the rate of change of the average amount of slag falling in the current period compared to the average amount of slag falling in the previous period; when the rate of change of the average amount of slag falling exceeds the preset value, the air volume of the regulating door in the air inlet area is increased or decreased. The step of adjusting the air volume of the regulating valve in the air inlet area according to the temperature of the air entering the furnace bottom includes calculating the average temperature of the air entering the furnace according to the time period and the rate of change of the average temperature of the air entering the furnace in the current period compared with the average temperature of the air entering the furnace in the previous period. When the rate of change of the average temperature of the air entering the furnace exceeds a preset value, the air volume of the regulating valve in the air inlet area is increased or decreased. It also includes the following steps: setting a non-continuous function relationship between the amount of coal burned under normal conditions and the opening of the regulating door in the air inlet area, and increasing or decreasing the air volume of the regulating door in the air inlet area under normal conditions based on this non-continuous function relationship.

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