Fan-shaped plate lifting system of boiler air preheater

Abstract

The invention discloses a fan-shaped plate lifting system of a boiler air preheater, and relates to the field of technical gap lifting. The laser gap control subsystem is used for collecting a gap signal value between a sector plate and a rotor flange surface; the temperature control subsystem is used for collecting the temperature of a flue gas outlet; the lifting interval presetting subsystem is used for presetting a plurality of lifting intervals according to a set value; the direct lifting control subsystem is used for determining a direct lifting control strategy according to the relation between the current gap signal value and the lifting interval; the indirect lifting control subsystem is used for determining an indirect lifting control strategy according to the flue gas outlet temperature when the laser gap control subsystem fails; and the execution control subsystem is used for controlling the sector plate to lift according to the direct lifting control strategy / indirect lifting control strategy so as to adjust the sealing gap. And through introducing a multi-parameter fusion feedback mechanism, fine control is realized.

Description

Technical Field

[0001] The invention relates to the technical field of gap lifting, in particular to a boiler air preheater sector plate lifting system. Background Art

[0002] In actual operation, rotary air preheaters commonly experience high air leakage rates due to their structural characteristics and high-temperature operating environments. Some units even experience leakage rates exceeding 15%, far exceeding the design value. The primary source of leakage is the sealing gap between the sector plates and the rotor, a gap whose fluctuations are affected by a variety of factors. During normal hot operation, the rotor of an air preheater filled with thermal storage elements experiences high temperatures and large radial expansion at the hot end due to internal heat exchange. Conversely, the cold end experiences low temperatures and small radial expansion. Furthermore, upward expansion of the central axis causes greater expansion at the hot end, shifting the center upward and reducing the outer edges. Combined with the effect of deadweight droop, this causes the rotor to exhibit a so-called "mushroom-like" deformation. This deformation increases the clearance in some areas (such as the outer side of the hot end) while decreasing it in others (such as the outer side of the cold end). If left uncorrected, this dynamic variation can lead to significant gas leakage and potentially severe friction between the rotor and mounting components, and in extreme cases, even to seizure. Therefore, the design intention of the fan plate is to compensate for the gap change caused by the lowering of the rotor. It is lowered under normal working conditions and can be raised in emergency conditions to monitor the status of the rotor and ensure that the appropriate gap is maintained between the parachute plate and the rotor.

[0003] However, traditional control systems typically rely on a single gap signal for regulation and lack a dynamic response mechanism to comprehensive factors such as temperature and deformation, making it difficult to achieve accurate and timely sealing control. When a sensor fails, these systems often lack effective backup strategies, leading to control failure or improper adjustment. These problems not only reduce the boiler's thermal efficiency and increase fan energy consumption, but also affect combustion stability, exacerbate equipment corrosion and dust accumulation, and in severe cases, even threaten the safe operation of the entire unit. Therefore, it is particularly important to improve the sealing control mechanism of existing systems and enhance their ability to cope with complex operating conditions. Summary of the Invention

[0004] The object of the present invention is to provide a boiler air preheater sector plate lifting system to solve the problem of difficulty in achieving accurate and timely sealing control.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a boiler air preheater sector plate lifting system, comprising the following modules: The laser gap control subsystem is installed on the air preheater sector plate and is used to collect the gap signal value between the sector plate and the rotor flange surface; Temperature control subsystem, used to collect flue gas outlet temperature; The boost interval preset subsystem is used to preset a number of boost intervals according to set values; A direct lifting control subsystem is connected to the lifting interval preset subsystem and is used to determine a direct lifting control strategy according to the relationship between the current gap signal value and the lifting interval; The indirect lifting control subsystem is connected to the laser gap control subsystem and the temperature control subsystem. When the laser gap control subsystem fails, the indirect lifting control strategy is determined according to the flue gas outlet temperature. The execution control subsystem is used to control the lifting of the sector plate to adjust the sealing gap according to the direct lifting control strategy / indirect lifting control strategy.

[0006] In another embodiment, the boost interval includes: a first boost interval, a second boost interval, a third boost interval and a fourth boost interval.

[0007] In another embodiment, the gap signal value range less than 70% of the set value is used as the first boost interval, the gap signal value range greater than or equal to 70% of the set value and less than or equal to 110% of the set value is used as the second boost interval, the gap signal value range greater than 110% of the set value and less than or equal to 140% of the set value is used as the third boost interval, and the gap signal value range greater than 140% of the set value is used as the fourth boost interval; the size relationship of the boost step lengths of the first boost interval, the second boost interval, the third boost interval and the fourth boost interval is: the boost step length of the first boost interval < the boost step length of the second boost interval < the boost step length of the third boost interval < the boost step length of the fourth boost interval.

[0008] In another embodiment, if the current gap signal value is in the first boost interval, no boost is performed; if the current gap signal value is in the second boost interval, the first direct boost control scheme is executed; if the current gap signal value is in the third boost interval, the second direct boost control scheme is executed; if the current gap signal value is in the fourth boost interval, the third direct boost control scheme is executed.

[0009] In another embodiment, when the gap signal value is currently in the second boost range, a first direct boost control scheme is executed, including: Sampling the current gap signal value three times continuously, determining whether the three consecutive sampled current gap signal values ​​are all in the second boosting interval, and if not, determining a first direct boosting sub-step length according to the latest sampled current gap signal value; If so, determining an average gap signal value based on the current gap signal values ​​sampled three times in succession, determining a first difference between the average gap signal value and a set value, and if the first difference is less than or equal to 2 mm, not performing the lifting; If the first difference is greater than 2 mm, preset an initial lifting step length and a reference deformation height of the rotor top, and design the following judgment conditions: The flue gas outlet temperature fluctuation range within the historical time window is greater than 5°C; The deformation height of the rotor top within the historical time window is ≥ 10% of the reference deformation height of the rotor top; If any of the above judgment conditions is met, the first direct lifting step length is determined based on the flue gas outlet temperature fluctuation amplitude, the rotor top deformation height and the initial lifting step length; if all of the above judgment conditions are not met, the initial lifting step length is used as the first direct lifting step length.

[0010] In another embodiment, when the gap signal value is currently in the third boost range, a second direct boost control scheme is executed, including: determining an initial gap signal value; Based on the current gap signal value, a new gap signal value is obtained every 10 seconds; if two consecutive new gap signal values ​​are greater than the initial gap signal value, the frequency of obtaining the new gap signal value is adjusted to 5 seconds; Determine a second difference between each new gap signal value and the set value; if the second difference is less than 2.5 mm, do not perform lifting; if the second difference is greater than or equal to 2.5 mm and less than 3.5 mm, use the initial lifting step length as the second direct lifting step length; if the second difference is greater than or equal to 3.5 mm, correct the initial lifting step length based on the second difference to obtain a corrected value, and use the corrected value as the second direct lifting step length; Each new gap signal value is adjusted by the second direct improvement step to obtain an adjusted gap signal value, and the improvement is stopped when the adjusted gap signal value improves to the second improvement interval or reaches a preset maximum improvement number.

[0011] In another embodiment, when the gap signal value is currently in the fourth boost interval, a third direct boost control scheme is executed, including: Determine whether the current gap signal value is in the fourth lifting interval and lasts for 5 minutes. If so, enter the emergency lifting mode; if not, execute the second direct lifting control scheme; In emergency lifting mode, the following disturbance conditions are designed: The fluctuating amplitude of flue gas outlet temperature in the historical time window is greater than 8°C; The deformation height of the rotor top within the historical time window is ≥ 15% of the reference deformation height of the rotor top; If any of the above disturbance conditions is met, the flue gas outlet temperature fluctuation amplitude is obtained in real time. According to the flue gas outlet temperature fluctuation amplitude and the deformation height of the rotor top, the dynamic boost step size is determined and the boost is performed. If none of the above disturbance conditions is met, the initial boost step size is used as the third direct boost step size and the boost is performed. After each action, the flue gas outlet temperature is obtained in real time. If the current flue gas outlet temperature is within the first target temperature range, the fan plate is raised by 10mm; if the flue gas outlet temperature is within the second target temperature range, the fan plate is further raised by 5mm. The lifting operation is continuously performed until the current gap value is lower than 140% of the set value, and this round of rapid and continuous lifting control is completed.

[0012] In another embodiment, when the gap signal value is 0, an indirect improvement control strategy is determined according to the flue gas outlet temperature, including: judging whether the laser gap control subsystem failure is the first failure, if so, starting the basic improvement plan; if not, starting the intelligent enhanced improvement plan.

[0013] In another embodiment, the basic improvement plan is specifically: When the laser gap control subsystem fails for the first time, determine the historical temperature reference value of the flue gas outlet and obtain the real-time temperature of the flue gas outlet at the current moment; Determine the flue gas outlet temperature deviation based on the historical flue gas outlet temperature reference value and the real-time flue gas outlet temperature; If the flue gas outlet temperature deviation is greater than 5°C, the rotary air preheater is judged to have abnormal air leakage; lift the fan plate by 5mm, wait for 5 minutes after the lifting is completed, and then re-judge whether the rotary air preheater has abnormal air leakage and whether it needs to be lifted; stop lifting when the cumulative lifting amount reaches 15% of the initial gap signal value.

[0014] In another embodiment, the intelligent enhancement solution is specifically as follows: At least two trigger threshold intervals are preset: a first-level trigger threshold interval and a second-level trigger threshold interval, wherein the first-level trigger threshold interval is smaller than the second-level trigger threshold interval; each trigger threshold interval includes an increase step size and a trigger time interval; Determine whether the current flue gas outlet temperature deviation belongs to the first-level trigger threshold interval or the second-level trigger threshold interval, perform a lifting operation on the fan plate according to the lifting step size under the trigger threshold interval, and wait for the trigger time interval, then re-determine the current flue gas outlet temperature deviation and perform the lifting operation until the re-determined current flue gas outlet temperature deviation is less than the first-level trigger threshold interval and remains unchanged for 10 minutes, stop performing the lifting operation, and maintain the current gap state.

[0015] The technical effects and advantages of the present invention are as follows: The boiler air preheater fan plate lifting system provided by the present invention realizes refined and adaptive control of the fan plate sealing gap by introducing a multi-parameter fusion feedback mechanism of the laser gap control subsystem and the temperature control subsystem, combined with a graded lifting interval and a dynamic adjustment strategy. The system automatically divides the control level according to the real-time gap signal and temperature change state, and uses different lifting steps and response frequencies for adjustment. When the laser sensor fails, it switches to an indirect control strategy based on temperature deviation to ensure control continuity and reliability. This solution effectively responds to the gap changes caused by thermal deformation of the rotor, significantly reduces the air leakage rate, improves the boiler combustion efficiency and the unit operation economy, while reducing equipment wear and energy consumption, extending the service life of the equipment, and has good engineering application value and promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A structural block diagram of the boiler air preheater sector plate lifting system provided in this embodiment; Figure 2 A schematic diagram of the sector plate lifting direction of the boiler air preheater sector plate lifting system provided in this embodiment; Figure 3 A schematic structural diagram of the sector plate lifting mechanism of the boiler air preheater sector plate lifting system provided in this embodiment; Figure 4 A side view of the sector plate lifting mechanism of the boiler air preheater sector plate lifting system provided in this embodiment.

[0017] Figure markings: 1-fan plate, 2-lifting mechanism frame, 3-worm gear hoist, 4-dual motor reducer, 5-main motor, 6-auxiliary motor, 7-displacement control box, 8-crossbeam, 9-coupling, 10-speed measuring wheel, 11-protective cover, 12-displacement pointer, 13-connecting plate, 14-lifting scale, 15-handwheel, 16-I-beam, 17-side plate, 18-synchronizing shaft, 19-linear speed device, 20-large pin shaft, 21-upper connecting rod, 22-adjusting nut, 23-lower connecting rod, 24-connecting rod flange, 25-upper flange, 26-bellows, 27-lower flange, 28-sealing seat, 29-small pin shaft, 30-fan plate connecting rod, 31-axial sealing device. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings to clarify the technical solutions in the embodiments of the present invention; although it is clear that the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] like Figure 1As shown, this embodiment discloses a boiler air preheater sector plate lifting system, including the following modules: The laser gap control subsystem is installed on the fan plate of the air preheater and is used to collect the gap signal value between the fan plate and the rotor flange surface.

[0020] In the prior art, the axial seal 31 of a boiler air preheater is fixedly connected via the rotor flange and positioned between the upper and lower sector plates, forming a dynamic sealing surface to reduce air leakage between the rotor and stator. When the equipment is operating, the rotor drives this structure to rotate while the sector plates remain relatively stationary. The size of this sealing gap is controlled by adjusting the position of the sector plates. To accurately monitor the sealing gap, this embodiment installs a laser gap control subsystem at multiple locations on the upper and lower sealing plates. The laser gap control subsystem is preferably a laser gap sensor that collects the gap signal value between the sector plates and the rotor flange.

[0021] In another embodiment, in order to accurately monitor the sealing gap between the boiler air preheater sector plate and the rotor flange surface, and convert this physical distance information into a processable electrical signal. Conversion process: First, based on a pre-set linear mapping relationship, for example, the minimum detection gap of 1mm corresponds to a 4mA current output, and the maximum detection gap of 5mm (may be larger) corresponds to a 20mA current output. Assuming that the actual gap measured at a certain moment is 3.5mm, the corresponding current signal calculated according to this linear relationship should be 14mA (calculation method: each millimeter of gap change causes a current change of 4mA / mm, so 3.5mm-1mm=2.5mm, 2.5mm 4mA / mm + 4mA = 14mA). This conversion not only facilitates long-distance transmission and enhances anti-electromagnetic interference capabilities, but also enables control systems such as PLCs to directly read and process these standardized current signals, thereby achieving precise adjustment of the sector plate position.

[0022] The temperature control subsystem is used to collect the flue gas outlet temperature.

[0023] The flue gas outlet temperature sensor is installed inside or immediately adjacent to the air preheater flue gas outlet duct. To accurately measure the flue gas outlet temperature, the sensor should be installed directly in the flue gas flow path, avoiding dead ends or areas with poor flue gas flow. The ideal installation point is in the center of the flue gas duct, ensuring that the actual flue gas temperature is measured, rather than the temperature affected by local cooling effects. A Pt100 platinum resistance temperature sensor is preferred as the temperature sensing element, as it is suitable for temperature measurement in industrial environments.

[0024] The boost interval preset subsystem is used to preset several boost intervals according to set values.

[0025] The set value is the optimal sealing gap between the sector plate and the rotor flange under ideal conditions, meaning no air leakage. This value is typically determined based on the manufacturer's specifications and engineering experience. To ensure optimal performance, the set value should take into account factors such as the material's thermal expansion coefficient, mechanical deformation, and long-term wear.

[0026] To more precisely control the position adjustment of the sector plate, the lifting ranges are divided into the first, second, third, and fourth lifting ranges. Each range is designed based on a different ratio of the set value, aiming to provide corresponding adjustment strategies for different operating conditions to achieve the best sealing effect.

[0027] The size relationship of the boosting steps of the first boosting interval, the second boosting interval, the third boosting interval and the fourth boosting interval is: the boosting step of the first boosting interval < the boosting step of the second boosting interval < the boosting step of the third boosting interval < the boosting step of the fourth boosting interval.

[0028] Furthermore, the range of gap signal values ​​less than 70% of the set value is defined as the first lifting interval. This indicates the seal is too tight, with excessive friction between the sector plate and the rotor flange, or even the risk of mechanical jamming. Lifting operations should be avoided in this situation. The range of gap signal values ​​greater than or equal to 70% and less than or equal to 110% of the set value is defined as the second lifting interval. This indicates the seal is close to ideal, but fine-tuning in small steps is still required to maintain optimal sealing. The control strategy within this range aims to achieve refined adjustment, gradually approaching the optimal sealing position while minimizing interference with system operation and maintaining stable and efficient operation of the air preheater. The range of gap signal values ​​greater than 110% and less than or equal to 140% of the set value is defined as the third lifting interval. This indicates that the seal is beginning to deviate from the ideal range, and air leakage may be increasing. In this case, medium-sized lifting operations should be implemented to quickly adjust the gap back to near the set value, effectively suppressing the deterioration of air leakage and ensuring the thermal efficiency and operational stability of the boiler system. The range of gap signal values ​​greater than or equal to 140% of the set value is defined as the fourth lifting interval. This means the risk of seal failure has increased significantly, and air leakage has become a serious problem. At this point, the seal gap should be quickly narrowed using larger steps to minimize air leakage losses and prevent further impacts on boiler combustion efficiency and safe equipment operation.

[0029] The direct lifting control subsystem is connected to the lifting interval preset subsystem and is used to determine the direct lifting control strategy according to the relationship between the current gap signal value and the lifting interval.

[0030] If the current gap signal value is in the first boosting interval, no boosting is performed.

[0031] If the current gap signal value is in the second boost range, the first direct boost control scheme is executed: The current gap signal value is sampled three times continuously to determine whether the three consecutive sampled current gap signal values ​​are all in the second improvement interval; if not, the first direct improvement sub-step is determined according to the latest sampled current gap signal value.

[0032] By sampling three times in a row, possible instantaneous noise or abnormal fluctuations can be effectively filtered out, ensuring that the acquired data is more stable and reliable. If the three sampling results are all within the same range, it indicates that the current state is relatively stable and further analysis can be conducted to determine whether adjustments are needed. Conversely, if the three sampling results are inconsistent, it may indicate that there are temporary interference factors. The situation where the current gap signal value is not within the second improvement range for three consecutive samplings is as follows: First sampling Second sampling The third sampling Treatment The second improvement range The second improvement range The third improvement range Determine the first direct boost sub-step length based on the gap signal value of the latest sampling The first lifting range The second improvement range The second improvement range Determine the first direct boost sub-step length based on the gap signal value of the latest sampling The second improvement range The fourth improvement range The third improvement range Determine the first direct boost sub-step length based on the gap signal value of the latest sampling The third improvement range The second improvement range The second improvement range Determine the first direct boost sub-step length based on the gap signal value of the latest sampling Example 1: The first sampling interval is the second boost interval, the second sampling interval is also the second boost interval, but the third sampling interval becomes the third boost interval. In this case, because the three sampling results are not completely consistent, the first direct boost sub-step size is determined based on the gap signal value of the third sampling interval. This helps to quickly respond to and adapt to changes in actual operating conditions, avoiding frequent adjustments due to transient fluctuations.

[0033] Example 2: If the first sample falls within the first boost interval, the second and third samples fall back to the second boost interval. Although the last two samples fall within the same interval, because the first sample falls outside the target interval, adjustments are still made based on the gap signal value of the last sample, ensuring that decisions are based on the latest and most accurate data.

[0034] If so, an average gap signal value is determined based on the current gap signal values ​​sampled three times in succession, and a first difference between the average gap signal value and the set value is determined. If the first difference is less than or equal to 2 mm, no improvement is performed.

[0035] If the first difference is less than or equal to 2mm, the system chooses not to perform the lifting operation, mainly due to a comprehensive consideration of equipment stability and operating efficiency. First of all, 2mm is a very small value. In actual industrial applications, such a small deviation usually does not significantly affect the sealing performance of the air preheater or cause obvious air leakage. Secondly, frequent adjustments to such slight deviations will not only increase the complexity and maintenance costs of the system, but may also introduce additional mechanical stress and wear risks, thereby shortening the service life of the equipment. Therefore, by setting such a small but reasonable threshold (2mm), unnecessary adjustment operations can be avoided while ensuring the efficient operation of the equipment, ensuring the long-term stability and reliability of the system. This strategy effectively balances the need for precise control with the economy and safety in actual operation, and embodies the design concept of refined management.

[0036] If the first difference is greater than 2 mm, an initial lifting step length and a reference deformation height of the rotor top are preset; The initial lifting step length is obtained through the relevant parameters of the boiler air preheater: the maximum allowable deformation of the sealing material and the minimum resolution of the actuator (directly obtained from the equipment manual). Based on these two parameters, the initial lifting step length S0 can be obtained: S0=K×(maximum allowable deformation of the sealing material / minimum resolution of the actuator), K is the proportional coefficient determined by experiments or experience, K, the maximum allowable deformation of the sealing material and the minimum resolution of the actuator are all length units.

[0037] The initial lifting step calculated in this way takes into account both the physical limitations of the sealing material and the operating accuracy of the actuator. While ensuring efficient operation of the equipment, it can effectively reduce the number of unnecessary adjustments, extend the service life of the equipment, and improve the reliability and safety of the overall system.

[0038] △h=kth×(Tgas-T0), △h is the deformation height of the rotor top, kth is the thermal expansion coefficient, Tgas is the average flue gas temperature at the flue gas outlet, and T0 is the cold reference temperature, that is, the flue gas outlet temperature when the equipment is not running or has just been started.

[0039] This formula can accurately predict the thermal expansion of the rotor caused by temperature changes, thereby achieving precise compensation for the sealing gap.

[0040] And design the following judgment conditions: The flue gas outlet temperature fluctuation range within the historical time window is greater than 5°C; The historical time window is determined based on the device's response time and the frequency of operating condition changes. For example, if the device's temperature changes slowly, a longer time window (such as 30 minutes) can be selected; if the temperature changes rapidly, a shorter time window (such as 5 minutes) can be selected.

[0041] The deformation height of the rotor top within the historical time window is ≥ 10% of the reference deformation height of the rotor top; If any of the above judgment conditions is met, the first direct lifting step length is determined based on the flue gas outlet temperature fluctuation amplitude, the rotor top deformation height and the initial lifting step length; if all of the above judgment conditions are not met, the initial lifting step length is used as the first direct lifting step length.

[0042] S1=S0×(1+0.5WT)×(1+△h / Href), S1 is the first direct lifting step, Href is the reference deformation height of the rotor top, and WT is the fluctuation amplitude of the flue gas outlet temperature.

[0043] Among them, the fluctuation range of the flue gas outlet temperature needs to be standardized and then entered into the above formula for calculation.

[0044] When the first difference is greater than 2 mm, in this embodiment, the first direct lifting step length is preferably set to 3 mm.

[0045] Large fluctuations in the flue gas outlet temperature reflect instability or local overheating in the combustion process. When the flue gas outlet temperature fluctuation amplitude exceeds 5°C within the historical time window, it indicates that the equipment may have problems such as insufficient combustion and uneven fuel supply. Such fluctuations will have a negative impact on the sealing performance of the air preheater because temperature changes will cause thermal expansion or contraction of the material. The deformation height of the rotor top reflects the thermal expansion of the rotor at high temperatures. When the deformation height of the rotor top within the historical time window reaches or exceeds 10% of the reference deformation height of the rotor top, it indicates that the rotor has undergone significant thermal expansion, which may cause the sealing gap to become larger and affect the sealing performance of the equipment. Therefore, this embodiment determines the first direct lifting step size based on the flue gas outlet temperature fluctuation amplitude, the rotor top deformation height and the initial lifting step size. It can achieve precise control and dynamic adjustment of the sealing gap.

[0046] If the gap signal value is currently in the third boost interval, a second direct boost control scheme is executed: determining an initial gap signal value.

[0047] The initial gap signal value refers to the first value of the gap signal value in the third boosting interval.

[0048] Based on the current gap signal value, a new gap signal value is obtained every 10 seconds; if two consecutive new gap signal values ​​are greater than the initial gap signal value, the frequency of obtaining the new gap signal value is adjusted to 5 seconds.

[0049] Adjusting the acquisition frequency improves response speed and sensitivity to rapidly changing operating conditions. Detecting two consecutive increases in the gap signal indicates that the air preheater may be experiencing rapid degradation, such as from thermal expansion caused by rising temperatures or increased wear of mechanical components. Shortening the sampling interval allows for more timely detection of these changing trends, ensuring a swift response from the control system and avoiding delayed adjustments that could lead to deteriorating seal performance or equipment failure.

[0050] Determine the second difference between each new gap signal value and the set value. If the second difference is less than 2.5mm, no lifting is performed; if the second difference is greater than or equal to 2.5mm and less than 3.5mm, the initial lifting step length is used as the second direct lifting step length; if the second difference is greater than or equal to 3.5mm, the initial lifting step length is corrected based on the second difference to obtain a corrected value, and the corrected value is used as the second direct lifting step length.

[0051] When the second difference is less than 2.5mm, the system determines that the current gap change is small and will not significantly affect the sealing effect, so no lifting operation is performed to avoid unnecessary mechanical movement and wear. If the second difference is greater than or equal to 2.5mm and less than 3.5mm, it indicates that there is a certain degree of seal degradation, but it is still within the controllable range. At this time, the initial lifting step size is used for adjustment, which can effectively restore the sealing gap while reducing the additional stress caused by excessive adjustment. When the second difference is greater than or equal to 3.5mm, it means that the sealing gap has significantly deviated from the ideal state, which may have a greater impact on the operating efficiency and safety of the equipment. Therefore, it is necessary to correct the initial lifting step size based on the second difference to restore the optimal sealing state faster and more accurately. This hierarchical adjustment strategy not only improves the response speed and stability of the system, but also effectively prevents improper operation problems caused by small deviations or excessive deviations, minimizes air leakage, and improves the overall operating efficiency and reliability of the equipment.

[0052] S2=S0×(1+d×△G), S2 is the second direct improvement step, △G is the second difference, d is the gain coefficient, and the value range of d is 0.5-1.0.

[0053] The second difference needs to be standardized before being entered into the calculation formula.

[0054] When the second difference is greater than or equal to 3.5 mm, the second lifting step length is preferably 4 mm.

[0055] Each new gap signal value is adjusted by the second direct improvement step to obtain an adjusted gap signal value, and the improvement is stopped when the adjusted gap signal value improves to the second improvement interval or reaches a preset maximum improvement number.

[0056] The maximum number of lifts is preferably 5.

[0057] If the gap signal value is currently in the fourth boost range, the third direct boost control scheme is executed: Determine whether the current gap signal value is in the fourth lifting interval and lasts for 5 minutes. If so, enter the emergency lifting mode; if not, execute the second direct lifting control scheme.

[0058] By setting a 5-minute time threshold, unnecessary emergency operations caused by instantaneous fluctuations or short-term anomalies are avoided, thereby improving the stability and reliability of the system.

[0059] In emergency lifting mode, the following disturbance conditions are designed: The fluctuating amplitude of flue gas outlet temperature in the historical time window is greater than 8°C; The deformation height of the rotor top within the historical time window is ≥ 15% of the reference deformation height of the rotor top; If any of the above disturbance conditions is met, the flue gas outlet temperature fluctuation amplitude is obtained in real time. According to the flue gas outlet temperature fluctuation amplitude and the deformation height of the rotor top, the dynamic boost step size is determined and the boost is performed. If none of the above disturbance conditions is met, the initial boost step size is used as the third direct boost step size and the boost is performed. S3=S0×(1-WT)×(1+△h / Href), S3 is the third direct lifting step.

[0060] The WT here also needs to be standardized before it can be substituted into the formula for calculation.

[0061] The reference deformation height of the rotor top refers to a threshold value at which the deformation height of the rotor top will not significantly affect the air leakage of the equipment in the control system of the boiler air preheater.

[0062] When the flue gas outlet temperature fluctuation amplitude exceeds 8°C within the historical time window, it indicates that the equipment may have problems such as incomplete combustion and uneven fuel supply. This fluctuation will have a significant impact on the sealing performance of the air preheater, because temperature changes will cause thermal expansion or contraction of the material. The deformation height of the rotor top reflects the thermal expansion of the rotor at high temperatures. When the deformation height of the rotor top within the historical time window reaches or exceeds 15% of the reference deformation height of the rotor top, it indicates that the rotor has undergone significant thermal expansion, which may cause the sealing gap to become larger and affect the sealing performance of the equipment. Through the comprehensive application of the above four disturbance conditions, the system can achieve precise control and dynamic adjustment of the sealing gap. Each condition monitors the operating status of the equipment from the flue gas outlet temperature fluctuation and the rotor top deformation, and adjusts it in real time according to the specific situation.

[0063] After each action, the flue gas outlet temperature is obtained in real time. If the current flue gas outlet temperature reaches the first target temperature range, the fan plate is raised by 10mm; when the flue gas outlet temperature reaches the second target temperature range, the fan plate is further raised by 15mm.

[0064] According to field experience and debugging results, the first target temperature range is preferably 170-180°C. Although the thermal expansion effect is small, there may be a large initial sealing gap in the initial stage of equipment startup or low-load operation. Therefore, a lifting step of 10mm is selected to help quickly restore the sealing performance. In actual operation, a lifting step of 10mm can effectively compensate for the large sealing gap caused by initial installation errors or long-term wear, ensuring that the equipment can quickly achieve a good sealing effect in the initial stage of startup. The second target temperature range is preferably 300-310°C. The thermal expansion effect is significant, and the risk of increased sealing gap is higher. At this time, continuing to increase the lifting step by 5mm can effectively cope with the significantly increased sealing gap and prevent excessive cold air from leaking directly to the flue gas side without heating. Therefore, when the flue gas outlet temperature is between 170-310°C, a cumulative increase of 15mm in the lifting step can quickly reduce the sealing gap under high-load operating conditions, ensuring the efficient operation and stability of the equipment under high temperature conditions.

[0065] The lifting operation is continuously performed until the current gap value is lower than 140% of the set value, and this round of rapid and continuous lifting control is completed.

[0066] The indirect lifting control subsystem is connected with the laser gap control subsystem and the temperature control subsystem. When the laser gap control subsystem fails, the indirect lifting control strategy is determined according to the flue gas outlet temperature.

[0067] When the gap signal value is 0, the indirect improvement control strategy is determined according to the flue gas outlet temperature, including: judging whether the laser gap control subsystem failure is the first failure, if so, starting the basic improvement plan; if not, starting the intelligent enhancement improvement plan.

[0068] The basic improvement plan is specifically as follows: When the laser gap control subsystem fails for the first time, determine the historical temperature reference value of the smoke outlet and obtain the real-time temperature of the smoke outlet at the current moment; The flue gas outlet temperature deviation is determined based on the historical flue gas outlet temperature reference value and the flue gas outlet real-time temperature.

[0069] If the flue gas outlet temperature deviation is greater than 5°C, it is determined that the rotary air preheater is leaking abnormally; lift the fan plate 5mm, wait for 5 minutes after the lowering is completed, and then re-determine whether the rotary air preheater is leaking abnormally and whether it needs to be lowered; stop lowering when the cumulative lowering amount reaches 15% of the initial gap signal value.

[0070] Using temperature deviation as an indirect basis for judgment, the system promptly identifies abnormal air leakage in a rotary air preheater and implements conservative, gradual, and controlled fan plate lowering to restore sealing performance. When the flue gas outlet temperature deviation exceeds 5°C, it typically indicates an abnormal operating condition, which may be caused by factors such as uneven thermal expansion, increased sealing gaps, or increased mechanical friction, leading to increased air leakage. In this case, the system proactively raises the fan plate by 5mm at a time. This effectively reduces the sealing gap and improves air leakage while avoiding the risk of mechanical shock or over-sealing caused by excessive adjustments. A five-minute wait after each raise provides sufficient response and stabilization time for the system, ensuring that subsequent judgments are based on a truly stable operating state. The cumulative lowering amount is set to no more than 15% of the initial gap signal value to prevent continued fan plate raising in the event of a sensor failure or misjudgment, which could lead to mechanical jamming or excessive compression of the sealing surface. The overall design balances control accuracy, safety, and system stability. It is a typical feedback-based preventive control strategy suitable for transitional control scenarios when the laser gap signal is missing or unreliable.

[0071] The intelligent enhancement and improvement scheme is specifically as follows: At least two trigger threshold intervals are preset: a first-level trigger threshold interval and a second-level trigger threshold interval, wherein the first-level trigger threshold interval is smaller than the second-level trigger threshold interval; each trigger threshold interval includes an increase step size and a trigger time interval.

[0072] This embodiment preferably designs three trigger threshold intervals: Zero-level trigger threshold interval I0: [i1-i2); first-level trigger threshold interval I1: [i2-i3); second-level trigger threshold interval I2: I2≥i3.

[0073] The lifting step lengths and trigger time intervals corresponding to the three trigger threshold intervals are different. The lifting step length and trigger time interval corresponding to the zero-level trigger threshold interval is the largest, the lifting step length and trigger time interval corresponding to the second-level trigger threshold interval is the smallest, and the lifting step length and trigger time interval corresponding to the first-level trigger threshold interval is moderate.

[0074] Determine whether the current flue gas outlet temperature deviation belongs to the zero-level trigger threshold interval, the first-level trigger threshold interval, or the second-level trigger threshold interval, perform a lifting operation on the fan plate according to the lifting step size under the trigger threshold interval, and wait for the trigger time interval, then re-determine the current flue gas outlet temperature deviation and perform a lowering operation until the re-determined current flue gas outlet temperature deviation is less than the first-level trigger threshold interval and remains unchanged for 10 minutes, stop performing the lifting operation, and maintain the current gap state.

[0075] This design achieves refined dynamic adjustment of the air preheater sealing gap by establishing zero-level, one-level, and two-level trigger threshold intervals. The zero-level trigger threshold interval has the largest step size and trigger time interval, which is suitable for dealing with significant temperature changes or large sealing gap deviations; and as the trigger threshold level increases, the corresponding step size decreases and the trigger time interval shortens, ensuring that precise adjustments can be made even under slight disturbances without overreacting. The design stops performing the lifting operation when the comprehensive temperature change index drops below the one-level or even zero-level trigger threshold interval and remains stable for 10 minutes. This ensures that the system can respond quickly and correct larger sealing problems, while avoiding frequent adjustments caused by small fluctuations, effectively reducing unnecessary mechanical movements and wear risks. This multi-level control strategy not only improves the adaptability and stability of the system, but also extends the service life of the equipment and reduces maintenance costs while maintaining optimal sealing performance, reflecting the concept of high efficiency, energy saving, and intelligent management.

[0076] The execution control subsystem is used to control the lifting of the sector plate to adjust the sealing gap according to the direct lifting control strategy / indirect lifting control strategy.

[0077] Based on the direct lifting control strategy / indirect lifting control strategy, the lifting operation of the fan plate is realized by the fan plate lifting device. Furthermore, this embodiment is based on the technical problem that the high-temperature mushroom-shaped deformation and increased air leakage of the rotor will occur during hot operation, and the direct lifting control strategy and the indirect lifting control strategy are designed. Therefore, Figure 2 As shown, the lifting operation in this embodiment refers to the movement of the sector plate toward the axial sealing device.

[0078] Among them, Figure 3-4 As shown, the sector plate lifting mechanism includes: a dual motor reducer 4 and a worm gear hoist 3 arranged on the sector plate 1, the dual motor reducer 4 is connected to the worm gear hoist 3, driving the worm gear hoist 3 to work and thereby drive the sector plate 1 to move in the longitudinal direction.

[0079] The dual-motor reducer 4 and the worm gear hoist 3 are connected via a coupling 9 .

[0080] A speed measuring wheel 10 is provided on the worm gear hoist 3 .

[0081] This embodiment further includes a lifting scale 14 for controlling the lifting height.

[0082] The dual-motor reducer 4 and the worm gear hoist 3 are connected through a main motor 5 and an auxiliary motor 6.

[0083] This embodiment further includes a displacement control box 7 , on which a displacement pointer 12 is provided, which is connected to the crossbeam via a connecting plate 13 .

[0084] The worm gear hoist 3 is further provided with a hand wheel 15 .

[0085] Furthermore, the output end of the worm gear elevator 3 is equipped with an upper connecting rod 21 and a lower connecting rod 23, connected by an adjusting nut 22. A bellows 26 is mounted on the lower connecting rod 23 and connected via a connecting rod flange 24, an upper flange 25, a lower flange 27, and a sealing seat 28. A connecting rod 30 is connected between the sector plate 1 and the lower connecting rod 23, and is connected via a small pin 29. Upper connecting rod 21 and lower connecting rod 23 are fixed to hoisting mechanism frame 2, and worm gear hoist 3 is mounted on hoisting mechanism frame via side panels 17. Hoisting mechanism frame and side panels 17 are connected via I-beam 16. Dual motor reducer 4 and worm gear hoist 3 are fixed to crossbeam 8 at their top ends.

[0086] The worm gear hoist 3 is also provided with a protective cover 11. The upper connecting rod 21 is connected to the output end of the worm gear hoist 3 through a large pin 20.

[0087] The worm gear hoist 3 is connected to the dual-motor reducer 4 through a synchronous shaft 18 and a speed limiter 19.

[0088] The fan-shaped plate lifting mechanism is an existing structure.

[0089] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. Boiler air preheater sector plate lifting system, characterized by: Includes the following modules: The laser gap control subsystem is installed on the air preheater sector plate and is used to collect the gap signal value between the sector plate and the rotor flange surface; Temperature control subsystem, used to collect flue gas outlet temperature; The boost interval preset subsystem is used to preset a number of boost intervals according to set values; A direct lifting control subsystem is connected to the lifting interval preset subsystem and is used to determine a direct lifting control strategy according to the relationship between the current gap signal value and the lifting interval; an indirect lifting control subsystem connected to the laser gap control subsystem and the temperature control subsystem, and determining an indirect lifting control strategy according to the flue gas outlet temperature when the laser gap control subsystem fails; The execution control subsystem is used to control the lifting of the sector plate according to the direct lifting control strategy / the indirect lifting control strategy to adjust the sealing gap.

2. The boiler air preheater sector plate lifting system according to claim 1, characterized in that: The boost intervals include: a first boost interval, a second boost interval, a third boost interval, and a fourth boost interval.

3. The boiler air preheater sector plate lifting system according to claim 2, characterized in that: The gap signal value range that is less than 70% of the set value is used as the first lifting interval, the gap signal value range that is greater than or equal to 70% of the set value and less than or equal to 110% of the set value is used as the second lifting interval, the gap signal value range that is greater than 110% of the set value and less than or equal to 140% of the set value is used as the third lifting interval, and the gap signal value range that is greater than 140% of the set value is used as the fourth lifting interval; the size relationship of the lifting step lengths of the first lifting interval, the second lifting interval, the third lifting interval and the fourth lifting interval is: the lifting step length of the first lifting interval < the lifting step length of the second lifting interval < the lifting step length of the third lifting interval < the lifting step length of the fourth lifting interval.

4. The boiler air preheater sector plate lifting system according to claim 3, characterized in that: If the current gap signal value is in the first boosting interval, no boosting is performed; if the current gap signal value is in the second boosting interval, a first direct boosting control scheme is executed; If the gap signal value is currently in the third boost range, the second direct boost control scheme is executed; If the gap signal value is currently in the fourth boost interval, the third direct boost control scheme is executed.

5. The boiler air preheater sector plate lifting system according to claim 4, characterized in that: If the gap signal value is currently in the second boost range, a first direct boost control scheme is executed, including: Sampling the current gap signal value three times continuously, determining whether the three consecutive sampled current gap signal values ​​are all in the second boosting interval, and if not, determining a first direct boosting sub-step length according to the latest sampled current gap signal value; If so, determining an average gap signal value based on the current gap signal values ​​sampled three times in succession, determining a first difference between the average gap signal value and a set value, and if the first difference is less than or equal to 2 mm, not performing the lifting; If the first difference is greater than 2 mm, preset an initial lifting step length and a reference deformation height of the rotor top, and design the following judgment conditions: The flue gas outlet temperature fluctuation range within the historical time window is greater than 5°C; The deformation height of the rotor top within the historical time window is ≥ 10% of the reference deformation height of the rotor top; If any of the above judgment conditions is met, the first direct lifting step length is determined based on the flue gas outlet temperature fluctuation amplitude, the rotor top deformation height and the initial lifting step length; if all of the above judgment conditions are not met, the initial lifting step length is used as the first direct lifting step length.

6. The boiler air preheater sector plate lifting system according to claim 5, characterized in that: If the gap signal value is currently in the third boost range, a second direct boost control scheme is executed, including: determining an initial gap signal value; Based on the current gap signal value, a new gap signal value is obtained every 10 seconds; if two consecutive new gap signal values ​​are greater than the initial gap signal value, the frequency of obtaining the new gap signal value is adjusted to 5 seconds; Determine a second difference between each new gap signal value and the set value; if the second difference is less than 2.5 mm, do not perform lifting; if the second difference is greater than or equal to 2.5 mm and less than 3.5 mm, use the initial lifting step length as the second direct lifting step length; if the second difference is greater than or equal to 3.5 mm, correct the initial lifting step length based on the second difference to obtain a corrected value, and use the corrected value as the second direct lifting step length; Each new gap signal value is adjusted by the second direct improvement step to obtain an adjusted gap signal value, and the improvement is stopped when the adjusted gap signal value improves to the second improvement interval or reaches a preset maximum improvement number.

7. The boiler air preheater sector plate lifting system according to claim 6, characterized in that: If the gap signal value is currently in the fourth boost range, a third direct boost control scheme is executed, including: Determine whether the current gap signal value is in the fourth lifting interval and lasts for 5 minutes. If so, enter the emergency lifting mode; if not, execute the second direct lifting control scheme; In emergency lifting mode, the following disturbance conditions are designed: The flue gas outlet temperature fluctuation range within the historical time window is greater than 8°C; The deformation height of the rotor top within the historical time window is ≥ 15% of the reference deformation height of the rotor top; If any of the above disturbance conditions is met, the flue gas outlet temperature fluctuation amplitude is obtained in real time. According to the flue gas outlet temperature fluctuation amplitude and the deformation height of the rotor top, the dynamic boost step size is determined and the boost is performed. If none of the above disturbance conditions is met, the initial boost step size is used as the third direct boost step size and the boost is performed. After each action, the flue gas outlet temperature is obtained in real time. If the current flue gas outlet temperature is in the first target temperature range, the fan plate is raised by 10mm; when the flue gas outlet temperature is in the second target temperature range, the fan plate is further raised by 5mm. The lifting operation is continuously performed until the current gap value is lower than 140% of the set value, thus completing this round of rapid and continuous lifting control.

8. The boiler air preheater sector plate lifting system according to claim 6, characterized in that: When the gap signal value is 0, the indirect improvement control strategy is determined according to the flue gas outlet temperature, including: judging whether the laser gap control subsystem failure is the first failure, if so, starting the basic improvement plan; if not, starting the intelligent enhancement improvement plan.

9. The boiler air preheater sector plate lifting system according to claim 8, characterized in that: The basic improvement plan is specifically as follows: When the laser gap control subsystem fails for the first time, determine the historical temperature reference value of the flue gas outlet and obtain the real-time temperature of the flue gas outlet at the current moment; Determine the flue gas outlet temperature deviation based on the historical flue gas outlet temperature reference value and the real-time flue gas outlet temperature; If the flue gas outlet temperature deviation is greater than 5°C, the rotary air preheater is judged to have abnormal air leakage; lift the fan plate by 5mm, wait for 5 minutes after the lifting is completed, and then re-judge whether the rotary air preheater has abnormal air leakage and whether it needs to be lifted; stop lifting when the cumulative lifting amount reaches 15% of the initial gap signal value.

10. The boiler air preheater sector plate lifting system according to claim 8, characterized in that: The intelligent enhancement and improvement scheme is specifically as follows: At least two trigger threshold intervals are preset: a first-level trigger threshold interval and a second-level trigger threshold interval, wherein the first-level trigger threshold interval is smaller than the second-level trigger threshold interval; each trigger threshold interval includes an increase step size and a trigger time interval; Determine whether the current flue gas outlet temperature deviation belongs to the first-level trigger threshold interval or the second-level trigger threshold interval, perform a lifting operation on the fan plate according to the lifting step size under the trigger threshold interval, and wait for the trigger time interval, then re-determine the current flue gas outlet temperature deviation and perform the lifting operation until the re-determined current flue gas outlet temperature deviation is less than the first-level trigger threshold interval and remains unchanged for 10 minutes, stop performing the lifting operation, and maintain the current gap state.

Images