Boiler air preheater sector lifting system

Abstract

The application discloses a boiler air preheater sector plate lifting system and relates to the technical gap lifting field.A laser gap control subsystem is used for collecting a gap signal value between a sector plate and a rotor flange face; a temperature control subsystem is used for collecting a flue gas outlet temperature; a lifting interval presetting subsystem is used for presetting a plurality of lifting intervals according to a set value; a direct lifting control subsystem is used for determining a direct lifting control strategy according to a relationship between the gap signal value and the lifting intervals; an 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 an execution control subsystem is used for controlling sector plate lifting to adjust a sealing gap according to the direct lifting control strategy / indirect lifting control strategy. Through the introduction of a multi-parameter fusion feedback mechanism, fine control is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gap lifting, in particular to a boiler air preheater sector plate lifting system. BACKGROUND

[0002] In the actual operation of rotary air preheaters, due to their structural characteristics and high-temperature working environment, there is a common problem of high air leakage rate, with some units having air leakage rates exceeding 15%, which is much higher than the design value. The main source of air leakage is the sealing gap between the sector plate and the rotor, and this gap is affected by multiple factors. During normal hot-state operation, the rotor of the air preheater filled with heat storage elements expands radially due to internal heat exchange, resulting in high temperature at the hot end and large radial expansion; on the contrary, the temperature at the cold end is low, and the radial expansion is small. In addition, the central axis expands upward, causing the hot end to expand more, the center to move upward, and the outer edge to be relatively small. In addition to the effect of self-weight sagging, the rotor will produce a so-called "mushroom-shaped" deformation. This deformation causes the gap to increase in some areas (such as the outside of the hot end), while the gap decreases in other areas (such as the outside of the cold end). If this dynamic change is not adjusted, it will lead to a large amount of gas leakage and may cause severe friction between the rotor and the fixed components, and in extreme cases, it may even cause jamming. Therefore, the design intention of the sector plate is to compensate for the gap change caused by the descent of the rotor, which is in a descending state under normal operating conditions, and can be lifted in emergency situations to monitor the state of the rotor and ensure that the umbrella-shaped plate and the rotor maintain an appropriate gap.

[0003] However, traditional control systems usually rely on a single gap signal for adjustment, lack dynamic response mechanisms for comprehensive factors such as temperature and deformation, and are difficult to achieve precise and timely sealing control. When the sensor fails, these systems often lack effective backup strategies, leading to control failure or improper adjustment. These problems not only reduce the thermal efficiency of the boiler and increase the energy consumption of the fan, but also affect the stability of the combustion, exacerbate the corrosion and ash accumulation of the equipment, 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 the existing system and improve its ability to cope with complex working conditions. SUMMARY

[0004] The present application relates to the technical field of gap lifting, in particular to a boiler air preheater sector plate lifting system.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a boiler air preheater sector plate lifting system, comprising the following modules:

[0006] A laser gap control subsystem is installed on the air preheater sector plate to collect the gap signal value between the sector plate and the rotor flange surface;

[0007] a temperature control subsystem for collecting the temperature of the flue gas outlet;

[0008] a lifting interval presetting subsystem for presetting a plurality of lifting intervals according to a set value;

[0009] a direct lifting control subsystem connected with the lifting interval presetting subsystem, for determining a direct lifting control strategy according to the relationship between the current gap signal value and the lifting interval;

[0010] an indirect lifting control subsystem connected with the laser gap control subsystem and the temperature control subsystem, for determining an indirect lifting control strategy according to the temperature of the flue gas outlet when the laser gap control subsystem fails;

[0011] an execution control subsystem for controlling the lifting of the sector plate to adjust the sealing gap according to the direct lifting control strategy / indirect lifting control strategy.

[0012] In another embodiment, the lifting intervals include a first lifting interval, a second lifting interval, a third lifting interval and a fourth lifting interval.

[0013] In another embodiment, a range of gap signal values less than 70% of the set value is taken as the first lifting interval, a range of gap signal values greater than or equal to 70% of the set value and less than or equal to 110% of the set value is taken as the second lifting interval, a range of gap signal values greater than 110% of the set value and less than or equal to 140% of the set value is taken as the third lifting interval, and a range of gap signal values greater than 140% of the set value is taken as the fourth lifting interval; the size relationship of the lifting steps of the first lifting interval, the second lifting interval, the third lifting interval and the fourth lifting interval is: the lifting step of the first lifting interval < the lifting step of the second lifting interval < the lifting step of the third lifting interval < the lifting step of the fourth lifting interval.

[0014] In another embodiment, when the current gap signal value is in the first lifting interval, no lifting is performed; when the current gap signal value is in the second lifting interval, a first direct lifting control scheme is executed; when the current gap signal value is in the third lifting interval, a second direct lifting control scheme is executed; and when the current gap signal value is in the fourth lifting interval, a third direct lifting control scheme is executed.

[0015] In another embodiment, when the current gap signal value is in the second lifting interval, a first direct lifting control scheme is executed, including:

[0016] sampling the current gap signal value three times in succession, and determining whether the current gap signal values sampled three times in succession are all in the second lifting interval; if not, determining a first direct lifting sub-step according to the current gap signal value sampled the latest time;

[0017] If yes, determine an average gap signal value based on the current gap signal value of the last three samplings, determine a first difference value between the average gap signal value and the set value, if the first difference value is less than or equal to 2 mm, then no lifting is performed;

[0018] If the first difference value is greater than 2 mm, preset an initial lifting step and a rotor top reference deformation height, and design the following judgment conditions:

[0019] The temperature fluctuation amplitude of the flue gas outlet in the historical time window is greater than 5℃;

[0020] The rotor top deformation height in the historical time window is greater than or equal to 10% of the rotor top reference deformation height;

[0021] If any of the above judgment conditions is met, then determine a first direct lifting step according to the temperature fluctuation amplitude of the flue gas outlet, the rotor top deformation height and the initial lifting step; if all of the above judgment conditions are not met, then the initial lifting step is taken as the first direct lifting step.

[0022] In another embodiment, if the current gap signal value is in the third lifting interval, then a second direct lifting control scheme is performed, including:

[0023] Determine an initial gap signal value;

[0024] Based on the current gap signal value, obtain a new gap signal value every 10s; if both of the last two new gap signal values are greater than the initial gap signal value, then adjust the frequency of obtaining the new gap signal value to 5s;

[0025] Determine a second difference value between each new gap signal value and the set value, if the second difference value is less than 2.5 mm, then no lifting is performed; if the second difference value is greater than or equal to 2.5 mm and less than 3.5 mm, then take the initial lifting step as the second direct lifting step; if the second difference value is greater than or equal to 3.5 mm, then modify the initial lifting step based on the second difference value to obtain a modified value, and take the modified value as the second direct lifting step;

[0026] Adjust each new gap signal value by the second direct lifting step to obtain an adjusted gap signal value, until the adjusted gap signal value is lifted up to the second lifting interval or the preset maximum lifting times are reached.

[0027] In another embodiment, if the current gap signal value is in the fourth lifting interval, then a third direct lifting control scheme is performed, including:

[0028] Determine whether the current gap signal value is in the fourth lifting interval and lasts for 5 minutes, if yes, then enter the emergency lifting mode; if no, then perform the second direct lifting control scheme;

[0029] In the emergency boost mode, the following perturbation conditions were designed:

[0030] The flue gas outlet temperature fluctuation range within the historical time window is >8℃;

[0031] Within the historical time window, the deformation height at the top of the rotor is ≥ 15% of the reference deformation height at the top of the rotor;

[0032] If any of the above disturbance conditions are met, the flue gas outlet temperature fluctuation range is obtained in real time. Based on the flue gas outlet temperature fluctuation range and the deformation height of the rotor top, the dynamic lifting step size is determined and the lifting is carried out. If none of the above disturbance conditions are met, the initial lifting step size is used as the third direct lifting step size and the lifting is carried out.

[0033] After each action, the flue gas outlet temperature is acquired 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 raised by another 5mm.

[0034] Continue the lifting operation until the current gap value is lower than 140% of the set value, thus completing this round of rapid continuous lifting control.

[0035] In another implementation, when the gap signal value is 0, an indirect enhancement control strategy is determined based on the flue gas outlet temperature, including: determining whether the fault in the laser gap control subsystem is the first fault; if so, the basic enhancement scheme is activated; if not, the intelligent enhancement enhancement scheme is activated.

[0036] In another implementation, the basic enhancement scheme is specifically as follows:

[0037] When the laser gap control subsystem experiences its first failure, 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.

[0038] The flue gas outlet temperature deviation is determined based on the historical baseline value of the flue gas outlet temperature and the real-time temperature of the flue gas outlet.

[0039] If the flue gas outlet temperature deviation is greater than 5℃, the rotary air preheater is judged to have abnormal air leakage. The fan-shaped plate is raised by 5mm. After the raising is completed, wait for 5 minutes and then re-determine whether the rotary air preheater has abnormal air leakage and whether it needs to be raised. The raising is stopped when the cumulative raising amount reaches 15% of the initial gap signal value.

[0040] In another implementation, the intelligent enhancement scheme is specifically as follows:

[0041] The preset at least two trigger threshold intervals are a first trigger threshold interval and a second trigger threshold interval, the first trigger threshold interval is smaller than the second trigger threshold interval, and each trigger threshold interval comprises a lifting step and a trigger time interval;

[0042] The smoke outlet temperature deviation at the current moment is determined to belong to the first trigger threshold interval or the second trigger threshold interval, lifting operation is performed on the sector plate according to the lifting step in the trigger threshold interval to which the smoke outlet temperature deviation belongs, and after the trigger time interval is waited, the smoke outlet temperature deviation at the current moment is determined again and lifting operation is performed until the smoke outlet temperature deviation at the current moment determined again is smaller than the first trigger threshold interval and remains unchanged for 10 minutes, and the lifting operation is stopped, and the current gap state is maintained.

[0043] The technical effects and advantages of the present application are as follows:

[0044] The boiler air preheater sector plate lifting system provided by the present application realizes fine and self-adaptive control of the sealing gap of the sector plate by introducing a multi-parameter fusion feedback mechanism of a laser gap control subsystem and a temperature control subsystem, combining a hierarchical lifting interval and a dynamic adjustment strategy. The system automatically divides the control levels according to the real-time gap signal and the temperature change state, adjusts respectively using different lifting steps and response frequencies, and switches to an indirect control strategy based on temperature deviation when the laser sensor fails, ensuring the continuity and reliability of the control. The scheme effectively deals with the gap change caused by the thermal deformation of the rotor, significantly reduces the air leakage rate, improves the boiler combustion efficiency and the economic efficiency of the unit operation, reduces the equipment wear and energy consumption, prolongs the service life of the equipment, and has good engineering application value and popularization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The structure block diagram of the boiler air preheater sector plate lifting system provided by the present application is provided;

[0046] Figure 2 The sector plate lifting direction schematic diagram of the boiler air preheater sector plate lifting system provided by the present application is provided;

[0047] Figure 3 The structure schematic diagram of the sector plate lifting mechanism of the boiler air preheater sector plate lifting system provided by the present application is provided;

[0048] Figure 4 The side view of the sector plate lifting mechanism of the boiler air preheater sector plate lifting system provided by the present application is provided.

[0049] Fig. 1: 1 - sector plate, 2 - lifting mechanism frame, 3 - worm gear lifting machine, 4 - double motor reducer, 5 - main motor, 6 - auxiliary motor, 7 - displacement control box, 8 - cross beam, 9 - shaft coupling, 10 - speed measuring wheel, 11 - protective cover, 12 - displacement pointer, 13 - connecting plate, 14 - lifting scale, 15 - hand wheel, 16 - I-beam, 17 - side plate, 18 - synchronous 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 - corrugated pipe, 27 - lower flange, 28 - sealing seat, 29 - small pin shaft, 30 - sector plate connecting rod, 31 - axial sealing device. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0051] As shown in Figure 1 The present embodiment discloses a boiler air preheater sector plate lifting system, which comprises the following modules:

[0052] A laser gap control subsystem is installed on the air preheater sector plate to collect the gap signal value between the sector plate and the rotor flange surface.

[0053] In the prior art, the axial sealing device 31 of the boiler air preheater is fixedly connected through the rotor flange surface and located between the upper sector plate and the lower sector plate, forming a dynamic sealing surface to reduce the air leakage between the rotor and the stator. When the device is running, the rotor will rotate with this part of the structure, while the sector plate remains relatively static, and the size of this sealing gap is controlled by adjusting the position of the sector plate. In order to accurately monitor the sealing gap, the laser gap control subsystem, preferably a laser gap sensor, is installed at multiple positions of the upper and lower sealing plates to collect the gap signal value between the sector plate and the rotor flange surface.

[0054] In another embodiment, in order to accurately monitor the sealing gap between the boiler air preheater sector plate and the rotor flange face, and to convert this physical distance information into a processable electrical signal. The conversion process: first based on a pre-set linear mapping relationship, for example, the minimum detection gap of 1 mm corresponds to the 4 mA current output, and the maximum detection gap of 5 mm (may be larger) corresponds to the 20 mA current output. Assuming that the actual gap measured at a certain time is 3.5 mm, then according to this linear relationship, the corresponding current signal should be 14 mA (calculation method: every mm of gap change causes a current change of 4 mA / mm, so 3.5 mm-1 mm=2.5 mm, 2.5 mm 4mA / mm+4mA=14mA). This conversion not only facilitates long-distance transmission and enhances electromagnetic interference resistance, but also enables PLC and other control systems to directly read and process these standardized current signals, thereby achieving precise adjustment of the sector plate position.

[0055] A temperature control subsystem for collecting the flue gas outlet temperature.

[0056] A flue gas outlet temperature sensor installed inside the air preheater flue gas outlet pipe or immediately adjacent to the outlet. In order to accurately measure the temperature of the flue gas outlet, the sensor should be installed on the path of the flue gas flow, avoiding installation in dead corners or areas with poor flue gas flow. The ideal installation point is at the center of the flue, which can ensure that the true temperature of the flue gas is measured rather than the temperature affected by local cooling effects. It is preferred to use a Pt100 platinum resistance temperature sensor as the temperature detection element, which is suitable for temperature measurement in industrial environments.

[0057] A lifting interval presetting subsystem for presetting a number of lifting intervals based on a set value.

[0058] The set value refers to the optimal sealing gap between the sector plate and the rotor flange face under ideal conditions, i.e., the equipment does not have air leakage. This value is usually determined based on the technical specifications provided by the equipment manufacturer and engineering experience. In order to ensure the best performance of the equipment, the set value should take into account factors such as the thermal expansion coefficient of the material, mechanical deformation, and wear during long-term operation.

[0059] In order to more finely control the position adjustment of the sector plate, the lifting intervals are divided. The lifting intervals include: a first lifting interval, a second lifting interval, a third lifting interval, and a fourth lifting interval. Each interval is designed based on a different proportion of the set value, with the goal of providing corresponding adjustment strategies for different operating conditions to achieve the best sealing effect.

[0060] The size relationship of the lifting steps of the first lifting interval, the second lifting interval, the third lifting interval and the fourth lifting interval is: the lifting step of the first lifting interval < the lifting step of the second lifting interval < the lifting step of the third lifting interval < the lifting step of the fourth lifting interval.

[0061] Further, the gap signal value range less than 70% of the set value is taken as the first lifting interval. It indicates that the sealing is too tight, and there is a risk of excessive friction or mechanical jamming between the fan-shaped plate and the rotor flange. At this time, the lifting operation should be avoided. 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 taken as the second lifting interval. It indicates that the current state has approached the ideal sealing state, but still needs to be fine-tuned by a small step to maintain the best sealing effect. The control strategy in this interval aims to achieve fine adjustment and gradually approach the optimal sealing position, while reducing the disturbance to the system operation and maintaining stable and efficient operation of the air preheater. The gap signal value range greater than 110% of the set value and less than or equal to 140% of the set value is taken as the third lifting interval, indicating that the sealing state starts to deviate from the ideal range, and the air leakage may increase. At this time, a medium step lifting action should be taken to quickly adjust the gap to the set value, effectively suppress the air leakage deterioration trend, and ensure the thermal efficiency and stable operation of the boiler system. The gap signal value range greater than or equal to 140% of the set value is taken as the fourth lifting interval. It means that the risk of sealing failure is significantly rising, and the air leakage problem is already serious. At this time, a larger step should be used to quickly reduce the sealing gap to minimize air leakage loss and prevent further affecting the boiler combustion efficiency and safe operation of the equipment.

[0062] The direct lifting control subsystem is connected with the lifting interval presetting subsystem, and is used for determining a direct lifting control strategy according to the relationship between the current gap signal value and the lifting interval.

[0063] If the current gap signal value is in the first lifting interval, no lifting is performed.

[0064] If the current gap signal value is in the second lifting interval, a first direct lifting control scheme is executed.

[0065] The current gap signal value is continuously sampled three times, and it is judged whether the current gap signal values sampled continuously three times are all in the second lifting interval. If not, a first direct lifting sub-step is determined according to the current gap signal value sampled for the latest time.

[0066] By taking three consecutive samples, the possible transient noise or abnormal fluctuations are effectively filtered out, ensuring that the data obtained is more stable and reliable. If the results of the three samples are within the same interval, it indicates that the current state is relatively stable, and further analysis can be performed to determine whether adjustment is needed; otherwise, if the results of the three samples are inconsistent, it may indicate that there are temporary interference factors, and the current gap signal value of the three consecutive samples is not in the second lifting interval as follows:

[0067] First sampling Second sampling Third sampling Treatment regime Second lifting interval Second lifting interval Third lifting interval Determining a first direct lifting substep from the gap signal value of the latest sampling First lifting interval Second lifting interval Second lifting interval Determining a first direct lifting substep from the gap signal value of the latest sampling Second lifting interval Fourth lifting interval Third lifting interval Determining a first direct lifting substep from the gap signal value of the latest sampling Third lifting interval Second lifting interval Second lifting interval Determining a first direct lifting substep from the gap signal value of the latest sampling

[0068] Example 1: The first sampling is in the second lifting interval, and the second sampling is also in the second lifting interval, but the third sampling becomes the third lifting interval. At this time, since the results of the three samples are not completely consistent, the first direct lifting sub-step will be determined according to the gap signal value of the third sampling. This helps to quickly respond and adapt to changes in actual working conditions, avoiding frequent adjustments due to transient fluctuations.

[0069] Example 2: If the first sampling is in the first lifting interval, the second and third samplings return to the second lifting interval. Although the last two samplings are in the same interval, since the first sampling is not in the target interval, the adjustment will still be based on the gap signal value of the last sampling to ensure that the decision is based on the latest and most accurate data.

[0070] If yes, determine the average gap signal value based on the current gap signal value of the three consecutive samplings, determine the first difference value between the average gap signal value and the set value, and if the first difference value is less than or equal to 2mm, do not perform lifting.

[0071] If the first difference value is less than or equal to 2mm, the system selects not to perform lifting operation, mainly considering the comprehensive consideration of equipment stability and running efficiency. First of all, 2mm is a very small value, in actual industrial application, such a small deviation usually does not significantly affect the sealing performance of the air preheater or cause obvious air leakage phenomenon. Secondly, frequent adjustment of such a subtle deviation not only increases the complexity and maintenance cost of the system, but also may introduce additional mechanical stress and wear risk, thereby shortening the service life of the equipment. Therefore, by setting such a small but reasonable threshold (2mm), the efficient operation of the equipment can be ensured while avoiding unnecessary adjustment operation, ensuring the long-term stability and reliability of the system. This strategy effectively balances the demand for precise control and the economy and safety in actual operation, embodying the design concept of fine management.

[0072] If the first difference value is greater than 2mm, an initial lifting step and a rotor top reference deformation height are preset;

[0073] The initial lifting step is obtained by relevant parameters of the boiler air preheater: the maximum deformation allowed by the sealing material and the minimum resolution of the actuator (directly obtained from the equipment manual), and the initial lifting step S0 can be obtained according to the two parameters: S0=K×(the maximum deformation allowed by the sealing material / the minimum resolution of the actuator), K is a proportional coefficient determined by experiment or experience, and K, the maximum deformation allowed by the sealing material and the minimum resolution of the actuator are all length units.

[0074] The initial lifting step calculated in this way not only considers the physical limit of the sealing material, but also takes into account the operation accuracy of the actuator, which can effectively reduce unnecessary adjustment times, prolong the service life of the equipment, and improve the reliability and safety of the overall system while ensuring efficient operation of the equipment.

[0075] △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 outlet, and T0 is the cold reference temperature, i.e. the flue gas outlet temperature when the equipment is not running or just started.

[0076] This formula can accurately predict the rotor thermal expansion caused by temperature changes, thereby achieving accurate compensation of the sealing gap.

[0077] And the following judgment conditions are designed:

[0078] The flue gas outlet temperature fluctuation amplitude in the historical time window is greater than 5℃;

[0079] The historical time window is determined according to the response time of the equipment and the frequency of working condition changes. For example, if the temperature change of the equipment is relatively slow, a longer time window (such as 30 minutes) can be selected; if the change is faster, a shorter time window (such as 5 minutes) should be selected.

[0080] The rotor top deformation height in the historical time window is greater than or equal to 10% of the rotor top reference deformation height;

[0081] If any of the above judgment conditions is met, the first direct lifting step is determined according to the flue gas outlet temperature fluctuation amplitude, the rotor top deformation height and the initial lifting step; if all the above judgment conditions are not met, the initial lifting step is taken as the first direct lifting step.

[0082] S1=S0×(1+0.5WT)×(1+△h / Href), S1 is the first direct lifting step, Href is the rotor top reference deformation height, and WT is the flue gas outlet temperature fluctuation amplitude.

[0083] Wherein, the flue gas outlet temperature fluctuation amplitude needs to be standardized before being put into the above formula for calculation.

[0084] When the first difference is greater than 2 mm, the first direct lifting step is preferably 3 mm in this embodiment.

[0085] Large fluctuations in the flue gas outlet temperature reflect the instability or local overheating phenomenon of the combustion process. When the fluctuation amplitude of the flue gas outlet temperature within the historical time window exceeds 5℃, it indicates that the equipment may have problems such as insufficient combustion and uneven fuel supply. Such fluctuations can have a negative impact on the sealing performance of the air preheater, as temperature changes can cause thermal expansion or contraction of materials. The rotor top deformation height reflects the thermal expansion of the rotor under high temperature. When the rotor top deformation height within the historical time window reaches or exceeds 10% of the rotor top reference deformation height, it indicates that the rotor has undergone significant thermal expansion, which may cause the sealing gap to become larger, affecting the sealing performance of the equipment. Therefore, this embodiment determines the first direct lifting step based on the flue gas outlet temperature fluctuation amplitude, the rotor top deformation height, and the initial lifting step. It can achieve precise control and dynamic adjustment of the sealing gap.

[0086] If the current gap signal value is in the third lifting interval, a second direct lifting control scheme is executed: determining an initial gap signal value.

[0087] The initial gap signal value refers to the first numerical value of the gap signal value within the third lifting interval.

[0088] Based on the current gap signal value, a new gap signal value is obtained every 10s; if the new gap signal values of two consecutive times are both greater than the initial gap signal value, the acquisition frequency of the new gap signal value is adjusted to 5s.

[0089] By adjusting the acquisition frequency, the response speed and sensitivity of rapidly changing working conditions are improved. When it is detected that the gap signal value increases continuously for two times, it indicates that the air preheater may be in a rapidly deteriorating stage, such as thermal expansion due to temperature rise or accelerated wear of mechanical parts, etc. By shortening the sampling interval, these changing trends can be captured more timely, ensuring that the control system can respond quickly to avoid deterioration of sealing performance or equipment failure due to delayed adjustment.

[0090] A second difference between each new gap signal value and the set value is determined, if the second difference is less than 2.5 mm, no lifting is performed; if the second difference is greater than or equal to 2.5 mm and less than 3.5 mm, the initial lifting step is taken as the second direct lifting step; if the second difference is greater than or equal to 3.5 mm, the initial lifting step is corrected based on the second difference to obtain a correction value, and the correction value is taken as the second direct lifting step.

[0091] When the second difference is less than 2.5 mm, the system determines that the current gap change is small and does not significantly affect the sealing effect, so no lifting operation is performed to avoid unnecessary mechanical action and wear. If the second difference is greater than or equal to 2.5 mm and less than 3.5 mm, it indicates that there is a certain degree of sealing degradation, but it is still within a controllable range. At this time, the initial lifting step is used for adjustment, which can effectively restore the sealing gap and reduce the additional stress caused by excessive adjustment. When the second difference is greater than or equal to 3.5 mm, it means that the sealing gap has deviated significantly from the ideal state, which may have a greater impact on the efficiency and safety of the device. Therefore, the initial lifting step needs to be corrected based on the second difference to restore the optimal sealing state more quickly and accurately. This hierarchical adjustment strategy not only improves the response speed and stability of the system, but also effectively prevents improper operation caused by small or large deviations, minimizing air leakage and improving the overall efficiency and reliability of the device.

[0092] S2 = S0 x (1 + d x AG), S2 is the second direct lifting step, AG is the second difference, d is the gain coefficient, and the value of d is 0.5-1.0.

[0093] The second difference needs to be standardized before being put into the formula for calculation.

[0094] When the second difference is greater than or equal to 3.5 mm, the second lifting step is preferably 4 mm.

[0095] The second direct lifting step is used to adjust each new gap signal value to obtain an adjusted gap signal value, and the adjustment is stopped when the adjusted gap signal value is lifted until the second lifting interval or the preset maximum lifting number is reached.

[0096] The maximum lifting number is preferably 5 times.

[0097] If the current gap signal value is in the fourth lifting interval, a third direct lifting control scheme is executed.

[0098] It is determined whether the current gap signal value is in the fourth lifting interval and lasts for 5 minutes. If yes, the emergency lifting mode is entered; if no, the second direct lifting control scheme is executed.

[0099] By setting a 5-minute time threshold, unnecessary emergency operations caused by transient fluctuations or temporary abnormalities are avoided, improving the stability and reliability of the system.

[0100] In the emergency lifting mode, the following disturbance conditions are designed:

[0101] The fluctuation amplitude of the flue gas outlet temperature in the historical time window is >8℃;

[0102] the rotor top deformation height in the historical time window is greater than or equal to 15% of the rotor top reference deformation height;

[0103] If any of the above disturbance conditions is met, the real-time flue gas outlet temperature fluctuation amplitude is obtained, and the dynamic lifting step is determined according to the flue gas outlet temperature fluctuation amplitude and the rotor top deformation height, and lifting is performed; if none of the above disturbance conditions is met, the initial lifting step is taken as the third direct lifting step and lifting is performed.

[0104] S3=S0x(1-WT)x(1+△h / Href), S3 is the third direct lifting step.

[0105] WT here also needs to be standardized before being substituted into the formula for calculation.

[0106] The rotor top reference deformation height refers to a threshold in the control system of the boiler air preheater, at which the rotor top deformation height does not significantly affect the equipment air leakage.

[0107] When the flue gas outlet temperature fluctuation amplitude in the historical time window exceeds 8℃, it indicates that the equipment may have problems such as insufficient combustion and uneven fuel supply. Such fluctuations can significantly affect the sealing performance of the air preheater, as temperature changes can cause thermal expansion or contraction of materials. The rotor top deformation height reflects the thermal expansion of the rotor under high temperature. When the rotor top deformation height in the historical time window reaches or exceeds 15% of the rotor top reference deformation height, it indicates that the rotor has undergone significant thermal expansion, which can 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 state of the equipment from the flue gas outlet temperature fluctuation and the rotor top deformation, and adjusts in real time according to the specific situation.

[0108] After each action, the real-time flue gas outlet temperature is obtained, and if the current flue gas outlet temperature reaches the first target temperature interval, the sector plate is lifted by 10mm; if the flue gas outlet temperature reaches the second target temperature interval, the sector plate is further lifted by 15mm.

[0109] According to field experience and commissioning results, the first target temperature range is preferably 170-180℃, although the thermal expansion effect is small, but because there may be a large initial sealing gap at the initial start-up or low load operation of the equipment, therefore, the lifting step of 10mm is selected, which is helpful to quickly restore the sealing performance. In actual operation, the lifting step of 10mm can effectively compensate for the larger sealing gap caused by initial installation error or long-term wear, ensuring that the equipment can quickly achieve good sealing effect at the initial start-up. The second target temperature range is preferably 300-310℃, the thermal expansion effect is significant, and the risk of increased sealing gap is higher. At this time, continue to increase the lifting step of 5mm, which can effectively cope with the significantly increased sealing gap and prevent too much cold air from leaking directly to the flue gas side without heating. Therefore, when the flue gas outlet temperature is in the range of 170-310℃, the cumulative lifting step of 15mm can quickly reduce the sealing gap under high load operation conditions, ensuring the efficient operation and stability of the equipment under high temperature conditions.

[0110] The lifting operation is continuously performed until the current gap value is lower than 140% of the set value, i.e. the current round of fast continuous lifting control is completed.

[0111] The indirect lifting control subsystem is connected with the laser gap control subsystem and the temperature control subsystem, and when the laser gap control subsystem fails, the indirect lifting control strategy is determined according to the flue gas outlet temperature.

[0112] When the gap signal value is 0, the indirect lifting 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 yes, starting the basic lifting scheme; if no, starting the intelligent enhanced lifting scheme.

[0113] The basic lifting scheme is specifically:

[0114] When the laser gap control subsystem is the first failure, the historical flue gas outlet temperature reference value is determined, and the real-time flue gas outlet temperature at the current time is obtained.

[0115] The flue gas outlet temperature deviation is determined according to the historical flue gas outlet temperature reference value and the real-time flue gas outlet temperature.

[0116] If the flue gas outlet temperature deviation is greater than 5℃, it is determined that the rotary air preheater has a leakage abnormality; the sector plate is lifted by 5mm, and after the descent is completed, it is determined again whether the rotary air preheater has a leakage abnormality and whether it needs to be lowered; until the cumulative descent amount reaches 15% of the initial gap signal value, the descent is stopped.

[0117] The temperature deviation is used as an indirect judgment basis to timely identify the abnormal state of air leakage of the rotary air preheater, and a conservative, gradual and controllable sector plate lowering measure is taken to restore the sealing performance. When the temperature deviation of the flue gas outlet exceeds 5℃, it usually means that the abnormal state of the equipment operation occurs, which may be caused by factors such as uneven thermal expansion, increased sealing gap or intensified mechanical friction, thereby causing increased air leakage. At this time, the system actively lifts the sector plate by 5mm each time, which can effectively reduce the sealing gap to improve the air leakage problem, and also avoids the mechanical impact or over-sealing risk caused by excessive adjustment amplitude; after each lifting, it waits for 5 minutes to provide sufficient response and stabilization time for the system, ensuring that the subsequent judgment is based on the true stable operating state; and the cumulative lowering amount is set to not more than 15% of the initial gap signal value, in order to prevent continuous lifting of the sector plate in the case of sensor failure or misjudgment, thereby avoiding problems such as mechanical jamming or excessive compression of the sealing surface. The overall design takes into account the control accuracy, safety and system stability, and is a typical preventive control strategy based on feedback, which is suitable for the transition control scene when the laser gap signal is missing or unreliable.

[0118] The intelligent enhancement lifting scheme specifically comprises:

[0119] predetermined at least two trigger threshold intervals: a first trigger threshold interval and a second trigger threshold interval, the first trigger threshold interval being smaller than the second trigger threshold interval; each trigger threshold interval includes a lifting step and a trigger time interval.

[0120] The embodiment preferably designs three trigger threshold intervals:

[0121] The zeroth trigger threshold interval I0 is [i1-i2); the first trigger threshold interval I1 is [i2-i3); and the second trigger threshold interval I2 is I2≥i3.

[0122] The lifting step and the trigger time interval corresponding to the three trigger threshold intervals are different, the lifting step and the trigger time interval corresponding to the zeroth trigger threshold interval are the largest, the lifting step and the trigger time interval corresponding to the second trigger threshold interval are the smallest, and the lifting step and the trigger time interval corresponding to the first trigger threshold interval are moderate.

[0123] Determine whether the flue gas outlet temperature deviation at the current time belongs to the zeroth trigger threshold interval, the first trigger threshold interval or the second trigger threshold interval, perform a lifting operation on the sector plate according to the lifting step under the trigger threshold interval to which it belongs, and wait for the trigger time interval, then re-determine the flue gas outlet temperature deviation at the current time and perform a lowering operation, until the re-determined flue gas outlet temperature deviation at the current time is less than the first trigger threshold interval and remains unchanged for 10 minutes, stop performing the lifting operation, and keep the current gap state.

[0124] The design realizes fine dynamic adjustment of the sealing gap of the air preheater by setting zero, first and second trigger threshold intervals. The promotion step and trigger time interval of the zero trigger threshold interval are the largest, which is suitable for coping with significant temperature changes or larger sealing gap deviations; and as the trigger threshold level increases, the corresponding promotion step decreases and the trigger time interval shortens, ensuring that accurate adjustment can be made under slight disturbance without overreaction. The design of stopping the promotion operation when the comprehensive temperature change index falls below the first or even zero trigger threshold interval and remains stable for 10 minutes ensures that the system can quickly respond and correct larger sealing problems, and avoids frequent adjustment caused by small fluctuations, effectively reducing unnecessary mechanical action and wear and tear risk. This multi-level control strategy not only improves the adaptability and stability of the system, but also prolongs the service life of the equipment and reduces maintenance costs while maintaining optimal sealing performance, embodying the concepts of high efficiency, energy saving and intelligent management.

[0125] The execution control subsystem is configured to control the sector plate lifting according to the direct lifting control strategy / indirect lifting control strategy to adjust the sealing gap.

[0126] The sector plate lifting is realized by the sector plate lifting device based on the direct lifting control strategy / indirect lifting control strategy. Further, the direct lifting control strategy and the indirect lifting control strategy are designed based on the technical problem that high-temperature mushroom-shaped deformation caused by rotor hot-state operation increases air leakage, and therefore, as shown in Figure 2 The lifting operation of the present embodiment refers to the movement operation of the sector plate moving towards the axial sealing device.

[0127] As shown in Figures 3-4 The sector plate lifting mechanism comprises a double-motor reducer 4 and a worm gear lifting machine 3 arranged on the sector plate 1, the double-motor reducer 4 is connected with the worm gear lifting machine 3, and drives the worm gear lifting machine 3 to work so as to drive the sector plate 1 to move in the longitudinal direction.

[0128] The double-motor reducer 4 and the worm gear lifting machine 3 are connected through a shaft coupling 9.

[0129] The worm gear lifting machine 3 is provided with a speed measuring wheel 10.

[0130] The present embodiment further comprises a lifting scale 14 for controlling the lifting height.

[0131] The double-motor reducer 4 and the worm gear lifting machine 3 are connected through a main motor 5 and an auxiliary motor 6.

[0132] The present embodiment further comprises a displacement control box 7, the displacement control box 7 is provided with a displacement pointer 12, and is connected to the cross beam through a connecting plate 13.

[0133] The worm gear and worm lifting machine 3 is further provided with a hand wheel 15.

[0134] Further, the output end of the worm gear and worm lifting machine 3 is provided with an upper connecting rod 21 and a lower connecting rod 23 and is connected through an adjusting nut 22; a corrugated pipe 26 is sleeved on the lower connecting rod 23 and is connected through a connecting rod flange 24, an upper flange 25, a lower flange 27 and a sealing seat 28. A sector plate connecting rod 30 is connected between the sector plate 1 and the lower connecting rod 23, and the sector plate connecting rod 30 is connected through a small pin shaft 29.

[0135] The upper connecting rod 21 and the lower connecting rod 23 are fixed on the lifting mechanism frame 2, and the worm gear and worm lifting machine 3 is installed on the lifting mechanism frame through the side plate 17. The lifting mechanism frame and the side plate 17 are connected through an I-shaped steel 16. The double-motor speed reducer 4 and the top end of the worm gear and worm lifting machine 3 are fixed on the cross beam 8.

[0136] The worm gear and worm lifting machine 3 is further provided with a protective cover 11. The upper connecting rod 21 and the output end of the worm gear and worm lifting machine 3 are connected through a large pin shaft 20.

[0137] The worm gear and worm lifting machine 3 is connected with the double-motor speed reducer 4 through a synchronous shaft 18 and a speed limiter 19.

[0138] The sector plate lifting mechanism is a prior art structure.

[0139] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art, according to the technical solution and the inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A boiler air preheater sector plate lifting system, characterized in that, Includes the following modules: The laser gap control subsystem is installed on the sector plate of the air preheater and is used to collect the gap signal value between the sector plate and the rotor flange surface. Temperature control subsystem is used to collect flue gas outlet temperature; The lifting interval preset subsystem is used to preset several lifting intervals according to a set value. The lifting intervals include: a first lifting interval, a second lifting interval, a third lifting interval, and a fourth lifting interval. A direct lift control subsystem, connected to a lift interval preset subsystem, is used to determine a direct lift control strategy based on the relationship between the current gap signal value and the lift interval. If the current gap signal value is in the first boosting range, no boosting is performed; if the current gap signal value is in the second boosting range, the first direct boosting control scheme is executed; if the current gap signal value is in the third boosting range, the second direct boosting control scheme is executed; if the current gap signal value is in the fourth boosting range, the third direct boosting control scheme is executed. If the current gap signal value is in the second boosting range, then the first direct boosting control scheme is executed, including: The current gap signal value is sampled three times consecutively. It is determined whether the current gap signal value sampled three times consecutively is within the second lifting interval. If not, the first direct lifting sub-step size is determined based on the latest sampled current gap signal value. If so, the average gap signal value is determined based on the current gap signal value of three consecutive samples, and the first difference between the average gap signal value and the set value is determined. If the first difference is less than or equal to 2mm, no increase is performed. If the first difference is greater than 2mm, a preset initial lifting step size and a reference deformation height at the top of the rotor are established, and the following judgment conditions are designed: The flue gas outlet temperature fluctuation range within the historical time window is >5℃; Within the historical time window, the deformation height at the top of the rotor is ≥ 10% of the reference deformation height at the top of the rotor; If any of the above judgment conditions are met, the first direct lifting step size is determined based on the flue gas outlet temperature fluctuation range, the rotor top deformation height, and the initial lifting step size; if none of the above judgment conditions are met, the initial lifting step size is taken as the first direct lifting step size. If the current gap signal value is in the third boost interval, then the second direct boost control scheme is executed, including: Determine the initial gap signal value; Based on the current gap signal value, a new gap signal value is acquired every 10 seconds; if two consecutive new gap signal values ​​are greater than the initial gap signal value, the acquisition frequency of the new gap signal value is adjusted to 5 seconds. A second difference is determined 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 size is used as the second direct lifting step size. If the second difference is greater than or equal to 3.5mm, the initial lifting step size is corrected based on the second difference to obtain a correction value, and the correction value is used as the second direct lifting step size. The gap signal value is adjusted by the second direct increase step size to obtain the adjusted gap signal value. The increase is stopped when the adjusted gap signal value increases to the second increase range or reaches the preset maximum number of increases. If the current gap signal value is in the fourth boost interval, then the third direct boost control scheme is executed, including: Determine whether the current gap signal value is in the fourth boosting range and has lasted for 5 minutes. If yes, enter the emergency boosting mode; otherwise, execute the second direct boosting control scheme. In the emergency boost mode, the following perturbation conditions were designed: The flue gas outlet temperature fluctuation range within the historical time window is >8℃; Within the historical time window, the deformation height at the top of the rotor is ≥ 15% of the reference deformation height at the top of the rotor; If any of the above disturbance conditions are met, the flue gas outlet temperature fluctuation range is obtained in real time. Based on the flue gas outlet temperature fluctuation range and the deformation height of the rotor top, the dynamic lifting step size is determined and the lifting is carried out. If none of the above disturbance conditions are met, the initial lifting step size is used as the third direct lifting step size and the lifting is carried out. After each action, the flue gas outlet temperature is acquired in real time. If the current flue gas outlet temperature is in the first target temperature range, the fan plate is raised by 10mm; if the flue gas outlet temperature is in the second target temperature range, the fan plate is raised by another 5mm. The raising operation is continued until the current gap value is lower than 140% of the set value, thus completing this round of rapid continuous raising control. An indirect boosting control subsystem is connected to the laser gap control subsystem and the temperature control subsystem. When the laser gap control subsystem fails, an indirect boosting control strategy is determined based on the flue gas outlet temperature. An 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 / the indirect lifting control strategy.

2. The boiler air preheater sector plate lifting system according to claim 1, characterized in that: The gap signal value range less than 70% of the set value is defined as the first lifting interval; the gap signal value range greater than or equal to 70% and less than or equal to 110% of the set value is defined as the second lifting interval; the gap signal value range greater than 110% and less than or equal to 140% of the set value is defined as the third lifting interval; and the gap signal value range greater than 140% of the set value is defined as the fourth lifting interval. The lifting step size of the first, second, third, and fourth lifting intervals is in the following relationship: lifting step size of the first lifting interval < lifting step size of the second lifting interval < lifting step size of the third lifting interval < lifting step size of the fourth lifting interval.

3. The boiler air preheater sector plate lifting system according to claim 1, characterized in that: When the gap signal value is 0, the indirect enhancement control strategy is determined based on the flue gas outlet temperature, including: determining whether the fault in the laser gap control subsystem is the first fault; if so, the basic enhancement scheme is started; if not, the intelligent enhancement enhancement scheme is started.

4. The boiler air preheater sector plate lifting system according to claim 3, characterized in that: The specific basic upgrade plan is as follows: When the laser gap control subsystem experiences its first failure, 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. The flue gas outlet temperature deviation is determined based on the historical baseline value of the flue gas outlet temperature and the real-time temperature of the flue gas outlet. If the flue gas outlet temperature deviation is greater than 5℃, the rotary air preheater is judged to have abnormal air leakage. The fan-shaped plate is raised by 5mm. After the raising is completed, wait for 5 minutes and then re-determine whether the rotary air preheater has abnormal air leakage and whether it needs to be raised. The raising is stopped when the cumulative raising amount reaches 15% of the initial gap signal value.

5. The boiler air preheater sector plate lifting system according to claim 3, characterized in that: The specific intelligent enhancement scheme is as follows: At least two trigger threshold ranges are preset: a first-level trigger threshold range and a second-level trigger threshold range, with the first-level trigger threshold range being smaller than the second-level trigger threshold range; each trigger threshold range includes an increment step and a trigger time interval; Determine whether the current flue gas outlet temperature deviation falls within the first-level or second-level trigger threshold range. Perform a lifting operation on the sector plate according to the lifting step size within the trigger threshold range it belongs to. After waiting for the trigger time interval, re-determine the current flue gas outlet temperature deviation and perform the lifting operation again. Continue this process until the re-determined current flue gas outlet temperature deviation is less than the first-level trigger threshold range and remains unchanged for 10 minutes. Then, stop the lifting operation and maintain the current gap state.

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