Automatic purging control method and system for differential pressure transmitter of coal-fired power generation unit

Abstract

The invention discloses an automatic purging control method and system for a differential pressure transmitter of a coal-fired power generation unit. According to the method, a comprehensive blockage index is set for each measuring point and is used for quantitatively evaluating the current blockage risk of the measuring point, and the two dimensions of'current state 'and'change trend' can be fused into a continuous and quantitative index, so that the system not only can identify the blockage, but also can evaluate the severity and urgency of the blockage; and a data basis is provided for subsequently realizing graded alarm or differential purging strategies, so that the blockage state can be automatically and intelligently judged, purging is quickly executed, and quantitative verification is performed on the effect.

Description

Technical Field

[0001] This application relates to the field of coal-fired power plant boiler technology, and more specifically, to an automatic purging control method and system for differential pressure transmitters of coal-fired power generating units. Background Technology

[0002] In thermal power generation, primary air plays a crucial role in conveying pulverized coal into the furnace. Accurate measurement of its volume directly impacts boiler air distribution optimization, combustion efficiency, and operational safety and stability. Currently, the differential pressure method is commonly used to measure primary air volume. This involves installing a differential pressure device in the primary air duct and using a differential pressure transmitter to convert the measured differential pressure signal into a standard electrical signal, thereby calculating the air volume. This measurement result serves as a key parameter in the combustion control logic, forming the foundation for achieving efficient and clean combustion.

[0003] In existing technologies, to address the blockage of pressure taps and pressure lines caused by coal dust, fly ash, and unburned carbon particles carried in the primary airflow, maintenance primarily relies on periodic manual purging. Specific procedures include obtaining work permits, removing measuring points, disassembling pipelines, connecting compressed air for purging, cleaning accumulated ash, and reinstalling and reactivating the measuring points. While this method can temporarily restore measurement functionality to some extent, it is essentially a passive, experience-based maintenance approach, highly dependent on human intervention. However, existing maintenance methods have several drawbacks: First, maintenance is inherently blind and delayed. Fixed-cycle preventative purging cannot dynamically respond to boiler load fluctuations and coal quality changes, easily leading to insufficient or excessive maintenance; while fault-driven purging has a delayed response, and measurement distortion has caused prolonged interference to the control system. Second, the operation process is cumbersome and time-consuming. A single operation requires multiple people and goes through multiple approval and operational steps, taking tens of minutes to several hours, making rapid response and immediate handling difficult. Third, practical operation is limited, requiring the unit to be in a low-load window. It is essential to ensure that the completion of the purging process does not affect the unit's load increase requirements. Fourth, the risk of misoperation during the operation is significant. Incorrectly disassembling or forcing measurement points can cause drastic fluctuations in airflow, increasing the risk of malfunction and reducing system reliability. Fifth, the harsh operating environment, with high temperatures, high dust levels, and high noise levels, increases personnel safety risks. Frequent disassembly and assembly can also easily damage the sealing structure, causing damage to interface threads, introducing potential leakage hazards, and reducing the long-term reliability of the system. Sixth, the lack of a scientific, closed-loop effect verification mechanism means that the thoroughness of the purging relies on subjective judgment and visual inspection, making quantitative assessment impossible. This can easily lead to residual dirt and repeated blockages.

[0004] Therefore, there is an urgent need for a primary air volume measurement and maintenance system that can be automated, intelligent, efficient, and provide feedback to overcome the above-mentioned shortcomings and improve the stability and safety of boiler operation. Summary of the Invention

[0005] The main objective of this application is to provide an automatic purging control method and system for differential pressure transmitters in coal-fired power generating units, which can automatically and intelligently determine the blockage status, quickly perform purging, and quantitatively verify the effect.

[0006] According to a first aspect of this application, an automatic purging control method for a differential pressure transmitter in a coal-fired power generation unit is provided, comprising the following steps: Step 1, simultaneously acquiring real-time differential pressure measurements from at least three adjacent measuring points within the sampling pipeline of the differential pressure transmitter, preprocessing each real-time differential pressure measurement to obtain a processed real-time differential pressure value for each measuring point; Step 2, obtaining dynamic reference values ​​for differential pressure at all measuring points based on the processed differential pressure values, and normalizing the deviation of each measuring point based on the processed differential pressure value and the dynamic reference value, to obtain a normalized deviation for each measuring point; obtaining the deviation deterioration rate for each measuring point using the data of the most recent N normalized deviations; Step 3, obtaining a comprehensive blockage index for each measuring point using the normalized deviation and the deviation deterioration rate, and determining when the comprehensive blockage index of a measuring point continuously exceeds a preset trigger threshold, and The system continuously checks for blockages at a preset time point and issues a purging request command. Step four involves a comprehensive assessment of the start / stop conditions. If purging is initiated, the system checks whether the normalized deviation of the measuring point and the real-time operating condition deviation coefficient of the differential pressure processing values ​​of all measuring points are below a set threshold. If not, purging continues for a preset time; if yes, purging stops. Step five involves stopping purging and checking whether the normalized deviation of the measuring point and the real-time operating condition deviation coefficient of the differential pressure processing values ​​of all measuring points are below a set threshold. If not, it returns to step four to continue purging. If the cumulative purging time exceeds a preset upper limit and still does not meet the threshold, purging is forcibly stopped and an alarm is triggered. If yes, purging ends, and the system proceeds to step six. Step six involves the system performing a self-check for faults after purging. If no fault is found, the system determines that purging of the measuring point is complete and put the measuring point into operation. If so, the system performs safeguard operations for the fault state and displays the fault and measuring point status.

[0007] In some embodiments, in step two, the dynamic reference value of the differential pressure at all measuring points is obtained by the following formula: ; in, This is a dynamic reference value for differential pressure, in kPa. Given a sequence of differential pressure values ​​at time t for n measuring points, where n ≥ 3; calculate... At that time, first put the sequence in Sort by ascending or descending order: If n is odd. Let n be the median of n measured data points; if n is even, It is the average of the two middle data points out of n measurement points.

[0008] In some embodiments, in step two, the normalized bias is obtained by the following formula: ; in, Normalized deviation, expressed as a percentage. Let be the preprocessed real-time differential pressure value at time t for the i-th measuring point, where i = 1, 2, 3. .

[0009] In some embodiments, the deviation deterioration rate of each measuring point in step two is obtained by the following formula:

[0010] Specifically, by performing linear regression analysis on the most recent N normalized deviation data, the slope of the fitted straight line is extracted as the deviation deterioration rate. , in units of % / s or % / min. Let N be the most recent N normalized deviation sequences, where N is a preset integer and N≥2.

[0011] In some embodiments, the algorithm for the comprehensive congestion index of each measuring point in step three is as follows:

[0012]

[0013] in, The comprehensive congestion index is given by T, which represents the total time window over the most recent N periods. The weighting coefficients for the deviation at each measuring point. The weighting coefficients for the deviation deterioration rate at each measuring point are used. Based on a preset weighting ratio, the deviation degree and deviation deterioration rate are weighted and summed to obtain the comprehensive blockage index. When... Furthermore, it continuously determines whether the measuring point is blocked within a preset time period.

[0014] In some embodiments, in steps four and five, the real-time operating condition deviation coefficient of the differential pressure processing values ​​at all measuring points is determined. The algorithm is as follows: 2 ; in, This is the real-time operating condition deviation coefficient, in kPa. Processed pressure difference values ​​at each measuring point The average value.

[0015] In some embodiments, step four further includes: before starting the purging, the main control system performs a status position judgment, executes a preset program, and maintains the differential pressure value; step six further includes: after the purging ends, the main control system performs a fault self-check and performs corresponding operations for different situations.

[0016] In some embodiments, the method further includes: when an emergency occurs, cutting off the purging process via a manual emergency stop interface and restoring the data output of real-time differential pressure measurements of all purged measuring points.

[0017] In some embodiments, in step one, the real-time differential pressure measurements are preprocessed by using a Kalman filter algorithm to process the data sequence of the real-time differential pressure measurements at each measuring point.

[0018] According to a second aspect of this application, an automatic purging system for differential pressure transmitters in coal-fired power generating units is provided, applied to the aforementioned automatic purging control method. The system includes: a multi-point measurement unit comprising at least three differential pressure transmitters installed independently at adjacent locations within the measured pipeline; a purging execution unit comprising multiple purging branch lines connected to the pressure tapping lines of each differential pressure transmitter, the multiple purging branch lines being independently controllable for on / off switching; and a central control unit electrically connected to the multi-point measurement unit and the purging execution unit. The central control unit includes: a data receiving module for receiving real-time differential pressure values ​​from each measuring point; a data processing module for preprocessing the real-time differential pressure values, calculating the normalized deviation, deviation deterioration rate, and comprehensive blockage index; a logic judgment module for real-time analysis of the processed data, determining whether blockage has occurred based on preset composite logic conditions; and an execution control module for automatically controlling the purging execution unit to perform purging based on the judgment result, verifying the purging effect in real time, and controlling the state switching and recovery of the entire process.

[0019] The technical solutions provided by the embodiments of this application may include the following beneficial effects: In this application, compared with the prior art, the automatic purging control method according to the present invention: 1) By setting a comprehensive blockage index for each measuring point to quantitatively assess its current blockage risk, the two dimensions of "current state" and "change trend" can be integrated into a continuous and quantitative indicator, enabling the system not only to identify blockages but also to assess their severity and urgency, providing a data foundation for subsequent implementation of graded alarms or differentiated purging strategies. 2) This application combines a complete maintenance process of monitoring, diagnosis, execution, verification, and recovery, achieving full automation and realizing adaptive proactive on-demand maintenance, thereby reducing manual intervention. 3) The measurement, judgment, and execution components are integrated and permanently installed, avoiding problems such as leakage and damage caused by repeated manual disassembly and assembly, improving the reliability and longevity of the measuring device. Through adaptive proactive purging of the measuring points, the reliability and stability of the measuring points are greatly improved. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 A flowchart illustrating the steps of the automatic purging control method for a differential pressure transmitter in a coal-fired power generation unit provided in this application; Figure 2 A system connection diagram for the automatic purging control system of the differential pressure transmitter for a coal-fired power generation unit provided in this application; Figure 3 A schematic diagram of the automatic purging control method provided in this application for automatic purging stop logic flow; Figure 4 A schematic diagram of the system operation logic flow of the automatic purging control method provided in this application. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0024] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0025] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linked," and "socketing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0026] According to a first aspect of this application, an automatic purging control method 100 for a differential pressure transmitter in a coal-fired power generation unit is provided. According to a second aspect of this application, an automatic purging system 200 for a differential pressure transmitter in a coal-fired power generation unit is provided, applied to the aforementioned automatic purging control method 100. Figure 1 The steps of an automatic purging control method 100 for a differential pressure transmitter in a coal-fired power generation unit according to an embodiment of the present invention are shown. Figure 2A schematic diagram of the system connection of an automatic purging control system according to an embodiment of the present invention is shown. The automatic purging control system 200 according to an embodiment of the present invention may include: a multi-point measurement unit, comprising at least three differential pressure transmitters installed independently at adjacent locations within the measured pipeline; a purging execution unit, comprising multiple purging branch lines respectively connected to the pressure tapping lines of each differential pressure transmitter, the multiple purging branch lines being configured to be independently controllable on / off; and a central control unit electrically connected to the differential pressure multi-point measurement unit and the differential pressure purging execution unit.

[0027] The central control unit can be a programmable logic controller (PLC) or a distributed control system (DCS) functional module. The central control unit may include: a data receiving module for receiving real-time differential pressure values ​​from various measuring points; a data processing module for preprocessing the real-time differential pressure values, calculating the normalized deviation, deviation deterioration rate, and comprehensive blockage index; a logic judgment module for analyzing the processed data in real-time and determining whether blockage has occurred based on preset composite logic conditions; and an execution control module for automatically controlling the purging execution unit to perform purging based on the judgment results, verifying the purging effect in real-time, and controlling the state switching and recovery of the entire process.

[0028] Combination Figure 1 and Figure 2 and refer to Figure 4 As shown, the automatic purging control method 100 according to an embodiment of the present invention includes the following steps: Step S1: Simultaneously collect real-time differential pressure measurements from at least three adjacent measuring points within the sampling pipeline of the differential pressure transmitter. Preprocess each real-time differential pressure measurement to obtain the processed real-time differential pressure value for each measuring point.

[0029] In step S1, the central control unit acquires real-time differential pressure measurements from all measuring points synchronously at high frequency and preprocesses these measurements. Preprocessing may include using a Kalman filter algorithm to process the data sequence of real-time differential pressure measurements from each measuring point, thereby eliminating high-frequency noise interference and obtaining a smoothed real-time differential pressure value (e.g., ...). ).

[0030] In this step, a multi-point measurement unit can be installed in the sampling pipeline of the differential pressure transmitter. The multi-point measurement unit can include at least three differential pressure transmitters (denoted as measuring point 1, measuring point 2, measuring point 3... measuring point n or measuring point A, measuring point B, measuring point C...) that are spatially close to each other and independently installed in the sampling pipeline of the differential pressure transmitter under test. These transmitters are used to simultaneously acquire real-time differential pressure measurements at multiple locations to monitor the differential pressure in the sampling pipeline of the differential pressure transmitter in real time.

[0031] Step S2: Obtain the dynamic reference value of differential pressure for all measuring points based on the processed differential pressure values. Normalize the deviation of each measuring point based on the processed differential pressure value and the dynamic reference value to obtain the normalized deviation for each measuring point. Calculate the deviation deterioration rate for each measuring point using the N most recent normalized deviations.

[0032] In step S2, the dynamic reference value of the differential pressure at all measuring points is obtained by the following formula: ; in, This is a dynamic reference value for differential pressure, in kPa. Given a sequence of differential pressure values ​​at time t for n measuring points, where n ≥ 3; calculate... At that time, first put the sequence in Sort by ascending or descending order: If n is odd. Let n be the median of n measured data points; if n is even, It is the average of the two middle data points out of n measurement points.

[0033] For example, when n=3, the processed value of the pressure difference at 3 measuring points at a certain time t is: =1.2kPa, =1.5kPa, =1.4 kPa. First, sort the above data: 1.2, 1.4, 1.5. Take the middle number, that is =1.4 kPa. This is the dynamic reference value of the pressure difference at this point. =1.4 kPa.

[0034] By using the median rather than the average value of the real-time differential pressure processing values ​​at each measuring point through the above steps, the influence of a single measuring point that has been severely blocked on the dynamic reference value of differential pressure (i.e., the baseline value) can be effectively eliminated, thereby ensuring that the dynamic reference value of differential pressure can reflect the true pressure state of the measured fluid with high fidelity.

[0035] In another scenario, if the differential pressure processing values ​​at the measuring points are irregular over N cycles, causing anomalies in the dynamic reference values ​​of the differential pressure over those N cycles, a sliding algorithm is used to process the differential pressure processing values ​​at each measuring point to stabilize the data. Taking measuring point 1 as an example, the algorithm is as follows: , That is, to calculate the average value of each measuring point 1, 2, 3..., n within a preset time period in real time. As The representative value. For example, if the adjacent calculation period is 5 seconds, then the preset time period can be 3 seconds, and the value within 3 seconds is taken every 1 second interval. Calculate the value This allows for continuous coverage of the sliding interval within 5 seconds.

[0036] In this application, for each measurement point i (i=1, 2, 3, ...), The following two feature parameters are calculated in real time: In step S2, the normalized deviation and the deviation deterioration rate are: Normalized deviation represents the degree of deviation of a measuring point from the dynamic reference value of differential pressure, that is, the "relative deviation ratio" of a single measuring point relative to the normal differential pressure of the entire pipeline. It is a core indicator for quantifying the blockage trend of the area corresponding to the measuring point and provides a basis for subsequent judgment on whether purging is necessary. Specifically, it can be obtained from the following formula: ; in, Normalized deviation, expressed as a percentage. Let be the preprocessed real-time differential pressure value at time t for the i-th measuring point, where i = 1, 2, 3. .

[0037] Through the above steps, after subtracting the dynamic reference value of the differential pressure (i.e., the benchmark value) from the real-time differential pressure processing value, and then normalizing it by dividing it by the dynamic reference value of the differential pressure, the influence of the overall pressure level fluctuation caused by boiler load changes can be eliminated, making it a dimensionless relative deviation index that can be compared across operating conditions.

[0038] The deviation deterioration rate represents the trend of the deviation at a measurement point over time, i.e., its first derivative. In discrete-time systems, this is expressed as the normalized deviation over the most recent N periods. Perform least squares linear regression on the sequence to obtain its slope.

[0039] The rate of deviation degradation at each measuring point is obtained by the following formula:

[0040] in, The deviation deterioration rate is expressed as % / s or % / min. The N most recent normalized deviation sequences; N is a preset integer and N≥2; This is a linear fitting function based on the least squares method, used to fit a straight line to N normalized deviation data points; This is the slope extraction function, used to obtain the slope of the fitted line.

[0041] when >0 and when A value greater than 0 indicates that the blockage at this measuring point is accelerating, meaning that the measuring point is rapidly deviating from its normal state. The magnitude of this value quantifies the urgency of the deterioration. The larger the value, the higher the degree of deterioration at that measuring point. Furthermore, if... The threshold was not reached, but A value greater than 0 can also predict impending severe congestion and allow for early intervention.

[0042] Through the above steps, the core of this formula is to first perform a linear fit on the "normalized deviation sequence of the most recent N periods" (…). ), and then take the slope of the fitted line ( Specifically: the input is the normalized bias over N consecutive periods ( ), corresponding to N time points (each cycle corresponds to a time interval, such as Δt); This will generate linear regression equations for these data (such as...) ); Extract the slope k of the equation, i.e. The unit is % / s or % / min, which represents the "rate of change of deviation over time" (deviation degradation rate). This method calculates the deviation degradation rate. It can extend from the "static current degree of blockage" to the "dynamic trend of blockage development," making blockage judgment more accurate and purging control more timely, avoiding misjudgment or delayed treatment. It also provides a basis for subsequent judgments on whether purging is necessary.

[0043] Step S3: Obtain the comprehensive blockage index of each measuring point by the normalized deviation and the deviation deterioration rate of each measuring point. When the comprehensive blockage index of a certain measuring point continuously exceeds the preset trigger threshold and continues for a preset time period, it is determined that the measuring point is blocked and a purging request command is issued.

[0044] In step S3, the algorithm for the comprehensive congestion index at each measuring point is as follows:

[0045]

[0046] in, The comprehensive congestion index is given by T, which represents the total time window over the most recent N periods. The weighting coefficients for the deviation at each measuring point reflect the level of attention paid to the current deviation status. The weighting coefficients for the rate of deviation deterioration at each measuring point reflect the level of concern regarding future deterioration trends. And it is a pre-defined non-negative real number. When Furthermore, it continuously determines whether the measuring point is blocked within a preset time period.

[0047] In this application, examples are provided using the formulas described above: For example, =0.5% / s means "the normalized deviation of this measurement point increases by 0.5% every second". T is defined as "the total time window of the most recent N periods" (for example, N=5 periods, each period sampling interval Δt=2s, then T=5×2=10s), and the unit is seconds (or minutes). The unit calculation provides a clear understanding of this. (% / s) × T(s) = (%), the unit changed from "rate of change (slope unit)" to "absolute increment (percentage unit)". This results in the rate of deviation deterioration occurring within the time window T. The "cumulative increase" in the normalization bias caused by this.

[0048] In this application, a comprehensive congestion index is set for each measuring point i to quantitatively assess its current congestion risk. When the comprehensive congestion index of any measuring point i... If the threshold is exceeded for an extended period of time, the system determines that the measurement point is blocked and generates a purging command for that specific measurement point.

[0049] Through the above steps, this algorithm integrates the two dimensions of "current state" and "change trend" into a continuous and quantitative indicator, enabling the system not only to identify blockages but also to assess their severity and urgency, providing a data foundation for subsequent implementation of graded alarms or differentiated purging strategies (such as adjusting purging pressure and duration).

[0050] In this application, during and after the purging process, the central control unit continuously monitors the status of the purged measurement points and verifies the adaptive effect. Specifically: Step 4 (S4): Make a comprehensive judgment based on the start-up conditions (e.g., whether the boiler load is stable, whether it is in the ignition stage, whether there are related interlocking actions, etc.). If purging is started, during the purging process, determine whether the normalized deviation of the measuring point and the real-time operating condition deviation coefficient of the differential pressure processing value of all measuring points meet the requirement of being lower than the set threshold. If not, continue purging for a preset time; if yes, stop purging.

[0051] In this application, the verification of the normalized deviation of the measuring point and the real-time operating condition deviation coefficient of the differential pressure processing value of all measuring points must be carried out after purging is stopped and the pressure is allowed to stabilize.

[0052] Please refer to Figure 3 As shown, step S4 also includes: before starting the purging, the main control system performs a status check, executes a preset program, and maintains the differential pressure value.

[0053] After generating the purging requirement command, the main control system performs status status checks: 1) By switching the execution path, the output values ​​of the measuring points (or all relevant measuring points) that need to be purged are maintained at the last valid value before purging. This method can avoid disturbances to the upper control loops such as boiler combustion caused by drastic pressure changes during the purging process.

[0054] 2) The purging execution unit includes multiple purging branch lines connected to the pressure tapping lines of each differential pressure transmitter. These purging branch lines are configured to be independently controlled by solenoid valves. The central control unit sends an "open" command to the solenoid valve on the purging branch line corresponding to the diagnosed blockage point, introducing compressed air for high-speed purging.

[0055] Step 5 (S5): After stopping purging, determine whether the normalized deviation of the measuring point and the real-time operating condition deviation coefficient of the differential pressure processing value of all measuring points are below the set threshold. If not, return to step 4 to continue purging. If the cumulative purging time exceeds the preset upper limit and still does not meet the requirement, force stop purging and alarm. If the requirement is met, end purging and proceed to step 6.

[0056] Similarly, in this application, the verification of the normalized deviation of the measuring point and the real-time operating condition deviation coefficient of the differential pressure processing value of all measuring points must be carried out after purging is stopped and the pressure is allowed to stabilize.

[0057] In steps S4 and S5, the real-time operating condition deviation coefficient (i.e., standard deviation formula) of the differential pressure processing values ​​at all measuring points is determined. The algorithm is as follows: 2 ; in, This is the real-time operating condition deviation coefficient, in kPa. Processed pressure difference values ​​at each measuring point The average value.

[0058] In the above steps, determining whether the normalized deviation of the measuring point is less than a set value (the range can be limited according to specific circumstances) ensures that the purged measuring point has returned to the "current true operating condition" level defined by other healthy measuring points, rather than a fixed "normal value range" that may no longer be applicable to the current operating condition. The real-time operating condition deviation coefficient of the smoothed real-time differential pressure values ​​of all measuring points is also considered. The value drops back to below the preset consistency threshold (the threshold range can be limited depending on the specific circumstances).

[0059] Through the above steps, the real-time operating condition deviation coefficient of the differential pressure processing values ​​of all measuring points in this application can effectively avoid misjudgment. Normal operating condition changes such as boiler load reduction will cause all measuring points to decrease synchronously. At this time, the real-time operating condition deviation coefficient will remain unchanged or decrease (converge). The composite logic of this invention can effectively eliminate false triggers caused by such global operating condition changes, and the decision accuracy is high.

[0060] Furthermore, if the purging execution time exceeds a preset maximum purging time limit (which can be set according to specific circumstances) and the purging success determination condition is still not met, the system will automatically stop purging, the data will remain in the "hold" state, and an alarm message "Purging failed, please check manually" will be sent to the operator station.

[0061] Step S6: After purging is completed, the system performs a self-check to see if there is a fault. If not, it determines that the purging of the measuring point is completed and put the measuring point into operation; if so, the system performs a protection operation for the fault status and displays the fault and measuring point status.

[0062] Furthermore, step six S6 also includes: after the purging is completed, the main control system performs a fault self-check and executes corresponding operations for different situations.

[0063] During the above steps, the data at the measuring point remains in a "hold" state throughout the purging process, and a "purging in progress" status message is sent to the operator station. Once the purging success criteria are met, the central control unit immediately closes the corresponding valve, releases the data "hold" state in the DCS, restores the real-time measured differential pressure value at the measuring point, re-enters closed-loop control, and sends a "purging completed" status message to the operator station.

[0064] In the above steps, if the system determines that other faults exist, such as boiler burner equipment malfunctions (including ignition failure, flameout failure, unstable combustion), differential pressure transmitter malfunctions, or primary air duct blockages, these are all faults that require immediate alarm and will trigger an alarm message requesting manual inspection.

[0065] In some embodiments, the method further includes: when an emergency occurs, cutting off the purging process via a manual emergency stop interface and restoring the data output of real-time differential pressure measurements of all purged measuring points.

[0066] In the above method, if any abnormal operating conditions occur in the unit or related equipment of the coal mill during the purging operation, and the operator decides that an immediate stop is necessary, a "Manual Emergency Stop" button can be provided on the DCS operation screen. After the operator presses the button, an emergency stop signal is issued, which has the highest response priority. The central control unit immediately closes the corresponding valves, releases the data "hold" state in the DCS, restores real-time measurement at the measuring points, and re-enters closed-loop control. It also sends a status message "Purge completed" to the operator station.

[0067] After the equipment malfunctions and repairs are completed, there is a "Fault Confirmation" button on the DCS operation screen. When the operator presses the button, a fault confirmation signal is sent. The system performs a self-check of the daily situation and checks the status of the measuring points. After confirming that there are no errors, the abnormality prompt is cleared.

[0068] In summary, compared with the prior art, the automatic purging control method 100 and system 200 according to embodiments of the present invention have the following significant advantages: 1) By setting a comprehensive blockage index for each measuring point to quantitatively assess its current blockage risk, the two dimensions of "current status" and "change trend" can be integrated into a continuous and quantitative indicator. This enables the system to not only identify blockages but also assess their severity and urgency, providing a data foundation for subsequent implementation of graded alarms or differentiated purging strategies (such as adjusting purging pressure and duration).

[0069] 2) In this application, the real-time operating condition deviation coefficient of the differential pressure processing values ​​of all measuring points can effectively avoid misjudgment. Normal operating condition changes such as boiler load reduction will cause all measuring points to decrease synchronously. At this time, the real-time operating condition deviation coefficient will remain unchanged or decrease (converge). The composite logic of this invention can effectively eliminate false triggers caused by such global operating condition changes, and the decision accuracy is high.

[0070] 3) This application integrates a complete maintenance process of monitoring, diagnosis, execution, verification, and recovery, achieving full automation and realizing adaptive, proactive, and on-demand maintenance, thereby reducing manual intervention. That is, no intervention is required at the measuring points during unit operation; the entire process is achieved through logical adaptive proactive operation, realizing seamless maintenance of the measuring points, reducing the possibility of human intervention, and shortening the single purging time from tens of minutes to seconds, resulting in extremely rapid maintenance response.

[0071] 4) The purging effect is verified in a closed loop by using quantitative data indicators (recovery to the normal range, real-time operating condition deviation coefficient approaching zero), which ensures the reliability and consistency of maintenance quality.

[0072] 5) The data retention function during purging shields the upper control system from interference from lower-level maintenance operations, ensuring the stable operation of the boiler main system. It reduces the operational pressure of the purging equipment on the unit, creating a completely isolated and reliable equipment system.

[0073] 6) Integrating and permanently installing the measurement, judgment, and execution components avoids problems such as leakage and damage caused by repeated manual disassembly and assembly, thus improving the reliability and longevity of the measuring device. Adaptive active purging of the measuring points greatly enhances their reliability and stability.

[0074] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0075] Obviously, those skilled in the art should understand that the various units or steps of this application described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device, or fabricating them separately as individual integrated circuit modules, or fabricating multiple modules or steps into a single integrated circuit module. Thus, this application is not limited to any particular combination of hardware and software.

[0076] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An automatic purging control method for a differential pressure transmitter in a coal-fired power generation unit, characterized in that, Includes the following steps: Step 1: Simultaneously collect real-time differential pressure measurements from at least three adjacent measuring points within the sampling pipeline of the differential pressure transmitter. Preprocess each real-time differential pressure measurement to obtain the processed real-time differential pressure value for each measuring point. Step 2: Obtain the dynamic reference value of differential pressure for all measuring points based on the differential pressure processing value of each measuring point. Based on the differential pressure processing value and the dynamic reference value of differential pressure for each measuring point, normalize the deviation of each measuring point to obtain the normalized deviation of each measuring point. Obtain the deviation deterioration rate of each measuring point through the data of the most recent N normalized deviations of each measuring point. Step 3: Obtain the comprehensive blockage index of each measuring point by the normalized deviation and the deviation deterioration rate of each measuring point. When the comprehensive blockage index of a certain measuring point continuously exceeds the preset trigger threshold for a preset time period, it is determined that the measuring point is blocked and a purging request command is issued. Step 4: Make a judgment based on the overall start-up conditions. If purging is started, during the purging process, determine whether the normalized deviation of the measuring point and the real-time operating condition deviation coefficient of the differential pressure processing value of all measuring points meet the requirements of being lower than the set threshold. If not, continue purging for a preset time. If so, stop blowing; Step 5: After stopping purging, determine whether the normalized deviation of the measuring point and the real-time operating condition deviation coefficient of the differential pressure processing value of all measuring points are below the set threshold. If not, return to step 4 to continue purging. If the cumulative purging time exceeds the preset limit and the condition is still not met, the purging will be forcibly stopped and an alarm will be triggered; if the condition is met, the purging will end and the process will proceed to step six. Step 6: After the purging is completed, the system performs a self-check for faults. If no fault is found, the purging of the measuring point is completed and the measuring point is put into operation. If a fault is found, the system performs a protection operation for the fault status and displays the fault and measuring point status.

2. The automatic purging control method according to claim 1, characterized in that, In step two, the dynamic reference value of the differential pressure at all measuring points is obtained by the following formula: ; in, This is a dynamic reference value for differential pressure, in kPa. Given a sequence of differential pressure values ​​at time t for n measuring points, where n ≥ 3; calculate... At that time, first put the sequence in Sort by ascending or descending order: If n is odd. Let n be the median of n measured data points; if n is even, It is the average of the two middle data points out of n measurement points.

3. The automatic purging control method according to claim 2, characterized in that, In step two, the normalized deviation is obtained by the following formula: ； in, Normalized deviation, expressed as a percentage. Let be the preprocessed real-time differential pressure value at time t for the i-th measuring point, where i = 1, 2, 3. .

4. The automatic purging control method according to claim 3, characterized in that, In step two, the deviation deterioration rate of each measuring point is obtained by the following formula: ； Specifically, by performing linear regression analysis on the most recent N normalized deviation data, the slope of the fitted straight line is extracted as the deviation deterioration rate. The unit is % / s or % / min; Let N be the most recent N normalized deviation sequences, where N is a preset integer and N≥2.

5. The automatic purging control method according to claim 4, characterized in that, In step three, the algorithm for the comprehensive congestion index at each measuring point is as follows: in, The comprehensive congestion index is given by T, which represents the total time window over the most recent N periods. The weighting coefficients for the deviation of each measuring point. The weighting coefficients for the deviation deterioration rate at each measuring point are used. Based on the preset weighting ratio, the deviation degree and the deviation deterioration rate are weighted and summed to obtain the comprehensive blockage index. when Furthermore, it continuously determines whether the measuring point is blocked within a preset time period.

6. The automatic purging control method according to claim 3, characterized in that, In step four, the real-time operating condition deviation coefficient of the differential pressure processing values ​​at all measuring points is determined. The algorithm is as follows: 2 ; in, This is the real-time operating condition deviation coefficient, in kPa. Processed pressure difference values ​​at each measuring point The average value.

7. The automatic purging control method according to claim 1, characterized in that, Step four also includes: before starting the purging, the main control system performs a status check, executes a preset program, and maintains the differential pressure value; Step six also includes: after the purging ends, the main control system performs a fault self-check and performs corresponding operations for different situations.

8. The automatic purging control method according to claim 1, characterized in that, Also includes: In the event of an emergency, the purging process is cut off via the manual emergency stop interface, and the real-time differential pressure measurement data output of all purged measuring points is restored.

9. The automatic purging control method according to claim 1, characterized in that, In step one, the real-time differential pressure measurements are preprocessed by using a Kalman filter algorithm to process the data sequence of the real-time differential pressure measurements at each measuring point.

10. An automatic purging system for a differential pressure transmitter in a coal-fired power generation unit, applied to the automatic purging control method according to any one of claims 1 to 9, characterized in that, include: A multi-point measurement unit comprising at least three differential pressure transmitters installed independently at adjacent locations within the pipeline being measured; The purging execution unit includes multiple purging branch lines that are connected to the pressure tapping lines of each differential pressure transmitter, and the multiple purging branch lines are configured to be independently controllable on / off. as well as, A central control unit, which is electrically connected to the multi-point measurement unit and the purging execution unit, includes: a data receiving module, which is used to receive the real-time differential pressure value of each measuring point; The data processing module is used to preprocess the real-time differential pressure value, calculate the normalized deviation, deviation deterioration rate, and comprehensive blockage index; the logic judgment module is used to analyze the processed data in real time and determine whether blockage has occurred based on preset composite logic conditions; the execution control module is used to automatically control the purging execution unit to perform purging based on the judgment result, verify the purging effect in real time, and control the state switching and recovery of the entire process.

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