A method for detecting and automatically handling boiler shut-off coal

Abstract

The application discloses a boiler blocked coal detection and automatic processing method. In order to overcome the problem that the completeness of signals is insufficient in the detection of blocked coal, and the problem that the single signal processing leads to inaccurate judgment of the blocked coal, and the problem that effective automatic processing is difficult to be performed when the blocked coal occurs, the application adopts direct signals to make branch pre-judgment, and adopts fused signals to make overall final judgment, improves the effectiveness and accuracy of the detection basis for the occurrence of the blocked coal, and performs reasonable automatic processing of the blocked coal according to signal data.

Description

Technical Field

[0001] This invention relates to the field of automatic control of thermoelectric systems, and more particularly to a method for detecting and automatically handling boiler coal blockage and failure. Background Technology

[0002] In the production process of thermal power plants, boilers, as one of the three main units, are crucial equipment. Among them, circulating fluidized bed boilers have experienced rapid development in recent years due to their significant superior performance, and their application has expanded from small boilers to large power plant boilers with capacities roughly equivalent to traditional pulverized coal boilers. The coal feeding system of a circulating fluidized bed boiler is an important component.

[0003] The coal required for combustion in a boiler enters the furnace through the coal feeding system, playing a crucial role in the safe and economical operation of the boiler. However, frequent malfunctions in the coal feeding system cause significant problems for the stable operation of the boiler. Among these, coal blockage and interruption are the most common and a common challenge for boiler operation and maintenance personnel. When the boiler coal feeding system experiences blockage or interruption, it can lead to a reduction in the amount of coal fed into the boiler, causing a sudden drop in load and affecting production; in severe cases, it can cause the boiler to shut down completely, or even extinguish, impacting the power grid and resulting in economic losses.

[0004] While the industry has accumulated experience over the years and developed some methods and technologies that can approximate the detection of coal blockage and interruption, these methods are still limited by insufficient signal completeness and simplistic signal processing. Currently, there are few engineering-efficient solutions to address this problem. Furthermore, while ensuring relatively accurate detection of coal blockage and interruption, simultaneously establishing interconnections with the combustion automatic control system to achieve a smooth transition between coal feeding and air distribution is also a pressing issue that needs to be addressed.

[0005] For example, a "Method for Detecting Coal Cut-off in a Circulating Fluidized Bed Boiler" disclosed in Chinese patent literature, publication number CN104469284B, includes an alarm, a memory, m cameras respectively installed at the coal outlets of m coal bunkers in the boiler, and a controller electrically connected to various electrical components in the boiler. The controller is electrically connected to the alarm, the memory, and each camera. This invention trains a neural network to detect and judge relevant data, using real-time oxygen content and other data as the basis for determining whether coal cut-off has occurred. However, the application of data is relatively simple, and there is no pre-processing step for coal cut-off; it only serves as an alarm. Summary of the Invention

[0006] This invention primarily addresses the issues of accuracy and timeliness in judging coal blockage and interruption due to the overly simplistic processing of related signals in existing technologies, as well as the difficulty in effectively and automatically handling coal blockage and interruption when they occur. It provides a method for detecting and automatically handling coal blockage and interruption in boilers.

[0007] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions:

[0008] This invention includes the following steps:

[0009] S1. Predict the blockage and interruption of coal supply based on direct signals, using oxygen content signals as the core judgment data, and calculate the fusion signal by combining relevant information;

[0010] S2. Based on the real-time data of the fused signal, make anomaly judgments, make an overall final judgment on coal blockage, assess the degree of coal blockage, and analyze the causes of coal blockage.

[0011] S3. Based on the predicted branch blockage and the overall final judgment results, automatically process the blockage and issue a blockage alarm.

[0012] By making real-time judgments on direct and fused signals, the accuracy and timeliness of coal blockage and interruption judgments are effectively improved. Automatic handling of coal blockage and interruption when it occurs can reduce losses.

[0013] Preferably, the direct signals include the branch feeder flow rate and the branch coal-spreading air pressure, which are correlated with the total feeder opening MV. gm The signal abrupt change caused by the coal feeder regulation is eliminated by fusion. Assume the direct signal of this branch is V. direct The fused expression is as follows:

[0014]

[0015] Performing a relatively coarse fusion calculation on the direct signal to make branch prediction can increase the basis for judging coal blockage and improve the efficiency of judging whether coal blockage has occurred. Furthermore, when coal blockage is severe, branch prediction can directly determine whether coal blockage has occurred.

[0016] Preferably, the relevant information includes the fan air volume and the total opening degree of the coal feeder, and the fusion expression of the fused signal is:

[0017]

[0018] For signal fusion, For oxygen levels, MV fir For primary fan air volume signal, MV sec For secondary fan air volume signal, MV gm This refers to the total opening degree of the coal mining machine.

[0019] The fusion signal is based on the oxygen content signal and combines the total opening information of the primary air fan, secondary air fan and coal feeder to eliminate the oxygen content fluctuation caused by active combustion adjustment, thereby effectively increasing the accuracy and timeliness of the judgment data.

[0020] Preferably, the anomaly detection includes amplitude exceeding the limit detection and speed exceeding the limit detection, wherein the speed exceeding the limit detection includes the following steps:

[0021] S2.1. Establish an anomaly database based on several manually calibrated speed anomalies, and calculate the dynamic anomaly speed radius based on the speed amplitude of the anomalies;

[0022] S2.2. Compare the real-time signal velocity vector with the dynamic abnormal velocity radius to determine whether the current real-time signal velocity is abnormal;

[0023] S2.3. Update the real-time signal velocity vector and enter the abnormal point data into the abnormal database for correction of abnormal velocity values.

[0024] Using the dynamic anomaly velocity radius as a comparison object for the real-time signal velocity vector effectively increases the accuracy of the comparison. Furthermore, adding the data of the anomaly points to the database can effectively correct errors.

[0025] Preferably, the formula for calculating the dynamic abnormal velocity radius is:

[0026]

[0027] R is the radius of the dynamic anomaly velocity, and n is the number of manually calibrated data points. V is the average signal velocity over a time interval near each outlier point. i Anomaly point speed.

[0028] The dynamic abnormal velocity radius reduces errors and noise by averaging the signal velocities of multiple abnormal points, improving the accuracy of the abnormal velocity radius. It is then compared with the real-time signal velocity vector to determine whether there is a coal feeding deviation in the entire fluidized bed circuit.

[0029] Preferably, the formula for calculating the real-time signal velocity vector is:

[0030] Δy(k)=y(k)-y(kT scan )

[0031] T scan Let k be the vector length, k be the current time, Δy(k) be the real-time signal velocity vector, y(k) be the current signal velocity, and y(kT) be the vector length. scan ) for T scan Signal speed before the specified time period.

[0032] Preferably, the automatic coal blockage and interruption treatment includes the following steps:

[0033] S3.1. Obtain the branch road prediction and overall final judgment results of the blocked coal supply and conduct a comprehensive evaluation. After evaluation, the results are divided into 8 states, which are labeled with 1-8 respectively.

[0034] S3.2. Adjust the coal feed output and air distribution in real time according to the comprehensive evaluation results;

[0035] S3.3. Repeat steps S3.1 and S3.2 above until the effects of the coal blockage are eliminated.

[0036] The comprehensive assessment effectively differentiated the response plans and made corresponding real-time adjustments to the coal feed output and air distribution volume based on different response plans, thereby improving the effectiveness of automatic coal blockage and interruption handling.

[0037] Preferably, the real-time adjustment includes coal output balancing and air distribution suspension. The coal output balancing distributes a given balancing component to each step of the normal branch until the required balancing component is fully distributed. The air distribution suspension automatically suspends the oxygen circuit, bed temperature circuit, and bed pressure circuit.

[0038] Coal output balancing distributes the impact of blocked coal branches to other normal branches, and with appropriate air distribution measures, effectively eliminates the harmful effects of blocked coal branches on the entire system.

[0039] Preferably, during the real-time adjustment process, the real-time adjustment time is recorded, and the measurement frequencies of the direct and fused signals are corrected based on the time of each single real-time adjustment process. Since the evaluation results after comprehensive assessment and the required adjustment values ​​differ, the required adjustment time varies. Because a fixed adjustment time cannot meet the immediacy and effectiveness requirements of real-time signal measurement, the signal measurement frequency needs to be changed according to the adjustment process time.

[0040] Preferably, the amplitude limit exceedance judgment is based on manually calibrated amplitude limits to determine whether coal blockage has occurred. If either the amplitude limit exceedance judgment or the speed limit exceedance judgment indicates coal blockage, it means that coal blockage has occurred in the boiler. By using both amplitude and speed limit exceedance criteria, coal blockage can be detected both suddenly and gradually, and the exceedance data can assist in determining the degree of coal blockage.

[0041] The beneficial effects of this invention are:

[0042] 1. This invention employs signal fusion technology, which effectively shields the interference of non-decision factors and can more directly reflect the influence of the information to be determined. The branch prediction of coal blockage and the overall final judgment of coal blockage can provide timely and accurate monitoring and location when a coal blockage occurs in the boiler.

[0043] 2. The automatic coal blockage and interruption handling mechanism of the present invention, based on the accurate coal blockage and interruption detection stage, simultaneously completes the balancing of coal feed branches and the suspension of air distribution. It can effectively connect the actions of the boiler combustion optimization system, effectively shield the control system abnormalities caused by system abnormalities during the occurrence and recovery of coal blockage and interruption, minimize the impact of coal quantity fluctuations on combustion in the furnace, greatly improve the smooth transition capability of the system in abnormal states, and enhance the robustness of the system. Attached Figure Description

[0044] Figure 1 This is a flowchart of a boiler coal blockage detection and automatic handling method according to the present invention.

[0045] Figure 2 This is a flowchart of a boiler coal blockage detection method according to the present invention.

[0046] Figure 3 This is a flowchart of a real-time detection method for abnormal speed signal changes in coal blockage and interruption in a boiler coal blockage and interruption detection and automatic processing method according to the present invention.

[0047] Figure 4 This is a flowchart of the coal blockage balance treatment method of the boiler coal blockage detection and automatic treatment method of the present invention.

[0048] Figure 5 This is a comprehensive analysis list of coal blockage alarms for a boiler coal blockage detection and automatic processing method according to the present invention. Detailed Implementation

[0049] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0050] Example:

[0051] This embodiment provides a method for detecting and automatically handling boiler coal blockage, such as... Figure 1 As shown, it includes a coal blockage detection and automatic processing system, a manual on-site coal blockage clearing and handling system, a boiler combustion optimization control system, and a circulating fluidized bed boiler system.

[0052] The coal blockage detection and automatic handling system obtains coal blockage information from the circulating fluidized bed boiler system and performs calculations and judgments. If coal blockage is detected, it notifies manual on-site clearing and handling of the coal blockage. The system also automatically handles the coal blockage through the boiler combustion optimization control system and adjusts the quantities of various materials input to the circulating fluidized bed boiler system.

[0053] like Figure 2 The specific implementation steps of the coal blockage detection method are as follows:

[0054] Step 1: Calculate the direct signal f(V) according to the fusion signal calculation method. direct ) and fusion signal And update their respective signal bit numbers.

[0055] Step 2: The amplitude and speed of the two signals are judged. If one of them is abnormal, it is considered that the signal is abnormal. Otherwise, the signal is normal, and the signal judgment result is recorded.

[0056] Step 3: Conduct a comprehensive analysis based on the signal judgment results to determine the current periodic coal blockage status. Figure 5 Make a judgment and classification.

[0057] Step 4: Based on the comprehensive judgment results, update the coal blockage status and alarm indicator information of the previous cycle.

[0058] Step 5: The current cycle detection and analysis is complete. Return to Step 1.

[0059] Direct signals include coal feeder flow rate and coal spreading air pressure. These signals react quickly, but due to limitations in the accuracy of the signal source, the overall judgment results have insufficient confidence. Therefore, they can only be used for judgment and early warning.

[0060] Branch prediction uses direct signals, such as coal feed rate or coal spreading air pressure signals. For ease of discussion, we assume the direct signal for this branch is V. direct , and the total opening degree MV of the coal feeder gm To eliminate signal abrupt changes caused by coal feeder regulation, fusion is performed. The fusion expression is as follows:

[0061]

[0062] When coal blockage occurs, the total opening of the coal feeder remains unchanged, but due to a decrease (coal blockage) or an increase (coal supply interruption) in the amount of coal on the conveyor belt, f(V) changes. direct The signal undergoes a sudden change, resulting in amplitude or speed exceeding limits; when the coal blockage is restored, the total opening of the coal feeder remains unchanged, but because the amount of coal on the conveyor belt returns to normal, f(V) increases. direct The signal returned to normal, so the overall signal can be used as a prediction of whether a coal shortage will occur or resume.

[0063] The fusion signal is based on the actual impact of the existing operating conditions on combustion production. Therefore, although the response is slightly slower than the direct signal results, the results are more accurate and can be used as the final basis for determining whether coal blockage has actually occurred.

[0064] The final judgment uses multi-signal fusion, with oxygen signal as the primary indicator. Using this as the core judgment criterion, combined with the primary wind turbine MV fir Secondary air fan MV sec The total opening information of the coal feeder is used to eliminate oxygen fluctuations caused by active combustion adjustments, thus enabling the judgment of abnormal coal quantity factors. The fusion expression is as follows:

[0065]

[0066] When coal blockage occurs, the total opening of the primary and secondary air fans and the coal feeder remains unchanged. However, due to the sudden decrease in coal quantity, there will be a short-term rapid increase in oxygen levels. Abnormal upward speed or direct exceedance of the upper limit; when the coal blockage is restored, the total opening of the primary and secondary fans and the coal feeder remains unchanged, but due to the sudden increase in coal volume, there will be a short-term rapid decrease in oxygen content, i.e., f(V O2 An abnormal rate of descent or a direct breach of the lower limit can indicate whether the current situation indicates a coal blockage or a recovery.

[0067] like Figure 3 Specific implementation steps for judging abnormal coal supply signals:

[0068] Signal anomaly detection is divided into two types: amplitude exceeding limits and speed exceeding limits.

[0069] Amplitude exceeding limits – This is judged based on manually preset normal upper and lower limits, which is relatively simple and will not be elaborated here;

[0070] Speed ​​exceeding limits – This is determined based on several manually calibrated abnormal speed amplitudes. Preparatory work includes calculating the dynamic abnormal speed radius.

[0071] Step 1: Obtain several manually calibrated speed anomaly signal data points (let's say there are n calibrated anomaly data points).

[0072] Step 2: Calculate the average signal velocity over a period of time near each outlier point. Anomaly point velocity V i

[0073] Step 3: Calculate the abnormal velocity radius R

[0074]

[0075] The steps for real-time detection of abnormal signal velocity changes are as follows:

[0076] Sampling time: The sampling time for velocity statistics can be set manually (T). scan

[0077] Statistical period: The length of time for which statistics are performed. This time period is used to calculate the average speed and can be set manually (T).

[0078] Signal to be measured: y(t)

[0079] Velocity vector of the signal under test: The vector length is T, and it cyclically stores the historical data of the signal under test within a time period T before the current time.

[0080] Step 1: If the sampling period is up, proceed to Step 2; otherwise, proceed to Step 7.

[0081] Step 2: Calculate the velocity value of the signal under test within the current sampling period.

[0082] Δy(k)=y(k)-y(kT scan )

[0083] Step 3: Update and calculate the mean value V of the velocity vector of the current signal under test. Δy

[0084] Step 4: Determine if the current speed change is normal.

[0085]

[0086] If the speed change is abnormal, proceed to step five; otherwise, proceed to step six.

[0087] Step 5: If the speed is abnormal, perform speed correction by replacing the absolute value with the mean value (in the direction of the current speed), and issue a speed abnormality alarm.

[0088] Step 6: Update the velocity vector (this vector is updated cyclically).

[0089] Step 7: End

[0090] like Figure 4 The specific implementation steps for automatic handling of coal blockage based on coal blockage detection are as follows:

[0091] Process parameter settings:

[0092] Coal feeding balance process time T balance ;

[0093] Equilibrium process time = 0;

[0094] Step 1: Obtain the comprehensive judgment results of the current coal blockage detection.

[0095] Step 2: If the overall judgment result is state 5 ( Figure 5 If the equilibrium process time is 0 (state 5 in the equation), a single coal break occurs, and the process proceeds to the third step; if the comprehensive judgment result is state 4 ( Figure 5 If the coal blockage is restored (state 4 in the equation) and the balancing process time is 0, proceed to step 4; otherwise, proceed to step 5.

[0096] Step 3: Independent coal generation, coal feeding balance and air distribution treatment.

[0097] Coal feed output balancing—With the total coal feed output opening unchanged, the total coal feed of the cut-off branch is incrementally added to the normal branch through an average distribution method. The balancing process time = T balance ;

[0098] Air distribution suspension processing—the oxygen supply circuit, bed temperature circuit, and bed pressure circuit automatically suspend their states, sending a suspension signal to each circuit of the boiler combustion optimization controller.

[0099] Step 4: Restore the blocked coal supply, and perform coal feeding balance and air distribution treatment.

[0100] Coal feed output balancing—With the total coal feed output opening unchanged, the total coal feed from the cut-off branch is reduced and added to the normal branch through an average distribution method. The balancing process time = T balance ;

[0101] Air distribution shutdown procedure: The oxygen supply circuit, bed temperature circuit, and bed pressure circuit automatically shut down, and a shutdown signal is sent to each circuit of the boiler combustion optimization controller;

[0102] Step 5: Balancing operation of coal feeding branches. In normal branches, a fixed amount of the given balancing component is allocated in each step until the balancing component is fully allocated.

[0103] Step 6: Decrement the balancing process time by 1. If the balancing process time is less than or equal to 0, then the balancing process time is equal to 0, and the air distribution pause signal is canceled; otherwise, no related operation is performed.

[0104] Step 7: The current cycle ends, return to step 1.

[0105] It should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for detecting and automatically handling boiler shut-down coal, characterized by, Includes the following steps: S1. Predict the blockage and interruption of coal supply based on direct signals, using oxygen quantity signals as the core judgment data, and calculate the fused signal by combining relevant information; relevant information includes fan air volume and total opening degree of coal feeder; S2. Based on the real-time data of the fused signal, make anomaly judgments, make an overall final judgment on coal blockage, assess the degree of coal blockage, and analyze the causes of coal blockage. S3. Based on the predicted branch blockage and the overall final judgment results, automatically process the blockage and issue a blockage alarm.

2. A method of detecting and automatically handling a boiler shut-off coal according to claim 1, characterized in that, The direct signal includes branch coal feeder flow and branch coal feeding air pressure, and is obtained by subtracting the total opening of the coal feeder from the total opening of the coal feeder The fusion eliminates the signal mutation caused by the adjustment of the coal feeder. Assuming that the branch direct signal is The expression after fusion is as follows: 。 3. A method for detecting and automatically handling a boiler shut-off coal according to claim 1, characterized in that, The fusion expression of the fused signal is: ， is a fusion signal, is an oxygen signal, is a primary fan air volume signal, is a secondary fan air volume signal, is a total opening degree of the coal machine.

4. A method for detecting and automatically handling a boiler shut-off coal according to claim 1, characterized in that, The anomaly detection includes amplitude exceeding the limit detection and speed exceeding the limit detection. The speed exceeding the limit detection includes the following steps: S2.

1. Establish an anomaly database based on several manually calibrated speed anomalies, and calculate the dynamic anomaly speed radius based on the speed amplitude of the anomalies; S2.

2. Compare the real-time signal velocity vector with the dynamic abnormal velocity radius to determine whether the current real-time signal velocity is abnormal; S2.

3. Update the real-time signal velocity vector and enter the abnormal point data into the abnormal database for correction of abnormal velocity values.

5. The boiler coal blockage detection and automatic handling method according to claim 4, characterized in that, The formula for calculating the dynamic anomaly velocity radius is: ， R is the dynamic anomaly velocity radius, n is the number of manually labeled data points, is the average signal velocity at the time of one end of the anomaly point, is the anomaly point velocity.

6. A method of detecting and automatically handling a boiler shut down coal as claimed in claim 4 wherein, The formula for calculating the real-time signal velocity vector is as follows: ， is the vector length, k is the current time, is the real-time signal velocity vector, is the current signal velocity, is signal velocity before the time length.

7. A method for detecting and automatically handling a boiler shut-off coal according to claim 1, wherein The automatic coal blockage handling includes the following steps: S3.

1. Obtain the preliminary judgment of the branch road blockage and the overall final judgment results for comprehensive evaluation. After evaluation, the results are divided into 8 states, which are labeled with 1-8 respectively. S3.

2. Adjust the coal feed output and air distribution in real time according to the comprehensive evaluation results; S3.

3. Repeat steps S3.1 and S3.2 above until the effects of the coal blockage are eliminated.

8. A method of detecting and automatically handling a boiler shut-off coal according to claim 7, characterized in that, The real-time adjustment includes coal output balancing and air distribution suspension. The coal output balancing distributes a given balancing component to each step of the normal branch until the required balancing component is fully distributed. The air distribution suspension automatically suspends the oxygen circuit, bed temperature circuit, and bed pressure circuit.

9. A method of detecting and automatically handling a boiler shut-off coal according to claim 7, characterized in that, During the real-time adjustment process, the time of the real-time adjustment process is recorded, and the measurement frequencies of the direct signal and the fused signal are corrected based on the time of each real-time adjustment process.

10. A method of detecting and automatically handling a boiler shut down coal according to claim 5 or 6, characterized in that, The amplitude limit exceedance judgment is determined by manually calibrated amplitude limits to determine whether coal blockage or interruption has occurred. If either the amplitude limit exceedance judgment or the speed limit exceedance judgment shows coal blockage or interruption, it indicates that coal blockage or interruption has occurred in the boiler.

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