A waste incineration flue gas detection method, device and system

Abstract

This invention relates to the field of flue gas detection technology, specifically to a method, equipment, and system for detecting flue gas from waste incineration. It solves the technical problem of inaccurate blockage type determination during waste incineration flue gas detection due to the inability of existing technologies to distinguish between physical ash accumulation and chemical crystallization blockage online. The method includes: acquiring a baseline pressure recovery sequence after backflushing the sampling probe under normal temperature conditions; heating the sampling probe to the decomposition temperature of the heat-sensitive deposit and maintaining thermal equilibrium, then acquiring a test pressure recovery sequence after backflushing under high temperature conditions; if the integral change rate of the test pressure recovery sequence compared to the baseline pressure recovery sequence is less than or equal to a change rate threshold, then normalizing both the baseline and test pressure recovery sequences, and using a sequence morphology comparison algorithm to determine the morphological difference index between the normalized sequences, thus identifying whether the blockage is thermally stable ash accumulation or heat-sensitive crystallization.

Description

Technical Field

[0001] This invention relates to the field of flue gas detection technology, specifically to a method, equipment, and system for detecting flue gas from waste incineration. Background Technology

[0002] Waste-to-energy plants commonly use selective non-catalytic reduction (SNCR) technology to control nitrogen oxide emissions. This process requires the injection of ammonia reducing agents into the furnace, which inevitably results in the presence of escaped ammonia in the flue gas. The escaped ammonia reacts with sulfur oxides in the flue gas to form ammonium bisulfate. This substance is a high-viscosity liquid in the range of 147°C to 230°C, while the sampling probe of the continuous emission monitoring system operates at a temperature of about 180°C, which happens to be within this high viscosity range. As a result, ammonium bisulfate adsorbs fly ash and forms a dense, sticky crystalline layer on the surface of the filter element.

[0003] The current maintenance method for clogging sampling probes mainly relies on timed compressed air backflushing. While the backflushing airflow at room temperature can effectively remove physical ash accumulation caused by dry fly ash, it cannot clean the chemical adhesion formed by sticky ammonium bisulfate crystals. In fact, the pressure squeeze may even worsen the clogging. Maintenance personnel cannot rely on existing monitoring data to distinguish whether the backflushing failure is caused by excessive ash accumulation or crystal adhesion.

[0004] Blindly baking the probe at high temperatures will not solve the problem of ash accumulation and blockage and will also damage the probe seals. Blindly disassembling and cleaning the machine will cause unnecessary shutdowns for crystal blockages that can be dissolved by heat. At the same time, drastic fluctuations in furnace negative pressure and changes in gas viscosity during temperature changes will interfere with the accurate judgment of the nature of the blockage, making it impossible to achieve accurate online diagnosis of sampling probe blockage. Summary of the Invention

[0005] To address the technical problem of inaccurate blockage type determination during waste incineration flue gas detection due to the inability of existing technologies to distinguish between physical ash accumulation and chemical crystallization blockage online, the present invention aims to provide a waste incineration flue gas detection method, equipment, and system. The specific technical solution adopted is as follows: In a first aspect, a method for detecting flue gas from waste incineration is provided, comprising: acquiring a baseline pressure recovery sequence after backflushing a sampling probe under ambient temperature conditions; heating the sampling probe to the decomposition temperature of the heat-sensitive deposits and maintaining thermal equilibrium, and then acquiring a test pressure recovery sequence after backflushing under high temperature conditions; if the integral rate of change of the test pressure recovery sequence compared to the baseline pressure recovery sequence is greater than a preset rate of change threshold, it is determined that the blockage in the sampling probe has been cleared; if the integral rate of change is less than or equal to the rate of change threshold, the baseline pressure recovery sequence and the test pressure recovery sequence are normalized respectively, and a morphological difference index between the normalized sequences is determined using a sequence morphology comparison algorithm; and the blockage is determined to be thermally stable ash or heat-sensitive crystals based on the morphological difference index.

[0006] Based on the above technical solution, in the waste incineration flue gas detection method provided by this invention, by acquiring the ambient temperature reference pressure recovery sequence and the high temperature test pressure recovery sequence, and based on the comparison results of the integral change rate of the two with the preset change rate threshold, when the integral change rate is large, it is directly determined that the blockage has been cleared, thus quickly ending the diagnosis. When the integral change rate is small, normalization processing is further used to eliminate amplitude differences, and a morphological difference index is extracted using a sequence morphology comparison algorithm to accurately distinguish between thermally stable ash and thermosensitive crystals. This enables automatic identification of blockage properties during online operation, avoiding ineffective high-temperature baking of ash or unnecessary disassembly and cleaning of crystals, significantly reducing the frequency of manual maintenance and equipment wear. At the same time, it overcomes the interference of furnace negative pressure fluctuations and high-temperature gas viscosity changes on the diagnostic results, realizing non-invasive, closed-loop adaptive blockage diagnosis.

[0007] In conjunction with the first aspect above, in one possible implementation, the method for obtaining the reference pressure recovery sequence after backflushing the sampling probe under normal temperature conditions specifically includes: collecting the background static pressure of the furnace when the backflushing action ends and the sampling pump is not started; after starting the sampling pump, continuously collecting the instantaneous pressure value in the sampling probe at multiple collection moments; subtracting the background static pressure from the instantaneous pressure value at each collection moment to obtain the differential pressure value, and recording the differential pressure value in chronological order to form the reference pressure recovery sequence.

[0008] In conjunction with the first aspect above, in one possible implementation, before obtaining the reference pressure recovery sequence, the method further includes: after a system cold start or manual reset, if there is no stored reference pressure recovery sequence, confirming that the current state is normal temperature; and performing a backflushing under normal temperature conditions.

[0009] In conjunction with the first aspect above, in one possible implementation, after obtaining the reference pressure recovery sequence, the method further includes: determining the integral value of the reference pressure recovery sequence; if the integral value of the reference pressure recovery sequence is less than or equal to a preset blockage alarm threshold, then the sampling probe is determined to be ventilated normally; if the integral value of the reference pressure recovery sequence is greater than the preset blockage alarm threshold, then the sampling probe is determined to be blocked, and the heating step is triggered.

[0010] In conjunction with the first aspect above, in one possible implementation, the method of heating the sampling probe to the decomposition temperature of the heat-sensitive adhering substance and maintaining thermal equilibrium specifically includes: sending a heating command to the temperature control unit to set the target temperature to a preset decomposition temperature; and starting a thermal equilibrium timer after the temperature sensor first reaches the decomposition temperature to maintain constant temperature heating until a preset thermal equilibrium duration is reached.

[0011] In conjunction with the first aspect above, in one possible implementation, the method for determining the morphological difference index between normalized sequences using the sequence morphological alignment algorithm specifically includes: constructing a distance matrix between the normalized baseline pressure recovery sequence and the normalized test pressure recovery sequence; each element in the distance matrix is ​​the square of the numerical difference between corresponding points in the two sequences; using a dynamic programming algorithm to calculate the minimum cumulative path cost from the starting point to the ending point of the matrix and recording the path length; and determining the morphological difference index based on the minimum cumulative path cost and the path length.

[0012] In conjunction with the first aspect above, in one possible implementation, the method for determining whether the blockage is thermally stable ash or thermosensitive crystal based on the morphological difference index specifically includes: if the morphological difference index is less than a preset morphological threshold, then the blockage is determined to be thermally stable ash, the sampling probe is controlled to cool down to the normal operating temperature, and an ash blockage alarm signal is issued; if the morphological difference index is greater than or equal to the preset morphological threshold, then the blockage is determined to be thermosensitive crystal, the decomposition temperature is maintained, and a high-temperature pulse cleaning operation is performed.

[0013] In conjunction with the first aspect above, in one possible implementation, the method of maintaining the decomposition temperature and performing high-temperature pulse cleaning specifically includes: maintaining the decomposition temperature and performing multiple high-temperature backflushing operations at fixed time intervals; after each high-temperature backflushing, re-acquiring the test pressure recovery sequence and re-determining the morphological difference index; if the change in the morphological difference index after two adjacent backflushing operations is less than a preset convergence threshold, then performing residual resistance verification based on the integral value of the test pressure recovery sequence, a preset blockage alarm threshold, and a preset correction coefficient; if the residual resistance verification passes, exiting the high-temperature mode and resuming normal temperature sampling; if the residual resistance verification fails, issuing an alarm signal requiring manual cleaning.

[0014] In a second aspect, a waste incineration flue gas detection device is provided, comprising: a pressure sensor for collecting instantaneous pressure values ​​within a sampling probe; a temperature control unit for controlling the heating temperature of the sampling probe; and a controller connected to the pressure sensor and the temperature control unit, the controller being configured to perform the method of any one of the first aspects.

[0015] Thirdly, a waste incineration flue gas detection system is provided, comprising: a waste incineration flue gas detection device, a sampling probe, a backflushing module, and a heating module; the sampling probe is used to extract flue gas from the waste incineration furnace; the backflushing module is used to introduce compressed air into the sampling probe to remove adhering substances; the heating module is used to adjust the temperature of the sampling probe; a pressure sensor in the waste incineration flue gas detection device is used to collect the instantaneous pressure value in the sampling probe; a temperature control unit in the waste incineration flue gas detection device is used to control the heating module; and a controller in the waste incineration flue gas detection device is connected to the backflushing module, the pressure sensor, and the temperature control unit respectively, for performing the method of any one of the first aspects.

[0016] The present invention has the following beneficial effects: By acquiring the room temperature reference pressure recovery sequence and the high temperature test pressure recovery sequence, and comparing the integral change rate of the two with the preset change rate threshold, when the integral change rate is large, it is directly determined that the blockage has been cleared, thus quickly ending the diagnosis. When the integral change rate is small, normalization is further used to eliminate amplitude differences, and a morphological difference index is extracted using a sequence morphology comparison algorithm to accurately distinguish between thermally stable ash and thermosensitive crystals. This enables automatic identification of blockage properties during online operation, avoiding ineffective high-temperature baking of ash or unnecessary disassembly and cleaning of crystals, significantly reducing the frequency of manual maintenance and equipment wear. At the same time, it overcomes the interference of furnace negative pressure fluctuations and high-temperature gas viscosity changes on the diagnostic results, realizing non-invasive, closed-loop adaptive blockage diagnosis. Attached Figure Description

[0017] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a system structure diagram of a waste incineration flue gas detection system provided in one embodiment of the present invention; Figure 2 This is a flowchart of a waste incineration flue gas detection method provided in one embodiment of the present invention. Detailed Implementation

[0019] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a waste incineration flue gas detection method, device, and system proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] The following description, in conjunction with the accompanying drawings, details the specific scheme of the waste incineration flue gas detection method, equipment, and system provided by the present invention.

[0022] Please see Figure 1 The diagram illustrates a system structure of a waste incineration flue gas detection system according to an embodiment of the present invention. The waste incineration flue gas detection system includes: a waste incineration flue gas detection device 1, a sampling probe 2, a backflushing module 3, and a heating module 4. Each module works together to complete the entire process of flue gas detection, blockage identification, and removal of attached materials. The system operation logic and data interaction are closely integrated, which can stably achieve accurate identification and automated cleaning of the sampling probe blockage type.

[0023] Among them, the waste incineration flue gas detection device 1 is the core control and data processing unit of the system, integrating three core components: pressure sensor 11, temperature control unit 12, and controller 13, undertaking the core functions of data acquisition, calculation and analysis, and command issuance.

[0024] The pressure sensor 11 adopts a high-precision micro differential pressure industrial sensing device, which is tightly assembled in the internal air path of the sampling probe 2. It collects the instantaneous pressure value inside the sampling probe 2 in real time. The collected pressure data is transmitted to the controller 13 in real time, providing raw data for the generation of the reference pressure recovery sequence and the test pressure recovery sequence. It is the data basis for calculating the degree of blockage and determining the type of blockage.

[0025] The temperature control unit 12 is a physical device consisting of a temperature regulation circuit and a signal feedback module. It is bidirectionally connected to the heating module 4 and the controller 13. It receives the temperature setting command from the controller 13, monitors the real-time temperature of the sampling probe 2 in real time and feeds it back to the controller 13. At the same time, it precisely controls the heating power and running time of the heating module 4 to ensure that the sampling probe 2 reaches the decomposition temperature of the heat-sensitive deposits and maintains a stable thermal balance.

[0026] The controller 13 adopts an industrial-grade programmable logic controller (PLC) or an embedded microcontroller unit. It is the core of the system's operation and decision-making. It receives pressure data transmitted by the pressure sensor 11 and temperature data transmitted by the temperature control unit 12. It completes all calculations such as pressure sequence integral calculation, sequence normalization processing, morphological difference index calculation, and blockage type determination. At the same time, it sends temperature control commands to the temperature control unit 12 and backflushing execution commands to the backflushing module 3 based on the calculation results, and coordinates the operation rhythm of all modules.

[0027] The sampling probe 2 is made of high-temperature resistant and corrosion-resistant alloy material and is installed in the flue gas emission pipeline of the waste incineration furnace. The probe is equipped with a special filter element to extract the waste incineration flue gas in the furnace and complete the preliminary filtration of the flue gas. It is the front-end execution component for flue gas detection. The clogging status of its internal filter element is the detection object of the entire system. The pressure sensor 11 directly collects the pressure signal inside the probe. The temperature status of the sampling probe 2 is directly controlled by the heating module 4 and is the carrier of data and actions of various functional modules.

[0028] The backflush module 3 is composed of a compressed air storage tank, an electromagnetic backflush valve, and a high-pressure air pipeline. It is directly connected to the controller 13 and receives backflush commands from the controller 13. During the normal temperature detection and high temperature detection stages, it introduces high-pressure compressed air into the sampling probe 2 according to the time sequence set by the system to complete the backflush cleaning of the deposits inside the probe. The time node for the end of the backflush action is accurately determined by the controller 13. It is a pre-execution module for obtaining the reference pressure recovery sequence and the test pressure recovery sequence. The pressure status data after backflush is directly collected and transmitted by the pressure sensor 11.

[0029] The heating module 4 is made of armored heating rods or ceramic heating plates, which are tightly fitted to the outer wall of the sampling probe 2 and the periphery of the filter element. It is directly connected to the temperature control unit 12, receives the control commands from the temperature control unit 12, and performs directional heating on the sampling probe 2 to raise the temperature of the sampling probe 2 to the decomposition temperature range of the heat-sensitive deposits. At the same time, it works with the temperature control unit 12 to maintain a constant temperature to meet the thermal balance requirements, providing the necessary heat conditions for the decomposition of ammonium bisulfate crystal blockages. Its operating status directly determines the effectiveness of the working conditions in the high-temperature test stage, and it is the core execution component for high-temperature detection and crystal removal.

[0030] Please see Figure 2 The diagram illustrates a flowchart of a waste incineration flue gas detection method according to an embodiment of the present invention. The waste incineration flue gas detection method includes: S1. Obtain the baseline pressure recovery sequence after backflushing the sampling probe under normal temperature conditions.

[0031] In some implementations, before obtaining the baseline pressure recovery sequence, if there is no stored baseline pressure recovery sequence after a system cold start or manual reset, the current state is confirmed to be normal temperature; and a backflushing is performed under normal temperature conditions.

[0032] Specifically, after initial power-on installation, software reset, or manual maintenance reset, the system enters the initialization state. At this time, there is no valid historical monitoring data in memory. To avoid subsequent diagnostic logic from getting stuck due to the lack of a comparison benchmark, the system first checks whether a preset factory default benchmark pressure recovery sequence is stored in the non-volatile memory. If it exists, the sequence is directly loaded as the initial room temperature benchmark pressure recovery sequence. If it does not exist, the temperature sensor confirms that the sampling probe is currently in a room temperature working state (room temperature refers to the natural temperature of the sampling probe when it is not heated, with a temperature range of 20℃ to 50℃). Then, the backflush module is controlled to perform a standard backflush action, and the subsequent data acquisition process is executed. The acquired differential pressure sequence is forcibly solidified as the initial benchmark pressure recovery sequence, ensuring that the system has a usable reference benchmark in any startup scenario, providing a stable foundation for subsequent relative change analysis.

[0033] In some implementations, the background static pressure of the furnace is collected when the backflushing action ends and the sampling pump is not started; after the sampling pump is started, the instantaneous pressure value in the sampling probe is continuously collected at multiple collection times; the background static pressure is subtracted from the instantaneous pressure value at each collection time to obtain the differential pressure value, and the differential pressure value is recorded in chronological order to form a reference pressure recovery sequence.

[0034] Specifically, the system monitors the control signal of the backflushing solenoid valve in real time. When the control signal changes from open to closed, it indicates that the backflushing action has just ended. At this time, a negative pressure has not yet been established in the sampling probe pipeline. Before starting the sampling pump at this moment, the instantaneous pressure value is read by the pressure sensor. This pressure value directly reflects the background static pressure in the furnace. The system then starts the sampling pump and continuously collects the instantaneous pressure value in the sampling probe at a preset sampling frequency (e.g., 20Hz). For each collected original pressure point, differential calculation is immediately performed to subtract the background static pressure from the original pressure value to obtain the net pressure value after deducting the interference of furnace negative pressure. The system continues to collect and calculate until the absolute value of the net pressure value reaches the preset target working threshold (e.g., 20kPa) or the collection time reaches the maximum time limit (e.g., 15 seconds). All calculated net pressure values ​​are arranged in chronological order to form a reference pressure recovery sequence after sampling probe backflushing under normal temperature conditions. This sequence can objectively and without interference reflect the ventilation resistance characteristics of the probe filter element, eliminating the interference of furnace negative pressure fluctuations on the measurement results from the root.

[0035] In some implementations, after obtaining the reference pressure recovery sequence, the integral value of the reference pressure recovery sequence is determined; if the integral value of the reference pressure recovery sequence is less than or equal to a preset blockage alarm threshold, the sampling probe is determined to be ventilated normally; if the integral value of the reference pressure recovery sequence is greater than the preset blockage alarm threshold, the sampling probe is determined to be blocked, and the heating step is triggered.

[0036] Specifically, to quantify the ventilation resistance level of the current sampling probe, the system performs numerical integration calculations on the reference pressure recovery sequence to obtain the negative pressure establishment integral value, expressed as: In the formula, This represents the k-th net pressure value in the baseline pressure recovery sequence. Take the absolute value to eliminate the influence of the negative sign of negative pressure, and only retain the pressure magnitude; The sampling time interval is determined by the sampling frequency; The area under the curve component corresponding to a single data point is obtained; N is the total number of data points in the baseline pressure recovery sequence; all components are summed to obtain the integral value of negative pressure establishment. The area under the curve (AUC) represents the total pressure recovery process and quantifies the air resistance level of the filter element.

[0037] The system uses the 3σ statistical principle to preset the blockage alarm threshold. During the system calibration phase, the negative pressure integral value is collected after multiple normal backflushing operations. The arithmetic mean and standard deviation of the integral values ​​are calculated first, and then the final threshold is obtained by adding three times the standard deviation to the mean. For example, if the integral mean of 30 consecutive normal backflushing operations is 62 kPa·s and the standard deviation is 14 kPa·s, the corresponding blockage alarm threshold is 104 kPa·s.

[0038] The system compares the calculated integral value with the preset blockage alarm threshold. If the integral value is less than or equal to the blockage alarm threshold, the sampling probe is deemed to be ventilated normally, and the system continues to execute the routine monitoring process. If the integral value is greater than the blockage alarm threshold, the sampling probe is deemed to have an abnormality of blocked ventilation. The system suspends routine sampling, marks the current reference pressure recovery sequence as the reference pressure recovery sequence of the fault state, stores it in the static storage area and locks it in read-only state to prevent the data from being overwritten during subsequent diagnosis. Then, the subsequent heating and high temperature test process is triggered to provide a stable fault reference for blockage type determination.

[0039] S2. After heating the sampling probe to the decomposition temperature of the heat-sensitive adhering material and maintaining thermal equilibrium, obtain the test pressure recovery sequence after backflushing under high temperature conditions.

[0040] In some implementations, a heating command is sent to the temperature control unit to set the target temperature to the preset decomposition temperature; when the temperature sensor first reaches the decomposition temperature, a thermal equilibrium timer is started to maintain constant temperature heating until the preset thermal equilibrium time is reached.

[0041] Specifically, after receiving the blockage anomaly trigger signal and the locked room temperature reference pressure recovery sequence during the room temperature detection phase, the system sends a heating command to the temperature control unit to effectively distinguish between thermally stable ash and heat-sensitive crystals, setting the target temperature to a preset decomposition temperature, such as 240°C. This temperature is within the effective decomposition temperature range of heat-sensitive deposits such as ammonium bisulfate, ensuring that crystalline blockages are decomposed by heat.

[0042] Because the probe filter element has a certain heat capacity and the crystal layer is located inside the filter element pores, the temperature sensor reaching the set value alone cannot guarantee that the crystal layer deep in the filter element reaches the decomposition temperature. Therefore, when the temperature sensor reading first reaches the preset decomposition temperature, the system starts a countdown timer to maintain a constant temperature heating state until the preset thermal equilibrium time is reached, for example, 300 seconds. This time is used to ensure that the heat is fully conducted to the deep layer of the filter element, so that the attached ammonium bisulfate crystals can completely absorb heat and melt or vaporize. During this period, the system keeps the sampling pump off to avoid data collection before thermal equilibrium is reached, which would lead to detection deviations. This provides a stable physical environment for subsequent pressure collection under high-temperature conditions, ensures the crystal decomposition effect, and provides a reliable high-temperature test basis for blockage type determination.

[0043] After thermal equilibrium is achieved, the system controls the backflushing module to perform a standard-duration high-temperature backflushing action to remove decomposed crystalline deposits and loose ash from the probe. The system monitors the control signal of the backflushing solenoid valve in real time. When the control signal changes from open to closed, it indicates that the high-temperature backflushing action has just ended. At this time, a sampling negative pressure has not yet been established in the sampling probe pipeline. Before starting the sampling pump, the instantaneous pressure value is read by the pressure sensor. This pressure value is the furnace background static pressure under the current high-temperature operating conditions. Since the furnace operating conditions may change, this value differs from the background static pressure under normal temperature conditions.

[0044] The system then activates the sampling pump to continuously acquire instantaneous pressure values ​​within the sampling probe at the same sampling frequency (e.g., 20Hz) as during the ambient temperature acquisition phase. For each acquired raw pressure point, differential calculation is immediately performed, subtracting the high-temperature background static pressure from the raw pressure value to obtain the net pressure value after deducting the interference of furnace negative pressure under high-temperature conditions. The system continues to acquire and calculate until the absolute value of the net pressure reaches the same preset target working threshold (e.g., 20kPa) as during the ambient temperature acquisition phase, or the acquisition duration reaches the same maximum time limit (e.g., 15 seconds). All calculated net pressure values ​​are arranged in chronological order to form a test pressure recovery sequence after backflushing the sampling probe under high-temperature conditions. This sequence is a dynamic variable and is updated after each high-temperature backflushing in subsequent cleaning cycles. It is used for comparison with the ambient temperature reference pressure recovery sequence, providing a data basis for subsequent blockage type determination and cleaning effect verification. At the same time, the differential acquisition strategy completely eliminates the interference of furnace background pressure fluctuations under high-temperature conditions, ensuring that the test data only reflects the ventilation resistance characteristics of the probe filter element.

[0045] S3. If the integral rate of change of the test pressure recovery sequence relative to the reference pressure recovery sequence is greater than the preset rate of change threshold, it is determined that the blockage in the sampling probe has been cleared.

[0046] In some implementations, after the system completes the locking of the ambient temperature reference pressure recovery sequence and the acquisition of the high temperature test pressure recovery sequence, it performs numerical integration calculations on the two sequences to obtain the reference integral value corresponding to the reference pressure recovery sequence and the test integral value corresponding to the test pressure recovery sequence. The integration calculation logic is consistent with the negative pressure integration calculation in the ambient temperature stage, quantifying the ventilation resistance level corresponding to the two sequences.

[0047] The system then uses the baseline integral value as a reference to calculate the integral rate of change of the test pressure recovery sequence relative to the baseline pressure recovery sequence, expressed as: In the formula, This is the integral value of the baseline pressure recovery sequence, i.e., the baseline integral value; The integral value of the test pressure recovery sequence, i.e., the test integral value; The integral rate of change, physically representing the relative improvement in ventilation resistance after high-temperature backflushing compared to the normal-temperature fault condition, is... ≥ hour, ≤0 indicates that the resistance has not improved or has even worsened; when When =0, =1 indicates that the resistance has been completely cleared. It should be noted that the denominator (i.e., the integral value of the baseline pressure recovery sequence) only approaches 0 when the sampling probe is completely blocked and cannot complete the pressure recovery sequence acquisition. However, in such a scenario, the blockage abnormality has already been triggered in the room temperature detection stage, and it is impossible to enter this step. Therefore, the denominator is always a positive real number greater than 0, and there is no problem of the denominator being zero.

[0048] The system compares the calculated integral rate of change with a preset rate of change threshold. The preset rate of change threshold can be determined by performing multiple high-temperature backflushing experiments with the sampling probe in a clean state, collecting integral rate of change data, and taking its statistical lower limit (such as the average value minus twice the standard deviation). For example, it can be set to 30%. If the integral rate of change is greater than the preset threshold, it means that the ventilation resistance of the sampling probe has decreased significantly after high-temperature backflushing, which means that the blockage has been decomposed or detached on a large scale. At this time, there is no need to perform subsequent normalization processing and sequence morphology comparison. It can directly determine that the blockage in the sampling probe has been cleared, generate a high confidence signal that the blockage has been cleared, and directly enter the subsequent maintenance decision process. This avoids information distortion caused by normalization under extreme working conditions and greatly improves diagnostic efficiency and reduces invalid calculations.

[0049] S4. If the integral rate of change is less than or equal to the rate of change threshold, the baseline pressure recovery sequence and the test pressure recovery sequence are normalized respectively, and the morphological difference index between the normalized sequences is determined by the sequence morphology comparison algorithm.

[0050] In some implementations, after determining the macroscopic resistance and confirming that the integral rate of change is less than or equal to the rate of change threshold, the system first performs normalization. Due to the decreased efficiency of the sampling pump and the reduced gas density under high-temperature conditions, the pressure amplitude of the test pressure recovery sequence is usually lower than that of the reference pressure recovery sequence. To eliminate this numerical dimension bias caused by differences in operating conditions and to allow subsequent analysis to focus on waveform shape rather than absolute value, the system performs normalization processing on both the reference pressure recovery sequence and the test pressure recovery sequence, mapping them to a preset numerical range using a maximum-minimum algorithm. For example, the reference pressure recovery sequence is represented as follows: In the formula, This represents the i-th net pressure value in the baseline pressure recovery sequence; The minimum pressure value in the baseline pressure recovery sequence. The maximum pressure value in the baseline pressure recovery sequence; This is the normalized value of the i-th point in the baseline pressure recovery sequence. Specifically, if the minimum pressure value and the maximum pressure value in the baseline pressure recovery sequence are equal, then directly set... The result is zero. The normalization process for the test pressure recovery sequence is similar.

[0051] In some implementations, a distance matrix is ​​constructed between the normalized baseline pressure recovery sequence and the normalized test pressure recovery sequence; each element in the distance matrix is ​​the square of the numerical difference between corresponding points in the two sequences; the minimum cumulative path cost from the starting point to the ending point of the matrix is ​​calculated using a dynamic programming algorithm, and the path length is recorded; based on the minimum cumulative path cost and the path length, the morphological difference index is determined.

[0052] Specifically, the system first constructs a distance matrix between the normalized baseline sequence and the normalized test sequence. The dimension of the matrix is ​​determined by the length of the two sequences. Each element in the matrix is ​​the square of the difference between the two normalized values ​​at the corresponding position. The smaller the value of this element, the more similar the two points are in shape, which provides a basis for subsequent path cost calculation.

[0053] The system then uses a dynamic programming algorithm to calculate the minimum cumulative path cost from the starting point to the ending point of the distance matrix, which is expressed as: In the formula, The element in the i-th row and j-th column of the distance matrix represents the morphological difference quantification value of corresponding points in the two sequences. The minimum cumulative path cost in the (i-1)th row and jth column of the distance matrix corresponds to the cost of the time axis stretching operation. The minimum cumulative path cost in the i-th row and j-1-th column of the distance matrix corresponds to the cost of the time axis compression operation. is the minimum cumulative path cost in the (i-1)th row and (j-1)th column of the distance matrix, corresponding to the cost of the linear matching operation; min is the minimum value operation, which selects the path with the minimum cost among the three operations; The minimum cumulative path cost in the i-th row and j-th column of the distance matrix is ​​used to automatically avoid nonlinear distortions such as time axis stretching, compression or twisting caused by gas viscosity changes under high temperature conditions by selecting the minimum cumulative cost during the calculation process. The path that can optimally match the two sequence shapes is found, and the length of the optimal path is recorded simultaneously to eliminate the influence of different sequence lengths.

[0054] Specifically, the boundary initialization of the distance matrix is ​​as follows: For the first line, For the first column, .

[0055] Finally, the system divides the minimum cumulative path cost by the recorded path length (the number of steps in the optimal path, i.e., the number of data point matching pairs involved in the alignment process), converting the total difference into an average difference per unit length. This eliminates the influence of different sequence lengths on the difference value and determines the morphological difference index. This index can objectively reflect the essential morphological difference between the two sequences after time axis alignment. The smaller the value, the more consistent the waveform topology; the larger the value, the more significant the morphological difference. This accurately distinguishes between thermosensitive crystallization and thermally stable ash accumulation, providing reliable quantitative data support for the accurate determination of subsequent blockage types.

[0056] S5. Based on the morphological difference index, determine whether the blockage is thermally stable ash or thermally sensitive crystals.

[0057] In some implementations, after the system completes the sequence morphology comparison to obtain the morphological difference index, it combines the preset morphological threshold to complete the classification and determination of the blockage type. The morphological difference index is used to characterize the essential morphological difference between the room temperature reference pressure recovery sequence and the high temperature test pressure recovery sequence after eliminating time axis distortion and dimensional deviation. The smaller the value, the more consistent the waveform topology, and the larger the value, the more significant the essential morphological difference. This distinguishes between thermally stable ash and thermally sensitive crystals, achieving accurate online identification of blockage type and avoiding equipment damage or downtime losses caused by blind maintenance.

[0058] The system can perform multiple tests on artificially simulated pure ash blockage and pure crystal blockage, calculate their respective morphological difference indices, and take the median value of the two index distribution intervals as the morphological threshold, for example, 0.02. If the morphological difference index is less than the preset morphological threshold, it indicates that after eliminating the waveform distortion caused by gas viscosity, the high-temperature test pressure recovery curve and the room-temperature reference pressure recovery curve are highly consistent in morphology. This means that the high-temperature environment has not changed the physical structure of the deposits, and the thermally stable ash will not decompose or change in structure due to high temperature. Therefore, the blockage is determined to be thermally stable ash. The system then executes a cooling control command to cool the sampling probe to the normal operating temperature, sends an alarm signal to the maintenance terminal indicating ash blockage and the need for manual cleaning, and releases the previously locked room-temperature reference pressure recovery sequence, ending the current diagnostic process and resuming normal flue gas monitoring. This operation avoids ineffective high-temperature heating of the ash blockage, protects the sealing components, filter elements, and other parts of the sampling probe, and promptly reminds maintenance personnel to carry out manual cleaning to prevent further deterioration of the ash and its impact on detection accuracy.

[0059] If the morphological difference index is greater than or equal to the preset morphological threshold, it indicates that the high-temperature environment has induced a significant abrupt change in the waveform morphology, corresponding to a local phase change or microstructural reorganization of the deposits. Thermosensitive crystals will decompose and melt due to high temperatures, causing a change in the physical model of the pressure recovery curve. Therefore, the blockage is identified as thermosensitive crystals. The system then enters a high-temperature pulse removal mode, using the synergistic effect of high-temperature decomposition and airflow impact to completely peel off the crystal layer.

[0060] Specifically, the system maintains the current decomposition temperature of the heat-sensitive deposits (e.g., 240℃, corresponding to the effective decomposition temperature range of ammonium bisulfate) and performs multiple high-temperature backflushing actions at fixed time intervals (e.g., 60 seconds). Each backflushing involves introducing high-pressure compressed air into the sampling probe to impact the decomposed crystalline deposits, thereby removing the blockage. After each high-temperature backflushing, the system repeats the entire process of high-temperature differential pressure acquisition, normalization processing, and sequence morphology comparison to re-acquire the test pressure recovery sequence and redetermine the morphological difference index for real-time monitoring of the cleaning effect.

[0061] The system calculates the change in the morphological difference index after two consecutive backflushing cycles, i.e., the absolute value of the difference between the morphological difference indexes after two consecutive backflushing cycles. Simultaneously, based on the stable fluctuation characteristics of the morphological difference index during the high-temperature pulse cleaning phase, a convergence threshold is calibrated. During system debugging or periodic calibration, the absolute values ​​of the differences between adjacent morphological difference indices are collected during multiple effective crystallization cleaning processes, and the sum of the average of these absolute values ​​and twice the standard deviation is taken as the convergence threshold.

[0062] If the change is greater than or equal to the convergence threshold, it indicates that the cleaning is still effective and the crystalline layer is still being peeled off. The system continues to execute the next round of high-temperature backflushing, while accumulating the number of backflushing cycles. When the number of backflushing cycles reaches the preset maximum number of backflushing cycles (e.g., 5 times) and the change is still not less than the convergence threshold, the high-temperature mode is exited and an alarm signal requiring manual cleaning is issued. If the change in the morphological difference index after two consecutive backflushing cycles is less than the preset convergence threshold, it indicates that the cleaning effect has stabilized. Then, based on the integral value of the test pressure recovery sequence, the preset blockage alarm threshold, and the preset correction coefficient, the system executes... Residual resistance verification: First, divide the integral value of the test pressure recovery sequence by the correction factor to obtain the equivalent ventilation resistance integral value under normal temperature conditions, i.e., the corrected test integral value, to offset the influence of gas viscosity changes on the integral value under high temperature conditions. Then, compare the corrected test integral value with the preset blockage alarm threshold. If the corrected test integral value is less than or equal to the blockage alarm threshold, the residual resistance verification is deemed to have passed, indicating that the ventilation resistance has recovered to the normal level. If the corrected test integral value is still greater than the blockage alarm threshold, the residual resistance verification is deemed to have failed, indicating that significant blockage still exists.

[0063] The correction factor was obtained through on-site calibration experiments. Under the premise of a clean sampling probe filter, the integral values ​​of ventilation resistance were collected at both room temperature and the decomposition temperature of heat-sensitive deposits. The ratio of the high-temperature integral value to the room-temperature integral value was calculated, which is the correction factor. This factor is used to offset the influence of gas viscosity changes on the integral value under high-temperature conditions, restoring the true ventilation resistance level. It should be noted that this correction factor is based on clean probe calibration and ignores the influence of blockages on the high-temperature gas flow characteristics. As an engineering approximation, it has sufficient reference value when verifying residual resistance. For example, the baseline integral value is 60 kPa·s under clean conditions at room temperature, and 72 kPa·s under clean high-temperature conditions at 240℃, corresponding to a correction factor of 1.2.

[0064] If the residual resistance check passes, it indicates that the ventilation resistance of the sampling probe has returned to near normal levels. The high-temperature mode is then exited, and room-temperature sampling resumes. If the residual resistance check fails, it indicates mixed blockage (crystallization has been cleared, but residual ash) or stubborn blockage remains. An alarm signal requiring manual cleaning is issued, the high-temperature mode is exited, and the diagnostic process ends. This process achieves a fully automated closed loop from blockage diagnosis and automatic cleaning to effect verification, significantly reducing unnecessary manual intervention, improving operational efficiency, and minimizing downtime losses.

[0065] Based on the above technical solution, by acquiring the room temperature reference pressure recovery sequence and the high temperature test pressure recovery sequence, and comparing the integral change rate of the two with the preset change rate threshold, when the integral change rate is large, it is directly determined that the blockage has been cleared, thus quickly ending the diagnosis. When the integral change rate is small, normalization is further used to eliminate amplitude differences, and a morphological difference index is extracted using a sequence morphology comparison algorithm to accurately distinguish between thermally stable ash and thermosensitive crystals. This enables automatic identification of blockage nature during online operation, avoiding ineffective high-temperature baking of ash or unnecessary disassembly and cleaning of crystals, significantly reducing the frequency of manual maintenance and equipment wear. At the same time, it overcomes the interference of furnace negative pressure fluctuations and high-temperature gas viscosity changes on the diagnostic results, realizing non-invasive, closed-loop adaptive blockage diagnosis.

[0066] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0067] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0068] In this embodiment of the invention, the waste incineration flue gas detection equipment can be divided into functional units according to the above method example. For example, each function can be divided into its own functional unit, or two or more functions can be integrated into one processing unit. The integrated unit can be implemented in hardware or software. It should be noted that the unit division in this embodiment is illustrative and only represents one logical functional division; other division methods may be used in actual implementation.

[0069] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings and the disclosure, will understand and implement other variations of the disclosed embodiments in carrying out the claimed invention. In this invention, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several of the functions listed in this invention.

[0070] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the scope of the invention. Accordingly, this specification and drawings are merely illustrative of the invention and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its scope. Thus, if such modifications and modifications of the invention fall within the scope of the invention and its equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for detecting flue gas from waste incineration, characterized in that, include: Obtain the baseline pressure recovery sequence after backflushing the sampling probe under normal temperature conditions; After heating the sampling probe to the decomposition temperature of the heat-sensitive adhering material and maintaining thermal equilibrium, the test pressure recovery sequence after backflushing under high-temperature conditions is obtained. If the integral rate of change of the test pressure recovery sequence relative to the reference pressure recovery sequence is greater than a preset rate of change threshold, it is determined that the blockage in the sampling probe has been cleared. If the integral rate of change is less than or equal to the rate of change threshold, the baseline pressure recovery sequence and the test pressure recovery sequence are normalized respectively, and the morphological difference index between the normalized sequences is determined by the sequence morphology comparison algorithm. Based on the morphological difference index, the blockage is determined to be either thermally stable ash or thermally sensitive crystals.

2. The method for detecting flue gas from waste incineration according to claim 1, characterized in that, Obtain the baseline pressure recovery sequence after backflushing the sampling probe under normal temperature conditions, including: The background static pressure of the furnace is collected after the backflushing action is completed and before the sampling pump is started; After the sampling pump is started, the instantaneous pressure value inside the sampling probe is continuously collected at multiple sampling times; The background static pressure is subtracted from the instantaneous pressure value at each acquisition moment to obtain the differential pressure value, and the differential pressure value is recorded in chronological order to form the reference pressure recovery sequence.

3. The method for detecting flue gas from waste incineration according to claim 2, characterized in that, Before obtaining the baseline pressure recovery sequence, the following steps are also included: If there is no stored baseline pressure recovery sequence after a cold start or manual reset of the system, then the current state is confirmed to be normal temperature. Perform a backflushing operation at the stated normal temperature.

4. The method for detecting flue gas from waste incineration according to claim 2, characterized in that, After obtaining the baseline pressure recovery sequence, the following steps are also included: Determine the integral value of the reference pressure recovery sequence; If the integral value of the reference pressure recovery sequence is less than or equal to the preset blockage alarm threshold, the sampling probe is determined to be ventilated normally. If the integral value of the reference pressure recovery sequence is greater than the preset blockage alarm threshold, it is determined that the sampling probe is blocked, and the heating step is triggered.

5. The method for detecting flue gas from waste incineration according to claim 1, characterized in that, Heating the sampling probe to the decomposition temperature of the heat-sensitive deposit and maintaining thermal equilibrium includes: Send a heating command to the temperature control unit to set the target temperature to the preset decomposition temperature; Once the temperature sensor reaches the decomposition temperature for the first time, a thermal equilibrium timer is started to maintain constant temperature heating until the preset thermal equilibrium duration is reached.

6. The method for detecting flue gas from waste incineration according to claim 1, characterized in that, The morphological difference index between normalized sequences is determined using a sequence morphological alignment algorithm, including: Construct a distance matrix between the normalized baseline pressure recovery sequence and the normalized test pressure recovery sequence; each element in the distance matrix is ​​the square of the difference between corresponding points in the two sequences; Calculate the minimum cumulative path cost from the starting point to the ending point of the matrix using dynamic programming algorithm, and record the path length; The morphological difference index is determined based on the minimum cumulative path cost and the path length.

7. The method for detecting flue gas from waste incineration according to claim 6, characterized in that, The blockage is determined to be either thermally stable ash or thermally sensitive crystals based on the morphological difference index, including: If the morphological difference index is less than the preset morphological threshold, the blockage is determined to be thermally stable ash, the sampling probe is controlled to cool down to the normal operating temperature, and an ash blockage alarm signal is issued. If the morphological difference index is greater than or equal to a preset morphological threshold, the blockage is determined to be a thermosensitive crystal, the decomposition temperature is maintained, and a high-temperature pulse removal operation is performed.

8. The method for detecting flue gas from waste incineration according to claim 7, characterized in that, Maintaining the decomposition temperature and performing a high-temperature pulse cleanup operation includes: Maintain the decomposition temperature and perform multiple high-temperature backflushing operations at fixed time intervals; After each high-temperature backflush, the test pressure recovery sequence is reacquired, and the morphological difference index is redefined. If the change in the morphological difference index after two consecutive backflushs is less than the preset convergence threshold, then residual resistance verification is performed based on the integral value of the test pressure recovery sequence, the preset blockage alarm threshold, and the preset correction coefficient. If the residual resistance test passes, exit the high-temperature mode and resume room temperature sampling; If the residual resistance test fails, an alarm signal will be issued indicating that manual cleaning is required.

9. A waste incineration flue gas detection device, characterized in that, include: A pressure sensor is used to collect instantaneous pressure values ​​within the sampling probe; The temperature control unit is used to control the heating temperature of the sampling probe; A controller is connected to both the pressure sensor and the temperature control unit, and the controller is configured to perform the method of any one of claims 1 to 8.

10. A waste incineration flue gas detection system, characterized in that, include: Waste incineration flue gas detection equipment, sampling probes, backflushing modules, and heating modules; The sampling probe is used to extract flue gas from inside the waste incinerator. The backflush module is used to introduce compressed air into the sampling probe to remove adhering substances; The heating module is used to adjust the temperature of the sampling probe; The pressure sensor in the waste incineration flue gas detection equipment is used to collect the instantaneous pressure value inside the sampling probe; The temperature control unit in the waste incineration flue gas detection equipment is used to control the heating module; The controller in the waste incineration flue gas detection device is connected to the backflushing module, the pressure sensor and the temperature control unit respectively, and is used to execute the method of any one of claims 1 to 8.

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