A cloth bag dust removal working condition calibration method and system based on temperature and humidity linkage

Abstract

The application belongs to the technical field of industrial dust removal, and particularly discloses a bag dust removal working condition calibration method and system based on temperature and humidity linkage, which comprises the following steps: collecting the inlet temperature and humidity, bag chamber pressure difference time series data and particulate matter emission concentration data of each sub-region; after each pulse jetting, extracting the initial slope of the pressure difference recovery curve and the steady-state residual pressure difference of each sub-region, and calculating the emission concentration trend slope of each sub-region; based on the initial slope, the steady-state residual pressure difference, the emission concentration trend slope and the inlet temperature and humidity, calculating the equivalent aperture drift index; based on the above parameters, performing hierarchical working condition calibration; based on the change rate of the equivalent aperture drift index with time, generating a filter bag replacement warning signal; recording historical events that do not meet the expectations under extreme temperature and humidity conditions, constructing a calibration prohibited black list area and switching to a protective shutdown mode. The application realizes the organic integration of temperature and humidity linkage compensation, multi-parameter collaborative identification and hierarchical adaptive calibration.

Description

Technical Field

[0001] This invention belongs to the field of industrial dust removal technology, and relates to a method and system for calibrating the working conditions of a bag filter based on temperature and humidity linkage. Background Technology

[0002] Baghouse dust collectors are among the most widely used particulate matter capture devices in the field of industrial flue gas treatment. Their working principle involves using the filtration effect of fibrous fabric to trap particulate matter in dust-laden gas on the surface of the filter bags. In actual operation, the filtration performance of the filter bags is not constant but is affected by a combination of factors, including inlet flue gas temperature, humidity, dust load, and pulse-jet cleaning parameters.

[0003] Current baghouse dust collectors primarily employ timed and pressure-controlled cleaning, triggering pulse jet cleaning at fixed time intervals or set differential pressure thresholds. However, when inlet conditions, particularly temperature and humidity, change, the filtration characteristics of the filter bags and the shedding characteristics of the dust layer alter. Fixed parameters cannot adapt to dynamic changes, easily leading to over-cleaning causing increased emission concentrations or under-cleaning causing excessive operating resistance. Some solutions use the baghouse differential pressure or outlet emission concentration as a single feedback signal to adjust the jet cleaning parameters, but a single parameter cannot fully reflect the true state of the filter bags. When the filter bags experience minor damage, the emission concentration may increase, but the differential pressure change may be minimal. Conversely, when dust accumulates on the filter bag surface, the differential pressure may increase, but the emission concentration may remain within the normal range. Relying solely on a single parameter can easily lead to misjudgments. Other solutions divide the dust collector into several zones for separate cleaning control, but existing solutions typically adjust based solely on differential pressure or dust load monitoring results, failing to fully consider the differences in inlet temperature and humidity between zones and the impact of temperature and humidity on the microstructure of the filter bag fiber material.

[0004] The key problem that current technologies have not yet solved is that temperature and humidity not only affect the adhesion characteristics and peeling difficulty of dust layers, but also cause the filter bag fiber material to expand due to moisture absorption or shrink due to thermal expansion, thereby changing the equivalent pore size structure of the filter bag. This change in microstructure affects filtration efficiency and pressure drop characteristics, but existing solutions lack a mechanism for quantitatively correlating temperature and humidity parameters with changes in the filter bag's state, making it impossible to achieve accurate adaptive calibration under operating conditions. Summary of the Invention

[0005] In view of this, in order to solve the problems mentioned in the background technology, a method and system for calibrating the working conditions of bag filters based on temperature and humidity linkage is proposed.

[0006] The objective of this invention can be achieved through the following technical solution: The first aspect of this invention provides a method for calibrating the working conditions of a bag filter based on temperature and humidity linkage, including: collecting inlet temperature and humidity, bag chamber pressure difference time series data and particulate matter emission concentration data of each sub-region.

[0007] After each pulse jet, the initial slope of the differential pressure recovery curve and the steady-state residual differential pressure of each sub-region are extracted, and the slope of the emission concentration trend of each sub-region is calculated.

[0008] Based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and inlet temperature and humidity, the equivalent aperture drift index of each sub-region is calculated.

[0009] Stratified operating condition calibration is performed based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and equivalent aperture drift index.

[0010] A filter bag replacement warning signal is generated based on the rate of change of the equivalent pore size drift index over time.

[0011] Record historical events where calibration results did not meet expectations under extreme temperature and humidity conditions, and construct a blacklist area for prohibited calibration. If the current operating condition falls into the blacklist area, switch to protective shutdown mode.

[0012] The second aspect of the present invention provides a bag filter operating condition calibration system based on temperature and humidity linkage, comprising: a differential pressure curve acquisition module, used to acquire inlet temperature and humidity, bag chamber differential pressure time series data and particulate matter emission concentration data of each sub-region.

[0013] The emission concentration monitoring module is used to extract the initial slope and steady-state residual pressure difference of the pressure difference recovery curve of each sub-region after each pulse injection, and to calculate the emission concentration trend slope of each sub-region.

[0014] The feature extraction module is used to calculate the equivalent aperture drift index of each sub-region based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and inlet temperature and humidity.

[0015] The collaborative verification analysis module is used to perform stratified operating condition calibration based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and equivalent aperture drift index.

[0016] The operating condition deviation judgment module is used to generate a filter bag replacement early warning signal based on the rate of change of the equivalent pore size drift index over time.

[0017] The dust removal adaptive calibration module is used to record historical events where the calibration effect did not meet expectations under extreme temperature and humidity conditions, and to build a blacklist area for prohibited calibration. If the current operating condition falls into the blacklist area, it switches to protective shutdown mode.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By introducing inlet temperature and humidity parameters, the present invention quantifies the expansion and contraction characteristics of filter bag fibers under the influence of temperature and humidity, corrects the equivalent pore size reference value, and enables the calibration results to adapt to the influence of temperature and humidity changes, significantly improving the calibration accuracy under fluctuating temperature and humidity conditions.

[0019] 2. This invention, through the synergistic analysis of the initial slope of the differential pressure recovery curve, the steady-state residual differential pressure, the trend slope of the emission concentration, and the equivalent aperture drift index, can accurately distinguish between blockage risk conditions, ash leakage risk conditions, and pseudo-fluctuation conditions, thus avoiding miscalibration caused by a single parameter judgment.

[0020] 3. This invention develops differentiated calibration strategies for different operating conditions, achieving precise application of measures, reducing ineffective and excessive blowing, and extending the service life of the filter bags. Based on the rate of change of the equivalent pore size drift index over time, it can predict in advance whether the filter bags will undergo irreversible thermal and wet aging, generating a replacement warning signal before the filter bags fail, thus realizing a shift from passive maintenance to predictive maintenance.

[0021] 4. This invention constructs a blacklist area for prohibited calibration, and when the calibration effect fails to meet the standard under extreme temperature and humidity conditions, it actively switches to a protective shutdown mode, thus avoiding irreversible damage to the filter bag caused by forced calibration. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments 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.

[0023] Figure 1 This is a schematic diagram illustrating the implementation steps of the method of the present invention.

[0024] Figure 2 This is a schematic diagram of the system module connections of the present invention.

[0025] Figure 3 This is a schematic diagram of the differential pressure recovery curve and characteristic parameter extraction of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 1 As shown, the first aspect of the present invention provides a method for calibrating the working conditions of a bag filter based on temperature and humidity linkage, the specific steps of which are as follows: collecting the inlet temperature and humidity, bag chamber pressure difference time series data and particulate matter emission concentration data of each sub-region.

[0028] It should be noted that baghouse dust collectors typically consist of multiple bag chambers, each containing a number of filter bags. Sub-regions are divided in the following ways: By bag chamber physical structure, each bag chamber is considered an independent sub-region, equipped with an independent inlet valve, outlet valve, and pulse jet cleaning assembly. This method is suitable for small and medium-sized dust collectors with a limited number of bag chambers. By airflow channel, for large baghouse dust collectors, two to four adjacent bag chambers along the flue gas flow direction are combined into one sub-region. The division is based on the following criteria: the inlet temperature and humidity fluctuations of each bag chamber within the same sub-region do not exceed 5% of the relative value, and the pressure difference time-series curves of each bag chamber have similar morphological characteristics, with a Pearson correlation coefficient of not less than 0.85.

[0029] Furthermore, sensors are deployed in each sub-region. It should be noted that the number and location of the sensors directly affect the accuracy and representativeness of the data acquisition. For example, temperature and humidity sensors are installed in the inlet flue of each sub-region, using capacitive temperature and humidity probes with a temperature accuracy of ±0.3 degrees Celsius and a relative humidity accuracy of ±2%. The sensors are installed at locations where the flue gas is uniformly mixed, at least five times the equivalent pipe diameter from upstream bends or reducers, and with a sampling frequency of at least 0.1 Hz.

[0030] Furthermore, the temperature and humidity sensors are installed in the inlet flue rather than the outlet flue because the flue gas conditions at the inlet directly reflect the current gas conditions entering the filter bags, which are the most critical factors affecting the expansion of filter bag fibers and the characteristics of the dust layer. Differential pressure sensors are installed between the clean air side and the dust-laden side of each sub-area's bag chamber, using differential pressure transmitters with a range of 0–2000 Pa, an accuracy of ±1% of full scale, and a sampling frequency of no less than 1 Hz. Particulate matter concentration detectors are installed in the main outlet flue of the dust collector, using laser scattering or electrostatic induction methods, with a range of 0–200 mg / m³, a detection limit not exceeding 0.5 mg / m³, and a sampling cycle of no less than once per minute.

[0031] After each pulse jet, the initial slope of the differential pressure recovery curve and the steady-state residual differential pressure of each sub-region are extracted, and the slope of the emission concentration trend of each sub-region is calculated.

[0032] It should be noted that the pressure recovery curve refers to the time-series curve of the pressure difference over time, which is composed of the differential pressure data collected by the differential pressure sensor after each pulse jet cleaning action. Its typical form is that the pressure difference drops sharply to a trough value at the moment of cleaning, at which point most of the dust layer on the filter bag surface is peeled off; subsequently, as the dust-laden gas continues to be filtered, the dust layer gradually reforms on the filter bag surface, the pressure difference gradually rises from the trough value and tends to stabilize, entering the next filtration cycle.

[0033] Furthermore, the acquisition time window for the differential pressure recovery curve is set as follows: the window starts at the rising edge of the pulse jet trigger signal plus 50 milliseconds, taking into account the opening response delay of the jet valve; the window ends at the moment when the differential pressure value changes by no more than ±5 Pa within 30 consecutive seconds; the data sampling frequency is not less than 1 Hz.

[0034] In a preferred embodiment of the present invention, the specific method for extracting the initial slope and steady-state residual pressure of the pressure recovery curve of each sub-region is as follows: after each pulse jet action, the bag chamber pressure difference data of the sub-region is collected at a sampling frequency not lower than a preset frequency, and a complete time-series curve containing the pressure difference from the peak value to the steady-state value is generated.

[0035] Identify the valley point and steady-state point of the time series curve, calculate the rate of change of pressure difference with time in the interval from the valley point to the steady-state point, and use this rate of change as the initial slope of the pressure difference recovery curve.

[0036] Calculate the difference between the steady-state value and the base pressure difference of the sub-region before this injection, and use this difference as the steady-state residual pressure difference.

[0037] It should be further explained that the initial slope extraction steps are as follows: the lowest point of the pressure difference is taken as the trough point, and the time corresponding to the trough point and the recovery amplitude reaching a preset percentage of the total recovery amplitude is taken as the end point. The value of this point is based on the definition of the time constant of the exponential response process. Within this interval, the pressure difference rises fastest and is closest to linear, and the calculated slope best reflects the initial rate of dust layer reformation. Within the determined calculation interval, the pressure difference time data is linearly fitted using the least squares method, and the slope value of the fitted line is the initial slope of the pressure difference recovery curve, in Pascals per second.

[0038] For example, the preset percentage of the total recovery is 63.2%. It should be noted that, in the differential pressure recovery curve, the process of dust layer reforming after the purging process can be described by a first-order exponential function: ,in Valley pressure difference, For steady-state pressure difference, is a time constant. When At that time, the pressure difference rebounded by a certain amount. Exactly equal to the total rebound of This is 63.2%. Mathematically, the second derivative of the exponential function at this point is zero, meaning that this point is precisely the inflection point where the function curve changes from increasing to decreasing growth rate. In other words, at... Within the previous range, the rate of increase in pressure differential gradually increased; in In the subsequent interval, the rate of increase in pressure differential gradually decreased; while... Within a nearby neighborhood, the rate of change of pressure difference is closest to a constant value, and the error of linear fitting is minimized.

[0039] Therefore, choosing 63.2% as the end point of the slope calculation interval essentially selects the interval with the optimal linearity in the exponential response process. If too small a percentage is selected, the calculation interval falls into the hysteresis period when the pressure difference is still slowly recovering, and the fitting results are easily affected by noise near the trough. If too large a percentage is selected, the calculation interval extends to the saturation period when the pressure difference has entered a state close to steady state, and the slope of the fitted line will deviate from the true initial recovery rate. 63.2% is precisely located in the middle between the hysteresis period and the saturation period, which can fully reflect the initial rate characteristics of dust layer reformation, and can suppress the errors caused by noise and saturation effects to the greatest extent. It is the mathematically optimal solution that balances linearity and representativeness.

[0040] It should be noted that the steady-state residual pressure difference is calculated as the difference between the steady-state point pressure difference and the baseline pressure difference. The steady-state point is the pressure difference value when the pressure difference recovery curve reaches a steady state, i.e., the average pressure difference within the 30 seconds before the end of the window. The baseline pressure difference is the baseline pressure difference value of this sub-region before this pulse-jet cleaning, taken as the average of the pressure difference time-series data within the 60 seconds before the start of this pulse-jet cleaning action. The reason for using a 60-second window to calculate the baseline pressure difference is that this time period can cover at least one complete filtration cycle, including the entire contribution of the dust layer accumulation process to the pressure difference. Using this as a benchmark allows for a more accurate assessment of the contribution of the residual dust layer to the pressure difference after pulse-jet cleaning, avoiding the introduction of instantaneous fluctuation noise due to an excessively short window or the inclusion of the cumulative effects of historical residues due to an excessively long window. When the steady-state residual pressure difference continues to increase, it indicates that the amount of residual dust after each pulse-jet cleaning is increasing, and early signs of dust caking or blockage are gradually appearing on the filter bag surface.

[0041] Please see Figure 3 As shown in the figure, the graph is a schematic diagram of the recovery curve of the sub-regional bag chamber pressure difference over time during one complete pulse jet cycle. The horizontal axis in the figure represents time. The unit is seconds, and the vertical axis represents the pressure difference. The unit is Pascal (Pa). The overall shape of the curve exhibits the following characteristics: before the injection is triggered, the pressure difference remains at a high level, corresponding to the baseline pressure difference value; at the moment of injection triggering, compressed air impacts the filter bag surface in the reverse direction, and the pressure difference drops sharply. The pressure drops to the trough B; after the pulse-jet cleaning ends, a dust layer reforms on the filter bag surface, and the pressure differential gradually recovers from the trough according to an exponential law, eventually tending towards a steady-state value. Point D corresponds to the completion of a full filtration cycle. In the diagram, point A is the trigger point for the injection, point B is the trough of the pressure difference, point C is the moment when the pressure difference recovery reaches 63.2% of the total recovery, which corresponds to a time constant τ in the exponential response process, and point D is the moment when the pressure difference reaches its steady-state value. A linear fit is performed on the pressure difference-time data within the interval from point B to point C; the slope of the fitted line is the initial slope of the pressure difference recovery curve. Steady-state pressure difference Differential pressure with base value The difference between them is the steady-state residual pressure difference. .

[0042] Furthermore, the initial slope of the differential pressure recovery curve and the steady-state residual differential pressure are the fundamental inputs for constructing the filter bag state perception model in this invention: the initial slope of the differential pressure recovery curve reflects the rate at which the dust layer reforms after each pulse-jet cleaning, and its decrease relative to the historical baseline indicates the attenuation trend of the filter bag surface porosity; the steady-state residual differential pressure reflects the thickness of the dust layer remaining on the filter bag surface after pulse-jet cleaning, and its continuous increasing trend indicates early signs of dust caking. In subsequent steps, this parameter will be analyzed in conjunction with the emission concentration trend slope and the inlet temperature and humidity parameters. On the one hand, it is used to calculate the equivalent pore size drift index to achieve temperature and humidity compensation correction; on the other hand, it serves as the basis for the stratified operating condition calibration decision logic, distinguishing between three different types of abnormal operating conditions: clogging risk, ash leakage risk, and pseudo-fluctuations, thereby generating differentiated cleaning parameter adjustment instructions.

[0043] In a preferred embodiment of the present invention, the specific method for calculating the slope of the emission concentration trend of each sub-region is as follows: with a preset time window as the period, the particulate matter emission concentration data of the sub-region is continuously collected to generate an emission concentration time series.

[0044] A linear regression is performed on the time series of emission concentrations to calculate the slope of the regression line, and this slope is used as the trend slope of the emission concentrations.

[0045] When the slope of the emission concentration trend is positive and continues to increase within a preset number of time windows, it is determined that the emission concentration is showing an upward trend.

[0046] It should be noted that when the emission concentration trend slope is positive and the trend slope value increases sequentially within a preset number of time windows, the emission concentration is determined to be on an upward trend. The reason for using a continuous increase rather than a single increase as the criterion is as follows: a single increase in concentration may be a false increase caused by accidental factors such as localized shedding of dust layer on the filter bag surface or instantaneous fluctuations in inlet dust load, while a continuous increase in the trend slope over multiple consecutive windows eliminates the interference of accidental factors and more reliably reflects the continuous deterioration of filter bag filtration performance.

[0047] Based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and inlet temperature and humidity, the equivalent aperture drift index of each sub-region is calculated.

[0048] In a preferred embodiment of the present invention, the specific method for calculating the equivalent pore size drift index of each sub-region is as follows: based on the inlet temperature and humidity data of the sub-region, combined with the expansion characteristic parameters of the filter bag fiber material under preset temperature and humidity conditions, the theoretical equivalent pore size benchmark value of the filter bag under the current temperature and humidity is calculated.

[0049] Obtain the initial slope and steady-state residual pressure of the pressure recovery curve for the sub-region. Perform deviation analysis between the initial slope and steady-state residual pressure and the corresponding historical benchmark values ​​to obtain the initial slope deviation and steady-state residual pressure deviation.

[0050] The initial slope deviation, steady-state residual pressure deviation, and theoretical equivalent aperture benchmark value are weighted and fused to obtain the equivalent aperture drift index of the sub-region.

[0051] It should be noted that the equivalent pore size drift index is the core innovation of this invention. The microstructure of filter bag fiber materials changes under the influence of temperature and humidity: when the temperature rises, the movement of fiber molecular chain segments intensifies, causing thermal expansion of the fibers. This expansion of the fiber diameter leads to a decrease in the pore size between fibers, i.e., the equivalent pore size; when the humidity rises, the fibers absorb water and swell, especially those with strong hygroscopicity. The effects of temperature and humidity on fiber expansion are not a simple linear superposition. Under high temperature and high humidity conditions, the flexibility of the fiber molecular chains increases, amplifying the water absorption and swelling effect. Therefore, this invention employs a temperature and humidity coupling model.

[0052] Furthermore, the theoretical equivalent pore size benchmark value is calculated using a temperature and humidity coupled formula. Based on the inlet temperature and humidity data of this sub-region, combined with the expansion characteristic parameters of the filter bag fiber material under preset temperature and humidity conditions, the theoretical equivalent pore size benchmark value of the filter bag under the current temperature and humidity is calculated. The formula is: .in For filter bag fibers at reference temperature and reference relative humidity The nominal equivalent pore size is provided by the filter bag supplier or obtained through laboratory scanning electron microscopy image analysis. The current inlet temperature, This represents the current relative humidity at the inlet. The coefficient of thermal expansion of the fiber material. This is the coefficient of hygroscopic expansion of the fiber material. These parameters, β, are obtained through laboratory fiber expansion tests, representing the temperature-humidity coupling coefficient. It should be noted that the physical meaning of the temperature-humidity coupling coefficient β is the amplification factor of the temperature-humidity expansion effect. A positive value indicates that the higher the temperature, the more significant the hygroscopic expansion effect of the fiber. This pattern is consistent with the physical characteristic of increased molecular chain mobility in polymer materials near their glass transition temperature.

[0053] For example, typical parameter values ​​for different filter bag materials are shown in the table below: Table 1. Expansion characteristics of different filter bag materials ; It should be noted that the above parameters are configured in the controller before the system is put into operation, and the corresponding parameters are updated synchronously when the filter bag is replaced with a new material.

[0054] It should be added that the initial slope deviation amount The calculation method is as follows ,in This is the initial slope reference value of the differential pressure recovery curve for this sub-region during the initial stage of operation and under standard operating conditions. Steady-state residual differential pressure deviation. The calculation method is as follows ,in This is the benchmark value of steady-state residual pressure difference for this sub-region under standard operating conditions during the initial stage of operation. The reason for selecting the data from the initial operating stage as the benchmark is that the filter bag is in a brand-new state at this time, with an intact surface fiber structure and uniform pores, and its pressure difference response characteristics best represent the ideal working state of the filter bag.

[0055] It should be added that the equivalent aperture drift index The weighted fusion calculation formula is as follows: The weighting coefficient satisfy The weighting coefficients are set based on the following: initial slope deviation. This reflects the rate of dust reformation and is closely related to the porosity of the filter bag surface. It is most sensitive to the decrease in the initial slope when the filter bag is clogged; steady-state residual pressure deviation. This reflects the change in the amount of residual dust after cleaning; this indicator deteriorates first when the filter bag becomes irreversibly clogged. The temperature and humidity correction term reflects the theoretical drift of the equivalent pore size of the filter bag fibers due to changes in temperature and humidity, and is introduced as a feedforward compensation term. The specific values ​​of the weighting coefficients are determined during the system commissioning phase by collecting historical data under different operating conditions, using whether the final emission concentration meets the standards as the evaluation indicator, and optimizing the weighting coefficients through an optimization algorithm. Maximize the correlation with the actual filter bag condition.

[0056] It should be further explained that the theoretical meaning of the equivalent pore size drift index is that when the index is close to zero, it indicates that the overall state of the filter bag is basically the same as the initial state, and the filtration performance is normal. When the index is positive and gradually increases, it indicates that the filter bag is becoming clogged, and the equivalent pore size is shrinking. When the index is negative and the absolute value gradually increases, it indicates that the filter bag is experiencing pore size expansion, such as fiber wear or damage, which may lead to dust leakage.

[0057] Stratified operating condition calibration is performed based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and equivalent aperture drift index.

[0058] In a preferred embodiment of the present invention, the specific method for performing the stratified operating condition calibration is as follows: when the initial slope decreases and the steady-state residual pressure difference increases, and the slope of the emission concentration trend is lower than the preset concentration trend threshold, it is determined to be a blockage risk condition, and the pulse width is increased and the low-frequency micro-injection action is initiated.

[0059] When the slope of the emission concentration trend exceeds the preset concentration trend threshold and the equivalent aperture drift index increases, it is determined to be a ash leakage risk condition, and the injection pressure is reduced and the pre-coating compensation action is activated.

[0060] When a sudden increase in differential pressure is detected, but the initial slope and steady-state residual differential pressure do not change and the trend slope of emission concentration does not change, it is determined to be a false fluctuation condition. In this case, no calibration action is allowed, and only log data is recorded.

[0061] It should be noted that the determination of the three different operating conditions is based on the results of multi-parameter collaborative analysis, rather than a single-parameter threshold judgment. When the initial slope decreases, there may be two reasons: one is normal thickening of the dust layer, and the other is irreversible caking on the filter bag surface. These two situations cannot be distinguished by the initial slope alone, but the increase in steady-state residual pressure difference can confirm a decrease in dust removal efficiency, and the normal trend slope of emission concentration can rule out the possibility of dust leakage. All three factors together confirm the clogging risk condition. Similarly, when only the trend slope of emission concentration increases, it may be due to an increase in inlet dust load rather than filter bag damage, but the increase in the equivalent pore size drift index can confirm that the filter bag itself has suffered physical damage. The introduction of this multi-parameter cross-verification mechanism fundamentally avoids the misjudgment problem caused by a single threshold judgment.

[0062] In a preferred embodiment of the present invention, the specific method of increasing the pulse width and starting the low-frequency micro-jetting action is as follows: obtain the reference pulse width of the current blowing cycle, and increase the pulse width step by step according to the preset incremental step size, so that the dust layer on the surface of the filter bag falls off under low-speed peeling conditions.

[0063] Between two regular blowing actions, at least one low-frequency micro-blowing action is inserted, wherein the blowing pressure of the low-frequency micro-blowing action is less than that of the regular blowing action, and the blowing frequency is lower than that of the regular blowing action.

[0064] During the low-frequency micro-jet operation, the initial slope of the differential pressure recovery curve and the steady-state residual differential pressure of the sub-region are continuously monitored. When the steady-state residual differential pressure drops to the preset regression threshold, the operation is restored to the normal jetting mode.

[0065] It should be noted that increasing the pulse width aims to prolong the impact time of the jetting airflow on the filter bag, allowing the caked dust layer adhering to the fiber surface to gradually loosen and detach under low-speed peeling conditions. Low-speed peeling avoids damage to the filter bag fiber structure caused by strong impact. For example, the jetting pressure of low-frequency micro-jet is 50% to 70% of the conventional jetting pressure, and the jetting frequency is one-third to one-half of the conventional jetting frequency. The mechanism of low-frequency micro-jet is to continuously vibrate the filter bag surface with low energy, causing loosened but not yet detached dust particles to gradually detach from the fiber surface without causing secondary dust re-entrainment.

[0066] In a preferred embodiment of the present invention, the specific method for performing the action of reducing the blowing pressure and activating the pre-coating compensation is as follows: obtain the reference blowing pressure of the current blowing cycle, and gradually reduce the blowing pressure according to the preset decreasing step size to avoid the aging filter bag fibers from falling off due to strong blowing.

[0067] Activate the pre-coating compensation module to increase the amount of pre-coating powder applied to the surface of the filter bag corresponding to the sub-area, in order to compensate for the dust penetration caused by the increase in the equivalent pore size of the filter bag.

[0068] The slope of the emission concentration trend in this sub-region is continuously monitored. When the slope of the emission concentration trend drops below the preset safety threshold, the pressure is restored to the baseline spraying pressure and the pre-coating compensation action is stopped.

[0069] The purpose of reducing the blowing pressure is to avoid further impact damage to the aged or worn filter bag fibers caused by high-pressure blowing, and to prevent further enlargement of the pore size. Activating the pre-coating compensation module increases the amount of pre-coating powder applied to the filter bag surface corresponding to this sub-area to compensate for dust penetration caused by the increased equivalent pore size of the filter bag. The pre-coating powder uses limestone powder or talc powder, which forms an auxiliary filtration layer on the filter bag surface, filling the pores caused by the increased equivalent pore size and preventing particulate matter penetration. The amount of pre-coating powder applied is controlled linearly based on the absolute value of the current equivalent pore size drift index.

[0070] Furthermore, the ratio of coating amount to equivalent pore size drift index was determined through experimental calibration. The calibration method involved preparing filter bag samples with different degrees of equivalent pore size drift under laboratory conditions, testing the minimum coating amount required to achieve emission standards, and establishing a mapping relationship between the equivalent pore size drift index and the coating amount. The slope of the emission concentration trend in this sub-region was continuously monitored. When the slope of the emission concentration trend dropped below the preset safety threshold, the pressure was restored to the baseline blowing pressure, and the pre-coating compensation action was stopped.

[0071] In a preferred embodiment of the present invention, the specific identification method for determining a false fluctuation condition is as follows: obtain the instantaneous increase data of the differential pressure in the sub-region, and at the same time read the initial slope of the differential pressure recovery curve and the steady-state residual differential pressure of the sub-region in the current cycle.

[0072] The initial slope is compared with the historical average initial slope of the sub-region under normal operating conditions, and the steady-state residual pressure difference is compared with the historical average steady-state residual pressure difference of the sub-region under normal operating conditions.

[0073] When the instantaneous increase in differential pressure exceeds the preset differential pressure fluctuation threshold, but the initial slope deviation and steady-state residual differential pressure deviation are both within the preset normal fluctuation range, and the emission concentration trend slope does not exceed the preset concentration trend threshold, it is judged as a false fluctuation condition.

[0074] It should be noted that the identification of pseudo-fluctuation conditions uses a three-parameter comparison method. The first comparison is whether the instantaneous increase in differential pressure exceeds the preset differential pressure fluctuation threshold, the specific value of which depends on the differential pressure fluctuation amplitude under normal operating conditions in that sub-region. The second comparison is whether the deviation rate between the current initial slope and the historical average initial slope is within the preset normal fluctuation range, and whether the deviation rate between the current steady-state residual differential pressure and the historical average steady-state residual differential pressure is within the preset normal fluctuation range. The third comparison is whether the current emission concentration trend slope exceeds the preset concentration trend threshold. When all three conditions are met simultaneously, it is determined to be a pseudo-fluctuation condition. For events determined to be pseudo-fluctuation conditions, the system prohibits any calibration actions to avoid invalid pulse-jet abrasion of the filter bags due to misjudgment; the event is only recorded in the log database for post-event analysis by maintenance personnel.

[0075] It should be noted that the preset differential pressure fluctuation threshold depends on the standard deviation of the differential pressure under normal operating conditions in this sub-region. Typically, three times the standard deviation is used as the threshold; fluctuations below this value are considered normal. The preset normal fluctuation range refers to initial slope deviation and steady-state residual differential pressure deviation within ±15% to ±20%. For events judged as false fluctuations, the system prohibits any calibration actions to avoid ineffective pulse-jet abrasion of the filter bags due to misjudgment; the event is only recorded in the log database for post-event analysis by maintenance personnel.

[0076] A filter bag replacement warning signal is generated based on the rate of change of the equivalent pore size drift index over time.

[0077] In a preferred embodiment of the present invention, the specific method for generating the filter bag replacement early warning signal is as follows: the equivalent pore size drift index of each sub-region is continuously collected at a preset time interval to generate a time sequence of the equivalent pore size drift index of each sub-region.

[0078] The equivalent aperture drift index time series is differentiated to obtain the rate of change of the equivalent aperture drift index over time for each sub-region.

[0079] The rate of change is compared with the preset degradation threshold of the filter bag material corresponding to the sub-region. When the rate of change exceeds the preset degradation threshold for a consecutive preset number of cycles, it is determined that the filter bag fiber in the sub-region has undergone irreversible thermal and wet aging, and a filter bag replacement warning signal containing the location identifier of the sub-region is generated.

[0080] It should be noted that the degradation threshold is determined through either laboratory testing or field calibration. Laboratory testing involves conducting accelerated aging tests on the target filter bag material in a laboratory environment, recording the rate of change of the equivalent pore size drift index when the tensile breaking strength of the filter bag decreases to 50% of its initial value, and using this as a reference value for the degradation threshold. Field calibration involves selecting a region of filter bags that have been in service and are nearing their expected lifespan after the system is put into operation, and using the average rate of change of the equivalent pore size drift index of this sub-region over a period before replacement as the baseline value for the degradation threshold.

[0081] Record historical events where calibration results did not meet expectations under extreme temperature and humidity conditions, and construct a blacklist area for prohibited calibration. If the current operating condition falls into the blacklist area, switch to protective shutdown mode.

[0082] It should be noted that in actual industrial operation, there are certain extreme temperature and humidity conditions that render any calibration actions ineffective in improving the filter bag's condition, and may even exacerbate filter bag damage. For example, under high temperature and high humidity conditions, the filter bag fibers are close to the critical point of thermal and moisture aging. At this time, pulse-jet cleaning may cause fiber cracking due to thermal stress, and the pre-coated powder may sinter and agglomerate due to high temperature, clogging the filter pores. Another example is under low temperature dew point conditions, where flue gas condenses on the filter bag surface, and the dust layer forms a muddy paste in a moist state. Any pulse-jet cleaning action cannot effectively remove this paste, and may even cause the filter bag surface to become caked.

[0083] In a preferred embodiment of the present invention, the specific method for constructing the blacklist area for prohibited calibration is as follows: each time a calibration action is triggered due to extreme temperature and humidity conditions, the actual execution effect data of the calibration action is collected. The actual execution effect data includes the improvement value of the initial slope of the differential pressure recovery curve after calibration, the reduction value of the steady-state residual differential pressure, and the change value of the emission concentration.

[0084] The actual performance data is compared with the preset calibration performance threshold. When the initial slope improvement value, steady-state residual pressure reduction value, and emission concentration change value are all lower than the corresponding threshold, the calibration action is determined to be a failure event, and the inlet temperature and humidity data at the time of the failure event are recorded as blacklist operating condition parameters.

[0085] The blacklisted operating condition parameters are added to the prohibited calibration blacklist database. Before the next calibration action is performed, the currently collected inlet temperature and humidity data are matched with each blacklisted operating condition parameter in the prohibited calibration blacklist database. When the match is successful, the system switches to protective shutdown mode.

[0086] The blacklist of areas where calibration is prohibited is stored in the system controller in the form of a two-dimensional coordinate system, with temperature on the horizontal axis and relative humidity on the vertical axis. The blacklist is dynamically updated. Whenever a new invalid calibration event occurs, it is checked whether the temperature and humidity coordinates corresponding to the event are within the existing blacklist area. If not, the boundaries are expanded or a new sub-region is added. If a blacklist sub-region has not triggered an invalid calibration event in the past consecutive operating cycles, it is removed from the blacklist.

[0087] The purpose of the dynamic update mechanism is to enable the blacklist to adaptively reflect changes in filter bag status and operating conditions. It should be noted that the blacklist area recovery mechanism is to prevent the system from being overprotected when previously invalid temperature and humidity ranges become valid again due to filter bag replacement or process improvements, thus preventing calibration from being performed within those ranges.

[0088] Furthermore, when the system detects that the current inlet temperature and humidity coordinates of any sub-region fall into the prohibited calibration blacklist area, the shutdown level is determined based on the deviation distance. When the deviation distance is less than the first threshold, a Level 1 shutdown is executed, immediately shutting off the inlet valve and purging the system. When the deviation distance is between the first and second thresholds, a Level 2 shutdown is executed, reducing the blowing frequency to the minimum maintenance frequency and issuing an alarm. When the deviation distance is greater than or equal to the second threshold, a Level 3 warning is executed. After entering protective shutdown mode, the system stops automated calibration and awaits confirmation from maintenance personnel for recovery.

[0089] Please see Figure 2 As shown, the second aspect of the present invention provides a bag filter dust collector operating condition calibration system based on temperature and humidity linkage, including a differential pressure curve acquisition module, an emission concentration monitoring module, a recovery feature extraction module, a collaborative verification analysis module, an operating condition deviation judgment module, and a dust removal adaptive calibration module. The differential pressure curve acquisition module is connected to the emission concentration monitoring module, the emission concentration monitoring module is connected to the recovery feature extraction module, the recovery feature extraction module is connected to the collaborative verification analysis module, the collaborative verification analysis module is connected to both the operating condition deviation judgment module and the dust removal adaptive calibration module, the operating condition deviation judgment module is connected to the dust removal adaptive calibration module, and the dust removal adaptive calibration module is connected to the collaborative verification analysis module to form a feedback loop.

[0090] The differential pressure curve acquisition module is used to collect inlet temperature and humidity, bag chamber differential pressure time series data, and particulate matter emission concentration data for each sub-region.

[0091] The emission concentration monitoring module is used to extract the initial slope and steady-state residual pressure difference of the pressure difference recovery curve of each sub-region after each pulse injection, and to calculate the emission concentration trend slope of each sub-region.

[0092] The recovery feature extraction module is used to calculate the equivalent aperture drift index of each sub-region based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and inlet temperature and humidity.

[0093] The collaborative verification analysis module is used to perform stratified operating condition calibration based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and equivalent aperture drift index.

[0094] The operating condition deviation judgment module is used to generate a filter bag replacement early warning signal based on the rate of change of the equivalent aperture drift index over time.

[0095] The dust removal adaptive calibration module is used to record historical events where the calibration effect did not meet expectations under extreme temperature and humidity conditions, and to build a blacklist area for prohibited calibration. If the current operating condition falls into the blacklist area, it switches to protective shutdown mode.

[0096] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A method for calibrating the operating conditions of a baghouse dust collector based on temperature and humidity linkage, characterized in that: include: Collect time-series data on inlet temperature and humidity, baghouse pressure difference, and particulate matter emission concentration for each sub-region; After each pulse jet, the initial slope and steady-state residual pressure difference of the pressure difference recovery curve of each sub-region are extracted, and the slope of the emission concentration trend of each sub-region is calculated. Based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and inlet temperature and humidity, the equivalent aperture drift index of each sub-region is calculated. Stratified operating condition calibration is performed based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and equivalent aperture drift index. A filter bag replacement early warning signal is generated based on the rate of change of the equivalent pore size drift index over time. Record historical events where calibration results did not meet expectations under extreme temperature and humidity conditions, and construct a blacklist area for prohibited calibration. If the current operating condition falls into the blacklist area, switch to protective shutdown mode.

2. The method for calibrating baghouse dust collector operating conditions based on temperature and humidity linkage according to claim 1, characterized in that: The specific method for extracting the initial slope and steady-state residual pressure of the pressure recovery curve for each sub-region is as follows: After each pulse jet action, the bag chamber differential pressure data of the sub-region is collected at a sampling frequency no less than the preset sampling frequency to generate a complete time series curve containing the differential pressure from the peak value to the steady state value; Identify the valley point and steady-state point of the time series curve, calculate the rate of change of pressure difference with time in the interval from the valley point to the steady-state point, and use this rate of change as the initial slope of the pressure difference recovery curve; Calculate the difference between the steady-state value and the base pressure difference of the sub-region before this injection, and use this difference as the steady-state residual pressure difference.

3. The method for calibrating baghouse dust collector operating conditions based on temperature and humidity linkage according to claim 1, characterized in that: The specific method for calculating the slope of the emission concentration trend in each sub-region is as follows: The particulate matter emission concentration data of this sub-region is continuously collected with a preset time window as the period to generate an emission concentration time series. A linear regression was performed on the time series of emission concentrations, and the slope of the regression line was calculated. This slope was used as the trend slope of the emission concentrations. When the slope of the emission concentration trend is positive and continues to increase within a preset number of time windows, it is determined that the emission concentration is showing an upward trend.

4. The method for calibrating baghouse dust collector operating conditions based on temperature and humidity linkage according to claim 1, characterized in that: The specific method for calculating the equivalent aperture drift index of each sub-region is as follows: Based on the inlet temperature and humidity data of this sub-region, and combined with the expansion characteristic parameters of the filter bag fiber material under preset temperature and humidity conditions, the theoretical equivalent pore size benchmark value of the filter bag under the current temperature and humidity is calculated. The initial slope and steady-state residual pressure of the pressure recovery curve of the sub-region are obtained. The initial slope and steady-state residual pressure are compared with the corresponding historical benchmark values ​​to obtain the initial slope deviation and steady-state residual pressure deviation. The initial slope deviation, steady-state residual pressure deviation, and theoretical equivalent aperture benchmark value are weighted and fused to obtain the equivalent aperture drift index of the sub-region.

5. The method for calibrating baghouse dust collector operating conditions based on temperature and humidity linkage according to claim 1, characterized in that: The specific method for performing tiered operating condition calibration is as follows: When the initial slope decreases and the steady-state residual pressure difference increases, and the slope of the emission concentration trend is lower than the preset concentration trend threshold, it is determined to be a blockage risk condition, and the pulse width is increased and the low-frequency micro-injection action is initiated. When the slope of the emission concentration trend exceeds the preset concentration trend threshold and the equivalent aperture drift index increases, it is determined to be a ash leakage risk condition, and the injection pressure is reduced and the pre-spraying compensation action is activated. When a sudden increase in differential pressure is detected, but the initial slope and steady-state residual differential pressure do not change and the trend slope of emission concentration does not change, it is determined to be a false fluctuation condition. In this case, no calibration action is allowed, and only log data is recorded.

6. The method for calibrating baghouse dust collector operating conditions based on temperature and humidity linkage according to claim 5, characterized in that: The specific method for increasing the pulse width and initiating the low-frequency micro-jet action is as follows: Obtain the reference pulse width for the current blowing cycle, and gradually increase the pulse width according to the preset incremental step size, so that the dust layer on the surface of the filter bag falls off under low-speed peeling conditions; Between two regular blowing actions, at least one low-frequency micro-blowing action is inserted, wherein the blowing pressure of the low-frequency micro-blowing action is less than the blowing pressure of the regular blowing action, and the blowing frequency is lower than the frequency of the regular blowing action. During the low-frequency micro-jet operation, the initial slope of the differential pressure recovery curve and the steady-state residual differential pressure of the sub-region are continuously monitored. When the steady-state residual differential pressure drops to the preset regression threshold, the operation is restored to the normal jetting mode.

7. The method for calibrating baghouse dust collector operating conditions based on temperature and humidity linkage according to claim 5, characterized in that: The specific method for reducing the spray pressure and activating the pre-coating compensation action is as follows: Obtain the reference blowing pressure for the current blowing cycle, and gradually reduce the blowing pressure according to the preset decreasing step size to avoid the aging filter bag fibers falling off due to strong blowing. Activate the pre-coating compensation module to increase the amount of pre-coating powder applied to the surface of the filter bag corresponding to the sub-area, in order to compensate for the dust penetration caused by the increase in the equivalent pore size of the filter bag. The slope of the emission concentration trend in this sub-region is continuously monitored. When the slope of the emission concentration trend drops below the preset safety threshold, the pressure is restored to the baseline spraying pressure and the pre-coating compensation action is stopped.

8. The method for calibrating baghouse dust collector operating conditions based on temperature and humidity linkage according to claim 5, characterized in that: The specific identification method for the pseudo-fluctuation condition is as follows: Acquire the instantaneous increase data of differential pressure in this sub-region, and simultaneously read the initial slope and steady-state residual differential pressure of the differential pressure recovery curve for the current period in this sub-region; The initial slope is compared with the historical average initial slope of the sub-region under normal operating conditions, and the steady-state residual pressure difference is compared with the historical average steady-state residual pressure difference of the sub-region under normal operating conditions. When the instantaneous increase in differential pressure exceeds the preset differential pressure fluctuation threshold, but the initial slope deviation and steady-state residual differential pressure deviation are both within the preset normal fluctuation range, and the emission concentration trend slope does not exceed the preset concentration trend threshold, it is judged as a false fluctuation condition.

9. The method for calibrating baghouse dust collector operating conditions based on temperature and humidity linkage according to claim 1, characterized in that: The specific method for generating the filter bag replacement early warning signal is as follows: The equivalent aperture drift index of each sub-region is continuously collected at a preset time interval to generate a time series of the equivalent aperture drift index of each sub-region. The equivalent aperture drift index time series is differentially calculated to obtain the rate of change of the equivalent aperture drift index of each sub-region over time. The rate of change is compared with the preset degradation threshold of the filter bag material corresponding to the sub-region. When the rate of change exceeds the preset degradation threshold for a consecutive preset number of cycles, it is determined that the filter bag fiber in the sub-region has undergone irreversible thermal and wet aging, and a filter bag replacement warning signal containing the location identifier of the sub-region is generated.

10. A bag filter dust collector operating condition calibration system based on temperature and humidity linkage, characterized in that: include: The differential pressure curve acquisition module is used to collect inlet temperature and humidity, bag chamber differential pressure time series data, and particulate matter emission concentration data for each sub-region; The emission concentration monitoring module is used to extract the initial slope and steady-state residual pressure difference of the pressure difference recovery curve of each sub-region after each pulse injection, and to calculate the emission concentration trend slope of each sub-region. The feature extraction module is used to calculate the equivalent aperture drift index of each sub-region based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and inlet temperature and humidity. The collaborative verification and analysis module is used to perform stratified operating condition calibration based on the initial slope, steady-state residual pressure difference, emission concentration trend slope, and equivalent aperture drift index. The working condition deviation judgment module is used to generate a filter bag replacement early warning signal based on the rate of change of the equivalent pore size drift index over time. The dust removal adaptive calibration module is used to record historical events where the calibration effect did not meet expectations under extreme temperature and humidity conditions, and to build a blacklist area for prohibited calibration. If the current operating condition falls into the blacklist area, it switches to protective shutdown mode.

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