A slurry pH self-adaptive control method for a wet flue gas desulfurization system of a thermal power plant

Abstract

The present application relates to the technical field of wet desulfurization control, and discloses a slurry pH adaptive control method for a wet desulfurization system of a thermal power plant, which comprises collecting the SO2 concentration at the inlet of an absorption tower, the inlet flue gas flow, the slurry pH, the slurry density and the limestone slurry supply flow, calculating the acid load change rate and the slurry pH response trend index, and identifying the operating state according to the combination relationship of the two; generating the corresponding limestone slurry compensation amount according to different operating states, and adjusting the limestone slurry supply flow; performing density constraint correction in combination with the slurry density, and performing overshoot suppression correction in combination with the slurry pH recovery trend and the acid load back-off trend; and updating the control parameters according to the operating data and using them for the subsequent control process. The present application identifies the operating state by combining the acid load change rate and the slurry pH response trend index, so that the inlet flue gas working condition change and the slurry response state jointly participate in the control process, thereby reducing the control lag.

Description

Technical Field

[0001] This invention belongs to the field of wet desulfurization control technology, specifically relating to an adaptive control method for the slurry pH value of a wet desulfurization system in a thermal power plant. Background Technology

[0002] Wet desulfurization technology is one of the most widely used technologies in flue gas desulfurization treatment in thermal power plants. It removes sulfur dioxide by having limestone slurry react with sulfur dioxide in the flue gas.

[0003] In existing wet desulfurization systems, the pH value of the slurry is typically acquired in real time using an online pH monitoring device, and the limestone slurry supply flow rate is adjusted based on the deviation between the current slurry pH value and the target pH value. When a decrease in the slurry pH value is detected, the limestone slurry supply rate is increased; when an increase in the slurry pH value is detected, the limestone slurry supply rate is decreased. This type of control method mainly relies on the slurry pH value feedback signal for adjustment. Its control logic is based on the slurry pH value change result, and the limestone slurry supply rate is adjusted through feedback control.

[0004] However, those skilled in the art discovered during the implementation of the above-mentioned technical solutions that the slurry pH value feedback control method in the prior art mainly relies on the result of changes in slurry pH value for adjustment. However, there is a mass transfer and reaction delay between changes in the flue gas conditions at the inlet of the absorption tower and changes in slurry pH value. When the acid load in the inlet flue gas changes, the slurry pH value often cannot reflect the change synchronously, resulting in the limestone slurry supply adjustment process lagging behind the actual changes in operating conditions, and there is a control lag problem. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide an adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant. This method improves the problem that the existing slurry pH feedback control method mainly adjusts the slurry pH based on the change in slurry pH, while there is a mass transfer and reaction delay between the change in flue gas conditions at the absorber inlet and the change in slurry pH, resulting in the limestone slurry supply adjustment process lagging behind the actual change in operating conditions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides the following technical solution: an adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant, comprising the following steps: S1. Collect the SO2 concentration at the inlet of the absorption tower, the inlet flue gas flow rate, the pH value of the slurry, the slurry density, and the limestone slurry supply flow rate, and smooth the pH value of the slurry to obtain a smoothed slurry pH value. S2. Calculate the inlet acid load index based on the SO2 concentration at the inlet of the absorption tower and the inlet flue gas flow rate, and calculate the smooth acid load change rate based on the inlet acid load index; S3. Calculate the pH response trend index of the slurry based on the pH value of the smooth slurry at continuous time points; S4. Identify the current operating status of the wet desulfurization system based on the combined relationship between the smooth acid load change rate and the slurry pH response trend index; S5. Generate limestone slurry compensation amount based on the identified operating status, and adjust the limestone slurry supply flow rate according to the limestone slurry compensation amount. S6. The adjusted limestone slurry supply flow rate is corrected by density constraint based on the slurry density, and overrush suppression correction is performed based on the smoothing slurry pH value and the smoothing acid load change rate. S7. Update the control parameters based on the operating data recorded during this adjustment process, and use the updated control parameters in the subsequent slurry pH control process.

[0007] Preferably, in S1, the step of smoothing the pH value of the slurry includes: The pH value of the slurry was continuously collected according to the preset sampling cycle; Establish a sliding time window; The pH value of the slurry within the sliding time window is averaged, and the averaged result is used as the pH value of the smoothing slurry.

[0008] Preferably, in step S2, the steps of calculating the inlet acid load index based on the SO2 concentration at the inlet of the absorption tower and the inlet flue gas flow rate, and calculating the smoothed acid load change rate based on the inlet acid load index, include: The SO2 concentration at the inlet of the absorption tower is correlated with the flue gas flow rate at the inlet to obtain the inlet acid load index at the corresponding time. The acid load change rate is calculated based on the relationship between the changes in the inlet acid load index at adjacent times. The acid load change rate obtained from multiple consecutive sampling periods is smoothed to obtain a smoothed acid load change rate.

[0009] Preferably, in S3, the step of calculating the slurry pH response trend index based on the pH value of the smoothed slurry at continuous time intervals includes: Calculate the rate of change of pH value of smoothing slurry between adjacent time points; Obtain the rate of change of slurry pH value over multiple consecutive sampling periods; The trend of pH change in slurry is determined based on the rate of pH change in the slurry. A slurry pH response trend index is generated based on the change trend of the slurry pH value.

[0010] Preferably, in S4, the step of identifying the current operating status of the wet desulfurization system based on the combined relationship between the smooth acid load change rate and the slurry pH response trend index includes: The condition for an increase is defined as the smooth acid load change rate being greater than a preset increase threshold; the condition for a decrease is defined as the smooth acid load change rate being less than a preset decrease threshold; and the condition for a stability is defined as the smooth acid load change rate being within a preset stable range. When the smooth acid load change rate meets the increase condition and the slurry pH response trend index meets the stability condition, it is determined to be a non-responding state when the load increases; When the smooth acid load change rate meets the increase condition and the slurry pH response trend index meets the decrease condition, it is determined to be a load increase response state; When the smooth acid load change rate meets the fallback condition or the slurry pH response trend index meets the recovery condition, it is determined to be a load fallback recovery state; When the smooth acid load change rate meets the stability condition and the slurry pH response trend index meets the stability condition, it is determined to be in a stable operating state.

[0011] Preferably, in S5, the step of generating limestone slurry compensation amount based on the identified operating status and adjusting the limestone slurry supply flow rate according to the corresponding limestone slurry compensation amount includes: When the operating state is a load increase and no response state, the first limestone slurry compensation amount is generated according to the smooth acid load change rate; When the operating state is a load increase response state, a second limestone slurry compensation amount is generated based on the smooth acid load change rate and slurry pH response trend index. When the operating state is the load fall-off recovery state, a third limestone slurry compensation amount is generated according to the smooth acid load change rate, and the corresponding limestone slurry supply flow rate is reduced according to the smooth acid load change rate. When the operating state is a stable operating state, a fourth limestone slurry compensation amount is generated based on the deviation between the pH value of the smoothing slurry and the pH value of the target slurry. Adjust the limestone slurry supply flow rate according to the corresponding limestone slurry compensation amount.

[0012] Preferably, the step of generating the second limestone slurry compensation amount based on the smooth acid load change rate and slurry pH response trend index includes: The load compensation amount is generated based on the smoothed acid load change rate; The response compensation amount is generated based on the pH response trend index of the slurry. The load compensation amount and the response compensation amount are correlated and calculated; The second limestone slurry compensation amount is generated based on the correlation calculation results.

[0013] Preferably, in S6, the steps of performing density constraint correction on the adjusted limestone slurry supply flow rate based on the slurry density, and performing overflush suppression correction based on the smoothing slurry pH value and the smoothing acid load change rate include: Obtain the current slurry density and determine the positional relationship between the current slurry density and the preset density range; Generate the corresponding density constraint factor based on the positional relationship; The limestone slurry compensation amount is scaled according to the density constraint factor to obtain the density-corrected limestone slurry compensation amount. Determine the pH recovery trend of the smoothing slurry based on its pH value; The trend of declining inlet acid load can be determined by the smoothed acid load change rate; When the pH recovery trend of the slurry and the decline trend of the inlet acid load simultaneously meet the preset conditions, the corresponding limestone slurry compensation amount is reduced according to the density-corrected limestone slurry compensation amount, and finally the corrected limestone slurry supply flow rate is obtained.

[0014] Preferably, in step S7, the step of updating the control parameters based on the operating data recorded during this adjustment process includes: Record the lowest and highest slurry pH values ​​during the adjustment process; calculate the deviation between the lowest slurry pH value and the target slurry pH value, and generate the first parameter correction amount based on this deviation; Calculate the deviation between the highest slurry pH value and the preset upper limit slurry pH value, and generate a second parameter correction amount based on the deviation; The control parameter is increased by the first parameter correction amount, and the control parameter is decreased by the second parameter correction amount, thereby obtaining the updated control parameter.

[0015] Secondly, the present invention provides the following technical solution: an adaptive pH control system for the slurry of a wet desulfurization system in a thermal power plant, used to implement the adaptive pH control method for the slurry of a wet desulfurization system in a thermal power plant as described above, comprising: The data acquisition module is used to collect data on SO2 concentration at the inlet of the absorption tower, inlet flue gas flow rate, slurry pH value, slurry density, and limestone slurry supply flow rate. The data preprocessing module is connected to the data acquisition module and is used to smooth the pH value of the slurry to obtain a smoothed pH value of the slurry. The acid load analysis module is connected to the data acquisition module and the data preprocessing module. It is used to calculate the inlet acid load index based on the SO2 concentration and flue gas flow rate at the inlet of the absorption tower, and to calculate the smooth acid load change rate based on the inlet acid load index. The response trend analysis module is connected to the data preprocessing module and is used to calculate the pH response trend index of the slurry based on the smooth slurry pH value at continuous time intervals. The operation status identification module is connected to the acid load analysis module and the response trend analysis module respectively, and is used to identify the current operation status of the wet desulfurization system based on the combined relationship between the smooth acid load change rate and the slurry pH response trend index. The compensation control module is connected to the operation status identification module for generating limestone slurry compensation amount based on the identified operation status, and adjusting the limestone slurry supply flow rate based on the limestone slurry compensation amount. The constraint correction module is connected to the compensation control module, the data acquisition module and the data preprocessing module. It is used to perform density constraint correction on the adjusted limestone slurry supply flow rate according to the slurry density, and to perform overrush suppression correction according to the smoothing slurry pH value and the smoothing acid load change rate. The parameter update module is connected to the constraint correction module and is used to update the control parameters based on the operating data during this adjustment process. The updated control parameters are then fed back to the compensation control module for subsequent slurry pH control.

[0016] The present invention has the following beneficial effects: This invention provides an adaptive pH control method for slurry in a wet desulfurization system for thermal power plants. First, it collects key data such as sulfur dioxide concentration at the absorber inlet, flue gas flow rate, slurry pH, slurry density, and limestone slurry supply flow rate. The slurry pH is smoothed to avoid interference from instantaneous fluctuations in the measured data. The smoothed acid load change rate is calculated using relevant inlet flue gas parameters, and then combined with the smoothed slurry pH over a continuous period to obtain a slurry pH response trend index. The system's operating status is determined by the combination of these two indices. Unlike traditional methods that rely solely on slurry pH for feedback regulation, this invention proactively captures the changing trend of flue gas acid load and combines it with the actual slurry response for control. This compensates for the mass transfer and reaction delays between flue gas conditions and slurry reactions, solving the problem of traditional regulation methods lagging behind actual operating conditions. The system generates corresponding limestone slurry compensation amounts and adjusts the supply flow rate based on the identified different operating states. This overcomes the limitations of previous single-logic adjustments, employing differentiated regulation methods for different operating conditions such as load increases, decreases, and stability, making flow rate regulation more closely aligned with actual on-site operating conditions. After initial flow rate adjustment, the system incorporates slurry density constraints to correct the flow rate, preventing excessive slurry density caused by continuous limestone slurry injection and ensuring normal slurry circulation and reaction conditions. Simultaneously, it utilizes smoothed slurry pH and smoothed acid load change rates for overshoot suppression correction. As the load decreases and slurry pH gradually recovers, the supply is optimized in a timely manner, effectively preventing pH adjustment overshoot. After each adjustment, the system updates control parameters based on the operational data and applies the new parameters to subsequent control processes, enabling dynamic adjustment of control parameters according to operating conditions. This allows the entire control method to continuously adapt to complex on-site conditions and stably maintain the desulfurization system slurry pH within a reasonable range. Attached Figure Description

[0017] Figure 1 This is a flowchart of an adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant, as proposed in this invention. Figure 2 Here is a flowchart of an operation status identification process proposed in this invention; Figure 3 This invention provides a flowchart for generating limestone slurry compensation amount. Figure 4 This is a flowchart of a density constraint correction and overshoot suppression correction proposed in this invention; Figure 5 This is a flowchart of a control parameter update proposed in this invention; Figure 6 This is a diagram illustrating the architecture of an adaptive pH control system for slurry in a wet desulfurization system for thermal power plants, as proposed in this invention. Detailed Implementation

[0018] The technical solutions in 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.

[0019] Example 1 Reference Figure 1 In the first embodiment of the present invention, this embodiment provides an adaptive pH control method for the slurry of a wet desulfurization system in a thermal power plant, comprising the following steps: S1. Collect the SO2 concentration at the inlet of the absorption tower, the inlet flue gas flow rate, the pH value of the slurry, the slurry density, and the limestone slurry supply flow rate, and smooth the pH value of the slurry to obtain a smoothed slurry pH value. Specifically, in S1, the step of smoothing the pH value of the slurry includes: The pH value of the slurry was continuously collected according to the preset sampling cycle; Establish a sliding time window; The pH value of the slurry within the sliding time window is averaged, and the averaged result is used as the pH value of the smoothing slurry.

[0020] Specifically, during the operation of the wet desulfurization system, SO2 concentration data at the inlet of the absorption tower is acquired using an online SO2 analyzer located at the inlet flue gas duct. Inlet flue gas flow rate data is acquired using a flue gas flow rate detector. Slurry pH value data is acquired using an online pH detector located in the slurry circulation area of ​​the absorption tower. Slurry density data is acquired using a slurry density detector located in the slurry circulation pipeline or slurry storage area. Limestone slurry supply flow rate data is acquired using a flow rate detector on the limestone slurry supply pipeline. The control system synchronously collects the above data according to a unified sampling period and establishes data correlation relationships at corresponding times to ensure that all parameters correspond to the same operating time during subsequent calculations.

[0021] Due to local flow field changes, slurry disturbances, and instantaneous fluctuations in the detection element during slurry circulation, the continuously collected slurry pH value may exhibit short-term abnormal changes. Therefore, a smoothing process is performed on the slurry pH value. Let the current slurry pH value be... The sliding time window contains Each sampling point will determine the pH value of the smoothing slurry. It can be represented as: ; in, Indicates the pH value of the smoothing slurry; This indicates the pH value of the slurry at the current sampling time; This indicates the pH value of the slurry corresponding to the historical sampling time within the sliding time window; This indicates the number of sampling points included in the sliding time window.

[0022] After acquiring a new slurry pH value, the control system adds this data to a sliding time window, removes the earliest data within the window, and averages all slurry pH values ​​within the window to obtain the smoothed slurry pH value corresponding to the current moment. This smoothed slurry pH value serves as a data input parameter for subsequent calculations in acid load change rate analysis, slurry pH response trend analysis, and operational status identification.

[0023] The above methods enable the simultaneous acquisition of SO2 concentration at the inlet of the absorption tower, inlet flue gas flow rate, slurry pH value, slurry density, and limestone slurry supply flow rate. Smoothing processing reduces the impact of instantaneous fluctuations in slurry pH value on subsequent analysis processes, providing a unified data foundation for subsequent operation status identification and limestone slurry compensation generation.

[0024] S2. Calculate the inlet acid load index based on the SO2 concentration and flue gas flow rate at the inlet of the absorption tower, and calculate the acid load change rate based on the inlet acid load index at continuous time, and then calculate the smooth acid load change rate. Specifically, in S2, the steps for calculating the smoothed acid load change rate include: The SO2 concentration at the inlet of the absorption tower is correlated with the inlet flue gas flow rate to obtain the inlet acid load index at the corresponding time. The acid load change rate is calculated based on the relationship between the changes in the inlet acid load index at adjacent times. The acid load change rate obtained from multiple consecutive sampling periods is smoothed to obtain a smoothed acid load change rate.

[0025] Specifically, after obtaining the SO2 concentration and flue gas flow rate at the absorber inlet, a correlation analysis is performed on these two parameters to characterize the acidic component load level entering the absorber per unit time. Since the inlet SO2 concentration only reflects the SO2 content in the flue gas, while the inlet flue gas flow rate reflects the flue gas transport scale, the two are calculated together to obtain the inlet acidic load index. Let the inlet acidic load index be... The SO2 concentration at the inlet of the absorption tower is The inlet flue gas flow rate is The inlet acid load index can then be expressed as: ; in, Indicates the inlet acidity load index; This indicates the SO2 concentration at the inlet of the absorption tower; This represents the inlet flue gas flow rate. The control system continuously calculates the inlet acid load index at each time point according to the sampling period, and forms an acid load data sequence arranged in chronological order.

[0026] After obtaining the inlet acid load index at continuous time intervals, the acid load change rate is further calculated to characterize the direction and magnitude of change in the inlet flue gas conditions. Let the inlet acid load index at the current time be... The previous inlet acid load index was: The sampling time interval is The rate of change of acid load It can be represented as: ; in, Indicates the rate of change of acid load; This indicates the current inlet acid load index; This indicates the inlet acid load index at the previous moment; This indicates the sampling time interval. When the acid load change rate is greater than zero, it indicates that the inlet acid load is increasing; when the acid load change rate is less than zero, it indicates that the inlet acid load is decreasing; when the acid load change rate is close to zero, it indicates that the inlet acid load is in a relatively stable state.

[0027] Because boiler load fluctuations, flue gas flow disturbances, and sampling errors of the detection device may cause short-term fluctuations in the acid load change rate, the control system smooths the acid load change rate obtained from multiple consecutive sampling periods. During the smoothing process, a sliding analysis window for the acid load change rate is established, and the acid load change rate corresponding to multiple sampling periods within the window is averaged to obtain smoothed acid load change rate data for subsequent operating status identification.

[0028] The above method converts the inlet SO2 concentration and inlet flue gas flow rate into a unified inlet acid load index, and further obtains the acid load change rate (or smoothed acid load change rate) that reflects the changing trend of inlet operating conditions, providing a basis for subsequent slurry pH response trend analysis and operating status identification process.

[0029] Furthermore, S3, calculate the pH response trend index of the slurry based on the pH value of the smoothed slurry at continuous time intervals; Specifically, in S3, the steps for calculating the pH response trend index of the slurry include: Calculate the rate of change of pH value of smoothing slurry between adjacent time points; Obtain the rate of change of slurry pH value over multiple consecutive sampling periods; Determine the trend of pH change in slurry based on the rate of pH change in slurry; A slurry pH response trend index is generated based on the trend of slurry pH change.

[0030] Specifically, after obtaining the pH value of the smoothing slurry, the control system analyzes the pH value of the smoothing slurry at continuous intervals to determine the response of the slurry system to changes in the inlet acid load. Since the limestone slurry dissolution reaction, SO2 absorption reaction, and slurry circulation process all require a certain amount of time in the wet desulfurization process, changes in the slurry pH value can reflect the reaction state and alkalinity changes inside the absorber tower. The control system first calculates the rate of change of the smoothing slurry pH value between adjacent time points, assuming the current pH value of the smoothing slurry is... The pH value of the smoothing slurry at the previous moment was The sampling time interval is The rate of change of pH value in the slurry It can be represented as: ; in, Indicates the rate of change of the slurry pH value; This indicates the current pH value of the smoothing slurry; This indicates the pH value of the smoothing slurry at the previous moment; Indicates the sampling time interval.

[0031] The control system continuously acquires the rate of change of slurry pH value for multiple sampling periods in chronological order and establishes a sequence of slurry pH value change rates. When the rate of change of slurry pH value is consistently greater than zero for multiple consecutive sampling periods, the slurry pH value is determined to be on an upward trend; when the rate of change of slurry pH value is consistently less than zero for multiple consecutive sampling periods, the slurry pH value is determined to be on a downward trend; when the rate of change of slurry pH value varies within a preset fluctuation range for multiple consecutive sampling periods, the slurry pH value is determined to be on a stable trend. Subsequently, based on the comprehensive factors of the direction of change, the duration of change, and the rate of change within consecutive sampling periods, a slurry pH response trend index is generated to characterize the response state of the slurry system to changes in inlet acid load. The slurry pH response trend index can correspond to different response states such as upward response, downward response, recovery response, and stable response.

[0032] Since changes in slurry pH not only reflect the current slurry alkalinity level but also the slurry system's response to changes in inlet acid load, the slurry pH response trend index serves as an important input parameter for subsequent operational status identification, participating in operational status analysis along with the acid load change rate. Different combinations of relationships between the acid load change rate and the slurry pH response trend index indicate different operational stages of the wet desulfurization system.

[0033] The above method converts the continuously collected smooth slurry pH values ​​into a slurry pH response trend index that reflects the slurry response state. This allows the subsequent operation status identification process to consider not only changes in the inlet flue gas conditions but also the actual response of the slurry system, providing a response status basis for the subsequent generation of limestone slurry compensation.

[0034] Reference Figure 2 S4. Identify the current operating status of the wet desulfurization system based on the combined relationship between the smooth acid load change rate and the slurry pH response trend index. Specifically, in S4, the steps for identifying the current operating status of the wet desulfurization system include: The condition for an increase is defined as the smooth acid load change rate being greater than a preset increase threshold; the condition for a decrease is defined as the smooth acid load change rate being less than a preset decrease threshold; and the condition for a stability is defined as the smooth acid load change rate being within a preset stable range. When the rate of change of smooth acid load meets the increase condition and the pH response trend index of slurry meets the stability condition, it is determined to be a state of no response to load increase. When the rate of change of smooth acid load meets the condition for increase and the pH response trend index of slurry meets the condition for decrease, it is determined to be the load increase response state; When the smooth acid load change rate meets the fallback condition or the slurry pH response trend index meets the recovery condition, it is determined to be the load fallback recovery state; When the smooth acid load change rate meets the stability condition and the slurry pH response trend index meets the stability condition, it is determined to be in a stable operating state.

[0035] Specifically, after obtaining the smoothed acid load change rate and the slurry pH response trend index, the control system performs a joint analysis of the two to determine the current operating stage of the wet desulfurization system. Because there is a time lag between changes in inlet flue gas conditions and the slurry system response, neither the smoothed acid load change rate nor the slurry pH value alone can fully reflect the system's operating status. Therefore, a combination of the smoothed acid load change rate and the slurry pH response trend index is used for status identification. Let the acid load change rate be... The preset threshold for raising the value is The preset fallback threshold is Then when This is considered an upward condition; when The system determines the falling condition when the smooth acid load change rate is within the preset stable range; it determines the stable condition when the smooth acid load change rate is within the preset stable range. The control system determines the direction of change of the inlet acid load based on the smooth acid load change rate of multiple consecutive sampling periods, and at the same time, it determines whether the slurry system has responded by combining the slurry pH response trend index.

[0036] When the inlet acid load continues to increase while the slurry pH response trend remains stable, it indicates that the inlet flue gas load has changed, but the slurry system has not yet shown a significant response; this is identified as a load increase without response state. When the inlet acid load continues to increase and the slurry pH response trend shows a decreasing response, it indicates that the slurry system has been affected by the increased acid load and has begun to change; this is identified as a load increase response state. When the inlet acid load begins to decrease or the slurry pH response trend shows a recovery response, it indicates that the system is gradually entering the load recovery phase; this is identified as a load decline recovery state. When the inlet acid load is stable and the slurry pH response trend remains stable, it indicates that the current system operation is relatively stable; this is identified as a stable operation state. The above operation state identification results serve as the control basis for the subsequent limestone slurry compensation generation process, with different compensation strategies corresponding to different operation states.

[0037] By combining the acid load change rate, which reflects the changes in inlet flue gas, with the slurry pH response trend index, which reflects the response of the slurry system, the operating status of the wet desulfurization system can be identified, providing a basis for the subsequent limestone slurry compensation process.

[0038] Reference Figure 3 S5. Generate the first limestone slurry compensation amount, the second limestone slurry compensation amount, the third limestone slurry compensation amount, or the fourth limestone slurry compensation amount according to the identified operating status, and adjust the limestone slurry supply flow rate according to the corresponding limestone slurry compensation amount. Specifically, in S5, the steps of generating the first limestone slurry compensation amount, the second limestone slurry compensation amount, the third limestone slurry compensation amount, or the fourth limestone slurry compensation amount based on the identified operating status include: When the operating status is a load increase and no response, the first limestone slurry compensation amount is generated based on the smooth acid load change rate. When the operating state is the load increase response state, the second limestone slurry compensation amount is generated based on the smooth acid load change rate and slurry pH response trend index. When the operating state is the load fall-off recovery state, the third limestone slurry compensation amount is generated according to the smooth acid load change rate, and the corresponding limestone slurry supply flow rate is reduced according to the smooth acid load change rate. When the operating state is stable, the fourth limestone slurry compensation amount is generated based on the deviation between the pH value of the smoothing slurry and the pH value of the target slurry. Adjust the limestone slurry supply flow rate according to the corresponding limestone slurry compensation amount.

[0039] Preferably, the step of generating the second limestone slurry compensation amount based on the smooth acid load change rate and slurry pH response trend index includes: The load compensation amount is generated based on the smoothed acid load change rate; The response compensation amount is generated based on the pH response trend index of the slurry. Perform correlation calculations between load compensation and response compensation; The second limestone slurry compensation amount is generated based on the correlation calculation results.

[0040] Specifically, after identifying the operating status, the control system adopts corresponding limestone slurry compensation strategies based on different operating states. When the system is in a state of no response to increased load, it indicates that the inlet acid load has increased but the slurry system has not yet shown a significant response. To reduce the subsequent drop in slurry pH, a first limestone slurry compensation amount is generated based on the smoothing rate of change of acid load, and this compensation amount is added to the current limestone slurry supply flow rate. When the system is in a state of response to increased load, it indicates that the inlet acid load has increased and the slurry system has shown a response change. At this time, a second limestone slurry compensation amount is generated by simultaneously considering the degree of change in inlet operating conditions and the degree of slurry response. Let the load compensation amount be... The rate of change of acid load The load compensation coefficient is The load compensation amount can then be expressed as: ; in, Indicates the load compensation amount; Indicates the load compensation coefficient; This indicates the rate of change in acid load.

[0041] Simultaneously, a response compensation amount is generated based on the pH response trend index of the slurry. Let the response compensation amount be... The rate of change of the slurry pH value is The response compensation coefficient is The response compensation amount can then be expressed as: ; in, Indicates the amount of response compensation; Indicates the response compensation coefficient; This represents the rate of change of the slurry pH value. Subsequently, the load compensation and response compensation were correlated and calculated to obtain the second limestone slurry compensation amount. : ; in, This indicates the second limestone slurry compensation amount. By simultaneously considering changes in inlet acid load and the slurry system response, the compensation amount generation process reflects both operating condition changes and response status.

[0042] When the system is in a load recovery phase, a third limestone slurry compensation amount is generated based on the smoothed acid load change rate. The limestone slurry supply flow rate is then gradually reduced according to the decrease in the acid load change rate to avoid maintaining a high limestone slurry supply flow rate even after the inlet acid load has decreased. When the system is in a stable operating state, a fourth limestone slurry compensation amount is generated based on the deviation between the smoothed slurry pH value and the target slurry pH value. This fourth limestone slurry compensation amount is then used to fine-tune the limestone slurry supply flow rate, maintaining the slurry pH value within the target operating range.

[0043] After obtaining the limestone slurry compensation amount under the corresponding state, the control system combines the limestone slurry compensation amount with the current limestone slurry supply flow rate to calculate a new limestone slurry supply flow rate control value, and sends the control value to the limestone slurry supply device for adjustment.

[0044] By using the above method, corresponding limestone slurry compensation amounts are generated according to different operating conditions, so that the limestone slurry supply flow rate can be adjusted according to changes in inlet acid load and slurry response state, providing a compensation basis for subsequent density constraint correction and overrush suppression correction.

[0045] Reference Figure 4 Furthermore, S6, the adjusted limestone slurry supply flow rate is corrected by density constraint based on the slurry density, and overrush suppression is corrected based on the smoothing slurry pH value and the smoothing acid load change rate. Specifically, in S6, the step of overflush suppression correction based on the pH value of the smoothing slurry and the rate of change of the smoothing acid load includes: Obtain the current slurry density and determine the positional relationship between the current slurry density and the preset density range; Generate the corresponding density constraint factor based on the positional relationship; The limestone slurry compensation amount is scaled according to the density constraint factor to obtain the density-corrected limestone slurry compensation amount. Determine the pH recovery trend of the smoothing slurry based on its pH value; The trend of declining inlet acid load can be determined by the smoothed acid load change rate; When the pH recovery trend of the slurry and the decline trend of the inlet acid load simultaneously meet the preset conditions, the corresponding limestone slurry compensation amount is reduced according to the density-corrected limestone slurry compensation amount, and finally the corrected limestone slurry supply flow rate is obtained.

[0046] Specifically, after generating the limestone slurry compensation amount, the control system further corrects the limestone slurry supply flow rate based on the slurry density and current operating status. Since continuous limestone slurry compensation alters the solid-liquid ratio in the absorber slurry system, a continuous increase in slurry density may affect the slurry circulation and absorption reaction process. Therefore, density constraint correction is applied to the compensation amount before executing compensation control. The control system acquires the current slurry density and determines its positional relationship with a preset density range. Let the current slurry density be... The preset density upper limit is The preset lower limit of density is Then density constraint factor It can be represented as: ; in, Indicates the density constraint factor; Indicates the current slurry density; Indicates the preset upper limit of density; This represents the preset lower density limit. As the current slurry density gradually approaches the preset upper density limit, the density constraint factor decreases accordingly; when the current slurry density is at a lower position within the preset density range, the density constraint factor increases accordingly. The control system uses the density constraint factor to scale the current limestone slurry compensation amount to obtain the density-corrected compensation amount, thereby limiting the increase in limestone slurry supply flow rate as the slurry density continues to increase.

[0047] After density constraint correction, overshoot suppression correction is further performed. The control system determines the slurry pH recovery trend based on the pH changes of the smoothed slurry over multiple consecutive sampling periods, and simultaneously determines the inlet acid load decline trend based on the acid load change rate. When the smoothed slurry pH continuously rises over multiple consecutive sampling periods and the slurry pH change rate remains positive, the slurry pH recovery trend is determined to be valid; when the acid load change rate is continuously less than zero over multiple consecutive sampling periods, the inlet acid load decline trend is determined to be valid. When both the slurry pH recovery trend and the inlet acid load decline trend simultaneously meet preset conditions, it indicates that the inlet flue gas load has decreased and the slurry system has begun to recover. At this time, the control system reduces the current limestone slurry compensation amount according to the preset reduction ratio and recalculates the limestone slurry supply flow control value to reduce the continuous impact of subsequent compensation processes on the slurry pH.

[0048] After completing density constraint correction and overshoot suppression correction, the control system obtains the final limestone slurry supply flow control value and sends it to the limestone slurry supply device for adjustment. Through this method, while performing limestone slurry compensation control, constraint analysis is performed on slurry density changes and slurry recovery states, enabling the limestone slurry supply flow rate to be corrected according to the slurry system state, providing corrected operating data for subsequent control parameter updates.

[0049] Reference Figure 5 Furthermore, S7, update the control parameters based on the operating data recorded during this adjustment process, and use the updated control parameters in the subsequent slurry pH control process; Specifically, in step S7, the steps of updating the control parameters based on the operating data recorded during this adjustment process include: Record the lowest and highest slurry pH values ​​during the adjustment process; calculate the deviation between the lowest slurry pH value and the target slurry pH value, and generate the first parameter correction amount based on this deviation; Calculate the deviation between the highest slurry pH value and the preset upper limit slurry pH value, and generate a second parameter correction amount based on the deviation; The control parameter is increased by the correction amount of the first parameter, and decreased by the correction amount of the second parameter, thereby obtaining the updated control parameter.

[0050] Specifically, after completing the limestone slurry supply adjustment for the current control cycle, the control system statistically analyzes the operational data during this adjustment process and updates the control parameters using the statistical results. The control system records the lowest and highest slurry pH values ​​observed during this adjustment cycle. The lowest slurry pH value reflects the lowest alkalinity level of the slurry system when the compensation amount is insufficient, while the highest slurry pH value reflects the highest alkalinity level of the slurry system when the compensation amount is excessive. Let the target slurry pH value be Ps, and the lowest slurry pH value during the adjustment process be... Then the first parameter correction amount It can be represented as: ; in, Indicates the correction amount for the first parameter; Indicates the target slurry pH value; This indicates the lowest slurry pH value during the adjustment process. When the lowest slurry pH value is lower than the target slurry pH value, it indicates that the current compensation control capability is insufficient, and the control system incrementally corrects the corresponding control parameter based on the first parameter correction amount.

[0051] Meanwhile, the highest slurry pH value during the adjustment process is set to... The preset upper limit pH value of the slurry is Then the second parameter correction amount It can be represented as: ; in, This indicates the amount of correction for the second parameter; This indicates the highest pH value of the slurry during the adjustment process; This indicates the preset upper limit pH value of the slurry. When the highest slurry pH value exceeds the preset upper limit pH value, it indicates that the compensation amount in the current compensation control process is too large. The control system will then reduce the corresponding control parameter according to the correction amount of the second parameter.

[0052] The control system updates the load compensation coefficient, response compensation coefficient, and control parameters related to the limestone slurry compensation generation process based on the first and second parameter corrections, and saves the updated control parameters to the control system's operating parameters. At the start of the next control cycle, the compensation calculation process prioritizes the use of the updated control parameters, allowing subsequent limestone slurry compensation generation processes to be adjusted based on the results of the previous cycle.

[0053] By using the above method, the control parameters are dynamically updated based on the lowest and highest slurry pH values ​​recorded during actual operation. This allows the control parameters to be corrected as the operating conditions change, and the updated control parameters are used in subsequent slurry pH control processes, providing data for parameter adjustments between continuous control cycles.

[0054] Example 2 Reference Figure 6 In a second embodiment of the present invention, the present invention provides an adaptive control system for the slurry pH value of a wet desulfurization system in a thermal power plant, comprising: The data acquisition module is used to collect data on SO2 concentration at the inlet of the absorption tower, inlet flue gas flow rate, slurry pH value, slurry density, and limestone slurry supply flow rate. The data preprocessing module is connected to the data acquisition module and is used to smooth the pH value of the slurry to obtain a smoothed pH value. The acid load analysis module is connected to the data acquisition module and the data preprocessing module. It is used to calculate the inlet acid load index based on the SO2 concentration and flue gas flow rate at the inlet of the absorption tower, and to calculate the smooth acid load change rate based on the inlet acid load index. The response trend analysis module is connected to the data preprocessing module and is used to calculate the pH response trend index of the slurry based on the smooth slurry pH value at continuous time. The operating status identification module is connected to the acid load analysis module and the response trend analysis module respectively. It is used to identify the current operating status of the wet desulfurization system based on the combined relationship between the smooth acid load change rate and the slurry pH response trend index. The compensation control module is connected to the operation status identification module and is used to generate a first limestone slurry compensation amount, a second limestone slurry compensation amount, a third limestone slurry compensation amount, or a fourth limestone slurry compensation amount based on the identified operation status, and adjust the limestone slurry supply flow rate according to the limestone slurry compensation amount. The constraint correction module is connected to the compensation control module, the data acquisition module, and the data preprocessing module. It is used to perform density constraint correction on the adjusted limestone slurry supply flow rate based on the slurry density, and to perform overrush suppression correction based on the pH value of the smoothing slurry and the acid load change rate. The parameter update module is connected to the constraint correction module. It is used to update the control parameters based on the running data during this adjustment process and feed the updated control parameters back to the compensation control module for subsequent slurry pH control.

[0055] Specifically, the data acquisition module communicates with the on-site monitoring equipment to acquire in real-time inlet flue gas parameters, slurry operating parameters, and limestone slurry supply parameters during the operation of the wet desulfurization system, and sends the acquired data to the data preprocessing module. The data preprocessing module smooths the acquired slurry pH value and sends the processing result to the acid load analysis module and the response trend analysis module. The acid load analysis module calculates the inlet acid load index and acid load change rate based on the SO2 concentration at the absorber inlet and the inlet flue gas flow rate, and sends the analysis result to the operation status identification module; the response trend analysis module generates a slurry pH response trend index based on the smoothed slurry pH value and simultaneously sends it to the operation status identification module.

[0056] The operation status identification module receives the acid load change rate and slurry pH response trend indicators. Based on the combination of these two indicators, it identifies the current operation status of the wet desulfurization system and sends the identification result to the compensation control module. The compensation control module invokes the corresponding compensation strategy based on the identification result, generates the corresponding limestone slurry compensation amount, and calculates the adjusted limestone slurry supply flow rate. After obtaining the compensation control result, the constraint correction module performs density constraint correction based on slurry density information, and simultaneously performs overshoot suppression correction based on smoothing slurry pH value and acid load change rate, obtaining the final limestone slurry supply flow rate control value.

[0057] The parameter update module receives the operating data and control results output by the constraint correction module, analyzes the lowest and highest slurry pH values ​​and corresponding control processes during the current adjustment, and updates the control parameters used in the compensation control process. The updated control parameters are fed back to the compensation control module to participate in the compensation calculation for the next control cycle, thus forming a closed-loop control process of data acquisition, state analysis, compensation control, constraint correction, and parameter updating, achieving continuous adjustment of the slurry pH value in the wet desulfurization system.

[0058] In summary, the technical solution of the present invention has the following characteristics: 1. This invention identifies the current operating status of a wet desulfurization system by combining the acid load change rate and slurry pH response trend index, so that the changes in inlet flue gas conditions and slurry response status jointly participate in the control process, thereby reducing the control lag that exists when only the slurry pH value is used for feedback adjustment.

[0059] 2. This invention generates corresponding limestone slurry compensation amounts based on different operating conditions and adjusts the limestone slurry supply flow rate, so that different operating conditions correspond to different adjustment strategies, thereby reducing the inadequacy of a single compensation method.

[0060] 3. This invention corrects the limestone slurry supply flow rate by density constraint and over-flush suppression, so that the limestone slurry compensation amount can be adjusted according to the changes in slurry state, thereby reducing the situation of abnormal slurry density and slurry pH over-flush.

[0061] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for adaptive control of slurry pH value in a wet desulfurization system of a thermal power plant, characterized in that, Includes the following steps: S1. Collect the SO2 concentration at the inlet of the absorption tower, the inlet flue gas flow rate, the pH value of the slurry, the slurry density, and the limestone slurry supply flow rate, and smooth the pH value of the slurry to obtain a smoothed slurry pH value. S2. Calculate the inlet acid load index based on the SO2 concentration at the inlet of the absorption tower and the inlet flue gas flow rate, and calculate the smooth acid load change rate based on the inlet acid load index; S3. Calculate the pH response trend index of the slurry based on the pH value of the smooth slurry at continuous time points; S4. Identify the current operating status of the wet desulfurization system based on the combined relationship between the smooth acid load change rate and the slurry pH response trend index; S5. Generate limestone slurry compensation amount based on the identified operating status, and adjust the limestone slurry supply flow rate according to the limestone slurry compensation amount. S6. The adjusted limestone slurry supply flow rate is corrected by density constraint based on the slurry density, and overrush suppression correction is performed based on the smoothing slurry pH value and the smoothing acid load change rate. S7. Update the control parameters based on the operating data recorded during this adjustment process, and use the updated control parameters in the subsequent slurry pH control process.

2. The adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant according to claim 1, characterized in that, In S1, the step of smoothing the pH value of the slurry includes: The pH value of the slurry was continuously collected according to the preset sampling cycle; Establish a sliding time window; The pH value of the slurry within the sliding time window is averaged, and the averaged result is used as the pH value of the smoothing slurry.

3. The adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant according to claim 1, characterized in that, In S2, the steps of calculating the inlet acid load index based on the SO2 concentration at the inlet of the absorption tower and the inlet flue gas flow rate, and calculating the smoothed acid load change rate based on the inlet acid load index, include: The SO2 concentration at the inlet of the absorption tower is correlated with the flue gas flow rate at the inlet to obtain the inlet acid load index at the corresponding time. The acid load change rate is calculated based on the relationship between the changes in the inlet acid load index at adjacent times. The acid load change rate obtained from multiple consecutive sampling periods is smoothed to obtain a smoothed acid load change rate.

4. The adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant according to claim 1, characterized in that, In S3, the step of calculating the slurry pH response trend index based on the pH value of the smoothed slurry at consecutive time points includes: Calculate the rate of change of pH value of smoothing slurry between adjacent time points; Obtain the rate of change of slurry pH value over multiple consecutive sampling periods; The trend of pH change in slurry is determined based on the rate of pH change in the slurry. A slurry pH response trend index is generated based on the change trend of the slurry pH value.

5. The adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant according to claim 1, characterized in that, In S4, the step of identifying the current operating status of the wet desulfurization system based on the combined relationship between the smooth acid load change rate and the slurry pH response trend index includes: The condition for an increase is defined as the smooth acid load change rate being greater than a preset increase threshold; the condition for a decrease is defined as the smooth acid load change rate being less than a preset decrease threshold; and the condition for a stability is defined as the smooth acid load change rate being within a preset stable range. When the smooth acid load change rate meets the increase condition and the slurry pH response trend index meets the stability condition, it is determined to be a non-responding state when the load increases; When the smooth acid load change rate meets the increase condition and the slurry pH response trend index meets the decrease condition, it is determined to be a load increase response state; When the smooth acid load change rate meets the fallback condition or the slurry pH response trend index meets the recovery condition, it is determined to be a load fallback recovery state; When the smooth acid load change rate meets the stability condition and the slurry pH response trend index meets the stability condition, it is determined to be in a stable operating state.

6. The adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant according to claim 5, characterized in that, In S5, the step of generating limestone slurry compensation amount based on the identified operating status and adjusting the limestone slurry supply flow rate according to the corresponding limestone slurry compensation amount includes: When the operating state is a load increase and no response state, the first limestone slurry compensation amount is generated according to the smooth acid load change rate; When the operating state is a load increase response state, a second limestone slurry compensation amount is generated based on the smooth acid load change rate and slurry pH response trend index. When the operating state is the load fall-off recovery state, a third limestone slurry compensation amount is generated according to the smooth acid load change rate, and the corresponding limestone slurry supply flow rate is reduced according to the smooth acid load change rate. When the operating state is a stable operating state, a fourth limestone slurry compensation amount is generated based on the deviation between the pH value of the smoothing slurry and the pH value of the target slurry. Adjust the limestone slurry supply flow rate according to the corresponding limestone slurry compensation amount.

7. The adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant according to claim 6, characterized in that, The step of generating the second limestone slurry compensation amount based on the smooth acid load change rate and slurry pH response trend index includes: The load compensation amount is generated based on the smoothed acid load change rate; The response compensation amount is generated based on the pH response trend index of the slurry. The load compensation amount and the response compensation amount are correlated and calculated; The second limestone slurry compensation amount is generated based on the correlation calculation results.

8. The adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant according to claim 6, characterized in that, In S6, the steps of performing density constraint correction on the adjusted limestone slurry supply flow rate based on the slurry density, and performing overflush suppression correction based on the smoothing slurry pH value and the smoothing acid load change rate include: Obtain the current slurry density and determine the positional relationship between the current slurry density and the preset density range; Generate the corresponding density constraint factor based on the positional relationship; The limestone slurry compensation amount is scaled according to the density constraint factor to obtain the density-corrected limestone slurry compensation amount. Determine the pH recovery trend of the smoothing slurry based on its pH value; The trend of declining inlet acid load can be determined by the smoothed acid load change rate; When the pH recovery trend of the slurry and the decline trend of the inlet acid load simultaneously meet the preset conditions, the corresponding limestone slurry compensation amount is reduced according to the density-corrected limestone slurry compensation amount, and finally the corrected limestone slurry supply flow rate is obtained.

9. The adaptive pH control method for slurry in a wet desulfurization system of a thermal power plant according to claim 1, characterized in that, In step S7, the step of updating the control parameters based on the operating data recorded during this adjustment process includes: Record the lowest and highest slurry pH values ​​during the adjustment process; calculate the deviation between the lowest slurry pH value and the target slurry pH value, and generate the first parameter correction amount based on this deviation; Calculate the deviation between the highest slurry pH value and the preset upper limit slurry pH value, and generate a second parameter correction amount based on the deviation; The control parameter is increased by the first parameter correction amount, and the control parameter is decreased by the second parameter correction amount, thereby obtaining the updated control parameter.

10. An adaptive pH control system for slurry in a wet desulfurization system of a thermal power plant, characterized in that, A method for adaptively controlling the slurry pH value of a wet desulfurization system in a thermal power plant as described in any one of claims 1-9 includes: The data acquisition module is used to collect data on SO2 concentration at the inlet of the absorption tower, inlet flue gas flow rate, slurry pH value, slurry density, and limestone slurry supply flow rate. The data preprocessing module is connected to the data acquisition module and is used to smooth the pH value of the slurry to obtain a smoothed pH value of the slurry. The acid load analysis module is connected to the data acquisition module and the data preprocessing module. It is used to calculate the inlet acid load index based on the SO2 concentration and flue gas flow rate at the inlet of the absorption tower, and to calculate the smooth acid load change rate based on the inlet acid load index. The response trend analysis module is connected to the data preprocessing module and is used to calculate the pH response trend index of the slurry based on the smooth slurry pH value at continuous time intervals. The operation status identification module is connected to the acid load analysis module and the response trend analysis module respectively, and is used to identify the current operation status of the wet desulfurization system based on the combined relationship between the smooth acid load change rate and the slurry pH response trend index. The compensation control module is connected to the operation status identification module for generating limestone slurry compensation amount based on the identified operation status, and adjusting the limestone slurry supply flow rate based on the limestone slurry compensation amount. The constraint correction module is connected to the compensation control module, the data acquisition module and the data preprocessing module. It is used to perform density constraint correction on the adjusted limestone slurry supply flow rate according to the slurry density, and to perform overrush suppression correction according to the smoothing slurry pH value and the smoothing acid load change rate. The parameter update module is connected to the constraint correction module and is used to update the control parameters based on the operating data during this adjustment process. The updated control parameters are then fed back to the compensation control module for subsequent slurry pH control.

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