Intelligent desulfurization tower slurry pH accurate measurement and automatic slurry supplement control method and system

Abstract

The invention relates to an intelligent desulfurization tower slurry pH accurate measurement and automatic slurry supplement control method, which comprises the following steps: S1, selecting a sampling point, and guiding a slurry sample based on the sampling point; s2, carrying out redundancy measurement and self-cleaning on the pH value of the slurry based on an open flow cell; s3, establishing an automatic slurry supplementing decision based on feedforward-cascade-fuzzy composite control, and generating an inner loop flow set value based on the automatic slurry supplementing decision; and S4, performing automatic slurry supplementing operation based on the inner ring flow set value, and forming slurry circulation. The invention further discloses a corresponding system, electronic equipment and a computer readable storage medium.

Description

Technical Field

[0001] This invention relates to the fields of flue gas purification in coal-fired power plants, online monitoring of pH in desulfurization tower slurry, and automatic slurry replenishment technology. In particular, it relates to an intelligent method and system for accurate pH measurement and automatic slurry replenishment control of desulfurization tower slurry, specifically a method and system for accurate measurement of slurry pH value in wet flue gas desulfurization systems and automatic limestone slurry replenishment control based on the measurement. Background Technology

[0002] Wet limestone-gypsum flue gas desulfurization (FGD) technology is currently the most widely used desulfurization technology in coal-fired power plants. Its core principle is to use a slurry containing limestone (calcium carbonate) to wash the flue gas, where it reacts chemically with sulfur dioxide to produce calcium sulfite, which is ultimately oxidized to gypsum. During this process, the pH value of the slurry in the absorption tower is a key process parameter determining desulfurization efficiency, operational economy, and byproduct quality.

[0003] Maintaining a stable and suitable pH value is crucial. If the pH value is too low, it will lead to a decrease in desulfurization efficiency, excessive sulfur dioxide concentration at the outlet, and corrosion of the equipment. If the pH value is too high, it will easily cause excessive consumption of limestone, increase operating costs, and may lead to scaling and blockage of the system, affecting the safe and stable operation of the equipment.

[0004] Currently, desulfurization systems commonly employ online pH monitoring instruments and conventional PID control loops to monitor slurry pH and control limestone slurry replenishment. However, in actual industrial operation, this system faces numerous challenges, leading to problems such as inaccurate measurements, control lag, and low levels of automation.

[0005] 1. Poor accuracy, reliability, and durability of pH measurements:

[0006] (1) Electrode damage and contamination: Desulfurization slurry is a complex solid-liquid two-phase flow with high solid content, strong corrosiveness, and multiple components. Traditional immersion or pipe insertion pH electrode installation methods cause the electrode sensitive bulb to be directly subjected to the severe scouring of high-speed, high-pressure slurry and the impact and wear of solid particles, resulting in rapid aging and damage of the electrode. At the same time, substances such as calcium salts and gypsum in the slurry are prone to deposit and scale on the electrode membrane surface, contaminating the liquid interface and causing measurement signal drift, slow response, or even failure.

[0007] (2) Harsh measurement environment: Fluctuations in slurry pressure and flow rate can significantly affect the liquid junction potential of the pH electrode, introducing measurement noise and errors. Traditional closed or semi-closed measurement cells are prone to clogging, resulting in untimely slurry renewal and measurement values ​​that cannot represent the true operating conditions inside the tower.

[0008] (3) Lack of effective self-diagnosis and redundancy: Once a single-channel pH measurement system fails, the system will lose the key controlled variable, and the automatic control loop will be forced to shut down, requiring manual intervention by the operator, which increases the operational burden and the risk of instability. The existing system lacks intelligent judgment and life cycle management of the electrode's own health status (such as aging and degree of contamination).

[0009] 2. The automatic slurry replenishment control effect is not ideal:

[0010] (1) Complex characteristics of the object: The desulfurization reaction is a complex process with large inertia, large time delay and severe nonlinearity. The pH value of the slurry responds slowly to the flow rate of limestone slurry, and its dynamic characteristics vary significantly under different loads and different inlet SO2 concentrations. Conventional fixed-parameter PID controllers are difficult to maintain good control quality throughout the entire operating range and are prone to overshoot, oscillation or slow adjustment.

[0011] (2) Coarse feedforward compensation: Existing feedforward control usually only calculates the theoretical limestone demand based on the inlet SO2 concentration and flue gas volume, but does not consider the fluctuation of the quality of the limestone slurry itself (such as density, purity, solid content) and the time-varying characteristics of the chemical reaction environment in the absorption tower, resulting in inaccurate feedforward quantity, which still needs to rely on the feedback loop for significant correction.

[0012] (3) Weak anti-interference ability: When the unit load or the inlet SO2 concentration changes drastically, the conventional control strategy responds slowly, which can easily cause the outlet SO2 concentration to exceed the standard instantaneously or the limestone to be over-supplied.

[0013] (4) Limitations of actuators: The poor characteristics of the field grouting valve (such as large empty stroke and poor linearity) make it difficult to achieve precise flow control, and it often degenerates into simple on / off control or manual adjustment.

[0014] In summary, existing technologies cannot achieve long-term, stable, and accurate measurement of the pH value of desulfurization slurry, nor can they establish a matching, intelligent, accurate, and reliable automatic slurry replenishment control system adapted to complex operating conditions. This directly affects the commissioning rate, desulfurization efficiency, economic operation level, and stable compliance with environmental protection indicators of the desulfurization system. Summary of the Invention

[0015] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an intelligent method and system for precise pH measurement and automatic slurry replenishment control of desulfurization tower slurry. This method utilizes a single monitoring unit connected to dual desulfurization pH electrodes, employing an open flow cell combined with a redundant dual-electrode design, and automatic backwashing as an auxiliary function. While monitoring and comparing the pH data of the two desulfurization slurries, the monitoring unit uses artificial intelligence technology to intelligently judge the accuracy and reliability of the monitoring results, achieving precise pH measurement of the desulfurization tower slurry and providing closed-loop feedback for subsequent precise control of the slurry flow rate. Simultaneously, the monitoring unit achieves fault self-diagnosis and electrode lifecycle management based on historical monitoring data. Therefore, on the one hand, an intelligent measurement method and system capable of long-term, stable, and accurate measurement of pH value in desulfurization tower slurry is provided, solving the problems of electrode damage, contamination, and unreliable measurement. On the other hand, an automatic slurry replenishment control method and system matching the above-mentioned accurate measurement is provided, which can adapt to the nonlinear and large time-delay characteristics of the desulfurization process, realize rapid, accurate, and adaptive control of limestone slurry supply, and ensure desulfurization efficiency and operational economy. Thirdly, the above measurement and control functions are integrated to form a complete intelligent closed-loop control system with system self-diagnosis, electrode life cycle management, intelligent anti-interference, and operating condition adaptive capabilities, comprehensively improving the automation level and operational reliability of the desulfurization system.

[0016] This invention provides an intelligent method for precise pH measurement and automatic slurry replenishment control of desulfurization tower slurry, comprising:

[0017] S1, Select sampling points and guide slurry samples based on the sampling points;

[0018] S2, based on an open flow cell, performs redundant measurement and self-cleaning of slurry pH value;

[0019] S3, establish an automatic slurry replenishment decision based on feedforward-cascade-fuzzy composite control and generate an inner loop flow setpoint based on the automatic slurry replenishment decision;

[0020] S4 automatically replenishes slurry based on the inner loop flow rate setpoint and forms a slurry circulation.

[0021] Preferably, S1 includes:

[0022] S11. On one side of the desulfurization absorption tower, avoiding the high-pressure and high-speed area of ​​the gypsum discharge pump outlet header, two sampling points are selected at the upper and lower ends of the tower wall near the pump room.

[0023] S12, based on the two sampling points, the slurry in the tower is naturally diverted to the designated monitoring area in the pump room by gravity and position difference through two independent diversion pipes (11). The diversion pipes are respectively equipped with regulating valves (12) and shut-off valves (13), and instruments (14) are installed at the lower end. The instruments (14) are connected to the open flow pool (2) in the designated monitoring area. The regulating valves (12) are used to accurately control the flow rate of the slurry flowing out from each sampling point. The shut-off valves (13) are used as isolation valves to completely cut off the slurry source when the system needs maintenance, calibration or long-term shutdown, to ensure operational safety and facilitate the maintenance of the downstream instruments (14) and open flow pool (2). The instruments (14) are flow meters or pressure gauges used to monitor the working status of the guidance system in real time, thereby providing visual assurance for system operation.

[0024] Preferably, S2 includes:

[0025] S21, the slurry in the designated monitoring area is introduced into an open flow cell. The structure of the open flow cell is designed so that after the slurry flows in, it forms a stable and uniform laminar or slow flow at the electrode monitoring site and is quickly discharged from the outlet, thereby realizing the rapid replacement of the slurry.

[0026] S22, redundant monitoring based on dual electrodes, includes: two highly corrosion-resistant pH electrodes arranged in parallel in the open flow cell, which are connected to a monitoring host. The monitoring host is used to collect and compare the two pH signals generated by the two highly corrosion-resistant pH electrodes in real time.

[0027] S23, based on the artificial intelligence algorithm built into the monitoring instrument host, performs intelligent data fusion and fault diagnosis, including the following operations:

[0028] (1) Perform data validity judgment, including: real-time analysis of the stability, trend and difference of the two pH signals generated by the two highly corrosion resistant pH electrodes, and remove obviously abnormal jump data;

[0029] (2) Assess the state of the electrodes, including: analyzing the changes in the response speed and sensitivity of the electrode signals based on historical data, and determining whether the electrodes are at risk of aging, contamination or failure.

[0030] (3) Output measurement values, including: when both high corrosion resistant pH electrodes are normal, output the weighted average of the two pH signals or the fusion value based on confidence as the final pH measurement value; when one electrode fails, automatically switch to the data of the other normal electrode and issue a maintenance alarm.

[0031] (4) Perform electrode self-cleaning.

[0032] Preferably, the electrode self-cleaning includes two methods: natural rinsing and active rinsing. The slurry in the open flow pool (1) flows continuously and steadily, forming a gentle natural rinsing on the surface of the electrode bulb to prevent the deposition of solid particles. The active rinsing is performed on the sensitive element of the pH electrode by setting an industrial water self-rinsing module, according to a preset cycle or remote command, to remove the attached substances.

[0033] Preferably, S3 includes:

[0034] S31, using the precise pH value of the slurry as the core feedback variable, combined with flue gas parameters, the following control logic is executed to form the automatic slurry replenishment decision based on feedforward-cascade-fuzzy composite control;

[0035] S32, perform theoretical slurry supply calculation, slurry supply quality coefficient calculation and feedforward correction. Based on the fuzzy rule table of outlet sulfur dioxide concentration formulated according to decision variables, output fuzzy correction amount according to the net flue gas SO2 concentration and pH value. Combine the feedforward amount, the outer loop controller output amount and the fuzzy correction amount to generate the final inner loop flow setting value.

[0036] Preferably, the control logic includes:

[0037] (i) An outer-loop control logic characterized by pH value closed-loop includes: taking the deviation between the measured pH value and the set value of the absorber slurry as input, passing through the outer-loop PID controller, and outputting the initial set value of limestone slurry flow rate, wherein the gain of the PID controller is adaptively adjusted according to the unit load or SO2 concentration change, and the outer-loop control logic is implemented based on feedforward compensation calculation, including calculating the theoretical value of the required slurry supply and correcting the slurry supply quality online;

[0038] (ii) Output feedforward, including: the corrected slurry supply calculation value As a feedforward signal, inner-loop control characterized by flow closed-loop and fuzzy rule intervention are implemented: wherein: the inner-loop control characterized by flow closed-loop includes: mixing the initial setpoint of the flow output by the outer-loop controller with the feedforward quantity. The total limestone slurry flow rate setpoint is obtained by summing the values. The deviation between the total limestone slurry flow rate setpoint and the actual flow rate feedback value is used as the input of the inner loop PID controller. Its output drives the slurry adjustment valve or pump to complete the flow closed-loop control. The fuzzy rule intervention includes: using the sulfur dioxide concentration in the clean flue gas as the decision variable and the pH value of the slurry as the constraint variable to formulate fuzzy control rules.

[0039] Preferably, the theoretical value of the required slurry supply It is based on the real-time collected sulfur dioxide concentration in the raw flue gas. and the original flue gas volume flow rate Combined with the density ρ of limestone slurry and the molar mass of calcium carbonate The molar mass of sulfur dioxide Preset calcium-sulfur ratio Limestone purity Limestone slurry solids content It is obtained by calculating using the following formula (1):

[0040] (1);

[0041] In the formula: This represents the theoretical value of the required slurry supply, in m³ / h. This indicates the real-time sulfur dioxide concentration in the raw flue gas, expressed in mg / m³. ρ represents the volumetric flow rate of the raw flue gas, m³ / h; ρ represents the density of the limestone slurry, kg / m³. Indicates the molar mass of calcium carbonate; This indicates the molar mass of sulfur dioxide; This indicates the preset calcium-to-sulfur ratio, with a preferred value of 1.03, and an actual value between 1.05 and 1.08. This indicates the purity of the limestone, taken as 0.93. This indicates the solids content of the limestone slurry.

[0042] Preferably, the online correction of slurry quality includes:

[0043] (1) Calculate the slurry quality coefficient The slurry quality coefficient By statistically analyzing the cumulative value of actual grout supply over a period of time The cumulative theoretical grout supply during this period And the theoretical slurry supply corresponding to the pH change in the absorption tower during this period. Calculated; if the slurry quality is high, the calculated slurry supply quality coefficient is obtained. If the value is less than 1, the corrected grouting amount is less than the theoretically calculated value, thus avoiding over-grouting; if the grout quality is low, the calculated grouting quality coefficient will be less than 1. If the value is greater than 1, the corrected grouting volume is greater than the theoretically calculated value; the grouting quality coefficient The calculation formula (2) is shown below:

[0044] (2);

[0045] In the formula: Indicates the slurry quality coefficient; This represents the cumulative actual slurry supply over a period of time, expressed in tons (t). This represents the cumulative theoretical slurry supply over the specified period, expressed in tons (t). The theoretical slurry supply, expressed in tons, corresponds to the pH change within the absorber during that period; the slurry quality coefficient... Used to reflect the actual reaction efficiency of limestone slurry; when the slurry quality is high... <1, reduce the amount of slurry added; when the quality is low. >1. Increase the amount of slurry added;

[0046] (2) Based on the slurry quality coefficient Theoretical value of required slurry supply The corrected slurry supply volume is obtained by performing dynamic correction, and the formula for dynamic correction is shown in equation (3) below:

[0047] (3)

[0048] In the formula: This represents the corrected calculated slurry supply rate, in m³ / h.

[0049] Preferably, S4 includes:

[0050] S41, a control signal is generated based on the inner loop flow setpoint. The control signal drives the actuator in the grouting pipeline to accurately add the calculated limestone slurry into the absorption tower.

[0051] S42, the slurry discharged from the open flow tank, along with any flushing wastewater, is introduced into the sump and pumped back to the absorption tower by the sump pump, forming a slurry circulation.

[0052] A second aspect of the present invention is to provide an intelligent desulfurization tower slurry pH precision measurement and automatic slurry replenishment control system for implementing the method of the first aspect, comprising:

[0053] The slurry sampling and guiding subsystem includes: sampling points located at the upper and lower ends of the tower wall of the desulfurization absorption tower and two diversion pipes (11) connecting the sampling points and the designated monitoring area of ​​the pump room. The ends of the diversion pipes (11) are arranged vertically downward to ensure that the slurry flows smoothly into the open flow pool.

[0054] The pH precision measurement subsystem includes: an open flow cell (2), two highly corrosion-resistant pH electrodes (13), an intelligent monitoring unit, and a self-cleaning module; wherein, the open flow cell (2) is located at the end of the drainage pipe (11), and has an inlet, an outlet, and an electrode mounting port. The internal flow channel of the open flow cell (2) is optimized to ensure that the slurry flows smoothly through the electrodes and is quickly discharged, while also having the ability to withstand natural scouring and pressure fluctuations; the two highly corrosion-resistant pH electrodes (13) are made of highly corrosion-resistant materials and are installed in parallel in the open flow cell (2). The electrode structure is designed with fluid dynamics in mind to reduce flow interference. The main unit of the intelligent monitoring instrument is connected to the two highly corrosion-resistant pH electrodes (13) and includes a signal conditioning circuit, an A / D converter, a microprocessor, and a memory. The microprocessor is used to run a program that realizes dual-channel data acquisition, comparison, validity judgment, electrode status evaluation, data fusion, and final pH value output. The self-cleaning module includes a flushing water connector (33), a flushing pipeline (32), a solenoid valve, and a nozzle connected in sequence to an industrial water source for periodic or remotely triggered flushing of the electrodes.

[0055] An automatic slurry replenishment control subsystem includes a data acquisition unit, a controller, an actuator, and a human-machine interface. The data acquisition unit is used to acquire in real-time the raw flue gas SO2 concentration, raw flue gas flow rate, clean flue gas SO2 concentration, limestone slurry density, slurry pH measurement, and actual limestone slurry flow rate. The controller includes a feedforward calculation module, a cascade control module, a fuzzy control module, and a control quantity synthesis module. The feedforward calculation module is used to calculate the theoretical slurry supply volume, the slurry quality coefficient, and correct the feedforward quantity. The cascade control module includes an outer-loop pH controller and an inner-loop flow controller. The fuzzy control module stores a fuzzy rule table and outputs a fuzzy correction quantity based on the clean flue gas SO2 concentration and pH value. The control quantity synthesis module integrates the feedforward quantity, the outer-loop controller output, and the fuzzy correction quantity to generate the final inner-loop flow rate setpoint. The actuator receives controller commands and adjusts the valve opening or pump speed on the limestone slurry pipeline to control the slurry flow rate. The human-machine interface is used for parameter setting, status display, alarm prompts, and manual / automatic mode switching.

[0056] The slurry circulation subsystem includes a sump and a sump pump; wherein the sump is located below the flow pool and is used to collect outflowing slurry and flushing water, and the sump pump is used to pump the collected slurry back to the desulfurization absorption tower.

[0057] A third aspect of the present invention provides an electronic device including a processor and a memory connected to the processor, the memory storing a plurality of instructions which can be loaded by the processor, and a driver driving the actuator to enable the processor to perform the method as described in the second aspect.

[0058] A fourth aspect of the present invention provides a computer-readable storage medium storing a plurality of instructions, which can be read by a processor and executed as described in the second aspect.

[0059] The measuring device and method of the present invention have the following beneficial effects:

[0060] (1) High measurement accuracy, high reliability and long service life. The open flow cell avoids direct scouring of the electrodes, alleviates the influence of pressure / flow fluctuations on liquid junction potential, prevents blockage, and ensures the stability and representativeness of the measurement environment; Dual electrode redundancy and intelligent diagnosis: realizes hardware redundancy and software fault tolerance of the measurement link, and single point failure does not affect system operation; AI algorithm performs predictive maintenance of electrode status, transforming passive maintenance into active management, which greatly improves system availability and the reliability of measurement data; Combined self-cleaning adopts a combination of natural scouring and active flushing, which effectively inhibits electrode contamination and scaling, extends electrode service life, and reduces maintenance costs and instrument calibration frequency.

[0061] (2) Fast control response, high precision, and strong adaptability. A feedforward-cascade composite structure is adopted. The feedforward loop, based on an accurate physicochemical model and online quality correction, can quickly respond to major disturbances in the inlet flue gas. The cascade structure decouples the pH-dependent high-inertia loop and the flow-dependent high-speed loop, improving the system's response speed and stability. The integration of intelligent algorithms and fuzzy control endows the system with intelligent decision-making capabilities to cope with nonlinear and highly variable operating conditions, mimicking the experience of excellent operators and overcoming the limitations of conventional PID control. Adaptive PID is employed, with PID parameters adjusting according to changes in operating conditions (such as load), ensuring optimal control performance across the entire operating range.

[0062] (3) High system integration and high level of automation. The system deeply integrates precise measurement and intelligent control to form a complete intelligent closed loop from perception and decision-making to execution. It realizes full-process automation from sampling, measurement, decision-making, slurry replenishment to circulation, which significantly reduces the operation intensity of operators. The system has complete self-diagnosis and alarm functions, which improves the overall operation and management level of the desulfurization unit.

[0063] (4) Significant economic and environmental benefits. By precisely controlling the amount of limestone slurry added, excessive consumption is avoided, saving plant electricity and desulfurizing agent costs; stable and efficient desulfurization ensures that the SO2 concentration in the flue gas remains consistently within the standard, resulting in outstanding environmental benefits; and unplanned shutdowns and equipment maintenance costs caused by instrument failures and control malfunctions are reduced. Attached Figure Description

[0064] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0065] Figure 1 The flowchart illustrates a method for precise pH measurement and automatic slurry replenishment control of intelligent desulfurization tower slurry according to a preferred embodiment of the present invention.

[0066] Figure 2 The flowchart below shows step S1 of the intelligent desulfurization tower slurry pH precision measurement and automatic slurry replenishment control method according to a preferred embodiment of the present invention.

[0067] Figure 3(a) is a three-dimensional schematic diagram of the sampling point implementation according to a preferred embodiment of the present invention; Figure 3(b) is a schematic diagram of the principle of the sampling point implementation component according to a preferred embodiment of the present invention.

[0068] Figure 4 The flowchart below shows step S2 of the intelligent desulfurization tower slurry pH precision measurement and automatic slurry replenishment control method according to a preferred embodiment of the present invention.

[0069] Figure 5 This is a schematic diagram illustrating a dual-electrode redundancy monitoring implementation scheme according to a preferred embodiment of the present invention.

[0070] Figure 6 This is a schematic diagram illustrating the control logic principle of automatic slurry replenishment based on pH value and sulfur dioxide concentration in clean flue gas, according to a preferred embodiment of the present invention.

[0071] Figure 7 The flowchart below shows step S3 of the intelligent desulfurization tower slurry pH precision measurement and automatic slurry replenishment control method according to a preferred embodiment of the present invention.

[0072] Figure 8 The flowchart below shows step S4 of the intelligent desulfurization tower slurry pH precision measurement and automatic slurry replenishment control method according to a preferred embodiment of the present invention.

[0073] Figure 9 This is a schematic diagram of an open flow cell structure according to a preferred embodiment of the present invention;

[0074] Figure 10 This is a schematic diagram of an electronic device structure according to a preferred embodiment of the present invention. Detailed Implementation

[0075] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0076] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0077] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0078] like Figure 1 As shown, this embodiment provides an intelligent method for precise pH measurement and automatic slurry replenishment control of desulfurization tower slurry, including:

[0079] S1, Select sampling points and guide slurry samples based on the sampling points;

[0080] like Figure 2 As shown, in a preferred embodiment, S1 includes:

[0081] S11. On one side of the desulfurization absorption tower, avoiding the high-pressure and high-speed area of ​​the gypsum discharge pump outlet header, two sampling points are selected at the upper and lower ends of the tower wall near the pump room. The schematic diagrams of the sampling point locations are shown in Figure 3(a) and Figure 3(b).

[0082] S12, based on the two sampling points, the slurry in the tower is naturally diverted to the designated monitoring area in the pump room by gravity and position difference through two independent diversion pipes (11). The diversion pipes are respectively equipped with regulating valves (12) and shut-off valves (13), and instruments (14) are installed at the lower end. The instruments (14) are connected to the open flow pool (2) in the designated monitoring area. The regulating valves (12) are used to accurately control the flow rate of the slurry flowing out from each sampling point. The shut-off valves (13) are used as isolation valves to completely cut off the slurry source when the system needs maintenance, calibration or long-term shutdown, to ensure operational safety and facilitate the maintenance of the downstream instruments (14) and open flow pool (2). The instruments (14) are flow meters or pressure gauges used to monitor the working status of the guidance system in real time, thereby providing visual assurance for system operation.

[0083] In this embodiment, the design reduces the slurry flow rate and pressure, avoiding direct impact of the slurry on subsequent measuring equipment.

[0084] Traditional desulfurization slurry pH monitoring instruments typically have their electrodes installed at the outlet header of the gypsum discharge pump. The high-speed, high-pressure slurry conditions and the presence of solids in the slurry can cause irreversible damage to the electrodes. Furthermore, the desulfurization system itself is characterized by large delays, time-varying properties, and nonlinearity. Step S1 is the prerequisite and foundation of the entire intelligent measurement system. Its core objective is to obtain a representative slurry sample from the desulfurization absorption tower that is compatible with subsequent measurement equipment. Through research on representative sampling points for desulfurization slurry pH monitoring, two openings were selected at the upper and lower ends of the absorption tower near the pump house. Two pipes were used to divert the slurry from the desulfurization tower into the slurry pump house. The slurry pipes in the pump house were installed vertically downwards at their ends, with an open flow tank added at the end. Backwash demineralized water was also connected to the open flow tank. After rapid flushing and replacement in the open flow tank, the slurry was discharged into a sump, where it was circulated repeatedly using a sump pump. This step, through innovative sampling point selection and reliable guidance system design, fundamentally avoids the drawbacks of traditional methods, creating ideal conditions for subsequent accurate measurements.

[0085] S11: Optimize the selection of sampling points

[0086] This step abandons the traditional method of installing electrodes on the outlet header of the gypsum discharge pump. At this location, the slurry flow rate is extremely high, the pressure is high, and the fluid state is unstable. The severe hydraulic conditions will directly and continuously impact the sensitive components of the pH electrode (such as the glass bulb), causing mechanical wear and vibration failure of the electrode, and significantly shortening its service life due to the "water hammer effect".

[0087] To resolve this issue, see attached Figure 3(a) and 3(b) As shown, the present invention optimizes the sampling point location:

[0088] Location selection: On one side of the absorption tower, near the pump room, two sampling points are selected at the top and bottom of the tower wall. This vertical arrangement helps to obtain slurry samples from different layers inside the tower, improves the representativeness of the samples, and avoids measurement deviations caused by slurry stratification or uneven local concentration.

[0089] Environmental advantages: This location completely avoids the high-pressure, high-speed area of ​​the gypsum discharge pump outlet header, ensuring a relatively stable flow of the slurry. The sampling point is located on the tower wall, utilizing the slurry's own static pressure head as the flow driving force, thus achieving "natural drainage" of the slurry.

[0090] S12: Constructing a controllable slurry guiding system

[0091] The function of the guiding system is to safely and controllably transport the slurry flowing from the sampling point to the monitoring area in the pump house. The system consists of two independent pipelines and key valves and instruments, such as the drainage pipe (11), regulating valve (12), shut-off valve (13), and instrument (14) shown in the attached diagram.

[0092] Dual independent drainage: Two independent drainage pipes (11) are used, corresponding to the upper and lower sampling points respectively. This redundant design improves the reliability of a system. When one pipe needs to be repaired or flushed for any reason, the other pipe can still maintain the operation of the system, ensuring the continuity of monitoring.

[0093] Gravity flow and elevation difference utilization: Utilizing the natural elevation difference between the absorption tower and the pump room floor, the slurry flows naturally to the monitoring point under gravity. This design eliminates the need for additional power equipment such as delivery pumps, simplifying the system and reducing energy consumption. More importantly, it avoids the damage to the slurry properties caused by pumps (such as shearing, agitation, and bubble generation) and changes to the distribution of solids in the slurry.

[0094] Flow regulation and stabilization: A regulating valve (12) is installed on each drainage pipe. The regulating valve (12) is used to precisely control the flow rate of slurry flowing out from each sampling point. By regulating, the flow rate of slurry flowing into the subsequent open flow cell can be stabilized within a preset optimal range. This range must ensure that the slurry in the flow cell can be fully and quickly replaced to ensure the real-time measurement, while avoiding unnecessary impact on the flow cell and electrodes due to excessive flow velocity.

[0095] Safety isolation and convenient maintenance: The shut-off valve (13) installed on the pipeline acts as an isolation valve, which can completely cut off the slurry source when the system needs maintenance, calibration or long-term shutdown, ensuring operational safety and facilitating the maintenance of downstream instruments (14) and open flow pool (2).

[0096] Process monitoring: The instrument (14) installed at the lower end of the pipeline is selected as a flow meter or pressure gauge to monitor the working status of the guiding system in real time, such as confirming whether the slurry flows normally and whether the flow rate is within the set value, providing a visual guarantee for the operation of the system.

[0097] Finally, the slurry, after being regulated by this guidance system, smoothly enters the open flow pool (2) in the designated monitoring area, thus completing the key transition from "sampling under harsh working conditions" to "measurement in an ideal environment", laying a solid foundation for the long-term, stable and accurate operation of the entire pH intelligent monitoring system.

[0098] S2, based on an open flow cell, performs redundant measurement and self-cleaning of slurry pH value;

[0099] like Figure 4 As shown, in a preferred embodiment, S2 includes:

[0100] S21, the slurry in the designated monitoring area is introduced into an open flow cell. The structure of the open flow cell is designed so that after the slurry flows in, it forms a stable and uniform laminar or slow flow at the electrode monitoring site and is quickly discharged from the outlet, thereby realizing the rapid replacement of the slurry.

[0101] S22, based on dual-electrode redundancy monitoring, includes: two highly corrosion-resistant pH electrodes arranged in parallel within the open flow cell, both connected to a monitoring instrument host. The monitoring instrument host is used to collect and compare the two pH signals generated by the two highly corrosion-resistant pH electrodes in real time; the schematic diagram of the dual-electrode redundancy monitoring implementation scheme is shown below. Figure 5 As shown, the system includes two highly corrosion-resistant pH electrodes (13) disposed in the open flow cell (2). A dual-electrode redundancy implementation is adopted, with a single monitoring unit connected to both desulfurization pH electrodes. This implementation reduces the installation cost of the desulfurization pH monitoring system while achieving intelligent monitoring. It also ensures that even if one electrode fails during actual operation, the other electrode can continue to provide reliable monitoring data. This design enhances the stability and reliability of the system, especially in harsh industrial environments, minimizing errors and downtime caused by equipment failure. The electrode structure uses measuring electrodes made of highly corrosion-resistant materials, enabling long-term stable operation in the corrosive environment of the desulfurization slurry. The electrode design considers hydrodynamic characteristics to reduce interference with liquid flow.

[0102] S23, based on the artificial intelligence algorithm built into the monitoring instrument host, performs intelligent data fusion and fault diagnosis, including the following operations:

[0103] (1) To determine the validity of the data, including: to analyze in real time the stability, trend and difference of the two pH signals generated by the two highly corrosion resistant pH electrodes, and to remove obviously abnormal jump data.

[0104] (2) Evaluate the state of the electrodes, including: analyzing the changes in the response speed and sensitivity of the electrode signals based on historical data, determining whether the electrodes are at risk of aging, contamination or failure, and realizing full life cycle management of the electrodes.

[0105] (3) Output measurement values, including: when both high corrosion resistant pH electrodes are normal, output the weighted average of the two pH signals or the fusion value based on confidence as the final pH measurement value; when one electrode fails, automatically switch to the data of the other normal electrode and issue a maintenance alarm.

[0106] (4) Perform electrode self-cleaning:

[0107] (A) Natural scouring: The continuous and steady flow of slurry in the open flow tank forms a gentle scouring effect on the surface of the electrode bulb, preventing the deposition of solid particles.

[0108] (B) Active flushing: An industrial water self-flushing module is set up to perform timed or event-triggered precise flushing of the sensitive elements of the pH electrode according to a preset cycle or remote command to remove deposits.

[0109] The flow cell employs an open impact sampling method, allowing the slurry to quickly detach after reaching the flow cell and electrodes. This ensures real-time slurry replacement, provides self-cleaning for the electrode bulbs, and reduces calcium salt deposition and wear on the electrode sensitive membrane, thus extending electrode lifespan. The self-rinsing module of the desulfurization pH online monitoring system uses industrial water for periodic or remote-controlled precise rinsing of the monitoring system's electrode sensitive elements. This ensures the cleanliness of the electrode sensitive elements during long-term use, effectively guaranteeing the accuracy of the monitoring data.

[0110] like Figure 7 As shown, in S3, an automatic slurry replenishment decision is established based on feedforward-cascade-fuzzy composite control, and an inner loop flow setpoint is generated based on the automatic slurry replenishment decision.

[0111] In a preferred embodiment, S3 includes:

[0112] S31, using the precise pH value of the slurry as the core feedback variable, combined with flue gas parameters, the following control logic is executed to form the automatic slurry replenishment decision based on feedforward-cascade-fuzzy composite control, the control logic including:

[0113] (i) An outer-loop control logic characterized by a pH value closed loop includes: taking the deviation between the measured pH value and the set value of the absorber slurry as input, passing through an outer-loop PID controller (preferably an incremental three-segment nonlinear variable gain PID controller), and outputting a preliminary set value for the limestone slurry flow rate, wherein the gain of the PID controller is adaptively adjusted according to changes in unit load or SO2 concentration. The outer-loop control logic is implemented based on feedforward compensation calculation, including calculating the theoretical value of the required slurry supply and correcting the slurry supply quality online.

[0114] In this embodiment, the theoretical value of the required slurry supply It is based on the real-time collected sulfur dioxide concentration in the raw flue gas. and the original flue gas volume flow rate Combined with the density ρ of limestone slurry and the molar mass of calcium carbonate The molar mass of sulfur dioxide Preset calcium-sulfur ratio Limestone purity Limestone slurry solids content It is obtained by calculating using the following formula (1):

[0115] (1);

[0116] In the formula: This represents the theoretical value of the required slurry supply, in m³ / h. This indicates the real-time sulfur dioxide concentration in the raw flue gas, expressed in mg / m³. ρ represents the volumetric flow rate of the raw flue gas, m³ / h; ρ represents the density of the limestone slurry, kg / m³. Indicates the molar mass of calcium carbonate; This indicates the molar mass of sulfur dioxide; This indicates the preset calcium-to-sulfur ratio, with a preferred value of 1.03, and an actual value between 1.05 and 1.08. This indicates the purity of the limestone, taken as 0.93. This indicates the solids content of the limestone slurry.

[0117] In this embodiment, the online correction of slurry quality includes:

[0118] 1. Calculate the slurry quality coefficient Slurry quality coefficient By statistically analyzing the cumulative value of actual grout supply over a period of time The cumulative theoretical grout supply during this period And the theoretical slurry supply corresponding to the pH change in the absorption tower during this period. Calculated. To improve the correction effect of the slurry quality coefficient, the pH trend is monitored in real time during actual operation. When the pH value is in a steady state, the slurry quality coefficient is updated once.

[0119] In this embodiment, the theoretical value of the required slurry supply is mainly calculated based on the inlet sulfur dioxide concentration and the original flue gas volumetric flow rate. To improve the accuracy of the feedforward compensation, this invention uses a slurry quality coefficient to correct the theoretical calculation value online. The slurry quality coefficient is calculated online based on the slurry quality in the slurry tank. If the slurry quality is high, the calculated slurry quality coefficient will be higher. If the value is less than 1, the corrected grouting amount is less than the theoretically calculated value, thus avoiding over-grouting; if the grout quality is low, the calculated grouting quality coefficient will be less than 1. If the value is greater than 1, the corrected slurry replenishment amount is greater than the theoretically calculated value, thus avoiding problems such as excessive sulfur dioxide concentration in the flue gas due to insufficient slurry replenishment. The slurry supply quality coefficient... The calculation formula (2) is shown below:

[0120] (2);

[0121] In the formula: Indicates the slurry quality coefficient; This represents the cumulative actual slurry supply over a period of time, expressed in tons (t). This represents the cumulative theoretical slurry supply over the specified period, expressed in tons (t). This represents the theoretical slurry supply in tons (t) corresponding to the pH change within the absorption tower during that period.

[0122] The value reflects the actual reaction efficiency of the limestone slurry. When the slurry quality is high, <1, reduce the amount of slurry added; when the quality is low. >1. Increase the amount of slurry added. The value is updated only when the pH is at steady state to ensure the effectiveness of the correction.

[0123] 2. Based on the slurry quality coefficient Theoretical value of required slurry supply The corrected slurry supply volume is obtained by performing dynamic correction, and the formula for dynamic correction is shown in equation (3) below:

[0124] (3)

[0125] In the formula: This represents the corrected calculated slurry supply rate, in m³ / h.

[0126] (ii) Output feedforward, including: the corrected slurry supply calculation value As a feedforward signal, inner-loop control characterized by flow closed-loop and fuzzy rule intervention are implemented.

[0127] 1. Inner-loop control characterized by flow closed-loop includes: combining the initial flow setpoint output by the outer-loop controller with the feedforward quantity. The total limestone slurry flow rate setpoint is obtained by summing the values. The deviation between the total limestone slurry flow rate setpoint and the actual flow rate feedback value is used as the input of the inner loop PID controller, and its output drives the slurry replenishment regulating valve or pump to complete the flow closed-loop control.

[0128] 2. Fuzzy rule intervention includes: using the net flue gas sulfur dioxide concentration as the decision variable and the slurry pH value as the constraint variable to formulate fuzzy control rules. For example:

[0129] When the SO2 concentration in the clean flue gas is <12mg / Nm³, it is determined that the slurry supply is excessive, and a negative correction amount (such as -15%) is added to the original control output.

[0130] When the SO2 concentration in the clean flue gas is between 12 and 16 mg / Nm³, it is determined that the slurry supply is excessive, and a negative correction amount (such as -10%) is added to the original control output.

[0131] When the SO2 concentration in the clean flue gas is between 16 and 20 mg / Nm³, fine-tune it according to the pH deviation (e.g., ±2 × deviation).

[0132] When the SO2 concentration in the clean flue gas is 20-25 mg / Nm³, the slurry supply is deemed insufficient, and a positive correction amount (such as +10%) is added.

[0133] When the SO2 concentration in the clean flue gas is >25mg / Nm³, the slurry supply is deemed insufficient, and a positive correction amount (such as +15%) is added.

[0134] This fuzzy rule mimics the operational experience of skilled operators, enabling rapid coarse adjustment of the slurry supply when operating conditions change drastically, thus overcoming large disturbances.

[0135] S32, perform theoretical slurry supply calculation, slurry supply quality coefficient calculation and feedforward correction. Based on the fuzzy rule table of outlet sulfur dioxide concentration formulated according to decision variables, output fuzzy correction amount according to the net flue gas SO2 concentration and pH value. Combine the feedforward amount, the outer loop controller output amount and the fuzzy correction amount to generate the final inner loop flow setting value.

[0136] Implementation path of application examples

[0137] The overall technical approach of precision slurry replenishment and automatic support is based on the company's historical data on unit operation, conducting analysis of the desulfurization system's operating characteristics under different load conditions, establishing desulfurization efficiency models and desulfurization energy consumption models, and simultaneously developing a desulfurization slurry flow optimization control system to achieve the lowest energy consumption under environmental constraints.

[0138] (i) Taking the desulfurization system as the research object, we analyze the various factors affecting desulfurization efficiency from the perspective of desulfurization mechanism and process flow, including: the influence characteristics of flue gas side parameters, the influence characteristics of desulfurization side operating parameters, and the influence characteristics of desulfurization system design parameters; using data correlation analysis, we extract and synthesize the factors affecting desulfurization efficiency to obtain the set of input variables for the desulfurization efficiency model; using the unit SIS data, we establish desulfurization efficiency models under different circulating pump combination modes.

[0139] The optimized control strategy employs incremental three-segment nonlinear variable-gain PID control to overcome the effects of time delay and severe nonlinearity in the neutralization reaction on the system. The control loop uses a cascade control system, with the outer loop being a pH closed-loop control and the inner loop being a limestone slurry flow closed-loop control. The gain of the PID controller in the inner loop is adjusted according to the sulfur dioxide concentration, thus achieving better dynamic characteristics. Through variable pH control experiments under different operating conditions, a preliminary mathematical model relationship between pH and load is established. The pH setpoint is automatically adjusted based on the load and sulfur dioxide concentration. A feedforward loop is added to calculate the calcium-sulfur ratio. After function transformation, the amount of sulfur dioxide is converted into the limestone slurry flow setpoint. When the sulfur dioxide content changes, the slurry feed rate can be adjusted in advance, accelerating the adjustment of the slurry pH.

[0140] (II) Slurry Flow Control Strategy

[0141] The slurry replenishment valve for the first-phase desulfurization slurry is an on / off valve, while the slurry replenishment valve for the second-phase desulfurization slurry has both on / off and regulating valves. The idle stroke of the regulating valve on site is greater than 50%, and simply replacing the actuator is not enough to solve the problem of automatic slurry replenishment on site. The actuators on site for the second-phase desulfurization currently exist, but the valve characteristics cannot meet the PID automatic control requirements of the plan. At present, an interlocking switch method is used to reduce the frequent valve operation and regulation actions of operators to achieve automatic slurry replenishment.

[0142] This embodiment uses pH value and sulfur dioxide concentration in the clean flue gas as targets for automatic control of slurry replenishment. The control diagram is shown below. Figure 6 As shown.

[0143] The feedforward-cascade control system does not directly introduce the feedforward signal into the control system. Instead, it introduces the feedforward signal as an input variable into the feedforward controller. The feedforward controller can calculate the theoretical slurry supply required at this time based on the input variable, and calculate the slurry quality coefficient online based on the slurry quality in the slurry tank. This corrects the theoretical slurry supply to obtain the calculated slurry supply value, which is then used as the feedforward signal for the entire control system, thus improving the accuracy of feedforward compensation. Fuzzy control is introduced into the control system to fit historical operating data and formulate fuzzy rules. These fuzzy rules can mimic the control process of operators under special operating conditions, ensuring that the new slurry supply control strategy remains in automatic operation even when the unit's operating conditions change significantly, controlling the sulfur dioxide concentration in the flue gas and the pH value of the slurry within the normal range.

[0144] Introducing fuzzy control into the control system can mimic the operator's actions of adding or reducing slurry, quickly overcoming disturbances such as sudden increases or decreases in unit load or flue gas sulfur dioxide concentration. The formulation of fuzzy rules is the core of fuzzy control. Using the net flue gas sulfur dioxide concentration as the decision variable and the slurry pH value as the constraint variable, fuzzy rules are formulated based on the operator's techniques.

[0145] The fuzzy rule table for export sulfur dioxide concentration based on decision variables is shown in Table 1:

[0146] Table 1

[0147] Export SO2 concentration range (mg / Nm³) Fuzzy control instructions for slurry supply <12 -15 12-16 -10 16-20 ±2× Deviation 20-25 +10 >25 +15

[0148] The table above divides the outlet sulfur dioxide concentration into five segments: 16-20 mg / Nm³ is the middle segment; when the outlet sulfur dioxide fluctuates within this range, the slurry volume should be increased or decreased by twice the deviation. Less than 16 mg / Nm³ and greater than 20 mg / Nm³ are the smaller and larger segments, respectively; less than 12 mg / Nm³ and greater than 25 mg / Nm³ are the positive small and positive large segments, respectively. The corresponding slurry supply volume will vary depending on the commissioning situation.

[0149] S4, based on the inner loop flow rate set value, performs automatic slurry replenishment and forms slurry circulation;

[0150] like Figure 8 As shown, in a preferred embodiment, S4 includes:

[0151] S41, a control signal is generated based on the inner loop flow setpoint. The control signal drives the actuator (regulating valve or pump) in the slurry replenishment pipeline to accurately add the calculated limestone slurry into the absorption tower.

[0152] S42, the slurry discharged from the open flow pool, along with any possible flushing wastewater, is introduced into the sump and pumped back to the absorption tower by the sump pump, forming a slurry circulation without any external discharge or waste.

[0153] This embodiment also provides an intelligent desulfurization tower slurry pH precision measurement and automatic slurry replenishment control system for implementing the above method, including:

[0154] The slurry sampling and guiding subsystem includes: sampling points located at the upper and lower ends of the tower wall of the desulfurization absorption tower and two diversion pipes (11) connecting the sampling points and the designated monitoring area of ​​the pump room. The ends of the diversion pipes (11) are arranged vertically downward to ensure that the slurry flows smoothly into the open flow pool.

[0155] The pH precision measurement subsystem includes: an open flow cell (2), two highly corrosion-resistant pH electrodes (13), an intelligent monitoring unit, and a self-cleaning module; wherein, the open flow cell (2) is located at the end of the drainage pipe (11), and has an inlet, an outlet, and an electrode mounting port. The internal flow channel of the open flow cell (2) is optimized to ensure that the slurry flows smoothly through the electrode and is quickly discharged, and has both natural flushing and pressure fluctuation resistance capabilities; the two highly corrosion-resistant pH electrodes (13) are made of highly corrosion-resistant materials and are installed in parallel in the open flow cell (2). The electrode structure takes into account fluid dynamics to reduce flow interference; the intelligent monitoring unit is connected to the two highly corrosion-resistant pH electrodes (13) and includes a signal conditioning circuit, an A / D converter, a microprocessor, and a memory. The microprocessor is used to run a program to realize dual-channel data acquisition, comparison, validity judgment, electrode status evaluation, data fusion, and final pH value output; the self-cleaning module: as Figure 5 As shown, it includes a flushing water connector (33), a flushing pipeline (32), a solenoid valve, and a nozzle (not shown) connected in sequence to an industrial water source, for periodic or remotely triggered flushing of the electrodes;

[0156] The automatic slurry replenishment control subsystem includes a data acquisition unit, a controller, an actuator, and a human-machine interface. The data acquisition unit is used to acquire in real-time the raw flue gas SO2 concentration, raw flue gas flow rate, net flue gas SO2 concentration, limestone slurry density, slurry pH measurement, and actual limestone slurry flow rate. The controller includes a feedforward calculation module, a cascade control module, a fuzzy control module, and a control quantity synthesis module. The feedforward calculation module is used to calculate the theoretical slurry supply volume, the slurry quality coefficient, and correct the feedforward quantity. The cascade control module includes an outer-loop pH controller and an inner-loop flow controller. The fuzzy control module stores a fuzzy rule table and outputs a fuzzy correction quantity based on the net flue gas SO2 concentration and pH value. The control quantity synthesis module integrates the feedforward quantity, the outer-loop controller output, and the fuzzy correction quantity to generate the final inner-loop flow rate setpoint. The actuator receives controller commands and adjusts the valve opening or pump speed on the limestone slurry pipeline to control the slurry flow rate. The human-machine interface is used for parameter setting, status display, alarm prompts, and manual / automatic mode switching.

[0157] The slurry circulation subsystem includes a sump and a sump pump; wherein the sump is located below the flow pool and is used to collect outflowing slurry and flushing water, and the sump pump is used to pump the collected slurry back to the desulfurization absorption tower. Specific implementation examples:

[0159] Example 1: System Hardware Configuration and Installation

[0160] The system hardware in this embodiment mainly includes a slurry sampling and guidance section, a pH measurement section, an automatic slurry replenishment control section, and a slurry circulation section.

[0161] Slurry sampling and guidance: As shown in Figure 3(a), sampling holes are opened above and below the liquid level on the side wall of the desulfurization absorption tower near the pump room, and two DN50 UPVC drainage pipes are connected to them. The pipes are inclined towards the pump room at a certain slope, and the ends are vertically downward, pointing to the inlet of the open flow pool (2).

[0162] Accurate pH measurement: such as Figure 9As shown, the open flow-through tank (2) is made of 316L stainless steel and includes a tank body (201) with a slurry inlet (202), a slurry outlet (203), a first electrode mounting port (204a), a second electrode mounting port (204b), and a rinsing water inlet (205). The internal flow channels of the tank body have a smooth transition and the cross-section gradually increases to reduce the flow velocity. Two industrial online pH electrodes (31) are inserted through the first electrode mounting port (204a) and the second electrode mounting port (204b), with their sensitive bulbs located in the stable flow field region at the center of the flow-through tank. The main unit of the intelligent monitoring instrument is connected to the two industrial online pH electrodes (31) via a waterproof cable. The self-cleaning module includes a demineralized water pump, a solenoid valve, and a fine nozzle pointing towards the electrode bulbs.

[0163] Automatic slurry replenishment control: The controller is implemented using a custom function block in a high-performance PLC or DCS. It obtains signals such as SO2 concentration, flue gas flow rate, and slurry density from the plant-level monitoring information system (SIS) or distributed control system (DCS) via a communication network, obtains the pH value from the intelligent monitoring instrument host, and obtains the actual flow rate of limestone slurry from the flow meter (14). The output signal of the controller is sent to the actuator of the regulating valve (12) on the slurry replenishment pipeline.

[0164] Slurry circulation: The slurry flowing out of the outlet of the open flow pool (2) falls into the pit below. The pit pump starts and stops automatically according to the liquid level, returning the slurry to the absorption tower.

[0165] Example 2: pH Measurement Procedure and Intelligent Diagnosis

[0166] The microprocessor inside the intelligent monitoring instrument's main unit executes the following process:

[0167] 1. The pHA signal of electrode (6a) and the pHB signal of electrode (6b) were acquired simultaneously.

[0168] 2. Signal preprocessing: Perform digital filtering (such as moving average filtering) on ​​the original signal to suppress noise.

[0169] 3. Data validity assessment:

[0170] (1) Determine whether |pHA-pHB| is less than the set threshold (e.g., 0.2pH). If it is much greater than the threshold, one of the electrodes may be faulty.

[0171] (2) Determine whether the rate of change of a single signal is within a reasonable range and eliminate instantaneous spike interference.

[0172] 4. Electrode condition assessment:

[0173] (1) Record the historical response data of each electrode (such as the slope when calibrated in standard buffer).

[0174] (2) Calculate the variance of the recent signal. If the variance continues to decrease, it may indicate a slower electrode response and increased contamination.

[0175] (3) Establish an electrode "health" indicator. When the indicator is below a certain threshold, a "maintenance warning" is prompted.

[0176] 5. Measurement value fusion and output:

[0177] (1) If both electrodes are judged to be normal, the final output value = (WA × pHA + WB × pHB) / (WA + WB), where the weights WA and WB can be dynamically allocated according to the stability of the recent signal.

[0178] (2) If electrode A is judged to be faulty, output pH_B and display "Electrode A failure, please check" on the human-machine interface.

[0179] (3) Self-cleaning control: Start the solenoid valve (9) to flush for 60 seconds every 8 hours or when the electrode health deteriorates rapidly.

[0180] Example 3: Implementation of the automatic slurry replenishment control algorithm

[0181] The controller performs the following calculations within each control cycle (e.g., 1 second):

[0182] 1. Feedforward calculation:

[0183] Calculate in real time according to formula (1) . Where, Take 1.06, Take 0.93, L and ρ come from the real-time measurement values of the densitometer. Every 30 minutes (or when the pH value fluctuates within ±0.05 for more than 10 minutes, it is judged as a steady state), update the slurry supply quality coefficient according to formula (2) . And Obtained by integrating the actual flow rate and the theoretical flow rate in the past 30 minutes, Obtained by querying the "pH change - slurry consumption" experience table. Calculate the accurate feedforward quantity according to formula (3) .

[0184] 2. Cascade control:

[0185] (1) Outer loop: Calculate the pH deviation epH(t) = pHsetpoint - pHmeasured. The outer loop PID controller uses an incremental algorithm, and its proportional gain Kp is set in segments according to the unit load L: when L < 50%, Kp = K1; when 50% ≤ L < 80%, Kp = K2; when L ≥ 80%, Kp = K3 (K1 < K2 < K3). The controller output is the preliminary flow rate setting value Fouter(t).

[0186] (2) Inner loop setpoint synthesis: Total flow setpoint Fset(t) = Fouter(t) + +Ffuzzy(t). Where Ffuzzy(t) is the fuzzy correction factor.

[0187] (3) Inner loop: Calculate the flow deviation eflow(t)=Fset(t)-Factual(t). The inner loop PID controller outputs the control signal u(t) to drive the regulating valve (12).

[0188] 3. Fuzzy rule intervention:

[0189] (1) Real-time reading of the SO2 concentration Cout in the clean flue gas.

[0190] (2) Look up the fuzzy rule table shown in Table 1 (stored in the controller):

[0191] If Cout = 18 mg / Nm³, falling within the “16-20” range, then Ffuzzy(t) = ±2×epH(t) (unit: m³ / h, requires standardization).

[0192] If Cout = 26 mg / Nm³, falling within the ">25" interval, then Ffuzzy(t) = +15% × Fset(t) (a fixed positive bias).

[0193] If Cout = 10 mg / Nm³, falling within the "<12" interval, then Ffuzzy(t) = -15% × Fset(t) (a fixed negative bias).

[0194] Through the coordinated operation of the aforementioned hardware and software, this embodiment achieves a leap from "inaccurate measurement and poor control" to "accurate measurement and precise control" of the desulfurization slurry pH, providing strong technical support for the efficient, economical, and stable operation of the desulfurization system.

[0195] The present invention also provides a memory that stores multiple instructions for implementing the method as described in Embodiment 1.

[0196] like Figure 10 As shown, the present invention also provides an electronic device, including a processor 302 and a memory 301 and a driver 303 connected to the processor 302. The memory 301 stores a plurality of instructions, which can be loaded by the processor. The driver 303 drives an actuator so that the processor can execute the method as described in the above embodiments.

[0197] Through the above description of the embodiments, those skilled in the art can clearly understand that the above embodiments can be implemented by software, or by using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions of the above embodiments can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, mobile hard drive, etc.), including several instructions to cause a computer device (such as a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0198] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for intelligent desulfurization tower slurry pH precise measurement and automatic slurry supplement control, characterized in that, Comprise: S1, select sampling points, and guide slurry samples based on the sampling points; S2, redundant measurement and self-cleaning of slurry pH value based on an open flow cell; S3, establishing an automatic slurry supplement decision based on feedforward-series-fuzzy complex control and generating an inner loop flow setting value based on the automatic slurry supplement decision; S4, automatic slurry supplement operation based on the inner loop flow setting value and forming slurry circulation.

2. The method according to claim 1, characterized in that, The S1 comprises: S11, on the side of the desulfurization absorption tower, avoiding the high-pressure high-speed area of the gypsum discharge pump outlet main pipe, two sampling points are selected on the upper and lower ends of the tower wall near the pump house; S12, based on the two sampling points, the tower slurry is naturally drained to the designated monitoring area in the pump house through two independent drainage pipes (11) by gravity and pressure difference, wherein the drainage pipes are respectively provided with regulating valves (12) and stop valves (13), and the lower end is provided with an instrument (14), the instrument (14) is communicated with the open flow cell (2) in the designated monitoring area, wherein the regulating valve (12) is used to accurately control the flow of slurry flowing out from each sampling point, the stop valve (13) is used as an isolation valve, which is used to completely cut off the slurry source when the system needs to be maintained, calibrated or long-term shutdown, to ensure the safety of operation, facilitate the maintenance of the downstream instrument (14) and open flow cell (2), and the instrument (14) is a flowmeter or a pressure gauge, which is used to monitor the working state of the guiding system in real time, thereby providing visual protection for system operation.

3. The method according to claim 2, wherein the method is characterized in that, The S2 comprises: S21, the slurry in the designated monitoring area is introduced into the open flow cell, and the structural design of the open flow cell makes the slurry form a smooth and uniform laminar flow or slow flow at the electrode monitoring site after flowing in, and is quickly discharged from the outlet, realizing rapid replacement of the slurry; S22, redundant monitoring based on double electrodes, comprising: arranging two high-corrosion-resistant pH electrodes in parallel in the open flow cell, and connecting them to a monitoring instrument host, the monitoring instrument host is used to collect and compare two pH signals generated by the two high-corrosion-resistant pH electrodes in real time; S23, intelligent data fusion and fault diagnosis based on the artificial intelligence algorithm built in the monitoring instrument host, including the following operations: (1) data validity judgment, including: real-time analysis of the stability, change trend and difference of the two pH signals generated by the two high-corrosion-resistant pH electrodes, and eliminating obviously abnormal jump data; (2) electrode state evaluation, including: analyzing the response speed and sensitivity change of the electrode signal based on historical data, and judging whether the electrode has aging, pollution or failure risk; (3) output measurement value, including: when both of the two high-corrosion-resistant pH electrodes are normal, output the weighted average value or the fusion value based on the confidence of the two pH signals as the final pH measurement value; when one electrode fails, automatically switch to the data of the other normal electrode, and issue a maintenance alarm; (4) electrode self-cleaning.

4. The method according to claim 3, wherein the method is characterized in that, The electrode self-cleaning includes both natural flushing and active flushing. The continuous and smooth flow of the slurry in the open flow tank (1) forms a natural flushing on the surface of the electrode ball, preventing the deposition of solid particles, and the active flushing of the sensitive element of the pH electrode is triggered by the industrial water self-flushing module according to the preset period or remote instruction, which can accurately remove the attachments.

5. The method according to claim 4, wherein the method is characterized in that, The S3 includes: S31, taking the accurate slurry pH value as the core feedback variable, combining the flue gas parameters, and executing the following control logic to form the automatic slurry supplementing decision based on the feedforward-series-fuzzy compound control; S32, performing theoretical slurry supply amount calculation, slurry quality coefficient calculation and feedforward amount correction, based on the outlet sulfur dioxide concentration fuzzy rule table formulated according to the decision variable, outputting the fuzzy correction amount according to the net flue gas SO2 concentration and pH value, and combining the feedforward amount, the outer loop controller output amount and the fuzzy correction amount to generate the final inner loop flow set value.

6. The method according to claim 5, wherein the method is characterized in that, The control logic includes: (1) The outer loop control logic characterized by pH value closed loop, including: taking the deviation of the measured value and the set value of the absorption tower slurry pH as the input, passing through the outer loop PID controller, and outputting the preliminary set value of the limestone slurry flow, wherein the gain of the PID controller is adaptively adjusted according to the unit load or SO2 concentration change, and the outer loop control logic is realized based on the feedforward compensation calculation, including calculating the theoretical value of the required slurry supply amount and online correcting the slurry quality; (ii) outputting the feedforward amount, comprising: calculating a modified slurry supply amount As a feedforward signal, an inner loop control characterized by flow closed loop and fuzzy rule intervention are implemented: wherein: the inner loop control characterized by flow closed loop comprises: adding the flow preliminary set value output by the outer loop controller and the feedforward amount to obtain a total limestone slurry flow set value, taking the deviation between the total limestone slurry flow set value and the actual flow feedback value as the input of the inner loop PID controller, and the output thereof drives the slurry adjustment valve or pump to complete the flow closed loop control; the fuzzy rule intervention comprises: taking the net flue gas sulfur dioxide concentration as the decision variable and the slurry pH value as the constraint variable to formulate the fuzzy control rule.

7. The method according to claim 6, wherein the method is characterized in that, The required theoretical value of slurry supply quantity is based on the real-time collected flue gas sulfur dioxide concentration and the original flue gas volume flow , combined with the limestone slurry density ρ, the molar mass of calcium carbonate , the mass of sulfur dioxide moles , the preset calcium sulfur ratio , the limestone purity , the solid content of limestone slurry , and is obtained by the following formula (1): （1）； In the formula: represents the theoretical value of the required slurry amount, m3 / h; represents the real-time collected original flue gas sulfur dioxide concentration, mg / m3; represents the original flue gas volume flow, m3 / h; p represents the limestone slurry density, kg / m3; represents the molar mass of calcium carbonate; represents the molar mass of sulfur dioxide; represents the preset calcium-sulfur ratio, preferably 1.03, and the actual value is between 1.05 and 1.08; represents the purity of limestone, which is 0.93; represents the solid content of the limestone slurry.

8. The method according to claim 7, wherein the method is characterized in that, The online correction of the slurry quality includes: (1) calculating a slurry supply quality coefficient , the slurry supply quality coefficient is obtained by statistics of an actual slurry supply cumulative value in a period of time , a theoretical slurry supply cumulative value in the period of time , and a theoretical slurry supply corresponding to a pH variation in the absorption tower in the period of time ; if the slurry quality is high, the calculated slurry supply quality coefficient is less than 1, the corrected make-up slurry is less than the theoretical calculation value, and over-supply of slurry is avoided; if the slurry quality is low, the calculated slurry supply quality coefficient is greater than 1, and the corrected make-up slurry is greater than the theoretical calculation value; the slurry supply quality coefficient is calculated according to the following formula (2): （2）； In the formula: represents a slurry supply quality coefficient; represents an actual slurry supply cumulative value in a period of time, t; represents a theoretical slurry supply cumulative value in the period of time, t; represents a theoretical slurry supply corresponding to the pH change amount in the absorption tower in the period of time, t; the slurry supply quality coefficient is used to reflect the actual reaction efficiency of the limestone slurry, when the slurry quality is high, <1, reduce the amount of slurry supplement; when the quality is low, >1, increase the amount of slurry supplement; (2) Based on the slurry supply quality coefficient Theoretical value of the required slurry supply amount The dynamic correction formula is shown in the following equation (3): （3） In the formula: represents the corrected slurry supply amount calculation value, m3 / h.

9. The method according to claim 8, wherein the method is characterized in that, The S4 includes: S41, generating a control signal based on the inner loop flow set value, the control signal driving the actuator in the slurry supplementing pipeline to accurately add the limestone slurry calculated into the absorption tower; S42, the slurry discharged from the open flow tank and the possible flushing wastewater are introduced into the pit together, and pumped back to the absorption tower by the pit pump to form a slurry circulation.

10. An intelligent desulfurization tower slurry pH precision measurement and automatic slurry supplement control system for implementing the method of claim 9, characterized in that, It includes: The slurry sampling and guiding subsystem includes: sampling points located at the upper and lower ends of the tower wall of the desulfurization absorption tower and two drainage pipelines (11) connecting the sampling points and the designated monitoring area of the pump house. The end of the drainage pipeline (11) is arranged vertically downward to ensure that the slurry flows smoothly into the open flow tank. The pH precision measurement subsystem comprises an open flow cell (2), two high-corrosion-resistant pH electrodes (13), an intelligent monitor host, and a self-cleaning module. The open flow cell (2) is arranged at the end of the drainage pipeline (11) and has an inlet, an outlet, and an electrode mounting port. The internal flow passage of the open flow cell (2) is optimally designed to ensure that the slurry flows smoothly through the electrodes and is quickly discharged, and the open flow cell (2) has the ability of natural flushing and pressure fluctuation resistance. The two high-corrosion-resistant pH electrodes (13) are made of high-corrosion-resistant materials and are installed in parallel in the open flow cell (2). The electrode structure considers fluid dynamics to reduce flow interference. The intelligent monitor host is connected with the two high-corrosion-resistant pH electrodes (13) and comprises a signal conditioning circuit, an A / D converter, a microprocessor, and a memory. The microprocessor is used to run programs for realizing double-channel data acquisition, comparison, effectiveness judgment, electrode state evaluation, data fusion, and final pH value output. The self-cleaning module comprises a flushing water connector (33), a flushing pipeline (32), an electromagnetic valve, and a nozzle connected with an industrial water source in sequence and is used for regularly or remotely triggering the flushing of the electrodes. The automatic slurry supplement control subsystem comprises a data acquisition unit, a controller, an actuator, and a human-machine interface. The data acquisition unit is used to acquire the original flue gas SO2 concentration, the original flue gas flow, the net flue gas SO2 concentration, the limestone slurry density, the slurry pH measurement value, and the actual limestone slurry flow in real time. The controller comprises a feedforward calculation module, a cascade control module, a fuzzy control module, and a control quantity synthesis module. The feedforward calculation module is used to perform theoretical slurry supply amount calculation, slurry quality coefficient calculation, and feedforward amount correction. The cascade control module comprises an outer loop pH controller and an inner loop flow controller. The fuzzy control module is used to store a fuzzy rule table and output a fuzzy correction amount according to the net flue gas SO2 concentration and the pH value. The control quantity synthesis module is used to synthesize the feedforward amount, the output amount of the outer loop controller, and the fuzzy correction amount to generate a final inner loop flow set value. The actuator is used to receive the controller instruction, adjust the valve opening or the pump speed of the limestone slurry pipeline, and control the slurry flow. The human-machine interface is used for parameter setting, state display, alarm prompt, and manual or automatic mode switching. The slurry circulation subsystem comprises a pit and a pit pump. The pit is arranged below the flow cell and is used to collect the outflowing slurry and flushing water. The pit pump is used to pump the collected slurry back to the desulfurization absorption tower.

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