A cement SNCR intelligent operation and maintenance method and system

Abstract

The present invention discloses a cement SNCR intelligent operation and maintenance method and system, belonging to the technical field of cement industry flue gas denitrification, comprising: a data acquisition module, used to obtain operating data of a cement DCS system, detection data of a preheater outlet flue gas analyzer, detection data of a chimney flue gas analyzer and manually set initial parameters; a data calculation and analysis module, receiving data from the acquisition module and performing data calculation and analysis; a performance evaluation module, using data obtained by the data calculation and analysis module to evaluate the working status of the preheater outlet flue gas analyzer, evaluate and diagnose the operating status of the cement kiln system, and judge the current operating status of the cement kiln; an automatic control coupling module, performing data interaction with the performance evaluation module, predicting the current optimal ammonia consumption and compressed air flow, thereby automatically adjusting the flow rates of ammonia and compressed air, and re-importing the adjusted parameters into the data acquisition module to establish a cycle.

Description

Technical field:

[0001] The present invention belongs to the technical field of cement industry flue gas denitrification, and in particular relates to a cement SNCR intelligent operation and maintenance method and system. Background technology:

[0002] Nitrogen oxides (NOx) are environmentally harmful pollutants that can easily cause acid rain and other hazards. To strengthen environmental protection, my country has enacted GB4915-2013, the "Emission Standard of Air Pollutants from the Cement Industry," to control NOx emissions. Currently, the cement industry widely uses selective non-catalytic reduction (SNCR) technology to reduce NOx emissions. Due to its advantages of simple modification and low investment, SNCR technology has been widely adopted and has undergone numerous improvements. For example, CN111773909A focuses on improving the performance of spray guns. First, the spray guns are grouped and the flow rate of each group is independently controlled. This ensures that the spray guns within each group have the same resistance loss, operating pressure, flow distribution, and atomization state, resulting in a stable atomization state of the sprayed reducing agent, thereby improving the SNCR effect. CN213032224U divides the SNCR system into multiple completely independent subsystems, each of which controls its own spray gun, thereby enhancing the adjustability of the SNCR control system. EP2723474B1 adds a dust removal device to the preheater, removing dust from the high-temperature flue gas before the SNCR reaction, thereby reducing the adverse effects of cement raw materials on SNCR. However, these patents do not address the shortcomings of large fluctuations in cement production, high emissions, high ammonia consumption, and high operating costs. The main reason for this is that current SNCR control is not ideal.

[0003] Most SNCR control research focuses on improving the stability of SNCR control systems. The most traditional SNCR control logic for the cement industry is fixed emission concentration regulation. When the chimney NOx emission concentration is within the target range (e.g., 280-320 mg / m³), the control system does not perform feedback adjustments. When the NOx emission concentration is below the target range (e.g., less than 280 mg / m³), the control system adjusts the ammonia pump frequency (or adjusts the valve opening by fixing the pump frequency) to reduce the ammonia flow rate. When the NOx emission concentration is above the target range (e.g., greater than 320 mg / m³), the control system adjusts the ammonia pump frequency (or adjusts the valve opening by fixing the pump frequency) to increase the ammonia flow rate. However, due to the long distance between the chimney and the ammonia injection point, the lag time of the flue gas analyzer is often 5-10 minutes, making it easy for NOx emission concentrations to exceed the target. Some SNCR systems use various proportional-integral and differential control methods. However, due to the extremely high fluctuations in NOx emission concentrations in the cement industry and the rapid frequency of changes, the control system frequently adjusts, which can easily lead to system oscillation and failure to converge. To ensure compliance with environmental protection standards, some cement SNCR systems employ fixed flow control, based on a fixed emission concentration. This means the ammonia pump maintains a fixed injection flow rate. As long as sufficient ammonia flow is maintained, nitrogen oxide emission concentrations can be guaranteed to meet standards. However, this control method often results in nitrogen oxide emission concentrations that are too low and ammonia flow rates that are too high, resulting in waste and requiring regular manual intervention. Consequently, traditional SNCR systems often lag significantly behind changes in nitrogen oxide emission concentrations, easily leading to excessive nitrogen oxide concentrations, high ammonia consumption, high operating costs, and the need for manual intervention.

[0004] Because traditional SNCR regulation through chimneys suffers from significant hysteresis, many researchers have begun using chimney NOx emission concentrations and other additional indicators to mitigate the adverse effects of hysteresis. Patent CN105938375A utilizes the flue gas flow rate Q and the NOx concentration in the chimney to establish a judgment formula based on the calculated and measured flow rates. This formula then reversely calculates the initial NOx concentration and adjusts the calculated reductant flow rate, ensuring that the measured NOx concentration continuously approaches the target NOx concentration and the reductant flow rate continuously approaches the calculated flow rate. This solution offers the advantage of automatically adjusting and operating after the initial parameters are set, automatically tracking, calculating, and adjusting the initial NOx concentration, thus reducing operator workload. However, patent CN105938375A has some issues: This solution assumes that the initial NOx concentration remains constant during the timeframe it automatically reverses to track the initial NOx concentration. However, initial NOx concentrations often fluctuate rapidly, especially in the current ultra-low emission environment, where initial NOx emission concentrations are highly unstable. This makes it difficult to achieve continuous and stable operation during this automatic adjustment process.

[0005] Dong Qingwu (Dong Qingwu. Design of Intelligent Control System for SNCR Denitrification of Industrial Kilns [D]. Fuzhou: Fuzhou University, 2017: 39) considered that it was impossible to establish an accurate mathematical model, considering the large delay, time-varying characteristics, and many influencing factors of the SNCR system of cement kilns. He achieved different responses through a segmented multi-level control mode, specifically controlling the injection amount of the reducing agent through the nitrogen oxide emissions and ammonia escape conditions of the chimney. Its shortcomings are similar to those of patent CN105938375A, and both cannot avoid the lag problem.

[0006] To eliminate hysteresis, patent CN104793651A proposes installing a temperature sensor, a flue gas flow monitoring sensor, and a first nitrogen oxide concentration detection sensor at the inlet of the ammonia injection zone of the decomposition furnace. Furthermore, a second nitrogen oxide concentration detection sensor and an ammonia concentration detection sensor are installed at the outlet of the decomposition furnace. Because the flue gas flow rate and nitrogen oxide concentration at the inlet of the ammonia injection zone, as well as the nitrogen oxide concentration and ammonia concentration at the outlet of the ammonia injection zone, can be measured in real time, the delay time of the SNCR system control is reduced, the hysteresis of ammonia flow changes is greatly reduced, and the response sensitivity is improved. At the same time, because the nitrogen oxide concentrations at the inlet and outlet of the ammonia injection zone are known, the shortcomings of the nonlinear changes in nitrogen oxide emission concentrations, which are caused by the numerous factors affecting nitrogen oxide emission concentrations, are eliminated to a certain extent. Furthermore, patent CN104793651A also proposes a method for adjusting the control logic using parameters such as the temperature correction coefficient and the ammonia slip correction coefficient. However, this solution has some practical problems: First, the working conditions at the inlet of the ammonia injection zone and the outlet of the decomposition furnace are poor, the flue gas temperature is 850-950℃, and the dust concentration is as high as 500-1500g / Nm3. The accuracy and precision of the nitrogen oxide concentration detection sensors used in small quantities in industrial applications are low, and the failure rate is extremely high, and the data utilization value is low. At the same time, the existing flue gas flow monitoring sensors and ammonia concentration detection sensors cannot meet the installation conditions here, and the ammonia escape correction parameters are even more unavailable. Therefore, the method of patent CN104793651A is fundamentally unattainable due to practical factors. Second, cement clinker production is not a stable production process. Changes in the composition of various raw materials and the addition amount of cement, as well as changes in the performance of cement process equipment, will cause changes in the cement process, thereby affecting the generation of nitrogen oxides. Fine-tuning by relying solely on the temperature correction coefficient and the ammonia escape correction coefficient will deviate greatly from the actual situation. To address hysteresis, CN103418228A installed a flue gas analyzer at the C1 outlet, and CN103977705A added an ammonia slip analyzer and other equipment. The system then used relevant parameters and the CO concentration and temperature provided by the flue gas analyzer at the original decomposition furnace outlet to comprehensively determine the initial nitrogen oxide emission concentration. This system has the advantages of shorter lag time and higher prediction accuracy than the original system. However, CN103418228A ignored the fact that the lag time between the C1 flue gas analyzer and the chimney flue gas analyzer is not a fixed value, and ignored the shortcomings of different nitrogen oxide feedback concentrations caused by the different working environments of the C1 flue gas analyzer and the chimney analyzer. CN103977705A relied on the unreliable flue gas analyzer at the decomposition furnace outlet, and the initial NOx concentration in the judgment logic was automatically generated based on data from the previous half hour. This system was unable to adapt to the extremely volatile and rapidly changing nitrogen oxide emission concentrations of the cement industry.

[0007] Patent CN111665711A considers the impact of various process parameters on kiln system operation and uses changes in kiln system parameters to predict nitrogen oxide and ammonia consumption. A multivariable input-output controller was designed, incorporating coal feed rate and sludge addition into SNCR adjustment. Changes in any parameter, including nitrogen oxide emission concentration, adjust the ammonia dosage of the SNCR. Changes in multiple parameters simultaneously influence the control. This solution has the advantage of being more accurate and timely than traditional SNCR systems by comprehensively considering the impact of several kiln parameters. However, this solution also has significant drawbacks: First, the impact of the cement kiln on SNCR is abstracted into two parameters: coal feed rate and sludge addition, ignoring the effects of other cement process parameters on SNCR, resulting in low accuracy. Second, the impact of coal feed rate and sludge addition on SNCR is subjectively characterized as a linear effect, which deviates significantly from the actual SNCR, resulting in unsatisfactory control results.

[0008] The development of numerical simulation technology has provided researchers with new insights. Patent CN203043832U uses CFD to simulate flow fields, determining the velocity and temperature fields within the precalciner. This approach helps identify the optimal injection location, ensuring a suitable temperature window and sufficient reaction time for improved denitrification efficiency. However, current research on simulated flow fields within precalciners in the cement industry primarily focuses on steady-state simulations, and there is currently no recognized, mature technology for cement production. Patent CN203043832U employs unsteady-state simulations to adjust SNCR control, which is far from realistic and currently unsuitable for practical applications. Liu Xiaodong (Liu Xiaodong. Research on cement denitrification process control system [D]. Jinan: Jinan University, 2017: 57) established the valve opening-NOx concentration characteristic based on the large hysteresis characteristics of cement SNCR, and designed a DMC theoretical controller to adjust the ammonia flow rate mainly through the reaction zone temperature. However, for the strong disturbance problem in the cement denitrification process, only an expert rule table can be designed. When a strong disturbance occurs, it switches to the expert rule and forcibly regulates the ammonia flow rate according to the nitrogen oxide emission concentration. Therefore, it can only be used when the nitrogen oxide fluctuation is small and the cement production parameters are relatively stable.

[0009] CN203281218U takes into account the non-ideal reaction temperature of ammonia solution injected into the spray gun and adds a temperature detector to each spray gun to adjust the ammonia flow rate according to the different temperatures. CN112403250A uses acoustic temperature measurement to coordinate the SNCR control of cement kilns. The problem with this solution is that it simply uses the injection point temperature as the most important factor affecting the SNCR reaction, while ignoring other factors. Therefore, adopting this solution is theoretically unreasonable and cannot effectively adjust the system.

[0010] From the above, we can see that the main problems of the existing SNCR system control in the cement industry are as follows:

[0011] First, the distance between the chimney flue gas analyzer and the SNCR reaction zone in traditional SNCR systems makes it prone to exceeding the standard for nitrogen oxide emissions. Using the chimney flue gas analyzer's feedback data as the SNCR control parameter results in significant lag. Even researchers have employed various control strategies, including increasing flue gas flow and ammonia slip parameters, but have still not been able to resolve this issue.

[0012] Second, the concentration of nitrogen oxide emissions from the cement industry fluctuates greatly and changes rapidly. Even though some scholars have added a flue gas analyzer to C1 to shorten the detection lag, the working environment of the C1 flue gas analyzer is quite different from that of the chimney, resulting in poor data synchronization. In addition, due to cement process reasons, the lag time between the C1 flue gas analyzer and the chimney flue gas analyzer is not a fixed value. Simply using the C1 flue gas analyzer instead of the chimney flue gas analyzer for control still has poor accuracy.

[0013] Third, the logical relationship between changes in cement kiln process parameters, NOx emission concentrations, and SNCR control is illogical, and numerical simulation results are currently inadequate for production guidance. The current control logic cannot effectively predict NOx concentration changes based on process parameter changes, thereby controlling the SNCR system.

[0014] Fourth, current cement denitrification primarily considers fuel NOx and thermal NOx, with little consideration of raw material NOx carried in cement raw meal. Consequently, the logic behind SNCR control rarely considers the impact of raw meal on NOx emissions and SNCR.

[0015] At present, SNCR control systems mainly control the flow of ammonia water, but do not pay attention to the regulation of compressed air flow. They generally only play the role of metering and monitoring. Summary of the invention:

[0016] In view of the above-mentioned defects of the prior art, the present invention provides a cement SNCR intelligent operation and maintenance method and system.

[0017] The first object of the present invention is to provide a method for obtaining ammonia flow based on a rotor scale, which at least comprises:

[0018] S1. When the raw material feeding amount is kept constant, the process of the rotor scale feeding amount of raw material is expressed by a waveform diagram;

[0019] S2. Obtaining a large period of the waveform;

[0020] S3. Divide the waveform of each large cycle into several small cycles, and the time interval of each small cycle is the same;

[0021] S4. Take the maximum value of the positive peak of each small cycle;

[0022] S5. Generate a trend line using the starting point of the large cycle, the maximum value of the positive wave peak, and the end point of the large cycle;

[0023] S6. Real-time ammonia flow rate = ammonia flow rate calculated by the initial algorithm + proportional coefficient x peak height; where:

[0024] The proportional coefficient is: the proportional relationship between the range of change of ammonia flow rate and the height of the highest point in the large cycle.

[0025] 3. Preferably, the ammonia flow rate calculated by the initial algorithm is:

[0026] When ΔC c1NOx-average >D r2 or -D r2 >ΔC c1NOx-average Or Er3<ΔC c1NOx When , the ammonia flow rate is the present value V0;

[0027] When D r2 >ΔC c1NOx-average >D r1 When the ammonia flow rate is V0+V1+K1*ΔC c1co +K2*ΔA kiln ;

[0028] When-D r1 >ΔC c1NOx-average >-D r2 When the ammonia flow rate is V0-V2+K1*ΔC c1co +K2*ΔA kiln ;

[0029] When D r1 >ΔC c1NOx-average >-D r1 , and -Er3<ΔC c1NOx <-Er2, the ammonia flow rate is V0-V3+K1*ΔC c1co +K2*ΔA kiln ;

[0030] When D r1 >ΔC c1NOx-average >-D r1 , and -Er2<ΔC c1NOx <-Er1, the ammonia flow rate is V0-V4+K1*ΔC c1co +K2*ΔA kiln ;

[0031] When D r1 >ΔC c1NOx-average >-D r1 , and Er1<ΔC c1NOx <Er2, the ammonia flow rate is V0+V5+K1*ΔC c1co+K2*ΔA kiln ;

[0032] When D r1 >ΔC c1NOx-average >-D r1 , and Er2<ΔC c1NOx <Er3, the ammonia flow rate is V0+V6+K1*ΔC c1co +K2*ΔA kiln ;in:

[0033] D r1 The lower limit of the change rate of the average NOx concentration of the C1 analyzer is set manually, D r2 The upper limit of the change rate of the average NOx concentration of the C1 analyzer is set manually; ΔC c1NOx-average is the rate of change of the average NOx concentration of the C1 analyzer, ΔC c1NOx For T 00 C during the period c1NOx With the previous T 00 C during the period c1NOx Er1 is the manually set lower limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, Er2 is the manually set middle limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, Er3 is the manually set upper limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, V0 is the actual flow rate of ammonia water; V1, V2, V3, V4, V5, V6 are the manually set ammonia flow rate changes of the precise SNCR system; ΔC c1co For T 00 C during the period c1co With the previous T 00 C during the period c1co The difference between kiln T 00 A during the period kiln With the previous T 00 A during the period kiln K1 is the manually set CO concentration change influencing factor, and K2 is the manually set kiln current change influencing factor.

[0034] A second object of the present invention is to provide an ammonia flow acquisition module based on a rotor scale, comprising at least:

[0035] The expression module uses a waveform diagram to express the process of the rotor scale adjusting the raw material feeding amount when the raw material feeding amount is kept constant.

[0036] A large cycle acquisition module, which acquires the large cycle of the waveform;

[0037] The small cycle acquisition module divides the waveform of each large cycle into several small cycles, and the time interval of each small cycle is the same;

[0038] The maximum value acquisition module takes the maximum value of the positive peak of each small cycle;

[0039] The trend module generates a trend line from the starting point of the large cycle, the maximum value of the positive peak, and the end point of the large cycle;

[0040] Calculation module, real-time ammonia flow rate = ammonia flow rate calculated by the initial algorithm + proportional coefficient X peak height; where:

[0041] The proportional coefficient is: the proportional relationship between the range of change of ammonia flow rate and the height of the highest point in the large cycle.

[0042] 4. Preferably, the initially calculated ammonia flow rate is:

[0043] When ΔC c1NOx-average >D r2 or -D r2 >ΔC c1NOx-average Or Er3<ΔC c1NOx When , the ammonia flow rate is the present value V0;

[0044] When D r2 >ΔC c1NOx-average >D r1 When the ammonia flow rate is V0+V1+K1*ΔC c1co +K2*ΔA kiln ;

[0045] When-D r1 >ΔC c1NOx-average >-D r2 When the ammonia flow rate is V0-V2+K1*ΔC c1co +K2*ΔA kiln ;

[0046] When D r1 >ΔC c1NOx-average >-D r1 , and -Er3<ΔC c1NOx <-Er2, the ammonia flow rate is V0-V3+K1*ΔC c1co +K2*ΔA kiln ;

[0047] When D r1 >ΔC c1NOx-average >-D r1 , and -Er2<ΔC c1NOx <-Er1, the ammonia flow rate is V0-V4+K1*ΔC c1co +K2*ΔA kiln ;

[0048] When D r1 >ΔC c1NOx-average >-Dr1 , and Er1<ΔC c1NOx <Er2, the ammonia flow rate is V0+V5+K1*ΔC c1co +K2*ΔA kiln ;

[0049] When D r1 >ΔC c1NOx-average >-D r1 , and Er2<ΔC c1NOx <Er3, the ammonia flow rate is V0+V6+K1*ΔC c1co +K2*ΔA kiln ;in:

[0050] D r1 The lower limit of the change rate of the average NOx concentration of the C1 analyzer is set manually, D r2 The upper limit of the change rate of the average NOx concentration of the C1 analyzer is set manually; ΔC c1NOx-average is the rate of change of the average NOx concentration of the C1 analyzer, ΔC c1NOx For T 00 C during the period c1NOx With the previous T 00 C during the period c1NOx Er1 is the manually set lower limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, Er2 is the manually set middle limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, Er3 is the manually set upper limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, V0 is the actual flow rate of ammonia water; V1, V2, V3, V4, V5, V6 are the manually set ammonia flow rate changes of the precise SNCR system; ΔC c1co For T 00 C during the period c1co With the previous T 00 C during the period c1co The difference between kiln T 00 A during the period kiln With the previous T 00 A during the period kiln K1 is the manually set CO concentration change influencing factor, and K2 is the manually set kiln current change influencing factor.

[0051] The third object of the present invention is to provide a cement SNCR intelligent operation and maintenance system, comprising:

[0052] Data acquisition module, used to obtain the operating data of the cement DCS system, the detection data of the preheater outlet flue gas analyzer, the detection data of the chimney flue gas analyzer and the manual initial setting parameters;

[0053] The data calculation and analysis module receives the data from the acquisition module and performs data calculation and analysis;

[0054] The performance evaluation module uses the data obtained by the data calculation and analysis module to evaluate the working status of the flue gas analyzer at the preheater outlet, evaluate and diagnose the operating status of the cement kiln system, and determine the current operating status of the cement kiln;

[0055] The automatic control coupling module exchanges data with the performance evaluation module to predict the current optimal ammonia consumption and compressed air flow, thereby automatically adjusting the flow rates of ammonia and compressed air. The adjusted parameters are then re-imported into the data acquisition module to establish a cycle.

[0056] Preferably, the data calculation and analysis module includes:

[0057] Current calculation module for calculating kiln current;

[0058] Coal feeding calculation module for calculating the coal feeding amount at the kiln tail;

[0059] A raw meal feed quantity calculation module for calculating the raw meal feed quantity;

[0060] CO concentration calculation module for calculating CO concentration of C1 analyzer;

[0061] C1 analyzer NOx concentration fluctuation calculation module for calculating C1 analyzer NOx concentration fluctuation;

[0062] A chimney analyzer NOx concentration fluctuation calculation module for calculating the chimney analyzer NOx concentration fluctuation;

[0063] A difference calculation module for calculating the difference and coefficient of variation of NOx between C1 and chimney flue gas analyzer;

[0064] C1 analyzer NOx concentration calculation module for calculating C1 analyzer NOx concentration;

[0065] Preferably, the performance evaluation module includes:

[0066] Cement kiln system operation status assessment module, used for kiln operation status assessment, feeding operation status assessment, and calciner operation status assessment;

[0067] The flue gas analyzer operating status evaluation module is used for C1 analyzer operating status evaluation, chimney analyzer operating status evaluation, and corresponding operating status evaluation of C1 and chimney analyzers.

[0068] Preferably, the automatic control coupling module includes:

[0069] An ammonia flow calculation module for calculating the ammonia flow rate;

[0070] Compressed air flow calculation module for calculating compressed air flow.

[0071] A fourth object of the present invention is to provide a cement SNCR intelligent operation and maintenance method, comprising the following steps:

[0072] The first step is data collection, which includes the operating data of the cement DCS system, the detection data of the flue gas analyzer at the preheater outlet, the detection data of the chimney flue gas analyzer, and the manually set initial parameters;

[0073] The second step is data calculation and analysis, which uses the real-time data obtained by the data acquisition module and combines it with the manually input parameters to perform data calculation and analysis;

[0074] The third step is performance evaluation. Based on the data calculation and analysis results, the current operating status of the cement kiln is evaluated through various evaluation models to analyze the state of the cement kiln and select the appropriate SNCR control solution.

[0075] The fourth step is automatic control coupling of the SNCR system. The SNCR control scheme obtained through performance evaluation is coupled with the nitrogen oxide production status through an algorithm to automatically optimize the SNCR control and make the SNCR system reach the optimal working state.

[0076] The fifth step is to establish a loop. Through the SNCR intelligent operation and maintenance system, the system automatically optimizes and adjusts. The data is returned to the data acquisition module to repeat the second step, thus establishing an intelligent operation and maintenance loop.

[0077] Preferably, the operating data of the cement DCS system includes: kiln current, kiln tail coal feeding amount, raw meal feeding amount, hoist current, CO concentration fed back by C1 flue gas analyzer, nitrogen oxide concentration fed back by C1 flue gas analyzer, oxygen concentration fed back by C1 flue gas analyzer, and converted nitrogen oxide concentration fed back by chimney flue gas analyzer.

[0078] Preferably, the operation data of the cement SNCR system includes adjusting the ammonia flow rate V0.

[0079] Preferably, in the second step, the data calculation and analysis includes:

[0080] Calculate kiln current calculation;

[0081] Calculate the amount of coal fed to the kiln tail;

[0082] Calculate raw meal feed quantity;

[0083] Calculate the CO concentration of the C1 analyzer;

[0084] Calculate the NOx concentration fluctuation of C1 analyzer;

[0085] Calculate the NOx concentration fluctuations of the stack analyzer;

[0086] Calculate the difference and coefficient of variation of NOx between C1 and stack flue gas analyzer;

[0087] Calculate the NOx concentration of the C1 analyzer.

[0088] Preferably, in the third step, the performance evaluation includes:

[0089] Evaluate the operating status of the cement kiln system: including kiln operating status evaluation, feeding operating status evaluation, and calciner operating status evaluation;

[0090] Evaluate the operating status of flue gas analyzers: including the operating status evaluation of C1 analyzer, the operating status evaluation of chimney analyzer, and the corresponding operating status evaluation of C1 and chimney analyzers.

[0091] Preferably, in the fourth step, the SNCR system automatic control coupling includes:

[0092] Calculate ammonia flow rate;

[0093] Calculate compressed air flow.

[0094] The present invention has the following beneficial effects:

[0095] First, the present invention takes into account the influence of raw nitrogen oxides in raw meal on cement kiln denitrification and utilizes the fluctuation of the raw meal rotor scale to enhance the control capability of the SNCR system.

[0096] Second, the present invention uses the NOx concentration of the C1 flue gas analyzer to control the SNCR system, and continuously corrects the data asynchrony between the C1 flue gas analyzer and the chimney flue gas analyzer due to different working environments and lag times through intelligent judgment, thereby greatly enhancing the reliability and accuracy of the data and shortening the lag.

[0097] Third, the present invention establishes a set of logical relationships between changes in various process parameters of cement kilns, nitrogen oxide emission concentrations, and SNCR control that conform to actual conditions, thereby greatly increasing the adaptability of the SNCR system to changes in cement kiln processes.

[0098] Fourthly, the present invention controls the flow rate of compressed air according to the flow rate of ammonia water, and ensures that the ammonia water particles are between 20-30 μm, thereby ensuring the atomization effect.

[0099] Fifth, when the NOx concentration fluctuates greatly, the present invention preferentially uses the nitrogen oxide concentration change rate of the C1 flue gas analyzer to control the ammonia flow rate, which greatly enhances the predictive ability of controlling the NOx emission concentration and ammonia consumption compared with using the C1 flue gas analyzer alone.

[0100] Compared with patents CN111773909A, CN213032224U, EP2723474B1 and CN111135683A, which all use chimney nitrogen oxide emission concentration to control SNCR, the present invention greatly shortens the problem of long response time of the SNCR system caused by the large lag of the chimney flue gas analyzer.

[0101] Compared to patent CN105938375A, which takes a long time to reversely calculate the initial nitrogen oxide concentration and assumes that the initial nitrogen oxide concentration remains unchanged during this time frame to calculate the ammonia dosage, the present invention prioritizes using the rate of change of nitrogen oxide concentration from the C1 flue gas analyzer to determine the ammonia dosage, offering strong predictive capabilities and a fast response. Compared to patent CN104793651A, which requires installing NOx analyzers at the inlet and outlet of the ammonia injection zone of the decomposition furnace, the working environment in this area is harsh, the data is unreliable, and the instrument has a high failure rate, making it unusable. The present invention, which utilizes the mature C1 flue gas analyzer, does not have this problem. Although CN103418228A also uses the C1 analyzer to control the SNCR system, CN103418228A ignores the fact that the lag time between the C1 flue gas analyzer and the chimney flue gas analyzer is not a constant value, ignores the shortcomings of the nitrogen oxide feedback concentration deviation and easy fluctuation caused by the different working environments of the C1 flue gas analyzer and the chimney analyzer, and unreliable feedback concentration during backwashing of the C1 flue gas analyzer, and forcibly uses the C1 analyzer to replace the chimney analyzer, which easily causes the nitrogen oxide emission concentration to exceed the standard; the present invention not only uses the C1 analyzer, but also makes intelligent judgments on the lag time, concentration changes, whether to backwash, etc. between the C1 flue gas analyzer and the chimney analyzer, fully eliminates adverse effects, completely solves the problem of data asynchrony between the C1 analyzer and the chimney analyzer, and improves the reliability of the SNCR system. Compared with patent CN103977705A, which relies on an unreliable flue gas analyzer at the decomposition furnace outlet, the initial NOx concentration in the judgment logic is automatically generated based on data from the previous half hour, which cannot adapt to the production fluctuations and rapid changes of cement kilns. The present invention, on the other hand, preferentially uses the nitrogen oxide concentration change rate of the C1 flue gas analyzer to determine the amount of ammonia solution used, which has strong predictive capabilities and can adapt to the large fluctuations in cement kiln production. Compared with patent CN111665711A, which takes into account the influence of various process parameters of the kiln system operation, it regards the coal feed rate and the amount of sludge added as the main influences on SNCR, and subjectively characterizes them as linear influences. Compared with patents CN203281218U and CN112403250A, it regards the reaction zone temperature as the main influencing factor of SNCR, completely ignoring other influencing factors. According to the actual situation of cement production, the present invention uses the nitrogen oxide concentration change rate of the C1 flue gas analyzer and the kiln current as influencing factors, and defines the influencing factors as both step functions and linear functions, which is closer to actual production conditions. Compared with the above patents, this patent proposes for the first time to take into account the impact of the fluctuation of the raw meal rotor scale on SNCR, with stronger logical judgment ability and more accurate SNCR denitrification effect. Description of the drawings:

[0102] Figure 1 A system block diagram of a preferred embodiment of the present invention;

[0103] Figure 2 This is a waveform diagram of the process of the rotor scale for raw meal feeding in the preferred embodiment of the present invention;

[0104] Figure 3 This is a large-cycle waveform diagram in a preferred embodiment of the present invention;

[0105] Figure 4 This is a small-cycle waveform diagram in a preferred embodiment of the present invention;

[0106] Figure 5 This is a waveform diagram showing the maximum value of the positive peak in the preferred embodiment of the present invention;

[0107] Figure 6 This is a trend line graph in a preferred embodiment of the present invention. Specific implementation method:

[0108] The present invention will be further explained below with reference to the accompanying drawings and embodiments.

[0109] See also Figures 1 to 6 A method for obtaining ammonia flow rate based on a rotor scale. The raw meal feed rate and the kiln tail coal feed rate are both controlled by the rotor scale. However, due to the inherent characteristics of the rotor scale, the raw meal feed and the kiln tail coal feed cannot be a stable average feeding process, but rather a feeding process that feeds in batches as the rotor scale rotates. The actual feeding situation has a clear corresponding relationship with the rotor scale speed. It includes:

[0110] S1. When the raw material feeding amount is kept constant, the process of the rotor scale feeding amount of raw material is expressed by a waveform diagram;

[0111] S2. Obtaining a large period of the waveform;

[0112] S3. Divide the waveform of each large cycle into several small cycles, and the time interval of each small cycle is the same;

[0113] S4. Take the maximum value of the positive peak of each small cycle;

[0114] S5. Generate a trend line using the starting point of the large cycle, the maximum value of the positive wave peak, and the end point of the large cycle;

[0115] S6, real-time ammonia flow rate = ammonia flow rate calculated by the initial algorithm + proportional coefficient x peak height;

[0116] in:

[0117] The proportional coefficient is: the proportional relationship between the range of change of ammonia flow rate and the height of the highest point in the large cycle.

[0118] The ammonia flow rate calculated by the initial algorithm is:

[0119] When ΔC c1NOx-average >Dr2 or -D r2 >ΔC c1NOx-average Or Er3<ΔC c1NOx When , the ammonia flow rate is the present value V0;

[0120] When D r2 >ΔC c1NOx-average >D r1 When the ammonia flow rate is V0+V1+K1*ΔC c1co +K2*ΔA kiln ;

[0121] When-D r1 >ΔC c1NOx-average >-D r2 When the ammonia flow rate is V0-V2+K1*ΔC c1co +K2*ΔA kiln ;

[0122] When D r1 >ΔC c1NOx-average >-D r1 , and -Er3<ΔC c1NOx <-Er2, the ammonia flow rate is V0-V3+K1*ΔC c1co +K2*ΔA kiln ;

[0123] When D r1 >ΔC c1NOx-average >-D r1 , and -Er2<ΔC c1NOx <-Er1, the ammonia flow rate is V0-V4+K1*ΔC c1co +K2*ΔA kiln ;

[0124] When D r1 >ΔC c1NOx-average >-D r1 , and Er1<ΔC c1NOx <Er2, the ammonia flow rate is V0+V5+K1*ΔC c1co +K2*ΔA kiln ;

[0125] When D r1 >ΔC c1NOx-average >-D r1 , and Er2<ΔC c1NOx <Er3, the ammonia flow rate is V0+V6+K1*ΔC c1co +K2*ΔA kiln ;in:

[0126] D r1 The lower limit of the change rate of the average NOx concentration of the C1 analyzer is set manually, Dr2 The upper limit of the change rate of the average NOx concentration of the C1 analyzer is set manually; ΔC c1NOx-average is the rate of change of the average NOx concentration of the C1 analyzer, Er1 is the manually set lower limit of the fluctuation of the average NOx concentration of the C1 flue gas analyzer, Er2 is the manually set middle limit of the fluctuation of the average NOx concentration of the C1 flue gas analyzer, Er3 is the manually set upper limit of the fluctuation of the average NOx concentration of the C1 flue gas analyzer, V0 is the actual flow rate of ammonia water; V1, V2, V3, V4, V5, V6 are the manually set ammonia flow rate changes of the precise SNCR system; ΔC c1co For T 00 C during the period c1co With the previous T 00 C during the period c1co The difference between kiln T 00 A during the period kiln With the previous T 00 A during the period kiln K1 is the manually set CO concentration change influencing factor, and K2 is the manually set kiln current change influencing factor.

[0127] An ammonia flow acquisition module based on a rotor scale, comprising:

[0128] The expression module uses a waveform diagram to express the process of the rotor scale adjusting the raw material feeding amount when the raw material feeding amount is kept constant.

[0129] A large cycle acquisition module, which acquires the large cycle of the waveform;

[0130] The small cycle acquisition module divides the waveform of each large cycle into several small cycles, and the time interval of each small cycle is the same;

[0131] The maximum value acquisition module takes the maximum value of the positive peak of each small cycle;

[0132] The trend module generates a trend line from the starting point of the large cycle, the maximum value of the positive peak, and the end point of the large cycle;

[0133] Calculation module, real-time ammonia flow rate = ammonia flow rate calculated by the initial algorithm + proportional coefficient X peak height; where:

[0134] The proportional coefficient is: the proportional relationship between the range of change of ammonia flow rate and the height of the highest point in the large cycle.

[0135] The ammonia flow rate calculated by the initial algorithm is:

[0136] When ΔC c1NOx-average >D r2 or -D r2 >ΔCc1NOx-average Or Er3<ΔC c1NOx When , the ammonia flow rate is the present value V0;

[0137] When D r2 >ΔC c1NOx-average >D r1 When the ammonia flow rate is V0+V1+K1*ΔC c1co +K2*ΔA kiln ;

[0138] When-D r1 >ΔC c1NOx-average >-D r2 When the ammonia flow rate is V0-V2+K1*ΔC c1co +K2*ΔA kiln ;

[0139] When D r1 >ΔC c1NOx-average >-D r1 , and -Er3<ΔC c1NOx <-Er2, the ammonia flow rate is V0-V3+K1*ΔC c1co +K2*ΔA kiln ;

[0140] When D r1 >ΔC c1NOx-average >-D r1 , and -Er2<ΔC c1NOx <-Er1, the ammonia flow rate is V0-V4+K1*ΔC c1co +K2*ΔA kiln ;

[0141] When D r1 >ΔC c1NOx-average >-D r1 , and Er1<ΔC c1NOx <Er2, the ammonia flow rate is V0+V5+K1*ΔC c1co +K2*ΔA kiln ;

[0142] When D r1 >ΔC c1NOx-average >-D r1 , and Er2<ΔC c1NOx <Er3, the ammonia flow rate is V0+V6+K1*ΔC c1co +K2*ΔA kiln ;in:

[0143] D r1 The lower limit of the change rate of the average NOx concentration of the C1 analyzer is set manually, D r2The upper limit of the change rate of the average NOx concentration of the C1 analyzer is set manually; ΔC c1NOx-average is the rate of change of the average NOx concentration of the C1 analyzer, Er1 is the manually set lower limit of the fluctuation of the average NOx concentration of the C1 flue gas analyzer, Er2 is the manually set middle limit of the fluctuation of the average NOx concentration of the C1 flue gas analyzer, Er3 is the manually set upper limit of the fluctuation of the average NOx concentration of the C1 flue gas analyzer, V0 is the actual flow rate of ammonia water; V1, V2, V3, V4, V5, V6 are the manually set ammonia flow rate changes of the precise SNCR system; ΔC c1co For T 00 C during the period c1co With the previous T 00 C during the period c1co The difference between kiln T 00 A during the period kiln With the previous T 00 A during the period kiln K1 is the manually set CO concentration change influencing factor, and K2 is the manually set kiln current change influencing factor.

[0144] In this example, a cement SNCR intelligent operation and maintenance system includes a data acquisition module, a data calculation and analysis module, a performance evaluation module, and an automatic control coupling module; wherein:

[0145] The data collected by the data acquisition module include the operating data of the cement DCS system, the detection data of the flue gas analyzer at the outlet of the preheater C1, the detection data of the chimney flue gas analyzer, and the manual initial setting parameters;

[0146] The data calculation and analysis module receives the data from the acquisition module and performs data calculation and analysis;

[0147] The performance evaluation module uses the data obtained by the data calculation and analysis module to evaluate the working status of the flue gas analyzer at the preheater outlet. It also evaluates and diagnoses the operating status of the cement kiln system to determine the current operating status of the cement kiln.

[0148] The automatic control coupling module is connected to the performance evaluation module to predict the current optimal ammonia consumption and compressed air flow, thereby automatically adjusting the flow rates of ammonia (using the above-mentioned ammonia flow acquisition method based on a rotor scale or the ammonia flow acquisition module based on a rotor scale) and compressed air flow. The adjusted parameters are re-imported into the data acquisition module to establish a cycle.

[0149] The data calculation and analysis module includes:

[0150] Current calculation module for calculating kiln current;

[0151] Coal feeding calculation module for calculating the coal feeding amount at the kiln tail;

[0152] A raw meal feed quantity calculation module for calculating the raw meal feed quantity;

[0153] CO concentration calculation module for calculating CO concentration of C1 analyzer;

[0154] C1 analyzer NOx concentration fluctuation calculation module for calculating C1 analyzer NOx concentration fluctuation;

[0155] A chimney analyzer NOx concentration fluctuation calculation module for calculating the chimney analyzer NOx concentration fluctuation;

[0156] A difference calculation module for calculating the difference and coefficient of variation of NOx between C1 and chimney flue gas analyzer;

[0157] C1 analyzer NOx concentration calculation module for calculating C1 analyzer NOx concentration;

[0158] The performance evaluation module includes:

[0159] Cement kiln system operation status assessment module, used for kiln operation status assessment, feeding operation status assessment, and calciner operation status assessment;

[0160] The flue gas analyzer operating status evaluation module is used for C1 analyzer operating status evaluation, chimney analyzer operating status evaluation, and corresponding operating status evaluation of C1 and chimney analyzers.

[0161] The automatic control coupling module includes:

[0162] An ammonia flow calculation module for calculating the ammonia flow rate;

[0163] Compressed air flow calculation module for calculating compressed air flow.

[0164] The data calculation and analysis module includes the following functions:

[0165] 1) Main equation for kiln current calculation;

[0166] 2) Main equation for calculating the amount of coal fed to the kiln tail;

[0167] 3) Main equation for calculating raw meal feed quantity;

[0168] 4) Main equation for calculating CO concentration of C1 analyzer;

[0169] 5) Main equation for calculating NOx concentration fluctuations in the C1 analyzer;

[0170] 6) Main equation for calculating NOx concentration fluctuations in stack analyzers;

[0171] 7) Main equations for calculating the difference and coefficient of variation of NOx between C1 analyzer and stack flue gas analyzer;

[0172] 8) Main equation for calculating NOx concentration of C1 analyzer;

[0173] The performance evaluation module includes the following functions:

[0174] 1) Cement kiln system operating status assessment: including kiln operating status assessment, feeding operating status assessment, and calciner operating status assessment;

[0175] 2) Flue gas analyzer operating status assessment: including C1 analyzer operating status assessment, chimney analyzer operating status assessment, and corresponding operating status assessment of C1 and chimney analyzers;

[0176] The automatic control coupling module includes the following functions:

[0177] 1) Main equation for calculating ammonia flow rate;

[0178] 2) Main equation for compressed air flow calculation;

[0179] A cement SNCR intelligent operation and maintenance method includes the following steps:

[0180] The first step is data collection, which includes three parts: cement kiln system, SNCR system operation data collection and manual initial setting parameter import; cement kiln operation data import includes kiln current, kiln tail coal feeding amount, raw meal feeding amount, hoist current, CO concentration fed by C1 flue gas analyzer, nitrogen oxide concentration fed by C1 flue gas analyzer, oxygen concentration fed by C1 flue gas analyzer, and converted nitrogen oxide concentration fed by chimney flue gas analyzer; SNCR system operation data collection includes adjusting ammonia flow rate V0; manual initial setting parameters include: lag time of chimney analyzer compared to C1 analyzer when T30 raw mill is running, ΔT3 raw mill The change in the lag time when stopping, n is the number of judgment cycles of the NOx difference and variation coefficient between C1 and the chimney, Dr1 and Dr2 are manually set limits on the rate of change of the NOx average concentration of the C1 analyzer (unit: mg / m3 / s), Er1, Er2, Er3 are manually set limits on the fluctuation of the NOx average concentration of the C1 flue gas analyzer (unit: mg / m3), V1, V2, V3, V4, V5, V6 are manually set changes in the ammonia flow rate of the precise SNCR system (unit L / h), K1 is manually set the CO concentration change influencing factor, K2 is manually set the kiln current change influencing factor. Alow is the manually set lower limit of kiln current (unit: ampere), Bcoal-low is the manually set lower limit of kiln tail coal feeding (unit: ton / hour), Bmeal-low is the manually set lower limit of raw meal feeding (unit: ton / hour), Cc1NOxΔT-normal is the manually set NOx fluctuation value limit of C1 analyzer (unit: mg / m3 / s), CchNOxΔT-normal is the manually set NOx fluctuation value limit of chimney analyzer (unit: mg / m3 / s), Cvt-normal is the manually set accuracy synchronization coefficient of C1 and chimney analyzer (dimensionless).

[0181] The second step is data calculation and analysis. The real-time data obtained by the data acquisition module is combined with the manually input parameters to perform data calculation and analysis according to the method provided by the prescribed equation.

[0182] The third step is performance evaluation. Based on the data calculation and analysis results, the current operating status of the cement kiln is evaluated through various evaluation models to analyze the status of the cement kiln and select the SNCR control scheme.

[0183] The fourth step is automatic control coupling of the SNCR system. The SNCR control scheme obtained through performance evaluation is coupled with the nitrogen oxide production state through a reasonable algorithm to automatically optimize the SNCR control and make the SNCR system reach the best working state.

[0184] The fifth step is to establish a loop. Through the SNCR intelligent operation and maintenance system, the system automatically optimizes and adjusts. The data is returned to the data acquisition module to repeat the second step, thus establishing an intelligent operation and maintenance loop.

[0185] The second step of data calculation and analysis includes the following:

[0186] 1) Main equation for kiln current calculation;

[0187] 2) Main equation for calculating the amount of coal fed to the kiln tail;

[0188] 3) Main equation for calculating raw meal feed quantity;

[0189] 4) Main equation for calculating CO concentration of C1 analyzer;

[0190] 5) Main equation for calculating NOx concentration fluctuations in the C1 analyzer;

[0191] 6) Main equation for calculating NOx concentration fluctuations in stack analyzers;

[0192] 7) Main equations for calculating the difference and coefficient of variation of NOx between C1 and stack flue gas analyzer;

[0193] 8) Main equation for calculating NOx concentration of C1 analyzer;

[0194] The performance evaluation described in step 3 includes the following:

[0195] 1) Cement kiln system operating status assessment: including kiln operating status assessment, feeding operating status assessment, and calciner operating status assessment;

[0196] 2) Flue gas analyzer operating status assessment: including C1 analyzer operating status assessment, chimney analyzer operating status assessment, and corresponding operating status assessment of C1 and chimney analyzers;

[0197] The automatic control coupling of the SNCR system described in the fourth step includes the following:

[0198] 1) Main equation for calculating ammonia flow rate;

[0199] 2) Main equation for compressed air flow calculation;

[0200] The above-mentioned cement kiln SCR system can also use this intelligent operation and maintenance system to control the consumption of ammonia water.

[0201] The following uses the SNCR intelligent operation and maintenance system on a 5000t / d cement clinker production line as an example to further illustrate the technical concept of the present invention. This example is only used to illustrate the present invention and is not intended to limit the scope of the present invention. Cement clinker production lines with different production capacities can all be targeted to build SNCR intelligent operation and maintenance systems. Various modifications or changes made by those skilled in the art based on this invention also fall within the scope defined by the appended claims of this application.

[0202] like Figure 1 As shown, the cement SNCR intelligent operation and maintenance system involved in the present invention includes a data acquisition module, a data calculation and analysis module, a performance evaluation module and an automatic control coupling module.

[0203] The first step is data acquisition. The data acquisition module of the present invention imports the kiln current data, kiln tail coal feed rate, raw meal feed rate, hoist current, CO concentration feedback from the C1 flue gas analyzer, nitrogen oxide concentration feedback from the C1 flue gas analyzer, oxygen concentration feedback from the C1 flue gas analyzer, converted nitrogen oxide concentration feedback from the chimney flue gas analyzer, and raw mill start and stop signals from the cement kiln DCS system; imports the converted nitrogen oxide concentration from the chimney flue gas analyzer; imports the actual ammonia flow data of the SNCR system; and imports the relevant parameters that are manually initially set. 00 Kiln condition judgment time interval,

[0204] The second step is data analysis. The data calculation and analysis module of the present invention includes calculations of kiln current, kiln tail coal feeding amount, raw meal feeding amount, C1 analyzer CO concentration, C1 analyzer NOx concentration fluctuation, chimney analyzer NOx concentration fluctuation, C1 and chimney NOx difference and coefficient of variation, and C1 analyzer NOx concentration.

[0205] 1. Main equation for kiln current calculation:

[0206] ① Kiln current

[0207] A kiln =ΣA kiln-i / T 00

[0208] A kiln Determine the kiln current (unit: ampere), A kiln-i T recorded in seconds 00 Kiln current during the period (unit: ampere), T 00 Kiln condition judgment time interval (unit: seconds).

[0209] ②ΔA kiln =A kiln -A kiln-1

[0210] ΔA kiln That is T00 A during the period kiln With the previous T 00 A during the period kiln The difference in amperes. kiln-1 Previous T 00 A during the period kiln .

[0211] 2. Calculation of coal feeding quantity at kiln tail:

[0212] ①B coal =ΣB coal-i / T 00

[0213] B coal Determine the amount of coal fed to the kiln tail (unit: tons / hour), B coal-i T recorded in seconds 00 The amount of coal fed to the kiln tail during the period (unit: tons / hour), T 00 Kiln condition judgment time interval (unit: seconds)

[0214] 3. Calculation of raw meal feeding amount:

[0215] ①B meal =ΣB meal-i / T 00

[0216] B meal Determine the kiln tail feeding amount (unit: tons / hour), B meall-i T recorded in seconds 00 Kiln tail feeding amount during the period (unit: tons / hour), T 00 Kiln condition judgment time interval (unit: seconds)

[0217] ②B meal =k meal *ΣA meal-i / T 00

[0218] When the feedback of the kiln tail feeding amount of some production lines is inaccurate, the hoist current is used to judge the kiln tail feeding amount. meal Determine the amount of coal fed to the kiln tail (unit: tons / hour), A meal-i T recorded in seconds 00 Hoist current during the period (unit: ampere), T 00 Kiln condition judgment time interval, k meal Correction coefficient for hoist current and kiln tail feeding amount.

[0219] 4. Main equation for calculating CO concentration of C1 analyzer:

[0220] ①C c1co =ΣCc1co-i / T 00

[0221] C c1co T recorded in seconds 00 The average CO concentration of the C1 analyzer during the period (unit: ppm), C c1co-i T recorded in seconds 00 C1 analyzer CO concentration during the time period (unit: ppm), T 00 Kiln condition judgment time interval (unit: seconds)

[0222] ②ΔC c1co =C c1co -C c1co-1

[0223] ΔC c1co That is T 00 C during the period c1co With the previous T 00 C during the period c1co The difference (unit: ppm). c1co-1 Previous T 00 C during the period c1co .

[0224] 5. Main equation for NOx concentration fluctuation of C1 analyzer:

[0225] ①C c1NOxlow =Min(C c1NOx-i )

[0226] C c1NOxlow T recorded in seconds 00 The minimum NOx concentration of C1 analyzer during the period (unit: mg / m 3 ), C c1NOx-i T recorded in seconds 00 C1 analyzer NOx concentration during the period

[0227] ②C c1NOxhigh =Max(C c1NOx-i )

[0228] C c1NOxhigh T recorded in seconds 00 The maximum NOx concentration of C1 analyzer during the period (unit: mg / m 3 ), C c1NOx-i T recorded in seconds 00 C1 analyzer NOx concentration during the period

[0229] ③C c1NOxΔ =C c1NOxhigh -C c1NOxlow

[0230] C c1NOxΔ00 Fluctuation value of NOx of C1 analyzer within the period (unit: mg / m 3 )

[0231] ④C c1NOxΔT＝ C c1NOxΔ / T 00

[0232] C c1NOxΔT In T 00 NOx fluctuation value of C1 analyzer within time (unit: mg / m 3 / s)

[0233] 6. Main equation for NOx concentration fluctuation of chimney analyzer:

[0234] ①C chNOxlow =Min(C chNOx-i )

[0235] C chNOxlow T recorded in seconds 00 The minimum NOx concentration of the chimney analyzer during the period (unit: mg / m 3 ), C chNOx-i T recorded in seconds 00 Chimney analyzer NOx concentration during the period

[0236] ②C chNOxhigh =Max(C chNOx-i )

[0237] C chNOxhigh T recorded in seconds 00 The maximum NOx concentration of the chimney analyzer during the period (unit: mg / m 3 ), C chNOx-i T recorded in seconds 00 Chimney analyzer NOx concentration during the period

[0238] ③C chNOxΔ =C chNOxhigh -C chNOxlow

[0239] C chNOxΔ T recorded in seconds 00 Fluctuation value of NOx of chimney analyzer during the period (unit: mg / m 3 )

[0240] ④C chNOxΔT＝ C chNOxΔ / T 00

[0241] C chNOxΔT In T 00NOx fluctuation value of chimney analyzer within a certain period of time (unit: mg / m 3 / s)

[0242] 7. Main equation for calculating the difference between C1 and stack NOx and coefficient of variation:

[0243] ①T3=T 30 +ΔT3

[0244] T3 is the lag time of the chimney analyzer compared to the C1 analyzer (unit: seconds), the manually set T 30 The lag time (in seconds) of the chimney analyzer compared to the C1 analyzer when the raw mill is running, and the manually set ΔT3 when the raw mill stops 30 The change in value (unit: second) is taken into account when the precise SNCR determines that the raw mill has stopped.

[0245] ②ΔC t =C chNOxt -C c1NOxt-T3

[0246] ΔC t The difference in NOx between the C1 analyzer and the chimney analyzer at time t (unit: mg / m 3 ), C c1NOxt-T3 The nitrogen oxide concentration of the C1 analyzer at time t-T3 (unit: mg / m 3 ), C chNOxt The nitrogen oxide concentration of the C1 analyzer at time t (unit: mg / m 3 ), the lag time of the T3 chimney analyzer compared to the C1 analyzer (in seconds).

[0247] ③ΔC tp =ΣΔC ti / T 00

[0248] ΔC ti From tT 00 ΔC at time t t (Unit: mg / m 3 , i=1~T 00 ), ΔC tp From tT 00 ΔC at time t t The average value (unit: mg / m 3 ).

[0249] ④ΔC tpn =ΣΔC tpi / n

[0250] ΔC tpi From ti*T 00 to t-(i-1)*T00 ΔC at time tp (Unit: mg / m 3 , i = 1 ~ n), n is the number of judgment cycles of the difference between C1 and chimney NOx and the coefficient of variation

[0251] ⑤C vt =ΔC tp / ΔC tpn

[0252] C vt is the coefficient of variation of the difference between C1 and stack NOx (dimensionless)

[0253] 8. Main equation for calculating target NOx concentration of C1 analyzer:

[0254] ①C c1NOxt-target＝ C chNOx-target +ΔC t

[0255] C1 analyzer from t to t+T 00 The target concentration of nitrogen oxides at the time (unit: mg / m 3 ), C chNOx-target Manually set chimney nitrogen oxide target emission concentration (unit: mg / m 3 ), ΔC t The difference in NOx between the C1 analyzer and the chimney analyzer at time t (unit: mg / m 3 ).

[0256] ②C c1NOx-average =Average(C c1NOx-i )

[0257] Average(): indicates the average value, C c1NOx-average tT recorded in seconds 00 Average NOx concentration of C1 analyzer at time t (unit: mg / m 3 ), C c1NOx-i T recorded in seconds 00 C1 analyzer NOx concentration during the period

[0258] ③ΔC c1NOx =C c1NOx-average -C c1NOxt-target

[0259] ΔC c1NOx The difference between the actual NOx concentration and the target NOx concentration (unit: mg / m 3 )

[0260] ④ΔC c1NOx-average =(C c1NOx-average -C c1NOx-average-1 ) / T00

[0261] ΔC c1NOx-average C1 analyzer NOx average concentration (unit: mg / m 3 / s) rate of change, C c1NOx-average tT recorded in seconds 00 Average NOx concentration of C1 analyzer at time t (unit: mg / m 3 ), C c1NOx-average-1 t-2*T recorded in seconds 00 To tT 00 Average NOx concentration of C1 analyzer at the time (unit: mg / m 3 )

[0262] The third step is performance evaluation. This module includes: kiln operation status evaluation, material feeding operation status evaluation, decomposition furnace operation status evaluation, C1 analyzer operation status evaluation, chimney analyzer operation status evaluation, and C1 and chimney analyzer corresponding operation status evaluation.

[0263] Table 1. Kiln operation status evaluation table

[0264] Serial number Evaluation conditions Evaluation results 1 <![CDATA[A kiln <A low ]]> The kiln system is producing abnormally. It is recommended to stop using the SNCR intelligent operation and maintenance system. 2 <![CDATA[A kiln ≥A low ]]> The kiln system is operating normally and the SNCR intelligent operation and maintenance system is running

[0265] A low Manually set kiln current lower limit (unit: ampere)

[0266] Table 2. Calciner operating status evaluation table

[0267] Serial number Evaluation conditions Evaluation results 1 <![CDATA[B coal <B coal-low ]]> The decomposition furnace is operating abnormally. It is recommended to disable the SNCR intelligent operation and maintenance system. 2 <![CDATA[B coal ≥B coal-low ]]> The decomposition furnace is operating normally and the SNCR intelligent operation and maintenance system is running

[0268] B coal-low Manually set lower limit of coal feeding at kiln tail (unit: tons / hour)

[0269] Table 3. Feeding operation status evaluation table

[0270] Serial number Evaluation conditions Evaluation results 1 <![CDATA[B meal <B meal-low ]]> The kiln system feeding is abnormal, it is recommended to stop using the SNCR intelligent operation and maintenance system 2 <![CDATA[B meal ≥B meal-low ]]> The kiln system is feeding normally and the SNCR intelligent operation and maintenance system is running

[0271] B meal-low Manually set lower limit of raw material feeding amount (unit: tons / hour)

[0272] Table 4. C1 analyzer operating status evaluation table

[0273]

[0274] ABS(): indicates absolute value, C c1NOxΔT-normal Manually set C1 analyzer NOx fluctuation value limit (unit: mg / m 3 / s)

[0275] Table 5. Chimney analyzer operating status evaluation table

[0276]

[0277] ABS(): indicates absolute value, C chNOxΔT-normal Manually set chimney analyzer NOx fluctuation value limit (unit: mg / m 3 / s)

[0278] Table 6. Evaluation table of corresponding operating status of C1 and chimney analyzers

[0279]

[0280] ABS(): indicates absolute value, C vt-normal Manually set C1 and chimney analyzer accuracy synchronization coefficient (dimensionless)

[0281] The fourth step is automatic control coupling. Performance evaluation determines the nitrogen oxide emissions of the cement kiln system. Using a rational algorithm coupled with the SNCR intelligent operation and maintenance system, the ammonia flow rate is intelligently optimized to achieve optimal denitrification. Details are as follows.

[0282] Table 7. Evaluation results

[0283]

[0284] When D r1 >ΔC c1NOx-average >-D r1 When the

[0285]

[0286]

[0287] D r1 , D r2 Manually set limit value of the change rate of the average NOx concentration of the C1 analyzer (unit: mg / m 3 / s), Er1, Er2, Er3 manually set the fluctuation limit of the average NOx concentration of the C1 flue gas analyzer (unit: mg / m 3 ), V0 actual ammonia flow rate (unit L / h), V1, V2, V3, V4, V5, V6 manually set ammonia flow rate change value of the precise SNCR system (unit L / h), K1 manually set CO concentration change factor, K2 manually set kiln current change factor, ΔC c1NOx For T 00 C during the period c1NOx With the previous T 00 C during the period c1NOxThe difference, ΔC c1co In T 00 C during the period c1co With the previous T 00 C during the period c1co The difference (unit: ppm), ΔA kiln That is T 00 A during the period kiln With the previous T 00 A during the period kiln The difference in amperes.

[0288] The compressed air flow calculation equation is calculated according to the gas-liquid ratio function provided by the spray gun manufacturer, and the calculation basis is the d 50 The particle size is 20-40μm.

[0289] Step 5: Loop Establishment: The data automatically adjusted by the cement kiln SNCR intelligent operation and maintenance system is returned to the data acquisition module, and step 2 is repeated, thus establishing an intelligent operation and maintenance loop.

[0290] The system is applied to a 2,500-ton cement clinker production line of a certain cement company. The ammonia consumption is reduced by 20% compared with when the system is not used, saving 1,043 tons of ammonia annually and reducing operating costs by 792,760 yuan.

[0291] Example 2

[0292] The same as Example 1, except that the limit value of the change rate of the average NOx concentration of the three C1 analyzers is set (unit: mg / m 3 / s)D r1 , D r2 , D r3 The manually set ammonia flow rate change value (unit: L / h) for the precise SNCR system has been increased to V1, V1', V2, and V2'. A more detailed gradient of the average NOx concentration change rate has been defined, which is more adaptable to fluctuations in cement production processes on some production lines.

[0293] The system was applied to a 5,000-ton cement clinker production line of a certain cement company. Ammonia consumption was reduced by 20% compared to the original system, saving 2,318 tons of ammonia annually and reducing operating costs by 1.76168 million yuan.

[0294] Example 3

[0295] The same as Example 1, except that the fluctuation limit of the average NOx concentration of the four C1 flue gas analyzers (unit: mg / m 3 )Er1, Er2, Er3, Er 4,, the manually set ammonia flow rate change value (unit L / h) of the precise SNCR system is increased to V3, V3', V4, V5, V5', V6, which divides the fluctuation of the average NOx concentration in more detail, and can better adapt to the fluctuation of cement production process in some production lines.

[0296] Example 4

[0297] It is basically the same as Example 1, except that K1 and K2 have different values ​​for different automatic control coupling situations, which can better adapt to fluctuations in cement production processes in some production lines.

[0298] Example 5

[0299] The same as Example 1, except that the main equation for calculating CO concentration of C1 analyzer, the main equation for NOx concentration fluctuation of C1 analyzer, the main equation for calculating NOx concentration fluctuation of chimney analyzer, the main equation for calculating the difference and coefficient of variation of NOx between C1 and chimney, and the main equation for calculating target NOx concentration of C1 analyzer all use independent judgment time intervals and are not combined with the main equation for calculating CO concentration of C1 analyzer.

[0300] The main equations for calculating kiln current, kiln tail coal feeding amount, and raw meal feeding amount are T 00 The kiln condition judgment time interval (unit: seconds) is consistent.

[0301] Example 6

[0302] This intelligent operation and maintenance system can be directly used in cement kiln SCR system, and the control logic and process are exactly the same as those of the SNCR system.

[0303] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of the claims.

Claims

1. A method for obtaining ammonia flow based on a rotor scale, characterized in that: At least: S1. When the raw material feeding amount is kept constant, the process of the rotor scale feeding amount of raw material is expressed by a waveform diagram; S2. Obtaining a large period of the waveform; S3. Divide the waveform of each large cycle into several small cycles, and the time interval of each small cycle is the same; S4. Take the maximum value of the positive peak of each small cycle; S5. Generate a trend line using the starting point of the large cycle, the maximum value of the positive wave peak, and the end point of the large cycle; S6, real-time ammonia flow rate = ammonia flow rate calculated by the initial algorithm + proportional coefficient X peak height; where: The proportional coefficient is the proportional relationship between the range of ammonia flow rate change and the height of the highest point in the large cycle; The ammonia flow rate calculated by the initial algorithm is: When ΔC c1NOx-average > D r2 or -D r2 >ΔC c1NOx-average Or Er3 < ΔC c1NOx When , the ammonia flow rate is the present value V0; When D r2 >Δ C c1NOx-average > D r1 When the ammonia flow rate is V0 + V1 + K1× ΔC c1co + K2×ΔA kiln ; When-D r1 >Δ C c1NOx-average > -D r2 When the ammonia flow rate is V0 - V2 + K1× ΔC c1co + K2×ΔA kiln ; When D r1 >Δ C c1NOx-average > -D r1 , and -Er3 < ΔC c1NOx < -Er2, the ammonia flow rate is V0 - V3 + K1×ΔC c1co + K2×ΔA kiln ; When D r1 >Δ C c1NOx-average > -D r1 , and -Er2 < ΔC c1NOx < -Er1, the ammonia flow rate is V0 - V4 + K1×ΔC c1co + K2×ΔA kiln ; When D r1 >Δ C c1NOx-average > -D r1 , and Er1 < ΔC c1NOx < Er2, the ammonia flow rate is V0 + V5 + K1×ΔC c1co + K2×ΔA kiln ; When D r1 >Δ C c1NOx-average > -D r1 , and Er2 < ΔC c1NOx < Er3, the ammonia flow rate is V0 + V6 + K1×ΔC c1co + K2×ΔA kiln ;in: D r1 The lower limit of the change rate of the average NOx concentration of the C1 flue gas analyzer is set manually, D r2 The upper limit of the change rate of the average NOx concentration of the C1 flue gas analyzer is set manually; ΔC c1NOx-average is the rate of change of the average NOx concentration of the C1 flue gas analyzer, ΔC c1NOx For T 00 C during the period c1NOx With the previous T 00 C during the period c1NOx Er1 is the manually set lower limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, Er2 is the manually set middle limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, Er3 is the manually set upper limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, V0 is the actual flow rate of ammonia water; V1, V2, V3, V4, V5, V6 are the manually set ammonia flow rate changes of the precise SNCR system; ΔC c1co For T 00 C during the period c1co With the previous T 00 C during the period c1co The difference between kiln T 00 A during the period kiln With the previous T 00 A during the period kiln K1 is the manually set CO concentration change influencing factor, and K2 is the manually set kiln current change influencing factor.

2. An ammonia flow acquisition module based on a rotor scale, characterized in that: include: The expression module uses a waveform diagram to express the process of the rotor scale adjusting the raw material feeding amount when the raw material feeding amount is kept constant. A large cycle acquisition module, which acquires the large cycle of the waveform; The small cycle acquisition module divides the waveform of each large cycle into several small cycles, and the time interval of each small cycle is the same; The maximum value acquisition module takes the maximum value of the positive peak of each small cycle; The trend module generates a trend line from the starting point of the large cycle, the maximum value of the positive peak, and the end point of the large cycle; Calculation module, real-time ammonia flow rate = ammonia flow rate calculated by the initial algorithm + proportional coefficient X peak height; where: The proportional coefficient is the proportional relationship between the range of ammonia flow rate change and the height of the highest point in the large cycle; The ammonia flow rate calculated by the initial algorithm is: When ΔC c1NOx-average > D r2 or -D r2 >ΔC c1NOx-average Or Er3 < ΔC c1NOx When , the ammonia flow rate is the present value V0; When D r2 >Δ C c1NOx-average > D r1 When the ammonia flow rate is V0 + V1 + K1× ΔC c1co + K2×ΔA kiln ; When-D r1 >Δ C c1NOx-average > -D r2 When the ammonia flow rate is V0 - V2 + K1× ΔC c1co + K2×ΔA kiln ; When D r1 >Δ C c1NOx-average > -D r1 , and -Er3 < ΔC c1NOx < -Er2, the ammonia flow rate is V0 - V3 + K1×ΔC c1co + K2×ΔA kiln ; When D r1 >Δ C c1NOx-average > -D r1 , and -Er2 < ΔC c1NOx < -Er1, the ammonia flow rate is V0 - V4 + K1×ΔC c1co + K2×ΔA kiln ; When D r1 >Δ C c1NOx-average > -D r1 , and Er1 < ΔC c1NOx < Er2, the ammonia flow rate is V0 + V5 + K1×ΔC c1co + K2×ΔA kiln ; When D r1 >Δ C c1NOx-average > -D r1 , and Er2 < ΔC c1NOx < Er3, the ammonia flow rate is V0 + V6 + K1×ΔC c1co + K2×ΔA kiln ;in: D r1 The lower limit of the change rate of the average NOx concentration of the C1 flue gas analyzer is set manually, D r2 The upper limit of the change rate of the average NOx concentration of the C1 flue gas analyzer is set manually; ΔC c1NOx-average is the rate of change of the average NOx concentration of the C1 flue gas analyzer, ΔC c1NOx For T 00 C during the period c1NOx With the previous T 00 C during the period c1NOx Er1 is the manually set lower limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, Er2 is the manually set middle limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, Er3 is the manually set upper limit of the NOx average concentration fluctuation of the C1 flue gas analyzer, V0 is the actual flow rate of ammonia water; V1, V2, V3, V4, V5, V6 are the manually set ammonia flow rate changes of the precise SNCR system; ΔC c1co For T 00 C during the period c1co With the previous T 00 C during the period c1co The difference between kiln T 00 A during the period kiln With the previous T 00 A during the period kiln K1 is the manually set CO concentration change influencing factor, and K2 is the manually set kiln current change influencing factor.

3. A cement SNCR intelligent operation and maintenance system, characterized in that: At least: Data acquisition module, used to obtain the operating data of the cement DCS system, the detection data of the preheater outlet flue gas analyzer, the detection data of the chimney flue gas analyzer and the manual initial setting parameters; The data calculation and analysis module receives the data from the acquisition module and performs data calculation and analysis; The performance evaluation module uses the data obtained by the data calculation and analysis module to evaluate the working status of the flue gas analyzer at the preheater outlet, evaluate and diagnose the operating status of the cement kiln system, and determine the current operating status of the cement kiln; The automatic control coupling module exchanges data with the performance evaluation module to predict the current optimal ammonia consumption and compressed air flow, thereby automatically adjusting the flow of ammonia and the flow of compressed air. The adjusted parameters are re-imported into the data acquisition module to establish a cycle; the flow of ammonia is realized based on the ammonia flow acquisition method of claim 1 or the ammonia flow acquisition module of claim 2.

4. The cement SNCR intelligent operation and maintenance system according to claim 3 is characterized by: The data calculation and analysis module includes: Current calculation module for calculating kiln current; Coal feeding amount calculation module for calculating the coal feeding amount at the kiln tail; A raw meal feed quantity calculation module for calculating the raw meal feed quantity; CO concentration calculation module for calculating CO concentration of C1 flue gas analyzer; C1 flue gas analyzer NOx concentration fluctuation calculation module for calculating C1 flue gas analyzer NOx concentration fluctuation; A chimney analyzer NOx concentration fluctuation calculation module for calculating the chimney analyzer NOx concentration fluctuation; A difference calculation module for calculating the NOx difference and coefficient of variation between the C1 flue gas analyzer and the chimney flue gas analyzer; C1 flue gas analyzer NOx concentration calculation module for calculating the NOx concentration of C1 flue gas analyzer; The performance evaluation module includes: Cement kiln system operation status assessment module, used for kiln operation status assessment, feeding operation status assessment, and calciner operation status assessment; Flue gas analyzer operating status evaluation module, used for C1 flue gas analyzer operating status evaluation, chimney analyzer operating status evaluation, and corresponding operating status evaluation of C1 flue gas analyzer and chimney analyzer; The automatic control coupling module includes: An ammonia flow calculation module for calculating the ammonia flow rate; Compressed air flow calculation module for calculating compressed air flow.

5. A cement SNCR intelligent operation and maintenance method, characterized in that: Utilize the cement SNCR intelligent operation and maintenance system described in claim 4 to complete the following steps: The first step is data collection, which includes the operating data of the cement DCS system, the detection data of the flue gas analyzer at the preheater outlet, the detection data of the chimney flue gas analyzer, and the manually set initial parameters; The second step is data calculation and analysis, which uses the real-time data obtained by the data acquisition module and combines it with the manually input parameters to perform data calculation and analysis; The third step is performance evaluation. Based on the data calculation and analysis results, the current operating status of the cement kiln is evaluated through various evaluation models to analyze the state of the cement kiln and select the appropriate SNCR control solution. The fourth step is automatic control coupling of the cement SNCR intelligent operation and maintenance system. The SNCR control solution obtained through performance evaluation is coupled with the nitrogen oxide production status through an algorithm to automatically optimize the SNCR control, so that the cement SNCR intelligent operation and maintenance system reaches the optimal working state. The fifth step is to establish a loop. Through automatic optimization and adjustment by the cement SNCR intelligent operation and maintenance system, the data is returned to the data acquisition module to repeat the second step, thus establishing an intelligent operation and maintenance loop.

6. The cement SNCR intelligent operation and maintenance method according to claim 5, characterized in that: The operating data of the cement DCS system include: kiln current, kiln tail coal feeding amount, raw meal feeding amount, hoist current, CO concentration fed by C1 flue gas analyzer, nitrogen oxide concentration fed by C1 flue gas analyzer, oxygen concentration fed by C1 flue gas analyzer, and converted nitrogen oxide concentration fed by chimney flue gas analyzer; the operating data of the cement SNCR intelligent operation and maintenance system include: adjustment of ammonia flow V0; In the second step, the data calculation and analysis includes: Calculate kiln current calculation; Calculate the amount of coal fed to the kiln tail; Calculate raw meal feed quantity; Calculate the CO concentration of the C1 flue gas analyzer; Calculate the NOx concentration fluctuation of C1 flue gas analyzer; Calculate the NOx concentration fluctuations of the stack analyzer; Calculate the difference and coefficient of variation of NOx between C1 flue gas analyzer and chimney flue gas analyzer; Calculate the NOx concentration of the C1 flue gas analyzer.

7. The cement SNCR intelligent operation and maintenance method according to claim 5, characterized in that: In the third step, the performance evaluation includes: Evaluate the operating status of the cement kiln system: including kiln operating status evaluation, feeding operating status evaluation, and calciner operating status evaluation; Evaluate the operating status of the flue gas analyzer: including the operating status evaluation of the C1 flue gas analyzer, the operating status evaluation of the chimney analyzer, and the corresponding operating status evaluation of the C1 flue gas analyzer and the chimney analyzer.

8. The cement SNCR intelligent operation and maintenance method according to claim 5, characterized in that: In the fourth step, the automatic control coupling of the cement SNCR intelligent operation and maintenance system includes: Calculate ammonia flow rate; Calculate compressed air flow.

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