A method for optimizing control of coal pressure at a cement kiln head

Abstract

The application discloses a cement kiln head coal pressure optimization control method, comprising: 1) limit condition judgment, including kiln condition index limit, kiln current limit, secondary air temperature limit and ammonia water flow trend limit; 2) recommended value calculation, the recommended value of the influence of related parameters on kiln output is calculated through the limit conditions of each parameter preliminarily determined in the previous step; 3) recommended value selection, the recommended value selection result is obtained according to the kiln condition comprehensive index recommendation, kiln current size recommendation, secondary air temperature recommendation, head and tail coal proportion, environment temperature recommendation, kiln tail flue NO x recommended priority, the recommended value selection is carried out from front to back, and the recommended value selection result is obtained; 4) calculation of head coal recommended value and adjustment of cement kiln head coal pressure, the head coal feeding amount is adjusted according to the head coal recommended value, and the formula of the head coal recommended value is: head coal recommended value = current set value + recommended value selection result. The application can timely adjust the kiln head coal feeding pressure, so that the temperature at each point in the kiln is in a relatively stable state.

Description

Technical Field

[0001] This invention belongs to the field of cement production technology, specifically relating to a method for optimizing and controlling coal pressure at the cement kiln head. Background Technology

[0002] Cement is a fundamental raw material in economic construction. However, the continuous increase in cement production has also led to high energy consumption. Applying new dry-process cement production technology and continuously optimizing production control strategies is an important way for the cement industry to achieve energy conservation and emission reduction. The kiln head coal feeding system is a crucial component of the new dry-process cement clinker calcination system.

[0003] Coal feeding at the kiln head is a crucial process step in clinker calcination that plays a decisive role in clinker quality and is vital to the operational stability of the calcination system. The stability of the coal feeding affects the temperature and position of different zones within the kiln. Unstable kiln temperatures can cause the liquid phase to shift, leading to condensation on the kiln lining due to temperature fluctuations and increasing the probability of forming a thick kiln lining, thus creating an opportunity for ring formation. Coal feeding is the most important factor affecting kiln temperature. Simultaneously, the influence of ambient temperature, material quality, and secondary air temperature must be considered. Parameters such as kiln current, comprehensive kiln condition indicators, and NOx content in the kiln tail flue must be referenced to adjust the coal feeding pressure at the kiln head in a timely manner. Maintaining a relatively stable temperature at all points within the kiln is extremely important for optimizing clinker calcination and extending the service life of the main equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a method for optimizing and controlling coal pressure at the kiln head in cement kilns, which aims to adjust the coal feeding pressure at the kiln head in a timely manner so that the temperature at various points inside the kiln remains relatively stable.

[0005] The method for optimizing and controlling coal pressure at the cement kiln head includes the following steps:

[0006] 1) Judgment of limiting conditions, including kiln condition index limits, kiln current limits, secondary air temperature limits, and ammonia water flow rate trend limits;

[0007] 2) Calculation of recommended values: Based on the constraints of the parameters initially determined in the previous step, the recommended values ​​for the impact of relevant parameters on kiln output are calculated. These recommended values ​​include recommendations for comprehensive kiln condition indicators, kiln current, secondary air temperature, ambient temperature, and NO0 in the kiln tail flue. X recommend;

[0008] 3) Recommended values ​​are selected based on comprehensive kiln condition indicators, recommended kiln current, recommended secondary air temperature, head and tail coal ratio, recommended ambient temperature, and kiln tail smoke chamber NO. X The recommendation priority is determined by selecting recommended values ​​from the beginning to the end, resulting in the recommended value selection results;

[0009] 4) Calculate the recommended head coal value and adjust the head coal pressure of the cement kiln. This step adjusts the head coal feed rate based on the recommended head coal value. The formula for the recommended head coal value is: Recommended head coal value = Current set value + Recommended value selection result.

[0010] Preferably, step 1) specifically includes:

[0011] 1.1) Limitation of kiln condition comprehensive index: When the free calcium in the clinker leaving the kiln is less than the set lower limit of free calcium and the kiln condition comprehensive index is 0, it is not recommended to increase the set value;

[0012] 1.2) Kiln current limit: When the kiln current is greater than the kiln current set value / 2 + the kiln current lower limit / 2, it is determined that the kiln current is at the high limit, and it is not recommended to increase the set value; conversely, it is not recommended to decrease the set value.

[0013] 1.3) Secondary air temperature limit: When the secondary air temperature is less than the secondary air temperature setting value - 50, it is determined that the secondary air temperature is low and it is not recommended to decrease the setting value. When the secondary air temperature is greater than the secondary air temperature setting value + 50, it is determined that the secondary air temperature is high and it is not recommended to increase the setting value.

[0014] 1.4) Ammonia flow rate trend limit: If the ammonia flow rate three minutes ago minus the ammonia flow rate thirty minutes ago is less than -200, it is determined that the ammonia flow rate is decreasing significantly, and it is not recommended to decrease the set value; if the ammonia flow rate three minutes ago minus the ammonia flow rate thirty minutes ago is greater than 200, it is determined that the ammonia flow rate is increasing significantly, and it is not recommended to increase the set value.

[0015] Preferably, the calculation method for the comprehensive kiln condition index in step 1.1) is as follows:

[0016] 1.1.1) Calculation of kiln temperature index, specifically including:

[0017] 1.1.1.1) Calculation of the score and predicted score, and the influencing factors for applying this score and predicted score include: fire observation, smoke room NO. X Kiln current, secondary air temperature, ammonia flow rate, NO in the middle of the decomposition furnace X ;

[0018] 1.1.1.2) Weight calculation: Calculate the weight of each of the above influencing factors;

[0019] 1.1.1.3) Calculation of kiln temperature index, the specific formula includes:

[0020] Kiln temperature index = Observation weight × Observation score + Kiln current weight × Kiln current score + Secondary air temperature weight × Secondary air temperature score + Ammonia flow rate weight × Ammonia flow rate score + NO X Weight × NO X Score;

[0021] 1.1.1.4) Recommended calculation method for kiln temperature index, the specific formula includes:

[0022] Recommended kiln temperature index = (Fire observation weight × Fire observation prediction score) + (Kiln current weight × Kiln current prediction score) + (Secondary air temperature weight × Secondary air temperature prediction score) + (Ammonia flow rate weight × Ammonia flow rate prediction score) + NO X Weight × NO X Predicted score;

[0023] 1.1.2) Calculation of free calcium compensation;

[0024] Let the current free calcium be CaO(0) and the target free calcium be CaO(i). Let FL_PV_list be an array of the updated free calcium values ​​over the past three hours, containing three values. Starting from the current free calcium, the three values ​​are CaO(1), CaO(2), and CaO(3) in chronological order. Thus:

[0025] Deviation value 1: err1 = CaO(1) - CaO(i). If err1 is within the range of ±0.1, then err1 is 0.

[0026] Deviation value 2: err2=CaO(1)-CaO(2);

[0027] Deviation value 3: err3=CaO(1)-CaO(2)-(CaO(2)-CaO(3));

[0028] Based on the above formula, the comprehensive deviation value delta is further calculated as -kp*(errl+err2*ki+err3*kd), where the parameter kp is generally -0.3, the parameter ki is generally -0.2, and the parameter kd is generally -0.05.

[0029] The formula for the free calcium compensation value TEMP_EST_SP is:

[0030] FL_COM=min(0.5,max(-0.5,delta));

[0031] 1.1.3) Calculation of comprehensive kiln condition index, the specific formula is as follows:

[0032] The initial comprehensive kiln condition index = weight_temp_rec * recommended value of kiln temperature index + kiln temperature index, and the parameter weight_temp_rec is generally -1;

[0033] After free calcium compensation, the comprehensive kiln condition index = min(1, max(-1, initial comprehensive kiln condition index + FL_COM*(1-absolute value of kiln temperature index))).

[0034] Preferably, the specific formulas for the scores and predicted scores of each influencing factor in step 1.1.1.1) are as follows:

[0035] Predicted value = Current value + Gain × Sampling period;

[0036] When the feedback value is greater than the set value, the score is calculated as: (feedback value - set value) / (set upper limit - set value).

[0037] When the feedback value is less than the set value, the score = (feedback value - set value) / (set value - set lower limit);

[0038] When the predicted value is greater than the set value, the prediction score is calculated as: predict = (predicted value - set value) / (set upper limit - set value).

[0039] When the predicted value is less than the set value, the prediction score is calculated as: predict = (predicted value - set value) / (set value - set lower limit).

[0040] Preferably, the weighting formula for each influencing factor in step 1.1.1.2) specifically includes:

[0041] Fire observation weight = 0.2 × (1 - fire observation status);

[0042] Kiln current weight = 0.03;

[0043] Secondary air temperature weight = 0.17 × (1 - secondary air temperature state);

[0044] Ammonia flow rate weight = 0.3;

[0045] NO X Weight = 0.3 × (1 - kiln tail smoke chamber NO) X (State) + 0.3 × kiln tail smoke chamber NO X State × (1 - NO in the middle of the decomposition furnace) X state).

[0046] Preferably, step 2) specifically includes:

[0047] 2.1) Recommendation of comprehensive kiln condition index: Based on the comprehensive kiln condition index, it is determined whether to add or reduce coal. The formula for the recommended value of adding coal is: Recommended value = max[0, -0.2 × comprehensive kiln condition index], while the formula for the recommended value of reducing coal is: Recommended value = -0.2 × comprehensive kiln condition index;

[0048] 2.2) Recommended kiln current: If either of the following two conditions is met, the kiln current is considered high and coal consumption needs to be reduced;

[0049] Condition 1: The rolling average value of the kiln current from the first 20 minutes to the first 10 minutes is greater than the upper limit of the kiln current, and the rolling average value of the kiln current from the first 10 minutes is greater than the upper limit of the kiln current + 20, and the kiln skin shedding condition is less than 0.6.

[0050] Condition 2: The rolling average value of the kiln current in the first 10 minutes is greater than the upper limit of the kiln current, and the kiln scabbing condition is ≥0.6.

[0051] The formula for the recommended value of coal reduction is: Recommended value = -0.1 × (1.5 + (rolling average value of kiln current in the first 10 minutes - lower limit of kiln current - 60) / 80);

[0052] 2.3) Recommended Secondary Air Temperature: If the secondary air temperature is greater than the upper limit of the secondary air temperature, it is determined that the secondary air temperature is high and coal consumption needs to be reduced. The formula for the recommended coal consumption reduction value is: Recommended value = -0.1 × (secondary air temperature - upper limit of secondary air temperature) / 50;

[0053] 2.4) Recommended ambient temperature: The formula for the recommended value of adjusting the coal feed rate at the kiln head based on the ambient temperature is: Recommended value = Head coal pressure set value - (273 + Ambient temperature) / (273 + Ambient temperature one minute ago) × Head coal pressure set value;

[0054] 2.5) Kiln tail smoke chamber NO X Recommendation: When the NOx value of the kiln tail smoke chamber is - kiln tail smoke chamber NO X When the recommended value is >100, the formula for adjusting the coal feed rate at the kiln head is: Recommended value = min(-(kiln tail smoke chamber NO)) X Value - Kiln Tail Smoke Chamber NO X Recommended value: (-100) × 0.001, 0);

[0055] When the NOx value in the kiln tail smoke chamber is less than the NO value in the kiln tail smoke chamber X When the recommended value is <-100, the formula for adjusting the coal feed rate at the kiln head is: Recommended value = max(-(kiln tail smoke chamber NO) X Value - Kiln Tail Smoke Chamber NO X Recommended value (+100) × 0.001, 0).

[0056] Preferably, step 2.1) recommending comprehensive kiln condition indicators specifically includes:

[0057] 2.1.1) If any of the following three conditions are met, the kiln condition is judged to be poor and coal needs to be added;

[0058] Condition 1: The brightness of the fire observed on the screen is less than the lower limit of the brightness of the fire observed on the screen, and the decomposition furnace has good performance;

[0059] Condition 2: The overall kiln condition index is < -0.2, and the decomposition furnace performance is good;

[0060] Condition 3: Overall kiln condition index < 0.4;

[0061] 2.1.2) If either of the following two conditions is met, the kiln condition is considered good, and coal reduction is required;

[0062] Condition 1: The comprehensive index of kiln condition is >0.2, and the actual head-to-tail coal ratio is <optimal head-to-tail coal ratio -0.01;

[0063] Condition 2: The CO at the preheater outlet is greater than the set value of the CO at the preheater outlet, and the comprehensive index of kiln condition is greater than 0.2. At the same time, 2 × free calcium in the clinker leaving the kiln is less than the lower limit of free calcium in the clinker leaving the kiln plus the set value of free calcium in the clinker leaving the kiln.

[0064] The present invention has the following advantages:

[0065] 1. This scheme is based on thermal principles and utilizes comprehensive kiln condition indicators, kiln current, secondary air temperature, head and tail coal ratio, raw material feedforward, and ambient temperature to establish a soft measurement system for kiln head coal compensation. Combined with data such as kiln head coal feeding pressure and kiln main transmission current, a comprehensive kiln head coal control scheme is considered. This allows for determining the approximate range of kiln temperature to be controlled based on the kiln current, and deciding whether to increase or decrease the head coal supply. Furthermore, it considers the NO₂ in the kiln tail flue. X The effects of kiln current, secondary air temperature, kiln condition indicators, head and tail coal feeding ratio, and ambient temperature can be used to indirectly calculate the head coal compensation amount. This scheme adjusts the kiln head coal feeding pressure in a timely manner to maintain stable temperatures at various points within the kiln. Attached Figure Description

[0066] Fig. 1 This is a flowchart of a method for optimizing and controlling coal pressure at the head of a cement kiln according to the present invention.

[0067] Fig. 2 This is a flowchart illustrating the specific process for calculating the recommended value of head coal in this invention. Detailed Implementation

[0068] The following detailed description of the embodiments, with reference to the accompanying drawings, will further illustrate the specific implementation of the present invention, in order to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0069] like Figs. 1-2 As shown, the present invention provides a method for optimizing and controlling the coal pressure at the head of a cement kiln, comprising the following steps.

[0070] 1) Determine the limiting conditions.

[0071] This step, based on parameters such as NOx in the tail gas chamber, kiln current, secondary air temperature, kiln condition indicators, head coal to tail coal ratio, and ambient temperature, combined with actual operating conditions, determines whether these parameters are instructive for changes in head coal consumption. This step specifically includes...

[0072] 1.1) Limitation of kiln condition comprehensive index: When the free calcium in the clinker leaving the kiln is less than the set lower limit of free calcium and the kiln condition comprehensive index is 0, it is not recommended to increase the set value.

[0073] The calculation method for the comprehensive kiln condition index is as follows.

[0074] 1.1.1) Calculation of kiln temperature index, specifically including.

[0075] 1.1.1.1) Calculation of the score and predicted score, and the influencing factors for applying this score and predicted score include: fire observation, smoke room NO. X Kiln current, secondary air temperature, ammonia flow rate, NO in the middle of the decomposition furnace X The specific formula is as follows.

[0076] Predicted value = Current value + Gain × Sampling period.

[0077] When the feedback value is greater than the set value, the score is calculated as (feedback value - set value) / (set upper limit - set value).

[0078] When the feedback value is less than the set value, the score is calculated as (feedback value - set value) / (set value - set lower limit).

[0079] When the predicted value is greater than the set value, the prediction score is calculated as: predict = (predicted value - set value) / (set upper limit - set value).

[0080] When the predicted value is less than the set value, the prediction score is calculated as: predict = (predicted value - set value) / (set value - set lower limit).

[0081] 1.1.1.2) Weight calculation, the specific formula for the weight of each influencing factor includes.

[0082] Fire observation weight = 0.2 × (1 - fire observation status).

[0083] Kiln current weight = 0.03.

[0084] Secondary air temperature weight = 0.17 × (1 - secondary air temperature state).

[0085] Ammonia flow rate weight = 0.3.

[0086] NO X Weight = 0.3 × (1 - kiln tail smoke chamber NO) X (State) + 0.3 × kiln tail smoke chamber NO X State × (1 - NO in the middle of the decomposition furnace) X state).

[0087] 1.1.1.3) Calculation of kiln temperature index, the specific formula includes.

[0088] Kiln temperature index = Observation weight × Observation score + Kiln current weight × Kiln current score + Secondary air temperature weight × Secondary air temperature score + Ammonia flow rate weight × Ammonia flow rate score + NO X Weight × NO X Score.

[0089] 1.1.1.4) Recommended calculation method for kiln temperature index, including specific formula.

[0090] Recommended kiln temperature index = (Fire observation weight × Fire observation prediction score) + (Kiln current weight × Kiln current prediction score) + (Secondary air temperature weight × Secondary air temperature prediction score) + (Ammonia flow rate weight × Ammonia flow rate prediction score) + NO X Weight × NO X Predicted score.

[0091] 1.1.2) Calculation of free calcium compensation;

[0092] Let the current free calcium be CaO(0) and the target free calcium be CaO(i). Let FL_PV_list be an array of the updated free calcium values ​​over the past three hours, containing three values. Starting from the current free calcium, the three values ​​are CaO(1), CaO(2), and CaO(3) in chronological order. Thus:

[0093] Deviation value 1: err1 = CaO(1) - CaO(i). If err1 is within the range of ±0.1, then err1 is 0.

[0094] Deviation value 2: err2=CaO(1)-CaO(2);

[0095] Deviation value 3: err3=CaO(1)-CaO(2)-(CaO(2)-CaO(3));

[0096] Based on the above formula, the comprehensive deviation value delta is further calculated as -kp*(err1+err2*ki+err3*kd), where the parameter kp is generally -0.3, the parameter ki is generally -0.2, and the parameter kd is generally -0.05.

[0097] The formula for the free calcium compensation value TEMP_EST_SP is:

[0098] FL_COM=min(0.5,max(-0.5,de1ta));

[0099] 1.1.3) Calculation of comprehensive kiln condition index, the specific formula is as follows:

[0100] The initial comprehensive kiln condition index = weight_temp_rec * recommended value of kiln temperature index + kiln temperature index, and the parameter weight_temp_rec is generally -1;

[0101] After free calcium compensation, the comprehensive kiln condition index = min(1, max(-1, initial comprehensive kiln condition index + FL_COM*(1-absolute value of kiln temperature index))).

[0102] 1.2) Kiln current limit: When the kiln current is greater than the kiln current setting value / 2 + the kiln current lower limit / 2, it is determined that the kiln current is at the high limit, and it is not recommended to increase the setting value; conversely, it is not recommended to decrease the setting value.

[0103] 1.3) Secondary air temperature limit: When the secondary air temperature is less than the secondary air temperature setting value - 50, it is determined that the secondary air temperature is low and it is not recommended to decrease the setting value. When the secondary air temperature is greater than the secondary air temperature setting value + 50, it is determined that the secondary air temperature is high and it is not recommended to increase the setting value.

[0104] 1.4) Ammonia flow rate trend limit: If the ammonia flow rate three minutes ago minus the ammonia flow rate thirty minutes ago is less than -200, it is determined that the ammonia flow rate is decreasing significantly, and it is not recommended to decrease the set value; if the ammonia flow rate three minutes ago minus the ammonia flow rate thirty minutes ago is greater than 200, it is determined that the ammonia flow rate is increasing significantly, and it is not recommended to increase the set value.

[0105] 2) Calculation of recommended values.

[0106] This step calculates recommended values ​​for the impact of relevant parameters on the head coal based on the aforementioned parameters such as NOx in the tail gas chamber, kiln current, secondary air temperature, kiln condition indicators, head coal to tail coal ratio, and ambient temperature. Specifically, these values ​​include...

[0107] 2.1) Recommended comprehensive kiln condition indicators, including the following:

[0108] 2.1.1) If any of the following three conditions are met, the kiln condition is judged to be poor and coal needs to be added.

[0109] Condition 1: The brightness of the fire observed on the screen is less than the lower limit of the brightness of the fire observed on the screen, and the decomposition furnace has good performance.

[0110] Condition 2: The comprehensive index of kiln condition is less than -0.2, and the performance of the decomposition furnace is good.

[0111] Condition 3: The comprehensive index of kiln condition is <0.4.

[0112] The formula for the recommended coal addition value is: Recommended value = max[0, -0.2 × kiln condition comprehensive index].

[0113] 2.1.2) If either of the following two conditions is met, the kiln condition is considered good and coal reduction is required.

[0114] Condition 1: The comprehensive index of kiln condition is greater than 0.2, and the actual head-to-tail coal ratio is less than the optimal head-to-feed ratio - 0.01.

[0115] Condition 2: The CO at the preheater outlet is greater than the set value of the CO at the preheater outlet, and the comprehensive index of kiln condition is greater than 0.2. At the same time, 2 × free calcium in the clinker leaving the kiln is less than the lower limit of free calcium in the clinker leaving the kiln plus the set value of free calcium in the clinker leaving the kiln.

[0116] The formula for the recommended value of coal reduction is: Recommended value = -0.2 × kiln condition comprehensive index.

[0117] 2.2) Recommended kiln current.

[0118] If either of the following two conditions is met, the kiln current is considered to be high, and coal production needs to be reduced.

[0119] Condition 1: The rolling average value of the kiln current from the first 20 minutes to the first 10 minutes is greater than the upper limit of the kiln current, and the rolling average value of the kiln current from the first 10 minutes is greater than the upper limit of the kiln current + 20, and the kiln skin shedding condition is less than 0.6.

[0120] Condition 2: The rolling average value of the kiln current in the first 10 minutes is greater than the upper limit of the kiln current, and the kiln scabbing condition is ≥0.6.

[0121] The formula for the recommended coal reduction value is: Recommended value = -0.1 × (1.5 + (rolling average value of kiln current in the first 10 minutes - lower limit of kiln current - 60) / 80).

[0122] 2.3) Recommended secondary air temperature.

[0123] If the secondary air temperature exceeds the upper limit of the secondary air temperature, it is determined that the secondary air temperature is high and coal consumption needs to be reduced. The recommended value for coal consumption reduction is calculated as follows: Recommended value = -0.1 × (secondary air temperature - upper limit of secondary air temperature) / 50.

[0124] 2.4) Recommended ambient temperature.

[0125] The formula for adjusting the coal feed rate at the kiln head based on the ambient temperature is: Recommended value = Head coal pressure set value - (273 + Ambient temperature) / (273 + Ambient temperature one minute ago) × Head coal pressure set value.

[0126] 2.5) Kiln tail smoke chamber NO X recommend.

[0127] When the NOx value in the kiln tail smoke chamber is less than the NO value in the kiln tail smoke chamber X When the recommended value is >100, the formula for adjusting the coal feed rate at the kiln head is: Recommended value = min(-(kiln tail smoke chamber NO)) X Value - Kiln Tail Smoke Chamber NO X Recommended value: (-100) × 0.001, 0);

[0128] When the NOx value in the kiln tail smoke chamber is less than the NO value in the kiln tail smoke chamber XWhen the recommended value is <-100, the formula for adjusting the coal feed rate at the kiln head is: Recommended value = max(-(kiln tail smoke chamber NO) X Value - Kiln Tail Smoke Chamber NO X Recommended value (+100) × 0.001, 0).

[0129] 3) Recommended value selection.

[0130] Based on recommendations for comprehensive kiln condition indicators, kiln current, secondary air temperature, head and tail coal ratio, ambient temperature, and kiln tail smoke chamber NO... X The recommendation priority is determined by selecting the recommended values ​​from the beginning to the end, resulting in the recommended value selection results.

[0131] 4) Calculate the recommended head coal value and adjust the head coal pressure of the cement kiln.

[0132] This step adjusts the amount of coal fed to the head coal based on the recommended head coal value. The formula for the recommended head coal value is: Recommended head coal value = Current set value + Recommended value selection result.

[0133] The adjustment process requires maintaining stable temperatures at all points within the kiln and ensuring good overall kiln condition indicators. Coal calorific value, ambient temperature, and material quality are considered interfering factors. This method detects and determines the parameters related to these interfering factors, and then calculates and selects recommended values ​​for the first coal feed based on the overall kiln condition indicators and various related parameters. In step 4), the first coal feed rate input to the cement kiln is adjusted based on the final recommended value determined in the previous step.

[0134] The specific adjustment method for the first coal feed amount includes: simultaneously calculating the first coal feeding pressure and kiln current as controlled variables through the first coal feed amount, and realizing the specific adjustment of the first coal feed amount based on the calculation results.

[0135] The comprehensive kiln condition index calculation method adopted in this scheme comprehensively considers factors that mainly affect the cement kiln condition, such as fire observation, NOx in the flue, kiln current, secondary air temperature, ammonia flow rate, and NOx in the middle of the decomposer. This allows the generated comprehensive kiln condition index to effectively reflect the actual production situation of the cement kiln. Consequently, this scheme can accurately determine whether to increase or decrease the initial coal feed rate based on the actual parameters of the above factors, and can accurately calculate the compensation amount for the initial coal feed rate, thus improving the accuracy of the initial coal feed rate adjustment. Furthermore, this scheme selects recommended values ​​for different factors with the correct priority, making the determination of the initial coal feed rate adjustment more reasonable and reliable.

[0136] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for optimizing and controlling coal pressure at the head of a cement kiln, characterized by comprising the following steps: 1) Judgment of limiting conditions, including kiln condition comprehensive index limits, kiln current limits, secondary air temperature limits, and ammonia water flow trend limits; 2) Calculation of recommended values: Based on the constraints of the parameters initially determined in the previous step, the recommended values ​​for the impact of relevant parameters on kiln output are calculated. These recommended values ​​include recommendations for comprehensive kiln condition indicators, kiln current, secondary air temperature, ambient temperature, and NO0 in the kiln tail flue. X recommend; 3) Recommended values ​​are selected based on comprehensive kiln condition indicators, recommended kiln current, recommended secondary air temperature, head and tail coal ratio, recommended ambient temperature, and kiln tail smoke chamber NO. X The recommendation priority is determined by selecting recommended values ​​from the beginning to the end, resulting in the recommended value selection results; 4) Calculate the recommended head coal value and adjust the head coal pressure of the cement kiln. This step adjusts the head coal feed rate based on the recommended head coal value. The formula for the recommended head coal value is: Recommended head coal value = Current set value + Recommended value selection result; Step 1) specifically includes: 1.1) Kiln condition comprehensive index limit: When the free calcium in the clinker leaving the kiln is less than the set lower limit of free calcium and the kiln condition comprehensive index is 0, it is not recommended to increase the set value; 1.2) Kiln current limit: When the kiln current is greater than the kiln current set value / 2 + the kiln current lower limit / 2, it is determined that the kiln current is at the high limit and it is not recommended to increase the set value; conversely, it is not recommended to decrease the set value. 1.3) Secondary air temperature limit: When the secondary air temperature is less than the secondary air temperature setting value - 50, it is determined that the secondary air temperature is low and it is not recommended to decrease the setting value. When the secondary air temperature is greater than the secondary air temperature setting value + 50, it is determined that the secondary air temperature is high and it is not recommended to increase the setting value. 1.4) Ammonia flow rate trend limit: If the ammonia flow rate three minutes ago - the ammonia flow rate thirty minutes ago < -200, it is judged that the ammonia flow rate is decreasing significantly, and it is not recommended to decrease the set value; if the ammonia flow rate three minutes ago - the ammonia flow rate thirty minutes ago > 200, it is judged that the ammonia flow rate is increasing significantly, and it is not recommended to increase the set value. The calculation method for the comprehensive kiln condition index in step 1.1) is as follows: 1.1.1) Calculation of kiln temperature index, specifically including: 1.1.1.1) Calculation of the score and predicted score, influencing factors for which the score and predicted score are applied include: fire observation, smoke room NO. X Kiln current, secondary air temperature, ammonia flow rate, NO in the middle of the decomposition furnace X ; 1.1.1.2) Weight calculation: Calculate the weight of each of the above influencing factors; 1.1.1.3) Calculation of kiln temperature index, the specific formula includes: Kiln temperature index = Observation weight × Observation score + Kiln current weight × Kiln current score + Secondary air temperature weight × Secondary air temperature score + Ammonia flow rate weight × Ammonia flow rate score + NO X Weight × NO X Score; 1.1.1.4) Recommended calculation method for kiln temperature index, the specific formula includes: Recommended kiln temperature index = (Fire observation weight × Fire observation prediction score) + (Kiln current weight × Kiln current prediction score) + (Secondary air temperature weight × Secondary air temperature prediction score) + (Ammonia flow rate weight × Ammonia flow rate prediction score) + NO X Weight × NO X Predicted score; 1.1.2) Calculation of free calcium compensation; Let the current free calcium be CaO(0) and the target free calcium be CaO(i). Let FL_PV_list be an array of the updated free calcium values ​​over the past three hours, containing three values. Starting from the current free calcium, the three values ​​are CaO(1), CaO(2), and CaO(3) in chronological order. Thus: Deviation value 1: err1 = CaO(1) - CaO(i). If err1 is within the range of ±0.1, then err1 is 0. Deviation value 2: err2 = CaO(1) - CaO(2); Deviation value 3: err3 = CaO(1) - CaO(2) - (CaO(2) - CaO(3)); Based on the above formula, the comprehensive deviation value delta is calculated as: delta = -kp*(err1+err2*ki+err3*kd), where... The parameter kp is -0.3, the parameter ki is -0.2, and the parameter kd is -0.05; The formula for the free calcium compensation value TEMP_EST_SP is: FL_COM= min(0.5,max(-0.5,delta)); 1.1.3) Calculation of comprehensive kiln condition index, the specific formula is as follows: The initial comprehensive kiln condition index = weight_temp_rec * recommended kiln temperature index + kiln temperature index, with the parameter weight_temp_rec being -1; After free calcium compensation, the comprehensive kiln condition index = min(1,max(-1, initial comprehensive kiln condition index + FL_COM * (1 - absolute value of kiln temperature index))).

2. The method for optimizing and controlling coal pressure at the head of a cement kiln according to claim 1, characterized in that: The specific formulas for the scores and predicted scores of each influencing factor in step 1.1.1.1) are as follows: Predicted value = Current value + Gain × Sampling period; When the feedback value is greater than the set value, the score is calculated as (feedback value - set value) / (set upper limit - set value). When the feedback value is less than the set value, the score is calculated as (feedback value - set value) / (set value - lower limit). When the predicted value is greater than the set value, the prediction score is calculated as: predict = (predicted value - set value) / (set upper limit - set value). When the predicted value is less than the set value, the prediction score is calculated as: predict = (predicted value - set value) / (set value - set lower limit).

3. The method for optimizing and controlling coal pressure at the head of a cement kiln according to claim 2 or 1, characterized in that: The specific weighting formulas for each influencing factor in step 1.1.1.2) include: Fire observation weight = 0.2 × (1 - fire observation status); Kiln current weight = 0.03; Secondary air temperature weight = 0.17 × (1 - secondary air temperature status); Ammonia water flow rate weight = 0.3; NO X Weight = 0.3 × (1 - kiln tail smoke chamber NO) X (Status) + 0.3 × Kiln Tail Smoke Chamber NO X State × (1 - NO in the middle of the decomposition furnace) X state).

4. The method for optimizing and controlling coal pressure at the head of a cement kiln according to claim 1, characterized in that: Step 2) specifically includes: 2.1) Recommendation of comprehensive kiln condition index: Determine whether to add or reduce coal based on the comprehensive kiln condition index. The formula for the recommended value of adding coal is: Recommended value = max[0, -0.2 × comprehensive kiln condition index], while the formula for the recommended value of reducing coal is: Recommended value = -0.2 × comprehensive kiln condition index; 2.2) Recommended kiln current level: If either of the following two conditions is met, the kiln current is considered high and coal reduction is required; Condition 1: The rolling average value of the kiln current from the first 20 minutes to the first 10 minutes is greater than the upper limit of the kiln current, and the rolling average value of the kiln current from the first 10 minutes is greater than the upper limit of the kiln current + 20, and the kiln skin shedding status is less than 0.

6. Condition 2: The rolling average value of the kiln current in the first 10 minutes is greater than the upper limit of the kiln current, and the kiln scabbing condition is ≥0.

6. The formula for the recommended value of coal reduction is: Recommended value = -0.1×(1.5+(rolling average value of kiln current in the first 10 minutes - lower limit of kiln current - 60) / 80); 2.3) Recommended secondary air temperature: When the secondary air temperature is greater than the upper limit of the secondary air temperature, it is determined that the secondary air temperature is high and coal reduction is required; the formula for the recommended value of coal reduction is: Recommended value = -0.1×(secondary air temperature - upper limit of secondary air temperature) / 50; 2.4) Recommended ambient temperature: The formula for the recommended value of adjusting the coal feed rate at the kiln head based on the ambient temperature is: Recommended value = Head coal pressure set value - (273 + Ambient temperature) / (273 + Ambient temperature one minute ago) × Head coal pressure set value; 2.5) Kiln tail smoke chamber NO X Recommendation: When the NOx value of the kiln tail smoke chamber is - kiln tail smoke chamber NO X When the recommended value is >100, the formula for adjusting the coal feed rate at the kiln head is: Recommended value = min(-(kiln tail smoke chamber NO)). X Value - Kiln Tail Smoke Chamber NO X Recommended value: (-100) × 0.001, 0); When the NOx value in the kiln tail smoke chamber is less than the NO value in the kiln tail smoke chamber X When the recommended value is <-100, the formula for adjusting the coal feed rate at the kiln head is: Recommended value = max(-(kiln tail smoke chamber NO)). X Value - Kiln Tail Smoke Chamber NO X Recommended value +100) ×0.001,0).

5. The method for optimizing and controlling coal pressure at the head of a cement kiln according to claim 4, characterized in that: Step 2.1) Recommendations for comprehensive kiln condition indicators specifically include: 2.1.1) If any of the following three conditions are met, the kiln condition is judged to be poor and coal needs to be added; Condition 1: The brightness of the fire observed on the screen is less than the lower limit of the brightness of the fire observed on the screen, and the decomposition furnace has good performance; Condition 2: The overall kiln condition index is < -0.2, and the decomposition furnace performance is good; Condition 3: Overall kiln condition index < 0.4; 2.1.2) If either of the following two conditions is met, the kiln condition is considered good, and coal reduction is required; Condition 1: The comprehensive index of kiln condition > 0.2, and the actual head-to-tail coal ratio < the optimal head-to-tail coal ratio - 0.01; Condition 2: The CO at the preheater outlet is greater than the set value of the CO at the preheater outlet, and the comprehensive index of kiln condition is greater than 0.

2. At the same time, 2 × free calcium in the clinker leaving the kiln is less than the lower limit of free calcium in the clinker leaving the kiln plus the set value of free calcium in the clinker leaving the kiln.

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