A method for verifying coke quality based on coke particle size distribution at blast furnace tuyeres

Abstract

This invention discloses a method for verifying coke quality based on the particle size distribution of coke at the blast furnace tuyere, comprising the following steps: (1) using a special high-temperature resistant sampling device to collect coke samples from the tuyere and pre-processing them; (2) performing particle size distribution detection on the pre-processed coke samples, and then extracting three characteristic parameters based on the particle size detection results; (3) calculating the comprehensive verification index P of coke quality, and then classifying the coke quality into verification grades based on its value, and establishing a coke quality verification model; (4) performing real-time verification of coke quality based on the coke quality verification model, and then adjusting the operating conditions according to the verification results and the causes of abnormalities, and re-collecting tuyere coke samples based on the adjusted blast furnace operating conditions for secondary verification until the coke quality reaches the standard, thereby forming a closed-loop optimization and control system; (5) periodically verifying and correcting the above verification method. This invention achieves real-time and accurate verification of coke quality.

Description

Technical Field

[0001] This invention relates to the field of coke quality evaluation technology, specifically to a method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres. Background Technology

[0002] Coke is a core raw material for blast furnace ironmaking, serving three crucial functions: fuel, reducing agent, and structural support for the blast furnace charge. Its quality directly determines the stability of blast furnace operations, smelting efficiency, and production costs. Currently, the steel industry faces the dual pressures of production restrictions and rising ore raw material costs. Precise control of coke quality has become a key breakthrough for cost reduction and efficiency improvement.

[0003] Currently, the industry's evaluation of coke quality mainly relies on offline testing before it enters the blast furnace. Core indicators include coke reactivity (CRI), post-reaction strength (CSR), and industrial analysis. However, this method has significant drawbacks: 1) Strong detection lag: Offline testing requires sampling, testing, and analysis of the coke entering the furnace, a process that takes 4-8 hours. It cannot reflect the actual quality status of the coke in the blast furnace in real time. When substandard coke is detected, it has already entered the blast furnace for smelting, easily leading to furnace condition fluctuations, increased coke ratio, and reduced output; 2) Insufficient representativeness: Coke sampling only reflects the quality of the coke at the moment of entry into the furnace. During the descent of the coke in the blast furnace, it is affected by multiple factors such as high-temperature thermal stress, gasification reaction, and mechanical wear, resulting in changes in particle size. The coke will continue to deteriorate (the particle size decreases by about 20% at the furnace waist, about 40% at the furnace belly, and about 55% at the tuyeres), indicating that the test results before entering the furnace cannot reflect the actual degree of deterioration and performance of the coke in the blast furnace; 3) It is out of touch with the blast furnace operating conditions: the existing test methods do not combine the actual operating parameters of the blast furnace (such as air volume, air temperature, and pulverized coal injection), but only evaluate the physicochemical indicators of the coke itself, which cannot accurately determine the compatibility of coke quality with blast furnace operating conditions and is difficult to guide the dynamic adjustment of blast furnace operating parameters; 4) The verification accuracy is low: the traditional method has not established a quantitative correlation between coke particle size distribution and quality indicators, and judges the quality only by a single particle size indicator, which is prone to misjudgment, especially for special cokes such as tamped coke, where conventional indicators are difficult to objectively reflect their actual thermal performance and skeleton function.

[0004] The tuyere of a blast furnace is a crucial area where coke participates in the smelting reaction. After undergoing multiple processes within the furnace, the particle size distribution of the coke at the tuyere accurately reflects its high-temperature strength, abrasion resistance, and reaction stability, directly indicative of its actual quality in use. Therefore, establishing a scientific and quantitative method for coke quality verification based on the coke particle size distribution at the blast furnace tuyere, and achieving real-time and accurate verification of coke quality, has become key to addressing current technological challenges. This is of great significance for improving the precision of blast furnace smelting and reducing production costs. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for verifying coke quality based on the particle size distribution of coke at the blast furnace tuyere. Relying on blast furnace tuyere coke sampling, the entire process of sample collection, testing and verification takes only 1 to 2 hours, which is significantly shorter than the 4 to 8 hours of traditional offline testing. It can also reflect the actual quality of coke in the blast furnace in real time, avoiding the phenomenon of unqualified coke continuously participating in smelting and causing fluctuations in furnace conditions, thus solving the problem of detection lag.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The innovative aspect of the present invention is that it includes the following steps: (1) Select a stable and smooth operation period of the blast furnace, use a special high-temperature resistant sampling device to collect coke samples by inserting the device into the tuyere through the blast furnace tuyere inspection hole, and pre-process the collected coke samples. (2) The particle size distribution of the pretreated coke sample was detected by sieving method combined with laser particle size analyzer. Then, three characteristic parameters were extracted based on the particle size detection results as the basic indicators for coke quality verification. (3) Determine the benchmark values ​​of each characteristic parameter of blast furnace with different volumes, compare the three characteristic parameters with the benchmark values ​​of each characteristic parameter, combine the influence weight of each characteristic parameter on blast furnace smelting, calculate the comprehensive verification index P of coke quality, and then classify the coke quality into verification grades according to the value of the comprehensive verification index P, clarify the verification standards, and establish a coke quality verification model. (4) Real-time verification of coke quality is carried out according to the coke quality verification model. Then, the working conditions are adjusted according to the verification results and the causes of abnormalities. The coke samples from the tuyeres are collected again according to the adjusted blast furnace working conditions for secondary verification until the coke quality reaches the standard, thereby forming a closed-loop optimization and control system. (5) The above verification methods shall be verified and corrected regularly.

[0007] Preferably, in step (1) above, the collection and pretreatment of coke samples specifically includes: (1.1) Sampling timing: Sampling should be carried out during the stable operation period of the blast furnace when the air volume fluctuation is ≤±3%, the air temperature fluctuation is ≤±10℃, and the furnace top pressure fluctuation is ≤±5kPa. Sampling should be carried out once every 2 to 4 hours, and 3 to 5 parallel coke samples should be collected each time. (1.2) Sampling method: A special high-temperature resistant sampling device is inserted into the tuyere of the blast furnace through the inspection hole. Coke samples are collected at a position of 500~800mm inside the tuyere, and the sampling amount is 500~1000g / sample. Inert gas is used for protection during the sampling process. (1.3) Sample pretreatment: The collected coke samples were rapidly cooled to room temperature, and mechanical impact should be avoided during the cooling process; slag and iron particles were removed from the coke samples; each coke sample was then divided into two parts, one for particle size distribution detection and the other for retesting; for coke samples that were stuck together, they were gently dispersed by hand.

[0008] Preferably, in step (1.2) above, the special high-temperature resistant sampling device includes a sampling tube, an insulation layer, a handle, and an inert gas protective sleeve; the sampling tube is made of a high-temperature resistant alloy material, and it must be able to maintain its shape and integrity in a high-temperature environment of 1500℃, and the end of the sampling tube is provided with an anti-clogging screen; the inert gas protective sleeve is coaxially arranged with the sampling tube, and inert gas must be continuously introduced during the sampling process, and the flow rate of the inert gas is controlled at 0.5~1.0L / min.

[0009] Preferably, in step (2) above, the sieving method uses a standard sieve group with sieve aperture sizes of 60mm, 40mm, 25mm, 15mm, 10mm and 5mm for grading and sieving, and the sieving time is 10~15min, the vibration frequency is 200~250r / min, and sample splashing should be avoided during the sieving process; then the mass ratio of coke in each particle size is recorded, and the distribution of coke powder particles smaller than 5mm is detected by a laser particle size analyzer to supplement fine particle data to ensure the integrity of particle size distribution detection.

[0010] Preferably, in step (2) above, the three characteristic parameters include the proportion of main particle size coke mass R, the particle size uniformity coefficient K, and the coke powder rate S, specifically: (2.1) Define 40~60mm as the main particle size of large blast furnaces and 25~40mm as the main particle size of medium and small blast furnaces, and calculate the mass ratio R of the main particle size coke. (2.2) Calculate the standard deviation of the coke mass percentage of each particle size. The standard deviation is inversely proportional to the particle size uniformity. Then calculate the particle size uniformity coefficient K. The calculation formula is as follows: (1) Among them, w i w represents the mass percentage of the i-th coke particle size. 平均 denoted as the average mass percentage of all coke particle sizes; n represents the quantity of coke particle sizes. (2.3) Calculate the mass percentage of coke with a particle size <15mm. The wear resistance and high temperature strength of coke are inversely proportional to the coke powder ratio, and thus obtain the coke powder ratio S. Among them, the mass percentage of coke powder with a particle size <5mm needs to be counted separately as an auxiliary verification index.

[0011] Preferably, in step (3) above, based on the blast furnace volume, the type of steel to be smelted, and the production target, and in conjunction with industry practice data, the baseline values ​​of various characteristic parameters for blast furnaces of different volumes are determined. These baseline values ​​include the baseline value R for the mass ratio of main coke particles. 基准 Particle size uniformity coefficient reference value K 基准 and the benchmark value S for coke powder ratio 基准 Specifically: (3.1.1) Furnace volume d≥3000m³ 3 Large blast furnaces: Benchmark value R of main particle size coke mass ratio 基准 ≥70%, particle size uniformity coefficient benchmark value K 基准 ≤8.5, coke powder ratio benchmark value S 基准 ≤1%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.3%; (3.1.2) 1000m 3 <furnace volume d < 3000m³ 3 Medium-sized blast furnace: Benchmark value R of main particle size coke mass ratio 基准 ≥65%, particle size uniformity coefficient benchmark value K 基准 ≤10.0, Coke powder ratio benchmark value S 基准 ≤1.5%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.5%; (3.1.3) Furnace volume d≤1000m³ 3 Small blast furnace: Benchmark value R of main particle size coke mass ratio 基准 ≥60%, particle size uniformity coefficient benchmark value K 基准 ≤11.5, Coke powder ratio benchmark value S 基准 ≤2%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.8%.

[0012] Preferably, in step (3) above, the formula for calculating the comprehensive verification index P of coke quality is: (2) Among them, K1 is the influence weight of the proportion of coke mass in the main particle size, and its value is 0.45~0.55; K2 is the influence weight of the particle size uniformity coefficient, and its value is 0.25~0.35; K3 is the influence weight of the coke powder rate, and its value is 0.15~0.25. K1+K2+K3=1, and the adjustment principle for the influence weight of each characteristic parameter is as follows: for large blast furnaces, the focus is on verifying the proportion of coke mass in the main particle size, so the value of K1 is directly proportional to the blast furnace volume, and the value of K3 is inversely proportional to the blast furnace volume; for small blast furnaces, the influence weight of the proportion of coke mass in the main particle size needs to be reduced, and the influence weight of coke powder rate needs to be increased.

[0013] Preferably, in step (3) above, the coke quality is divided into three verification levels based on the value of the comprehensive verification index P, and the verification standards are clearly defined, specifically as follows: (3.2.1) When the value of the comprehensive verification index P is ≥1.05, the coke quality is classified as premium grade, which can maintain the existing coke ratio and blast furnace operating parameters. (3.2.2) When 0.95≤ the value of the comprehensive verification index P is <1.05, the coke quality is classified as qualified, and close monitoring is required, and the screening parameters of the coke entering the furnace should be adjusted appropriately. (3.2.3) When the value of the comprehensive verification index P is <0.95, the coke quality is classified as unqualified and the coke ratio or blast furnace operating parameters need to be adjusted immediately.

[0014] Preferably, in step (4) above, the closed-loop optimization control system specifically comprises: (4.1) Substitute the main particle size coke mass ratio R, particle size uniformity coefficient K and coke powder rate S extracted in step (2) into the comprehensive verification index P of formula (2), and determine the coke quality grade according to the value of the comprehensive verification index P to complete the real-time verification of coke quality. (4.2) Adjustments to the blast furnace operating conditions based on the verification results and the causes of the anomalies, specifically as follows: (4.2.1) If the verification result is of excellent quality, maintain the existing coke ratio and blast furnace operating parameters; (4.2.2) If the verification result is qualified, the verification data should be summarized every 12 hours to track the trend of particle size distribution. If the P value continues to decrease, preventive measures should be taken in advance. (4.2.3) If the verification result is unqualified and the abnormality is due to excessive coke powder ratio, adjust the coke ratio into the furnace, increase the proportion of high-strength coke, and ensure that the CSR of high-strength coke is ≥65% and CRI is ≤23%, and reduce the amount of weakly caking coal by 3~5%; at the same time, reduce the blast furnace temperature by 50~80℃ and reduce the amount of pulverized coal by 5~10kg / t iron, and monitor the blast furnace condition after adjusting the blast furnace temperature and the amount of pulverized coal. (4.2.4) If the verification result is unqualified and the abnormality is caused by the low proportion of coke mass of main particle size and the high particle size uniformity coefficient, optimize the coke screening process, adjust the screen size, and increase the proportion of coke mass of main particle size; at the same time, check the blast furnace charging system and adjust the material line height. (4.3) Collect coke samples from the tuyeres again according to the adjusted blast furnace operating conditions, and repeat the above steps for secondary verification until the coke quality reaches the premium or qualified level, forming a closed-loop optimization and control system of sampling-testing-verification-adjustment-re-inspection.

[0015] Preferably, in step (5) above, the process of periodically verifying and correcting the above verification method is as follows: (5.1) Collect offline detection data of coke entering the furnace once a quarter, namely CRI, CSR and industrial analysis, and compare them with the particle size distribution verification results of coke at the tuyeres in the same period to verify the accuracy of the coke quality verification model. (5.2) If the offline detection results do not match the verification level, adjust K1, K2 and K3 in the coke quality verification model, and update the baseline values ​​of each characteristic parameter according to the changes in blast furnace production parameters.

[0016] The beneficial effects of this invention are: (1) This invention relies on blast furnace tuyeres to sample coke, and the entire process of sample collection, testing and verification only takes 1 to 2 hours. Compared with the traditional offline testing of 4 to 8 hours, it greatly shortens the verification cycle and can reflect the actual quality of coke in the blast furnace in real time, avoiding the phenomenon of unqualified coke continuously participating in smelting and causing furnace condition fluctuations, thus solving the problem of detection lag. (2) This invention takes the particle size distribution of coke at the blast furnace tuyere as the core, extracts three characteristic parameters: the proportion of main particle size, the particle size uniformity coefficient, and the coke powder rate, and establishes a quantitative verification model in combination with the blast furnace volume. It takes into account the skeletal function, wear resistance and reaction stability of coke, and overcomes the defects of traditional methods that only detect the coke entering the furnace and are out of touch with the actual working conditions of the blast furnace. The verification accuracy rate is improved to more than 98%. At the same time, a comprehensive verification index is introduced to realize the quantitative evaluation of coke quality and avoid the phenomenon of misjudgment due to a single indicator. (3) This invention can not only complete the coke quality verification, but also analyze the cause of abnormality based on the verification results, and give targeted suggestions for adjusting the coke ratio and optimizing the blast furnace operating parameters, thereby forming a closed-loop control system, realizing the precise matching of coke quality and blast furnace operating conditions, effectively reducing the coke ratio by 5-8 kg / t iron, and increasing the blast furnace utilization coefficient by 0.05-0.1 t / (m³·d); (4) The present invention can adjust the benchmark value and weight coefficient according to the blast furnace volume, thus it is applicable to various types of blast furnaces. The sampling and testing process is simple to operate, no new complex equipment is required, it can be achieved by relying on the existing testing instruments of steel plants, the investment cost is low, and it is easy to promote and apply. (5) This invention establishes a quantitative correlation between the particle size distribution of coke at the blast furnace tuyeres and the quality of coke, which solves the problem that traditional methods cannot accurately evaluate the actual quality of coke used in the furnace. It is especially suitable for quality verification of special cokes such as tamped coke, and provides a new technical path for the fine smelting of blast furnaces. At the same time, it meets the current needs of the steel industry for cost reduction, efficiency improvement and green development. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram illustrating the principle of a method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres, according to the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below through specific embodiments.

[0020] This invention provides a method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres, such as... Figure 1 As shown, it includes the following steps: (1) Select a stable and smooth operation period of the blast furnace, use a special high-temperature resistant sampling device to collect coke samples by inserting the device into the tuyere through the tuyere inspection hole, and pre-process the collected coke samples.

[0021] The above steps, specifically the collection and pretreatment of coke samples, include: (1.1) Sampling timing: In order to avoid the distortion of coke particle size distribution caused by abnormal furnace conditions, sampling was carried out during the stable operation period of the blast furnace. The sampling was carried out during the stable operation period of the blast furnace with air volume fluctuation ≤ ±3%, air temperature fluctuation ≤ ±10℃, and furnace top pressure fluctuation ≤ ±5kPa. Sampling was carried out every 2 to 4 hours, and 3 to 5 parallel coke samples were collected each time to ensure the representativeness of the coke samples.

[0022] (1.2) Sampling method: A special high-temperature resistant sampling device is inserted into the tuyere of the blast furnace and a coke sample is collected at a position of 500~800mm inside the tuyere. The sampling amount is 500~1000g / sample. Inert gas is used for protection during the sampling process to avoid the coke sample from oxidizing or getting damp in the air, which would affect the particle size detection accuracy. The special high-temperature resistant sampling device of this invention includes a sampling tube, an insulation layer, a handle, and an inert gas protective sleeve. The sampling tube is made of high-temperature resistant alloy material and must be able to maintain its shape and integrity at a high temperature of 1500℃. The end of the sampling tube is equipped with an anti-clogging screen to prevent slag from entering the sampling tube. The inert gas protective sleeve is coaxially arranged with the sampling tube, and inert gas must be continuously introduced during the sampling process, with the flow rate of the inert gas controlled at 0.5~1.0L / min to prevent oxidation of the coke sample.

[0023] (1.3) Sample pretreatment: The collected coke samples are rapidly cooled to room temperature, and mechanical impact should be avoided during the cooling process to prevent particle breakage; slag and iron particles are removed from the coke samples; each coke sample is then divided into two parts, one for particle size distribution testing and the other for retesting; for coke samples that are stuck together, they are gently dispersed by hand, and mechanical crushing is strictly prohibited to ensure that the particle size of the coke samples is consistent with the actual state of the tuyeres.

[0024] (2) The particle size distribution of the pretreated coke sample was detected by sieving method combined with laser particle size analyzer. Then, three characteristic parameters were extracted based on the particle size detection results as the basic indicators for coke quality verification.

[0025] The sieving method of this invention uses a standard sieve group with sieve aperture sizes of 60mm, 40mm, 25mm, 15mm, 10mm, and 5mm for grading and sieving. The sieving time is 10-15 minutes, the vibration frequency is 200-250 r / min, and sample splashing must be avoided during the sieving process. Then, the mass percentage of coke in each particle size is recorded, and the distribution of coke powder particles smaller than 5mm is detected by a laser particle size analyzer to supplement the fine particle size data and ensure the completeness of particle size distribution detection. The detection range of the laser particle size analyzer is 0.1-500μm, and the detection accuracy is ≤±2%, ensuring the accuracy of fine coke powder detection.

[0026] The three characteristic parameters of this invention include the main particle size fraction of coke mass R, the particle size uniformity coefficient K, and the coke powder rate S, specifically: (2.1) Define 40~60mm as the main particle size of large blast furnace and 25~40mm as the main particle size of medium and small blast furnace, and calculate the mass ratio R of the main particle size coke. The mass ratio of the main particle size coke is the percentage of the main particle size coke in the total coke sample mass, and this reflects the skeleton support capacity of coke. (2.2) Calculate the standard deviation of the coke mass percentage of each particle size. The standard deviation is inversely proportional to the particle size uniformity. Then calculate the particle size uniformity coefficient K. The calculation formula is as follows: (1) Among them, w i w represents the mass percentage of the i-th coke particle size. 平均 denoted as the average mass percentage of all coke particle sizes; n represents the quantity of coke particle sizes. (2.3) Calculate the mass percentage of coke with a particle size <15mm. The wear resistance and high temperature strength of coke are inversely proportional to the coke powder ratio, and thus obtain the coke powder ratio S. Among them, the mass percentage of coke powder with a particle size <5mm needs to be counted separately as an auxiliary verification index.

[0027] (3) Determine the benchmark values ​​of each characteristic parameter of blast furnace with different volumes, compare the three characteristic parameters with the benchmark values ​​of each characteristic parameter, combine the influence weight of each characteristic parameter on blast furnace smelting, calculate the comprehensive verification index P of coke quality, and then classify the coke quality into verification grades according to the value of the comprehensive verification index P, clarify the verification standards, and establish a coke quality verification model.

[0028] This invention, based on blast furnace volume, steel grade, and production targets, and in conjunction with industry practice data, determines benchmark values ​​for various characteristic parameters of blast furnaces with different volumes. These benchmark values ​​include the benchmark value R for the mass percentage of main coke particles. 基准 Particle size uniformity coefficient reference value K 基准 and the benchmark value S for coke powder ratio 基准 Specifically: (3.1.1) Furnace volume d≥3000m³ 3 Large blast furnaces: Benchmark value R of main particle size coke mass ratio 基准 ≥70%, particle size uniformity coefficient benchmark value K 基准 ≤8.5, coke powder ratio benchmark value S 基准 ≤1%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.3%; (3.1.2) 1000m 3 <furnace volume d < 3000m³ 3 Medium-sized blast furnace: Benchmark value R of main particle size coke mass ratio 基准 ≥65%, particle size uniformity coefficient benchmark value K 基准 ≤10.0, Coke powder ratio benchmark value S 基准 ≤1.5%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.5%; (3.1.3) Furnace volume d≤1000m³ 3 Small blast furnace: Benchmark value R of main particle size coke mass ratio 基准 ≥60%, particle size uniformity coefficient benchmark value K 基准 ≤11.5, Coke powder ratio benchmark value S 基准 ≤2%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.8%.

[0029] The formula for calculating the comprehensive verification index P of coke quality in this invention is as follows: (2) Among them, K1 is the influence weight of the proportion of coke mass in the main particle size, and its value is 0.45~0.55; K2 is the influence weight of the particle size uniformity coefficient, and its value is 0.25~0.35; K3 is the influence weight of the coke powder rate, and its value is 0.15~0.25. K1+K2+K3=1, and the adjustment principle for the influence weight of each characteristic parameter is as follows: for large blast furnaces, the focus is on verifying the proportion of coke mass in the main particle size, so the value of K1 is directly proportional to the blast furnace volume, and the value of K3 is inversely proportional to the blast furnace volume; for small blast furnaces, the influence weight of the proportion of coke mass in the main particle size needs to be reduced, and the influence weight of coke powder rate needs to be increased.

[0030] This invention classifies coke quality into three verification levels based on the value of the comprehensive verification index P, and clarifies the verification standards, specifically as follows: (3.2.1) When the value of the comprehensive verification index P is ≥1.05, the coke quality is classified as premium grade. At this time, the coke quality is excellent, the skeleton support capacity is strong, the particle size is uniform, the coke powder rate is low, it is suitable for the current blast furnace conditions, and the existing coke ratio and blast furnace operating parameters can be maintained. (3.2.2) When 0.95≤ the value of the comprehensive verification index P is <1.05, the coke quality is classified as qualified. At this time, the coke quality is qualified and basically suitable for blast furnace conditions, but there are problems such as uneven particle size or high coke powder rate. Close monitoring is required and the coke screening parameters should be adjusted appropriately. (3.2.3) When the value of the comprehensive verification index P is <0.95, the coke quality is classified as unqualified. At this time, the coke quality is substandard, the skeleton support capacity is insufficient, the particle size distribution is uneven or the coke powder rate is too high, which can easily lead to a decrease in blast furnace permeability and fluctuation in furnace condition. The coke ratio or blast furnace operating parameters need to be adjusted immediately.

[0031] (4) Real-time verification of coke quality is carried out according to the coke quality verification model. Then, the working conditions are adjusted according to the verification results and the causes of abnormalities. The coke samples from the tuyeres are collected again according to the adjusted blast furnace working conditions for secondary verification until the coke quality reaches the standard, thereby forming a closed-loop optimization and control system.

[0032] The aforementioned closed-loop optimization and control system is specifically as follows: (4.1) Substitute the main particle size coke mass ratio R, particle size uniformity coefficient K and coke powder rate S extracted in step (2) into the comprehensive verification index P of formula (2), and determine the coke quality grade according to the value of the comprehensive verification index P to complete the real-time verification of coke quality.

[0033] (4.2) Adjustments to the blast furnace operating conditions based on the verification results and the causes of the anomalies, specifically as follows: (4.2.1) If the verification result is of excellent quality, maintain the existing coke ratio and blast furnace operating parameters; (4.2.2) If the verification result is qualified, the verification data should be summarized every 12 hours to track the trend of particle size distribution. If the P value continues to decrease, preventive measures should be taken in advance to avoid the deterioration of coke quality. (4.2.3) If the verification result is unqualified and the abnormality is due to excessive coke powder ratio, it indicates that the coke's abrasion resistance and high-temperature strength are insufficient. This may be due to the substandard quality of the coke itself or excessive blast furnace temperature and excessive pulverized coal injection. At this time, adjust the coke ratio to increase the proportion of high-strength coke, and ensure that the CSR of the high-strength coke is ≥65% and CRI is ≤23%. Reduce the amount of weakly caking coal by 3-5%. At the same time, reduce the blast furnace temperature by 50-80℃ and reduce the pulverized coal injection by 5-10 kg / t iron. After adjusting the blast furnace temperature and pulverized coal injection, monitor the blast furnace condition to ensure that parameters such as air volume and furnace top pressure are stable within a reasonable range, thereby reducing the thermal stress and reaction loss of the coke. (4.2.4) If the verification result is unqualified, and the abnormality is caused by the low proportion of coke mass of the main particle size and the high particle size uniformity coefficient, it indicates that the coke particle size classification is unreasonable or the mechanical wear in the furnace is too serious. At this time, it is necessary to optimize the coke screening process, adjust the screen size, and increase the proportion of coke mass of the main particle size; at the same time, check the blast furnace charging system, adjust the material line height, and reduce the mechanical wear of coke in the furnace.

[0034] (4.3) Collect coke samples from the tuyeres again according to the adjusted blast furnace operating conditions, and repeat the above steps for secondary verification until the coke quality reaches the premium or qualified level, forming a closed-loop optimization and control system of sampling-testing-verification-adjustment-re-inspection.

[0035] (5) The above verification methods shall be verified and revised periodically, specifically as follows: (5.1) Collect offline detection data of coke entering the furnace once a quarter, namely CRI, CSR and industrial analysis, and compare them with the particle size distribution verification results of coke at the tuyeres in the same period to verify the accuracy of the coke quality verification model. (5.2) If the offline detection results do not match the verification level, K1, K2 and K3 in the coke quality verification model shall be adjusted. At the same time, the benchmark values ​​of each characteristic parameter shall be updated according to the changes in blast furnace production parameters (such as furnace capacity expansion and steel grade adjustment) to ensure the adaptability and accuracy of the verification method.

[0036] Example 1 With a furnace volume of 4038m³ 3 Taking large blast furnaces as an example The present invention provides a method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres, comprising the following steps: (1) First, select a stable period of blast furnace operation. At this time, the air volume is 4200 m³ / min, the air volume fluctuation is ±2%, the air temperature is 1250℃, the air temperature fluctuation is ±8℃, the furnace top pressure is 0.25 MPa, and the furnace top pressure fluctuation is ±3 kPa. Then, every 3 hours, a special high-temperature resistant sampling device is used to collect coke samples from 700 mm inside the tuyere through the tuyere viewing hole. Four parallel coke samples are collected each time, and the sample amount of each sample is 800 g. Nitrogen gas is introduced for protection during the sampling process, and the flow rate of nitrogen gas is controlled at 0.8 L / min. Then, the collected coke samples are quickly cooled to room temperature. After removing slag and iron particles from the coke samples, each coke sample is divided into two parts for particle size distribution detection and backup retesting.

[0037] (2) Standard sieves were used for grading and screening, with a screening time of 12 min and a vibration frequency of 220 r / min. At the same time, the distribution of coke powder particles smaller than 5 mm was detected by a laser particle size analyzer with a detection accuracy of 1.5%. The detection results were as follows: the mass proportion of coke powder with a particle size of 40-60 mm was 72%, the mass proportion of coke powder with a particle size of 25-40 mm was 15%, the mass proportion of coke powder with a particle size of 15-25 mm was 8%, the mass proportion of coke powder with a particle size of 10-15 mm was 3%, the mass proportion of coke powder with a particle size of 5-10 mm was 1.5%, and the mass proportion of coke powder with a particle size of <5 mm was 0.5%. Among them, the 40-60 mm particle size was the main particle size. Then, based on the particle size detection results, three characteristic parameters are extracted: the mass ratio of main particle size coke R=72%, the particle size uniformity coefficient K=7.8, and the coke powder rate S=3%+1.5%+0.5%=5% (this is simulated abnormal data), of which the mass ratio of coke powder with a particle size <5mm is 0.5%.

[0038] (3) Determine the benchmark values ​​of each characteristic parameter of the large blast furnace, namely the benchmark value R of the mass ratio of main particle size coke. 基准 =70%, particle size uniformity coefficient benchmark value K 基准 =8.5, Coke powder ratio benchmark value S 基准 =1%; and the weighting coefficients for large blast furnaces are set to K1=0.5, K2=0.3, and K3=0.2 respectively; Then, the comprehensive verification index of coke quality is calculated according to formula (2). It was judged to be unqualified.

[0039] (4) The abnormality was analyzed as follows: the coke powder rate S=5%, which is much higher than the benchmark value of 1%, indicating that the coke's wear resistance and high temperature strength are insufficient. Based on the blast furnace operating parameters, it was determined that the excessive coal injection rate (180kg / t iron) led to increased coke reaction loss. At this time, the coal injection rate was reduced to 165kg / t iron, the blast temperature was reduced to 1180℃, the coke ratio was adjusted, the proportion of high-strength coke with CSR=68% and CRI=21% was increased, and the amount of weakly caking coal was reduced by 4%. After 24 hours of adjustment, the samples were resampled and tested, and the new characteristic parameters were obtained as R=73%, K=7.5, and S=0.8%. The comprehensive verification index of coke quality was then calculated according to formula (2). It was still judged as unqualified, and then the coal injection rate was adjusted to 160 kg / t iron, and the proportion of high-strength coke was increased by 2%. After 12 hours of adjustment, the samples were resampled and tested, and the new characteristic parameters were obtained as R=74%, K=7.2, and S=0.6%. The comprehensive verification index of coke quality was then calculated according to formula (2). If the result is deemed satisfactory, continuous monitoring will continue for 48 hours. When the value of the comprehensive verification index P stabilizes between 0.97 and 0.99, the closed-loop optimization is complete.

[0040] Example 2 With a furnace volume of 2000m³ 3 Taking a medium-sized blast furnace as an example The present invention provides a method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres, comprising the following steps: (1) First, select a stable period of blast furnace operation. At this time, the air volume is 2800 m³ / min, the air volume fluctuation is ±2.5%, the air temperature is 1200℃, the air temperature fluctuation is ±9℃, the furnace top pressure is 0.20 MPa, and the furnace top pressure fluctuation is ±4 kPa. Then, every 4 hours, a special high-temperature resistant sampling device is used to collect coke samples from the tuyere through the tuyere viewing hole to a depth of 600 mm. Three parallel coke samples are collected each time, and the sample amount of each sample is 700 g. Nitrogen gas is introduced for protection during the sampling process, and the flow rate of nitrogen gas is controlled at 0.6 L / min. Then, the collected coke samples are quickly cooled to room temperature. After removing slag and iron particles from the coke samples, each coke sample is divided into two parts for particle size distribution detection and backup retesting.

[0041] (2) Standard sieves were used for grading and screening, with a screening time of 13 min and a vibration frequency of 230 r / min. At the same time, the distribution of coke powder particles smaller than 5 mm was detected by a laser particle size analyzer with a detection accuracy of 1.5%. The detection results were as follows: the mass proportion of coke powder with a particle size of 25-40 mm was 67%, the mass proportion of coke powder with a particle size of 15-25 mm was 18%, the mass proportion of coke powder with a particle size of 10-15 mm was 7%, the mass proportion of coke powder with a particle size of 5-10 mm was 5%, and the mass proportion of coke powder with a particle size of <5 mm was 3%, of which the 25-40 mm particle size was the main particle size. Then, based on the particle size detection results, three characteristic parameters are extracted: the mass ratio of main particle size coke R=67%, the particle size uniformity coefficient K=9.2, and the coke powder rate S=7%+5%+3%=15% (this is simulated abnormal data), of which the mass ratio of coke powder with a particle size <5mm is 3%.

[0042] (3) Determine the baseline values ​​of each characteristic parameter of the medium-sized blast furnace, namely the baseline value R of the mass ratio of main particle size coke. 基准 =65%, particle size uniformity coefficient benchmark value K 基准 =10.0, Coke powder ratio benchmark value S 基准 =1.5%; and the weighting coefficients for medium-sized blast furnaces are set to K1=0.48, K2=0.32, and K3=0.2 respectively; Then, the comprehensive verification index of coke quality is calculated according to formula (2). It was judged to be unqualified.

[0043] (4) The abnormality was caused by excessive coke powder ratio and low main particle coke mass ratio. It was determined that the coke screening was unreasonable and the coke itself was not strong enough. At this time, the coke screening process was optimized, and the screen size was adjusted to 40mm and 25mm to increase the main particle coke mass ratio. The coke ratio was then adjusted to increase the proportion of high-strength coke by 5% and replace some weakly sticky coal. The blast temperature was reduced to 1150℃ to reduce coke thermal stress loss. After 36 hours of adjustment, the samples were resampled and tested, and the new characteristic parameters were obtained as R=68%, K=8.8, and S=1.2%. The comprehensive verification index of coke quality was then calculated according to formula (2). It was still judged as unqualified, and then the screening process was further optimized by increasing the screening time of the main particle size and adjusting the proportion of high-strength coke to 3%. After 24 hours of adjustment, the samples were resampled and tested, and the new characteristic parameters were obtained as R=69%, K=8.5, and S=1.0%. The comprehensive verification index of coke quality was then calculated according to formula (2). If the result is deemed acceptable, follow-up testing will be conducted. When the value of the comprehensive verification index P stabilizes between 0.96 and 1.02, closed-loop optimization is completed, and the generation requirements are met.

[0044] Example 3 With a furnace volume of 800m³ 3 Taking a small blast furnace as an example The present invention provides a method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres, comprising the following steps: (1) First, select a stable period of blast furnace operation. At this time, the air volume is 1500 m³ / min, the air volume fluctuation is ±3%, the air temperature is 1150℃, the air temperature fluctuation is ±10℃, the furnace top pressure is 0.15 MPa, and the furnace top pressure fluctuation is ±5 kPa. Then, every 2 hours, a special high-temperature resistant sampling device is used to collect coke samples 500 mm into the tuyere through the tuyere viewing hole. Five parallel coke samples are collected each time, and the sample amount of each sample is 600 g. Nitrogen gas is introduced for protection during the sampling process, and the flow rate of nitrogen gas is controlled at 0.5 L / min. Then, the collected coke samples are quickly cooled to room temperature. After removing slag and iron particles from the coke samples, each coke sample is divided into two parts for particle size distribution detection and backup retesting.

[0045] (2) Standard sieves were used for grading and screening, with a screening time of 10 min and a vibration frequency of 200 r / min. At the same time, the distribution of coke powder particles smaller than 5 mm was detected by a laser particle size analyzer with a detection accuracy of 1.5%. The detection results were as follows: the mass proportion of coke powder with a particle size of 25-40 mm was 62%, the mass proportion of coke powder with a particle size of 15-25 mm was 20%, the mass proportion of coke powder with a particle size of 10-15 mm was 10%, the mass proportion of coke powder with a particle size of 5-10 mm was 5%, and the mass proportion of coke powder with a particle size of <5 mm was 3%. Among them, the particle size of 25-40 mm was the main particle size. Then, based on the particle size detection results, three characteristic parameters are extracted: the mass ratio of main particle size coke R=62%, the particle size uniformity coefficient K=10.8, and the coke powder rate S=10%+5%+3%=18% (this is simulated abnormal data), of which the mass ratio of coke powder with a particle size <5mm is 3%.

[0046] (3) Determine the benchmark values ​​of each characteristic parameter of the small blast furnace, namely the benchmark value R of the mass ratio of main particle size coke. 基准 =60%, particle size uniformity coefficient benchmark value K 基准 =11.5, Coke powder ratio benchmark value S 基准 =2%; and the weighting coefficients for small blast furnaces are set to K1=0.45, K2=0.35, and K3=0.2 respectively; Then, the comprehensive verification index of coke quality is calculated according to formula (2). It was judged to be unqualified.

[0047] (4) The abnormality was analyzed as being caused by excessive coke powder ratio and poor particle size uniformity. It was determined that the blast furnace charging system was unreasonable, resulting in severe mechanical wear of the coke and substandard quality of the coke entering the furnace. At this time, the height of the blast furnace charge line was adjusted to reduce the charge line by 50mm to reduce the mechanical impact during the coke falling process. The charging system was optimized by adopting the "uniform charging" mode to reduce local wear. The coke ratio entering the furnace was adjusted by increasing the proportion of coke with CSR=65% by 4% and reducing the amount of weakly caking coal by 3%. After 24 hours of adjustment, the samples were resampled and tested, and the new characteristic parameters were obtained as R=63%, K=10.2, and S=1.8%. The comprehensive verification index of coke quality was then calculated according to formula (2). It was still judged as unqualified, so the material line height was adjusted again and the proportion of high-strength coke was increased by 2%. After 12 hours of adjustment, the samples were resampled and tested, and the new characteristic parameters were obtained as R=64%, K=9.8, and S=1.5%. The comprehensive verification index of coke quality was then calculated according to formula (2). It is close to being qualified; After adjusting for 8 hours, the samples were resampled and tested, and the new characteristic parameters were obtained as R=64%, K=9.7, and S=1.4%. The comprehensive verification index of coke quality was then calculated according to formula (2). It was judged to be qualified, closed-loop optimization was completed, and subsequent tracking and testing were conducted to ensure that the generation requirements were met.

[0048] The beneficial effects of this invention are: (1) This invention relies on blast furnace tuyeres to sample coke, and the entire process of sample collection, testing and verification only takes 1 to 2 hours. Compared with the traditional offline testing of 4 to 8 hours, it greatly shortens the verification cycle and can reflect the actual quality of coke in the blast furnace in real time, avoiding the phenomenon of unqualified coke continuously participating in smelting and causing furnace condition fluctuations, thus solving the problem of detection lag. (2) This invention takes the particle size distribution of coke at the blast furnace tuyere as the core, extracts three characteristic parameters: the proportion of main particle size, the particle size uniformity coefficient, and the coke powder rate, and establishes a quantitative verification model in combination with the blast furnace volume. It takes into account the skeletal function, wear resistance and reaction stability of coke, and overcomes the defects of traditional methods that only detect the coke entering the furnace and are out of touch with the actual working conditions of the blast furnace. The verification accuracy rate is improved to more than 98%. At the same time, a comprehensive verification index is introduced to realize the quantitative evaluation of coke quality and avoid the phenomenon of misjudgment due to a single indicator. (3) This invention can not only complete the coke quality verification, but also analyze the cause of abnormality based on the verification results, and give targeted suggestions for adjusting the coke ratio and optimizing the blast furnace operating parameters, thereby forming a closed-loop control system, realizing the precise matching of coke quality and blast furnace operating conditions, effectively reducing the coke ratio by 5-8 kg / t iron, and increasing the blast furnace utilization coefficient by 0.05-0.1 t / (m³·d); (4) The present invention can adjust the benchmark value and weight coefficient according to the blast furnace volume, thus it is applicable to various types of blast furnaces. The sampling and testing process is simple to operate, no new complex equipment is required, it can be achieved by relying on the existing testing instruments of steel plants, the investment cost is low, and it is easy to promote and apply. (5) This invention establishes a quantitative correlation between the particle size distribution of coke at the blast furnace tuyeres and the quality of coke, which solves the problem that traditional methods cannot accurately evaluate the actual quality of coke used in the furnace. It is especially suitable for quality verification of special cokes such as tamped coke, and provides a new technical path for the fine smelting of blast furnaces. At the same time, it meets the current needs of the steel industry for cost reduction, efficiency improvement and green development.

[0049] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, all modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope of the present invention. The technical content for which protection is sought in the present invention has been fully described in the technical requirements.

Claims

1. A method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres, characterized in that... Includes the following steps: (1) Select a stable and smooth operation period of the blast furnace, use a special high-temperature resistant sampling device to collect coke samples by inserting the device into the tuyere through the blast furnace tuyere inspection hole, and pre-process the collected coke samples. (2) The particle size distribution of the pretreated coke sample was detected by sieving method combined with laser particle size analyzer. Then, three characteristic parameters were extracted based on the particle size detection results as the basic indicators for coke quality verification. (3) Determine the benchmark values ​​of each characteristic parameter of blast furnace with different volumes, compare the three characteristic parameters with the benchmark values ​​of each characteristic parameter, combine the influence weight of each characteristic parameter on blast furnace smelting, calculate the comprehensive verification index P of coke quality, and then classify the coke quality into verification grades according to the value of the comprehensive verification index P, clarify the verification standards, and establish a coke quality verification model. (4) Real-time verification of coke quality is carried out according to the coke quality verification model. Then, the working conditions are adjusted according to the verification results and the causes of abnormalities. The coke samples from the tuyeres are collected again according to the adjusted blast furnace working conditions for secondary verification until the coke quality reaches the standard, thereby forming a closed-loop optimization and control system. (5) The above verification methods shall be verified and corrected regularly.

2. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 1, characterized in that: In step (1) above, the collection and pretreatment of coke samples specifically includes: (1.1) Sampling timing: Sampling should be carried out during the stable operation period of the blast furnace when the air volume fluctuation is ≤±3%, the air temperature fluctuation is ≤±10℃, and the furnace top pressure fluctuation is ≤±5kPa. Sampling should be carried out once every 2 to 4 hours, and 3 to 5 parallel coke samples should be collected each time. (1.2) Sampling method: A special high-temperature resistant sampling device is inserted into the tuyere of the blast furnace through the inspection hole. Coke samples are collected at a position of 500~800mm inside the tuyere, and the sampling amount is 500~1000g / sample. Inert gas is used for protection during the sampling process. (1.3) Sample pretreatment: The collected coke samples were rapidly cooled to room temperature, and mechanical impact should be avoided during the cooling process; slag and iron particles were removed from the coke samples; each coke sample was then divided into two parts, one for particle size distribution detection and the other for retesting; for coke samples that were stuck together, they were gently dispersed by hand.

3. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 2, characterized in that: In step (1.2) above, the special high-temperature resistant sampling device includes a sampling tube, an insulation layer, a handle, and an inert gas protective sleeve; the sampling tube is made of high-temperature resistant alloy material, and it must be able to maintain its shape and integrity in a high-temperature environment of 1500℃, and the end of the sampling tube is provided with an anti-clogging screen; the inert gas protective sleeve is coaxially arranged with the sampling tube, and inert gas must be continuously introduced during the sampling process, and the flow rate of the inert gas is controlled at 0.5~1.0L / min.

4. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 1, characterized in that: In step (2) above, the sieving method uses a standard sieve group with sieve aperture sizes of 60mm, 40mm, 25mm, 15mm, 10mm and 5mm for grading and sieving. The sieving time is 10~15min and the vibration frequency is 200~250r / min. Sample splashing should be avoided during the sieving process. Then, the mass percentage of coke in each particle size is recorded. The distribution of coke powder particles smaller than 5mm is detected by a laser particle size analyzer to supplement the fine particle size data and ensure the integrity of the particle size distribution detection.

5. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 4, characterized in that: In step (2) above, the three characteristic parameters include the proportion of coke mass in the main particle size fraction R, the particle size uniformity coefficient K, and the coke powder ratio S, specifically: (2.1) Define 40~60mm as the main particle size of large blast furnaces and 25~40mm as the main particle size of medium and small blast furnaces, and calculate the mass ratio R of the main particle size coke. (2.2) Calculate the standard deviation of the coke mass percentage of each particle size. The standard deviation is inversely proportional to the particle size uniformity. Then calculate the particle size uniformity coefficient K. The calculation formula is as follows: （1） Among them, w i w represents the mass percentage of the i-th coke particle size. 平均 denoted as the average mass percentage of all coke particle sizes; n represents the quantity of coke particle sizes. (2.3) Calculate the mass percentage of coke with a particle size <15mm. The wear resistance and high temperature strength of coke are inversely proportional to the coke powder ratio, and thus obtain the coke powder ratio S. Among them, the mass percentage of coke powder with a particle size <5mm needs to be counted separately as an auxiliary verification index.

6. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 1, characterized in that: In step (3) above, based on the blast furnace volume, the type of steel to be smelted, and the production target, and in conjunction with industry practice data, the baseline values ​​of various characteristic parameters for blast furnaces of different volumes are determined. The baseline values ​​of each characteristic parameter include the baseline value R of the mass ratio of main coke particles. 基准 Particle size uniformity coefficient reference value K 基准 and the benchmark value S for coke powder ratio 基准 Specifically: (3.1.1) Furnace volume d≥3000m³ 3 Large blast furnaces: Benchmark value R of main particle size coke mass ratio 基准 ≥70%, particle size uniformity coefficient benchmark value K 基准 ≤8.5, coke powder ratio benchmark value S 基准 ≤1%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.3%; (3.1.2) 1000m 3 <furnace volume d < 3000m³ 3 Medium-sized blast furnace: Benchmark value R of main particle size coke mass ratio 基准 ≥65%, particle size uniformity coefficient benchmark value K 基准 ≤10.0, Coke powder ratio benchmark value S 基准 ≤1.5%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.5%; (3.1.3) Furnace volume d≤1000m³ 3 Small blast furnace: Benchmark value R of main particle size coke mass ratio 基准 ≥60%, particle size uniformity coefficient benchmark value K 基准 ≤11.5, Coke powder ratio benchmark value S 基准 ≤2%; of which, the mass percentage of coke powder with a particle size <5mm must be ≤0.8%.

7. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 6, characterized in that: In step (3) above, the formula for calculating the comprehensive verification index P of coke quality is: （2） Among them, K1 is the influence weight of the proportion of coke mass in the main particle size, and its value is 0.45~0.55; K2 is the influence weight of the particle size uniformity coefficient, and its value is 0.25~0.35; K3 is the influence weight of the coke powder rate, and its value is 0.15~0.

25. K1+K2+K3=1, and the adjustment principle for the influence weight of each characteristic parameter is as follows: for large blast furnaces, the focus is on verifying the proportion of coke mass in the main particle size, so the value of K1 is directly proportional to the blast furnace volume, and the value of K3 is inversely proportional to the blast furnace volume; for small blast furnaces, the influence weight of the proportion of coke mass in the main particle size needs to be reduced, and the influence weight of coke powder rate needs to be increased.

8. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 7, characterized in that: In step (3) above, the coke quality is divided into three verification levels based on the value of the comprehensive verification index P, and the verification standards are clearly defined, as follows: (3.2.1) When the value of the comprehensive verification index P is ≥1.05, the coke quality is classified as premium grade, which can maintain the existing coke ratio and blast furnace operating parameters. (3.2.2) When 0.95≤ the value of the comprehensive verification index P is <1.05, the coke quality is classified as qualified, and close monitoring is required, and the screening parameters of the coke entering the furnace should be adjusted appropriately. (3.2.3) When the value of the comprehensive verification index P is <0.95, the coke quality is classified as unqualified and the coke ratio or blast furnace operating parameters need to be adjusted immediately.

9. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 8, characterized in that: In step (4) above, the closed-loop optimization control system specifically refers to: (4.1) Substitute the main particle size coke mass ratio R, particle size uniformity coefficient K and coke powder rate S extracted in step (2) into the comprehensive verification index P of formula (2), and determine the coke quality grade according to the value of the comprehensive verification index P to complete the real-time verification of coke quality. (4.2) Adjustments to the blast furnace operating conditions based on the verification results and the causes of the anomalies, specifically as follows: (4.2.1) If the verification result is of excellent quality, maintain the existing coke ratio and blast furnace operating parameters; (4.2.2) If the verification result is qualified, the verification data should be summarized every 12 hours to track the trend of particle size distribution. If the P value continues to decrease, preventive measures should be taken in advance. (4.2.3) If the verification result is unqualified and the abnormality is due to excessive coke powder ratio, adjust the coke ratio into the furnace, increase the proportion of high-strength coke, and ensure that the CSR of high-strength coke is ≥65% and CRI is ≤23%, and reduce the amount of weakly caking coal by 3~5%; at the same time, reduce the blast furnace temperature by 50~80℃ and reduce the amount of pulverized coal by 5~10kg / t iron, and monitor the blast furnace condition after adjusting the blast furnace temperature and the amount of pulverized coal. (4.2.4) If the verification result is unqualified and the abnormality is caused by the low proportion of coke mass of main particle size and the high particle size uniformity coefficient, optimize the coke screening process, adjust the screen size, and increase the proportion of coke mass of main particle size; at the same time, check the blast furnace charging system and adjust the material line height. (4.3) Collect coke samples from the tuyeres again according to the adjusted blast furnace operating conditions, and repeat the above steps for secondary verification until the coke quality reaches the premium or qualified level, forming a closed-loop optimization and control system of sampling-testing-verification-adjustment-re-inspection.

10. The method for verifying coke quality based on the coke particle size distribution at the blast furnace tuyeres according to claim 9, characterized in that: In step (5) above, the process of periodically verifying and correcting the above verification method is as follows: (5.1) Collect offline detection data of coke entering the furnace once a quarter, namely CRI, CSR and industrial analysis, and compare them with the particle size distribution verification results of coke at the tuyeres in the same period to verify the accuracy of the coke quality verification model. (5.2) If the offline detection results do not match the verification level, adjust K1, K2 and K3 in the coke quality verification model, and update the baseline values ​​of each characteristic parameter according to the changes in blast furnace production parameters.

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