Method for improving detection precision of thermal performance of coking coal

Abstract

The invention discloses a method for improving coking coal thermal performance detection precision, and belongs to the technical field of coking coal performance evaluation and coal blending coking. The method comprises the following steps: step 1, determining the furnace type of a test coke oven; step 2, influence of a temperature control program; 3, determining the coal loading quantity and the coal loading density; 4, determining a coke quenching mode; 5, determining a sample preparation method; step 6, detecting the number of samples; step 7, setting a hearth constant temperature area; 8, a temperature control thermocouple; step 9, reaction gas; and step 10, standard screening. The method for improving the detection precision of the thermal performance of the coking coal and the metallurgical coke is provided by combing and analyzing the whole detection process of the thermal performance of the coking coal and the metallurgical coke, the patent method is provided for scientific and economic use of the coking coal, the application prospect is wide, considerable economic benefits are created, and the method is suitable for popularization and application. And good social benefits are generated.

Description

Technical Field

[0001] The invention belongs to the technical field of coking coal performance evaluation and coal blending for coking, and in particular relates to a method for improving the detection accuracy of thermal properties of coking coal. Background Art

[0002] Coking coal is the raw material for metallurgical coke production, and its thermal properties directly influence and restrict the thermal properties of metallurgical coke. Metallurgical coke is a core raw material for steel production, a pillar industry of the national economy. It is irreplaceable and plays a vital role in supporting the development of the steel industry. Metallurgical coke serves as a heat source, reducing agent, material column skeleton, and penetrant in blast furnace smelting. It is also the most important parameter control tool for the blast furnace production process. With the recent development and advancement of blast furnace smelting technology, particularly the rapid development of larger blast furnaces, high blast temperature technology, and oxygen-enriched coal injection technology, coke, as the skeleton of the material column within the blast furnace, has become more prominent in ensuring air and liquid permeability within the blast furnace. The thermal properties of coke (reactivity index (CRI) and post-reaction strength (CSR)) have a significant impact on the modern blast furnace smelting process and have become a key factor in ensuring stable, balanced, high-quality, and efficient production of hot metal. The ironmaking and coking industries have reached an unprecedented level of awareness of their importance and reliance on these parameters.

[0003] Current standards for testing metallurgical coke reactivity (Coke Reactivity Index CRI%) and coke strength after reaction (Coke Strength after Reaction CSR%) were developed based on the "Test Method for the Post-CO2 Strength of Blast Furnace Coke," published by Nippon Steel Corporation (NSC) in the Journal of the Fuel Association in 1982. The principle of this test method is to weigh a 200g lump coke sample, place it in a reactor, and react it with CO2 (5L / min) at 1100°C for 2 hours. The coke reactivity index (CRI) is expressed as the percentage of coke mass loss. The coke is then subjected to a drum test, and the coke strength after reaction (CSR) is expressed as the percentage of coke with a particle size greater than 10mm in the post-reaction coke mass. Upon its release, the NSC method, by revealing the high-temperature CO2 melting process of coke in blast furnaces, significantly advanced previous understanding of coke behavior and the simulation of its parameters in blast furnaces. It has since gained widespread recognition and acclaim in the coking and ironmaking industries, and has been adopted and standardized by global organizations and countries. The International Institute for Standards adopted it as ISO 18894:2006, and the American Society for Testing and Materials revised it as ASTM D5341-93a. In 1983, my country, with appropriate adjustments, revised it into the national standard "Coke Reactivity and Post-Reaction Strength GB / T4000," with subsequent revisions in 1996, 2008, and 2017.

[0004] The testing principles of various chemical testing agencies for coke thermal properties are consistent, and they all implement the national standard "Coke Reactivity and Post-Reaction Strength GB / T4000". However, due to the long process of coking coal testing, from sample preparation, coke smelting to test sample preparation, thermal performance testing heating and high-temperature reaction, etc., the process is long, with many test control points and complex influencing factors. Therefore, the reproducibility of test data varies greatly, which has become the biggest problem facing coke users, production enterprises, traders and testing agencies. They do not trust each other, which seriously affects the production, consumption and trading of coking coal and metallurgical coke.

[0005] Therefore, in order to solve such problems, we propose a method to improve the accuracy of thermal property detection of coking coal and metallurgical coke. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for improving the detection accuracy of thermal properties of coking coal to solve the problems existing in the above-mentioned prior art. The method is scientific and rigorous, and the characterization is intuitive.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for improving the accuracy of thermal property detection of coking coal, comprising the following steps:

[0009] Step 1: determine the type of coke oven to be tested;

[0010] Domestic test coke ovens are generally divided by the amount of coal loaded. Currently, the test coke ovens used in the coal industry and coking industry include 20Kg, 40Kg, 200Kg, and 300Kg types, of which the 40Kg test coke oven is the most commonly used type.

[0011] Step 2, Impact of Temperature Control Program

[0012] Clarify the heating procedure;

[0013] Step 3: Determine the coal loading quantity and density

[0014] Approved coal loading quantity: When the coal loading quantity is less than the approved coal loading quantity, the coke maturation speed will be accelerated, the coke lump size will be reduced, and the strength will increase; when the coal loading quantity is greater than the approved coal loading quantity, the coke maturity will be reduced, the coke volatile matter will increase, and the coke hot strength will decrease;

[0015] Approved coal charging density: The bulk density of the commonly used non-ramming type 40kg test coke oven charge is between 0.745kg / cm3 and 0.760kg / cm3, and the bulk density of the ramming type test coke oven charge is between 0.95kg / cm3 and 1.05kg / cm3;

[0016] Step 4: Determine the quenching method

[0017] Step 5: Clarify the sample preparation method

[0018] Four sample preparation methods: manual ball-smashing and trimming sample preparation method, mechanical sample preparation method, jaw crusher sample preparation method, jaw crusher crushing and trimming sample preparation method;

[0019] Step 6: The number of pieces of the test sample is determined to be equal to or less than one piece of the coke test sample.

[0020] Step 7, furnace constant temperature zone, the core control point is the control of the reactor furnace constant temperature zone, to ensure that the coke thermal performance tester reactor is in the constant temperature zone of 1100 ℃, the temperature control variation is within ± 3 ℃;

[0021] Step 8, Temperature Control Thermocouple

[0022] The thermocouple must be a φ0.5mm S-type thermocouple;

[0023] Step 9, reaction gas

[0024] The purity is not less than 99.99%. Before CO2 gas ventilation, the outlet of the CO2 cylinder should be preheated with an electric heating pressure reducing valve to ensure the stability of the gas flow.

[0025] Step 10, Standard Sieve

[0026] The size of the sieve aperture of the standard sieve should be checked regularly, and the standard sieve should be calibrated by a qualified measurement unit before use.

[0027] Furthermore, in step 1, the 40 kg test coke oven has a load type and a non-load type; the test coke oven has a ramming type and a non-ramming type.

[0028] Furthermore, in the step 2, the constant temperature time of the heating end point temperature of 1050°C is the so-called "stewing time" in the industry. Currently, there are several heating temperature control programs for the constant temperature time of 1050°C, such as 80min, 120min and 200min; the total heating time is clarified. Currently, the total heating time is generally 15.5h, 16.5h, 17.5h and the like.

[0029] Furthermore, in step 7, the length of the constant temperature zone of the furnace must be approximately 150 mm; and the calibration period of the constant temperature zone of the furnace must not exceed 3 months.

[0030] Furthermore, in step 7, after the heating rod is replaced, the constant temperature zone of the furnace should be calibrated before performing sample testing.

[0031] Furthermore, in step 8, the junction of the thermocouple is spherical and must be located at the top of the corundum sleeve to ensure the accuracy of the measurement position.

[0032] Furthermore, in step 8, the distance between the inner thread and the top of the casing is to prevent the distance from being too large to affect the temperature collection;

[0033] Calibration of thermocouples: Thermocouples that are normally used must be sent to a qualified testing unit for calibration once a year and can continue to be used only after a certificate of qualification is issued. The calibration results are generally determined to determine whether they meet the requirements based on the calibration regulations, with the temperature deviation of the 600-1600℃ detection point not exceeding ±0.25×t, where t is the detection point temperature.

[0034] Furthermore, in step 8:

[0035] The compensation wire of the thermocouple is a pair of wires with an insulation layer that has the same thermoelectromotive force value as the matched thermocouple within a certain temperature range;

[0036] The compensation wire must be selected correctly according to the type of thermocouple used and the occasion in which it is used. S-type thermocouples must use S-type compensation wires, and K-type thermocouples must use K-type compensation wires.

[0037] Furthermore, in step 10, a reasonable periodic inspection should be established for the standard sieves that are frequently used for a large number of samples to ensure the standard of the standard sieve aperture.

[0038] Compared with the prior art, the present invention has the following beneficial technical effects:

[0039] The present invention analyzes the entire process of thermal performance testing of coking coal and metallurgical coke, proposes a method for improving the accuracy of thermal performance testing of coking coal and metallurgical coke, and proposes a patented method for the scientific and economical use of coking coal. This method has broad application prospects, creates considerable economic benefits, and produces good social benefits. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the patented technology of the present invention, the thermal performance test process of coking coal purchased by a coking plant of a steel joint enterprise is used to accurately test the process, ensure the accuracy of the test data, and improve the test accuracy, and further explain the patented technology of the present invention.

[0041] Step 1: Determine the type of test coke oven

[0042] Domestic test coke ovens are generally classified by coal charge. Currently, the coal and coking industries use test coke ovens with capacities of 20 kg, 40 kg, 200 kg, and 300 kg. The 40 kg test coke oven is a recent development in modern coal-blended coking testing and has been widely recognized within the coking industry. Its primary advantage lies in its moderate coal charge and good data correlation, making it the most widely used and predominant type for coal-blended coking testing. Coke thermal properties vary significantly between different oven types due to differences in coal charge, resulting in factors such as coking coal density, chimney suction, and smelting processes. The general trend is that, under otherwise identical conditions, coke post-reaction strength (CSR) increases with increasing coal charge, but the degree of improvement is not proportional to the coal charge. Comparative tests of mechanical strength (M40, M10) and thermal properties (CRI, CSR) were conducted using coking coals of varying properties in 20 kg and 40 kg test coke ovens. See Table 1 for details.

[0043]

[0044] As can be seen from the above table, the mechanical strength and thermal properties of coke smelted in the 40K test coke oven are significantly better than those smelted in the 20K test coke oven, and the difference in thermal strength is more significant.

[0045] The load-type test coke oven has poor sensitivity to sample detection due to its use of a heating kettle-type progressive cooling method. The coking plant uses a bottom-mounted masonry test coke oven to detect the hot properties of purchased coking coal.

[0046] Step 2, Impact of Temperature Control Program

[0047] The heating program plays a key role in testing the thermal properties of coke from single-species coal coking. Coking single-species coal is essentially a high-temperature dry distillation process within a test coke oven, and temperature plays a decisive role in the maturation and performance of the coke. The 1050°C hold time and total heating time have a significant impact. The 1050°C hold time, commonly referred to in the industry as the "simmering time," currently has several heating control programs for 1050°C, including 80 minutes, 120 minutes, and 200 minutes. Total heating time generally ranges from 15.5 hours, 16.5 hours, and 17.5 hours. The effects of two different heating control programs on the thermal properties of coke from a 40kg test coke oven commonly used in the coal and coking industries, under otherwise identical testing conditions, are shown in Tables 2 and 3, respectively.

[0048] Table 2 40Kg test coke oven with two different heating control programs

[0049] Critical Control Points Temperature control program 1 Temperature control program 2 Stewing time min 80 200 Total heating time h 15.5 17.5

[0050] Table 3 Coke mass of 40 kg test coke oven under two different heating control procedures

[0051]

[0052] From the data in the table above, we can clearly see that the two heating control programs have different critical control points. When all other test conditions are the same, the thermal properties of coke, especially the post-reaction strength, vary greatly, with the maximum value differing by 7.3% and the minimum value differing by 3.1%. This is enough to illustrate that the critical control points of the temperature control program have an important influence on the thermal properties of coke.

[0053] The coking plant uses temperature control program 1 to detect the hot properties of purchased coking coal.

[0054] Step 3: Determine the coal loading quantity and density

[0055] Coal charge has a significant impact on the thermal properties of metallurgical coke in the test coke oven and is a key parameter for setting the parameters of the test coke oven's heating and temperature control program. Conversely, once the test coke oven's heating and temperature control program parameters have been set, coal charge becomes one of the key factors influencing the thermal properties of metallurgical coke. When the coal charge is less than the approved charge, the coke matures faster, the coke size decreases, and the strength increases. When the coal charge exceeds the approved charge, the coke may become less mature, the volatile matter increases, and the hot strength may decrease.

[0056] The bulk density of the non-rammed 40kg test coke ovens currently used on the market ranges from 0.745kg / cm³ to 0.760kg / cm³. Increasing bulk density improves the colloid meltability of the coking coal, increases mesophase formation, increases colloid pressure, increases coke density, and improves the thermal properties of the coke. As the bulk density of the coke oven increases, the thermal properties of the coke improve accordingly. Coke produced in a rammed 40kg test coke oven has better thermal properties than coke produced in a non-rammed 40kg test coke oven. Table 4 shows the thermal properties of coke produced in different bulk densities using the same coking coal.

[0057] Table 4 Hot properties of coke produced from the same coking coal at different bulk densities

[0058] Furnace density kg / cm3 CRI% CSR% 0.74 30.2 55.7 0.75 28.4 57.4 0.80 25.1 59.8 0.85 21.6 62.9 0.90 19.8 65.2

[0059] Step 4: Determine the quenching method

[0060] Currently, there are two main coke quenching methods used in experimental coke ovens: wet quenching and dry quenching. These two different quenching methods significantly affect the thermal properties of the coke. Generally speaking, dry-quenched coke exhibits better thermal properties than wet-quenched coke. The quenching method significantly affects the coke's pore structure. During wet quenching, quenching water is sprayed onto the hot coke. Simultaneously, due to the rapid cooling, the coke agglomerates cool and contract, increasing internal stress in the coke, creating numerous cracks and forming numerous pores. Furthermore, some water vapor chemically reacts with the coke, further generating numerous pores. Dry quenching, on the other hand, quenches the coke through heat exchange between an inert gas and the coke. The coke cools very slowly, resulting in minimal thermal stress and fewer cracks and pores. This is why dry quenching improves coke quality. A comparison of the coke pore structure and thermal properties of the two different quenching methods is shown in Tables 5 and 6.

[0061] Table 5 Comparative analysis of pores between dry quenching and wet quenching

[0062]

[0063]

[0064] Table 6 Comparison of thermal reaction intensity between dry quenching and wet quenching

[0065]

[0066] Step 5: Clarify the sample preparation method

[0067] Sample preparation is a critical operation in coke hot performance testing, significantly impacting test values. The national standard stipulates, "Coke should be formed into approximately spherical particles measuring 23mm-25mm. Mechanical sample preparation should be carried out in accordance with the requirements of YB / T4494." The national standard also stipulates, "Take the φ23mm oversize, remove thin flakes and thin strips, retain the thicker flakes and coarser strips, and manually trim the coke granules. Sieve through a φ23mm round sieve and mix with the untrimmed granules." The national standard also stipulates, "Take the φ21mm oversize, remove flakes and strips, and reduce them to obtain 2kg coke lumps." Four sampling methods are currently available: manual balling, mechanical sampling, jaw crusher sampling, and jaw crusher balling. When different sample preparation methods are used for the same type of coke, the reproducibility of the reactivity (CRI) and post-reaction strength (CSR) during the coke hot performance test varies significantly, all other conditions remaining the same. Of the four different sample preparation methods, the manual ball-smashing method has the best repeatability, but the coke's hot performance tends to be better, with values ​​slightly higher than those of the other sample preparation methods. This leads to some disagreement within the coal supply and coking industries. Currently, the more commonly used methods are jaw crusher ball-smashing and mechanical sample preparation. See Table 7 for the hot performance of the same type of coke using different sample preparation methods.

[0068] Table 7 Hot properties of the same coke with different sample preparation methods

[0069] Sample preparation method CRI% CSR% Purely manual ball-smashing and sample-making method 20.7 67.4 Mechanical sample preparation method 22.8 65.5 Jaw crusher sampling method 25.1 60.4 Jaw Crusher Crushing Ball Sample Preparation Method 23.7 62.1 Range 4.4 7.0

[0070] Step 6: Detect the number of samples

[0071] For the same sample, varying the number of coke particles fed into the reactor can have a certain impact on the test data. Generally speaking, the more coke particles fed into the reactor, the worse the thermal performance data, and vice versa. This is because the coke mass required for thermal performance testing is 200g. For the same mass of coke particles, the lighter the coke matrix, the more porosity the coke will have, resulting in greater melt loss during the thermal performance test and CO2 reaction, and lower coke strength after the reaction. National standards stipulate that the difference in coke particles should not exceed one particle.

[0072] Step 7, furnace constant temperature zone

[0073] Coke thermal performance testing involves measuring the melting loss of coke during its reaction with CO2 at a specified temperature within a specific reactor. The reaction temperature between coke and CO2 is crucial and one of the core parameters affecting coke's thermal performance. The key control point lies in the constant temperature zone of the reactor furnace. The reactor of the coke thermal performance tester must be kept within a constant temperature zone of 1100°C, with temperature fluctuations within ±3°C. The reactor is 500mm deep, and the height of a 200g sample is approximately 100mm. Therefore, the length of the furnace's constant temperature zone must be approximately 150mm. Regular calibration of the furnace's constant temperature zone is required during routine testing to ensure that the sample remains within the constant temperature zone during testing.

[0074] Step 8, Temperature Control Thermocouple

[0075] The temperature of the coke hot performance tester is controlled by a thermocouple. The quality of the thermocouple and its operation during use have a significant impact on the coke hot performance test. To ensure accurate control of the reaction temperature during the test, the following aspects of the thermocouple should be paid attention to.

[0076] Selection of thermocouple: The thermocouple must be S-type thermocouple with φ0.5mm.

[0077] Thermocouple size requirements: The thermocouple's junction is spherical (temperature measurement point) and must be located at the top of the corundum sheath to ensure accurate measurement. At the same time, the distance between the inner wire and the top of the sheath must be carefully considered to prevent excessive distance, which could affect temperature acquisition. During the coke thermal performance test, the thermocouple is inserted into the center of the coke layer, a constant temperature zone that reflects the true reaction temperature. If the thermocouple wire is too short and the outer sheath is of constant length, the distance from the top will be too large, causing distortion in the constant temperature zone, resulting in the temperature displayed in the coke layer not reflecting the true temperature.

[0078] Thermocouple calibration: Thermocouples in normal use must be sent to a qualified testing unit for calibration once a year. They can only continue to be used after a certificate of compliance is issued. The calibration results are generally based on the verification regulations, which require that the temperature deviation of the 600-1600℃ test point should not exceed ±0.25×t (t is the test point temperature) to determine whether they meet the requirements.

[0079] Compensation wire: A pair of insulated conductors with the same thermoelectromotive force as the thermocouple within a certain temperature range. Connecting a thermocouple to a temperature measuring instrument, it can compensate for errors caused by temperature changes at the connection between the secondary instrument and the thermocouple. Compensation wires must be selected based on the type of thermocouple used and the application. S-type thermocouples must use S-type compensation wire, and K-type thermocouples must use K-type compensation wire. Incorrect selection of compensation wire will directly cause the displayed temperature to differ from the actual temperature.

[0080] Step 9, reaction gas

[0081] Two gases are used during the coke hot performance test: N2 and CO2. N2 serves as a protective gas before the reaction, preventing the coke from undergoing redox reactions with air before the reaction reaches 1100°C and during cooling after the reaction. CO2 serves as a reactive gas, reacting with the coke at 1100°C for 2 hours. The purity of N2 has a certain impact on the test results, particularly the CRI. The lower the purity, the higher the measured CRI. Therefore, N2 with a purity less than 99.99% should be purified to remove oxygen and moisture. The CO2 flow rate must be stable and accurate, and the purity must meet the required level, not less than 99.99%. Insufficient CO2 flow results in low reactivity and high post-reaction strength, while excessive CO2 flow has the opposite effect. Before CO2 gas flow, an electrically heated pressure reducing valve should be used to preheat the CO2 cylinder outlet to ensure a stable gas flow. The lower the CO2 purity, the better the measured coke hot performance. Ensure that the CO2 purity meets the technical requirements during testing.

[0082] Step 10, Standard Sieve

[0083] During the coke hot performance test, 23mm and 25mm standard sieves are used during the sampling process. After the coke passes through the Type I drum after reaction, a 10mm standard sieve is used to calculate the post-reaction strength. The standard sieve aperture size should be regularly checked and calibrated by a qualified metrology agency before use. For standard sieves used frequently for a large number of samples, reasonable periodic inspections should be established to ensure the standard sieve aperture size. Longer use of the standard sieve during sample preparation increases the aperture size of the standard sieve, which in turn increases the aperture size of the sample. This may result in improved coke hot performance due to increased coke size, increased density, and improved resistance to melting loss. Furthermore, the increased coke size during the reaction process reduces the specific surface area, resulting in improved coke post-reaction strength. After the coke passes through the Type I drum after reaction, a 10mm standard sieve is used to calculate the post-reaction strength. Due to the increased aperture size, the oversize decreases, resulting in a decrease in post-reaction strength.

[0084] The present invention analyzes the entire process of thermal performance testing of coking coal and metallurgical coke, proposes a method for improving the accuracy of thermal performance testing of coking coal and metallurgical coke, and proposes a patented method for the scientific and economical use of coking coal. This method has broad application prospects, creates considerable economic benefits, and produces good social benefits.

[0085] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for improving the accuracy of thermal property testing of coking coal, characterized by: The steps include: Step 1: determine the type of coke oven to be tested; Domestic test coke ovens are generally divided by the amount of coal loaded. Currently, the test coke ovens used in the coal industry and coking industry include 20Kg, 40Kg, 200Kg, and 300Kg types, of which the 40Kg test coke oven is the most commonly used type. Step 2, Impact of Temperature Control Program Clarify the heating procedure; Step 3: Determine the coal loading quantity and density Approved coal loading quantity: When the coal loading quantity is less than the approved coal loading quantity, the coke maturation speed will be accelerated, the coke lump size will be reduced, and the strength will increase; when the coal loading quantity is greater than the approved coal loading quantity, the coke maturity will be reduced, the coke volatile matter will increase, and the coke hot strength will decrease; Approved coal charging density: The bulk density of the commonly used non-ramming type 40kg test coke oven charge is between 0.745kg / cm3 and 0.760kg / cm3, and the bulk density of the ramming type test coke oven charge is between 0.95kg / cm3 and 1.05kg / cm3; Step 4: Determine the quenching method Step 5: Clarify the sample preparation method Four sample preparation methods: manual ball-smashing and trimming sample preparation method, mechanical sample preparation method, jaw crusher sample preparation method, jaw crusher crushing and trimming sample preparation method; Step 6: The number of pieces of the test sample is determined to be equal to or less than one piece of the coke test sample. Step 7, furnace constant temperature zone, the core control point is the control of the reactor furnace constant temperature zone, to ensure that the coke thermal performance tester reactor is in the constant temperature zone of 1100 ℃, the temperature control variation is within ± 3 ℃; Step 8, Temperature Control Thermocouple The thermocouple must be a φ0.5mm S-type thermocouple; Step 9, reaction gas The purity is not less than 99.99%. Before CO2 gas ventilation, the outlet of the CO2 cylinder should be preheated with an electric heating pressure reducing valve to ensure the stability of the gas flow. Step 10, Standard Sieve The size of the sieve aperture of the standard sieve should be checked regularly, and the standard sieve should be calibrated by a qualified measurement unit before use.

2. The method for improving the detection accuracy of thermal properties of coking coal according to claim 1, characterized in that: In step 1, the 40 kg test coke oven has a load type and a non-load type; the test coke oven has a tamping type and a non-tamping type.

3. The method for improving the detection accuracy of thermal properties of coking coal according to claim 1, characterized in that: In the step 2, the constant temperature time at the heating end point temperature of 1050°C is the so-called "stewing time" in the industry. Currently, there are several heating temperature control programs for the constant temperature time of 1050°C, including 80 minutes, 120 minutes and 200 minutes. The total heating time is specified. Currently, the total heating time is generally 15.5 hours, 16.5 hours and 17.5 hours.

4. The method for improving the detection accuracy of thermal properties of coking coal according to claim 1, characterized in that: In step 7, the length of the constant temperature zone of the furnace must be approximately 150 mm; and the calibration period of the constant temperature zone of the furnace must not exceed 3 months.

5. The method for improving the detection accuracy of thermal properties of coking coal according to claim 1, characterized in that: In step 7, after the heating rod is replaced, the constant temperature zone of the furnace should be calibrated before the sample test is performed.

6. The method for improving the detection accuracy of thermal properties of coking coal according to claim 1, characterized in that: In step 8, the junction of the thermocouple is spherical and must be located at the top of the corundum sleeve to ensure the accuracy of the measurement position.

7. The method for improving the detection accuracy of thermal properties of coking coal according to claim 1, characterized in that: In step 8, the distance between the inner thread and the top of the casing is too large to affect the temperature collection; Calibration of thermocouples: Thermocouples that are normally used must be sent to a qualified testing unit for calibration once a year and can continue to be used only after a certificate of qualification is issued. The calibration results are generally determined to determine whether they meet the requirements based on the calibration regulations, with the temperature deviation of the 600-1600℃ detection point not exceeding ±0.25×t, where t is the detection point temperature.

8. The method for improving the detection accuracy of thermal properties of coking coal according to claim 1, characterized in that: In step 8: The compensation wire of the thermocouple is a pair of wires with an insulation layer that has the same thermoelectromotive force value as the matched thermocouple within a certain temperature range; The compensation wire must be selected correctly according to the type of thermocouple used and the occasion in which it is used. S-type thermocouples must use S-type compensation wires, and K-type thermocouples must use K-type compensation wires.

9. The method for improving the detection accuracy of thermal properties of coking coal according to claim 1, characterized in that: In step 10, for the standard sieves that are frequently used with a large number of samples, reasonable periodic inspections should be established to ensure the standard of the standard sieve aperture.

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