A method for measuring the degradation process of coke for hydrogen-rich blast furnace

Abstract

A method for determining the deterioration process of coke for hydrogen-rich blast furnaces belongs to the technical field of iron and steel metallurgy. The technical problem to be solved is to provide a method for determining the deterioration process of coke for hydrogen-rich blast furnaces that can more realistically reflect the quality changes of coke under hydrogen-rich smelting conditions and provide technical support for the selection of coke for hydrogen-rich blast furnaces. The following steps are adopted to (1) prepare samples and load samples, (2) test, and (3) calculate the gasification rate of coke. The present invention simulates the dissolution behavior of the gasification reaction of coke with CO2 and H2O under hydrogen-rich blast furnace gas conditions, detects the effects of different temperatures, loads and atmospheres on the thermal properties of coke, and evaluates the deterioration performance of coke by deriving the gasification rate of coke through comprehensive analysis of multiple test results. The evaluation method more realistically reflects the deterioration process of coke in a hydrogen-rich blast furnace and opens up a new way for blast furnace coke quality detection.

Description

Technical Field

[0001] The invention relates to a method for determining a deterioration process of coke for a hydrogen-rich blast furnace, and belongs to the technical field of iron and steel metallurgy. Background Art

[0002] Reducing CO2 gas emissions and achieving low-carbon smelting are challenges and major demands faced by the development of the iron and steel metallurgical industry. The blast furnace hydrogen-rich smelting technology aims to replace carbon with hydrogen to increase the proportion of coal gas hydrogen reduction and achieve energy conservation and emission reduction. This has great value and practical significance for the steel industry to promote the realization of the "dual carbon" goal. At present, one of the bottleneck problems of blast furnace hydrogen-rich smelting technology is the imperfect basic reaction theory of the hydrogen-rich smelting process and the lack of understanding of the quality requirements of raw fuels under hydrogen-rich coal gas conditions.

[0003] Coke is the main raw material for blast furnace smelting. Its main functions in the blast furnace are heating agent, reducing agent, carburizing agent and skeleton function. The degradation of coke in the blast furnace is mainly affected by physical mechanical wear, load-bearing cracks, carburizing loss and chemical combustion loss, gasification reaction and reduction loss. The amount of physical and chemical loss of coke is different due to different working conditions in the blast furnace. Therefore, the requirements for coke quality in hydrogen-rich blast furnace and traditional blast furnace smelting are also different.

[0004] Under the condition of hydrogen-rich coal gas, the gasification and crushing of coke in the blast furnace are not independent processes, but they affect each other and occur simultaneously. The gasification reaction of coke is C+CO2=2CO, which is a reaction of increasing gas volume, that is, the pressure in the furnace and the amount of CO gas will affect the reaction. In the hydrogen-rich blast furnace, the H2O vapor generated by the indirect reduction of hydrogen will also react with coke to form C+H2O(g)=2CO(g). As the H2 content of coal gas increases, the coke degradation caused by H2O may be more obvious. Therefore, the coke quality requirements that match the blast furnace smelting process are different from those of traditional blast furnaces, and the coke quality indicators that can be accepted by hydrogen-rich blast furnaces are also different from those of traditional blast furnaces. Therefore, it is necessary to re-evaluate the relationship between the hydrogen content of coal gas and the quality of coke in hydrogen-rich blast furnaces. This requires a more reasonable method to study the degradation process of coke under hydrogen-rich coal gas conditions, and evaluate the quality of coke for hydrogen-rich blast furnaces on the basis of understanding the coke degradation process. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for determining the deterioration process of coke for hydrogen-rich blast furnaces, which can more truly reflect the quality changes of coke under hydrogen-rich smelting conditions and provide technical support for the selection of hydrogen-rich blast furnace coke.

[0006] The technical solution to solve the above technical problems is:

[0007] A method for determining the degradation process of coke for hydrogen-rich blast furnaces is carried out by the following steps:

[0008] (1) Sample preparation and sample loading

[0009] a. Prepare the sample: the particle size of the iron-containing raw material is 10-12.5 mm, the particle size of the coke sample is 12-14 mm, and the mass m1 and specific surface area s1 of the coke before the test are recorded;

[0010] b. The coke sample and the iron-containing raw material are loaded into the crucible, the bottom and upper layers are loaded with the iron-containing raw material, the coke sample is laid into the middle layer, and after loading, the crucible is placed in a pit-type high-temperature furnace;

[0011] (2) Test:

[0012] a. Apply 0.4-0.6kg / cm to the sample in the crucible 2 Inert gas is introduced into the crucible to form a protective atmosphere for the sample in the crucible, and the temperature is raised to 400-600°C;

[0013] b. Switch the inert gas to a reducing gas composed of N2, CO, H2, CO2 and H2O, and continue heating to 800-1000°C;

[0014] c. Increase the load on the sample to 0.9-1.1kg / cm 2 , stop introducing H2O into the crucible and continue heating to 1000-1100℃;

[0015] d. Continue to increase the load on the sample to 1.9-2.1kg / cm 2 , and at the same time, stop introducing CO2 into the crucible, and continue heating to the end temperature of the measurement, 1100-1350°C, switch the reducing atmosphere to an inert gas atmosphere, cool the sample to room temperature, and remove the load;

[0016] (3) Calculation of coke gasification rate

[0017] Take out the coke sample after the test, weigh it, and calculate the gasification rate R of the coke according to the following formula: C :

[0018]

[0019] Wherein, m1 is the mass of coke before the test, g; m2 is the remaining mass of coke after the test, g.

[0020] In the above-mentioned method for determining the degradation process of coke for hydrogen-rich blast furnace, in the step (1), the iron raw material can be one or more of iron ore, sintered ore or pelletized ore, and the thickness of each material layer is 20-50 mm; the specific surface area of ​​the coke is determined by a N2 adsorption instrument.

[0021] In the above method for determining the degradation process of hydrogen-rich blast furnace coke, the heating temperature rise rate in steps (2) a. and 2) b. is 9-11°C / min.

[0022] In the above-mentioned method for determining the degradation process of coke for hydrogen-rich blast furnace, in the step (2) b., the total flow rate of the reducing gas composed of N2, CO, H2, CO2 and H2O is 8L / min, wherein N2 is 4.0-3.6L / min, accounting for 50%-45% by volume, CO is 1.6L / min, accounting for 20% by volume, CO2 is 1.6L / min, accounting for 20% by volume, H2 is 0.4-0.6L / min, accounting for 5%-7.5% by volume, and H2O is 0.4-0.6L / min, accounting for 5%-7.5% by volume, and the sum of the volume proportions of each component is 100%.

[0023] In the above-mentioned method for determining the degradation process of coke for hydrogen-rich blast furnace, in the step (2) c., after stopping the introduction of H2 into the crucible, the components of the reducing gas are N2 4.0-3.6L / min, accounting for 50%-45% by volume, CO 1.6L / min, accounting for 20% by volume, CO2 1.6L / min, accounting for 20% by volume, H2 0.8-1.2L / min, accounting for 10%-15% by volume, and the sum of the volume proportions of each component is 100%; the heating rate of the crucible is 1.5-2.5℃ / min.

[0024] In the above-mentioned method for determining the degradation process of coke for hydrogen-rich blast furnace, in the step (2) d., after stopping the introduction of CO2 into the crucible, the components of the reducing gas are N2: 4.8-4.4L / min, accounting for 60%-55% by volume, CO 2.4L / min, accounting for 30% by volume, H2 0.8-1.2L / min, accounting for 10%-15% by volume, and the sum of the volume proportions of each component is 100%; the heating rate is 4-6℃ / min.

[0025] In the above-mentioned method for determining the degradation process of coke for hydrogen-rich blast furnace, in step (3)a and step (3)d, the flow rate of the inert gas is 2-3 L / min.

[0026] The above method for determining the degradation process of hydrogen-rich blast furnace coke is as follows: the specific surface area change rate S of the coke c for:

[0027]

[0028] Where s1 is the specific surface area of ​​coke before the test, mm 2 / g; s2 is the specific surface area of ​​coke after the test, mm 2 / g.

[0029] The above-mentioned method for measuring the degradation process of hydrogen-rich blast furnace coke is to take the average value of 4-6 measurement results to calculate the gasification rate and specific surface area change rate of the coke.

[0030] The beneficial effects of the present invention are:

[0031] The present invention simulates the dissolution behavior of the gasification reaction of coke with CO2 and H2O under the condition of hydrogen-rich blast furnace gas, detects the influence of different temperatures, loads and atmospheres on the thermal properties of coke, and evaluates the deterioration performance of coke by obtaining the gasification rate of coke through comprehensive analysis of multiple test results.

[0032] The method for determining the heat strength of coke after reaction of the present invention is aimed at the actual smelting conditions of a hydrogen-rich blast furnace. By changing the temperature, load and reducing atmosphere composition, the dissolution loss behavior of the gasification reaction of coke with CO2 and H2O under different working conditions is determined, and the degradation process of coke is analyzed according to the gasification rate and specific surface area of ​​the coke after reaction at different target temperatures. The greater the gasification rate and the larger the specific surface area, the more significant the degradation of the coke. At the same time, the temperature range corresponding to the significant degradation of the coke can also be obtained. And this is used to evaluate the degradation performance of coke, thereby changing the experimental conditions that are inconsistent with the actual blast furnace in the traditional method of using coke reactivity and post-reaction strength detection to evaluate the degradation performance of coke, so that the evaluation method can more truly reflect the degradation process of coke in a hydrogen-rich blast furnace, and open up a new way for blast furnace coke quality detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the device used in the test of the present invention;

[0034] Figure 2 Schematic diagram of material layer in crucible;

[0035] The markings in the figure are as follows: 1. Nitrogen cylinder, 2. CO cylinder, 3. CO2 cylinder, 4. H2 cylinder, 5. Water vapor generator, 6. Mixed gas pressure stabilizing device, 7. Heating pipe, 8. Thermocouple, 9. Pressure rod, 10. Material layer, bottom layer 10-1, middle layer 10-2, upper layer 10-3, 11. MoSi2 pit-type high temperature furnace, 12. Pressure device, 13. Displacement sensor, 14. Pressure sensor, 15. Data acquisition system, 16. Temperature control unit. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below through examples.

[0037] Example 1

[0038] The method for determining the degradation process of hydrogen-rich blast furnace coke of the present invention uses a test device such as Figure 1As shown. The inner diameter of the MoSi2 high temperature furnace crucible is Φ60mm and the height is 100mm. The following steps are used for measurement:

[0039] (1) Sample preparation and sample loading

[0040] a. Prepare samples: The weight of the iron ore sample is 200g, and the particle size is 11.0mm; the mass m1 of each group of coke samples is 50g, and the particle size is 12mm. Take 15 coke particles from the coke sample, 3 particles in a group, and divide them into 5 groups and place them in the N2 adsorption instrument for specific surface area measurement. The average value of the 5 measurement results is taken as the measurement value of the coke specific surface area s1. The average value of the 5 measurement results is 0.8cm 2 / g;

[0041] b. Load the coke sample and iron ore into the crucible, with 100g of iron ore in the bottom and upper layers, 20mm thick, and 50g of coke sample, 40mm thick, in the middle; after loading, place the crucible in the constant temperature zone of the MoSi2 high-temperature pit-type high-temperature furnace.

[0042] (2) Test:

[0043] a. Put the graphite pressure rod, pressure sensor 14, displacement sensor 13 and thermocouple 8 into the pressure device 12 in order, introduce N2 to replace the furnace gas, and check the air tightness by measuring the pressure difference inside and outside the high-temperature furnace. When the pressure difference inside and outside the furnace is ≥10kpa, start heating to 500℃ at a rate of 10℃ / min, and apply 0.4kg / cm 2 The load;

[0044] b. Switch the N2 introduced into reducing gas with a total flow rate of 8 L / min. The flow rates of the components are N2 4.0 L / min, accounting for 47.5% by volume, CO 1.6 L / min, accounting for 20% by volume, CO2 1.6 L / min, accounting for 20% by volume, H2 0.4 L / min, accounting for 5% by volume, H2O: 0.4 L / min, accounting for 7.5% by volume, and continue heating to 800 ° C.

[0045] c. Increase the load on the sample to 0.9kg / cm 2 , and at the same time, stop introducing H2 into the crucible, and continue heating to 1000℃; stop introducing H2O into the crucible, and the components of the reducing gas are N2 4.0L / min, accounting for 50% by volume, CO1.6L / min, accounting for 20% by volume, CO21.6L / min, accounting for 20% by volume, H20.8L / min, accounting for 10% by volume; the heating rate of the crucible is 2.5℃ / min.

[0046] d. Continue to increase the load on the sample to 1.9kg / cm2 At the same time, stop introducing CO2 into the crucible. The components of the reducing gas are N2: 4.8L / min, 60% by volume, CO 2.4L / min, 30% by volume, H2 0.8L / min, 10% by volume; continue heating at a rate of 6℃ / min to the end temperature of the measurement, 1100℃, and switch the reducing atmosphere to an inert gas atmosphere with a flow rate of 2-3L / min; cool the sample to room temperature and remove the load;

[0047] (3) Calculation of coke gasification rate

[0048] Take out the coke sample after the test and weigh it to be 42.6 grams. Calculate the gasification rate R of the coke. C :

[0049]

[0050] Wherein, m1 is the mass of coke before the test, g; m2 is the remaining mass of coke after the test, g.

[0051] Calculate the specific surface area change rate S of coke c :

[0052] Example 2

[0053] (1) Sample preparation and sample loading

[0054] a. Prepare samples: The weight of the iron ore sample is 200g, and the particle size is 11.0mm; the mass m1 of each group of coke samples is 50g, and the particle size is 12mm. Take 15 coke particles from the coke sample, 3 particles in a group, and divide them into 5 groups and place them in the N2 adsorption instrument for specific surface area measurement. The average value of the 5 measurement results is taken as the measurement value of the coke specific surface area s1. The average value of the 5 measurement results is 0.8cm 2 / g;

[0055] b. Load the coke sample and iron ore into the crucible, with 100g of iron ore in the bottom and upper layers, with a thickness of 20mm; 50g of coke sample, with a thickness of 40mm, is laid in the middle; after loading, place the crucible in the constant temperature zone of the MoSi2 high-temperature pit-type high-temperature furnace.

[0056] (2) Test:

[0057] a. Put the graphite pressure rod, pressure sensor 14, displacement sensor 13 and thermocouple 8 into the pressure device 12 in order, introduce N2 to replace the furnace gas, and check the air tightness by measuring the pressure difference inside and outside the high-temperature furnace. When the pressure difference inside and outside the furnace is ≥10kpa, start heating to 500℃ at a rate of 10℃ / min, and apply 0.5kg / cm 2 The load;

[0058] b. Switch the N2 introduced into reducing gas with a total flow rate of 8 L / min. The flow rates of the components are N2 3.8 L / min, accounting for 47.5% by volume, CO 1.6 L / min, accounting for 20% by volume, CO2 1.6 L / min, accounting for 20% by volume, H2 0.5 L / min, accounting for 6.25% by volume, H2O: 0.5 L / min, accounting for 6.25% by volume, and continue heating to 900 ° C.

[0059] c. Increase the load on the sample to 1.0kg / cm 2 , and at the same time, stop introducing H2 into the crucible, and continue heating to 1100℃; stop introducing H2O into the crucible, and the components of the reducing gas are N2 3.8L / min, accounting for 47.5% by volume, CO1.6L / min, accounting for 20% by volume, CO21.6L / min, accounting for 20% by volume, H2 1.0L / min, accounting for 12.5% ​​by volume; the crucible heating rate is 2.0℃ / min.

[0060] d. Continue to increase the load on the sample to 2.0kg / cm 2 At the same time, stop introducing CO2 into the crucible. The components of the reducing gas are N2: 4.4L / min, 57.5% by volume, CO 2.4L / min, 30% by volume, H2 1.0L / min, 12.5% ​​by volume; continue heating at a rate of 5℃ / min to the end temperature of the measurement, 1200℃, and switch the reducing atmosphere to an inert gas atmosphere with a flow rate of 2-3L / min; cool the sample to room temperature and remove the load;

[0061] (3) Calculation of coke gasification rate

[0062] Take out the coke sample after the test and weigh it to be 38.4 grams. Calculate the gasification rate RC of the coke:

[0063]

[0064] Wherein, m1 is the mass of coke before the test, g; m2 is the remaining mass of coke after the test, g.

[0065] Calculate the specific surface area change rate S of coke c :

[0066] Example 3

[0067] The method for determining the degradation process of hydrogen-rich blast furnace coke of the present invention uses a test device such as Figure 1As shown. The inner diameter of the MoSi2 high temperature furnace crucible is Φ60mm and the height is 100mm. The following steps are used for measurement:

[0068] (1) Sample preparation and sample loading

[0069] a. Prepare samples: The weight of the iron ore sample is 200g, and the particle size is 11.0mm; the mass m1 of each group of coke samples is 50g, and the particle size is 12mm. Take 15 coke particles from the coke sample, 3 particles in a group, and divide them into 5 groups and place them in the N2 adsorption instrument for specific surface area measurement. The average value of the 5 measurement results is taken as the measurement value of the coke specific surface area s1. The average value of the 5 measurement results is 0.8cm 2 / g;

[0070] b. Load the coke sample and iron ore into the crucible, with 100g and 20mm of iron ore in the bottom and upper layers respectively; 50g and 40mm of coke sample are placed in the middle; after loading, place the crucible in the constant temperature zone of the MoSi2 high-temperature pit-type high-temperature furnace.

[0071] (2) Test:

[0072] a. Put the graphite pressure rod, pressure sensor 14, displacement sensor 13 and thermocouple 8 into the pressure device 12 in order, introduce N2 to replace the furnace gas, and check the air tightness by measuring the pressure difference inside and outside the high-temperature furnace. When the pressure difference inside and outside the furnace is ≥10kpa, start heating to 500℃ at a rate of 10℃ / min, and apply 0.6kg / cm 2 The load;

[0073] b. Switch the N2 introduced into reducing gas with a total flow rate of 8 L / min. The flow rates of the components are N2 3.6 L / min, accounting for 45% by volume, CO 1.6 L / min, accounting for 20% by volume, CO2 1.6 L / min, accounting for 20% by volume, H2 0.6 L / min, accounting for 7.5% by volume, H2O: 0.6 L / min, accounting for 7.5% by volume, and continue heating to 1000°C.

[0074] c. Increase the load on the sample to 1.1kg / cm 2 , and at the same time, stop introducing H2 into the crucible, and continue heating to 1100℃; stop introducing H2O into the crucible, the reducing gas components are N2 3.6L / min, accounting for 45% by volume, CO1.6L / min, accounting for 20% by volume, CO21.6L / min, accounting for 20% by volume, H21.2L / min, accounting for 15% by volume; the crucible heating rate is 1.5℃ / min.

[0075] d. Continue to increase the load on the sample to 2.1kg / cm2 At the same time, stop introducing CO2 into the crucible. The components of the reducing gas are N2: 4.4L / min, 55% by volume, CO 2.4L / min, 30% by volume, H2 1.2L / min, 15% by volume; continue heating at a rate of 4℃ / min to the end temperature of the measurement, 1350℃, and switch the reducing atmosphere to an inert gas atmosphere with a flow rate of 2-3L / min; cool the sample to room temperature and remove the load;

[0076] (3) Calculation of coke gasification rate

[0077] Take out the coke sample after the test and weigh it to be 35.2 grams. Calculate the gasification rate R of the coke. C :

[0078]

[0079] Wherein, m1 is the mass of coke before the test, g; m2 is the remaining mass of coke after the test, g.

[0080] Calculate the specific surface area change rate S of coke c :

Claims

1. A method for measuring the degradation process of coke for hydrogen-rich blast furnace, characterized in that: The following steps are used: (1) Sample preparation and sample loading a. Prepare samples: the particle size of the iron-containing raw material is 10-12.5 mm, the particle size of the coke sample is 12-14 mm, and the mass m1 and specific surface area s1 of the coke before the test are recorded; b. The coke sample and the iron-containing raw material are loaded into the crucible, the bottom layer (10-1) and the upper layer (10-3) are loaded with the iron-containing raw material, and the coke sample is laid into the middle layer (10-2); after loading, the crucible is placed in a pit-type high-temperature furnace; (2) Test: a. Apply 0.4-0.6kg / cm to the sample in the crucible 2 Inert gas is introduced into the crucible to form a protective atmosphere for the sample in the crucible, and the temperature is raised to 400-600°C; b. Switch the inert gas to a reducing gas composed of N2, CO, H2, CO2 and H2O, and continue heating to 800-1000°C; In the step (2) b., the total flow rate of the reducing gas composed of N2, CO, H2, CO2 and H2O is 8 L / min, wherein N2 is 4.0-3.6 L / min, accounting for 50%-45% by volume, CO is 1.6 L / min, accounting for 20% by volume, CO2 is 1.6 L / min, accounting for 20% by volume, H2 is 0.4-0.6 L / min, accounting for 5%-7.5% by volume, and H2O is 0.4-0.6 L / min, accounting for 5%-7.5% by volume, and the sum of the volume proportions of each component is 100%; c. Increase the load on the sample to 0.9-1.1kg / cm 2 , stop introducing H2O into the crucible and continue heating to 1000-1100℃; d. Continue to increase the load on the sample to 1.9-2.1kg / cm 2 , and at the same time, stop introducing CO2 into the crucible, and continue heating to the end temperature of the measurement, 1100-1350°C, switch the reducing atmosphere to an inert gas atmosphere, cool the sample to room temperature, and remove the load; (3) Calculation of coke gasification rate Take out the coke sample after the test, weigh it, and calculate the gasification rate R of the coke according to the following formula: C : Wherein, m1 is the mass of coke before the test, g; m2 is the remaining mass of coke after the test, g.

2. The method for measuring the degradation process of hydrogen-rich blast furnace coke according to claim 1, characterized in that: In the step (1), the iron-containing raw material is one or more of iron ore, sintered ore or pelletized ore, and the thickness of each material layer is 20-50 mm; the specific surface area of ​​the coke is measured using a N2 adsorption instrument.

3. The method for measuring the degradation process of hydrogen-rich blast furnace coke according to claim 1, characterized in that: The heating rate in steps (2) a. and 2) b. is 9-11°C / min.

4. The method for measuring the degradation process of hydrogen-rich blast furnace coke according to claim 1, characterized in that: In the step (2) c., after stopping the introduction of H2O into the crucible, the components of the reducing gas are N2 4.0-3.6 L / min, accounting for 50%-45% by volume, CO 1.6 L / min, accounting for 20% by volume, CO2 1.6 L / min, accounting for 20% by volume, H2 0.8-1.2 L / min, accounting for 10%-15% by volume, and the sum of the volume proportions of each component is 100%; The crucible is heated at a rate of 1.5-2.5°C / min.

5. The method for measuring the degradation process of hydrogen-rich blast furnace coke according to claim 1, characterized in that: In the step (2) d., after the introduction of CO2 into the crucible is stopped, the components of the reducing gas are N2: 4.8-4.4 L / min, accounting for 60%-55% by volume, CO 2.4 L / min, accounting for 30% by volume, H2 0.8-1.2 L / mi, accounting for 10%-15% by volume, and the sum of the volume proportions of each component is 100%; the heating rate is 4-6°C / min.

6. The method for measuring the degradation process of hydrogen-rich blast furnace coke according to claim 1, characterized in that: In the steps (2)a and (2)d, the flow rate of the inert gas is 2-3 L / min.

7. The method for measuring the degradation process of hydrogen-rich blast furnace coke according to any one of claims 1 to 6, characterized in that: The change rate of specific surface area of ​​coke Sc is: Where s1 is the specific surface area of ​​coke before the test, mm 2 / g; s2 is the specific surface area of ​​coke after the test, mm 2 / g.

8. The method for measuring the degradation process of hydrogen-rich blast furnace coke according to any one of claims 1 to 6, characterized in that: The change rate of the specific surface area of ​​coke was calculated by taking the average value of 4-6 measurement results.

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