Heat recovery coke oven coal blending method based on coal coking function

Abstract

The invention discloses a heat recovery coke oven coal blending method based on coking coal functions. The method comprises the following steps: classifying coking coals according to the functions of the coking coals in coking coal blending and coking processes; the coking coals are divided into a first type of coking coals (HPR) for regulating and controlling porosity and improving reactivity, a second type of coking coals (FW) for providing skeleton action, a third type of coking coals (CP) for providing cohesiveness, a fourth type of coking coals (HF) with high fluidity and cohesiveness for providing high inert capacity, a fifth type of low-volatile coals (LRV) for reducing reactivity and a sixth type of low-ash low-sulfur high-volatile coals (LSHV); the method comprises the following steps: respectively pre-crushing and blending first-class coking coal (HPR), fifth-class coking coal (LRV) and sixth-class coking coal (LSHV), so that the G value of the blended coal is 58-78, the Y value of the blended coal is 11-16mm, and the volatile component Vdaf of the blended coal is 22-27%; then crushing (mixing) according to a heat recovery coke oven process, wherein the crushing fineness is lt; 3 mm of the raw materials account for 90%-95%, then tamping is conducted, the tamping density is 0.95-1.15 ton / m < 3 >, and finally the raw materials are charged into a furnace to be subjected to coking production. And the qualified metallurgical coke with M40 greater than 88%, M10 less than 7.5%, CRI greater than 20% and CSR greater than 58% can be produced. The method specifically regulates and controls the quality index of the coke, so that the coke meets the blast furnace smelting requirement.

Description

Technical Field

[0001] The invention relates to a coke oven coal blending method based on the heat recovery function of coking coal, belonging to the technical field of coking coal blending. Background Art

[0002] China's heat recovery coke oven technology adopts the process of ramming thick coal cakes, heating from top to bottom, long coking cycle, and negative pressure operation throughout the process. All the raw coal gas produced during the coking process is burned in the furnace, and the high-temperature exhaust gas generated is used to generate steam for power generation or external steam supply through waste heat recovery. The exhaust gas is discharged after desulfurization and denitrification treatment and meets the emission standards. The red-hot coke uses the dry quenching process to cool the coke while generating steam and connecting it to the grid with the above-mentioned high-temperature exhaust gas waste heat recovery steam. No process wastewater is generated during the entire production process, which is an environmentally friendly coking process. Since there is an arched space above the rammed coal cakes in the heat recovery coke oven, the raw coal gas is initially burned and heated in the arched space for coking, and the coal cakes can expand freely upward. Therefore, the expansion pressure of the mixed coal will not affect the side furnace wall and coke pushing, and coal with large expansion and high expansion pressure can be added to the coal blending. In addition, due to the use of the ramming process, low-bonding or non-bonding coal can be added in a high proportion in the coal blending. Since the coal distribution structure and production process of heat recovery coke ovens are different from those of conventional top-loading coke ovens and ramming coke ovens, the quality of the coke produced is also significantly different from that of conventional top-loading coke ovens and ramming coke ovens. Specifically, it has high cold strength, wide fluctuation range of thermal performance, low porosity, high apparent density, and high bulk density. The behavior of heat recovery coke oven coke in the blast furnace is also different from that of conventional top-loading coke ovens and ramming coke ovens, which is manifested in poor blast furnace permeability, inactive furnace hearth, small tuyere whirlpool zone, slow combustion speed, slow re-airing after blast furnace shutdown, and other problems, which seriously affect the smooth operation of the blast furnace and efficient and low-cost operation.

[0003] Heat recovery coke ovens have the advantages of low environmental impact and the ability to use weakly viscous or non-viscous coal in a larger proportion, and have been developed to a certain extent in China and other countries. At present, the output of coke from heat recovery coke ovens accounts for only 2.5% of China's coke output, which is a very low proportion. Although the traditional quality indicators of the obtained coke can meet the requirements of blast furnaces, blast furnace smelting problems frequently occur. Therefore, heat recovery coke oven coke is now mostly used as coke for blast furnace smelting. The present invention targets the needs of blast furnace smelting, and achieves coke quality control by adjusting the coal blending structure and the coke oven process indicators to meet the requirements of blast furnace smelting for coke quality. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide a coke oven coal blending method based on the heat recovery function of coking coal.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The heat recovery coke oven coal blending method based on the coking coal function has the following specific steps:

[0007] S1. Classify each coking coal according to its function in coking coal blending and coking process:

[0008] The first category is coking coal HPR that regulates porosity and improves reactivity;

[0009] The second type is coking coal FW that provides skeleton function;

[0010] The third category is coking coal CP which provides caking properties;

[0011] The fourth category is coking coal HF, which provides high fluidity and bonding properties with high inertness capacity;

[0012] The fifth category is low volatile coal LRV with reduced reactivity;

[0013] The sixth category is low ash, low sulfur, weakly caking and high volatile coal LSHV;

[0014] S2. Set the mass ratio of each type of coking coal according to the function: first type coking coal HPR: 15% ~ 38%, second type coking coal FW: 5% ~ 45%, third type coking coal CP: 5% ~ 35%, fourth type coking coal HF: 0% ~ 20%, fifth type coking coal LRV: 25% ~ 40%, sixth type coking coal LSHV: 0% ~ 15%;

[0015] S3. Pre-crush the first type coking coal HPR, the fifth type coking coal LRV and the sixth type coking coal LSHV respectively, and then grind and mix them with other types of coking coal, so that the bonding index G value of the mixed coal is 58 to 78, the maximum thickness Y value of the colloid layer is 11 to 16 mm, and the volatile matter Vdaf is 22% to 27%;

[0016] S4. Carry out coal preparation, coking and coke quenching operations according to the heat recovery coke oven production process.

[0017] As one of the preferred technical solutions, the specific classification criteria of step S1 are as follows:

[0018] Category 1 coking coal HPR: volatile matter Vdaf>28%, 85>G>35, CRI>28%.

[0019] The second type of coking coal FW: volatile matter Vdaf <28%, G>75, 15mm<Y<22mm, CSR>56%.

[0020] The third type of coking coal CP: volatile matter Vdaf>20%, G>85, Y>22, αmax>1500dd / min.

[0021] The fourth type of coking coal HF: volatile matter Vdaf>20%, G>85, Y>25, αmax>15000dd / min.

[0022] Category 5 coking coal LRV: volatile matter Vdaf <20%, G <65, CRI <22%.

[0023] Category 6 coking coal LSHV: volatile matter Vdaf>30%, G<20, S<0.4%, Ad<4.5%.

[0024] As one of the preferred technical solutions, in step S2, the first type of coking coal HPR + the sixth type of coking coal LSHV ≤ 45%, the third type of coking coal CP + the fourth type of coking coal HF ≥ 20%; thereby ensuring that the functions of different types of coking coal are complementary and non-conflicting.

[0025] As one of the preferred technical solutions, in step S3, the mass proportion of the pre-crushed particles with a fineness of less than 3 mm is greater than 60-80%.

[0026] As one of the preferred technical solutions, in step S4, preparing coal includes:

[0027] S4-1. Coal blending, crushing to a fineness of less than 3 mm, accounting for 90-95% by mass and mixing;

[0028] S4-2. Ramming and charging: The ramming density is 0.95 to 1.15 tons / cubic meter.

[0029] As one of the further preferred technical solutions, the method for controlling the tamping density is: loading coal in three times and tamping in three batches; among them, the first and second tamping adopts the hammer tamping method, and the third tamping adopts the hydraulic tamping method; when improving the cold strength of coke, reducing the porosity, and increasing the bulk density, a high-density tamping method is adopted, and the three layers are tamped 2 to 3 times, and the tamping density is 1.00 to 1.15 tons / cubic meter; when improving the porosity, reducing the bulk density and the cold strength of coke, a low-density tamping method is adopted, the first layer is tamped 2 times, the second layer is tamped 1 to 2 times, the third layer is tamped once, and the tamping density is 0.95 to 0.99 tons / cubic meter.

[0030] As one of the preferred technical solutions, in step S4, the coking conditions are: when the coal cake thickness is 1 to 1.15 m, the coking time is 68 to 85 hours.

[0031] As one of the preferred technical solutions, in step S4, dry quenching is adopted.

[0032] As one of the preferred technical solutions, step S4 obtains qualified metallurgical coke with M40>88%, M10<7.5%, CRI>20%, and CSR>58%.

[0033] Beneficial effects of the present invention:

[0034] The invention provides a method for heat recovery coke oven blending based on the function of coking coal, comprising the following steps: classifying each coking coal according to the function of the coking coal in the coking coal blending and the coking process; classifying each coking coal into: a first type of coking coal (HPR) for regulating porosity and improving reactivity, a second type of coking coal (FW) for providing skeleton function, a third type of coking coal (CP) for providing cohesiveness, a fourth type of coking coal (HF) for providing high fluidity and cohesiveness with high inertia capacity, a fifth type of low volatile coal (LRV) for reducing reactivity, and a sixth type of low ash and low Sulfur high volatile coal (LSHV); pre-crush the first type coking coal (HPR), the fifth type coking coal (LRV) and the sixth type coking coal (LSHV) respectively, and then mix them with other coking coals to make the G value of the mixed coal 58-78, the Y value 11-16mm, and the volatile matter Vdaf 22%-27%; then crush (mix) according to the heat recovery coke oven process, and the proportion of crushing fineness <3mm is 90-95%, and then ramming, the ramming density is 0.95-1.15 tons / cubic meter, and finally loaded into the furnace for coking production. It can produce qualified metallurgical coke with M40>88%, M10<7.5%, CRI>20%, and CSR>58%.

[0035] The present invention classifies the coking coal according to its function in the coking process of the heat recovery coke oven and its contribution to the quality of the obtained coke. According to the classification, the coal blending structure can be adjusted to make each coking coal give full play to its own function and make its function complementary, so as to fully expand the coking coal resources. At the same time, according to the coke quality index requirements and the contribution of the coking coal to the coke quality, the quality index of the coke can be adjusted by adjusting the coal blending structure to meet the needs of blast furnace smelting.

[0036] In addition, the coal blending method provided by the present invention can produce coke that meets the smelting needs of blast furnaces when the coal blending ratio changes greatly, significantly improving the utilization efficiency of coking coal resources, reducing costs and improving production benefits. At the same time, the quality of coke can also be accurately controlled according to the needs of blast furnaces, meeting the high-efficiency and low-cost production requirements of blast furnaces. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its contents.

[0038] The following embodiments of the present invention are all implemented in a heat recovery coke oven, comprising the following steps:

[0039] A. Carry out coal quality analysis on all coal types;

[0040] B. Carry out coking tests in experimental coke ovens on all the coal types;

[0041] C. Screening and cold strength testing of the test coke oven coke of all coal types;

[0042] D. Conduct hot strength test on the test coke oven coke from all coal types.

[0043] The coal quality analysis parameters described in step A include work points ("Industrial Analysis Method of Coal" (GB / T 212-2008)), adhesion index G value ("Determination Method of Adhesion Index of Bituminous Coal" (GB / T 5447-2014)), maximum thickness Y value of colloid layer ("Determination Method of Colloidal Layer Index of Bituminous Coal" (GB / T 479-2016)), Gibbs fluidity αmax ("Plasticity Determination of Coal by Constant Torque Gibbs Plasticity Instrument Method" (GB / T 25213-2010)), maximum average reflectivity and distribution ("Determination Method of Vitrinite Reflectivity of Coal by Microscope" (GB / T 6948-2008) or "Automatic Determination of Random Reflectivity of Vitrinite of Coal by Image Analysis" (GB / T40485-2021)).

[0044] The experimental coke oven coking test described in step B refers to the process of loading 43 kg of coking coal with 10% moisture into a 40 kg experimental coke oven according to Appendix A of the metallurgical industry standard "Technical Specifications for Small Coke Ovens for Coking Tests" YBT 4526-2016, and dry distilling at 1050°C for 15.5 hours to obtain coke.

[0045] The coke screening and cold strength test described in step C refers to screening the coke into >80mm, 80-60mm, 60-40mm, 40-25mm, and <25mm, and then measuring the cold mechanical strength of the coke according to the national standard "Method for Determination of Mechanical Strength of Coke" GB / T2000-2008, and obtaining the M40 and M10 indicators.

[0046] The hot strength test of coke described in step D is to measure the hot strength of coke according to the "Test Method for Reactivity and Post-Reaction Strength of Coke" GB / T4000-2008, and obtain the CRI and CSR indicators.

[0047] E. Coking coal is divided into six categories according to the following classification standards:

[0048] The first type of coking coal (HPR) has volatile matter Vdaf>28%, 85>G>35, and CRI>28%.

[0049] The second type of coking coal (FW): volatile matter Vdaf <28%, G>75, 15 <mmY<22mm,CSR> 65%.

[0050] The third type of coking coal (CP) has the following characteristics: volatile matter Vdaf>20%, G>85, Y>22mm, αmax>1500dd / min.

[0051] The fourth type of coking coal (HF) has the following characteristics: volatile matter Vdaf>20%, G>85, Y>25mm, αmax>15000dd / min.

[0052] The fifth type of coking coal (LRV) has the following characteristics: volatile matter Vdaf<20%, G<65, and CRI<22%.

[0053] The sixth type of coking coal (LSHV) has the following characteristics: volatile matter Vdaf>30%, G<20, S<0.4%, and Ad<4.5%.

[0054] F. According to the above six types of coal indicators and their functions, combined with inventory and price, formulate coal blending ratio and add them up for calculation. By adjusting the blending ratio, the G value of the blended coal is 58-78, the Y value is 11-16mm, and the volatile matter Vdaf is 22%-27%.

[0055] G. Carry out coal blending operations on the production equipment according to the coal blending ratio determined above.

[0056] The first type of coal (HPR), the fifth type of coal (LRV) and the sixth type of coal (LSHV) are pre-crushed respectively, and the proportion of pre-crushed fineness <3mm is controlled at 60-80%.

[0057] H. Crush the prepared coal and send it into the coal tower.

[0058] According to the coal crushing fineness, the proportion of <3mm is controlled at 90-95%.

[0059] I. Load the mixed coal in the coal tower into the coal trough of the tamping machine, and then unload the material for tamping.

[0060] J. Push the compacted coal cakes into the empty carbonization chamber for carbonization.

[0061] K. Push the coke cake out of the carbonization chamber.

[0062] L. Send the coke into the dry quenching furnace for quenching.

[0063] M. Screen the coke discharged from the dry quenching furnace.

[0064] The coal quality analysis indicators of the mixed coal types are shown in Table 1.

[0065] Table 1. Coal quality analysis indicators of coal types

[0066]

[0067] Note: The fifth category (LRV) and sixth category LSHV coal in the table have low cohesiveness and αmax cannot be measured. Since they cannot be coked alone, the M40, M10, CRI and CSR indicators of coke cannot be measured.

[0068] The coal blending ratios and quality indicators of Examples 1 to 4 are shown in Tables 2 and 3. In Example 1, a high-density tamping method is adopted, and the three layers are tamped 2 to 3 times, and the tamping density is 1.00-1.15 tons / cubic meter, which improves the cold strength of coke, reduces the porosity, and improves the bulk density; Examples 2 to 4 adopt a low-density tamping method, with the first layer tamped 2 times, the second layer tamped 1-2 times, and the third tamping 1 time, and the tamping density is 0.95-0.99 tons / cubic meter, which improves the coke porosity, reduces the bulk density and the cold strength of coke.

[0069] Table 2. Coal blending ratios of Examples 1 to 4

[0070]

[0071]

[0072] Table 3. Coal quality indexes of Examples 1 to 4

[0073] Total moisture / % Moisture / % Ash / % Volatile matter / % Fixed carbon / % sulfur / % G-Value Example 1 9.72 0.87 10.82 22.76 68.90 0.92 65.58 Example 2 10.54 1.17 10.22 23.78 68.44 1.08 60.35 Example 3 10.3 1.22 10.32 26.1 66.28 1.00 68.43 Example 4 11.28 1.46 9.96 25.09 67.46 1.00 59.14

[0074] The coke quality indicators of Examples 1 to 4 are shown in Table 4.

[0075] Table 4. Coke quality indexes of Examples 1 to 4

[0076]

[0077] As shown in Table 4, the coking coal blending method based on the function of coking coal in the coking process of heat recovery coke oven combined with the coking process parameter tamping density to control the coke quality can effectively control the coke quality. The coke M40, M10, CRI and CSR obtained in Examples 1 to 4 all reach the first-class metallurgical coke quality index. The microscopic strength and apparent porosity of the coke matrix in Examples 2 to 4 are significantly improved, and the dry basis bulk density is reduced. It can be seen from the coke quality indexes obtained in Examples 1 to 4 that the method of the present invention can adjust the coal blending structure to a large extent to make full use of coal resources to produce coke with qualified quality indexes; at the same time, the coke quality indexes of Examples 2 to 4 obtained by adjusting the coal blending structure and tamping process parameters can better meet the blast furnace smelting needs compared with the coke in Example 1, which has been fully verified in blast furnace production.

[0078] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A method for blending coal for a coke oven based on heat recovery of coking coal, characterized in that: The specific steps are as follows: S1. Classify each coking coal according to its function in coking coal blending and coking process: The first category is coking coal HPR that regulates porosity and improves reactivity; The second type is coking coal FW that provides skeleton function; The third category is coking coal CP which provides caking properties; The fourth category is coking coal HF, which provides high fluidity and bonding properties with high inertness capacity; The fifth category is low volatile coal LRV with reduced reactivity; The sixth category is low ash, low sulfur, weakly caking and high volatile coal LSHV; S2. Set the mass ratio of each type of coking coal according to the function: first type coking coal HPR: 15% ~ 38%, second type coking coal FW: 5% ~ 45%, third type coking coal CP: 5% ~ 35%, fourth type coking coal HF: 0% ~ 20%, fifth type coking coal LRV: 25% ~ 40%, sixth type coking coal LSHV: 0% ~ 15%; S3. The first type of coking coal HPR, the fifth type of coking coal LRV and the sixth type of coking coal LSHV are pre-crushed, and then crushed and mixed with other types of coking coal, so that the G value of the mixed coal is 58 to 78, the Y value is 11 to 16 mm, and the volatile matter Vdaf is 22% to 27%; S4. Carry out coal preparation, coking and coke quenching operations according to the heat recovery coke oven production process.

2. The method according to claim 1, characterized in that The specific classification criteria of step S1 are as follows: Category 1 coking coal HPR: volatile matter Vdaf>28%, 85>G>35, CRI>28%. The second type of coking coal FW: volatile matter Vdaf <28%, G>75, 15mm<Y<22mm, CSR>56%. The third type of coking coal CP: volatile matter Vdaf>20%, G>85, Y>22, αmax>1500dd / min. The fourth type of coking coal HF: volatile matter Vdaf>20%, G>85, Y>25, αmax>15000dd / min. Category 5 coking coal LRV: volatile matter Vdaf <20%, G <65, CRI <22%. Category 6 coking coal LSHV: volatile matter Vdaf>30%, G<20, S<0.4%, Ad<4.5%.

3. The method according to claim 1, characterized in that In step S2, the first type coking coal HPR + the sixth type coking coal LSHV ≤ 45%, and the third type coking coal CP + the fourth type coking coal HF ≥ 20%.

4. The method according to claim 1, characterized in that: In step S3, the mass proportion of the pre-crushed particles with a particle size of less than 3 mm is greater than 60-80%.

5. The method according to claim 1, characterized in that In step S4, coal preparation includes: S4-1. Coal blending, crushing to a fineness of less than 3 mm, accounting for 90-95% by mass and mixing; S4-2. Ramming and charging: The ramming density is 0.95 to 1.15 tons / cubic meter.

6. The method according to claim 5, characterized in that The method for controlling the tamping density is: loading coal in three times and tamping in three batches; among them, the first and second tamping adopts the hammer tamping method, and the third tamping adopts the hydraulic tamping method; when improving the cold strength of coke, reducing the porosity, and increasing the bulk density, a high-density tamping method is adopted, and the three layers are tamped 2 to 3 times, and the tamping density is 1.00 to 1.15 tons / cubic meter; when improving the porosity, reducing the bulk density and the cold strength of coke, a low-density tamping method is adopted, the first layer is tamped 2 times, the second layer is tamped 1 to 2 times, the third layer is tamped once, and the tamping density is 0.95 to 0.99 tons / cubic meter.

7. The method according to claim 1, characterized in that In step S4, the coking conditions are: when the coal cake thickness is 1 to 1.15 m, the coking time is 68 to 85 hours.

8. The method according to claim 1, characterized in that In step S4, dry quenching is adopted.

9. The method according to claim 1, characterized in that: Step S4 obtains qualified metallurgical coke with M40>88%, M10<7.5%, CRI>20-27%, and CSR>58%.

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