Quality control method for coke and blast furnace operation method

Abstract

To optimize a control value of a quality control index of coke in blast furnace operation in which hydrogen-based gas is blown into the blast furnace.SOLUTION: A quality control method for coke charged into a blast furnace into which hydrogen-based gas is blown, comprises a preparation step for preparing a correlation between information on the blowing amount of the hydrogen-based gas to be blown into the blast furnace and a quality control index of the coke, and a control value determination step for determining a control value of the quality control index of the coke based on the correlation prepared in the preparation step and the information on the blowing amount of the hydrogen-based gas to be blown into the blast furnace.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The technology disclosed in the present application relates to a coke quality control method and a blast furnace operation method. [Background technology]

[0002] There are known studies on the deterioration of coke in a blast furnace (see, for example, Non-Patent Documents 1 to 3). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Gasification Reactivity and Structure Evolution of Metallurgical Coke under H2O / CO2Atmosphere", Energy&Fuels, 2018, 32, 1188-1195 [Non-Patent Document 2] "Deterioration of coke by molten iron oxide in the cohesive and dripping zones of blast furnaces", Tetsu-to-Hagane Vol. 84 (1998) No. 10, pp. 697-701 [Non-Patent Document 3] "Effect of Gasification and Smelting Reduction on Deterioration of Coke", Tetsu-to-Hagane Vol. 92 (2006) No. 12, pp. 841-848 Summary of the Invention [Problem to be solved by the invention]

[0004] Coke charged into a blast furnace is required to have a certain quality, and the quality of this coke is controlled based on the control value of a quality control index such as CSR (post-reaction strength, hereinafter referred to as "post-hot gasification strength").

[0005] Here, for example, from the viewpoint of reducing carbon dioxide emissions, it is conceivable to inject hydrogen-based gas into the blast furnace as a reducing agent for iron ore in addition to charging coke into the blast furnace. However, in this case, there is a concern that the reaction of the coke is promoted by the hydrogen-based gas, and the control value of the quality control index such as the required strength of the coke becomes high.

[0006] The technology disclosed in the present application aims to optimize the control values ​​of coke quality control indexes in blast furnace operation in which a hydrogen-based gas is injected into the blast furnace. [Means for solving the problem]

[0007] A coke quality control method according to a first embodiment is a quality control method for coke charged into a blast furnace into which a hydrogen-based gas is injected, and includes a preparation step of preparing a correlation between information regarding the amount of hydrogen-based gas injected into the blast furnace and a quality control index of the coke, and a control value determination step of determining a control value of the quality control index of the coke based on the correlation prepared in the preparation step and information regarding the amount of hydrogen-based gas injected into the blast furnace.

[0008] According to the above aspect, first, in a preparation step, a correlation between information on the amount of hydrogen-based gas injected into the blast furnace and a quality control index of the coke is prepared. Next, in a control value determination step, a control value of the quality control index of the coke is determined based on the correlation prepared in the preparation step and the information on the amount of hydrogen-based gas injected into the blast furnace.

[0009] This allows the control values ​​of the quality control indexes of the coke to be optimized, and therefore the production cost of the coke can be reduced.

[0010] A coke quality control method according to a second aspect is the coke quality control method according to the first aspect, wherein the coke quality control index is the coke's strength after hot gasification reaction, and in the preparation process, a correlation is prepared between information regarding the amount of hydrogen-based gas injected into the blast furnace and a correction index that corrects a control value of the coke's strength after hot gasification reaction when no hydrogen-based gas is injected into the blast furnace, and in the control value determination process, a correction value is determined based on the correlation prepared in the preparation process and information regarding the amount of hydrogen-based gas injected into the blast furnace, and the control value is corrected based on the determined correction value.

[0011] According to the above embodiment, the quality control index of the coke is the coke strength after hot gasification reaction (CSR). Here, when hydrogen-based gas is injected into the blast furnace, the iron ore and the hydrogen-based gas undergo a reduction reaction. Therefore, when the amount of hydrogen-based gas injected into the blast furnace increases, the solution loss carbon amount (SLC) decreases, and the reaction rate of the coke decreases. As a result, the coke strength after hot gasification reaction increases. In consideration of this increase in the coke strength after hot gasification reaction, in this embodiment, the control value of the coke strength after hot gasification reaction is corrected (relaxed).

[0012] Specifically, first, in a preparation step, a correlation is prepared between information on the amount of hydrogen-based gas injected into the blast furnace and a correction index for correcting a control value of the strength of the coke after the hot gasification reaction when no hydrogen-based gas is injected into the blast furnace. Next, in a control value determination step, a correction value is calculated based on the correlation prepared in the preparation step and information on the amount of hydrogen-based gas injected into the blast furnace, and the control value of the strength of the coke after the hot gasification reaction is corrected based on the calculated correction value.

[0013] This makes it possible to use the strength of coke after hot gasification reaction when no hydrogen-based gas is injected into the blast furnace as a quality control index for coke when hydrogen-based gas is injected into the blast furnace, while optimizing the control value of the strength after hot gasification reaction, thereby reducing the production cost of coke.

[0014] A coke quality control method according to a third aspect is the coke quality control method according to the second aspect, wherein the information relating to the amount of hydrogen-based gas injected into the blast furnace includes a coke reactivity corresponding to the amount of hydrogen-based gas injected into the blast furnace, and in the control value determination process, the correction value is calculated based on the correlation prepared in the preparation process and the coke reactivity, and the control value is corrected based on the calculated correction value.

[0015] According to the above aspect, the information on the amount of hydrogen-based gas injected into the blast furnace includes a coke reactivity corresponding to the amount of hydrogen-based gas injected into the blast furnace. As described above, when the amount of hydrogen-based gas injected into the blast furnace increases, the coke reactivity decreases. In other words, there is a predetermined correlation between the amount of hydrogen-based gas injected into the blast furnace and the coke reactivity. In addition, there is a predetermined correlation between the coke reactivity and the strength of the coke after hot gasification reaction.

[0016] Therefore, in this embodiment, for example, in the preparation step, a correlation between the reactivity of the coke according to the amount of hydrogen-based gas injected into the blast furnace and the correction index is prepared. Next, in the control value determination step, a correction value is obtained based on the correlation prepared in the preparation step and the reactivity of the coke, and the control value of the strength after the hot gasification reaction of the coke is corrected based on the obtained correction value. This makes it possible to improve the correction accuracy of the control value of the strength after the hot gasification reaction of the coke.

[0017] A coke quality control method according to a fourth aspect is the coke quality control method according to the third aspect, wherein the correction index is a strength of the coke after a smelting reduction reaction due to a smelting reduction reaction.

[0018] According to the above-mentioned aspect, the correction index is set to the strength of the coke after the smelting reduction reaction due to the smelting reduction reaction. Here, as described above, when the amount of hydrogen-based gas injected into the blast furnace increases, the amount of solution loss carbon decreases, and therefore the reaction rate of the coke decreases.

[0019] More specifically, when the amount of hydrogen-based gas injected into the blast furnace increases, the amount of solution loss carbon, mainly the amount of smelting reduction reaction, decreases, and the reaction rate of the coke decreases. Therefore, the management of the strength of the coke after the hot gasification reaction can be corrected (relaxed) for the decrease in the reaction rate of the coke due to the decrease in the amount of smelting reduction reaction.

[0020] Therefore, in the preparation process, by preparing a correlation between the coke reactivity according to the amount of hydrogen-based gas injected into the blast furnace and the strength of the coke after the smelting reduction reaction due to the smelting reduction reaction, the accuracy of correcting the control value of the coke strength after the hot gasification reaction can be improved.

[0021] A coke quality control method according to a fifth aspect is the coke quality control method according to the fourth aspect, wherein in the control value determination step, the control value is corrected based on a difference between the control value and the correction value.

[0022] According to the above aspect, the control value of the strength of the coke after the hot gasification reaction is corrected based on the difference between the control value of the strength of the coke after the hot gasification reaction and the strength of the coke after the smelting reduction reaction, thereby further improving the correction accuracy of the control value of the strength of the coke after the hot gasification reaction.

[0023] A coke quality control method according to a sixth aspect is a coke quality control method according to the fourth or fifth aspect, in which, in the preparation step, a first relational equation between the reactivity of the coke and the strength of the coke after a hot gasification reaction, and a second relational equation between the reactivity of the coke and the strength of the coke after a smelting reduction reaction, the slope of which is 1 / 5 or more and 1 / 4 or less of the slope of the first relational equation, are prepared.

[0024] According to the above embodiment, the slope of the second relational expression between the coke reactivity and the strength of the coke after the smelting reduction reaction is set to be 1 / 5 or more and 1 / 4 or less of the slope of the first relational expression between the coke reactivity and the strength of the coke after the hot gasification reaction. This improves the calculation accuracy of the strength of the coke after the smelting reduction reaction as a correction index. Therefore, the correction accuracy of the control value of the strength of the coke after the hot gasification reaction can be further improved.

[0025] A seventh aspect of the coke quality control method is a coke quality control method according to the sixth aspect, wherein the intercept of the second relational equation is set so that the graph representing the second relational equation intersects with the graph representing the first relational equation at the control value before correction.

[0026] According to the above aspect, the intercept of the second relational expression is set so that the graph representing the second relational expression intersects with the graph representing the first relational expression at the control value of the strength of the coke after the hot gasification reaction before correction. This further improves the calculation accuracy of the strength of the coke after the smelting reduction reaction as the correction index. Therefore, the correction accuracy of the control value of the strength of the coke after the hot gasification reaction can be further improved.

[0027] A coke quality control method according to an eighth aspect is a coke quality control method according to any one of the first to seventh aspects, and further includes a selection process for selecting the coke to be charged into the blast furnace based on the control value determined by the control value determination process.

[0028] According to the above aspect, the coke to be charged into the blast furnace is selected based on the control value of the coke quality control index corrected according to the amount of hydrogen-based gas injected into the blast furnace, thereby reducing the manufacturing cost of the coke.

[0029] A ninth aspect of the present invention relates to a blast furnace operation method, in which iron ore and coke selected by the coke quality control method according to the eighth aspect are charged into a blast furnace, and a hydrogen-based gas is injected into the blast furnace.

[0030] According to the above aspect, it is possible to reduce the cost of producing coke while maintaining the productivity of blast furnace operation. Effect of the Invention

[0031] According to the technology disclosed in the present application, it is possible to optimize the control value of the quality control index of coke in blast furnace operation in which a hydrogen-based gas is injected into the blast furnace. [Brief description of the drawings]

[0032] [Figure 1] 1 is a vertical cross-sectional view showing a blast furnace to which a coke quality control method and a blast furnace operation method according to an embodiment are applied. [Diagram 2] 1 is a graph showing the relationship between the amount of hydrogen-based gas injected and the reduction form of iron ore. [Diagram 3] 1 is a graph showing the relationship between the amount of hydrogen-based gas blown and the amount of solution loss carbon. [Figure 4] 1 is a graph showing the relationship between the coke conversion index (CRI) and the coke strength after hot gasification reaction (CSR) and strength after smelting reduction reaction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, one embodiment will be described with reference to the drawings.

[0034] (blast furnace) 1 shows a blast furnace 10 to which the coke quality control method and the blast furnace operation method according to the present embodiment are applied. Iron ore, coke, and the like are charged into the blast furnace 10 from the top of the furnace. As a result, a coke layer 20 and an iron ore layer 22 are alternately deposited in the blast furnace 10.

[0035] Hot air, auxiliary fuel, and the like are blown into the blast furnace 10 through tuyere 12 provided at the bottom of the blast furnace 10. This causes the auxiliary fuel and coke to burn, generating rising high-temperature gas (reducing gas). The iron ore in the iron ore layer formed in the blast furnace 10 is heated and reduced by this reducing gas as it descends. The iron ore melts as it descends and is discharged as pig iron from a tap hole (not shown) provided on the side wall of the furnace bottom.

[0036] In addition, hydrogen-based gas is blown into the blast furnace 10 from the tuyere 12 or a tuyere provided in a shaft portion (not shown) as a reducing agent for iron ore. Examples of hydrogen-based gas include industrially produced hydrogen gas, natural hydrogen gas, hydrogen gas discharged from factories such as coke ovens, and circulating gas obtained by removing carbon dioxide (CO2) and moisture from exhaust gas discharged from the top of the blast furnace 10.

[0037] (Analysis Overview) Here, in blast furnace operation when a hydrogen-based gas is injected into the blast furnace 10, the reaction mode of the coke in the blast furnace 10 will be explained based on the analysis results using a blast furnace mathematical model.

[0038] In this analysis, the productivity is set at 2.7 [t / d / m 3 The amount of hydrogen-based gas (room temperature) injected into the blast furnace from the tuyere was changed as a parameter, as shown in Table 1 below. In this case, in each of the reference models and models 1 to 4, in order to keep the analysis conditions constant, for example, the pulverized coal ratio (ratio of pulverized coal amount to iron production rate) was adjusted so that the iron production rate per day, molten iron temperature, coke ratio, and furnace top temperature were constant.

[0039] As an example of the blast furnace mathematical model, the three-dimensional model described in the literature ("Three dimensional Dynamic Simulator for Blast Furnace" ISIJ International, Vol. 39, (1999), No. 1, pp. 15-22) was used. In this analysis, the pulverized coal ratio was adjusted so that the daily iron production rate and molten iron temperature were constant.

[0040] [Table 1]

[0041] (Analysis results) Figure 2 shows the relationship between the amount of hydrogen-based gas injected and the reduction form of iron ore. As shown in Figure 2, when the amount of hydrogen-based gas injected increases, the reduction rate by the hydrogen-based gas increases, and the melting reduction rate (direct reduction rate), which is a large endothermic reaction, decreases. From this, it can be seen that the reducing agent ratio (= coke ratio + pulverized coal ratio) can be reduced according to the increase in the amount of hydrogen-based gas injected, as in models 1 to 4 shown in Table 1 above.

[0042] Next, Figure 3 shows the relationship between the amount of hydrogen-based gas injected and the amount of solution loss carbon (SLC). As shown in Figure 3, when the amount of hydrogen-based gas injected increases, the amount of solution loss carbon decreases. In other words, under blast furnace operating conditions with a constant coke ratio, as in this analysis, when the amount of hydrogen-based gas injected increases, the coke reaction rate decreases. From this, it can be seen that the control value of the coke quality control index can be corrected (relaxed) for the decrease in the coke reaction rate according to the increase in the amount of hydrogen-based gas injected.

[0043] Here, the amount of gasification reaction by H2O and CO2 in the amount of solution loss carbon does not change significantly even if the amount of hydrogen-based gas injected is increased. On the other hand, the amount of smelting reduction reaction in the amount of solution loss carbon decreases as the amount of hydrogen-based gas injected increases. From this, it is considered that the decrease in the coke reaction rate with an increase in the amount of hydrogen-based gas injected is mainly due to the decrease in the amount of smelting reduction reaction of the coke. Therefore, it is possible to correct (relax) the control value of the coke quality control index for the decrease in the amount of smelting reduction reaction with an increase in the amount of hydrogen-based gas injected.

[0044] The reason why the amount of smelting reduction reaction decreases with an increase in the amount of hydrogen-based gas injected is thought to be as follows. That is, the reduction reaction of iron ore by hydrogen-based gas (H2) is faster than that by carbon monoxide gas (CO), and tends to be more active in a lower temperature region than the reduction reaction of iron ore by carbon monoxide gas. Therefore, when the amount of hydrogen-based gas injected increases, the reduction reaction rate of iron ore by hydrogen-based gas becomes higher in the upper part of the blast furnace, which is lower in temperature than in the lower part. From this result, it is thought that the amount of smelting reduction reaction between iron ore and coke decreased in the lower part of the blast furnace.

[0045] (Method of correcting the control value of the quality control index of coke) Next, a correction method for correcting the control value of the quality control index of coke will be described.

[0046] In the following, a method for correcting the control value of coke's post-hot gasification strength (CSR: post-reaction strength) will be described as an example of a control value of a quality control index of coke. The post-hot gasification strength of coke is an index showing the strength of coke after reacting (gasification reaction) coke with carbon dioxide (CO2) under specific conditions. The method for measuring the post-hot gasification strength of coke is specified in ASTM-D5341.

[0047] Graph G1 showing the relationship between the coke reactivity index (CRI) and the coke strength after hot gasification reaction (CSR) is shown in Fig. 4. Graph G2 shown in Fig. 4 is a graph of formula (2) described later.

[0048] Graph G1 shows a general relationship between the coke reactivity and the strength of the coke after hot gasification reaction when the strength of the coke after hot gasification reaction is measured by the method specified in the above-mentioned ASTM-D5341. This graph G1 is expressed by the following formula (1). y=-1.00x+89.1 (1)

[0049] Equation (1) shows the relationship between the coke reactivity and the strength of the coke after hot gasification reaction when the coke is gasified, regardless of the type of gas with which the coke is reacted. Therefore, for example, the relationship between the coke reactivity and the strength of the coke after hot gasification reaction when the coke is reacted with a gas containing steam (H2O) under the specified conditions specified in ASTM-D5341 can also be expressed by equation (1).

[0050] The formula (1) is obtained, for example, from the results of measuring the strength of coke after hot gasification reaction, which is periodically performed in blast furnace operation. The coefficients and the like in the formula (1) can be appropriately changed depending on the reaction conditions of the coke. The formula (1) is also an example of a first relational formula between the reaction rate of the coke and the strength of the coke after hot gasification reaction.

[0051] As can be seen from the above analysis results, in blast furnace operation where hydrogen-based gas is injected into the blast furnace, the coke reactivity decreases as the amount of hydrogen-based gas injected increases (see Figure 3). Therefore, it is conceivable to substitute the coke reactivity that decreases with an increase in the amount of hydrogen-based gas injected into equation (1) and use the obtained coke strength after hot gasification reaction as the new coke control value.

[0052] However, the decrease in the coke reactivity with an increase in the amount of hydrogen-based gas injected is believed to be mainly due to the decrease in the amount of solution loss carbon that is the result of the melting and reduction reaction of the coke, as mentioned above. Therefore, even if the decrease in the coke reactivity with an increase in the amount of hydrogen-based gas injected is substituted into equation (1) for the case where the coke is gasified, it is not possible to obtain an appropriate coke strength (control value) after the hot gasification reaction.

[0053] Here, in Non-Patent Documents 2 and 3, the variation (decrease) in the strength of coke after hot gasification reaction due to the smelting reduction reaction (hereinafter referred to as "strength of coke after smelting reduction reaction") is set to 1 / 5 to 1 / 4 (0.2 to 0.25 times) of the variation (decrease) in the strength of coke after hot gasification reaction due to the gasification reaction. Therefore, in this embodiment, an equation is created as the relational equation between the coke reactivity and the strength of coke after smelting reduction reaction, with the slope being 1 / 5 to 1 / 4 of the slope of equation (1).

[0054] Hereinafter, a method for creating a relational expression between the coke reaction rate and the strength of the coke after the smelting reduction reaction will be described using the above analysis results.

[0055] Table 2 below shows the specifications of the reference model and each of models 1 to 4. As shown in Table 2, the coke strength after hot gasification reaction (CSR) of the reference model is 65.9%. In the following, the coke strength after hot gasification reaction of this reference model (65.9%]) will be described as the control value of the strength after hot gasification reaction, which is the subject of correction. The coke strength after hot gasification reaction (control value) of the reference model was calculated from formula (1).

[0056] [Table 2]

[0057] First, as a relational equation (second relational equation) between the coke reactivity and the strength of the coke after the melting and reduction reaction, equation (2) is created with a slope of 1 / 5 to 1 / 4 of the slope of equation (1). In the following equation (2), as an example, the slope is set to 1 / 4 of the slope of equation (1). In addition, the intercept of equation (2) is set so that a graph G2 representing equation (2) intersects with a graph G1 at the control value (65.9%) of the strength of the coke after the hot gasification reaction, which is the object of correction. y=-0.25x+71.7···(2)

[0058] The symbol P in FIG. 4 indicates the reference point where the graph G1 and the graph G2 intersect (coke reaction rate: 23.4%; coke strength after hot gasification reaction: 65.9%).

[0059] Next, a method for calculating the correction value will be described.

[0060] First, as shown in item (c) of Table 2, the coke reactivity (estimated reactivity) corresponding to the amount of hydrogen-based gas injected into the blast furnace is calculated. For example, in the case of model 2, the coke reactivity is 16.5%. The coke reactivity was calculated based on the formulas a) to e) described below.

[0061] Next, the calculated coke reactivity is substituted into formula (2) to calculate the strength of the coke after the smelting and reduction reaction, as shown in item (e) of Table 2. For example, in the case of model 2, the coke reactivity (16.5%) is substituted into formula (2) to calculate the strength of the coke after the smelting and reduction reaction (67.6%).

[0062] Next, as shown in item (f) of Table 2, the difference between the obtained coke strength after hot gasification reaction and the control value of the coke strength after hot gasification reaction is calculated as a correction value. For example, in the case of model 2, the correction value (1.7%]) is calculated by subtracting the control value of the coke strength after hot gasification reaction (65.9%]) from the coke strength after hot gasification reaction (67.6%]).

[0063] Next, the control value of the coke strength after hot gasification reaction is corrected by the obtained correction value, as shown in item (g) of Table 2. For example, in the case of Model 2, the corrected control value of the coke strength after hot gasification reaction (64.2%) is calculated by subtracting the correction value (1.7%) from the coke strength after hot gasification reaction (67.6%).

[0064] In Table 2, as shown in item (f), the difference between the strength after hot gasification reaction of the coke (control value) and the strength after hot gasification reaction of the coke was calculated as the correction value. However, the calculation method of the correction value can be changed as appropriate. For example, the ratio of the control value of the strength after hot gasification reaction of the coke to the strength after melting reduction reaction of the coke (=control value of the strength after hot gasification reaction of the coke / strength after melting reduction reaction of the coke) may be calculated as the correction value. In this case, the control value of the strength after hot gasification reaction of the coke is corrected by multiplying the calculated correction value by the control value of the strength after hot gasification reaction of the coke.

[0065] Specifically, in the case of Model 2, the ratio of the control value of the strength of the coke after the hot gasification reaction to the strength of the coke after the melting reduction reaction is set as the correction value (65.9 / 67.6). Then, the control value of the strength of the coke after the hot gasification reaction (65.9%]) is multiplied by the correction value (65.9 / 67.6) to correct the control value of the strength of the coke after the hot gasification reaction (64.2 = 65.9% x (65.9 / 67.6)). The correction value can also be multiplied by a safety factor, etc.

[0066] In addition, item (c) “Coke reaction rate (estimated reaction rate) [%]” in Table 2 was estimated using the following formulas a) to e) based on the following assumptions.

[0067] First, the pulverized coal injected from the tuyere of the blast furnace is not completely burned at the tuyere tip, and unburned pulverized coal is generated depending on the combustion rate. Here, the combustion rate of the pulverized coal at the tuyere tip was set to 70%, based on the results estimated from the porosity of unburned char sampled from an actual blast furnace.

[0068] Next, it was assumed that the unburned pulverized coal is consumed in the carburization in an amount corresponding to the ratio of the pulverized coal to the reducing material, and the remaining unburned pulverized coal is consumed in its entirety in preference to the coke through the solution loss reaction. Finally, it was assumed that the remaining solution loss reaction, which is the amount of solution loss carbon in the blast furnace minus the consumption by the unburned pulverized coal, is carried out by the coke, and the reaction rate of the coke (RD CK ) was calculated. The carbon concentrations in the pulverized coal and the coke were kept constant.

[0069] U PC =PCR × (100-ηPC) / 100 a) CB PC =U PC ×PCR / RAR b) SLC PC =(U PC -CB PC )×C PC / 100 ···c) SLC CK =SLC / C CK ×100-SLC PC d) RD CK =SLC CK / CR×100 e) however, U PC : Unburned pulverized coal [kg / t] ηPC: Pulverized coal combustion rate at the tip of the tuyere (=70[%]) CB PC : Pulverized coal consumed in carburizing [kg / t] SLC PC : Pulverized coal consumed in solution loss reaction [kg / t] C PC : Carbon in pulverized coal (=82[%]) SLC CK : Coke consumed in solution loss reaction [kg / t] C CK : Carbon in coke (=85[%]) RD CK : Coke reaction rate [%] It is.

[0070] (Quality control method for coke) Next, an example of a coke quality control method according to this embodiment will be described.

[0071] In the coke quality control method according to the present embodiment, the quality of the coke charged into the blast furnace 10 is controlled based on a predetermined control value of the coke during blast furnace operation in which a hydrogen-based gas is injected into the blast furnace 10. More specifically, in the coke quality control method according to the present embodiment, the coke to be charged into the blast furnace 10 is selected based on the control value of the coke.

[0072] Here, when the hydrogen-based gas is injected into the blast furnace 10, as described above, the iron ore and the hydrogen-based gas undergo a reduction reaction in the blast furnace 10. As a result, the reaction rate of the coke in the blast furnace 10 decreases, and the required strength of the coke decreases.

[0073] Therefore, in blast furnace operation in which hydrogen-based gas is injected into the blast furnace 10, if the quality of the coke is controlled based on the coke control values ​​used in blast furnace operation in which hydrogen-based gas is not injected into the blast furnace 10, the coke quality may be excessive, which may result in extra costs in producing the coke.

[0074] Therefore, in the coke quality control method of this embodiment, the control value of the coke quality control index used in blast furnace operation in which no hydrogen-based gas is injected into the blast furnace 10 is corrected and used based on the amount of hydrogen-based gas injected into the blast furnace 10.

[0075] (preparation process) The coke quality control method according to the present embodiment includes a preparation step and a control value determination step. First, the preparation step will be described. As an example of the coke quality control index, the coke post-hot gasification strength (CSR) is used.

[0076] In the preparation process, a correlation is prepared between information on the amount of hydrogen-based gas injected into the blast furnace 10 and a correction index that corrects the control value of the strength of the coke after hot gasification reaction when no hydrogen-based gas is injected into the blast furnace 10. The information on the amount of hydrogen-based gas injected into the blast furnace 10 is, for example, a reaction rate of the coke according to the amount of hydrogen-based gas injected into the blast furnace 10. Also, the correction index is, for example, a strength of the coke after melting reduction reaction due to a melting reduction reaction.

[0077] Specifically, first, a relational expression (hereinafter referred to as "first relational expression F1") between the coke reactivity and the coke strength after hot gasification reaction is obtained from the measurement results of the coke strength after hot gasification reaction, for example, as shown in formula (1). In addition, analysis and experiments are performed using a blast furnace mathematical model to obtain a correlation between the amount of hydrogen-based gas injected into the blast furnace and the coke reactivity (estimated reactivity), for example, as shown in Table 2. In other words, the coke reactivity according to the amount of hydrogen-based gas injected is obtained. At this time, the relationship between the amount of hydrogen-based gas injected and the amount of solution loss carbon may be obtained, as shown in FIG. 3.

[0078] Next, based on the first relational expression F1 and the control value of the strength of the coke after the hot gasification reaction, a relational expression (hereinafter referred to as "second relational expression F2") between the coke reactivity and the strength of the coke after the smelting reduction reaction as a correction index is obtained, for example, as shown in formula (2). In this case, the slope of the second relational expression F2 is set to be 1 / 5 or more and 1 / 4 or less of the slope of the first relational expression F1. In addition, the intercept of the second relational expression F2 is set so that the graph representing the second relational expression F2 (corresponding to the graph G2 in FIG. 4) intersects with the graph representing the first relational expression F1 (corresponding to the graph G1 in FIG. 4) at the control value of the strength of the coke after the hot gasification reaction (corresponding to the reference point P in FIG. 4).

[0079] The slope of the second relational expression F2 is not limited to 1 / 5 or more and 1 / 4 or less of the slope of the first relational expression F1, and can be appropriately changed. The intercept of the second relational expression F2 is not limited to the control value of the strength after hot gasification reaction of the coke, and may be set so that the graph representing the second relational expression F2 intersects with the graph representing the first relational expression F1 at another reference point.

[0080] (Control value determination process) Next, the control value determination step will be described. In the control value determination step, a correction value for correcting the control value of the coke strength after hot gasification reaction is obtained based on the second relational expression F2 prepared in the preparation step and the reactivity of the coke according to the injection amount of the hydrogen-based gas. Then, the control value of the coke strength after hot gasification reaction is corrected based on the obtained correction value.

[0081] Specifically, the coke reactivity (estimated reactivity) corresponding to the amount of hydrogen-based gas injected into the blast furnace 10 is substituted into the second relational expression F2 to determine the strength of the coke after the melting and reduction reaction (corresponding to item (e) in Table 2). Next, the difference between the control value of the strength of the coke after the hot gasification reaction and the strength of the coke after the melting and reduction reaction is determined as a correction value (corresponding to item (f) in Table 2). Next, the control value of the strength of the coke after the hot gasification reaction is corrected by subtracting the correction value from the control value of the strength of the coke after the hot gasification reaction (corresponding to item (g) in Table 2).

[0082] Next, the coke to be charged into the blast furnace 10 is selected based on the corrected control value of the strength of the coke after the hot gasification reaction. Note that the corrected control value of the strength of the coke after the hot gasification reaction can also be multiplied by, for example, a safety factor.

[0083] In this way, by correcting the control value of the strength of the coke after the hot gasification reaction based on the amount of hydrogen-based gas injected into the blast furnace 10, the control value can be optimized. This makes it possible to increase the blending ratio of non- or slightly caking coal when producing coke, thereby reducing costs. Therefore, the production cost of coke can be reduced.

[0084] (Blast furnace operation method) Next, an example of a blast furnace operation method according to this embodiment will be described.

[0085] In the blast furnace operation method according to the present embodiment, coke selected by the above-mentioned coke quality control method is charged into the blast furnace 10, and a predetermined amount of hydrogen-based gas is injected into the blast furnace 10 from the tuyere 12. This makes it possible to reduce the production cost of coke while maintaining the productivity of the blast furnace operation.

[0086] (Modification) Next, a modification of the above embodiment will be described.

[0087] In the above embodiment, the reaction rate of the coke corresponding to the amount of the hydrogen-based gas injected into the blast furnace 10 is used as the information on the amount of the hydrogen-based gas injected into the blast furnace 10. However, the information on the amount of the hydrogen-based gas injected into the blast furnace 10 is not limited to the reaction rate of the coke corresponding to the amount of the hydrogen-based gas injected into the blast furnace 10, and may be, for example, the amount of solution loss carbon corresponding to the amount of the hydrogen-based gas injected into the blast furnace 10, or the amount of the hydrogen-based gas injected into the blast furnace 10. In other words, the information on the amount of the hydrogen-based gas injected into the blast furnace 10 is a concept including the amount of the hydrogen-based gas injected into the blast furnace 10, the reaction rate of the coke corresponding to the amount of the hydrogen-based gas injected into the blast furnace 10, the amount of solution loss carbon, etc.

[0088] In the above embodiment, the strength of the coke after the smelting and reduction reaction is used as a correction index for correcting the control value of the quality control index of the coke when a hydrogen-based gas is injected into the blast furnace 10. However, this correction index is not limited to the strength of the coke after the smelting and reduction reaction, and may be another index that is correlated with information on the amount of hydrogen-based gas injected into the blast furnace 10.

[0089] In the above embodiment, the strength of the coke after the hot gasification reaction is used as the quality control index of the coke when the hydrogen-based gas is injected into the blast furnace 10. However, this quality control index is not limited to the strength of the coke after the hot gasification reaction, and may be other indexes that are correlated with information on the amount of hydrogen-based gas injected into the blast furnace 10, such as the drum strength index DI (JIS K2151), tumbler strength index TI (ASTM D3402, JIS K2151), Micom strength index M (ISO 556), and Irsid strength index I (ISO 556) after the gasification reaction or the smelting reduction reaction.

[0090] Although one embodiment of the technology disclosed in the present application has been described above, the technology disclosed in the present application is not limited to the above embodiment. In addition, the above embodiment and various modified examples may be used in appropriate combination, and the technology disclosed in the present application may be embodied in various forms without departing from the gist of the technology. [Explanation of symbols]

[0091] 10 blast furnace

Claims

1. A method for quality control of coke charged into a blast furnace into which hydrogen-based gas is blown, comprising: A preparation step of preparing a correlation between information on the amount of hydrogen-based gas injected into the blast furnace and a quality control index of coke; a control value determination step of determining a control value of the quality control index of the coke based on the correlation prepared in the preparation step and information on the amount of hydrogen-based gas injected into the blast furnace; The coke quality control method includes the steps of:

2. The quality control index of the coke is the strength of the coke after hot gasification reaction; In the preparation step, a correlation between information on an injection amount of a hydrogen-based gas injected into the blast furnace and a correction index for correcting a control value of a strength after a hot gasification reaction of the coke in a case where a hydrogen-based gas is not injected into the blast furnace is prepared; In the control value determination step, a correction value is obtained based on the correlation prepared in the preparation step and information on the amount of hydrogen-based gas injected into the blast furnace, and the control value is corrected based on the obtained correction value. The method for controlling the quality of coke according to claim 1.

3. The information regarding the amount of hydrogen-based gas injected into the blast furnace includes a reaction rate of coke according to the amount of hydrogen-based gas injected into the blast furnace, In the control value determination step, the correction value is determined based on the correlation prepared in the preparation step and the reactivity of the coke, and the control value is corrected based on the determined correction value. The method for controlling the quality of coke according to claim 2.

4. The correction index is the strength of the coke after smelting reduction reaction due to the smelting reduction reaction, The method for controlling the quality of coke according to claim 3.

5. In the control value determination step, the control value is corrected based on a difference between the control value and the correction value. The method for controlling the quality of coke according to claim 4.

6. In the preparation step, A first relational expression between the reaction rate of the coke and the strength of the coke after a hot gasification reaction; A second relational equation between the reactivity of the coke and the strength of the coke after a smelting reduction reaction, the second relational equation having a slope of 1 / 5 or more and 1 / 4 or less of the slope of the first relational equation; Prepare the The method for controlling the quality of coke according to claim 4.

7. an intercept of the second relational expression is set so that a graph representing the second relational expression intersects with a graph representing the first relational expression at the control value before correction; The method for controlling the quality of coke according to claim 6.

8. A selection process is provided for selecting the coke to be charged into the blast furnace based on the control value determined by the control value determination process. The method for controlling the quality of coke according to any one of claims 1 to 7.

9. Iron ore and coke selected by the coke quality control method according to claim 8 are charged into a blast furnace, and a hydrogen-based gas is injected into the blast furnace. Blast furnace operating methods.

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