TW202130820A - Blast furnace operation method - Google Patents

Abstract

According to one aspect of the present invention, provided is a blast furnace operation method characterized in that a high-concentration hydrogen-containing gas which contains at least 80 mol% of hydrogen gas, is blown from a tuyere under certain conditions such as: a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is room temperature to 300 DEG C, and the blown amount of hydrogen gas in the high-concentration hydrogen-containing gas is 200 Nm3/t to 500 Nm3/t; a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is 300 DEG C to 600 DEG C, and the blown amount of hydrogen gas in the high-concentration hydrogen-containing gas is at least 145 Nm3/t; or a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is 600 DEG C to 900 DEG C, and the blown amount of the high-concentration hydrogen-containing gas is at least 125 Nm3/t.

Description

Blast furnace operation method

The present invention relates to a method of operating a blast furnace. This case is based on Special Application No. 2019-216568 filed in Japan on November 29, 2019 and Special Application No. 2020-092467 filed in Japan on May 27, 2020, and its content is cited here.

In the steel manufacturing industry, the blast furnace method is the mainstream of the pig iron process. In the blast furnace method, the iron-based raw materials for the blast furnace (raw materials including iron oxide, mainly sintered ore, hereinafter also referred to as "iron-based raw materials") and coke are alternately and layered into the blast furnace from the top of the blast furnace , On the other hand, hot air is blown into the blast furnace from the tuyere at the lower part of the blast furnace. The hot air system reacts with the pulverized coal blown together with the hot air and the coke in the blast furnace to generate high-temperature reducing gas (here, mainly CO gas). That is, the hot air will melt the coke and powder coal gas. The reducing gas rises in the blast furnace to heat and reduce the iron-based raw materials at the same time. The iron-based raw materials descend in the blast furnace while being heated and reduced by the reducing gas. After that, the iron-based raw materials will melt and be further reduced by the coke, while dripping in the blast furnace. The iron-based raw materials are finally accumulated in the hearth part as melt milling (pig iron) containing slightly less than 5 mass% carbon. The melt milling of the hearth part is taken out from the tap hole and supplied to the subsequent steel making process. Therefore, in the blast furnace method, carbon materials such as coke and pulverized coal are used as reducing materials.

However, in recent years, people are clamoring to prevent global warming, and _{emission reduction of carbon dioxide (CO 2} gas), which is one of the greenhouse gases, has become a social problem. As described above, the blast furnace method uses a carbon material as a reducing material, so a large amount of CO ₂ gas is generated. Therefore, the steel industry, as _{one of the main industries in terms of CO 2} gas emissions, must respond to social demands. Specifically, in the blast furnace operation, further reducing the ratio of reduced materials (reduced materials used per ton of melt milling) has become a top priority.

The reducing material has the function of forming heat energy in the furnace to raise the temperature of the charge and reducing the iron-based raw materials in the furnace. To reduce the ratio of the reducing material, the reduction efficiency in the furnace must be improved. The reduction reaction in the furnace can be represented by various reaction formulas. Among these reduction reactions, the direct reduction reaction using coke (reaction formula: FeO+C⇒Fe+CO) is an endothermic reaction accompanied by a large amount of endothermic heat. Therefore, try to prevent this reaction from occurring. This matter becomes very important in reducing the ratio of reducing materials. Since the direct reduction reaction is a reaction that occurs in the lower part of the blast furnace, if the iron-based raw _{material can be sufficiently reduced with reducing gases such as CO and H 2} before the iron-based raw material reaches the lower part of the furnace, the target of the direct reduction reaction can be reduced. The iron-based raw materials.

As a conventional technique to solve the above-mentioned problems, for example, as disclosed in Patent Documents 1 to 6, it is known that reducing gas (H ₂ gas, COG (Cokes Oven Gas), natural gas, urban gas, etc.) is blown from a tuyere together with hot air. ), to increase the potential of the reducing gas in the furnace. When the reducing gas is a carbon-containing reducing gas (a reducing gas in which the molecular structure of the gas contains carbon atoms, such as hydrocarbon gas), the carbon atoms in the carbon-containing gas will become CO gas in the blast furnace to reduce the iron-based raw materials. When the reducing gas is hydrogen (H ₂ gas), the hydrogen reduces the iron-based raw materials. Thereby, the iron-based raw material that is the target of the direct reduction reaction can be reduced. In addition, in the following description, unless otherwise defined, "carbon" and "hydrogen" mean a carbon atom and a hydrogen atom, respectively.

Prior art literature Patent literature Patent Document 1: Japanese Patent No. 6019893 Patent Document 2: Japanese Patent No. 5987773 Patent Document 3: Japanese Patent No. 5050706 Patent Document 4: Japanese Patent No. 5770124 Patent Document 5: Japanese Patent No. 5315732 Patent Document 6: Japanese Patent No. 5851828

The problem to be solved by the invention However, in the techniques disclosed in Patent Documents 1 to 6, the amount of reducing gas blown in from the tuyere is small, and _{the effect of reducing CO 2} emissions is small.

Therefore, the present invention was made in view of the above-mentioned problems. The object of the present invention is to provide a novel and improved blast furnace operation method that can stably maintain the blast furnace operation while increasing the amount of reducing gas blown from the tuyere. The amount of gas that contains high-concentration hydrogen is injected to further reduce CO ₂ emissions.

Means for Solving the Problem In order to solve the above-mentioned problem, according to one aspect of the present invention, a method for operating a blast furnace is provided, which is characterized in that a gas containing a high concentration of hydrogen containing more than 80 mol% of hydrogen is blown into the tuyere under the following conditions: the temperature of the hydrogen gas is blown into the high concentration of not less than room temperature and below 300 ℃, and the amount of the blowing gas containing a high concentration of hydrogen in the hydrogen gas was 200Nm ³ / t or more and conditions 500Nm ³ / t of less; with high The blowing temperature of the hydrogen-concentrated gas is higher than 300℃ and below 600℃, and the blowing amount of hydrogen in the gas containing high-concentration hydrogen is 145Nm ³ /t or more; the blowing-in of the gas containing high-concentration hydrogen The temperature is higher than 600℃ and below 900℃, and the blowing volume of the gas containing high concentration of hydrogen is 125Nm ³ /t or more; the blowing temperature of the gas containing high concentration of hydrogen is above 900℃ and below 1200℃ , And the blowing amount of hydrogen in the gas containing high concentration of hydrogen is 110Nm ³ /t or more; or, the blowing temperature of the gas containing high concentration of hydrogen is higher than 1200 ℃ and the gas containing high concentration of hydrogen is The blowing amount of hydrogen is under ^{the condition of 100 Nm 3} /t or more.

Here, the temperature may also be blown into the hydrogen-containing gas of a high concentration of not less than room temperature and below 300 ℃, and the amount of the blowing gas containing a high concentration of hydrogen in the hydrogen is 200Nm ³ / t or more and 300Nm ³ / t below.

In addition, the blowing temperature of the gas containing high concentration of hydrogen may be higher than 300°C and below 600°C, and the blowing amount of hydrogen in the gas containing high concentration of hydrogen may be 145Nm ³ /t or more and 600 Nm ³ / t below.

In addition, the temperature in front of the tuyere may be 2050°C or lower.

In addition, the temperature in front of the tuyere may be higher than 2050°C and lower than 2150°C.

In addition, the temperature in front of the tuyere may be higher than 2150°C and lower than 2250°C.

In addition, the blowing temperature of the gas containing high-concentration hydrogen may be higher than 600°C and 1400°C or lower.

In addition, when the blowing temperature of the gas containing high concentration hydrogen is higher than 600°C, the blowing amount of the hydrogen gas in the gas containing high concentration hydrogen may be 1000 Nm ³ /t or less.

In addition, when the blowing temperature of the gas containing high concentration of hydrogen is higher than 600℃, and the blowing amount of hydrogen in the gas containing high concentration of hydrogen is ^{more than 400Nm 3} /t, the temperature in front of the tuyere can also be set below 2050℃ .

According to other viewpoints of the present invention, a method for operating a blast furnace can be provided, which is characterized in that the correlation between the blowing amount and the carbon consumption parameter is calculated in advance according to the temperature in front of each tuyere, and the carbon is determined according to the correlation between the blowing amount and the carbon consumption parameter. The consumption is lower than the current operation. The blowing amount of hydrogen in the gas with high concentration of hydrogen is reduced, and the gas containing high concentration of hydrogen is blown in from the tuyere according to the determined blowing amount; the above blowing amount-carbon consumption The parameter correlation is the correlation between the amount of hydrogen injected in the gas containing high concentration of hydrogen and the carbon consumption parameter related to the amount of carbon consumption when the blowing temperature of the gas containing high concentration of hydrogen containing more than 80mol% of hydrogen is a predetermined value .

In addition, it is also possible to calculate the correlation between the injection amount of hydrogen gas in the gas containing high concentration hydrogen and the carbon consumption parameter based on the injection temperature of each gas containing high concentration hydrogen.

In addition, the correlation between the blow-in amount and the pressure loss change amount can be calculated in advance according to the temperature in front of each tuyere, and the carbon can be determined based on the correlation between the blow-in amount and the carbon consumption parameter and the correlation relationship between the blow-in amount and the pressure loss change amount. The amount of hydrogen injected in a gas containing high concentration of hydrogen whose consumption is lower than that of the current operation and the change in pressure loss reaches a value within a predetermined range; the aforementioned relationship between the amount of injection and the change in pressure loss is that it contains high concentration of hydrogen. When the blowing temperature of the gas is a predetermined value, the relationship between the blowing amount of hydrogen in the gas containing high concentration of hydrogen and the change in pressure loss relative to the basic operation.

In addition, it is also possible to calculate in advance the correlation between the blow-in amount-the change in the top gas temperature based on the temperature in front of each tuyere, and the correlation between the blow-in amount-the carbon consumption parameter and the blow-in-the change in the top gas temperature The correlation determines the amount of hydrogen injected in a gas containing high-concentration hydrogen in which the carbon consumption is lower than the current operation and the change in the top gas temperature reaches a value within the predetermined range; the aforementioned injected amount-the temperature change of the top gas The amount correlation is the correlation between the amount of hydrogen in the gas containing high concentration of hydrogen and the amount of change relative to the top gas temperature of the basic operation when the blowing temperature of the gas containing high concentration of hydrogen is a predetermined value.

Effects of the Invention As described above, according to the above-mentioned viewpoints of the present invention, the operation of the blast furnace can be stably maintained while increasing the amount of gas containing high-concentration hydrogen blown from the tuyere as the reducing gas, thereby further reducing CO ₂ emissions.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in this embodiment, the numerical range indicated by "~" means a range that includes the numerical values described before and after "~" as the lower limit and the upper limit. In addition, the "reduced material ratio" is the total mass of the reduced material required to manufacture 1 ton of melt milling. Therefore, the reducing material ratio is basically the total mass of coke and pulverized coal required to produce 1 ton of melt milling, and the mass of the carbon-containing reducing gas in the gas containing high concentration of hydrogen is regarded as not included in the reducing material ratio. In addition, the "Basic Unit of Carbon Consumption (Input C)" refers to the carbon required to manufacture 1 ton of melt milling (that is, the amount of carbon consumed per 1 ton of melt milling). "The reduction rate Input ΔC of the basic unit of carbon consumption" refers to the reduction rate of the basic unit of carbon consumption relative to the basic operation. If the Input C of the basic operation calculated in the unit kg/t is A, and the Input C of a certain operation calculated in the unit kg/t is B, then Input ΔC is expressed by the following mathematical formula. Input ΔC=(AB)/A×100(%) The reduction ratio of the basic unit of carbon consumption, the larger the Input ΔC, the more the reduction material ratio is reduced, which in turn can reduce CO ₂ emissions.

＜1. Knowledge and opinions of the inventor of this case＞ In order to solve the above-mentioned problems, the inventor of the present invention focused on a gas containing a high concentration of hydrogen as a reducing gas. Here, in the present embodiment, the gas containing high-concentration hydrogen means a gas containing 80 mol% or more of hydrogen (mol% of hydrogen relative to the total mass of all gases constituting the high-concentration hydrogen-containing gas). Pure hydrogen (a gas with a hydrogen concentration of 100 mol%) is included in a gas containing a high concentration of hydrogen.

In addition, the inventor of the present application focused on the blowing amount of hydrogen gas in the gas containing high concentration hydrogen (hereinafter also referred to as the blowing amount) and the blowing temperature of the gas containing high concentration hydrogen. The reaction of reducing iron-based raw materials by hydrogen in a gas containing a high concentration of hydrogen is an endothermic reaction. In order to compensate for the temperature drop caused by the endothermic reaction, it may be considered to increase the blowing temperature of the hydrogen. However, it is very difficult to grasp the amount of decrease in furnace temperature when blowing a large amount of hydrogen in a gas containing a high concentration of hydrogen, and the degree of thermal compensation calculated in response to the amount of decrease in furnace temperature. Conduct detailed discussions. In response to the above matters, the inventors of this case conducted detailed discussions for the first time. Specifically, it is to grasp the reduction reaction speed of various gas compositions such as hydrogen and CO gas in a gas containing a high concentration of hydrogen and various blowing temperatures of a gas containing a high concentration of hydrogen, and to grasp the reduction reaction caused by these gases In addition to the influence of the furnace temperature changed by heat energy on the reduction reaction rate, and the influence of the gas composition changed by the reduction reaction on the reduction reaction rate, it is also important to grasp the extent to which the reduction reaction rate will not decrease in the entire furnace. Heat. The said research must have an experiment in which multiple tests are carried out with the actual blast furnace, the use of a test blast furnace grade device, and the use of an experimental device that can blow into the blast furnace gas according to the conditions of the blast furnace while simulating the thermal insulation conditions, or Research conducted using simulation models. The inventors of the present case conducted the above-mentioned study using a simulation model, and found that there is an appropriate range of the blowing amount for each blowing temperature. That is, when the blowing temperature of the gas containing high concentration of hydrogen is below 600°C, the reduction ratio Input ΔC of the basic unit of carbon consumption does not simply increase as the blowing amount of hydrogen in the gas containing high concentration of hydrogen increases. Once the blow-in volume increases to a certain extent, it will ease down and then decrease. In addition, when the reduction ratio Input ΔC of the basic unit of carbon consumption eases and then decreases, the injection amount of hydrogen in the gas containing high concentration of hydrogen will vary depending on the injection temperature of the gas containing high concentration of hydrogen. On the other hand, when the blowing temperature of a gas containing a high concentration of hydrogen is higher than 600°C, the reduction rate Input ΔC of the basic unit of carbon consumption tends to increase as the blowing amount increases. If the blowing amount of hydrogen gas in a gas containing a high concentration of hydrogen is increased to some extent, the reduction rate Input ΔC of the basic unit of carbon consumption, for example, becomes 7% or more. Therefore, by blowing into the blast furnace the amount of gas containing high-concentration hydrogen, which is determined based on the amount of hydrogen in the appropriate range, the amount of CO ₂ emissions can be drastically reduced. For example, as shown in the embodiments described later, the reduction rate Input ΔC of the basic unit of carbon consumption during blast furnace operation can be set to 7% or more, and CO ₂ emissions can be significantly reduced. The inventor of the present case considered the operation method of the blast furnace of the present embodiment based on the above knowledge. Hereinafter, this embodiment will be described in detail.

<2. Composition of gas containing high concentration of hydrogen> The operating method of the blast furnace in this embodiment is to blow a gas containing high concentration of hydrogen from a tuyere. Therefore, first, the composition of a gas containing a high concentration of hydrogen will be explained. As mentioned above, the high-concentration hydrogen-containing gas system contains more than 80 mol% hydrogen gas. Gases containing high concentrations of hydrogen include pure hydrogen. The gas containing high-concentration hydrogen may also include gases other than hydrogen, such as the aforementioned carbon-containing reducing gas (such as hydrocarbon gas), CO gas, CO ₂ gas, H ₂ O gas, and N ₂ gas. However, the total concentration of other gases is less than 20mol%.

Gases with a total concentration of other gases above 20 mol% are not included in the gas containing high-concentration hydrogen in this embodiment. The reason is that when the concentration of other gases is above 20 mol%, _{the reduction of CO 2} gas will be greatly reduced. For example, among other gases, hydrocarbon gas, CO ₂ gas and H ₂ O gas will produce an endothermic reaction when decomposing at the outlet of the tuyere, which will reduce the reduction efficiency in the blast furnace. Therefore, the iron-based raw materials reaching the lower part of the blast furnace without being reduced increase. Furthermore, the amount of direct reduction reaction by coke increases. As a result, in order to maintain the temperature in the blast furnace, more reducing materials are required, and the _{amount of CO 2} gas reduction is greatly reduced. For example, when COG (coke oven gas) containing 50 mol% hydrogen is blown into the blast furnace at a blowing rate of ^{600 Nm 3} /t, hydrogen is blown into the blast furnace at a blowing rate of ^{300 Nm 3 /t.} Compared to when pure hydrogen is blown into the blast furnace at a blowing rate of ^{300 Nm 3} _{/t, the effect of reducing CO 2} emissions at this time is very inferior, and it cannot lead to a fundamental reduction in CO ₂ emissions (such as the basic unit of carbon consumption). Reduction ratio Input ΔC≧7%). In addition, in the case of pure hydrogen gas at room temperature as shown in the examples described later, the effect of reducing CO ₂ ^{emissions is maximized when the injection rate is about 300 Nm 3 /t.}

＜3. How to operate the blast furnace＞ Next, the operation method of the blast furnace in this embodiment will be explained. In the operating method of the blast furnace of the present embodiment, first, the blowing temperature of the gas containing high-concentration hydrogen is determined in the range above normal temperature.

Here, referring to FIG. 1, the blowing temperature of the gas containing high-concentration hydrogen (hereinafter, this may be simply referred to as "blowing temperature") will be described. Fig. 1 is a diagram for explaining the blowing temperature. The temperature of the gas containing high-concentration hydrogen can be adjusted in the gas tank 3 provided with the heater 5, for example. That is, the gas containing high-concentration hydrogen can be heated by the heater 5 in the gas tank 3 or sent directly to the tuyere 2 for blowing in hot air without heating at room temperature. The tuyere 2 is installed in the blast furnace 1. The lower part of the furnace. The gas containing high-concentration hydrogen sent to the tuyere 2 can be blown into the blast furnace 1 from the tuyere 2. Specifically, the high-concentration hydrogen-containing gas system sent to the tuyere 2 is mixed (combined) with the hot air generated in the hot blast stove 4 and then blown into the blast furnace 1 from the tuyere 2. The blowing temperature is the temperature of the high-concentration hydrogen-containing gas immediately before being mixed with the hot air when blowing into the blast furnace 1 from the tuyere 2. In the actual operation (the actual furnace), for example, since the temperature will not decrease from heating the heater 5 of the gas containing high-concentration hydrogen to blowing into the blast furnace 1, the set temperature of the heater 5 can be set as blowing入温度。 Into the temperature. Although the temperature of the gas containing high concentration of hydrogen may rise due to the mixing of hot air and the gas containing high concentration of hydrogen, the temperature at this time is not the blowing temperature of this embodiment. In addition, patent document 1 describes the blowing temperature, but the blowing temperature of patent document 1 is different from the blowing temperature in this embodiment.

As shown in the examples described later, in the case where the gas containing high concentration hydrogen is not heated but is directly blown in from the tuyere at room temperature, the CO ₂ emissions can also be significantly reduced (see FIG. 2). Figure 2 is a graph showing the correlation between the amount of pure hydrogen blown in at room temperature and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. This chart can be obtained through blast furnace operation simulation. Details will be described in the examples, where Kouji TAKATANI, Takanobu INADA, and Yutaka UJISAWA, "Three-dimensional Dynamic Simulator for Blast Furnace", ISIJ International, Vol. 39 (1999), No. 1, p. 15 are used here. The so-called "Blast Furnace Mathematical Model" shown in -22, etc. The blast furnace mathematical model, in summary, regulates multiple grids (small regions) by dividing the internal area of the blast furnace in the height direction, diameter direction, and circumferential direction, and simulates the behavior of each grid. The simulation conditions are the same as those in the later-described embodiment. As shown in Figure 2, when the amount of pure hydrogen injected at room temperature reaches 200 to 500 Nm ³ /t, the reduction rate Input ΔC of the basic unit of carbon consumption can be made, for example, 7% or more. The reduction ratio Input ΔC of the basic unit of carbon consumption should be 8% or more. In addition, the "normal temperature" in this embodiment means a state without heating, and specifically it is set to a temperature of 5°C or higher and 35°C or lower.

The details will be explained later. When the blowing temperature is above room temperature, the higher the blowing temperature of a gas containing high concentration of hydrogen, the larger the input ΔC for the reduction ratio of the basic unit of carbon consumption for the same blowing amount ( Refer to Figure 2~Figure 10). Fig. 3 is a graph showing the correlation between the amount of pure hydrogen blown in at 300°C and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Figure 4 is a graph showing the correlation between the amount of pure hydrogen blown in at 350°C and the reduction ratio Input ΔC of the basic unit of carbon consumption. Fig. 5 is a graph showing the correlation between the amount of pure hydrogen blown in at 600°C and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Fig. 6 is a graph showing the correlation between the amount of pure hydrogen blown in at 650°C and the reduction ratio Input ΔC of the basic unit of carbon consumption. Fig. 7 is a graph showing the correlation between the amount of pure hydrogen blown in at 900°C and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Fig. 8 is a graph showing the correlation between the amount of pure hydrogen blown in at 950°C and the reduction ratio Input ΔC of the basic unit of carbon consumption. Figure 9 is a graph showing the correlation between the amount of pure hydrogen blown in at 1200°C and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Fig. 10 is a graph showing the correlation between the amount of pure hydrogen blown in at 1250°C and the reduction ratio Input ΔC of the basic unit of carbon consumption.

These graphs can be obtained through the above-mentioned blast furnace operation simulation. The details will be described in the embodiment. It can be seen that the reduction ratio Input ΔC of the basic unit of carbon consumption in Figs. 3 to 10 is higher than the reduction ratio Input ΔC of the basic unit of carbon consumption in Fig. 2. And it can be considered that the higher the blowing temperature of the gas containing high-concentration hydrogen, the higher the sensible heat of the hearth gas (mixed gas of nitrogen, hydrogen and CO gas) generated in the blast furnace, so that more reducing gas will be Reduction of iron-based raw materials. That is, the reduction efficiency is improved. Therefore, it can be considered that the higher the blowing temperature of the gas containing high-concentration hydrogen, the larger the reduction ratio Input ΔC of the basic unit of carbon consumption. Therefore, from the viewpoint of increasing the reduction ratio Input ΔC of the basic unit of carbon consumption, it is preferable to increase the blowing temperature of a gas containing a high concentration of hydrogen. Specifically, it is preferable to determine the blowing temperature in a range higher than 300°C, preferably in a range higher than 600°C, and more preferably in a range higher than 900°C.

However, in order to make the blowing temperature of the gas containing high concentration hydrogen higher than 600°C, large-scale modification of equipment is sometimes required. Therefore, if it is difficult to use existing equipment to make the blowing temperature of the gas containing high concentration hydrogen higher than 600°C, it is also possible to determine the blowing temperature of the gas containing high concentration hydrogen within the range of normal temperature to 600°C. On the other hand, it is possible to use existing equipment (or by modifying existing equipment) to make the blowing temperature of high-concentration hydrogen-containing gas higher than 600°C, and it can also be determined to contain high-concentration hydrogen within the range of higher than 600°C. The blowing temperature of the gas.

Next, determine the amount of hydrogen gas in the gas containing high-concentration hydrogen. Here, the blowing amount of hydrogen in the gas with high concentration of hydrogen is the flow rate of the hydrogen in the gas with high concentration of hydrogen blown into the blast furnace from the tuyere per 1 ton of melt milling, and the unit is Nm ³ /t. When the high-concentration hydrogen-containing gas is pure hydrogen, the blowing amount of hydrogen in the high-concentration hydrogen-containing gas is equal to the blowing amount of the high-concentration hydrogen-containing gas. When the high-concentration hydrogen-containing gas is a mixed gas containing other gases other than hydrogen, the blowing amount of hydrogen in the high-concentration hydrogen-containing gas is the blowing amount of the high-concentration hydrogen-containing gas in unit mol% multiplied by The amount derived from the ratio of hydrogen. In actual operation, the value shown by the flowmeter set at the discharge port of the gas supply source (such as the gas tank) containing the high concentration of hydrogen can be compared with the hydrogen in the gas containing the high concentration of hydrogen in mol%. Calculate the amount of hydrogen blown into the gas containing high-concentration hydrogen.

In the present embodiment, the blowing amount of the gas containing high-concentration hydrogen is classified according to the blowing temperature. Specifically, when the blowing temperature reaches normal temperature to 300°C, the blowing amount of hydrogen in the gas containing high concentration of hydrogen is determined within the range of ^{200 to 500 Nm 3 /t.} On the other hand, when the blowing temperature is higher than 300°C and lower than 600°C, the blowing amount of hydrogen in the gas containing high concentration of hydrogen is determined within the range of ^{145Nm 3 /t.} When the blowing temperature of the gas containing high concentration of hydrogen is higher than 600°C and below 900°C, the blowing amount of the gas containing high concentration of hydrogen is determined in the range of ^{125Nm 3 /t or more.} When the blowing temperature of the high-concentration hydrogen-containing gas is higher than 900°C and below 1200°C, the blowing amount of hydrogen in the high-concentration hydrogen-containing gas is determined in the range of ^{110Nm 3 /t or more.} When the blowing temperature of high-concentration hydrogen-containing gas is higher than 1200°C, the blowing amount of hydrogen in the high-concentration hydrogen-containing gas is determined within the range of ^{100Nm 3 /t or more.}

The reason for the classification by blowing temperature in the manner described above is that depending on the blowing temperature, the preferable blowing amount is slightly different. In addition, although the following description takes the case where the gas containing a high concentration of hydrogen is pure hydrogen as an example, as shown in Example 1-2 described later, even when the gas containing a high concentration of hydrogen contains a gas other than hydrogen In this case, the correlation between the blowing temperature of the gas containing high concentration of hydrogen and the preferable blowing amount remains unchanged.

As shown in Figures 2 and 3, when the blowing temperature of the gas containing high concentration of hydrogen reaches normal temperature ~ 300℃, if the blowing amount of the gas containing high concentration of hydrogen is gradually increased from 0 in the basic operation, then The reduction ratio Input ΔC of the basic unit of carbon consumption increases. Moreover, when the injection rate of hydrogen in a gas containing high concentration of hydrogen reaches about 300Nm ³ /t, the reduction ratio Input ΔC of the basic unit of carbon consumption reaches a peak, if the injection rate of hydrogen in a gas containing high concentration of hydrogen If it increases further, the reduction ratio Input ΔC of the basic unit of carbon consumption turns to decrease. In addition, when the blowing amount of hydrogen in the gas with high concentration of hydrogen is within the range of 200 to 500 Nm ³ /t, the reduction rate Input ΔC of the basic unit of carbon consumption can be 7% or more. In addition, when the gas containing high concentration of hydrogen is pure hydrogen, the amount of hydrogen in the gas containing high concentration of hydrogen will be the amount of blowing of the gas containing high concentration of hydrogen, but when the gas containing high concentration of hydrogen contains hydrogen other than hydrogen In the case of the gas, the value will be the amount of the gas containing high concentration of hydrogen multiplied by the hydrogen ratio (mol%).

The reaction of reducing iron-based raw materials by hydrogen (that is, the hydrogen reduction reaction) is an endothermic reaction. Therefore, it can be considered that when the blowing amount of hydrogen in the gas containing high concentration of hydrogen exceeds 300 Nm ³ /t, the endothermic reaction will occur in a large amount in the furnace, resulting in a decrease in the temperature in the furnace. In addition, it is considered that the reduction in the furnace temperature as described above causes a reduction in the reduction efficiency due to the reduction gas containing hydrogen. In order to prevent the reduction in the reduction efficiency described above, it is necessary to increase the reduction material ratio to perform work. Therefore, when the injection amount of hydrogen in the gas containing high concentration hydrogen is greater than 300 Nm ³ /t, the reduction ratio Input ΔC of the basic unit of carbon consumption turns to decrease. Therefore, when the blowing temperature reaches normal temperature ~ 300℃, the blowing amount of hydrogen in the gas containing high concentration hydrogen should be determined in the range of ^{200~400Nm 3} /t, preferably in the range of ^{200~300Nm 3 /t} Within the decision. In this case, the reduction rate Input ΔC of the basic unit of carbon consumption can be 8% or more.

As shown in Figures 4 and 5, when the blowing temperature of the gas containing high concentration of hydrogen is higher than 300°C and below 600°C, it is also the amount of hydrogen blowing in the gas containing high concentration of hydrogen ^{Gradually increasing from 0Nm 3} /t of the basic operation, the reduction ratio Input ΔC of the basic unit of carbon consumption increases. In addition, if the blowing amount of hydrogen in the gas containing high concentration of hydrogen is ^{more than 145Nm 3} /t, the reduction rate Input ΔC of the basic unit of carbon consumption will reach 7% or more. When the blowing temperature of the gas containing high concentration of hydrogen is 600℃, as shown in Figure 5, the blowing amount of hydrogen in the gas containing high concentration of hydrogen is about 600Nm ³ /t, the basic unit of carbon consumption The reduction ratio Input ΔC reaches saturation. When the blowing temperature of the gas containing high concentration of hydrogen is 350℃, as shown in Figure 4, when the blowing amount of hydrogen in the gas containing high concentration of hydrogen reaches about 300Nm ³ /t, the basic unit of carbon consumption The reduction ratio Input ΔC reaches a peak. If the amount of hydrogen injected in a gas with high concentration of hydrogen increases, the reduction ratio Input ΔC, which is the basic unit of carbon consumption, will decrease. In addition, when the blowing temperature of the gas containing high concentration of hydrogen is 350°C, if the blowing amount of hydrogen in the gas containing high concentration of hydrogen exceeds 600Nm ³ /t, it may be difficult to maintain the temperature Tf at the outlet end of the tuyere. At 2200°C. In the conventional blast furnace operation, the temperature Tf before the tuyere is mostly set at about 2200°C. If the temperature Tf before the tuyere is difficult to maintain at 2200°C, the operating conditions will have to be significantly changed from those of the previous blast furnace operation.

When the blowing temperature of the high-concentration hydrogen-containing gas is 350°C, the reason why the reduction ratio Input ΔC of the basic unit of carbon consumption is reduced is the same as the above. When the blowing temperature of the gas containing high-concentration hydrogen is 600°C, in the range up to the blowing amount of 700 Nm ³ /t, the reduction rate Input ΔC of the basic unit of carbon consumption does not decrease. However, when the blowing amount of hydrogen in the gas containing high concentration of hydrogen is about 600 Nm ³ /t, the reduction effect of the basic unit of carbon consumption is saturated. When the blowing temperature is higher than 350°C and below 600°C, the sensible heat of the furnace gas is greater. Therefore, the influence of the endothermic heat caused by the hydrogen reduction reaction is reduced, and it can be considered that even if more hydrogen is blown in than in the above-mentioned case, the temperature in the furnace is not easily lowered. Therefore, it can be considered that even if a large amount of hydrogen is blown into the blast furnace, the temperature in the furnace is not easily lowered, and the reduction efficiency is not easily lowered. Therefore, it can be considered that the reduction ratio Input ΔC of the basic unit of carbon consumption has reached saturation. In addition, when the blow-in amount of hydrogen in the gas with high concentration of hydrogen reaches 300~600Nm ³ /t, the reduction rate Input ΔC of the basic unit of carbon consumption will be more than 10%.

As shown in Figures 6 and 7, when the blowing temperature is higher than 600°C and below 900°C, it is also true that if the blowing amount of hydrogen in a gas containing high concentration of hydrogen is changed from 0Nm ³ / of the basic operation As t gradually increases, the reduction ratio Input ΔC of the basic unit of carbon consumption increases. In addition, when the injection amount of hydrogen in the gas containing high-concentration hydrogen ^{is within the range of 125 Nm 3} /t or more, the reduction ratio Input ΔC of the basic unit of carbon consumption is 7% or more. In particular, when the injection amount of hydrogen in a gas containing high-concentration hydrogen ^{is within the range of 180 Nm 3} /t or more, the reduction rate Input ΔC of the basic unit of carbon consumption is more than 10%. In addition, as the injected amount of hydrogen in a gas containing high concentration of hydrogen increases, the reduction rate of the basic unit of carbon consumption Input ΔC increase rate (the reduction rate of the basic unit of carbon consumption relative to the increase of the injected amount of carbon input Although the increase in ΔC) decreased, the reduction ratio Input ΔC, which is the basic unit of carbon consumption, did not turn into a decrease. This behavior is significantly different from the case where the blowing temperature of a gas containing a high concentration of hydrogen is below 600°C. In addition, Fig. 7 shows the reduction ratio of the amount of hydrogen in the gas containing high-concentration hydrogen and the reduction ratio of the basic unit of carbon consumption when the blowing temperature of the gas containing high-concentration hydrogen (pure hydrogen here) reaches 900°C. In the graph of the correlation of ΔC, the same tendency as in Fig. 7 can be observed even when the blowing temperature of a gas containing a high concentration of hydrogen reaches 650°C. For example, as shown in Figure 6, when the blowing temperature of the gas containing high concentration of hydrogen reaches 650°C and the blowing amount of the gas containing high concentration of hydrogen reaches 125Nm ³ /t or more, the reduction ratio Input ΔC of the basic unit of carbon consumption will be Above 7.0%.

As described above, the reduction reaction by hydrogen is an endothermic reaction. Therefore, once the amount of hydrogen injected in a gas containing high-concentration hydrogen increases to a certain extent, the reduction ratio Input ΔC of the basic unit of carbon consumption will decrease. However, if the blowing temperature of the gas containing high concentration of hydrogen is higher than 600°C, the sensible heat of the hearth gas generated in the blast furnace becomes very high, so the reaction heat required for the reduction reaction can be supplied. Therefore, it can be inferred that even if the injection amount of hydrogen gas in a gas with a high concentration of hydrogen increases, the reduction rate Input ΔC of the basic unit of carbon consumption will not decrease, but will continue to increase. The behavior can be observed when the blowing temperature of a gas containing a high concentration of hydrogen is higher than 600°C. Therefore, from the viewpoint of further increasing the reduction ratio Input ΔC of the basic unit of carbon consumption, the upper limit of the injection amount of hydrogen in the gas containing high-concentration hydrogen is not particularly set. However, as the injection amount of hydrogen in a gas with high concentration of hydrogen increases, the reduction rate of the basic unit of carbon consumption, the increase rate of Input ΔC, will decrease. Therefore, assuming a certain amount of injection, the rate of increase of the basic unit of carbon consumption The reduction effect reaches the upper limit. It is assumed that the blow-in amount at this time is approximately 1000 Nm ³ /t. Therefore, the blowing amount of hydrogen gas in a gas containing high-concentration hydrogen can also be 1000 Nm ³ /t or less.

As shown in Fig. 8 and Fig. 9, when the blowing temperature is higher than 900°C and lower than 1200°C, it is also true that if the blowing amount of hydrogen in the gas with high concentration of hydrogen is changed from 0Nm ³ / of the basic operation As t gradually increases, the reduction ratio Input ΔC of the basic unit of carbon consumption increases. In addition, when the injection amount of hydrogen in the gas containing high-concentration hydrogen ^{is within the range of 110 Nm 3} /t or more, the reduction ratio Input ΔC of the basic unit of carbon consumption is 7% or more. In particular, when the injection amount of hydrogen in a gas containing high-concentration hydrogen ^{is within the range of 150 Nm 3} /t or more, the reduction rate Input ΔC of the basic unit of carbon consumption is more than 10%. In addition, as in the case where the blowing temperature of the gas containing high concentration of hydrogen is higher than 600°C and below 900°C, as the blowing amount of hydrogen in the gas containing high concentration of hydrogen increases, the basic unit of carbon consumption is reduced. Although the increase rate of Input ΔC decreased, the reduction rate Input ΔC of the basic unit of carbon consumption did not turn into a decrease. In addition, Fig. 9 shows the reduction ratio of the amount of hydrogen in the gas containing high concentration of hydrogen and the reduction ratio of the basic unit of carbon consumption when the blowing temperature of the gas containing high concentration of hydrogen (here, pure hydrogen) reaches 1200°C. In the graph of the correlation of ΔC, the same tendency as in Fig. 9 can be observed even when the blowing temperature of a gas containing a high concentration of hydrogen reaches 950°C. For example, as shown in Figure 8, when the blowing temperature of the gas containing high concentration of hydrogen reaches 950°C and the blowing amount of the gas containing high concentration of hydrogen reaches 110Nm ³ /t or more, the carbon consumption basic unit reduction ratio Input ΔC will be at 7.0% or more.

Therefore, from the viewpoint of further increasing the reduction ratio Input ΔC of the basic unit of carbon consumption, the upper limit of the injection amount of hydrogen in the gas containing high concentration of hydrogen is not particularly set. However, assuming that the blowing amount of hydrogen in a gas containing high concentration of hydrogen reaches about 1000 Nm ³ /t, the reduction effect of the basic unit of carbon consumption reaches the upper limit, so the blowing amount of hydrogen in a gas containing high concentration of hydrogen is also acceptable. It is ^{less than 1000Nm 3} /t.

In addition, according to the blast furnace operation simulation, when the blowing temperature of the gas containing high concentration of hydrogen reaches 1200℃ and the blowing amount of hydrogen in the gas containing high concentration of hydrogen reaches 800Nm ³ /t or more, the blowing amount of pulverized coal will become 0, by reducing the coke ratio, the basic unit of carbon consumption can be further reduced. Generally speaking, in the blast furnace operation, reducing the coke ratio will lead to an increase in pressure loss and make the operation unstable. Here, the pressure loss refers to the pressure at the outlet of the tuyere (before the tuyere), in other words the difference between the pressure in the furnace at the outlet of the tuyere and the pressure at the top of the furnace, and refers to the pressure loss of the pipeline from the blower to the outlet of the tuyere is eliminated The value. In actual operation, the pressure loss can be measured with a pressure gauge installed on the furnace wall. However, as shown in Figure 14, in the blast furnace operation under high hydrogen concentration conditions as in the present embodiment, the gas viscosity and gas density in the furnace are greatly reduced, so the doubt that the pressure loss will increase after reducing the coke ratio can be relieved. In actual operation, the pressure loss can be stabilized without any problems. In addition, Fig. 14 is a graph showing the correlation between the amount of pure hydrogen injected at 1200°C and the change in pressure loss in the furnace when the temperature before the tuyere reaches 2100°C, and it is obtained by blast furnace operation simulation. The pressure loss in normal operation is roughly based on about 85kPa. According to Fig. 14, it can be seen that the pressure loss is less than 85 kPa under the operating conditions of this embodiment.

As shown in Figure 10, when the blowing temperature is higher than 1200°C, if the blowing amount of hydrogen in the gas containing high concentration of hydrogen is ^{gradually increased from 0Nm 3} /t in the basic operation, the carbon consumption is basically The unit reduction ratio Input ΔC increases. In addition, when the injection amount of hydrogen in the gas containing high-concentration hydrogen ^{is within the range of 100 Nm 3} /t or more, the reduction rate Input ΔC of the basic unit of carbon consumption is 7% or more. In addition, as in the case where the blowing temperature of the gas containing high concentration of hydrogen is higher than 600°C and below 900°C, as the blowing amount of hydrogen in the gas containing high concentration of hydrogen increases, the basic unit of carbon consumption is reduced. Although the increase rate of Input ΔC decreased, the reduction rate Input ΔC of the basic unit of carbon consumption did not turn into a decrease. Therefore, from the viewpoint of further increasing the reduction ratio Input ΔC of the basic unit of carbon consumption, the upper limit of the injection amount of hydrogen in the gas containing high-concentration hydrogen is not particularly set. However, assuming that the blowing amount of hydrogen in a gas containing high concentration of hydrogen reaches about 1000 Nm ³ /t, the reduction effect of the basic unit of carbon consumption reaches the upper limit, so the blowing amount of hydrogen in a gas containing high concentration of hydrogen is also acceptable. It is ^{less than 1000Nm 3} /t.

As long as it is an environment in which the blowing temperature of a gas containing a high concentration of hydrogen can be higher than 600°C, the upper limit of the blowing temperature is not particularly limited. However, as shown in Figs. 15 and 16, the reduction effect of the basic unit of carbon consumption is almost the same in the range where the blowing temperature of the gas containing a high concentration of hydrogen is higher than 1200°C and to about 1400°C. 15 and 16 are graphs showing the correlation between the blowing temperature of pure hydrogen and the blowing amount of pure hydrogen. The blowing amount of pure hydrogen is used to make the reduction ratio Input ΔC of the basic unit of carbon consumption 10 % Or 20% of the required amount. And the temperature Tf in front of the tuyere is set to 2100°C. These graphs organize the correlations of Figures 2 to 10 into graphs of the correlation between the blowing temperature of pure hydrogen and the blowing amount of pure hydrogen. The blowing amount of pure hydrogen is used to make the basic unit of carbon consumption. The reduction ratio Input ΔC is the amount required to become 10% or 20%. Therefore, the blowing temperature of the gas containing high-concentration hydrogen may be 1400°C or less. That is, the blowing temperature of the gas containing high-concentration hydrogen may be, for example, higher than 600°C and lower than 1400°C.

Next, the gas containing high-concentration hydrogen is blown in from the tuyere at the determined blowing temperature and blowing amount. As a result, the reduction ratio Input ΔC of the basic unit of carbon consumption can be made, for example, 7% or more, and CO ₂ emissions can be significantly reduced. In addition, a tuyere for blowing in a gas containing a high concentration of hydrogen is, for example, a tuyere for blowing in hot air provided in the lower part of the furnace. In this embodiment, the description is based on the premise that the gas containing high concentration of hydrogen is blown in from the tuyere for blowing in the hot air, but the tuyere for blowing the gas containing the high concentration of hydrogen is not limited to this. Other examples of tuyere may be a so-called neck tuyere provided in the neck of the furnace. The gas with high concentration of hydrogen can be blown into the blast furnace from any one of the tuyere, and can also be blown into the blast furnace from two tuyeres. When the gas containing high concentration of hydrogen is blown into the blast furnace from a plurality of tuyeres, the total amount of hydrogen in the gas containing high concentration of hydrogen blown from each tuyere is consistent with the above-determined blowing amount.

In addition, by appropriately setting the blowing temperature, the blowing amount, the temperature Tf in front of the tuyere, and the like of the hydrogen gas under the conditions of the present embodiment, the operation of appropriately maintaining the top gas temperature can be realized. Therefore, it is not necessary to blow the preheating gas and preheat the contents of the furnace in order to maintain the temperature of the furnace top gas, but they can be implemented separately.

＜4. Modifications＞ (4-1. Modification 1) Hereinafter, various modifications of the operating method of the blast furnace will be described. In Modification 1, the temperature Tf before the tuyere is maintained at 2050°C or lower. Here, the tuyere front temperature Tf is the temperature in the furnace at the front end of the furnace inner side of the tuyere, and is also referred to as the tuyere outlet temperature Tf. In actual operation, the temperature Tf in front of the tuyere is calculated as the theoretical combustion temperature at the tuyere outlet according to the Lamb formula described in the "Milling Handbook" by Remi Akari (Diren Shuguan).

As shown in Figure 2, Figure 3, Figure 5, Figure 7 and Figure 9, the carbon consumption when the temperature Tf before the tuyere is below 2050°C (2000°C in Figure 2, Figure 3, Figure 5, Figure 7 and Figure 9) The reduction ratio of the basic unit Input ΔC is the reduction ratio of the basic unit of carbon consumption when the temperature Tf before the tuyere is higher than 2050℃ (2100℃, 2200℃ in Figure 2, Figure 3, Figure 5, Figure 7 and Figure 9) Input ΔC is greater. Therefore, in Modification 1, the temperature Tf before the tuyere is maintained at 2050°C or lower. In this way, the reduction ratio Input ΔC of the basic unit of carbon consumption can be further increased. In addition, as shown in Figures 7 and 9, when the blowing temperature of the gas containing high concentration of hydrogen is higher than 600°C, when the blowing amount of hydrogen in the gas containing high concentration of hydrogen reaches 400Nm ³ /t or more , The tendency is obvious. Therefore, when the blowing temperature of the gas containing high concentration of hydrogen is set to be higher than 600°C, and the blowing amount of hydrogen in the gas containing high concentration of hydrogen is set to 400Nm ³ /t or more, it is also possible to set The temperature Tf in front of the tuyere is set to 2050°C or less.

Here, since the blowing temperature of the gas containing high concentration of hydrogen is lower than that of hot air, blowing the gas containing high concentration of hydrogen into the blast furnace will cause the temperature Tf in front of the tuyere to decrease. In order to make the temperature Tf in front of the tuyere reach the desired temperature, that is, in order to increase the temperature Tf in front of the tuyere, it is necessary to increase the oxygenation rate for operation. Here, the hot air blown into the blast furnace is a gas containing air. In addition to air, hot air may also contain moisture and increased oxygen. In summary, the oxygen increase rate is the ratio of the volume of oxygen in the hot air to the total volume of the hot air, and is expressed as: oxygen increase rate (%)={(air supply volume (flow rate) [Nm ³ /min]×0.21+increase Oxygen volume [Nm ³ /min])/(Air supply volume [Nm ³ /min] + oxygen increase volume [Nm ³ /min])}×100-21. In actual operation, ^{the total flow rate of the incremental oxygen in the unit Nm 3} /t and the oxygen in the hot air, that is, the oxygen flow rate, is not changed, but the incremental oxygen flow rate and the air flow rate in the ^{unit Nm 3 /t are changed.} To adjust the oxygenation rate. The reason is to make the iron tapping ratio (the ^{amount of iron per 1 m 3} of the furnace inner volume per day) as constant as possible. Therefore, if the oxygen increase rate increases, the hot air flow rate will decrease. As a result, the amount of gas in the hearth is reduced.

As a result, the higher the temperature Tf before the tuyere, the lower the amount of gas in the hearth. And if the amount of gas in the hearth decreases, the sensible heat of the gas in the hearth decreases. Therefore, the temperature in the furnace tends to be lowered due to the endothermic heat caused by the hydrogen reduction reaction. However, in order to prevent the temperature in the furnace from lowering, it is necessary to increase the ratio of reducing material. Therefore, it can be considered that the reduction ratio Input ΔC of the basic unit of carbon consumption when the temperature Tf before the tuyere is below 2050°C will become larger than the reduction ratio Input ΔC of the basic unit of carbon consumption when the temperature Tf before the tuyere is higher than 2050°C.

In addition, from the viewpoint of thermal conductivity of melt milling and pulverized coal combustibility, the temperature Tf in front of the tuyere is preferably 2000°C or higher. However, as long as the reduction ratio Input ΔC of the basic unit of carbon consumption is sufficiently increased and the ratio of pulverized coal (pulverized coal used per 1 ton of melt milling) can be sufficiently reduced, the temperature Tf in front of the tuyere can also be lower than 2000°C. For example, even if the temperature Tf before the tuyere is lower than 2000°C, as long as the reduction ratio Input ΔC of the basic unit of carbon consumption can be maintained and stable operation can be achieved, the temperature Tf before the tuyere may be lower than 2000°C. For example, as described above, when the blowing temperature of the gas containing high concentration of hydrogen reaches 1200°C and the blowing amount of hydrogen in the gas containing high concentration of hydrogen reaches 800Nm ³ /t or more, the blowing amount of pulverized coal will become 0 (that is, the pulverized coal ratio is 0). In this case, there is no need to consider the combustion of pulverized coal, so even if the temperature Tf in front of the tuyere is set to less than 2000°C, the reduction rate Input ΔC of the basic unit of carbon consumption can still be maintained, and stable operation can be achieved. Therefore, the temperature Tf in front of the tuyere can be set to less than 2000°C. That is, if the blowing temperature of the gas containing high-concentration hydrogen is increased and the blowing amount is increased, so that the blowing amount of pulverized coal can be made zero, the temperature Tf in front of the tuyere may be lower than 2000°C.

(4-2. Modification 2) In Modification 2, the temperature Tf in front of the tuyere is maintained above 2050°C and below 2150°C. According to Modification 1, by setting the temperature Tf in front of the tuyere to 2050°C or less, the reduction ratio Input ΔC of the basic unit of carbon consumption can be increased. On the other hand, if the temperature Tf in front of the tuyere decreases, the combustion rate of pulverized coal may decrease. That is, if the temperature Tf in front of the tuyere is lowered, the pulverized coal will not burn easily. When the pulverized coal is flame-retardant or when the pulverized coal ratio is increased, the possibility that the combustion rate of pulverized coal will decrease will increase. If the combustion rate of pulverized coal is lowered, the temperature in the furnace will be lowered. Therefore, it will be necessary to perform operations that only increase the ratio of reduced materials by this amount. From this viewpoint, in Modification 2, the temperature Tf in front of the tuyere is maintained at a temperature higher than 2050°C and lower than 2150°C. Thereby, the combustion rate of pulverized coal can be maintained, and the temperature drop in the furnace can be suppressed.

(4-3. Modification 3) In Modification 3, the temperature Tf in front of the tuyere is maintained above 2150°C. In the conventional blast furnace operation, the temperature Tf before the tuyere is mostly set at about 2200°C. Therefore, by setting the temperature Tf in front of the tuyere to be higher than 2150°C, the operation conditions can be operated without drastically changing from the conventional blast furnace operation. In addition, from the viewpoint of protecting tuyere equipment, etc., the temperature Tf in front of the tuyere is preferably 2250°C or less.

(4-4. Modification 4) As shown in Figures 2 to 10, there is a fixed correlation between the amount of hydrogen injected in a gas containing high-concentration hydrogen and the reduction ratio Input ΔC of the basic unit of carbon consumption. Therefore, in Modification 4, the correlation between the injection amount and the reduction ratio of the basic unit of carbon consumption is calculated in advance, which is the ratio of the injection amount of hydrogen in the gas containing high-concentration hydrogen to the reduction ratio of the basic unit of carbon consumption Input ΔC relationship.

For example, through the blast furnace operation simulation, the reduction ratio Input ΔC of the basic unit of carbon consumption is calculated for the injection amount of several points. The blast furnace operation simulation includes the injection temperature of the gas containing high concentration of hydrogen and reflects the current situation of the blast furnace operation By. The specific method only needs to be the same method as in the below-mentioned embodiment.

Next, set the horizontal axis as the ^{amount of hydrogen injected in the gas containing high-concentration hydrogen in the unit Nm 3} /t, and the vertical axis as the reduction rate Input ΔC (%) of the basic unit of carbon consumption. Draw the value obtained by the above method on the plane. Next, the approximate curve of the drawing points is calculated by, for example, the least square method, and the approximate curve, more specifically, the relationship that expresses the approximate curve is used as the above-mentioned injection amount-carbon consumption basic unit reduction ratio correlation relationship. . The correlation between the blow-in amount and the reduction ratio of the basic unit of carbon consumption should be calculated based on the temperature Tf in front of each tuyere.

Next, based on the above-obtained correlation between the amount of injection and the reduction rate of the basic unit of carbon consumption, the reduction rate of the basic unit of carbon consumption is determined. quantity. Next, the gas containing high-concentration hydrogen is blown in from the tuyere according to the determined blow-in amount. By this, it is possible to more reliably increase the reduction ratio Input ΔC of the basic unit of carbon consumption.

Here, the correlation between the amount of injection and the reduction ratio of the basic unit of carbon consumption should be calculated in advance based on the injection temperature of each gas containing a high concentration of hydrogen. Thereby, even when the blowing temperature changes, the blowing amount of hydrogen gas in the desired high-concentration hydrogen-containing gas can be easily determined. That is, even when the blowing temperature fluctuates, it is easy to determine the blowing amount of hydrogen in the high-concentration hydrogen-containing gas with an increase in the reduction ratio Input ΔC of the basic unit of carbon consumption.

(4-5. Modification 5) Figure 12 shows the ^{amount of pure hydrogen blown in at room temperature in Nm 3} /t based on the temperature Tf in front of each tuyere and the change in pressure loss relative to the unit kPa of the basic operation. The graph of the correlation, the basic operation is an operation that does not blow in a gas containing a high concentration of hydrogen. This chart can be obtained through blast furnace operation simulation. The details will be described in the embodiment. Here, the pressure loss refers to the pressure at the outlet of the tuyere (before the tuyere), in other words the difference between the pressure in the furnace at the outlet of the tuyere and the pressure at the top of the furnace, and refers to the pressure loss of the pipeline from the blower to the outlet of the tuyere is eliminated The value. In actual operation, the pressure loss can be measured with a pressure gauge installed on the furnace wall. The change in pressure loss from the basic operation is the value obtained by subtracting the pressure loss during the basic operation from the pressure loss during a certain operation. The pressure loss should be the same level as the basic operation or a value lower than that of the basic operation from the viewpoint of the restriction of the supply air pressure and the prevention of blow-through. Figure 12 shows the above-mentioned correlation when using pure hydrogen at room temperature. However, the above-mentioned correlation can also be obtained when using a gas containing high-concentration hydrogen other than pure hydrogen. Moreover, even if the blowing temperature of the gas containing high-concentration hydrogen is higher than the normal temperature, the above-mentioned correlation can still be obtained.

It is obvious from FIG. 12 that there is a fixed correlation between the amount of hydrogen injected in the gas containing high concentration of hydrogen and the amount of change in pressure loss. For example, when the blowing amount of hydrogen gas in a gas containing a high concentration of hydrogen is increased, the temperature Tf in front of the tuyere will decrease as described above. In order to make the temperature in front of the tuyere the desired temperature, it is necessary to increase the oxygenation rate for operation. In actual operation, ^{the total flow rate of the incremental oxygen in the unit Nm 3} /t and the oxygen in the hot air, that is, the oxygen flow rate, is not changed, but by changing the incremental oxygen flow rate and the air flow rate in the ^{unit Nm 3 /t,} To maintain the iron output ratio at a predetermined amount, while adjusting the oxygen increase rate. Therefore, if the oxygen increase rate increases, the hot air flow rate will decrease. As a result, the amount of gas in the hearth is reduced. In other words, when the temperature Tf in front of the tuyere is low, the amount of gas in the hearth increases. As a result, the pressure loss may increase compared to the basic operation. However, if the blowing amount of hydrogen in the gas containing high concentration of hydrogen is further increased, the gas viscosity and gas density of the gas in the furnace will decrease, and the pressure loss will decrease. Furthermore, the decrease in pressure loss due to the decrease in gas viscosity and gas density will cancel each other out with the increase in pressure loss due to the increase in the amount of gas in the hearth, resulting in a decrease in pressure loss.

In Modification 5, first, as in Modification 4, the correlation between the injection amount and the reduction ratio of the basic unit of carbon consumption is calculated in advance. In addition, the correlation between the blow-in amount and the pressure loss change is calculated, which is the correlation between the blow-in amount and the pressure loss change relative to the basic operation.

For example, through a blast furnace operation simulation, the pressure loss changes are calculated for the injection amounts of several points. The blast furnace operation simulation includes the injection temperature of a gas containing a high concentration of hydrogen and reflects the current situation of the blast furnace operator. The specific method only needs to be the same method as in the below-mentioned embodiment.

Next, let the horizontal axis be ^{the injection amount of hydrogen gas in the high-concentration hydrogen-containing gas in units of Nm 3} /t, and the vertical axis in the unit kPa as the amount of change in pressure loss, that is, Δ pressure loss, Draw the value obtained by the above method on the obtained plane. Next, the approximate curve of the drawing points is calculated by, for example, the least square method, and the approximate curve (more specifically, the relational expression representing the approximate curve) is used as the above-mentioned correlation between the injection amount and the pressure loss change amount. The relationship between the blow-in amount and the change in pressure loss should be calculated based on the temperature Tf in front of each tuyere.

Next, determine the injection volume based on the correlation between the injection volume and the reduction ratio of the basic unit of carbon consumption and the correlation between the injection volume and the change in pressure loss. The injection volume can make the reduction ratio Input ΔC of the basic unit of carbon consumption higher than the current situation. Larger operations can reduce carbon consumption and make the pressure loss change into a value within a predetermined range. Here, the predetermined range can be set to, for example, about -50 to +5 kPa, but it is not limited to this. Next, the gas containing high-concentration hydrogen is blown in from the tuyere according to the determined blow-in amount. Thereby, the pressure loss can be changed to a value within a predetermined range, and at the same time, the reduction ratio Input ΔC of the basic unit of carbon consumption can be increased more reliably.

(4-6. Modification 6) Figure 13 shows the ^{ratio of the amount of pure hydrogen injected in Nm 3} /t in Nm 3 /t and the temperature of the furnace top gas in the unit ℃ relative to the top gas temperature of the basic operation according to the temperature Tf in front of each tuyere A graph of the correlation between the amount of change. This chart can be obtained through blast furnace operation simulation. The details will be described in the embodiment. Here, the top gas temperature is the temperature of the top gas (mainly CO ₂ , N ₂ , unreacted CO, etc.) discharged from the top of the blast furnace, which is measured by a thermometer installed in the riser, etc. in actual operation . The amount of change relative to the top gas temperature of the basic operation is the value obtained by subtracting the top gas temperature of the basic operation from the top gas temperature of a certain operation. From the viewpoint of the limitation of furnace top equipment and the efficiency of the work, the top gas temperature should be the same level as the basic work. As an example, the top gas temperature of the basic work should be within the range of ±20℃. . Figure 13 shows the above-mentioned correlation when using pure hydrogen at room temperature. However, the above-mentioned correlation can also be obtained when using a gas containing high-concentration hydrogen other than pure hydrogen. Moreover, even if the blowing temperature of the gas containing high-concentration hydrogen is higher than the normal temperature, the above-mentioned correlation can still be obtained.

It is obvious from Fig. 13 that there is a fixed correlation between the amount of hydrogen injected in the gas containing high concentration of hydrogen and the amount of change in the top gas temperature. For example, when the blowing amount of hydrogen gas in a gas containing a high concentration of hydrogen is increased, the temperature Tf in front of the tuyere will decrease as described above. In order to make the temperature Tf in front of the tuyere the desired temperature, it is necessary to increase the oxygen increase rate for operation. In actual operation, the oxygen flow rate in the ^{unit Nm 3} /t is not changed, but the oxygen increase rate is adjusted by changing the air flow rate in the ^{unit Nm 3 /t.} Therefore, if the oxygen increase rate increases, the hot air flow rate will decrease. As a result, the amount of gas in the hearth is reduced. In other words, if the temperature Tf in front of the tuyere increases, the amount of gas in the hearth decreases. As a result, the heat flow ratio increases, and the heat flow ratio is expressed as (heat capacity of the furnace charge that falls in a unit time)/(heat capacity of the hearth gas that rises in a unit time). As a result, the temperature of the furnace gas rising in the furnace becomes easy to decrease, and as a result, the temperature of the furnace top gas tends to decrease. As a result, the top gas temperature may decrease compared to the basic operation. However, if the amount of hydrogen in the gas containing high concentration of hydrogen is gradually increased, roughly at 300 Nm ³ /t, the temperature in the furnace will drop due to the endothermic reaction as described above, and the reduction efficiency in the furnace will begin to decrease. In order to prevent the reduction in the reduction efficiency, the operation is performed by increasing the ratio of the reducing material. However, if the ratio of the reducing material is increased, the heat input into the furnace increases, and the top gas temperature tends to rise, which causes the top gas temperature to increase.

In Modification 6, first, as in Modification 4, the correlation between the injection amount and the reduction ratio of the basic unit of carbon consumption is calculated in advance. And calculate the correlation between the amount of blowing-the amount of change in furnace top gas temperature, which is the correlation between the amount of blowing and the amount of change in furnace top gas temperature relative to the basic operation.

For example, through a blast furnace operation simulation, the amount of change in the top gas temperature is calculated for the amount of injection at several points. The blast furnace operation simulation includes the injection temperature of a gas containing a high concentration of hydrogen and reflects the current situation of the blast furnace operator. The specific method only needs to be the same method as in the below-mentioned embodiment.

Next, the horizontal axis is set to the ^{amount of hydrogen injected in the gas containing high concentration of hydrogen in units of Nm 3} /t, and the vertical axis is set to the amount of change in the top gas temperature in units of °C, that is, Δ furnace The temperature of the top gas is plotted on the obtained plane with the value obtained by the above method. Next, calculate the approximate curve of the drawing points by, for example, the least square method, and use the approximate curve, more specifically, the relationship that expresses the approximate curve as the correlation between the injection amount and the top gas temperature change amount, namely Can. The correlation between blow-in amount and furnace top gas temperature change amount should be calculated based on the temperature Tf in front of each tuyere.

Next, the amount of injection is determined based on the correlation between the amount of injection and the reduction rate of the basic unit of carbon consumption and the relationship between the amount of injection and the amount of change in top gas temperature. The amount of injection can make the reduction rate of the basic unit of carbon consumption Input ΔC Compared with the current operation, the carbon consumption can be reduced, and the variation of the top gas temperature can be a value within a predetermined range. Here, the predetermined range can be set to, for example, about -20 to +20°C, but is not limited to this. Next, the gas containing high-concentration hydrogen is blown in from the tuyere according to the determined blow-in amount. Thereby, the amount of change in the top gas temperature can be within a predetermined range, and at the same time, the reduction ratio Input ΔC of the basic unit of carbon consumption can be increased more reliably.

Here, in the above-mentioned modified examples 4 to 6, the injection amount of hydrogen gas in the high-concentration hydrogen-containing gas becomes a pair of parameters, and it is not necessarily limited to the reduction ratio Input ΔC of the basic unit of carbon consumption. That is, the injection amount of hydrogen in the gas containing high concentration hydrogen becomes a pair of parameters, and it does not matter as long as it is a parameter involving carbon consumption, that is, a carbon consumption parameter. The reason is that as long as carbon consumption is reduced, CO ₂ emissions can be reduced. As the carbon consumption parameter, in addition to the reduction ratio Input ΔC of the basic unit of carbon consumption, the reduction ratio of the basic unit of carbon consumption, the reduction material ratio, and the reduction ratio of the reduction material ratio may also be mentioned. The reduction ratio of the reduction material ratio is the reduction ratio relative to the reduction material ratio of the basic operation, and the calculation method is the same as the calculation method of the reduction ratio Input ΔC of the basic unit of carbon consumption.

In addition, Modification 5 and Modification 6 may also be combined. Thereby, the amount of change in pressure loss and the amount of change in furnace top gas temperature can be within a predetermined range, and at the same time, the reduction ratio Input ΔC of the basic unit of carbon consumption can be increased more reliably. [Example]

Next, examples of this embodiment will be described. In this embodiment, by performing a blast furnace operation simulation, it is confirmed that the reduction ratio Input ΔC of the basic unit of carbon consumption is increased by the operation method of the blast furnace of this embodiment, and the CO ₂ emission can be reduced.

<1. Example 1: Verification when the blowing temperature of a gas containing high concentration of hydrogen is from room temperature to 600°C> As described above, the correlation between the amount of hydrogen injected in a gas containing high-concentration hydrogen and the reduction ratio Input ΔC, which is the basic unit of carbon consumption, shows different behaviors based on the injection temperature of 600°C. Therefore, in Example 1, verification was performed when the blowing temperature of a gas containing a high concentration of hydrogen was below 600°C.

＜1-1. Model and calculation conditions for simulation＞ The blast furnace operation simulation system uses the so-called "Blast Furnace Mathematical Model", which is based on Kouji　TAKATANI, Takanobu INADA, Yutaka UJISAWA, "Three-dimensional Dynamic Simulator for Blast Furnace", ISIJ　International, Vol.39(1999), No.1, p The ones shown in .15-22 etc. The mathematical model of the blast furnace, in summary, regulates a plurality of grids (small regions) by dividing the internal area of the blast furnace in the height direction, the radial direction, and the circumferential direction, and simulates the behavior of each grid.

In the blast furnace mathematical model, the amount of gas containing high concentration of hydrogen is set as the amount of gas containing high concentration of hydrogen blown from the tuyere. Among them, the blowing amount of hydrogen in the gas containing high concentration of hydrogen is set as the amount obtained by multiplying the blowing amount of the gas containing high concentration of hydrogen by the hydrogen ratio in unit mol%. The blowing temperature of the high-concentration hydrogen-containing gas is set as the temperature of the high-concentration hydrogen-containing gas when the high-concentration hydrogen-containing gas is blown from the tuyere. The Tf of the temperature in front of the tuyere is calculated as a result of considering the combustion heat of various gases, the sensible heat of the supply air, the coke temperature at the outlet of the tuyere (before the tuyere), and various reaction heats. The pressure loss is calculated as the pressure loss of the filling layer in the furnace using the ergun formula. The top gas temperature is calculated as the gas temperature of the most surface layer (the uppermost layer) of the furnace contents.

The calculation conditions are listed in Table 1. The coke-to-carbon ratio in Table 1 is the amount of coke used per 1 ton of melt milling. In addition, Table 2 lists the essentials of the basic operations that do not blow in gas containing high concentrations of hydrogen. As shown in Tables 1 and 2, in this embodiment, the temperature Tf before the tuyere is set to any one of 2000°C, 2100°C, and 2200°C. In addition, the blowing amount of hydrogen in the gas containing high-concentration hydrogen is set to 0 to 600 Nm ³ /t. In addition, the air flow rate, oxygen increase rate, and PC (pulverized coal) blowing rate are adjusted so that the iron tapping ratio and the melting and milling temperature are fixed in all operations.

[Table 1]

[Table 2]

In addition, all iron-based raw materials were sintered ore. In addition, the composition of the sinter is set to T-Fe: 58.5%, FeO: 7.5%, C/S: 1.9, and Al ₂ O ₃ : 1.7%. In addition, for coke, it is assumed that C: 87.2% and ash content: 12.6% are used. In addition, the above "%" all mean "quality %".

<1-2. Example 1-1: A case where the blowing temperature of the gas containing high concentration of hydrogen is from room temperature to 600°C and the gas containing high concentration of hydrogen is pure hydrogen> In Example 1-1, under the condition that the blowing temperature of the high-concentration hydrogen-containing gas is 600°C or lower, the high-concentration hydrogen-containing gas is set to pure hydrogen, and the amount of pure hydrogen injected and carbon are calculated. Correlation of Input ΔC, which is the reduction ratio of the basic unit of consumption. The results are shown in Figure 2 to Figure 5.

As shown in Figures 2 to 5, it can be seen that when the blowing temperature is above room temperature and below 600°C, the reduction rate of the basic unit of carbon consumption Input ΔC does not simply increase with the increase in the blowing amount. Once increased to a certain degree, it will saturate and then decrease. Moreover, it can be seen that when the reduction ratio Input ΔC of the basic unit of carbon consumption reaches saturation and then decreases, the blow-in amount is slightly different depending on the blow-in temperature. That is, it can be known that there is an appropriate range of the blowing amount for each blowing temperature. In addition, the appropriate range will be 200 to 500 Nm ^{3 /t when the blowing temperature reaches normal temperature to 300°C, and 145 Nm 3} /t or more when the blowing temperature is higher than 300°C and below 600°C. In addition, as shown in Figs. 4 and 5, it can be seen that Input ΔC, the reduction rate of the basic unit of carbon consumption, does not simply increase with the increase in the blow-in volume. When the blow-in temperature is 600°C, the blow-in volume will be 600Nm ³ / When the blow-in temperature is 350°C, the blow-in amount will ^{reach a peak at about 300Nm 3} /t, and the blow-in amount will increase and decrease at the same time. In addition, when the blowing temperature is higher than 300°C and 600°C or lower, and the blowing rate ^{is within the appropriate range of 145Nm 3} /t or more, the reduction rate Input ΔC of the basic unit of carbon consumption can be 7% or more. . Furthermore, as shown in Figures 2 to 5, it can be seen that the reduction rate Input ΔC of the basic unit of carbon consumption for the same blow-in amount varies according to the temperature Tf in front of the tuyere, and it becomes the maximum when the temperature Tf in front of the tuyere is 2000°C. . The reason why the phenomenon can be obtained is as described above.

Therefore, by blowing a high-concentration hydrogen-containing gas into the blast furnace according to the operation method of the blast furnace of the present embodiment, the reduction ratio Input ΔC of the basic unit of carbon consumption can be increased, and CO ₂ emissions can be significantly reduced.

<1-3. Example 1-2> In Example 1-2, it was confirmed that the same operation as in the case of pure hydrogen can be achieved even if the gas containing high-concentration hydrogen contains a gas other than hydrogen. Specifically, it is assumed that the gas containing high concentration of hydrogen is 80 mol% H ₂ -20 mol% N ₂ gas composed of 80 mol% hydrogen and 20 mol% nitrogen. Then, the blowing temperature was set to 25°C and the tuyere front temperature Tf was set to 2100°C, and the blast furnace operation simulation was performed in the same manner as in Example 1. The results are shown in Figure 11. Figure 11 compares the calculation result of pure hydrogen (100mol% H ₂ gas) with the calculation result of _{80mol% H 2} -20mol% N ₂ gas and displays it. In addition, the horizontal axis of Fig. 11 is the value obtained by converting the flow rate of the mixed gas into pure hydrogen, that is, the value obtained by multiplying the flow rate of _{80mol% H 2} -20mol% N _{2 gas by 80mol%.} It is obvious from Fig. 11 that for 80 mol% H ₂ -20 _{mol% N 2} gas, the appropriate range of the injected amount after conversion into pure hydrogen is also the same as in the case of pure hydrogen, but the effect is only slightly reduced. Therefore, it can be seen that even if the gas containing high-concentration hydrogen contains gases other than hydrogen, the same operation as in pure hydrogen can be achieved. And it can be seen that although the effect is slightly reduced, the reduction rate Input ΔC of the basic unit of carbon consumption can still be increased.

<1-4. Example 1-3> In Example 1-3, pure hydrogen gas at room temperature was used as a gas containing high-concentration hydrogen, and the pressure loss changes (relative to The amount of change in pressure loss in basic operations). The results are shown in Figure 12. It is obvious from Fig. 12 that there is a fixed correlation between the amount of pure hydrogen blown in and the amount of change in pressure loss. For example, it can be seen that when the temperature Tf in front of the tuyere is low, the pressure loss may increase relative to the basic operation. However, if the blowing amount of pure hydrogen increases, the pressure loss decreases. More specifically, when the temperature Tf in front of the tuyere reaches 2000°C and the blow-in amount reaches 100 to 150 Nm ³ /t, the pressure loss is increased by about 10 to 20 kPa compared to the basic operation. This is a value outside the above-mentioned predetermined range. However, if the injection volume rises ^{above 200Nm 3} /t, the pressure loss will be the same as or below the value of the basic operation. The reason for this phenomenon is as described above. Therefore, it can be known that the correlation between the blow-in amount and the pressure loss change is calculated in advance according to the temperature Tf in front of each tuyere, and the carbon consumption is determined based on the correlation between the blow-in amount and the carbon consumption parameter and the correlation between the blown amount and the pressure loss change. The amount of hydrogen is blown into a gas containing high-concentration hydrogen that is lower than the current state of work, and the pressure loss changes within a predetermined range. This suppresses the increase in pressure loss and enables stable operations while Increase the reduction ratio Input ΔC of the basic unit of carbon consumption. The aforementioned correlation between the injection volume and the pressure loss change is that when the injection temperature is a predetermined value, the injection volume of hydrogen in a gas containing high concentration of hydrogen is relative to the basic operation The correlation between the change in pressure loss. Further, it was found in normal temperature pure hydrogen as a gas containing a high concentration of hydrogen, and the blowing amount of 200Nm ³ / t or more and at 500Nm ³ / t of the following conditions, as shown in FIG. 12 can suppress the pressure loss is increased , And it is possible to increase the reduction rate Input ΔC of the basic unit of carbon consumption while performing stable operations. And it can be seen that if it is pure hydrogen above normal temperature and below 300°C, once its blowing rate rises to 200Nm ³ /t, the pressure loss will be the same as or below the value of the basic operation. It can also be seen that the increase in pressure loss can be suppressed in the following cases, and the reduction rate of the basic unit of carbon consumption can be increased while performing stable operations. Input ΔC: Blowing of pure hydrogen above 300°C and below 600°C when the amount of 145Nm ³ / t or more, higher than 600 deg.] C or less and in the amount of injection of pure hydrogen was 900 ℃ 125Nm ³ / t or more, the amount of injection higher than 900 deg.] C and below 1200 deg.] C of pure hydrogen When it is 110 Nm ³ /t or more, and when the blowing amount of pure hydrogen above 1200°C is 100 Nm ³ /t or more.

From this, it can be seen that by blowing a gas containing high concentration of hydrogen into the blast furnace according to the blast furnace operation method of this embodiment, the pressure loss can be changed to a value within a predetermined range, and at the same time, the reduction of the basic unit of carbon consumption is increased. Ratio Input ΔC.

<1-5. Example 1-4> In Example 1-4, pure hydrogen gas at room temperature was used as a gas containing high-concentration hydrogen, and the amount of change in the top gas temperature ( The amount of change in the top gas temperature relative to the basic operation). The results are shown in Figure 13. It is obvious from Fig. 13 that there is a fixed correlation between the amount of pure hydrogen blown in and the amount of change in the top gas temperature. For example, if the temperature Tf in front of the tuyere increases, the top gas temperature will be lower than the basic operation. Specifically, when the temperature Tf in front of the tuyere reaches 2100°C and the blow-in amount reaches 250-300 Nm ³ /t, the amount of change in the furnace top gas temperature will be a value outside the above-mentioned predetermined range. However, as long as the blowing rate is reduced to 200Nm ³ /t, the amount of change in the top gas temperature will become a value within a predetermined range. The reason for this phenomenon is as described above. Therefore, when attaching importance to work efficiency, etc., it is only necessary to consider the correlation between the amount of pure hydrogen injected and the amount of change in top gas temperature to adjust the amount of injection. From this, it can be known that the correlation between the blowing amount and the top gas temperature change is calculated in advance according to the temperature in front of each tuyere, and the correlation between the blowing amount and the carbon consumption parameter and the correlation between the blowing amount and the top gas temperature change Determine the amount of hydrogen in the gas containing high-concentration hydrogen in which the carbon consumption is lower than the current operation and the variation of the top gas temperature reaches a value within a predetermined range, thereby suppressing the decrease in the efficiency of the operation.

<2. Example 2: Verification when the blowing temperature of a gas containing high concentration of hydrogen is higher than 600°C> In Example 2, verification was performed when the blowing temperature of a gas containing a high concentration of hydrogen was higher than 600°C.

＜2-1. Model and calculation conditions for simulation＞ The blast furnace operation simulation system uses the same mathematical model of the blast furnace as in Example 1. The calculation conditions are listed in Table 3. As shown in Table 3, the calculation conditions are almost the same as those of Example 1, but the coke ratio is set to conditions different from those of Example 1. That is, in Example 2, the coke ratio is set to be fixed at 300 kg/t when the pulverized coal injection rate is greater than 0 ton/h, and when the pulverized coal injection rate is 0 ton/h (that is, the pulverized coal ratio is 0 o'clock) is set to change. That is, when the injection rate of pulverized coal is 0 ton/h, the furnace temperature is adjusted according to the coke ratio.

As described above, when the blowing temperature of the gas containing high concentration hydrogen is increased and the blowing rate is increased, the blowing rate of pulverized coal can be 0 ton/h. At this time, by reducing the coke-to-carbon ratio, the basic unit of carbon consumption can be further reduced. In addition, the injection amount of hydrogen gas in the gas containing high-concentration hydrogen is set to 0 to 1000 Nm ³ /t. In addition, the blowing temperature of the gas containing high-concentration hydrogen is set to be higher than 600°C and 1400°C or lower. In addition, the essential items of the basic operation of not blowing the gas containing high-concentration hydrogen are the same as in the first embodiment. In addition, other various conditions were set to be the same as in Example 1. For example, adjust the air supply volume, oxygen increase rate and PC (pulverized coal) blowing volume to make the iron tapping ratio and the melting and milling temperature constant in all operations. The iron-based raw material was used as the sintered ore used in Example 1.

[table 3]

<2-2. Example 2-1: The blowing temperature of the gas containing high concentration of hydrogen is higher than 600°C and the case where the gas containing high concentration of hydrogen is pure hydrogen> In Example 2-1, the gas containing high-concentration hydrogen was set to pure hydrogen, and the correlation between the injection amount of pure hydrogen and the reduction ratio Input ΔC of the basic unit of carbon consumption was calculated. The results are shown in Figure 6 to Figure 10.

As shown in Figures 6 to 10, it can be seen that if the injection amount of hydrogen in a gas containing high concentration of hydrogen is ^{gradually increased from 0Nm 3} /t in the basic operation, the reduction ratio Input ΔC of the basic unit of carbon consumption increases. In addition, as the injection volume of hydrogen in a gas containing high concentration of hydrogen increases, the reduction ratio of the basic unit of carbon consumption Input ΔC increase ratio (the reduction ratio of the basic unit of carbon consumption relative to the increase in the injection volume Input Although the increase in ΔC) decreased, the reduction ratio Input ΔC, which is the basic unit of carbon consumption, did not turn into a decrease. This behavior is significantly different from the case where the blowing temperature of a gas containing a high concentration of hydrogen is below 600°C.

In addition, the range for the reduction ratio Input ΔC of the basic unit of carbon consumption to 7% or more depends on the blowing temperature of each gas containing high concentration of hydrogen. Specifically, when the blowing temperature is higher than 600°C and below 900°C, when the blowing amount of hydrogen in a gas containing high concentration of hydrogen reaches a ^{value in the range of 125Nm 3} /t or more, the carbon consumption is basically The unit reduction ratio Input ΔC is more than 7%. In addition, when the blowing temperature is higher than 900°C and below 1200°C, when the amount of hydrogen in the gas containing high-concentration hydrogen reaches a ^{value in the range of 110Nm 3} /t or more, the basic unit of carbon consumption is The reduction ratio Input ΔC reaches more than 7%. When the blowing temperature is higher than 1200℃, and the blowing amount of hydrogen in the gas containing high concentration of hydrogen reaches a ^{value in the range of 100Nm 3} /t or more, the reduction rate of the basic unit of carbon consumption Input ΔC reaches 7% above.

＜2-3. Other tests＞ The blowing temperature of pure hydrogen was set to 900°C, and the same test as in Examples 1-3 and 1-4 was performed. As a result, it can be confirmed that when the blowing temperature of pure hydrogen reaches 900°C, there is also a fixed correlation between the blowing amount of pure hydrogen and the change in pressure loss or the change in furnace top gas temperature.

Therefore, by blowing gas containing high concentration of hydrogen into the blast furnace according to the blast furnace operation method of this embodiment, the amount of change in the top gas temperature can be within a predetermined range, and at the same time increase the reduction in the basic unit of carbon consumption. Ratio Input ΔC.

Above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited by these examples. And obviously, anyone with a general knowledge in the technical field to which the present invention belongs can think about various changes or amendments within the scope of the technical ideas described in the scope of the patent application, and know that these technologies also belong to the present invention. Scope.

1: blast furnace 2: tuyere 3: Air tank 4: Hot air stove 5: heater

Fig. 1 is a diagram for explaining the blowing temperature of a gas containing a high concentration of hydrogen. Figure 2 is a graph showing the correlation between the amount of pure hydrogen blown in at room temperature and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Fig. 3 is a graph showing the correlation between the amount of pure hydrogen blown in at 300°C and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Figure 4 is a graph showing the correlation between the amount of pure hydrogen blown in at 350°C and the reduction ratio Input ΔC of the basic unit of carbon consumption. Fig. 5 is a graph showing the correlation between the amount of pure hydrogen blown in at 600°C and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Fig. 6 is a graph showing the correlation between the amount of pure hydrogen blown in at 650°C and the reduction ratio Input ΔC of the basic unit of carbon consumption. Fig. 7 is a graph showing the correlation between the amount of pure hydrogen blown in at 900°C and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Fig. 8 is a graph showing the correlation between the amount of pure hydrogen blown in at 950°C and the reduction ratio Input ΔC of the basic unit of carbon consumption. Figure 9 is a graph showing the correlation between the amount of pure hydrogen blown in at 1200°C and the reduction ratio Input ΔC of the basic unit of carbon consumption according to the temperature Tf in front of each tuyere. Fig. 10 is a graph showing the correlation between the amount of pure hydrogen blown in at 1250°C and the reduction ratio Input ΔC of the basic unit of carbon consumption. Figure 11 shows the correlation between the amount of pure hydrogen injected at room temperature or the amount of _{hydrogen injected in a gas containing high concentration of hydrogen at 80mol% H 2} -20mol% N ₂ at room temperature and the reduction ratio Input ΔC of the basic unit of carbon consumption Chart. Fig. 12 is a graph showing the correlation between the amount of pure hydrogen blown in at room temperature and the change in pressure loss according to the temperature Tf in front of each tuyere. Figure 13 is a graph showing the correlation between the amount of pure hydrogen blown in at room temperature and the amount of change in furnace top gas temperature according to the temperature Tf in front of each tuyere. Figure 14 is a graph showing the correlation between the amount of pure hydrogen blown in at 1200°C and the change in pressure loss when the temperature Tf before the tuyere is 2100°C. Figure 15 is a graph showing the correlation between the blowing temperature of pure hydrogen and the blowing amount of pure hydrogen. The blowing amount of pure hydrogen is the amount required to make the reduction ratio Input ΔC of the basic unit of carbon consumption 10%. . Figure 16 is a graph showing the correlation between the injection temperature of pure hydrogen and the injection amount of pure hydrogen. The injection amount of pure hydrogen is the amount required to make the reduction ratio Input ΔC of the basic unit of carbon consumption 20%. .

Claims (13)

A method for operating a blast furnace, which is characterized in that a gas with a high concentration of hydrogen containing more than 80 mol% of hydrogen is blown from a tuyere under the following conditions: The blowing temperature of the gas containing high concentration of hydrogen is above normal temperature and below 300°C And the condition that the blowing amount of hydrogen in the aforementioned high-concentration hydrogen-containing gas is 200Nm ³ /t or more and less than 500Nm ³ /t; the aforementioned high-concentration hydrogen-containing gas has a blowing temperature higher than 300°C and 600°C Below, and the condition that the blowing amount of hydrogen in the high-concentration hydrogen-containing gas is 145Nm ³ /t or more; the blowing temperature of the high-concentration hydrogen-containing gas is higher than 600°C and below 900°C, and The blowing rate of the high-concentration hydrogen gas is 125Nm ³ /t or more; the blowing temperature of the aforementioned high-concentration hydrogen-containing gas is higher than 900°C and below 1200°C, and the hydrogen in the aforementioned high-concentration hydrogen gas The blowing rate is 110Nm ³ /t or more; or the blowing temperature of the high-concentration hydrogen-containing gas is higher than 1200℃, and the blowing amount of the hydrogen in the high-concentration hydrogen-containing gas is 100Nm ³ /t The above conditions. The method of operation of a requested item of a blast furnace, wherein the blowing amount and the blowing temperature is below room temperature 300 ℃, and the hydrogen-containing gas of high concentration of hydrogen is 200Nm ³ / t or more and 300Nm ³ / t below. The blast furnace operation method of claim 1, wherein the blowing temperature of the high-concentration hydrogen-containing gas is higher than 300°C and below 600°C, and the blowing amount of the hydrogen in the high-concentration hydrogen-containing gas is 145Nm ³ /t or more and 600Nm ³ /t or less. For the blast furnace operation method of any one of claims 1 to 3, the temperature in front of the tuyere is set to 2050°C or less. For the blast furnace operation method of any one of claims 1 to 3, the temperature in front of the tuyere is set to be higher than 2050°C and lower than 2150°C. Such as the blast furnace operation method of any one of claims 1 to 3, which sets the temperature in front of the tuyere to be higher than 2150°C and lower than 2250°C. The blast furnace operation method of claim 1, wherein the blowing temperature of the aforementioned high-concentration hydrogen-containing gas is higher than 600°C and lower than 1400°C. Such as claim 1 or 7 of the blast furnace operation method, wherein when the blowing temperature of the high-concentration hydrogen-containing gas is higher than 600°C, the blowing amount of the hydrogen in the high-concentration hydrogen-containing gas is set to 1000Nm ³ /t the following. The blast furnace operation method of 7 or 8, in which the blowing temperature of the high-concentration hydrogen-containing gas is higher than 600°C, and the blowing amount of the hydrogen in the high-concentration hydrogen-containing gas is ^{more than 400Nm 3} /t. The temperature in front of the tuyere is set below 2050°C. A method for operating a blast furnace, which is characterized in that the correlation between the blowing amount and the carbon consumption parameter is calculated in advance according to the temperature in front of each tuyere, and the carbon consumption is determined to be lower than the current operation based on the correlation between the blowing amount and the carbon consumption parameter. The blowing amount of the hydrogen gas in the high-concentration hydrogen-containing gas, and blowing the high-concentration hydrogen-containing gas from the tuyere according to the determined blowing amount, The correlation between the injection volume and the carbon consumption parameter is that when the injection temperature of a gas containing high concentration of hydrogen containing more than 80 mol% of hydrogen is a predetermined value, the injection volume of hydrogen in the gas containing high concentration of hydrogen is related to the aforementioned carbon Correlation between consumption and carbon consumption parameters. Such as the operating method of the blast furnace in claim 10, which calculates the correlation between the blowing amount and the carbon consumption parameter according to each blowing temperature. For example, the operating method of the blast furnace in claim 10 or 11, which calculates in advance the correlation between the blowing amount-the pressure loss change amount according to the temperature in front of each tuyere, and according to the correlation between the blowing amount-the carbon consumption parameter and the blowing amount -The correlation of the pressure loss change amount determines the amount of hydrogen blowing in the high-concentration hydrogen-containing gas whose carbon consumption is lower than the current operation and the pressure loss change reaches a value within a predetermined range. The correlation between the amount of injection and the amount of change in pressure loss is the relationship between the amount of hydrogen injected in the gas containing high concentration of hydrogen and the amount of change in the pressure loss relative to the basic operation when the injection temperature is a predetermined value . For example, the operating method of the blast furnace in any one of claims 10 to 12, which calculates the correlation between the blowing amount-the temperature change of the top gas according to the temperature in front of each tuyere, and the correlation is based on the aforementioned blowing amount-the carbon consumption parameter The relationship and the correlation between the amount of blown-in and the amount of change in top gas temperature determine that the amount of carbon consumption is lower than the current operation, and the amount of change in the top gas temperature reaches a value within a predetermined range of hydrogen in the aforementioned high-concentration hydrogen-containing gas The blow-in amount, The correlation between the amount of injection and the amount of change in top gas temperature is the change in the amount of hydrogen in the gas containing high concentration of hydrogen and the temperature of the top gas relative to the basic operation when the injection temperature is a predetermined value. The correlation between the quantity.

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