JPH0610288B2 - Blast furnace operation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a blast furnace operating method capable of significantly changing the blast furnace gas calorie with respect to the amount of pig iron produced.

(Prior Art) A blast furnace, which is a pig iron manufacturing apparatus, is a fuel supply source in a steel mill together with a coke oven, which is a coke manufacturing apparatus used for the blast furnace. In the future, these gases are expected to be used for power generation, external fuel, or chemical raw materials. In order to meet these expectations, it is required that the total calorific value of gas generation (gas amount x calorific value per unit gas amount) can be elastically changed with respect to the pig iron production amount. Since the total gas-generated calorie per ton of pig iron is determined by the fuel ratio per ton of pig-iron, the amount of change in the total gas-generated calorie largely depends on the amount of change in the fuel ratio of the blast furnace. The fuel ratio of the blast furnace is determined by the heat balance in the lower part of the furnace and the progress of gas reduction in the upper part of the furnace. Figure 1 is called the operation diagram of the blast furnace. From X = 1 to the right,
The oxygen balance with the progress of reduction is shown. Point W is
This is a point showing the reduction equilibrium of Fe-FeO at the temperature Tw, and this changes depending on the temperature Tw. From X = 1 to the left,
The heat balance of the lower part of the blast furnace is shown. The slope of the line segment AE is proportional to the coke ratio. Ratio of line segment UR and UW (UR / U
W) is called the shaft efficiency γ, which indicates the utilization efficiency of the reducing gas. Ideally, the point R coincides with the point W when γ = 1. In the actual blast furnace, approximately γ = 0.90 to 0.97
It is in the range of. The ordinate Yd of the point B represents the reaction amount in the reaction (solution loss reaction) between CO ₂ and carbon in the coke generated as a result of the reduction of the iron ore in the furnace. Since this reaction is an endothermic reaction, the solution is If the loss reaction amount Yd is large, the required heat amount in the lower part of the furnace will increase. By the way, the temperature Tw substantially corresponds to the temperature at which the reaction of the coke begins to occur, and when using ordinary coke at present, it is approximately 950-10.
The temperature is 00 ° C.

FIG. 2 shows the theoretical flame temperature Tf at the tuyere of 2000-250.
The change in the coke ratio CR and the solution loss reaction amount Yd when the temperature is changed to 0 ° C is shown. Shaft efficiency γ
Is considered to change depending on the distribution of ore and coke in the blast furnace, but its width is not so large and the coke ratio C
The range of R is considered to be approximately 450 to 550 Kg / T. The range of the total calories of the generated gas is not so wide as shown by the one-dot chain line in FIG. 7, and as a result, the calorie is limited to the range satisfying the required energy amount in the post-process of the steel mill, and there is no room for other uses.

(Technical Problem to be Solved by the Invention) The present invention is capable of significantly changing the total calorie of blast furnace gas for a given amount of pig iron production, so that the blast furnace can effectively use these gases for external applications. The purpose is to provide a method of operation.

(Means for Solving the Technical Problem) This invention blows oxygen and a temperature adjusting gas such as steam from a tuyere, and further blows fuel such as pulverized coal as necessary,
In the method of blowing preheated gas from the shaft, the temperature of the preheated gas is adjusted in the range of 700 to 1300 ° C. to adjust the FeO—Fe reduction equilibrium temperature, and thereby the coke ratio is adjusted to adjust the coke ratio per ton of pig iron. It is a blast furnace operating method characterized by changing the total calorie content of generated gas. When changing the total calorie content of gas generated per ton of pig iron,
Reaction amount Yd of solution loss reaction and fuel ratio (Kg /
T is point A (0.33,710), point B (0.19,510), point C (0.07,540), and D shown in FIG.
It is a blast furnace operating method in which an operation is carried out so as to be within a range surrounded by points (0.11, 790).

(Example) FIG. 3 is a schematic view of a blast furnace operation according to the present invention. In this operating method, ore and coke are loaded into the blast furnace 1 from the furnace top, oxygen 3 from the tuyere 2, pulverized coal and steam or furnace top gas 4 etc. are blown as temperature control gas for the tuyere, and further from the middle stage of the furnace. Blow preheat gas 5 to preheat inserts (ores and coke). As a result, pig iron and slag are produced from the bottom of the furnace, and blast furnace gas is generated from the top of the furnace. After removing dust from this blast furnace gas through the duct collector 7, the gas is circulated to the tuyere and part of it is used in the steel mill. Further, a part of them is treated by the CO ₂ removal treatment device 8 as necessary, and the obtained CO ₂ gas is used as a raw material gas for the synthetic chemical industry.
The CO ₂ gas was obtained by removing CO ₂ processing generator 8,
It is also possible to send it to a combustion furnace or tuyere for generating preheated gas.

In this operating method, in the present invention, the temperature of the preheated gas blown from the shaft is adjusted within the range of 700 to 1300 ° C. By this temperature adjustment, the FeO—Fe reduction equilibrium temperature Tw
Can be adjusted to expand the operable range of the coke ratio or the fuel ratio. A detailed description will be given below with reference to FIG. FIG. 4 shows changes in the solid temperature in the furnace and changes in the reduction rate when the temperature of the preheating gas blown from the interruption of the blast furnace was changed to 650 ° C., 830 ° C., 1000 ° C. and 1200 ° C. From the figure, it can be seen that as the temperature of the preheated gas increases, the temperature rise and reduction of the solid proceed faster. From this figure, the solid temperature T when the FeO composition is reduced (oxidation degree 1.056)
When w is obtained, it becomes as shown in FIG. 5 (a), and it can be seen that Tw changes with the preheating gas temperature. The corresponding equilibrium gas composition is determined on FIG. 5 (b), the lower the preheating gas temperature, the lower the Tw, and the equilibrium gas composition shifts to the CO ₂ or H ₂ O rich side, that is, the oxidizing side. . This is the first
This means that the point W in the figure moves to the right, and even if the shaft efficiency is constant, the gradient of the line segment AE is small, that is, the coke ratio CR is low.

FIG. 6 shows the operating range of the present invention, and the preheating gas temperature is controlled to 700 to 1300 ° C. to realize a wide operating range. In the figure, B → C are the tuyere theoretical flame temperature Tf when the preheating gas temperature = 700 ° C. and the shaft efficiency γ = 0.97.
Shows the case where the temperature is changed from 2500 ° C. to 2000 ° C. A →
D shows the case where the theoretical tuyere flame temperature Tf is changed from 2500 ° C. to 2000 ° C. when the preheated gas temperature = 1300 ° C. and γ = 0.90. Solution loss 0.3 at point A
3, fuel ratio 710, B point is 0.19,510, C point is 0.07,540, and D point is 0.11,790. When the preheated gas is changed from 700 ° C to 1300 ° C in Fig. 5 (a), Tw changes from 700 to 1100 ° C.

FIG. 7 shows the range of change in the total calories generated per ton of pig iron. Since coke is used, it is more rational to add a coke oven gas for comparison in order to evaluate the energy supply from the pig iron production process to the outside. .

(Effect of the Invention) According to the present invention, as is apparent from FIG. 7, the change range of the total calorie content of gas generated from the blast furnace is large. For this reason, there is a remarkable effect that the generated energy can be adjusted significantly as needed from the energy supply level for the inside of the steel mill to the supply of a considerably large amount to the outside without changing the pig iron production amount.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an operation diagram of a blast furnace, FIG. 2 is an explanatory view showing an operation range of a normal blast furnace, FIG. 3 is a schematic view showing an operation method of the present invention, and FIG. Explanatory diagram showing changes in preheating gas temperature, solid temperature in furnace, and reduction rate, FIG. 5 (a) is a diagram showing a relationship between preheating gas temperature and solid temperature, and FIG. 5 (b) is corresponding to solid temperature. It is a phase diagram which shows an equilibrium gas composition. FIG. 6 is a diagram showing the operation range of the present invention, and FIG. 7 is a diagram showing the total calories of gas generated per ton of pig iron in the present invention in comparison with the conventional one. 1 ... blast furnace, 2 ... tuyere, 3 ... oxygen, 4 ... top gas, 5 ... preheating gas, 7 ... dust collector, 8 ... de-CO ₂ processor, 9 ... combustion furnace.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuro Ariyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (56) References JP-A-60-159104 (JP, A)

Claims (2)

[Claims] 1. A method of injecting at least oxygen and a temperature adjusting gas from a tuyere, and injecting a preheated gas from a shaft, wherein the temperature of the preheated gas is adjusted within a range of 700 to 1300 ° C., FeO, Fe. A blast furnace operating method characterized in that the reduction equilibrium temperature is adjusted, and thereby the coke ratio is adjusted to change the total calorie content of gas generated per ton of pig iron. 2. A method of injecting at least oxygen and a temperature adjusting gas from a tuyere and injecting a preheated gas from a shaft by adjusting the temperature of the preheated gas in a range of 700 to 1300 ° C., FeO, Fe. When the reduction equilibrium temperature is adjusted and the coke ratio is adjusted to change the total calorie amount of gas generated per ton of pig iron, the reaction amount Yd of the solution loss reaction and the fuel ratio (Kg / T) are shown in Fig. 6. Point A (0.33,710), Point B (0.19,510), C
The blast furnace operating method according to claim 1, characterized in that the operation is carried out within a range surrounded by a point (0.07,540) and a point D (0.11,790).