JPS6360215A - Method for blowing raw material into smelting reduction furnace - Google Patents

Abstract

PURPOSE:To operate a smelting reduction furnace under stable condition and to efficiently execute carburization by using a tuyere having triplex cylindrical structure, blowing fine powdery carbonic material from center and oxygen from the outer side of the center, and flowing protecting gas from the most outside. CONSTITUTION:The tuyere for the smelting reduction furnace is composed of triplex cylindrical structure. The fine powdery coal is blown together with carrier gas from a first flowing passage A in the inner cylinder 11, the oxygen is flowed from a second flowing passage B in the intermediate cylinder 21 and the tuyere protecting gas is flowed from a third flowing passage C of the outer cylinder 31. As the fine powdery coal is blown from the first flowing passage A having large section, even if the quantity is large, the wear of the inner cylinder 11 is little. And, as flowing of fine powdery coal is enclosed by the oxygen gas, the carbonic material is perfectly burnt and there is no clogging caused by soot. Further, as the protecting gas is flowed from the third flowing passage C, the metal depositted at the tip of tuyere is slight and the cause of clogging is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for injecting raw materials into a melting reduction furnace.

[Prior Art] Conventionally, there are various types of tuyere structures for blowing carbonaceous material into molten iron in an immersed state. In other words, it has a single-tube structure, in which pulverized coal is blown in together with a carrier gas, and it has a double-tube structure, in which pulverized coal is blown into the inner tube together with a carrier gas, and protective gas is blown through the gap between the inner tube and the outer tube. There are things to include. However, with these structures, there was a problem that the tuyere tip became clogged. Although it has a double-tube structure, a coin system is known in which oxygen flows through the inner tube 1 and pulverized coal is injected together with a carrier gas through the gap between the inner tube 1 and the outer tube 2, as shown in Figure 7. ing.

[Problem to be solved by the invention] However, this coin system also has the following problems.

■Since pulverized coal is injected through a narrow gap, it may become clogged by the generated soot.

(2) The control range of the supply amount of pulverized coal is narrow, at most about 1:3.

■As the outer periphery of the tuyere is cooled by the flow of pulverized coal, metal tends to cool and accumulate at the tip of the tuyere, forming a so-called pine mushroom shown at 3 in Figure 7, making it difficult to control its shape. .

(2) When recarburizing molten iron, it is desired to inject a large amount of pulverized coal, but as the flow rate increases, the tuyere wear increases and the tuyere must be replaced immediately.

The object of the present invention is to provide a raw material injection method that can solve the above-mentioned problems.

[Means and operations for solving the problem] This invention uses a triple-tube structure tuyere in a melting reduction furnace, injects pulverized carbonaceous material from the center of the tuyere, and injects oxygen from the outside. In this method, the tuyere protective gas is flowed outside the tuyere.

The tuyere used in the method of this invention has a first channel provided in the center for blowing pulverized coal into it, and a second channel provided surrounding this first channel for blowing oxygen gas into it. It has a triple-tube structure consisting of a third flow path surrounding the second flow path and through which the tuyere protective gas flows.

In this way, a large amount of pulverized coal can be blown into the first flow path with no restrictions on cross-sectional area. Also, since this flow of pulverized coal is surrounded by sufficient oxygen gas from the second flow path,
Charcoal wood burns completely, so no soot is generated and it does not become clogged. Furthermore, since the protective gas is blown in from the third flow path, it is unlikely that metal will accumulate at the tip of the tuyere and form an excessively large pine mushroom, unlike in the conventional case.

[Example] An example of the tuyere used in the present invention will be explained with reference to FIGS. 1 and 2. An intermediate cylinder 21 is provided outside the inner cylinder 11 that forms the first flow path A, and a second flow path B is formed.

An outer cylinder 31 is provided on the outside thereof, and a third flow path C is formed. Then, pulverized coal is blown in together with carrier gas through the first flow path A, oxygen gas is flowed through the second flow path B, and tuyere protective gas is flowed through the third flow path C. As a protective gas, hydrocarbon gas such as propane, Ar, N2, C01
Uses CO2, recovered gas, etc. In this case, since the pulverized coal is blown into the first flow path A having a large cross-sectional area, the wear of the inner cylinder 11 is small even when the amount of pulverized coal is large. Furthermore, since the flow of pulverized coal is surrounded by oxygen gas from the second flow path B, the carbonaceous material is completely combusted, so there is no possibility of soot being generated and causing clogging. Furthermore, since the protective gas is flowed through the 30th channel C, the amount of metal deposited at the tip of the tuyere is extremely small, as shown in FIG. 3, and does not cause clogging.

Next, another embodiment will be explained with reference to FIG. This is the first
Unlike the embodiment, an inner cylinder 12, an intermediate cylinder 22, and an outer cylinder 32
Each cross section is rectangular. In this case as well, the same effects as in the first embodiment can be obtained, and the jet flow from the tuyere is more stable than in the case of the round ring shown in FIG. This modification is shown in FIG. This has bent portions formed in the multi-cylinders 13, 23 and 33 having rectangular cross sections.

Still another embodiment will be described with reference to FIG. This is an intermediate cylinder 24 having a bent portion by connecting thin tubes 14 that serve as a flow path B for oxygen gas in an airtight manner. The inside of this intermediate cylinder 24 becomes the first flow path A. and intermediate cylinder 2
4 and the outer cylinder 33 forms a 30th flow path C.

Next, the following table shows the effects and effects when the method of the present invention is applied to an actual furnace in comparison with the conventional method.

Compared to the conventional method, nozzle clogging due to pine mushroom formation is eliminated. Furthermore, compared to the conventional method, the control range of carbon material injection can be greatly increased, and carburization can be carried out efficiently.

[Effects of the Invention] The present invention is as described above, and can operate in a stable state without causing nozzle clogging in a melting reduction furnace. Further, recarburization can be carried out efficiently.

[Brief explanation of drawings]

1 and 2 are longitudinal and cross sectional views showing one embodiment of the tuyere used in the method of the present invention, FIG.
5 and 5 are cross-sectional views of other embodiments and modifications thereof, and FIG.
The figure is a sectional view of another embodiment, and FIG. 7 is an explanatory view showing a conventional tuyere in use. A...First flow path B...Second flow path C...Third
flow path

Claims (1)

[Claims] 1) When directly producing hot metal or molten steel by adding iron ore, carbonaceous material, solvent material, and oxygen to a molten iron bath, a tuyere with a triple tube structure is used, and the pulverized carbonaceous material is added to the tuyere. A method for injecting raw materials into a melting reduction furnace, which is characterized by blowing in from the center, blowing oxygen from the outside, and then flowing a tuyere protective gas to the outside. 2) A method for injecting raw materials into a smelting reduction furnace according to claim 1, in which pure oxygen sufficient to completely burn the volatile content in the pulverized coal injected from the center of the tuyere is flowed from the outside thereof. .