JPH01191723A - Iron bath type smelting reduction furnace - Google Patents

Abstract

PURPOSE:To effectively cool a furnace wall, to facilitate the repairs and to improve the durability of a total furnace by constructing the furnace wall in order of forced cooling layers, a refractory lining layer from a shell side to the furnace side part excluding the furnace bottom part of an iron bath type smelting reduction furnace 9. CONSTITUTION:Oxidation and reduction are executed in an iron bath composed of an iron bath part 8 and a slug part 9, and a secondary combustion is made in the space 10 above the bath to obtain molten iron. In this iron bath type smelting reduction furnace, the furnace wall is constructed in order of the refractory lining layer 5, forced cooling layers 2, 3, 4 from the side of the furnace shell 1 on the furnace side part excluding the furnace bottom part 6 provided with bottom blowing tuyeres. Accordingly, the iron bath 8, the slug bath 9, the combustion part, etc., do not come into direct contact with the forced cooling layers 2.... As a result, the forced cooling layers 2...are protected and the furnace wall is prevented from failure due to the thermal strain of the furnace wall to facilitate the repairs.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an iron bath type smelting reduction furnace for producing hot metal by smelting reduction.

(Prior technology) In an iron bath type smelting reduction furnace, raw materials such as iron magnets, coal, and lime are introduced through the tuyere provided at the bottom or side of the furnace, or from the top of the furnace, and oxygen is blown into them to form iron magnets. This is a reactor that produces hot metal through melting and reduction. Inside this furnace, there is a steel tower layer at the bottom, a slag layer in the middle, and a secondary combustion exhaust gas layer in the upper space.Furthermore, because it requires continuous operation for a long time, the reduction furnace Furnace walls are subjected to severe thermal loads, and large wall-resistant materials are easily damaged. Furthermore, there is little hope that the refractories will be repaired during operation, and it is necessary to interrupt the operation of the furnace in order to carry out repairs. Therefore, in order to improve the operating efficiency of the furnace, a lining structure that can withstand long life as well as cooling of the refractory wall is desired.

As a lining structure for a reactor used under the above conditions, there is a technique disclosed in, for example, Japanese Patent Application Laid-open No. 123697/1983.

(Problems to be Solved by the Invention) However, the above technology has the following problems.

(b) The iron bath section has a cooling furnace wall installed only in a part of the structure, and this is not a plank-like solution to suppressing damage to the entire furnace wall of the iron bath section.

(b) Since the cooling block is exposed to the operating surface inside the furnace, it is easily damaged by direct damage from slag and hot metal scattering, and in the type where the furnace is tilted to tap iron,
Damage is likely to be greater due to immersion in slag and metal.

(A) The temperature difference between the temperature inside the furnace and the cooling block is extremely large, so there is a high possibility that the cooling block will suffer fatigue damage due to thermal stress.

(d) A repair method is proposed in which only the damaged cooling block is replaced, but the cost of the cooling block increases the cost.

The present invention has been made in view of the above-mentioned problems, and provides an iron bath type melting reduction furnace having a refractory lining structure that effectively cools the furnace wall and facilitates repairs.

(Means for Solving the Problems) The present invention provides an iron bath type smelting reduction furnace in which iron oxide is reduced in an iron bath and secondary combustion is performed in the upper part of the bath surface to obtain hot metal, which is equipped with a bottom blowing tuyere. This is an iron bath type smelting reduction furnace characterized in that the furnace wall is constructed in the order of a forced cooling layer and a refractory lining layer from the iron shell side on the furnace side excluding the furnace bottom.

The forced cooling layer applied in the present invention includes (a) a cast and forged block with a cooling pipe buried therein, (b) a refractory block with a cooling pipe buried therein, and (viii) a cooling layer fixed to the iron skin by means such as direct welding. Water, steam, or inert gas can be used as the cooling medium. In addition, the cooling intensity is cal/r for the iron bath part 20X 10' to 60X 103.
n”Hr.

Slag bath part 25x 103~70x 103Kcal
/rn”Hr.

Bath upper part 30X 103~80x 103Kcal/m'
Hr.

It is sufficient to add some ability.

The materials for the refractory lining layer include magnesia, magnesia/alumina/carbon, magnesia/chromia, magnesia/carbon, alumina/silicon carbide/carbon, and carbon, which have sufficient heat resistance against hot metal, etc. The material is selected depending on conditions such as slag composition and temperature. As for the composition of the lining, it is desirable to have an S/)-layer structure that does not have joints that can easily cause disturbances in the heat transfer resistance characteristics, but if the conditions for controlling the heat transfer resistance characteristics at the joints are in place, a structure with two or more layers can be used. Good too.

[For production]

With the above configuration, the forced cooling layer is protected without the slag bath and iron bath coming into direct contact with the forced cooling layer, and the sudden temperature gradient between the inside and outside of the furnace through the furnace wall, and the Refractory lining layer, forced cooling layer,
Fatigue damage due to heat distortion of the steel shell can be avoided, and the furnace wall can be easily repaired, increasing the durability of the entire furnace.

〔Example〕

Figure 1 is a schematic side sectional view showing an example of an iron bath type smelting reduction furnace. 1 is a furnace body shell, and the furnace side has an iron bath part, a slag bath part, and a bath part inside the shell from the bottom. upper respective forced cooling layers 2;
3.4 is attached, and a refractory lining layer 5 is further provided on its inner surface to form the furnace wall. In addition, 6 is a refractory layer equipped with a bottom blowing tuyere (not shown) at the bottom of the furnace, and 7 is a lance for top blowing. During operation, the molten iron section 8, slag bath section 9, and secondary combustion are carried out from the bottom. A bath upper part 10 is formed.

FIG. 2 is a sectional view showing an example of a furnace wall structure, in which a cast or forged or refractory block 12 with a cooling pipe 11 buried therein is used as a forced cooling layer 2.3°4 attached to the inner surface of the steel shell 1. , for example, carbon joint material 1 with good thermal conductivity.
3 shows the structure pushed in.

As a construction example, a cast and forged block with cooling piping embedded as a forced cooling layer is used, and the cooling strength of each part is 240 x 103 Kcal/m'Hr in the iron bath part, 350 x 103 Kcal/m'Hr in the slag bath part.

Cal/rn") Ir in the upper part of the bath 460xlO3.

As a result of using water as the cooling medium and constructing the furnace wall as the refractory lining layer 5, the furnace wall was not damaged and the forced cooling layer operated normally, resulting in long-term operation. We were able to operate stably for a long time.

FIG. 3 is a graph showing the relationship between the heat load on the furnace wall and the temperature inside the furnace. In this graph, the straight line 21 is the heat load when the cooling piping of the forced cooling layer is exposed during operation, and the straight line 22 is the The heat load when the forced cooling layer is damaged, straight lines 23 and 24 are the heat loads when the forced cooling layer and the refractory lining layer are healthy, respectively, A, B,
The sections indicated by C indicate the cooling intensities implemented in the present invention in the iron bath section, slag bath section, and upper bath section, respectively.

Therefore, if the operation is carried out within the cooling intensity range of straight lines 22 and 23, the refractory lining layer will require some repair, but the forced cooling layer will always maintain its integrity, ensuring stable operation and durability of the furnace body. be able to.

(Effects of the Invention) As explained above, in the present invention, since the furnace wall is constructed by forming the forced cooling layer and the refractory lining layer in order from the steel shell side, the forced cooling layer is not directly exposed to the high temperature of the bath. Not,
In addition, since there is no sudden temperature gradient between the inside and outside of the furnace wall, fatigue damage due to thermal distortion of the furnace wall is prevented, increasing the durability of the entire furnace. Repairing only the layers is sufficient, reducing costs and ensuring stable operation.

[Brief explanation of the drawing]

Figure 1 is a schematic side cross-sectional view showing an example of an iron bath type smelting reduction furnace, Figure 2 is a cross-sectional view showing an example of the furnace wall structure, and Figure 3 shows the relationship between the temperature inside the furnace and the thermal load that the furnace wall receives. This is a graph showing. 1... Furnace shell, 2, 3.4... Forced cooling layer, 5.
... Refractory lining layer, 8... Iron bath part, 9... Slag bath part, 10... Bath upper part, 11... Cooling piping, 1
2...Forged or refractory block, 13...Joint. Agent: Patent attorney Masamitsu Akizawa and 1 other person, 1 illustration

Claims (1)

[Claims] In an iron bath-type smelting reduction furnace where iron oxide is reduced in an iron bath and secondary combustion is performed above the bath surface to obtain hot metal, the furnace side is forced from the shell side to the side of the furnace except for the bottom part equipped with bottom blowing tuyeres. An iron bath type melting reduction furnace characterized by having a furnace wall constructed in the order of a cooling layer and a refractory lining layer.