JPH02240206A - Tuyere for blast furnace - Google Patents

Abstract

PURPOSE:To prevent the enlargement of hole diameter and the development of chipping and cracking at tip part of a ceramic tube by constituting inside at the tip part over a specific length of the material having the specific content of SiC and the specific porosity and outside of monolithic refractory having Al2O3-SiO2 as essential component and the specific thermal conductivity for the ceramic tube. CONSTITUTION:The ceramic tube 3 is inserted in inside of a tuyere 1 for blast furnace. Then, the inside of 20-200 length at the tip part of ceramic tube 3 is constituted of the material having >=90% SiC content and 3-17% porosity. Further, the outside thereof is constituted of the monolithic refractory having the coating body Al2O3-SiO2 as essential components and <=5kcal/mhr deg.C thermal conductivity. By this method, repair of the tuyere can be unnecessary.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to the improvement of tuyeres for blast furnaces, and more specifically to a tuyere for blast furnaces that can be used for multiple purposes such as energy saving, improved durability, and tuyere adjustment. It is related to.

(Prior art) The tuyere of a blast furnace is heated at a high temperature of 1100°C to 1300°C inside the furnace.
In addition, hot air and fuel such as heavy oil or pulverized coal are blown into the combustion chamber at a high speed of 200 to 230 ei/s. Conventionally, these sidings are made of copper and equipped with a forced water cooling mechanism to protect the tuyere material, but due to the harsh conditions of use, the lifespan is short and the tuyere material is damaged. Since forced water cooling is used for protection, burnout is also very large. For this reason, in recent years, measures have been taken to extend the protective life of the tuyere, to save energy, and to adjust the amount of air injected from the tuyere for the purpose of blast furnace operation.
As shown in the figure, AI is installed inside the tuyere 1a which has a water cooling zone 2a.
A tuyere is used in which a ceramic tube 3a of O, A1, 03-8in, or coprite type is inserted and a mortar set 5a is used, but the usage conditions are as follows: ■ Fuel (heavy oil, The combustion of pulverized coal produces gas and heat, and the chemical erosion caused by molten ash is high.

(2) The temperature inside the tuyere is 1100°C to 1300°C, and a large amount of hot air and fuel such as heavy oil or pulverized coal are blown in at a speed of 200 to 230 g*/s, so wear during hot conditions is extremely large.

■ The inside of the ceramic tube is exposed to high temperatures, but because the back side is in contact with the water-cooled copper tuyere, there is a large temperature gradient.

In addition, the inside of the furnace is affected by (→ The inside point of the furnace is said to be theoretically 2300 degrees Celsius, and the tip receives high-temperature heat from inside the furnace.

(b) Weakness and damage to tissues due to erosion and penetration by slag and alkali caused by iron ore 9 lime, coke, etc.

QS) Effect of CO gas on carbon deposition and structure.

Under conditions such as mechanical, chemical, thermal and resistance to thermal changes must be high.

(Problem to be solved by the invention) As mentioned above, the current ceramic tube is A t x Oj
Because these conditions cannot be satisfied because the products are manufactured using materials such as A1103-8in, A1103-8in, Copelite, etc., and are used by inserting them inside the siding, these conditions cannot be met, and after the start of use, the number of After a few days, an abnormality occurs at the tip, and a turbulent flow of hot air gradually begins, causing damage and causing the temperature of the cooling water in the first wing to rise, resulting in disadvantages such as a drop in temperature and speed of the blowing. As a result, it is currently impossible to maintain effects such as protection of the lining and energy saving, so there is a strong demand for a highly durable tuyere that satisfies these conditions.

(Means for solving the problem) In view of the current situation, the inventor of the present invention sought a material with high resistance to these conditions, and as a result of various researches,
It has been discovered that a refractory material with a SiC content of 90% or more and a porosity of 3% to 17% has high mechanical abrasion resistance, excellent resistance to thermal changes, and is chemically stable. But, S
Since it is a material containing more than 90% iC component, it has a high thermal conductivity of 15 to 30 Kcal/mthr'C, and its insulation effect is lower than that of conventional materials, which reduces the energy saving effect. For improvement, the inside of the 20 mm to 100 mm tip of the ceramic tube to be inserted is made of a material with a SiC content of 90% or more and a porosity of 3% to 17%.

The outer side of the construction body is mainly made of AI, 03-5in, and is made of a monolithic refractory with a thermal conductivity of 5Kcal/hour, 'C or less, which has a conventional high thermal conductivity, resulting in an energy saving effect. By using a silicon carbide material with limited quality of component 9, which was considered to be an unsuitable material due to its low level of energy, we have found a tuyere that is highly durable, protects the tuyere, and has a high energy-saving effect. It is.

If necessary, a layer of a buffer material may be provided between this Al2O, -8in2 system construction body and the SiC ceramic ring material.

(Reason for limitation) As shown in Figure 1 for SiC content of 90% or more, (if the SiC content is 90% or less, the reactivity with slag increases rapidly and the amount of erosion increases. .

X-rotating slag test method Test conditions ■ 1500℃ 430 hours (6 hours x 5 repeated tests) ■ Slag Coal ash ■ For porosity 3% to 17%: 1) Heat-resistant spalling when porosity is within 3% The hardness becomes smaller and the occurrence of chips and cracks increases.

2) When the porosity is 17% or more, the bonding between particles deteriorates, and the penetration of slag into the structure causes the formation of a thick layer and slag adhesion, resulting in increased erosion loss.

■ Thermal conductivity of monolithic refractories as external materials.

This is to make the thermal efficiency more effective in terms of 5 Kcal/m, hr, 'C.

■ Silicon carbide material tip 20IIIl~100III
Regarding the inner layer, if the tip is not in contact with the tuyere, slag etc. may enter.To prevent this, and from the viewpoint of damage and durability, the minimum value is 20cm.

The reason for setting the value to 100 .mu.

That is, the present invention provides a tip 2011Xn of a ceramic tube 3 inserted into a tuyere l having a water cooling zone 2 as shown in FIG.
"100 The inside of the side has a SiC content of 90% or more and a porosity of 3.
% to 17% of the material, and the same outer side is A1. Thermal conductivity is 5 Kcal/m, hr.
A mortar set 5 is composed of monolithic refractories (At, O, -8iO□ type castable) 4 having a grade of C or less.

(Effect of the invention) Next, the effects of this invention will be described with reference to examples.

(Embodiment) The tip 30cm and the inside 8m of the tuyere tube are made of silicon carbide fired material, and the outside except the tip 30cm is Al, O, -5in.

A two-layer method is used, which is castable and castable. Table 1 shows the chemical composition values of the raw materials used in the examples.

Using the above raw materials, (1) A fired material made of two SiC materials with maximum particle diameters of 1.4 m and 0.044011 as the tip and inner layer materials.

(2) The product of the present invention is manufactured using chamots castable as the outer layer (side) material, and the comparative material is a fired product made mainly of synthetic mullite and sintered alumina as a high alumina material for comparison.

The results are shown in Table 2.

As shown in Table 2 of the quality characteristic values of each material used in the above implementation, silicon carbide material has extremely high strength (hot,
room temperature), high thermal conductivity, and good heat spalling resistance as shown by the residual rate of elastic modulus in the spalling test.

It also has excellent properties in erosion tests using coal ash. Also, SiO□-AlIO used for the outer layer part
, the castable system and thermal conductivity are 1.59 cal/m
, hr, 'C, which is low, and can be expected to have a sufficient heat insulating effect.

Next, embodiments will be shown and effects will be described.

Table 3 The results of using two types of the invention products (■ and ■) and a comparative amount ■ as the material of a 3800 m blast furnace by the above-mentioned association of each village showed that at the beginning of use, almost the same effect was obtained, but the comparative amount ■
From the 5th, a turbulent flow of hot air was observed, and the temperature of the waste water gradually increased, and no thermal effect was observed after 40 days of use. However, both of the products of the present invention maintained their initial effects, and after continued use, they were removed and inspected on the 180th day. As a result, the damage to the tip was 1.5 cm and 0.7 m.
.

The hole diameter expanded to 1.7 m and 0.7 m at 60 m from the tip, and good results were obtained with no chips or cracks. In addition, the water-cooled tuyere of the comparative amount (■) required repair before reuse, but the product of the present invention did not require any repair and was able to achieve significant effects.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention for blast furnace lining, in which Figure 1 is a chart showing the relationship between silicon carbide content and slag erosion amount, Figure 2 is a longitudinal cross-sectional view of the set of this invention, FIG. 3 is a longitudinal sectional view of a conventional ceramic tube insertion tuyere. 1.1a...Tuyere, 2,2a...Water cooling zone, 3...
SiC ceramic tube, 3a...High alumina ceramic tube, 4...Unshaped refractory material, 5,5a...Mortar set, 1m 2nd rjA 8th Figure S1 usage ff1 (clear I%)

Claims (1)

[Claims] In a tuyere made by inserting a ceramic tube inside a blast furnace tuyere, the tip of the ceramic tube is 20 mm to 100 m.
The inside of m has a SiC content of 90% or more and a porosity of 3% to 17
A blast furnace tuyere, characterized in that the outer side is made of a monolithic refractory having a thermal conductivity of 5 Kcal/m, hr, °C or less and a construction body mainly composed of Al_2O_3-SiO_2.