JP3023912B2 - Tuyere for blast furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a tuyere for a blast furnace, and more particularly to a tuyere for a blast furnace which can be used for various purposes such as energy saving, improvement of durability and adjustment of the tuyere. It is about.

(Prior art) The tuyere of a blast furnace has a high temperature of 1100 ° C to 1300 ° C,
At a high speed of 0 to 230 m / s, hot air and fuel such as heavy oil or pulverized coal are blown and burned. This tuyere has conventionally been made of copper, and a tuyere equipped with a forced water cooling / cooling mechanism has been used to protect the tuyere material. Heat loss is very large because forced water cooling is used to protect the mouthpiece. For this reason, recently, water-cooled zones as shown in Fig. 3 have been used as measures to extend the life span of tuyere protection, to save energy, and to adjust the amount of air blown from the tuyere during operation of the blast furnace.
A ₂ O ₃ type, A ₂ O ₃ —SiO ₂ type or cordierite type ceramic tube 3 a is inserted inside a tuyere 1 a having a 2 a and a mortar set 5 a tuyere is used. The condition is that the combustion of fuel (heavy oil, pulverized coal) in the tuyere results in high gas and heat and high chemical erosion due to molten ash.

The temperature inside the tuyere is between 1100 ° C and 1300 ° C, and the wind speed is 20
A large amount of hot air and fuel such as heavy oil and pulverized coal are blown in at a speed of 0 to 230 m / s, so that hot wear is extremely large.

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

In addition, the influences in the furnace are as follows: (a) The in-furnace (show) point is theoretically said to be 2300 ° C, and the tip receives high-temperature heat from the furnace.

(B) Weakness and damage of the structure due to erosion and penetration by slag and alkali generated by iron ore, coal, coke, etc.

(C) The effect of CO gas on carbon deposition and organization.

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

(Problems to be Solved by the Invention) As described above, current ceramic pipes are A ₂ O ₃ type, A ₂ O ₃
Manufactured from materials such as O ₃ -SiO ₂ and cordierite,
These conditions cannot be satisfied because the tuyere is inserted immediately inside and used for use.
In a few days, abnormalities occur at the tip, turbulence of hot air gradually starts, damage progresses, the temperature of the cooling water at the tuyere rises, and the accompanying blowing causes a drop in temperature and speed, which is disadvantageous Bring. For this reason, at present, effects such as protection of the tuyere and energy saving cannot be sustained, and a highly durable tuyere that satisfies these conditions is strongly demanded.

(Means for Solving the Problems) In view of such a situation, the present inventor has sought a material having high resistance to these various conditions, and as a result of various studies, as a result, it has been found that the SiC content is 90% or more and the pore is It has been found that refractory materials with a rate of 3% to 17% have high mechanical wear resistance, are excellent in heat change and heat resistance, and are chemically stable.
Since the material contains 90% or more of the components, the thermal conductivity is as high as 15 to 30 Kcal / m, hr ° C, and the heat insulation effect is lower than that of the conventional material. at the tip 20mm~100mm and the inner layer portion of the porosity of 3% to 17% in SiC content of 90% or more material of the ceramic tube to be inserted to the outer layer portion excluding the front end portion a ₂ O ₃ -S
Constructed mainly of iO ₂ and made of an amorphous refractory with a thermal conductivity of 5 Kcal / m, hr, ° C or lower. By using a silicon carbide material with limited components and quality, a tuyere having high durability, protection of the tuyere, and high energy saving effect has been found.

If necessary, a layer made of a buffer material may be provided between the A ₂ O ₃ —SiO ₂ -based construction body and the SiC-based ceramic ring material.

(Reason for limitation) Regarding the content of SiC of 90% or more When the content of SiC becomes 90% or less as shown in FIG. 1, the reactivity with slag rapidly increases and the amount of erosion increases.

* Rotating slag test method Test conditions: 1500 ° C, 430 hours (6 hours x 5 repetitions) Slag Coal ash For porosity of 3% to 17% 1) Heat resistance spalling is small if the porosity is 3% or less. And the occurrence of cracks increases.

2) When the climatic coefficient is 17% or more, the connectivity between particles deteriorates, and a slag penetrates into the tissue to form a thick layer and adhere to the slag, resulting in increased erosion.

 Thermal conductivity of the refractory of the external member.

 This is to make the thermal efficiency more effective at 5Kcal / m, hr, ℃.

If the tip is not in contact with the tuyere, the tip of the silicon carbide material 20mm to 100mm and the inner layer will have slag and other intrusions.To prevent this, set the minimum to 20mm from the point of damage and durability. . The reason why the thickness is set to 100 mm is determined because it is better to reduce the number of the high thermal conductive materials in order to enhance the thermal efficiency.

That is, according to the present invention, as shown in FIG. 2, the front end portion of the ceramic tube 3 inserted into the tuyere 1 having the water cooling zone 2 is 20 mm to 100 m in length.
m and the inner layer are made of a material with a SiC content of 90% or more and a porosity of 3% to 17%, and the outer layer excluding the tip is a construction body mainly composed of A ₂ O ₃ —SiO ₂ with a thermal conductivity of 5 Kcal / m. The mortar set 5 is composed of an amorphous refractory (A ₂ O ₃ —SiO ₂ castable) 4 having a temperature of, hr, ° C or less.

(Effects of the Invention) Next, effects of the present invention will be described with reference to examples.

(Embodiment) The tip portion 30 mm and the inner layer portion 8 mm of the tuyere tube are cast with a silicon carbide-based fired material, and the outer layer portion excluding the tip portion 30 mm is castable mainly using an A ₂ O ₃ —SiO ₂ system. And Chemical components of raw materials used in Examples The values are shown in Table 1.

Using the above raw materials, (1) SiC material with a maximum particle size of 1.4 mm as the tip and inner layer material
And two fired materials of 0.044mm.

(2) A product of the present invention is manufactured using a chamotte castable as an outer layer (side) material, and a fired product is produced and compared with a comparative material mainly composed of synthetic mullite and fired alumina as a high alumina material.

 Table 2 shows the results.

Table 2 of quality characteristic values of each material to be used in the above implementation
As shown in FIG. 2, the silicon carbide-based material has extremely high strength (both hot and room temperature), high thermal conductivity, and heat resistance spalling property is also shown by the residual modulus of elasticity by a spalling test. Shows good values.

It also has very good properties in erosion tests with coal ash. The castable of SiO ₂ -A ₂ O ₃ system used in the outer layer portion thermal conductivity of 1.59Kcal / m, hr, ℃ and low,
A sufficient heat insulating effect can be expected.

Next, effects will be described by showing embodiments.

The results of using the above two products of the present invention and the comparative product as the tuyere of a 3800 m ³ blast furnace by the combination of the above materials had almost the same effect at the start of use, but the comparative product was effective from day 5 Turbulence of the hot air was observed, and the temperature of the wastewater gradually increased, and no thermal effect was observed after 40 days of use. However, both of the products of the present invention maintain their initial effects, continue to be used, and are removed and inspected on the 180th day. As a result, good results were obtained with no damage at the tip, 1.5 mm and 0.7 mm, and a hole diameter expansion of 1.7 mm and 0.7 mm at 60 mm from the tip, with no cracks. The water-cooled tuyere of the comparative product had to be repaired for reuse, but the product of the present invention did not need to be repaired at all, and a great effect could be achieved.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the tuyere for a blast furnace of the present invention. FIG. 1 is a table showing the relationship between the silicon carbide content and the slag erosion amount, and FIG. , Third
The figure is a longitudinal sectional view of a conventional ceramic tube insertion tuyere. 1,1a tuyere, 2,2a ... water-cooled zone, 3 ... SiC ceramic tube, 3a ... high alumina ceramic tube, 4 ... irregular refractory material, 5,5a ... mortar set, 6 ... … Tip of ceramic tube

Claims (1)

(57) [Claims] 1. A tuyere comprising a ceramic tube inserted inside a tuyere for a blast furnace, wherein the tip of the ceramic tube has a length of 20 mm or more.
100mm and inner layer 90% or more SiC content, porosity 3% ~ 17
%, And the outer layer excluding the tip is composed of a refractory with a thermal conductivity of 5 Kcal / m, hr, ° C or less in a construction body mainly composed of A ₂ O ₃ —SiO _2. Tuyere for blast furnace.