JPH02240207A - Tuyere for blast furnace - Google Patents

Abstract

PURPOSE:To prevent the development of chipping and cracking of a ceramic tube by forming tip part having the specific length and inside of the ceramic tube of the ceramic material having the specific content of SiC and the specific porosity, arranging supporting part on outer surface and having constitution having gap between a tuyere except the above part. CONSTITUTION:The ceramic tube 3 is inserted in the inside of tuyere 1. The tip part having 20-100mm length and inside layer of the ceramic tube 3 are constituted of the ceramic material having the quality characteristic value of >=90% SiC content and 3-17% porosity. On the other outer surface, if necessary, on the optional position with the optional mold, the reinforcement and the supporting part of ceramic tube are arranged. The gap 4 is arranged between the tuyere except the above part. By this method, the tuyere having necessity of repairing can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a blast furnace tuyere that can be used for multiple purposes, such as energy saving, improved durability, and tuyere adjustment.

(Prior art) The tuyere of a blast furnace is heated at a high temperature of 1100°C to 1300°C inside the furnace.
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 m/s. Traditionally, these tuyeres have been made of copper and equipped with a forced water cooling mechanism to protect the tuyere material, but due to these harsh operating conditions, the lifespan of the tuyeres has been shortened and the tuyere has Because forced water cooling is used to protect the mouthpiece, burnout can be very large. For this reason, recently water cooling zone 2a has been installed as shown in Figure 3 as a measure to protect the tuyere, extend its life, save energy, and adjust the amount of air injected from the tuyere for the operation of the blast furnace. Al inside the tuyere 1a with
l0. System, A t20. - A tuyere in which a ceramic tube 3a of Sio2 type or coprite type is inserted and a mortar set 5a is used, but the conditions of use are as follows: ■ The combustion of fuel (heavy oil, pulverized coal) in the tuyere and high degree of chemical erosion due to heat and molten ash.

(2) The inside of the tuyere has a temperature of 1,100°C to 1,300°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 m/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 tuyeres, there is a large temperature gradient.

In addition, the influence from inside the furnace is as follows: (Theoretically, the in-furnace scorching point is said to be 2300°C, and the tip receives high-temperature heat from inside the furnace.

(b) Iron ore 1. Tissue cell weakening and damage due to erosion and penetration by slag and alkali caused by lime, coke, etc.

Q%) 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 tubes are made of Al2o3 system, A
1. Since it is manufactured from materials such as O, -8in, Copelite, etc. and inserted into the inside of a tuyere for use, these conditions cannot be satisfied, and after the start of use, several After a few days, an abnormality occurs at the tip, and turbulent flow of hot air gradually begins, causing damage and increasing the temperature of the cooling water in one tuyere. bring. For this reason, it is currently not possible to maintain the effects of tuyere protection and energy saving, so there is a strong demand for highly durable tuyeres that meet these conditions.

(Means for solving the problem) In view of the current situation, the inventor of the present invention searched for a material with high resistance to these conditions, and as a result of repeated research,
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
Because it is a material containing more than 90% of iC ingredients,
Thermal conductivity is 15-30 Kcal/m, hr *”
C, and the insulation effect is lower than that of conventional materials, so the energy saving effect is small. To improve this defect, the tip of the inserted ceramic tube should be 201 to 100 cm, and the inner layer should have a SiC content of 90% or more and a porosity of 3% to I7%.
material, and if necessary, provide reinforcement and support for the ceramic tube at any location using any type of material.

Other than that, by making it an air barrier, we have adopted a silicon carbide material with limited quality, which was previously considered to be an inappropriate material due to its high conductivity and low energy saving efficiency.It is highly durable. We have discovered a tuyere that can protect the tuyere and has a high energy-saving effect.

(Reasons for limitation) (A) Regarding the SiC content of 90% or more, as shown in Figure 1, when the SiC content becomes 90% or less, the reactivity with slag increases rapidly and the amount of erosion increases. be.

* Dramatic slag test method test conditions, ■1500℃, 430 hours (6 hours x 5 repeated tests) ■Slag coal ash (B) Regarding porosity 3% to 17% 1) Porosity is within 3% The heat spalling resistance decreases and chips and cracks occur more frequently.

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 altered layer, slag adhesion, and increases erosion loss.

(C) Regarding the tip 2001 to 100m of the silicon carbide material and the inner layer, if the tip is not in contact with the tuyere, slag etc. may infiltrate.To prevent this, and from the viewpoint of damage and durability, the minimum value is 201. do. Moreover, the reason for setting it to Loomm was decided because it is better to use less highly thermally conductive material in order to increase thermal efficiency.

That is, in this invention, as shown in FIG.
00m and the inner layer has a SiC content of 90% or more and a porosity of 3.
% to 17% of the quality characteristic value, and if necessary, provide reinforcement and a support part for the ceramic tube 3 at any location using an arbitrary type if necessary, and otherwise connect it to the metal tuyere 1. This is a mortar set 5 with a structure having an air gap 4 between them.

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

Embodiment: The tip 30 om and the inner 8 cm of the tuyere tube are made of silicon carbide 1. The outside except for the tip 30 mm is made of a silicon carbide ceramic layer as shown in FIGS. 4 and 5 as required. The structure has an air barrier between the tuyere and the tuyere, except for the reinforcement and support parts provided on the outside of the tuyere.

Table 1 shows the chemical composition values of the raw materials used in the examples.

Using the raw material of Clothing 1 above, ■ SiC material for the tip and inner layer material with a maximum particle size of 1.4.
Fired products made of two materials, m and Q, and Q44m are used. In use, there is a space between the tip 100m and the water-cooled tuyere except for the ceramic tube support.

■ Comparison amount is synthetic mullite as a high alumina material.

Create and compare fired products made mainly of sintered alumina material.

The results are shown in Table 2.

As shown in the quality characteristic values shown in Table 2, silicon carbide material has extremely high strength and high thermal conductivity, and has high heat spalling resistance as shown in the residual rate of elastic modulus, and also has high resistance to body slag erosion. It also has excellent sexual characteristics.

Table 2 of quality characteristic values of each material used in the above examples
As shown in the above, silicon carbide materials have extremely high strength (both hot and room temperature) and high thermal conductivity, and their heat spalling resistance is also shown in the residual rate of elastic modulus in the spalling test. It shows good value.

It also has excellent properties in erosion tests using coal ash. Also, Sin is used for the outer layer.

- Al2O2 based castable and thermal conductivity of 1.59K
It has low cal/m, hr, and 'C, and can be expected to have a sufficient heat insulating effect.

Next, the drawings 4 and 5 show the invention product 1 and the invention product 2.
FIG. 6 shows a conventional product. In the figure, 6 is a ceramic tube external reinforcement part, 7 is a ceramic tube support part, and 8 is a tip main body part.

Table 3 Inventive product ■■-2 by combining the above materials and aspects
The results of using seeds and comparative amount ■ as blast furnace tuyeres at 3800 rn' show that both had almost the same effect at the beginning of use, but with comparative amount ■, turbulence of hot air was observed from the 68th point onwards.
A gradual rise in wastewater temperature was observed, and no thermal effect was observed after 43 days of use. Both of the two types of products of the present invention were able to connect the initial effects, and even though they were removed and inspected on the 90th day, the results showed that the melting damage at the tip was 1.6 BIl and 0.8 mi.
The hole diameter expanded to 1.9 m at 60 Wm from the tip, showing good results with no chips or cracks.

Note that the water-cooled metal tuyere of Comparative Volume (1) required repair in order to reuse the tuyere, but the product of the present invention did not require repair at all and was able to achieve great effects.

[Brief explanation of drawings]

The drawings show an embodiment of the blast furnace tuyere according to the invention, in which Fig. 1 is a chart showing the relationship between silicon carbide content and slag erosion amount, and Fig. 2 is a longitudinal cross-sectional view of the set product of the invention. , FIG. 3 is a vertical cross-sectional view of a conventional ceramic tube insertion tuyere, FIG. 4 is a perspective view of an embodiment of the invention product 1, and FIG. 5 is a perspective view of the invention product 2.
FIG. 6 is a perspective view of a conventional product. 1.1a...Tuyere, 2,2...Water cooling zone, 3...S
iC ceramics tube, 3a... High alumina ceramics tube, 4... Air barrier, 5, 5a... Mortar set, 6... Ceramics tube external reinforcement part, 7... Ceramics tube support part, 8 ...Tip body part, Fig. 4

Claims (1)

[Claims] In a tuyere made by inserting a ceramic tube inside the tuyere, the tip of the ceramic tube is 20 mm to 100 mm, and the inner layer has a SiC content of 90% or more and a porosity of 3% to 17%.
The other outer surface is made of ceramic material with quality characteristic values, and if necessary, reinforcement and support for the ceramic tube are provided in any place using any type, and otherwise there is an air barrier between it and the metal tuyere. A blast furnace tuyere characterized by a structure.