JP2000178629A - Coolant to inner wall in converter and cooling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the exhaust gas temperature in a converter while keeping a secondary combustion ratio high by mixing petroleum hydrocarbon, water and surfactant in emulsion state. SOLUTION: Relating to a coolant which is sprayed onto the inner wall in the converter for refining charged material while giving the charged material, the secondary combustion heat of the generating gas in the furnace, the coolant for the inner wall in the converter is composed of the mixture of the petroleum hydrocarbon, water and surfactant in the emulsion state. The mixing ratio of the petroleum hydrocarbon and the water is made to 3:7-7:3 by weight. The coolant is blown into the converter through a top-blown lance. In this cooling method of the inner wall in the converter, the inner wall in the converter is a magnesia-quality brick containing the carbon. Since the coolant uniformly mixed in the emulsion state is blown, the reaction interface area is drastically increased in comparison with the blowing of solid carbonaceous powder and the reforming of gas is efficiently executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling method and a cooling method for an inner wall of a converter, and more particularly, to a method for lining a furnace wall by local high temperature caused by secondary combustion of gas generated in the converter. This is a technique to prevent damaged refractories.

[0002]

2. Description of the Related Art For the purpose of improving the melting capacity of scrap in a converter and increasing the amount of ore reduction, it has been conventional to secondarily burn gas generated in a converter to apply heat to the melt. Is being done. This is called the secondary combustion method, in which a special upper blowing lance is provided in the converter, and CO gas generated in the converter is burned by an oxygen gas jet blown through the converter, and the combustion heat is converted into molten metal. This is a technique that is very effective in that heat is reused and that the [S] concentration in molten steel is not increased. However, since this secondary combustion utilizes an exothermic reaction in the gas phase of CO + 1 / 2O ₂ → CO _2, if the secondary combustion ratio defined by CO ₂ / (CO + CO ₂ ) is to be increased, the exhaust gas temperature Will be very high and will significantly damage the refractory lining at the top of the converter. Also, in this secondary combustion method, C
Since O is reduced and CO ₂ is increased, the calories of the exhaust gas are reduced, which causes a problem in the reuse of the exhaust gas.

[0003] In order to solve these problems,
Coal powder, coke powder, etc. into the converter through a blowing lance
By blowing the powder, the temperature of the exhaust gas is lowered and the inner wall of the converter is resistant.
A method for reducing the damage rate of fire is known (Japanese Unexamined Patent Application Publication No.
See JP-A-64-79313). In addition, Japanese Unexamined Patent Publication No.
No. 067708 discloses that CO2 is blown from an upper blowing lance or a furnace wall. _Two
N_Two, Hydrocarbon containing fluid, powdered carbonaceous material, water mist and water
A technique for cooling the inner wall refractory by spraying one or more types of steam.
We suggest technique. The inner wall of the converter is usually
Shear-carbon refractory bricks must be lined
Many.

[0004]

However, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 64-79313, the method of blowing coal powder and coke powder into a converter through an upper blowing lance is not known. Although the temperature of the exhaust gas is lowered and the erosion rate of the refractory on the inner wall is reduced, there are the following problems.

[0005] First, the reforming efficiency of exhaust gas is low, that is, all the carbon content of the injected carbonaceous material powder is Sol.
A part of the reaction was not trapped in the exhaust gas without being reacted, but was recovered as dust collection powder, without causing a reaction of loss loss (CO ₂ + C → 2CO). Conversely, if the blown carbon material powder is reduced and the supply speed of the blown carbon material powder is reduced, the required effect of lowering the exhaust gas temperature cannot be obtained. Therefore, in the above method, an increase in the amount of carbon-based dust generated was unavoidable. Further, since the carbonaceous powder itself is expensive, there is a problem that the cost for cooling is high.

On the other hand, in the method described in Japanese Patent Application Laid-Open No. 61-067708, since water mist or steam is used, decarburization occurs on the surface of the brick on the inner wall, and the durability of the brick is reduced. There was a problem.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a coolant and a method for cooling the inner wall of a converter capable of lowering the temperature of exhaust gas in a converter (particularly, a throttle section) while maintaining a high secondary combustion ratio. The purpose is to propose.

[0008]

Means for Solving the Problems The inventor of the present invention has conducted intensive studies to achieve the above object, found a suitable coolant for the inner wall of the converter, and used the same to lower the atmospheric temperature in the furnace and to use the inner coolant. The refractory is cooled to reduce its wear.

That is, the present invention relates to a coolant which is applied to the inner wall of a converter for scouring the charge while imparting the secondary combustion heat of the gas produced in the furnace to the charge, and is a petroleum hydrocarbon. , Water and a surfactant in an emulsion state.

[0010] The present invention is also a coolant for the inner wall of a converter, wherein the mixing ratio of the petroleum hydrocarbon and water is 3: 7 to 7: 3 by weight.

Further, the present invention provides a method for cooling the inner wall of a converter for refining the charge while applying the secondary combustion heat of the gas generated in the furnace to the charge. A method for cooling the inner wall of a converter, characterized by blowing into a converter via a blowing lance.

[0012] In addition, the present invention is also a method for cooling a converter inner wall, wherein the inner wall of the converter is a magnesia brick containing carbon.

In the present invention, a coolant in which petroleum hydrocarbons, water, and a surfactant are uniformly mixed in an emulsion state is blown into the converter through an upper blowing lance. Since the reaction interface area is dramatically increased compared to the injection of solid carbonaceous powder, gas reforming can be performed efficiently, and all the injected coolant contributes to the reforming reaction. Equipment (equipment for treating exhaust gas with water)
The temperature of the exhaust gas can be reduced without any adverse effect on the operation of the exhaust gas. That is, the heat load on the inner wall of the upper part of the converter can be reduced, and the wear of the refractory on the inner wall can be suppressed.

[0014]

Embodiments of the present invention will be described below.

First, the coolant on the inner wall of the converter according to the present invention is:
Mainly petroleum hydrocarbons. As a result, the following (1)
This is because the heat of decomposition of the reaction of the formula can be used, and a small amount of tar (residual carbon) contained in petroleum can form a protective film against heat on the furnace wall. As a result, a reaction between magnesia and carbon at high temperature (formula (2) below) is prevented from occurring, and deterioration (weight reduction) which is a problem peculiar to carbon-containing magnesia bricks can be prevented.

The coolant for the inner wall of the converter according to the present invention is:
Make petroleum hydrocarbons as inexpensive as possible, plus use water. As a result, not only the cost required for cooling the inner wall can be reduced, but also the endothermic reaction of water (4) can be expected in addition to the endothermic reaction of the following equation (3). As the equation proceeds, an endothermic reaction by the reaction of equation (5) can be expected.

(—CH ₂ —) n → nC + nH ₂ O (1) MgO (solid) + C (solid) → CO (g) + Mg (g) (2) C + CO ₂ → 2CO (3) C + H ₂ O → H ₂ + CO (4) CO ₂ + H ₂ → H ₂ O + CO (5) However, a simple mixture of petroleum hydrocarbon and water separates, and does not become a uniform coolant. Therefore, in order to blow into a converter, a lance provided with two pipes, a pipe for petroleum hydrocarbons and a pipe for water, is prepared and mixed at the outlet.

The inventor has worked diligently to eliminate this inconvenience, and has found that the addition of a surfactant can make the lance structure simple if the three are in an emulsion state. Surfactants used at this time include those commonly used, such as an aqueous solution of dodecyl benzene sulfonic acid amine salt, polyoxyethylene alkyl ether, and polyoxyalkylene alkyl ether. Is enough.

The amount of the surfactant is not particularly limited as long as the petroleum hydrocarbon can be sufficiently dispersed in water. It is preferable that the content be about 0.1 to 10.0% by weight.
If the amount is less than 0.1% by weight, the emulsification may be insufficient when the amount of the petroleum hydrocarbon is large, and if it exceeds 10.0% by weight, the cost increases.

In addition, in the present invention, it is preferable to mix petroleum hydrocarbons and water in a weight ratio of 3: 7 to 7: 3. When the content of water in the emulsion is 70% by weight or more, decarburization occurs from the carbon-containing magnesia brick according to the above formula (4), and the durability of the brick decreases. On the other hand, if the water content is less than 30% by weight, the effect of the endothermic reaction according to the formula (4) is small, and the effect as a coolant cannot be sufficiently obtained. Therefore, in the above mixing range, C used in the formula (4) is generated by decomposing at a higher temperature than hydrocarbons (for example, heavy oil), and C deposited on the surface of the refractory is used preferentially. Therefore, the refractory does not deteriorate and the life is not shortened. The method for cooling the inner wall of the converter according to the present invention using such a coolant will be specifically described in the following examples.

[0021]

FIG. 1 shows a structure of a converter to which a cooling method according to the present invention is applied. In FIG. 1, 1 is a converter, 2 is a bottom blowing nozzle, 3 is a molten iron, 4 is a molten slag generated on the surface of the molten metal 3, 5 is an upper blowing lance, and 6 is an injection from the tip of the upper blowing lance 5. The oxygen gas jet 7 is a coolant according to the present invention which is jetted from the outer peripheral portion of the upper blowing lance 5. FIG. 2 is an enlarged sectional view of the upper blowing lance 5 used for performing the cooling method according to the present invention. The upper blowing lance 5 is provided with an outer peripheral wall of a water-cooled structure, an oxygen line 10 and an oxygen nozzle 11, similarly to those conventionally used. However, in the present invention, in addition to these functions, a coolant supply line 12 is separately provided so as to be included in the coolant outlet line 9, and a coolant ejection nozzle 13 is attached to the tip of the coolant supply line 12. I have to.

Converter refining was performed using the upper-blowing converter 1 (capacity 150 tons) shown in FIG. 90 tons of hot metal (temperature: 1220 ° C.), which had been desiliconized and dephosphorized in advance, was transported by a topped car (not shown), and charged into the converter 1 into which 70 tons of scrap had been previously charged. In the converter 1, an upper blowing lance 5 is provided such that the tip height is 4.2 m from the stationary molten steel surface, and the height of the coolant jet nozzle 13 is 5.7 m from the stationary molten steel surface. ing. In the converter 1, the top blown oxygen amount is 550 Nm ³ / min, and the bottom blown oxygen amount is 50 Nm ³ / mi.
n, oxygen blowing was performed on the charge under the conditions of the bottom blown nitrogen amount of 20 Nm ³ / min. Until the temperature of the hot metal reaches 1550 ° C., 1.25 kg / N
Supplied in a ratio of m ³ —O ₂ .

Further, in this embodiment, the upper lance 5
, A coolant 7 was blown during oxygen blowing, but a heavy oil A was selected as a petroleum hydrocarbon, a surfactant was added to the coolant 7, and a 1: 1 ratio by weight with water was added. Emulsified one was used by mixing uniformly (Example of the present invention).
The supply rate of the coolant 7 is 30 kg / min, and the amount of the surfactant is 1.5 kg / min.

In order to determine the effect of the present invention,
When the coolant 7 is not used at all (Comparative Example 1), when the coke breeze is jetted as the coolant 7 at a supply speed of 115 kg / min (Comparative Example 2), when only water as the coolant 7 is used (Comparative Example 1) Example 3) In the case of using only heavy oil A as the coolant 7 (Comparative Example 4), oxygen blowing was also performed.
In this case, the conditions other than the coolant 7 are all the same as in the case where the coolant 7 according to the present invention is used.

The results of such oxygen blowing were evaluated by examining the temperature of the exhaust gas, the heat-up ability, and the amount of carbon-based dust generated. Table 1 shows the survey results.

[0026]

[Table 1]

From Table 1, it can be seen that the present invention and Comparative Examples 2, 3, and 4
It is apparent that when the coolant 7 is jetted through the upper blowing lance 5 as described above, the temperature of the exhaust gas can be reduced while maintaining the heat-up ability. This effect of the temperature drop is not observed in Comparative Example 1 in which the coolant 7 is not used at all. However, it is also clear that the temperature lowering effects of Comparative Examples 2, 3, and 4 are smaller than those of the present invention. Further, in Comparative Example 2 using coke breeze, the amount of generated dust and the cooling cost are larger than those of the present invention and Comparative Examples 1, 3, and 4.

Further, in order to confirm the above effects, the inventor separately performed a heat treatment at 1600 ° C. × 2 hours for the carbon-containing magnesia brick in a CO atmosphere in a laboratory.
At that time, the above-mentioned various coolants 7 were also sprayed on the brick surface to simulate the oxygen blowing. That is, for the example of the present invention, 1.5 hours out of the holding time at 1600 ° C.
An emulsion mixed at a weight ratio of heavy oil: water = 1: 1 is mixed with 5
g / min, Comparative Example 1 was sprayed with no coolant 7, Comparative Example 3 was sprayed with water at 5 g / min, and Comparative Example 4 was sprayed with heavy oil A at 5 g / min. Then, the brick after the heat treatment was cut, and the presence or absence of a decarburized layer was observed. The results are shown in Table 2.

[0029]

[Table 2]

As shown in Table 2, in the case of Comparative Example 3, decarburization occurred on the surface of the brick recovered after the experiment. However, in the present invention and Comparative Examples 1, 2, and 4, decarburized layers were observed. Did not.

In the above embodiment, the upper lance 5
Although the one in which the supply line 12 of the coolant 7 is included in the cooling water outlet side line 9 was used, if the structure of the upper blowing lance 5 allows it, it may be installed in the cooling water inlet side line 8. No problem. Further, the present invention relates to these upper lances 5.
The invention is not limited thereto, and a dedicated lance for blowing only the coolant 7 may be used.

[0032]

As described above, according to the present invention, a coolant made into an emulsion by uniformly mixing petroleum hydrocarbons, water and a surfactant in a converter through an upper blowing lance. To prevent refractory damage to the inner wall of the converter due to high-temperature exhaust gas due to the heat of secondary combustion of the produced gas, decrease in CO concentration in exhaust gas, and decrease in calorie of exhaust gas due to increase in CO ₂ concentration. Can be solved.

[Brief description of the drawings]

FIG. 1 is a diagram showing the structure of a converter for implementing a cooling method according to the present invention.

FIG. 2 is an enlarged sectional view of an upper blowing lance 5 used for performing a cooling method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Converter 2 Bottom blow nozzle 3 Molten metal (or hot metal) 4 Molten slag 5 Top blow lance 6 Oxygen gas jet 7 Coolant 8 Coolant inlet line 9 Coolant outlet line 10 Oxygen line 11 Oxygen nozzle 12 Coolant line 13 Coolant ejection nozzle 14 Refractory

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Sadako Kiyota 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Inside the Technical Research Institute of Kawasaki Steel Corporation (72) Inventor Masato Kumagai 1, Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba (72) Inventor Hiroyasu Morioka 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Corporation Chiba Works F-term (reference) 4K002 AA01 AC05 BB03 BF04

Claims (4)

[Claims] Claims: 1. A coolant sprayed on an inner wall of a converter for refining a charge while imparting secondary combustion heat of a gas generated in the furnace to the charge, the refrigerant being a petroleum hydrocarbon, water and And a surfactant in an emulsion state. 2. The cooling agent according to claim 1, wherein the mixing ratio of the petroleum hydrocarbon and water is 3: 7 to 7: 3 by weight. 3. The method according to claim 1, wherein the cooling agent according to claim 1 or 2 is used for cooling the inner wall of a converter for refining the charge while applying the secondary combustion heat of the gas generated in the furnace to the charge. A method for cooling an inner wall of a converter, wherein the inner wall of the converter is blown into the converter via an upper blowing lance. 4. The method according to claim 3, wherein the inner wall of the converter is a magnesia brick containing carbon.