JPS61143507A - Lance for accelerating secondary combustion of converter - Google Patents

Abstract

PURPOSE:To provide a titled lance which prevents the clogging and erosion of a nozzle and burns positively the gaseous CO generated in a furnace by providing plural pieces of nozzles which consist of the non-circular aperture having a large ratio between the long diametral axis and short diametral axis and have the same shape. CONSTITUTION:At least >=2 nozzles 2 which consist of the non-circular aperture such as elliptical shape having >=1.2 ratio between the long diametral axis and short diametral axis and have mutually the same shape are provided in the top blowing lance 1 for accelerating the secondary combustion of the converter which blows oxygen into the converter to burn secondarily the gaseous CO generated in a decarburization stage and to substitute the auxialiry energy. The outside surface area of the oxygen jets are thus formed large and the jets are interfered with each other to include much of the atmosphere gas contg. the above-mentioned gaseous co, by which the combustion of the gaseous CO is advantageously conducted and the clogging and erosion of the above- mentioned nozzle 2 by the bottom blowing gas are effectively prevented.

Description

[Detailed description of the invention] (Field of industrial application) The cost of steel produced by the converter steel manufacturing method strongly depends on the price of the pig iron and iron scrap charged into the furnace, and the price of iron scrap is It is advantageous to increase the charging ratio of iron scrap when the price of steel is lower than that of steel, but there is a shortage of heat sources necessary for steelmaking. Furthermore, even when desiliconized hot metal or dephosphorized hot metal is refined in a converter, depending on the type of steel, the heat source in the converter may still be insufficient and the desired blow-off temperature may not be obtained.

Furthermore, in converter refining with the aim of increasing blow-off (Cr), (Mnl) by melting and reducing chromium ore, manganese ore, etc. in the converter, depending on the amount of these ores added, In some cases, the amount of heat may be insufficient.

In the case of a lack of heat in this way, conventionally, solid substances with a strong affinity for oxygen (e.g. PeSi + coke) or auxiliary energy such as fuel oil, fuel gas, or even plasma are added to the converter. This example uses thermal compensation.

However, adding auxiliary energy from outside,
Naturally, the cost increases and the benefits of special blowing in the converter are lost.

(Prior Art) Japanese Patent Application Laid-Open No. 57-131313 discloses at least one main opening for blowing a gas jet with a strong impact, and a main jet that opens in an umbrella shape around the gas jet. Oxidizing the CO released from the hot metal bath with refining oxygen using an oxygen blast lance with two types of openings, with at least one sub-opening for gas stream blasting with a significantly lower impact. Regarding the increase in the secondary combustion rate, it is disclosed that the durability of the lance nose is improved.

When used in a top-bottom blowing converter using a launch knob with a slit-shaped nozzle for a gas flow with a very weak impact, the splash generated by the strong bottom-blown gas is caused by the slit-shaped nozzle. It may enter and cause nozzle clogging, or it may melt the cu part in the nozzle and cause water leakage.

(Problem to be solved by the invention) CO gas generated during the decarburization process of the converter is actively
This makes it possible to effectively replace the above-mentioned auxiliary energy by secondary combustion without worrying about nozzle clogging or nozzle melting, which was a concern with conventional technology, when secondary combustion increases the amount of heat generated in the furnace. This is the object of the invention.

(Means for Solving the Problems) The present invention provides a converter comprising at least two nozzles having the same shape and each having a non-circular opening having a ratio of the major axis to the minor axis of 1.2 or more. This is a lance for promoting secondary combustion.

Inside the converter 2 of CO gas generated during decarburization in converter blowing
Promoting the next combustion is important from the standpoint of increasing the amount of heat generated in the furnace. However, when a normal top blowing lance is used, there are certain limits to secondary combustion. In order to increase secondary combustion, a jet with the following characteristics is desirable.

■Large surface area outside the jet.

■Buffer the jets mutually and increase the turbulence of the jets;
Increase the amount of atmospheric gas involved.

In order to provide the above-mentioned jet characteristics, the present invention has a top-blowing lance nozzle with a non-circular cross-section, and preferably its arrangement. In other words, the outer surface area of the jet is increased by forming a nozzle with a non-circular cross section, and it is necessary to set the ratio of the major axis to the minor axis of the non-circular nozzle to be 1.2 or more. Note that if this length/breadth axis ratio is less than 1.2, the difference from the circular nozzle will be small, which will cause mutual interference between the jets, which is not compatible with the initial purpose, and reduce CO in the furnace.
As shown in Fig. 1, an example of nozzle arrangement that advantageously leads to combustion of CO gas by increasing the amount of gas entrained, in the case of a twin-hole nozzle, the short diameter of each nozzle 2 is aligned on the diameter line of the lance 1, or In addition, when there are three holes, the major axis of each nozzle 2 is aligned on the radius line dividing the cross section of the lance 1 into three equal parts, or the minor axis of at least one of them is aligned, and the minor axis of at least one of the four holes is In this case, the major axis of each nozzle 2 should be aligned on the orthogonal diameter of nozzle 1, or -
As for the diameter, various embodiments may be adopted, such as making the short axis the same.

(Example) According to the present invention, a lance tip with an 8-hole nozzle shown in FIG. 2 was manufactured as a prototype, and 250 was applied to a top-bottom blowing converter. In this example, each nozzle 2 has a major axis of 40+u+ and a minor axis of 25 m5, so the major axis ratio is 1.6, and the adjacent nozzles are oriented so that the major axis and minor axis are aligned alternately with respect to the radius line of the lance 1. The layout was as follows. This arrangement promotes mutual interference of oxygen jets from adjacent lance holes, which has a favorable effect on CO gas combustion.

In order to compare the effect with this lance tip, it was compared with a commonly used φ44-12°-4 hole (Laval nozzle).

The longitudinal cross-section of the nozzle of the lance tip is the same as the cross-section A-A in FIG. 2, and the nozzle length E is 150-.

As is clear from Figure 3, which shows the relationship between the CO1 concentration in the furnace gas and the lance height, when the lance tip according to the present invention is used, compared to when using a normal lance tip,
The COt gas concentration in the furnace increased by 10 to 20%, and the amount of secondary combustion increased. In addition, the relationship between the amount of iron ore used as a cold material during converter blowing and the lance height was compared with that when using a normal lance tip, and the lance tip of the present invention is shown in Fig. 4. It can be seen that by using , it is possible to increase the amount of coolant input, and a large amount of heat can be supplied.

Incidentally, experiments were conducted using various nozzle arrangements shown in FIG. 1, and it was confirmed that an effect of increasing CO combustion similar to that described in the example could be obtained. Further, the non-circular shape of the nozzle 2 may be an oval narrow rectangle with chamfered corners.

(Effect of the invention) According to this invention, CO generated in the refining reaction of the converter can be
It can be effectively used for secondary combustion and used as a heat source required in the refining process.

[Brief explanation of the drawing]

Fig. 1 is an end view of the lance showing an example of the nozzle arrangement of the lance, Fig. 2 is an end view of the lance in an example, and Figs. 3 and 4 show the Cot gas concentration in the furnace depending on the lance height. This is a comparison chart of the increase in iron ore input and the increase in iron ore input. 1... Lance 2... Nozzle Figure 1 Figure 2 A-ADIlln Lance height Lance height

Claims (1)

[Claims] 1. A lance for promoting secondary combustion in a converter, comprising a non-circular opening with a ratio of the major axis to the minor axis of 1.2 or more, and having at least two or more nozzles of the same shape.