JPS62164813A - Converter lance - Google Patents

Abstract

PURPOSE:To make thorough secondary combustion of gaseous CO generated during decarburization by positioning an oxygen nozzle provided to the top end of a lance near to the base part of an inside pipe, providing an outdoor suction pipe to the outside of the nozzle and opening the lance through a gas restricting part. CONSTITUTION:The gaseous oxygen conducted to the converter lance 1 arrives at the oxygen nozzle 6 and passes the gaseous oxygen restricting part 6a at a sound velocity. The gaseous oxygen expands in a nozzle expanding part 6b and is ejected at the supersonic velocity from the nozzle 6. The gaseous oxygen is mixed with the in-furnace gas which is essentially composed of the gaseous CO sucked from the outdoor air suction pipe 7 and passes the gaseous mixture restricting part 5a. The velocity energy is converted to pressure energy during this time to develop the pressure higher than the pressure in the suction stage by which the gaseous CO and the gaseous oxygen are thoroughly mixed and are substantially burned when both gases are ejected from an aperture 5b. The efficiency of converter blowing is improved by using such lance 1 and the saving of energy is attained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a method of sufficiently burning CO gas generated during decarburization in converter blowing to convert it into CO2, thereby increasing the heat level inside the converter. This invention relates to a converter lance that enables economical converter blowing.

[Conventional technology]

In a converter, free oxygen blown in from a converter lance (hereinafter referred to simply as a lance) is brought into contact with a large amount of CO gas generated from molten metal in the furnace during blowing to promote secondary combustion in the furnace. The heat of combustion is transferred to the molten metal to raise the temperature of the molten metal, and the ratio of cold material (for example, scrap steel or ferroalloy of a known brand) to the molten metal in the furnace is increased to increase the processing capacity (T/H). ) Steelmaking technology with high thermal efficiency is being developed. The key point of this technology is how to properly bring the free oxygen blown in from the lance into contact with the molten steel (CO gas generated from the interface between the molten steel and the molten metal) to cause sufficient secondary combustion between the lances. Improvements to lance nozzles were developed as such technology, for example, in Japanese Patent Application Laid-open No. 5
This method has been proposed in No. 3-102205 and Japanese Unexamined Patent Publication No. 17711.8/1986. The former relates to a dual lance nozzle that has a secondary nozzle installed on the side of the main nozzle of the top-blowing lance to blow out oxygen for secondary combustion, while the latter has a configuration in which the shape of the secondary nozzle is configured so that oxygen can easily spread horizontally. It is something.

[Problem that the invention seeks to solve]

However, with the conventional improved lance nozzle as described above, it is difficult to combust COO gas sufficiently in a converter due to its combustion characteristics. The reason is as follows.

■ In the converter, the COO gas concentration is almost 100%, C
It is an inert region for O combustion (the combustion range of a mixed gas of CO and oxygen is 15.5 to 94% in COO gas degree)
(2) The COO gas flame propagation speed is 0.3 to 0.4 m/sec, which is very small compared to the CO gas upward rise rate of 3 to 5 msec generated during blowing.

Therefore, even if secondary combustion oxygen is injected from the top blowing lance, it can burn in most of the inside of the converter, and in reality, it burns almost all the way to the furnace mouth.

This can be seen from the fact that when the lance is pulled up immediately after blowing has stopped, the oxygen jet that is still ejected due to the residual pressure inside the lance forms a flame near the furnace throat. In this way, with conventional improved lances, secondary combustion occurs only near the furnace mouth, so there was a problem in that it was almost impossible to transfer the combustion heat to the molten metal and raise the temperature of the molten metal. .

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems of the prior art and to develop a converter lance that performs secondary combustion not far from the molten steel in the furnace. The present invention was completed by determining that the problem can be solved by adopting a structure that closes the problem.

That is, the present invention provides a converter lance having a structure in which a cooling water channel is formed outside the oxygen flow channel, in which the oxygen nozzle provided at the tip of the oxygen flow channel is located closer to the base than the lance tip within the innermost tube forming the cooling water channel. A plurality of outside air suction pipes are located on the side and pass through the cooling waterway near the oxygen nozzle to communicate the space inside the innermost pipe outside the oxygen nozzle with the outside of the lance. The present invention relates to a converter lance characterized in that the innermost tube forms an opening that expands outward through a mixed gas throttle section.

[Explanation of configuration]

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a sectional view showing the main parts of one embodiment of the present invention.

FIG. 2 is an end view taken along the line A-A in FIG. 1, and FIG. 3 is a cross-sectional explanatory view transparently showing the state inside the furnace body during steelmaking using the converter lance according to the present invention. .

In the drawing, reference numeral 1 denotes a converter lance, which has an oxygen flow path 2 at its core and a cooling water column path 3 and a cooling water return path 4 formed in sequence on the outside as a cooling water path, which is similar to a conventional converter lance. is the same as The innermost tube 5 of the triple tubes forming the cooling waterway also forms an oxygen flow path 2 from the lance base 1a side inside thereof, and oxygen and cooling water are respectively flowed in the directions of the arrows. The oxygen flow path 2 has an oxygen nozzle 6 at the tip,
Unlike the conventional converter lance where the oxygen nozzle 6 is formed at the tip of the lance by the innermost tube 5, the oxygen nozzle 6 is located at the lance base Ia rather than at the lance tip 1b in the innermost tube 5.
It is installed separately on the side.

As shown in FIG. 1, this oxygen nozzle 6 has an oxygen gas throttle part 6a and a nozzle widening part 6a from the upstream side, and this nozzle widening part 6b opens into the innermost tube 5. In the vicinity of the oxygen nozzle 6, as shown in FIGS. 1 and 2, there are preferably a plurality of holes that penetrate the cooling waterway and communicate the inner space of the innermost tube 5 outside the oxygen nozzle 6 with the outside of the converter lance 1. is provided with three or more (four in the illustrated example) outer suction pipes 7. The cooling water column path 3 and the cooling water return path 4 are connected at the lance tip, and the innermost pipe 5 is connected to the lance tip 1b.
As shown in FIG. 1, an opening 5b is formed that extends outward from the upstream side to the downstream side via the mixed gas throttle section 5a. In addition, 8 is the main body of the converter.

9 is molten steel in the converter main body 8, 10 is a furnace mouth hood, and 11 is a bottom blowing tuyere.

[Action and effect]

When blowing using the converter lance 1 according to the present invention, the following functions and effects are exhibited. The oxygen gas led to the converter lance 1 reaches the oxygen nozzle 6 through the oxygen flow path 2, passes through the oxygen gas constriction part 6a at sonic speed, and in the nozzle widening part 6b, the oxygen gas expands and becomes supersonic, and becomes oxygen. It is ejected from nozzle 6. This supersonic oxygen gas flows into the molten steel 9 inside the converter main body 8.
C sucked in from the outside air intake pipe 7 located directly above the
The mixed gas is mixed with the furnace gas mainly composed of O gas and
While passing through the opening 5, velocity energy is converted to pressure energy, and the pressure becomes higher than the suction pressure.
When ejected from b, the CO gas and oxygen gas are almost completely mixed and are sufficiently combusted. The operation of the converter lance 1 in the converter main body 8 will be explained in more detail with reference to FIG. Molten metal such as blast furnace hot metal or hot metal obtained by melting auxiliary raw materials is supplied into the converter body 8, and the converter lance 1 according to the present invention is charged from above, and oxygen gas is introduced into the converter lance 1. Initially, oxygen gas is blown onto the surface of the molten metal, that is, the molten steel 9, and reacts with carbon in the molten steel 9 to generate CO gas. In this way, a large amount of C
When O gas starts to be generated, a large amount of CO gas is sucked in through the outside air suction pipe 7 of the converter lance 1, and acts as described above to create a mixed gas of the furnace gas, mainly CO gas, and oxygen gas. burns near the opening 5b at the tip of the converter lance 1,
The generated CO□ gas and surplus oxygen gas are blown onto the molten steel 9 as shown in FIG. 3 while forming a flame. At this time, the excess oxygen gas reacts with carbon in the molten steel 9 as described above to generate CO gas, and a part of it is sucked in from the outside air suction pipe 7 of the converter lance 1 and burned near the opening 5a. This is repeated below. CO generated in this way
2 gas and a portion of the CO gas that was not drawn into the converter lance 1 is discharged from the furnace mouth hood lO. Although the converter main body 8 shown in FIG. 3 is provided with a bottom blowing tuyere 11 for stirring the molten steel 9, the bottom blowing tuyere 11 is not necessarily required.

By the action of the converter lance 1 as described above, it is possible to sufficiently perform secondary combustion of the CO gas generated during decarburization, and the flame is transmitted from the tip of the converter lance 1 to the molten steel 9.
The combustion heat is extremely effectively transferred to the molten steel 9, increasing the heat level in the converter, increasing the input ratio of removed material, which is an auxiliary raw material, and increasing the converter's processing capacity (T/ H
) and can improve energy savings.

[Reference example]

Next, the converter lance 1 according to the present invention (dimensions: outer diameter 230 m,
Amount of heat generated and increased amount of material removed when making steel by supplying 50 tons of molten steel 9 into the converter body 8 using a converter with a length of 14,600 nn, an innermost tube inner diameter of 85 g+, an outside air suction tube inner diameter of 50 mm, and 4 pieces) An example will be explained in detail.

Feed 1!2 quantity 600ONm'/hour rj revision converter lance l
When the oxygen is ejected from the oxygen nozzle 6, 200ONm37 hours of furnace gas, mainly CO gas, is sucked in from the outside air suction pipe 7. do). This suction amount varies depending on the cross-sectional area ratio of the oxygen gas constriction section 6a of the oxygen nozzle 6 and the mixed gas constriction section 5a of the innermost pipe 5 and the oxygen supply pressure.
In this example, the above inhalation amount is used for calculation.

This inhaled CO gas causes an exothermic reaction with oxygen near the opening 5b as follows.

co+q○2→CO7+3oooKc4',,3-c.

In the above equation, since CO gas is inhaled at 200ONm3/hour, 1 of the oxygen supply f&600ONm'/hour
100ON'/hour is consumed. Assuming that 80% of the above calorific value is transferred to the molten steel during 15 minutes of blowing, the amount of heat supplied by secondary combustion is:

3000Kca%, -X 2000 N% x 15
Sword 0 minutes x 89100 = 1200 x 103K”345
On the other hand, removed wood (specific heat 0, 18KcaQ/
kg'C.

When the latent heat of fusion (65.5 KcaA/kg) is introduced into a converter with a molten steel temperature of 1850°C, the heat particles to be inhaled are caV per ton of 400 pieces x 10', so the removal of material is introduced every 15 minutes. Possibility is 1200
It is calculated that 103 KcaQ 400 X 10 KcaQ/T = 3°0 tons, but the result of actual converter operation also showed that it was possible to input 3 to 4 tons.

This is about a 50% increase in the amount of material removed compared to the case of operating a converter under almost the same conditions except for using a conventional converter lance, and converter blowing is efficient and saves energy. However, it was done economically.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main parts of one embodiment of the present invention, and FIG.
The figure is an end view taken along the line A--A in FIG. 1, and FIG. 3 is a cross-sectional explanatory view transparently showing the state inside the furnace body during steelmaking using the converter lance according to the present invention. 1...Converter lance la...Lance base 1b...Lance tip 2...Oxygen flow path 3...Cooling water outgoing path 4...Cooling water return path 5...・Innermost pipe 5a...Mixed gas throttle part 5b...Opening part 6...Oxygen nozzle 6a...Oxygen gas throttle part 6b...Nozzle widening part 7...Outside air Suction pipe 8... Converter body 9... Molten steel 10... Furnace hood 11... Bottom blowing tuyere

Claims (1)

[Claims] 1 In a converter lance having a structure in which a cooling waterway is formed outside the oxygen flow path, the oxygen nozzle provided at the tip of the oxygen flow path is located closer to the base side than the lance tip within the innermost pipe forming the cooling waterway. At the same time, a plurality of outside air suction pipes are provided that penetrate the cooling waterway near the oxygen nozzle and communicate the space inside the innermost pipe outside the oxygen nozzle with the outside of the lance, and at the tip of the lance, the innermost pipe A converter lance is characterized in that the lance forms an opening that expands outward through a mixed gas throttle.