JP2018035441A - Lance and operation method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lance capable of improving the secondary combustion rate of a gas generated in a container and suppressing the erosion around an auxiliary nozzle, and an operation method using the same.SOLUTION: Provided is a lance made of a nozzle part and an internal space, projecting to the inside of a container and blowing a raw material gas thereto. The nozzle part comprises: a nozzle wall body including the internal space through which the raw material gas passes; a main nozzle communicated with the internal space, passing through the bottom part of the nozzle wall body and blowing off the raw material gas to the inside of the container; and an auxiliary nozzle communicated with the internal space, located in the circumferential direction of the lower part of the nozzle wall body and formed so as to pass through the nozzle wall body. The auxiliary nozzle is provided so as to be crossed with the extended line in the width direction passing through the center in the width direction of the nozzle part.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lance and an operation method using the lance. More specifically, the present invention relates to a lance that is easy to ensure the temperature in the container and has a long life and an operation method using the lance.

In general, in a converter, oxygen is supplied to the hot metal to oxidize C (carbon), Si (silicon), Mn (manganese), etc. contained in the hot metal, thereby producing hot metal. The temperature of the hot metal itself rises by heat generated in the oxidation process. At this time, generally, the ratio of the scrap that can be operated using the heat generated from the hot metal itself is about 20%.
For this reason, when it is going to increase the charging ratio of a scrap, the method of adding the substance which reacts with oxygen and generates heat, for example, Si (silicon) or C (carbon), is used.
As another method, there is a method of using the secondary combustion heat generated when the CO gas generated in the decarburization refining performed in the converter is again reacted with oxygen and changed to CO ₂ .
As described above, as a method for generating the secondary combustion heat, in addition to the main hole for refining the hot metal (Main-hole), the secondary combustion oxygen can be ejected to the lance nozzle. Providing (Sub-hole) is disclosed in Japanese Laid-Open Patent Publication No. 1995-138631.

However, even if a secondary hole is provided for secondary combustion, the secondary combustion rate has not been improved satisfactorily. In addition, although the normal lance which does not have a subhole is the use frequency of 200 to 300 times, the lance which has a subhole can be used less than 100 times, and there is a problem that the life is very short. There is.
Also, in order to improve the secondary combustion rate, the shape of the sub-hole was changed so as to be inclined at a predetermined angle with respect to the extension direction of the main hole. A stable use count could not be secured.
The reason is as follows. That is, the main hole spouts oxygen for refining from a height of about 1.5 m or more from the hot metal surface, and the main jet formed thereby collides with the hot surface. However, when the main jet collides with the molten metal surface and switches the direction to the upper part, there arises a problem of interfering with the flow of the oxygen auxiliary jet (sub jet) ejected from the auxiliary hole for the purpose of secondary combustion. For this reason, the auxiliary jet does not extend straight, but a phenomenon of backfire toward the sub-hole occurs again, causing thermal damage to the lance nozzle and shortening the life of the lance nozzle.

Japanese Patent Application Laid-Open No. 07-138631 Republic of Korea Registered Utility Model Publication No. 0199915 Korean Published Patent Publication No. 2011-0031533

An object of the present invention is to provide a lance capable of improving the secondary combustion rate of gas generated in a container and an operation method using the lance.
Another object of the present invention is to provide a lance capable of suppressing melting damage around the sub nozzle and an operation method using the lance.

The present invention consists of a nozzle part and an internal space, and is a lance that projects into the container and blows a raw material gas,
The nozzle part is
A nozzle wall including an internal space through which the source gas passes;
A main nozzle that communicates with the internal space and that blows the raw material gas into the container through the bottom of the nozzle wall;
A sub-nozzle that communicates with the internal space and is formed in the circumferential direction of the lower portion of the nozzle wall and penetrating the nozzle wall;
Consists of
The sub nozzle is provided so as to intersect with an extension line in the width direction passing through the center in the width direction of the nozzle portion.

The sub nozzle has an extension line extending in the width direction on the horizontal plane of the nozzle wall, the extension line of the sub nozzle extending from the inflow port of the sub nozzle to the discharge port for discharging the source gas flowing into the inflow port. It is formed so that it may cross | intersect.

The angle formed between the extension line of the sub nozzle and the extension line in the width direction is 5 ° to 30 °.

The sub nozzle is extended so that an extension line of the sub nozzle intersects with an extension line in the vertical direction of the nozzle portion.

In the sub nozzle, an angle formed by an extension line of the sub nozzle and an extension line in the vertical direction is 10 ° to 40 °.

The sub nozzle is designed to blow the raw material gas at supersonic speed.

A diameter of the discharge port is larger than a diameter of the sub nozzle corresponding to the space between the inflow port and the discharge port.

The sub nozzles may be provided in a number of 3 to 6 spaced apart from each other in the circumferential direction of the nozzle wall.

In the main nozzle, an extension line of the main nozzle extending to an outlet of the main nozzle through which the source gas is discharged from an inlet of the main nozzle communicated with the internal space intersects with the extension line in the vertical direction. It is formed so that it may do.

The angle formed by the extension line of the main nozzle and the extension line in the vertical direction is 0 ° to 20 °.

Further, the present invention is an operation method for refining hot metal,
Injecting the hot metal into the container;
Placing a lance on the hot metal;
Supplying raw material gas to the lance, and injecting the raw material gas through the main nozzle of the lance onto the hot metal;
A process of injecting the raw material gas through a sub nozzle located above the main nozzle in a direction intersecting the horizontal plane of the lance,
It is characterized by including.

In the process of passing the raw material gas in the direction intersecting the horizontal plane of the lance and injecting it through the sub nozzle,
The source gas is injected through the sub nozzle in a direction intersecting with an extension line in the width direction passing through the center in the width direction of the lance.

The source gas injected through the sub nozzle is injected through the sub nozzle in a direction intersecting with the vertical extension line of the lance.

The source gas passing through the sub nozzle passes through 10 to 40 degrees with respect to the vertical extension line of the lance and 5 to 30 degrees with respect to the width direction extension line. It is characterized by that.

The source gas passing through the sub nozzle is blown at supersonic speed.

The source gas passes through the main nozzle so as to be 20 ° or less with respect to an extension line in the vertical direction of the lance.

According to the present invention, the auxiliary nozzle is formed around the main jet by forming the sub nozzle above the main nozzle and intersecting with the extension line in the vertical direction. Moreover, the auxiliary jet is formed in a swirling flow shape by extending the sub nozzle so as to intersect the extension line in the width direction. Furthermore, the swirling flow of the auxiliary jet increases the contact rate or contact opportunity with the CO gas, thereby increasing the secondary combustion rate of CO. Therefore, a sufficient heat source can be secured through secondary combustion without adding another heat source from the outside.
In addition, by designing the sub nozzle as a supersonic nozzle type, it is possible to reduce the melting damage around the sub nozzle and improve the life of the lance.

The figure which shows roughly the converter operation process by embodiment of this invention. The disassembled perspective view of the lance by embodiment of this invention. Sectional drawing which shows the nozzle part of the lance by embodiment of this invention. The figure which shows notionally the state from which a nozzle part and oxygen are discharged | emitted. Shows the distribution of the CO ₂ gas by extending angle at which the sub-nozzle with respect to the horizontal direction of the extension line (extension line in the width direction) of the lance.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram schematically showing a converter operation process according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of a lance according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. It is sectional drawing which shows the nozzle part of the lance by. FIG. 4 is a diagram conceptually showing a state in which the nozzle part and oxygen are discharged, wherein FIG. 4a shows a nozzle part according to an embodiment of the present invention, and FIG. 4b shows a conventional nozzle. Part. Furthermore, FIG. 5 is a diagram showing the distribution of CO ₂ gas according to the extension angle of the sub nozzle with respect to the horizontal extension line (width direction extension line) of the lance.

The lance of the present invention will be described below with reference to FIGS.
A lance according to an embodiment of the present invention and an operation method using the lance are a lance 100 for blowing a raw material gas into a container in which a reaction gas is generated and an operation method using the lance 100. In the present invention, the reaction gas is a CO gas. The container is the converter 1, and the source gas is an oxidizing gas.
The converter 1 is charged with hot metal transported from a blast furnace and blown in gas such as oxygen, or charged with refining agents and other additives for adjusting various components. This is an equipment for producing molten steel by removing the impurities and adjusting the concentration to a desired component.
The lance 100 is a means for inserting oxygen gas into the hot metal M by being inserted into the container in which the hot metal M is charged, that is, the converter 1. The lance 100 according to the embodiment is provided with a nozzle portion 130 for blowing oxygen into the converter 1 and a passage 110a through which oxygen moves so that oxygen can be supplied to the nozzle portion 130. A body part 110.

Hereinafter, for ease of explanation, a line extending in the lance extension direction (that is, the vertical extension direction) is referred to as a vertical extension line L _n1 . A line extending in the width direction (horizontal direction or left-right direction) so as to pass through the center of the lance 100 in the width direction is referred to as a width direction extension line L _n2 .
Here, the extension line L _n1 in the vertical direction refers to the width direction of the lance 100, that is, the vertical axis from the center in the horizontal direction to the orthogonal direction, and the surface of the hot metal M in the converter 1, that is, The vertical axis in the direction perpendicular to the hot water surface. That is, the vertical extension line L _n1 is an extension line perpendicular to the width extension line L _n2 . Further, the widthwise extension line _Ln2 is a lateral extension line of the lance 100, and is an extension line in the direction perpendicular to the vertical axis of the lance 100, that is, the vertical extension line _Ln1. And a horizontal line that is parallel or horizontal to the surface of the molten metal. Hereinafter, “lance extension line” and “vertical axis in a direction perpendicular to the molten metal surface” have the same meaning as above, and may be given the same reference numerals.

As described above, the body portion 110 supplies or provides oxygen to the nozzle portion 130, and has a tubular shape with a passage 110 a serving as an empty space in which oxygen moves to the nozzle portion 130. The body part 110 according to the embodiment has a shape extending in one direction, and may be, for example, a cylindrical shape. The body part 110 is not limited thereto, and is a passage through which oxygen can move toward the nozzle part 130. It may be changed into various cylindrical shapes having One end of the body part 110 is connected to a gas supply part (not shown) that supplies oxygen gas, and the other end is connected to the nozzle part 130. Further, the body portion 110 may be designed such that a coolant flows through the inside of the body portion 110 by providing a flow path independent of the passage. For this reason, the lance 100 is protected from a high-temperature operating environment by the refrigerant circulating inside the body portion 110.

The nozzle part 130 is means for blowing oxygen that has moved through the passage 110 a of the body part 110 into the hot metal M in the converter 1. As shown in FIG. 3, the nozzle portion 130 is connected to the other end of the body portion 110 and has a nozzle wall 131 having an internal space communicating with the passage of the body portion 110, and the nozzle wall body 131. A main nozzle that discharges, injects or blows oxygen transmitted from the internal space 130a to the outside of the nozzle, and an upper side of the main nozzle 132 on the nozzle wall 131. The inner space 130a is formed so as to be located and communicated with the inner space 130a, and is not parallel to the upper and lower extension directions and the diametrical direction of the lance 100 but extends so as to be twisted at a predetermined angle. And a sub nozzle 133 that discharges, injects or blows oxygen transmitted from the outside.
The nozzle wall 131 is configured to form an internal space 130 a through which oxygen is transmitted from the passage 110 a of the body portion 110 and is configured to be blocked from the outside of the lance 100. Similar to the body portion 110, the nozzle wall body 131 is designed so that cooling water flows by providing a space flow path independent of the internal space 130a in order to protect it from a high-temperature operating environment.

The main nozzle 132 blows oxygen into the hot metal in the converter 1 and is formed to penetrate the nozzle wall 131 in one direction below the internal space 130a, with one end and the other end opened. Shape. One end of the main nozzle 132 is connected to or communicated with the lower end of the internal space, and the other end is formed to be positioned at the lower end of the nozzle wall 131 and exposed to the outside of the nozzle unit 130. Here, one end of the main nozzle 132 is an inflow port through which oxygen in the internal space flows (hereinafter referred to as a first inflow port 132a), and the other end of the main nozzle 132 is the nozzle unit 130 in which oxygen that has passed through the main nozzle 132 is formed. It is the discharge port (henceforth the 1st discharge port 132b) discharged | emitted outside.
The main nozzle 132 according to the embodiment is not parallel to the vertical direction of the extension line L _n1, the may be the vertical direction of the extension line L _n1 is extended to tilt at a predetermined angle, the angle is 20 ° or less It may be. To illustrate more specifically the main nozzle 132, the extension line of the extending direction of the main nozzle 132 called extension line L _m of the main nozzle, an extension L _m of the main nozzle in the width direction of the main nozzle 132 A line that passes through the center. In the main nozzle 132 according to the embodiment, the angle (hereinafter, referred to as the first angle θ _m ) or the depression angle formed by the extension line L _{m of the} main nozzle and the extension line L _{n1 in the} vertical direction is 20 ° or less, and preferably 15 ° to 17 °. It is extended so that it becomes °. This extension L _m of the main nozzle is obliquely disposed so as to form the extended line L _n1 and 20 ° or less an angle theta _m in the vertical direction, the molten metal surface of the extended line L _m is the converter of the main nozzle This means that the angle between is not vertical.

Above, extension L _m of the main nozzle has been described as an example a case where inclined vertical extension line L _n1 and 20 ° or less. However, the present invention this is not limited any way, as an extension L _m of the main nozzle is aligned with the vertical direction of the extension line L _n1 (or in parallel) extending to a first of The angle θ _m may be 0 °. This extension L _m of the main nozzle the angle formed with the molten metal surface of the converter in the meaning that is vertical.
Here, the first angle θ _m is not limited to any angle within the range of 0 to 20 °, but the greater the value within the range of the angle, the more oxygen (hereinafter, Since the radius of the main jet is increased, the time for blowing the hot metal M can be shortened as compared with the case of injecting oxygen in a vertical state. On the other hand, if it has a value of the first angle theta _m exceeds 20 °, although the radius of the main jet is increased, interference with the oxygen injected from the secondary nozzle 133 to be described later (hereinafter, referred to as auxiliary jet.) This may cause a problem that the main jet is not normally ejected onto the hot metal.

A plurality of the main nozzles 132 as described above are provided, but are separated from each other at the lower part of the nozzle wall 131. For example, six main nozzles 132 may be provided. Of course, the number of main nozzles 132 is not limited to six, and a number less than six or more than six may be provided.
The sub nozzle 133 is a nozzle for injecting oxygen for secondary combustion in which the reaction gas generated during operation in the converter 1 is burned again. Such a sub-nozzle 133 is extended above the main nozzle 132 so as to penetrate the nozzle wall 131 and has one end and the other end opened. Here, one end of the sub nozzle 133 is connected or communicated with the internal space above the first inflow port 132a, and the other end is exposed to the outside of the nozzle unit 130 above the first discharge port 132b. It is formed so that. One end of the sub-nozzle 133 is an inflow port (hereinafter referred to as a second inflow port 133a) into which oxygen in the internal space flows, and the other end is a portion where oxygen that has passed through the sub-nozzle 133 is the nozzle unit 130. This is a discharge port (hereinafter, referred to as a second discharge port 133b) that is discharged to the outside. As described above, the second discharge port 133b is formed so as to be exposed to the outside of the nozzle unit 130. For example, the second discharge port 133b is formed so as to be exposed on the side surface of the outer peripheral surface of the nozzle wall 131. May be. For this reason, oxygen injected from the sub nozzle 133, that is, the auxiliary jet, is injected in the direction around the main jet.

The sub nozzle 133 according to the embodiment is not parallel to the extension line L _{n1 in the} vertical direction and the extension line L _{n2 in the} width direction, but extends so as to be inclined at a predetermined angle from the extension lines in the first and width directions.
First, based on FIG. 3, the case where the sub nozzle 133 is extended so as to incline at a predetermined angle with respect to the extension line L _{n1 in the} vertical direction will be described.
The sub nozzle 133 is not parallel to the vertical extension line L _n1 but has an angle (hereinafter referred to as a second angle θ _s1 ) of 10 ° to 40 ° with the vertical extension line L _n1 . It is extended to. In order to describe the sub nozzle 133 more specifically, an extension line in the extension direction of the sub nozzle 133 is referred to as a sub nozzle extension line L _s, and the sub nozzle extension line L _s is the width direction of the sub nozzle 133. It is a line that passes through the center of. The extension direction of the sub-nozzle will be described again using the above-described definition. The sub-nozzle extension line L _s is extended so that the angle formed by the vertical extension line L _n1 is 10 ° to 40 °. . This means that the angle formed by the extension line L _s of the sub nozzle and the molten metal surface in the converter 1 is not vertical.

At this time, the second angle θ _s1 formed by the extension line L _{s of the} sub nozzle and the vertical extension line L _n1 is the first angle formed by the extension line L _{m of the} main nozzle and the vertical extension line L _n1 . it is preferably larger than the angle theta _m. That is, an extension L _m of the main nozzle vertical extension line L _n1 and the angle is 0 or more, when it is 20 ° or less, an extension L _s of the sub nozzles is angle between the vertical direction of the extension line L _n1 It is preferably greater than 20 ° and not greater than 40 °. This is because the oxygen flow is formed in the converter so that the radius of the auxiliary jet is larger than that of the main jet, but at an angle that can prevent interference with the main jet flow.
On the other hand, when the second angle θ _s1 is formed to have a value less than 10 °, the effect of suppressing interference with the flow of the main jet ejected from the main nozzle 132 is not obtained so much. That is, the main jet collides with the hot metal surface of the hot metal M, and the oxygen whose direction is switched upward collides with the auxiliary jet injected from the sub nozzle 133, and the auxiliary jet may lose straightness. For this reason, the reaction between the CO gas produced by the reaction between the carbon C in the hot metal in the converter 1 and the oxygen blown from the main nozzle 132 and the auxiliary jet is weak, and the 2 in the converter 1 by the sub nozzle 133 is weak. There is an inconvenience that the next combustion efficiency is lowered.

According to another example, when the second angle θ _s1 is formed to have a value exceeding 40 °, the upward flow of the main jet that the auxiliary jet extrudes and flows toward the upper side of the lance 100 is the fuselage of the lance 100. Since it directly collides with the part 110, there is a possibility that a disadvantage that the body part 110 is thermally damaged occurs. Further, in view of the characteristics of the internal space 130a of the nozzle portion 130, when the second angle θ _s1 exceeds 40 °, the end portion of the main nozzle 132 and the end portion of the sub nozzle 133 formed on the inner wall of the nozzle wall body 131. Since the sub nozzle 133 may take away the flow of oxygen that should escape from the internal space 130a to the main nozzle 132, there is a problem in that the efficiency of hot metal blowing by the main nozzle 132 is reduced. There is a fear. For this reason, the sub nozzle 133 may be formed on the nozzle wall 131 so as to have the value of the second angle θ _s1 described above.

In addition, the sub nozzle 133 according to the embodiment of the present invention is formed not to be parallel to an extension line of the horizontal plane on the transverse sectional view of the lance or the nozzle wall 131 but to intersect the horizontal plane. That is, the sub-nozzles 133 are not parallel to the width direction of the extension line L _n2 through the center in the width direction of the lance or nozzle wall 131 (or, not folded on the same line), and the extension line in the width direction L _n2 predetermined (Hereinafter referred to as a third angle). That is, the extension line L _{s of the} sub nozzle is not parallel to the extension line L _{n2 in the} width direction (or is not on the same line), and the extension line L _{s of the} sub nozzle is the second in relation to the extension line L _{n2 in the} width direction. The angle is inclined at an angle θ _s2 of 3. At this time, the third angle θ _s2 formed by the extension line L _{n2 in the} width direction and the extension line L _{s of the} sub nozzle is 5 ° to 30 °.
In other words, the extension direction of the sub nozzle 133 means that it extends in the circumferential direction of the nozzle wall 131 when it extends from the second inflow port 133a toward the second discharge port 133b. means. That is, an extension of the extension line _{L s} of the sub-nozzle connecting the second inlet 133a and a second outlet 133b passes through the center C in the width direction of the nozzle wall 131, i.e., an extension in the width direction _{L n2} It does not located on the angle at which the extended line L _s of the sub nozzle forms an extension L _n2 in the width direction is made to be a 5 ° to 30 °.

In other words, the auxiliary nozzle 133 extends in the circumferential direction of the nozzle wall 131. The auxiliary nozzle 133 has a rotation angle of 5 ° to 30 ° in the circumferential direction of the nozzle wall 131. It is meant to be formed.
Thus, by extending so that the sub nozzle 133 is not located on the same line as the extension line L _{n2 in the} width direction (or the sub nozzle 133 is not parallel to the extension line L _{n2 in the} width direction). As shown in FIG. 4a, the oxygen blown from the sub nozzle 133 forms a swirl flow. When oxygen is blown in the form of a swirling flow, the residence time in the converter 1 is extended as compared with the case where it is not, and as a result, contact with the CO gas generated by the reaction between the main jet and the carbon in the hot metal M occurs. Increases rate or contact opportunity. As a result, the secondary combustion rate at which CO becomes CO ₂ increases, and the heat generated when the CO is subjected to secondary combustion serves as a heat source for raising the temperature of the hot metal M.

On the other hand, as shown in FIG. 4b, the sub nozzle is inclined at 10 ° to 40 ° with respect to the extension line L _{n1 in the} vertical direction, but the extension line L _{s of the} sub nozzle is connected to the extension line L _{n2 in the} width direction. When they are parallel or on the extension line _{Ln2 in} the width direction, the swirling flow by the sub nozzle is not generated or the strength of the swirling flow is low as in the present invention. For this reason, in the case of the nozzle part 130 of FIG. 4b, a secondary combustion rate is low compared with the nozzle part by embodiment of FIG. 4b.
Furthermore, as shown in FIG. 5, the distribution area of the CO ₂ gas varies depending on the angle of the extension line L _s of the sub nozzle. FIG. 5a shows a case where the third angle θ _s2 is 0 ° because the extension line L _s of the sub nozzle is on the extension line L _{n2 in} the width direction. 5B and 5C, the extension line L _s of the sub nozzle is not on the extension line L _{n2 in} the width direction, and the extension line L _{s of the} sub nozzle intersects the extension line L _{n2 in the} width direction. 5b is a case where the third angle is 10 °, and FIG. 5c is a case where the third angle is 25 °.

FIG. 5 shows the result of numerical analysis of the gas concentration in the converter 1 when the third angle is changed to 0 °, 10 °, and 25 °, and the third angle θ _s2 becomes wider. As can be seen, the distribution area of the concentration of the CO ₂ gas increases. Further, when the third angle of the sub nozzle 133 exceeds 30 °, oxygen discharged from the sub nozzle 133 overlaps, and the amount of secondary combustion generated rather decreases. Therefore, in the present invention, the angle of the extended line L _n2 extension line L _s and the width direction of the auxiliary nozzle forms are set to be 5 ° to 30 °.
The second discharge port 133b of the sub nozzle 133 may be formed at a location 100 to 200 mm away from the end of the nozzle portion 130 facing the converter 1.
If the second discharge ports 133b are spaced apart from each other by less than 100 mm from the end of the nozzle portion 130, the distance between the first discharge port 132b and the second discharge port 133b is small, so that the main jet Among them, the auxiliary jet that changes the rising flow that collides with the hot metal surface of the hot metal M is not injected, and the effect of suppressing the interference between the main jet and the auxiliary jet is not so much obtained.

Conversely, when the second discharge ports 133b are spaced apart from each other by more than 200 mm from the end of the nozzle portion 130, the distance between the first discharge port 132b and the second discharge port 133b is very large. An auxiliary jet that suppresses the nozzle wall 131 from being damaged by the second discharge port 133b formed above the position where the upward flow of the main jet reaches the nozzle wall 131. The role of is insignificant. Therefore, the second discharge port 133b is formed at the end of the nozzle portion 130, that is, at a location 100 to 200 mm away from the first discharge port 132b.
A plurality of the sub nozzles 133 described above are provided, but are spaced apart from each other in the circumferential direction or the circumferential direction of the nozzle wall. In the embodiment, three to six sub nozzles 133 are provided. If the number of sub-nozzles 133 is too small (less than 3), the chance of secondary combustion is reduced. If the number of sub-nozzles 133 is more than 6 and too large, the flow rate of oxygen flowing out through the sub-nozzles 133 is uniform. Therefore, in the case of the sub nozzle 133 with a small flow rate, there is a possibility that molten steel or iron ore is infiltrated and clogged, and in the case of the sub nozzle 133 with a low flow rate, the possibility of melting damage due to backfire increases.

On the other hand, when the sub nozzle 133 is applied to the lance 100, the biggest factor that shortens or lowers the life or the number of times of use of the lance 100 is melting damage around the sub nozzle 133. The melting damage around the sub nozzle 133 is because the flow rate of oxygen discharged from the sub nozzle 133 is slow, so it does not pass through the flow of CO gas that flows out toward the top, but rather backfires toward the sub nozzle 133. is there.
In order to prevent such a backfire phenomenon, it is necessary to sufficiently increase the speed of the oxygen gas injected (or blown) from the sub nozzle 133. For this reason, in the embodiment of the present invention, the flow rate is increased. In order to maximize it, the sub nozzle 133 is designed to be a supersonic nozzle type. That is, the diameter De of the second discharge port 133b is formed to be larger than the internal diameter Dt of the sub nozzle 133 corresponding to the space between the second inflow port 133a and the second discharge port 133b. Thereby, while oxygen flows into the 2nd inlet 133a of the sub nozzle 133, and passes the 2nd outlet 133b, it is designed so that the movement speed of oxygen may become larger than a sonic speed by gas expansion. .

Further, in the embodiment, when adjusting the diameter (De, mm) of the second outlet 133b so that oxygen is injected at supersonic speed through the sub nozzle 133, the oxygen blown through the sub nozzle 133 is blown. It is determined using the amount of penetration (Q, Nm ³ / min), the pressure of oxygen (P ₀ , kg / cm ² ), the number of sub nozzles (N), the internal diameter (Dt, mm), and the speed of sound (Ma). In embodiments, using the following equation 1 and 2, to determine the diameter _{D e} of the second outlet 133b of the sub-nozzles 133.

First, the flow rate of oxygen injected from the sub nozzle 133 is determined. At this time, the volume ratio is preferably 3% to 15% of the flow rate of oxygen injected from the main nozzle 132. If the flow rate of oxygen is less than 3%, the flow rate of oxygen passing through the sub-nozzle 133 is small, so that the secondary combustion effect is not obtained so much. If the flow rate of oxygen exceeds 15%, the oxygen required for the refining reaction There is a disadvantage that the refining time is extended due to the small amount.
Here, the pressure of oxygen is a value that is already set (or already determined), and the number of sub-nozzles 133 is determined to be 3 to 6. For this reason, when the flow rate of oxygen, the number of sub nozzles, and the pressure of oxygen are applied to Equation 1, the internal diameter D _t of the sub nozzle 133 is calculated.
The above equation 1, the number of sub-nozzles 133, the internal diameter, the pressure of oxygen is determined, determining the diameter De of the internal diameter D _t it is applied to the above equation 2.

In Formula 2, Ma is the Mach number as described above, and the Ma number is 1.5 to 2.5. When the internal diameter D _t calculated from the above equation 1 is applied to the above equation 2, the diameter De of the second discharge port 133b can be determined.
Thereby, the oxygen passing through the sub nozzle 133 is injected at supersonic speed.
Table 1 below compares the life of the lance when the nozzle portion is applied according to the example and the comparative example and the rising temperature due to the secondary combustion.
For the experiment, 250 tons of hot metal and 40 tons of scrap iron were charged into a 290-ton capacity converter, and oxygen was supplied to the lance at 850 Nm ³ / min for blowing.
The nozzle unit 130 according to the first comparative example, the sub-nozzles 133 are six, are 14mm internal diameter _{D t} and diameter _{D e} of the second outlet 133b are both of the sub nozzle 133, the sub nozzle The amount of oxygen blown from 133 is 2.9% of the amount of oxygen blown from the main nozzle 132.

Furthermore, the second and third comparative examples and the first and second examples are both supersonic nozzle types, with an inner diameter Dt of 14 mm and a second outlet diameter of 19.4 mm. The number of sub nozzles 133 and the amount of oxygen blown were changed.

Referring to Table 1 above, in the case of the first comparative example in which the sub nozzle 133 is a normal nozzle type, the number of times of use is significantly higher than in the second and third comparative examples and the first and second embodiments. It can be seen that the temperature rise effect is small. This is because the flow rate of oxygen injected from the sub-nozzle 133 becomes lower than the sound velocity, the back-fire is generated around the sub-nozzle, and melting damage occurs.
In the second comparative example, although the number of times of use is increased as compared with the first comparative example, the number of sub-nozzles 133 is less than three, and as a result, the secondary combustion efficiency is lowered, and the first and third comparisons are performed. An example shows the temperature raised compared to the first and second examples.
On the contrary, in the third comparative example, the temperature rise is higher than that in the first and second comparative examples and the first and second embodiments, but the number of sub nozzles 133 is six. Since the number is more than eight, a uniform amount of oxygen cannot be supplied from the eight sub nozzles 133, and the sub nozzles 133 with a small oxygen flow rate cause melting damage and the number of uses is reduced. That is, if the number of sub nozzles 133 is too large, uniform oxygen cannot be supplied to all the sub nozzles 133, and in the case of the sub nozzles 133 having a relatively small oxygen flow rate, the possibility of melting damage increases.

In the case of the first and second examples, both the number of uses and the temperature increase effect were increased compared to the first comparative example.
In addition, although the first and second examples are less used than the second comparative example, the number of uses is 127 and 115, respectively, which is considerably higher than that of the first comparative example. Although it was in an increased state, the temperature rising effect was lower than that of the third comparative example, but it was sufficiently higher than that of the first and second comparative examples.
For this reason, it can be seen from the first and second embodiments that the lance 100 according to the present invention improves both the number of uses and the temperature rise effect.

Hereinafter, a converter operating method using a lance according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5.
First, the hot metal conveyed from the blast furnace is charged into the converter 1. At this time, in order to remove impurities in the hot metal M, at least a part of the lance 100 is inserted into the converter 1, and the end of the lance 100 is spaced on the molten metal surface of the hot metal M. So that
When the lance 100 is disposed, the gas supply unit is operated to supply oxygen to the passage 110a of the lance 100. The oxygen supplied from the gas supply device is moved along the passage of the body portion 110 and flows into the internal space 130 a of the nozzle portion 130.

Oxygen that has flowed into the internal space of the nozzle portion 130 is blown into the hot metal via each of the plurality of main nozzles 132 and sub nozzles 133, thereby starting blowing. At this time, most of the oxygen blown from the main nozzle 132 reacts with the carbon C in the hot metal to participate in decarburization to lower the carbon concentration. In addition, oxygen injected through the sub nozzle 133, that is, the auxiliary jet, is blown around the main jet blown from the main nozzle 132 with a wider radius than the main jet. Note that most of the oxygen blown from the sub nozzle 133 reacts with the CO gas generated during the decarburization process, causing the CO to undergo secondary combustion, and the temperature of the hot metal rises due to the heat generated during the secondary combustion. To do.
That is, first, the reaction between the oxygen O of the oxidizing gas and the carbon C present in the hot metal is performed to generate CO gas. Then, when the blowing is continued, The secondary combustion reaction is performed simultaneously.

Here, the sub nozzle 133 according to the embodiment is positioned above the main nozzle 132 and is formed to be inclined by 10 ° to 40 ° with respect to the extension line L _{n1 in the} vertical direction, so that the auxiliary jet is formed around the main jet. Is formed. Further, the auxiliary nozzle 133 is extended so as to form an angle of 5 ° to 30 ° with respect to the extending line L _{n2 in the} width direction, whereby an auxiliary jet is formed in a swirling flow. Note that the swirl flow of the auxiliary jet increases the contact rate or contact opportunity with the CO gas, thereby increasing the secondary combustion rate of CO. Therefore, a sufficient heat source can be secured by secondary combustion without adding a separate heat source from the outside.

100: Lance
110: Body part 130: Nozzle part
132: Main nozzle 133: Sub nozzle
L _n1 : Extension line in the vertical direction L _n2 : Extension line in the width direction
L _m : Extension line of the main nozzle L _s : Extension line of the sub nozzle

Claims (16)

A lance that consists of a nozzle part and an internal space, protrudes into the container and blows the raw material gas,
The nozzle part is
A nozzle wall including an internal space through which the source gas passes;
A main nozzle that communicates with the internal space and that blows the raw material gas into the container through the bottom of the nozzle wall;
A sub-nozzle that communicates with the internal space and is formed in the circumferential direction of the lower portion of the nozzle wall and penetrating the nozzle wall;
Consists of
The sub-nozzle is provided so as to intersect with an extension line in the width direction passing through a center in the width direction of the nozzle portion. The sub nozzle has an extension line extending in the width direction on the horizontal plane of the nozzle wall, the extension line of the sub nozzle extending from the inflow port of the sub nozzle to the discharge port for discharging the source gas flowing into the inflow port. The lance according to claim 1, wherein the lance is formed so as to intersect with the lance. The lance according to claim 2, wherein an angle formed by the extension line of the sub nozzle and the extension line in the width direction is 5 ° to 30 °. The lance according to claim 3, wherein the sub nozzle extends so that an extension line of the sub nozzle intersects with an extension line in the vertical direction of the nozzle portion. 5. The lance according to claim 4, wherein the sub nozzle has an angle formed by an extension line of the sub nozzle and an extension line in the vertical direction of 10 ° to 40 °. The lance according to any one of claims 2 to 5, wherein the sub nozzle is designed to blow the raw material gas at supersonic speed. The lance according to claim 6, wherein a diameter of the discharge port is larger than an inner diameter of the sub nozzle corresponding to the space between the inflow port and the discharge port. The lance according to claim 7, wherein the sub nozzles are provided in a number of 3 to 6 that are spaced apart from each other in a circumferential direction of the nozzle wall body. In the main nozzle, an extension line of the main nozzle extending to an outlet of the main nozzle through which the source gas is discharged from an inlet of the main nozzle communicated with the internal space intersects with the extension line in the vertical direction. The lance according to any one of claims 2 to 5, wherein the lance is formed as described above. The lance according to claim 9, wherein an angle formed by the extension line of the main nozzle and the extension line in the vertical direction is 0 ° to 20 °. An operation method for refining hot metal,
Injecting the hot metal into the container;
Placing a lance on the hot metal;
Supplying raw material gas to the lance, and injecting the raw material gas through the main nozzle of the lance onto the hot metal;
A process of injecting the raw material gas through a sub nozzle located above the main nozzle in a direction intersecting the horizontal plane of the lance,
A method of operation characterized by comprising. In the process of passing the raw material gas in the direction intersecting the horizontal plane of the lance and injecting it through the sub nozzle,
The operation method according to claim 11, wherein the source gas is injected through the sub nozzle in a direction intersecting with an extension line in a width direction passing through a center in a width direction of the lance. The operation method according to claim 12, wherein the raw material gas injected through the sub nozzle is injected through the sub nozzle in a direction crossing an extension line in the vertical direction of the lance. . The source gas passing through the sub nozzle passes through 10 to 40 degrees with respect to the vertical extension line of the lance and 5 to 30 degrees with respect to the width direction extension line. The operation method according to claim 12, wherein: The operation method according to claim 14, wherein the source gas passing through the sub nozzle is blown at supersonic speed. The operation method according to claim 13, wherein the source gas passes through the main nozzle so as to be 20 ° or less with respect to an extension line in the vertical direction of the lance.

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