JP6347200B2 - Top blowing lance device for RH vacuum degassing equipment - Google Patents

Description

  The present invention relates to an upper blowing lance device for RH vacuum degassing equipment.

  In the RH vacuum degassing equipment, the molten steel in the riser is raised into the vacuum chamber by blowing argon gas into one (rising pipe) of the two pipes (immersion pipe) immersed in the molten steel in the ladle. After the molten steel is exposed to vacuum in the vacuum tank, the other pipe (downcomer pipe) is returned to the ladle and this reflux (ascending pipe-vacuum tank-downcomer-ladle-ascending pipe) is repeated. The final refining is done.

  In the refining process of molten steel using such an RH vacuum degassing facility, various techniques for providing an upper blow lance device in the RH vacuum degassing facility for the purpose of adjusting the temperature of the molten steel and improving the efficiency of refining have been disclosed. The upper blowing lance in the RH degassing facility is usually inserted into the vacuum chamber through a seal hole installed in the center of the upper lid of the vacuum chamber, and moves vertically up and down, and gas is directed vertically downward toward the center of the vacuum chamber bottom. However, Patent Document 1 discloses that an oxygen-containing gas is blown from the top blowing lance toward the riser side, whereby a fire point (the oxygen-containing gas jet is in the molten steel bath surface in the vacuum chamber). A technique is disclosed in which the region sprayed on the top of the vacuum tank is moved closer to the strong stirring region by the reflux gas bubbles on the riser side from the center point of the vacuum chamber, and the supply rate of molten steel contributing to the reaction at the fire point is increased.

  Also, in the RH vacuum degassing equipment, the rising reflux pipe (rising pipe) has a higher refractory wear rate than the descending reflux pipe (falling pipe). Since it is common to extend the life of the refractory by using it as an ascending pipe, in Patent Document 1, it is assumed that two reflux pipes are used alternately as an ascending pipe, As a technique for blowing the oxygen-containing gas from the lance toward the ascending pipe, a technique that can change the jet direction of the oxygen-containing gas jet is also disclosed. Specifically, in Patent Document 1, as means for enabling the change of the jet direction of the oxygen-containing gas jet, a working gas outlet is provided on the inner wall of the nozzle provided at the tip of the upper blowing lance, and the oxygen-containing gas (main gas) ) Is used to eject the working gas so as to be orthogonal to.

  However, when the working gas outlet is provided on the inner wall of the nozzle provided at the tip of the top blowing lance as described above, it is necessary to install a working gas pipe in addition to the main gas pipe in the top blowing lance. However, in the existing top blowing lance, in addition to the main gas pipe, there is also a water channel for circulating a large amount of cooling water. Usually, there is room for adding a new working gas pipe. There is no. Therefore, in the technique of Patent Document 1, it is required to change the top blowing lance itself to one having a large diameter, and this is accompanied by a significant modification such as reinforcement of the building foundation, and the return on investment is not commensurate. There was a problem.

Japanese Patent No. 4032930

  An object of the present invention is to solve the above-mentioned problems and to provide a technique that allows the jet direction of a gas jet to be changed in an RH vacuum degassing facility without expanding the upper blowing lance diameter.

  In order to solve the above-mentioned problems, an RH vacuum degassing equipment top blowing lance device of the present invention has a plurality of vertical gas flow paths arranged in a top blowing lance having a laval nozzle at the tip, A throttle part connecting the end part of the path and the upper end part of the Laval nozzle is provided, and gas flow rate adjusting means is provided to make the gas flow rate of each gas flow path adjustable for each gas flow path. It is.

  According to a second aspect of the present invention, in the top blow lance device of the RH vacuum degassing facility according to the first aspect, the plurality of gas flow paths are formed by dividing a cylindrical interior of a single tubular body by partition walls. It is also characterized by being a plurality of gas flow paths.

  According to a third aspect of the present invention, in the top blowing lance device of the RH vacuum degassing facility according to the second aspect, the partition wall is a partition wall that divides the cylindrical interior of one tubular body into two left and right flow paths. It is characterized by this.

  An upper blowing lance device of the RH vacuum degassing facility according to the present invention has a plurality of vertical gas flow paths arranged in an upper blowing lance provided with a Laval nozzle at the tip, the end of the gas flow path and the Laval nozzle. In order to provide a gas flow rate adjusting means for adjusting the gas flow rate of each gas flow path for each gas flow path, including the throttle part connecting the upper end portions, the flow rate of gas flowing through each gas flow path is adjusted, It is possible to freely change the flow direction of the gas that joins at the throttle portion. That is, according to the present invention, as in Patent Document 1, it is possible to freely change the flow direction of the gas to be merged at the throttle portion using only the main gas without using the working gas. It is not necessary to expand the upper blowing lance diameter to increase the working gas piping, and the jet direction of the gas jet ejected from the Laval nozzle can be changed by a simple method.

  According to a second aspect of the present invention, by dividing the cylindrical interior of one tubular body with the partition walls to form a plurality of gas flow paths, the partition walls are added to the conventional upper blowing lance. In this way, the jet direction of the gas jet ejected from the Laval nozzle can be changed freely.

It is a whole explanatory view of RH vacuum degassing equipment provided with the top blowing lance device of this embodiment. It is explanatory drawing explaining the principle which adjusts the gas flow rate within an upper blowing lance, and changes the jet direction of a gas jet. It is explanatory drawing explaining the principle which adjusts the gas flow rate within an upper blowing lance, and changes the jet direction of a gas jet. It is explanatory drawing explaining the principle which adjusts the gas flow rate within an upper blowing lance, and changes the jet direction of a gas jet. It is a graph which shows the relationship between the jet angle (alpha) of a gas jet, and the ratio of the gas flow rate of the gas flow path on either side.

  Preferred embodiments of the present invention are shown below.

  In FIG. 1, 1 is an RH vacuum degassing facility, and 2 is an upper blowing lance device. The top blowing lance device 2 includes two gas flow paths 4 and 5 formed by dividing a cylindrical interior of a tubular body into two right and left flow paths 3, a divergent type Laval nozzle 6, and the like. The throttle part 7 connects the end parts of the gas flow paths 4 and 5 and the upper end part of the Laval nozzle 6. In the present embodiment, the lower end of the throttle portion 7 is connected to the upper end portion of the Laval nozzle 6 via the straight portion 8.

  The top blowing lance device 2 in the RH degassing facility 1 is arranged with a large distance from the bath surface in order to avoid splash of molten steel as a characteristic of the facility, but the Laval nozzle 6 can be used even under such conditions. The aperture ratio is designed appropriately from the back pressure of the nozzle and the atmospheric pressure so that the gas jet reaches the bath surface with sufficient kinetic energy.

  Each of the two gas flow paths 4 and 5 is provided with a gas flow meter, and a gas flow rate adjusting means that can be adjusted by the opening degree of a flow control valve in which the gas flow rates of the gas flow paths 4 and 5 are installed. ing.

  For example, as shown in FIG. 2, when the gas flow rate (A) of the gas flow channel 4 is adjusted to be larger than the gas flow rate (B) of the gas flow channel 5, the gas flow channels are exited and joined by the throttle unit 7. The gas forms a flow toward the right in the drawing of FIG. The gas flow in the right direction is reflected by colliding with the straight portion 8 or the left side wall of the Laval nozzle 6 to form a flow toward the left side in FIG. 2, and the gas jet ejected from the opening 9 of the Laval nozzle 6 The ejection direction is the left direction of the paper. )

  Further, as shown in FIG. 3, when the gas flow rate (A) of the gas flow path 4 is adjusted to be less than the gas flow rate (B) of the gas flow path 5, each gas flow path is exited and merged at the throttle unit 7. The gas forms a flow toward the left side in FIG. 3 in the throttle unit 7, and the jet direction of the gas jet ejected from the opening 9 of the Laval nozzle 6 is the right side of the page, as shown in FIG. When the gas flow rate in the gas flow path 4 and the gas flow rate in the gas flow path 5 are adjusted to be equal, the gas merged in the throttle unit 7 forms a flow that goes directly below the throttle unit 7, and the Laval nozzle 6 The jet direction of the gas jet ejected from the opening 9 is a vertically downward direction.

  In this way, by forming a plurality of gas flow paths by dividing the cylindrical interior of one tubular body by partition walls, a simpler method of adding partition walls to the conventional upper blowing lance is achieved. The ejection direction of the gas jet ejected from the Laval nozzle can be changed freely.

  In the present embodiment, the two gas flow paths 4 and 5 formed by dividing the cylindrical interior of the single tubular body 3 by the partition walls 3 that are divided into the two right and left flow paths are formed. 4 or more gas flow paths are formed inside the body by two or more partition walls, or a plurality of pipes are arranged inside the cylindrical shape of one tubular body to form a plurality of gas flow paths, A gas flow rate adjusting means that allows the gas flow rate to be adjusted for each gas flow path can be provided. In any case, as in Patent Document 1, the flow direction of the gas joined at the throttle portion can be freely changed using only the main gas without using the working gas. There is no need to expand the diameter and increase the number of working gas pipes, and the jet direction of the gas jet ejected from the Laval nozzle can be changed by a simple method.

  FIG. 5 shows a graph in which the relationship between the jet angle α of the gas jet and the ratio of the gas flow rates in the left and right gas flow paths is examined. This graph shows the ejection angle α of the gas jet when the ratio of the gas flow rate in the gas flow path 4 and the gas flow rate in the gas flow path 5 is changed in the off-line test in the RH vacuum degassing facility shown in FIG. It was obtained by investigating changes. As shown in FIG. 5, when the flow rate ratio A / (A + B) = 0.5 is used as a boundary, the discharge jet forms a flow toward the left side of the drawing in FIG. It was confirmed that the discharge jet flow saturates at a lance spread angle by forming a flow toward the right in FIG.

DESCRIPTION OF SYMBOLS 1 RH vacuum degassing equipment 2 Top blowing lance apparatus 3 Partition 4, 5 Gas flow path 6 Laval nozzle 7 Restriction part 8 Straight part 9 Opening part

Claims (3)

A plurality of vertical gas flow paths are arranged in an upper blowing lance provided with a Laval nozzle at the tip, and a throttle part connecting the end of the gas flow path and the upper end of the Laval nozzle is provided.
An upper blowing lance device for RH vacuum degassing equipment, comprising gas flow rate adjusting means for adjusting the gas flow rate of each gas flow channel for each gas flow channel.   2. The RH vacuum degassing facility according to claim 1, wherein the plurality of gas flow paths are a plurality of gas flow paths formed by dividing a cylindrical interior of a tubular body by partition walls. Blow lance device.   The upper blow lance device for an RH vacuum degassing facility according to claim 2, wherein the partition wall is a partition wall that divides a cylindrical interior of a tubular body into two right and left flow paths.