JPS63153213A - Submerged tube and method for gas blowing - Google Patents

Abstract

PURPOSE:To increase circulating quantity by blowing only a little gas by from gas blowing holes formed in a circumferential wall of submerged tube in a direction swerving slightly from the center of the tube. CONSTITUTION:The submerged tube 3 is constituted by forming regular shaped refractory layer 3b at the internal circumference of metal-made cylinder 3a and monolithic refractory layer 3c at the outer circumference and the gas blowing holes 5 opening on the inner face 3d of tube. Further, the above gas blowing holes 5 are formed, so that the gas blowing direction (f) into the tube is deviated from the center (c) of the tube 3, in which the gas is blown. And, the gas blowing holes 5 are arranged in almost equal intervals at three positions or more and extending direction of holes are desirably formed, so as to deviate to the same side from the center (c). This submerged tube 3 is connected with the circulating tube of RH degassing apparatus through a flange 4, to blow inert gas from the above hole 5. The blowing gas is ascended together with the molten steel while forming spiral flow in the submerged tube 3 and the circulating quantity is increased by little blowing gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a gas blowing immersion tube for use in a vacuum degassing device, etc., and a blowing method.

[Prior Art] Conventionally, inert gas injection from the shaped refractory layer of a dipping tube for vacuum degassing equipment was carried out using a dipping tube having a gas blowing hole (passage) in the center of the inner cylinder. known to be used.

To explain this with reference to FIGS. 4 and 5, the extension f'' of the inert gas injection hole 5' coincides with the center C' of the pipe.Therefore, the kinetic forces during gas injection mutually cancel each other out. And the accompanying 1 increase force has no spiral effect.

[Problems to be Solved by the Invention] The present invention has a method in which inert gas is blown into a submerged tube for an RH vacuum degassing device, which has not been known in the past, in a direction slightly shifted from the center of the cylinder. The purpose of this is to increase the reflux rate of the RH vacuum degassing device or reduce the amount of inert gas blown into the cylinder to obtain the same reflux rate as in the conventional system, which was blown into the center of the cylinder. It is something to do.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and specifically, the inner periphery of the metal cylinder is made of a shaped refractory layer, and the outer periphery is made of an unshaped refractory layer. An immersion tube for a vacuum degassing device that allows inert gas to be blown from a refractory layer such as the shaped refractory layer in a direction slightly shifted from the center of the tube in an immersion tube constructed of layers. With pipe and blowing method,
In particular, the present invention provides an immersion tube for a vacuum degassing device in which the direction of inert gas blowing through a plurality of holes is slightly offset from the center of the immersion tube, and the inert gas can be blown into the tube in a spiral manner at the center of the tube.

A typical immersion tube for an RH vacuum degasser will be described below with reference to the drawings.

As can be seen in FIGS. 3 and 4, the vacuum degassing device is provided with a reflux tube 2 and a dip tube 3 connected by a flange 4 at the bottom of a vacuum chamber 1.

This immersion tube 3 has an inert gas blowing hole (passage) 5 formed therein.

Note that the immersion tube 3 may be made of a refractory material that is uniform in the thickness direction, but usually, as shown in FIG. The one composed of the shaped refractory layer 3C is a mistake.

The present invention is characterized in that inert gas blowing holes (passages) 5 are formed in at least the internal measuring refractory layer of such a immersion tube in a specific direction.

That is, a gas blowing hole opened on the inner surface 3d of the tube is formed so that the direction of gas blowing into the tube from the hole is shifted from the center of the tube. Explain in detail.

Although the metal cylinder and the inner and outer refractory layers are not shown separately in Fig. 2 for ease of understanding, the blow holes 5 that penetrate horizontally and linearly over the entire width of the pipe in the inner thickness direction are arranged at approximately equal intervals. This is a typical example in which four are formed in a horizontal position.

In general, it is sufficient to have the holes in two or more positions in the vertical (vertical) direction, but it is of course also possible to form them in a plurality of holes, or to form them in four positions slightly shifted from each other.

Note that the height position of this blow hole should normally be formed slightly below the repair of the entire product, so if the inner refractory layer is divided, it corresponds to that position. For example, if it is divided into three parts, it may be formed in the middle refractory layer.

As shown in FIG. 2, the blow hole in the present invention is formed so that the direction of gas blowing from the inner surface of the tube is offset from the center C (that is, the extension of the blow hole is offset from the center C). Because there is.

It is necessary that at least the extension line of the hole is offset from the center C, but there is no problem even if it has a slight slope in the vertical direction, and the hole must necessarily penetrate in a straight line. Moreover, the hole may be formed directly in the refractory pipe itself, or may be formed by fitting another tubular object into it.

Generally, a plurality of blow holes are required in order to efficiently generate rotational force of the fluid in the pipe, and preferably 3 to 10 holes, preferably 4 to 8 holes, equally spaced in the circumferential direction.

In addition, if it is possible to adjust the rotational force of the fluid in the pipes, the circulation driving force, or the rising force of the bubbles in the fluid, etc., the number of pipes, the interval, the blowing amount, the deviation angle of the holes, etc. can be selected appropriately. It is possible, and depending on the purpose, these can be formed differently for each hole.

In order to generate an efficient flow in the pipe by blowing gas, it is necessary to make sure that the extension directions from the plurality of holes do not coincide at the center C of the pipe, and a preferable example for this is to The direction is to be shifted toward the same side of the center as seen from the hole (in Fig. 2, the extension line f is always on the right side of the center C). As can be seen in the figure, the flow inside the tube is counterclockwise when viewed from above, and a spiral flow is likely to occur due to the counterclockwise rotational force.

In the present invention, the appropriate degree of deviation of the gas injection direction from the center of the pipe can be explained with reference to FIG. The diameter d1 of g should be 5 to 50% of the pipe inner diameter d2, preferably 10 to 30%.

Furthermore, when considering the directionality of the thin flow, when viewed from above, a left-handed thin flow has a force applied in an upward direction, and a right-handed vortex flow has a force applied in a downward direction.

Therefore, since the purpose of gas injection through the immersion tube is to apply upward force to the molten steel, it is desirable to specify the direction of the gas injection hole so as to provide a left-handed rotational flow.

The method of blowing gas into a submerged tube for a vacuum degassing device according to the present invention will be further explained as follows.

1. Inert gas is blown into the molten steel from the immersion pipe section to improve circulation flow and degassing ability of the molten steel (gas lift pump action). 2. To make the lift pump action more efficient.

Slightly below the station of the total height of the immersion pipe, equally spaced in the circumferential direction 4
- Eight gas blowing holes are provided so that the extension direction is offset from the center of the pipe.

3. Blow gas toward the center of the inner circumference of the immersion tube. The amount and pressure of gas blowing should be such that the gas cross-sectional distance in the L riser tube reaches near the center of the inner diameter of the riser tube. This improves liquid mixing and effectively acts as a reflux driving force.

4. Since the gas injection is staggered, the mutual cancellation of the slow force during gas injection is eliminated, and by converting it into the rotational force of the fluid, the circulation driving force is the combination of the bubbling upward force and the fluid rotation upward force. Reciprocal effects emerge.

(In addition, when the gas is injected so that it coincides with the center of the riser tube as shown in Fig. 4 and Fig. 5, the power of the injected gas is
At the matching point (i.e., the center), they cancel each other's kinetic forces, but because the gas bubbles, a driving force as an upward flow is generated due to the difference in specific gravity. 5. Although the direction of gas blowing from the plurality of holes in the riser tube is toward the center of the inner periphery of the tube, in the present invention, the gas is blown in a spiral manner.

That is, the blowing directions are slightly offset from the center.

[Example] The effects of the immersion tube and blowing method of the present invention were confirmed by simulating an RH vacuum degassing device and conducting a water model experiment. That is, in the apparatus shown in Fig. 3, the immersion tube shown in Fig. 1 (height 200 mm, inner diameter 80 mm, gas inlet holes are located slightly below the center, equidistant in the circumferential direction) is used. 4, the hole diameter is 2.5 mm, and the deviation of the hole extension direction from the center of the tube is the direction in which the diameter of the small circle is 25% of the inner diameter of the tube when a small circle is drawn with the extension line as the circumscribed tangent. 3QjL/win of N2 gas from the gas injection hole
It was injected under the following conditions.

As a result, the water circulation capacity is lower than when using a dipping tube with the holes facing toward the center.

It improved by about 20%.

In addition, the amount of injection to obtain the same amount of recirculation is approximately 1
It was confirmed that the amount could be reduced by 0%.

[Function] In the present invention, according to the inert gas blowing method using the immersion tube for RH vacuum degassing equipment, the gas can be blown spirally in a direction slightly shifted from the center of the inner circumference of the immersion tube, which is different from the conventional method. By eliminating the mutual cancellation of the kinetic force during gas injection and converting it into the rotational force of the molten steel, the reflux driving force becomes a mutual effect of the gas bubbling upward force and the fluid rotation upward force. This makes it possible to process molten steel efficiently.

[Effects of the Invention] The present invention provides a method for blowing inert gas into a dipping tube for an RH vacuum degassing device by blowing spirally in a direction slightly shifted from the center of the inner periphery of the dipping tube. By converting the force into rotational force of the molten steel, the recirculation driving force increases the recirculation flow rate or decreases the amount of inert gas blown through the mutual effect of the gas bubbling upward force and the rotational upward force of the fluid. The effect of this is recognized.

Furthermore, improvement in reflux ability can be expected to have effects on degassing ability, scouring ability, etc.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an RH vacuum degasser immersion tube showing an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of a shaped refractory taken along the line A-A in FIG. Figures 3 and 4 are R
FIG. 3 is a cross-sectional view illustrating the H vacuum degassing device; FIG. 3 shows an upward flow pattern according to the present invention, and FIG. 4 shows the same upward flow pattern using a conventional dip tube. FIG. 5 is a cross-sectional view taken along line B-B in FIG. 4. In the figure, l is a vacuum tank, 2 is a reflux tube, 3 is an immersion tube, and 5
is a gas blowing hole (passage).

Claims (9)

[Claims] (1) An immersion tube having a gas blowing hole opened on the inner surface of the tube, the hole being formed so that the direction of gas blowing from the hole into the tube is shifted from the center of the tube. A gas-blown dip tube. (2) The immersion tube according to claim 1, wherein a plurality of gas blowing holes are provided, and the extending directions of the plurality of holes do not coincide with each other at the center of the tube. (3) At least three or more holes are provided at approximately equal intervals, and the extension direction of these holes is formed to be shifted in the direction of the same side of the center as viewed from the hole. Dip tube as described. (4) A gas blowing hole is formed so that the blowing gas forms a spiral flow within the pipe.
The dip tube according to any one of paragraph 3. (5) The immersion tube according to claim 4, wherein the blowing hole is formed so that the spiral flow produces a left-handed rotating flow when viewed from above within the tube. (6) The deviation of the direction of the gas injection hole from the center of the pipe,
When a small circle is drawn inside the pipe with the extension direction of the hole as the tangent line,
The immersion tube according to any one of claims 1 to 5, wherein the blow hole is formed so that the diameter of the small circle is 5 to 50% of the inner diameter of the tube. (7) The immersion tube according to claim 6, wherein the blow hole is formed so that the diameter of the small circle is 10 to 30% of the inner diameter of the tube. (8) Gas is blown into the immersion tube in a direction slightly offset from the center of the tube through a blow hole provided on the peripheral wall of the immersion tube, so that the gas is blown into the gas tube to form a swirling flow. A method of blowing gas into the immersion pipe. (9) When a small circle is drawn in the pipe with the gas blowing direction as a tangent line, the diameter of the small circle is 5 to 50% of the inner diameter of the pipe. The blowing method described in Scope Item 8.