US3655176A

US3655176A - Closure devices for metallurgical and like vessels

Info

Publication number: US3655176A
Application number: US12943A
Authority: US
Inventors: Hans-Joachim Winkler; Hans Richard Fehling
Original assignee: Stoecker and Kunz GmbH
Current assignee: Stoecker and Kunz GmbH
Priority date: 1969-02-27
Filing date: 1970-02-20
Publication date: 1972-04-11
Anticipated expiration: 1989-04-11
Also published as: LU60413A1; GB1277491A; NL7002648A; FR2032459A1; BE746493A; AT318158B; DE2008667A1; SE365143B

Abstract

A vessel for containing and discharging molten material is provided with a gas-tight annex chamber offset from but communicating with the interior of the vessel, the bottom of which chamber is not substantially above the bottom of the vessel interior and is provided with a discharge orifice for the downward discharge of the molten material, said orifice being opened and closed by a vertically-movable stopper rod which extends down through the roof of the chamber. The roof of the chamber is formed with a pocket through which the rod extends and in which gas is trapped and pressurized as the level of the molten material in the chamber rises as the latter fills from the vessel. The gas pressure in the pocket may be transmitted to a gauge or may be used for automatic adjustment of the height of the rod to obtain a constant discharge rate through the discharge orifice.

Description

United States Patent Winkler et al. [451 Apr. 11, 1972 [54] CLOSURE DEVICES FOR 3,028,874 4/1962 Burkett ..266/38 x METALLURGICAL AND LIKE VESSELS 31 33;; {32 g 4 te X [72] Inventors: Hans-Joachim Winkler, Krenfeld-Uerdin- 3 206 301 9/1965 21; 2, X

g y; Hans Richard g Swltzerland Primary Examiner-Gerald A. Dost 73 Assignee: Stoecker & Kunz GmbH, Krenfeld-Linn, AtwmeyBrumbaush, r v D n and Raymond Germany 5 7 ABSTRACT [22] Filed: Feb. 20, 1970 i 1 If d d h l l vesse or containing an isc argmg mo ten materia is pro- [21] Appl. No.. 12,943 vided with a gas-tight annex chamber offset from but communicating with the interior of the vessel, the bottom of which 30 Foreign Application p i m chamber is not substantially above the bottom of the vessel interior and is provided with a discharge orifice for the Feb. 27, [969 Great Britain 10,57 1/69 downward discharge of the molten material, i orifice being opened and closed by a vertically-movable stopper rod which [if] }J.S.2|l ..266/38, 164/2822] extends down through the roof of the chamber The roof of [58] Fntid B37 6 the chamber is formed with a pocket through which the rod 1 o arc 1 2 extends and in which gas is trapped and pressurized as the level of the molten material in the chamber rises as the latter fills from the vessel. The gas pressure in the pocket maybe [56] References cued transmitted to a gauge or may be used for automatic adjustment'of the hei ht of the rod to obtain a constant dischar e UNITED STATES PATENTS g g 2 054 921 9/1936 B u n 266/3 V rate through the discharge orifice.

a e on 2,880,989 4/1959 Stauffer ..266/38 8 Claims, 5 Drawing Figures Patented A ril 11, 1972 X 3,655,176

3 Sheets-Sheet 2 Fig. 3

5 5; IE 4 gn/z Fig. 4

INVENTORS. HANS REINHARD FEHLING a HANS-JOACHIM WINKLER QZ AWz T their ATTORNEYS CLOSURE DEVICES FOR METALLURGICAL AND LIKE VESSELS CROSS-REFERENCE TO RELATED APPLICATIONS Reference is made to British Pat. application No. l057l/69 of 27th February, 1969 Stoecker and Kunz G. m. b. H, from which priority is claimed.

The invention relates to closure devices designed to open and close an aperture at the bottom of metallurgical vessels, and other vessels for containing and discharging molten material, (or melt) particularly casting ladles in the steel industry. In the following the expression ladle will include any metallurgical vessel for containing molten material.

For a very long time is has been the nonnal procedure to discharge molten metal from a ladle through an aperture at its bottom, which is opened and closed from inside the ladle by a stopper at the end of a vertically-movable refractory-clad rod extending down to the mouth of the aperture through the melt.

With the recent increase in the size of ladies to capacities of several hundred tons and the rise in casting temperature required by high alloy steels it has been increasingly difficult to apply the method described.

Even in the past the wear and tear on the refractory parts subjected to erosive attack by a rapid flow of steel and on the refractory cladding of the stopper rods was such that, for the sake of operational safety, these parts had to be replaced after each heat. This could only be done economically by using comparatively cheap refractory materials. With increasing ladle capacities (and heights), longer casting times and higher temperature, the margin of safety in using such stopper rods of necessarily-increased free length was steadily reduced.

One of the most dangerous aspects was reduced protection of the stopper rod at the surface of the melt where the refractory cladding material of the rod is exposed to attack of the high corrosive slag. The operational side of the resetting, loading and operating such long rods became equally unsatisfactory.

It is the object of the invention to overcome these difficulties.

The invention therefore provides a vessel for containing and discharging molten material, having a small gas-tight annex chamber offset from but communicating laterally with the interior of the vessel, the bottom of which chamber is not substantially above the bottom of the vessel interior and is provided with a discharge orifice for the discharge of the molten material, and having a refractory, or refractory-clad, stopper rod extending down through the chamber and movable in a substantially vertical direction between a lower closed position in which its lower end closes the orifice and an upper open position in which its lower end is spaced from the orifice. The expression gas-tight" means that the chamber is gastight except for its communication with the interior of the vessel and its orifice for discharging the molten material.

In a specific construction the rod extends slidably through the roof of the chamber so as to be capable of being raised and lowered by means external to the chamber, and is provided with a gas-tight gland. The latter may comprise a bellows into which the upper end of the rod extends, the bellows being sealed to the rod and to the roof of the chamber.

The vessel may have, above the annex chamber, a gas-tight enclosure into which the upper end of the stopper rod extends, and a connection for supplying gas into the interior of said enclosure from an external source.

In order that the invention may be better understood, reference will now be made to the accompanying drawings, in which:

FIG. 1 shows an embodiment of the invention in section;

FIG. 2 is a section taken on the line A-A in FIG. 1;

FIGS. 3 and 4 shows the application of the invention to a large casting ladle, FIG. 4 being a section taken on the line BB in FIG. 3,

FIG. 5 shows an alternative gas seal for the annex chamber according to the invention.

Referring to FIGS. 1 and 2 the shell 1 of the metallurgical vessel 2 has a refractory lining 3. There is a small gas-tight annex chamber 4 offset from but communicating laterally with the interior of vessel 2 through a duct or port 6, said chamber having a gas-tight steel shell 5 with a refractory lining 3a. In the bottom of the chamber 4, which is substantially level with the bottom of the vessel interior, there is a replaceable refractory teeming nozzle 7 of known type providing a discharge orifice 16. This nozzle is exchangeable and removable from below.

Preferably the bottom and side steel shells (5a, 5b respectively) of the chamber are permanently welded or otherwise fixed to the main vessel, while the top 5c is formed by a removable plate secured to the shell. This is convenient for ex tracting the whole stopper rod assembly and mechanism particularly for the purpose of easy maintenance work on the refractory parts.

The chamber 4 has a very low ceiling 6a which is perforated above the noule 7 by a tubular hole 8 which acts as a guide for the refractory stopper rod 9. The hole 'is widened at its lower end, forming an annular recess or pocket 10 at the top of the annex chamber 4.

At its upper end the hole is closed by a gas-tight steel bellows 11 fixed to the shell 5 of the chamber. The rod 9 is attached to the bellows by means of the gas-tight sleeve 12 at the inside of which it is secured by any suitable method e.g. by a screw thread. The bellows 11 is capable of a vertical stroke corresponding to the distance between the closed and open position of the stopper rod 9. For this purpose the bellows is connected to a mechanical or hydraulic actuator 13 fixed to the shell 5 of the chamber. Such an actuator has the advantage of allowing the operation of the stopper rod by remote control. If desired, such as actuator may be replaced by any other suitable device, as for example the conventional mechanical lever.

The operation of the device is as follows.

When the vessel 2 is charged with metal the stopper 9 is in the closed position in which it rests on and seals the orifice 16, so that the chamber 4 fills rapidly with metal. When the level of the metal in the vessel 2 is rising above the ceiling 6a of the chamber a volume of gas contained in the chamber above the surface of the metal is trapped, as it is surrounded by a gastight enclosure formed by the shell 5 and the bellows 11. As the level of the metal in the vessel 2 continues to rise this trapped volume is compressed to a pressure corresponding to the hydrostatic head of the liquid metal so that the level of the metal rises within the annular recess 10. But provided the volume of the clearance between the rod 9 and the hole 8 is only a fraction of the volume of the annular recess, a rise of metal within this clearance, which would make the rod inoperable through freezing of the metal sliver in the clearance, will not occur.

It will therefore, be appreciated that only a very short part of the rod 9 at its lower end will be in contact with the molten steel while the major part of the rod remains protected and relatively cool. If by accident the stopper at the end of the rod became detached it would be trapped in the chamber and could not escape by rising at increasing velocity through the molten material of the ladle.

To ensure that the trapped gas volume cannot escape, it is desirable to provide the upper part of the hole with a sleeve 14 of refractory steel. It is desirable to provide the refractory lining of the chamber with the back-up insulating material 15 particularly above the ceiling of the chamber.

If desired the pocket or chamber could, at its upper end, be connected at 18 to a supply of argon or nitrogen in order to maintain a neutral atmosphere above the surface of the molten steel in the chamber. Such a supply would also provide additional safety in case of the development of a small gas leak which would otherwise allow the metal to rise in the hole 8.

The'development of the gas pressure inside the bellows 11 which correspond to the hydrostatic head of the melt further provides a convenient way of obtaining, by means of a pressure gauge, an accurate indication of the metal level in the vessel. This variable pressure control could therefore, be used for automatic adjustment of the position of the stopper 9, i.e. to raise the latter in order to maintain a constant flow rate while the metal level in vessel 2 descends.

This automatic link is particularly valuable in order to dose the stopper automatically as soon as the steel level descends below a certain level. This is important if it is desired to ensure that no slag enters the chamber 4 at the end of the discharge period.

FIGS. 3 and 4 illustrate the incorporation of the annex chamber according to the invention in a large casting ladle, which may as shown in FIG. 4, have a twin set of stopper rods 9a, 9b and teeming nozzles. It will be appreciated from FIG. 3 how much shorter the stopper rod is compared with the conventional ladle in which the rod extends inevitably over the full height of the latter.

In FIG. 4, two annex chambers 4a, 4b are shown, each with its stopper rod 9a, or 9b and its teeming nozzle. However, it is within the scope of the invention to provide two stopper rods, with their teeming nozzles, in a single annex chamber.

FIG. shows an alternative to the bellows 11 in FIG. 1. In

this case the bellows are replaced by a rigid gas-tight box 19 having a gland 20 through which an extension of the stopper rod 9 passes, leaving only enough clearance for sliding. The

box is connected through pipe 21 and valve 22 to a supply of a suitable gas. It will be appreciated that, if the gas is supplied at a pressure equally or preferably slightly exceeding the hydrostatic head of the molten material, the latter will be prevented from rising upwards through the annular clearance between the stopper rod and its guide in the ceiling of the chamber. The actuation of the stopper rod does not differ from that described in relation to FIGS. 1 and 2.

The refractory material particularly of the stopper and the nozzle must be suitably selected having regard to the nature of the molten material and the temperatures encountered. If for economic and operational reasons it is preferred to replace these parts after each heat, the relatively cheap conventional refractories for this purpose may be used. If these parts are to withstand many heats they should be highly resistant to the highly resistant to the erosive action of the melt. For steel, the best material so far available among the normal refractory range is a refractory containing over 80 A1 0 For even higher resistance cermet materials are available.

Although in the accompanying drawings the annex chamber and its walls are shown as integral inseparate parts of the vessel I, the same may be constructed so as to be detachably attached to the container.

What is claim is:

1. In a vessel for containing and discharging molten material, having a gas-tight annex chamber offset from but communicating laterally with the interior of the vessel, the bottom of which chamber being not substantially above the bottom of the vessel interior and being provided with a discharge orifice for the downward discharge of the molten material, and also having a refractory, or refractory-clad, stopper rod extending down through the chamber and movable in a substantially vertical direction between a lower closed position in which its lower end closes the orifice and an upper open position in which its lower end is spaced from the orifice, the rod extending slidably through the roof of the chamber so as to be capable of being raised and lowered by means external to the chamber and being provided with a gas-tight gland, the improvement comprising an enlarged recess formed in the roof of the chamber surrounding the stopper rod, the volume of the recess t eing substantially greater than the volume enclosed by the gland above the recess and communicating therewith, whereby gas trapped above the level of molten material in the annex chamber is compressed primarily within the enlarged recess as the level of vessel according to claim 1 wherein the gland comprises a bellows into which the upper end of the rod extends, said bellows being sealed to the rod and to the roof of the chamber.

2. A vessel according to claim I, wherein the gland comprises a bellows into which the upper end of the rod extends, said bellows being sealed to the rod to the roof of the chamber 7w I 3. A vessel according to claim 1, wherein the pressure of the trapped gas is applied to a pressure gauge.

4. A vessel according to claim 1, wherein the pressure of the trapped gas is employed to adjust the height of the stopper rod as the level of the molten material in the pocket falls during discharge through the discharge orifice.

5. A vessel according to claim 1, wherein the discharge orifice is provided in a refractory nozzle which is replaceable from below the vessel.

6. A vessel according to claim 1, having, above the annex chamber, a gas-tight enclosure into which the upper end of the stopper rod extends, and a connection for supplying gas to the interior of said enclosure from an external source.

7. A vessel according to claim 1, including a second gastight annex chamber, and a second stopper rod within the second annex chamber.

8. A vessel according to claim 1, having the annex chamber detachably attached to the vessel.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTKON P t t NO, 3,655,176 Dated April i]., 1.972

Hans-Joachim Winkler et al Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

First P g Item .[72], "Hans Richard Fehling" should be Hans Reinhard Fehling Col. 2, line 34, "as' should read an Col; 3', line 5, "dose" should read close Col. 3, lines 39 and 40, "highly resistant to the" has been duplicated and should appear once only.

Col. 4, lines 21-23, "vessel according to claim 1 wherein the gland comprises a bellows into which the upper end of the rod extends, said bellows being sealed to the rod and to" should read:

- molten material rises in the vessel, thereby preventing molten material from reaching the clearance space between the stopper rod and Col. 4, line 27, after "rod" insert and Signed and sealed this 26th day of December 1972.

(SEAL) Attest:

5 EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Patent

Claims

1. In a vessel for containing and discharging molten material, having a gas-tight annex chamber offset from but communicating laterally with the interior of the vessel, the bottom of which chamber being not substantially above the bottom of the vessel interior and being provided with a discharge orifice for the downward discharge of the molten material, and also having a refractory, or refractory-clad, stopper rod extending down through the chamber and movable in a substantially vertical direction between a lower closed position in which its lower end closes the orifice and an upper open position in which its lower end is spaced from the orifice, the rod extending slidably through the roof of the chamber so as to be capable of being raised and lowered by means external to the chamber and being provided with a gas-tight gland, the improvement comprising an enlarged recess formed in the roof of the chamber surrounding the stopper rod, the volume of the recess being substantially greater than the volume enclosed by the gland above the recess and communicating therewith, whereby gas trapped above the level of molten material in the annex chamber is compressed primarily within the enlarged recess as the level of vessel according to claim 1 wherein the gland comprises a bellows into which the upper end of the rod extends, said bellows being sealed to the rod and to the roof of the chamber.

2. A VESSEL ACCORDING TO CLAIM -, WHEREIN THE GLAND COMPRISES A BELLOWS INTO WHICH THE UPPER END OF THE ROD EXTENDS, SAID BELLOWS BEING SEALED TO THE ROD TO THE ROOF OF THE CHAMBER.

3. A vessel according to claim 1, wherein the pressure of the trapped gas is applied to a pressure gauge.

7. A vessel according to claim 1, including a second gas-tight annex chamber, and a second stopper rod within the second annex chamber.