WO2008054243A1

WO2008054243A1 - Method for vacuum refining steel in a ladle, device (variants) and socket for carrying out said method

Info

Publication number: WO2008054243A1
Application number: PCT/RU2007/000530
Authority: WO
Inventors: Ivan Ivanovich Karpukhin; Andrey Vladimirovich Lukyanov; Aleksandr Vladimirovich Pogozhev; Aleksandr Anatolievich Nemtinov; Albert Pavlovich Schegolev; Alexandr Mikhailovich Sorokin
Original assignee: Zakrytoe Aktsionernnoe Obschestvo 'prochnost'; Otkrytoe Aktsionernoe Obschestvo 'severstal'
Priority date: 2006-10-05
Filing date: 2007-10-03
Publication date: 2008-05-08
Also published as: RU2324744C1

Abstract

The invention relates to metallurgy, in particular to a method and a device for ladle processing of molten metal. The inventive method consists in supplying, during the entire refining process, an agitating gas to a ladle (4), which contains a molten steel (5) and is arranged in a vacuum chamber (1), in increasing vacuum in such a way that an equal vacuum level is provided at every time above the entire surface of steel in the ladle, in dividing the surface of rimming steel into central and peripheral areas and in forming a vacuum degree above the central area in such a way that it is greater than the vacuum degree above the peripheral area,afterwards, in continuously increasing the vacuum degree above said areas in such a way that the specified difference in vacuum therebetween is maintained, in combining the above-mentioned areas and continuously increasing the vacuum degree above the entire surface of steel in the ladle in such a way that a specified level is attained. Said method is carried out by means of a device which is used for carrying out a steel vacuum refining in a ladle and comprises a socket (6) which is embodied in such a way that it is immersible into a melted steel. Said invention makes it possible to reduce the length of a vacuum refining process and to increase the amount of steel contained in the ladle during the vacuum refining thereof.

Description

The method of vacuum refining of steel in a ladle, device (options) and pipe for its implementation

The invention relates to the field of metallurgy, in particular to methods and equipment for out-of-furnace treatment of liquid metal, and can be used in the production of high quality steel.

Currently, various methods of out-of-furnace treatment of liquid metal have become widespread at metallurgical plants, including various methods of vacuum refining, the essence of which is the removal of impurities, mainly carbon and oxygen, contained in the liquid metal under the influence of rarefaction from steel obtained in the converter in bound (carbon) or in dissolved (oxygen, hydrogen, nitrogen) state. The most common method of evacuation is the method of vacuum refining liquid steel in a ladle, which involves placing a ladle with liquid steel in a vacuum chamber, sealing the chamber and creating a vacuum therein over the entire surface of the steel (SU 1675371 Al, IPC C21C 7/10, 09/07/91 , RU 2171298 C2, IPC C21C 7/10, 07.27.2001). In order to intensify the process of removing impurities, at the same time as creating a vacuum above the surface of the steel, an inert gas, mainly argon, is blown through the steel. The method of vacuum refining in a ladle has several advantages, firstly, it is the simplest known method of vacuum refining, and secondly, when it is vacuumized, the entire surface of the steel placed in the ladle is evacuated, so the steel is processed more evenly, which ensures a guaranteed and reproducible result, i.e. guaranteed quality of steel. In addition to the above, vacuum refining of steel in the ladle allows for deep desulfurization

SUBSTITUTE SHEET (RULE 26) steel due to intense mass transfer between slag and steel on its surface. However, the creation of rarefaction above the surface of the steel leads to its boiling, the formation of splashes and overflow of steel through the side of the bucket. Sprays and overflows of steel across the side of the bucket contaminate the vacuum chamber and lead to steel losses. In practice, to eliminate these drawbacks, steel is poured into the bucket with underfilling, leaving the bucket side free in height by about 1200-1450 mm (the free side is determined experimentally and is determined by the level at which the gas-slag emulsion rises when the steel boils, as well as the nature of the process refining, the content of impurities in the steel and the intensity of the argon purge). Underfilling the metal into the ladle reduces the productivity of the metal production process as a whole, since the volume of the ladle must correspond to the volume of steel smelted during one heat in one converter. In the converter plants built earlier, the technological process did not provide for vacuum refining of liquid steel in the ladle, therefore, the volume of the bucket corresponded to the volume of the converter taking into account the minimum free side of the bucket, which ensures its safe transportation in the production environment. If it is necessary to use liquid steel evacuation in such plants, it is necessary to produce melts of reduced mass in the ladle, which leads to a decrease in productivity and an increase in the cost of steel. During the construction of a new production involving the use of vacuum refining plants, in order to use the converter's capabilities in full, it is necessary to significantly increase the dimensions of the bucket and, accordingly, the dimensions of all mechanisms and the building as a whole, which leads to a significant increase in capital costs.

There are known constructions in which the ladle is covered with various covers during the vacuum refining process, which protect the vacuum chamber from steel splashing, for example, as shown in FIG. 1 in patent RU 2171298, but such covers cannot prevent overflows

SUBSTITUTE SHEET (RULE 26) steel overboard, since during operation on the sides formed overlaps and the lid ceases to fit snugly against the upper flange of the bucket.

Known vacuum batch refining methods in which steel is processed by immersing a nozzle (immersion chamber) in molten steel, the necessary vacuum being created only inside the nozzle, and the surface of the steel limited by the perimeter of the nozzle is exposed to vacuum, and refining occurs in portions with sequential set and discharge vacuum (SU 954439, MIJ C21C 7/10, 08.30.82, RU 2173715 C2, IPC C21C 7/10, 09.20.2001).

Circulating vacuum refining methods are also known in which the vacuum refining unit comprises two nozzles, one of which melts the steel in a vacuum chamber, undergoes a vacuum, and then flows back into the ladle (DE 19923205 Cl, IPC C21C 7 / 10, 11/30/2000). The advantage of these methods is that both processes allow vacuum refining in a bucket with a minimum free board, have a high speed, and steel sprays do not splash out. The disadvantage of these methods is the unevenness of the process throughout the entire volume of the ladle, therefore, the moment of completion of the vacuum refining process is determined only by chemical analysis of steel samples and in each case, to obtain steel with guaranteed properties, the number of vacuuming cycles should be determined from the results of the study.

A known method of vacuum refining, in which the vacuum cap is connected directly to the upper flange of the bucket with liquid steel (WO 01/86007, IPC C21C 7/10, 11/15/2001). The vacuum lid is equipped with a cylindrical protrusion located above the level of the upper flange of the bucket, which plays the role of a protective shield against splash of slag and steel in the process of evacuation. The disadvantage of this method is that it is very difficult to provide a vacuum-tight connection between the vacuum

SUBSTITUTE SHEET (RULE 26) the lid and the bucket flange, since the latter always has slag and steel outgrowths resulting from spray both during the pouring of steel into the ladle and during the processing of steel under vacuum.

The closest analogue of the present invention is a method of vacuum refining molten steel in a ladle, which involves pouring molten steel into a ladle, placing the ladle in a vacuum chamber, dividing the steel surface into central and peripheral zones, and creating different rarefaction steel surfaces above these zones (WO 90/10087, IPC C21C 7/10, September 7, 90). The separation of the steel surface in the ladle into the central and peripheral zones is ensured by immersion in the molten (liquid) steel end of the nozzle located directly on the lid of the vacuum chamber. In this case, the separation of the steel surface into these two zones is provided throughout the entire process of vacuum refining. Steel processing in the central and peripheral zones is carried out at different levels of pressure (rarefaction), and during the refining process the difference in rarefaction is constantly maintained: a large degree of rarefaction in the central zone, a lower degree of rarefaction in the peripheral zone.

This method allows vacuum refining of liquid steel with a lower height of the free side of the bucket without overflow of liquid steel overboard. However, this leads to a complication of the process of vacuum refining, an increase in its duration and a decrease in the quality of refining, since in this case there is no mass transfer between the slag located on the surface of the steel in different zones and liquid steel.

An object of the present invention is to increase the volume of steel processed in the ladle during the vacuum refining process, to obtain steel with guaranteed properties as a result of processing by intensively mixing steel throughout the volume and mass transfer between slag and liquid steel throughout the volume, and to reduce the duration of the vacuum refining process.

SUBSTITUTE SHEET (RULE 26) . The problem is solved in a method of vacuum refining steel, which involves placing a ladle with liquid steel in a vacuum chamber and dividing the steel surface into central and peripheral zones with the possibility of creating zones of varying degrees of vacuum, in which according to the invention a mixing gas is supplied to the ladle with liquid steel for the entire refining process, and in the first stage of the refining process, the vacuum is increased with the same intensity with the same vacuum in each m a moment of time over the entire surface of the steel in the ladle, at the second stage during the beginning of intense boiling of steel, determined by the formation of a gas-slag-metal emulsion on its surface, the surface of the boiling steel is divided into the central and peripheral zones, while a greater degree of rarefaction is created over the central zone, than above the peripheral zone, after which they continue to increase the degree of rarefaction over these zones with the provision of a given difference in the vacuum between them, in the third stage with a decrease in the intensity of steel singing, these zones are combined again and continue to increase the degree of rarefaction over the entire surface of the steel to a predetermined level, after which the steel is held at the specified degree of depression for a predetermined time, the level of steel refinement in the ladle is controlled in the fourth stage, and if it exceeds a predetermined value, These process steps are repeated until a predetermined level of steel refining is obtained.

Mixing gas is supplied to the ladle with liquid steel from the bottom of the ladle so that gas bubbles come to the surface of the central and peripheral zones in certain areas that occupy part of their surface. At the same time, ascending flows of liquid steel are organized in the areas of exit of bubbles on the surface of the central and peripheral zones, and in areas free of gas bubbles, descending flows of liquid steel are formed due to the above, intensive mixing of liquid steel in the ladle takes place.

SUBSTITUTE SHEET (RULE 26) The surface of the boiling steel is divided into the central and peripheral zones by means of a pipe by immersing the end of the lower end of the pipe in boiling steel to a depth of h _pp , and the union of these zones is carried out by raising the pipe to form a gap Δ between the end of the lower end of the pipe and the surface of the boiling steel in the bucket.

The separation of the surface of boiling steel into the central and peripheral zones is also carried out by lifting the bucket with boiling steel relative to the stationary pipe until the end of the lower end of the pipe is immersed in boiling steel to a depth of h _m , and the union of these zones is carried out by lowering the bucket with boiling steel until a gap Δ between the end of the lower end of the stationary pipe and the surface of the boiling steel in the bucket.

The separation of the surface of boiling steel into the central and peripheral zones is also carried out by raising the surface level of boiling steel in the bucket relative to the pipe until the end of the lower end of the pipe is immersed in boiling steel to a depth of h _pp , and the union of these zones is carried out by lowering the surface level of boiling steel in the bucket until the gap Δ between the end face of the lower end of the pipe and the surface of the boiling steel in the ladle.

The time of the beginning of intense boiling of steel in the ladle is determined by controlling the rise of the gas and slag metal emulsion and its achievement of a predetermined limit level of h _{ep max} , and the time of decrease of the intense boiling of steel is determined by lowering the level of gas and slag metal emulsion below the specified limit level of h _{ep max} -

The maximum level of gas-slag emulsion rise is set either relative to the end of the bead side, or relative to the initial level of the surface of liquid steel in the bucket.

At the second stage of the process, the end of the lower end of the pipe is immersed in boiling steel at a level of h _ep gas-slag metal

SUBSTITUTE SHEET (RULE 26) emulsions in the peripheral zone exceeding by 0–200 mm the level of the end face of the lower end of the nozzle, and at the third stage of the process, when these zones are combined, they provide a gap Δ between the surface of the boiling steel and the end of the lower end of the nozzle in the range:

0 <Δ <H _c6 - 200 mm, (1) where H _cb is the height of the free side of the bucket.

The predetermined difference in the degree of rarefaction over the central and peripheral zones of the surface of boiling steel is supported by ensuring the flow of gas-slag emulsion from the peripheral to the central zone around the end of the lower end of the pipe.

The predetermined difference in the degree of rarefaction over the central and peripheral zones of the surface of boiling steel is also provided by pumping gas from the cavity of the vacuum chamber in communication with the peripheral zone of the steel surface in the ladle, and / or by supplying an inert gas, such as argon, to the specified cavity.

Due to the difference in rarefaction in the central and peripheral zones of the ladle, the present invention allows to increase the volume of steel processed in the ladle during vacuum refining, to obtain steel with guaranteed properties throughout the volume by 15 ÷ 25% and to reduce the duration of the vacuum refining process by 3 ÷ 15%.

The inventive method of vacuum refining steel in a ladle is implemented by means of a device for vacuum refining steel in a ladle, including a vacuum chamber with a lid, a stand for installing a ladle with molten steel and a nozzle configured to immerse the lower end in molten steel, which according to the invention is provided with a screen, the central part of which a pipe is installed, and the outer edge of the screen is made with the possibility of tight placement between the upper end of the vacuum chamber and the flange of its cover, and the system Aci molten steel stirring gas, the inner surface krysh-

SUBSTITUTE SHEET (RULE 26) The ki, the upper surface of the screen and the inner surface of the nozzle form a cavity communicating with the vacuum pump and the central zone of the bucket, and the inner surface of the vacuum chamber, the lower surface of the screen, the outer surface of the bucket, and the outer surface of the nozzle form a cavity communicating with the peripheral zone of the bucket.

The mixing gas supply system to liquid steel can be made in the form of gas supply paths and porous plugs installed in the bottom of the bucket at a distance from the bucket axis, equal to: l _pp = 0 _÷ 0.35D _k , (2) where l _pp is the distance from center of the plug to the axis of the bucket, mm,

D _to - the inner diameter of the bucket in the upper part, mm The outer diameter of the lower end of the pipe is selected from the ratio: D _to - Yu0 ≥ D _np ≥ 21 _ppmax + d _pp + 2δ _p , (3) where D _to is the inner diameter of the bucket in the upper part, mm, D _np is the outer diameter of the lower end of the pipe , hr _max - the maximum distance from the center of the tube to the axis of the bucket, mm, d _pp - diameter of the tube, mm, δ _p - wall thickness of the lower end of the pipe, mm. The upper end of the nozzle may be equipped with an inspection hole located in its central part and having dimensions that provide video surveillance of the surface of liquid steel in the central zone of the bucket and the introduction of technological additives in the form of solid, powder, and gaseous materials into liquid steel.

On the lid of the vacuum chamber, video surveillance tools for the central and peripheral zones of the bucket can be installed, and pressure sensors for measuring the degree of depression above the indicated zones are installed in the indicated cavities communicating with the central and peripheral zones of the bucket.

SUBSTITUTE SHEET (RULE 26) The inner surface of the lower end of the pipe can be made in the form of a conical surface, the base of which coincides with the end of the pipe or in the form of a surface of revolution, the generatrix of which is a line of constant or variable curvature.

The inner and outer surfaces of the lower end of the nozzle can be made in the form of two mutually intersecting conical surfaces, while the base of the inner conical surface coincides with the lower end of the nozzle, the base of the outer conical surface is equal to the outer diameter of the lower end of the nozzle, and its top is directed towards the end of the lower end of the nozzle .

The inner and outer surfaces of the lower end of the nozzle can be made in the form of surfaces of revolution, the generators of which are lines of constant or variable curvature.

The pipe can be installed with the possibility of vertical movement relative to the screen, while the device is equipped with a vertical movement mechanism located on the screen or on the cover of the vacuum chamber.

The bucket stand can be equipped with a vertical movement mechanism.

The cover of the vacuum chamber is provided with a flange, while the screen and said flange are interconnected by means of locking elements.

The screen in the second embodiment is equipped with an annular protrusion, the inner surface of which together with the outer surface of the lower end of the nozzle form an annular cavity around the latter, while the inner diameter of the protrusion is selected from the ratio:

D _VK - 2δ _in > D _in ≥ D _{to 5} (4) where D _{VK is the} internal diameter of the lid of the vacuum chamber, δ _in is the wall thickness of the protrusion, D _in is the internal diameter of the protrusion, / L is the inner diameter of the bucket in the upper part,

SUBSTITUTE SHEET (RULE 26) and the height of the cavity formed by the protrusion is determined by the formula:

H _in = H _p -h _fk - K, (5) where H _in is the height of the cavity formed by the protrusion, h _fK is the distance from the vacuum chamber flange to the end of the bucket side, h _p is the distance from the end of the pipe to the end of the bucket side.

The device is equipped with locking and regulating equipment, providing the ability to connect these cavities with a vacuum pump and gas supply paths and / or locking and regulating equipment, providing the ability to connect these cavities with each other.

In a second embodiment, a device for vacuum refining steel in a ladle includes a vacuum chamber with a lid, a stand for installing a ladle with molten steel and a nozzle connected to the lid and configured to immerse the lower end in molten steel, and the nozzle is provided with a flange made for tight mating with the cover of the vacuum chamber, while the upper part of the nozzle is closed, located above the cover of the vacuum chamber outside its internal space and connected to the vacuum pump, and the lower part l pipe located under the cover inside the vacuum chamber.

In a third embodiment, a device for vacuum refining steel in a ladle includes a vacuum chamber with a lid, a stand for installing a ladle with liquid steel and a nozzle connected to the lid and configured to immerse the lower end in molten steel, the nozzle being provided with a screen made in the form of a flange, the lower edge of which is made with the possibility of tight pairing with the upper edge of the bucket, and is connected to the lid with the possibility of mutual vertical movement.

The nozzle may be connected to the cap via flexible connections.

The solution to this problem is also provided by means of a nozzle of a device for evacuating liquid metal in a ladle located in a vacuum chamber interacting with liquid metal, which

SUBSTITUTE SHEET (RULE 26) according to the invention is equipped with a screen mounted above the ladle with molten metal, the edges of which are made with the possibility of tight placement between the end of the wall of the vacuum chamber and its cover, while the pipe is placed perpendicular to the screen and is rigidly connected with it. The pipe may be made in the form of a cylinder and placed in the center of the screen.

The screen is made in the form of a metal ring-shaped plate, the perimeter of which corresponds to the perimeter of the vacuum chamber, and a lining is placed on the surface of the plate facing the liquid metal, which can be made of concrete and connected to the metal ring-shaped plate by means of anchors.

In the first embodiment, the pipe includes a metal cylinder rigidly connected to a metal annular vault plate, and a lining placed on the inner surface of the cylinder and on the outer surface of the lower part of the cylinder. In this case, the height of the lining on the lower part of the outer surface of the cylinder is limited by the lower surface of the screen (lining).

The lining of the nozzle can be made of concrete and connected to the metal cylinder by means of anchors, moreover, the lining of the lower part of the surface of the metal cylinder can be integral with the lining of the screen, and the upper part of the lining of the inner surface of the metal cylinder can be made of brick.

In the second embodiment, the pipe includes a metal cylinder rigidly connected to a metal annular arch plate, a lining placed on the inner surface of the cylinder and on the lower part of its outer surface, and a cylindrical element made of reinforced concrete mounted on the end of the metal cylinder with the possibility of dismantling.

The nozzle is equipped with an annular cover installed by means of a guide on its upper end.

SUBSTITUTE SHEET (RULE 26) The guide can be made in the form of a metal ring with a bead along the outer edge, while the inner diameter of the ring is equal to the inner diameter of the nozzle, the board protrudes beyond it, forming a protrusion, and the guide is rigidly connected to the metal cylinder.

The cover can be made in the form of a ring of concrete or it contains an upper part made in the form of a metal ring installed in the guide, and a lower part made of concrete, connected to the upper part by means of anchors and adjacent to the inner surface of the metal cylinder, while the lining the inner surface of the metal cylinder does not reach the upper end of the cylinder by an amount equal to the thickness of the lower part of the cover.

The nozzle contains cooling means located on the outer surface of the screen or on the outer surface of the nozzle located above the screen, and made in the form of channels.

The nozzle is equipped with trunnions located on the edge of the screen for installation on a bucket in a vacuum chamber and removal.

The pipe may be connected to the annular plate of the screen by means of stiffeners located radially and adjacent to the upper part of the outer surface of the metal cylinder and the outer surface of the metal annular plate of the screen.

The inner surface of the lower end of the pipe may be made as described above.

The nozzle made according to the present invention allows for the evacuation of molten metal, in particular steel, in a vacuum installation without overflows with maximum filling of the bucket, while the height of the free side is limited only by the conditions of transportation of the bucket. The use of this device is possible in existing industries with a slight refinement of the vacuum chamber.

The invention in terms of the method, device and pipe is illustrated by examples of specific implementations of variants of the device and pipe

SUBSTITUTE SHEET (RULE 26) with reference to the accompanying drawings, in which the following is schematically shown.

FIG. 1 - a device for the vacuum refining of steel in a ladle, made according to the present invention, the first option, General view, section.

FIG. 2 is a section A-A of FIG. one.

FIG. 3 - the specified device, in which the pipe and the screen are a collapsible design, General view, section.

FIG. 4 - the specified device with a mechanism for the vertical movement of the pipe, placed on the screen, General view, section.

FIG. 5 - the specified device with a mechanism for the vertical movement of the pipe located on the lid of the vacuum chamber, General view, section.

FIG. 6 - device, the second option, General view, section.

FIG. 7 - the same, with locking and regulating equipment.

FIG. 8 - the same, with the mechanism of vertical movement of the pipe.

FIG. 9 - the same, with the mechanism of vertical movement of the bucket.

FIG. 10 is a fragment I of FIG. 3, increased.

FIG. 11 is the same flow diagram.

FIG. 12 is a fragment II of FIG. four.

FIG. 13 is a fragment III of FIG. four.

FIG. 14 - device, the third option, General view, section.

FIG. 15 ÷ 20 - forms of execution of the lower end of the pipe.

FIG. 21 - pipe made in the first embodiment with a cover in the form of a ring of concrete, General view, section.

FIG. 22 - the same, with a cover containing a metal ring.

FIG. 23 is a fragment of FIG. 2, increased.

FIG. 24 - pipe, top view of FIG. 2.

FIG. 25 - pipe made in the second embodiment, a General view,

^{pa3pe3 "SUBSTITUTE} SHEET (RULE 26) A device for vacuum refining steel in a ladle (Fig.

1-5) includes a vacuum chamber 1 with a cover 2, a stand 3 for installing a bucket 4 with molten steel 5 and a nozzle 6. The nozzle 6 is configured to immerse the lower end in molten steel 5. The device is equipped with a screen 7, in the central part of which there is a nozzle 6, and the outer edge of the screen 7 is made with the possibility of tight placement between the upper end of the vacuum chamber 1 and the flange 8 of the cover 2 by means of a tight connection (seal) 9. The pipe 6 is mounted vertically and may have a cylindrical or any other shape with a cross section, for example Emer as oval or polyhedron (not shown). In FIG. 1, 3, 5 it is shown that the pipe 6 and the screen 7 can be made both in the form of an integral structure, and in the form of a collapsible design. In the second case, the pipe 6 may be provided with a flange 10, which is connected to the screen 7 by means of a tight connection 11, or the pipe 6 and the screen 7 are connected by means of a tight connection 11 without a flange 10. The pipe 6 can be made through, in the form of a hollow cylinder (FIG. 1) or in the form of a cylinder with a partially closed upper end (Fig. 3-5), and the overlap of the upper end of the nozzle can be provided as a whole design, and a removable cover 12. The inner surface of the cover 2, the upper surface of the screen 7 and the inner surface the nozzle 6 form a cavity 13 in communication with a vacuum pump (not shown) and with the central zone 14 of the bucket 4. The inner surface of the vacuum chamber 2, the lower surface of the screen I _{1 the} outer surface of the bucket 4 and the outer surface of the nozzle 6 form a cavity 15 in communication with the peripheral zone 16 bucket 4.

The device is equipped with a feed system in liquid steel of a mixing gas, for example argon, containing gas supply ducts 17 and porous plugs 18 installed in the bottom of the bucket 4.

To determine the specific dimensions of the device indicated in the relations (l) - (5), the following initial data were accepted, correspondingly

SUBSTITUTE SHEET (RULE 26) meeting the production conditions on which experimental tests of this design were carried out, namely: D _k = 4150 mm, d _pp = 350 mm, δ _x = 300 mm, H _& = 5550 mm,

δ _th - 150 mm,

h _p = 500 mm.

Substituting the initial values in expression (2), we obtained a range of distances from the center of the cork to the axis of the bucket, in which the specific value l _pp , l _pp should be 0-1452.5 mm, while l _{pp max} = 1452.5 mm.

From relation (3), we determined the range of values within which the outer diameter D _{np of the} lower end of the nozzle should be 6. D _np ^~ 3450-4050 mm. At D _np more than 4050 mm, the gap between the inner wall of the bucket and the outer surface of the nozzle will be insufficient, which in the case of formation of accretions can lead to damage to the lining of the bucket when removing the extension after evacuation, and at D _np less than 3450 mm the volume of the internal cavity of the extension will be insufficient to ensure lack of overflow of metal overboard. In addition, when purging, a significant portion of the argon pop-up bubbles will fall on the end of the nozzle and the area between the outer wall of the nozzle and the inner wall of the bucket, which reduces the refining intensity. In this case, D _np is equal to 3530 mm.

The upper end of the pipe 6 is equipped with a viewing hole 19 located in its central part and having dimensions that provide both video surveillance of the surface of the molten steel 5 in the central zone of the ladle and the introduction of technological additives in the form of solid, powder, and gaseous materials into molten steel.

SUBSTITUTE SHEET (RULE 26) On the lid of the vacuum chamber 1 can be installed means 20 for monitoring the central and peripheral zones 14, 16 of the bucket 4, and in the cavities 13, 15 in communication with the central and peripheral zones 14, 16 of the bucket, pressure sensors 21 are installed to measure the degree of vacuum over the zones 14, 16.

The lower end of the nozzle 6 may have a different shape, as shown in FIG. 15 - 20. The inner surface of the lower end of the pipe 6 can be made in the form of a conical surface, the base of which coincides with the end of the pipe (Fig. 15). This shape of the lower end of the nozzle is preferred when the argon purge plugs are located close to the center of the bucket and / or the diameter of the nozzle has a diameter close to the inner diameter of the bucket and the end of the nozzle is far from the metal surface. The inner and outer surfaces of the lower end of the pipe 6 can be made in the form of two mutually intersecting conical surfaces (Fig. 16). In this case, the base of the inner conical surface coincides with the lower end of the nozzle 6, the base of the outer conical surface is equal to the outer diameter of the lower end of the nozzle (D _np ), and its top is directed to the end of the lower end of the nozzle 6. This shape of the lower end of the nozzle is preferred when the plugs are argon purges are located far from the center of the bucket and / or the diameter of the pipe is much smaller than the inner diameter of the bucket. The inner surface of the lower end of the pipe 6 and / or the inner and outer surfaces can be made in the form of a surface of revolution, the generatrix of which is a line of constant or variable curvature. The shape of the lower end of the nozzle made in the form of a surface of revolution on the inside (Fig. 17, 19) is preferable in the case when the plugs for argon purging are located close to the center of the bucket and / or the diameter of the nozzle has a diameter close to the inner diameter of the bucket and the end of the nozzle is located far from the surface of the metal. The shape of the lower end of the pipe made in the form of surfaces of revolution both from the inside and from the outside (Fig. 18,

SUBSTITUTE SHEET (RULE 26) 20) it is preferable in the case when the plugs for purging with argon are located far from the center of the bucket and / or the diameter of the pipe is much smaller than the inner diameter of the bucket.

The pipe 6 can be installed with the possibility of vertical movement relative to the screen 7, while the device is equipped with a mechanism 22 for the vertical movement of the pipe 6, placed on the screen 7 or on the cover 2 of the vacuum chamber 1 (Fig. 4, 5).

The stand 3 for installing the bucket 4 may be equipped with a mechanism 23 for the vertical movement of the bucket 4, as shown in FIG. 9. In both cases, any type of vertical movement mechanisms known to those skilled in the art can be used.

To ensure the joint lifting of the cover 2 and the shield 7, the flange 8 can be additionally connected to the outer edge of the shield 7 by means of locking elements 24, for example, a type of clamp, as shown in FIG. 12.

To ensure better capture of the spray generated during the boiling of steel 5 in the ladle 4, the screen 7 can be equipped with an annular protrusion 25, the inner surface of which together with the outer surface of the lower end of the pipe 6 form an annular cavity 26 around the pipe 6. The inner diameter D of _the protrusion is selected from relation (4):

7948-2x 150mm>£>_β> 4150 mm and height H _{in the} cavity formed by the projection is determined by the formula (5) and is equal to: H _a _n = H - h _fc - h _n, where H ₆ - the height of the cavity, formed by the protrusion, h _fc - the distance from the flange of the vacuum chamber to the end of the side of the bucket,

H _n - the height of the lower part of the pipe, h _p - the distance from the end of the pipe to the end of the side of the bucket. The device is equipped with shut-off and control valves 27, providing both the possibility of connecting the cavities 13, 15 with a vacuum pump

SUBSTITUTE SHEET (RULE 26) (not shown) and gas supply paths 16, and the possibility of connecting the cavities 13, 15 with each other, as shown in FIG. 4, 5. As shut-off and control valves 27, standard valves known to those skilled in the art can be used. The choice of specific models of fittings depends on the conditions of a particular production and the equipment used.

In the second embodiment, the device according to the present invention (Fig. 6-9) includes a vacuum chamber 1 with a cover 2, a stand 3 for installing a bucket 4 with liquid steel 5 and a pipe 6 connected to the cover 2 and configured to immerse the lower end in the liquid steel 5, while in contrast to the first embodiment, the nozzle 6 is equipped with a flange 8 made with the possibility of tight coupling by connecting 28 with the cover 2 of the vacuum chamber 1. The upper part of the pipe 6 is closed, located above the cover 2 of the vacuum chamber measures 1 outside its internal space and is connected to a vacuum pump (not shown), and the lower part of the nozzle 6 is located under the cover 2 inside the vacuum chamber 1. In this design, the nozzle 6 has a greater height compared to the nozzle 6 made according to the first embodiment, and can be equipped with a vertical movement mechanism 22 mounted on the cover 2 of the vacuum chamber 1.

In the third embodiment, the device (Fig. 14) also includes a vacuum chamber 1 with a cover 2, a stand 3 for installing a bucket 4 with liquid steel 5 and a pipe 6 connected to the cover 2 and configured to immerse the lower end in liquid steel 5, with this pipe 6 is provided with a screen 29 made in the form of a flange. The lower edge of the flange is sealed by means of a connection 30 with the end of the bead 4. The screen 29 is connected to the lid 2 with the possibility of mutual vertical movement by means of flexible connections 31. The screen 29 can be made in the form of a half of a torus with a cavity 32 open towards the bucket 4 to catch the spray of steel during boiling.

SUBSTITUTE SHEET (RULE 26) The constructions made according to the second and third options may contain video surveillance means 20 for the central and peripheral zones 14, 16 of the bucket 4, pressure sensors 21, mechanisms for vertical movement of the bucket 4 and shut-off and control valves 27. In all three embodiments, these elements are similar and are intended to perform similar functions. The geometric parameters of similar elements of the device in all three variants are determined in accordance with relations (l) - (5). In FIG. Figure 2 shows the region 33 of exit of gas bubbles from a liquid metal in the process of evacuation.

In FIG. 21-25 shows the design options of the pipe 6.

The pipe 6 is equipped with a screen 7, the edges of which are made with the possibility of tight placement between the end of the wall of the vacuum chamber 1 and its cover 2. The pipe 6 is placed perpendicular to the screen 7 and is rigidly connected with it. The pipe 6 can be made in the form of a cylinder and placed in the center of the screen 7.

The screen 7 is made in the form of a metal ring-shaped plate 34, the perimeter of which corresponds to the perimeter of the vacuum chamber 1. On the surface of the plate 34 facing the liquid metal, a lining 35 is placed, which can be made of refractory concrete and connected to the metal ring-shaped plate 34 by means of anchors 36.

In the first embodiment (Fig. 21-22), the pipe 6 includes a metal cylinder 37, rigidly connected to a metal ring-shaped plate 34 of the screen 7, and a lining 38 located on the inner surface of the cylinder 37, and on the outer surface of the lower part of the cylinder 37. In this if the height of the lining 38 on the outer surface of the lower part of the cylinder 37 is limited to the lower surface of the screen 7.

The lining 38 is made of concrete and is bonded to the metal cylinder 37 by means of anchors 39. The lining 38 of the lower surface of the cylinder 37 can be integral with the lining 35 of the shield 7, as shown in FIG. 22. The upper part of the lining 38 of the inner surface

SUBSTITUTE SHEET (RULE 26) The metal cylinder 37 may be made of refractory brick 40.

In the second embodiment (Fig. 25), the nozzle 6 includes a metal cylinder 37, rigidly connected with a metal annular plate 34, a lining 38 placed on the inner surface of the cylinder 37 and on the lower part of its outer surface, and a cylindrical element 41 made of reinforced concrete, mounted on the end of the metal cylinder 37 with the possibility of dismantling.

The pipe 6 is equipped with an annular cover 42 mounted by means of a guide 43 at its upper end. The guide 43 is made in the form of a metal ring with a flange on the outer edge, while the inner diameter of the ring is equal to the inner diameter of the nozzle 6, and the flange protrudes beyond it, forming a protrusion, and is rigidly connected with the metal cylinder 37.

The cover 42 can be made in two versions. In FIG. 21 shows a cover 42 made in the form of a ring of concrete. In FIG. 22 shows a cover that includes an upper part 44 made in the form of a metal ring mounted in the guide 43 and a lower part 45 made of refractory concrete, connected to the upper part 44 by means of anchors (not shown) and adjacent to the inner surface of the metal cylinder 37 In this case, the lining 38 of the inner surface of the metal cylinder 37 does not reach the end of the cylinder 37 by an amount equal to the thickness of the lower part 45 of the cover.

The device contains cooling means 46 located on the outer surface of the screen 7 or on the outer surface of the pipe 6 located above the screen 7, which are made in the form of channels (Fig. 22, 23, 25).

The device is equipped with pins 47 located along the edge of the screen 7, for installation in a vacuum chamber 1.

SUBSTITUTE SHEET (RULE 26) The metal cylinder 37 is rigidly connected to the annular plate 34 of the screen 7 by means of stiffening ribs 48 located radially and adjacent to the upper part of the outer surface of the metal cylinder 37 and the outer surface of the metal annular plate 34 of the screen 7 (Fig. 24).

The inner surface of the lower end of the pipe 6 may have any of the forms indicated above.

Example 1

A pilot implementation of the method was carried out on a plant for ladle evacuation of steel, using a ladle with a capacity of up to 385 tons of liquid steel, having an inner diameter in the upper part Z) _k = 4150 mm, depth / 4 = 5550 mm, and a cylindrical vacuum chamber with a lid, inner wherein the diameter D is equal to _VC = 794S mm. The method was implemented by means of the device shown in FIG. 1. Ladle 4 with liquid steel 5 (smelting mass 345 t) was installed using a bridge crane into the internal cavity of the vacuum chamber 1 on stand 3. Then, chamber 1 with a ladle 4 installed in it was covered with a screen 7 with a cylindrical pipe 6 and a cover 2. Tightness the connection of the chamber 1, the shield 7 and the cover 2 was ensured by the seals 9 installed between the flange of the chamber 1, the outer edge of the shield 7 and the flange 8 of the cover 2. The gap Δ between the end of the lower end of the pipe and the surface of the molten steel was determined from the relation (1) and amounted to Δ = 500 mm, with height of the free side of the bucket # _cb = 1000 mm. After assembly, a vacuum from 760 to 200 mm Hg was created in the vacuum chamber. Art. using a steam jet pump. The liquid steel 5 located in the ladle 4 was purged with argon through the bottom plugs 18. Argon was supplied in such a way that gas bubbles came to the surface of the central and peripheral zones 14, 16 in certain regions 33 occupying part of their surface, as shown in FIG. 2. The vacuum control in the vacuum chamber was carried out using vacuum gauges in cavities 13, 15 during the entire vacuum process

SUBSTITUTE SHEET (RULE 26) refining. Under the influence of rarefaction from liquid steel, bubbles of dissolved gases — carbon monoxide, hydrogen, and nitrogen — were formed and a gozslag-metal emulsion was formed on the surface of the liquid steel. The rise of gas-slag emulsion was controlled in a ladle 4 (in the peripheral zone 16) through the inspection holes 19 (not shown in Fig. 1) located on the lid 2, during the entire vacuum refining process, and by analyzing the traces of the lifting of a gas-slag emulsion in the ladle 4 relative to the primary level of liquid steel with slag and on the outer and inner surfaces of the pipe 6 (in the Central zone 14). With a vacuum of 200 mm RT. Art. the gas-slag-metal emulsion rose to the end of the lower end of the nozzle 6 and the steel surface was divided into the central zone 14 and the peripheral zone 16. At the same time, dilution was continued to increase above zones 14 and 16 to ensure a predetermined difference in the depression in the range from 0.5 to 30 mm Hg. Art. A greater rarefaction was created above the central zone 14. The gas-slag-metal emulsion continued to rise until the end of the nozzle 6 was immersed to a depth of h _pp –l20 mm. This immersion depth of the end of the nozzle ensured the creation of a reliable hydraulic shutter between zones 14, 16. At the third stage of the process, as the rate of steel boiling decreases (due to the release of gases dissolved in liquid steel), the gas-slag emulsion level decreased, which led to the unification of zones 14 and 16 and as a result of this, the alignment of the vacuum above them. The vacuum continued to increase to a predetermined level, which was in the range from 0.5 to 2 mm RT. Art. Then, the steel was kept under the indicated vacuum for 6 minutes. At the fourth stage of the process, the level of steel refining was monitored by the content of carbon, sulfur and dissolved gases. The control showed that these indicators correspond to the set, therefore, the repetition of the stages of the process is not required.

SUBSTITUTE SHEET (RULE 26) The experiments were carried out on swimming trunks with different mass of molten steel and different freeboard heights H _C Q. The experimental results are presented in table 1.

Analysis of the results obtained during the processing of liquid steel by the method in accordance with the present invention (experimental, examples N ° 1-3) and the traditional method (control, examples N ° 4, 5), shows the following. In the experimental treatments, there was a steady vacuum refining of steel without splashes and overflows over the side of the bucket. In control treatments (without using the inventive method and device for vacuum refining), only vacuum refining is stable according to Example 5, i.e., with a mass of steel of 320 tons. When processing steel with the method according to the present invention, an increase in the mass (volume) of steel was achieved processed in the ladle during the vacuum refining process by 55 tons (17.2%) and reducing the duration of the vacuum refining process by an average of 2 minutes (8.5-14.5%). At the same time, metallographic studies, chemical analysis and mechanical tests of samples cut from rolled metal obtained from steel processed by the inventive method show that deviations from the given parameter values and deviations in structure, chemical composition, nonmetallic inclusions, as well as mechanical properties: strength, hardness, toughness, elongation and relative narrowing - in the control samples was not observed.

SUBSTITUTE SHEET (RULE 26) Table 1

W n

ABOUT

H and

* Smelting N ° N ° 4, 5 - control, carried out by the traditional method of vacuum refining

Claims

Claim

1. A method of vacuum refining steel, comprising placing a ladle with liquid steel in a vacuum chamber and dividing the surface of the steel into central and peripheral zones with the possibility of creating zones of varying degrees of depression, characterized in that it provides for mixing gas to the ladle with liquid steel for the entire refining process, and in the first stage of the refining process, the vacuum is increased with the same intensity with the same vacuum at each time over the surface of the steel in the ladle, at the second stage during the beginning of intense boiling of steel, determined by the formation of a gas-slag-metal emulsion on its surface, the surface of the boiling steel is divided into the central and peripheral zones, while a greater degree of rarefaction is created above the central zone than above the peripheral zone, after which they continue to increase the degree of rarefaction over these zones with the provision of a given difference in the vacuum between them, in the third stage, with a decrease in the intensity of boiling, the steel is indicated the e zones are again combined and continue to increase the degree of rarefaction over the entire: the surface of the steel to a predetermined level, after which the steel is held at the specified degree of depression for a predetermined time, at the fourth stage, the level of steel refinement in the ladle is controlled and, if it exceeds a predetermined value, the process steps are repeated until a predetermined level of steel refining is obtained.

2. The method according to p. 1, characterized in that the supply of mixing gas to the ladle with liquid steel is carried out from the bottom of the ladle so that the gas bubbles come to the surface of the central and peripheral zones in certain areas that occupy part of their surface.

3. The method according to p. 1, characterized in that the separation of the surface of the boiling steel into the Central and peripheral zones

SUBSTITUTE SHEET (RULE 26) by means of a pipe by immersing the end of the lower end of the pipe in boiling steel to a depth of h _pp , and combining these zones is carried out by lifting the pipe to form a gap Δ between the end of the lower end of the pipe and the surface of the boiling steel in the ladle.

4. The method according to p. 1, characterized in that the separation of the surface of the boiling steel into the central and peripheral zones is carried out by lifting the ladle with boiling steel relative to the stationary pipe until the end of the lower end of the pipe is immersed in boiling steel to a depth of h _m , and the combination of these zones is carried out by lowering the ladle with boiling steel to the formation of a gap Δ between the end face of the lower end of the stationary pipe and the surface of the boiling steel in the ladle.

5. The method according to p. 1, characterized in that the separation of the surface of the boiling steel into the central and peripheral zones is carried out by raising the surface level of the boiling steel in the ladle relative to the pipe until the end of the lower end of the pipe is immersed in boiling steel to a depth of h _pp , and combining these zones carried out by lowering the surface level of boiling steel in the bucket to form a gap Δ between the end face of the lower end of the pipe and the surface of the boiling steel in the bucket.

6. The method according to any one of paragraphs 1 to 4, characterized in that the time of the beginning of intense boiling of steel in the ladle is determined by controlling the rise of gas-slag emulsion and its achievement of a predetermined limit level h _{e max} , and the time of decrease of intense boiling of steel is determined by lowering the level of gas-slag emulsion below a given limit level h _{e max} .

7. The method according to p. 6, characterized in that the limit level of gas-slag emulsion rise is set either relative to the end of the bead side, or relative to the initial surface level of the liquid steel in the ladle.

8. The method according to any one of paragraphs 1-4, characterized in that in the second stage of the process immersion of the end of the lower end of the pipe in

SUBSTITUTE SHEET (RULE 26) boiling steel performed at the level h _ep gazoshlakometallicheskoy emulsion in the peripheral zone exceeding at 0-200 mm level end of the lower end nozzle, and at the third stage of the process, at ^"combining said zones provide a gap Δ between the surface and the end of boiling steel pipe in the lower end range:

0 ≤ Δ ≤ I _rf - 200lsh, (1) where H _cb is the height of the free side of the bucket.

9. The method according to any one of paragraphs 1-4, characterized in that the predetermined difference in the degree of rarefaction over the central and peripheral zones of the surface of the boiling steel is supported by ensuring the flow of gas-slag emulsion from the peripheral to the central zone around the end of the lower end of the pipe.

10. The method according to any one of paragraphs 1-4, characterized in that the predetermined difference in the degree of rarefaction over the central and peripheral zones of the surface of the boiling steel is provided by pumping gas from the cavity of the vacuum chamber in communication with the peripheral zone of the steel surface in the ladle, and / or by feeding in the specified cavity inert gas, such as argon.

11. A device for vacuum refining steel in a ladle, including a vacuum chamber with a lid, a stand for installing a ladle with liquid steel and a pipe made with the possibility of immersing the lower end in liquid steel, characterized in that it is provided with a screen in the central part of which a pipe is installed and the outer edge of the screen is made with the possibility of tight placement between the upper end of the vacuum chamber and the flange of its cover, and the supply system of mixing gas in liquid steel, while the inner surface of the cover, top Thread screen surface and the inner surface of the pipe to form a cavity in fluid communication with a vacuum pump and with the central area of the bucket, and the inner surface of the vacuum chamber, the lower

SUBSTITUTE SHEET (RULE 26) _oo

Zo the surface of the screen, the outer surface of the bucket and the outer surface of the nozzle form a cavity in communication with the peripheral zone of the bucket.

12. The device according to claim 11, characterized in that the mixing gas supply system to liquid steel is made in the form of gas supply paths and porous plugs installed in the bottom of the bucket at a distance from the bucket axis equal to: l _{) φ} = 0 _÷ 0.35D _k , (2) where l _pp is the distance from the center of the tube to the axis of the bucket, mm, D _k is the inner diameter of the bucket in the upper part, mm.

13. The device according to p. 11, characterized in that the outer diameter of the lower end of the pipe is selected from the ratio:

D _k - 100> D _m > 2l _ppmäx + d _ιφ + 2δ _p , (3) where D _k is the inner diameter of the bucket in the upper part, mm, D _np is the outer diameter of the lower end of the pipe L _{p max} is the maximum distance from the center of the tube to the axis of the bucket, mm, d _pp is the tube diameter, mm, δ _{t is the} wall thickness of the lower end of the pipe, mm.

14. The device according to claim 11, characterized in that the upper end of the nozzle is provided with an inspection hole located in its central part and having dimensions that provide video surveillance of the surface of the liquid steel in the central zone of the bucket and the introduction of technological additives in the form of solid, powder and gaseous materials.

15. The device according to claim 11, characterized in that on the lid of the vacuum chamber there are installed video surveillance means for the central and peripheral zones of the bucket, and pressure sensors for measuring the degree of rarefaction above these zones are installed in the indicated cavities communicating with the central and peripheral zones of the bucket.

SUBSTITUTE SHEET (RULE 26)

16. The device according to p. 11 characterized in that the inner surface of the lower end of the pipe is made in the form of a conical surface, the base of which coincides with the end of the pipe.

17. The device according to claim 11, characterized in that the inner and outer surfaces of the lower end of the nozzle are made in the form of two mutually intersecting conical surfaces, while the base of the inner conical surface coincides with the lower end of the nozzle, the base of the outer conical surface is equal to the outer diameter of the lower end of the nozzle, and its top is directed to the end of the lower end of the pipe.

18. The device according to p. 11 characterized in that the inner surface of the lower end of the pipe is made in the form of a surface of revolution, the generatrix of which is a line of constant or variable curvature.

19. The device according to p. 11 characterized in that the inner and outer surfaces of the lower end of the pipe are made in the form of surfaces of revolution, the generators of which are lines of constant or variable curvature.

20. The device according to p. 11, characterized in that the pipe is mounted with the possibility of vertical movement relative to the screen, while the device is equipped with a vertical movement mechanism located on the screen or on the cover of the vacuum chamber.

21. The device according to p. 11, characterized in that the stand for installing the bucket is equipped with a vertical movement mechanism.

22. The device according to p. 11, characterized in that the lid of the vacuum chamber is provided with a flange, while the screen and said flange are interconnected by means of locking elements.

23. The device according to p. 11, characterized in that the screen is equipped with an annular protrusion, the inner surface of which in combination with the outer surface of the lower end of the pipe form an annular

SUBSTITUTE SHEET (RULE 26) cavity around the latter, while the inner diameter of the protrusion is selected from the ratio:

D _VK - 2δ _in ≥ D _in ≥ D _K , (4) where D _{VK is the} inner diameter of the lid of the vacuum chamber, δ _in is the wall thickness of the protrusion, D _in is the internal diameter of the protrusion, D. is the inner diameter of the bucket in the upper part, and the height of the cavity formed by the protrusion is determined by the formula: H _in = H _m -h _fk - h _p , (5) where H _in is the height of the cavity formed by the protrusion, hψ _k is the distance from the vacuum chamber flange to the end of the bucket side, h _p - the distance from the end of the pipe to the end of the side of the bucket.

24. The device according to p. 11, characterized in that it is equipped with shut-off and control equipment, providing the ability to connect these cavities with a vacuum pump and gas paths.

25. The device according to p. 11 or 24, characterized in that it is equipped with shut-off and control equipment, providing the ability to connect these cavities with each other.

26. A device for vacuum refining steel in a ladle, including a vacuum chamber with a lid, a stand for installing a ladle with liquid steel and a nozzle connected to the lid and configured to immerse the lower end in molten steel, characterized in that the nozzle is equipped with a flange made with the possibility of tight connection with the cover of the vacuum chamber, while the upper part of the nozzle is closed, located above the cover of the vacuum chamber outside its internal space and is connected to the vacuum pump, and the lower hour s nozzle located inside the lid of the vacuum chamber. SUBSTITUTE SHEET (RULE 26)

27. A device for vacuum refining steel in a ladle, including a vacuum chamber with a lid, a stand for installing a ladle with liquid steel and a nozzle connected to the lid and configured to immerse the lower end in liquid steel, characterized in that the nozzle is provided with a screen made in in the form of a flange, the lower edge of which is made with the possibility of tight coupling with the upper edge of the bucket, while the pipe is connected to the lid with the possibility of mutual vertical movement.

28. The device according to p. 27, characterized in that the pipe is connected to the cover by means of flexible connections.

29. A nozzle of a device for evacuating liquid metal in a ladle placed in a vacuum chamber, interacting with liquid metal, characterized in that it is provided with a screen mounted above the ladle with liquid metal, the edges of which are made with the possibility of tight placement between the end wall of the vacuum chamber and its lid, while the screen is made in the form of a metal ring-shaped plate, on the surface facing the liquid metal of which the lining is placed, and the pipe includes a metal cylinder, which is rigidly knitted with the specified plate, and a lining placed on the inner surface of the metal cylinder and on the outer surface of its lower part, and the height of the lining on the outer surface of the lower part of the cylinder is limited by the lining of the metal ring-shaped plate.

30. The pipe according to claim 29, characterized in that the lining of the metal ring-shaped plate is made of concrete and is connected to the metal ring-shaped plate by means of anchors.

31. A pipe according to claim 29 or 30, characterized in that the lining of the metal cylinder is made of concrete and is connected to the metal cylinder by means of anchors.

SUBSTITUTE SHEET (RULE 26)

32. The pipe according to p. 31, characterized in that the lining of the outer surface of the lower part of the metal cylinder is made in one piece with the lining of the metal annular plate.

33. The pipe according to claim 31, characterized in that the upper part of the lining of the inner surface of the metal cylinder is made of brick.

34. The pipe according to claim 29, characterized in that it includes a cylindrical element made of reinforced concrete and mounted on the end of the metal cylinder with the possibility of dismantling.

35. A pipe according to claim 29 or 34, characterized in that it is provided with an annular cover mounted by means of a guide on its upper end.

36. The pipe according to claim 35, characterized in that said guide is made in the form of a metal ring with a flange on the outer edge, the inner diameter of the ring being equal to the internal diameter of the pipe, and the flange protrudes beyond it, forming a protrusion, the guide being rigidly connected to metal cylinder.

37. The pipe according to claim 35, wherein the cover is made of concrete.

38. A pipe according to claim 35, characterized in that the cap comprises an upper part made in the form of a metal ring mounted in the guide and a lower part made of concrete, connected to the upper part by means of anchors and adjacent to the inner surface of the metal cylinder of the pipe, however, the lining of the inner surface of the metal cylinder does not reach the end of the cylinder by an amount equal to the thickness of the lower part of the cover.

39. The pipe according to claim 29, characterized in that it contains cooling means located on the outer surface of the screen or on the outer surface of the pipe located above the screen.

SUBSTITUTE SHEET (RULE 26)

40. The pipe according to claim 29, characterized in that for installation and removal it is equipped with trunnions located along the edge of the screen.

41. The pipe according to claim 29, wherein the metal cylinder is rigidly connected to the metal annular plate by means of stiffening ribs located radially and adjacent to the upper part of the outer surface of the metal cylinder and the outer surface of the metal annular plate.

42. The pipe according to claim 29 or 34, characterized in that the inner surface of its lower end is made in the form of a conical surface, the base of which coincides with the end of the pipe.

43. The pipe according to claim 29 or 34, characterized in that the inner and outer surfaces of its lower end are made in the form of two mutually intersecting conical surfaces, while the base of the inner conical surface coincides with the lower end of the pipe, the base of the outer conical surface is equal to the outer diameter of the lower the end of the pipe, and its top is directed to the end of the lower end of the pipe.

44. The pipe according to claim 29 or 34, characterized in that the inner surface of its lower end is made in the form of a surface of revolution, the generatrix of which is a line of constant or variable curvature.

45. The pipe according to claim 29 or 34, characterized in that the inner and outer surfaces of its lower end are made in the form of surfaces of revolution, the generators of which are lines of constant or variable curvature.

SUBSTITUTE SHEET (RULE 26)