RU21915U1 - PLANT FOR THE PRODUCTION OF LOW CARBON STEEL - Google Patents

Description

: PLANT FOR THE PRODUCTION OF LOW-CARBON STEEL The utility model relates to metallurgy, and in particular, to devices for treating steel in a vacuum by the method of oxidative circulation vacuum degassing and can be used for deep refining, in particular, to produce ultra-low-carbon steel. A known installation for circulating vacuum treatment with oxygen decarburization, comprising a bucket and mounted above it with the possibility of reciprocating movement in the vertical plane of the vacuum chamber, including a vacuum pipe, a nozzle for additive ferroalloys and a water-cooled oxygen lance installed in the upper part of the vacuum chamber, as well as a suction and drain nozzles made in the bottom, and a device for supplying a conveying gas to the suction nozzle (see, for example, Joystick G. Deoxidation and vacuum processing of steel, Fundamentals and technology of ladle metallurgy: Translated from German, Moscow: Metallurgy, 1984. p.343). The disadvantage of this installation is the low efficiency of decarburization in the production of low-carbon steels, associated with a decrease in the temperature of the steel at a rate of 2 ° C / min and unproductive compensation for heat loss. To maintain the lining of the vacuum chamber during the interoperational period, gas burners are used in the preheated state. Object - a useful model of MPK С21С7 / 10 v flame from which contributes to the oxidation of deposits in the lining and secondary pollution of steel with carbon. The radial supply of the conveying gas to the suction pipe and the axial supply of oxygen-containing gas to the purge lance contribute to scaling that causes jumps in the carbon content of the steel. The closest analogue to the claimed utility model is an installation for the production of low-carbon steel containing a bucket mounted above it with the possibility of reciprocating movement in a vertical plane of a circulation vacuum chamber with nozzles for additive ferroalloys, the upper part of which is connected to a vacuum pipe, and the bottom is symmetrically arranged relative to vacuum chamber axes drain pipe with channels for conveying gas supply, hermetically installed in the vacuum chamber graph a heater and a movable purge tuyere, while nozzles are made at the end of the purge tuyere located inside the vacuum chamber, and nozzles for supplying gases and reagents are provided at the opposite end of the vacuum chamber (see French application No. 2187921, С21С7 / 10). The disadvantages of the known installation are the low depth of carbon removal from steel, as well as the inability to stabilize the temperature of the steel. This is due to the fact that the supply of the conveying gas to the suction pipe is radial, while the intensity of the steel through the vacuum chamber is limited by the critical gas flow, exceeding which leads to a decrease in the circulation speed and yes /// gz U2. h depth of decarburization. At the same time, the axial supply of oxygen-containing gas to the purge lance leads to strong gushing of steel in the vacuum chamber, which contributes to the subsequent secondary carburization of steel during melting of layers. The possibilities of temperature stabilization when using combined heating of steel (using a graphite heater and the heat of oxidative reactions) in this installation are limited by the low resistance of the graphite heater in the oxygen blast mode. There is also an irrational distribution of heat fluxes with increased heat losses through the vacuum chamber barriers and with low efficiency steel heating, which reduces the effectiveness of its decarburization and temperature stabilization. The technical problem, the solution of which is claimed by the claimed installation for the production of low-carbon steel, is to ensure the deep removal of carbon from steel while stabilizing its temperature. The problem is solved in that in the known installation for the production of low-carbon steel containing a ladle, mounted above it with the possibility of reciprocating movement in a vertical plane, a circulation chamber with a nozzle for additive ferroalloys, the upper part of which is connected to the vacuum pipe, and the bottom is made symmetrically located relative to the axis of the vacuum chamber, a drain pipe and a suction pipe with channels for supplying transporting gas, sealed in a vacuum chamber fit for a heater and a movable purge tuyere, while nozzles are made at the end of the purge tuyere located inside the vacuum chamber, and nozzles for supplying gases and reagents are made at its opposite outer end; according to the change, the inner surface of the upper part of the vacuum chamber is made in the form of a truncated rotation paraboloid, the focus of which is parallel to the drain and suction pipes is a graphite heater with a reflector screen mounted under it, in which from the side of the graphite heater are made from covered channels for supplying inert gas, a purge lance in a vacuum chamber is installed opposite the nozzle for additive ferroalloys, inclined to the bottom and with the possibility of movement relative to the latter in a vertical and horizontal plane, while the nozzles for supplying gas and reagents and / or nozzles of the purge lance are made tangentially, and the channels for supplying the transporting gas in the suction pipe are tangential to a conditional circumference equal to 2/3 of its inner diameter, and oriented opposite branch pipes for supplying gases and reagents and / or nozzles of the purge lance. The essence of the utility model is illustrated by drawings, where: FigL shows a General view of the installation for the production of low carbon steel in section; figure 2 - section aa in fig. 1; The installation for the production of low-carbon steel includes a bucket 1 (Figs. 1, 2), above which, with the possibility of reciprocating movement in a vertical plane, a circulation vacuum chamber 2 with a pipe for adding ferroalloys 3 (Fig. L) is installed. The upper part 4 of the vacuum chamber 2 is in communication with the vacuum pipe 5, and in the bottom 6 there are made, symmetrically located relative to the axis of the vacuum chamber 2, a drain pipe 7 (Fig. 1) and a suction pipe 8 (FigL, 2) with channels for supplying the conveying gas 9 from the pipe 10 The inner surface 11 of the upper part 4 of the vacuum chamber 2 is made in the form of a truncated paraboloid of revolution, described by the well-known (see Tarasov NP Course of Higher Mathematics. M .: Nauka, 1969.P.79-81) equation: (Rr) -2рН ; where r, R are the upper and lower radii of the upper part 4 of the vacuum chamber 2, respectively; H the height of the upper part 4 of the vacuum chamber 2; p is the geometric parameter of the parabola, equal to the distance between the focus and the director of the parabola. In the focus plane of the rotation paraboloid parallel to the drain 7 and the suction pipe 8, a graphite heater 12 is installed, which is connected through current leads 13 to a transformer (not shown in the drawing). Under the graphite heater 12, a refractory protective concave shield-reflector 14 is installed (FIGS. 1, 2), in which open channels 15 for supplying inert gas are made on the side of the heater 12, communicating with the pipe 16. The blowing lance 17 is hermetically installed in the vacuum chamber 2 (FIG. .2) opposite the nozzle 3 for the addition of ferroalloys. At the same time, nozzles 18 are made at the end of the purge lance 17 (Fig. 2) located inside the vacuum chamber 2, and nozzles 19 for supplying gases and reagents are made at its opposite end, located outside the vacuum chamber 2. The purge lance 17 (FIGS. 1, 2) by means of a ball seal 20 of any known construction is mounted obliquely to the bottom of the encore with the possibility of movement relative to it in the vertical and horizontal plane. In this case, the nozzles 19 for supplying gas and reagents and / or nozzles 18 are made tangentially, and the channels 9 for supplying a conveying gas in the suction pipe 8 (Fig. 3) are tangentially made to a conditional circle 21 equal to 2/3 of its internal diameter (Dn) , and are oriented opposite to the direction of the nozzles 19 for supplying gases and reagents and / or nozzles 18 of the purge lance 17 (FIG. 2). Pa figl, 2, positions 22 and 23 respectively indicate molten steel in the ladle 1 and in the vacuum chamber 2. Installation for the production of low-carbon steel works as follows: steel 22 (figl, 2) containing 0.2 h-0.6% carbon is fed into bucket 1 to the evacuation bench using a trolley (not shown in the drawing). Vacuum chamber 2, with a closed pipe for adding ferroalloys 3, is placed above the ladle 1 and the upper part 4 of the vacuum chamber 2, vacuum pipe 5, bottom 6, drain pipe 7 and suction pipe 8 are preheated, with channels 9 for supplying transporting gas disconnected from pipe 10. The heating of these elements and the inner surface 11, the upper part 4 of the vacuum chamber 2, is carried out using a graphite heater 12 connected through current leads 13 to a transformer (not shown in the drawings) to an operating temperature of 1500 ° C. Fulfillment of intDI) 1 6.

the front surface 11 in the form of a truncated rotation paraboloid, as well as the installation of a graphite heater 12 in the focus of this paraboloid, allows you to concentrate radiation (in FIG. 2, the radiation fluxes are shown by dashed lines with arrows) from the graphite heater 12 on the bottom 6 and to conduct a more uniform and intense heating the lining of the vacuum chamber 2 and steel 22. To increase the reflectivity on the inner surface 11 of the upper part 4, the vacuum chamber 2 is applied

high reflectivity coatings. Then vacuum chamber 2

lower down, until the suction 8 and drain 7 pipes are submerged under the level of the steel 22 mirror in the bucket 1, and the vacuum pump (not shown in the drawings) from the vacuum chamber 2 pumps the gases through the vacuum pipe 5. Under the influence of atmospheric pressure, steel 22 (FigL, 2) from the bucket 1 rises through nozzles 7 and 8 into the interior of the vacuum chamber 2 to a barometric height of 1.4 m and covers the bottom 6. At the same time, into the lower part of the suction nozzle 8 (Fig. 1), through channels 9 for supplying a transport gas

argon (or other gases) is supplied from the pipe 10, which drives the steel 22 and lifts it into the vacuum chamber 2. Steel 23 is degassed and then passes through the drain pipe 8 to the ladle 1 with the possibility of multiple circulation. The channels 9 (FIG. 3) for supplying the conveying gas are made using several tubes, for example eight, made of stainless steel, and the argon supply in each tube is regulated separately, independently of the other tubes, which eliminates the interruption of the argon supply when one of the tubes becomes clogged. The supply of transporting gas to the suction pipe 8 through channels 9 located tangentially to a conditional circumference 21 equal to 2/3 of the inner diameter (Dn) of the suction pipe 8, allows to increase the gas content of the steel stream 22 and, due to this, the refining depth and the circulation speed of steel 23 vacuum chamber 2. At the same time, all steel 22 in the suction pipe 8 moves only upward with a minimum speed difference in the central and peripheral zones, which implements a stable maximum operation mode of the metal.

Optimal tangential flow of conveying gas provides

maximum energy dissipation and differential momentum of gas jets, developed interface and turbulence of steel flow 23, which contributes to deeper refinement, due to effective degassing and removal of non-metallic inclusions from it, reduction of spraying and dust formation. At the same time, with the beginning of the evacuation of steel 23, the refractory protective shield-reflector 14, mounted under the graphite heater 12, is fed through open channels 15 from the pipe 16

inert gas blowing the surface of the graphite heater 12, protecting it from aggressive gases, dust and drops of steel 23. The screen protector 14 re-radiates part of the radiation heat fluxes from the graphite heater 12 the inner surface And the upper part 4 of the vacuum chamber 2 and from it to the steel mirror 23, increasing efficiency heating the latter and stabilizing its temperature. Further, if it is necessary to obtain steel 22 of a certain composition, alloying additives and / or deoxidizers are fed into the vacuum chamber 2 through the pipe 3 for supplying ferroalloys. in the purge lance 17, through the nozzles 19 for supplying gases and reagents, oxygen or oxygen-containing gases, as well as powdered reagents, which through nozzles 18 enter the mirror 23 or under it, are supplied. The installation of the purge lance 17 hermetically and with the possibility of its movement in the vertical and horizontal plane relative to the bottom 6, provides a flexible implementation of the various stages of vacuum decarburization. During the first half of the decarburization cycle, oxygen is supplied through nozzles 18 of the purge lance 17, maintained at a predetermined height above the surface of the steel 23, which, by burning carbon monoxide that escapes from steel 23 during vacuum decarburization, melts the crusts frozen on the walls of the vacuum chamber 2. During the second half of the cycle through a purge lance 17 serves a mixture of oxygen and argon, which, coming under the mirror of steel 23, accelerates the decarburization reaction and reduces secondary pollution during subsequent removal d. It is also possible to supply natural gas as a reagent to the purge lance 17, the combustion of which in the volume of steel 23 provides active mixing of the steel 23, due to the formation of combustion products, and at the same time promotes the melting of layers. Using the purge lance 17, through the nozzles 19 for supplying gases and reagents, it is possible to supply powder additives or fluxes to steel 23 using oxygen as the carrier gas. This contributes to a deeper decarburization and desulfurization of steel. Oxygen purge of a vertically and horizontally controlled purge lance 17 contributes during the cumulative decarburization process to increasing the refining efficiency of steel 23 by activating chemical reactions in the first half of the treatment process, when oxygen supply is the limiting factor in the decarburization reaction. If it is necessary to additionally heat steel 23, the function of the purge f) mold 17 during its movement is also temperature control by local oxidation with aluminum oxygen introduced into steel 22 through a nozzle for adding ferroalloys 3. During oxidative purging, the lining of the bottom 6 of the vacuum chamber 2 experiences significant loads moreover, the horizontal movement of the purge lance 17 allows you to adjust the position of the zone of maximum temperatures, in connection with which slag-forming seated in such a zone is less Do not destroy the lining. To purge steel 23 in a vacuum chamber 2, vortex jets of gas and / or reagents are formed at the outlet of the purge lance 17 in the following ways (Figs. 1, 2): when using a single-nozzle purge lance 17, gases and reagents are fed into the axial nozzle 18 through tangential nozzles 19 ; with a multi-nozzle blowing lance 17, the nozzles 18 are tangential to its axis; when making nozzles 18 in the form of Laval nozzles, swirlers are installed in them (not shown in the drawings). The use of a vortex jet of oxygen and reagents flowing out of the nozzles 18 of the blowing lance 17 allows increasing the effective reaction area with increasing volume factor and decarburization rate of steel 23. Since the decarburization reaction proceeds only from the surface of steel 23, the tangential supply of oxygen-containing gas allows increasing the interfacial surface and disperse gas bubbles without strong spraying and compensate for the lack of oxygen in the circulating steel 23, and it is possible to achieve ontsentratsii oxygen are 2-3 times higher than the stoichiometric, which provides a deeper decarburization to produce ultra low carbon steel. Vortex blasting implements a “soft blast” mode with uniform distribution of gas and reagents in steel 23, reduces the visibility of the vacuum chamber refractories 2. Structural design of channels 9 (Fig. 3) for feeding

transporting gas on the suction nozzle 8 tangentially to the conditional circumference 21, equal to 2/3 of its inner diameter, and oriented opposite to the direction of the nozzles 19 for supplying gases and reagents and / or nozzles 18 of the blowing lance 17, contributes to grinding, uniform distribution and increase the residence time of the bubbles gas in steel 23. In this case, the rate and depth of decarburization increase with increasing volume of dispersed gas and the intensity of overtaking of steel 23 in a vacuum chamber 2. Organization of counterclosing ducks of the transporting and purging gases makes it possible to realize turbulent coagulation and effective removal of finely dispersed nonmetallic inclusions, which are formed during deoxidation or chemical heating of steel 23. After the oxygen purge is completed and the necessary circulation coefficient is reached, deoxidation and adjustment of the composition of steel 23 are carried out under vacuum. The obtained ultralow-carbon steel 22 with a carbon concentration of less than 0.003% is subjected to continuous casting, and then

rolling with a high degree of reduction, for example, for steel 0810 - to obtain an automobile sheet of a troupe of especially complex deep drawing.

Based on the foregoing, we can conclude that the inventive installation for the production of low carbon steel is efficient and eliminates the disadvantages that occur in the prototype. Accordingly, the inventive installation can be used in metallurgy for processing steel in vacuum by the method of oxidative vacuum circulation degassing, and therefore, meets the condition of "industrial applicability.

Claims (1)

Installation for the production of low-carbon steel, containing a bucket mounted above it with the possibility of reciprocating movement in a vertical plane of a vacuum chamber with a nozzle for additive ferroalloys, the upper part of which is connected to a vacuum wire, and the bottom is made symmetrically located relative to the axis of the vacuum chamber drain a nozzle and a suction nozzle with channels for supplying a conveying gas, a graphite heater and a movable purge are hermetically seated in a vacuum chamber lance, with nozzles at the end of the blowing lance located inside the vacuum chamber, and nozzles for supplying gases and reagents at its opposite outer end, characterized in that the inner surface of the upper part of the vacuum chamber is made in the form of a truncated rotation paraboloid in the focus of which a graphite heater with a reflector screen mounted above it is placed parallel to the drain and suction nozzles, in which open channels for supplying an inert gas are made on the side of the graphite heater , the purge lance is installed opposite the nozzle for additive ferroalloys, inclined to the bottom and with the possibility of movement relative to the latter in the vertical and horizontal plane, while the nozzles for supplying gas and reagents and / or nozzles of the purge lance are made tangentially, and the channels for supplying conveying gas in the suction the nozzle is made tangentially to a conditional circle equal to 2/3 of its inner diameter, and oriented opposite to the direction of the nozzles for supplying gases and reagents and / or with ate purge lance.