EP0024637B2 - Process for operating a change-over valve for supplying a nozzle in steel-producing convertor - Google Patents

Description

The invention relates to a method for operating a changeover valve for the supply of a nozzle with protective media jacket below the bath surface in a steel production converter with oxygen and fine-grained, carbonaceous fuel, which is suspended in a carrier gas that allows it to alternate through the oxygen inlet channel of the nozzle Add fuel or oxygen.

Methods for introducing pulverized or granular solids into a molten iron with a carrier gas are known. For example, lances are used for blowing in, the outlet openings of which are guided close to the surface of the bath, so that the solids get into the melt with the exit impulse, or the lances are immersed in the iron bath.

Furthermore, nozzle arrangements are known which are located below the bath surface in the refractory masonry, through which solids suspended in carrier gases are fed to the melt.

German Laid-Open Specification 2 316 768 describes, for example, a method and a device for fresh ironing, in which oxygen and fine lime are added through nozzles arranged below the bath surface and solid carbon carriers are added to the melt through further nozzles. A nozzle can also be provided with a plurality of openings, one opening being charged with carrier gas and carbon or fine ore and another opening with fresh gas and fine lime.

German patent specification 2 401 540 deals with a method for melting sponge iron. In this process too, the reactants, namely oxygen, dust-like carbon and fine-grained sponge iron, are fed to the melt below the bath surface, for example through a jacket gas nozzle. The nozzle has several feed channels, e.g. flow in several feed channels, e.g. flow in the inner oxygen, in the middle carbon and in the outer sponge iron. Carbon and sponge iron are suspended in a suitable carrier gas, such as carbon monoxide.

German Patent Specification 2,520,883 describes a method and a device for the continuous gasification of coal. The reactants, preferably fine-grained coal and oxygen, are fed to the iron bath through nozzles below the bath surface, which are arranged in the refractory lining and thus wear out in unison. Inert gas, nitrogen, CO ₂ and water vapor come into consideration as the conveying gas for the carbon. The reactants can be passed through a multi-channel nozzle, preferably from concentric tubes. For the first time, the possibility is mentioned that the reactants oxygen and coal can be mixed within the nozzle shortly before the nozzle mouth.

In the reference "Fluid Power", Bureau of Naval Personnel, Navy Training Course, Navpers 16193-A, 1966 Edition, pages 175 and 176, a shuttle valve is described in function in a hydraulic aircraft system. However, this reference does not contain any references to the use of a shuttle valve for introducing fuel and oxygen into an iron bath.

The German laid-open specification 27 56 432 describes a method and a device for increasing the scrap rate. Alternatively, gaseous or liquid hydrocarbons can be supplied via a valve. However, the reliable introduction of fuel and oxygen in alternation is not mentioned in this document.

German Offenlegungsschrift 2,723,857 relates to a method and an apparatus for steel production. Solid, carbon-containing material is conducted into the melt below the surface and an oxidizing gas is introduced into the vessel. The carbonaceous material is blown through blowpipes using a carrier gas. The carrier gas can be a reducing, oxidizing or inert gas. In this process, the oxygen is normally delivered to the metallurgical vessel through a water-cooled lance. However, it is also possible to supply the oxygen by blowing tube injection or by injection using a submerged lance. The application description literally states: "If blowpipes are used to inject oxygen and / or solid, carbonaceous materials, then the blowpipes can consist of two or more concentric tubes and have a circular liquid shield that surrounds the primary injection tube. This shielding fluid can an inert gas or a liquid, e.g. hydrocarbon gas or a liquid, or an oxidizing gas or a liquid, and the fluid can be chosen so that wear of the liner and the blowpipes is kept as low as possible in order to block the blowpipes The blowpipes can be designed so that they can supply both oxidizing gas and solid, carbon-containing material ". It is then said further in the specific embodiment 1 that particulate graphite was blown in at a rate of 2.5 kg / min for 17 minutes. The blowpipes used for blowing carbon had a circular cross section and were charged as follows: shielding gas: air at a rate of 7 m ³ / h; Carrier gas: argon at a rate of 30 m ³ / h. The blow tube core diameter was 7 mm with an annular gap of 1 mm.

The known methods for introducing carbonaceous fuels into an iron melt have in common that the finely divided solids suspended in a carrier gas are fed separately from the oxygen to the melt through their own feed channels. This feed box channels are adapted in cross-section to the flow rate and accordingly correspondingly small, for example the diameter of the blow pipe is 7 mm. However, with the decreasing cross-section of the conveyor, the risk of blockages increases. Mainly if finely divided fuels with different grain sizes and fluctuations in the grain size distribution are used at high loading rates from solids to carrier gas for economic reasons, there is a risk of grafting, which leads to blockages in narrow delivery lines.

Another difficulty with the known induction methods is keeping the feed channels clear in periods without fuel delivery, e.g. when finishing a molten steel, if you set the desired low final carbon content. During this fresh period, the carrier gas usually flows through the feed channels without solid loading in order to prevent melt from penetrating into the nozzles. However, the carrier gas extracts heat from the melt and, depending on the type of gas, can also have an unfavorable effect on the steel composition, e.g. due to increased nitrogen levels in the finished steel.

French patent applications 2 292 771 and 2 378 867 describe fresh processes in which a change from oxygen to fuel takes place in the course of the process. A teaching for a reliable and trouble-free fuel introduction process can not be found in these patents.

In operational practice, it has proven to be particularly important to use the inlet nozzles for carbon-containing fuels over long periods, e.g. when operating an iron bath reactor for gas generation over several months and when producing steel over a converter journey of about 1000 batches, to operate reliably and without problems since every repair, e.g. if a nozzle becomes clogged, as a loss of production time and thus economically very disadvantageous.

The invention is therefore based on the object to provide a method for operating a changeover valve for supplying a nozzle with oxygen and fine-grained, carbonaceous fuel, in which the reliable, trouble-free addition of fuels below the bath surface is guaranteed over long periods, clogging of the nozzle are avoided and the nozzles are kept clear during fuel-free operating periods.

This object is achieved according to the invention in that the valve switchover is carried out by one of the media to be conveyed itself.

• a) der Sauerstoffvordruck zur Ventilumschaltung benutzt wird,
• b) dieser Sauerstoffvordruck im Ventil selbst auf den Sauerstoffblasdruck der Düse (4) reduziert wird,
• c) wobei die Reduzierung des Sauerstoffvordruckes auf dem Sauerstoffblasdruck mittels eines vor der Düse (4) im Sauerstoffdurchströmkanal des Ventils angeordnetem 'Drosselorgan (11) mit fest einstellbarem, definiertem Sauerstofföffnungsquerschnitt (10) erfolgt,
• d) durch den beweglichen Ventilkörper (5) bei anstehendem Sauerstoffvordruck nur der Sauerstofföffnungsquerschnitt (10) für die Düse (4) geöffnet ist,
• e) oder bei Verringerung des anstehenden Sauerstoffvordrucks um einen bestimmten, einstellbaren Betrag von 0,5 bis 10 bar über dem Sauerstoffblasdruck der Düse (4), nur der Brennstofföffnungsquerschnitt (6) zur Düse (4) freigegeben wird,
• f) die sauerstoffdurchströmten Ventilbauteile gasdicht gegen die brennstoffdurchströmten Ventilteile abgedichtet sind, und
• g) das Umschaltventil zwischen Konverterdrehachse und Düse (4) am Konverter vorgesehen ist.

The invention relates to a method for operating a changeover valve for the provision of a nozzle with protective medium jacket beneath the bath surface in a steel production converter with oxygen and fine-grained, carbonaceous fuel, which is suspended in a carrier gas which allows fuel to be alternately passed through the oxygen inlet channel of the nozzle or supply oxygen, in which a displaceable valve body (5) is arranged in a housing (1) with a fuel supply line (7), an oxygen supply line (3) and a nozzle pipe (4), said valve body (5) or the oxygen opening cross section (6) or the oxygen opening cross section (10 ) releases, and where

• a) the oxygen pre-pressure is used for valve switching,
• b) this oxygen admission pressure in the valve itself is reduced to the oxygen blowing pressure of the nozzle (4),
• c) the reduction of the oxygen admission pressure to the oxygen blowing pressure takes place by means of a throttle element (11) arranged in front of the nozzle (4) in the oxygen flow channel of the valve and having a permanently adjustable, defined oxygen opening cross section (10),
• d) only the oxygen opening cross section (10) for the nozzle (4) is opened by the movable valve body (5) when the oxygen pressure is present,
• e) or when the pending oxygen admission pressure is reduced by a certain, adjustable amount of 0.5 to 10 bar above the oxygen blowing pressure of the nozzle (4), only the fuel opening cross section (6) to the nozzle (4) is released,
• f) the oxygen-flowed valve components are sealed gas-tight against the fuel-flowed valve parts, and
• g) the switching valve between the converter axis of rotation and the nozzle (4) is provided on the converter.

The method according to the invention is characterized by high operational reliability, and the inlet nozzles for finely divided, carbon-containing fuels below the bath surface do not become clogged. As soon as irregularities become apparent in the flow rate of the carbon-containing fuels, for example the delivery rate decreases, the fuel delivery is switched over to oxygen and the nozzle channel is thus blown free. Formations at the nozzle mouth, which often form the starting point for blockages, are burned off by the oxygen flow. In order to achieve this blowing out of the nozzle, the shortest oxygen blowing times are sufficient, for example from 0.1 to about 2 minutes. The oxygen blowing times can be varied as desired and, in particular, can be extended longer before the supply of fuel and carrier medium is started again.

According to the invention, the change from fuel to oxygen can occur several times in short succession. This procedure is particularly useful if the oxygen blowing times are to be short. As soon as the fuel delivery runs smoothly again after a brief burst of oxygen of, for example, 10 s, another acid is unnecessary addition of fabric. Otherwise, the short-term addition of oxygen can be repeated a corresponding number of times. The switchover of oxygen bubbles to the suspension conveyance, e.g. of nitrogen and dusty coal, is carried out almost without inertia by means of corresponding switchover devices, which are arranged in the immediate vicinity of the nozzle mounting flanges, in any case directly on the bottom of the treatment vessels, for example an iron bath reactor or a convertor for steel production.

A simple form of the inlet nozzle for the suspension of finely divided, carbonaceous fuel and a carrier medium on the one hand and oxygen on the other hand, consists of two concentric tubes, the fuel and alternately the oxygen flowing through the central tube. To protect the nozzle against premature burning back, the annular gap, formed from the central tube and the second concentric tube, is charged with, for example, 0.5 to 5% by weight of gaseous and / or liquid hydrocarbons, based on the oxygen. This nozzle is usually installed in the fireproof masonry below the bath surface and burns back evenly with the lining.

According to the invention, the risk of nozzle clogging when introducing carbon-containing, pulverized fuels into an iron smelter is practically excluded, and for this reason the installation of the blow cross section actually required is sufficient to introduce the suspension, that is, the additional installation of further fuel introduction nozzles is unnecessary for safety reasons. For example, in a converter that works according to the oxygen blow-through method, it has proven to be completely sufficient to convert only two of the ten oxygen inlet nozzles present in the converter base for the addition of fine-particle coal or coke. Through these two nozzles, about 2000 kg of coal dust can be fed to an iron melt of about 65 t within 10 minutes. Nitrogen is used as the carrier medium, for example, and the loading rate is about 12 kg of coal dust / Nm ^{3 of} nitrogen. The addition of fuel serves to increase the heat balance in order to increase the scrap melting capacity in steel production.

In the known methods for introducing finely divided, carbon-containing fuels into a molten iron, supply tubes of 10 mm inside diameter are installed in the center in the ten oxygen inlet nozzles mentioned in each nozzle as a delivery channel for the fuel-carrier gas suspension. As usual, the oxygen inlet nozzles themselves are constructed from two concentric tubes, in which the inner tube with a clear diameter of 24 mm is used to supply oxygen or oxygen and lime dust. The arrangement of the fuel supply channels in the oxygen tube has been found to be disadvantageous for several reasons. The installation and supply of the ten fuel inlet pipes is procedurally complex, but is required with this fuel inlet method in order to avoid malfunctions in individual feed channels, e.g. Blockages to keep a sufficient delivery cross-section for the carbon-containing fuels operational. Blockages on individual fuel introduction channels occurred in almost every batch. Furthermore, it turned out to be particularly unfavorable to have to keep these channels clear with carrier gas if the fuel delivery is stopped towards the end of the cycle. The nitrogen used to fuel the fuel led to undesirably high nitrogen contents in the molten steel. Other carrier gases, such as argon or methane, are expensive compared to nitrogen and also require costly installations for another medium on the converter system. Nitrogen is usually available on an oxygen blow-through converter. In addition, carrier gas blowing without fuel loading leads to a deterioration in the heat balance in steel production. The heat for heating the carrier gas is lost as energy for melting the scrap.

The method according to the invention makes it possible, for example, to further increase the operational safety of an iron bath recorder for the continuous gasification of coal, as is described in German patent specification 2 520 883. In such an iron bath reactor, large amounts of coal are converted to gas, consisting essentially of CO and H ₂ . The reactants carbon rod and oxygen are normally added through nozzles consisting of several concentric tubes which are arranged below the surface of the iron bath. The suspension of finely divided coal and a conveying gas, for example CH ₄ , usually flows through the central tube, oxygen through the annular gap around the central tube and the nozzle protection medium, for example natural gas, through a further annular gap. Normally, these nozzles work without problems, but there are occasional approaches at the nozzle mouth of the central tube, which lead to a reduction in the amount of coal dust. However, since the iron bath reactor should have as uniform a gas generation rate as possible, the rapid elimination of such disruptions in coal production is particularly important. The change according to the invention from coal dust to oxygen in the oxygen inlet channel of the nozzle allows the usual coal production to be resumed after a relatively short time, for example as a rule of less than 1 min.

A particularly advantageous application of the invention consists in combining it with the method for supplying heat during steel production in the converter, described in German patent application P 2 838 983.5. In this process, the steel is produced in the converter by the carbon-containing melt Fuels supplied heat and especially these fuels with a previously unattainable, high thermal efficiency in the melt used and thus the economic melting of solid iron carriers, such as scrap, increased significantly up to the steel production without molten pig iron. In this method, the oxygen for freshening the melt and for burning the fuels is introduced simultaneously into the converter as gas jets directed onto the bath surface and below the bath surface. In particular, coke, brown coal coke, graphite, coal of various qualities and mixtures thereof are used as carbon-containing fuels.

These carbon-containing fuels are preferably introduced in powder form below the bath surface into the iron melt of the converter together with a carrier gas. Nitrogen, CO, CH ₄ or natural gas and inert gas, for example argon, have proven suitable as carrier gases. According to the aforementioned German patent application, the suspension of carbon-containing fuels and a carrier gas can also be supplied via one or more nozzles in an oxygen blow-through converter, the inlet tube of individual nozzles being charged with the suspension of fuel and carrier gas instead of oxygen.

The method according to the present invention now overcomes the disadvantages which still exist hitherto in the known supply of finely divided, carbon-containing fuels into an iron or steel melt, as they also adhere to the otherwise very advantageous process of supplying heat according to German patent application P 2 838 983.5.

In addition to the advantages of the method according to the invention which have already been set out, a further advantage is to be pointed out, particularly in steel production. By using the oxygen inlet pipes of one or more nozzles in the oxygen blow-through process for supplying finely divided, carbon-containing fuels during the fuel introduction period and the subsequent change to oxygen, stands for the finished fresh phase, i.e. the period without introduction of fuel, a correspondingly higher blowing cross-section is available for the oxygen. This shortens this fresh phase, which in turn results in a reduced total fresh time, which means a profit for steel production.

The method according to the invention is suitable for introducing a wide variety of fine-grained fuels, for example coal of different quality, coke, brown coal coke, graphite, refining residues and mixtures of these fuels. The fuels are supplied in powdered or granular form, whereby the grain size and grain size distribution can be varied within wide limits.

Inert gases such as argon, nitrogen, carbon monoxide, carbon dioxide, hydrocarbons such as methane, natural gas and water vapor are particularly suitable as carrier gas.

The method according to the invention is not restricted to the introduction of oxygen, but is also suitable for the introduction of other oxygen-containing gases, in particular air, and mixtures of oxygen and other gases, in particular oxygen with argon.

According to a preferred embodiment, only a part of the total number of nozzles which are arranged below the iron bath surface in a treatment vessel, for example an iron bath reactor for gas production or an oxygen blow-through converter for steel production, are used as inlet nozzles for the carbon-containing fuels.

The method according to the earth's infection, in which a change from fuel to oxygen and vice versa takes place in the same nozzle channel, can also be applied to other processes in which carbon-containing fuels are introduced into an iron melt.

The method according to the invention for alternately introducing finely divided, carbon-containing fuels and oxygen is explained in more detail below.

The existing pressure in the oxygen supply system, i.e. the oxygen admission pressure, which is normally of the order of 20 bar, serves to switch over the valve. The oxygen admission pressure is reduced in the valve itself to the oxygen blowing pressure of the nozzle. The moving valve body only opens the oxygen opening cross-section for the nozzle when oxygen pressure is present. When the prevailing oxygen admission pressure is reduced by a certain amount, which can be set by means of a spring, of 0.5 to 10 bar, preferably 2 bar, above the oxygen blowing pressure of the nozzle, only the fuel opening cross section to the nozzle is released.

In order to ensure the reliable switching of fuel to oxygen and, in particular, to avoid lines through which fuel and oxygen flow in succession, the changeover valve is located in the immediate vicinity of the nozzle on the converter, between the converter axis of rotation and the nozzle, in particular in a structural unit with the nozzle itself, assembled. The changeover valve is preferably attached directly to the mounting flange of the nozzle.

The proven double-tube nozzles with protective medium coating are normally used as nozzles. In this nozzle embodiment, the oxygen usually flows through the central tube. The method according to the invention allows oxygen or fuel to be passed alternately through this nozzle channel, ie in this case the central nozzle tube, and to switch from fuel to oxygen as often as desired. To protect the nozzle against premature burning back of the nozzle in the refractory lining in which it is normally installed, flows through the annular gap between the inner and a second outer a protective medium. Gases and / or liquids can be used as a protective medium. Carbon dioxide such as methane, natural gas, propane, butane, light heating oil and other types of oil are preferred. The proportion of hydrocarbons, based on the oxygen throughput, is low and is between 1 and 5% by weight.

However, the method for operating the changeover valve according to the invention is not limited to this type of nozzle, but rather can be used for each inlet nozzle in the converter area for switching from oxygen-containing media to fine-shaped carbon-containing media. The switching valve can e.g. can be used in conjunction with the so-called ring slot nozzle according to German Patent 2,438,142.

A preferred method of operating the switching valve is to use certain double tube nozzles, e.g. to operate two of a total of ten, which are installed in the converter floor of an oxygen blow-through converter, briefly with oxygen, then over a longer period of, for example, 8 minutes with a suspension of powdered, carbon-containing fuels and a carrier gas and then against freshness, for example 5 minutes to prevent oxygen again. Coke, lignite coke, graphite, coal of various qualities and mixtures thereof in the finely divided state of up to about 1 mm grain size have proven themselves as carbon-containing fuels. The changeover valves have proven to be extremely reliable, for example the valves over 1000 batches could be used in the described mode of operation without malfunctions.

Pneumatically or electrically controllable valves for medium switching are common and are widely used. However, the known valves for reversing require an additional line for the control medium. When installing the known valves directly on a steel production converter, difficulties arise because of the relatively high ambient temperature of up to 300 ° C. and, moreover, due to the need to supply an additional control line. These lines must be brought to the converter via a rotating union in the converter pivot.

These disadvantages are avoided in the method according to the invention for operating the changeover valve, since the application medium in the converter, namely oxygen, is used directly for valve control. An additional control medium or an electrical line is therefore unnecessary. The oxygen is mixed with the network pressure, i.e. the admission pressure up to the changeover valve. The full oxygen upstream pressure, normally around 20 bar, is used in the valve to control the movable valve body. Of course, other pressure values, depending on the oxygen supply system, are also suitable.

The oxygen pressure in the valve acts on a movable valve body, which closes the fuel opening cross-section to the changeover valve in a gas-tight manner. In this position of the movable valve body, oxygen can reach the nozzle channel through the oxygen opening cross section. The oxygen opening cross-section is dimensioned such that it acts as a throttle element and reduces the oxygen admission pressure to the oxygen nozzle pressure. This reduction in pressure, for example from 20 bar upstream pressure to 4 bar nozzle pressure, determines the cross section of the oxygen opening to the amount of oxygen flow. The oxygen opening cross-section is fixed at the changeover valve. However, this setting can be changed relatively easily according to the desired pressure conditions.

As soon as the oxygen admission pressure decreases i.e. When the oxygen supply is shut off and the line is released, the changeover valve switches using the movable valve body. The oxygen opening cross section is closed gas-tight and the fuel opening cross section is released. The pressure difference between the oxygen pre-pressure, e.g. 20 bar, and the oxygen pre-pressure reduction at which the switching process is triggered, is set via a spring in the valve by a value between 0.5 to 10 bar, preferably 2 bar, above the oxygen blowing pressure of the nozzle, for example 4 bar, in the changeover valve and is consequently, for example, 6 bar. This triggering of the switching process by means of a pressure difference that can be selected within the specified limits of 0.5 to 10 bar via the oxygen blowing pressure of the nozzle has the advantage that, in the event of slow pressure reduction in the oxygen pre-pressure line, no intermediate position or fluttering of the movable valve body occurs, in which both oxygen and Fuel can get into the nozzle channel at the same time.

The oxygen supply line is preferably connected to a valve chamber which has a boundary wall which permits a change in length of the valve chamber under oxygen gas pressure, the displaceable end of the valve chamber is connected to a double-acting valve body which monitors the fuel opening cross section on the one hand and the oxygen opening cross section on the other hand, and the valve body is so preloaded that the oxygen opening cross section is closed.

The preloading of the valve body can be brought about by a spring or by equivalent means, such as a pneumatic pre-pressure.

The valve body is preferably arranged coaxially in the fuel supply line.

The boundary wall is preferably formed by a bellows.

The parts of the device through which oxygen flows are sealed gas-tight against the parts through which fuel flows.

A throttle element is provided which determines the cross section of the oxygen opening.

The method according to the invention will now be explained in more detail using an exemplary embodiment with reference to the drawing.

The figure shows a longitudinal section through a changeover valve, for use in the method according to the invention.

The changeover valve comprises a stationary housing 1 (shown hatched), with an oxygen feed line 3, in which the oxygen admission pressure prevails when oxygen is supplied to the nozzle tube 4. In the position shown of the movable valve body 5 (shown in hatched lines) there is no oxygen pressure, and the fuel opening cross section 6 is released so that the fuel, for example a carbon / nitrogen suspension, can pass from the fuel line 7 to the nozzle line 4.

For example, serves as the conveying gas for the powdered carbon, for example coke, nitrogen or inert gas, for example argon. The feed gas has a pressure of about 3 bar without a load and a pressure of about 12 bar with a full load of 17 kg of carbon per Nm ³ .

As soon as the oxygen supply line 3 with the oxygen pre-pressure, e.g. 20 bar, is acted upon, the movable valve body 5 moves in the direction of the fuel supply line 7 and closes the fuel opening cross section 6 by means of the sealing means 8 in cooperation with the contact surface 9. The oxygen opening cross section 10 is released and oxygen flows into the nozzle tube 4. In order to reduce the desired pressure from To achieve oxygen admission pressure (20 bar) to the oxygen nozzle pressure, for example 3 bar, the oxygen opening cross section 10 can be adjusted accordingly by different bore diameters 10 in the perforated disk of the throttle element 11.

As soon as the oxygen admission pressure has dropped by an adjustable pressure difference between 0.5 to 10 bar above the blowing pressure of the nozzle 4 (0.5 to 10 bar + blowing pressure), the movable valve body 5 moves back into the position shown and releases the fuel opening cross section 6 . The pressure difference for triggering the switching process is set in the described embodiment by the spring force of the spring 13.

It should also be mentioned that the parts through which oxygen flows are sealed gas-tight when the fuel is being conveyed and that the metal bellows 14 allows the required movement of the movable valve body 5 when switching over.

Claims (2)

1. A method of operating a reversing valve for supplying a tuyere having a protective medium jacket below the bath surface in a steelmaking converter with oxygen and fine-grained carbonaceous fuel that is suspended in a carrier gas, said method making it possible to supply fuel and oxygen alternatingly through the oxygen introducing duct of the tuyere, wherein a housing (1) having a fuel supply pipe (7), an oxygen supply pipe (3) and a tuyere pipe (4) contains a displaceable valve body (5) that releases the fuel aperture cross section (6) or the oxygen aperture cross section (10), and wherein

a) the oxygen admission pressure is used for reversing the valve,

b) this oxygen admission pressure is reduced in the valve itself to the oxygen blast pressure of the tuyere (4),

c) whereby the reduction of the oxygen admission pressure to the oxygen blast pressure is performed by a throttle member (11) disposed before the tuyere (4) in the oxygen flow duct of the valve and having a firmly adjustable, predefined oxygen aperture cross section (10),

d) the movable valve body (5) opens only the oxygen aperture cross section (10) for the tuyere (4) when the oxygen admission pressure prevails,

e) or, when the prevailing oxygen admission pressure is reduced by a certain adjustable amount of 0.5 to 10 bar above the oxygen blast pressure of the tuyere (4), only the fuel aperture cross section (6) of the tuyere (4) is released.

f) the valve parts that oxygen flows through are sealed in gastight fashion from the valve parts that fuel flows through, and

g) the reversing valve is provided on the converter between the rotation axis of the converter and the tuyers (4).

2. The method of claim 1, characterized in that the adjustable amount for reducing the prevailing oxygen admission pressure is 2 bar.

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