EP0024637A1 - Process for operating a change-over valve for supplying a nozzle in steel-producing convertor - Google Patents

Abstract

A method and a device for introducing finely divided, carbon-containing fuels, which are suspended in a carrier gas, and oxygen into a molten iron are described. In the process, fuel and oxygen can be introduced alternately through the same inlet channel of a nozzle into an iron melt below the surface of the iron bath. The device allows the alternate supply of fuel or oxygen and is controlled by the oxygen line pressure.

Description

The invention relates to a method and a device for introducing fine-grained, carbon-containing fuels, such as coal and coke powder, which are suspended in a carrier medium, and oxygen into an iron melt below the iron bath surface through nozzles arranged in the refractory masonry of the treatment vessel.

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.

The German Auslegeschrift 23 16 768 describes, for example, a method and an apparatus for fresh iron, 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.

The German patent 2 4 ₀ 1 54o deals with egg process for melting iron sponge. 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. B. 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 25 2o 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.

German Offenlegungsschrift 27 23 857 relates to a method and an apparatus for steel production. Solid, carbon-containing material is led 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 supplied to the metallurgical vessel via a water-cooled lance. However, it is 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, carbon-shaped materials, 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 may be an inert gas or a liquid, e.g., hydrocarbon gas or a liquid, or an oxidizing gas or a liquid, and the fluid may be chosen to minimize wear on the liner and blowpipes to minimize to prevent blockage of the blowpipes. The blowpipes can be designed so that they can supply both oxidizing gas and solid, carbon-containing material. " Then, in specific embodiment 1, it is said that particulate graphite was blown in at a rate of 3.5 kg / min for 17 minutes. The blowpipes used to inject 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.

A common feature of the known processes for introducing carbon-containing fuels into an iron melt is that the finely divided solids are suspended in a carrier gas and fed separately from the oxygen to the melt by their own feed channels. These feed channels are adapted in cross-section to the flow rate and accordingly small, z. B. the diameter of said blow pipe is 7 mm. With the decreasing conveyor cross However, the risk of constipation 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 to keep the feed channels clear in periods without fuel delivery, e.g. B. 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 continue to have an adverse effect on the steel composition, e.g. B. by increased nitrogen levels in the finished steel.

In operational practice, it proves to be particularly important to use the inlet nozzles for carbon-containing fuels over long periods, e.g. B. when operating an iron bath reactor for gas generation over several months and in steel production via a converter journey of about _1,000 batches, reliable and trouble-free to operate, since every repair, eg. B. when a nozzle clogs, as a loss of production time and thus economically very disadvantageous.

The invention is accordingly based on the object of providing a method and a device for introducing fine-grained, carbon-containing fuels, such as coal and coke powder, into an iron smelt, in which The reliable, trouble-free addition of fuels below the surface of the bath is guaranteed over long periods, clogging of the nozzles is avoided and the nozzles are kept free during fuel-free operating periods.

This object is achieved according to the invention in that fuel and oxygen are fed alternately through the same inlet duct to the nozzle.

The invention relates to a method for introducing fine-grained, carbon-containing fuels, which are suspended in a carrier gas, and oxygen into an iron melt below the surface of the iron bath through nozzles arranged in the refractory masonry of the treatment vessel, which is characterized in that fuel and oxygen alternate through the same inlet channel of the nozzle.

The invention further relates to a device for introducing fine-grained, carbon-containing fuels, which are suspended in a carrier gas, and oxygen into a molten iron, which is characterized in that a displaceable valve body is arranged in a housing with a fuel supply line, an oxygen supply line and a nozzle tube which releases the fuel opening cross section or the oxygen opening cross section and which is controlled by the oxygen supply line pressure.

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. Once there are irregularities in the flow rate of the carbonaceous Fuels show, for example, the delivery rate is reduced, is switched from fuel delivery to oxygen for a short time and thus the nozzle channel is 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 seconds, there is no need for further oxygen addition. Otherwise, the short-term addition of oxygen can be repeated a corresponding number of times. The switchover of oxygen bubbles to the suspension conveyance, for example of nitrogen and dusty coal, takes place 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 converter for steelmaking.

A simple form of the inlet nozzle for the suspension of finely divided, carbon-containing 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. The annular gap, formed from the central tube and the second concentric tube, for protecting the nozzle against premature burning back, 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 a molten iron is practically excluded, and for this reason the installation of the blow cross section actually required is sufficient to introduce the suspension, i. H. there is no need to install additional fuel injectors for safety reasons. For example, in a converter that works according to the oxygen blow-through method, it has proven entirely 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, an iron melt of about 65 t can be fed with about 2ooo kg of coal dust within 10 minutes. Nitrogen is used as the carrier medium, for example, and the loading rate is about 12 kg of coal dust / Nm 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 an iron smelter, feed pipes of 1o mm inside diameter are installed in the center of the ten oxygen inlet nozzles mentioned in each nozzle as a delivery channel for the fuel-carrier gas suspension. The oxygen injection nozzles themselves, as usual, are made up of 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 necessary with this fuel inlet method, in order to avoid malfunctions in individual supply channels, e.g. B. 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 reactor for the continuous gasification of coal, as is described in German specification 2,508,883. In such an iron bath reactor, large amounts of coal become gas, essentially consisting of CO and H ₂ , implemented. The reactants coal dust and oxygen are normally added through nozzles consisting of several concentric tubes which are arranged below the surface of the iron bath. Usually, the suspension of finely divided coal and a conveying gas, for example CH ₄ , flows through the central tube, oxygen flows 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 gas generation rates that are as uniform as possible, the rapid elimination of such disruptions in coal production is particularly important. The inventive change from coal dust to oxygen in the fuel inlet channel of the nozzle allows it after a relatively short time, for. B. usually less than 1 min to resume the usual coal production.

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 28 38 983.5. In this process, heat is added to the melt by carbon-containing fuels during steel production in the converter and, in particular, these fuels are used in the melt with a previously unattainable high thermal efficiency, thus considerably increasing the economic melting of solid iron carriers, for example scrap, right up to steel production without molten pig iron. In this method, the oxygen for freshening up the melt and for burning the fuels is simultaneously used as gas jets directed at the bath surface and below the bath surface initiated in the converter. 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 pipe 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 28 38'983.5.

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

The method and the device according to the invention are suitable for introducing a wide variety of fine-grained fuels, for example coal of different quality, coke, brown coal coke, graphite, refinery 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 and the device according to the invention are not limited to the introduction of oxygen, but are also suitable for the introduction of other gases containing oxygen, 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 invention will now be described using a non-limiting example of steel production increased scrap rate explained in more detail.

In a 6o t oxygen blow-through converter, which is equipped with ten nozzles in the converter bottom and a nozzle in the upper converter wall for oxygen blowing, 30 tons of commercial grade scrap and 44 tons of pig iron with a composition of 4.2% carbon, 0.6 % Silicon, 0.8% manganese, 0.3% phosphorus, 0.03% sulfur and a temperature of 125 ° C.

Two of the floor nozzles are equipped to use the method according to the invention, i. H. Fuel and oxygen can be passed alternately through the same inlet channel of the nozzle.

At the start of freshness, approximately 10,000 Nm ³ / h of oxygen are fed to the melt through eight floor nozzles and approximately the same amount of oxygen through the inflation nozzle in the converter hat. At the same time, 2oo kg / min coke powder together with 16 Nm ³ / min nitrogen are fed into the melt via two floor nozzles.

After about 10 minutes, about 2000 kg of coke are added to the melt in this way, and the two fuel injection nozzles are switched to oxygen.

After a blowing time of about 15 minutes, the freshening process is finished, and after a subsequent corrective blowing of about 2 minutes, the molten steel with a composition of about 0.2% carbon, 0.1% manganese, 0.025% phosphorus, 0.02% sulfur and one Temperature of 167o ° C.

The total batch follow-up time is about 40 minutes. In total, the melt has 46oo Nm ³ oxygen, 100 Nm ³ Propane for nozzle protection, 15o 1 oil for two-minute scrap preheating and 2ooo kg coke added. The tapping weight of the finished batch is 64 t.

It goes without saying that the method of operation explained, for example, can be modified in a variety of ways, in particular as regards the supply of the finely divided, carbon-containing fuels. For example, in the case of a batch in the oxygen blow-through converter, the fuel supply can be briefly interrupted and oxygen can be blown through the fuel introduction channel.

The method according to the invention, 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 device 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. H. the oxygen admission pressure, which is usually in the order of 20 bar, serves to switch 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 oxygen supply pressure is reduced by a certain amount, which can be adjusted via a spring, from 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 according to the invention is located in the immediate vicinity of the nozzle on the converter, preferably between the converter axis of rotation and the nozzle, in particular in a structural unit with the nozzle yourself, assembled. The changeover valve is preferably attached directly to the mounting flange of the nozzle.

The proven double-tube nozzles with protective medium sheathing are normally used as nozzles. In this nozzle embodiment, the oxygen usually flows through the central tube. The changeover valve according to the invention allows alternating oxygen or fuel through this nozzle channel, ie. H. in this case the central nozzle pipe, to conduct and switch as often as required from fuel to oxygen. To protect the nozzle against premature burning back of the nozzle in the refractory lining in which it is normally installed, a protective medium flows through the annular gap between the inner and a second outer nozzle tube. Gases and / or liquids can be used as a protective medium. Hydrocarbons 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 use of the changeover valve according to the invention is not restricted to this type of nozzle, but rather can be used for each inlet nozzle in the converter area for switching over oxygen-containing media to fuels and / or pneumatically conveyable goods. The switching valve can e.g. B. in connection with the so-called called ring slot nozzle can be used according to German Patent 2,438,142.

A preferred application of the switching valve according to the invention is to use certain double tube nozzles, e.g. B. two out of a total of ten, which are installed in the converter floor of an oxygen blow-through converter, for a short time with oxygen, then for a longer period of time, for example 8 minutes, with a suspension of powdered, carbon-containing fuels and a carrier gas and then against freshness, for example 5 min to supply oxygen again. As carbonaceous fuels, coke, brown coal coke, graphite, coal of various qualities and mixtures thereof have been found in the finely divided state of
proven up to about 1 mm grain size. The changeover valves have proven to be extremely reliable, for example, the valves could be used over 100,000 batches in the described mode of operation without interference.

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 the known valves are installed 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 a further control line. These lines must be brought to the converter via a rotating union in the converter pivot.

With the changeover valve according to the invention, these disadvantages are avoided since the application medium in the converter, namely oxygen, is used directly for valve control becomes. An additional control medium or an electrical line is therefore unnecessary. The oxygen is brought up to the changeover valve with the network pressure, ie the upstream pressure. The full oxygen admission pressure, normally in the order of 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, only 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, also determines the cross-section of the oxygen opening and 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, ie when the oxygen supply is switched off and the line is released, the changeover valve according to the invention switches over with the help of 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 pressure, e.g. B. 2o bar, and the oxygen pressure reduction, in which the switching process is triggered, is 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 4th bar, fixed in the changeover valve and is consequently, for example, 6 bar. This triggering of the switching process by means of a pressure difference above the oxygen blowing pressure of the nozzle which can be selected within the specified limits of 0.5 to 10 bar has the advantage that, with 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 effected by a spring or by means having the same effect, 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 preferably sealed gas-tight against the parts through which fuel flows.

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

The device according to the invention is now based on egg ner exemplary embodiment explained with reference to the drawing.

The figure shows a longitudinal section through an embodiment of the changeover valve according to the invention.

The changeover valve comprises a stationary housing 1 (shown hatched), with an oxygen feed line 3, in which the oxygen pressure prevails when oxygen is supplied to the nozzle tube 4. In the position of the movable valve body 5 (shown hatched) 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 a conveying gas for the pulverized carbon, e.g. B. coke, nitrogen or inert gas, e.g. B. Argon. The conveying 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 form, for. B. 2o 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 the sealing means 8 in cooperation with the contact surface 9. The oxygen opening cross section 1 ₀ is released and oxygen flows into the nozzle tube 4. To the desired To achieve pressure reduction from the oxygen pre-pressure (2o bar) to the oxygen nozzle pressure, for example 3 bar, the oxygen opening cross section 1o can correspond through different bore diameters 1o in the perforated disk of the throttle element 11 be set accordingly.

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.

Constructive deviations from the described embodiment of the changeover valve are within the meaning of the invention, in particular as long as the essential feature of the invention, namely the valve control by means of the oxygen admission pressure, is realized.

Claims (10)

1. A method for introducing fine-grained, carbon-containing fuels, which are suspended in a carrier gas, and oxygen in an iron melt below the surface of the iron bath through nozzles arranged in the refractory masonry of the treatment vessel, characterized in that fuel and oxygen are passed alternately through the same inlet duct of the nozzle will. 2. The method according to claim 1, characterized in that during a treatment period of the iron melt is switched one or more times between fuel and oxygen. 3. The method according to claim 1 or 2, characterized in that the oxygen is introduced jacketed by gaseous or liquid hydrocarbons. 4. The method according to any one of claims 1 to 3, characterized in that the fuel and the oxygen is passed through a central tube through a concentric tube. 5. Device for introducing fine-grained, carbon-containing fuels, which are suspended in a carrier gas, and oxygen in a molten iron, characterized in that in a housing (1) with a fuel supply line (7), an oxygen supply line (3) and a nozzle tube (4 ) a displaceable valve body (5) is arranged, which releases the fuel opening cross section (6) or the oxygen opening cross section (10) and which is controlled by the oxygen supply line pressure. 6. The device according to claim 5, characterized in that the oxygen supply line (3) is in communication with a valve chamber which has a boundary wall (14) which allows a change in length of the valve chamber under oxygen gas pressure, the displaceable end of the valve chamber with a double-acting valve body (5) is connected, which on the one hand monitors the fuel opening cross section (6) and on the other hand the oxygen opening cross section (10), and the valve body (5) is preloaded so that the oxygen opening cross section (10) is closed. 7. The device according to claim 5 or 6, characterized characterized in that the valve body (5) is arranged coaxially in the fuel supply line (7). 8. Device according to one of claims 5 to 7, characterized in that the boundary wall (14) is formed by a bellows. 9. Device according to one of claims 5 to 8, characterized in that the oxygen-flowed parts of the device are sealed gas-tight against the fuel-flowed parts. 10. Device according to one of claims 5 to 9, characterized in that a throttle member (11) is provided which determines the oxygen opening cross section (10).

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