JPS6040487B2 - A device that introduces fine fuel containing carbon into a molten iron bath. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes a fuel containing finely divided carbon such as coal and coke dust suspended in a carrier medium and oxygen disposed within the refractory brickwork of a converter vessel. This invention relates to a device for introducing subsurface iron melt through a tuyere.

It is known to introduce powdered or granulated solid material into the iron melt by means of a carrier gas.

For example, a lance is used for blowing the powdered or granulated solid material into the molten grate, and the outlet opening of this lance is such that the powdered or granulated solid material is introduced into the molten grate with a power pulse. Either the lance is extended to approximately the surface of the grate, or the lance is submerged into the molten iron grate. Furthermore, tuyere structures are known which are placed in the refractory brickwork below the surface of the molten metal and through which solid substances suspended in the carrier gas are fed to the molten metal.

For example, German Patent No. 2 316 768 discloses a method and apparatus for refining molten metal, in which oxygen and powdered lime are supplied to the molten metal through tuyeres arranged below the surface of the molten metal. Solid carbon carrier is also fed through other tuyeres.

A multi-opening tuyere may be provided, in which case one tuyere is filled with carrier gas, carbon or powdered ore, and the other tuyere is filled with smelting gas and powdered lime. Ru. West German Patent No. 240,154 P discloses a method for smelting sponge iron. In this method, the components, ie, oxygen, granulated carbon, and fine-grained sponge iron, are fed to the molten metal below the vessel surface, for example, through coated gas tuyeres. The tuyere has a number of feed channels, where, for example, oxygen flows through the inner channel, carbon flows through the central channel, and iron flows through the outer channel. The carbon and sponge iron are suspended in a suitable carrier gas, such as carbon monoxide. West German Patent No. 2520-3 discloses a method and apparatus for continuous gasification of coal. placed in fireproof brickwork, resulting in
Sample material, preferably fine coal, and oxygen are fed into the iron melting bath through tuyeres placed below the surface of the iron melting bath which are subjected to the same amount of wear. The carrier gas for the carbon can be either an inert gas, nitrogen, C02 or water vapor. The encrusting material may be passed through a multi-passage tuyere, preferably with a D-pipe. This West German patent describes for the first time the possibility of mixing test oxygen and carbon in a tuyere located a short distance in front of the orifice. West German Patent No. 2
No. 72-57 discloses a method and apparatus for making steel.

In this case, a carbon-containing material is introduced into the molten metal below the surface, and an oxidizing gas is also introduced into the vessel. The carbon-containing material is blown through a blowpipe by a carrier gas. The carrier gas may be a reducing, oxidizing or inert gas. In this method, oxygen is usually supplied to the waste container through a water-cooled lance. However, it is also possible to supply the oxygen by injection through a blowpipe or by means of a lance submerged in the melting chamber.
The West German patent provides the following explanation regarding this point. "If a blowpipe is used to inject materials containing oxygen and/or carbon, the blowpipe should include two or more concentric pipes and a circular fluid screen surrounding the main injection pipe. May have.

This screen flow medium can be an inert gas or liquid, such as a hydrocarbon gas or liquid, or an oxidizing gas or liquid, and the soot content is kept as low as possible in order to prevent lining wear and blowpipe sufficiency from clogging the blowpipe. selected to be The blowpipe is configured to supply oxidizing gas and carbon-containing material. The first example of this West German patent publication states that particulate graphite is injected at a rate of 3.5 kilograms per minute for 17 minutes. The blowing pipe used to blow the carbon had a circular cross section and was as follows. Screen gas: air at a rate of 7 cubic meters per hour; carrier gas: argon at a rate of 30 cubic meters per hour. The core diameter of the flow pipe was 7 mm and the annular passage was 1 mm. The method for introducing carbon-containing fuel into an iron melt bath is similar insofar as the finely divided solid material is suspended in a carrier gas and fed to the molten metal while being separated from oxygen by other feed passages. ing.

The cross section of the supply channel is adapted to the quantity to be conveyed and is therefore small, the length of the blowing pipe being, for example, 7 mm. However, as the aforementioned cross-sectional area for conveyance becomes smaller, the risk of clogging increases. If fine-grained fuels with different particle sizes and particle size distributions are used for economic reasons with a high bagging ratio of solid material to carrier gas, there is a risk of agglomeration causing blockages in narrow supply pipes. It makes me smile. Another difficulty in the case of the known introduction method is that when no fuel is conveyed, e.g. when a desired low final amount of carbon is set, it is difficult to block the feed channel during the finishing refining stage of finishing refining of molten steel. The problem is to prevent it from happening.

During refining, the carrier gas typically flows through the feed passage without solid material to prevent molten metal from entering the tuyere. However, the carrier gas removes some heat from the molten metal and, moreover, depending on the type of gas used, it can have an undesirable effect on the composition of the steel, for example due to increased nitrogen levels in the finished steel. In actual work, for example, when operating an iron melting reactor that generates gas for several months, and when producing 1000 melts of copper, for example, when the blade □ is clogged. Any repair work carried out results in lost manufacturing time and creates a significant cost penalty;
It has been found that it is particularly important to operate supply channels for carbon-containing fuels reliably and trouble-free over long periods of time. Therefore, if fine particulate fuel containing carbon such as coal and coke dust is introduced into the iron smelter, a reliable and trouble-free supply of the fuel below the melting surface is guaranteed over a long period of time. It is also an object of the present invention to provide a device in which the tuyeres are not obstructed and the tuyere remains open while no fuel is being delivered.

Another object of the present invention is to provide an apparatus for introducing fine particle fuel containing carbon suspended in a carrier gas and oxygen into a molten iron tank, the housing having a fuel supply line, an oxygen supply line, and a wing pipe. The valve member has a movable valve member located at the cross section of the fuel and oxygen openings and which is regulated by the pressure in the oxygen line.

The process of the invention is characterized by high reliability of operation and the tuyere through which the carbon-containing fine-grained fuel is introduced below the surface of the melt is not clogged. As soon as irregularities occur with respect to the throughput of carbon-containing fuel, for example when the conveyance rate decreases, the fuel conveyance is briefly switched to oxygen and the tuyere channels are blown. The deposits that eventually form at the tuyere orifice causing the blockage are burned away by the flow of oxygen. For example, a very short oxygen blowing time of 0.1 to about 2 minutes is sufficient to blow open wings. The time of oxygen blowing can be varied at will, in particular it can be extended before the supply of fuel and carrier soot is started again. According to the invention, switching from fuel to oxygen takes place several times within a short period of time. This operating form shortens the oxygen blowing time and is sometimes significant. For example, after the sand shortening in step 1 and oxygen blowing, if the fuel supply is again carried out without problems, it is no longer necessary to add oxygen. If this is not the case, short oxygen blows are performed as many times as necessary. The changeover from oxygen blowing to the conveyance of floating bodies, such as nitrogen and coal dust, takes place in the immediate vicinity of the wing assembly flange, in any case in a processing vessel, for example in an iron molten bath reactor or in a converter for producing steel. This is carried out with almost no inertia by means of a suitable reversing device placed directly at the bottom of the inverter. A simple type of vane for introducing suspended particles of carbon-containing fuel and carrier medium, as well as oxygen, has two concentric pipes, in which the fuel and oxygen are passed through a central pipe. flows alternately.

An annular passage formed between the center pipe and the second center pipe is filled with gas and/or liquid carbonization, e.g. Filled with hydrogen. The tuyere is usually provided integrally below the surface of the molten material within the refractory brickwork and necessarily backfires at the same rate as the brickwork itself. According to the invention, the danger of the wings being blocked when carbon-containing powder fuel is introduced into the iron melting tank is practically eliminated, and it is actually possible to The required blow cross section arrangement is sufficient. In other words, it is no longer necessary to additionally arrange separate fuel supply tuyeres for safety reasons. For example, in the case of converter operation with a basic oxygen process, it has been found that it is sufficient to use only two of the lq solid oxygen supply tuyeres at the bottom of the converter for feeding fine coal or coke. are doing. Approximately 2000 kilograms of coal dust are fed into approximately 65 tons of molten iron within 10 minutes using these two vanes. For example, nitrogen can be used as the carrier soot, and when this nitrogen is used, the rate of filling with coal dust is 12 kilograms per cubic meter of nitrogen. The addition of fuel improves the thermal balance and thus increases the refining capacity of scrap when producing steel. In the known method of introducing a fuel containing finely divided carbon into a molten iron supply pipe having an internal diameter of 10 mm, each of the above-mentioned IN solid oxygen supply tuyeres is used as a conveying passage for a fuel carrier gas suspension. placed in the center.

Very commonly, the oxygen supply tuyere itself consists of two concentric pipes, the inner pipe having an internal diameter of 24 millimeters and serving as the supply pipe for oxygen or oxygen and powdered lime. The arrangement of the fuel supply passage in the oxygen pipe has been found to be disadvantageous for a number of reasons. 1
Although the installation and maintenance of zero fuel supply pipes is technically expensive, it is still possible to prevent a failure of an individual supply channel, e.g. for carbon-containing fuel, in the event of a blockage. This method of supplying fuel is required to maintain a sufficient conveyance diameter in order of operation.

Blockages in individual fuel supply passages have hitherto occurred in almost every case. Furthermore, it has been found to be particularly undesirable to have to keep the passages open with carrier gas when the fuel supply is cut towards the end of the refining process. The nitrogen used to deliver the fuel resulted in an undesirably high nitrogen content in the molten steel. Other carrier gases, such as argon or methane, are expensive and require additional soot-based conversion converter units and costly installation work. Nitrogen is very easily used in basic oxygen converters. Additionally, carrier gas bubbles can degrade the thermal balance of steel production when not filled with fuel. The heat for heating the carrier gas is consumed as energy for refining the scrap. For example, according to the method of the invention, West German Patent No. 2520
The safety of operation of the iron molten bath reaction diamond for continuous gasification of coal as disclosed in Madara No. 3 is further improved. In iron molten bath reactors of this type, large quantities of coal are converted into gases containing essentially CO and CO2. sample material,
Coal dust and oxygen are normally supplied through tuyeres and from a number of similar pipes interposed below the surface of the iron melt.
Usually finely ground coal and carrier gas, e.g. suspensions with a C ratio, flow through a central pipe, oxygen flows through an annular passage surrounding the circular central pipe, and tuyere protection, e.g. natural gas flows through a separate annular passage. Flow through the passage. Normally these vanes work without failure, but sometimes deposits form in the orifice of the tuyere of the central pipe, which reduces the amount of coal dust that is delivered. However, rapid resolution of such failures is particularly important when delivering coal since the iron melt reactor should have a very uniform rate of gas production. By switching according to the invention from coal dust to oxygen in the fuel supply passage of the nozzle, normal coal supply is restored after a relatively short period of time, typically less than one minute, for example. A particularly advantageous application of the invention lies in its combination with the heat supply method in converter steelmaking as described in West German Patent No. P28 Madokahan 3.5.

In the production of copper by converter furnaces, heat is provided by carbon-containing fuels, and in particular these fuels have a high degree of efficiency due to high temperature measurement, which was not attainable until the time of their invention. Used in molten metal. The economical refining of solid iron carriers, such as scrap, is therefore considerably increased and even makes it possible to produce steel without liquid molten metal. In this method, oxygen for refining the molten metal and burning the fuel is simultaneously introduced into the converter below the surface of the melt and the gas jet is directed at the surface of the melt. Special coke, brown coal coke, graphitic coal of different qualities and mixtures thereof are used as carbon-containing fuels. These carbon-containing fuels are preferably introduced in powdered form together with a carrier gas into the molten iron of the converter below the surface of the molten bath. Nitrogen, CO, C or natural gas and inert gases such as argon have been successful examples as carrier gases.
According to the above-mentioned West German patent application, floating bodies with carbon-containing fuel and carrier gas are fed into a basic oxygen converter through one or more tuyeres, while individual tuyere The supply pipe is filled with a floating body having a carrier gas and fuel instead of oxygen. The method according to the invention has been able to overcome the drawbacks which existed hitherto and which were associated with the supply of molten iron or steel with fuel containing finely divided carbon.

While these drawbacks were disadvantages according to West German Samurai Application No. P28 Paper Group No. 3.5, they were extremely advantageous processes for heat supply. Apart from the advantages of the method according to the invention already mentioned, another advantage in producing steel should be noted.

Final refining by using one or more tuyere oxygen supply pipes in the basic oxygen step to supply carbon-containing fine-grained fuel during the fueling period and subsequent switchover to oxygen. For stages, ie stages without fuel supply, there is a concomitantly larger oxygen blowing cross section. Therefore, this refining time is shortened, resulting in a reduction in overall refining time.
This means other advantages in manufacturing steel. The method and apparatus of the invention are suitable for supplying various fine grain fuels, such as coal of various qualities, coke, brown coal coke, graphite, smelting residues and mixtures of these fuels.

The fuel is introduced in powdered or granulated form, and the particle size and its distribution can vary within a wide range. Inert gases such as argon, nitrogen, carbon monoxide, carbon dioxide, hydrocarbons such as methane, natural gas and water vapor are particularly suitable as carrier gases. The device of the invention is not limited to the introduction of oxygen, but can also be used to introduce other gases containing oxygen, in particular air, and mixtures of oxygen with other gases, in particular mixtures of oxygen and argon. Are suitable.

According to a preferred embodiment, in any tuyeres arranged below the surface of the molten bath in a processing vessel, such as a ferrous melt grade reactor for producing gas or a basic oxygen converter for producing steel. Some of these are used as feed tuyeres for carbon-containing fuels. The method of the invention will be explained in more detail with respect to the example of producing steel with increased amounts of scrap. Note that the present invention is not limited to this manufacturing example. The 60 ton basic oxygen converter is equipped with an IN picture vane □ at the bottom of the converter and one vane □ in the top wall of the converter above for top blowing of oxygen. 30 tons of scrap with 4.2 percent carbon, 0.6 g-cent silicon, 0. &g-cent manganese, 0.3% phosphorus, 0.03% sulfur and 12 degrees centigrade
44 tons of molten metal at a temperature of 50 degrees is charged.

Two of the bottom wings □ are provided for applying the method of the invention.

That is, fuel and oxygen are supplied alternately through the same supply passage of the tuyere. Approximately 10 per hour at the beginning of smelting
000 N cubic meters of oxygen are fed to the molten metal through eight bottom tuyeres, and the same amount of oxygen is fed to the molten metal through the top blow tuyeres of the upper converter down.

At the same time, 200 kilograms of powdered coke is produced every minute.
The kiln is fed through two bottom tuyeres along with 100 liters of nitrogen to the kiln. After about 10 minutes, the molten metal will melt).
2000 kilograms of coke are fed in this way and the two fuel supply tuyeres are switched to oxygen.

The smelting operation is completed after a blowing time of about 1 gram, followed by about 0.02/f-cent carbon, 0.1 percent manganese, and 0.025 g-cent phosphorus after about 2 minutes of corrective blowing. , with a composition of 0.02 percent sulfur and 16 degrees Celsius
Molten metal at 70 degrees is tapped.

The total charge follow-up time will be approximately 40 minutes.

In total, the molten metal contains 460 cubic meters of oxygen;
10 cubic meters of propane to protect the tuyeres,
150 liters of oil and heat the scraps for 2 minutes
00 kg of coke is supplied. The weight of the steel tapping charge will be 64 tons. It is clear that this mode of operation described by way of example can be modified in many ways, in particular with regard to the supply of carbon-containing fine-grained fuel. For example, in the case of a full basic oxygen converter, the fuel supply can be cut short and oxygen can be blown through the fuel supply passage. The method of the invention, in which the switching from fuel to oxygen and from oxygen to fuel occurs in the same tuyere track, can also be applied to other processes in which carbon-containing fuel is fed to molten iron.

The apparatus of the present invention for alternately introducing carbon-containing fine-grained fuel and oxygen will now be described in more detail.

The pressure in the oxygen supply system, i.e. generally around 20 bar.
Oxygen inlet pressure, which becomes equal to 100 mL, acts to reverse the valve.

Oxygen inlet pressure is generated within the valve itself until the tuyere oxygen blowing pressure is reached. When oxygen inlet pressure is applied, the movable valve member only opens the oxygen hole cross section of the vane.
0.5 without the applied oxygen inlet pressure being higher than the tuyere oxygen blowing pressure which can be set by the spring;
If the pressure is reduced by a predetermined pressure in the range of 10 bar, preferably 2 bar, only the fuel hole cross section to the vane □ is opened. In order to ensure a reliable switchover from fuel to oxygen and in particular to avoid having pipes in which fuel and oxygen flow in succession to each other, the inventive reversing valve is placed in close proximity to the converter tuyere, preferably in the converter. between the pivot and the tuyere, especially as a structural unit with the tuyere itself.

The reversing valve is preferably placed directly on the mounting flange of the tuyere. Reliable double-pipe tuyeres with protective media skins are usually used as feathers.

In this tuyere embodiment, oxygen normally flows through the central pipe. The reversing valve of the present invention allows oxygen and fuel to be supplied alternately through this tuyere passage. This means that in this case it is possible to switch from fuel to oxygen as many times as desired through the central tuyere pipe. The protective medium is an annular passage between the inner pipe and the second outer tuyere pipe in order to protect the tuyere against premature back combustion within the refractory brickwork with the tuyere normally located inside. flows through. Gases and/or liquids can be used as protective media. Preference is given to using hydrocarbons such as methane, natural gas, propane, butane, gas oil and other oils. The proportion of hydrocarbons with respect to oxygen throughput is low and lies between 1 and 5 weight percent. However, the use of the reversing valve according to the invention is not limited to this type of tuyeres, but is also suitable for use in conversion zones for switching from oxygen-containing media to fuel and/or pneumatically conveyed material.
It can also be used for tuyeres.

Reversing valves are used in combination with so-called circular two-lot tuyeres, as shown for example in DE 24 38 142. A preferred application of the reversing valve of the invention is in the operation of double pipe tuyeres, for example, in a total of IM solid tuyere installed at the bottom of a basic oxygen converter, two tuyeres can be operated for short periods of time with oxygen. and then for a longer period of time, for example 8 minutes, in suspension with carbon-containing pulverized fuel and carrier gas, and then at the end of the refining process, for example 5 minutes, and again with oxygen. Coke of different qualities in a finely crushed state down to approximately 1 millimeter, brown coal coke, graphite, coal and mixtures thereof are examples of successful carbon-containing fuels. The reversing valve has been found to be extremely reliable in operation and has been used for over 1000 charges without resulting in disassembly, as described above, for example. Media reversal valves that can be adjusted pneumatically or electrically are commercially available and commonly used. However, known valves for reversal require additional pipes for the regulating medium.
Directly equipping a converter for producing steel with the known valve poses difficulties due to the relatively high ambient temperatures, which can rise up to 300 degrees Celsius, and the need for further regulating pipes. . These pipes must be placed in the converter via a rotary transmission in the converter pivot. The above-mentioned disadvantages are avoided in the case of the reversing valve according to the invention, since the medium added to the converter, ie the element, directly controls the valve.

No additional conditioning media or electrical conductors are therefore required. Oxygen is delivered to the reversing valve at system pressure, ie, inlet pressure. The full oxygen inlet pressure, which is usually about 20 bar, is utilized in the valve for regulating the movable valve section. Other pressure values unrelated to the oxygen supply system are of course also suitable. Oxygen pressure acts within the valve of the movable valve member which closes the fuel hole cross-section and makes the reversing valve airtight.

In this position of the movable valve member, only oxygen can flow through the oxygen hole cross section to the tuyere. The oxygen hole cross section is sized to act as a throttle member and reduce the oxygen inlet pressure to the oxygen tuyere pressure. By reducing this pressure, for example from an input pressure of 20 bar to a pressure of 4 bar, the oxygen hole cross section also determines the flow rate of oxygen.
The oxygen hole cross section is fixedly adjusted by a reversing valve.

However, this setting is relatively easily changed according to the desired pressure conditions. The reversing valve of the invention is switched by the movable valve member as soon as the oxygen inlet pressure decreases, i.e. the pipe to which the oxygen is supplied is depressurized.

The oxygen hole cross section is hermetically closed and the fuel hole cross section is open. The pressure difference between the oxygen inlet pressure, e.g. 2 degrees and the decrease in the oxygen inlet pressure when the switching operation is initiated, is reduced by the spring of the reversing valve to the oxygen blowing pressure of vane □, e.g. 4
It is set to a value between 0.5 bar and 10 bar, preferably 2 bar, resulting in, for example, 6 bar. 0.5 higher than the oxygen blowing pressure of the blade
The initiation of this reversal process by a pressure difference within a given limit of 10 bar causes the movable valve member to move so that both oxygen and fuel are simultaneously in the vane passage when there is a slow pressure decrease in the oxygen inlet pressure pipe. This has the advantage that it does not take intermediate or irregular positions that can flow into the air. Preferably, the oxygen supply pipe passes through a valve chamber having a partition that changes the length of the valve chamber when oxygen gas pressure is applied, the movable end of the valve chamber monitoring the fuel hole cross section while monitoring the oxygen hole cross section. It is connected to a double-acting valve and the valve is preloaded so that the oxygen cross section is closed.

The valve member is preloaded by a spring or by other means capable of producing this effect, for example by pneumatic inlet pressure.

The valve member is preferably interposed coaxially within the fuel supply pipe.

The partition is preferably formed by bellows.

The portion of the member through which oxygen flows is preferably hermetically sealed to the portion through which fuel flows. Preferably a throttle member is provided which defines the oxygen hole cross section.

The apparatus of the present invention will now be described in detail with reference to embodiments shown in the accompanying drawings.

The accompanying drawing shows a longitudinal section through an embodiment of the reversing valve of the invention.

The reversing valve has a fixed housing with an oxygen supply pipe 3 (
In this fixed housing, the inlet pressure of oxygen prevails when oxygen is supplied to the tuyere pipe 4.

At the location of the illustrated movable valve village 5 (represented by longitudinal shading), no oxygen pressure is applied and the fuel hole is opened so that fuel, e.g. coal/nitrogen floats, can flow from the fuel pipe 7 to the wing pipe 4. Section 6 is opened. Nitrogen or an inert gas, such as argon, acts as a carrier gas for the pulverized carbon, such as coke.

When unloaded, the carrier gas has a pressure of approximately 3 bar and when fully loaded with 17 kg of carbon per cubic meter of N, the carrier gas has a pressure of approximately 12 bar. As soon as the oxygen supply pipe 3 is pressurized with an oxygen inlet pressure of, for example, 20 bar, the movable valve member 5 moves in the direction of the fuel supply pipe 7 and seals the fuel hole cross section 6 by means of the sealing member 8 cooperating with the support surface 9. Close.

The oxygen hole cross section 10 is opened and oxygen flows into the tuyere pipe 4. By varying hole diameters in the raised disk of the throttle member 11, the oxygen hole cross section 10' can be adjusted to achieve the desired pressure reduction from the oxygen inlet pressure (20 bar) to the oxygen vane pressure, e.g. 3 bar. Correspondingly set. As soon as the oxygen inlet pressure decreases by an adjustable pressure difference of 0.5-10 bar (0.5-10 bar blowing pressure) higher than the blowing pressure of vane □4, the movable valve member 5 Return to the illustrated position and open the fuel hole cross section 6.

The pressure difference for starting the reversing operation is set in this embodiment by the force of the spring 13. It should be noted that the section through which the oxygen flows is closed gas-tightly when the fuel is conveyed, and the metal bellows 14 effect the necessary movement of the movable valve member 5 during reversal. Changes in the structure of the reversing valve may be made without departing from the scope of the invention, especially as long as the essential feature of the invention, namely regulation of the valve by oxygen inlet pressure, is realized.

The simplified illustration of the drawing is a longitudinal cross-sectional view of an embodiment of the invention.

1...Housing, 3...Oxygen supply pipe, 4...
- Tuyere pipe, 5... Movable valve member, 6... Fuel hole cross section, 7... Fuel pipe, 8... Seal member, 9...
- Support surface, 10...Oxygen hole cross section, 11...Throttle member, 13...'Imitation, 14...Metal bellows.

Claims (1)

[Claims] 1. An apparatus for introducing fine particle fuel containing carbon suspended in a carrier gas and oxygen into a molten iron bath,
A movable valve member is disposed within a housing having a fuel supply pipe, an oxygen supply pipe and a tuyere pipe, the valve member opening a fuel hole cross section or an oxygen hole cross section and controlled by the pressure of oxygen in the supply pipe. An apparatus for introducing fine particle fuel containing carbon into a molten iron bath. 2. The oxygen supply pipe communicates with a valve chamber having a partition that changes the length of the valve chamber under the action of oxygen gas pressure, and the movable end of the valve chamber monitors the cross section of the fuel hole while monitoring the cross section of the oxygen hole. 2. Device according to claim 1, characterized in that it is connected to a monitoring dual-acting valve member, said valve member being preloaded so that said oxygen hole cross-section is closed. 3. A device according to claim 1 or 2, wherein the valve member is arranged concentrically within the fuel supply pipe. 4. The device according to any one of claims 1 to 3, wherein the finishing cut is formed by a bellows. 5. The device according to any one of claims 1 to 4, wherein the portion of the device through which oxygen flows is hermetically sealed from the portion through which fuel flows. 6. The device according to any one of claims 1 to 5, which is provided with a throttle member that determines the oxygen cross section.