DE29924757U1 - Device for spraying fuel, preferably natural gas, and/or oxygen into an arc furnace has feed pipes for the natural gas and oxygen with various chambers and supports - Google Patents

Abstract

Device for spraying fuel, preferably natural gas, and/or oxygen into an arc furnace comprises a feed pipe (1), a feed channel (2) and a hole (3) for the fuel, a feed pipe (4) for the oxygen, a pressure chamber (5) containing a stamp (6), a throughbore (7), a deviating chamber (9), a chamber (10) with a slanted opening, an outlet nozzle (12), an axial piston rod (13) with a closing part (14), a support element (15), a compensating chamber (16), a release opening (18) connected to a cylinder (19), a feed pipe for cooling chamber (20), a water-cooled track (21) and a removal pipe for the cooling water.

Description

The The invention relates to a device for injecting fuel and / or Oxygen in a metallurgical furnace and a metallurgical Melting furnace.

Worldwide In the last few years, the trend has gone, and steel production has increased To use electric arc furnace. The efficiency and thus the productivity as well The efficiency of the electric arc furnaces has been increasingly increased.

The Development of the melting process in electric arc furnaces was influenced by the use of fuel / oxygen burners. In addition to the use This burner is the evolution of the melting process of the Factors oxygen consumption, the increasing use of fossil fuels Fuels as carbon carriers, the use of contaminated scraps and increased environmental awareness.

In order to be able to reduce the specific electric energy consumption in the electric arc furnace, the exhaust gas losses, which account for up to 30% of the energy introduced, must be reduced as a priority. The exhaust of the arc furnaces contains a significant amount of chemical and thermal energy from imperfectly burned components such as carbon monoxide (CO); Hydrogen (H ₂ ) and other radicals (C _m H _n ). The unburned components are created in the start-up phase of smelting, when oil, grease and other scrap materials and fossil fuels burn. In most cases, not enough oxygen is available inside the arc furnace, so that, for example, carbon is only oxidized to CO.

The full Combustion of the individual components in the electric arc furnace is during Smelting of scrap makes it difficult, as a result of the scrap heap, which is located in the arc furnace after charging, z.T. just small combustion chambers to disposal stand and the firing conditions constantly change.

Of the Combustion process is essentially by the mixture determined between combustible components and the oxidation medium. This results in the requirement to provide an effective, i. intensive To create mixture formation in order to achieve optimal burnout.

From the DE 36 290 55 C2 It is known to arrange a plurality of inflators for oxygen in the upper region of the arc furnace, so that were burned by the resulting intense oxygen flow from the scrap originating unburned components. The oxygen inflators are adjusted so that the flow rates of oxygen are at least sonic velocity. To generate flow velocities greater than the speed of sound, Laval nozzles are to be used in which the pressure energy is converted into speed. Disadvantages are high production costs for the inflators and insufficient flow conditions for spraying, since the Laval nozzles operate optimally only in a clean state in a narrow range. Furthermore, high operating costs are caused by the high shielding gas required to keep the Laval nozzles free. Furthermore, the selected design of the nozzles of at least the speed of sound produces high oxygen momentum currents which lead to the destruction of the adjacent water-cooled furnace panel.

In the EP 0 627 492 B1 there is described an oxygen injection nozzle comprising an assembly consisting of an elongated body having a main direction defining the gas inlet passage connectable to an oxygen supply passageway and a head defining the gas exit passageway. The injection nozzles end at a certain angle in the furnace wall of the arc furnace. This form of injection nozzle has the disadvantage that large amounts of inert gas in the form of oxygen or air are needed to avoid clogging of the gas outlet passage. If oxygen is used as protective gas, high operating costs arise. The use of air as a protective gas to keep the gas outlet passage, it comes next to additional costs for control and safety technology due to the high throughputs of air to thermal losses in the electric arc furnace, which have a higher energy consumption.

In the US 5,572,544 discloses an arc furnace post-combustion process in which oxygen is injected for post-combustion of imperfectly burned components via a lance guided through the furnace door. A disadvantage of the positioning of the oxygen lance through the oven door is that very large amounts of false air, which flow through the furnace door in the arc furnace during the melting process, participate in the afterburning. Due to the high nitrogen ballast of the false air, low flame temperatures of the afterburning, because the inert nitrogen must be warmed up. As a result, both the post-combustion efficiency and the heat transfer by radiation reduce, so that the saving en electrical energy in kWh / t per m ^{3 of} oxygen used is reduced.

The previously known devices and Ver drive for afterburning in the electric arc furnace meet the demands made in terms of low operating costs for the inert gas to keep the lances and high levels of post combustion with high heat transfer by radiation during a longer oven travel insufficient.

Of the Invention is based on the object, the disadvantages of said Prior art overcome and a device for injection of fuel and / or oxygen in a metallurgical furnace, especially electric arc furnace, which make it possible the amount of inert gas and thus the operating costs of the inert gas for Keep the device free to reduce the melting performance of the oven increase and strengthened Use of cost-effective Scrap and fuels due to high post-combustion efficiencies at the same time high heat transfer by radiation to contribute to the saving of particular electrical energy.

According to the invention this Task by a device for injection of fuel and / or Oxygen in a metallurgical furnace, especially electric arc furnace solved, which Device a supply line for fuel, a feed channel for fuel and at least one oblique arranged hole for fuel, a supply line for oxygen, one Pressure chamber in which a stamp is located, at least one through-bore, a deflection space for Oxygen, a supply channel for oxygen, a chamber with at least one obliquely arranged opening, an outlet nozzle, an axial piston rod with a closure part, a support element, e.g. a bush, a compensation chamber, which is an elastic means contains a relief opening, which is in communication with a cylinder, a supply line for cooling water, a water cooled Trakt and a discharge line for cooling water wherein the over the supply line incoming Oxygen the outlet nozzle self-medium controlled by pressure on the punch, movement of the axial Piston rod and the closure part in the direction of the discharge opening and thus opening the bore and inclined opening opens.

The Achieving the greatest possible Saving of protective gas to keep the outlet nozzle of the device free is characterized according to the invention achieved that only in the melt phases, when oxygen is needed, the outlet nozzle through the inflowing Oxygen is opened with medium control. This is advantageous possible, in natural gas / oxygen operation outside the outlet nozzle a Form a flame, the one related to the combustion performance Pulse current of 4 to 20 N / MW, preferably 6 to 15 N / MW generated. The invention also favorable conditions are created been that the outer diameter the device can be sized small.

By an arrangement and dimensioning of the outlet nozzle with a Aspect ratio of Fuel hole to the oxygen opening in the range of 0.45 to 0.7 and in particular at a value of about 0.59 is advantageous achieved that the combustion ratio in dependence be adjusted by oxygen content in the oven between 0.9 to 2.0 can, so in the entire control range creates a stable flame.

It is provided that the exhaust nozzle made of copper.

It is for the closure part a high temperature resistant material such as high temperature resistant steel, preferably a nickel-base alloy such as Inconel used.

To invention, it is found in a metallurgical furnace, in particular electric arc furnace with at least one electrode, as advantageous, at least one device for injecting fuel and / or oxygen, in particular according to claim 1, in the range of Hot gas manifold in the wall of the furnace with an inclination angle of about 30 ° to the horizontal down and tangent in the space between the electrode and to arrange the wall of the furnace.

Especially it is advantageous in a metallurgical furnace two devices for injection of fuel and / or oxygen below the hot gas manifold so to arrange that with superimposed Oxygen flow coverage the main exhaust stream is mixed.

at the afterburning of products from incomplete combustion in a metallurgical furnace, in particular electric arc furnace at least one electrode, with at least one fuel / oxygen burner is in Burner operation a fuel / oxygen pulse stream less than 45 N and / or in pure oxygen mode an oxygen pulse stream less than 90 N set. By the maximum fuel / oxygen pulse current of 45 N becomes a hazard the neighboring water-cooled Stove panel excluded. The process reduces consumption of electrical energy and increased at the same time the melting capacity of the arc furnace, the components produced in the oven from imperfect combustion almost complete to be burned.

In particular, by an entprechende dimensioning of the outlet nozzle is on the Cross-section related pulse current density of 0.8 to 8.0 N / cm ² , preferably 1.1 to 6.0 N / cm ² , achieved. Advantageously, a maximum oxygen momentum flux of 90 N is produced in pure oxygen mode, thereby avoiding a hazard to the adjacent water-cooled furnace panel.

It proves to be advantageous that the flow conditions of the fuel / oxygen flame and the injected into the furnace oxygen jet through the device does not change and thus make crucial economic afterburning possible. It is particularly advantageous that according to an embodiment of the Invention, the direction of the fuel / oxygen pulse stream and / or oxygen pulse stream set opposite to the direction of the movement pulse of the main exhaust gas flow becomes. There are fuel, preferably natural gas, and / or oxygen in the area of the hot gas manifold the oven wall with a tilt angle of 30 ° to the horizontal down and introduced tangentially into the space between the electrodes and the furnace wall. This is advantageous for the fact that Fuel / oxygen pulse stream with a maximum of 45 N and the oxygen pulse stream with a maximum of 90 N opposite to the movement pulse of the main exhaust gas flow acts. This results in a good mixing of the exhaust gases with the free oxygen is achieved, resulting in almost complete afterburning.

It is also advantageously achieved that in phases of the melting process, in which no oxygen is needed, the outlet nozzle remains almost closed and only small amounts of inert gas to keep the outlet nozzle of the device for injection of less than or equal to 20 m ³ / h are required.

It in fuel / oxygen operation, a combustion ratio of 0.9 to 2.0, so that in an accelerated Schrotteinschmelzen and Burning a swath into the scrap heap depending on guaranteed by the oxygen content can be. Free oxygen can be blown into the scrap heap and transfer the energy generated from the post-combustion to the scrap become. It begins the melting of the insert in an electric arc furnace using the electrode and cutting a swath with the help of the device according to the invention simultaneously.

It the device is after clearing the lane as pure Oxygen lance operated. This allows an economic Afterburning with low specific oxygen consumption Simultaneous protection of the adjacent water-cooled stove panel.

The combustion ratio between fuel, preferably natural gas, and oxygen and the Oxygen flow rates may vary depending on the exhaust gas analysis be managed.

It is intended to use natural gas as fuel for the device.

Advantageous will the device for a smelting process of Cast iron, metal alloys and / or molten metal used.

Further will the device for post-combustion of products from incomplete combustion, in particular carbon monoxide used in metallurgical smelting furnaces.

Of the However, use is not limited to metallurgical smelting furnaces. Much more can the device for post-combustion of products from incomplete combustion, especially carbon monoxide, in other high-temperature processes, e.g. in a waste incineration, in particular hazardous waste incineration, be used.

The Invention will be described below with reference to an embodiment and a drawing (Fig.) Example closer explained become.

The Figure shows a section through a device for injecting Natural gas and / or oxygen in open Position.

The device for the injection of natural gas and / or oxygen consists of a supply line for natural gas 1 , a supply channel for natural gas 2 , and at least one obliquely arranged bore for natural gas 3 , a supply line for oxygen 4 , a pressure chamber 5 in which is a stamp 6 located, at least one through hole 7 , a deflection space for oxygen 8th , a supply channel for oxygen 9 , a chamber 10 , with at least one obliquely arranged opening for oxygen 11 , an outlet nozzle 12 , an axial piston rod 13 with a closure part 14 , a socket 15 for supporting and guiding the axial piston rod 13 , a compensation chamber 16 that a spring 17 contains, a relief opening 18 that with a short-stroke cylinder 19 is in communication, a supply line for cooling water 20 , a water-cooled tract 21 and a discharge line for cooling water 22 ,

The over the supply line 4 supplied oxygen enters the pressure chamber 5 , this is the stamp 6 in the compensation chamber 16 pressed, so that the passage bore 7 becomes free. At the same time, the closure member moves 14 that over the axial piston rod 13 with the stamp 6 connected is, in the direction Kurzhubzylinder 19 , This will be in the chamber 10 the opening 11 for oxygen and the bore 3 released for natural gas (open position).

The oxygen flows through the pressure chamber 5 , then through the through hole 7 in the deflection space 8th and further through the supply channel 9 over the opening 11 in the chamber 10 and continue through the outlet nozzle 12 in the oven.

The over the supply line 1 supplied natural gas passes through the supply channel 2 into the hole 3 and forms with the oxygen outside the exit nozzle 12 a flame producing a combustion power pulse current of 4 to 20 N / MW.

The aspect ratio of the opening 11 to the hole 3 is in the range of 0.45 to 0.7. This achieves stable flames with combustion ratios between 0.9 and 2.0. In combustion operation, a maximum natural gas / oxygen pulse current of 45 N is generated, so that a threat to the adjacent water-cooled furnace panel is excluded.

In the oxygen operation of the device is a on the cross section of the outlet nozzle 12 referred pulse current density of 0.8 to 8.0 N / cm ³ generated, the max. Oxygen pulse current of 90 N is not exceeded.

The device for the injection of natural gas and / or oxygen can be used at maximum furnace temperatures, since the outlet nozzle 12 with a water-cooled tract 21 surrounded, wherein the cooling water via the supply line 20 flows in and over the discharge line 22 flows.

The previously described device was in an electric arc furnace, for example in a process for post-combustion of imperfect products Combustion, used.

Two devices were placed in the region of the hot gas manifold in the furnace wall at an angle of 30 ° to the horizontal downwards and tangentially in the space between the electrode and the furnace wall, so that the main exhaust gas flow is detected with superimposed oxygen flow cover. The devices are operated in the initial phase of melting as a fuel / oxygen burner. The combustion power per device is specified according to the scrap ratios between 1.0 to 2.5 MW. The combustion ratio is set between 0.9 and 2.0 depending on the oxygen content in the furnace. After collapse of the scrap column, the natural gas supply is turned off and oxygen injection rates in adaptation to the oxygen content in the exhaust gas between 13 to 30 m ³ / min. set. This corresponds to specific oxygen consumption of 4 to 8 m ³ / tfl.

For a certain, relatively short period of time, typically a few seconds, the entire gas supply (natural gas and oxygen supply) is interrupted so that the closure part 14 towards the outlet nozzle 12 moved and in the chamber 10 any adhering contaminants from the chamber 10 out suppressed.

In melt phases in which there are no unburned components in the exhaust, only very small amounts of oxygen are passed over the device, so that the outlet nozzles 12 the devices by means of the closure member 14 be almost completely closed. In these phases, the devices for keeping the outlet nozzle 12 with less than or equal to 20 m ³ oxygen per hour and device acted upon.

In the afterburning of products from incomplete combustion Nachverbrennungswirkungsgrade of greater than or equal to 85% is achieved, with a savings potential of electrical energy per m ^{3 of} oxygen greater than or equal to 2.5 kWh is achieved.

With the device, the advantages of an additional saving of electrical energy by higher Nachverbrennungswirkungsgrade and a saving of inert gas amounts and thus reducing the operating costs is achieved over the devices and methods of the prior art. The plant safety is increased, as deflagrations and explosions in the exhaust tract are avoided and there is the advantage of more constant performance data of the arc furnace, since the outlet nozzle 12 is not contaminated and thus constant flow conditions can be achieved.

Claims (5)

Device for injecting fuel and / or oxygen into a metallurgical smelting furnace, in particular an arc furnace, which device has a feed line for fuel ( 1 ), a supply channel for fuel ( 2 ) and at least one obliquely arranged bore for fuel ( 3 ), a supply line for oxygen ( 4 ), a pressure chamber ( 5 ), in which a stamp ( 6 ), at least one through-bore ( 7 ), a deflection space for oxygen ( 8th ), a supply channel for oxygen ( 9 ), a chamber ( 10 ) with at least one obliquely arranged opening ( 11 ), an outlet nozzle ( 12 ), an axial piston rod ( 13 ) with a closure part ( 14 ), a support element ( 15 ), a compensation chamber ( 16 ), which is an elastic means ( 17 ), a discharge opening ( 18 ) with a cylinder ( 19 ), a supply line for cooling water ( 20 ), a water-cooled tract ( 21 ) and a discharge line for cooling water ( 22 ), which via the supply line ( 4 ) inflowing oxygen the outlet nozzle ( 12 ) self-medium controlled by pressure on the stamp ( 6 ), Movement of the axial piston rod ( 13 ) and the closure part ( 14 ) in the direction of the discharge opening ( 18 ) and thus release of the bore ( 3 ) and obliquely arranged opening ( 11 ) opens. Apparatus according to claim 1, characterized in that the cross-sectional ratio of the opening ( 11 ) to the bore ( 3 ) Is 0.45 to 0.7, preferably about 0.59. Apparatus according to claim 1 or 2, characterized in that the outlet nozzle ( 12 ) consists of copper. Device according to one of claims 1 to 3, characterized in that the closure part ( 14 ) consists of a high temperature resistant material, preferably a nickel-based alloy, such as Inconel. Metallurgical smelting furnace, in particular electric arc furnace with at least one electrode, in which metallurgical furnace at least one device for injecting fuel and / or Oxygen, in particular according to claim 1, in the region of the hot gas manifold in the wall of the furnace with an inclination angle of about 30 ° to the horizontal down and tangent in the space between the electrode and the wall of the furnace is arranged.