DE102012017066A1 - Shaft furnace i.e. cupola furnace, for melting e.g. raw material, has outlet for combustion gases and arranged above feeding aperture, and oxygen supply and ignition device arranged below aperture during functional alignment of furnace - Google Patents

Abstract

The furnace (1) has a shaft (10) in which raw material is melted. A feeding aperture (12) feeds the material to the shaft. A wind system (15) provides combustion air. An over-top outlet (13) is provided for combustion gases, where the material is fed upwardly into the shaft through the aperture during functional alignment of the furnace. The outlet is arranged above the aperture, and an oxygen supply and ignition device (14) is arranged below the aperture during functional alignment of the furnace. The ignition device has a burner i.e. oxygen burner. An independent claim is also included for a method for operating a shaft furnace.

Description

The invention relates to a shaft furnace and a method for operating a shaft furnace. For the afterburning of coal monoxide located in the shaft, oxygen is supplied and ignited at a position between the feed opening of the shaft furnace and above a maximum or actual filling level.

Shaft furnaces, in particular cupola furnaces, are used to melt feedstock such as pig iron, cast iron, steel scrap or other alloys. In most cases, the coke is ignited in the hearth of a shaft of the respective shaft furnace; For example, the coke can be made to glow by means of a gas burner. Subsequently, the melted material can be introduced into the shaft together with coke and additives in the shaft to the burning embers by a feed opening located at the upper end of the shaft. In this case, air, which was preferably previously enriched with oxygen, supplied via tuyeres above the hearth in the shaft (fed into the molten zone). From the EP 0 762 068 A1 and the DE 10 2008 048 779 A1 is particularly known to use a conveyor, the supply of which generates a negative pressure and thus sucking the air required for the combustion of the wind system of the furnace. effects (Treibdüsen injection method (TDI) or High Efficiency Furnace (HEF) method with wind system (HEF-W)). Alternatively, top gas can be sucked out of the bottom layer (so-called HEF-G process).

Combustion of fuels produces combustion gases, also referred to as "gassing gases," which in particular contain toxic carbon monoxide. So that as little as possible of these gases gets into the environment, the gassing gases are withdrawn and cleaned. In the so-called "lower-gas extraction", the top gases are taken off below, and in the "top-gas extraction" above the feed opening of the shaft furnace. Also combinations of both technologies are known.

The publication DE 10 2008 048 779 A1 discloses a method and shaft furnace in which a portion of the withdrawn gases are returned to the shaft furnace along with additional oxygen. In this way, a coke saving of up to 25% can be achieved.

With such a top gas recirculation, a part of the combustion air from the wind system of the furnace is sucked. Due to the increased technical oxygen content in this Ofenfahrweise can be dispensed with a significant proportion of furnace wind, thus reducing the total amount of blast furnace gas and the carbon monoxide in the top gas increases (lower gas volume, higher carbon monoxide concentration).

In the case of undergassing, part of the high-energy storm gases are fed to newly-developed systems (top gas burners). Thus, part of the primary energy used can be reduced, in most cases the foundry coke used.

The part of the top gas, which is not extracted by a top layer, passes through the so - called bottom suction to various gas purification systems, to the top gas afterburning and can be used in most cases as energy for various heat (energy) - recoveries. This can be used in the form of use for heating the hot blast or for internal or external hot purposes (industrial water, electricity).

The present invention has an object to provide a technology to reduce harmful shaft furnace emissions, which are sucked through the top layer, in particular those of carbon monoxide and u. a. those of benzene. This is intended in particular to achieve an odor reduction in the plant environment.

Disclosure of the invention

According to the invention, a shaft furnace and a method for operating a shaft furnace according to the independent patent claims are proposed.

The shaft furnace according to the invention comprises a shaft in which metallic material can be melted. The shaft furnace comprises a feed opening (also called the charging or charging opening), through which the material can be introduced from the top into the shaft when it is properly aligned. In the stated orientation, the shaft furnace above the feed opening at least one outlet for combustion gases (in particular blast furnace gas). The shaft furnace according to the invention further comprises a device for supplying (preferably technical) oxygen and for ignition, which is arranged below the feed opening when the shaft furnace is in the proper position. The latter is advantageously designed to ignite with the supplied oxygen enriched blast furnace gas. The device may additionally comprise an oil or gas burner or an oxygen burner.

The method according to the invention for operating a shaft furnace comprises melting feedstock in the shaft furnace. The shaft furnace has a feed opening and above the feed opening at least one trigger for combustion gases. Below the feed opening, top gas is enriched in the shaft furnace by supplying (preferably technical) oxygen and ignited according to the invention.

By supplying oxygen according to the invention above the column of material and below the feed opening, the high-energy blast furnace gas can be ignited by means of an ignition source and then the proportion u. a. almost completely burned by carbon monoxide. The hot rising exhaust gases are mixed at the feed opening with the incoming secondary air and cooled and thus pass through the exhaust gas cooler and the filter to the chimney. The CO concentration at the exhaust stack of systems with u. a. Obergichtabsaugungen can be reduced so many times.

The fact that the oxygen is supplied below the feed opening for igniting the top gas leads to a "natural" afterburning of the combustible constituents of the top gas. Combustion of the gassing gases after mixing with false air behind the discharge opening would no longer be possible due to the dilution effect.

Preferred embodiments are disclosed in the subclaims, the present description and the drawing.

The present invention relates to all types of shaft furnaces, but is particularly suitable for cupola furnaces. The shaft furnace according to the invention is preferably designed for melting cast iron, mineral wool, copper, lead and / or aluminum.

In a preferred embodiment, the device for supplying oxygen and for igniting comprises a gas burner (eg a propane or natural gas burner) or a gas burner or gas-oxygen burner. Preferably, the burner is arranged to ignite during a melting process at regular intervals or to burn continuously.

In an advantageous embodiment of the method according to the invention, the ignition of the enriched top gas is ignited by a corresponding burner.

Such a burner allows a simple control of the ignition and / or combustion, for example by controlling a fuel gas supply to the burner. The burner is preferably used only to initiate the combustion reaction. This can be done by a continuous burning or by a repeated, preferably periodic ignition of separately supplied fuel gas, for example in the immediate vicinity of the position at which the oxygen is supplied to the shaft. After igniting the top gas by means of oxygen, the top gas burns with the carbon monoxide so preferably alone, d. H. without additional energy supply. The ignition gas of the burner can in turn be oxygen.

Particularly preferred is an embodiment of the shaft furnace, wherein the device for oxygen supply and ignition in the proper orientation of the shaft furnace in the upper half, in the upper third or in the upper quarter of the shaft or above a provided for a melting operation maximum filling height of the shaft is arranged , A maximum filling height can be specified in particular by a manufacturer of the shaft furnace and / or mark a height of the shaft, up to which it can be charged during a melting process (meaningfully, that is without impairing the melting process or endangering the shaft furnace environment). In particular, a maximum fill level may be determined by the overall height and / or shape of the shaft and / or (eg, resulting) air or material flows in the shaft.

Accordingly, an embodiment of the method according to the invention is advantageous in which the oxygen supply and the ignition of the top gas is effected by means of the oxygen above a level in the shaft. The level is the current level of the shaft with feed and / or fuel; it is preferably at most three quarters of the total height of the shaft, or at most two thirds or at most half the total height of the shaft, or at a given maximum filling height of the shaft, to which the shaft can be filled, without any disadvantages in operation of the shaft furnace are to be expected.

Since the supply of oxygen in these embodiments takes place above the filling level of the shaft furnace, no metallurgical work is performed by the combustion, so that the metallurgical properties of the shaft furnace insert do not change.

Short description of the figures

1A schematically shows an embodiment of the shaft furnace according to the invention with a combination of Obergicht- and Untergichtabsaugung.

1B schematically shows an embodiment of the shaft furnace according to the invention with a Obergichtabsaugung.

Embodiments of the invention

In 1A is an example of a shaft furnace 1 shown a manhole 10 in which feedstock (eg, cast iron, mineral wool, copper, lead, and / or aluminum) can be melted. The feed may be co-fired with fuel (eg, coke) through a feed port 12 be introduced into the shaft. Molten material can be taken from a drain, not shown.

The illustrated shaft furnace 1 includes a nozzle 18 and a wind system 15 to provide combustion air. The wind system includes a supply line 17 to a fan and is part of a motive nozzle injection device 16 , About the nozzle 18 can be a partial flow of combustion air in the wind system 15 can be entered in the shaft. Preferably, this suction is enhanced by adding a conveyor.

Above the feed opening 12 the shaft furnace shown has a trigger 13 for gassing gases on; In this positioning one speaks of a Obergichtabzug. Through the deduction 13 withdrawn top gas can be supplied to a combustion chamber, not shown, and burned there. The released heat can be used, for example, for heating gas (eg air or oxygen) to be supplied by the shaft furnace.

Part of the deduction 13 withdrawn overhead gas, however, can be fed to the shaft again via a return line, not shown. In this case, the top gas is preferably mixed by means of a device with oxygen.

The shaft furnace shown 1 can be filled to melt feedstock up to a maximum fill level. This maximum fill level in the 1 shown schematically and with the reference numeral 11 may be specified by the manufacturer of the shaft furnace and / or marked boundary, the z. B. can result from the shape of the shaft. In the use of the shaft furnace whose level is therefore below or at most at the same height as the maximum level.

Between the maximum fill level 11 and the loading opening 12 points the shaft furnace 1 a device 14 for oxygenation and ignition. With it, the blast furnace gas can be enriched with oxygen and then ignited. The apparatus comprises an oxygen injection and an ignition device, preferably an oil or gas burner (eg a natural gas burner), expediently with combustion air supply, or an oxygen burner. With the ignition device, the blast furnace gas (in particular the carbon monoxide component) can be ignited together with the supplied oxygen and then burns essentially independently. In other words, the top gas flowing out of the shaft is enriched with oxygen and ignited with the burner. As a result, in particular, the carbon monoxide component is significantly reduced and there are the other advantages described above.

In 1B an alternative embodiment of the present invention is shown; for features that are in the 1A the same reference numerals are used.

In 1B is a shaft furnace 1' shown, which has a combination of upper and Untergichtabzug: Above the feed opening 12 is a Obergichtabzug 13 arranged, below said opening, the shaft furnace 1' an undergauge hood 19 on. The shaft 10 also has a top gas recirculation line 20 on.

Between the maximum fill level 11 and the loading opening 12 is the device 14 for the supply of oxygen and the ignition of blast furnace gas with the help of oxygen, as already related to 1A has been described.

LIST OF REFERENCE NUMBERS

1, 1 '

shaft furnace

10

shaft

11

maximum filling height

12

loading port

13

Upper gout deduction

14

Apparatus for supplying oxygen and for igniting

15

wind system

16

Propellant jet injection device

17

Supply to fan

18

Nozzle for introducing a partial flow of the combustion air

19

From gout deduction

20

Blast furnace gas recirculation line

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0762068 A1 [0002]
• DE 102008048779 A1 [0002, 0004]

Claims (10)

Shaft furnace ( 1 . 1' ), comprising: a shaft ( 10 ), in which metallic material can be melted; a loading opening ( 12 ), through which the material can be introduced into the shaft; and at least one deduction ( 13 ) for combustion gases; wherein, in a proper orientation of the shaft furnace, the material can be introduced through the feed opening from above into the shaft and the at least one trigger is arranged above the feed opening; characterized by a device ( 14 ) for the supply of oxygen and for ignition, which in the proper orientation of the shaft furnace below the feed opening ( 12 ) is arranged. Shaft furnace according to claim 1, wherein the device for supplying oxygen and for igniting comprises a burner, preferably an oxygen burner, wherein the burner is preferably arranged to ignite during a melting process at regular intervals or to burn continuously. Shaft furnace according to one of claims 1 or 2, wherein the device ( 14 ) for the oxygen supply and for ignition in the proper orientation of the shaft furnace in the upper half, in the upper third or in the upper quarter of the shaft ( 10 ) or above a maximum fill level intended for a melt operation ( 11 ) of the shaft is arranged. Shaft furnace according to one of claims 1 to 3, the nozzles ( 18 ) for supplying ambient air and is adapted to suck in air required for the combustion, preferably together with a conveying means, through the nozzles from the vicinity of the shaft furnace. Shaft furnace according to one of claims 1 to 4, further comprising a device ( 16 ) for recirculating blast furnace gas into the pit, wherein the blast furnace gas is preferably mixed with gas having an oxygen content of more than 80%, more preferably more than 90%. Method for operating a shaft furnace ( 1 ), which is a melting of feed in a shaft ( 10 ) of the shaft furnace, wherein the shaft furnace has a feed opening ( 12 ) and above the feed opening at least one trigger ( 13 ) for combustion gases, characterized in that the method comprises: enriching blast furnace gas in the shaft furnace by supplying oxygen below the charging port; and igniting the enriched blast furnace gas. A method according to claim 6, wherein the ignition is carried out with a burner, preferably an oxygen burner, wherein the burner is preferably adapted to ignite during a melting process at regular intervals or to burn continuously. A method according to claim 6 or 7, wherein the feeding of the oxygen and the igniting and above a level of the shaft takes place. A method according to any one of claims 6 to 8, further comprising sucking ambient air into the well, wherein the ambient air is preferably mixed with a conveyor. A method according to any one of claims 6 to 9, comprising recirculating top gas into the well, the blast gas preferably being mixed with gas having an oxygen content of greater than 80%, more preferably greater than 90%.

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