METHOD AND DEVICE FOR DIRECT REDUCTION WITH DRY VENT GAS DE-DUSTING

Abstract

A method for direct reduction of metal oxide-containing starting materials to produce metallized material by contact with hot reduction gas in a reduction unit (1), wherein the product of the direct reduction is discharged from the reduction unit (1) by means of a product discharge device (3) which is flushed with seal gas and from which vent gas is drawn and subsequently de-dusted. The vent gas is de-dusted dry and the content of at least one gaseous constituent is reduced by catalytic conversion or combustion. Also, a device for carrying out the method is disclosed.

Claims

1. A method for direct reduction of metal oxide-containing, to iron oxide-containing, starting materials to produce metallized material comprising: contacting the starting materials with hot reduction gas in a reduction unit; discharging the product of the direct reduction from the reduction unit by means of a product discharge device, by flushing the product discharge device with seal gas and drawing vent gas from the discharge device and subsequently, de-dusting the vent gas; wherein the vent gas is de-dusted dry, the content of at least one gaseous constituent of the de-dusted vent gas is reduced, wherein the content of the at least one gaseous constituent is reduced by conversion into CO.sub.2 and/or into H.sub.2O by at least one of catalytic conversion using at least one of oxygen O.sub.2 and/or H.sub.2O in the form of steam, and/or by combustion.

2. The method as claimed in claim 1, wherein the gaseous constituent is carbon monoxide CO, and the content the CO.sub.2 is reduced by conversion into CO.sub.2 by at least one of catalytic conversion using oxygen O.sub.2 and/or H.sub.2O in the form of steam, and/or by combustion.

3. The method as claimed in claim 1 claim 1, wherein the at least one of oxygen-containing and/or steam-containing gases are supplied for the conversion into CO.sub.2 and/or H.sub.2O.

4. A device for carrying out a method as claimed in claim 1 comprising: a reduction unit with a reduction gas supply; a product discharge device, from the reduction unit; a seal gas supply line opening into the product discharge device; a vent gas removal line exiting from the product discharge device; a dry de-dusting device, the vent gas removal line opening into the dry de-dusting device a diverting device exiting from the dry de-dusting device for diverting dry de-dusted vent gas into the atmosphere; the diverting device comprising a reducing device for reducing the content of at least one gaseous constituent of the de-dusted vent gas, the reducing device reducing the content by catalytic conversion to at least one of CO.sub.2 and/or H.sub.2O using at least one of oxygen O.sub.2 and/or H.sub.2O in the form of steam, and/or by combustion to at least one of CO.sub.2 and/or H.sub.2O.

5. The device as claimed in claim 4, further comprising: the device for reducing the content of at least one gaseous constituent of the de-dusted vent gas is a device for reducing the CO content by catalytic conversion to CO.sub.2 using oxygen O.sub.2 and/or H.sub.2O in the form of steam, and/or by combustion to CO.sub.2.

6. The device as claimed in claim 5, the device for reducing the content of at least one gaseous constituent of the de-dusted vent gas, preferably the CO content, has at least one supply line for supplying oxygen-containing and/or steam-containing gases.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] FIG. 1 schematically shows an embodiment of a device according to the invention.

[0066] FIG. 2 schematically shows another embodiment of a device according to the invention, in which a MIDREX method is carried out.

DESCRIPTION OF THE EMBODIMENTS

[0067] FIG. 1 shows a device for carrying out a method according to the invention. It comprises a reduction unit 1 with a reduction gas supply 2 through which hot reduction gas is guided into the reduction unit. For a better overview, illustration of the introduction of metal oxide-containing starting materials, as raw material, into the reduction unit has been omitted. Exiting from the reduction unit 1 is a product discharge device 3 which discharges the product of the direct reduction from the reduction unit 1. Opening into the product discharge device 3 is a seal gas supply line 4 through which seal gas is introduced into the product discharge device in order to flush the latter with seal gas which exits from the product discharge device 3. Vent gas from the product discharge device 3 is guided out through the vent gas removal line 5. If the product discharge device comprises, for example, a discharge member and a material-conveying device (these not being additionally illustrated here), it is possible for seal gas to be introduced into the discharge member, which seal gas, in part, flows into the material-conveying device and is guided out of the latter as vent gas. The material-conveying device could be, for example, a cellular wheel conveyor or a wiper bar. Discharged product is indicated by an undulating arrow. The vent gas removal line 5 opens into a dry de-dusting device 6 in which the vent gas is de-dusted dry. Discharge of dry dust, for example to consumers mentioned above in the description, is illustrated by an undulating arrow. A diverting device 7 for diverting dry de-dusted vent gas into the atmosphere (schematically illustrated by a line leading to a chimney 8) exits from the dry de-dusting device 6. The diverting device 7 comprises a device 9 for reducing the content of at least one gaseous constituent of the de-dusted vent gas. In the illustrated case, the device 9 is a device for reducing the CO content by oxidation via catalytic conversion using oxygen O.sub.2 or H.sub.2O in the form of steam. It could also be a device for reducing the CO content by combustion, that is by a burner system.

[0068] FIG. 2 shows an embodiment in which a MIDREX method is carried out. Natural gas 10, or if appropriate a mixture of natural gas 10 with a process gas, is guided into a reformer 11 and there is converted into reduction gas. Hot reduction gas is introduced into the reduction shaft 13 by means of the reduction gas supply 12. For a better overview, the illustration of recycling of top gas of the reduction shaft has been omitted. The product discharge device for discharging HDRI from the reduction shaft 13 comprises a dynamic seal leg 14 as a discharge member, into which a seal gas supply line 15 opens, and a PDC 16. The seal gas supplied via the seal gas supply line seals off the reduction shaft 13 with respect to breakthrough of reduction gas and flushes the dynamic seal leg 14 and the PDC 16. HDRI is supplied to a briquetting plant 17 from the product discharge device (in the illustrated example, from the PDC 16 thereof). A vent gas removal line 18 which opens into a dry de-dusting device 19 departs from the product discharge device (in the illustrated example, from the PDC 16 thereof). De-dusted vent gas is released from the dry de-dusting device 19, which can be equipped with ceramic filter candles, and into the environment via the diverting device 20. The dry de-dusting device may optionally also comprise a cyclone upstream of the ceramic filter candles, which, for a better overview, is not additionally illustrated. A device for reducing the CO content in the de-dusted vent gas by catalytic conversion using oxygen 21a, and/or a burner system 21b, indicated by dashed lines, are/is present in the diverting device 20. Dry dust from the dry de-dusting device 19 can be supplied to different destinations via a dust discharge line 22.

[0069] In FIG. 1 and FIG. 2, the device for reducing the CO content may also have a supply line for supplying oxygen-containing and/or steam-containing gases. This is not additionally illustrated, however, for the purpose of a better overview.

[0070] Even though the invention has been illustrated and described in more detail by way of the preferred exemplary embodiments, the invention is not restricted by the examples disclosed, and other variations may be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.

[0071] The disclosure of the present application also encompasses the entire disclosure of WO08123962, U.S. Pat. No. 4,188,022, WO2011012448 and WO2011012452 incorporated herein by reference.

LIST OF CITATIONS

Patent Literature

WO2011012452

WO2008123962

[0072] U.S. Pat. No. 4,188,022

WO2011012448

LIST OF REFERENCE SIGNS

[0073] 1 Reduction unit [0074] 2 Reduction gas supply [0075] 3 Product discharge device [0076] 4 Seal gas supply line [0077] Vent gas removal line [0078] 6 Dry de-dusting device [0079] 7 Diverting device [0080] 8 Chimney [0081] 9 Device for reducing the content of at least one gaseous constituent of the de-dusted vent gas [0082] 10 Natural gas [0083] 11 Reformer [0084] 12 Reduction gas supply [0085] 13 Reduction shaft [0086] 14 Dynamic seal leg [0087] Seal gas supply line [0088] 16 Product discharge chamber (PDC) [0089] 17 Briquetting plant [0090] 18 Vent gas line [0091] 19 Dry de-dusting device [0092] 20 Diverting device [0093] 21a Device for reducing the CO content in the de-dusted vent gas by catalytic conversion using oxygen [0094] 21b Burner system [0095] 22 Dust discharge line