Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B13/00—Making spongy iron or liquid steel, by direct processes
  • C21B13/0073—Selection or treatment of the reducing gases
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
  • C21B2100/20—Increasing the gas reduction potential of recycled exhaust gases
  • C21B2100/22—Increasing the gas reduction potential of recycled exhaust gases by reforming
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
  • C21B2100/20—Increasing the gas reduction potential of recycled exhaust gases
  • C21B2100/28—Increasing the gas reduction potential of recycled exhaust gases by separation
  • C21B2100/282—Increasing the gas reduction potential of recycled exhaust gases by separation of carbon dioxide
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
  • C21B2100/60—Process control or energy utilisation in the manufacture of iron or steel
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
  • Y02P10/122—Reduction of greenhouse gas [GHG] emissions by capturing or storing CO2
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
  • Y02P10/134—Reduction of greenhouse gas [GHG] emissions by avoiding CO2, e.g. using hydrogen
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
  • Y02P10/143—Reduction of greenhouse gas [GHG] emissions of methane [CH4]

Definitions

• the invention relates to a process for the direct reduction of iron oxide-containing material, synthesis gas, preferably reformed natural gas, being mixed with top gas formed in the direct reduction of the iron oxide-containing material and used as a reducing gas for direct reduction and for heating the iron oxide-containing material to the reduction temperature, and a system for carrying out the Procedure.
• Metal dusting occurs increasingly at higher temperatures, which means in particular Parts of the system that come into contact with hot reducing gas are at risk.
• these are, in particular, the reactors used for direct reduction and the gas heater which heats the reducing gas to the reduction temperature.
• the invention aims to avoid these disadvantages and difficulties and has as its object to provide a method of the type described above and a system for carrying out the method, which an adjustment of an H2S content to a predetermined value with sufficient accuracy and avoiding a large enable procedural or constructive and costly effort.
• This object is achieved in that at least part of a sulfur contained in the iron oxide-containing material in the form of H2S obtained during the heating or the direct reduction is fed to the reducing gas with the top gas.
• the invention is based on the idea of utilizing the sulfur usually contained in the ore, which has hitherto not been used in further processing, and makes the fact take advantage of the fact that when sulfur-containing ore is heated, H2S is formed.
• this PbS is derived as the top gas with the reducing gas which brings about the heating and from which it is absorbed, and is fed to the reducing gas.
• a __2S content in the reducing gas is expediently set in the size of 20 to 40 ppmV, preferably in the size of approximately 25 ppmV, with the top gas.
• the top gas is subjected to a CO 2 scrubbing before use as a reducing gas, and the __2S content in the reducing gas is adjusted by admixing at least a partial volume of the top gas to the reducing gas bypassing the CO 2 scrubbing.
• This variant is particularly easy to implement, since only a bypass line which bridges the CO 2 washer is to be arranged. This prevents the FbS present in this part of the top gas from being washed out, whereas the remaining part of the top gas is subjected to an Olb wash, in which H2S is also washed out.
• the desired H2S content of the reducing gas can be set in a simple manner by varying the amount of top gas passed through the bypass line.
• a further preferred embodiment is characterized in that reformed natural gas is used as synthesis gas and that both the reformed natural gas and the top gas are subjected to a CO 2 scrubbing before use as a reducing gas, a partial volume of the reformed natural gas being bypassed by the CO 2 scrubbing Reducing gas is added directly.
• a desired CO content can be set in a simple manner or changes in the CO 2 content and the CO / CO2 ratio of the reducing gas caused by the direct admixing of a part of a CO2-unwashed top gas can be compensated for, taking into account the desired H2S content.
• Another preferred possibility for setting the desired H2S content in the reducing gas is characterized in that the setting of the H2S content in the reducing gas is carried out by varying the degree of washing out of the CO 2 wash, etc. in that part of the CO2 and thus part of the H2S remain in the scrubbed gas.
• This embodiment requires the least possible design effort, that is, not even the arrangement of a bypass line, but it must be taken into account that the entire gas must be passed through the CO2 scrubber, which must be dimensioned accordingly
• the particulate iron oxide-containing material is preferred in the event that it is not sulfur-containing. a sulfur-containing material such as Fe pyrite is added, thereby causing the formation of H2S and its inclusion in the reducing gas which brings about the heating of the iron oxide-containing material to the reduction temperature.
• a reformer for reforming natural gas and a reforming gas line starting from the reformer, which opens together with the top gas discharge line, are provided for producing the synthesis gas, both the reformed gas line and the top gas discharge line opening into the b scrubber.
• the bypass line of the reformed gas line is preferably connected to the reducing gas supply line bypassing the CO 2 scrubber by means of a bypass line.
• the bypass line (s) is (are) suitably equipped with a control valve, preferably a control valve, which can be activated via an H2S measuring device.
• the plant according to the invention has four fluidized bed reactors 1 to 4 connected in series, with iron oxide-containing material, such as fine ore, being fed via an ore feed line 5 to the first fluidized bed reactor 1, in which the heating to the reduction temperature (or a pre-reduction) takes place, and then from Fluidized bed reactor to fluidized bed reactor via feed lines 6 is passed.
• the finished reduced material (sponge iron) is hot briquetted in a briquetting system 7 If necessary, the reduced iron is protected from reoxidation by an inert gas system (not shown) during the briquetting.
• the fine ore Before the fine ore is introduced into the first fluidized bed reactor 1, it is subjected to an ore preparation, such as drying and sieving, which is not shown in detail.
• Reducing gas is conducted in countercurrent to the ore flow from the fluidized bed reactor 4 to the fluidized bed reactor 3 to 1 and is discharged as top gas via a top gas discharge line 8 from the last fluidized bed reactor 1 in the gas flow direction and cooled and washed in a wet scrubber 9.
• the reduction gas is produced by reforming natural gas supplied via line 11 and desulfurized in a desulfurization system 12 in a reformer 10.
• the gas formed from natural gas and steam and leaving reformer 10 essentially consists of H2, CO, CH4, H2O and CO2 .
• This reformed natural gas is fed via the reformed gas line 13 to a plurality of heat exchangers 14, in which it is cooled, as a result of which water is condensed out of the gas.
• the reformed gas line 13 opens into the top gas discharge line 8 after the top gas has been compressed by means of a compressor 15.
• the mixed gas thus formed is sent through a CO2 scrubber 16 and freed of CO2 and thereby also of H2S. It is now available as a reducing gas.
• This reducing gas is heated via a reducing gas feed line in a gas heater 18 arranged downstream of the CO 2 scrubber 16 to a reducing gas temperature of approximately 800 ° C. and fed to the first fluidized bed reactor 4 in the gas flow direction, where it reacts with the fine ores to produce direct-reduced iron.
• the fluidized bed reactors 4 to 1 are connected in series; the reducing gas passes through the connecting lines 19 from the fluidized bed reactor to the fluidized bed reactor.
• Part of the top gas is removed from the gas circuit 8, 17, 19 in order to avoid an enrichment of inert gases, such as N2.
• the discharged top gas is fed via a branch line 20 to the gas heater 18 for heating the reducing gas and burned there. Any missing energy is supplemented by natural gas which is fed in via the feed line 21
• the sensible heat of the reformed natural gas emerging from the reformer 10 and of the reformer fumes is used in a recuperator 22 to preheat the natural gas after passing through the desulfurization system 12, to generate the steam required for the reforming and to supply the gas heater 18 via line 23 Preheat the combustion air and possibly also the reducing gas.
• the combustion air supplied to the reformer via line 24 is also preheated.
• the top gas leaving the fluidized bed reactor 1 has - depending on the sulfur content of the ore - an H2S content of 40 to 140 ppmV.
• the H2S gas forms during the heating of the fine ore to the reduction temperature or during the pre-reduction of the fine ore.
• the H2S is no longer completely washed out of the top gas by means of the CO 2 scrubber, but care is taken to ensure that the percentage of H2S of the top gas desired for the reducing gas is fed to the reducing gas.
• this can be achieved by means of a bypass line 25 which bypasses the CO 2 scrubber 16, which starts from the top gas discharge line 8 via a control or regulating valve 26 and opens into the reducing gas supply line 17.
• the control or regulating valve 26 can be set such that an H2S content in the reducing gas in the size of 20 to 40 ppmV, preferably in the size of about 25 ppmV. is available.
• the control valve 26 is preferably activated via an H2S measuring device 27, not shown.
• the desired H2S content in the reducing gas can also be set by passing all of the top gas through the C02 scrubber 16, but this is set to a degree of leaching at which part of the CO2 and thus part of the H2S is removed the gas emerging from the CO 2 scrubber 16 remain.
• This has the advantage that no auxiliary devices, such as a bypass line 25 with control valve 26, have to be provided, but requires that the entire gas quantity, that is to say the entire top gas and the entire reformed natural gas, must be passed through the CO 2 scrubber 16 , so that this must be measured for this amount.
• a part can be used to set a desired CO 2 content or a desired CO / CO2 ratio, which is influenced by a change in the degree of scrubbing of the CO 2 scrubber 16 or by a direct supply of part of the top gas via the bypass line 25 of the reformed natural gas are fed to the reducing gas supply line 17 via a bypass line 29 bridging the CO2 scrubber 16 and also equipped with an adjustable valve 28; this bypass line 29 then goes from the Reform gas line 13 out.
• the measures described above for setting a desired H2S content in the reducing gas can be implemented individually or together.
• the reformed natural gas and the top gas have the chemical composition given in the table below:
• the gas mixture emerging from the CO 2 scrubber 16 and formed from the scrubbed reformed natural gas and the scrubbed top gas is composed as follows:
• This gas mixture is mixed with 78,000 N ⁇ vVh of the top gas which was not passed through the CO 2 scrubber 16.
• This gas mixture forms the reducing gas which is fed to the gas heater 18 and subsequently to the fluidized bed reactors 1 to 4 and has the following chemical composition:
• the degree of metallization of the sponge iron is 92 9c.
• the reformed natural gas and the top gas have the chemical composition given in the table below:
• the gas mixture emerging from the CO 2 scrubber 16 and formed from the washed reformed natural gas and the top gas is composed as follows:
• This gas mixture is mixed with 94,000 Nm 3 / h of the top gas which was not passed through the CO 2 scrubber 16.
• This gas mixture forms the reducing gas fed to the gas heater 18 and subsequently to the fluidized bed reactors 1 to 4 and has the following chemical composition:
• the degree of metallization of the sponge iron is 92 9c.
• the invention is not limited to the examples described above, but is also used for other direct reduction processes, e.g. those in which 1 to 4 shaft furnaces for lump ore are used instead of the fluidized bed reactors can be used.
• other reducing gases containing mainly CO and H2 such as

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture Of Iron (AREA)
• Catalysts (AREA)
• Manufacture And Refinement Of Metals (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

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• 1994
  • 1994-06-23 AT AT0124894A patent/AT402825B/de not_active IP Right Cessation
• 1995
  • 1995-06-15 PE PE1995271376A patent/PE49695A1/es not_active Application Discontinuation
  • 1995-06-20 MX MX9606728A patent/MX9606728A/es unknown
  • 1995-06-20 AU AU25568/95A patent/AU691293B2/en not_active Ceased
  • 1995-06-20 WO PCT/AT1995/000121 patent/WO1996000302A1/de not_active Application Discontinuation
  • 1995-06-20 JP JP50263096A patent/JP3248915B2/ja not_active Expired - Fee Related
  • 1995-06-20 RU RU97101124A patent/RU2125098C1/ru active
  • 1995-06-20 BR BR9508108A patent/BR9508108A/pt not_active Application Discontinuation
  • 1995-06-20 US US08/765,342 patent/US5871560A/en not_active Expired - Fee Related
  • 1995-06-20 UA UA96124793A patent/UA27080C2/uk unknown
  • 1995-06-20 CA CA002193855A patent/CA2193855C/en not_active Expired - Fee Related
  • 1995-06-20 KR KR1019960707371A patent/KR100240811B1/ko not_active IP Right Cessation
  • 1995-06-20 EP EP95919926A patent/EP0766747A1/de not_active Ceased
  • 1995-06-22 ZA ZA955177A patent/ZA955177B/xx unknown

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