Method and corresponding apparatus for producing iron from direct reduction of iron ore

Patent metadata

Field	Value
Publication number	US-2022396843-A1
Application number	US-202017776666-A
Country	US
Kind code	A1
Filing date	Nov 10, 2020
Priority date	Nov 14, 2019
Publication date	Dec 15, 2022
Grant date	—

Abstract

A method for producing direct reduced iron is provided. The method includes circulating a first stream of spent reducing gas exiting a reactor in a reducing gas circuit through at least one carbon dioxide removal unit and a reducing gas heater and the reactor. The method also includes mixing the first stream with reducing gas containing heavier hydrocarbons than methane.

First claim

1 . A method for producing DRI in a direct reduction process using a reducing gas chosen among a natural gas having a high content of total hydrocarbons heavier than methane, or coke oven gas (COG) having complex carbon compounds (BTX) or other synthetic gases coming from any source with high content of CH 4 and heavy hydrocarbons, said method comprising circulating a first stream (F 1 ) of reducing gas exiting a reactor ( 10 ) in a reducing gas circuit ( 20 ) through at least one carbon dioxide removal unit ( 38 ), a reducing gas heater ( 42 ) and said reactor ( 10 ); and feeding, into said reducing gas circuit ( 20 ), between said reducing gas heater ( 42 ) and said reduction reactor ( 10 ), a stream (F 2 ) of fresh reducing gas which amounts to more than 20% of the overall quantity of fresh reducing gas sent to the reduction reactor ( 10 ).

2 . The method as in claim 1 , wherein said gas stream (F 2 ) is pre-heated to a temperature lower than 650° C.

3 . The method as in claim 2 , wherein said stream (F 2 ) is pre-heated in a convective zone ( 43 ) of said reducing gas heater ( 42 ).

4 . The method as in claim 2 , wherein said stream (F 2 ) is pre-heated in a heat exchanger or fired heater separated from said reducing gas heater ( 42 ).

5 . The method as in claim 1 , wherein said stream (F 2 ) is injected into the circuit ( 20 ) without being pre-heated.

6 . The method as in claim 1 , the method further comprising feeding at least one further fresh stream (F 3 , F 4 ) of said fresh reducing gas which amounts to the portion of fresh reducing gas not injected into the reducing gas circuit ( 20 ) by the stream (F 2 ).

7 . The method as in claim 6 , wherein said stream (F 3 ) is injected in correspondence with any portion whatsoever of the reducing gas circuit ( 20 ) located between said carbon dioxide removal unit ( 38 ) and said reducing gas heater ( 42 ).

8 . The method as in claim 6 , wherein it feeds said stream (F 4 ) directly into the reactor ( 10 ).

9 . The method as in claim 6 , the method comprising feeding a combination of said fresh reducing gas which amounts to the portion of fresh reducing gas not injected by the stream (F 2 ), formed by the stream (F 3 ) injected in correspondence with any portion whatsoever of the circuit ( 20 ) located between said carbon dioxide removal unit ( 38 ) and said reducing gas heater ( 42 ), and by the stream (F 4 ) injected directly into the reactor ( 10 ).

10 . The method as in claim 1 , wherein at least the stream (F 2 ) is controlled by at least one control unit ( 68 ) configured to regulate flow rate and therefore the percentage of said fresh reducing gas injected into the circuit ( 20 ).

11 . The method according to claim 10 , wherein said control unit ( 68 ) regulates the flow rate of said gas stream (F 2 ) in response to a signal emitted by a flow rate sensor ( 69 , 70 ) measuring the flow rate of gas stream (F 3 ) and/or (F 4 ).

12 . The method as in claim 10 , wherein said control unit ( 68 ) additionally to regulating the flow rate of said gas stream (F 2 ) also regulates the flow rate of gas stream (F 3 ) and/or (F 4 ).

13 . The method as in claim 10 , wherein said control unit ( 68 ) regulates at least the flow rate of the stream (F 3 ) so as to maintain the sum of the heat provided by stream (F 2 ) plus the heat provided by stream (F 3 ) within a predetermined range of values so as to maintain the operating conditions of the reduction zone ( 12 ) of the reactor ( 10 ) to produce DRI at a predetermined production rate.

14 . The method as in claim 10 , wherein said control unit ( 68 ) also regulates a flow rate of oxygen ( 52 ) with the aim of compensating the loss of energy caused by the fact that gas stream (F 2 ) bypassing the fired heater ( 42 ) will not have in any case the same temperature of the pipe ( 28 ) after heating in same fired heater ( 42 ).

15 . The method as in claim 1 , wherein said method does not comprise any step of removal of the fraction of heavier hydrocarbons from the reducing gas, in particular it does not comprise any reforming step.

16 . An apparatus for producing DRI from direct reduction of iron ore using a reducing gas having a high content of hydrocarbons heavier than methane, chosen among a natural gas having a high content of hydrocarbons heavier than methane, or coke oven gas (COG) having complex carbon compounds (BTX) or other synthetic gases coming from any source with high content of CH 4 and heavy hydrocarbons, said apparatus comprising a reduction reactor ( 10 ), a carbon dioxide removal unit ( 38 ) and a heater ( 42 ), a reducing gas circuit ( 20 ) being provided which passes through said carbon dioxide removal unit ( 38 ) and said heater ( 42 ) and said reactor ( 10 ), said apparatus comprising a first injection means ( 49 a ) configured to feed, into said reducing gas circuit ( 20 ) between said reducing gas heater ( 42 ) and said reduction reactor ( 10 ), a stream (F 2 ) of fresh reducing gas which amounts to more than 20% of the quantity of reducing sent to the reduction reactor ( 10 ).

17 . The apparatus as in claim 16 , wherein the apparatus comprises further injection means ( 49 b , 49 c ) configured to inject into the reducing gas circuit ( 20 ) at least one fresh stream (F 3 , F 4 ) of said reducing gas which amounts to the portion of reducing gas not injected into the reducing gas circuit ( 20 ) by the stream (F 2 ).

18 . The apparatus as in claim 17 , wherein said injection means ( 49 b ) are configured to inject said stream (F 3 ) in correspondence with any portion whatsoever of the reducing gas circuit ( 20 ) located between said carbon dioxide removal unit ( 38 ) and said reducing gas heater ( 42 ).

19 . The apparatus as in claim 17 , wherein said injection means ( 49 c ) are configured to feed said stream (F 4 ) directly into the reactor ( 10 ).

20 . The apparatus as in claim 16 , wherein the apparatus comprises at least one control unit ( 68 ) connected to at least one of valves ( 56 , 58 , 60 , 62 ) and configured to regulate the respective streams (F 2 , F 3 , F 4 ).

21 . The apparatus as in claim 20 , wherein the at least one control unit ( 68 ) is connected to the source ( 52 ) of oxygen and configured to regulate its flowrate.

22 . The apparatus as in claim 16 , wherein said apparatus does not comprise any means or device for removal of the fraction of heavier hydrocarbons from the reducing gas, in particular it does not include any reformer.

Assignees

• Danieli Off Mecc
• Hyl Tech S A De C V

Inventors

• Franco Barbara
• Roman Di Catterina Paolo
• Martinez Miramontes Jorge Eugenio

Classifications

• C21B2100/26

  by adding additional fuel in recirculation pipes · CPC title

• Y02P10/25

  Process efficiency · CPC title

• C21B13/0073

  Selection or treatment of the reducing gases · CPC title

• C21B2100/282

  of carbon dioxide · CPC title

• C21B13/004 Primary

  in a continuous way by reduction from ores · CPC title