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

Patent metadata

Field	Value
Publication number	US-12509738-B2
Application number	US-202017776666-A
Country	US
Kind code	B2
Filing date	Nov 10, 2020
Priority date	Nov 14, 2019
Publication date	Dec 30, 2025
Grant date	Dec 30, 2025

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

The invention claimed is:

1 . A method for producing DRI in a direct reduction process using a reducing gas selected from a natural gas having more than 4% by volume of total hydrocarbons heavier than methane, coke oven gas (COG) having complex carbon compounds (BTX), or other synthetic gases coming from any source with a content of CH 4 and heavy hydrocarbons, wherein said method comprises circulating a first stream (F 1 ) of reducing gas exiting a reduction reactor ( 10 ) in a reducing gas circuit ( 20 ) through at least one carbon dioxide removal unit ( 38 ), a reducing gas heater ( 42 ) and said reduction 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, feeding at least one further stream (F 3 , F 4 ) of fresh reducing gas into said reducing gas circuit ( 20 ) wherein a flow rate of said stream (F 2 ) of fresh reducing gas is more than 20% by volume of a sum of the flow rate of said stream (F 2 ) plus a flow rate of said at least one further stream (F 3 , F 4 ) of fresh reducing gas,
wherein said method does not comprise any step of removal of hydrocarbons heavier than methane from the fresh reducing gas streams (F 3 , F 4 ) fed into the reducing gas circuit ( 20 ).

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 reducing gas circuit ( 20 ) without being pre-heated.

6 . The method as in claim 1 , wherein said further stream (F 3 ) of fresh reducing gas is injected at a point of the reducing gas circuit ( 20 ) located between said carbon dioxide removal unit ( 38 ) and said reducing gas heater ( 42 ).

7 . The method as in claim 1 , wherein said further stream (F 4 ) of fresh reducing gas is injected directly into the reactor ( 10 ).

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

9 . The method according to claim 8 , 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 ).

10 . The method as in claim 8 , 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 ).

11 . The method as in claim 8 , wherein said control unit ( 68 ) regulates at least the flow rate of the stream (F 3 ) so as to maintain the sum of heat provided by stream (F 2 ) plus heat provided by stream (F 3 ) at a temperature high enough to maintain a total amount of energy necessary to carry out a reduction reaction in a reduction zone ( 12 ) of the reactor ( 10 ) according to a programmed DRI production rate of the reactor.

12 . The method as in claim 8 , wherein said control unit ( 68 ) also regulates a flow rate of oxygen ( 52 ) to increase a temperature of a fresh reducing incoming gas stream (F 2 ) and maintain a temperature in reducing gas heater ( 42 ) to compensate for temperature loss upon mixing the fresh reducing incoming gas stream (F 2 ) with reducing gas coming from the reducing gas heater ( 42 ).

Assignees

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

Inventors

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

Classifications

• C21B13/02

  in shaft furnaces · CPC title

• C21B13/0073

  Selection or treatment of the reducing gases · CPC title

• C21B2100/64

  Controlling the physical properties of the gas, e.g. pressure or temperature · CPC title

• Y02P10/25

  Process efficiency · CPC title

• C21B2005/005

  Selection or treatment of the reducing gases · CPC title