DIRECT REDUCTION PROCESS FOR THE PRODUCTION OF DIRECT-REDUCED IRON WITH HIGH PURITY METHANE

• US 20190323098A1
• Filed: 12/14/2017
• Published: 10/24/2019
• Est. Priority Date: 12/22/2016
• Status: Active Application

• Current Assignee: SABIC Global Technologies BV (Government of Saudi Arabia)
• Original Assignee: SABIC Global Technologies BV (Government of Saudi Arabia)
• Inventors: HANDAGAMA, Nareshkumar Bernard, LIU, Zheng
• Application Number:
  US16/471,115
• Publication Number:
  US 20190323098A1
• Time in Patent Office: Days
• CPC Class Codes: B01D 2256/245 Methane
• CPC Class Codes: B01D 2257/102 Nitrogen
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: B01D 53/22 by diffusion manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00
• CPC Class Codes: C21B 13/0073 Selection or treatment of the reducing gases
• CPC Class Codes: C21B 2100/284 of nitrogen
• CPC Class Codes: F27B 1/08 heated otherwise than by solid fuel mixed with charge
• CPC Class Codes: F27D 7/06 Forming or maintaining special atmospheres or vacuum within heating chambers F27D7/02 takes precedence
• CPC Class Codes: Y02P 10/134 by avoiding CO2, e.g. using hydrogen
• CPC Class Codes: Y02P 10/143 of methane [CH4]

Abstract

Systems and processes to produce direct reduced iron with a gaseous reducing stream having less than 10 mol. % nitrogen (N₂) and greater than 80 mol. % methane (CH₄) are described. A process includes separating N₂ from a gaseous stream to produce the reducing stream and contacting the reducing stream with iron ore under conditions sufficient to form direct-reduced iron. The reduction in the N₂ content of the reducing stream improves the overall steel producing capacity by at least 2%.

Claims

1. A direct reduction process for producing direct-reduced iron, the process comprising:

(a) subjecting a gaseous stream comprising methane (CH₄) and nitrogen (N₂) to conditions sufficient to separate N₂ from the gaseous stream and form a gaseous reducing stream comprising less than 10 mol. % N₂ and greater than 80 mol. % CH₄; and

(b) contacting the gaseous reducing stream with iron ore under conditions sufficient to form direct-reduced iron.

2. The direct reduction process of claim 1, further comprising capturing energy from step (b) and using the energy in step (a).

3. The direct reduction process of claim 1, wherein conditions sufficient to form direct-reduced iron comprise:

(i) heating the gaseous reducing stream;

(ii) contacting the heated gaseous reducing stream with iron ore to form direct-reduced iron; and

(iii) capturing energy from step (i) and/or step (ii) and providing the captured energy to step (a).

4. The direct reduction process of claim 3, wherein substantially all of the energy required for the separation conditions of step (a) is obtained from the captured energy.

5. The direct reduction process of claim 1, wherein the gaseous reducing stream comprises 0 to 10 mol. % N₂, 2 to 6 mol. % N₂, or 4 to 6 mol. % Na.

6. The direct reduction process of claim 1, wherein the gaseous reducing stream comprises 85 to 99 mol. % CH4, 87 to 98 mol. % CH₄, or 90 to 95 mol. % CH₄.

7. The direct reduction process of claim 1, further comprising producing iron steel from the direct-reduced iron.

8. The direct reduction process of claim 7, wherein separation of N₂ in step (a) increases iron steel production capacity by at least 2%, at least 5%, at least 9%, or at least 15%.

9. The direct reduction process of claim 1, wherein the separation conditions comprise flowing the gaseous stream through a membrane system to produce the gaseous reducing stream and a N₂-containing stream.

10. The direct reduction process of any claim 1, wherein the separation conditions comprise cryogenically distilling the gaseous stream comprising CH₄ and N₂ to produce the gaseous reducing stream and a N₂-containing stream.

11. The direct reduction process of claim 9, wherein the N₂-containing stream comprises N₂ and CH₄.

12. The direct reduction process of claim 11, further comprising generating heat from the N₂-containing stream by combusting the N₂-containing stream, and providing the heat to one or more steel production processes.

13. The direct reduction process of claim 1, wherein the gaseous reducing stream of step (a) is heated in the presence of an oxidant and then contacted with the iron ore in step (b).

14. The direct reduction process of claim 1, wherein the gaseous stream is natural gas.

15. The direct reduction process of claim 1, wherein the gaseous stream comprises 70 to 88 mol. % CH₄, 1 to 5 mol. % ethane, 1 to 5 mol. % propane, 15 to 20 mol % nitrogen, 0.1 to 1 mol. % with the balance being carbon monoxide and oxygen.

16. The direct reduction process of claim 10, wherein the N₂-containing stream comprises N₂ and CH₄.

17. The direct reduction process of claim 3, further comprising producing iron steel from the direct-reduced iron.

18. The direct reduction process of claim 4, further comprising producing iron steel from the direct-reduced iron.

19. The direct reduction process of claim 5, further comprising producing iron steel from the direct-reduced iron.

20. The direct reduction process of claim 6, further comprising producing iron steel from the direct-reduced iron.