Rotary hearth furnace, and method for producing reduced iron using rotary hearth furnace

Patent metadata

Field	Value
Publication number	US-11428468-B2
Application number	US-201716315916-A
Country	US
Kind code	B2
Filing date	Jun 28, 2017
Priority date	Jul 15, 2016
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

A rotary hearth furnace includes: a furnace body which surrounds a ring-like space; a hearth portion which forms a bottom portion of the ring-like space and is rotatable in the rotational direction; a gas exhaust portion which discharges an exhaust gas generated in the ring-like space to the outside of the furnace body; an introducing portion; and a flow rate regulating portion. The introducing portion is disposed upstream of the gas exhaust portion in the rotational direction and introduces a pressure regulating gas into a non-heating section of the ring-like space. The flow rate regulating portion is disposed between the introducing portion and the gas exhaust portion and regulates a flow rate of a gas by adjusting an opening area of the non-heating section.

First claim

The invention claimed is:

1. A rotary hearth furnace suitable for producing reduced iron by reducing iron oxide by heating agglomerates comprising iron oxide, the rotary hearth furnace comprising:
a furnace body comprising a pair of peripheral walls and a ceiling plate that enclose a ring-like space having a continuous ring-like shape at lateral sides and an upper side of the ring-like space, respectively;
a ring-like hearth portion which forms a bottom portion of the ring-like space and which is rotatable in a predetermined rotational direction;
a gas exhaust portion for discharging an exhaust gas generated in the ring-like space an outside of the furnace body;
an introducing portion; and
a flow rate regulating portion,
wherein the ring-like space having a heating zone where the agglomerates placed on the hearth portion are heated and a non-heating zone where the agglomerates are not heated, the heating zone and the non-heating zone being joined with each other in a ring-like shape thereby forming the ring-like space,
wherein the gas exhaust portion is disposed in the non-heating zone,
wherein the introducing portion is disposed upstream of the gas exhaust portion in the rotational direction and is configured to introduce a pressure regulating gas for regulating a pressure in the ring-like space into the non-heating zone,
wherein the flow rate regulating portion is disposed between the introducing portion and the gas exhaust portion in the non-heating zone and is configured to regulate a flow rate of a gas which flows through the non-heating zone by adjusting an opening area of the non-heating zone, and
wherein the flow rate regulating portion is configured to regulate a flow rate of a gas which flows through the non-heating zone such that a pressure at a boundary between the heating zone and the non-heating zone, the boundary being a downstream end of the heating zone in the rotational direction, becomes the highest in the ring-like space.

2. The furnace of claim 1 , wherein the introducing portion includes an introducing amount regulating portion which regulates an introducing amount of the pressure regulating gas introduced into the non-heating zone.

3. The furnace of claim 1 , wherein the flow rate regulating portion includes a liftable partition wall disposed in the inside of the ring-like space,
wherein the partition wall has a lower end portion which faces the hearth portion and is capable of approaching to or being away from the hearth portion, and
wherein the partition wall is configured to be lifted or lowered so as to adjust the opening area formed by a gap between the lower end portion and the hearth portion.

4. The furnace of claim 1 , wherein the introducing portion includes a blower which supplies air outside the furnace body to the non-heating zone as the pressure regulating gas.

5. The furnace of claim 2 , wherein the non-heating zone includes a cooling section which is continuous with a downstream side end portion of the heating zone in the rotational direction and in which the agglomerates which pass through the heating zone is cooled, and
wherein the introducing portion is configured to introduce the air to a position downstream of the cooling section in the rotational direction in the non-heating zone.

6. The furnace of claim 1 , further comprising:
a hearth covering charcoal supply portion configure to supply hearth covering charcoal onto an upper surface of the hearth portion in the non-heating zone,
wherein the introducing portion is configured to introduce the pressure regulating gas to an upstream side of the hearth covering charcoal supply portion in the rotational direction.

7. The furnace of claim 6 , wherein the flow rate regulating portion is disposed upstream of the hearth covering charcoal supply portion in the rotational direction.

8. A method for producing reduced iron, the method comprising:
heating agglomerates that comprise iron oxide and are placed on a ring-like hearth portion in a heating zone which forms a section being a portion of a ring-like space in the rotary hearth furnace of claim 1 ;
discharging an exhaust gas generated in the ring-like space to the outside of the ring-like space in a non-heating zone connected to the heating zone in the ring-like space;
introducing a pressure regulating gas to a position upstream of a position where the exhaust gas is discharged in the non-heating zone in the rotational direction; and
regulating a flow rate of a gas which flows between a discharge position at which the exhaust gas is discharged in the non-heating zone and an introducing position at which the pressure regulating gas is introduced by adjusting an opening area of the non-heating zone.

9. The method of claim 8 , wherein in the regulating, a flow rate of a gas which flows through the non-heating zone is regulated such that a pressure at a boundary between the heating zone and the non-heating zone, the boundary being a downstream end of the heating zone in the rotational direction, becomes the highest in the ring-like space.

10. The method of claim 8 , wherein in the introducing, an introducing amount of the pressure regulating gas introduced into the non-heating zone is regulated corresponding to a change in an amount of the exhaust gas.

11. The furnace of claim 1 , further comprising:
a discharge portion in the non-heating zone configured to take out reduced iron and slag generated in the heating zone to the outside of the furnace body,
wherein the flow rate regulating portion is disposed downstream of the discharge portion in the rotational direction.

12. The furnace of claim 1 , further comprising:
a pressure detection portion which is disposed in the inside of the ring-like space and detects pressures at the boundary and positions in the vicinity of the boundary.

13. The furnace of claim 1 , wherein the flow rate regulating portion includes a liftable partition wall disposed in the inside of the ring-like space.

14. The furnace of claim 2 , wherein the flow rate regulating portion includes a liftable partition wall disposed in the inside of the ring-like space.

15. The furnace of claim 2 , wherein the introducing portion includes a blower which supplies air outside the furnace body to the non-heating zone as the pressure regulating gas.

16. The furnace of claim 3 , wherein the introducing portion includes a blower which supplies air outside the furnace body to the non-heating zone as the pressure regulating gas.

17. The furnace of claim 11 , wherein the introducing portion includes a blower which supplies air outside the furnace body to the non-heating zone as the pressure regulating gas.

18. The furnace of claim 12 , wherein the introducing portion includes a blower which supplies air outside the furnace body to the non-heating zone as the pressure regulating gas.

19. The furnace of claim 13 , wherein the introducing portion includes a blower which supplies air outside the furnace body to the non-heating zone as the pressure regulating gas.

Assignees

• Kobe Steel Ltd

Inventors

• Uemura Tomoki
• Hashimoto Sumito
• Tokuda Koji

Classifications

• C21B13/10

  in hearth-type furnaces · CPC title

• F27B9/34

  Arrangements of linings · CPC title

• C21B13/105

  Rotary hearth-type furnaces · CPC title

• C21B2100/66

  Heat exchange · CPC title

• F27B9/16 Primary

  the charge moving in a circular or arcuate path · CPC title