EP2586877A1

EP2586877A1 - Furnace having even distribution of gas

Info

Publication number: EP2586877A1
Application number: EP10853710.1A
Authority: EP
Inventors: Sin-Myoung Kang; Sang-Ho Lee
Original assignee: Posco Co Ltd; Posco Engineering and Construction Co Ltd
Current assignee: Posco Engineering and Construction Co Ltd; Posco Holdings Inc
Priority date: 2010-06-23
Filing date: 2010-06-23
Publication date: 2013-05-01
Anticipated expiration: 2030-06-23
Also published as: EP2586877B1; CN102947470A; WO2011162427A1; ZA201300525B; EP2586877A4

Abstract

Provided is a reduction furnace reducing ore containing an iron oxide component, and including a charge feeding port 110 having a charge material introduced therethrough and a reducing gas intake port 170 having reducing gas injected therethrough, wherein the charge feeding port 110 is formed in an upper portion thereof and the reducing gas intake port 170 is installed in a bottom portion thereof.

According to the present invention, since the reducing gas may be injected into the center of a lower portion of the reduction furnace, the reducing gas may be allowed to be uniformly distributed in the reduction furnace, and thus, a reduction rate of the charge material may be increased and reduction rates between particles of the charge material may be uniformized.

Description

[Technical Field]

The present invention relates to a reduction furnace reducing ore containing an iron oxide component and an apparatus for manufacturing molten iron by melting reduced ore.

[Background Art]

FIG. 1 illustrates a typical reduction furnace reducing ore containing an iron oxide component and an apparatus 1 for manufacturing molten iron by melting reduced ore. As illustrated in FIG. 1, the apparatus 1 includes a reduction furnace 10 for reducing or preheating agglomerated ores, such as pellets or lump ore, by injecting a reducing gas. A charge material is introduced into the reduction furnace 10 through a charge feeding port 11. The charge material reduced in the reduction furnace 10 is discharged in a fixed amount by a discharge screw 13 and the discharged charge material is supplied to a melting furnace 20 through a vertical down pipe 14 and a tilt down pipe 16. A drop box 15 is included in the vertical down pipe 14 and a nitrogen supply pipe (not shown) is connected to the drop box 15 to inject nitrogen for cooling into the vertical down pipe 14. The nitrogen for cooling may decrease thermal shock applied to the discharge screw 13 by gas flowing backwards to the reduction furnace 10 from the melting furnace 20.
In the melting furnace 20, reducing gas required for the reduction of the charge material is prepared by the gasification of coal and heat generated at this time is also used to melt the charge material reduced and supplied from the reduction furnace 10.
The reducing gas generated in the melting furnace 20 is dust collected in a cyclone 22 and is then injected into the reduction furnace 10 through a reducing gas intake port 17. The injected reducing gas reduces the charge material while passing through a packed bed 30 of the charge material in an oxide form. The injected reducing gas may not be provided to the center of the reduction furnace 10 due to the resistance caused by the packed charge material and may mainly flow along a wall portion thereof. The non-uniform distribution of the reducing gas may cause severe unbalance of a reduction rate for each position of the charge material and the unreduced charge material at the center of the reduction furnace 10 may be provided to the melting furnace 20 to break thermal balance of the melting furnace 20, and thus, limitations, such as a decrease in production, an increase in fuel cost, and a decrease in an operating ratio, may occur. In particular, in the case that a size of the typical reduction furnace 10 is increased for the purpose of increasing the capacity thereof, the non-uniform distribution of the reducing gas may be more severe and it may be more difficult for the reducing gas to reach the center thereof when the size of the reduction furnace 10 radial direction is increased in a radial direction.
Also, since pressure drop in the cyclone 22 may occur in the case that the reducing gas generated in the melting furnace 20 is injected into the reduction furnace 10 through the cyclone 22, the reducing gas may flow backwards into the reduction furnace 10 through the vertical down pipe 14 and the discharge screw 13 having a relatively small pressure loss. Therefore, in order to prevent this, installation of an unreduced height h of the charge material is essentially required for the purpose of generating a reduction in pressure in the reducing gas flowing backwards into the reduction furnace 10 through the discharge screw 13 and, as a result, the height of a facility must be unnecessarily increased.

[Disclosure]

[Technical Problem]

An aspect of the present invention provides improvements, such as an increase in production, a decrease in fuel costs, an increase in an operating ratio, and operational stability, by decreasing a thermal load of a melting furnace when a charge material is supplied thereto by removing a non-uniform distribution phenomenon of reducing gas, in which the reducing gas supplied to the inside of a reduction furnace in a reduction process is mainly flowing along a wall portion but not introducing to the center of the reduction furnace thereof, to increase a reduction rate of the charge material and uniformize reduction rates between particles of the charge material.
Another aspect of the present invention provides an increase in the capacity of a facility, able to be achieved by simply increasing the size of a reduction furnace and a deadman in a radial direction during the increase in the capacity of the reduction furnace by allowing the reducing gas to be uniformly distributed in the radial direction of the reduction furnace.

[Technical Solution]

According to an aspect of the present invention, there is provided a reduction furnace including: a charge feeding port having a charge material introduced therethrough; and a reducing gas intake port having reducing gas injected therethrough, wherein the charge feeding port is formed in an upper portion thereof and the reducing gas intake port is installed in a bottom portion thereof.
The reducing gas intake port may be installed in a bottom portion of a deadman disposed in a lower portion of the reduction furnace.
A path connected to the reducing gas intake port may be formed inside the deadman.
The path may be formed in plural to be symmetrical in a radial direction.
A vertical down pipe having the charge material reduced by the reducing gas discharged therethrough may be filled with the charge material in normal operating conditions.
A drop box may be installed in an end portion of the vertical down pipe and a discharge screw discharging a fixed amount of the charge material may be installed in the drop box.
The vertical down pipe has a predetermined vertical length to generate a reduction in pressure in gas flowing backwards into the reduction furnace through the vertical down pipe.

[Advantageous Effects]

According to the present invention, since reducing gas may be injected through a deadman disposed at the center of a bottom portion of a reduction furnace, a reduction rate of a charge material in the reduction furnace may increase, reduction rates between particles of the charge material may be uniformized, and a thermal load of a melting furnace may be decreased during the charge material is supplied to the melting furnace, and thus, an increase in production, a decrease in fuel costs, an increase in an operating ratio, and operational stability may be achieved.
Also, in the present invention, the reducing gas may be allowed to be uniformly distributed in a radial direction of the reduction furnace, and thus, an increase in the capacity of a facility may be achieved by simply increasing the size of the reduction furnace and the deadman in the radial direction thereof during the increase in the capacity of the reduction furnace.
Also, since the position of a discharge screw, a charge material supply device, may be changed from a lower end of the reduction furnace to a portion of a drop box, differential pressure in a vertical down pipe may be generated, and thus, a back flow of high-pressure gas from the melting furnace into the reduction furnace may be prevented.

[Description of Drawings]

The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a longitudinal sectional view illustrating a typical reduction furnace reducing ore containing an iron oxide component and an apparatus for manufacturing molten iron by melting reduced ore; and
FIG. 2 is a longitudinal sectional view illustrating a reduction furnace according to an embodiment of the present invention.

[Best Mode]

Hereinafter, an embodiment of the present invention is described in detail with reference to the accompanying drawings.
FIG. 2 is a longitudinal sectional view illustrating a reduction furnace 100 according to an embodiment of the present invention. Referring to FIG. 2, a charge feeding port 110 and a plurality of exhaust gas discharge ports 120 are included in an upper portion of the reduction furnace 110. A deadman 180 (or a deadwoman, hereinafter, both terms are used interchangeably) is installed in a lower end of the inside of the reduction furnace 100. The deadman 180 is installed to prevent the degradation of the charge material due to the accumulative load of the charge material itself or formation of a stationary bed. A reducing gas intake port 170 is installed in a bottom portion of the deadman 180 and a path is formed inside the deadman 180 so as to allow the reducing gas injected through the reducing gas intake port 170 to pass therethrough. The reducing gas intake port 170 is formed in the center of the reduction furnace 100 in a radial direction, and the path inside the deadman 180 connected to the reducing gas intake port 170 may be formed in plural to be symmetrical in the radial direction.
A vertical down pipe 140 connected to the reduction furnace 100 is installed in a lower portion of the reduction furnace 100 and a drop box 150 is installed in an end portion of the vertical down pipe 140. A discharge screw 130, an attachable and detachable device for supplying a fixed amount of the charge material, is installed in the drop box 150. A tilt down pipe 160 connected to a dome portion of a melting furnace is installed in a lower portion of the drop box 150.
The charge material is introduced into the reduction furnace 100 through the charge feeding port 110. The charge material reduced in the reduction furnace 100 is transferred to the vertical down pipe 140 to be discharged by the discharge screw 130 formed in the end portion of the vertical down pipe 140 in a fixed amount. The discharged charge material is supplied to the melting furnace through the tilt down pipe 160. Meanwhile, reducing gas reduces the charge material and is then discharged through the exhaust gas discharge ports 120.
Inner portions of the reduction furnace 100 and the vertical down pipe 140 are filled with the charge material in normal operating conditions.
According to the configuration of the foregoing reduction furnace 100, reducing gas from the melting furnace is allowed to be injected thereinto by the installation of the reducing gas intake port 170 having the reducing gas passed therethrough in the bottom portion of the deadman 180 installed at the lower end of the inside of the reduction furnace, instead of a typical reducing gas intake port disposed on an intermediate wall portion of the reduction furnace, and thus, uniform distribution in the radial direction may be induced from a typical non-uniform distribution phenomenon of the reducing gas, a reducing gas utilization ratio and a reduction rate of the charge material may be increased, and the reduction rate thereof may be uniformized. Also, an increase in production, a decrease in fuel costs, an increase in an operating ratio, and an increase in operational stability may be achieved by reducing a thermal load of the melting furnace when the charge material is provided to the melting furnace. Further, since the reducing gas may be uniformly distributed in the radial direction of the reduction furnace, an increase in the capacity of facility may be achieved by simply increasing the reduction furnace 100 and the deadman 180 in the radial direction thereof during the increase in the capacity of the reduction furnace 100.
Also, since the discharge screw 130, a device for supplying a fixed amount of the charge material, is installed in a portion of the drop box 150 instead of the lower end of the reduction furnace, a reduction in pressure in the vertical down pipe 140 is generated, and thus, a back flow of high-pressure reducing gas in the melting furnace into the reduction furnace 100 through the discharge screw 130 may be prevented. That is, the back flow of high-pressure reducing gas in the melting furnace disposed at a lower portion of the tilt down pipe 160 into the reduction furnace 100 due to the generation of differential pressure in the vertical down pipe 140 may be prevented. Typically, installation of an unreduced height h of the charge material is essential for the purpose of generating a reduction in pressure in the reducing gas in order to prevent the back flow of the reducing gas through the discharge screw 130. However, since the pressure loss may be generated through the vertical down pipe 140 in the present invention, the height of the reduction furnace 100 may be reduced by as much as the unreduced height h of the charge material illustrated in FIG. 1.
Further, nitrogen is typically injected into the vertical down pipe 140 for the purpose of reducing thermal shock applied to the discharge screw 130 by gas flowing backwards from the melting furnace into the reduction furnace 100. However, since nitrogen injected into the vertical down pipe 140 may not be required in the reduction furnace 100 according to the present invention, the amount of nitrogen used may be reduced and operational costs may be reduced.
While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

A reduction furnace comprising:
a charge feeding port 110 having a charge material introduced therethrough; and

a reducing gas intake port 170 having reducing gas injected therethrough,

wherein the charge feeding port 110 is formed in an upper portion thereof and the reducing gas intake port 170 is installed in a bottom portion thereof.
The reduction furnace of claim 1, further comprising a deadman 180 disposed in a lower portion thereof,
wherein the reducing gas intake port 170 is installed in a bottom portion of the deadman 180.
The reduction furnace of claim 2, a path connected to the reducing gas intake port 170 is formed inside the deadman 180.
The reduction furnace of claim 3, the path is formed in plural to be symmetrical in a radial direction.
The reduction furnace of any one of claims 1 to 4, further comprising a vertical down pipe 140 having the charge material reduced by the reducing gas discharged therethrough,
wherein inside of the vertical down pipe 140 is filled with the charge material in normal operating conditions.
The reduction furnace of claim 5, wherein a drop box 150 is installed in an end portion of the vertical down pipe 140 and a discharge screw 130 discharging a fixed amount of the charge material is installed in the drop box 150.
The reduction furnace of claim 6, wherein the vertical down pipe 140 has a predetermined vertical length to generate pressure drop in gas flowing backward into the reduction furnace through the vertical down pipe 140.