WO2007075025A1

WO2007075025A1 - Method for manufacturing molten irons by injecting a hydrocarbon gas and apparatus for manufacturing molten irons using the same

Info

Publication number: WO2007075025A1
Application number: PCT/KR2006/005702
Authority: WO
Inventors: Eung-Soo Choi; Jin-Chan Bae; Woon-Jae Lee
Original assignee: Posco Co Ltd
Current assignee: Posco Holdings Inc
Priority date: 2005-12-26
Filing date: 2006-12-26
Publication date: 2007-07-05
Anticipated expiration: 2008-06-26
Also published as: KR20070068214A; CN101346478A; KR101235252B1; CN101346478B

Abstract

The present invention relates to a method for manufacturing molten iron by injecting a hydrocarbon gas and an apparatus for manufacturing molten iron using the same. A method for manufacturing molten iron according to an embodiment of the present invention includes: i) converting iron ore into reduced materials while passing the iron ore through a reduction reactor, ii) charging lumped carbonaceous materials into a melter-gasifier connected to the reduction reactor and forming a coal-packed bed in the melter-gasifier, iii) charging the reduced materials into the melter-gasifier connected to the reduction reactor, injecting oxygen, vapor, and hydrocarbon gas together into a lower portion of the coal-packed bed and manufacturing molten iron, and iv) supplying a reducing gas discharged from the melter-gasifier to the reduction reactor. The vapor is injected to prevent the oxygen and the hydrocarbon gas from contacting each other in the manufacturing of molten iron.

Description

METHOD FOR MANUFACTURING MOLTEN IRONS BY INJECTING A HYDROCARBON GAS AND APPARATUS FOR MANUFACTURING MOLTEN

IRONS USING THE SAME

Technical Field

The present invention relates to a method for manufacturing molten iron by injecting a hydrocarbon gas and an apparatus for manufacturing molten iron using the same, and more specifically to a method for manufacturing molten iron and an apparatus for manufacturing molten iron using the same for injecting a hydrocarbon gas to secure a heating source for melting reduced iron and generating a reducing gas having good quality, by injecting the hydrocarbon gas into a melter-gasifier. Background Art

The iron and steel industry is a core industry that supplies the basic materials needed in construction and in the manufacture of automobiles, ships, home appliances, and many of the other products we use. It is also an industry with one of the longest histories that has progressed together with humanity. In an iron foundry, which plays a pivotal roll in the iron and steel industry, after molten iron, which is pig iron in a molten state, is produced by using iron ore and coal as raw materials, steel is produced from the molten iron and is then supplied to customers.

At present, approximately 60% of the world's iron production is realized by using the blast furnace process developed from the 14th century. In the blast furnace process, coke produced by using bituminous coal and iron ore that have undergone a sintering process are charged into a blast furnace, and hot gas is supplied to the blast furnace to reduce the iron ore to iron, to thereby manufacture molten iron. However, in the blast furnace process, there are problems in that accessory equipment is necessary to manufacture coke and sintered ore, and environmental pollution is very severe due to the accessory equipment. In order to solve the above problems of the blast furnace process, a smelting reduction process has been developed and researched by many countries. In the smelting reduction process, molten iron is manufactured in a melter-gasifier by directly using raw coal as a fuel, and a reducing agent and iron ore as iron sources. Here, oxygen is injected through a plurality of tuyeres installed in an outer wall of the melter-gasifier, and a coal-packed bed in the melter-gasifier is burned. The oxygen is converted into a hot reducing gas and is transferred to a fluidized-bed reduction reactor. Then, the hot reducing gas reduces iron ore and is discharged outside.

Lumped coal or coal briquettes as a heat source are charged into the melter-gasifier. Manufacturing cost depends on a charging amount of coal. Therefore, iron ore having a high reducing ratio should be charged into the melter-gasifier to minimize a charging amount of coal. For this, a reducing gas of good quality should be supplied to the fluidized-bed reduction reactor and a reducing ratio of the iron ore should be increased by a maximum degree.

The iron ore can be reduced by using hydrogen and carbon monoxide included in the reducing gas. Therefore, a large amount of hydrogen and carbon monoxide should be generated in the melter-gasifier from which the reducing gas is generated.

Lumped coal and coal briquettes are charged into the melter-gasifier, and then a coal-packed bed is formed therein. The reducing gas is generated from the coal-packed bed. The carbon and hydrogen in the form of carbon and water exist in the lumped coal and coal briquettes. Therefore, an activity in the melter-gasifier should be controlled to completely convert the elements included in the lumped coal and coal briquettes into reducing gas. However, it is difficult to control the activity in the melter-gasifier due to various parameters. For example, there is a problem that some carbon included in the lumped coal and coal briquettes is oxidized to carbon dioxide and so on, thereby not being able to contribute to reducing the iron ore.

DISCLOSURE Technical Problem

The present invention is contrived to provide a method for manufacturing molten iron capable of increasing an amount of reducing gas and improving the quality of molten iron by injecting a hydrocarbon gas.

In addition, the present invention is contrived to provide an apparatus for manufacturing molten iron using the above method for manufacturing molten iron.

Technical Solution

A method for manufacturing molten iron according to an embodiment of the present invention includes i ) converting iron ore into reduced materials while passing the iron ore through a reduction reactor, ii ) charging lumped carbonaceous materials into a melter-gasifier connected to the reduction reactor and forming a coal-packed bed in the melter-gasifier, iii) charging the reduced materials into the melter-gasifier connected to the reduction reactor, injecting oxygen, vapor, and hydrocarbon gas together into a lower portion of the coal-packed bed and manufacturing molten iron, and iv) supplying a reducing gas discharged from the melter-gasifier to the reduction reactor. The vapor is injected to prevent the oxygen and the hydrocarbon gas from contacting with each other in the manufacturing of the molten iron. The amount of the oxygen may be two times or more an amount of the hydrocarbon gas in the manufacturing of the molten iron. The reduction reactor may be the fluidized-bed reduction reactor or a packed-bed reduction reactor in the converting of the iron ore into reduced materials. The vapor may interact with the hydrocarbon gas and the reducing gas may be generated in the manufacturing of the molten iron.

An apparatus for manufacturing molten iron according to an embodiment of the present invention includes i ) a reduction reactor that reduces iron ore and converts the iron ore into reduced materials, ii ) a melter-gasifier into which lumped carbonaceous materials and the reduced materials are charged, the melter-gasifier that forms a coal-packed bed and includes a tuyere through which oxygen, vapor, and hydrocarbon gas are injected, the tuyere installed in a lower portion of the coal-packed bed, the melter-gasifier connected to the reduction reactor and that manufactures molten iron, and iii) a reducing gas supply line that supplies a reducing gas discharged from the melter-gasifier into the reduction reactor. The vapor is injected to prevent the oxygen and the hydrocarbon gas from contacting each other.

It is preferable that an opening is formed in the tuyere and that a dual tube is inserted in the opening. The dual tube may include an inner tube and an outer tube surrounding the inner tube, and the vapor may be injected into a space between the inner tube and the outer tube. The hydrocarbon gas may be injected into the inner tube. The oxygen may be injected into an opening located at an outer space of the dual tube.

An end portion of the tuyere directed to the melter-gasifier and an end portion of the dual tube may be located on the same line. The amount of oxygen may be two or more times the amount of hydrocarbon gas. The reduction reactor may be a fluidized-bed reduction reactor or a packed-bed reduction reactor. Advantageous Effects

In an embodiment of the present invention, the oxygen and the hydrocarbon gas are prevented from contacting each other and are injected by using a vapor, and damage by melting of the tuyere and the dual tube can be prevented. In addition, the vapor may directly contact the hydrocarbon gas and the reducing gas may be generated, and a heat load to end portions of the tuyere and the dual tube can be reduced.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of an apparatus for manufacturing molten iron according to a first embodiment of the present invention. FIG. 2 is a schematic view of an apparatus for manufacturing molten iron according to a second embodiment of the present invention.

FIG. 3 is a conceptional view of an injecting state of a hydrocarbon gas. FIG. 4 is a cross-sectional view of a gas injector provided in an apparatus for manufacturing molten iron according to an embodiment of the present invention.

BEST MODE

With reference to FIGs.l to 4, embodiments of the present invention will be described in order for those skilled in the art to be able to implement it. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Wherever possible, the same reference numbers will be used throughout the drawings for the same or like parts. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

FIG. 1 illustrates a molten iron manufacturing apparatus 100 according to a first embodiment of the present invention. The apparatus for manufacturing molten iron 100 illustrated in FIG. 1 includes a reduction reactor 30 and a melter-gasifier 60. In addition, other devices may be further included as necessary. The iron ore is charged into the reduction reactor 30 and is reduced. Additives may be also used as necessary. The iron ore that is to be charged into the reduction reactor 30 is pre-dried as a form of lumped coal. The iron ore is converted into reduced materials while passing through the reduction reactor 30. The reduction reactor 30 is a packed-bed reduction reactor, and a reducing gas is supplied thereto from the melter-gasifier 60. Then, a packed bed is formed therein, and iron ore is converted into reduced materials while passing through the packed bed. The lumped carbonaceous materials are charged into an upper portion of the melter-gasifier 60 and then a coal-packed bed is formed therein. For example, lumped coal and coal briquettes can be used as the lumped carbonaceous materials. The coal briquettes are made by compressing fine coal. In addition, coke may also be charged as necessary. Tuyeres 601 are installed in an outer wall of the melter-gasifier 60, and the hydrocarbon gas A, vapor B, and oxygen C are injected together therethrough.

The hydrocarbon gas A is all gasses that include hydrocarbon. For example, the hydrocarbon gas can be liquid natural gas (LNG). The hydrocarbon gas is preferable to generate the reducing gas because the hydrocarbon gas A, vapor B, and oxygen C are injected into a lower portion of the coal-packed bed and combust the coal-packed bed. In addition, since the hydrocarbon gas A, vapor B, and oxygen C are injected together, an amount of the reduction gas can be increased while the tuyere can be cooled by interacting them with each other.

The materials that are reduced in the reduction reactor 30 are charged into an upper portion of the melter-gasifier 60, pass through the coal-packed bed, and are melted. Molten iron can be manufactured by using the above method. A tap is installed in a lower portion of the melter-gasifier 60 and the molten iron and slag are discharged therethrough.

A reducing gas containing hydrogen and carbon monoxide is generated from the coal-packed bed formed in the melter-gasifier 60. The reducing gas is generated well in the melter-gasifier 60 due to the dome-shaped upper portion thereof. The reducing gas discharged from the melter-gasifier 60 is supplied to the reduction reactor 30 through the reducing gas supply line 70. Therefore, iron ore can be reduced and plasticized by the reducing gas.

FIG. 2 illustrates an apparatus for manufacturing molten iron according to a second embodiment of the present invention. The melter-gasifier 60 illustrated in FIG. 2 is the same as that illustrated in FIG. 1, and like reference numerals refer to like elements and a detailed description thereof is omitted.

The molten iron manufacturing apparatus 200 includes at least one fluidized-bed reduction reactor 20, a melter-gasifier 60, a reducing gas supply line 70, and a compacted iron manufacturing apparatus 40. In addition, a hot pressure equalizing device 50 for transferring compacted iron manufactured in the compacted iron manufacturing apparatus 40 to the melter-gasifier 60 can be further included. The hot pressure equalizing device 50 forcibly transfers compacted iron manufactured in the compacted iron manufacturing apparatus 40 to the melter-gasifier 60. The compacted iron manufacturing apparatus 40 and the hot pressure equalizing device 50 can be omitted depending on the case. The compacted iron can be temporarily stored in a storage bin 52.

The molten iron manufacturing apparatus 200 can use fine iron ore, and additives can be further used as necessary. A fluidized-bed is formed in the fluidized-bed reduction reactor 20 and reduces the iron ore. The fluidized-bed reduction reactor 20 includes a first fluidized-bed reduction reactor 201, a second fluidized-bed reduction reactor 203, a third fluidized-bed reduction reactor 205, and a fourth fluidized-bed reduction reactor 207. The first fluidized-bed reduction reactor 201 preheats the iron ore by using a reducing gas discharged from the second fluidized-bed reduction reactor 203.

The second and third fluidized-bed reduction reactors 203 and 205 pre-reduce the preheated iron ore. In addition, the fourth fluidized-bed reduction reactor 207 finally reduces the pre-reduced iron ore and converts it into the reduced materials.

The iron ore are reduced and heated while passing through the fluidized-bed reduction reactor 20. For this, the reducing gas generated from the melter-gasifier 60 is supplied to the fluidized-bed reduction reactor 20 through the reducing gas supply line 70. The reduced iron ore is manufactured into compacted iron by the compacted iron manufacturing apparatus 40.

The compacted iron manufacturing apparatus 40 includes a charging hopper 401, a pair of rollers 403, a crusher 405, and a storage bin 407. In addition, other devices may be further included as necessary. The charging hopper 401 stores the reduced iron ore that is reduced while passing through the fluidized-bed reduction reactor 20. The iron ore is charged into the pair of rollers 403 from the charging hopper 401 and then pressed into a shape of a strip. The pressed iron ore is crushed by the crusher 405 and stored in the storage bin 407 as compacted iron.

FIG. 3 schematically illustrates an injecting state of the hydrocarbon gas A, vapor B, and oxygen C from the tuyere 601 illustrated in FIG. 1. A dual tube 603 is inserted in an opening 6015 formed in the tuyere 601.

For example, a lance can be used as the dual tube 603. The dual tube 603 includes an inner tube 6031 and an outer tube 6033 surrounding the inner tube 6031. Therefore, three spaces including an opening 6015 of the dual tube 603, a space between the inner tube 6031 and the outer tube 6033, and an inner portion of the inner tube 6031 are formed. Therefore, different gases can be supplied to the three spaces to be injected into the melter-gasifier 60.

In an embodiment, the hydrocarbon gas A, vapor B, and oxygen C are injected together. A reducing ratio of the iron ore can be improved by injecting the hydrocarbon gas A and increasing an amount of the reducing gas. Therefore, an amount of lumped carbonaceous materials charged into the melter-gasifier 60 can be reduced. In addition, the temperature of a combustion area can be stably controlled by injecting the hydrocarbon gas A. Therefore, the quality of molten iron can be improved by largely reducing an amount of silicon Si included in the molten iron. In addition, a generating amount of a carbon dioxide can be largely reduced by injecting the hydrocarbon gas A.

In an embodiment, the oxygen C and the hydrocarbon gas A are prevented from directly contacting each other and are injected by using the vapor B. Therefore, a phenomenon in which the hydrocarbon gas A is ignited by the oxygen C and end portions of the tuyere 601 and the dual tube 603 are damaged by being melted can be prevented. That is, since a combustion focus is spaced apart from the end portion of the tuyere 601 toward the inner portion of the melter-gasifier 60 by equal to or more than lcm, the end portions of the tuyere 601 and the dual tube

603 can be prevented from being damaged by being melted by the combustion heat.

For this, as illustrated in FIG. 3, the hydrocarbon gas A is injected through the inner tube 6031, and the vapor B is injected through the space between the inner tube 6031 and the outer tube 6033. The oxygen C is injected through the opening 6015 located outside of the dual tube 603. It is preferable that the oxygen C is injected through the opening 6015 that has a relatively large space since a large amount of oxygen should be injected to the combustion area in the coal-packed bed. The amount of oxygen C may be two times or more that of the hydrocarbon gas A. If the amount of the oxygen C is less than that of the hydrocarbon gas A, stable combustion is difficult to be realized since the amount of the oxygen C is deficient.

The above gas injection method is merely to illustrate the present invention and the present invention is not limited thereto. Therefore, using another type of tuyere, the vapor B can prevent the oxygen C and the hydrocarbon gas A from contacting with each other when being injected. Meanwhile, as illustrated in FIG. 3, it is preferable that an end portion of the tuyere 601 directed to the melter-gasifier 60 and an end portion of the dual tube 603 are located on the same line (P). The oxygen C and the hydrocarbon gas A directly contact each other and then the hydrocarbon gas A is ignited, thereby there is a high possibility that the end portion of the tuyere 601 can be damaged by being melted if the end portion of the dual tube 603 is located behind the end portion of the tuyere 601. On the contrary, the dual tube 603 can be broken due to an impact of charged materials in the melter-gasifier 60 if the end portion of the dual tube 603 is located in front of the end portion of the tuyere 601.

Since the vapor B directly contacts the hydrocarbon gas A, the reducing gas is generated by an interaction therewith. The reacting process is described as Chemical Formula 1. [Chemical Formula 1]

CH₄ + H₂O → CO +3H₂, ΔH = + 228,000kJ/kg-mol

Here, CH4 is a main element of the hydrocarbon gas A. As described in Chemical Formula 1, the vapor B contacts the hydrocarbon gas A and is then decomposed into hydrogen and carbon monoxide while causing an endothermic reaction that absorbs ambient heat. Therefore, the tuyere 601 and the dual tube 603 can be prevented from being overheated and damaged by being melted since the heat load to the tuyere 601 and the dual tube 603 is reduced.

In addition, the vapor B generates a large amount of hydrogen and carbon monoxide by contacting the hydrocarbon gas A. Particularly, iron ore can be reduced well since the hydrogen whose amount is about three times or more that of the carbon monoxide is generated and the hydrogen an excellent reducing power compared to carbon monoxide.

FIG. 4 illustrates a cross-sectional structure of a gas injector 80 provided in a molten iron manufacturing apparatus according to an embodiment of the present invention. The structure of the gas injector 80 illustrated in FIG. 4 is merely to illustrate the present invention and the present invention is not limited thereto.

Therefore, the structure of the gas injector 80 can be modified in other forms.

The hydrocarbon gas A, vapor B, and oxygen C can be injected together through a gas injector 80. The gas injector 80 includes the tuyere 601 and the dual tube 603. In addition, the gas injector 80 may further include other parts as necessary.

A cooling water jacket 6011 is formed in the tuyere 601 and cooling water flows therein. Therefore, the tuyere 601 can be prevented from being damaged by being overheated. A valve 6037 is installed in the inner tube 6031 included in the dual tube 603. The amount of the hydrocarbon gas A injected into the melter-gasifier can be controlled by controlling the valve 6037. Further, a vapor injecting port 6035 is installed outside of the outer tube 6033 included in the dual tube 603. The vapor B is supplied through the vapor injecting port 6035. In addition, the oxygen C is supplied through the oxygen injecting port 6013 connected to the opening 6015. Therefore, the hydrocarbon gas A, vapor B, and oxygen C can be injected together into a lower portion of the coal-packed bed.

Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and /or modifications of the basic inventive concept taught herein still fall within the spirit and scope of the present invention, as defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing molten iron, comprising: converting iron ore into reduced materials while passing the iron ore through a reduction reactor; charging lumped carbonaceous materials into a melter-gasifier connected to the reduction reactor and forming a coal-packed bed in the melter-gasifier; charging the reduced materials into the melter-gasifier connected to the reduction reactor, injecting oxygen, vapor, and hydrocarbon gas together into a lower portion of the coal-packed bed and manufacturing molten iron; and supplying a reducing gas discharged from the melter-gasifier to the reduction reactor, wherein the vapor is injected to prevent the oxygen and the hydrocarbon gas from contacting each other in the manufacturing of molten iron.

2. The method of Claim 1, wherein the amount of oxygen is two times or more an amount of the hydrocarbon gas in the manufacturing of molten iron.

3. The method of Claim 1, wherein the reduction reactor is the fluidized-bed reduction reactor or a packed-bed reduction reactor in the converting the iron ore into reduced materials.

4. The method of Claim 1, wherein the vapor is interacted with the hydrocarbon gas and the reducing gas is generated in the manufacturing molten iron.

5. An apparatus for manufacturing molten iron, comprising: a reduction reactor that reduces iron ore and converts the iron ore into reduced materials; a melter-gasifier into which lumped carbonaceous materials and the reduced materials are charged, the melter-gasifier forming a coal-packed bed and comprising a tuyere through which oxygen, vapor, and hydrocarbon gas are injected, the tuyere installed in a lower portion of the coal-packed bed and the melter-gasifier connected to the reduction reactor that manufactures molten iron; and a reducing gas supply line that supplies a reducing gas discharged from the melter-gasifier into the reduction reactor, wherein the vapor is injected to prevent the oxygen and the hydrocarbon gas from contacting each other.

6. The apparatus of Claim 5, wherein an opening is formed in the tuyere and a dual tube is inserted in the opening.

7. The apparatus of Claim 6, wherein the dual tube comprises an inner tube and an outer tube surrounding the inner tube, and the vapor is injected into a space between the inner tube and the outer tube.

8. The apparatus of Claim 7, wherein the hydrocarbon gas is injected into the inner tube.

9. The apparatus of Claim 6, wherein the oxygen is injected into an opening located in an outer space of the dual tube.

10. The apparatus of Claim 6, wherein an end portion of the tuyere directed to the melter-gasifier and an end portion of the dual tube are located on the same line.

11. The apparatus of Claim 5, wherein an amount of the oxygen is two times or more than an amount of the hydrocarbon gas.

12. The apparatus of Claim 5, wherein the reduction reactor is a fluidized-bed reduction reactor or a packed-bed reduction reactor.