JP2002213883A - Method of refining metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal-refining method which is markedly economical compared with a conventional art, using oxygen gas being manufactured through a gas-separating membrane consisting of a metal oxide film. SOLUTION: The exhaust gas discharged from a furnace top is pressurized with a gas compressor 6, and is supplied to a high-pressure combustor 7, while for air, its one part is supplied to the high-pressure combustor 7 after pressurization in an air compressor 8, and is mixed with high-pressure gas and burned, and the combustion gas drives a gas turbine 9. Both gas compressor 6 and the air compressor 8 are driven by this gas turbine 9. The remainder of the pressurized air becomes hot, being heated further with a heating burner 11 after being heated with a heat exchanger 10, and is supplied to an oxygen manufacturing unit 13. The oxygen manufacturing unit 13 is one using a composite metal oxide film. The separated oxygen is compressed to a high-pressure by an oxygen compressor 15 and is stored in high pressure oxygen holder 16, and is supplied to a cupola 1. The oxygen compressor 15 is also driven by the gas turbine 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for generating electricity by using a high-calorie gas obtained when refining a metal as a fuel for power generation by a gas turbine combined cycle power generation system, and to generate high temperature and high pressure gas generated at this time. The present invention relates to a method for refining a metal which is significantly more economical than the prior art, utilizing oxygen energy to produce and use oxygen gas through a gas separation membrane composed of a metal oxide film.

[0002]

2. Description of the Related Art Various methods of refining iron are known, but there are various problems in reducing the cost of refining. For example, today, from the viewpoint of resource recycling, there is a demand for producing steel by using iron scrap generated in large quantities. In response to such demands, steel scrap is conventionally produced by melting iron scrap as it is in an electric furnace, mainly an electric arc furnace. However, since this method consumes a large amount of oxygen and expensive electric power of about 350 to 400 kwh per ton of steel, a more economical steel production method is required.

[0003] Thus, a method of melting steel scrap in a cupola in advance and producing steel in an electric furnace using the obtained hot metal as a raw material has already been disclosed. JP-A-6-2876
No. 21 discloses a method in which a vertical furnace such as a cupola is used in combination with a converter or an arc furnace. In addition, Japanese Patent Application Laid-Open Nos.
In 297720, the exhaust gas obtained from cupola can be used as a fuel for power generation at 1500 kcal / Nm.
Processes that can be recovered as ^three or more high calories have been proposed. The purpose of this is to obtain hot metal whose production cost is low by recovering exhaust gas as electric power.

[0004]

However, there is still a strong demand for refining iron and other metals at the lowest possible cost, and Japanese Patent Application Laid-Open No. 6-287621.
JP-A-8-25746 and JP-A-8-297
There is a need for a method for performing refining at a lower cost than the refining method described in Japanese Patent Publication No. 720-720.

The present invention has been made in view of such circumstances, and provides a method of refining a metal at a low cost, which could not be realized conventionally, by employing a novel method. That is the task.

[0006]

Means for Solving the Problems A first method for solving the above problems is described below.
Means is a method of refining a metal by blowing oxygen gas, (a) using, as the oxygen gas, an oxygen gas produced by an oxygen separation device having a gas separation film made of a metal oxide film, b) The exhaust gas generated during refining is collected and compressed by a gas compressor, and then used as fuel for a combustor. (c) A gas turbine is driven by combustion gas exiting the combustor, and (d) A metal refining method comprising: driving at least a gas compressor, an air compressor for compressing air supplied to the oxygen separator and the combustor, and a generator by a gas turbine (claim) Item 1).

[0007] A major technical problem in economically refining metals such as iron (hereinafter, iron will be described as an example) is to establish a technique for providing inexpensive oxygen. The present inventors have paid close attention to the fact that a method of separating oxygen from air through a mixed conductive film that conducts both oxygen ions and electrons is an effective oxygen production method, and made intensive studies.

In order to use such an oxygen separation method, the pressure of the air supplied to the oxygen separation device must be high. The present inventors have focused on the fact that exhaust gas obtained from refining equipment has high calories, and by introducing an air compressor into a gas turbine combined cycle power generation system using this as a fuel, the energy of the exhaust gas can be effectively used. The present inventors have found that a method for producing compressed air by utilizing the method is efficient, and have accomplished the present invention. Hereinafter, the present invention will be described in detail.

The composite metal oxide film used in the present invention is a mixed conductive film that conducts both oxygen ions and electrons, and is several tens μm to several hundred μm in view of the relationship between the oxygen transmission rate and the film strength.
m. Further, as shown in FIG. 4, a support made of a porous material having continuous through holes can be used for reinforcing the membrane strength.

As the mixed conductive film, there is a perovskite-type metal oxide or a metal oxide-stabilized zirconia such as yttria-stabilized zirconia and calcium-stabilized zirconia. Further, as the support of the porous material, a material which does not form a mixed metal oxide such as a mixed conductive film and spinel and has the same coefficient of thermal expansion is preferable.

The surface area of the mixed conductive film is appropriately determined depending on the required amount of oxygen. However, the specific surface area is increased by forming irregularities on the film surface in order to increase the gas-solid contact area between the supply gas and the film. The area occupied by the film can be reduced. As the film shape, there is a shell tube structure in which a composite metal oxide thin film is formed on the outer surface of a planar film or a tubular porous support, and the film shape can be selected according to the purpose of use.

In the mixed conductive membrane, the difference in oxygen partial pressure between the air side and the oxygen side across the membrane becomes a driving force for oxygen separation. Therefore, the oxygen permeation rate is improved by pressurizing the air side or purging the oxygen side with a non-permeating gas or nitrogen to reduce the oxygen partial pressure on the oxygen side. Among them, a method of pressurizing air to about 1 to 50 kg / cm ² is generally used. Also, since the working temperature of the mixed conductive film is in the range of 500 ° C to 1300 ° C,
The feed air must be heated to a temperature in this range.

Using the oxygen producing apparatus having the composite metal oxide film configured as described above, oxygen is separated from air compressed by a gas turbine driven by high-pressure combustion gas of exhaust gas from a refining facility to separate oxygen for refining. It can be used as oxygen and produce electricity with a gas turbine.
Further, in a combustor for driving a gas turbine, it is necessary to mix and burn high-pressure gas and air. For this purpose, the compression of exhaust gas and the compression of air are also performed by the compression driven by this gas turbine. Machine.

Although various methods can be used for the iron refining equipment used in the present invention, a process that generates a large amount of exhaust gas having high calories is desirable. Examples include a cupola for melting scrap, a converter, a smelting reduction furnace, and the like. As the carbon material used for these, coal, coke, plastic and various wastes are suitable. It goes without saying that the carbon in the hot metal also becomes a fuel.

As described above, by using an oxygen production apparatus having a composite metal oxide film and adopting an apparatus configuration such as this means, power can be generated and oxygen required for iron refining can be efficiently secured. can do. Further, oxygen can be easily supplied without a new piping from the existing oxygen production equipment, which is required in the conventional cryogenic separation method.

In addition, when a new conventional oxygen supply facility is provided, even if oxygen supply by a relatively small on-site PSA is considered, a site area of several tens m ² and additional facilities are required. Become. According to this means, the equipment can be made very compact and extremely economical in comparison with this.

In this means, it goes without saying that the produced oxygen can be supplied to other equipment and used in other equipment.

A second means for solving the above-mentioned problem is as follows.
The first means, wherein the air supplied to the oxygen separator is heated by the heat of the remaining exhaust gas of the oxygen separated by the oxygen separator (claim 2). It is.

Since the separation of oxygen by the gas separation film made of a metal oxide film is performed at a high temperature, the supplied air must be heated, and both the separated oxygen and the remaining gas have a high temperature. In this means, since the air supplied to the oxygen separation device is heated by the heat of the remaining gas, the thermal efficiency can be improved.

A third means for solving the above-mentioned problem is as follows.
The second means, wherein the remaining exhaust gas after heating the air is supplied to the combustor together with the air (Claim 3).

In the second means, the gas after heating the air supplied to the oxygen separator is still at a high temperature. In this means, since this gas is supplied to the combustor together with the air, the thermal efficiency can be further increased.

A fourth means for solving the above problem is as follows.
Any one of the first means to the third means, wherein oxygen immediately before burning the carbon material is heated by oxygen immediately after being separated by the oxygen separation device (claim) Item 4).

As described above, the oxygen immediately after being separated by the oxygen separator has a high temperature. Therefore, by heating the oxygen immediately before burning the carbon material with this oxygen, the thermal efficiency in a reaction furnace or the like for burning the carbon material can be increased.

A fifth means for solving the above problem is as follows.
Any one of the first to fourth means, wherein steam is generated by a combustion gas after driving the gas turbine, and power is generated by the steam. ).

The combustion gas after driving the gas turbine is still hot. Therefore, by generating steam by the heat of the gas and generating power by the steam,
Thermal efficiency can be further increased.

A sixth means for solving the above-mentioned problem is:
An oxygen gas blowing facility for refining metal, an exhaust gas compressor for pressurizing exhaust gas generated from a furnace for refining metal, an air compressor for pressurizing air, and the pressurized exhaust gas. A combustor for mixing and burning the air, a gas turbine driven by combustion gas generated by combustion of the exhaust gas in the combustor, a heating device for heating the pressurized air, and the heating device. An oxygen separator that separates oxygen from the air heated by a gas separation membrane made of a metal oxide film, an oxygen compressor that pressurizes the separated oxygen, and a generator. The turbine drives the exhaust gas compressor, the air compressor, the oxygen compressor and the generator, and the pressurized oxygen is blown to burn carbon material. It is refining apparatus of the metal, wherein (claim 6) being.

[0027] A seventh means for solving the above problem is as follows.
The sixth means, comprising a heat exchanger for performing heat exchange between oxygen separated by the oxygen separation device and remaining exhaust gas and air supplied to the oxygen separation device. This is a feature (claim 7).

Eighth means for solving the above-mentioned problem is:
The seventh means is characterized in that the exhaust gas exiting the heat exchanger is supplied to the combustor together with air (claim 8).

A ninth means for solving the above-mentioned problem is:
The heat exchanger according to any one of the sixth to eighth means, wherein the heat exchanger performs heat exchange between oxygen immediately after being separated by the oxygen separation device and oxygen immediately before burning the carbon material. (Claim 9).

A tenth means for solving the above-mentioned problem is any of the sixth means to the ninth means, wherein the heat of the combustion gas after driving the gas turbine is used as a heat source. (Claim 10).

According to the sixth to tenth means, the methods of the first to fifth means can be realized, respectively, and the same operation and effect can be achieved.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an iron smelting facility using cupolas, which is an example of an embodiment of the present invention. Iron scrap and coal are charged from a charging port 2 above the cupola 1, and high-purity oxygen is blown from a tuyere 3 provided below the charging port. Thereby, the iron scrap is refined, and the hot metal is taken out from the tap hole 4 of the cupola 1.

The exhaust gas discharged from the furnace top is reduced in dust by a dust remover 5, then pressurized by a gas compressor 6 and supplied to a high-pressure combustor 7. On the other hand, after the air is compressed by the air compressor 8, a part of the air is supplied to the high-pressure combustor 7. In the high-pressure combustor 7, high-pressure gas and high-pressure air are mixed and burned, and the combustion gas is supplied to the gas turbine 9 to drive the gas turbine 9. The gas compressor 6 and the air compressor 8 are both driven by the gas turbine 9.

The remainder of the pressurized air is heated by the heat exchanger 10, further heated by the heating burner 11 to a high temperature, and supplied to the oxygen producing apparatus 13. As described above, the oxygen production apparatus 13 uses a composite metal oxide film, and high-purity oxygen is separated through the composite metal oxide film. The separated oxygen is led to the heat exchanger 14 and heats the oxygen supplied to the cupola 1 to lower the temperature of the oxygen itself. After that, the oxygen is compressed by the oxygen compressor 15 and stored in the high-pressure oxygen holder 16. . Then, after being heated by the heat exchanger 14, it is supplied to the cupola 1 as described above. The oxygen compressor 15 is also driven by the gas turbine 9.

As described above, the gas turbine 9 drives the gas compressor 6, the air compressor 8, and the oxygen compressor 9, but the surplus power drives the generator 17 and is recovered as electric power.
Since the gas discharged from the gas turbine 9 is still hot, the steam turbine 19 is driven by the steam generated by being guided to the steam generator 18, thereby driving the generator 20, and using the waste heat of the gas as electric power. to recover. In addition, 21 is a condenser.

The gas containing nitrogen as a main component separated from the oxygen production equipment 13 is heated in air by the heat exchanger 10,
It is mixed into the air guided to the high pressure combustor 7. Thereby, the heat in the gas is effectively recovered. The generated oxygen can be supplied to equipment other than the present system, for example, other metal refining equipment, refuse incinerators, activated sludge treatment equipment, and the like.

As described above, the apparatus shown in FIG. 1 utilizes the energy of the exhaust gas of the cupola 1 to
Since oxygen is generated and heat is recovered by power generation, iron smelting can be performed at extremely low cost.

FIG. 2 is a schematic diagram showing a steel refining facility using a converter, which is an example of an embodiment of the present invention.
In the following drawings, the same components as those shown in the preceding drawings are denoted by the same reference numerals, and description thereof may be omitted.

High purity oxygen is supplied from a lance 23 of the converter 22 to reduce the molten steel 24. The exhaust gas generated at that time is recovered from the exhaust gas recovery device 25. The configuration of the other equipment shown in FIG. 2 is the same as that shown in FIG. 1, and its operation and effect are the same as those shown in the description of FIG.

FIG. 3 is a schematic diagram showing a steel refining facility using a smelting reduction furnace which is an example of an embodiment of the present invention. In the smelting reduction furnace 26, iron ore is charged from an iron ore charging facility 27 and coal is charged from a coal charging facility 28. Then, high-purity oxygen is blown from the lance 23 to perform smelting reduction of the iron ore. The generated pig iron is taken out from the tap hole 4.

The construction of the other equipment shown in FIG. 2 is the same as that shown in FIG. 1, and its operation and effect are the same as those shown in the description of FIG. I do.

[0042]

Embodiments of the present invention using cupolas will be described below. The equipment used is as shown in FIG. The operating conditions of Cupola were as follows. 1) Capacity: 2,000 [t / d] 2) Tapping capacity: 83 [t · H] (average) 3) Operating hours: 24 days / day [H / d] 4) Basic unit of raw materials, etc. (THM = 1 ton of hot metal) Per) coke: 540 kg, transfer: 120 kg, oxygen: 293 Nm ³ , steam: 171 kg 5) Raw material properties Iron scrap: bulk specific gravity 0.65 coke: coke for blast furnace, particle size 25-60 [mm] Cupola 1 scraps from the furnace top 85T / H and coke 30
T / H etc. were installed. Oxygen is 10 from the tuyere below the cupola
The blowing operation was performed at a flow rate of 000 Nm ³ / H. The properties of the obtained product are shown below. 1) Hot metal: Fe 94.4%, C 4.5%, Si 0.5%, Mn 0.3
%, P 0.1%, S 0.07 % Temperature 1500 [℃] 2) slag: CaO / SiO ₂ 1.25 [-], temperature of 1550 [℃] 3) _{gas: CO 76.7Vol%, CO 2 0.3Vol} %, H 2 22.5 V
ol%, N 2 0.6Vol% lower calorific value 2890 [kcal / Nm ^3], a temperature of 150 [℃] 87000Nm 3 / ^H gas cupola of is dust in dust remover 5, a high pressure is compressed by the gas compressor 6 It was introduced into the combustor 7. 153000Nm ³ / H air is compressed by air compressor 8,
The heat exchanger 1 is partially exhausted by the exhaust gas from the oxygen production device 13.
After heating at 0, the mixture was heated to 900 ° C. by the heating burner 11 and introduced into the oxygen production apparatus 7.

The remaining air was introduced into the high-pressure combustor 7 together with the exhaust gas from the oxygen producing device 13. The gas turbine 6 is driven by the combustion gas generated in the high-pressure combustor 7, but is driven by external electric power at the time of starting. The oxygen produced by the oxygen producing apparatus 13 was 10,000 Nm ³ / H, and the purity was 99.9%. Since the temperature of this oxygen was 600 ° C., it was used as a heat source for heating cupola oxygen after being compressed by the heat exchanger 14 and the oxygen compressor 15.

The oxygen compressed by the oxygen compressor 15 is stored in the gas holder 13 and supplied to the cupola 1, but it can be used for other purposes than the cupola. Further, since the combustion gas generated in the high-pressure combustor 7 is about 600 ° C. at the gas turbine outlet, the combustion gas is recovered by the steam generator 18 as a heat source, and power generation using the steam turbine and the condenser is also possible. . As a result of the above operations, the unit production of oxygen was about 0.2 kWh / Nm ³ , which reduced the cost of hot metal by 10% compared to the conventional method.

[0045]

As described above, according to the present invention,
Since oxygen for refining and electric power can be co-produced, iron can be economically refined. Conventionally, oxygen produced by the existing air separation technology (cryogenic separation method) is used, and no attempt has been made to produce supplied oxygen at low cost. And installation of an on-site PSA, which was expensive. On the other hand, the equipment of the present invention is very compact in terms of equipment scale and extremely economical.

[0046]

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an iron refining facility using cupolas, which is an example of an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a steel refining facility using a converter, which is an example of an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a steel refining facility using a smelting reduction furnace as an example of an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a structure of a metal oxide film.

[Explanation of Signs] 1 ... cupola, 2 ... loading inlet, 3 ... tuyere, 4 ... taphole, 5
... dust collector, 6 ... gas compressor, 7 ... high pressure combustor, 8 ... air compressor, 9 ... gas turbine, 10 ... heat exchange, 11 ... heating burner, 13 ... oxygen production equipment, 14 ... heat exchanger, 15 ...
Oxygen compressor, 16 ... High pressure oxygen holder, 17 ... Generator, 1
8 ... oxygen generator, 19 ... steam turbine, 20 ... generator,
21: condenser, 22: converter, 23: lance, 24: molten steel, 25: exhaust gas recovery device, 26: smelting reduction furnace, 27 ...
Iron ore charging equipment, 28 ... Coal charging equipment

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C21B 11/02 C21B 11/02 C21C 5/40 C21C 5/40 Z F01K 23/10 F01K 23/10 T F02C 3/22 F02C 3/22 6/00 6/00 A 6/18 6/18 A (72) Inventor Takayoshi Anyashiki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Jun Ishii 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Tatsuro Ariyama 1-2-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. 3G081 BA02 BA11 BB00 BC07 BD00 DA22 4D006 GA41 JA03C KA02 KB30 MA31 MC03 PA02 PB17 PC71 4K002 BA01 4K012 CB01 CB04 CB07 4K056 AA01 AA02 AA05 BA01 BA06 BB01 CA02 DA02 DA17 DA22 DA32 DA36 DA38 DA39 DB39

Claims (10)

[Claims] 1. A method for refining a metal by blowing oxygen gas, comprising: (a) using, as the oxygen gas, an oxygen gas produced by an oxygen separation device having a gas separation film made of a metal oxide film; (b) exhaust gas generated during refining is collected, compressed by a gas compressor, and then used as fuel for a combustor; (c) driving a gas turbine with the combustion gas exiting the combustor; (d) A metal refining method comprising: driving at least the gas compressor, an air compressor for compressing air supplied to the oxygen separator and the combustor, and a generator by the gas turbine. 2. The metal refining method according to claim 1, wherein the air supplied to the oxygen separation device is heated by the heat of the remaining exhaust gas of the oxygen separated by the oxygen separation device. A metal refining method. 3. The metal refining method according to claim 2, wherein the remaining exhaust gas after heating the air is supplied to the combustor together with the air. 4. One of claims 1 to 3
The metal refining method according to claim 1, wherein oxygen immediately before burning the carbon material is heated by oxygen immediately after being separated by the oxygen separation device. 5. The method according to claim 1, wherein
The method for refining a metal according to claim 1, wherein steam is generated by a combustion gas after driving the gas turbine, and power is generated by the steam. 6. An equipment for injecting oxygen gas and refining metal, comprising: an exhaust gas compressor for pressurizing exhaust gas generated from a furnace for refining metal; an air compressor for pressurizing air;
A combustor configured to mix and burn the pressurized exhaust gas and the pressurized air, a gas turbine driven by combustion gas generated by combustion of the exhaust gas in the combustor, and the pressurized air A heating device that heats the air, an oxygen separation device that separates oxygen from the air heated by the heating device through a gas separation film made of a metal oxide film,
An oxygen compressor for pressurizing the separated oxygen, and a generator, the exhaust gas compressor, the air compressor, the oxygen compressor and the generator are driven by the gas turbine, The metal refining device, wherein the pressurized oxygen is blown to burn a carbon material. 7. The metal refining device according to claim 6, wherein heat exchange of oxygen separated by the oxygen separation device with remaining exhaust gas and air supplied to the oxygen separation device is performed. A metal refining device comprising a heat exchanger. 8. The metal refining apparatus according to claim 7, wherein the exhaust gas exiting the heat exchanger is supplied to the combustor together with air. Refining equipment. 9. The method according to claim 6, wherein the first and second parts are different from each other.
The metal refining device according to the item, comprising a heat exchanger that performs heat exchange between oxygen immediately after being separated by the oxygen separation device and oxygen immediately before burning the carbon material. Characteristic metal refining equipment. 10. The metal refining apparatus according to claim 6, wherein the power generation system is driven by using heat of the combustion gas after driving the gas turbine as a heat source. A metal smelting apparatus characterized by having.