JP2007009069A - Method and system for reforming byproduct gas in steelmaking plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the quantity of industrially useful carbon monoxide through reducing carbon dioxide emissions in steelmaking plants and also reforming carbon dioxide in the byproduct gas in the steelmaking plants. <P>SOLUTION: In a steelmaking furnace 1, carbon dioxide-rich byproduct gas 54 is generated in the process of manufacturing crude steel 56 from iron feedstocks 51 including iron ore and scrap and then fed via a gas holder 7 and a compressor 2 to a gas reforming furnace 4 where carbon-containing solid compounds 52 such as coal and wastes are gasified. The carbon dioxide in the thus fed byproduct gas is reduced into carbon monoxide by char generated in the gas reforming furnace 4. Thereby, the calorific value of the byproduct gas is increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and system for reforming by-product gas in an iron making process.

  In the iron making process, iron raw materials such as iron ore and scrap iron are put into iron making furnaces such as blast furnaces and converters together with coal and organic waste. Organic waste is a substance containing carbon or hydrogen, such as waste tire chips and waste plastics. In the furnace, oxygen or air is supplied to burn part of carbon and hydrogen of the input coal and organic waste, thereby melting and reducing the iron raw material to produce iron.

  In an iron making furnace, hydrocarbons are partially burned to generate a gas containing carbon monoxide, hydrogen, and hydrocarbons (tar, etc.). This gas is oxidized by reducing iron oxide contained in the iron raw material, and becomes carbon dioxide or water vapor. Note that not all carbon monoxide, hydrogen, and hydrocarbon gas are converted into carbon dioxide and water vapor, and some of them remain and are discharged from the steelmaking furnace as by-product gases. The by-product gas includes a combustible gas, but the calorific value may be low. Therefore, various studies for effectively using the gas have been carried out.

  In Patent Document 1, hydrogen is collected from a by-product gas generated from a coke oven, a blast furnace, a converter, etc. in a steelworks, and a high calorific value gas and a low calorific value gas are mixed. The method of using it for various devices is devised.

JP 2004-224926 A

  As in Patent Document 1, in a steel mill having a plurality of furnaces such as a coke oven, a blast furnace, and a converter, by-product gases having various compositions and calorific values are discharged. Therefore, it is possible to prepare gas and use it as an appropriate calorific value, which is effective. However, for example, in a small steelworks having only a converter, only one kind of by-product gas is discharged. When the by-product gas has a low calorific value and the usage destination is limited, the non-combustible gas such as nitrogen and carbon dioxide is separated from the by-product gas to improve the calorific value of the by-product gas, About the separated nonflammable gas, the method of utilizing for a certain use separately can be considered.

  This method is considered to be effective when there is a device using nitrogen or carbon dioxide in the steelworks or when there is a sales destination. However, it does not hold if there is no usage destination. From the viewpoint of measures against global environmental problems to reduce carbon dioxide emissions, it is desirable that carbon dioxide be used in steelworks while avoiding atmospheric release.

  An object of the present invention is to effectively use carbon dioxide, which is a non-flammable gas contained in an iron-produced by-product gas, in a steelworks, and is also useful as a chemical material with a combustible gas by reforming carbon dioxide. An object of the present invention is to provide a method and system for reforming an iron-produced by-product gas capable of obtaining carbon monoxide.

  The iron production byproduct gas reforming method and system according to the present invention basically includes an iron making furnace (for example, a blast furnace or a converter) and a gas reforming furnace, and includes an iron making byproduct containing carbon dioxide generated from the iron making furnace. Gas is supplied to the gas reforming furnace.

  The gas reforming furnace is a furnace for generating reformed gas that is separate from the iron making furnace, and reacts coal and a combustible waste and / or a compound containing carbon, which is a by-product, with oxygen. The reformed gas (combustible gas) such as carbon monoxide and hydrogen is generated by partial combustion. During partial combustion in a gas reforming furnace, char containing a large amount of carbon (solid compound containing carbon) is generated in addition to the reformed gas.

As a result, a portion of the carbon dioxide contained in the iron by-product gas sent into the gas reforming furnace reacts with C + CO ₂ → 2CO and is reduced to carbon monoxide by the char obtained in the gas reforming furnace. Thereby, the calorific value of the by-product gas is improved. The by-product gas sent from the iron making furnace to the gas reforming furnace is preferably sent at a pressure higher than the operating pressure of the gas reforming furnace.

  In addition, the following configuration is proposed.

  When the by-product gas generated in the iron making furnace is supplied near the gas outlet of the gas reforming furnace, it cools the high-temperature gas generated in the gas reforming furnace, thereby preventing ash from adhering to the wall of the gas reforming furnace. Can be suppressed.

  Furthermore, after reducing the iron by-product gas (especially carbon dioxide) in the gas reforming furnace to increase the amount of carbon monoxide (reformed gas), the dust contained in the reformed gas discharged from the gas reforming furnace A structure that removes sulfur and other components is proposed.

  In addition, the carbon dioxide contained in the reformed gas discharged from the gas reforming furnace is removed as described above, and the partial pressure of useful components (carbon monoxide, hydrogen, etc.) of the reformed gas is further increased. Therefore, we propose a configuration to be used as fuel and chemical raw materials.

  Further, a configuration is proposed in which hydrogen and carbon monoxide are separated from the reformed by-product gas in which the amount of carbon monoxide is increased as described above, and hydrogen is used as a fuel and carbon monoxide is used as a chemical raw material.

  According to the present invention, it is possible to reduce atmospheric emissions of carbon dioxide, a by-product gas generated in an iron (steel) furnace, and to reform the by-product gas to increase the amount of carbon monoxide. Can be expanded. In addition, the gas reforming furnace can be operated stably.

In the iron making process, raw steel such as iron ore and scrap iron is reduced by partial combustion of a substance containing carbon or hydrogen such as coal to obtain crude steel. Usually, combustible gases such as carbon monoxide (CO), hydrogen (H ₂ ), and hydrocarbon gas are contained in the exhaust gas (by-product gas) of an iron furnace, but the calorific value is low and the usage destination is restricted. There is a case. Therefore, in the present invention, a by-product gas reforming furnace is provided, and carbon dioxide (CO ₂ ) in the by-product gas is reduced by an activated char obtained by partial combustion of coal in the reforming furnace to be oxidized. Reforming to carbon to improve the calorific value.

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following examples.
Example 1
FIG. 1 shows the structure of a method and system for reforming a by-product gas by an embodiment of the present invention.

  Overall, the iron making furnace 1, the gas holder 7, the compressor 2, the coal hopper 3, and the gas reforming furnace 4 are main components. As the iron making furnace 1, for example, a blast furnace or a converter is used. The iron making furnace 1 is supplied with an iron raw material (for example, iron ore or scrap) 51, coal 52, air or oxygen-enriched air 53 to produce crude steel 56. In addition, you may add carbon-containing compounds, such as a waste tire and a waste plastic, as a fuel of an iron furnace. In the iron making process, a by-product gas 54 containing a large amount of carbon dioxide and also containing carbon monoxide, hydrogen, and hydrocarbon gas is generated and discharged.

  After the by-product gas 54 is temporarily stored in the gas holder 7, the pressure is increased to a pressure higher than that of the gas reforming furnace 4 by the compressor 2, and then supplied to the gas reforming furnace 4 through the by-product gas nozzle 5. On the other hand, the gas reforming furnace 4 is supplied with oxygen 57 from the coal hopper 3 along with the coal 52 ′ via the coal nozzle 6.

  The gas holder 7 temporarily stores the by-product gas 54 from the iron making furnace 1 so that the composition, flow rate, pressure, and the like can be taken out constantly.

  The structure of the gas reforming furnace is not particularly limited. The basic structure itself may be an existing coal gasifier, and detailed description thereof is omitted. Basically, the reforming furnace includes a coal nozzle 6 for coal input and a by-product gas nozzle 5, and has a high-temperature furnace that partially burns coal to generate a gas rich in carbon monoxide and hydrogen. There is an outlet for the product gas of the reforming furnace, and a slag discharge hole (not shown) for melting the ash content in the coal and discharging it as slag at the bottom.

  Coal is supplied into the reforming furnace through the coal nozzle 6 together with oxygen. In the reforming furnace, coal is partially burned by oxygen to cause a gasification reaction, generating a gas rich in carbon monoxide and hydrogen. Some of the carbon in the coal remains as a solid. This is called char.

In the gas reforming furnace 4, the coal 52 ′ is partially burned by the oxygen 57, becomes a high temperature of about 1600 ° C., and a gas containing carbon monoxide, hydrogen, methane, etc. and a char containing a large amount of carbon are generated. The high temperature char contacts the byproduct gas 54 supplied from the byproduct gas nozzle 5. Here, the carbon dioxide in the by-product gas 54 is reduced by char and converted (reformed) into carbon monoxide, and further, the carbon content in the char is oxidized and converted into carbon monoxide. This is represented by the following chemical formula:
[Chemical 2]
CO ₂ + C → 2CO
aC + bO ₂ → cCO + dCO ₂
Through the above reaction, the reformed gas 55 containing a large amount of carbon monoxide is taken out from the gasification reforming furnace 4. Since the amount of carbon monoxide in the reformed gas is increased, the calorific value is improved. By-product gas is introduced into the reforming furnace outlet to suppress ash adhesion by cooling the ash and sealing the wall.

  FIG. 2 shows the carbon dioxide concentration contained in the coal gas (a gas discharged from the gas reforming furnace) of a when the by-product gas reforming method of the present invention is performed, and the coal gas of Comparative Example b. It is the figure which compared the dioxide concentration. FIG. 3 is a graph comparing the carbon monoxide concentrations contained in the reformed gases of a and comparative example b when the by-product gas reforming method of the present invention is performed. The comparative example b is an example in which the iron-produced by-product gas is joined (mixed) with the coal gas downstream of the outlet of the gas reforming furnace without being introduced into the gas reforming furnace 4. The horizontal axis of FIG. 2 shows the ratio of coal gas to the iron production byproduct gas of Comparative Examples a and b, and the vertical axis shows the concentration of discharged carbon dioxide. The horizontal axis of FIG. 3 is the same as that of FIG. 2, and the vertical axis indicates the carbon monoxide concentration.

  Since the steelmaking by-product gas contains a large amount of carbon dioxide, simply mixing the by-product gas and the coal gas as in Comparative Example b results in the carbon dioxide in the entire gas as shown in FIG. To increase. In the case of the present invention, by applying the reforming method, a part of carbon dioxide can be reduced by char generated from coal, so the concentration of carbon dioxide in the entire exhausted gas decreases. , Has the effect of reducing carbon dioxide emissions.

  In addition, according to the case a of the present invention, as shown in FIG. 3, the carbon dioxide in the iron by-product gas is reduced and converted to carbon monoxide. The carbon monoxide concentration increases. As a result, the reformed gas of the present invention increases the calorific value of the entire gas, and thus can be used for expanding the use of gas.

  In addition, since a part of the carbon dioxide in the iron by-product gas is reduced to carbon monoxide in the reforming furnace, the concentration of monoxide in the entire gas is as shown in FIG. It tends to decrease as the amount of input increases. However, the carbon monoxide concentration only needs to be able to maintain the required concentration. If the required concentration is satisfied, there is no problem even if the steelmaking byproduct gas is introduced into the gas reforming furnace. For example, when a concentration of 65% is desired in a certain process, the present invention requires 60 vol% of coal gas, whereas in comparative example b, 70 vol% of coal gas is required. Therefore, according to the present invention, the amount of coal used can be reduced with respect to the required carbon monoxide concentration, and there is a merit of raw material reduction.

  FIG. 4 shows a second embodiment of the present invention. The basic configuration is the same as that of the first embodiment, but in this embodiment, further components are added. The contents of the first embodiment described above are the same in this embodiment. A difference is that a dedusting device 8 and a desulfurization device 9 are provided downstream of the gas reforming furnace 4 as a reformed gas purification device.

  The reformed gas 55 contains a powdery solid such as soot dust or a sulfur content contained in the coal 52 or the like. The reformed gas 55 is dedusted by a dedusting device 8 such as a cyclone or a filter, and a sulfur content is further removed by a desulfurization device 9 to obtain a by-product gas 58 after reforming. As a result, clean gas can be obtained and used as fuel or the like.

  FIG. 5 is a block diagram showing a third embodiment of the present invention. The basic configuration of this embodiment is the same as that of the first embodiment, but in this embodiment, further components are added. The contents of the first embodiment described above are the same in this embodiment. The difference is that a dust removing device 8 and a carbon dioxide separator 12 are provided downstream of the gas reforming furnace 4.

  Powder solids such as soot dust contained in the reformed gas 55 are removed by the dust removing device 8, and the gas after the dust removal is introduced into the carbon dioxide separator 12 to separate the carbon dioxide 64, which is used as dry ice or the like. can do. Since the calorific value of the gas 65 after removing carbon dioxide is improved, it is suitable for use as a fuel.

  FIG. 6 is a block diagram showing a fourth embodiment of the present invention. The basic configuration of this embodiment is the same as that of the first embodiment, but in this embodiment, further components are added. The contents of the first embodiment described above are the same in this embodiment. The difference is that a dust removing device 8 and a hydrogen separation device 10 are provided downstream of the gas reforming furnace 4.

  Powder solids such as dust contained in the reformed gas 55 are dedusted by the dedusting device 8, and the degassed gas is introduced into the hydrogen separation device 10 to separate the hydrogen gas 59 and used as hydrogen fuel or the like. be able to. Since the reformed gas 60 after the removal of hydrogen gas contains combustible carbon monoxide, it can be used as a fuel or the like. For the hydrogen separator 10, PSA (pressure swing adsorption) or the like can be used.

  FIG. 7 is a block diagram showing a fifth embodiment of the present invention. The basic configuration of this embodiment is the same as that of the first embodiment, but in this embodiment, further components are added. The contents of the first embodiment described above are the same in this embodiment. The difference is that a dust removing device 8 and a carbon monoxide separation device 11 are provided downstream of the gas reforming furnace 4.

  Powder solids such as dust contained in the reformed gas 55 are dedusted by the dedusting device 8, and the dedusted gas is introduced into the carbon monoxide separation device 11 to separate the carbon monoxide 61. Carbon monoxide can be used as a chemical raw material. Since the gas 62 after the removal of carbon monoxide contains hydrogen gas, it can be used as a fuel or the like. For the carbon monoxide separator 11, PSA or the like can be used.

  FIG. 8 is a block diagram showing a sixth embodiment of the present invention. The basic configuration of this embodiment is the same as that of the first embodiment, but in this embodiment, further components are added. The contents of the first embodiment described above are the same in this embodiment. The difference is that a dust removing device 8, a hydrogen separation device 10, and a carbon monoxide separation device 11 are provided downstream of the gas reforming furnace 4.

  Powder solids such as dust contained in the reformed gas 55 are dedusted by the dedusting device 8, and the degassed gas is introduced into the hydrogen separation device 10 to separate the hydrogen gas 59 to be used as hydrogen fuel or the like. can do. The gas 60 after the hydrogen removal is further introduced into the carbon monoxide separator 11 to separate the carbon monoxide 61 and can be used as a chemical raw material (for example, acetic acid).

  In any of the above-described embodiments, it is possible to reduce carbon dioxide emissions at an ironworks and to reform carbon dioxide contained in a by-product gas, thereby increasing the amount of industrially useful carbon monoxide. it can. In the above embodiment, only the coal is gasified in the gas reforming furnace 4, but other solid compounds containing carbon such as waste tires and waste plastics may be gasified.

The figure which showed the structure of the iron manufacture byproduct gas reforming method and system by 1st Example of this invention. The figure which showed the comparison of the carbon dioxide density | concentration contained in coal gas of the case a and the comparative example b when implementing the modification | reformation method of the iron by-product gas of this invention. The figure which showed the comparison of the carbon monoxide density | concentration contained in coal gas of the case where the reforming method of the iron by-product gas of this invention is implemented and the comparative example b. The figure which showed the structure of the modification | reformation method and system of an iron manufacture byproduct gas concerning 2nd Example of this invention. The figure which showed the structure of the modification | reformation method and system of an iron manufacture byproduct gas based on 3rd Example of this invention. The figure which showed the structure of the modification | reformation method and system of an iron manufacture byproduct gas which concerns on 4th Example of this invention. The figure which showed the structure of the modification | reformation method and system of an iron manufacture byproduct gas concerning 5th Example of this invention. The figure which showed the structure of the modification | reformation method and system of an iron manufacture byproduct gas which concerns on 6th Example of this invention.

Explanation of symbols

1: Iron making furnace, 2: Compressor, 3: Coal hopper, 4: Gas reforming furnace, 5: By-product gas nozzle, 6: Coal nozzle, 7: Gas holder, 8: Dedusting device, 9: Desulfurization device, 10: Hydrogen separator, 11: carbon monoxide separator, 12: carbon dioxide remover, 51: iron raw material, 52: coal, 53: air or oxygen-enriched air, 54: by-product gas, 55: reformed gas, 56 : Crude steel, 57: Oxygen, 58: Reformed gas after purification, 59: Hydrogen, 60: Reformed gas after removal of hydrogen, 61: Reformed gas after removal of carbon monoxide, 62: Reformed gas after removal of carbon monoxide, 63: Gas after removing hydrogen and carbon monoxide, 64: carbon dioxide, 65: gas after removing carbon dioxide.

Claims (10)

Iron making furnaces such as blast furnaces and converters,
A gas reforming furnace that reacts at least one of coal, combustible waste, and a carbon-containing compound that is a by-product thereof with oxygen to generate a reformed gas such as carbon monoxide by partial combustion. ,
A steelmaking by-product gas containing carbon dioxide generated from the iron making furnace is supplied to the gas reforming furnace, and a part of the carbon dioxide is reduced to carbon monoxide by char obtained in the gas reforming furnace. A method for reforming a steel by-product gas.   The method for reforming a steelmaking byproduct gas according to claim 1, wherein the steelmaking byproduct gas generated from the steelmaking furnace is supplied to the gas reforming furnace through a gas holder and a compressor.   2. The high-temperature gas generated in the gas reforming furnace according to claim 1, wherein the iron-produced by-product gas supplied to the gas reforming furnace is reformed into carbon monoxide in the gas reforming furnace while carbon dioxide therein is reformed. A method for reforming a steelmaking by-product gas, characterized in that the hot gas is cooled by direct contact with the steel. An iron making furnace that discharges by-product gas containing carbon dioxide and carbon monoxide during crude steel production;
A gas holder that temporarily stores the iron by-product gas and enables the iron by-product gas to be sent out in a stable state in composition, flow rate, and pressure,
A gas reforming furnace that partially burns at least one of coal, combustible waste, and by-products of combustible waste with oxygen or air to generate reformed gas such as carbon monoxide or char;
An iron production by-product gas delivery line of the iron making furnace is connected to the gas reforming furnace via the gas holder, and a gas supply line for supplying the iron production by-product gas to the gas reforming furnace is formed. By-product gas reforming system characterized by this.   5. The iron production by-product gas reforming system according to claim 4, wherein a compressor for increasing gas pressure is provided in the iron production by-product gas supply line between the iron making furnace and the gas reforming furnace.   5. The iron production by-product gas modification according to claim 4, wherein a gas purification device is provided that dedusts the reformed gas sent from the gas reforming furnace and removes sulfur content such as hydrogen sulfide at a subsequent stage of the gas reforming furnace. Quality system.   5. The apparatus according to claim 4, wherein a device for separating and removing carbon dioxide contained in the reformed gas sent from the gas reforming furnace is provided at a subsequent stage of the gas reforming furnace, and the removed reformed gas is used as fuel or a chemical raw material. Steelmaking by-product gas reforming system.   5. The apparatus according to claim 4, wherein a device for separating and recovering hydrogen contained in the reformed gas delivered from the gas reforming furnace is provided at a subsequent stage of the gas reforming furnace, and the hydrogen and the hydrogen-removed gas are respectively used as fuel. Steelmaking by-product gas reforming system.   In Claim 4, the apparatus which isolate | separates and collects carbon monoxide contained in the reformed gas sent out from the gas reforming furnace is provided at the rear stage of the gas reforming furnace, and the carbon monoxide is used as a chemical raw material. The gas after removing the carbon oxide is a reforming system for steelmaking by-product gas used as fuel.   5. The apparatus according to claim 4, wherein a device for separating and recovering hydrogen and carbon monoxide contained in the reformed gas sent from the gas reforming furnace is provided at a subsequent stage of the gas reforming furnace, and hydrogen is used as fuel for carbon monoxide. Steelmaking by-product gas reforming system that uses as a chemical raw material.

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