JP2011202271A - Method for utilizing gas containing carbon oxides - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for utilizing gas containing carbon oxides by which the gas containing carbon oxides (carbon-dioxide or mixed gas containing carbon-dioxide and carbon-monoxide) in blast furnace gas, converter gas, etc.SOLUTION: The method includes the steps of: recovering the gas containing the carbon-oxides (the carbon-dioxide or the mixed gas containing the carbon-dioxide and the carbon monoxide) in the blast furnace, the converter, etc.; separating the carbon-oxides (the carbon-dioxide or the mixed gas containing the carbon-dioxide and the carbon-monoxide) from the recovered gas containing the carbon-oxides; converting the carbon-dioxide in the separated carbon-oxides into the carbon-monoxide by reducing with hydrocarbon-series reducing agent; and utilizing the thus obtained carbon-monoxide (the carbon-monoxide obtained by reducing the carbon-dioxide separated from the gas containing the carbon-oxides, and the carbon-monoxide obtained by separating the gas containing the carbon-oxides) in the blast furnace.

Description

  The present invention relates to a method of using a carbon oxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide).

  Global warming due to an increase in carbon dioxide has been taken up as an international issue, and reducing its emissions has become a global issue. Various technological developments (for example, Patent Documents 1 to 3 and Non-Patent Document 1) have been attempted in order to separate and recover carbon dioxide. However, no very effective means has been proposed for using the recovered carbon dioxide.

  For example, a so-called CCS (Carbon Dioxide Capture and Storage) technique for filling the collected carbon dioxide into the ground has been actively developed mainly in Europe, the United States, Japan and the like. However, this method is not only difficult to obtain an agreement on safety after being buried in the ground, especially in Japan, which is an earthquake-prone country, but according to a calculation by the Institute for Global Environmental Research (RITE) It is said that the value obtained by dividing the amount of carbon dioxide that can be buried in the vicinity of Japan including emissions by the amount of emissions, that is, the lifetime is only about 50 to 100 years. In such a situation, it must be said that building a recycling-oriented society is uncertain.

  By the way, according to statistics, the amount of carbon dioxide emissions in Japan is about 30% due to power generation, 10% due to steel production, and the transportation sector and civilian sector account for a large percentage. Yes.

  For example, in a power plant, carbon dioxide is emitted because chemical energy of coal, oil, and natural gas is converted into electric energy while generating carbon dioxide by complete oxidation of these fossil fuels. Therefore, as long as fossil fuels are used, a reasonable amount of carbon dioxide is inevitably generated. However, these are expected to decrease gradually due to the use of so-called soft energy such as wind power generation and tidal power generation, biomass power generation, and nuclear power generation.

  On the other hand, the generation of carbon dioxide in steel production is accompanied by the reduction of iron ore, which is iron oxide, with carbon (coke) and the removal of the carbon content. This can be said to be the same in the operation in the blast furnace and in the operation in the converter. For this reason, it can be said that the generation of carbon dioxide is inevitable in steel production.

  In the steel industry, it has been proposed to circulate a part of blast furnace gas to the blast furnace (Patent Document 4). That is, Patent Document 4 discloses a technique for burning a blast furnace gas, a mixture of a blast furnace gas and a coke oven gas, or a gas obtained by removing carbon dioxide from a blast furnace gas and introducing the gas into a blast furnace shaft portion. When the temperature of the blast furnace decreases, troubles such as corrosion of the furnace wall due to condensation of moisture occur. Therefore, in Patent Document 4, when the furnace top temperature becomes 110 ° C. or lower, the blast furnace gas or the mixture with the coke oven gas or the blast furnace gas from which carbon dioxide gas is removed is introduced into the blast furnace shaft portion. It is intended to suppress the problem.

However, the blast furnace gas is mainly composed of nitrogen, which is an inert gas, and occupies 50 to 60% by volume. Carbon dioxide and carbon monoxide are each about 20 to 25%. Patent Document 4 shows a method of removing carbon dioxide and returning it to the blast furnace shaft. However, if nitrogen is not removed more than carbon dioxide, the effect is small, and only the nitrogen that is circulated and introduced is used. The nitrogen content of the blast furnace gas increases and the amount of heat of the blast furnace gas decreases. Originally, the blast furnace gas has a low calorific value of 1000 kcal / m ³ or less, and is generally used as a fuel gas by mixing with other high calorific gas. Decreasing the calorific value of the blast furnace gas has a negative effect such as the need to increase the mixing ratio of the high calorific gas, resulting in an increase in carbon dioxide emission.

JP 11-137960 A JP 2007-44677 A JP 2009-214101 A JP 2008-214735 A

Onoda, Journal of the Japan Institute of Energy, 88 (4) 278-283 (2009)

  As described above, the production of carbon dioxide is inevitable in steel production. At the same time, carbon monoxide is generated, and the carbon monoxide is changed to carbon dioxide.

  For this reason, it becomes an important subject how to effectively reuse the generated mixed gas containing carbon dioxide and carbon monoxide to reduce the actual carbon dioxide generation amount.

  The present invention has been made in view of the circumstances as described above, and carbon oxide that can efficiently use carbon oxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide). The object is to provide a method of using the contained gas.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors recovered carbon dioxide generated in the steel industry or other industries, etc., and reduced and reused it as carbon monoxide in a blast furnace. And found that it can achieve substantial carbon dioxide reduction.

  That is, carbon oxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide) such as blast furnace gas and converter gas generated at steelworks is recovered, and carbon oxide ( Carbon dioxide or carbon dioxide and carbon monoxide) is separated, and the carbon dioxide in the separated carbon oxide is reduced by a hydrocarbon-based reducing agent and converted to carbon monoxide, and the carbon monoxide (oxidation) obtained by them is converted The idea was to recycle carbon monoxide obtained by reducing carbon dioxide separated from a carbon-containing gas and / or carbon monoxide obtained by separating carbon dioxide-containing gas in a blast furnace.

  Based on the above idea, the present invention has the following features.

  [1] After carbon dioxide or carbon dioxide and carbon monoxide are separated from carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide, the separated carbon dioxide or carbon dioxide and carbon monoxide are carbonized. A method of using a carbon oxide-containing gas, wherein the carbon monoxide is converted into carbon monoxide and hydrogen by contacting with a hydrogen-based reducing agent, and the obtained carbon monoxide is introduced into a blast furnace.

  [2] The method for using a carbon oxide-containing gas according to the above [1], wherein the carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide is a blast furnace gas by-produced at an ironworks.

  [3] The method for using a carbon oxide-containing gas according to [1], wherein the carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide is a converter gas by-produced at an ironworks. .

  [4] The above-mentioned [1], wherein the method for separating carbon dioxide or carbon dioxide and carbon monoxide from carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide is an adsorption separation method. The utilization method of the carbon oxide containing gas in any one of [3].

  [5] The method for using a carbon oxide-containing gas according to any one of [1] to [4], wherein the hydrocarbon-based reducing agent is a gas containing methane as a main component.

  [6] The method for using a carbon oxide gas-containing gas according to any one of [1] to [4], wherein the hydrocarbon-based reducing agent is a gas mainly composed of liquefied petroleum gas.

  [7] The carbon oxide gas-containing product as described in any one of [1] to [4] above, wherein the hydrocarbon-based reducing agent is a gas and / or a liquid mainly containing methanol and / or dimethyl ether. How to use gas.

  [8] Waste heat from a steel mill as part or all of the heat source when the separated carbon dioxide or the carbon dioxide and carbon monoxide are brought into contact with a hydrocarbon-based reducing agent to be converted into carbon monoxide and hydrogen. The method for using a carbon oxide gas-containing gas according to any one of [1] to [7], wherein:

  The present invention has an effect that carbon dioxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide) can be efficiently reused to substantially suppress carbon dioxide.

It is a figure which shows Example 1 of this invention. It is a figure which shows Example 2 of this invention. It is a figure which shows Example 3 of this invention.

  One embodiment of the present invention is described below. The gas concentration described below is volume%.

  One embodiment of the present invention is a method of using a carbon oxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide) generated in the steel industry or other industries. Carbon dioxide (carbon dioxide or carbon dioxide and carbon monoxide) is separated and recovered from carbon oxide-containing gas generated in industry or other industries, and the carbon dioxide in the carbon oxide is reduced to carbon monoxide, This is a method of using a carbon oxide-containing gas that substantially reduces carbon dioxide by reusing the obtained carbon monoxide in a blast furnace.

  That is, in one embodiment of the present invention, a carbon oxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide) such as blast furnace gas and converter gas generated in the iron making process is recovered and recovered. The gas having a carbon oxide concentration (total concentration of carbon dioxide and carbon monoxide) of 80% or more is separated from the carbon oxide-containing gas, and the separated gas (total concentration of carbon dioxide and carbon monoxide is 80%). In a method of reducing carbon dioxide in the gas) to a gas mainly composed of carbon monoxide and hydrogen, and reusing the obtained carbon monoxide and hydrogen in a blast furnace. is there.

  In addition, when the concentration of carbon oxide in the recovered carbon oxide-containing gas is less than 80%, in the subsequent reduction process, the reactor becomes large, and the influence of sensible heat of other components increases, which is not economical. .

  In one embodiment of the present invention, the carbon oxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide) as a raw material is not necessarily limited to a gas generated in the iron making process, but a reducing agent is used later. Since there is a step of reducing with (hydrocarbon reducing agent), the oxygen concentration is desirably 5% or less. This is because if the oxygen concentration is higher than 5%, more reducing agent is consumed by combustion.

  There are various methods for separating and recovering carbon oxide (carbon dioxide or carbon dioxide and carbon monoxide) from the raw material carbon oxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide). Any known method can be used. That is, after separating and collecting carbon dioxide, separating and collecting carbon monoxide, or conversely, separating and collecting carbon monoxide and then separating and collecting carbon dioxide, and further, carbon dioxide. And carbon monoxide are simultaneously separated and recovered.

  Here, as a method for separating and recovering carbon dioxide, for example, a method in which it is adsorbed on activated carbon or zeolite and separated and recovered by heating or reduced pressure (adsorption separation method), a method in which it is liquefied or solidified by pressurization or cooling, caustic soda , Absorbed into a basic aqueous solution such as amine, and separated and recovered by heating or reduced pressure, separated and recovered by a carbon dioxide separation membrane, absorbed by a solid carbon dioxide absorbent such as barium titanate and separated by heating or reduced pressure Any known method such as a recovery method can be employed. Among them, it is particularly preferable to use an adsorption separation method that has little influence on the post-process and is technically established.

  In addition, as a method for separating and recovering carbon monoxide, for example, a method in which carbon monoxide is adsorbed on a carbon monoxide adsorbent such as copper / activated carbon, copper / alumina, copper / zeolite, and separated and recovered by heating or reduced pressure (adsorption separation method Any known method such as a method of absorbing in a carbon monoxide absorbing solution containing copper as a main component and separating and recovering by heating or decompressing can be employed. Among them, it is particularly preferable to use an adsorption separation method that has little influence on the post-process and is technically established.

  Furthermore, the method for separating and collecting carbon dioxide and the method for separating and collecting carbon monoxide may be performed simultaneously or in combination to separate carbon dioxide and carbon monoxide simultaneously.

  Next, as a method for obtaining carbon monoxide by reducing carbon dioxide in carbon oxide separated and recovered as described above, a known method can be used. For example, dry reforming using methane as a reducing agent such as the following formula (1) can be mentioned.

CO ₂ + CH ₄ → 2CO + 2H ₂ (1)
In the dry reforming method using methane as a reducing agent, the reaction proceeds at 700 to 900 ° C. when a catalyst is used, but the reaction proceeds thermally at a high temperature exceeding 1000 ° C. When gas is blown into the blast furnace, the higher the temperature, the more desirable. Either a method using a catalyst or a method in which the reaction proceeds thermally can be adopted, and it is not necessary to cool after the reaction. It is desirable to be able to. In order to carry out such a high-temperature reaction, it is necessary to apply heat from the outside. For example, unused sensible heat such as blast furnace slag and converter slag can be used, and unnecessary carbonation by heating is possible. It is also desirable from the viewpoint of not generating gas.

  In this dry reforming method, the reducing agent to be used need not be limited to methane, hydrocarbons such as liquefied petroleum gas (LPG), alcohols such as methanol and dimethyl ether (DME), and ethers, Aldehydes and ketones can be used.

  Here, the reduction reaction formula of carbon dioxide when LPG is used as the reducing agent is shown in the following formula (2), and the reduction reaction formula of carbon dioxide when DME is used as the reducing agent is shown in the following formula (3). .

3CO ₂ + C ₃ H ₈ → 6CO + 4H ₂ (2)
CO ₂ + (CH ₃ ) ₂ O → 3CO + 3H ₂ (3)
In the above, carbon monoxide (one obtained by separating from the carbon oxide-containing gas) is obtained by separating and collecting carbon oxide from the carbon oxide-containing gas and reducing carbon dioxide in the separated and collected carbon oxide. When obtaining a gas with a concentration of 80% or more of carbon oxide and carbon monoxide obtained by reducing carbon dioxide separated from the carbon oxide-containing gas, carbon dioxide and monoxide separated and recovered separately After carbon is mixed, it may be reduced, or after carbon dioxide is reduced, it may be mixed with carbon monoxide that has been separately separated and recovered. Furthermore, carbon dioxide and carbon monoxide may be separated and recovered simultaneously and reduced.

  In the reaction between these carbon dioxide and the reducing agent, it is preferable to set conditions for setting the conversion rate of carbon dioxide to 50% or more, and particularly preferably 70% or more.

  The reaction between the carbon dioxide and a reducing agent such as methane, LPG, or DME is an endothermic reaction. Therefore, in order to advance these reactions, it is necessary to apply heat from the outside. On the other hand, there may be waste heat that is not used in steelworks and chemical factories. Therefore, in one embodiment of the present invention, these exhaust heats may be used as a part or all of a heat source for advancing the endothermic reaction. Specifically, the sensible heat of blast furnace slag and converter slag, the sensible heat of red hot coke, etc. in an ironworks are mentioned.

  And the position at the time of introducing the gas whose carbon monoxide concentration is 80% or more into the blast furnace may be in the vicinity of the tuyere of the blast furnace, or may be the upper part of the blast furnace.

  As described above, in this embodiment, carbon dioxide-containing gas (carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide) is efficiently reused to substantially suppress carbon dioxide. Can do.

  In the above, hydrogen obtained by reducing carbon dioxide may be used for other purposes without introducing part or all of the hydrogen into the blast furnace.

  Further, in the above, when the carbon oxide-containing gas does not contain carbon monoxide, the above-described separation and recovery of carbon monoxide is not performed. Further, even when the carbon oxide-containing gas contains carbon monoxide, the same applies to the case where carbon monoxide is not separated and recovered due to its low content.

  FIG. 1 shows Example 1 of the present invention (Invention Example 1).

  As Example 1 of the present invention, as shown in FIG. 1, a blast furnace gas (nitrogen: 52%, carbon dioxide: 22%, carbon monoxide: 23%, hydrogen: 3%) generated from the blast furnace 1 is used as a carbon dioxide adsorbent. In an adsorption tower (PSA unit) 2 filled with an adsorbent mixed with carbon monoxide adsorbent, it is adsorbed at an absolute pressure of 200 kPa, desorbed at an absolute pressure of 7 kPa, and the total of carbon dioxide and carbon monoxide A gas with a concentration of 99% was obtained. Then, this mixed gas of carbon dioxide and carbon monoxide is mixed with the same amount of DME (reducing agent) as carbon dioxide, and the reforming reactor 3 is modified at atmospheric pressure and 280 ° C. in the presence of a copper catalyst. As a result of the quality reaction, 90% of the carbon dioxide was converted, and the concentration of carbon monoxide in the carbon oxide produced by the reforming reaction was 95%. The concentrations of carbon monoxide and hydrogen in the total product were 49% and 47%, respectively. This was directly introduced into the tuyere of the blast furnace.

  Thereby, in this invention, it was confirmed that carbon oxide containing gas (blast furnace gas etc.) can be reused efficiently and carbon dioxide can be suppressed substantially.

  FIG. 2 shows Example 2 (Example 2) of the present invention.

  As Example 2 of the present invention, as shown in FIG. 2, the blast furnace gas (nitrogen: 52%, carbon dioxide: 22%, carbon monoxide: 23%, hydrogen: 3%) generated from the blast furnace 1 is maintained at 30 ° C. The obtained MEA (monoethanolamine) aqueous solution was circulated through the absorption tower 4 to absorb carbon dioxide. The aqueous MEA solution in which carbon dioxide was absorbed was heated to 100 ° C. in the recovery tower 5 to release carbon dioxide, and this generated gas was cooled to condense water and collect carbon dioxide. The purity of carbon dioxide was 99%. This carbon dioxide and natural gas mainly composed of methane were mixed, and a reforming reaction was performed at 900 ° C. in the presence of a nickel-based catalyst. As a result, 98% of the carbon dioxide reacted, and the concentrations of carbon monoxide and hydrogen in the product were both 49%. This was directly introduced into the tuyere of the blast furnace.

  Thereby, in this invention, it was confirmed that carbon oxide containing gas (blast furnace gas etc.) can be reused efficiently and carbon dioxide can be suppressed substantially.

  FIG. 3 shows Example 3 (Example 3) of the present invention.

  As Example 3 of the present invention, as shown in FIG. 3, a high-temperature blast furnace slag 10 was used as the heat source of the reforming reactor 3 in Example 1 of the present invention. Others were carried out in the same manner as Example 1 of the present invention. In the slag sensible heat recovery device 6, the high-temperature blast furnace slag 10 heats the heat medium and further heats the dimethyl ether 9 to become a low-temperature blast furnace slag 11. Dimethyl ether 9 heated by the slag sensible heat recovery device 6 is sent to the reforming reactor 3. On the other hand, the heated heat medium is sent to the reforming reactor 3 through the heat medium circulation line 7 and cooled by supplying reaction heat to an endothermic reaction in which carbon dioxide gas and dimethyl ether are reformed to carbon monoxide and hydrogen. Then, it is sent again to the slag sensible heat recovery device 6 by the heat medium circulation pump 8.

  And when it tested on the same conditions as this invention example 1, 88% of the carbon dioxide converted, and the density | concentration of the carbon monoxide in the carbon oxide produced | generated by the reforming reaction became 93%. The concentrations of carbon monoxide and hydrogen in the total product were 48% and 46%, respectively. This was directly introduced into the tuyere of the blast furnace.

  Thereby, in this invention, it was confirmed that carbon oxide containing gas (blast furnace gas etc.) can be reused efficiently and carbon dioxide can be suppressed substantially.

DESCRIPTION OF SYMBOLS 1 Blast furnace 2 PSA unit 3 Reforming reactor 4 Absorption tower 5 Recovery tower 6 Slag sensible heat recovery device 7 Heat medium circulation line 8 Heat medium circulation pump 9 Dimethyl ether 10 Blast furnace slag (high temperature)
11 Blast furnace slag (low temperature)

Claims (8)

  After separating carbon dioxide or carbon dioxide and carbon monoxide from carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide, the separated carbon dioxide or the carbon dioxide and carbon monoxide are reduced by hydrocarbons. A method of using a carbon oxide-containing gas, wherein the carbon monoxide is converted into carbon monoxide and hydrogen by being brought into contact with an agent, and the obtained carbon monoxide is introduced into a blast furnace.   The method for using a carbon oxide-containing gas according to claim 1, wherein the carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide is a blast furnace gas by-produced at an ironworks.   The method of using a carbon oxide-containing gas according to claim 1, wherein the carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide is a converter gas by-produced at an ironworks.   The method for separating carbon dioxide or carbon dioxide and carbon monoxide from carbon dioxide or a mixed gas containing carbon dioxide and carbon monoxide is an adsorptive separation method. The utilization method of carbon oxide containing gas as described in 1.   The method for using a carbon oxide-containing gas according to any one of claims 1 to 4, wherein the hydrocarbon-based reducing agent is a gas containing methane as a main component.   The method for using a carbon oxide gas-containing gas according to any one of claims 1 to 4, wherein the hydrocarbon-based reducing agent is a gas containing liquefied petroleum gas as a main component.   The method for using a carbon oxide gas-containing gas according to any one of claims 1 to 4, wherein the hydrocarbon-based reducing agent is a gas and / or a liquid mainly composed of methanol and / or dimethyl ether.   Use the waste heat of the steelworks as part or all of the heat source when the separated carbon dioxide or the carbon dioxide and carbon monoxide are brought into contact with a hydrocarbon-based reducing agent to convert to carbon monoxide and hydrogen. A method of using a carbon oxide gas-containing gas according to any one of claims 1 to 7.

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