JP2002212119A - Method for producing methanol from converter gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing methanol from a converter gas, by which the methanol can be produced in a large amount and at a low cost by use of the converter exhaust gas of an iron mill. SOLUTION: This method for producing the methanol with the converter gas comprises adding steam 4 and a natural gas 5 to the gas of converters 1a to 1c, introducing the obtained mixture gas into a continuous casting line 2, utilizing the held heat of a cast piece 2a of the casting line 2 to decompose the mixture gas into CO gas and H2 gas by a steam reforming method, and then reacting the CO gas with the H2 gas in a methanol reaction tower 9 to synthesize the methanol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing methanol inexpensively and in large quantities by using exhaust gas generated from a converter in a steel mill, steam generated from waste heat of the steel mill, and heat retained by a slab in a casting line. The present invention relates to a method for producing methanol using a converter gas capable of producing methane.

[0002]

2. Description of the Related Art In recent years, as environmental problems have been highlighted, various studies have been made in the steel industry on the effective use of a large amount of by-product gas from a blast furnace, a coke oven, and a converter. On the other hand, the automobile industry is also researching and developing a fuel cell as a next-generation engine replacing a gasoline engine, and hydrogen gas, natural gas, methanol, and the like are being studied as fuels. Among these fuels, methanol is considered to be one of the most promising in terms of ease of handling, C / H ratio (ratio of hydrogen to carbon), safety, and low cost. Research is under way.

Accordingly, the applicant company has conducted various studies on a method for producing methanol using by-product gas generated from an iron-making process.
No. 025 and JP-A-4-243845. However, the former method has a problem in that a step of separating methane is required in the production process of the reducing gas, and the production step becomes complicated and expensive. The latter requires the installation of a separate desulfurization facility to prevent the catalyst from being poisoned by sulfur when synthesizing methanol, and requires a very high pressure to compensate for the low partial pressure. And the process is not suitable for mass production.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and solves the above-mentioned problems by solving the problem of the exhaust gas containing less sulfur generated from the converter of a steelworks, the steam generated from the exhaust heat of the steelworks, and The present invention has been completed for the purpose of providing a method for producing methanol using a converter gas, which can produce methanol at low cost by utilizing heat retained in a slab of a casting line.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to provide a mixed gas by adding steam and natural gas to a converter gas, guide the mixed gas to a continuous casting line, The mixed gas is thermally decomposed into CO gas and H ₂ gas by utilizing the heat retained in the slab in the casting line. Then, the CO gas and H ₂ gas are decomposed in a low-temperature, high-pressure Is synthesized.

Further, the mixed gas is led to a continuous casting line,
A method for decomposing a mixed gas into CO gas and H ₂ gas by using heat retained in a slab is defined as the invention according to claim 2, and further, the methanol gas obtained by the synthesis is cooled to room temperature to perform distillation separation. The method of recovering the liquid methanol as liquid methanol is defined as the invention according to claim 3.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail. In general, a methanol synthesis reaction is composed of two processes, (1) a reducing gas production process and (2) a methanol synthesis process, which are represented by the following reaction formulas (1) and (2), respectively.

[0008]

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The above-mentioned reducing gas production process is widely used in the direct reduction iron making process. In addition to the steam reforming method of Chemical Formula 1, there are three methods, namely, a carbon dioxide gas reforming method and a partial oxidation method. Adopt a steam reforming method suitable for mass production and inexpensive. In this steam reforming method, the reaction temperature is 8
This is an endothermic reaction in which decomposition proceeds at 50 ° C or higher, and the progress of the reaction requires additional heat from the outside. However, there are many parts that emit high-temperature heat of 850 ° C or higher in steel mills. And it is possible to use that heat. In particular, when utilizing the retained heat of the slab of the continuous casting line at the time of supplying the additional heat, it is possible to continuously maintain a temperature of 900 ° C. or more, and a facility for supplying the retained heat of the slab to the synthesis gas is: It is preferable because it can be easily installed and repaired on a casting facility. In addition, the steam reforming method requires a large amount of steam.However, a technology for producing steam from the sensible heat of exhaust gas from a converter and the like has already been established in steel mills, and the necessary and sufficient amount of steam can be produced at extremely low cost. It is preferable because it can be supplied.

[0010] On the other hand, many practical plants are already operating in the methanol synthesis process, and each plant has its own characteristics, but can be roughly classified into two types.
Representative examples thereof include the high pressure method and the ICI method. High pressure method ZnO-Cr ₂ O ₃ catalyst under 15 to 20 MPa,
It is carried out under the condition of 300 to 400 ° C. and is characterized in that the reaction of the catalyst is not reduced by sulfur gas. However, since it is a very high pressure facility, there is a disadvantage that mass production cannot be performed.
On the other hand, the ICI method (Imperial Chemical
(Industries (UK)) method is 3-5 MPa, 150-3 under a Cu-ZnO-based catalyst.
It is performed under the condition of 00 ° C. This equipment is characterized by the fact that the reaction temperature and pressure are both low, so that the equipment can be enlarged.However, this catalyst has a reduced reaction activity due to sulfur gas. It is necessary to remove sulfur content in the desulfurization process. Since the converter gas used in the present invention has a very low sulfur content and does not require desulfurization, IC
It is also possible to select a low-temperature and low-pressure process of a Cu-ZnO-based catalyst typified by the method I to increase the size of the equipment. In addition. After synthesizing methanol gas, it is cooled, separated by distillation, recovered as liquid methanol, and can be easily transported by truck, pipe, or the like. Since it is liquid at room temperature, it is easy to store.

Next, an example in which the present invention is specifically applied to a steelmaking factory will be described with reference to the drawings. The drawing is
FIG. 1 is an overall view of an apparatus for producing methanol by using exhaust gas generated from a converter in a steelmaking plant. In the figure, reference numeral 1 denotes a converter composed of a desulfurization furnace 1a, a dephosphorization furnace 1b, and a decarburization furnace 1c. The furnace 2 is a continuous casting line, and 2a is a slab conveying path. Reference numeral 3 denotes a storage container for storing exhaust gas generated from the converter 1, reference numeral 4 denotes a steam supply device, reference numeral 5 denotes a natural gas supply device, and reference numeral 6 denotes a converter gas storage container 3, a steam supply device 4, and a natural gas supply device. This is a reducing gas mixer that receives a supply of gas from the supply device 5 to make a mixed gas of an appropriate ratio. In this equipment layout, the configuration of one converter differs for each steelworks, and it is not always necessary to provide all of 1a, 1b, and 1c, and 1b and 1c may be shared. The container may be an electric furnace, a converter, a pan, a mixed iron wheel, or the like.

The mixed gas produced by the reducing gas mixer 6 is led to the slab conveying path 2a of the continuous casting line 2 and is brought into contact with or close to the slab. Heat of the slab (900-1
000 ° C.) to thermally decompose into CO gas and H ₂ gas (see Chemical Formula 1). In this case, the heat required for disassembly is secured by the slab, so no special heating source is required and the disassembly process can be performed economically. Repair on a single transport path is easy.

The reduction gas production process is completed as described above, and then a methanol synthesis process is performed. C obtained in the above step
The O gas and the H ₂ gas are led to the methanol reaction tower 9 where methanol is synthesized under a methanol synthesis catalyst (see Chemical Formula 2). Reference numeral 8 denotes a pressurizing device for setting the inside of the methanol reaction tower 9 to a reaction pressure. Next, the synthesized methanol is introduced into a methanol separation column 10 and cooled to room temperature to obtain liquid methanol.

As described above, according to the present invention, useful methanol can be safely produced in large quantities and inexpensively from converter gas by using raw materials and heat sources in an ironworks. At the same time, by fixing the converter gas as methanol, an effect of suppressing the amount of CO ₂ emitted to the atmosphere can be obtained.

[0015]

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Embedded image Finally, the economical benefits are explained using a reaction formula.
The reaction formulas of the reduction gas production process and the methanol synthesis process in the present invention are as shown in Chemical Formulas 3 and 4, respectively.
In the present invention, natural gas is added to the exhaust gas and steam of the converter as shown in Chemical formula 3 to synthesize a reducing gas, which is synthesized into methanol as shown in Chemical formula 4, but the reaction stoichiometry is 1 mol. 1.5 mol of methanol is produced from this natural gas. Further, in the existing methanol synthesis process, the cost of burning natural gas to produce H ₂ O (g) and CO (g) gas of Chemical Formula 3 and -260 kJ / mol
This process requires very little natural gas for existing methanol synthesis because of the cost of supplementing the additional heat with natural gas.

[0016]

As is apparent from the above description, the present invention makes it possible to produce methanol in a large amount and stably using exhaust gas and steam generated from a converter of an ironworks.
In addition, since low-sulfur exhaust gas is used, a large-scale desulfurization facility is not required, and methanol can be produced at low cost by using a slab heat source in a steelmaking line. By fixing the converter gas, which is originally emitted as CO _{2 to the} atmosphere, as methanol, an effect can be obtained for preventing global warming. Therefore, the present invention greatly contributes to industrial development as a method for producing methanol using a converter gas that has eliminated the conventional problems.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Converter 2 Continuous casting line 2a Slab conveyance path 3 Converter gas storage container 4 Steam supply container 5 Natural gas supply device 6 Reduction gas mixer 7 Piping 8 Compressor 9 Methanol reaction tower 10 Separation tower 11 Purification tower

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // C07B 61/00 300 C07B 61/00 300 F term (reference) 4G040 BA02 BB02 EA03 EA06 EB44 4G140 BA02 BB02 EA03 EA06 EB44 4H006 AA02 AC41 AD11 BA05 BA07 BA30 BC10 BC11 BC13 BD10 BD70 BE20 BE40 FE11 4H013 BA01 4H039 CA60 CB20 CL35

Claims (3)

[Claims] 1. A mixed gas is prepared by adding steam and natural gas to a converter gas. The mixed gas is guided to a continuous casting line, and the mixed gas is converted into CO by utilizing the heat of the slab in the casting line. A method for producing methanol using a converter gas, comprising thermally decomposing into gas and H ₂ gas, and then synthesizing this CO gas and H ₂ gas into methanol using a catalyst in a low-temperature, high-pressure reaction tower. . 2. The method according to claim 1, wherein the mixed gas of the converter gas, the steam and the natural gas is led to a continuous casting line, and the mixed gas is decomposed into CO gas and H ₂ gas by utilizing the retained heat of the slab. A method for producing methanol using converter gas. 3. The method for producing methanol using converter gas according to claim 1, wherein the methanol gas obtained by the synthesis is cooled, separated by distillation, and recovered as liquid methanol.