KR20200105601A - Methanol synthesis process exploiting by-product gas from steelmaking plant - Google Patents

Abstract

The present invention relates to a process for synthesizing methanol using Linz-Donawitz converter gas (LDG), which is a by-product gas from steelmaking. The present invention is a high-efficiency, eco-friendly process with reduced carbon emissions, which uses coke oven gas (COG) and LDG to produce methanol, a high value-added product. A method for synthesizing methanol from a steelmaking by-product gas according to the present invention includes the steps of: (1) a COG separation step of producing a mixed gas having a hydrogen content of 70% or more from COG through a gas separation process; (2) a step of preparing a mixed gas for methanol synthesis by mixing LDG and the separated-COG gas of which main component is hydrogen while adjusting a mixing ratio to obtain a mixed gas composition suitable for methanol production; and (3) synthesizing methanol using the mixed gas for methanol synthesis.

Description

Methanol synthesis process exploiting by-product gas from steelmaking plant}

The present invention relates to a process for synthesizing methanol using a converter gas, which is a by-product gas of steel making, and uses a coke oven gas (COG) and a converter gas (Lintz-Donawiaz convert Gas, LDG) to produce methanol, a high value-added product. It is a highly efficient and eco-friendly process that produces and reduces carbon emissions.

Methanol itself can be used as a fuel or fuel additive or as a major starting material for petrochemical raw materials such as synthetic resins, chemical fiber raw materials, MTBE, and acetic acid. A method mainly commercially used for methanol synthesis is a method of utilizing synthesis gas generated through gasification of coal or biomass or reforming of natural gas. However, in general, gasification of coal or biomass carried out using a fluidized bed reactor requires a dust collector to collect dust as well as sulfur compounds or nitrogen oxides contained in the raw material. It is a situation in which most (70% or more) are produced from syngas obtained through gas reforming. However, since the reforming reaction of methane occurs at a high temperature and is a strong endothermic reaction, a lot of energy must be supplied from the outside in order for the methane reforming reaction to occur.

On the other hand, the reaction of synthesizing methanol from the synthesis gas of carbon monoxide and hydrogen generated by the reforming of natural gas is as shown in Reaction Formula (1), and methods for increasing the efficiency of such a synthesis reaction have been studied in various ways.

CO + 2 H ₂ ↔ CH ₃ OH ΔH = -90.8kJ/mol (1)

In addition, as a countermeasure against global warming, a method of synthesizing methanol by mixing carbon dioxide and hydrogen as shown in Reaction Equation (2) below has also been widely used as a method of efficiently utilizing carbon dioxide for reducing carbon dioxide emission.

CO ₂ + 3 H ₂ ↔ CH ₃ OH + H ₂ O ΔH = -49.6kJ/mol (2)

Moreover, in the case of producing synthetic gas by steam reforming natural gas with a high content of carbon dioxide, the synthesis reaction of methanol by the conventional synthesis gas of hydrogen and carbon monoxide and the synthesis reaction of methanol by mixing carbon dioxide and hydrogen are shown in the following reaction formula ( As shown in 3), recently, as an economical utilization reaction of carbon dioxide, as a mixed reforming reaction of natural gas, a reaction capable of synthesizing methanol by performing a reforming reaction of carbon dioxide and methane simultaneously with the steam reforming reaction has been developed. It is mainly used.

CO ₂ + CO + 5H ₂ ↔ 2CH ₃ OH + H ₂ O (3)

As shown in Reaction Formulas (1)(2), the reaction of synthesizing methanol by hydrogenation of carbon monoxide and carbon dioxide is an exothermic reaction, one carbon monoxide molecule reacts with two hydrogen molecules, and one carbon dioxide molecule is three hydrogen molecules. It can be seen that it reacts with to make methanol. In other words, it can be seen that when methanol is synthesized by hydrogenation of a mixture of carbon monoxide and carbon dioxide, the ratio of H ₂ /(2CO + 3CO ₂ ) should be 1.

The domestic demand for methanol is about 1.5 million tons/year, and the demand is expected to increase further in the future. However, since it requires a lot of cost to produce syngas from natural gas and to synthesize methanol from it again, recently, it is a method that can synthesize methanol by a cheaper method, or a fuel that can replace methanol. It is a situation in which development is required.

In the steel industry, a large amount of by-product gas is generated, and depending on each process, coke oven gas (COG), blast furnace gas (BFG) and Lintz-Donawiaz convert gas , LDG). The steel by-product gas mainly contains fuel substances such as H ₂ , CH ₄ , CO and CO ₂ , and basic raw materials for the synthesis of chemical substances.

Iron ore and coke are needed to make molten iron, and coke refers to the coke that is steamed in small lumps before being put into the blast furnace. The gas generated in the process of drying bituminous coal in the coke oven is coke oven gas (COG), which has a calorific value of 4,400 Kcal/Nm ³ , contains a large amount of hydrogen, carbon monoxide and carbon dioxide, and contains 25% of CH ₄ etc. It contains.

Blast furnace gas (BFG) is a gas that is generated when coke is burned in the process of manufacturing pig iron by charging iron ore and coke in the blast furnace, and it contains a large amount of nitrogen because it uses air during the process. The calorific value is 750 Kcal/Nm ³ .

Converter gas (LDG) is a gas generated in the process of making pig iron into steel.It is a gas that is generated when carbon in the molten iron is combined with oxygen in the process of charging and injecting oxygen into the converter of a steel mill. The calorific value is 2,000 Kcal. /Nm ³ LDG is a hazardous substance, and has the highest specific gravity with 50 to 80% of carbon monoxide, and is composed of hydrogen, nitrogen, carbon dioxide, and carbon monoxide.

An object of the present invention is to provide a new process and optimal process conditions for producing methanol using steel by-product gas.

A first aspect of the present invention is (1) a COG separation step of producing a mixed gas having a hydrogen content of 70% or more from coke oven gas (COG) through a gas separation process; (2) In order to obtain a mixed gas composition suitable for methanol production, a mixed gas for methanol synthesis was prepared by mixing the separated-COG gas containing the hydrogen as the main component and a converter gas (Lintz-Donawiaz convert Gas, LDG) while controlling the mixing ratio. Manufacturing steps; And (3) synthesizing methanol using the mixed gas for methanol synthesis. It provides a method for synthesizing methanol from the steel-making by-product gas comprising a.

A second aspect of the present invention is a system for synthesizing methanol from steel by-product gas for performing the methanol synthesis method of the first aspect, comprising: a COG separator for increasing the content of hydrogen from coke oven gas (COG) to 70% or more; A gas mixer capable of mixing a converter gas (LDG) with the hydrogen-rich COG separated in the COG separator, and adjusting a mixing ratio to obtain a mixed gas composition suitable for methanol production; A methanol synthesis reactor accommodating a methanol synthesis catalyst in which the mixed gas prepared in the gas mixer is supplied as a reactant; And a gas-liquid separator for separating methanol from the unreacted gas of the methanol synthesis reactor by gas-liquid; it provides a methanol synthesis system from the steel-making by-product gas characterized in that it comprises.

Hereinafter, the present invention will be described in detail.

The present invention is one of the steel by-product gases, in order to utilize the CO-rich converter gas (LDG) in the methanol synthesis process, after producing a hydrogen-rich gas from coke oven gas (COG) containing hydrogen and methane as the main components, CO is It is characterized in that a mixed gas containing hydrogen and carbon monoxide is prepared by mixing it with a converter gas (LDG), which is a main component, in an appropriate ratio, and converting the prepared mixed gas into methanol through a catalytic process.

When synthesizing methanol from syngas containing H ₂ and CO, it is recommended to maintain the stoichiometric ratio R (H ₂ /(2CO+3CO ₂ )) of the syngas at 0.85 to 1.15 in order to increase the methanol production efficiency. By the way, the present invention is a result of comparing Figure 2 (methanol synthesis experiment result using COG and LDG mixed gas) and Figure 4 (methanol synthesis experiment result using separated-COG and LDG mixed gas), between the methanol production amount and the mixing ratio Found that an unexpected relationship appeared. In addition, COG is not typically separated is H ₂ composition is inde 55 ~ 65%, since the separation process COG is increased the H ₂ purity and H ₂ composition reaches 89%, this case is simply a mixture of COG and LDG for methanol synthesis Unlike the case of preparing a mixed gas, not only the CO conversion rate and the CO ₂ conversion rate are remarkably improved by adjusting the separated-COG and LDG to an appropriate molar ratio within the range of different mixing ratios, but also methanol with a higher yield and production amount. It was found that it can be synthesized. The present invention is based on this.

In the present invention, after preparing a hydrogen-rich gas from COG, the mixture is mixed with LDG, which is the main component, within a rather wide specific ratio range, to produce a mixed gas containing hydrogen and carbon monoxide, and the prepared gas is subjected to a catalytic process. Methanol conversion is possible with high methanol production. Accordingly, the present invention uses coke oven gas (COG) rich in hydrogen and methane and LDG rich in carbon monoxide among the byproduct gases generated in the steelmaking process to synthesize methanol as raw materials, thereby providing a new process for utilizing steelworks byproduct gas. This process meets the global issues of energy saving and efficient use of waste because it does not separately manufacture syngas required for methanol synthesis. In addition, the methanol synthesis process according to the present invention converts hydrogen, carbon monoxide, and carbon dioxide contained in the steelmaking by-product gas to produce methanol with high efficiency and high efficiency, so that by-product gas is generally used as a fuel for power generation in the steelmaking process. It is an economical and eco-friendly process with low carbon emissions. Therefore, in the case of the process according to the present invention, it is possible to reduce the greenhouse gas and solve the problem of supply and demand of basic chemicals.

1 schematically shows a flow chart of a methanol synthesis process using COG and LDG of steel by-products according to an embodiment of the present invention.

The method for synthesizing methanol from steel by-product gas according to the present invention

(1) COG separation step of producing a mixed gas having a hydrogen content of 70% or more from coke oven gas (COG) through a gas separation process;

(2) In order to obtain a mixed gas composition suitable for methanol production, a mixed gas for methanol synthesis was prepared by mixing the separated-COG gas containing the hydrogen as the main component and a converter gas (Lintz-Donawiaz convert Gas, LDG) while controlling the mixing ratio. Manufacturing steps; And

(3) synthesizing methanol using the mixed gas for methanol synthesis;

Includes.

The methanol synthesis system for performing the methanol synthesis method from steel by-product gas according to the present invention

COG separator to increase the content of hydrogen from coke oven gas (COG) to 70% or more;

A gas mixer capable of mixing a converter gas (LDG) with the hydrogen-rich COG separated in the COG separator, and adjusting a mixing ratio to obtain a mixed gas composition suitable for methanol production;

A methanol synthesis reactor accommodating a methanol synthesis catalyst in which the mixed gas prepared in the gas mixer is supplied as a reactant; And

A gas-liquid separator for gas-liquid separation of methanol from unreacted gas in the methanol synthesis reactor;

Includes.

In the present invention, step (1) is a COG separation step of separating methane, carbon monoxide, and carbon dioxide from coke oven gas (COG) through a gas separation process and producing a mixed gas having a hydrogen content of 70% or more. Step (1) is equipped with a COG separator that increases the content of hydrogen from coke oven gas (COG) to 70% or more, such as a device for separating and removing methane, carbon monoxide, and carbon dioxide from COG to produce a permeate gas containing more than 70% hydrogen. It can be carried out in a COG separator.

Through the experiment, there is an appropriate mixing (molar) ratio between LDG:H ₂ in terms of CO conversion, CO ₂ conversion, methanol yield, and production, and further, separation through a separation process when preparing a mixed gas for methanol synthesis using LDG and COG It was found that there are remarkably excellent areas in terms of CO conversion, CO ₂ conversion, methanol yield, and production when using hydrogen-rich COG. Therefore, step (1) uses coke oven gas (COG), one of steel by-product gases as a source of H ₂ , but separates methane, carbon monoxide and carbon dioxide from COG through a separation process, and contains more than 70% hydrogen, preferably Is characterized in that a mixed gas of 80% or more, more preferably 85% or more is used as a hydrogen source of the mixed gas for methanol synthesis.

Since coke oven gas (COG) has a relatively high content of methane, which is an inert material in the methanol synthesis reaction, in the present invention, prior to mixing the coke oven gas with the LDG by-product gas, a separation process for separating hydrogen from the coke oven gas is performed. By doing so, it is possible to minimize the content of methane and maximize the content of hydrogen. In addition, the residual gas rich in CH ₄ , which is a by-product generated in the separation process, can be used as a heat source for a process or a combustion gas for power generation.

COG, one of the steel by-product gases, has a main component of hydrogen, which is mixed with methane, nitrogen, hydrogen sulfide, and dust, but is mainly used as a heat source for process or as a fuel for power generation. On the other hand, the degree of hydrogen separation from the COG by-product gas, which is required as a hydrogen source in the present invention, is sufficient by a separation membrane method that uses the difference in gas permeability from hydrogen and other gas permeability. Also, the investment and maintenance costs are relatively low. In addition, since the separation process is not for obtaining pure hydrogen, but for obtaining hydrogen-rich gas, it is possible to use pressure swing adsorption, cryogenic separation, etc. without being limited by the separation membrane process. .

For example, the principle of gas separation by a separation membrane is that at a high pressure gas is separated at a low pressure by permeating through the separation membrane by the affinity with the separation membrane or the kinetic size of the gas. The permeability of gases in the polymer membrane is in the order of H ₂ O> H ₂ >He> CO ₂ > O ₂ >Ar>CO> N ₂ > CH ₄ . Materials for polymer separation membranes for general COG by-product gas separation are polysulfone, polyimide, polyphenylene oxide, polycarbonate, poly(ether imide), etc. There is this.

Membrane for gas separation includes a porous membrane and a non-porous membrane. In the following examples of the present invention, a non-porous membrane was used as a separator for COG permeation. Non-porous membranes are generally polymer membranes, and gas separation occurs due to differences between molecules that dissolve and diffuse into the polymer membrane. The COG permeation mechanism is a solution-diffusion mechanism, which consists of three steps: (i) the feed mixture gas absorbs or adsorbs gas on the membrane interface, (ii) diffusion into the polymer membrane, and (iii) desorption or evaporation to the permeate side. . This mechanism depends on the thermodynamic activity of the gas acting on both sides of the membrane. The permeability of a gas molecule can be expressed as the product of the diffusion coefficient and solubility. 3 is a block diagram of a COG separation experiment apparatus using a hollow fiber membrane module.

In the present invention, step (2) is for methanol synthesis by mixing the separated-COG and converter gas (Lintz-Donawiaz convert Gas, LDG) whose hydrogen is the main component while controlling the mixing ratio to obtain a mixed gas composition suitable for methanol production. This is the step of preparing a mixed gas. Step (2) is a converter gas (LDG) is mixed with the hydrogen-rich COG separated in the COG separator, it may be carried out in a gas mixer capable of adjusting the mixing ratio to obtain a mixed gas composition suitable for methanol production.

As shown in Reaction Formulas (1)(2)(3), the synthesis reaction of methanol from synthesis gas requires twice as much hydrogen as the number of reacting carbon monoxide molecules and three times as much hydrogen in the case of carbon dioxide, so H ₂ / In the equation (2CO + 3CO ₂ ), it is necessary to keep its ratio close to 1. In general, H ₂ and CO syngas synthesized through methane reforming can achieve excellent production efficiency by maintaining a specific molar ratio, that is, the stoichiometric ratio R (H ₂ /(2CO+3CO ₂ )) of 0.85 to 1.15. Methanol can be synthesized. On the other hand, as shown in Table 2, for a mixed gas of H ₂ and LDG, R = 0.6 is also possible for the maximum methanol production (10 g/day). On the other hand, as shown in Table 3, in the case of a mixed gas of COG and LDG, R (H ₂ /(2CO+3CO ₂ ) = 0.6 ~ 2 for the maximum methanol production (10g/day). This is a COG: LDG ratio of 9: 1 to 7: 3. Further, as shown in Table 6, in the case of the separated-COG and LDG mixed gas, R (H ₂ /(2CO+3CO ₂ ) for the maximum methanol production (10 g/day) = 0.23 ~ 2.82 This is the mixture ratio (molar ratio) of separated-COG:LDG is in the range of 9:1 to 3:7 In short, in terms of methanol production (g/day), the mixture of COG:LDG (mol) While the ratio is preferably in the range of 9:1 to 7:3, in the present invention, the mixed (molar) ratio of separated-COG:LDG can be achieved in a wide range between 9:1 to 3:7, and methanol production ( In terms of g/day), the mixed (molar) ratio of -COG:LDG is preferably in the range of 8:2 to 5:5.

In the present invention, step (3) is a step of synthesizing methanol using the mixed gas for methanol synthesis.

Step (3) may be performed in a methanol synthesis reactor containing a methanol synthesis catalyst, in which the mixed gas prepared in a gas mixer is supplied as a reactant. For example, step (3) may be performed while passing the mixed gas prepared in step (2) through a fixed bed reactor filled with a methanol synthesis catalyst. In the present invention, when the separated-COG and LDG are mixed, carbon monoxide and hydrogen and carbon dioxide and hydrogen contained in the mixed gas form methanol through the reactions of the above reaction formulas (1) and (2). The conditions in which the reaction occurs can be carried out using the reaction conditions given for synthesizing methanol from conventional synthesis gas, but it is most preferable to apply reaction conditions of a temperature of 200 to 300°C and a pressure of 30 to 100 bar for methanol production. . The synthesis gas prepared in step (2) goes through a process of increasing pressure through a gas compressor to 30 ~ 100 atm and then enters the methanol synthesis reactor.

In the present invention, the methanol synthesis reaction is preferably the ratio H ₂ /(2CO + 3CO ₂ ) of the synthesis gas is 0.23 ~ 2.82, the space velocity is 1,000 ~ 50,000 h ^-1 .

In addition, the catalyst that can be used in the methanol synthesis reaction is a catalyst having high methanol conversion efficiency of hydrogen, carbon monoxide and carbon dioxide, and is not particularly limited, but, for example, a Cu/Zn/Al-based catalyst, a zinc-chromium oxide catalyst A (ZnCrOx)-based catalyst or a copper-based catalyst may be used.

Methanol synthesis reaction is an exothermic reaction, and reaction heat control is required to increase the methanol yield. To this end, the reaction heat can be controlled by the latent heat when the water vaporizes by flowing water as a refrigerant to the outside of the catalyst layer tube of the methanol synthesis reactor. Methanol synthesis reaction is an equilibrium reaction, and since the equilibrium conversion rate of the reactants decreases as the temperature increases, temperature control in the reactor becomes important.

As a catalyst for the methanol synthesis reaction, a Cu/ZnO/Al ₂ O _{3 type} catalyst is widely used, and in the present invention, a catalyst having a composition of CuO 52 to 58%, ZnO 22 to 27%, and Al ₂ O ₃ 6 to 9% is used. However, it is not particularly limited thereto.

Step (3) can produce high purity methanol having an average purity of 90% or more of methanol in the liquid product after gas-liquid separation.

In the present invention, after step (3) or while performing step (3), a step of gas-liquid separation of unreacted gas and methanol may be performed. The gas-liquid separation may be performed in a gas-liquid separator for gas-liquid separation of methanol and unreacted gas of the methanol synthesis reaction. The gas-liquid separator may be installed integrally at the rear end of the methanol synthesis reactor or inside the methanol synthesis reactor.

The method for synthesizing methanol from steel by-product gas according to the present invention further includes a step (4) of separating methanol synthesized in the previous step and unreacted gas, and recycling some or all of the unreacted gas to step (3). Can include.

In the case of one-pass operation, since the gas components participating in methanol synthesis remain in the unreacted gas, it can be recycled and injected together with the raw material for methanol synthesis. As recycling occurs, since the residual amount of gas indicating inertness to methanol synthesis in the unreacted gas increases, it is preferable to operate by controlling the ratio of the amount of recirculation and discharge of the unreacted gas (recycle ratio). At this time, it is preferable that the recycle ratio is in the range of 0.8 to 0.95 (Example 15). As the recycle ratio increases, the flow rate of the methanol reactor injection gas increases significantly, so the size of the methanol reactor increases, resulting in an increase in initial investment cost. In addition, as the recycle ratio decreases, the amount of hydrogen in the exhaust gas increases, so when considering the hydrogen production cost, the discharge amount should be reduced as much as possible. Therefore, a range of 0.8 to 0.95, which is the range of the recycle ratio in which the discharged flow rate does not exceed the injected LDG flow rate, is appropriate.

On the other hand, unlike the present invention in which COG is separated and mixed with LDG, if COG is not separated and mixed with LDG as it is, the gas component inert to the methanol synthesis reaction in COG becomes about 30-40%. If the amount of recycle is increased, the ratio of the inert gas in the raw material for methanol synthesis increases, and the partial pressure of the active gas components (CO, CO ₂ , H ₂ ) decreases, so that the methanol synthesis reaction activity decreases, so the reaction pressure must be further increased. An increase in process pressure may cause a problem of equipment stability and an increase in equipment cost. In addition, when COG is used without separating, the flow rate of the methanol synthesis reactor injection gas increases significantly as the recycle ratio increases, and thus the overall size of the methanol synthesis reaction system increases, thereby increasing the initial investment cost. In addition, as the recycle ratio decreases, the amount of raw material decreases, but it is not efficient because the amount of unreacted and discharged gas increases. If LDG and COG are used as they are, the composition of the inert gas is high, which is not suitable for the methanol synthesis process. The present invention (Example 16), which separates COG and mixes it with LDG, reduces the initial investment cost because the flow rate of the injected gas is small at the same recycling rate compared to the case of mixing LDG and COG as it is (Comparative Example 13). In addition, since the composition of the gas used as a raw material increases, the flow rate of LDG and separated COG required as a raw material decreases, thereby reducing the process cost. In addition, since the flow rate of gas discharged at the same recycling rate is reduced, process efficiency can be increased.

For example, after cooling the product passing through the methanol synthesis reactor according to the present invention, methanol as a liquid product is obtained by gas-liquid separation, some unreacted synthesis gas in the gas phase is discharged, and the unreacted gas is pressurized as a raw material for the methanol reactor Can be recycled. Accordingly, according to the present invention, the methanol synthesis system from the raw material of the iron-making by-product includes a gas-liquid separator for gas-liquid separating unreacted gas and methanol of the methanol synthesis reactor; And it may be provided with a pipe for recycling some or all of the unreacted gas separated here to the methanol synthesis reactor.

According to one embodiment of the present invention, the purity of methanol during the one-pass operation is 95.5%, and the purity of methanol during the recycle operation is about 92% on average, all of which can produce high-purity methanol.

When the methanol synthesis process from the steel-making by-product gas of the present invention is applied instead of the by-product gas power generation process, it is possible to provide a high-efficiency, eco-friendly steel-making process with reduced carbon emissions.

The present invention proposes a new process for synthesizing methanol by separating coke oven gas (COG) rich in hydrogen as a by-product gas generated in the steelmaking process through a separation process, and mixing it with a converter gas (LDG) rich in carbon monoxide in a specific ratio. do. By using this process, it is possible to achieve high value-added by-product gas in steel mills, and to reduce the use of fossil fuels and energy used in syngas production.

1 schematically shows a flow chart of a methanol synthesis process using COG and LDG of steel by-products according to an embodiment of the present invention.
2 is a graph showing the result of a methanol synthesis experiment using a mixed gas of COG and LDG, which is an iron-making by-product gas.
3 is a schematic diagram of a COG separation experiment equipment.
4 is a graph showing the result of an experiment for methanol synthesis using separated -COG and LDG gas mixture.
5 shows a process flow diagram (PFD) of a methanol synthesis process using a COG + LDG gas mixture according to one embodiment.
6 shows the PFD of the methanol synthesis process using the separated -COG + LDG gas mixture according to an embodiment.

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited by the following examples.

[Methanol synthesis experiment]

In the reaction experiment, a pellet-type catalyst having a composition of 52 to 58% CuO, 22 to 27% ZnO, and 6 to 9% Al ₂ O ₃ was used for methanol synthesis. The weight of the commercial catalyst was 0.6g (25 ~ 40 mesh), the weight of the sea sand (diluent) was 1.8 g, and the catalyst: diluent = 1:3 was physically mixed and loaded into the reactor, and the temperature was 250 ℃, H ₂ for 3 h. After reduction in the atmosphere, a methanol synthesis reaction experiment was performed.

The results of methanol synthesis using the steel-making by-product gas according to the present invention are shown in the following table, and the equilibrium conversion rate for each synthesis gas composition was calculated by a simulation program (HSC Chemistry) and shown in tables and figures.

Example 1 to 4: With by-product hydrogen LDG Methanol synthesis using mixed gas

Using the same model gas and hydrogen gas as the composition of the converter gas (LDG: H ₂ , N ₂ , CO, CO ₂ ) as raw materials, a methanol synthesis reaction was performed according to the mixing ratio of the LDG model gas and hydrogen gas.

Operating conditions were maintained at a temperature of 250°C and a pressure of 50 bar, and the LDG flow rate was maintained at 30.7 ml/min in the same catalyst as shown in Table 1 below, and the H ₂ flow rate was based on H ₂ /LDG = 1.6 (R=1). The methanol synthesis reaction was carried out by changing the H ₂ ratio to decrease by 0.2.

Table 1 below shows the feed injection flow rate according to the LDG: H ₂ ratio, and Table 2 shows the methanol synthesis experiment results according to the H ₂ + LDG mixing ratio.

LDG: H ₂ ratio LDG
(ml/min) H ₂
(ml/min) 1: 1.6 30.7 49.3 1: 1.4 43.0 1: 1.2 36.8 1: 1.0 30.7

division Mixing ratio LDG (mol %) R ^* Equilibrium conversion rate Experiment result value Methanol
yield
(%) Methanol
output
(g/day) CO conv. (%) CO ₂ conv. (%) CO conv.
(%) CO ₂ conv.
(%) Total conv.
(%) LDG H ₂ H ₂ CO CO ₂ N ₂ Example 1 One 1.6 62.1 21.5 6.3 10.1 1.0 55.7 4.3 56.1 4.8 44.4 44.3 20.3 Example 2 One 1.4 54.2 21.5 6.3 10.1 0.9 51.2 3.4 52.8 2.5 41.4 41.3 18.7 Example 3 One 1.2 46.5 21.5 6.3 10.1 0.8 46.1 2.6 48.3 2.3 37.8 37.7 17.2 Example 4 One 1.0 38.8 21.5 6.3 10.1 0.6 40.1 1.8 43.6 1.3 34.0 33.9 15.4 * R: H ₂ /((2CO+3CO ₂ )

At a specific molar ratio of LDG+H ₂ mixed gas, that is, the stoichiometric ratio R (H ₂ /(2CO+3CO ₂ ) = 0.85 to 1.15), it is possible to optimize the conversion rate of raw materials, methanol yield and production. Here, when the H ₂ /LDG ratio is 1.6, R=1, and as the H ₂ ratio decreases, the R value decreases from 1 to 0.6, and the methanol production also decreases. As the hydrogen ratio decreases, the ratio of H ₂ , CO and CO ₂ according to the methanol synthesis chemical reaction equation It means that it does not reach the equivalent ratio. Therefore, when the R value is less than 0.6, the carbon conversion rate and the methanol production amount are very low, which is not preferable. When the R value exceeds 1, the expensive amount of H ₂ is increased, which is not preferable because it is not economical.

Example 5 to 7 and Comparative example 1 to 8: Steel by-product gas Inn COG and LDG Methanol synthesis using mixed gas

Methanol synthesis reaction using model gas of coke oven gas (COG: H ₂ , N ₂ , CO, CH ₄ , CO ₂ ) and converter gas (LDG: H ₂ , N ₂ , CO, CO ₂ ) among steel by-product gases Was performed. Operating conditions were maintained at a temperature of 250° C., a pressure of 50 bar, and a space velocity of 8000 ml/g _cat h, and the methanol synthesis reaction was performed by varying the mixing ratio of COG and LDG in the same catalyst. The mixing ratio of COG + LDG of the injected gas and the reaction results are shown in Table 3 below.

division Mixing ratio Composition (GC result) R ^* Equilibrium conversion rate Experiment result conversion rate Methanol
yield
(%) Methanol
output
(g/day) COG
(%) LDG
(%) Before reaction
(%) After reaction
(%) CO
(%) CO ₂
(%) CO
(%) CO ₂
(%) Total
(%) Comparative Example 2 10 0 H ₂ 59.3 57.8 2.44 60.8 18.8 64.5 15.5 52.6 52.6 8.5 N ₂ 6.6 7.8 CO 7.5 3.2 CH ₄ 24.2 28.7 CO ₂ 2.4 2.4 Example 6 9 One H ₂ 53.5 50.4 1.38 51.7 6.8 55.7 10.6 45.1 43.5 12.4 N ₂ 8.4 10.7 CO 12.6 7.1 CH ₄ 21.7 27.6 CO ₂ 3.7 4.2 Example 5 8 2 H ₂ 47.7 41.8 0.89 42.7 3.5 41.8 -4.1 31.1 31.1 12.5 N ₂ 10.4 13.5 CO 17.8 13.2 CH ₄ 19.2 24.9 CO ₂ 4.9 6.6 Example 7 7 3 H ₂ 42.4 34.4 0.62 34.1 2.1 32.9 -3.5 24.5 24.5 11.8 N ₂ 12.1 15.7 CO 22.3 19.5 CH ₄ 16.9 21.9 CO ₂ 6.3 8.5 Comparative Example 3 6 4 H ₂ 36.0 30.4 0.44 25.2 1.1 17.9 2.5 14.3 14.3 8.5 N ₂ 13.9 16.5 CO 27.8 27.1 CH ₄ 14.1 16.7 CO ₂ 8.1 9.3 Comparative Example 1 5 5 H ₂ 30.4 22.8 0.31 18.4 0.7 17.0 -1.8 12.7 12.4 8.9 N ₂ 15.8 18.9 CO 32.6 32.5 CH ₄ 11.8 14.2 CO ₂ 9.5 11.6 Comparative Example 4 4 6 H ₂ 24.8 19.6 0.22 12.8 0.9 9.2 1.0 7.3 7.3 5.9 N ₂ 17.5 19.6 CO 37.4 38.0 CH ₄ 9.5 10.6 CO ₂ 10.9 12.1 Comparative Example 5 3 7 H ₂ 19.0 13.8 0.15 8.1 0 7.3 -1.0 5.4 4.8 4.9 N ₂ 19.3 21.3 CO 42.2 43.2 CH ₄ 7.1 7.9 CO ₂ 12.4 13.8 Comparative Example 6 2 8 H ₂ 13.5 10.6 0.09 4.5 0 3.5 -0.5 2.6 2.6 2.7 N ₂ 21.0 22.1 CO 46.8 47.6 CH ₄ 5.0 5.2 CO ₂ 13.7 14.5 Comparative Example 7 One 9 H ₂ 7.4 6.0 0.04 1.7 0 1.2 -0.3 0.8 0.2 0.9 N ₂ 23.0 23.4 CO 51.9 52.4 CH ₄ 2.5 2.6 CO ₂ 15.2 15.6 Comparative Example 8 0 10 H ₂ 1.5 1.2 0.01 0.2 0 -0.4 0.3 -0.2 0 0 N ₂ 24.8 24.8 CO 56.8 57.1 CH ₄ 0 0 CO ₂ 16.9 16.8 * R: H ₂ /((2CO+3CO ₂ )

As shown in Table 3 and Figure 2, the methanol synthesis reaction of the COG + LDG mixed gas according to the present invention is a result of comparing Examples 5 to 7 and Comparative Examples 1 to 8, and the mixing ratio (molar ratio) of the COG + LDG mixed gas is In the range of 9:1 to 7:3, the methanol production amount is preferably 10 g/day or more.

In the range of 9:1 to 7:3, the COG: LDG ratio is most preferable because the CO conversion is 30% or more, and the methanol yield and production amount is 20% and 10 g/day or more, and the COG: LDG ratio is 4:6 to In the range between 0:10, the conversion rate is less than 10%, the methanol yield and production amount is less than 10% and 10 g/day, which is not preferable.

Reference example 1: COG gas separation using a separation membrane

3 shows a configuration diagram of a COG separation experiment apparatus using a separation membrane. Since separation is not required with pure hydrogen, a single stage separation membrane process was performed.

In order to recover hydrogen in COG, a permeation experiment was conducted using a polysulfone hollow fiber membrane module (Synopex). In the COG separation experiment, a model gas having a composition of coke oven gas (COG: H ₂ , N ₂ , CO, CH ₄ , CO ₂ ) was used.

The separation membrane module was installed in a temperature-controllable oven to maintain a constant operating temperature. The flow rate of gas supplied to the separation membrane module installed in the mixed gas separation device was controlled by installing a gas flow controller (MFC) at the rear end of the gas regulator, and the operating pressure inside the separation membrane was supplied using a BPR (Back Pressure Regulator). The pressures of the gas, the residual part and the gas in the permeate part were adjusted. The flow rate of the gas passing through the separation membrane was measured with a Mass Flow Meter (MFM), and GC-TCD (YL-6100GC) was used for the measurement.

In the COG simulation gas separation test, the pressure difference between the supply side and the permeate side, the composition of the supply gas, and the operating temperature were kept constant, and the supply flow rate was adjusted to confirm the concentration and recovery rate of hydrogen in the permeate portion according to stage-cut. The operating conditions for separating the mixed gas are shown in Table 4 below.

Experimental conditions Supply pressure (bar) 9.1 Permeate pressure (bar) 1.1 Operating temperature (℃) 25 Supply flow rate (L/min) 2, 6, 10 Composition of injected gas H ₂ (%mol) 56.58 N ₂ (%mol) 7.31 CO (%mol) 7.8 CH ₄ (%mol) 25.81 CO ₂ (%mol) 2.49 Membrane module Effective membrane area (m ² ) 0.48

The stage-cut and recovery rate used to evaluate the performance of the separation membrane are defined as follows. Stage-cut is expressed as the ratio of the permeate flow rate to the supply flow rate, and was calculated by Equation 1 at a constant temperature and pressure.

H ₂ is a gas having a higher permeability than N ₂ , CO, CH ₄ , and CO ₂ for a general glassy polymer membrane, and is concentrated and recovered at the permeate portion. The H ₂ recovery rate was defined by Equation 2.

Table 5 below summarizes the gas compositions corresponding to the supply part, the permeation part, and the residual part by conducting a separation membrane permeation test of COG simulated gas. When the feed gas flow rate was 10 L/min, the composition ratio of H _{2 among} the compositions of the permeate gas was the highest by 89.0%, so the composition of the separated-COG was fixed by the composition ratio at this time, and the methanol synthesis reaction was performed by changing the mixing ratio with LDG.

Supply gas Permeate gas Residual gas H ₂
Recovery rate stage-cut H ₂ N ₂ CO CH ₄ CO ₂ flux H ₂ N ₂ CO CH ₄ CO ₂ flux H ₂ N ₂ CO CH ₄ CO ₂ flux %mol L/min %mol L/min % L/min % 56.6 7.3 7.8 25.8 2.5 2.0 71.2 4.1 5.7 15.9 3.1 1.6 3.1 18.9 15.6 62.2 0.2 0.4 98.8 0.79 6.0 85.1 1.7 2.7 6.9 3.6 3.5 16.1 16.3 14.9 51.8 0.9 2.5 88.0 0.59 10.0 89.0 1.1 1.7 4.5 3.7 5.1 23.5 13.6 14.0 47.6 1.3 5.0 79.5 0.50

Example 8-14 and Comparative example 9-12: separated-COG and LDG Methanol synthesis reaction using mixed gas

The operating conditions were maintained at a temperature of 250° C., a pressure of 50 bar, and a space velocity of 8000 ml/g _cat h, and the methanol synthesis reaction was performed by varying the mixing ratio of -COG and LDG separated from the same catalyst. The separated -COG + LDG mixing ratio and reaction results of the injected gas are shown in Table 6 below.

division Mixing ratio Composition (GC result) R ^* Equilibrium conversion rate Experiment result conversion rate Methanol
yield
(%) Methanol
output
(g/day) Separate
-COG
(%) LDG
(%) Before reaction
(%) After reaction
(%) CO
(%) CO ₂
(%) CO
(%) CO ₂
(%) Total
(%) Comparative Example 10 10 0 H ₂ 89.8 91.9 6.68 56.4 56.6 65.1 59.6 61.4 60.5 5.3 N ₂ 1.0 1.2 CO 1.7 0.7 CH ₄ 4.0 4.6 CO ₂ 3.5 1.6 Example 12 9 One H ₂ 83.9 87.4 2.82 71.5 26.6 79.6 39.0 63.5 63.5 10.3 N ₂ 2.5 3.2 CO 5.8 1.6 CH ₄ 3.7 4.6 CO ₂ 4.1 3.3 Example 11 8 2 H ₂ 75.5 78.0 1.64 67.2 12.3 72.3 17.9 54.8 63.5 15.0 N ₂ 4.6 6.6 CO 11.2 4.5 CH ₄ 3.3 4.6 CO ₂ 5.4 6.4 Example 9 7 3 H ₂ 66.2 65.2 1.02 57.1 5.1 61.3 7.9 46.2 46.2 18.3 N ₂ 6.9 10.5 CO 17.2 10.2 CH ₄ 2.9 4.3 CO ₂ 6.8 9.7 Example 8 6 4 H ₂ 58.6 53.8 0.73 46.4 2.6 50.6 6.1 38.8 38.8 19.1 N ₂ 8.7 13.6 CO 22.0 16.9 CH ₄ 2.5 3.8 CO ₂ 8.1 11.9 Example 10 5 5 H ₂ 49.7 42.1 0.51 34.1 1.3 35.4 -0.7 25.7 25.6 16.0 N ₂ 11.2 16.0 CO 27.7 25.5 CH ₄ 2.1 3.0 CO ₂ 9.3 13.3 Example 13 4 6 H ₂ 40.8 31.8 0.35 23.2 0.7 24.5 -0.6 17.8 17.7 13.3 N ₂ 13.5 18.0 CO 33.3 33.5 CH ₄ 1.7 2.3 CO ₂ 10.7 14.4 Example 14 3 7 H ₂ 31.7 23.3 0.23 14.6 0.2 16.2 -0.3 11.8 11.7 10.4 N ₂ 15.8 19.5 CO 39.1 40.6 CH ₄ 1.3 1.6 CO ₂ 12.1 15.0 Comparative Example 9 2 8 H ₂ 22.2 15.9 0.14 7.8 0.5 8.7 -0.7 6.2 6.1 6.3 N ₂ 18.2 20.7 CO 45.1 46.8 CH ₄ 0.9 1.0 CO ₂ 13.6 15.6 Comparative Example 11 One 9 H ₂ 12.1 11.2 0.07 2.9 0.1 1.0 0.1 0.7 0.5 0.8 N ₂ 20.8 21.1 CO 51.5 51.8 CH ₄ 0.4 0.4 CO ₂ 15.2 15.5 Comparative Example 12 0 10 H ₂ 1.4 1.4 0.01 0.1 -0.2 0.1 -0.2 0 0 0.1 N ₂ 23.4 23.4 CO 58.3 58.2 CH ₄ 0 0 CO ₂ 16.9 16.9 * R: H ₂ /((2CO+3CO ₂ )

As shown in Table 6 and Figure 4, the methanol synthesis reaction of the -COG + LDG mixed gas separated in Reference Example 1 was compared to Examples 8 to 14 and Comparative Examples 9 to 12, the separated -COG + LDG mixture When the gas mixture ratio (molar ratio) is in the range of 9:1 to 3:7, it is preferable because the methanol production amount is as high as 10 g/day or more based on 0.6 g of the catalyst, and it is possible to maintain the range of 8:2 to 5:5. It is more preferable to ensure the best methanol synthesis efficiency with a methanol production amount of 15 g/day or more. Separated-COG: LDG ratio in the range of 9:1 to 7:3, CO conversion is 30% or more, methanol yield and production is 20% and 15 g/day or more, so it is most preferable, and separated-COG: LDG In the range of 2:8 to 0:10, the conversion rate is less than 10%, the methanol yield and production amount is less than 10% and 10 g/day, which is not preferable.

Example 15: for methanol production Pilot Plant operation

The separated-COG and LDG mixed gas was used as a raw material and the operation was performed for 140 h operation time in a pilot plant for methanol production, and the results are shown in Table 8 below. During the pilot plant operation, the COG separation process was omitted, and the model gas according to the pre-test result was used. The composition of the model gas is shown in Table 7 below (the composition and mixing ratio of the model gas used during the pilot plant operation).

H ₂ N ₂ CO CH ₄ CO ₂ Separated-COG ⁽¹⁾ 89.0 1.1 1.7 4.5 3.7 LDG ⁽²⁾ 1.2 24.9 57.2 0 16.7 Model gas ^{[(1)/(2) = 2.2]} 61.8 8.5 18.9 3.1 7.7

Methanol synthesis reaction was performed using a packed bed reactor, and 770 g of a CuZnAl-based pellet-type catalyst was charged as the catalyst, and the reaction temperature was maintained at about 250°C and the pressure was maintained at about 50 bar. The space velocity was changed to 1,558 ~ 2,338 ml/g _cat ·h during one-pass operation and 3,116 ~ 4,052 ml/g _cat ·h during recycle operation.

Table 8 shows the results of the pilot plant operation for methanol production under the conditions of one-pass operation and a recycle ratio of 0.85 to 0.90.

TOS
(h) division Gas composition (%) Conversion rate (%) Space speed
(ml/g _cat h) Methanol
output
(kg/day) H ₂ N ₂ CO CH ₄ CO ₂ CO CO ₂ 0-5 One-pass
driving Feed 56.7 9.8 21.2 3.3 9.1 67.9 30.0 1,558 7.2 After reaction 56.3 16.8 10.4 4.8 11.8 104-
120 Recycle
driving Feed 49.8 20.0 11.3 6.6 12.3 51.1 7.0 5,701 9.6 After reaction 47.5 24.4 6.7 7.4 14.0

During the one-pass operation, after the methanol synthesis reaction, the gas composition decreased significantly compared to the feed gas, and the composition ratio of the relatively inert gas, N ₂ , increased significantly as H ₂ , CO, and CO ₂ were converted. In one-pass operation, CO and CO ₂ were high at 67.9% and 30.0%, respectively. When Recycle operation, Feed compositions are due to the accumulation of inert gases, was the N ₂ and CH ₄ ratio increased significantly compared to the one-pass operation, due to partial pressure decrease of the reaction gases CO, CO ₂ and H ₂ conversion is respectively 51.1% , Decreased to 7.0% and 21.5%. Due to the increase in feed amount, methanol production increased from 7.2 kg/day in one-pass operation to 9.6 kg/day in recycle operation.

The purity of methanol produced from the above process was calculated by measuring the specific gravity, and Table 9 shows the purity of methanol obtained from the pilot plant. It was 95.5% in one-pass operation and about 92.0% in recycle operation, all of high purity methanol.

division One-pass Recycle TOS (h) 4.7 54.5 97.8 135.3 Liquid specific gravity 0.816 0.832 0.823 0.829 Reference weight 0.803 0.805 0.805 0.806 Temperature (F) 45 41 42 40 Methanol purity (%) 95.5 90.6 93.6 91.9

Comparative example 13: COG + LDG Simulation of methanol synthesis process using mixed gas

In order to find out the economy and process efficiency according to the recycle ratio of gas after the methanol synthesis reaction, a process simulation of the methanol synthesis process using a COG + LDG gas mixture was performed. The simulation of the process was based on the scale of methanol production of 1,000 ktonne/yr using the ASPEN PLUS program, and the PFD (Process Flow Diagram) for the process is shown in FIG. 5 below. The process consists of a gas mixer, a compressor, a preheater, a methanol synthesis reactor, a DME (dimethyl ether) synthesis reactor, a heat exchanger, a gas-liquid separator, and a splitter. The DME synthesis reactor was included for calculation of the DME synthesis reaction, a side reaction occurring in the methanol synthesis reaction.

Table 10 shows the simulation results of the methanol synthesis process using COG + LDG mixed gas, and Table 11 shows the exhaust gas composition according to the recycle ratio of the methanol synthesis process using the COG + LDG mixed gas. As the amount of reactants H ₂ , CO and CO ₂ decreases as the recycle rate decreases, the COG and LDG flow rates increase in order to maintain production. The exhaust gas is mainly composed of H ₂ , CH ₄ , CO ₂ and N ₂ , as shown in Table 11 below, and when the recycle rate decreases, the exhaust gas flow rate increases, and the H ₂ utilization rate decreases. If the recycle flow rate exceeds the upper limit, the reactor size must be increased because the flow rate of the methanol reactor injection gas increases, which means that the initial investment cost increases.

The exhaust gas of the methanol synthesis process using the COG + LDG gas mixture mainly consists of H ₂ and N ₂ , and as the recycle rate decreases, the CH ₄ ratio in the exhaust gas decreases, and the H ₂ ratio increases. The exhaust gas of the above process can be used as a heat source of a power plant, and as the recycle rate decreases, the CH ₄ composition ratio with the highest calorific value decreases greatly, and as the H ₂ composition ratio with relatively low calorific value increases, the calorific value of the exhaust gas Decreased.

Recycle
ratio MeOH production
(ktonne/yr) COG flow
(kmol/h) LDG flow
(kmol/h) Vent flow (kmol/h) Methanol reactor
Injection gas flow rate (kmol/h) 0.95 1,000 10,330 4,987 3,671 85,070 0.9 1,000 10,993 5,356 4,803 59,578 0.8 1,000 12,067 5,879 6,523 44,039 0.7 1,000 13,019 6,258 7,925 37,769 0.6 1,000 13,816 6,613 9,125 34,117 0.5 1,000 14,607 6,922 10,258 31,787

Vent gas mole fraction (%) Recycle rate 0.95 0.9 0.8 0.7 0.6 0.5 CH ₄ 12.23 10.00 8.12 7.24 6.68 6.30 H ₂ O 0.01 0.01 0.00 0.00 0.00 0.00 CO 3.86 4.44 5.47 6.28 7.14 7.83 H ₂ 37.74 44.26 49.88 52.88 54.36 55.58 CO ₂ 9.64 11.25 12.16 12.18 12.12 11.92 MeOH 0.17 0.16 0.16 0.16 0.16 0.16 C ₂ H ₆ 0.00 0.00 0.00 0.00 0.00 0.00 C ₃ H ₈ 0.00 0.00 0.00 0.00 0.00 0.00 C ₄ H ₁₀ 0.00 0.00 0.00 0.00 0.00 0.00 N ₂ 36.34 29.87 24.19 21.25 19.53 18.21 O ₂ 0.00 0.00 0.00 0.00 0.00 0.00 DME 0.01 0.01 0.01 0.01 0.01 0.01 EtOH 0.00 0.00 0.00 0.00 0.00 0.00 Low heat generation (Kcal/Nm) 3,982 3,643 3,394 3,284 3,222 3,180

Example 16: separated-COG + LDG Simulation of methanol synthesis process using mixed gas

In order to find out the economy and process efficiency according to the recycle ratio of the gas after the methanol synthesis reaction, a process simulation of the methanol synthesis process using the separated -COG + LDG gas mixture was performed. The simulation of the process was based on the scale of methanol production of 1,000 ktonne/yr using the ASPEN PLUS program, and FIG. 6 shows a PFD (Process Flow Diagram) for the process.

The process additionally includes a COG separation process using a separation membrane before the process of mixing COG and LDG in the methanol synthesis process using a COG + LDG gas mixture.

Table 12 shows the simulation results of the methanol synthesis process using the separated -COG + LDG mixed gas, and Table 13 shows the exhaust gas composition according to the recycle ratio of the methanol synthesis process using the separated -COG + LDG mixed gas. As the recycle rate decreases, the amount of reactants H ₂ , CO and CO ₂ decreases, so the COG and LDG flow rates increase in order to maintain production. The exhaust gas is mainly composed of H ₂ , CH ₄ , CO ₂ and N ₂ , as shown in Table 13 below, and when the recycle ratio decreases, the flow rate of unreacted exhaust gas increases and the process efficiency decreases. Compared to Comparative Example 13 using LDG and COG as it is, since the flow rate of the injected gas is small at the same recycling rate, the initial investment cost can be reduced, and the composition of the gas used as a raw material increases. The flow rate is also small, which has the effect of reducing process cost. In addition, since the flow rate of the gas discharged at the same recycling rate is reduced, the process efficiency may be increased compared to Comparative Example 13.

Therefore, the methanol synthesis process using the separated -COG + LDG gas mixture according to Example 16 has high conversion efficiency of steelmaking by-product gas, and is a simple process consisting only of a simple separation process and a methanol conversion process.

The exhaust gas of the methanol synthesis process using the separated-COG + LDG mixture mainly consists of H ₂ and N ₂ , and as the recycle rate decreases, the CH ₄ ratio in the exhaust gas decreases, and on the contrary, the H ₂ ratio increases. . The exhaust gas of the process can be reused as a heat source of the process or fuel of a power plant. As the recycle ratio decreases, the CH ₄ composition ratio with the highest calorific value decreases, and as the H ₂ composition ratio with relatively low calorific value increases, the calorific value of the exhaust gas decreases.

Recycle
ratio MeOH production
(ktonne/yr) COG flow rate injected as raw material
(kmol/h) LDG flow
(kmol/h) Vent flow (kmol/h) Methanol reactor
Injection gas flow rate (kmol/h) 0.95 1,000 9,505 5,199 3,044 72,539 0.9 1,000 10,110 5,563 4,105 52,622 0.8 1,000 11,074 6,101 5,729 40,091 0.7 1,000 11,914 6,502 7,042 34,848 0.6 1,000 12,686 6,843 8,204 31,835 0.5 1,000 13,405 7,160 9,274 29,839

Vent gas mole fraction (%) Recycle rate 0.95 0.9 0.8 0.7 0.6 0.5 CH ₄ 1.62 1.28 1.01 0.89 0.82 0.76 H ₂ O 0.01 0.01 0.00 0.00 0.00 0.00 CO 3.92 4.47 5.54 6.43 7.20 7.91 H ₂ 41.39 48.27 53.69 56.39 58.08 59.20 CO ₂ 10.81 12.33 13.21 13.21 13.01 12.77 MeOH 0.16 0.15 0.15 0.15 0.15 0.15 C ₂ H ₆ 0.00 0.00 0.00 0.00 0.00 0.00 C ₃ H ₈ 0.00 0.00 0.00 0.00 0.00 0.00 C ₄ H ₁₀ 0.00 0.00 0.00 0.00 0.00 0.00 N ₂ 42.08 33.48 26.39 22.91 20.73 19.20 O ₂ 0.00 0.00 0.00 0.00 0.00 0.00 DME 0.01 0.01 0.01 0.01 0.01 0.01 EtOH 0.00 0.00 0.00 0.00 0.00 0.00 Low caloric value
(Kcal/Nm) 2,476 2,551 2,594 2,609 2,630 2,637

Although the present invention has been described with reference to the above-described embodiments and the accompanying drawings, different embodiments may be constructed within the concept and scope of the present invention. Accordingly, the scope of the present invention is defined by the appended claims and their equivalents, and is not limited by the specific embodiments described herein.

Claims (17)

(1) COG separation step of producing a mixed gas having a hydrogen content of 70% or more from coke oven gas (COG) through a gas separation process;
(2) In order to obtain a mixed gas composition suitable for methanol production, a mixed gas for methanol synthesis was prepared by mixing the separated-COG gas containing hydrogen as the main component and a converter gas (Lintz-Donawiaz convert Gas, LDG) while controlling the mixing ratio. Manufacturing steps; And
(3) synthesizing methanol using the mixed gas for methanol synthesis;
A method for synthesizing methanol from steel by-product gas, characterized in that it comprises a. The method of claim 1, wherein the separation process in step (1) uses a hydrogen separation process. The method of claim 1, wherein the separated-COG gas: LDG gas (mixed molar ratio) = 9:1 to 3:7 to be suitable for methanol production in step (2). The method of claim 1, wherein the separated-COG gas: LDG gas (mixed molar ratio) = 8:2 to 5:5 to be suitable for methanol production in step (2). The method of claim 1, wherein in step (3), the unreacted gas and methanol are separated by gas-liquid separation. The method according to any one of claims 1 to 5, wherein (4) separating methanol synthesized in the previous step and unreacted gas, and recycling some or all of the unreacted gas to step (3). Method for synthesizing methanol from steel by-product gas characterized in that it further comprises. The method of claim 6, wherein in step (4), the recycle ratio is in the range of 0.8 to 0.95. [7] The method of claim 6, wherein step (3) is characterized by producing high-purity methanol having an average purity of methanol of 90% or more in the liquid product after gas-liquid separation. According to any one of claims 1 to 5, (5) The CH ₄ rich residual gas separated and removed in the COG separation step further comprises the step of using as a heat source for a process or a combustion gas for power generation. Method for synthesizing methanol from by-product gas. The method according to any one of claims 1 to 5, wherein (3) the methanol synthesis step is performed under a temperature of 200 to 300°C and a pressure of 30 to 100 bar. As a methanol synthesis system from iron-making by-product gas for performing the methanol synthesis method according to any one of claims 1 to 5,
COG separator to increase the content of hydrogen from coke oven gas (COG) to 70% or more;
A gas mixer capable of mixing a converter gas (LDG) with the hydrogen-rich COG separated in the COG separator, and adjusting a mixing ratio to obtain a mixed gas composition suitable for methanol production;
A methanol synthesis reactor accommodating a methanol synthesis catalyst in which the mixed gas prepared in the gas mixer is supplied as a reactant; And
A gas-liquid separator for gas-liquid separation of methanol from unreacted gas in the methanol synthesis reactor;
Methanol synthesis system from steel by-product gas characterized in that it comprises a. The system of claim 11, further comprising a pipe for recirculating some or all of the unreacted gas separated in the gas-liquid separator to the methanol synthesis reactor. The system of claim 11, wherein the COG separator is provided with a hollow fiber membrane module. The method of claim 11, wherein in order to obtain a mixed gas composition suitable for methanol production, the gas mixer is characterized in that the mixing ratio (molar ratio) of the separated -COG + LDG synthesis gas can be adjusted in the range of 9:1 to 3:7. Methanol synthesis system from phosphorus steel by-product gas. The method of claim 11, wherein in order to obtain a mixed gas composition suitable for methanol production, the gas mixer is characterized in that the mixing ratio (molar ratio) of the separated -COG + LDG synthesis gas can be adjusted in the range of 8:2 to 5:5. Methanol synthesis system from phosphorus steel by-product gas. The system according to claim 11, wherein a gas compressor is provided between the gas mixer and the methanol synthesis reactor to compress the mixed gas in the methanol synthesis reactor and provide it as a feed gas. The system for synthesizing methanol from steelmaking by-product gas according to claim 11, wherein the CH ₄ rich residual gas separated and removed through a COG separator is supplied as a combustion gas for power generation through a pipe.

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