JP2023028524A - Method for producing methanol - Google Patents

Abstract

To produce methanol industrially and efficiently from waste.SOLUTION: A method includes: a gas component adjustment process (S3) of adjusting a composition of a waste-derived gas (G1) to be a primary adjustment gas (G2); a CO2 separation process (S4) of selectively separating at least part of carbon dioxide from the primary adjustment gas (G2) to be a secondary adjustment gas (G3); and a conversion process (S7) of converting at least part of the secondary adjustment gas (G3) into methanol as a raw material gas (G4). A volume ratio of hydrogen to carbon monoxide in the primary adjustment gas (G2) is 1.5 to 4.0, inclusive, and a content of CO2 in the secondary adjustment gas (G3) is 1 to 10 vol%, inclusive.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing methanol from waste.

Incinerable waste is usually disposed of by landfilling or incineration. In addition to landfilling, even incineration involves emissions of carbon dioxide and heat. Therefore, improvements are required from the viewpoint of global environmental problems such as global warming countermeasures.

In consideration of global environmental issues and with the aim of effectively utilizing waste, a method of converting waste into hydrogen, a high-energy substance, or methanol or dimethyl ether, one of the most basic organic substances, has been developed. being developed. For example, Patent Literature 1 discloses a waste treatment system including a step of synthesizing methanol from hydrogen and carbon dioxide obtained by gasifying waste. On the other hand, Non-Patent Document 1 discloses a method of recovering energy from waste by fluidized bed gasification technology.

WO2012-017893

Kohei Matsunaga, 5 others, "Energy Recovery from Waste by Fluidized Bed Gasification Technology", Ebara Times, Ebara Corporation, October 2007, No. 217, p. 17-21

However, according to the systems disclosed by US Pat.

An object of one aspect of the present invention is to industrially and efficiently produce methanol from waste.

In order to solve the above problems, a production method according to one aspect of the present invention is a method for producing methanol from a waste-derived gas obtained by gasifying waste, wherein the composition of the waste-derived gas is adjusted. , a gas component adjustment step to be a primary adjusted gas, a CO ₂ separation step of selectively separating at least a part of carbon dioxide (CO ₂ ) from the primary adjusted gas to be a secondary adjusted gas, and the secondary a conversion step of converting at least a portion of the regulated gas into methanol as a feedstock gas, wherein the volume ratio of hydrogen ( _H2 ) to carbon monoxide (CO) in the primary regulated gas is 1.5 to 4.0. and the content of CO ₂ in the secondary adjustment gas is 1 vol % or more and 10 vol % or less.

According to one aspect of the present invention, methanol can be industrially and efficiently produced from waste.

1 is a flow chart showing an example of a method for producing methanol according to Embodiment 1 of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a system diagram schematically showing the configuration of a methanol production apparatus according to Embodiment 1 of the present invention;

[Embodiment 1]
BEST MODE FOR CARRYING OUT THE INVENTION A method for producing methanol, which is one embodiment of the present invention, will be described in detail below together with a production apparatus used therein, using the drawings.

FIG. 1 is a flow chart showing an example of the method for producing methanol according to this embodiment. As shown in FIG. 1, the method for producing methanol of the present invention includes a gas acquisition step S1, a gas component adjustment step S3, a CO ₂ separation step S4, and a conversion step S7. The gas acquisition step S1 is a step of decomposing waste to obtain a gas containing carbon oxide and hydrogen (H ₂ ) (referred to as waste-derived gas G1), that is, a step of gasifying the waste. The gas component adjustment step S3 is a step of adjusting the composition of the waste-derived gas G1 to obtain the primary adjustment gas G2. The CO ₂ separation step S4 is a step of removing at least part of carbon dioxide (CO ₂ ) from the primary adjusted gas G2 obtained through the gas component adjustment step S3 to obtain a secondary adjusted gas G3. The conversion step S7 is a step of synthesizing methanol from at least part of the carbon oxides and hydrogen contained in the source gas G4, using the secondary adjustment gas G3 obtained through the CO ₂ separation step S4 as the source gas G4. Here, carbon oxide includes at least one of carbon monoxide (CO) and carbon dioxide (CO ₂ ).

The flowchart shown in FIG. 1 includes a gas cleaning step S2, a compression step S5, a moisture removal step S6, a cooling condensation step S8, and a purification step S9 in addition to the above steps. Each step is detailed below. In the present embodiment, as an example, the flowchart shown in FIG. 1 and a methanol production apparatus (hereinafter simply referred to as "production apparatus") that implements the production flow shown in the flowchart will be described. However, the gas scrubbing step S2, the compression step S5, the moisture removal step S6, the cooling condensation step S8, and the purification step S9 are steps that can be incorporated into the manufacturing flow if desired. The steps and the like described in the drawings of this specification are merely typical examples, and are not intended to limit the scope of the present invention.

(Configuration of methanol production equipment)
First, an example of the configuration of a manufacturing apparatus 100, which is an embodiment to which the present invention is applied, will be described. FIG. 2 is a system diagram schematically showing the configuration of the manufacturing apparatus 100 according to Embodiment 1. As shown in FIG.

As shown in FIG. 2, the manufacturing apparatus 100 of the present embodiment includes a gas acquisition device 1, a gas cleaning device 2, a gas component adjustment device 3, a _CO2 separation device 4, a compressor 5, and a water removal device. 6, a reactor 7, a condenser 8, a refining device 9, a residual gas combustion device 10, and paths L1 to L19. A production apparatus 100 of the present embodiment is an apparatus for producing methanol from waste. The method for producing methanol of the present invention is a method in which a gas containing carbon oxide and hydrogen obtained by decomposing waste is supplied as a raw material gas to the reactor 7 and converted into methanol.

In the present embodiment, the waste may be any substance containing organic matter from which a gas containing hydrogen and carbon oxide can be obtained in the gas obtaining step S1. Examples of the waste include garbage, paper waste, textile waste, plastic waste, sewage sludge, night soil, livestock waste, waste oil, rubber tires, black liquor, blackstrap molasses, and waste such as mixtures thereof. .

The gas acquisition device 1 is a device for performing a gas acquisition step S1 of decomposing waste to obtain gas containing carbon oxide and hydrogen (referred to as waste-derived gas G1). The gas acquisition device 1 causes the waste supplied from the path L1 to react within the device. As the gas acquisition device 1, known devices such as a fixed bed furnace, a fluidized bed furnace, a bubbling type fluidized bed furnace, a circulating fluidized bed furnace, and a circulating moving bed furnace can be used.

A path L2 is provided between the gas acquisition device 1 and the gas cleaning device 2 . Thereby, the waste-derived gas G1 is supplied to the gas scrubber 2 .

The gas cleaning device 2 is a device that performs a gas cleaning step S2 for cleaning the gas by removing impurities from the waste-derived gas G1. The gas cleaning step S2 can be performed by a known method, and as the gas cleaning device 2, a known device such as a wet cleaning tower or an electrostatic precipitator can be used.

A path L3 is provided between the gas cleaning device 2 and the gas component adjusting device 3 . As a result, the waste-derived gas G<b>1 cleaned by the gas cleaning device 2 is supplied to the gas component adjusting device 3 .

The gas component adjusting device 3 is a device that performs a gas component adjusting step S<b>3 for adjusting the components of the raw material gas supplied to the reactor 7 . A path L4 is provided in the gas component adjusting device 3, and hydrogen can be supplied via the path L4.

A path L5 is provided between the gas component adjusting device 3 and the CO ₂ separating device 4 . Thereby, the primary adjustment gas G2 adjusted in the gas component adjustment device 3 is supplied to the CO ₂ separation device 4 . As the gas component adjusting device 3, known devices such as a partial oxidation reactor, a steam reforming reactor, and an aqueous shift reactor can be used.

The CO ₂ separation device 4 is a device that performs a CO ₂ separation step S4 of selectively separating CO ₂ from the supplied primary adjustment gas G2 to obtain a secondary adjustment gas G3. A carbon dioxide discharge path L6 is provided in the CO ₂ separation device 4, and carbon dioxide can be discharged. As the CO ₂ separation device 4, known devices such as a pressure swing adsorption device, an absorption diffusion tower, a cryogenic carbon dioxide separation device, and a carbon dioxide separation membrane device can be used. The gas component adjustment performed in the gas component adjustment device 3 and the CO ₂ separation device 4 will be described in detail in the explanation of the gas component adjustment process below.

A path L7 is provided between the CO ₂ separator 4 and the compressor 5 . Thereby, the secondary adjustment gas G3 obtained through the CO ₂ separator 4 is supplied to the compressor 5 . The compressor 5 is a device that performs a compression step S5 for compressing the secondary adjustment gas G3 to a pressure suitable for methanol synthesis. As the compressor 5, a known compression device such as a centrifugal compressor, an axial compressor, or a reciprocating compressor can be used.

A path L8 is provided between the compressor 5 and the water remover 6 . Thereby, the compressed secondary adjustment gas G3 is supplied to the moisture removal device 6 . The water removing device 6 is a device that removes water from the compressed secondary regulated gas G3 and performs a water removing step S6 for reducing the amount of water in the secondary regulated gas G3. The moisture removing device 6 may be composed of a plurality of devices. For example, the moisture removal device 6 can be configured including a cooler and a gas-liquid separator.

A path L9 is provided between the moisture remover 6 and the reactor 7 . As a result, the secondary adjustment gas G3, the water content of which has been reduced in the water removing device 6, is supplied to the reactor 7 as the source gas G4.

The reactor 7 is a reactor that performs a conversion step S7 in which the gas containing carbon oxide and hydrogen supplied as the raw material gas G4 is reacted in the presence of a catalyst to convert it into methanol.

As the reactor 7, a known methanol synthesis reactor such as a quench type multi-stage adiabatic reactor or a heat exchange isothermal reactor can be used. When the heat exchange type isothermal reactor is used, the heat generated by the reaction in the catalyst layer can be recovered via the heat medium. Moreover, the reactor 7 may be a combination of a plurality of reactors, and by connecting reactors of the same type or having different structures in series, it is possible to improve the methanol production rate. At this time, a condenser 8 may be provided between each of the plurality of reactors.

A path L10 is provided between the reactor 7 and the condenser 8 . Thereby, the gas discharged from the reactor 7 is supplied to the condenser 8 . The condenser 8 is a device that cools the gas discharged from the reactor 7 and separates it into an unreacted residual gas G5 and a condensed liquid containing methanol and water in a cooling condensation step S8. As the condenser 8, a known device such as a water-cooled condenser, an air-cooled condenser, or an evaporative condenser can be used.

A path L11 is provided between the condenser 8 and the refining device 9 . As a result, the condensate containing methanol and water discharged from the condenser is supplied to the refining device 9 via the path L11.

A path L<b>14 is provided between the condenser 8 and the residual gas combustion device 10 . As a result, the unreacted residual gas G5 discharged from the condenser 8 is supplied to the residual gas combustion device 10 via the path L14.

The refining device 9 is a device that performs a refining step S9 of refining methanol by refining the condensate and separating water and impurities. The condensate obtained from the condenser 8 is obtained as a liquid mixture containing the products methanol and water. The method of extracting methanol from the mixture in the refining device 9 is not particularly limited, but for example, water and impurities may be removed by dehydration and purification using a known method to obtain methanol. Examples of dehydration and purification methods include distillation and membrane separation.

The residual gas combustion device 10 is a device that burns the unreacted residual gas G5 and performs a residual gas combustion process to obtain thermal energy. Note that the residual gas combustion process is not shown in the flowchart of FIG. As the residual gas combustion device 10, a known device such as a direct combustion device or a catalytic combustion device can be used. In addition, the waste-derived gas G1 from which impurities have been removed by the gas cleaning device 2 is supplied to the residual gas combustion device 10 via the combustion gas bypass route (route L18 shown in FIG. 2) to generate additional thermal energy. You may get The thermal energy obtained in the residual gas combustion device 10 can be used as a heat source for the gas component adjustment step S3 (path L17 shown in FIG. 2). The residual gas burned in the residual gas combustion device 10 is discharged as exhaust gas through the path L19.

Further, a route for resupplying the unreacted residual gas G5 may be connected to the route L14. For example, path L15 can be connected to path L7 to join unreacted residual gas G5 to secondary adjustment gas G3. The path L<b>16 is connected to the gas component adjusting device 3 and can supply the unreacted residual gas G<b>5 to the gas component adjusting device 3 . As a result, unreacted carbon oxide and/or hydrogen in the conversion step S7 in the reactor 7 can be recovered as the unreacted residual gas G5 and reused.

(Method for producing methanol)
The method for producing methanol according to Embodiment 1 is executed, for example, according to the flowchart shown in FIG. In addition, the flowchart shown in FIG. 1 is an example, and is not limited to this. Each step in the method for producing methanol according to Embodiment 1 will be described in detail.

(Gas acquisition step S1)
The gas obtaining step S1 is a step of obtaining a gas containing carbon oxide and hydrogen from waste. When waste containing unsaturated hydrocarbon components such as plastic waste is used as the waste, in the gas acquisition device 1, the reaction between the hydrocarbon and water vapor or oxygen causes, for example, the following formulas (1) to ( 4) is assumed to occur.

_CnH2n + _nH2O →nCO+ _2nH2 (1)
_CnH2n + _2nH2O → _nCO2 + _3nH2 (2)
_CnH2n + _0.5nO2 →nCO+ _nH2 (3)
_CnH2n + _nO2 → _nCO2 + _nH2 (4)
In the above formulas (1) and (3), carbon monoxide is produced together with hydrogen. In the method for producing methanol of the present invention, the carbon monoxide and water are used as raw materials, ) may undergo a step of obtaining carbon dioxide and hydrogen. Alternatively, the carbon monoxide and oxygen may be used as raw materials, and the reaction of the following formula (6) may be performed to obtain thermal energy and carbon dioxide required for the gasification reaction (gas acquisition reaction).

CO+ _H2O → _CO2 + _H2 (5)
CO+ _0.5O2 → _CO2 (6)
In the reactions of formulas (1) to (6), 1 to 3 moles of hydrogen are obtained per mole of carbon atoms.

On the other hand, when waste containing naturally occurring organic matter is used as the waste, for example, the reaction represented by the following formula (7) and/or the reaction represented by the following formula (8) occurs in the gas acquisition device 1. thought to occur.

( _C6H12O6 ) _{n →} 6nCO+ _6nH2 (7)
( _C6H12O6 )n _{+ 6nH2O} → _{6nCO2 + 12nH2} (8)
In the above formula (7), carbon monoxide is generated together with hydrogen, but carbon monoxide and water may be used as raw materials and carbon dioxide and hydrogen may be obtained by the reaction of the above formula (5). . In the above formulas (7) to (8), 1 to 2 moles of hydrogen are obtained per mole of carbon atoms.

In the reaction to obtain carbon monoxide and hydrogen from organic matter as described above, a reaction at a higher temperature may be required compared to the reaction to obtain carbon dioxide and hydrogen, and in view of the energy cost related to temperature rise Also, it is expected that the method of obtaining carbon dioxide and hydrogen may be more advantageous.

(Gas cleaning step S2)
The gas cleaning step S2 is a step of cleaning the gas by removing impurities from the waste-derived gas G1. The waste-derived gas G1 may contain solids such as soot and fly ash that poison the catalyst as impurities. In addition, reaction-inhibiting components such as sulfur, chlorine, and nitrogen may be included as other impurities. In such a case, it is preferable to wash the waste-derived gas G1 in the gas washing step S2 before supplying it to the reactor 7 in the latter stage. The gas cleaning step S2 can, for example, reduce the concentrations of chlorides and sulfides in the waste-derived gas G1. As a result, the concentrations of chlorides and sulfides in source gas G4 supplied to reactor 7 can each be reduced to 100 ppb or less. The gas cleaning step S2 is usually performed according to the solid content or reaction-inhibiting components contained in the waste-derived gas G1, and can be performed by a known cleaning method.

By cleaning the gas in the gas cleaning step S2 so that the concentrations of chlorides and sulfides in the raw material gas G4 supplied to the reactor 7 are each 100 ppb or less, the deterioration rate of the catalyst used in the conversion step S7 is reduced. and extend the life of the catalyst.

(Gas component adjustment step S3, _CO2 separation step S4)
The gas component adjustment step S3 is a step of adjusting the composition of the waste-derived gas G1 to obtain the primary adjustment gas G2. The CO ₂ separation step S4 is a step of removing at least part of carbon dioxide (CO ₂ ) from the primary adjusted gas G2 obtained through the gas component adjustment step S3 to obtain a secondary adjusted gas G3. Through the gas component adjustment step S3 and the CO ₂ separation step S4, the waste-derived gas G1 can be adjusted to have a composition suitable for methanol synthesis.

The hydrogen required to produce methanol is 2 moles per mole of carbon monoxide (CO) and 3 moles per mole of carbon dioxide (CO ₂ ). Therefore, the volume fractions of hydrogen, carbon monoxide, and carbon dioxide in the source gas G4 supplied to the reactor 7 are ideally adjusted so that the index SN shown in the following formula (9) is 2. is. In the following formula (9), yH ₂ , yCO ₂ and yCO are the volume fractions of hydrogen, carbon dioxide and carbon monoxide in the source gas supplied to the reactor 7, respectively.

SN=(yH ₂ −yCO ₂ )/(yCO+yCO ₂ ) (9)
On the other hand, in general, when high-energy waste such as polyolefin is used as the waste, in order to carry out gasification without inputting thermal energy from the outside, oxidation of carbon monoxide shown in the above formula (6) It may be necessary to secure heat energy for the reaction. Therefore, the index SN shown in the above formula (9) becomes about 1 by increasing the ratio of carbon dioxide.

In the method for producing methanol of the present invention, when the waste-derived gas G1 obtained in the gas acquisition step S1 contains hydrogen, carbon dioxide and carbon monoxide, carbon dioxide is preferably 0.1 to 20 vol%, more preferably It is desirable to adjust the concentration to 1 to 10 vol % and supply it to the reactor 7 . Therefore, when the value of the index SN is low, it is preferable to adjust the SN value in advance before supplying the waste-derived gas G1 to the reactor 7 as the source gas G4. The value of the index SN is preferably 1 or more and 10 or less, more preferably 1.5 or more and 3 or less.

The gas component adjustment step S3 includes (i) a partial oxidation reaction of hydrocarbons contained in the waste-derived gas G1, (ii) a steam reforming reaction of hydrocarbons contained in the waste-derived gas G1, and (iii) waste-derived It may be carried out by carrying out at least one of: an aqueous shift reaction of carbon dioxide contained in the gas G1; and (iv) a method of adding hydrogen to the waste-derived gas G1. As a result, the volume ratio of hydrogen to carbon monoxide (H ₂ /CO) in the primary adjustment gas G2 obtained through the gas component adjustment step S3 can be adjusted to 1.5 or more and 4.0 or less. By subjecting the primary regulated gas G2 having an H ₂ /CO ratio of 1.5 to 4.0 to the CO ₂ separation step S4, the index SN of the secondary regulated gas G3 after carbon dioxide separation is reduced to 1.5 to 3 You can adjust below.

In the gas component adjustment step S3, for example, the hydrocarbons contained in the waste-derived gas G1 are reformed into carbon monoxide and hydrogen by partial oxidation reaction and/or steam reforming reaction, and then the water gas shift reaction is performed. good too. Thereby, _H2 /CO can be more easily adjusted to 1.5 or more and 4.0 or less.

Alternatively, in the gas component adjustment step S3, the hydrocarbons contained in the waste-derived gas G1 are reformed into carbon monoxide and hydrogen by partial oxidation reaction and/or steam reforming reaction, and then hydrogen (hydrogen gas) is added. You can (add). Thereby, _H2 /CO can be more easily adjusted to 1.5 or more and 4.0 or less. As a method for obtaining the hydrogen, known techniques such as reforming and cracking of fossil fuels, electrolysis of water, and splitting of water using a photocatalyst can be used.

In the CO ₂ separation step S4, for example, carbon dioxide, which is an acid gas, can be separated from the primary regulating gas G2 by treating the primary regulating gas G2 by a chemical absorption method using an amine solution. This makes it possible to obtain the secondary adjustment gas G3 in which the carbon dioxide concentration is adjusted to 0.1 to 20 vol %, preferably 1 to 10 vol %. Alternatively, in the CO ₂ separation step S4, carbon dioxide, which has the highest boiling point among hydrogen, carbon monoxide, and carbon dioxide, may be separated by treating the primary adjustment gas G2 with a cryogenic separation method. Alternatively, carbon dioxide may be separated by a membrane separation method using a separation membrane that selectively blocks carbon dioxide, or more preferably a separation membrane that selectively permeates carbon dioxide. Carbon dioxide separated in the CO ₂ separation step S4 may be used for another purpose.

By adjusting the gas components in the gas component adjustment step S3 and the _CO2 separation step S4, the composition of the raw material gas G4 is adjusted so as to have a composition suitable for the methanol conversion reaction (synthesis reaction) in the subsequent conversion step S7. be able to. Thereby, the conversion rate to methanol in the conversion step S7 can be improved.

(Compression step S5)
The pressure of the source gas G4 supplied to the reactor 7 is preferably a pressure suitable for methanol synthesis. In the compression step S5, the secondary adjustment gas G3 obtained through the CO ₂ separation step S4 is pressurized by the compressor 5 to a pressure suitable for methanol synthesis. The energy required for compressing the gas increases with the amount of gas supplied to the compressor 5 . Therefore, it is desirable to compress the gas after removing carbon dioxide by the CO ₂ separation step S4. The pressure of the secondary conditioning gas G3 after compression may be 0.2-10 MPaG, more preferably 2-6 MPaG. Through the compression step S5, the pressure of the source gas G4 supplied to the reactor 7 becomes 0.2 to 10 MPaG, preferably 2 to 6 MPaG, thereby improving the efficiency of methanol synthesis.

(Moisture removal step S6)
Moisture contained in the raw material gas G4 supplied to the reactor 7 hinders the reaction and lowers the reaction activity of the catalyst, so it is desirable to reduce it before the conversion step S7. As a method for removing water in the water removal step S6, for example, a method of cooling the compressed secondary adjustment gas G3 with a cooler to a temperature below the dew point of water to liquefy the vapor and then separating it with a gas-liquid separator is available. mentioned. The moisture removal step S6 can reduce the moisture content in the source gas G4 supplied to the reactor 7 to 5 vol% or less, preferably 2.5 vol% or less. As a result, the reaction efficiency in the conversion step S7 can be improved, and the life of the catalyst can be extended. is more preferred.

(Conversion step S7)
The conversion step S7 is a step of contacting at least part of the gas obtained from the waste with a catalyst and converting it into methanol in the gas phase.

Here, the catalyst used in the conversion step S7 will be explained. When methanol is obtained by the reaction of carbon dioxide and hydrogen, water is by-produced as represented by the following formula (10). On the other hand, when methanol is obtained by the reaction of carbon monoxide and hydrogen, water is not by-produced as represented by the following formula (11).

_CO2 + _3H2- > _CH3OH + _H2O (49.4 kJ/mol (exothermic reaction)) (10)
CO+2H ₂ →CH ₃ OH (90.4 kJ/mol (exothermic reaction)) (11)
The by-produced water may lower the reaction activity of the catalyst and lower the productivity of methanol. Therefore, it is preferable to use a catalyst that is less susceptible to water in the method for producing methanol of the present invention.

Therefore, in the present embodiment, it is preferable to use a catalyst whose activity is less likely to be lowered by water, such as a copper-based catalyst. As the catalyst, for example, a catalyst containing copper, zinc, aluminum and silicon as essential components and optionally containing zirconium, palladium and gallium is used. In general, a catalyst used for obtaining methanol by reacting carbon dioxide and hydrogen tends to be able to obtain methanol even when carbon monoxide and hydrogen are used as raw materials. Therefore, a catalyst containing a component such as copper exhibits activity in both the reaction between carbon dioxide and hydrogen and the reaction between carbon monoxide and hydrogen, and also exhibits durability against by-product water. , can be suitably used in the method for producing methanol of the present embodiment.

When using a catalyst containing copper as a catalyst, the particle size is not particularly limited. you can When the particle size of the catalyst is within the above range, it is not only easy to handle the catalyst, but also suitable in terms of strength of the catalyst. preferred. The method for producing the catalyst having the above particle size is not particularly limited, and known methods can be used. A tableting method is preferably used.

The reaction temperature in the catalyst layer may be, for example, about 180° C. or higher and 260° C. or lower, preferably 220° C. or higher and 240° C. or lower.

Note that the conversion step S7 in the reactor 7 may be carried out in the presence of a so-called inert gas that does not participate in the conversion reaction or lowering the activity of the catalyst.

(Cooling condensation step S8)
In the cooling condensation step S8, the condenser 8 is used to cool the gas discharged from the reactor 7 and separate it into an unreacted residual gas G5 and a condensate containing methanol and water.

(Purification step S9)
In the purification step S9, methanol is purified by purifying the condensate obtained in the cooling condensation step S8 and separating water and impurities.

(Residual gas combustion process)
In the residual gas combustion step, thermal energy is obtained by burning at least part of the waste-derived gas G1 and/or the unreacted residual gas G5 discharged from the condenser 8 . The heat obtained by the residual gas combustion step can be used as at least part of the heat source for performing the gas component adjustment step S3.

(summary)
A production method according to an aspect of the present invention is a method for producing methanol from a waste-derived gas G1 obtained by gasifying waste. A gas component adjustment step S3 in which the composition of the waste-derived gas G1 is adjusted to form a primary regulated gas G2, and at least a portion of carbon dioxide is selectively separated from the primary regulated gas G2 to form a secondary regulated gas G3. A _CO2 separation step S4 and a conversion step S7 of converting at least a portion of the secondary conditioning gas G3 to methanol as feed gas G4. The volume ratio of hydrogen to carbon monoxide in the primary adjustment gas G2 is 1.5 or more and 4.0 or less, and the content of _CO2 in the secondary adjustment gas G3 is 1 vol% or more and 10 vol% or less.

With the above configuration, methanol can be more efficiently produced from waste, and effective utilization of waste can be achieved. It also contributes to the reduction of carbon dioxide derived from fossil fuels associated with conventional methanol production. This will contribute to the achievement of the Sustainable Development Goals (SDGs).

Further, the production method according to one aspect of the present invention may further include a gas cleaning step S2 for removing impurities, and the concentrations of chlorides and sulfides in source gas G4 may each be 100 ppb or less.

With the above configuration, the life of the catalyst in the conversion step S7 can be extended.

In addition, the production method according to one aspect of the present invention further includes a water removal step S6 for reducing water content prior to the conversion step S7, and the water content in the source gas G4 is 2.5 vol% or less. may

With the above configuration, the efficiency of methanol synthesis in the conversion step S7 can be improved, and the life of the catalyst in the reactor 7 can be extended.

In addition, the production method according to one aspect of the present invention further includes a compression step of compressing the secondary adjustment gas G3 before the conversion step S7, and the pressure of the raw material gas G4 is 2 MPaG or more and 6 MPaG or less. good.

With the above configuration, the efficiency of methanol synthesis in the conversion step S7 can be improved.

In addition, the production method according to one aspect of the present invention burns the waste-derived gas G1 and/or the unreacted residual gas G5 in the conversion step S7 as at least part of the heat source for performing the gas component adjustment step S3. The resulting heat may also be used.

With the above configuration, energy consumption in methanol production can be reduced.

In the production method according to one aspect of the present invention, at least one of partial oxidation reaction, steam reforming reaction, water gas shift reaction, and hydrogenation may be performed in the gas component adjustment step S3.

With the above configuration, the composition of the source gas G4 can be made suitable for methanol synthesis, and the efficiency of methanol synthesis can be improved.

Moreover, in the production method according to one aspect of the present invention, the water gas shift reaction may be performed after the partial oxidation reaction and/or the steam reforming reaction.

With the above configuration, the composition of the source gas G4 can more easily be made suitable for methanol synthesis.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

S1 Gas acquisition step S2 Gas cleaning step S3 Gas component adjustment step S4 _CO2 separation step S5 Compression step S6 Moisture removal step S7 Conversion step S8 ... cooling condensation step S9 ... purification step 1 ... gas acquisition device 2 ... gas cleaning device 3 ... gas component adjustment device 4 ... CO ₂ separation device 5 ... compressor 6. Moisture removal device 7 Reactor 8 Condenser 9 Refining device 10 Residual gas combustion device 100 Manufacturing device

Claims (7)

A method for producing methanol from a waste-derived gas obtained by gasifying waste,
A gas component adjustment step of adjusting the composition of the waste-derived gas and using it as a primary adjustment gas;
a _CO2 separation step for selectively separating at least a portion of carbon dioxide ( _CO2 ) from the primary regulated gas into a secondary regulated gas;
a converting step of converting at least a portion of the secondary conditioning gas into methanol as a feed gas;
The volume ratio of hydrogen (H ₂ ) to carbon monoxide (CO) in the primary adjustment gas is 1.5 or more and 4.0 or less,
The production method, wherein the content of _CO2 in the secondary adjustment gas is 1 vol% or more and 10 vol% or less. further comprising a gas scrubbing step to remove impurities prior to the converting step;
2. The production method according to claim 1, wherein the concentrations of chlorides and sulfides in the source gas are each 100 ppb or less. further comprising a moisture removal step to reduce moisture prior to the conversion step;
3. The manufacturing method according to claim 1, wherein the water content in said raw material gas is 2.5 vol % or less. further comprising a compressing step of compressing the secondary conditioning gas prior to the converting step;
The manufacturing method according to any one of claims 1 to 3, wherein the pressure of the raw material gas is 2 MPaG or more and 6 MPaG or less. Any one of claims 1 to 4, wherein heat generated by burning the waste-derived gas and/or the unreacted residual gas in the conversion step is used as at least part of the heat source for performing the gas component adjustment step. 1. The manufacturing method according to 1. 6. The production method according to any one of claims 1 to 5, wherein at least one of partial oxidation reaction, steam reforming reaction, water gas shift reaction and hydrogenation is carried out in the gas component adjustment step. 7. The production method according to claim 6, wherein in said gas component adjusting step, a water gas shift reaction is carried out after a partial oxidation reaction and/or a steam reforming reaction.

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