WO2012017893A1

WO2012017893A1 - Waste processing system

Info

Publication number: WO2012017893A1
Application number: PCT/JP2011/067104
Authority: WO
Inventors: 佐伯　卓哉; 伊藤　潔
Original assignee: 三井化学株式会社
Priority date: 2010-08-02
Filing date: 2011-07-27
Publication date: 2012-02-09

Abstract

The purpose of the present invention is to provide a system for converting carbon dioxide to methanol which limits the burden placed on the global environment as much as possible. This waste processing system is characterised by including: a gasification process for obtaining a hydrogen and carbon dioxide-containing gas and residue from waste; and a methanol production process for synthesising methanol from part or all of the hydrogen obtained in the gasification process. This waste processing system preferably includes waste conveyance and collection processes using a conveyance vehicle having methanol as a fuel.

Description

Waste treatment system

The present invention relates to a waste processing system for processing methanol to produce methanol.

In recent years, carbon dioxide fixation methods have attracted attention from the viewpoint of global environmental issues such as global warming countermeasures. Carbon dioxide assimilation by photosynthesis is a well-known immobilization method of carbon dioxide, and other methods using light energy are also known, but light energy utilization efficiency is generally low, and at present only light energy is used. Therefore, it is difficult to fundamentally solve the current global environmental problems.

Another aspect of global environmental problems is the problem of waste. Waste that can be incinerated is often incinerated, but this involves the emission of carbon dioxide and heat, which goes against global warming prevention.
There is an example of generating power using combustion of waste, but electricity is basically unstorable, so advanced control is necessary, and initial capital investment and running costs may become excessive. Further, for example, when waste containing a lot of water such as household waste is used for combustion as it is, energy is lost due to evaporation of water and the like, resulting in a decrease in power generation efficiency. For this reason, such waste often undergoes a process of once drying before combustion, which also involves problems of energy loss and complicated processes.

In order to effectively use waste, a method for converting waste into hydrogen, which is a high-energy substance, or methanol or dimethyl ether, which is one of the most basic organic substances, is disclosed in JP-A-2003-171675 (Patent Document 1). ), Japanese Patent Application Laid-Open No. 2005-146056 (Patent Document 2), Japanese Patent Application Laid-Open No. 2006-205135 (Patent Document 3), and the like. These documents describe the conversion of waste to gas and steam reforming to hydrogen and carbon monoxide. Furthermore, for the synthesis of methanol, a method using carbon monoxide and hydrogen as raw materials is disclosed, and a mode in which carbon dioxide is used not as a reaction raw material but as a fluidizing gas is disclosed.

As a method for producing methanol, a number of methods using carbon monoxide and hydrogen which may contain carbon dioxide as raw materials are disclosed. On the other hand, although a method for producing methanol from carbon dioxide and hydrogen is disclosed in Japanese Patent Application Laid-Open No. 10-309466 (Patent Document 4) and the like, there is no description regarding a hydrogen source.

Hydrogen is industrially produced by steam reforming of natural gas and is actually derived from general fossil fuels.

JP 2003-171675 A JP 2005-146056 A JP 2006-205135 A Japanese Patent Laid-Open No. 10-309466

As described above, although a method for converting carbon dioxide to an organic compound has been reported, a method for converting carbon dioxide to an organic compound that is effective as a method for fixing carbon dioxide from the viewpoint of global environmental problems has not been reported. is the current situation. Therefore, an object of the present invention is to provide a system that suppresses the burden on the global environment as much as possible and converts carbon dioxide into methanol, which is a useful organic compound. It is another object of the present invention to provide a system that effectively uses it.

In view of such a situation, the present inventors examined an effective utilization method of carbon dioxide using waste that is usually incinerated or landfilled.

In view of the fact that water in waste containing much water such as household waste (hereinafter also referred to as low-calorie waste) can be used for steam reforming, waste gasification, steam reforming, A method for obtaining hydrogen and carbon dioxide or carbon monoxide is effective. However, since the moisture in the waste is not constant, the gas obtained by gasification may contain a considerable amount of moisture.

Generally, it is known that a catalyst capable of producing methanol or dimethyl ether from carbon monoxide and hydrogen is reduced in activity by water. For this reason, it is thought that the process which removes the water | moisture content in the carbon monoxide which is a raw material and hydrogen, and the process of managing a water content are considered necessary.

When producing methanol or dimethyl ether from carbon dioxide and hydrogen, water is generated. For this reason, it is presumed that a catalyst exhibiting excellent activity in the above reaction is not easily affected by water and can produce methanol and dimethyl ether without reducing the reaction activity even when the gas contains water. The

On the other hand, high-calorie waste such as plastic waste mainly has a saturated hydrocarbon structure, so when gasification, steam reforming, or methanol production is performed using this, excess hydrogen is present. It is thought that it may occur. Therefore, if this hydrogen is used in the reaction for converting carbon dioxide to methanol, it is considered that waste reduction and effective utilization of carbon dioxide can be simultaneously performed.

If methanol is produced using hydrogen and carbon dioxide obtained by gasification and steam reforming of waste as main raw materials, and part or all of the methanol is used as fuel for transportation vehicles such as waste collection trucks, CO2 A cycle of carbon utilization can be formed. In addition, methanol is considered to be useful as an energy source for fuel cells, which are considered to have high power generation efficiency. From this point of view, the above method is compared to conventional methods such as generating electricity by directly burning waste The present invention was completed by considering that this is an effective method for immobilizing carbon dioxide.

That is, the waste treatment system of the present invention includes a gasification step for obtaining a gas containing hydrogen and carbon dioxide and a residue from waste, carbon dioxide, and part or all of the hydrogen obtained in the gasification step. And a methanol production step of synthesizing methanol from the above.

It is preferable that part or all of carbon dioxide used in the methanol production process is carbon dioxide obtained in the gasification process.

The gasification step is a step of obtaining a gas containing hydrogen, carbon dioxide and carbon monoxide and a residue from waste, and carbon dioxide per 100 mol% of the total of carbon dioxide and carbon monoxide obtained in the step Is preferably 30 mol% or more.

The methanol production step is a step of synthesizing methanol from carbon dioxide, carbon monoxide, and part or all of the hydrogen obtained in the gasification step, and carbon dioxide and carbon monoxide used in the step It is preferable that carbon dioxide is 30 mol% or more per 100 mol% in total.

It is preferable to further include a transporting and collecting step of waste using the transport vehicle using methanol as a fuel.

It is preferable to further include an incineration step of the residue.

In the incineration step, it is preferable that an incineration heat recovery boiler is used, and further includes a power generation step using steam generated from the boiler.

It is preferable that the electric power obtained in the power generation process is used as a power source for at least one process selected from the gasification process and the methanol production process.

According to the present invention, carbon dioxide can be converted into methanol using waste materials that have been used in the past such as incineration and landfilling.

In addition, by using the methanol as fuel for a transportation vehicle used for transporting and collecting waste, a cycle for effectively using carbon dioxide can be constructed.

Considering the current situation of global warming, the value of this technology is great as a technology that suppresses the increase in carbon dioxide.

FIG. 1 is a flowchart showing an example of the waste treatment system of the present invention. FIG. 2 is a flowchart showing an example of the waste treatment system of the present invention.

The waste treatment system of the present invention comprises a gasification step for obtaining a gas containing hydrogen and carbon dioxide from a waste and a residue, carbon dioxide, and a part or all of hydrogen obtained in the gasification step. And a methanol production process for synthesizing methanol.

The waste used in the present invention is not particularly limited as long as it is a waste from which a gas containing hydrogen and carbon dioxide can be obtained by a gasification step described later, that is, a waste containing organic matter. Food waste such as wood; woody biomass such as waste wood, thinned wood, sawdust; paper waste; fiber waste; plastic waste; sewage sludge; human waste; livestock waste; waste oil; rubber tire; black liquor; . The waste may be a mixture of these.

From the viewpoint of energy efficiency, high-calorie waste consisting of general waste such as paper waste and industrial waste such as waste plastic and waste oil is preferable. However, in the waste treatment system of the present invention, food waste, woody biomass, etc. Even low-calorie wastes that often contain a large amount of water can be suitably used, and are also useful from the viewpoint of sustainable chemistry.

In the gasification process described later, a gas containing hydrogen and carbon dioxide is obtained from waste.

The main component of the high-calorie waste is plastic, and contains a large amount of polyolefins, typically polyethylene (Polyethylene (C ₂ H ₄ )) and polypropylene (Polypropylene (C ₃ H ₆ )). It is expected that Such as polyethylene and polypropylene, it believed that has it been known to use hydrogen for molecular weight control at the time of manufacture, in most cases, the saturated hydrocarbon structure (composition can be represented by C _n C _{2n + 2)} It is done. Therefore, it is considered that the high-calorie waste includes those having a large amount of saturated hydrocarbon structure.

In this saturated hydrocarbon gasification step, for example, the reaction represented by the following (formula 1) and the reaction represented by the following (formula 2) are considered to occur.

C _n H _{2n + 2} + nH ₂ O → nCO + (2n + 1) H ₂ (Formula 1)
C _n H _{2n + 2} + 2nH ₂ O → nCO ₂ + (3n + 1) H ₂ (Formula 2)
In (Formula 1), carbon monoxide is generated together with hydrogen. Carbon dioxide and hydrogen may be obtained by the reaction of the following (Formula 3) using the carbon monoxide and water as raw materials.

CO + H ₂ O → CO ₂ + H ₂ (Formula 3)
In (Formula 1), 2 moles or more of hydrogen are obtained per mole of carbon atoms, and in (Formula 2), 3 moles or more of hydrogen are obtained per mole of carbon atoms, following (Formula 1). When the reaction of (Formula 3) occurs, 3 moles or more of hydrogen per mole of carbon atoms is obtained in total (Formula 1 and Formula 3).

It is expected that the reaction of Formula 2 is more advantageous for completely decomposing the saturated hydrocarbon as described above to obtain hydrogen. At this time, it is expected that the use of water at 2 mol times or more with respect to carbon is advantageous for completing the decomposition reaction.

As will be described later, the catalyst used in the present invention for producing methanol from carbon dioxide and hydrogen tends to be hardly affected by water. For this reason, when excess water is used to efficiently obtain hydrogen from high-calorie waste, it is expected that the process of removing water from the obtained hydrogen and carbon dioxide will have a small effect on the reaction to obtain methanol. Is done.

On the other hand, the low-calorie waste is considered to contain mainly organic substances of natural origin (biomass). In the gasification step, for example, the reaction represented by the following (Formula 4) and the reaction represented by the following (Formula 5) Is thought to occur.

(C ₆ H ₁₂ O ₆ ) _n → ₆ nCO + ₆ nH ₂ (Formula 4)
_{_{_{(C 6 H 12 O 6)}}} n + 6nH 2 O → 6nCO 2 + 12nH 2 ( Equation 5)
In the above (Formula 4), carbon monoxide is generated together with hydrogen. However, carbon dioxide and hydrogen may be obtained by the reaction of the above (Formula 3) using the carbon monoxide and water as raw materials.

In (Formula 4), 1 mole of hydrogen is obtained per mole of carbon atoms, and in (Formula 5), 2 moles of hydrogen is obtained per mole of carbon atoms. Following (Formula 4), When the reaction of (Formula 3) occurs, 2 moles of hydrogen per mole of carbon atoms is obtained in total (Formula 4 and Formula 3).

It is expected that the reaction of Formula 5 will be advantageous when hydrogen is obtained by completely decomposing the natural organic material. At this time, it is expected that the use of equimolar water or more with respect to carbon is advantageous in completing the decomposition reaction.

As will be described later, the catalyst used in the present invention for producing methanol from carbon dioxide and hydrogen tends to be hardly affected by water. For this reason, when excess water is used to efficiently obtain hydrogen from low-calorie waste, it is expected that the process of removing water from the obtained hydrogen and carbon dioxide will have a small effect on the reaction to obtain methanol. Is done.

Furthermore, it is also attractive in the present invention that hydrogen obtained from waste containing natural organic substances is not derived from fossil fuels.

The reaction for obtaining carbon monoxide and hydrogen from the organic matter as described above may require a higher temperature than the reaction for obtaining carbon dioxide and hydrogen. It is expected that the method of obtaining carbon and hydrogen is more advantageous.

Since hydrogen required for the production of methanol is 2 mol per mol of carbon monoxide (CO) and 3 mol per mol of carbon dioxide (CO ₂ ), high-calorie waste such as polyolefin was used as waste. In some cases, even if all of the carbon monoxide of (Formula 1) and the carbon dioxide of (Formula 2) or (Formula 3) are used for the production of methanol, hydrogen is surplus.

Recently, it is known that polyethylene and polypropylene alone, which are representative polyolefins and the five largest general-purpose resins, have a production volume exceeding 100 million tons per year. In view of the enormous amount of waste that is expected in the future, high-calorie waste such as polyolefin is expected to become a considerable amount of hydrogen supply source.

In the methanol production process, carbon dioxide and hydrogen are used. As the hydrogen used in the methanol production process, part or all of the hydrogen obtained in the gasification process is used. On the other hand, as the carbon dioxide used in the methanol production process, carbon dioxide obtained in the gasification process may be used, and other carbon dioxide, for example, carbon dioxide obtained when the residue is incinerated, fossil fuel Carbon dioxide or the like obtained when the gas is burned for power generation may be used. As carbon dioxide, carbon dioxide obtained by various methods (processes) may be used in combination.

The waste treatment system of the present invention usually comprises a gasification step in which waste collected by a transport vehicle such as a garbage truck is gasified by a known method to obtain a gas containing hydrogen and a residue, and carbon dioxide. And a methanol production step of synthesizing methanol from part or all of the hydrogen obtained in the gasification step.

The waste treatment system of the present invention includes a methanol production step in which methanol is obtained by reacting carbon dioxide and hydrogen, preferably in the presence of a copper-based catalyst. Conventional catalysts employed for obtaining methanol from carbon monoxide and hydrogen generally tend to be reduced in reaction activity by water. On the other hand, when methanol is obtained by the reaction of carbon dioxide and hydrogen, water is by-produced as represented by the following (formula 6). For this reason, when the catalyst used when obtaining methanol from carbon monoxide and hydrogen is used in the methanol production process, the reaction activity of the catalyst is lowered, and the productivity of methanol is lowered. There is a risk of being connected.

CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O (Formula 6)
On the other hand, a catalyst that gives methanol from carbon dioxide and hydrogen generally tends to give methanol even when carbon monoxide and hydrogen are used as raw materials. For this reason, in the present invention, it is preferable to use a catalyst in which the decrease in activity due to water hardly occurs, for example, the copper-based catalyst described in Patent Document 4. In addition, as a catalyst, the catalyst which contains copper, zinc, aluminum, and silicon of the said patent document 4 as an essential component, and contains zirconium, palladium, and a gallium as an arbitrary component is mentioned as a preferable example. The catalyst containing a component such as copper described in Patent Document 4 is active in both the reaction between carbon dioxide and hydrogen and the reaction between carbon monoxide and hydrogen, and also exhibits durability in by-product water. For these reasons, it can be suitably used in the waste treatment system of the present invention.

The copper-containing catalyst preferably has a particle size of 1 to 20 mm, more preferably 2 to 20 mm, further preferably 3 to 20 mm, particularly preferably 3 to 15 mm, and 3 to 10 mm. Is particularly preferred. When the particle size of the catalyst containing copper is within the above range, not only is the catalyst easy to handle, but the catalyst layer is formed by, for example, increasing the strength of the catalyst or loading it on a fixed bed. It is suitable for. As a method for producing the catalyst having the above particle diameter, a known method can be used without limitation. A tableting method is preferably used.

In the methanol production process, it is preferable to react carbon dioxide and hydrogen in the presence of the catalyst. In this reaction step, unreacted carbon dioxide and hydrogen can be recovered and recycled to the reaction step. Further, this reaction generates water as shown in the above (Formula 6). For this reason, in the reaction, methanol is usually obtained as a liquid mixture with water. For example, methanol can be obtained by dehydrating the mixture by a known method. In an actual reaction, hydrogen does not need to be 3 mol per 1 mol of carbon dioxide, and may be a reaction in the presence of hydrogen exceeding 3 mol. Moreover, you may perform the said reaction in presence of what is called an inert gas which does not participate in said reaction and catalyst activity fall.

In the waste treatment system of the present invention, in the methanol production process, it is difficult for the activity to be reduced by water, and the activity is exhibited in both the reaction between carbon dioxide and hydrogen and the reaction between carbon monoxide and hydrogen to obtain methanol. In the gasification step, there is no need for highly controlled only in the reaction of (Formula 2) or (Formula 5), that is, only the reaction for obtaining hydrogen and carbon dioxide. The reaction may be performed under conditions in which the reaction of 1) or (Formula 4) and the reaction of (Formula 2) or (Formula 5) occur. Therefore, the waste treatment system of the present invention is expected to be a system that allows a wide range of operating conditions for the gasification step and is easy to commercialize.

Other processes may be provided in the waste treatment system of the present invention. Examples of other processes include a dimethyl ether (DME) synthesis process, a waste pretreatment process, a gasification gas purification process, an incineration exhaust gas purification process, and the like.

The DME synthesis step is a step of synthesizing DME by dehydration reaction of methanol obtained in the methanol production step. In this process, a DME synthesis apparatus is usually used, and in this apparatus, methanol heated to a temperature suitable for DME synthesis (240 to 320 ° C.) is filled with a catalyst for DME synthesis (for example, alumina system or the like). DME is synthesized by feeding to the reaction tower. The apparatus may be further connected to distillation for obtaining purified DME (product DME) by distilling the produced crude DME. An apparatus in which the methanol synthesizer and the DME synthesizer are integrated can also be used.

In the waste treatment system of the present invention, the gasification gas is obtained by treating the waste in the gasification step. Before supplying the waste to the gasification step, the waste pretreatment step Processing may be performed. The pretreatment process varies depending on the type of waste, and is not particularly limited. However, the separation process for separating the type of waste, the drying process performed according to the amount of water in the waste, the size of the waste, etc. The crushing process etc. performed according to are mentioned. A plurality of these steps may be performed.

As described above, the gasification gas and the residue are usually separately taken out from the outlet of the gasification furnace in which the gasification step has been performed. May be included. In addition, reaction impurities such as sulfur and nitrogen may be contained as other impurities. In such a case, the gasification gas is preferably purified by the gasification gas purification step before being used in the methanol production step. The gasification gas purification step is usually performed according to the solid content contained in the gasification gas and the reaction-inhibiting component, and is performed by a conventionally known method.

In addition, when the residue is burned, an incineration exhaust gas purification step may be performed before being released into the atmosphere, depending on the components contained in the incineration exhaust gas obtained by combustion. Although the incineration exhaust gas purification step is included in the incineration gas and varies depending on the components to be removed, the incineration exhaust gas purification step is performed by a conventionally known method as in the gasification gas purification step. Carbon dioxide in the combustion exhaust gas may be used in the methanol production process as described in Example 2 described later. In such a case, a carbon dioxide concentration separation process for separating carbon dioxide from the incineration exhaust gas is performed. This step is performed by a conventionally known method.

In the waste treatment system of the present invention, when the gasification gas obtained in the gasification step contains hydrogen, carbon dioxide, and carbon monoxide, the three components can be supplied to the methanol production step. However, some or all of carbon dioxide and carbon monoxide may be removed and used for other applications. For example, by treating the gasification gas by a chemical adsorption method using an amine solution, carbon dioxide that is an acidic gas can be removed, and a gas containing hydrogen and carbon monoxide can be obtained. Further, hydrogen can be separated by further processing a gas containing hydrogen and carbon monoxide by a PSA (Pressure Swing Adsorption) method which is a kind of physical adsorption method. In addition to the chemical adsorption method, carbon dioxide having the highest boiling point among the three components can be separated by treatment by a cryogenic separation method to obtain a gas containing hydrogen and carbon monoxide. it can. Moreover, you may isolate | separate by a membrane separation method. In addition, when carbon dioxide is removed by the chemical adsorption method, moisture derived from the chemical adsorption method may be mixed in the gas containing hydrogen and carbon monoxide obtained. Even in such a case, methanol can be suitably produced by using the above-described catalyst in which the activity is hardly reduced by water in the methanol production process.

In addition, when carbon monoxide is separated from the gasification gas, the liquid fuel can be obtained, for example, by supplying it to the liquid fuel production apparatus. Examples of the liquid fuel production apparatus include an FT (Fischer-Tropsch) production apparatus.

Also, a tank for storing the methanol, DME, or liquid fuel may be provided.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the steps and the like described in this embodiment are merely illustrative examples, and are not intended to limit the scope of the present invention unless otherwise specifically described.

The system according to the present embodiment uses a waste material to obtain a raw material such as hydrogen by a gasification process described later, and generates methanol by reacting carbon dioxide and hydrogen obtained in the gasification process. This is a waste treatment system. Preferably, the waste treatment system uses the methanol as a fuel for a transportation vehicle such as a waste collection vehicle to form a carbon dioxide utilization cycle. Further, the methanol may be used as a power source such as fuel for other transportation means. Examples of the transportation means include public transportation means such as a public bus. An example of this system is shown in FIGS.

[Example 1]
Example 1 which is a preferred embodiment of the present invention will be described with reference to FIG.

In the first embodiment, waste (10) collected by a transport vehicle such as a garbage truck is gasified (20) by a known method, and a gas (30) containing hydrogen and carbon dioxide and a residue (21) are collected. And a methanol production step (40) for synthesizing methanol from hydrogen obtained in the gasification step and carbon dioxide. The residue (21) is incinerated (22), and the generated heat is used for power generation (23).

Moreover, in FIG. 1, as a utilization mode of methanol, methanol (50) obtained in the methanol production process (40) is used as a waste collection vehicle (for example, combustible garbage collection vehicle) (60) or public transportation (public bus etc.). ) (70) The mode used as a transportation fuel is illustrated.

As the treatment apparatus for gasifying (20) the waste (10), a known material can be used without limitation. The waste treatment system of the present invention has a gasification furnace in which waste is supplied and gasification (20) is performed, and includes at least hydrogen and carbon dioxide, and carbon monoxide generated by gasification. It is preferable to provide a gas purification device into which a gas that may be discharged is introduced. In addition, although the gas obtained by gasification (20) should just contain hydrogen and a carbon dioxide, normally carbon monoxide is also contained. When the gas contains hydrogen, carbon dioxide, and carbon monoxide, the carbon dioxide is preferably 30 mol% or more, more preferably 50 mol% per 100 mol% of the total of carbon dioxide and carbon monoxide. As mentioned above, More preferably, it is 70 mol% or more.

The gasification furnace is an apparatus that generates gas containing at least hydrogen and carbon dioxide by heating waste to gasify. The structure of the gasification furnace is not particularly limited, but a fixed bed gasification furnace, a fluidized bed gasification furnace, a circulating fluidized bed gasification furnace, a rotary furnace, a moving bed gasification furnace, a spouted bed gasification furnace, an indirect heating gasification A spouted bed gasification furnace is particularly preferable. Also, depending on the contents of the waste, there are cases where the residue increases, but in such a case, a gasification melting furnace can be employed. As the gasification melting furnace, there are an updraft type, a downdraft type, a fluidized bed type and the like, but any type can be adopted as long as it meets the object of the present invention. If importance is attached to gasification and residue reduction, the downdraft type is preferred.

The gasification furnace may be supplied with a gasifying agent such as steam or oxygen for steam reforming reaction according to the amount of water contained in the waste. In the gasification step, a reaction occurs in a temperature range of 800 to 1100 ° C., and includes a gas (gasification gas) that contains at least hydrogen and carbon dioxide, and may contain carbon monoxide, and a residue such as tar and soot. , Fly ash and incombustible material are obtained. Further, a gasified gas mainly composed of carbon monoxide and hydrogen can be generated from a by-product hydrocarbon such as methane, ethane, and tar and unburned solid content such as soot by a reforming reaction.

The gasification gas and the residue are usually taken out separately from the outlet of the gasification furnace. The obtained gasification gas may contain solids such as soot and fly ash as impurities. In such a case, the aforementioned gasification gas purification step may be further performed.

The residue (21) can be gasified by a more powerful reforming method. However, in view of energy efficiency, the residue (21) is incinerated (22), and the generated heat is converted into steam generation means such as an incineration heat recovery boiler. It is preferable to convert the energy into the form of power generation using generated steam (23) or the like. The electric power obtained in this step can be sold to, for example, an electric power company. Moreover, it is also possible to use for the electric power (power) required for the above-mentioned gasification process (20) and the methanol production process (40) described later, which is necessary for the waste treatment system of the present invention.

Also, heat generated during incineration (22) or power generation (23) may be used in other processes. As the utilization of heat, for example, it is preferably used as a heat source for the above-described drying step, gasification step, methanol production step described later, and the like.

The gasification gas obtained in the gasification step contains at least hydrogen and carbon dioxide as described above, and may contain carbon monoxide. In the methanol production step (40), methanol is produced using the gasification gas. The methanol production step (40) is carried out in the presence of a methanol synthesis catalyst, and it is preferable to use a catalyst in which the aforementioned activity is hardly reduced by water, for example, the copper-based catalyst described in Patent Document 4.

The methanol production process is usually performed by supplying the gasification gas to a methanol synthesizer. The methanol synthesizer is an apparatus for producing methanol by raising the temperature to a normal methanol synthesis reaction pressure (for example, a pressure of 3 to 15 MPa) and a methanol synthesis temperature (for example, 180 to 500 ° C.). The methanol synthesizer is preferably provided with a distillation column. It is preferable to distill crude methanol in the distillation column to separate low-boiling components and paraffins, purify the crude methanol, and obtain purified methanol.

The carbon monoxide obtained in the above gasification step is usually supplied to the methanol production step (40) together with hydrogen and carbon dioxide, but part or all of the carbon monoxide is used as a raw material for other chemical reactions. Also good. In the case where the methanol production step (40) is a step of synthesizing methanol from carbon dioxide, carbon monoxide and hydrogen, per 100 mol% of carbon dioxide and carbon monoxide used in the step, It is preferable that carbon is 30 mol% or more, More preferably, it is 50 mol% or more, More preferably, it is 70 mol% or more.

Also. The carbon dioxide obtained in the gasification step is usually supplied to the methanol production step (40) together with hydrogen, but part or all of the carbon dioxide obtained in the gasification step is used for other applications. Also good. Other uses include compression and use as dry ice.

In the methanol production process (40), a tank for storing methanol may be provided. The methanol stored in the tank is transported to various places where methanol is used by transportation means such as a transportation vehicle. At this time, the methanol or liquid fuel can be used as a transportation fuel for the transportation means.

Methanol (50) obtained in the methanol production process (40) should be used as a transportation fuel for waste collection vehicles (combustible garbage collection vehicles) (60) and public transportation (public buses) (70) described later. You can also. Methanol can be used as a raw material for a wide variety of organic chemical reactions.

In addition, the waste (10) as a raw material of the waste treatment system is usually transported to a facility that performs the gasification step (20) by a transport vehicle such as a garbage truck, which is a methanol vehicle. A vehicle using methanol as an energy source, such as a methanol / gasoline mixed fuel vehicle, a methanol / light oil mixed fuel vehicle (for example, a diesel engine vehicle), or a methanol fuel cell vehicle, is preferred.

Further, it is preferable to use methanol obtained by the waste treatment system of the present invention as fuel for the garbage truck. Thus, by using methanol obtained by the waste treatment system of the present invention as a waste collecting means, a waste treatment cycle is formed. As a result, it is considered that the energy derived from fossil fuels such as thermal power generation and gasoline input to the waste treatment can be greatly reduced. Therefore, the waste treatment system of the present invention is considered to be a technology that greatly contributes to environmental problems such as global warming.

[Example 2]
Example 2 which is a preferred embodiment of the present invention will be described with reference to FIG.

In Example 2, the carbon dioxide (24) generated in the incineration (22) is supplied to the methanol production step (40) and reacted with the gas (30) containing hydrogen and carbon dioxide to obtain methanol (50). Except for this feature, the second embodiment is the same as the first embodiment.

In Example 2, since carbon dioxide (24) generated in incineration (22) is used as a raw material for methanol, it is preferable because the amount of carbon dioxide discharged into the atmosphere can be reduced.

Claims

A gasification step for obtaining a gas containing hydrogen and carbon dioxide and a residue from waste;
A waste treatment system comprising a methanol production step of synthesizing methanol from carbon dioxide and part or all of hydrogen obtained in the gasification step.
The waste treatment system according to claim 1, wherein a part or all of carbon dioxide used in the methanol production process is carbon dioxide obtained in the gasification process.
The gasification step is a step of obtaining a gas containing hydrogen, carbon dioxide and carbon monoxide, and a residue from waste,
The waste treatment system according to claim 1 or 2, wherein carbon dioxide is 30 mol% or more per 100 mol% of carbon dioxide and carbon monoxide obtained in the step.
The methanol production step is a step of synthesizing methanol from carbon dioxide, carbon monoxide, and part or all of the hydrogen obtained in the gasification step;
The waste treatment system according to any one of claims 1 to 3, wherein carbon dioxide is 30 mol% or more per 100 mol% of carbon dioxide and carbon monoxide used in the step.
The waste treatment system according to any one of claims 1 to 4, further comprising a step of transporting and collecting waste using a transport vehicle using methanol as a fuel.
The waste treatment system according to any one of claims 1 to 5, further comprising an incineration step of the residue.
The waste treatment system according to claim 6, further comprising a power generation step using an incineration heat recovery boiler in the incineration step and using water vapor generated from the boiler.
The waste treatment system according to claim 7, wherein the electric power obtained in the power generation step is used as a power source for at least one step selected from the gasification step and the methanol production step.