JP2007070408A - Method for treating supercritical water decomposition gas, and energy recovery system and organic compound production system each utilizing the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method capable of catching and utilizing in the system tars, high-boiling nondecomposed organic matter, ammonia, hydrogen chloride, etc. produced when water-rich organic matter is subjected to gasification treatment with supercritical water to obtain fuel gas for energy recovery and feedstock gas for dimethyl ether, etc. <P>SOLUTION: The method for treating supercritical water decomposition gas comprises the step of decomposing water-rich organic matter with supercritical water and obtaining the resultant gas generated, the step of absorbing substances comprising tars and other high-boiling oil-soluble organic matter in biomass-derived combustible oil to remove the substances, and the step of simultaneously separating and removing part of the water-soluble components in the above gas by condensing water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is achieved by a treatment method for decomposing and gasifying organic matter having a high water content, particularly food waste, food factory waste, sewage sludge, livestock manure, etc., and microalgiers such as algae in supercritical water. The present invention relates to a method for treating cracked gas produced by supercritical water gasification of organic substances, in which fuels such as carbon oxide, hydrogen, lower hydrocarbons, etc. and raw gas (purified gas) are produced. Supercritical water equipped with a critical water gasification process, a process for treating tar content and high-boiling oil-soluble organic matter in cracked gas, and a process for treating water-soluble gases such as ammonia, hydrogen chloride and carbon dioxide in cracked gas The present invention relates to a cracked gas processing method, an energy recovery system using the same, and an organic compound manufacturing system.

  Conventionally, organic substances having a high water content have been incinerated, and the residue has been disposed of in a final disposal site in a very simple manner. However, there is a need to review incineration from the viewpoint of shortage of final disposal sites, dioxin generation problems during incineration, hazardous heavy metal problems, and recent recycling and energy recovery use.

  On the other hand, it is obvious that energy using biomass including organic waste as a raw material is suitable energy as a countermeasure against global environmental problems, particularly global warming, since the biomass is carbon neutral. For this reason, biomass pyrolysis technology has been studied. However, relatively dry grass and trees (moisture content: 10 to 30%) can be gasified by a fixed bed, fluidized bed, spouted bed, etc., and liquefied by rapid thermal decomposition. Evaporation of water when handling 80-90% food waste (garbage), food factory waste (beer lees, bagasse, soybean lees, etc.), livestock manure and sewage sludge The loss due to latent heat is too great and the usual pyrolysis method is difficult. Therefore, at present, biological methods such as methane fermentation are used. However, the reaction is slow and there is a problem of residue, and its application is limited.

  In recent years, therefore, supercritical water gasification of biomass has attracted attention. Several methods for gasifying biomass containing organic waste having a high water content in supercritical water have been disclosed (Japanese Patent Publication No. 11-502891). However, in the treatment as described in the publication, a method of completely gasifying is aimed at, and a high temperature condition of 600 ° C. or higher is required. Moreover, it does not mention nitrogen contained in animal wastes and chlorine in general organic wastes, but mainly targets pure substances such as glucose. Moreover, it does not mention utilization of the obtained gas.

  However, as a practical matter, when recovering energy from biomass containing organic waste, what kind of cracked gas should be generated in relation to the problem of how to use the subsequent product gas? The problem remains. Furthermore, there is also a problem of how to treat ammonia produced from wastes rich in nitrogen such as livestock manure and hydrogen chloride produced from general waste.

In controlling the ratio of gas components, temperature control is the most effective means even in the presence of a catalyst, and addition of an oxidizing agent, a reductive entrainer, etc. is also conceivable. However, with these operations, tar and high-boiling point non-decomposed organic matter production, which is originally less than 1% in the supercritical water gasification treatment, is increased to several percent. The ammonia component varies depending on the nitrogen content of the raw material. A method is disclosed in which char and tar generated in pyrolysis gasification of organic matter are not adsorbed on fine particles but removed by supercritical water gasification (Japanese Patent Laid-Open Nos. 2004-131560 and 2004-2004). 298818). This method does not mention the use of the removed tar. Therefore, when these tars, high boiling point non-decomposed organic substances, ammonia, hydrogen chloride, or the like are generated, there is no quasi-zero emission type system that can efficiently remove them and effectively use them.
Japanese National Patent Publication No. 11-502891 JP 2004-131560 A JP 2004-298818 A

  Therefore, one of the objects of the present invention is to gasify an organic substance having a high water content with supercritical water and obtain a fuel gas for energy recovery and a raw material gas for dimethyl ether, etc. It is an object of the present invention to provide a treatment method capable of capturing high boiling point non-decomposed organic substances, ammonia, hydrogen chloride and the like and utilizing them in the system.

The present invention relates to the following 1. The object is achieved by providing the invention.
1. A step of taking out a gas generated by decomposing organic matter having a high water content with supercritical water in a supercritical water gasification treatment tank or the like, and a substance consisting of tar content in the gas and other high-boiling oil-soluble organic matter, A supercritical water splitting gas comprising a step of removing the substance by absorbing it in a flammable oil, and a step of separating and removing a part of water-soluble components in the gas by condensing water. Processing method.
Since this invention consists of said structure, a tar content, a high boiling point nondecomposition organic substance, ammonia, hydrogen chloride, etc. can be capture | acquired and these can be utilized in a system.
Here, the moisture content in the organic matter having a high moisture content is preferably 50% or more.

The present invention also provides the following 2. ~ 11. The present invention is preferably provided.
2. In the step of taking out the gas, it is possible to renew a material comprising a metal-supported or non-supported metal oxide and a carbon material having a catalytic function capable of capturing inorganic salts from the organic material having a high water content and relaxing the reaction conditions. 2. The method for treating a supercritical water cracking gas according to 1 above, which is present in a shape.

  According to this, the severe condition of 500 ° C. or more and 35 MPa or more, which is generally the supercritical water gasification condition, can be relaxed to about 400 ° C. and about 25 MPa by the action of the catalyst. It is possible to widen the design allowable range and to control the ratio of gas components to be generated to a component ratio advantageous for the next process. Furthermore, by making it exist in an updatable shape, it is possible to widen the control range, and it is possible to change the shape according to the properties of the fluid and to exhibit practicality. Furthermore, since it is possible to use an immobilized catalyst format, it is possible to prevent the catalyst from being mixed into the reaction solution and reduce the load of the purification process.

  In addition, the “updatable shape” is a reaction vessel wall surface, or a protrusion from the wall surface, including a catalyst mixture in a general semi-homogeneous system, and a shape of a permeable membrane. It means that it can be removed, changed, and updated via a doorway such as a valve.

3. 3. The method for treating a supercritical water cracking gas according to 1 or 2, wherein a step of removing a part of the water-soluble component is performed after the step of removing the tar and other high-boiling oil-soluble organic substances.
Since the water-soluble component generally has a lower boiling point than the oil-soluble component, it is preferable to provide the removal steps in this order because each can be removed with high efficiency and high purity.

4). The super-according to any one of 1 to 3 above, wherein the temperature when absorbing the tar and other high-boiling oil-soluble organic substances is 100 ° C to 250 ° C, and the pressure is 0.1 MPa to 3.9 MPa. Processing method of critical water cracking gas.
According to this, the vaporization of low molecular weight substances in tar is prevented, the separation of the tar content is promoted, the decomposition reaction of the biomass-derived combustible oil is suppressed, and the water is in a gaseous state so that it is retained in this step. It is preferable because it is advantageous in removing water-soluble components in the next step.

5. The biomass-derived combustible oil is selected from the group consisting of vegetable oil, animal oil, waste cooking oil, fatty acid ester type biodiesel oil, oil pyrolysis biodiesel oil, biomass chemical decomposition biodiesel oil and biomass pyrolysis biodiesel oil 5. The method for treating a supercritical water decomposition gas according to any one of 1 to 4 above, which is one kind or a mixture of two or more kinds.
According to this, since the use of combustible oil for absorption derived from a specific biomass, carbon dioxide is zero-counted even after subsequent combustion, leading to a reduction in the burden on the global environment. Since it is an oxygen fuel, it is preferable because various organic substances are easily dissolved.

6). The method for treating a supercritical water decomposition gas according to any one of 1 to 5, wherein the water-soluble component is one or a mixture of two or more selected from the group consisting of moisture, ammonia, hydrogen chloride, and carbon dioxide. .
This is preferable because moisture, ammonia, hydrogen chloride, carbon dioxide and the like can be efficiently captured.

7). In any one of the above 1 to 6, further comprising a step of burning the biomass-derived combustible oil that has absorbed the tar and other high-boiling oil-soluble organic substances in an incinerator or the like, and utilizing the combustion heat. The supercritical water decomposition gas treatment method as described.
According to this, since the tar content discarded as a by-product until now can be used efficiently as a heat source, it is preferable.

8). 8. The method for treating a supercritical water decomposition gas according to any one of 1 to 5 or 7, further comprising a step of separating an ammonia component as the water-soluble component and using the ammonia component as a component for exhaust gas treatment.
According to this, since the ammonia content discarded as a by-product until now can be used efficiently as an exhaust gas treating agent, it is preferable.

9. An energy recovery system using a purified gas obtained by the supercritical water cracking gas treatment method according to any one of 1 to 8 as a fuel gas.
This is preferable because energy in the system can be efficiently recovered and the entire system can be made self-sufficient.

10. 10. The energy recovery system according to 9, wherein the energy is energy of a gas turbine, a gas engine, a Stirling engine, or a fuel cell.
This is preferable because the obtained gas can be used directly without conversion.

11. The organic compound manufacturing system using the refined gas obtained by the processing method of the supercritical water cracking gas in any one of said 1-8 as raw material gas.
This makes it possible to efficiently produce lower organic compounds such as lower alcohols and ethers.

12 12. The organic compound production system according to 11 above, wherein the organic compound is methanol or dimethyl ether.
According to this, methanol or methyl ether can be produced efficiently.

  According to the present invention, tar content, high boiling point non-decomposed organic matter, ammonia, hydrogen chloride, and the like generated when gasifying a high moisture content organic substance with supercritical water to produce purified gas can be easily captured. The purified gas obtained can be used in various systems.

  Further, according to the present invention, there is no trouble in the system or energy recovery device due to the adhesion of tar, and the corrosion problem due to hydrogen chloride or the like is solved. Furthermore, since the ammonia content is removed and can be used thereafter, the conventional nitrogen content treatment problem is also passed. In addition, by using the removed tar as a combustion fuel, it is possible to simultaneously reduce the reprocessing energy of the tar and secure the heat source in the system. Furthermore, the use of biomass-derived combustible oil can reduce the total system carbon dioxide emissions to zero.

  In addition, according to the present invention, organic waste having a high moisture content, particularly food waste, food factory waste, sewage sludge, livestock manure, etc., and microalgiers such as algae, etc., and organic matter, particularly carbon dioxide Provided is an energy recovery method from organic matter that can be processed by a method that uses very little energy derived from isofossil fuel, and that the tar content and ammonia that are generated can be effectively used to recover energy from other combustible biogas. The

  According to a preferred embodiment of the present invention, there is provided a method for treating a cracked gas in supercritical water of an organic substance having a high water content, wherein the catalyst can trap inorganic salts and relax reaction conditions in a supercritical water slurry. A material consisting of a metal-supported metal oxide and carbonaceous material having both functions is present in a renewable form, and the biogas containing water is generated under the condition that the water is in a dry steam state and has a high boiling point derived from biomass. Absorb and remove tar by passing fuel oil, vegetable oil, biodiesel oil, etc., and then condense the gas to remove water and water soluble components such as carbon dioxide and ammonia. In addition, fuel gas mainly composed of hydrogen, carbon monoxide, methane, etc., that is, gas turbine, gas engine, Stirling engine, fuel cell, etc. Energy recovery fuel, it is possible to obtain the methanol or dimethyl ether (DME) feed efficiently.

FIG. 1 is a schematic process diagram of a method for treating an organic supercritical water decomposition gas having a high water content according to the present invention.
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIG. The high water content organic substance here refers to food waste, food factory waste, sewage sludge, livestock manure, etc., and microalgiers such as algae.

  First, the recovered high water content organic substance (101) is gasified and decomposed in supercritical water in the supercritical water gasification tank (1). Process temperature and pressure are subcritical water conditions (250 ° C. to 374 ° C., 4.0 MPa to 22.1 MPa) and supercritical water conditions (374 ° C. or higher, 22.1 MPa or higher). The condition is set according to the type of. When obtaining a gas component suitable for a hydrocarbon-dominated energy recovery system such as methane, the temperature may be about 400 ° C. and 25 MPa. However, when hydrogen is dominant, it is necessary to increase the temperature to 600 ° C. and 35 MPa. Moreover, these change also by the defense of an in-system oxidizing agent.

  Furthermore, for the purpose of controlling reaction conditions, a metal oxide such as alumina, titania, zirconia and activated carbon are fixed in a rod-like, cylindrical, piece-like, granular shape in the supercritical water gasification treatment tank (1) or It is floating. The method for providing these metal oxides and activated carbon is not particularly limited as long as it does not affect the fluidity of supercritical water, can be contacted with the supercritical water fluid, and can be desorbed. Furthermore, a metal having a gasification decomposition catalytic effect such as nickel may be supported on the surface of these carriers (metal oxide and activated carbon). Thus, since various conditions are fluctuate | varied, the quantity of a tar content and the high boiling point nondecomposition organic substance changes.

  Next, the cracked gas decomposed in the supercritical water gasification tank (1) is sent to the tar separation tank (2). Here, the cracked gas is preferably cooled, and the tar content and the high-boiling point non-decomposed organic matter in the cracked gas are absorbed by the biomass-derived combustible oil. The temperature and pressure at this time are preferably maintained in a dry steam state of water (temperature 100 ° C. to 250 ° C., pressure 0.1 MPa to 3.9 MPa, range). When this temperature is exceeded, low molecular weight substances in tar vaporize and are contained in the gas and cannot be separated. Moreover, the decomposition reaction of biomass origin combustible oil will also arise. Further, the temperature and pressure are preferably 125 ° C. to 200 ° C. and 0.2 MPa to 1.5 MPa depending on the relationship with the vapor pressure.

  Biomass-derived combustible oil is selected from the group consisting of vegetable oil, animal oil, waste cooking oil, fatty acid ester biodiesel oil, oil pyrolysis biodiesel oil, biomass chemical decomposition biodiesel oil, and biomass pyrolysis biodiesel oil One kind or a mixture of two or more kinds is preferred.

  The combustible oil (103) that has absorbed the tar component is sent to the exhaust heat boiler (4) continuously or discontinuously for combustion. The heat obtained here is used as a heat source for producing supercritical water.

On the other hand, the cracked gas from which the tar content has been removed is sent to water, NH ₃ , and CO ₂ removal tank (3). Here, moisture in the gas is condensed, and this water and previously introduced water are decomposed into cracked gas. Has a structure to pass through. As a result, ammonia, carbon dioxide, hydrogen chloride and the like, which are water-soluble components in the gas, are absorbed and separated. The temperature and pressure conditions in this case may be basically any conditions that allow water to be condensed, but preferably 50 to 100 ° C.

  Water (104) that has absorbed the water-soluble component is subjected to an alkali treatment to separate the ammonia component. The ammonia component is used as a denitration treatment agent for an exhaust gas treatment apparatus.

  On the other hand, the gas (102) from which the water-soluble component has been separated is sent to the energy recovery device (6) or the methanol / dimethyl ether production device (6) according to the purpose. The heat of the exhaust heat boiler (4) can also be used as a heat source for these devices.

  INDUSTRIAL APPLICABILITY The present invention can easily capture tars, high boiling point non-decomposed organic substances, ammonia, hydrogen chloride, and the like that are produced when gasifying an organic substance having a high water content with supercritical water to produce a purified gas. The present invention has industrial applicability as a supercritical water decomposition gas treatment method, an energy recovery system using the same, and an organic compound production system.

It is a general | schematic process drawing of the processing method of the supercritical water decomposition gas of the organic substance with a high moisture content based on this invention.

Claims (12)

Decomposing organic matter with a high water content with supercritical water and extracting the generated gas;
A step of removing the substance by absorbing the tar content in the gas and other high-boiling oil-soluble organic substances into the biomass-derived combustible oil;
A process for treating a supercritical water decomposition gas comprising: a step of simultaneously separating and removing a part of water-soluble components in the gas by condensing water.   In the step of taking out the gas, it is possible to renew a material comprising a metal-supported or non-supported metal oxide and a carbon material having a catalytic function capable of capturing inorganic salts from the organic material having a high water content and relaxing the reaction conditions. The supercritical water cracking gas treatment method according to claim 1, wherein the supercritical water decomposition gas is present in a shape.   The method for treating a supercritical water cracking gas according to claim 1 or 2, wherein a step of removing a part of the water-soluble component is performed after the step of removing the tar and other substances composed of high-boiling oil-soluble organic substances. .   The temperature at the time of absorbing the substance consisting of the tar content and other high-boiling oil-soluble organic substances is 100 ° C to 250 ° C, and the pressure is 0.1 MPa to 3.9 MPa. Supercritical water cracking gas treatment method.   The biomass-derived combustible oil is selected from the group consisting of vegetable oil, animal oil, waste cooking oil, fatty acid ester type biodiesel oil, oil pyrolysis biodiesel oil, biomass chemical decomposition biodiesel oil and biomass pyrolysis biodiesel oil The method for treating a supercritical water cracking gas according to any one of claims 1 to 4, which is one kind or a mixture of two or more kinds.   The supercritical water decomposition gas treatment according to any one of claims 1 to 5, wherein the water-soluble component is one or a mixture of two or more selected from the group consisting of moisture, ammonia, hydrogen chloride, and carbon dioxide. Method.   7. The method according to claim 1, further comprising a step of combusting biomass-derived combustible oil in which a substance composed of the tar content and other high-boiling oil-soluble organic matter is absorbed, and utilizing the heat of combustion. Processing method of critical water cracking gas.   The method for treating a supercritical water decomposition gas according to any one of claims 1 to 5, further comprising a step of separating an ammonia component as the water-soluble component and using the ammonia component as a component for exhaust gas treatment. .   The energy recovery system using the refined gas obtained by the processing method of the supercritical water cracking gas in any one of Claims 1-8 as fuel gas.   The energy recovery system according to claim 9, wherein the energy is energy of a gas turbine, a gas engine, a Stirling engine, or a fuel cell.   The organic compound manufacturing system using the refined gas obtained by the processing method of the supercritical water cracking gas in any one of Claims 1-8 as raw material gas.   The organic compound manufacturing system according to claim 11, wherein the organic compound is methanol or dimethyl ether.

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