JP2006274013A - Biomass gasification system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biomass gasification method and a biomass gasification system which are capable of producing more efficiently a fuel gas from a biomass by means of a supercritical water. <P>SOLUTION: The method and the system are such that the first power hot water treatment apparatus performs the hot water treatment of a biomass under the conditions of a temperature in the range of 100-250°C and a pressure in the range of 0.1-4 MPa in the presence of a nonmetallic catalyst and the second power hot water treatment apparatus performs the hot water treatment of such a slurry of the above biomass as is obtained by the above hot water treatment and as contains the above nonmetallic catalyst under the conditions of a temperature of 374°C or above and a pressure of 22.1 MPa or above. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biomass gasification method for gasifying biomass with supercritical water using a nonmetallic catalyst, and a biomass gasification system with supercritical water.

In recent years, energy conversion technologies using biomass such as plants or waste materials thereof, livestock manure, garbage, food waste, and sewage sludge have been developed. As an energy conversion technology using biomass as a raw material, for example, a method of generating fuel gas by fermenting biomass with microorganisms, a method of generating fuel gas by performing pressurized hot water treatment using water contained in biomass As the latter improved method, a method of gasifying wet biomass with supercritical water using a catalyst to generate fuel gas is known (for example, see Patent Documents 1 to 3). .
Japanese National Patent Publication No. 11-502891 JP 2002-105466 A JP 2002-105467 A

  However, the energy conversion techniques known so far are not always satisfactory in terms of fuel gas generation efficiency, and there is a demand for the development of a technique that can generate fuel gas more efficiently from biomass. .

  Then, an object of this invention is to provide the biomass gasification method and biomass gasification system by supercritical water which can produce | generate fuel gas from biomass more efficiently.

  In order to solve the above-mentioned problems, the biomass gasification method using supercritical water according to the present invention is characterized in that the biomass is heated to a temperature in the range of 100 to 250 ° C. and 0.1 to 4 MPa in the presence of a nonmetallic catalyst. A first step of performing hydrothermal treatment under conditions of pressure within the range of the above, and a biomass slurry obtained by the first step and containing the nonmetallic catalyst at a temperature of 374 ° C. or higher, And a second step of performing a hydrothermal treatment under a pressure condition of 22.1 MPa or more to generate fuel gas from the biomass. The hydrothermal treatment in the first step is preferably performed under conditions of a predetermined pressure (within a range of 0.1 to 4 MPa) and a saturation temperature of water at the pressure, and the hydrothermal treatment in the second step. Is preferably performed at a temperature of 600 ° C. and a pressure of 25 MPa.

  Moreover, the biomass gasification system using supercritical water (hereinafter referred to as “system”) according to the present invention has a biomass in the range of 100 to 250 ° C. and 0 in the presence of a nonmetallic catalyst. Obtained by performing hot water treatment in the first pressurized hot water treatment device that performs hot water treatment under conditions of pressure in the range of 1 to 4 MPa, and the first pressurized hot water treatment device And a second pressurized hydrothermal treatment device for hydrothermally treating the biomass slurry containing the nonmetallic catalyst under conditions of a temperature of 374 ° C. or higher and a pressure of 22.1 MPa or higher. Consists of.

  The system according to the present invention comprises: a means for supplying the slurry body from the first pressurized hot water treatment device to the second pressurized hot water treatment device; and the second pressurized hot water treatment device. The heat exchanger may further include a heat exchanger that preheats the slurry body using heat of the fuel gas generated by performing the hydrothermal treatment. Further, the system according to the present invention uses means for supplying the biomass to be processed in the first pressurized hot water treatment apparatus to the first pressurized hot water treatment apparatus, and heat of the slurry body. And a heat exchanger that preheats the biomass supplied to the first pressurized hot water treatment apparatus. Furthermore, the system according to the present invention includes means for supplying the biomass to be processed in the first pressurized hot water treatment apparatus to the first pressurized hot water treatment apparatus, and the second pressurized hot water. A heat exchanger that preheats the biomass supplied to the first pressurized hot water treatment device by using the heat of the fuel gas generated by performing the hot water treatment in the treatment device. Also good.

  The treatment in the first pressurized hot water treatment apparatus is preferably performed under conditions of a predetermined pressure and the saturation temperature of water at the pressure, and the treatment in the second pressurized hot water treatment apparatus is It is preferable to carry out under the conditions of a temperature of 600 ° C. and a pressure of 25 MPa.

  As the non-metallic catalyst, for example, activated carbon can be used. The activated carbon is preferably in a powder form and has an average particle size of 200 μm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the biomass gasification method and biomass gasification system by supercritical water which can produce | generate fuel gas from biomass more efficiently can be provided. Since the fuel gas obtained by these inventions can be used as a fuel for power generation or the like, it becomes possible to save resources of fossil fuels such as coal and oil.

  Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings.

== Configuration of biomass gasification system using supercritical water ==
FIG. 1 shows a configuration diagram of a biomass gasification system using supercritical water described as an embodiment of the present invention. Note that the numbers “1” to “13” in FIG. 1 indicate the order in which biomass and generated fuel gas pass through the system 100.

  As shown in FIG. 1, a system 100 according to the present invention includes a stirrer 20, a supply pump 30, a first pressurized hot water treatment device 50, a high pressure pump 31, a second pressurized hot water treatment device 70, and a cooling device. 80, separator 90, and the like.

  The stirrer 20 is a device that stirs and mixes the biomass and the nonmetallic catalyst. The first heated hot water treatment apparatus 50 uses a non-metallic catalyst in the mixture stirred and mixed by the stirrer 20 at a temperature in the range of 100 to 250 ° C. and 0.1 It is an apparatus for forming a biomass slurry by hydrothermal treatment under conditions of pressure in the range of -4 MPa. The supply pump 30 is a device that supplies the mixture stirred and mixed by the stirrer 20 to the first heated hot water treatment device 50.

  The second pressurized hot water treatment apparatus 70 uses a biomass slurry containing a nonmetallic catalyst obtained by performing the hydrothermal treatment in the first pressurized hot water treatment apparatus 50 as a nonmetallic catalyst. Is a device for generating fuel gas from biomass by hydrothermal treatment under conditions of a temperature of 374 ° C. or higher and a pressure of 22.1 MPa or higher. The high-pressure pump 31 is a second pressurized hot water while applying pressure to a biomass slurry body containing a nonmetallic catalyst obtained by performing the hydrothermal treatment in the first pressurized hot water treatment apparatus 50. This is a device that supplies the processing device 70.

  The cooling device 80 is a device that cools the gas discharged from the second pressurized hot water treatment device 70. Since the gas discharged from the second pressurized hot water treatment apparatus 70 includes explosive fuel gas, water vapor, and the like, the risk is reduced or the gas is converted to water to remove the water vapor. Therefore, the cooling device 80 is required. As the cooling device 80, for example, a known device such as a cooler can be used. The separator 90 is a device that separates the gas component contained in the exhaust gas cooled by the cooling device 80 and water. As the separator 90, for example, a known gas-liquid separator such as a separator can be used.

  As described above, by providing the first pressurized hot water treatment apparatus 50 in the system 100 including the second pressurized hot water treatment apparatus 70, the second pressurized hot water treatment apparatus 70 is processed. Biomass can be decomposed from high molecular weight to low molecular weight, and as a result, the contact efficiency between the biomass to be treated in the second pressurized hot water treatment device 70 and water or a non-metallic catalyst is increased. Fuel gas such as methane, ethane, and propane can be generated efficiently.

  Moreover, since the biomass slurry body excellent in fluidity can be formed by hydrothermally treating the biomass in the first pressurized hydrothermal treatment apparatus 50, the first high-pressure pump is used. A biomass slurry containing a nonmetallic catalyst can be supplied from the pressurized hot water treatment apparatus 50 to the second pressurized hot water treatment apparatus 70. Moreover, since the said slurry body is excellent in fluidity | liquidity (viscosity), such as an apparatus and piping produced when supplying from the 1st pressurized hot water treatment apparatus 50 to the 2nd pressurized hot water treatment apparatus 70 Clogging can be prevented.

  Furthermore, the system 100 according to the present invention is not only for hot water treatment performed in the first pressurized hot water treatment apparatus 50 but also for hot water treatment performed in the second pressurized hot water treatment apparatus 70. Since the system catalyst can be used effectively, the consumption of the catalyst can be reduced.

  Further, by providing the system 100 according to the present invention with the cooling device 80, the separator 90, and the like, the purity of the fuel gas discharged from the second pressurized hot water treatment device 70 can be increased.

  In the present embodiment, the biomass and the nonmetallic catalyst are mixed by the stirrer 20 and then supplied to the first pressurized hot water treatment device 50 by the supply pump 30, but these are separately supplied. It is good also as a structure which supplies directly to the 1st pressurized hot water processing apparatus 50. FIG.

  In the present embodiment, the biomass slurry containing the nonmetallic catalyst that has been hydrothermally treated in the first pressurized hot water treatment apparatus 50 is used as the second pressurized heat using the high-pressure pump 31. The slurry body is supplied to the water treatment device 70, but the slurry body may be preheated by the heating device 60 before being supplied to the second pressurized hot water treatment device 70. As the heating device 60, for example, a known device such as a heater can be used.

  According to a preferred aspect of the present embodiment, the biomass gasification system 100 using supercritical water may further include the heat exchangers 40, 41, and 42. In addition, a heat exchanger is the heat | fever of the slurry body of the biomass containing the nonmetallic catalyst obtained by carrying out the hot water process with the 1st pressurized hot water processing apparatus 50, or the 2nd pressurized hot water process. It is desirable to install so that the heat of the fuel gas produced | generated by performing the hot water process in the apparatus 70 can be utilized effectively.

  In the present embodiment, the hot water treatment is performed by the first pressurized hot water treatment device 50 using the heat of the fuel gas generated by performing the hot water treatment in the second pressurized hot water treatment device. The heat exchanger 42 for preheating the biomass slurry containing the nonmetallic catalyst obtained by doing so is provided. In addition, using the heat of the biomass slurry containing the nonmetallic catalyst obtained by hydrothermal treatment by the first pressurized hydrothermal treatment device 50, the first pressurized hydrothermal treatment device is used. A heat exchanger 40 for preheating the supplied biomass and the like is provided. Furthermore, in order to preheat biomass supplied to the first pressurized hot water treatment apparatus by using the heat of the fuel gas generated by performing the hot water treatment in the second pressurized hot water treatment apparatus The heat exchanger 41 is provided.

  By providing the heat exchangers 40, 41, and 42 as described above, energy can be used effectively, so that fuel gas can be generated with low energy and low cost. Moreover, since the heating time in each apparatus 50 and 70 is shortened, fuel gas can be generated from biomass in a short time. Accordingly, it can be said that the system 100 including the heat exchangers 40, 41, and 42 is excellent in economic efficiency.

== Biomass gasification method using supercritical water ===
Next, as one embodiment of the present invention, a method for generating fuel gas from biomass will be described.

  First, a mixture obtained by stirring and mixing a nonmetallic catalyst and biomass by the stirrer 20 is supplied to the first pressurized hot water treatment apparatus 50 by the supply pump 30 through the heat exchangers 40 and 41. The biomass supplied to the first pressurized hot water treatment apparatus 50 is hydrothermally treated under conditions of a predetermined pressure and a predetermined temperature in the presence of the nonmetallic catalyst supplied together with the biomass. The hot water treatment may be performed using water contained in the biomass, but may be performed using water that does not contain oxygen added in the stirrer 20, and water that does not contain oxygen. It is good also as supplying separately.

  In addition, the hydrothermal treatment conditions are not particularly limited as long as the temperature is in the range of 100 to 250 ° C. and the pressure is in the range of 0.1 to 4 MPa. From the viewpoint of the efficiency of the treatment of decomposing into low molecules, it is preferably the saturation temperature of water under a pressure within these ranges, and from the viewpoint of energy saving, a temperature of 179.8 ° C. and a pressure of 1.0 MPa It is particularly preferred that In addition, it was decided that the hydrothermal treatment was performed at a temperature within the range of 100 ° C. to 250 ° C. The decomposition reaction rate of biomass was low at less than 100 ° C., and tar and char were not generated when the temperature exceeded 250 ° C. It was because it was thought. In addition, the hydrothermal treatment is performed at a pressure within the range of 0.1 to 4 MPa because the biomass decomposition reaction rate is low at less than 0.1 MPa, and the influence on the decomposition reaction changes greatly even when the pressure exceeds 4 MPa. This is because it was thought that they would not.

  By treating the biomass with hot water in this way, it becomes possible to separate the biomass from a polymer into a low molecule. Moreover, the biomass separation efficiency can be increased by hydrothermally treating the biomass in the presence of a nonmetallic catalyst.

  The biomass slurry containing the nonmetallic catalyst obtained as described above is supplied to the second pressurized hot water treatment apparatus 70 through the heat exchangers 40 and 42 and the heater 60. The biomass slurry supplied to the second pressurized hot water treatment apparatus 70 is hydrothermally treated under conditions of a predetermined pressure and a predetermined temperature in the presence of the nonmetallic catalyst supplied with the biomass. . The hydrothermal treatment conditions are not particularly limited as long as the temperature is 374 ° C. or higher and the pressure is 22.1 MPa or higher. In order to suppress the generation of tar and char and increase the reaction efficiency. It is preferable to carry out at 600 ° C. and 25 to 35 MPa, and it is particularly preferred to carry out at 600 ° C. and 25 MPa from the viewpoints of equipment burden and prevention of deterioration, and energy saving. When it is desired to control the ratio of components in the fuel gas converted from biomass, the temperature and pressure conditions are adjusted and the fluid density and reaction time (in the second pressurized hot water treatment device 70 are adjusted). It becomes possible by controlling the biomass residence time).

  Thus, by reacting the biomass slurry body with supercritical water, it becomes possible to generate combustion gas from the biomass slurry body. In addition, by reducing the biomass from a polymer in advance, the contact efficiency with water or a non-metallic catalyst can be increased, and furthermore, the gasification reaction time of the biomass can be shortened. Fuel gas such as hydrogen gas, methane, ethane, or propane can be generated more efficiently from the slurry body.

  The fuel gas generated as described above is discharged from the second pressurized hot water treatment device 70 together with gas such as water vapor, carbon monoxide, carbon dioxide, and the like through the heat exchangers 42 and 41 and the cooling device 80. It is supplied to the separator 90 and separated into a gas component and water by a known gas-liquid separation technique. Then, when it is desired to separate each component contained in the gas, the gas component may be separated using a known gas separation technique. Thereby, the gas of each component with high purity can be obtained.

  When tar is generated in addition to the fuel gas by the hot water treatment performed in the second pressurized hot water treatment apparatus 70, a dust collector (for example, a wet or dry electric dust collector), a filter (for example, The tar may be removed using a ceramic filter, a bag filter, etc.), an amino adsorption column, etc., or the tar is decomposed and removed in a tar cracking furnace using heat, steam, oxygen, or a catalyst (eg, dolomite). It is good to do. In addition, when char is generated in addition to the fuel gas, the char may be removed using a dust collector (for example, a wet or dry electric dust collector), a filter (for example, a ceramic filter, a bag filter, etc.), etc. Good. As a result, troubles caused by tar and char can be solved, and fuel gas can be efficiently recovered.

  The nonmetallic catalyst used in the present embodiment is, for example, activated carbon or zeolite. Thus, by using a non-metallic catalyst instead of an alkali metal-based catalyst, it is possible to prevent deterioration due to corrosion of equipment or piping caused by the alkali metal-based catalyst, and long-term use of the system 100 can be realized. Become. In addition, a processing step for neutralizing the alkali metal catalyst is not required, and the efficiency of workability can be improved. As the non-metallic catalyst, it is preferable to use a powder having an average particle diameter of 200 μm or less, and it is more preferable that the non-metallic catalyst is porous. As a result, the surface area can be increased to increase the reaction efficiency, and clogging of equipment, piping, etc. in the system 100 due to the nonmetallic catalyst can be prevented. In addition, it is preferable that the nonmetallic catalyst used in this Embodiment is in the range of 1: 5-20: 1 by mass ratio (nonmetallic catalyst: biomass) with dry biomass, The gasification efficiency is particularly preferably in the range of 1: 2 to 20: 1.

  Further, when the biomass to be treated in the present embodiment is wastewater sludge or manure containing foreign matters such as sand, a known separation is performed before and after the biomass is treated in the first pressurized hot water treatment apparatus 50. It is good also as removing foreign substances, such as the sand contained in biomass, by the technique (For example, the separation method using a strainer, the separation method using a sediment layer). As a result, troubles caused by foreign matters such as sand can be prevented.

  Hereinafter, the present invention will be specifically described by way of examples. These examples are for explaining the present invention, and do not limit the scope of the present invention.

[Example 1]
30 parts by mass or 60 parts by mass of activated carbon having a particle size of 100 μm is added to 100 parts by mass of a potato paste having a water content of 90%, and the mixture is stirred and mixed. The reaction with supercritical water was carried out for 1 hour. As a control experiment, a gasification reaction with supercritical water was similarly performed without adding activated carbon. As a result, when no activated carbon is added, the gasification rate is 20% or less in terms of carbon dioxide, whereas when 30 parts by mass of activated carbon is added, the gasification rate increases to 30%. It became clear. It was also found that when the amount of activated carbon was increased to 60 parts by mass, the gasification rate further increased to 60%.

[Example 2]
Next, 80 parts by mass of water, 20 parts by mass of cellulose powder, and 20 parts by mass of activated carbon having an average particle size of 100 μm were stirred and mixed to prepare a slurry. Thereafter, 40 ml of the slurry was poured into a 167 ml autoclave equipped with a stirrer, and the temperature was raised to 400 ° C. while stirring at a pressure of 25 MPa and held for 1 hour to perform a gasification reaction with supercritical water. After the reaction, the reaction mixture was cooled to room temperature, and the product gas was recovered to determine the carbon gasification rate. As a control experiment, the same treatment was performed without adding activated carbon. As a result, it was found that the carbon gasification rate was 10% when no activated carbon was added, whereas the carbon gasification rate increased to 30% when activated carbon was added.

  From the above, it has been clarified that the gasification efficiency can be increased by adding the catalyst, and the gasification efficiency can be further increased by adding the catalyst in an increased amount. Further, it was shown that even when a biomass slurry containing activated carbon is supplied to the fluidized bed reactor, the activated carbon contained in the slurry acts as a catalyst, and the biomass can be efficiently gasified.

It is a figure which shows the structure of the biomass gasification system by supercritical water demonstrated as one Example of this invention.

Explanation of symbols

20 Stirrer 30 Supply pump 31 High-pressure pump 40, 41, 42 Heat exchanger 50 First pressurized hot water treatment device 60 Heating device 70 Second pressurized hot water treatment device 80 Cooling device 90 Separator 100 Biomass by supercritical water Gasification system

Claims (13)

A first step of hydrothermally treating the biomass under conditions of a temperature in the range of 100 to 250 ° C. and a pressure in the range of 0.1 to 4 MPa in the presence of a nonmetallic catalyst;
The biomass slurry containing the non-metallic catalyst obtained in the first step is subjected to hydrothermal treatment under conditions of a temperature of 374 ° C. or higher and a pressure of 22.1 MPa or higher, and from the biomass A second step of generating fuel gas;
A biomass gasification method using supercritical water, comprising:   The method according to claim 1, wherein the hydrothermal treatment in the first step is performed under a condition of a predetermined pressure and a saturation temperature of water at the pressure.   The method according to claim 1 or 2, wherein the non-metallic catalyst is activated carbon.   The method according to claim 3, wherein the activated carbon is a powder having an average particle size of 200 μm or less.   The method according to claim 1, wherein the hydrothermal treatment in the second step is performed under conditions of a temperature of 600 ° C. and a pressure of 25 MPa. A first pressurized hydrothermal treatment apparatus that performs hydrothermal treatment of biomass under conditions of a temperature within a range of 100 to 250 ° C. and a pressure within a range of 0.1 to 4 MPa in the presence of a nonmetallic catalyst. When,
The biomass slurry containing the non-metallic catalyst obtained by performing hydrothermal treatment in the first pressurized hot water treatment apparatus has a temperature of 374 ° C. or higher and a pressure of 22.1 MPa or higher. A second pressurized hot water treatment device that performs hot water treatment under conditions;
A biomass gasification system using supercritical water, characterized by comprising: Means for supplying the slurry body from the first pressurized hot water treatment device to the second pressurized hot water treatment device;
A heat exchanger that preheats the slurry body using heat of fuel gas generated by performing hydrothermal treatment in the second pressurized hot water treatment apparatus;
The system of claim 6 further comprising: Means for supplying the biomass to be treated in the first pressurized hot water treatment apparatus to the first pressurized hot water treatment apparatus;
A heat exchanger that preheats the biomass supplied to the first pressurized hot water treatment device using the heat of the slurry body;
The system of claim 6 further comprising: Means for supplying the biomass to be treated in the first pressurized hot water treatment apparatus to the first pressurized hot water treatment apparatus;
Heat that preheats the biomass supplied to the first pressurized hot water treatment device using the heat of the fuel gas generated by performing the hot water treatment in the second pressurized hot water treatment device An exchange,
The system of claim 6 further comprising:   The system according to any one of claims 6 to 9, wherein the hot water treatment in the first pressurized hot water treatment apparatus is performed under a condition of a predetermined pressure and a saturation temperature of water at the pressure. .   The system according to claim 6, wherein the nonmetallic catalyst is activated carbon.   The system according to claim 11, wherein the activated carbon is a powder having an average particle size of 200 μm or less. The system according to any one of claims 6 to 12, wherein the hot water treatment in the second pressurized hot water treatment apparatus is performed under conditions of a temperature of 600 ° C and a pressure of 25 MPa.