Method for producing biomass carbide

Abstract

To provide a method for producing a biomass carbide having reduced exothermic properties.SOLUTION: A method for producing a biomass carbide, comprising a step of carbonizing biomass in a steam atmosphere at 550 °C or higher to obtain a biomass carbide.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing biomass charcoal. [Background technology]

[0002] Many methods for producing biomass fuels have already been put into practical use. Known methods for producing biomass fuels include drying, cutting, and molding biomass, followed by semi-carbonization or carbonization, and semi-carbonization or carbonization in an inert atmosphere (such as nitrogen) or in an oxygen-free atmosphere of combustion exhaust gas (such as pyrolysis gas). Technologies for converting biomass into carbon-neutral fuels have also been developed.

[0003] For example, Patent Document 1 discloses a method for producing charcoal, which is characterized by introducing exothermic charcoal that has been produced in a carbonization furnace and then washed with water into a retention device located between a water washing tank and a storage tank, and promoting the exothermic reaction of the charcoal in this retention device. Patent Document 2 discloses a method for producing a carbonized material, in which exothermic carbonized material produced in a carbonization furnace and then recovered is led, while maintained at a relatively high temperature, into a retention device located between the carbonization furnace and a water washing tank located downstream of the carbonization furnace, and the exothermic reaction of the carbonized material is promoted in this retention device, followed by a water washing treatment.

[0004] Patent Document 3 discloses a method for producing solid fuel from organic sludge, in which dried organic sludge is carbonized in a carbonization facility to produce a solid fuel, characterized by a carbonization step in which the dried organic sludge is carbonized until the atomic ratio H / C of hydrogen to carbon reaches 1.0 or more and 1.8 or less, and by contacting the sludge with steam during the carbonization step. Patent Document 4 discloses a carbonization system that carbonizes waste-based biomass and uses the combustion exhaust gas generated by burning the dry distillation gas generated during the carbonization as a heat source, characterized by comprising: a dryer that dries the waste-based biomass to turn it into dried biomass; a carbonization furnace that heats and carbonizes the dried biomass to produce a carbonized material and dry distillation gas; a combustion furnace that combusts the dry distillation gas from the carbonization furnace to produce a combustion exhaust gas; and a cooling mechanism that introduces steam or water into the carbonized material discharged from the carbonization furnace and cools it. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-302834 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-246773 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-146130 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-082799 Summary of the Invention [Problem to be solved by the invention]

[0006] However, while carbonized materials obtained from biomass and other materials have a high calorific value, they are more susceptible to oxidation reactions than before carbonization due to structural changes caused by decomposition and polymerization during dry distillation. As a result, the risk of spontaneous heating during storage of carbonized materials tends to increase as the volatile content decreases. Patent Documents 1 and 2 describe a method of carrying out post-treatment in which the obtained carbonized material is subjected to an exothermic reaction in a retention device to prevent ignition and fire, but it would be effective if carbonized material could be produced using existing equipment without such post-treatment. Patent Documents 3 and 4 are technologies that mainly use biomass derived from sludge. Patent Documents 3 and 4 describe a method of introducing steam into a carbonization furnace or into the carbonized material discharged from the carbonization furnace, but it cannot be said that sufficient consideration has been given to the carbonization conditions for reducing the heat generation property of the carbonized material.

[0007] An object of the present invention is to provide a method for producing biomass char with reduced heat generation. [Means for solving the problem]

[0008] [1] A process for carbonizing biomass in a water vapor atmosphere at 550°C or higher to obtain biomass charcoal. A method for producing biomass charcoal. [2] The temperature of the carbonization treatment is 600°C or higher. The method for producing biomass charcoal described in [1] above. [3] The biomass carbonized material is in the form of powder, pellets, briquettes, or chips. The method for producing biomass charcoal according to [1] or claim 2. [4] The content of volatile matter in the biomass carbonized material is 30% by mass or less. The method for producing biomass charcoal according to any one of [1] to [3] above. [5] The volatile content of the biomass carbonized material is 15% by mass or less. The method for producing biomass charcoal according to [4] above. [6] When the biomass carbonized material is held in an oxygen atmosphere at 140°C for 15 minutes using a differential scanning calorimeter, the integrated value of the calorific value is 110 J / g or less. The method for producing biomass charcoal according to any one of [1] to [5] above. [7] The process for obtaining the biomass carbonized material is a process for carbonizing the biomass while introducing water vapor into the carbonization furnace from the start of heating the biomass to the end of the carbonization process after introducing the biomass into the carbonization furnace. The method for producing biomass charcoal according to any one of [1] to [6] above. [8] In the step of obtaining the biomass carbonized material, after the biomass is introduced into the carbonization furnace, water vapor is introduced into the carbonization furnace when the temperature of the biomass is less than 50°C. The method for producing biomass charcoal according to any one of [1] to [6] above. [9] The molar ratio of hydrogen atoms to carbon atoms in the biomass carbonized material (moles of hydrogen atoms / moles of carbon atoms) is 0.50 or less. The method for producing biomass charcoal according to any one of [1] to [8].

[10] The biomass is at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass; The method for producing biomass charcoal according to any one of [1] to [9].

[11] The biomass is palm biomass. The method for producing biomass charcoal according to

[10] above. [Effects of the Invention]

[0009] According to one aspect of the present invention, a method for producing biomass charcoal with reduced heat generation can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a carbonization apparatus used in Examples and Comparative Examples. [Figure 2] FIG. 1 is a schematic diagram of a spontaneous combustion test device used in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0011] In this specification, a numerical range expressed using "to" means a range that includes the number written before "to" as the lower limit and the number written after "to" as the upper limit. In this specification, mass percent concentration (unit: mass % (mass%)) and weight percent concentration (unit: weight % (wt%)) are the same value.

[0012] [First embodiment] [Method for producing biomass charcoal] The method for producing biomass char according to this embodiment (hereinafter also referred to as the production method of this embodiment) includes a step of carbonizing biomass in a water vapor atmosphere at 550° C. or higher to obtain biomass char. According to the manufacturing method of this embodiment, biomass charcoal with reduced heat generation properties can be obtained. In this specification, the cumulative oxidation heat value and the time t 180 is used. The cumulative oxidation calorific value is the cumulative value of the heat generated when biomass carbonized material is kept in an oxygen atmosphere at 140°C for 15 minutes using a differential scanning calorimeter. The unit of cumulative oxidation calorific value is [J / g]. Time t 180 The time is measured using a spontaneous combustion test device (see Figure 2), and is the time it takes for the biomass carbonized material to reach 110°C and 180°C under specified test conditions. Cumulative oxidation heat generation and time t 180 The method for measuring this will be explained in the Examples below.

[0013] Hereinafter, biomass carbonized material may be simply referred to as carbonized material. The inventors have found that when biomass is carbonized in a water vapor atmosphere at 550°C or higher, the heat generation properties of the carbonized product tend to be contradictory to those when biomass is carbonized in a nitrogen atmosphere at high temperatures (e.g., 500°C or higher). Specifically, when biomass is carbonized in a nitrogen atmosphere at high temperatures, the cumulative oxidation heat value of the carbonized product increases as the carbonization temperature increases, but when biomass is carbonized in a water vapor atmosphere at 550°C or higher, the cumulative oxidation heat value of the carbonized product decreases. The reasons for this are thought to be as follows. The exothermicity of charcoal is thought to depend on its functional groups and physical structure. If the charcoal contains many functional groups that are particularly susceptible to oxidation (e.g., carboxyl groups and hydroxyl groups), the oxidation of these functional groups can easily generate heat. As the number of functional groups that are easily oxidized increases with the progress of the pyrolysis reaction, the exothermicity of the charcoal becomes even higher. When biomass is carbonized in a water vapor atmosphere, in addition to the thermal decomposition of functional groups, the biomass may also undergo a gasification reaction due to reaction with water vapor. Therefore, just as functional groups change as the thermal decomposition reaction progresses (in the case of a thermal decomposition reaction, the number of functional groups increases), it is thought that functional groups also change as the gasification reaction progresses. However, the gasification reaction by steam occurs at a higher temperature than the pyrolysis reaction. Although the detailed mechanism is not clear, it is thought that the functional groups and physical structure of the resulting carbonized material change depending on the presence or absence of steam during carbonization treatment at a specific temperature or higher (550°C or higher in this embodiment) for the reasons (i) and (ii) below. According to the manufacturing method of this embodiment, it is believed that these changes in functional groups and physical structure contribute to a decrease in the heat buildup of the charcoal. (i) In pyrolysis in a steam atmosphere, in addition to the pyrolysis reaction, a gasification reaction due to the steam may occur. (ii) The temperature ranges for the pyrolysis reaction and the gasification reaction are different.

[0014] Furthermore, according to the manufacturing method of this embodiment, the carbonized material can be carbonized using existing equipment without post-processing as in Patent Documents 1 and 2, which reduces the number of steps and simplifies the manufacturing equipment.

[0015] <Step for obtaining biomass charcoal> The step of obtaining biomass carbonized material is carried out in a carbonization furnace. The carbonization furnace is not particularly limited, but examples thereof include known heating furnaces (such as rotary kilns) and electric furnaces. In the process of obtaining biomass carbonized material, the carbonization temperature refers to the set temperature of the carbonization furnace. The carbonization temperature is preferably 600°C or higher, more preferably 650°C or higher, and even more preferably 700°C or higher. From the viewpoint of yield, the carbonization temperature is, for example, 800°C or lower.

[0016] In the step of obtaining biomass carbonized material, the pressure in the carbonization furnace is preferably atmospheric pressure (0.1 MPa) or higher.

[0017] In the step of obtaining biomass carbonized material, the temperature of the steam when introduced into the carbonization furnace is preferably 150°C or higher, more preferably 180°C or higher, and even more preferably 200°C or higher. The temperature of the steam when it is introduced into the carbonization furnace is the temperature set in the steam generation source (for example, a steam generator, a superheated steam generator, etc.).

[0018] In the process of obtaining biomass carbonized material, the time of the carbonization treatment depends on the temperature of the carbonization treatment, but is preferably 5 minutes or more and 120 minutes or less, more preferably 5 minutes or more and 60 minutes or less, and even more preferably 5 minutes or more and 30 minutes or less. The carbonization treatment time refers to the time the biomass is held at the desired temperature.

[0019] In the process of obtaining biomass carbonized material, the flow rate of steam supplied to the carbonization furnace depends on the size of the carbonization furnace, but is preferably 1 L / min or more and 5 L / min or less, more preferably 2 L / min or more and 4 L / min or less, and even more preferably 2 L / min or more and 3 L / min or less.

[0020] In the manufacturing method of this embodiment, the process for obtaining a carbonized material is preferably a process in which, after introducing biomass into a carbonization furnace, the biomass is carbonized while introducing steam into the carbonization furnace from the start of heating the biomass to the end of the carbonization process. In the step of obtaining biomass carbonized material, after the biomass is introduced into the carbonization furnace, it is preferable to introduce steam into the carbonization furnace when the temperature of the biomass is lower than 50°C. The temperature referred to in the phrase "from the time when the temperature of the biomass becomes less than 50°C" is, for example, the temperature of the biomass when it is introduced into the carbonization furnace. The temperature referred to in the phrase "from the time when the temperature of the biomass becomes less than 50°C" may be less than 40°C, less than 30°C, room temperature (25°C), or less than 25°C. The time (minutes) from the start of heating the biomass to the end of the carbonization process refers to the sum of the time from the start of heating the biomass to the time the carbonization furnace reaches the target temperature and the time the biomass is held at the target temperature.

[0021] <Shape of biomass charcoal> The shape of the biomass char is derived from the shape of the biomass introduced into the carbonization furnace. The biomass introduced into the carbonization furnace is crushed, cut, molded, etc. by known means and adjusted to a predetermined shape and size. The shape of the biomass charcoal is not particularly limited. The biomass carbonized material is preferably in the form of powder, pellets, briquettes, or chips. The shape of the biomass carbonized material may be, for example, a shape derived from the shape of the biomass itself (for example, palm fruit bunches), or may be elongated or irregular in shape.

[0022] When the biomass char is in powder form, the particle size of the biomass char is preferably 1000 μm or less, more preferably 500 μm or less. In this specification, particle size refers to the major axis diameter, which is the maximum length of a straight line connecting any two points on the outer contour of the biomass char. The pellets are usually cylindrical, with a diameter of 5 mm to 10 mm and a length of 5 mm to 50 mm. Briquettes typically have a larger width and length than pellets. When the briquette is cylindrical, the size of the briquette-shaped biomass charcoal is, for example, 10 mm or more and 100 mm or less in diameter and 10 mm or more and 300 mm or less in length. When the biomass char is in chip form, the size of the biomass char is not particularly limited. For example, the major axis diameter of wood-based biomass char is preferably 5.0 cm or less, and more preferably 1.0 cm or less.

[0023] <Characteristics of biomass charcoal> The characteristics of the biomass char obtained in the process for obtaining the biomass char will be described. The methods for measuring each property will be explained in the examples below.

[0024] (volatile matter) The content of volatile matter (on a dry basis) in the biomass carbonized material is preferably 30% by mass or less, more preferably 15% by mass or less, even more preferably 12% by mass or less, and even more preferably 11% by mass or less.

[0025] (fixed carbon) Biomass carbonized material contains carbonized biomass components and has a high proportion of fixed carbon. The fixed carbon content of the biomass carbonized material (mass basis, dry basis) is preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more. The upper limit of the fixed carbon content is, for example, 95% or less.

[0026] (carbon yield) The carbon yield (by mass, dry basis) of the biomass carbonized product is preferably 20% or more, more preferably 20% to 40%, even more preferably 20% to 35%, and even more preferably 20% to 30%.

[0027] (moles of hydrogen atoms / moles of carbon atoms) The molar ratio of hydrogen atoms to carbon atoms (moles of hydrogen atoms / moles of carbon atoms) [mol / mol] in the biomass carbonized material is preferably 0.50 or less, more preferably 0.40 or less, and even more preferably 0.30 or less. Hereinafter, the molar ratio (number of moles of hydrogen atoms / number of moles of carbon atoms) may be referred to as the molar ratio (H / C) [mol / mol].

[0028] (moles of oxygen atoms / moles of carbon atoms) The molar ratio of oxygen atoms to carbon atoms (moles of oxygen atoms / moles of carbon atoms) [mol / mol] in the biomass carbonized material is preferably 0.060 or less, more preferably 0.050 or less, and even more preferably 0.045 or less. Hereinafter, the molar ratio (moles of oxygen atoms / moles of carbon atoms) may be referred to as the molar ratio (O / C) [mol / mol]. The molar ratio (O / C) [mol / mol] is a value calculated from elemental analysis values.

[0029] (Cumulative oxidation heat generation) When biomass carbonized material is held in an oxygen atmosphere at 140°C for 15 minutes using a differential scanning calorimeter, the cumulative oxidation calorific value (cumulative value of heat generation) is preferably 110 J / g or less, more preferably 108 J / g or less, even more preferably 100 J / g or less, and even more preferably 90 J / g or less.

[0030] (Time t 180 ) Time t 180 is measured using a spontaneous combustion test device (see Figure 2) in the following manner. First, the biomass char is filled into the test vessel of the spontaneous combustion test device, and then heated to 110°C under adiabatic conditions and a nitrogen atmosphere. The atmosphere is then switched from nitrogen to oxygen, and the time from when the biomass char reaches 110°C to when it reaches 180°C is measured. This time is called time t 180 (minutes). It is believed that the temperature of biomass charcoal rises due to an oxidation reaction in an oxygen atmosphere. Time t 180 The time (minutes) is preferably 60 minutes or more, more preferably 70 minutes or more, even more preferably 75 minutes or more, and even more preferably 80 minutes or more.

[0031] The biomass used in the production method of this embodiment will be described.

[0032] (biomass) The biomass is not particularly limited, but examples thereof include woody biomass, herbaceous biomass, agricultural residue biomass, palm biomass, cellulose products, and pulp products. As used herein, crop residue biomass means anything other than the edible parts. As used herein, palm biomass refers to agricultural waste from palm trees. The biomass is preferably at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass. The biomass is more preferably woody biomass or palm biomass, and even more preferably palm biomass.

[0033] Examples of woody biomass include conifers (e.g., cedar, pine, eucalyptus, cypress, and fir), and broad-leaved trees (e.g., birch, acacia, black locust, beech, zelkova, katsura, paulownia, rubber tree, and camphor tree). Woody biomass may also be construction waste (e.g., cut off wood, chips generated at processing plants, and sawdust), forest residues, thinned wood, and bamboo. Examples of herbaceous biomass include grasses, naturally grown plants, and artificially planted plants. Herbaceous biomass may be hemp, cotton, rice straw, rice husks, wheat straw, bamboo grass, napier grass, sorghum, and Japanese silver grass.

[0034] Crop residue biomass includes, for example, leaves, fruit clusters, stems, roots, and other non-edible parts of crops such as wheat, corn, potato, sugarcane (including bagasse), and banana.

[0035] Examples of palm biomass include palm kernel shells (PKS), empty fruit bunches (EFB), and palm trunks. The above-described biomass may be used singly or in combination of two or more kinds.

[0036] The present invention is not limited to the above-described embodiment, and any modifications and improvements that can achieve the object of the present invention are included in the present invention. [Example]

[0037] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0038] Table 1 shows the properties of the EFB pellets used in each example. The EFB pellets used in each example were pellets (cylindrical: diameter 8 mm, maximum height 40 mm) obtained by cutting, drying, and crushing palm empty fruit bunches, and then compressing and molding them.

[0039] [Table 1]

[0040] Explanation of Table 1 "EFB WP" indicates that the EFB pellets have not been heat treated. Proximate analysis values ​​were measured in accordance with JIS M8812 (2004). Of the elemental analysis values, carbon, hydrogen, nitrogen, and sulfur were measured in accordance with JIS M8819 (1997), and oxygen was calculated from other analytical values ​​in accordance with JIS M8813 (2004). The chlorine content (mg / kg, DB) is a value measured in accordance with JIS Z7302-6 (1999). The fluorine content (mg / kg, DB) was measured in accordance with ISO 11724. The higher heating value is a value measured in accordance with JIS M8814 (2003). The lower heating value is a value measured in accordance with JIS M8814 (2003). The fuel ratio is "fixed carbon / volatiles." Total sulfur is measured by a method conforming to JIS M8813 (2004). Bulk density is measured by a method conforming to ISO 17828. Dry basis (DB) calorific value indicates the calorific value in a dry state. "Ash" indicates ash-based. "AR" indicates arrival base.

[0041] Explanation of Tables 1 and 2 "AD" indicates an air-dried basis. This is the analytical value when the weight in a naturally dried state indoors is taken as 100% by weight. "DB" indicates a dry basis, which is an analytical value when the weight excluding water is taken as 100% by weight. "Daf" and "DAF" indicate dry ash-free basis, which is an analytical value when the weight excluding moisture and ash is taken as 100% by weight.

[0042] [Carbonization device] First, we will explain the carbonization apparatus used when carbonizing the EFB pellets in Examples 1 to 3 and Comparative Examples 1 to 4. Fig. 1 is a schematic diagram of the carbonization apparatus.

[0043] The carbonization apparatus 100 includes a carbonization furnace 10, a reaction tube 12 disposed in the center of the carbonization furnace 10, a gas supply section 20, a cooling section 30, a processing section 32, and an exhaust section 40. In the case of Fig. 1, the carbonization furnace 10 is an electric furnace. A thermocouple 16A for measuring the temperature of the reaction tube 12 is embedded in the center of the side wall of the carbonization furnace 10. The reaction tube 12 is heated to, for example, 500° C. or higher by heating the carbonization furnace 10. A gas supply pipe 121 is disposed at the bottom of the reaction tube 12, and a gas exhaust pipe 122 is disposed at the top of the reaction tube 12. The gas supply pipe 121 is connected to a gas supply unit 20, and the gas exhaust pipe 122 is connected to a cooling unit 30. The reaction tube 12 has a sample stage 18 therein, and a sample S (EFB pellets) is introduced into this sample stage 18. A thermocouple 16B for measuring the temperature of the sample S is embedded in the bottom of the sample stage 18, and the thermocouple 16B is connected to a data logger 17. The data logger 17 calculates and displays the temperature of the reaction tube 12 measured by the thermocouple 16A and the temperature of the sample S measured by the thermocouple 16B. The gas supply unit 20 is connected to a water supply unit 22 and a nitrogen supply unit 24, and a heater 21 is wound around the gas supply unit 20. When water is supplied to the gas supply unit 20 from the water supply device 22 by a pump (not shown), the gas supply unit 20 functions as a water vapor generator that generates water vapor. The water supplied to the gas supply unit 20 is heated by the heater 21 to become water vapor. The water vapor is supplied into the reaction tube 12 from the gas supply pipe 121, passes through the sample S, and then is discharged from the gas discharge pipe 122 together with the gas generated from the sample S. It is considered that the water vapor becomes superheated water vapor when passing through the reaction tube 12 at a high temperature (for example, 500°C or higher). The gas supply unit 20 may be a superheated steam generator that generates superheated steam. In this case, the superheated steam is supplied into the reaction tube 12 through the gas supply pipe 121. When nitrogen is supplied to the gas supply unit 20 from the nitrogen supply unit 24, the gas supply unit 20 heats the nitrogen with the heater 21 or passes the nitrogen as is without heating it. The heated or unheated nitrogen is supplied into the reaction tube 12 from the gas supply pipe 121. The exhaust gas (water vapor, nitrogen, and gas generated from the sample S) discharged from the gas discharge pipe 122 etc. ) is cooled in the cooling section 30, passes through the treatment section 32, and is then exhausted from the exhaust section 40. The treatment section 32 is, for example, a treatment tank that stores treated water (for example, water, etc.).

[0044] Example 1 EFB pellets (20 g) were filled as sample S on the sample stage 18 in the reaction tube 12. Steam at 200°C generated in the gas supply unit 20 was supplied into the reaction tube 12 at a rate of 2 L / min, and the atmosphere in the reaction tube 12 was replaced with steam. The carbonization furnace 10 was set to 550° C. to heat the reaction tube 12 while supplying water vapor into the reaction tube 12 at 2 L / min. The set temperature of the carbonization furnace 10 was defined as the carbonization temperature (temperature of the carbonization treatment). After the temperature of the carbonization furnace 10 reached 550°C, the sample S was held there for 5 minutes to be carbonized. The carbonization conditions were as follows:

[0045] (Carbonization conditions) Heating rate of carbonization furnace 10: 60°C / min Carbonization furnace 10 setting temperature (carbonization temperature): 550℃ Carbonization time: 5 minutes Pressure of carbonization furnace 10: 0.1 MPa

[0046] Then, the carbonization furnace 10 of Heating was stopped, and the supply of water vapor into the reaction tube 12 was stopped. Thereafter, the gas supply unit 20 was connected to the nitrogen supply unit 24, and nitrogen was supplied into the reaction tube 12 at a rate of 2 L / min, thereby replacing the atmosphere inside the reaction tube 12 with nitrogen. After it was confirmed that the temperature of the sample S had dropped to 50°C, the supply of nitrogen into the reaction tube 12 was stopped, and the carbonized EFB pellets were collected as the biomass carbonized product.

[0047] Example 2 A carbonized product of the EFB pellets of Example 2 was obtained in the same manner as in Example 1, except that the set temperature of the carbonization furnace 10 was changed to 600°C compared to the carbonization conditions of Example 1.

[0048] Example 3 A carbonized product of the EFB pellets of Example 3 was obtained in the same manner as in Example 1, except that the set temperature of the carbonization furnace 10 was changed to 700°C compared to the carbonization conditions of Example 1.

[0049] Comparative Example 1 The sample stage 18 in the reaction tube 12 was filled with EFB pellets (20 g) as the sample S. The gas supply unit 20 was connected to the nitrogen supply unit 24, and nitrogen was supplied into the reaction tube 12 at a rate of 2 L / min, so that the atmosphere in the reaction tube 12 was replaced with nitrogen. While nitrogen was supplied into the reaction tube 12 at a rate of 2 L / min, the carbonization furnace 10 was set to 500°C, and the reaction tube 12 was heated to 500°C. After the temperature of the carbonization furnace 10 reached 500°C, the sample S was held there for 5 minutes to be carbonized. The carbonization conditions were the same as those in Example 1 except for the set temperature of the carbonization furnace 10 . Thereafter, heating by the carbonization furnace 10 was stopped. Meanwhile, the supply of nitrogen into the reaction tube 12 was continued, and after it was confirmed that the temperature of the sample S had dropped to 50°C, the supply of nitrogen into the reaction tube 12 was stopped. Next, the carbonized EFB pellets were collected as biomass carbonized material.

[0050] Comparative Example 2 A carbonized product of the EFB pellets of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the set temperature of the carbonization furnace 10 was changed to 600°C compared to the carbonization conditions of Comparative Example 1.

[0051] Comparative Example 3 A carbonized product of the EFB pellets of Comparative Example 3 was obtained in the same manner as in Comparative Example 1, except that the set temperature of the carbonization furnace 10 was changed to 700°C compared to the carbonization conditions of Comparative Example 1.

[0052] Comparative Example 4 A carbonized product of the EFB pellets of Comparative Example 4 was obtained in the same manner as in Example 1, except that the set temperature of the carbonization furnace 10 was changed to 500°C compared to the carbonization conditions in Example 1.

[0053] [Reference example 1] The EFB pellets were heated in a nitrogen atmosphere at 700°C for 30 minutes to obtain a carbonized EFB pellet. This carbonized EFB pellet was then heated in an atmosphere with an oxygen concentration of 10% by volume or less at 200°C for 120 minutes (oxidation step). In this manner, a carbonized product of the oxidized EFB pellets of Reference Example 1 was obtained.

[0054] [evaluation] The carbides obtained in each example were evaluated as follows. The carbides obtained in the reference examples were also evaluated for the items other than "-" in Table 2. The results are shown in Table 2.

[0055] <Elemental analysis> Of the elemental analysis values, carbon, hydrogen, and nitrogen (all DAF) were measured in accordance with JIS M8819 (1997). Of the elemental analysis values, oxygen (DAF) is calculated by the following formula (Math 1). Oxygen [wt%] = 100 [wt%] - Carbon [wt%] - Hydrogen [wt%] - Nitrogen [wt%] ... (Equation 1) The molar ratio (H / C) [mol / mol] is a value calculated from elemental analysis values. The molar ratio (O / C) [mol / mol] is a value calculated from elemental analysis values.

[0056] <Carbonization yield> The carbonization yield is measured from the weight of the EFB pellets before and after carbonization using the following formula (2). Carbonization yield [wt%] = (weight [g] (DB) of EFB pellets after carbonization / weight [g] (DB) of EFB pellets before carbonization) × 100 (Equation 2)

[0057] <Fixed carbon, ash, and volatile matter> Fixed carbon, ash, and volatile matter (all DB) are proximate analysis values. Proximate analysis values ​​are measured in accordance with JIS M8812 (2004).

[0058] <High heating value> The higher heating value (DB) is measured in accordance with JIS M8814 (2003). The unit of higher heating value is [kcal / kg].

[0059] <Cumulative oxidation heat generation> The cumulative oxidation heat value (DB) [J / g] of the carbonized material obtained in each example was measured by differential scanning calorimetry (DSC). A sample for measuring the cumulative oxidation calorific value was prepared in the following manner. The carbide obtained in each example was pulverized to obtain fine powder with a particle size of 0.212 mm or less. This was used as the measurement sample. The measurement conditions were as follows: The smaller the cumulative oxidation heat value, the less likely the carbide is to generate heat.

[0060] (Measurement conditions) Apparatus: Differential scanning calorimeter (Shimadzu Corporation, model number DSC-60) Heating rate and holding time: The temperature was raised from room temperature (25°C) to 140°C at a rate of 50°C / min in a nitrogen atmosphere, then switched to an oxygen atmosphere and held at 140°C for 15 minutes. Nitrogen flow rate during heating: 50 mL / min Oxygen flow rate during maintenance: 50 mL / min Sample amount: 5 mg

[0061] <Fever> (Spontaneous combustion test device) The heat generation properties of the charcoal obtained in each example were evaluated using a spontaneous combustion test device (Shimadzu Corporation: SIT-2) shown in Figure 2. First, the spontaneous combustion test device will be described. FIG. 2 is a schematic diagram of the spontaneous combustion test apparatus. The spontaneous combustion test device 50 includes a thermostatic chamber 51 and a reactor 59. The reactor 59 is provided inside the thermostatic chamber 51, and a cylindrical test vessel 60 is provided inside the reactor 59. The test vessel 60 is designed so that a sample 52 can be filled inside. A gas supply pipe 61 is provided at the bottom of the reactor 59, and an exhaust pipe 62 is provided at the top. Nitrogen gas or oxygen gas is introduced into the reactor 59 through the gas supply pipe 61, and is discharged from the exhaust pipe 62 that communicates with the top of the reactor 59. A heater 55 for adiabatic control is provided around the reactor 59, and the temperature is controlled by a temperature controller 66. An amplifier 65 is connected to the temperature controller 66, and acquires data from thermocouples 53 a and 53 b provided in the test vessel 60 and the reactor 59, respectively. A temperature sensor 54 is provided inside the thermostatic bath 51. A heater 57 and a temperature regulator 63 are provided below the thermostatic bath 51, and the initial temperature inside the thermostatic bath 51 is set by the temperature sensor 54 and an initial temperature setter 67. A fan 58 is provided below the heater 57. The heat generation evaluation is carried out while the inside of the test container 60 is kept in an insulated state.

[0062] The heat generation property of the charcoal was evaluated by the following method. As the sample 52 , the carbonized material (1 g) was filled into a test container 60 . Nitrogen gas was introduced into the reactor 59 to replace the atmosphere in the reactor 59 with nitrogen gas. Under the nitrogen atmosphere, the carbonized material in the test vessel 60 was heated to 110°C. Next, oxygen gas was introduced into the reactor 59 to replace the atmosphere in the reactor 59 with oxygen gas, and the temperature rise history of the carbonized material was recorded. The time t from when the carbide in the test vessel 60 reaches 110 ° C to when it reaches 180 ° C 180 (min) was measured. Time t 180 The longer the time (minutes), the less likely the carbonized material is to generate heat.

[0063] [Table 2]

[0064] The higher the cumulative oxidation heat value, the higher the heat-generating property of the charcoal, and as the cumulative oxidation heat value decreases, the risk of spontaneous combustion decreases. The carbonized materials of Examples 1 to 3, which were carbonized in a water vapor atmosphere at 550°C or higher, showed a significantly lower cumulative oxidation heat value than the carbonized materials of Comparative Examples 1 to 3, which were carbonized in a nitrogen atmosphere at 500°C or higher, and the carbonized material of Comparative Example 4, which was carbonized in a water vapor atmosphere at 500°C.

[0065] In the heat generation evaluation, time t 180 The longer the time, the lower the heat generation property of the carbide. The carbonized materials of Examples 1 to 3, which were carbonized in a water vapor atmosphere at 550°C or higher, showed a longer carbonization time than the carbonized materials of Comparative Examples 1 to 3, which were carbonized in a nitrogen atmosphere at 500°C or higher, and the carbonized material of Comparative Example 4, which was carbonized in a water vapor atmosphere at 500°C. 180 has become longer.

[0066] Therefore, it was confirmed that when carbonizing biomass, the heat generation of the carbonized material can be reduced by using a water vapor atmosphere at 550°C or higher. Furthermore, according to the manufacturing method of this example, the volatile content of the carbonized product also tends to be lower, and it was confirmed that by using a water vapor atmosphere during carbonization, the carbonization temperature can be lowered when producing a carbonized product with a specific volatile content (for example, volatile content of 10.6 [wt%, DB] in Example 2).

[0067] In Reference Example 1, after obtaining the carbide, an oxidation treatment of the carbide is further required, which leads to an increase in the number of steps and equipment compared to the production methods of Examples 1 to 3. [Industrial Applicability]

[0068] The biomass carbide of the present invention can be used for power generation in power plants, steel mills, factories, etc. In addition, the biomass carbide of the present invention can be used in fields related to carbon-neutral fuels that replace fossil fuels, and in fields related to carbon materials that can immobilize carbon. [Explanation of symbols]

[0069] 10...carbonization furnace, 12...reaction tube, 17...data logger, 18...sample stage, 20...gas supply section, 21, 57...heater, 22...water supply unit, 24...nitrogen supply section, 30...cooling section, 32...processing section, 40...exhaust section, 50...spontaneous combustion test device, 51...thermostatic bath, 52...sample, 54...temperature sensor, 55...heater for thermal insulation control, 58...fan, 59...reactor, 60...test vessel, 61...gas supply pipe, 62...exhaust pipe, 63...temperature controller, 65...amplifier, 66...temperature controller, 67...initial temperature setting device, 100...carbonization device, 121...gas supply pipe, 122...gas exhaust pipe, 16A, 16B, 53a...thermocouple.

Claims

1. The method includes a step of carbonizing biomass in a water vapor atmosphere at 550°C or higher to obtain biomass charcoal. A method for producing biomass charcoal.

2. The temperature of the carbonization treatment is 600°C or higher. The method for producing biomass charcoal according to claim 1.

3. The biomass carbonized material is in the form of powder, pellets, briquettes, or chips. The method for producing biomass charcoal according to claim 1 or 2.

4. The volatile content of the biomass carbonized material is 30% by mass or less. The method for producing biomass charcoal according to any one of claims 1 to 3.

5. The volatile content of the biomass carbonized material is 15% by mass or less. The method for producing biomass charcoal according to claim 4.

6. When the biomass carbonized material is held in an oxygen atmosphere at 140°C for 15 minutes using a differential scanning calorimeter, the integrated value of the calorific value is 110 J / g or less. The method for producing biomass charcoal according to any one of claims 1 to 5.

7. The step of obtaining the biomass carbonized material is a step of introducing the biomass into a carbonization furnace, and then carbonizing the biomass while introducing water vapor into the carbonization furnace from the start of heating the biomass to the end of the carbonization treatment. The method for producing biomass charcoal according to any one of claims 1 to 6.

8. In the step of obtaining the biomass carbonized material, after the biomass is introduced into the carbonization furnace, water vapor is introduced into the carbonization furnace when the temperature of the biomass is lower than 50°C. The method for producing biomass charcoal according to any one of claims 1 to 6.

9. The molar ratio of hydrogen atoms to carbon atoms in the biomass carbonized material (moles of hydrogen atoms / moles of carbon atoms) is 0.50 or less. The method for producing biomass charcoal according to any one of claims 1 to 8.

10. The biomass is at least one selected from the group consisting of woody biomass, herbaceous biomass, agricultural crop residue biomass, and palm biomass. The method for producing biomass charcoal according to any one of claims 1 to 9.

11. The biomass is palm biomass. The method for producing biomass charcoal according to claim 10.

Images