Method for manufacturing biocarbon

Abstract

To provide a method for manufacturing biocarbon that can manufacture biocarbon having stable pH even at a low heating temperature.SOLUTION: A method for manufacturing biocarbon includes: a step (S104) of mixing terrestrial biomass 30 which is a raw material originated from the land with marine biomass 20 which is a raw material originated from the ocean; and a step (S106) of heating the mixed raw material in a low oxygen atmosphere at 300°C or higher and 350°C or lower.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to methods for producing biochar. [Background technology]

[0002] In recent years, the development of biochar using biomass has been progressing. For example, Patent Document 1 discloses a method for producing biochar that mainly uses terrestrial biomass such as bamboo. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2014-531487 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have found the following problems regarding the method for producing biochar. The technology disclosed in Patent Document 1 involves mixing terrestrial biomass with mainly marine biomass. To use biochar as a soil conditioner, it is preferable for the biochar to be stable and alkaline. Therefore, the mixed biomass must be heated at high temperatures to produce biochar with a stable pH. However, to reduce energy input, there is a need to lower the heating temperature during biochar production.

[0005] The present disclosure has been made in consideration of these problems, and aims to provide a biochar production method that can produce biochar with a stable pH even at low heating temperatures. [Means for solving the problem]

[0006] One aspect of the present invention to achieve the above object is to 1. A method for producing biochar, comprising: mixing a terrestrially derived raw material with a marine-derived raw material; and heating the mixed raw materials at 300°C or higher and 350°C or lower in a low-oxygen atmosphere. [Effects of the Invention]

[0007] According to the present disclosure, a biochar production method can be provided that can produce biochar with a stable pH even at low heating temperatures. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an enlarged schematic view of an example of biochar according to an embodiment. [Figure 2] 1 is a flowchart illustrating an example of a biochar production method according to an embodiment. [Figure 3] 1 is a graph showing an example of the surface potential and particle diameter of biomass. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary. In addition, for ease of understanding, the scale of each part in the drawings may differ from the actual scale.

[0010] First, referring to FIG. 1, an example of the configuration of biochar produced by the biochar production method according to the present embodiment, i.e., biochar according to the present embodiment, will be described. Biochar 10 according to the present embodiment is charcoal produced using biomass raw materials and is suitable as a soil conditioner. As shown in FIG. 1, biochar 10 includes marine biomass 20 (20a, 20b, 20c, 20d) and terrestrial biomass 30. Biochar 10 is produced by heating a mixed biomass of marine biomass 20 and terrestrial biomass 30.

[0011] The marine biomass 20 is a raw material of marine origin. The marine biomass 20 is produced using, for example, seaweed. The terrestrial biomass 30 is a raw material of terrestrial origin. The terrestrial biomass 30 is produced using, for example, bamboo or sugarcane. The marine biomass 20 and the terrestrial biomass 30 have different particle sizes. There is no particular limitation on the method for measuring the particle sizes of the terrestrial biomass 30 and the marine biomass 20. The particle sizes of the terrestrial biomass 30 and the marine biomass 20 may be measured as, for example, a median diameter. For example, the median particle size diameter of the marine biomass 20 may be about ¼ that of the terrestrial biomass 30.

[0012] 1 illustrates a case where the marine biomass 20 has a smaller particle size than the terrestrial biomass 30. However, the marine biomass 20 may have a larger particle size than the terrestrial biomass 30. Because the marine biomass 20 and the terrestrial biomass 30 have different particle sizes, the marine biomass 20 and the terrestrial biomass 30 are more uniformly mixed and composited than if the marine biomass 20 and the terrestrial biomass 30 had approximately the same particle size.

[0013] Marine biomass 20 and terrestrial biomass 30 are composed of different materials and therefore typically have different pH values. Therefore, by adjusting the ratio of the mixed marine biomass 20 and terrestrial biomass 30, the pH of the mixed biomass, i.e., the pH of biochar 10, can be adjusted. Furthermore, because biochar 10 is a composite of marine biomass 20 and terrestrial biomass 30, there is no internal pH imbalance. Therefore, when biochar 10 is spread on soil, the entire soil can be adjusted to the desired pH. Because biochar 10 has a desired pH throughout, it can be fully effective as a soil conditioner.

[0014] Next, the flow of the biochar production method according to this embodiment will be described with reference to Figure 2. In the biochar production method according to this embodiment, first, marine biomass 20 and terrestrial biomass 30 are pulverized (step S101). In step S101, the marine biomass 20 and terrestrial biomass 30 are pulverized to respective predetermined particle sizes, i.e., different particle sizes. Specifically, for example, the marine biomass 20 may be pulverized to a median particle size diameter of 100 µm or more and 300 µm or less. The terrestrial biomass 30 may be pulverized to a median particle size diameter of 300 µm or more.

[0015] Next, the characteristics of the marine biomass 20 and the terrestrial biomass 30 are measured (step S102). Specifically, in step S102, the pH of each of the marine biomass 20 and the terrestrial biomass 30 is measured. Based on the pH measurement results in step S102, the mixing ratio of the marine biomass 20 and the terrestrial biomass 30, etc., is determined. In step S102, it is also preferable to measure the electric charges of each of the marine biomass 20 and the terrestrial biomass 30. Based on the electric charge measurement results in step S102, it may be determined whether or not static elimination processing of the marine biomass 20 and the terrestrial biomass 30 is necessary.

[0016] Next, at least one of the marine biomass 20 and the terrestrial biomass 30 may be de-electrified (step S103). Step S103 may be performed when it is determined in step S102 that de-electrification processing is necessary. In the example shown in FIG. 1, step S103 is performed after step S102, but step S103 may be performed in parallel with step S102 or may be performed before step S102. The means for de-electrification is not particularly limited, and may be, for example, de-electrified by electrostatic adsorption using an ionizer.

[0017] Fig. 3 shows the relationship between the surface potential and particle size of each biomass when only the terrestrial biomass 30 is neutralized. In the example shown in Fig. 3, the terrestrial biomass 30 has a larger particle size than the marine biomass 20. Therefore, from the viewpoint of reducing the amount of energy required for neutralization, Fig. In the example shown in Fig. 1, only the terrestrial biomass 30 is de-electrified. The terrestrial biomass 30 is normally positively charged. Therefore, by de-electrifying it using an ionizer, the terrestrial biomass 30 is brought closer to electrical neutrality. Furthermore, the marine biomass 20 is normally positively charged. By performing step S103, the marine biomass 20 and the terrestrial biomass 30 can be more uniformly mixed and combined due to the charging caused by the potential difference between them.

[0018] 3, only the terrestrial biomass 30 is neutralized, but only the marine biomass 20 may be neutralized, or both the marine biomass 20 and the terrestrial biomass 30 may be neutralized. Furthermore, in order to further strengthen the particle combination, the terrestrial biomass 30 may be negatively charged and the marine biomass 20 may be uniformly positively charged. In this case, the electrostatic bond between the terrestrial biomass 30 and the marine biomass 20 becomes stronger.

[0019] Returning to Figure 2, the explanation continues. Next, the marine biomass 20 and the terrestrial biomass 30 are mixed (step S104). In step S104, the marine biomass 20 and the terrestrial biomass 30 are mixed in a mixing ratio determined based on the pH measured in step S102 to form a mixed biomass. Because the marine biomass 20 and the terrestrial biomass 30 have different particle sizes, the mixed biomass is a composite in which the marine biomass 20 and the terrestrial biomass 30 are uniformly mixed together. Therefore, there is no bias in the pH inside the mixed biomass.

[0020] Generally, biomass contains various components, and these components are often localized. Because the charging characteristics change depending on the content ratio and localization of the components, simply mixing different biomass particles often results in particles coming into contact with each other and exerting a positive electrical influence on each other, causing particle aggregation, etc. Therefore, in order to reliably combine different biomass particles, it is preferable to adjust the charging state of each biomass before mixing them.

[0021] Next, the mixed biomass may be preheated (step S105). From the viewpoint of reducing energy input, step S105 is preferably performed using waste heat from the heating step (step S106) described below. Step S105 may be performed at, for example, about 150°C. When the marine biomass 20 is derived from seaweed, it contains polysaccharides such as alginic acid. Therefore, by performing step S105, the polysaccharides contained in the marine biomass 20 can bind the mixed biomass before the main heating. Furthermore, the marine biomass 20 contains volatile odor components. Therefore, by performing step S105, the odor unique to the marine biomass 20 can be removed before the main heating.

[0022] Next, the mixed biomass is heated, i.e., main heating (step S106). Step S106 is performed at a low temperature in a low-oxygen atmosphere. Specifically, step S106 is performed at a temperature between 300°C and 350°C. As described above, the mixed biomass has no internal pH imbalance and the pH is adjusted to a predetermined range. Therefore, even when heated at a low temperature, biochar with a stable alkaline pH is produced. In other words, there is no need to heat at a high temperature to extract the alkalinity of the ash. As such, the biochar production method according to this embodiment can produce biochar with a stable pH even at a low heating temperature. Furthermore, because the biochar production method according to this embodiment can produce biochar at a low heating temperature, it is possible to suppress volatile components and increase the product ratio.

[0023] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0024] 10. Biochar 20 Marine Biomass 30 Terrestrial biomass

Claims

1. mixing a terrestrially derived raw material with a marine-derived raw material; and heating the mixed raw materials at 300°C or higher and 350°C or lower in a low-oxygen atmosphere. Biochar production methods.

2. The method further comprises a step of preheating the mixed raw materials prior to the heating step. The method for producing biochar according to claim 1.

3. The median particle size of the terrestrially derived raw material is 300 μm or more; The median particle size of the marine-derived raw material is 100 μm or more and 300 μm or less. The method for producing biochar according to claim 1 or 2.

4. The method further includes a step of destaticizing at least one of the terrestrial-derived raw material and the marine-derived raw material prior to the mixing step. The method for producing biochar according to claim 1 or 2.

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