Biochar manufacturing method

Abstract

Provided is a biochar production method with which it is possible to produce pH-stable biochar even at a relatively low heating temperature. A biochar production method according to the present disclosure comprises: a step for mixing a land biomass, which is a land-derived raw material, and a marine biomass, which is a marine-derived raw material; and a step for heating the mixed raw material in a low-oxygen atmosphere at 300 DEG C to 350 DEG C (inclusive).

Description

Technical Field

[0001] The present disclosure relates to a method for producing biochar. Background Art

[0002] In recent years, the development of biochar using biomass has been progressing.

[0003] For example, Patent Document 1 discloses a method for producing biochar mainly from land-derived biomass such as bamboo.

[0004] Patent Document 1: Japanese Patent Application No. 2014-531487 Summary of the Invention

[0005] The inventors have discovered the following problems regarding the method for producing biochar.

[0006] The technology disclosed in Patent Document 1 primarily uses terrestrial biomass, mixed with marine biomass. To utilize biochar as a soil conditioner, it is preferred that the biochar be stable and alkaline. Therefore, to achieve pH-stable biochar, the mixed biomass must be heated at high temperatures. However, to minimize energy input, there is a need for technologies that lower the heating temperature during biochar production.

[0007] The present disclosure is an invention made in view of such problems, and an object of the present invention is to provide a method for producing biocoke that can produce biocoke with stable pH even at a relatively low heating temperature.

[0008] One means for achieving the above-mentioned object is a method for producing biochar, comprising: mixing a raw material from land and a raw material from the ocean; and heating the mixed raw materials at 300° C. to 350° C. in a low-oxygen atmosphere.

[0009] According to the present disclosure, a biochar production method capable of producing biochar with stable pH even at a relatively low heating temperature can be provided.

[0010] The above and other objects, features and advantages of the present disclosure will be more fully understood from the detailed description given below and the accompanying drawings which are given by way of illustration only. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is an enlarged schematic diagram of an example of biochar according to an embodiment.

[0012] Figure 2 This is a flowchart showing an example of a biocoal production method according to an embodiment.

[0013] Figure 3 This is a graph showing an example of the surface potential and particle diameter of biomass. DETAILED DESCRIPTION

[0014] The following describes embodiments of the present disclosure in detail with reference to the accompanying drawings. Identical or corresponding elements are denoted by the same reference numerals in the various drawings, and duplicate descriptions are omitted as necessary for clarity. Furthermore, for ease of understanding, the scales of various parts in the drawings may sometimes differ from those in actual practice.

[0015] First, refer to Figure 1 The following describes an example of the structure of the biochar produced by the biochar production method according to the present embodiment, that is, the biochar according to the present embodiment. The biochar 10 according to the present embodiment is a charcoal produced using a biomass raw material and is suitable for a soil conditioner. Figure 1 As shown, the biocoal 10 includes marine biomass 20 (20a, 20b, 20c, 20d) and terrestrial biomass 30. The biocoal 10 is produced by heating a mixed biomass in which the marine biomass 20 and the terrestrial biomass 30 are mixed.

[0016] Marine biomass 20 is a raw material from the ocean. Marine biomass 20 is produced using, for example, seaweed. Terrestrial biomass 30 is a raw material from land. Terrestrial biomass 30 is produced using, for example, bamboo or sugarcane. Marine biomass 20 and terrestrial biomass 30 have different particle sizes. The method for measuring the particle sizes of terrestrial biomass 30 and marine biomass 20 is not particularly limited. The particle sizes of terrestrial biomass 30 and marine biomass 20 can also be measured, for example, as median diameters. For example, the median particle size of marine biomass 20 can be approximately 1 / 4 of that of terrestrial biomass 30.

[0017] exist Figure 1 , the diagram illustrates a case where the marine biomass 20 has a smaller particle size than the terrestrial biomass 30. However, the marine biomass 20 may also have a larger particle size than the terrestrial biomass 30. Since 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 when they have approximately the same particle size.

[0018] Because marine biomass 20 and terrestrial biomass 30 are made of different materials, they 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, and therefore the pH of the biochar 10, can be adjusted. Furthermore, because the marine biomass 20 and terrestrial biomass 30 are composited, there is no internal pH imbalance in the biochar 10. Therefore, when the biochar 10 is spread in the soil, the entire soil can be set to the target pH. In this way, since the entire biochar 10 reaches the target pH, it can fully demonstrate its effectiveness as a soil conditioner.

[0019] Next, refer to Figure 2 The process of the biochar production method involved in the present embodiment will be described. In the biochar production method involved in the present embodiment, first, the marine biomass 20 and the terrestrial biomass 30 are crushed (step S101). In step S101, the marine biomass 20 and the terrestrial biomass 30 are crushed in a manner such that each becomes a predetermined particle size, that is, a different particle size. Specifically, for example, the marine biomass 20 can also be crushed in a manner such that the median particle size becomes greater than 100 μm and less than 300 μm. In addition, the terrestrial biomass 30 can also be crushed in a manner such that the median particle size becomes greater than 300 μm.

[0020] Next, the properties of the marine biomass 20 and the terrestrial biomass 30 are measured (step S102). Specifically, in step S102, the pH of the marine biomass 20 and the terrestrial biomass 30 are measured. Based on the pH measurement results in step S102, the mixing ratio of the marine biomass 20 and the terrestrial biomass 30 is determined. In step S102, the charge of the marine biomass 20 and the terrestrial biomass 30 is preferably measured. The charge measurement results in step S102 can also be used to determine whether the marine biomass 20 and the terrestrial biomass 30 need to be subjected to charge removal treatment.

[0021] Next, at least one of the marine biomass 20 and the terrestrial biomass 30 may be subjected to static removal (step S103). Step S103 may also be performed when it is determined in step S102 that static removal is necessary. Figure 1 In the example shown, step S103 is performed after step S102, but step S103 may be performed in parallel with step S102 or before step S102. The means for removing static electricity is not particularly limited, but static electricity removal may be performed by, for example, using an ionizer to perform electrostatic adsorption.

[0022] exist Figure 3 In FIG, the relationship between the surface potential and particle size of each biomass is shown when only the terrestrial biomass 30 is de-electrified. Figure 3 In the example shown, the particle size of the terrestrial biomass 30 is larger than that of the marine biomass 20. Therefore, from the perspective of suppressing the energy required for static elimination, Figure 3 In the example shown, only terrestrial biomass 30 is subjected to charge removal. Terrestrial biomass 30 is typically positively charged. Therefore, using an ionizer for charge removal allows the terrestrial biomass 30 to be brought closer to electrical neutrality. Furthermore, marine biomass 20 is typically positively charged. By implementing step S103, the charge generated by the potential difference between the marine biomass 20 and the terrestrial biomass 30 can be more evenly mixed and composited.

[0023] In addition, although Figure 3 In the example shown, only the terrestrial biomass 30 is de-electrified. However, this can also be done only for the marine biomass 20, or for both the marine biomass 20 and the terrestrial biomass 30. Furthermore, to further strengthen the composite particle structure, the terrestrial biomass 30 can be negatively charged, while the marine biomass 20 can be uniformly positively charged. In this case, the electrostatic coupling between the terrestrial biomass 30 and the marine biomass 20 is further strengthened.

[0024] Return to Figure 2 To continue the explanation. 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 at 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 uniformly mixes and forms a composite. Therefore, there is no pH imbalance within the mixed biomass.

[0025] Biomass generally consists of a variety of components, and components are often locally distributed. Because the charge characteristics vary depending on the component ratios and local distribution, simply mixing different biomasses often results in particles positively charging each other upon contact, leading to particle aggregation. Therefore, to reliably combine different biomasses, it is preferable to adjust the charge state of each biomass before mixing.

[0026] Next, the mixed biomass can also be preheated (step S105). From the perspective of reducing the amount of energy input, step S105 is preferably implemented using the waste heat of the heating process (step S106) described later. Step S105 can also be implemented at around 150°C, for example. When the marine biomass 20 comes from seaweed, it contains polysaccharides such as alginic acid. Therefore, when step S105 is implemented, the mixed biomass can be combined by the polysaccharides contained in the marine biomass 20 before formal heating. In addition, the marine biomass 20 contains volatile odor components. Therefore, when step S105 is implemented, the odor unique to the marine biomass 20 can be removed before formal heating.

[0027] Next, the mixed biomass is heated, that is, formally heated (step S106). Step S106 is implemented at a low temperature in a low-oxygen atmosphere. Specifically, step S106 is implemented at a temperature of 300°C or higher and 350°C or lower. As described above, there is no pH imbalance inside the mixed biomass, and the pH is adjusted to a predetermined range. Therefore, even when heated at a low temperature, biochar with a stable alkaline pH will be obtained. In other words, there is no need to heat at a high temperature to bring out the alkalinity of the ash. In this way, the biochar manufacturing method involved in the present embodiment can produce biochar with stable pH even at a relatively low heating temperature. In addition, since the biochar manufacturing method involved in the present embodiment can produce biochar at a relatively low heating temperature, the volatile components can be suppressed, thereby increasing the product ratio.

[0028] In addition, the present disclosure is not limited to the above-described embodiment, and can be appropriately modified within a scope not departing from the gist of the present disclosure.

[0029] It is clear from the disclosure thus described that the disclosed embodiments can be modified in various ways. It is obvious that such modifications should not be regarded as departing from the spirit and scope of the present invention, and for those skilled in the art, all such modifications should be included in the appended claims.

Claims

1. A method for producing biochar, comprising: The process of mixing raw materials from land and marine sources; A step of heating the mixed raw materials at 300° C. to 350° C. in a low-oxygen atmosphere.

2. The method for producing biochar according to claim 1, wherein: The method further comprises the step of preheating the mixed raw materials before the heating step.

3. The method for producing biochar according to claim 1 or 2, wherein: The median particle size of the raw materials from land is 300 μm or more, The marine-derived raw material has a median particle size of 100 μm or more and 300 μm or less.

4. The method for producing biochar according to claim 1 or 2, wherein: The method further includes, before the mixing step, a step of removing static electricity from at least one of the raw material from land and the raw material from the ocean.

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