WO2021161660A1

WO2021161660A1 - Method for producing biomass fuel

Info

Publication number: WO2021161660A1
Application number: PCT/JP2020/047739
Authority: WO
Inventors: 志保池田; 吉田　拓也
Original assignee: 株式会社神戸製鋼所
Priority date: 2020-02-13
Filing date: 2020-12-21
Publication date: 2021-08-19

Abstract

One aspect of the present invention pertains to a method for producing a biomass fuel from a biomass, the method for producing a biomass fuel including a step for hot-pressure-forming a semi-carbonized biomass or an unreacted biomass, and being such that a formic acid aqueous solution and/or acetic acid aqueous solution is added to the semi-carbonized product or the unreacted biomass prior to the hot-pressure-forming step.

Description

Biomass fuel manufacturing method

The present invention relates to a method for producing biomass fuel from biomass.

Biomass is an organic substance of biological origin that can be used as a raw material and fuel. For example, wood, dried vegetation, agricultural waste, livestock waste, food / beverage waste, initial sludge in biological wastewater treatment facilities and sewage treatment plants, organic sludge such as surplus sludge, and its dehydrated sludge. Corresponds to.

Recently, in _{order to reduce CO 2} emissions, attempts have been made to co-fire biomass in coal-fired power plants (Patent Document 1). Among biomass, especially plant-derived biomass can effectively utilize carbon resources converted from carbon dioxide by photosynthesis during the plant growth process, so even if it is burned as fuel, carbon dioxide in the atmosphere can be seen in terms of the overall carbon dioxide balance. Will not be increased (carbon neutral).

However, compared to coal, biomass has features such as high water content, low density, low calorific value, low pulverizability, high hydrophilicity, high biodegradability, and high alkali content, making it difficult to use directly, and it is also difficult to transport and transport. There are also problems with storage and handling. One of the conventional techniques for solving these problems is semi-carbonization treatment and consolidation molding as biomass pretreatment methods.

Semi-carbonization treatment can be expected to have effects such as imparting hydrophobicity, lowering water content, lowering biodegradability, and improving pulverizability, in addition to improving the energy density per mass of biomass. In particular, by improving the crushability, it is possible that the use of existing crushers in coal-fired power plants and a high co-firing rate can be achieved at the same time. Specifically, when wood chips (crushed wood biomass) are crushed together with coal with an existing coal crusher, the upper limit is a co-firing rate of 2 to 3 cal%, but wood semi-carbonized pellets (wood chips). In the case of semi-carbonized and compacted), there is a report that a co-firing rate of 10 to 30 cal% is possible (Non-Patent Document 1).

In addition, consolidation molding can improve the energy density per volume of biomass. There are various reports on factors that influence the molding of biomass (Non-Patent Document 2).

By the semi-carbonization treatment and consolidation molding as described above, the properties of biomass as a fuel can be improved.

Further, it is characterized in that a carbide of biomass is crushed, a flocculant is mixed with the pulverized carbide to agglomerate the particles to form an agglomerate, and the agglomerate is compactly molded to obtain a solidified carbide. A method for producing a solidified carbide product has also been reported so far (Patent Document 1).

However, the semi-carbonization treatment strongly affects the moldability of biomass, and in particular, the biomass semi-carbonization obtained by the dry semi-carbonization treatment has low moldability, which may lead to problems such as a risk of dust explosion during handling (non-carbonization). Patent Document 2). In order to improve the moldability and obtain the required strength, a binder is required at the time of molding, which is a factor of increasing the cost.

As the binder of this biomass semi-carbide, castor bean cake (CAS) (Non-Patent Document 3 and Non-Patent Document 4) and the like are known. Further, regarding the method of adding the binder, the solid binder is heated. Treatments such as dissolving (Non-Patent Documents 5 and 6) and dissolving in water (Non-Patent Document 7) are required. Further, in order to sufficiently mix the biomass sample and the binder, stirring for 15 minutes is performed every 12 hours. It may be necessary to carry out the mixing treatment at least 6 times (Non-Patent Document 5), or to allow the mixture to stand in an environment of 4 ° C. for 24 hours after stirring for 20 minutes (Non-Patent Document 8).

Further, in Patent Document 1, although the biomass carbide is examined, the unreacted biomass and the semi-carbide are not examined. Here, the difference between biomass carbide, semi-carbonized biomass, and unreacted biomass is that unreacted biomass (woody) is composed of cellulose (fiber), hemicellulose, and lignin, and is semi-carbonized biomass (carbonized at ~ 280 ° C.). Hemicellulose and lignin are decomposed, but cellulose (fiber) remains. On the other hand, in the case of carbides (generally, biomass that has been carbonized at 400 ° C or higher), the fiber structure in the biomass is broken by the carbonization reaction and becomes more carbonic. It is unclear whether similar treatments with biomass and unreacted biomass will yield similar results.

The present invention has been made by paying attention to the above-mentioned problems, and an object of the present invention is to provide a method for efficiently obtaining high-strength biomass fuel from semi-carbonized biomass or unreacted biomass at low cost. It is to be.

Japanese Unexamined Patent Publication No. 2019-59880

The present inventors have made extensive studies and found that the above problems can be solved by the following configuration.

That is, the method for producing a biomass fuel according to one aspect of the present invention includes a step of hot pressure molding a biomass semi-carbohydrate or unreacted biomass, and before the step of hot pressure molding, an aqueous formatic acid solution and acetic acid. It is characterized in that at least one of the aqueous solutions is added to the semi-carbohydrate or the unreacted biomass.

FIG. 1 is a graph showing the crush strength ratio of each Example and Comparative Example in Test Example 1. FIG. 2 is a graph showing the crush strength ratio of each Example and Comparative Example in Test Example 3. FIG. 3 is a graph showing the crush strength ratio of each Example and Comparative Example in Test Example 4. FIG. 4 is a graph showing the relationship between the molding temperature and the crushing strength ratio of the biomass semi-carbide in Test Example 4. FIG. 5 is a graph showing the relationship between the molding temperature and the crushing strength ratio of unreacted biomass in Test Example 4. FIG. 6 is a graph showing the crush strength ratio of each Example and Comparative Example in Test Example 5.

As described above, the method for producing a biomass fuel of the present embodiment includes a step of hot pressure molding a biomass semi-carbohydrate or unreacted biomass, and prior to the step of hot pressure molding, an aqueous formatic acid solution and acetic acid. It is characterized in that at least one of the aqueous solutions is added to the semi-carbohydrate or the unreacted biomass.

With such a configuration, the strength of the obtained biomass fuel can be greatly improved as compared with the conventional case. Since the formic acid aqueous solution and the acetic acid aqueous solution are liquids, they can be directly added to semi-carbide or unreacted biomass, and complicated mixing treatment such as when using a solid binder such as CAS or glycerol which has been used in the prior art is required. It is efficient because it is not.

The reason why high-strength biomass fuel can be obtained by adding formic acid and / or acetic acid is that formic acid and acetic acid are constituents of biomass during pressure molding at about 150 ° C.・ It is considered that it acts on lignin) and the binding structure becomes stronger. Specifically, the addition of acid causes relaxation of the cellulose fiber structure in the semi-carbide or unreacted biomass, and relaxation of the bond between cellulose, hemicellulose, and lignin, and by pressure-molding this, the fibers are closer to each other. It is considered that this is because a high-strength structure can be obtained.

Hereinafter, embodiments of the present invention will be described in more detail, but the present invention is not limited thereto. Unless otherwise specified in the present specification, "A to B" representing a numerical range means "A or more and B or less".

(Biomass raw material)
The biomass used in this embodiment is not particularly limited, but is preferably plant-derived biomass. Plant-derived biomass refers to plant-derived organic resources, including wood, dried vegetation, agricultural or forestry waste. The biomass typically contains cellulose, hemicellulose and lignin as the main components.

Specifically, for example, thinned wood, pruned branches, waste wood, bark chips, other wood, bamboo, grass, palm husks, palm oil residue (EFB: Empty Fruit Bunch), waste vegetables due to overproduction, vegetable waste, etc. Examples thereof include cut vegetables, fruits, shavings, straw, rice straw, and paddy husks. Among these plant-derived biomasses, it is preferable to use woody biomass, EFB, etc. from the viewpoint of abundant resources.

In this embodiment, unreacted biomass or biomass semi-carbide may be used for the hot pressure molding step described later. In the present specification, the “unreacted biomass” refers to biomass in a state where no chemical reaction due to carbonization or semi-carbonization has occurred. However, for example, crushed biomass or treated such as evaporating water content (adjustment of water content, etc.) is included in the "unreacted biomass" of the present embodiment.

When the unreacted biomass is used, it is directly subjected to the hot pressure molding step described later, or if necessary, it is crushed to an appropriate size by a crushing means, and / or the water is evaporated appropriately. After that, it may be subjected to the hot pressure molding step described later. On the other hand, when a semi-carbide is used, the step of semi-carbonizing the biomass raw material is performed first.

(Semi-carbonization process)
In this step, the above-mentioned biomass raw material is subjected to semi-carbonization treatment. The semi-carbonization treatment of the present embodiment is not particularly limited, and may be dry semi-carbonization or wet semi-carbonization. In particular, it is desirable to carry out dry semi-carbide from the viewpoint that this embodiment is effective for carbides that are dry semi-carbides and have low granulation properties. Since it is known that a molded product of a wet semi-carbide can obtain the required strength (strength that can withstand transportation) without a binder, the present embodiment mainly targets dry semi-carbonization.

The biomass raw material may be subjected to semi-carbonization treatment as it is, but if necessary, it may be used after being crushed to an appropriate size by a crushing means.

As the semi-carbonization treatment, the semi-carbonization method conventionally used for the production of biomass can be used without particular limitation. Specifically, to give an example of the dry semi-carbonization treatment, semi-carbonization may be carried out in an inert atmosphere in a temperature range of 200 to 300 ° C. for about 10 to 60 minutes. The inert atmosphere here refers to a gas that does not react with the biomass raw material, such as nitrogen or carbon dioxide. Moreover, superheated steam may be used in order to raise the temperature rapidly to the carbonization temperature.

(Addition of formic acid aqueous solution and / or acetic acid aqueous solution)
Then, at least one of a formic acid aqueous solution and an acetic acid aqueous solution is added to the semi-carbide or unreacted biomass of the biomass obtained above.

The method of addition is not particularly limited, but since the formic acid aqueous solution and the acetic acid aqueous solution are liquids, they can be added directly to the semicarbide or unreacted biomass. The addition amount (addition rate) of at least one of formic acid and acetic acid is preferably about 1 to 26 wt% / db (dry base) with respect to the semi-carbide. In addition, when it contains water, it may be referred to as a wet base (wb) as opposed to a dry base (db) of a dry base, but the methods described in Examples described later are used for each calculation method. If the amount added is less than 1 wt% / db, the strength improvement rate of the molded product is small, and the required strength (for example, strength that can withstand transportation) may not be obtained. On the other hand, if it exceeds 26 wt% / db, Since the liquid content of the semi-carbide or unreacted biomass increases too much, the strength tends to decrease, which is not preferable. The lower limit of the more preferable addition amount is 4 wt% / db, and the more preferable upper limit is 22 wt% / db.

When an aqueous solution of formic acid or an aqueous solution of acetic acid is used, their concentrations are not particularly limited as long as the addition rate of formic acid and / or acetic acid is within the above range. For example, when an aqueous solution of formic acid is used, the concentration of formic acid may be about 30 to 70% by weight, and when an aqueous solution of acetic acid is used, the concentration of acetic acid may be about 30 to 70% by weight.

Either one of the formic acid aqueous solution and the acetic acid aqueous solution may be used alone, or both may be used in combination.

After adding at least one of the formic acid aqueous solution and the acetic acid aqueous solution, it is preferable to stir because it is mixed with the biomass semi-carbide or unreacted biomass. The stirring method is not particularly limited, and any means may be used as long as at least one of the formic acid aqueous solution and the acetic acid aqueous solution is uniformly mixed with the semicarbide or unreacted biomass. In the method of the present embodiment, since the aqueous solution is mixed instead of the solid binder, it is not necessary to stir for a long time as in the conventional method. For example, the sample in the beaker is stirred for an appropriate time using a spatula. That's enough.

Further, the production method of the present embodiment preferably includes a step of pulverizing at least one of the semicarbide and the unreacted biomass before adding at least one of the formic acid aqueous solution and the acetic acid aqueous solution. Thereby, it is considered that at least one of the formic acid aqueous solution and the acetic acid aqueous solution can be mixed more uniformly when the biomass semi-carbide or unreacted biomass is mixed.

This pulverization step may be performed on at least one of the semi-carbide and the unreacted biomass, for example, on the unreacted biomass or the biomass semi-carbide, or before semi-carbide. The biomass raw material may be crushed in advance.

The method for crushing unreacted biomass or semi-carbide is not particularly limited, and for example, it can be crushed using a blender, a mortar, a cutter mill, a ball mill, or the like.

The size of the obtained crushed product is also not particularly limited, but from the viewpoint that the strength of the molded product is improved when the particle size is smaller, it is preferable to crush the crushed product to a extent that the major axis is about 1 mm or less, for example.

The semi-carbide obtained in the semi-carbonization step is preferably added after cooling to about 100 ° C. or lower before adding at least one of the formic acid aqueous solution and the acetic acid aqueous solution.

Further, when the production method of the present embodiment includes the semi-carbohydrate step, the formic acid aqueous solution and / or the acetic acid aqueous solution to be added to the semi-carbohydrate is the formic acid aqueous solution and / or the formic acid aqueous solution contained in the volatile matter generated in the reaction in the semi-carbohydrate step. Alternatively, an aqueous acetic acid solution can be used. As a result, it is not necessary to add a new binder (formic acid aqueous solution and / or acetic acid aqueous solution), so that a significant reduction in manufacturing cost can be expected.

Regarding the method of using the formic acid aqueous solution and / or the acetic acid aqueous solution from the volatile matter, for example, the formic acid aqueous solution and / or the acetic acid aqueous solution is extracted from the furnace performing the semi-carbonization treatment, and the formic acid aqueous solution and / or the acetic acid aqueous solution and other main components contained in the volatile matter are used. The formic acid aqueous solution and / or the acetic acid aqueous solution can be recovered by utilizing the difference in boiling point from (phenols).

(Hot pressure molding process)

After the above-mentioned step of adding the formic acid aqueous solution and / or the acetic acid aqueous solution, hot pressure molding is performed. You may. As a result, there is an advantage that the semi-carbide granulated product can be made into a dense structure and a stronger granulated product can be obtained. The pulverizing means, the size after pulverization, and the like are not particularly limited, and may be appropriately adjusted depending on the desired granulated product or molded product.

The hot pressure molding of this embodiment is preferably performed in a temperature range of more than 100 ° C. and 200 ° C. or lower. If the temperature is 100 ° C. or lower, sufficient strength may not be obtained. On the other hand, the upper limit is not particularly limited, but if the temperature exceeds 200 ° C., the temperature becomes higher than necessary, resulting in wasteful energy consumption. It is preferably ℃ or less. The lower limit of the more preferable temperature range is 120 ° C., and the upper limit of the more preferable temperature range is 180 ° C.

When unreacted biomass is used, it is preferable to perform hot pressure molding at a temperature of 130 to 200 ° C., more preferably 135 ° C. or higher and 170 ° C. or lower. When a biomass semi-carbide is used, it is more preferable to perform hot pressure molding at a temperature of 125 to 200 ° C., and more preferably 130 ° C. or higher and 170 ° C. or lower.

In the present embodiment, the temperature of the hot pressure molding described above means the temperature of the mold used for molding. The temperature of the mold can be obtained by directly attaching the thermocouple to the mold and measuring, or the set temperature (target temperature) of the constant temperature bath containing the mold is set and the mold temperature is set in relation to the heating time. It can be adjusted by doing so. As a specific method, for example, the method described in the examples described later can be used.

The molding means or molding conditions in the hot pressure molding step of the present embodiment can be appropriately selected depending on the desired molded product, with the known methods and conditions as they are or modified. The shape and size of the molded product may be appropriately adjusted to a desired size.

For example, it is possible to granulate or mold biomass fuel by extrusion molding using a ring die or flat die type pelletizer, or briquette molding using a roll molding machine.

According to this embodiment, since the strength of the molded product after the molding process is excellent, there is an advantage that it is very easy to handle when transporting and using it as fuel.

(Biomass fuel)
The biomass fuel obtained by the method of this embodiment can be used as a fuel in various situations. The biomass fuel obtained by the production method of the present embodiment has extremely high strength and excellent moldability as compared with the conventional biomass solid fuel, and is therefore extremely useful in industry.

This specification discloses various modes of technology as described above, and the main technologies are summarized below.

According to such a configuration, it is possible to provide a method for efficiently obtaining high-strength biomass fuel from semi-carbonized biomass or unreacted biomass at low cost.

Further, in the production method, it is preferable to include a step of pulverizing at least one of the semicarbide and the unreacted biomass before adding at least one of the formic acid aqueous solution and the acetic acid aqueous solution.

Further, it is preferable that the amount of at least one of formic acid and acetic acid added is 1 to 26 wt% / db with respect to the semicarbide or the unreacted biomass.

Further, in the production method, it is preferable to perform the hot pressure molding at a temperature of more than 100 and 200 ° C. or less. Further, when unreacted biomass is used, the unreacted biomass is hot-press molded at a temperature of 130 to 200 ° C., or when a semi-carbide is used, the biomass semi-carbide is heated at a temperature of 125 to 200 ° C. It is preferable to perform hot pressure molding at.

Further, when a biomass semi-carbide is used in the above-mentioned production method, it is preferable to further include a step of semi-carbonizing the biomass raw material before the hot pressure molding step. In that case, it is preferable to use formic acid and acetic acid obtained from volatile substances generated during the semi-carbonization step as the formic acid and acetic acid.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Test Example 1)
[Manufacturing of biomass fuel from semi-carbide]
1. 1. Semi-carbonized treatment Using woody biomass pellets (moisture content of about 10% -db) as a raw material for biomass,
Semi-carbonization treatment under the following conditions was carried out (when water is contained, it is referred to as a wet base (wb) as opposed to a dry base (db) of a dry base).
Each calculation is as follows.
-Wb (wet base;%) = (sample weight-sample absolute dry weight) / sample weight x 100
DB (dry base;%) = (sample weight-sample absolute dry weight) / sample absolute dry weight x 100

As the device, a small dry distillation furnace (high frequency dielectric heating device IMC-ASH-103 type, IMEX Co., Ltd.) was used.

Four quartz containers (inner size φ47.7 mm, height 140 mm, internal volume 200 ml) were filled with samples of about 120 g-wb each, placed in a graphite crucible, and set in a small carbonization furnace. The nitrogen flow rate during the test was 2 L / min.

Temperature condition: The temperature was raised to the target temperature (about 260 ° C.) at a heating rate of 5 ° C./min, and then held for 30 to 60 minutes to obtain a semi-carbide of woody biomass. The measurement of the holding time was started when the sample temperature reached the target temperature of −10 ° C.

2. Milling of semi-carbide The semi-carbide obtained above was pulverized with a blender to obtain a pulverized product under a 1 mm sieve.

3. 3. Addition of formic acid / acetic acid aqueous solution Pure water or formic acid / acetic acid aqueous solution was added dropwise or sprayed to about 50 g-db of a semi-carbide (crushed product) at the addition rates shown in Tables 3 and 4 described later, and the mixture was stirred so as to be evenly mixed. .. Using a test example without the addition of an aqueous solution of formic acid and acetic acid (adding only pure water) as a comparative example, a semicarbide to which an aqueous solution of formic acid and acetic acid was added (formic acid and acetic acid addition rate 0 to 25 wt% -db) was prepared. , Used for the following molding test.

4. Molding and crushing strength test For the mold, the above 3. After preparing the samples of each of the Examples and Comparative Examples adjusted in 1 and heating in that state, the pressure molding machine (mold: custom order, hydraulic pump: RIKEN Seiki P-8, cylinder:) under the conditions shown in Table 1 below. Molding was performed using RIKEN Seiki SC3.6-30).

The pre-molding heating temperature in this test means the set temperature of the constant temperature bath when the pressure molding machine (mold) in which the sample is charged is heated in the constant temperature bath before pressure molding. In this test condition, the time until the sample temperature in the mold reaches the target temperature is measured at the constant temperature bath set temperature (target temperature), and the pre-molding heating time is set according to the desired temperature. The heating temperature before molding was adjusted according to the above.
The relationship between each target temperature and the heating time when the pressure molding machine is used is shown in Table 2 below.

(* At 170 ° C, the two types of heating time are 70 minutes when there are multiple n numbers and n = 1, but when n = 2, the temperature history is recorded in the mold. This is because the target temperature was reached in 40 minutes because it remained.)

In this test, after the pressure molding machine inside the constant temperature bath reached the set temperature of the constant temperature bath, the pressure molding test was conducted outside the constant temperature bath. In this test, the above-mentioned preheating molding temperature is regarded as the hot pressure molding temperature (mold temperature).

Next, the strength of the obtained molded product was measured using a crush tester (manufactured by Furukawa Otsuka Iron Works, "LXA-500") and a dynamic strain measuring instrument (manufactured by Kyowa Electric Co., Ltd., "DPM-711B"). .. The crush strength value (measured value) is an average value of n = 5. The crush strength ratio was calculated with the crush strength at the time of pure addition as 1.

The results are summarized in Tables 3 and 4. The formic acid / acetic acid addition rate, water content, and aqueous solution addition rate of each sample in the table are all calculated values. Furthermore, Fig. 1 summarizes the crushing strength ratio to the formic acid / acetic acid addition rate.

(Discussion)
As shown in Tables 3 to 4 and FIG. 1, it was confirmed that the crushing strength of the obtained biomass molded product was improved by adding formic acid or acetic acid. In addition, from the results in Table 4, it was confirmed that formic acid has the effect of improving the crushing strength even when the water content and the aqueous solution addition rate are kept constant.

(Test Example 2)
Next, the temperature range in the hot pressure molding process was verified.

Specifically, the sample before pressure molding and the heating temperature before molding (mold temperature) were changed to 130 to 170 ° C. as shown in Table 5, but the molding was performed in the same manner as in Test Example 1. A crush strength test was conducted. The results are shown in Table 5. In the table, the formic acid addition rate is a calculated value, and the crushing strength value is a measured value (an average value of n = 5).

(Discussion)
As is clear from Table 5, it was confirmed that excellent strength can be obtained by adding the formic acid aqueous solution, especially when the temperature at the time of hot pressure molding is in the range of 150 to 170 ° C.

(Test Example 3)
Next, after adding the formic acid aqueous solution to the semi-carbide, in order to confirm whether the standing time is necessary for sufficient permeation, after adding the formic acid aqueous solution and stirring, (1) the mixture was allowed to stand in a sealed container for 1 day or more. The crushing strength was compared between the case where the molding test was carried out later and the case where the molding test was carried out immediately (2). The manufacturing method and the test method other than the presence or absence of the standing time were manufactured and evaluated in the same manner as in Test Example 1 above.

Table 6 below shows the presence or absence of standing time, the formic acid addition rate (calculated value) of each sample, the crushing strength value (measured value, average value of n = 5) and its standard deviation, and Fig. 2 (error bar is 2σ). Each crush strength value is shown.

(Discussion)
As is clear from the results of Table 6 and FIG. 2, it was confirmed that the strength of the molded product was improved by the addition of the formic acid aqueous solution regardless of the presence or absence of the standing time. That is, it was found that in the production method of the present invention, the standing time after the addition of the formic acid aqueous solution is unnecessary, and the biomass fuel can be produced easily and quickly.

(Test Example 4)
[Manufacturing of biomass fuel from unreacted biomass]
1. 1. Crushing of unreacted biomass As a raw material for biomass, woody biomass pellets (moisture content of about 10% -db) were crushed with a blender to obtain a crushed product under a 1 mm sieve.

2. Addition of formic acid / acetic acid aqueous solution Pure water or formic acid / acetic acid aqueous solution was added dropwise or sprayed to about 50 g-db of unreacted biomass (crushed product) at the addition rate shown in Table 9 described later, and the mixture was stirred so as to be evenly mixed. A test example in which no formic acid / acetic acid aqueous solution was added (only pure water was added) was used as a comparative example, and as an example, unreacted biomass to which a formic acid / acetic acid aqueous solution was added was prepared and used in the following molding test.

3. 3. Molding and crushing strength test For the mold, the above 2. After preparing the samples of each Example and Comparative Example adjusted in the above and heating in that state, the following Table 7 (Condition A: Used in the following evaluation test A) or Table 8 (Condition B: Used in the following evaluation test B) Molding was performed under the conditions shown. The pre-molding heating temperature in Table 7 (Condition A) has the same meaning as the pre-molding heating temperature of Test Example 1. The mold temperature in Table 8 is the thermocouple temperature installed in the mold. Under the condition B of Table 8, the pressure molding test was carried out in a state where the pressure molding machine in which the sample was charged was installed in the constant temperature bath.
Both the pre-molding heating temperature in Table 7 and the mold temperature in Table 8 are regarded as hot pressure molding temperatures.

(Evaluation test A)
The strength of the molded product obtained under the above condition A is measured using a crush tester (manufactured by Furukawa Otsuka Iron Works, "LXA-500") and a dynamic strain measuring instrument (manufactured by Kyowa Electric Co., Ltd., "DPM-711B"). bottom. The crush strength value (measured value) is an average value of n = 5. The crush strength ratio was calculated with the crush strength at the time of pure addition as 1.

The results are summarized in Table 9. The formic acid / acetic acid addition rate, water content, and aqueous solution addition rate of each sample in the table are all calculated values. Furthermore, Fig. 3 summarizes the crushing strength ratio to the formic acid / acetic acid addition rate.

(Discussion)
As shown in Table 9 and FIG. 3, it was confirmed that the crushing strength of the biomass molded product obtained from the unreacted biomass was improved by adding formic acid or acetic acid.

(Evaluation test B)
Next, the temperature range in the hot pressure molding process was verified. Specifically, the formic acid addition rate in the samples of semi-carbonized biomass and unreacted biomass and the temperature of the mold used for hot pressure molding are changed to 100 to 140 ° C. as shown in Table 10 to obtain the above. The molded product obtained under Condition B was subjected to a crushing strength test. The results are shown in Table 10 and FIGS. 4 to 5 (error bars are 2σ). In the table, the formic acid addition rate is a calculated value, and the crushing strength value is a measured value (an average value of n = 3). As the semi-carbide, the pulverized product obtained in the same manner as in Test Example 1 was used, and as the unreacted biomass, the pulverized product obtained in the same manner as in Test Example 4 was used.

(Discussion)
As shown in Table 10 and FIGS. 4 to 5, it was found that hot molding at a temperature of 125 ° C. or higher for biomass semi-carbide and 130 ° C. or higher for unreacted biomass further improved the molding strength by adding formic acid. On the other hand, neither the biomass semi-carbide nor the unreacted biomass could be molded at a temperature of 100 ° C. or lower because sufficient strength could not be obtained.

(Test Example 5)
[Manufacturing of biomass fuel from unreacted biomass 2]
1. 1. Raw material Cellulose powder was used as the biomass raw material.

2. Addition of formic acid / acetic acid aqueous solution Pure water or formic acid aqueous solution was added dropwise or sprayed to about 50 g-db of cellulose powder at the addition rate shown in Table 11 described later, and the mixture was stirred so as to be evenly mixed. Using a test example without the addition of an aqueous formic acid solution (adding only pure water) as a comparative example, unreacted biomass (raw cellulose) to which a 52% aqueous solution of formic acid and a 72% aqueous solution of formic acid were added was prepared and subjected to the following molding test. used.

3. 3. Molding and crushing strength test For the mold, the above 2. The samples of each Example and Comparative Example adjusted in 1 above were charged, heated in that state, and then molded under the conditions shown in Table 7 (Condition A).

Table 11 summarizes the formic acid addition rate, water content, aqueous solution addition rate, crush strength value (average value of n = 5), and crush strength ratio (the crush strength when pure water is added is 1) of each sample. Furthermore, FIG. 6 summarizes the crushing strength ratio to the formic acid addition rate.

(Discussion)
As shown in Table 11 and FIG. 6, it was confirmed that the addition of formic acid improved the crushing strength of the biomass molded product obtained from unreacted biomass (raw cellulose).

This application is based on Japanese Patent Application Patent Application No. 2020-022112 filed on February 13, 2020 and Japanese Patent Application Japanese Patent Application No. 2020-152537 filed on September 11, 2020. , The content thereof is included in the present application.

In order to express the present invention, the present invention has been appropriately and sufficiently described through the embodiments with reference to specific examples and the like, but those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that it can be done. Therefore, unless the modified or improved form implemented by a person skilled in the art is at a level that deviates from the scope of rights of the claims stated in the claims, the modified form or the improved form is the scope of rights of the claims. It is interpreted as being comprehensively included in.

The present invention has a wide range of industrial applicability in the technical field related to the energy industry such as biomass.

Claims

A method of producing biomass fuel from biomass,
Biomass Including the step of hot pressure molding of semi-carbide or unreacted biomass
A method for producing a biomass fuel, in which at least one of an aqueous solution of formic acid and an aqueous solution of acetic acid is added to the semi-carbohydrate or the unreacted biomass before the step of hot pressure molding.
The method for producing a biomass fuel according to claim 1, further comprising a step of crushing at least one of the semicarbide and the unreacted biomass before adding at least one of the formic acid aqueous solution and the acetic acid aqueous solution.
The method for producing a biomass fuel according to claim 1 or 2, wherein the addition amount of at least one of formic acid and acetic acid is 1 to 26 wt% / db with respect to the semicarbide or the unreacted biomass.
The method for producing a biomass fuel according to claim 1, wherein the hot pressure molding is performed at a temperature of more than 100 ° C. and 200 ° C. or lower.
The method for producing a biomass fuel according to claim 4, wherein the unreacted biomass is hot-press molded at a temperature of 130 to 200 ° C.
The method for producing a biomass fuel according to claim 4, wherein the biomass semi-carbide is hot pressure molded at a temperature of 125 to 200 ° C.
The method for producing a biomass fuel according to claim 1, further comprising a step of semi-carbonizing the biomass raw material before the hot pressure molding step when using the biomass semi-carbohydrate.
The method for producing a biomass fuel according to claim 7, wherein formic acid and acetic acid obtained from the volatile matter generated during the semi-carbonization step are used as the formic acid and acetic acid.