Method for modifying wood pellets, wood pellets, and wood pellet swelling inhibitors

Abstract

To provide a ligneous pellet modification method that suppresses swelling of ligneous pellets, suppresses generation of powdered materials of ligneous pellets during transportation and / or storage, allows collection of the powdered materials of the ligneous pellets generated during transportation without scattering, and allows the ligneous pellets to be effectively used as a solid fuel.SOLUTION: A method for modifying ligneous pellets during transportation and / or storage comprises spraying a modifier containing an aqueous glycerin solution onto the ligneous pellets and powdered materials of the ligneous pellets produced during the transportation and / or storage.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for modifying wood pellets that can suppress the generation of powdered substances during transportation and / or storage, can recover the generated powdered substances, and can further suppress the swelling of wood pellets, wood pellets obtained by the method, and a swelling inhibitor for wood pellets.

Background Art

[0002] Wood pellets are obtained by compressing and forming sawdust and crushed wood into granules, and are formed into pellets by melting and fixing lignin and saccharides contained in the wood with heat. Pelletization makes transportation and storage easier, and it is used as an alternative fuel to fossil fuels.

[0003] During the transportation process by a bulk carrier or the like, the surface of wood pellets may be worn down by rubbing due to vibration and impact, and a part of them may be pulverized. The pulverization of wood pellets can also occur by breakage due to their own weight and external pressure during transportation. Most of the powdered substances generated from wood pellets during transportation fall and scatter due to vibration or the like while being transferred from the unloading equipment to the belt conveyor, and disappear before reaching the combustion equipment such as a power plant, substantially reducing the part that can be utilized as energy. In addition, such powdered substances of wood pellets have also been a cause of significantly deteriorating the working environment by depositing or rising in the equipment.

[0004] As a method for suppressing the scattering of powdered substances generated from wood pellets during transportation, for example, Patent Document 1 discloses an apparatus that generates a mist wall at the opening of a hatch with mist sprayed from a spray nozzle to suppress the dust generated in a warehouse such as a ship's hold from scattering outside through the opening of the hatch. Furthermore, for example, Patent Document 2 discloses an unloader dust prevention device that includes a water supply hose connected to a watering nozzle, a water supply pump, an outflow prevention valve that opens and closes according to the water pressure in the water supply hose, a hose winding machine, etc., which prevents the generation of dust when unloading dust-generating materials from a ship's hold or the like using an unloader. These conventional technologies were all aimed at preventing dust generation from wood pellets, etc., and did not involve recovering the generated powder or modifying the wood pellets themselves.

[0005] On the other hand, Patent Document 3 discloses a wood pellet recycling facility comprising: a storage hopper for collecting powder generated in a wood pellet storage and conveying facility; a moisture measuring hopper for receiving the powder from the storage hopper and measuring the moisture content of the powder; a water-adding means for adding water to the powder in the moisture measuring hopper so that it reaches a predetermined moisture content; a molding material storage hopper for receiving the powder that has been adjusted to the predetermined moisture content and stirred; and a molding machine for manufacturing wood pellets using the stored powder. The recycling equipment disclosed in Patent Document 3 is capable of reusing powdered material generated from wood pellets, but it requires extremely large equipment, making it difficult to install in existing factories and other facilities. Furthermore, wood pellets had the problem of rapidly absorbing water and swelling when watered, becoming brittle and easily crumbling. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6881688 [Patent Document 2] Japanese Patent Application Publication No. 63-022488 [Patent Document 3] Japanese Patent Publication No. 2020-132718 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In view of the above situation, the present invention aims to provide a method for modifying wood pellets that suppresses the swelling of wood pellets, suppresses the generation of powdered material during transportation and / or storage, and allows for the recovery of powdered wood pellets generated during transportation without scattering, and enables their effective use as solid fuel; wood pellets obtained by the wood pellet modification method; and a wood pellet swelling inhibitor. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the inventor focused on recovering the powder generated when storing and / or transporting wood pellets. By spraying a predetermined modifier onto the wood pellets, the scattering of the powder from the wood pellets can be minimized, and the generated powder can be fixed to the wood pellets themselves, allowing for effective use as a solid fuel. Furthermore, swelling of the wood pellets can also be suppressed, leading to the completion of the present invention.

[0009] The present invention (1) is a method for modifying wood pellets during transport and / or storage, characterized in that a modifying agent containing an aqueous glycerin solution is sprayed onto the wood pellets and the wood pellet powder generated during transport and / or storage. Furthermore, the present invention (2) is a wood pellet modification method according to the present invention (1), wherein a modifier is sprayed so that the amount of glycerin added is 800 to 30,000 mg / kg relative to the weight of the wood pellets. Furthermore, the present invention (3) is a wood pellet modification method according to the present invention (1) or (2), wherein the glycerin concentration of the modifier is 15 to 80% by weight. Furthermore, the present invention (4) is a wood pellet modified by the wood pellet modification method described in any of the present inventions (1) to (3). Furthermore, the present invention (5) is a wood pellet swelling inhibitor that is used when sprayed onto wood pellets during transportation and / or storage, and is characterized by containing an aqueous glycerin solution. The present invention will be described in detail below.

[0010] In this specification, "X~Y" means "greater than or equal to X and less than or equal to Y".

[0011] This invention relates to a method for modifying wood pellets during transportation and / or storage. The wood pellets mentioned above are not particularly limited and include conventionally known types, such as bark pellets, white pellets, and whole-wood pellets. The term "transportation" above means the transfer of the wood pellets by known means, such as bulk carriers, loading facilities, trucks, containers, etc., and "storage" means storing the wood pellets in storage tanks such as silos or hoppers by known means.

[0012] The present invention involves spraying a modifier onto the wood pellets and the wood pellet powder generated during transportation and / or storage. In the present invention, the modifier contains an aqueous glycerin solution. This process modifies the wood pellets by coating their surface with glycerin, thereby suppressing the generation of powder. Furthermore, by spraying the modifier onto any existing powder on the wood pellets, the powder can be fixed to the wood pellets themselves and recovered. Moreover, because the modifier contains an aqueous glycerin solution, it effectively suppresses the swelling of the wood pellets, thus functioning as a swelling inhibitor. A wood pellet swelling inhibitor containing an aqueous glycerin solution, used for spraying on wood pellets during transport and / or storage, is also part of the present invention. In the following explanation, unless otherwise specified, the term "modifier" also applies to "wood pellet swelling inhibitors."

[0013] In the present invention, it is preferable to spray the modifier so that the amount of glycerin added is 800 to 30,000 mg / kg relative to the weight of the wood pellets. If the amount of glycerin added is less than 800 mg / kg, the wood pellets may swell, making it difficult to adequately modify the wood pellets and recover the powdered material. If it exceeds 30,000 mg / kg, the expected effect cannot be expected. A more preferable lower limit for the amount of glycerin added is 1,000 mg / kg, and a more preferable upper limit is 25,000 mg / kg.

[0014] Furthermore, it is preferable that the glycerin concentration of the above-mentioned modifier be 15 to 80% by weight. If it is less than 15% by weight, the wood pellets may swell, making it difficult to adequately modify the wood pellets and recover the powdered material. If it exceeds 80% by weight, the viscosity of the modifier becomes too high, making it impossible to spray. A more preferable lower limit for the glycerin concentration of the above-mentioned modifier is 20% by weight, and a more preferable upper limit is 60% by weight.

[0015] In the present invention, the glycerin may be glycerin and / or diglycerin. Furthermore, the modifier containing the above-mentioned aqueous glycerin solution may also contain water repellents, preservatives, antioxidants, surfactants, and thickeners, as long as they do not impair the effects of the present invention.

[0016] As for the spraying method of the above-mentioned modifier, conventionally known spraying methods can be used. For example, wood pellets stored in bulk carriers may be sprayed using spraying means such as spray nozzles or rain guns, or wood pellets on transport means such as belt conveyors may be sprayed using spraying means such as spray nozzles.

[0017] The method for modifying wood pellets of the present invention sprays the above-mentioned modifier onto the wood pellets or their pulverized products during transportation and / or storage, so that the wood pellets can be modified without swelling, and the generation of pulverized products can be preferably suppressed. Further, by spraying the above glycerin aqueous solution onto the already generated pulverized products of wood pellets, the pulverized products can be fixed to the wood pellets and recovered.

Advantages of the Invention

[0018] According to the present invention, swelling of wood pellets can be suppressed, generation of pulverized products during transportation and / or storage can be suppressed, and the pulverized products of wood pellets generated during transportation can be recovered without scattering, and can be effectively utilized as solid fuel.

Embodiments for Carrying Out the Invention

[0019] Examples of the present invention are shown below and will be described more specifically, but the present invention is not limited thereto.

Examples

[0020] After pulverizing wood pellets with a crusher, they were passed through a sieve with a mesh size of 250 μm to produce pulverized products of wood pellets. 1 g of the pulverized products of wood pellets prepared was added to 100 g of wood pellets to prepare a simulated sample.

[0021] (Example 1) 60 g of commercially available glycerin (reagent grade, manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 40 g of deionized water and mixed to prepare a 60% glycerin aqueous solution, which was used as a modifier. Using a commercially available spray bottle, the 60% glycerin aqueous solution was sprayed onto the simulated sample so that the glycerin addition amount shown in Table 1 was obtained, and then left standing for 10 minutes. The state of cracks and expansion on the surface of the wood pellets was observed (swelling test). The simulated sample sprayed with the glycerin aqueous solution was placed on the flow table of a mortar flow test solution (manufactured by Kansai Equipment Manufacturing Co., Ltd., KC-24), and 100 amplitude shocks were applied. Subsequently, the entire volume was passed through a sieve with a mesh size of 250 μm to collect the powdered unfixed wood pellets, and its weight was measured. The fixation rate (%) was then calculated using the following formula (fixation test). Note that the Blank test was performed using only the simulated sample, without spraying with glycerin aqueous solution.

number

[0022] (Examples 2-3) The wood pellets according to Examples 2 and 3 were modified in the same manner as in Example 1, except that the glycerin aqueous solution used had the glycerin concentrations shown in Table 1. (Comparative Example 1) The wood pellets according to Comparative Example 1 were modified in the same manner as in Example 1, except that tap water was used instead of an aqueous glycerin solution.

[0023] [Table 1]

[0024] As shown in Table 1, in the adhesion test, Examples 1-3 showed a tendency for the wood pellet powder to adhere well. On the other hand, Comparative Example 1 (water only) showed a slight increase in the amount of powder compared to Blank. This is presumed to be because the wood pellets became brittle due to water spraying and partially disintegrated. In the swelling test, no swelling or cracking was observed in Examples 1-3, but swelling and cracking were observed in Comparative Example 1.

Claims

1. A method for modifying wood pellets during transportation and / or storage, A modifier containing an aqueous glycerin solution is sprayed onto the wood pellets and the wood pellet powder generated during transportation and / or storage. The modifier is sprayed so that the amount of glycerin added is 800 to 30,000 mg / kg relative to the weight of the wood pellets. A method for modifying wood pellets, characterized by suppressing the swelling of the wood pellets.

2. The wood pellet modification method according to Claim 1, wherein the modifier is sprayed so that the amount of glycerin added is 1,000 to 25,000 mg / kg relative to the weight of the wood pellets.

3. A wood pellet swelling inhibitor used as a modifier in a method for modifying wood pellets during transportation and / or storage, A modifier containing an aqueous glycerin solution is sprayed onto the wood pellets and the wood pellet powder generated during transportation and / or storage. A wood pellet swelling inhibitor, characterized by containing an aqueous glycerin solution, used as a wood pellet modification agent in a wood pellet modification method, characterized by spraying the modifier so that the amount of glycerin added is 800 to 30,000 mg / kg relative to the weight of the wood pellets.

4. The wood pellet swelling inhibitor according to Claim 3, wherein the modifier is sprayed so that the amount of glycerin added is 1,000 to 25,000 mg / kg relative to the weight of the wood pellets.

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