Manufacturing method of woody explosive pellet fuel

Abstract

To provide a simple and low-cost method for the production of a woody pellet fuel which attains a handling property and improvement in combustion heat generation amount per unit weight, the fuel having high water resistance and water repellency.SOLUTION: A production method of a woody explosive flame pellet comprises: putting a preheated or roasted bark pellet 1 into a waste oil 4 heated at 140°C to 280°C and carrying out frying treatment with oil (step S2 and step S3); removing the resultant pellet after carrying out the frying treatment with oil until 10 minutes or more measured from a time when foam generation becomes slight while checking a process in which foam generation amount decreases as vaporization of water proceeds (step S4); and placing a stainless steel colander 6 on another aluminum pan and separating the waste oil 4 and the bark pellet 1, yielding the explosive flame pellet (a product) 7 (step S5 and step S6).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing wood pellet fuel made from wood, particularly to explosive pellets that are easy to handle and have a high combustion heat value per unit weight. [Background technology]

[0002] In recent years, in order to prevent global warming and reduce carbon dioxide emissions into the atmosphere worldwide, various research and development efforts have been made on fuels that utilize biomass resources as renewable energy sources. Among these biomass fuels, wood fuels made from thinned wood, which is industrial waste that was previously simply incinerated, have attracted attention as an alternative fuel to fossil fuels such as oil and coal. In fact, in recent years, there has been an increase in afforestation and felling of thinned wood to produce white pellets.

[0003] The wood raw materials currently used in steam boilers, hot water boilers, heating equipment, and cooking heat sources are listed below. (a) Chip pellets are simply waste wood and thinnings generated during the process of manufacturing construction lumber, crushed to a specified size. (b) White pellets are made by crushing and compressing waste wood scraps, sawdust, packaging materials, and pallet waste generated during the process of manufacturing building lumber. (c) Bark pellets are made by crushing and compressing bark generated during the process of manufacturing building lumber. (d) Whole wood pellets made by mixing the crushed raw materials (b) and (c) and compressing them into solid form. (e) Wood pellets made by compressing and solidifying sawdust generated during the process of manufacturing building lumber, then torrefying them. (f) Charcoal made by carbonizing forest wood. (g) Dried tree branches (firewood) used for heating, etc. (h) Fuel made by compressing and solidifying rice husks. (i) Bamboo charcoal made by cutting bamboo to a specified length and lengthwise, roasting it at high temperature, and carbonizing it.

[0004] Generally, wood pellet fuel is a solid fuel made by crushing dried wood into fine powder and compressing it under pressure into a cylindrical shape with a diameter of 6 to 8 mm and a length of 10 to 25 mm.Compared to fuels made from other biomass resources, wood pellets are easier to handle and are suitable for long-distance transportation.In addition, because they are heat-treated and have a low moisture content, they can be stored for long periods of time.

[0005] Among alternative fossil fuels, the following have attracted particular attention: (b) white pellets (made from wood only, excluding bark), (c) bark pellets (made from bark only; see, for example, Patent Documents 1 and 2), and (d) whole wood pellets. These wood pellets are made by compressing and forming into granules the bark, sawdust, and scrap wood pulverized from thinning and sawmilling processes. Pellets are formed by melting and solidifying lignin, a component of wood, with heat (see, for example, Patent Document 3). Furthermore, (h) compressed rice husk fuel, made from rice husks generated during the rice and wheat milling process, is also attracting attention in regions where disposal is difficult. Compressed rice husk fuel is made by solidifying and forming rice husks using a screw compression method.

[0006] However, compared to fossil fuels, these wood pellets have the following problems: (1) The heat generated by combustion per unit weight is low. (2) The manufacturing process is complex, resulting in high costs. (3) When it comes into contact with water, it expands and loses its shape, making it difficult to store outdoors like coal.

[0007] Therefore, for example, a method has been proposed in which sawdust for wood pellets and sawdust for charcoal powder, i.e., charcoal, is added to improve the calorific value (see Patent Document 4). Other methods have been proposed, such as coating with vegetable oils such as palm oil, or fatty acids or esters derived from beef tallow or lard to improve water resistance (see Patent Document 5). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-266546 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-297532 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-40542 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-303305 [Patent Document 5] Japanese Patent Application Laid-Open No. 2008-7711 Summary of the Invention [Problem to be solved by the invention]

[0009] The above problems (1) and (2) can be solved by compressing and solidifying wood pellets, then roasting them at high temperatures in a reactor to semi-carbonize them, and turning them into torrefied pellets, or so-called black pellets, in order to improve the combustion heat value per unit weight. However, this method requires high installation costs for the reactor, and the running costs are also high, making it uneconomical compared to coal.

[0010] To address problem (3) above, a huge warehouse with a dedicated roof and walls is required for wood pellets. In other words, conventional wood pellets have the disadvantage of requiring more storage space than coal or other fossil fuels in order to obtain the same calorific value.

[0011] In view of the problems with the prior art as described above, the present invention aims to provide a method for producing wood pellet fuel that is simple and low-cost, improves handling properties and combustion heat output per unit weight, and is highly water-resistant. [Means for solving the problem]

[0012] Therefore, the first feature of the method for producing woody explosive pellet fuel of the present invention is that it is prepared by frying pelletized wood raw materials. This is because frying pyrolyzes and torrefies the pellet fuel in an oxygen-free environment. The second feature includes a step of preheating or roasting the pelletized wood raw materials, a step of frying the preheated wood raw materials with vegetable oil or animal oil (in this test, inexpensive waste oil was used; hereafter referred to as waste oil), and a step of removing excess waste oil adhering to the oil-fried wood raw materials. The third feature is that it is prepared by frying the pelletized wood raw materials with a flammable hardener synthetic oil liquid, which is obtained by adding a flammable hardener to waste oil. The fourth feature is that it is impregnated with a flammable hardener synthetic oil liquid. The wood raw materials are preferably at least one selected from bark, scraps, thinned wood, pruning wood, sawdust, construction waste, packaging waste, pallet waste, rice husks, and bamboo. [Effects of the Invention]

[0013] The present invention has the following excellent effects. (1) Because it is a fuel made from biomass resources (wood), it can reduce carbon dioxide emissions, making it an excellent fuel from an environmental perspective. (2) By frying wood pellets in oil, it is possible to obtain fuel with a higher calorific value than conventional wood pellets. This increases the calorific value per unit of fuel, thereby reducing storage space. (3) The moisture content of wood pellets is reduced to near the lower limit, making them less susceptible to tissue decomposition by microorganisms and enabling long-term storage. (4) The pellets are over-dried, contain oil, or contain tar, resulting in significantly improved water resistance and water repellency. This improves productivity and allows for outdoor storage, eliminating the need for large warehouses. [Brief explanation of the drawings]

[0014] Next, an embodiment of the present invention will be described based on the examples shown in the drawings. [Figure 1]1 is a flowchart showing a manufacturing process of woody explosive pellets according to the present invention. [Figure 2] 10 is a flowchart showing another manufacturing process of woody explosive pellets according to the present invention. [Figure 3] 10 is a flowchart showing another manufacturing process of woody explosive pellets according to the present invention. [Figure 4] 1 is an explanatory diagram showing a schematic diagram of an example of the configuration of a woody explosive pellet manufacturing apparatus according to the present invention. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0015] The method for producing woody explosive pellets according to the present invention will be described with reference to Fig. 1. Bark pellets 1 made solely from bark were used as the woody raw material.

[0016] First, 100 g of bark pellets 1 were weighed out using a tabletop scale and heated in a paper cup at 600 W for one minute in a microwave oven 2 to raise the temperature of the bark pellets 1 to nearly 100°C (step S1). This was done to reproduce the 70°C to 100°C temperature of the pellets discharged from a disk-rotating compression extrusion-type pelletizer in the process of producing conventional pellet fuel. One liter of waste oil 4 was placed in an aluminum pot 3 and heated on a gas stove 5, with the temperature maintained between 140°C and 150°C using a resistance thermometer. To measure the moisture content of control bark pellets identical to bark pellets 1, they were ground in a tabletop grinder and pre-weighed using a near-infrared moisture meter.

[0017] In step S1, preheated bark pellets 1 were placed into heated waste oil 4 for frying (steps S2 and S3). First, the moisture contained in the bark pellets 1 was evaporated. The temperature of the waste oil 4 initially dropped, but the heat of the gas stove 5 was adjusted to maintain a temperature range of 180°C to 240°C, while the appearance of bubbles from the evaporating moisture was monitored. Initially, bubbles from the evaporated moisture vigorously formed. However, as the moisture evaporation progressed, the amount of bubbles generated decreased. Once the bubbles decreased, the bark pellets were removed (step S4). A stainless steel colander 6 was placed on top of another aluminum pot, and the bark pellets fried in the waste oil 4 were placed on top of the colander 6. The waste oil 4 and bark pellets 1 were separated, yielding explosive pellets (product) 7 (steps S5 and S6). To remove as much of the waste oil 4 as possible from the bark pellets 1 remaining in the colander 6, the colander was vibrated up and down several times to remove the waste oil 4. It is considered that this process can be performed more efficiently using a centrifuge. After the waste oil 4 was removed, the pellets were cooled to obtain explosive pellets 7, which are the final product of the present invention.

[0018] The obtained explosive pellets 7 were transferred to a paper cup, and their weight was measured using a tabletop measuring instrument. Thereafter, in order to measure the moisture content of the obtained explosive pellets 7, the pellets were pulverized using a tabletop grinder and measured using a near-infrared moisture meter.

[0019] [Water repellency and hydrophobicity test] To confirm the water repellency and hydrophobicity of Explosive Pellets 7, a paper cup was filled with water and fried bark pellets (product) were placed in it to observe the change in shape and measure the time the shape was maintained. The target shape retention time in water was six hours. The combustion heat per unit weight was measured by an external testing institution. The target heat was 5,400 Kcal.

[0020] [Test result 1] After the frying process, the original dark brown color of bark pellet 1 had turned completely black. This discoloration was the result of the fine raw material being carbonized at temperatures above 180°C and tar being synthesized on the surface of the raw material. The calorific value of combustion per unit weight increased from 4200 Kcal before treatment to 5860 Kcal. This value is comparable to that of crude coal, highlighting the possibility of using it as a substitute for coal. The moisture content of the bark pellets before treatment was 13.2%, which decreased to 1.8% after treatment. Furthermore, the weight was 100g at first, but 102g after treatment, confirming an almost complete exchange of the evaporated moisture and the amount of waste oil that had permeated.

[0021] Here, the following three problems arose: Problem (1): No change was observed in the underwater shape retention for the water repellency and hydrophobicity check until two hours had passed, but after that the product gradually expanded and crumbled when picked up by hand after six hours, failing to achieve the target six-hour shape retention. Problem (2): It was discovered that fried bark pellets have a sticky surface due to the waste oil when the ambient temperature exceeds 30°C, making them difficult to handle. This problem can lead to bridging when the pellets are put into or discharged from a hopper, and can also lead to soil contamination when the pellets are stored outdoors due to the waste oil seeping into the ground. Problem (3) When the product is cooled naturally after frying and exposed to air, the product temperature is high, which may cause a risk of spontaneous combustion.

[0022] Therefore, in order to resolve the above three problems and further increase the combustion heat value per unit weight, the heating temperature range was expanded to 140°C to 280°C in order to gasify and eliminate the non-combustible (volatile) substances in the pellets.

[0023] To maintain shape retention underwater, the pellets were fried for a longer period of time to enhance their water-repellent properties by over-drying them, synthesizing more tar on the surface of the small particles and inside the pellets, increasing the proportion of carbonized wood components, and further melting the lignin at a higher temperature to impart viscosity and water-repellency and prevent moisture from penetrating into the pellets. The oil temperature was kept between 140°C and 160°C, and the amount of bubbles generated by evaporated water decreased. Measurements were taken from the point at which bubbles were minimized. The frying time was measured in 5-minute increments (5, 10, 15, and 20 minutes) with the oil temperature raised to and maintained between 180°C and 280°C. The reason for keeping the temperature between 140°C and 160°C at the time of feeding was to prevent sudden boiling or steam explosions when wood pellets with a high moisture content were added. In addition, the low-temperature frying process after the high-temperature frying process is carried out in order to lower the product temperature to prevent spontaneous combustion, and to address concerns that the flammable hardener added to the waste oil may evaporate and disappear during the high-temperature frying process, so the low-temperature frying process is carried out to mix and impregnate the waste oil with a flammable hardener. [Example]

[0024] The microwave oven 2 treatment of bark pellets 1 performed in Example 1 was carried out by roasting. Figure 2 shows the process. First, the heating roaster 2a was preheated (step T1). In order to evaporate the moisture contained in the bark pellets 1 in a short time, the temperature of the heat contact part of the heating roaster 2a was preheated to 240°C, and the pellets were placed in the heating roaster 2a and heated to a temperature of 180°C, evaporating the moisture and drying and roasting the pellets until the non-flammable (volatile) substances contained in the pellets began to gasify (steps T2 to T4).

[0025] The bark pellets 1 dried and roasted in steps (T1-T4) were placed in waste oil 4 heated in an aluminum pot 3A and fried using a gas stove 5a (steps T5 and T6). The temperature of the waste oil 4 was adjusted to 240-280°C while the heat of the gas stove 5a was adjusted for 5, 10, or 15 minutes, after which the pellets were removed from the pan 6a and the oil was separated (step T7). Next, waste oil containing a flammable hardener 8 was heated to 100-110°C in an aluminum pot 3B on another gas stove 5b. The pellets were fried in this synthetic oil until the temperature of the pellets reached 160°C or below, and then removed (steps T8 and T9). The waste oil 4 and the bark pellets 1 were separated into solid and liquid using a vibrating sieve 6c (step 10). The flammable hardener-added waste oil was removed, and the pellets were cooled to obtain the explosive pellets 7 (step 11).

[0026] To prevent waste oil from seeping out of the pellets, the pellets were fried in a synthetic oil solution to which flammable hardener 8 was added. The ratios of waste oil to flammable hardener were 9:1, 8:2, 7:3, and 6:4. This demonstrated that it was possible to prevent the seepage of waste oil up to 65°C, the melting point of flammable hardener 8. The reason the flammable hardener was added to the waste oil in the low-temperature frying process was to prevent the flammable hardener from volatilizing and gasifying at high temperatures during high-temperature frying, thereby reducing the effectiveness of the hardener.

[0027] After the frying process, the color of the bark pellet 1 changed from its original dark brown color to pitch black. The calorific value of combustion per unit weight increased from 4,200 Kcal before the process to 5,780 Kcal. This value is comparable to that of raw coal, and it was found to be a potential alternative to coal.

[0028] The moisture content of Bark Pellet 1 before treatment was 12.8%, which dropped to 1.2% after treatment. Additionally, the weight was 100g at first, but 101g after treatment, confirming that the amount of evaporated moisture and the amount of non-combustible (volatile) substances that had evaporated and disappeared were almost completely replaced by the amount of waste oil that had permeated.

[0029] Regardless of the blend ratio of combustible hardener 8 and oil, the fried bark pellets did not allow the waste oil to seep out of the surface even when the ambient temperature exceeded 30°C, and they remained smooth and dry, significantly improving handleability. The hardening effect of the waste oil 8 using the combustible hardener was effective.

[0030] To check the water repellency and hydrophobicity, the underwater shape retention was confirmed, and no change in shape was observed even after soaking in water for several days, and the target of 6 hours could be significantly extended. Frying times of 10 minutes or more produced significantly better results.

[0031] As mentioned above, the underwater shape retention for confirming water repellency and hydrophobicity showed that no change in shape was observed even when soaked in water for several days, and it was found that the target shape retention time of 6 hours could be significantly extended.Furthermore, frying for 10 minutes or more with oil temperature maintained at 240°C or higher was significantly better.

[0032] [Additional Experimental Results] As a result of the above experiments, the following facts became clear. (1) Bark pellets are pre-roasted and then fried in a synthetic oil mixture of waste oil and a flammable hardener 8 at a temperature between 160°C and 280°C for 10 minutes or more to produce explosive pellets that have a combustion heat value comparable to that of crude coal. (2) Because of its excellent water-repellent and hydrophobic properties, it can be stored outdoors, eliminating the need for huge warehouses to pack it into ton bags (flexi-con bags) and store it indoors.Furthermore, it can be stored outdoors, similar to the current storage conditions for coal. (3) By using a synthetic oil liquid to which a flammable hardener 8 has been added, it is possible to suppress the seepage of waste oil from the finished product. In particular, a ratio of waste oil to flammable hardener of 9:1 or more is preferable. (4) It was confirmed that if the product temperature after frying is below 160°C, spontaneous combustion due to contact with air during the subsequent cooling process will not occur and the product can be manufactured safely. [Example]

[0033] 100 g of White Pellets 1 are weighed out into a paper cup using a tabletop scale. The White Pellets 1 are then ground in a tabletop grinder, and the moisture content before processing is measured in advance using a near-infrared moisture meter. The mixture is heated while measuring the temperature of the bottom of the pot in the heating roaster 2b using a non-contact thermometer until the temperature reaches the range of 240°C to 280°C. Next, white pellets 1 were placed in the heating roaster 2b and pre-roasted while stirring (Steps U1-U2). This process first evaporates the moisture contained in the white pellets 1 when the raw material temperature reaches approximately 95°C. The temperature of the heating roaster 2b then drops to approximately 200°C, but the heating power of the heating roaster 2b is adjusted to maintain a temperature range of 230-280°C. After about five minutes, the raw material temperature exceeds 150°C, and volatile gases begin to evolve. The raw material gradually turns brown, and after 14 minutes, when the raw material temperature exceeds 270°C, gas generation becomes intense. At this point, the heating of the heating roaster 2b is stopped, completing the drying and roasting process (Steps U3-U4). Next, waste oil 4 was placed in another aluminum pot 3C, heated on a gas stove 5c, and fried for 5 minutes at a temperature between 250°C and 280°C using a resistance thermometer. The pan was then transferred to a colander 6b and the oil was separated (U5-U7). Next, waste oil 4 with added flammable hardener 8 was placed in another aluminum pot D, heated on a gas stove 5d, and poured into synthetic waste oil heated to 100-110°C using a resistance thermometer. The oil was then fried at low temperature until the product temperature reached 160°C or below, and then poured into a vibrating sieve 6d for solid-liquid separation (U8-U10). After removing the flammable hardener-added waste oil liquid, the mixture was cooled to obtain explosive pellets 7, the final product of the present invention (step U11). Here, paraffin was used as the flammable hardener 8.

[0034] The white pellets 1 dried and roasted in steps U2 to U4 were placed in heated waste oil 4 for deep-frying (steps U5 and U6). The temperature of the waste oil 4 was lowered, but the heat of the gas stove 5c was adjusted so that the temperature remained in the range of 250 to 280°C, and the pellets were deep-fried for 5 minutes, then the pellets were removed into a colander 6b and the oil was separated (step U7). The waste oil 4 containing the flammable hardener 8 was placed in another aluminum pot 3D, heated on the gas stove 5d, and placed in synthetic waste oil heated to 100 to 110°C using a resistance thermometer, and deep-fried at a low temperature until the product temperature reached 160°C or below (step U8). Thereafter, the white pellets 1 that had been subjected to low-temperature oil frying treatment were put into a vibrating sieve 6d together with the waste oil, and the flammable hardener-added waste oil liquid and the white pellets 1 were separated (steps U9 to U10). After cooling, explosive pellets (products) 7 were obtained (step U11).

[0035] To prevent waste oil from seeping out of the pellets, the pellets were fried at low temperatures in a synthetic oil solution containing paraffin 8 as a flammable hardener. The ratio of waste oil to flammable hardener was 9:1. This proved to be effective in preventing the seepage of waste oil up to 65°C, the melting point of paraffin.

[0036] After the frying process, White Pellet 1 changed color from its original light brown to pitch black. The calorific value of combustion per unit weight increased from 4,200 Kcal before the process to 5,910 Kcal. This value is comparable to that of raw coal, and it was found to be a potential alternative coal.

[0037] The moisture content of White Pellet 1 before treatment was 7.8%, which dropped to 1.8% after treatment. In addition, the weight was initially 100g, but after roasting it was 72g, and after oiling it was 103g, confirming that the amount of evaporated moisture and volatile substances that had evaporated and disappeared were almost completely replaced by the amount of waste oil to which paraffin had been added.

[0038] The fried white pellets 1 did not seep out of the surface of the waste oil even when the ambient temperature exceeded 30°C, and they remained dry and smooth, significantly improving their handling. The use of paraffin as a flammable hardener 8 was effective as a hardener for the waste oil.

[0039] The underwater shape retention test, which confirmed water repellency and hydrophobicity, showed no change in shape even after immersion in water for several days, significantly extending the target of six hours. In other words, good results were obtained when the product was fried for more than five minutes in waste oil heated to 240-280°C after pre-roasting until the raw material temperature reached 270°C. Furthermore, if the product temperature after low-temperature frying using paraffin-added waste oil was kept below 160°C, spontaneous combustion due to contact with air during the subsequent cooling process was not observed, and the product could be safely manufactured. It was also confirmed that the loss of the paraffin added to the waste oil due to volatilization and gasification was suppressed.

[0040] In addition, in an underwater shape retention test to confirm the water repellency and hydrophobicity of white pellets that had only been heated and roasted under the same conditions, no change in shape was observed even after immersing them in water for several days.

[0041] As mentioned above, the underwater shape retention to confirm water repellency and hydrophobicity showed that no change in shape was observed even when the pellets were immersed in water for several days, demonstrating sufficient water repellency and hydrophobicity as the target. Furthermore, similar effects were obtained with raw materials other than white pellets, such as chipped thinned wood, rice husks stored outdoors by farmers, and chipped green bamboo. [Industrial Applicability]

[0042] [Devices for practical use] As shown in Figure 4, the typical equipment used to process wood pellets is to process dried and crushed wood raw material through a conditioner 9 in a disk-rotating, compression-extrusion-type disk pelleter 10. After processing, the pellets reach a high temperature of over 70°C due to frictional heat. If the pellets are stored in this state in the product bunker 12, the evaporated water will condense, which can have the adverse effect of causing mold to grow inside the product bunker 12. Therefore, the pellets are cooled in a counter cooler 11 before being transported to the product bunker 12 for storage.

[0043] In the present invention, by adding a continuous roaster or continuous oven (including a superheated steam type), a continuous fryer and a vibration separator to the above-mentioned existing equipment configuration, it is possible to obtain explosive pellets with a higher combustion heat output and water repellency and hydrophobicity. However, when using a continuous superheated steam oven, if the moisture content of the raw materials is high, the pellets may absorb condensed water during heat exchange and lose their shape, so it is necessary to use a roaster in advance to reduce the moisture content and to keep the pellet temperature at 150°C or higher. Furthermore, even if there is no space in the existing equipment configuration to install a continuous roaster or continuous oven (including superheated steam type), continuous fryer, and vibration separator, and wood pellets are produced and temporarily stored in the product bunker 12 (storage hopper), they can be discharged and transported from the bottom of the product bunker 12 (storage hopper) using a discharge and pellet transport conveyor, and then fed into the continuous roaster or continuous oven (including superheated steam type) or continuous fryer, and a vibration separator can be added to obtain explosive pellets that have a high combustion heat output and are water-repellent and hydrophobic. However, when using a continuous superheated steam oven, if the moisture content of the raw materials is high, the pellets may absorb condensed water during heat exchange and lose their shape, so it is necessary to use a roaster in advance to reduce the moisture content and to keep the pellet temperature at 150°C or higher. In addition, by configuring new equipment and factories for processing explosive pellets, it is possible to obtain explosive pellets that have a high combustion heat output and are water-repellent and hydrophobic. When frying a small amount of wood fuel in a continuous fryer, it is possible to prepare a pot of a size that matches the amount of raw material to be processed and process it in batches. [Explanation of symbols]

[0044] 1. Bark pellets or white pellets (wood raw materials) 2. Microwave 2a heating roaster 2b heating roaster 3. Aluminum pots 3A aluminum pot 3B aluminum pot 3C aluminum pot 3D aluminum pot 4. Waste oil 5 Gas stove 5a gas stove 5b Gas stove 5c gas stove 5d gas stove 6 colander 6a Colander 6b Colander 6c vibrating sieve machine 6d vibrating sieve machine 7 Explosive Pellets (Product) 8. Flammable hardeners 9. Conditioner 10-disc rotary compression extrusion type pelletizer 11 Countertop Cooler 12 product bunkers

Claims

1. A step of roasting a pellet-shaped wood raw material; A step of oiling the roasted wood raw material with vegetable oil or animal oil at a high temperature of 240°C to 280°C; a step of subjecting the high-temperature oil-treated wood raw material to low-temperature oil-treatment with vegetable oil or animal oil at 100°C to 110°C; and removing vegetable oils or animal oils adhering to the oil-treated wood raw material, A method for producing woody explosive pellets, characterized in that in the low-temperature oil preparation step, a synthetic oil liquid containing paraffin in the vegetable oil or animal oil is used.

2. 2. The method for producing woody explosive pellets according to claim 1, wherein the vegetable oil or animal oil is waste oil.

3. The method for producing woody explosive pellets according to claim 1 or 2, characterized in that the high-temperature oil treatment is carried out for 5 minutes or more.

4. 3. The method for producing woody explosive pellets according to claim 1, wherein the synthetic oil contains 10% or more of paraffin.

5. 3. The method for producing woody explosive pellets according to claim 1, wherein the woody raw material is bark pellets or white pellets.

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