Method for producing bio-solid fuel using cassava waste

Abstract

The present disclosure relates to a method for producing a bio-solid fuel using cassava waste. A method for producing a bio-solid fuel using cassava waste, according to one embodiment of the present disclosure, comprises: a step (S100) of supplying cassava waste as a raw material; a step (S200) of supplying an acid catalyst to the raw material and hydrothermally carbonizing same at a temperature of 160℃ to 240℃; and a step (S300) of producing the hydrothermally carbonized product as a bio-solid fuel, wherein the cassava waste includes starch waste sludge, root waste, and peel waste, and the acid catalyst is a single acid catalyst.

Description

Method for producing biosolid fuel using cassava waste

[0001] The present disclosure relates to a method for producing a biosolid fuel using cassava waste, and more specifically, to a method for producing a solid fuel using cassava waste as a raw material through catalytic hydrothermal carbonization.

[0002] This patent was conducted with the support of the Korea Institute of Energy Technology Evaluation and Planning (20228520090010, Development of an integrated system for producing biofuel from tapioca starch waste using anaerobic digestion and hybrid hydrothermal carbonization technology) with funding from the government (Ministry of Trade, Industry and Energy) in 2022.

[0003] Cassava is a subtropical crop rich in carbohydrates. It is a root vegetable with a brown outer skin and white flesh. It is a staple food in Southeast Asia and Africa. Tapioca is an edible starch extracted from cassava, and cassava contains approximately 20-25% tapioca starch. Tapioca is rich in nutrients such as calcium, vitamin B, and vitamin D, and is widely used in everyday foods. It also contains more resistant carbohydrates, which are slower to digest than rice or wheat flour, and is therefore attracting attention as a diet food and for diabetics.

[0004] As interest in tapioca starch grows and its production increases, so does the amount of cassava waste generated during its production. Some of the starch waste is used for biogas production, while the remaining waste (cassava peel and root waste) is disposed of through incineration or landfill.

[0005] Figure 1 is a diagram illustrating a conventional cassava waste treatment process. Referring to Figure 1, the conventional cassava waste treatment process involves separating starch waste from process water and waste sludge through solid-liquid separation, and then anaerobically digesting the process water to convert it into biogas.

[0006] However, a significant portion of starch waste, including sludge, is currently being disposed of through incineration or landfill. Remaining waste, such as cassava root and peel waste, is not suitable for anaerobic digestion and is therefore entirely incinerated or landfilled. In other words, most cassava waste is incinerated or landfilled, with only a small portion converted into biogas through anaerobic digestion and used as fuel.

[0007] Accordingly, there is a need for an environmentally friendly and effective method to dispose of not only starch waste generated during the cassava starch production process, but also residual waste such as peels and roots.

[0008] [Prior Art Literature]

[0009] (Patent Document 1) Patent Publication No. 10-2505116 (February 24, 2023)

[0010] The present disclosure is intended to solve the problems of the above-described prior art, and its purpose is to provide a method for effectively processing cassava waste by producing solid fuel from cassava waste using hydrothermal carbonization.

[0011] In addition, the present disclosure aims to provide a method for producing a high-calorie solid fuel from a low-calorie raw material by using a catalyst during hydrothermal carbonization.

[0012] A representative configuration of the present disclosure to achieve the above purpose is as follows.

[0013] A method for producing a biosolid fuel using cassava waste according to one embodiment of the present disclosure is a method for producing a solid fuel from cassava waste through catalytic hydrothermal carbonization, comprising the steps of: supplying cassava waste as a raw material; supplying an acid catalyst to the raw material and hydrothermally carbonizing it at a temperature of 160°C to 240°C; and producing a hydrothermally carbonized product as a biosolid fuel. Here, the cassava waste includes starch waste sludge, root waste, and peel waste, and the acid catalyst is a single acid catalyst.

[0014] According to one embodiment of the present disclosure, the step of supplying cassava waste as a raw material may include a step of subjecting cassava starch waste to solid-liquid separation, and a step of providing starch waste sludge, which is a solid separated by subjecting the starch waste to solid-liquid separation, as a raw material for hydrothermal carbonization together with root waste and peel waste.

[0015] A method for producing a biosolid fuel using cassava waste according to one embodiment of the present disclosure may further include a step of subjecting starch waste to solid-liquid separation and anaerobically digesting the separated liquid product to produce biogas.

[0016] According to one embodiment of the present disclosure, the acid catalyst may be hydrochloric acid or citric acid.

[0017] According to one embodiment of the present disclosure, the solid fuel manufacturing step may include a step of solid-liquid separating a hydrothermal carbonized product, a step of drying the solid separated by the solid-liquid separation, and a step of forming the dried solid into a form of solid fuel.

[0018] According to one embodiment of the present disclosure, the biosolid fuel may have a lower calorific value of 5,000 kcal / kg or more.

[0019] According to one embodiment of the present disclosure, the biosolid fuel may have an ash content of 15 wt% or less.

[0020] According to one embodiment of the present disclosure, the biosolid fuel may have a fuel ratio of 0.7 or greater.

[0021] According to one embodiment of the present disclosure, the biosolid fuel may have an H / C of 0.9 to 1 and an O / C of 0.2 to 0.4.

[0022] In addition, other configurations may be added to produce biosolid fuel using cassava waste for implementing the present disclosure.

[0023] According to one embodiment of the present disclosure, cassava waste, i.e., starch waste sludge, root waste and peel waste, can be effectively treated.

[0024] At the same time, according to one embodiment of the present disclosure, a high-calorie solid fuel having a calorific value of 5,000 kcal / kg or more can be obtained by catalytic hydrothermal carbonization using cassava waste as a raw material.

[0025] Figure 1 is a schematic diagram showing a conventional cassava waste treatment process.

[0026] FIG. 2 is a diagram showing a process for producing biosolid fuel using cassava waste according to one embodiment of the present disclosure.

[0027] FIG. 3 is a schematic diagram illustrating a process of supplying cassava waste as a raw material according to one embodiment of the present disclosure.

[0028] FIG. 4 is a drawing schematically showing a process for manufacturing solid fuel according to one embodiment of the present disclosure.

[0029] FIG. 5 is a diagram showing the overall process for producing biosolid fuel using cassava waste according to one embodiment of the present disclosure.

[0030] FIG. 6 is a graph showing changes in calorific value according to catalyst and hydrothermal carbonization temperatures in a biosolid fuel manufactured according to one embodiment of the present disclosure.

[0031] FIG. 7 is a graph showing the degree of carbonization according to the catalyst in a biosolid fuel manufactured according to one embodiment of the present disclosure.

[0032] [Explanation of symbols]

[0033] 101: High-Liquid Separator

[0034] 201: Hydrothermal carbonization reactor

[0035] 301: High-Liquid Separator

[0036] 302: Dryer

[0037] 401: Anaerobic digester

[0038] The embodiments described below are provided for the purpose of explaining the technical idea of ​​the present disclosure, and the scope of the present disclosure is not limited to the embodiments presented below or the specific description thereof.

[0039] All technical and scientific terms used in this specification have the meaning commonly understood by a person of ordinary skill in the art to which this disclosure belongs, unless otherwise defined, and all terms used in this specification have been selected for the purpose of more clearly describing this disclosure and have not been selected to limit the scope of the rights of this disclosure.

[0040] As used herein, expressions such as “including,” “comprising,” “having,” etc. should be understood as open-ended terms implying the possibility of including other embodiments, unless otherwise stated in the phrase or sentence in which the expression is included.

[0041] Hereinafter, with reference to the attached drawings, a preferred embodiment of the present disclosure will be described in detail to a degree that a person having ordinary skill in the art to which the present disclosure pertains can easily practice the present disclosure.

[0042] FIG. 2 is a diagram showing a process for manufacturing a biosolid fuel using cassava waste according to an embodiment of the present disclosure, FIG. 3 is a diagram schematically showing a process for supplying cassava waste as a raw material according to an embodiment of the present disclosure, FIG. 4 is a diagram schematically showing a process for manufacturing a solid fuel according to an embodiment of the present disclosure, and FIG. 5 is a diagram showing an entire process for manufacturing a biosolid fuel using cassava waste according to an embodiment of the present disclosure.

[0043] Referring to FIGS. 2 to 5, a method (S10) for producing a biosolid fuel using cassava waste according to one embodiment of the present disclosure may include a step of supplying cassava waste as a raw material (S100), a step of hydrothermal carbonization (S200), a step of producing a biosolid fuel (S300), and a step of generating biogas (S400).

[0044] The step of supplying cassava waste as a raw material (S100) is a step of providing cassava waste as a feedstock for biosolid fuel production. Here, cassava waste is waste generated during the cassava starch production process, and may be mixed cassava waste including cassava starch waste sludge, root waste, and peel waste.

[0045] Referring to FIG. 3, the step (S100) of supplying cassava waste as a raw material may include a step (S110) of solid-liquid separation of cassava starch waste and a step (S120) of providing starch waste sludge as a raw material for hydrothermal carbonization.

[0046] In the solid-liquid separation step (S110) of cassava starch waste, cassava starch waste generated during the cassava starch production process is separated into solid starch waste sludge and process water (wastewater) through a solid-liquid separator (101).

[0047] The step (S120) of providing starch waste sludge as a raw material for hydrothermal carbonization is a step (S120) of providing starch waste sludge separated through solid-liquid separation as a raw material for hydrothermal carbonization. In step (S120), the starch waste sludge is provided as a raw material for hydrothermal carbonization together with root waste and peel waste. In other words, the cassava waste provided as a raw material for biosolid fuel production may include not only starch waste sludge separated from starch waste through solid-liquid separation, but also residual waste with a high solid content, such as root waste and peel waste.

[0048] The hydrothermal carbonization step (S200) is a step in which cassava waste raw material is provided and subjected to catalytic hydrothermal carbonization. The cassava waste raw material is exposed to high temperature and high pressure in a hydrothermal carbonization facility to undergo hydrothermal carbonization. Specifically, in the hydrothermal carbonization step (S200), cassava waste including starch waste sludge, root waste, and peel waste is fed into a hydrothermal carbonization reactor (201) and subjected to hydrothermal carbonization, and a catalyst is supplied during the hydrothermal carbonization. At this time, a single acid catalyst is used as the catalyst. According to one embodiment of the present disclosure, hydrochloric acid or citric acid may be used as the single acid catalyst.

[0049] According to one embodiment, the hydrothermal carbonization step (S200) can hydrothermally carbonize cassava waste at a temperature of 160°C to 220°C for 60 to 90 minutes.

[0050] The biosolid fuel manufacturing step (S300) involves manufacturing biosolid fuel from hydrothermal carbonization products. Specifically, in this step (S300), the hydrothermal carbonization product undergoes dehydration, deodorization, and drying to manufacture biosolid fuel.

[0051] Referring to FIG. 4, the bio-solid fuel manufacturing step (S300) may include a solid-liquid separation step (S310), a drying step (S320), and a forming step (S330) into a solid fuel form.

[0052] The solid-liquid separation step (S310) is a step of extracting solids from a product that has undergone hydrothermal carbonization through a solid-liquid separator (301), and the extracted solids can be formed into bio-solid fuel. At this time, the wastewater separated and discharged through the solid-liquid separator (301) can be transferred to an anaerobic digestion tank (401) for post-treatment.

[0053] In the drying step (S320), the solid extracted in the solid-liquid separation step (S310) is dried through a dryer (302).

[0054] In the step of forming into a solid fuel (S330), the dried solid material is received and manufactured into a bio-solid fuel. Specifically, in the step of forming into a solid fuel (S330), the dried solid material is formed into pellets to manufacture a bio-solid fuel.

[0055]

[0056] *The step of generating biogas (S400) is a step of generating biogas by anaerobically digesting the process water (wastewater), which is a liquid product separated by solid-liquid separation of starch waste. Specifically, in the step of generating biogas (S400), the process water (wastewater), which is a liquid product separated by solid-liquid separation of starch waste, is supplied to an anaerobic digestion tank (401), and high-concentration organic solids are decomposed by anaerobic microorganisms, thereby processing organic waste without oxygen supply and producing biogas at the same time. The biogas generated here may be methane (CH4).

[0057] In the step of generating biogas (S400), in addition to the liquid product separated by solid-liquid separation of starch waste, the liquid product separated by solid-liquid separation of the product after hydrothermal carbonization, process water (wastewater), can be supplied to the anaerobic digestion tank (401) and anaerobically digested together.

[0058] Meanwhile, solid fuels can be classified into high-calorie coal (5,500 kcal / kg or more), medium-calorie coal (5,000 kcal / kg or more), and low-calorie coal (5,000 kcal / kg or less) based on their calorific value. For solid fuels to be used as conventional fuel, a calorific value equivalent to medium-calorie coal (5,000 kcal / kg or more) is required. Furthermore, according to South Korea's Enforcement Decree of the Act on Promotion of Saving and Recycling of Resources, manufactured biosolid fuels are required to have a calorific value of at least 3,000 kcal / kg and an ash content of no more than 15 wt%.

[0059] A biosolid fuel according to one embodiment of the present disclosure has a low calorific value of 5,000 kcal / kg or more, a calorific value equivalent to that of medium-calorific coal, and an ash content of 15 wt% or less, thereby satisfying the requirements as a biosolid fuel.

[0060] In addition, the biosolid fuel according to one embodiment of the present disclosure may have a fuel ratio of 0.7 or more, and when analyzing the elements, H / C may be 0.9 to 1, and O / C may be 0.2 to 0.4.

[0061] Hereinafter, the configuration and resulting effects of the present disclosure will be described in more detail through specific examples and comparative examples. However, the examples described below are intended to more specifically explain the present disclosure, and the scope of the present disclosure is not limited to these examples.

[0062] In the production of biosolid fuel using cassava waste according to the present disclosure, the quality of the biosolid fuel produced was compared depending on the type of catalyst supplied during hydrothermal carbonization, catalyst concentration, and hydrothermal carbonization temperature.

[0063] The biosolid fuel using cassava waste according to the present disclosure is produced through hydrothermal carbonization, and the cassava waste raw material comprises mixed cassava waste, including cassava starch waste sludge, peel waste, and root waste. Specifically, the mixed cassava waste raw material comprises starch: peel: root mixed in a ratio of 15:15:70.

[0064] Table 1 describes the characteristics of cassava waste raw materials. Referring to Table 1, it can be confirmed that the properties of cassava waste raw materials mixed with starch sludge, peel, and root meet the standards for bio-solid fuel (Bio-SPF).

[0065]

[0066] In the experimental examples below, cassava mixed waste mixed as above was used as a raw material.

[0067] Experimental Example 1: Characterization of Biosolid Fuels by Single-Catalyst Hydrothermal Carbonization

[0068] Quality analysis of biosolid fuels manufactured by varying the type of single catalyst supplied during hydrothermal carbonization was performed.

[0069] A single catalyst type was used, including an organic acid (weak acid), an inorganic acid (strong acid), an inorganic base, and a metal chloride catalyst. Specifically, examples 1 (C2H4O2, acetic acid), 2 (C6H8O7, citric acid), and 3 (CH2O2, formic acid) used organic acid catalysts, examples 4 (HCl, hydrochloric acid), 5 (H2SO4, sulfuric acid), and 6 (H3PO4, phosphoric acid) used inorganic acid catalysts, examples 7 (NaOH, sodium hydroxide), 8 (KOH, potassium hydroxide), and 9 (Ca(OH)2, calcium hydroxide) used inorganic base catalysts, and examples 10 (FeCl3, iron chloride), 11 (AlCl3, aluminum chloride), and 12 (CaCl2, calcium chloride) used metal chloride catalysts. The concentration of the catalyst was provided as 1.5 wt%, and hydrothermal carbonization was performed at a temperature of approximately 220°C for approximately 90 minutes.

[0070] The quality analysis results for the comparative example (no catalyst) and bio-solid fuels of Examples 1 to 12 are as shown in Table 2.

[0071]

[0072] Referring to Table 2, all bio-solid fuels provided with a single catalyst showed a calorific value of 3,000 kcal / kg or higher, which is the standard for calorific value of bio-solid fuels, and it was confirmed that bio-solid fuels using an acid catalyst had a relatively high lower calorific value.

[0073] The lower calorific value of the biosolid fuel according to Example 4 was the highest at 5,140 kcal / kg, and the lower calorific value of the biosolid fuel according to Example 2 was the next highest at 5,060 kcal / kg. That is, it can be confirmed that the biosolid fuel manufactured by hydrothermal carbonization by supplying the hydrochloric acid (HCl) catalyst of Example 4 or the citric acid (C6H8O7) catalyst of Example 2 to cassava waste has a lower calorific value of 5,000 kcal / kg or more, meeting the standards for medium-calorific carbon-grade biosolid fuel.

[0074] Experimental Example 2: Analysis of Biosolid Fuel Characteristics According to Catalyst Concentration

[0075] In Experimental Example 1, a quality analysis of biosolid fuels manufactured by varying the catalyst concentration in Example 2 [citric acid (C6H8O7)] and Example 4 [hydrochloric acid (HCl)], which showed a low calorific value of 5,000 kcal / kg or more, was performed.

[0076] The concentration of the citric acid (C6H8O7) catalyst was 0.75 wt% (Example 2-1), 1.50 wt% (Example 2), and 3.00 wt% (Example 2-2), and the concentration of the hydrochloric acid (HCl) catalyst was 0.75 wt% (Example 4-1), 1.50 wt% (Example 4), and 3.00 wt% (Example 4-2).

[0077] The quality analysis results for the biosolid fuels of Examples 2 to 2-2 and Examples 4 to 4-2 are as described in Table 3.

[0078]

[0079] Referring to Table 3, in the case of the citric acid (C6H8O7) catalyst, it was confirmed that the low heating value of the bio-solid fuel according to Example 2 was the highest. In addition, in the case of the hydrochloric acid (HCl) catalyst, it was confirmed that the low heating value of the bio-solid fuel according to Example 4 was the highest. That is, when a citric acid (C6H8O7) catalyst or a hydrochloric acid (HCl) catalyst is supplied to cassava waste, the bio-solid fuel manufactured by hydrothermal carbonization when the catalyst concentration is 1.5 wt% has a low heating value of 5,000 kcal / kg or more, which satisfies the standard for medium-calorie carbon-grade bio-solid fuel.

[0080]

[0081] *The ash content of the biosolid fuel according to Example 2 was 10.7 wt%, and the ash content of the biosolid fuel according to Example 4 was 14.6 wt%. When a citric acid (C6H8O7) catalyst or hydrochloric acid (HCl) catalyst is supplied to cassava waste, it can be confirmed that the biosolid fuel manufactured by hydrothermal carbonization when the catalyst concentration is 1.5 wt% also satisfies the ash content standard (15 wt% or less) of the solid fuel quality standard of the 「Act on Promotion of Saving and Recycling of Resources」 in Korea.

[0082] Experimental Example 3: Analysis of Biosolid Fuel Characteristics According to Hydrothermal Carbonization Temperature

[0083] In Experimental Example 1, a quality analysis of biosolid fuels manufactured by varying the hydrothermal carbonization temperature was performed for Example 2 [citric acid (C6H8O7)] and Example 4 [hydrochloric acid (HCl)], which showed a low calorific value of 5,000 kcal / kg or more.

[0084] The quality of biosolid fuels manufactured by supplying a citric acid (C6H8O7) catalyst during hydrothermal carbonization and varying the hydrothermal carbonization temperature was analyzed. The hydrothermal carbonization temperatures were 160°C (Example 2-3), 180°C (Example 2-4), 200°C (Example 2-5), 220°C (Example 2), and 240°C (Example 2-6), and the quality of biosolid fuels manufactured by hydrothermal carbonization at each temperature for 90 minutes was analyzed.

[0085] The quality analysis results for the biosolid fuels of Examples 2 and 2-3 to 2-6 are as described in Table 4.

[0086]

[0087] Referring to Table 4, the lower calorific value of the bio-solid fuel according to Examples 2 and 2-3 to 2-6 was 5,060 kcal / kg in Example 2 (220°C), and was the highest at 5,404 kcal / kg in Example 2-6 (240°C). That is, when cassava waste is hydrothermally carbonized by supplying a citric acid (C6H8O7) catalyst, the lower calorific value is 5,000 kcal / kg or more when the temperature is 220°C to 240°C, which satisfies the standard for medium-calorific carbon-grade bio-solid fuel.

[0088] The fuel ratio of the biosolid fuel of Example 2 (220℃) was 0.75FC / VM, and that of Example 2-6 (240℃) was 0.92FC / VM. It can be confirmed that the fuel ratio is relatively high at the hydrothermal carbonization temperature of Examples 2 (220℃) to 2-6 (240℃). Here, the fuel ratio is the ratio of fixed carbon to volatile matter (fixed carbon / volatile matter), and when the fuel ratio is high, the ignition temperature increases, the calorific value increases, and combustion is possible stably at relatively high temperatures.

[0089] The quality of biosolid fuels manufactured by supplying hydrochloric acid (HCl) catalyst during hydrothermal carbonization and varying hydrothermal carbonization temperatures was analyzed. The hydrothermal carbonization temperatures were 160°C (Example 4-3), 180°C (Example 4-4), 200°C (Example 4-5), 220°C (Example 4), and 240°C (Example 4-6), and the quality of biosolid fuels manufactured by hydrothermal carbonization at each temperature for 90 minutes was analyzed.

[0090] The quality analysis results for the biosolid fuels of Examples 4 and 4-3 to 4-6 are as described in Table 5.

[0091]

[0092] Referring to Table 5, the lower heating value of the bio-solid fuels according to Examples 4 and 4-3 to 4-6 was 5,140 kcal / kg in Example 4 (220°C). The bio-solid fuels according to Examples 4 and 4-3 to 4-6 showed the best effect (4,767 kcal / kg to 5,140 kcal / kg) in increasing the heating value in the hydrothermal carbonization reaction. In addition, it was confirmed that a relatively high heating value (4,785 kcal / kg) was also shown in the bio-solid fuel of Example 4-3 (160°C) at a relatively low temperature. In addition, when hydrothermal carbonization was performed by supplying a hydrochloric acid (HCl) catalyst to cassava waste, the lower heating value was 5,000 kcal / kg or more at a temperature of 220°C, which satisfies the standard for medium-heat-value carbon-grade bio-solid fuel.

[0093] The fuel ratio of the biosolid fuel of Example 4 (220°C) was 0.93 FC / VM, and the fuel ratio of Example 4-6 (240°C) was 1.06 FC / VM. It can be confirmed that the fuel ratio is relatively high at the hydrothermal carbonization temperatures of Example 4 (220°C) to Example 4-6 (240°C).

[0094] FIG. 6 is a graph showing the change in calorific value according to the catalyst and hydrothermal carbonization temperature in a biosolid fuel manufactured according to an embodiment of the present disclosure. Specifically, in FIG. 6, the black line (Non-cat.) shows the change in calorific value according to the temperature of non-catalytic hydrothermal carbonization, the orange line (Citric acid) shows the change in calorific value according to the temperature of hydrothermal carbonization using a citric acid (C6H8O7) catalyst according to an embodiment of the present disclosure, and the green line (HCl) shows the change in calorific value according to the temperature of hydrothermal carbonization using a hydrochloric acid (HCl) catalyst according to an embodiment of the present disclosure.

[0095] Referring to FIG. 6, the bio-solid fuel according to one embodiment of the present disclosure, when a citric acid (C6H8O7) catalyst is applied, exhibits a low calorific value of 5,000 kcal / kg or more at a hydrothermal carbonization temperature of 220°C to 240°C, thereby satisfying the standards for medium-calorific carbon-grade bio-solid fuel. In addition, it can be confirmed once again that when a hydrochloric acid (HCl) catalyst is applied, exhibits a low calorific value of 5,000 kcal / kg or more at a hydrothermal carbonization temperature of 220°C, thereby satisfying the standards for medium-calorific carbon-grade bio-solid fuel.

[0096] Elemental analysis was also performed on each of the bio-solid fuels of Examples 2 and 4, and the results are as described in Table 6.

[0097]

[0098] Referring to Table 6, the H / C of Examples 2 and 4 were approximately 0.94 to 0.98, and the O / C was approximately 0.27 to 0.31. Here, H / C and O / C represent the carbonization degree of the biosolid fuel, which is the proportion of carbon among the components excluding moisture and ash, expressed as a weight ratio. The carbonization degree can be used to confirm the degree of increase in the solid carbon density in the process for converting waste into solid fuel and improving the quality of the solid fuel.

[0099] FIG. 7 is a graph showing the degree of carbonization according to a catalyst in a bio-solid fuel manufactured according to an embodiment of the present disclosure. Specifically, in FIG. 7, the black square dot (Feedstock) represents the degree of carbonization of a cassava waste raw material, the black circular dot (Non-cat.) represents the degree of carbonization of a bio-solid fuel manufactured by hydrothermal carbonization treatment at a temperature of 220°C without a catalyst, the orange circular dot (Citric acid) represents the degree of carbonization of a bio-solid fuel manufactured by supplying a citric acid (C6H8O7) catalyst according to an embodiment of the present disclosure and by hydrothermal carbonization treatment at a temperature of 220°C, and the green circular dot represents the degree of carbonization of a bio-solid fuel manufactured by supplying a hydrochloric acid (HCl) catalyst according to an embodiment of the present disclosure and by hydrothermal carbonization treatment at a temperature of 220°C. According to an embodiment of the present disclosure, a solid fuel, i.e., a solid fuel obtained by hydrothermally carbonizing cassava waste using a citric acid (C6H8O7) catalyst and a hydrochloric acid (HCl) catalyst, can be confirmed to appear close to the red area (Coal) in the graph. The red area (Coal) is an area showing a degree of carbonization close to coal, and the closer it is to the red area (Coal), the more similar the fuel is to coal.

[0100] That is, it was confirmed that biosolid fuel using cassava waste is a high-grade solid fuel with a low heating value of 5,000 kcal / kg or more by using a single citric acid catalyst or hydrochloric acid catalyst during hydrothermal carbonization. Therefore, starch sludge, root, and peel waste, which have high solid content among cassava waste, can be converted into high-calorie solid fuel, enabling effective cassava waste treatment and obtaining high-calorie solid fuel.

[0101] Although the present disclosure has been described above through specific details such as specific components and limited examples and drawings, these are provided only to help a more general understanding of the present disclosure, and the present disclosure is not limited to the above examples, and a person having ordinary knowledge in the technical field to which the present disclosure belongs will be able to make various modifications and variations based on this description.

[0102] Therefore, the spirit of the present disclosure should not be limited to the above-described embodiments, and all modifications equivalent to or equivalent to the claims described below should be interpreted as falling within the scope of the spirit of the present disclosure.

Claims

1. A method (S10) for producing solid fuel from cassava waste through catalytic hydrothermal carbonization, Step of supplying cassava waste as raw material (S100); Step (S200) of supplying an acid catalyst to the above raw material and hydrothermally carbonizing it at a temperature of 160°C to 240°C; and A step (S300) of manufacturing the above hydrothermal carbonized product into a bio-solid fuel; The above cassava waste includes starch waste sludge, root waste and peel waste, The above acid catalyst is a single acid catalyst, Method for producing biosolid fuel using cassava waste.

2. In paragraph 1, The step (S100) of supplying the above cassava waste as a raw material is Step (S110) of separating cassava starch waste into high and low-liquid fractions, A step (S120) further includes providing the starch waste sludge, which is a solid material separated by subjecting the starch waste to solid-liquid separation, as a raw material for the hydrothermal carbonization together with the root waste and the peel waste. Method for producing biosolid fuel using cassava waste.

3. In paragraph 2, It further includes a step (S400) of generating biogas by anaerobically digesting the liquid product separated by solid-liquid separation of the above starch waste and the liquid product separated by solid-liquid separation of the above hydrothermal carbonized product. Method for producing biosolid fuel using cassava waste.

4. In paragraph 1, The above acid catalyst is hydrochloric acid or citric acid. Method for producing biosolid fuel using cassava waste.

5. In paragraph 1, The above solid fuel manufacturing step (S300) is A step (S310) of separating the solid and liquid of the above carbonized product, A step (S320) of drying the solid separated by the above high-liquid separation, and A step (S330) of forming the dried solid material into a solid fuel form is included. Method for producing biosolid fuel using cassava waste.

6. In paragraph 1, The above bio-solid fuel has a low calorific value of 5,000 kcal / kg or more. Method for producing biosolid fuel using cassava waste.

7. In paragraph 1, The above bio-solid fuel has an ash content of 15 wt% or less. Method for producing biosolid fuel using cassava waste.

8. In paragraph 1, The above bio-solid fuel has a fuel cost of 0.7 or higher. Method for producing biosolid fuel using cassava waste.

9. In paragraph 1, The above bio-solid fuel has H / C of 0.9 to 1 and O / C of 0.2 to 0.

4. Method for producing biosolid fuel using cassava waste.

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