KR20200055380A - Method of Manufacturing Solid Fuel using Food Waste - Google Patents

Abstract

One embodiment of the present invention relates to a method for manufacturing solid fuel using food waste. To this end, the food waste undergoes a hydrothermal carbonization process under conditions involving a temperature of 180-230°C and 10-40 bar and a reaction time of 1-6 hours with sulfuric acid added in an amount of 0.5-5 wt%, thereby enabling the production of solid fuel with a low content of chlorine (Cl^-) while a lower heating value is high. The solid fuel thus produced can be useful as a fuel for a thermal power plant or the like.

Description

Method of manufacturing solid fuel using food waste

The present invention relates to a method for producing solid fuel using food waste, and more particularly, to a method for producing solid fuel by hydrothermal carbonization of food waste.

As a result of the improved dietary habits by increasing national income, our table has become richer and the phenomenon of not being able to eat properly has disappeared, but it has already been noted that the amount of food waste that is discharged as garbage is left unnecessarily on the enriched table. It is true. In 2016, the amount of food waste in Korea was 15,680 tons / day. This is equivalent to about 29% of the total amount of waste generated (4 households consume 718 kWh of energy based on food waste that is thrown out for one year, accounting for 20% of annual household power consumption). .

Food waste is usually disposed of because it is difficult to recycle because it is difficult to recycle due to the variety of types and foreign matter.However, landfilling is prohibited due to the revision of the Waste Management Law Enforcement Rules, and in recent years, as a way to turn it into a resource, feed and composting methods Is mainly used. In the case of fodderization, it can be divided into a wet method and a dry method. The dry method has a very low operating cost such as fuel cost during drying, and thus economical efficiency is low. Due to the large number, it is currently being operated in a small-scale treatment plant. In addition, in the case of dry feed, the economic efficiency is very low due to excessive energy cost for drying, and both methods are prohibited or avoided in the world due to foreign matter mixing, salt problems, and livestock disease infection problems. Even in the case of composting, it is difficult to supply due to the problem of salt content and contaminants in compost, and it undergoes a pre-treatment screening process, but it contains vinyl and contaminants, which makes it difficult to compost.

On the other hand, due to the above-mentioned problems, a technology for solidifying in terms of supplying alternative energy by utilizing food waste has been developed. However, in the process of drying the food waste to produce food waste as solid fuel, the food waste was not evenly dried, and when incinerating the solid fuel produced, there was a problem that the calorific value was low. Particularly, when the solid fuel is used as a fuel for a thermal power plant, salt (Cl ⁻ ) contained in the solid fuel may cause corrosion of a boiler material in a power plant, and thus cannot be used as a fuel for a thermal power plant.

Therefore, there is a need for a method for manufacturing a solid fuel using food waste that can solve these problems.

Republic of Korea Registered Patent No. 10-1664119

An object of the present invention is to provide a method for producing solid fuel using food waste that can produce solid fuel with high calorific value and low chlorine content.

In order to achieve the above object,

The present invention in one embodiment,

Hydrocarbonization of food waste to produce carbonized slurry;

Separating the solid product and the liquid desorption solution from the prepared carbonized slurry; And

Forming a solid product to produce a solid fuel; It includes,

The step of manufacturing the carbonized slurry provides a method for producing solid fuel using food waste, characterized in that it is performed at a temperature of 180 to 230 ° C. and a pressure of 10 to 40 bar and a reaction time of 1 to 6 hours.

According to the method for producing solid fuel using food waste of the present invention, food waste is subjected to a hydrothermal carbonization process at a temperature of 180 to 230 ° C. and 10 to 40 bar and a reaction time of 1 to 6 hours, and the low calorific value is high. Solid fuels with low content can be produced. The solid fuel manufactured in this way can be usefully used as a fuel such as a thermal power plant.

1 is a flowchart showing a method of manufacturing a solid fuel using food waste according to an embodiment of the present invention.
2 is a schematic view of the discharge system of the hydrothermal hydrocarbon reactor.
3 is an overall conceptual diagram of a continuous production apparatus for solid fuel according to the present invention.
Figure 4 is a photograph showing the amount of generation of tar (Tar) according to the material properties ((a) 90% rice, (b) 90% vegetables)
5 is a photograph of the particle surface of the solid fuel prepared in Example 6 and Comparative Example 2 with an electron microscope (SEM) ((a) 220 ℃, (b) 250 ℃).
6 (a) and (b) are graphs showing the reduction of lignin and the amount of tar, respectively, depending on the temperature.
7 (a) is a photograph showing dry carbide before acetone filtration, (b) dry carbide after acetone filtration, (c) room for hand press before acetone filtration, and (d) room for hand press after acetone filtration.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and it should be understood that all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention are included.

In the present invention, terms such as "comprises" or "have" are intended to indicate that there are features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, actions, components, parts or combinations thereof are not excluded in advance.

In the present invention, the term "hydrothermal carbonization (HTC)" means that a material having a low water content and a material having a high water content or a material having a high water content is heated in a closed reactor and water is saturated by this heating. Refers to a process in which the carbonization reaction proceeds without evaporation of moisture as water vapor pressure is generated. In particular, such hydrothermal carbonization is an easy technique for treating high-functional organic wastes, and it is possible to remove moisture by mechanical dehydration after reaction without latent heat of evaporation, and thus has less energy consumption compared to drying.

On the other hand, since food waste has a high water content, a carbonization reaction may occur in a hydrothermal carbonization reactor without supplying additional water. Specifically, as heat is applied to the hydrothermal carbonization reactor, carbon can be relatively fixed while the moisture content of food waste supplied to the hydrothermal carbonization reactor is reduced. In other words, the oxygen content and the hydrogen content of the food waste are reduced by reducing the water content of the food waste (or food sludge), and thus the carbon content of the food waste is relatively increased.

In the present invention, "low calorific power" means the amount of heat that does not take into account the amount of water vapor contained in the fuel, and means the amount of heat that can be used in an actual boiler. That is, the low calorific value may mean a value obtained by subtracting the latent heat of water vapor from the total calorific value.

The present invention relates to a method for producing solid fuel using food waste.

Conventionally, solid fuels manufactured using food wastes have a problem in that the food wastes are not evenly dried during the drying process of the food wastes, resulting in a bad smell when incineration of the solid fuels and a low calorific value. In addition, when the solid fuel is used as a fuel for a thermal power plant, salt (for example, Cl ⁻ ) contained in the solid fuel may cause corrosion of a boiler material in a power plant, and thus cannot be used as a fuel for a thermal power plant.

To overcome these problems, the present invention provides a method for producing solid fuel by hydrothermal carbonization of food waste.

According to the method for producing solid fuel using food waste of the present invention, food waste is subjected to a hydrothermal carbonization process at a temperature of 180 to 230 ° C. and 10 to 40 bar and a reaction time of 1 to 6 hours, and the low calorific value is high. Solid fuels with low content can be produced.

The solid fuel manufactured in this way can be usefully used as a fuel such as a thermal power plant.

Hereinafter, the present invention will be described in detail.

The present invention,

Hydrocarbonization of food waste to produce carbonized slurry;

Separating the solid product and the liquid desorption solution from the prepared carbonized slurry; And

Forming a solid product to produce a solid fuel; It includes,

The step of preparing the carbonized slurry is performed under conditions of a temperature of 180 to 230 ° C and a pressure of 10 to 40 bar and a reaction time of 1 to 6 hours.

More specifically, the method for manufacturing a solid fuel according to the present invention comprises the steps of: preparing food waste by hydrothermal carbonization of food waste in a hydrothermal carbonization reactor; Fluidly transferring the carbonized slurry from the reactor to the storage tank, and separating the solid product and the liquid lysate from the carbonized slurry; And forming a solid product to form a solid fuel; It includes.

In one embodiment, the present invention,

Preparing food waste by hydrothermal carbonization of food waste in a hydrothermal carbonization reactor (S100);

A step of fluidly transferring the carbonized slurry from the reactor to the storage tank, and separating the solid product and the liquid lysate from the carbonized slurry (S200); And

Forming a solid product to produce solid fuel (S300); It includes,

The step of manufacturing the carbonized slurry is a method of producing solid fuel using food waste, characterized in that heating and pressurization in a hydrothermal hydrocarbon reactor at a temperature of 180 to 230 ° C. and a pressure of 10 to 40 bar and a reaction time of 1 to 6 hours. Provided (see FIG. 1).

The food waste supplied to the hydrothermal carbonization reactor may mean consumed and leftover food, and may be food waste including grains and / or vegetables. In particular, the food waste supplied to the hydrothermal hydrocarbon reactor may be food waste having a high water content, specifically, the water content of the food waste is 70 to 90%, 72 to 88%, 73 to 86%, or 71 to 84% days Can be.

For example, since food waste has a water content in the above-described range, a carbonization reaction may occur in a hydrothermal carbonization reactor without supplying additional water. Specifically, as heat is applied to the hydrothermal carbonization reactor, carbon can be relatively fixed while the moisture content of food waste supplied to the hydrothermal carbonization reactor is reduced. On the other hand, when the water content of the food waste is less than the above range, the raw material itself lacks moisture, so that a carbonization reaction cannot occur. In addition, when it exceeds the above range, the process time or temperature for manufacturing the carbide slurry is increased, which may cause a problem of consuming a lot of energy.

In the method of manufacturing the solid fuel, the step of preparing hydrocarbon slurry by hydrothermal carbonization of food waste in a hydrothermal carbonization reactor includes a temperature of 180 to 230 ° C and a pressure of 10 to 40 bar and a reaction time of 1 to 6 hours, or a temperature of 190 to 220 ℃ and pressure 15 to 35 bar and reaction time may be 2 to 5 hours condition, preferably 190 to 210 ℃ and pressure 15 to 30 bar and reaction time may be 2 to 4 hours condition, more preferably 190 It can be carried out in a hydrothermal carbonization reactor of 200 to 200 ℃ and pressure of 15 to 20 bar and reaction time of 3 to 4 hours or 190 ℃ and pressure of 16 to 19 bar and reaction of 4 hours.

In the temperature range and pressure, it is possible to manufacture a solid fuel that effectively lowers the water content of the reactants (food waste) and exhibits excellent calorific value. For example, if the reaction temperature is less than 160 ° C and the reaction time is less than 2 hours, the heat and pressure supplied to the reactants are too low to achieve complete carbonization, and the water content of the reactants cannot be easily reduced due to dehydration. When the reaction temperature exceeds 220 ° C., the pressure 35 bar, and the reaction time 6 hours, the energy required for the reaction is too high, resulting in poor economic efficiency, and tar may be generated on the surface of the reactant (food waste). The generation of tar not only decreases the dehydration property of the reactants, but also lowers the combustion efficiency of carbides, deteriorates the quality value as a solid fuel, and acts as a factor that inhibits the growth of crops, so it cannot be applied as a soil modifier.

For example, tar is a general term for black or brown viscous oily bitumen produced by thermal decomposition of organic substances. When food wastes made of organic substances are compressed at high temperature, benzopyrene in food wastes is polycyclic aromatic hydrocarbon through thermochemical reaction. It can be converted into (polycyclic aromatic hydrocarbon, PHA), and depending on the ratio, particles due to viscous bituminous particles may generate binding phenomena, which can cause difficulties in separating sludge solids using plant equipment formula and filter press. On the other hand, when the raw material contained in the food waste contains a lot of vegetables rather than a lot of rice, the amount of tar may increase. For example, the vegetables may have a higher lignin content, so that the amount of tar generated may be higher.

The step of preparing the carbonized slurry may be performed in the temperature and pressure range for 2 to 5 hours, 2 to 4 hours, or 4 hours. This, as described above, when the reaction temperature is less than 2 hours, it may be difficult to easily reduce the moisture content of the reactant, and when the reaction temperature exceeds 5 hours, a problem that too much energy is consumed may occur.

On the other hand, it was confirmed that when preparing the carbonized slurry under the above reaction conditions, the content of salt in the solid fuel can be reduced. For example, the amount of the salt is a chloride ion (Cl ^-) can be calculated through the quantity of.

In the step of preparing a hydrocarbon slurry by hydrothermal carbonization of food waste in a reactor at a temperature of 180 to 230 ° C and a pressure of 10 to 40 bar and a reaction time of 1 to 6 hours, the food waste is preheated to a temperature of 50 to 150 ° C. It can be introduced into the reactor. Specifically, the food waste is introduced in a preheated state in the range of 50 to 110 ° C, which can prevent a rapid temperature change inside the reactor. Alternatively, the food waste is introduced in a preheated state in the range of 120 to 150 ° C, in which case the food waste is preliminarily or partially carbonized. This has the effect of increasing the carbonization efficiency of food waste.

In the step of preparing the carbonized slurry, if necessary, the hydrothermal carbonization reactor may further include introducing sulfuric acid. More specifically, in the step of preparing the carbonized slurry, it may include a process of adding 0.5 to 5% by weight of sulfuric acid with respect to 100% by weight of food waste. In the step of preparing the carbonized slurry, sulfuric acid acts as a catalyst, thereby reducing the reaction time and increasing energy density. Alternatively, the content of chlorine in the solid fuel to be produced can be effectively reduced, and the dehydration power can be improved during the subsequent solid-liquid separation process.

In this case, the sulfuric acid may be added at a level of 0.5 to 5% by weight, 1 to 4% by weight, 1.5 to 3% by weight, or 2% by weight relative to the total weight of food waste. When the sulfuric acid content is less than 0.5% by weight, the effect of reducing chlorine is insignificant, and when it exceeds 5% by weight, a problem that the content of sulfur remaining in the solid fuel increases may occur.

In one example, the step of fluidly transferring the carbonized slurry from the hydrothermal carbonization reactor to a storage tank and separating the solid product and the liquid lysate from the carbonized slurry includes: a gas separation process for separating gas components from liquid and solid components, and solids It can be performed through a solid-liquid separation process for separating the product and the liquid desorption liquid.

The solid product that has undergone the solid-liquid separation process may be dried to produce solid fuel, or may be subjected to a step of molding it. For example, in the step of forming the solid fuel, it may be molded into pellets or the like, and may be molded to a size of 50 mm in diameter and 100 mm in length or less.

In addition, tar may be produced in the solidified fuel that is produced immediately after hydrothermal carbonization. The resulting tar can be removed through acetone washing immediately after the hydrothermal carbonization reaction. For example, the carbonized slurry can be placed on a filter paper and acetone can be washed by dropping it by gravity filtration.

That is, the hydrocarbon slurry immediately after the hydrothermal carbonization reaction can remove the viscosity of the carbide through acetone washing, and remove the tar component in the slurry, which is the main cause of the viscosity. However, acetone is difficult to apply in the field due to the explosion problem, and can be replaced with ethanol-based or vegetable organic solvents.

The solid fuel made in accordance with the present invention is the lower heating value is 7,000 kcal / kg or more, a water content of 10 wt% or less, chlorine (Cl ^-) is the content be not more than 0.5 wt%.

Specifically, the solid fuel manufactured according to the present invention has a low calorific value of 7,000 kcal / kg or more, 7,000 to 10,000 kcal / kg range, 7,000 to 9,000 kcal / kg range, 7,100 to 8,000 kcal / kg range, 7,150 to 7,600 kcal / kg range, may range from 7,200 to 7,550 kcal / kg. As an example, the calorific value of the solid fuel can be measured using a Cl Calorimeter (ICA).

The solid fuel manufactured according to the present invention can satisfy both the Bio-SRF standard (3,000 kcal / kg or more) and the power plant mixing standard (3,000 kacl / kg or more) by satisfying the low calorific value of 7,000 kcal / kg or more. For reference, Bio-SRF (Biomass-Solid Refuse Fuel) refers to solid fuel produced using combustible solid waste including biomass (Enforcement Regulations on the Conservation and Recycling of Resources, Annex 7, Enforcement Decree No. 745 number).

In addition, since the solid fuel having a low water content is obtained from a solid product preceded by hydrothermal carbonization and solid-liquid separation, it can have excellent calorific value and excellent energy density. This is because the content of urea (carbon) excluding oxygen increased during the hydrothermal carbonization of food waste.

In addition, the solid fuel is produced, the chlorine (Cl ^-) upon detecting a PXRF (Potable X-Ray Fluorescence) may be less than 0.5% by weight. Specifically, chlorine may have a content of less than 0.5% by weight, 0.0001 to 0.5% by weight, 0.001 to 0.5% by weight, 0.01 to 0.3% by weight, and 0.1 to 0.2% by weight. Thus, the chlorine (Cl ^-) can be prepared a smaller amount of solid fuel, As a result, when using the solid fuel to the fuel, such as thermal power plants, it is possible to solve problems such as corrosion caused.

The solid fuel produced according to the present invention may contain heavy metals (chlorine, mercury, cadmium, lead, arsenic, chromium, sulfur) undetected or in a very small range. In practice, most heavy metals are not detected, and accordingly, when the solid fuel is burned, harmful substances and environmental pollutants are significantly reduced.

The solid fuel manufactured according to the present invention can be usefully used as a fuel such as a thermal power plant. In addition, since the content of chlorine (Cl-) is low, it can also be used as a soil modifier. For example, the solid fuel may be suitable as a soil modifier because the nitrogen content of organic matter is 3.54%, which is higher than the average content of about 2% of livestock manure.

Hereinafter, a manufacturing apparatus and a process for manufacturing solid fuel using food waste according to the present invention will be described in detail.

The step of manufacturing the carbonized slurry may be performed in a hydrothermal hydrocarbon reactor having a closed structure having an inflow line and an outflow line. 2 is a schematic view of the discharge system of the hydrothermal hydrocarbon reactor.

Referring to Figure 2, the hydrothermal carbonization reactor 107, the reaction raw material is introduced through the inlet line, the reaction is completed through the outlet line is reacted. The reactant that has flowed out through the hydrothermal carbonization reactor 107 outlet line is transferred to the reservoir 113a via the discharge member 112. The storage tank 113a may have a structure in which a stirring means is provided. The storage tank 113a is a gas separator 113a for separating gas components from reactants, and a solid-liquid separator 115 for separating solid and liquid components is sequentially connected to the rear end. The gas component separated from the gas separator 113a is discharged through the exhaust gas purifier 114. The solid-liquid separator 115 separates and discharges the solid component and the liquid component. Here, the reaction raw material refers to food waste, and the reactant after the reaction is completed may mean carbonization slurry.

On the other hand, the discharge member 112 serves to continuously flow out the reaction is complete reaction in the hydrothermal carbonization reactor 107. The discharge member 112 is a decompression means including a section in which pressure is sequentially or continuously depressurized along a fluid flow direction inside the member. The discharge member 112 may be a structure in which reactants flow out along a direction in which the screw rotates. In addition, the discharge member 112 is designed, for example, to have a structure in which the inner diameter increases sequentially or continuously along the fluid flow, or a structure in which the pressure decreases sequentially or continuously along the fluid flow.

3 is an overall conceptual diagram of a continuous production apparatus for solid fuel according to the present invention. Referring to FIG. 3, food waste, which is a reaction raw material, flows into the storage tank 101, and food waste accommodated in the storage tank 101 flows into the hydrothermal carbonization reactor 107 through the supply member 102. When the reactor water level is above a certain level, the supply member 102 stops the operation of the supply member or reduces the supply flow rate of the supply member. At this time, the hydrothermal carbonization reactor 107 is formed with a water level sensor for measuring the water level inside.

Secondary reactors 103a and 103b are positioned on the fluid flows of the supply member 102 and the reactor 107. If necessary, the auxiliary reactors 103a and 103b have a structure in which two reactors are formed in parallel positions . In the auxiliary reactors 103a and 103b, preliminary carbonization is performed by preheating food waste in the range of 70 to 80 ° C or heating it in the range of 100 to 110 ° C.

Food waste that has passed through the auxiliary reactors 103a and 103b flows into the hydrothermal carbonization reactor 107 under pressure at a pressure in the range of 10 to 40 bar. In addition, the catalyst stored in the chemical storage tank 105 is added into the hydrothermal carbonization reactor 107 via the chemical pump 106. Sulfuric acid is used as the catalyst. If necessary, a separate heating oil heater 108 is provided on one side of the hydrothermal carbonization reactor 107. Through the heating oil heater 108, the hydrothermal carbonization reactor 107 is heated or the temperature is maintained. The inside of the reactor 107 is heated and pressurized in a range of 180 to 230 ° C. and 10 to 40 bar and reaction time 1 to 6 hours. Under the heating and pressurizing conditions, the food waste inside the reactor 107 is converted to a solid-liquid slurry containing a solid product and a liquid desorption liquid through a carbonization process.

The reactant flows out through the outlet line of the hydrothermal hydrocarbon reactor 107. The reactant that flows out flows into the discharge member 112 through the first heat exchanger 109 and the second heat exchanger 110. The first heat exchanger 109 supplies the heat generated from the high temperature reactant discharged from the reactor 107 to the auxiliary reactors 103a and 103b. If necessary, the first heat exchanger 109 supplies heat to the auxiliary reactors 103a and 103b through the heating oil. In this case, the heat exchanger pump 104 is positioned between the first heat exchanger 109 and the auxiliary reactors 103a and 103b. In addition, a separate cooler 111 is formed on one side of the second heat exchanger 110. Through the second heat exchanger 110, the temperature of the reactants flowing into the discharge member 112 is cooled to 60 to 70 ° C.

The reactants introduced into the discharge member 112 undergo a process of being depressurized while passing through the discharge member 112. While passing through the discharge member 112, the pressure of the reactants is reduced from 20 to 23 bar to atmospheric pressure (about 1 bar). The discharge member 112 continuously discharges the reactant, and at the same time, the pressure of the reactant is sequentially or continuously lowered along the fluid flow direction inside the member. When the water level of the gas separator 113b is higher than a certain level, the discharge member 112 stops the operation of the discharge member or reduces the flow rate of the discharge member. At this time, the gas separator 113b is formed with a water level sensor for measuring the water level inside.

The reactant passed through the discharge member 112 flows into the gas separator 113b that separates gas components in the reactant. The reactant having the gas component separated while passing through the gas separator 113b is introduced into the solid-liquid separator 115 again. In the solid separator 115, the reactants are separated into a solid product and a liquid stripping liquid. The solid product is introduced into a solid fuel molding machine and subjected to a molding process, and the liquid desorption liquid is discharged or reused.

Thereby, solid fuel can be obtained from the drying apparatus. At this time, the solid fuel may have a water content of about 10% or less, and may be supplied to a heating device, a power plant, and a demand for solid fuel.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples.

<Example>

Example 1.

Food waste was produced as solid fuel using a solid fuel manufacturing apparatus. Specifically, 2 kg of food waste having a water content of 75.6% was heated and pressed for 4 hours in a reactor at a temperature of 220 ° C. and a pressure of 30 bar before and after hydrothermal carbonization. Then, the solid product and the liquid desorption liquid were separated by fluid transfer to a storage tank to prepare a solid fuel.

Example 2.

Solid fuel was prepared in the same manner as in Example 1, except that sulfuric acid was added to the food waste. At this time, sulfuric acid was added 2% by weight relative to the total weight of food waste.

Example 3.

2 kg of food waste having a water content of 77.4% was hydrothermal carbonized for 4 hours in a reactor at a temperature of 190 ° C and a pressure of about 18 bar. Then, the fluid was moved to a storage tank to separate the solid product and the liquid desorption liquid.

Example 4.

Solid fuel was prepared in the same manner as in Example 1, except that sulfuric acid was added to the food waste. At this time, sulfuric acid was added 2% by weight relative to the total weight of food waste.

Example 5.

Solid fuel was prepared in the same manner as in Example 3, except that the reaction temperature was set to 220 ° C.

Example 6.

Solid fuel was prepared in the same manner as in Example 5, except that sulfuric acid was added to the food waste. At this time, sulfuric acid was added 2% by weight relative to the total weight of food waste.

Example 7.

A solid fuel was prepared in the same manner as in Example 1, except that food waste having a water content of 76.5% was used as a sample and the heat treatment temperature was set at 190 ° C.

Example 8.

A solid fuel was prepared in the same manner as in Example 1, except that food waste having a water content of 74.8% was used as a sample and the heat treatment temperature was set at 190 ° C.

Comparative Example 1.

Solid fuel was prepared in the same manner as in Example 3, except that the reaction temperature was set to 160 ° C.

Comparative Example 2.

A solid fuel was prepared in the same manner as in Example 1, except that food waste having a water content of 78.1% was used as a sample, and a heat treatment temperature was set at 250 ° C.

<Experimental Example>

Experimental Example 1. Component analysis of solid fuel and measurement of low heat generation

Component analysis of the solid fuels prepared in Examples 1 and 2 and low calorific value were measured.

As for the calorific value, analysis using a device is generally used, and when a sample in a cylinder is burned, it transfers heat to the water in the device and measures the temperature of the water to calculate the calorific value. Instrumental analysis values are as dry senior heating value, water vapor latent s a value calculated using the reference high-ranking heat value (total calorific power, H _h), and, as the reference lower heating value moist heat generation other than the latent heat of water vapor (see heating value, H _l) It is called.

The low heat generation amount is oxidized to CO ₂ , H ₂ O. NO ₂ , and SO ₂ by using an elemental analyzer (Elemental Analyzer, Thermo Fisher Scientific) using a catalyst at a temperature of about 1000 ° C., respectively. Separation using GC column and using standard conductive detector (TCD) to detect calibration curves for each C, H, N, S using standard materials, and the content of each element from GC chromatogram % Was quantified and calculated using the Dulong formula.

-

-

Here, C: carbon (%), H: hydrogen (%), O: oxygen (%), S: sulfur (%), W: moisture (%).

Item unit Bio-SRF
standard power plant
Mixed standards Example 1 Example 2 Temperature condition - - - 220 ℃ (sulfuric acid X) 220 ℃
(O sulfuric acid) size diameter mm 50 - 100% 100% Length mm 100 40 moisture weight % 10 10 2 1.8 Low heat generation kcal / kg More than 3,000 More than 3,000 7,200 7,540 Ash wt% 15 35 3.3 8.2 Goat wt% 0.5 0.5 0.46 0.28 Yellow powder wt% 0.6 2 0.3 1.04 metal
ingredient Mercury mg / kg 0.6 1.2 Non-detection Non-detection cadmium mg / kg 5 9 0.15 Non-detection lead mg / kg 100 200 Non-detection Non-detection arsenic mg / kg 5 13 2.78 1.65 chrome mg / kg 70 - 4.6 5.3

Referring to Table 1, Examples 1 and 2 increased the low heat generation by the Bio-SRF standard and the power plant mixing standard by about 2 times.

In addition, Example 1 without the addition of sulfuric acid met the chlorine standards of Bio-SRF and power plant mixing standards, and Example 2 with the addition of sulfuric acid had a sulfuric acid content exceeding about 173% based on Bio-SRF, "the waste management method Enforcement Rules (Annex 5, 3, R-9-5) "meets the criteria for mixing plants. In addition, the addition of sulfuric acid could reduce the chlorine content of carbides by about 39%.

For reference, Bio-SRF (Biomass-Solid Refuse Fuel) refers to solid fuel produced using combustible solid waste including biomass (Enforcement Regulations on the Conservation and Recycling of Resources, Annex 7, Enforcement Decree No. 745 number). In particular, it is recognized as Bio-SRF only when the Bio-SRF standard is satisfied.

Experimental Example 2. Analysis of component of solid fuel and measurement of low heat generation according to treatment temperature

Component analysis and low heat generation of the solid fuels prepared in Examples 3 to 6 and Comparative Example 1 were measured. Then, heavy metals and pollutants in solid fuels were analyzed, and the results are shown in Table 2.

Item unit power plant
Mixed standards Comparative Example 1 Example 3 Example 4 Example 5 Example 6 Temperature condition - - 160 ℃ (sulfuric acid X) 190 ℃
(Sulfuric acid X) 190 ℃
(O sulfuric acid) 220 ℃
(Sulfuric acid X) 220 ℃
(O sulfuric acid) size diameter mm - 100% 100% 100% 100% 100% Length mm 40 moisture % 10 1.2 2.5 2.5 2 1.8 Low heat generation kcal / kg More than 3,000 5,609 7,314 7,314 7,200 7,540 Ash wt% 35 6.5 6.2 6.2 3.3 8.2 Goat wt% 0.5 2.04 0.48 0.31 0.46 0.28 Yellow powder wt% 2 0.45 0.32 0.32 0.3 1.04 metal
ingredient Mercury mg / kg 1.2 Non-detection Non-detection Non-detection Non-detection Non-detection cadmium mg / kg 9 0.31 Non-detection Non-detection 0.15 Non-detection lead mg / kg 200 Non-detection Non-detection Non-detection Non-detection Non-detection arsenic mg / kg 13 2.55 1.21 0.98 2.78 1.65 chrome mg / kg - 3.12 1.73 2.89 4.6 5.3 element
analysis C % - 56.1 67.0 68.3 68.8 69.8 H % - 7.1 8.8 8.6 8.4 8.1 N % - 5.1 3.7 3.2 3.5 2.3 O % - 22.5 13.5 12.4 15 10.2 (Solid) Yield % - 71.37 62.7 54.7 51 44

Referring to Table 2, it was confirmed that as the temperature increased, dehydration increased and the solid yield decreased. In addition, at the same temperature, dehydration increased with sulfuric acid injection.

Comparative Example 1 had a low carbon (C) content because the carbonization reaction was not completely performed at a heat treatment temperature of 160 ° C., and the low calorific value was relatively low due to high oxygen (O) content. On the other hand, most of the values were similar under the conditions of the heat treatment temperature of 190 ° C and 220 ° C, and considering energy consumption and tar generation, the low temperature of 190 ° C was determined to be suitable.

All of Examples 3 to 6 met the mixing standards of the "Waste Management Act Enforcement Rules (3, R-9-5 in Appendix 5)" regardless of whether or not catalysts were used, but when comparing the presence or absence of sulfuric acid, Example 3 and implementation The chlorine content of Example 5 was 0.48 and 0.46%, respectively, but the chlorine content of Examples 4 and 6 in which sulfuric acid was added was 0.31 and 0.28 wt%, respectively. It was possible to increase the value of solid fuel quality on a mixed basis.

Experimental Example 3. Comparison of the amount of tar generated according to the properties of raw materials

The food waste containing 90% of rice and the food waste containing 90% of vegetables were subjected to hydrothermal carbonization (220 ° C., 4 hr), and immediately after the hydrothermal carbonization reaction, the carbonized slurry was subjected to solid-liquid separation through a 5-7 μm filter paper.

And, in order to compare the generation amount of tar, shown in Figure 4 ((a) 90% rice, 90% vegetables). As a result, in the case of most of the rice, the color of the carbide was brown with no tar formation, but in the case of most of the kimchi and vegetables (B), the content of lignin was high and the tar generation was much higher than the same condition.

Experimental Example 4. Evaluation of tar generation of solid fuel according to treatment temperature

In order to evaluate the tar generation of the solid fuel prepared in Example 6 and Comparative Example 2, the particle surface of the solid fuel was observed by magnifying it 1,000 times with a scanning electron microscope (SEM).

5 is a photograph of the particle surface of the solid fuel prepared in Example 6 and Comparative Example 2 with an electron microscope (SEM) ((a) 220 ℃, (b) 250 ℃).

Referring to FIG. 5, the heat treatment temperature was 250 ° C. and the viscosity was very high compared to 220 ° C. It was impossible to observe the surface of the individual particles because the entire particles were covered with solid oil (tar).

On the other hand, tar is a black or brown viscous oily bitumen material generated by thermal decomposition of organic substances.When food wastes made of organic substances are compressed at high temperature and high temperature, benzopyrene in food wastes is polycyclic aromatic hydrocarbon ( It is converted to polycyclic aromatic hydrocarbon (PHA), and depending on the ratio, it can cause the bonding phenomenon between particles due to viscous bitumen, which can cause difficulties when separating sludge solids using plant equipment formula and filter press.

Figure 6 (a), (b) is a graph showing the amount of lignin reduction and tar production with temperature, respectively

Referring to Figure 6, the hydrothermal carbonization reaction of the organic material is inevitably accompanied by a certain amount of tar generation upon reaching the decomposition temperature of the lignin component in the biomass, and it can be seen that the tar conversion amount increases as the temperature increases. . The melting point of benzopyrene is 179 ℃, and the higher the temperature, the higher the amount of tar converted to liquefied form increases.

Excess tar component in carbide is known as an inhibitor that interferes with crop growth, but decomposition of a certain amount of lignin is consistent with the "bio difference value" while increasing carbon content and heat, and around 190 ℃ considering the mechanism of tar production It was judged as the optimal temperature for food waste disposal through hydrothermal carbonization.

Experimental Example 5. Tar treatment evaluation of solid fuel

Immediately after the hydrothermal carbonization reaction of Example 7, the carbonized slurry was subjected to solid-liquid separation through a 5-7 μm filter paper. At this time, the tar component was treated using 95% acetone at 40 to 60% by weight based on the total weight of the slurry. Specifically, about 120 g of slurry was placed on a 5-7 μm filter paper, and about 50 ml of acetone having a purity of 95% or more was dropped and washed by gravity filtration.

The degree of desorption of solids was compared using a hand press (1 kgf, 2 min) of the carbonized slurry immediately after the hydrothermal reaction and the acetone slurry after washing. This is shown in FIG. 7.

Referring to FIG. 7, it was confirmed that the color of dry carbide was changed from black to dark brown by removing the tar component in the slurry, and it was confirmed that the slurry was cleanly separated without leaving traces on the filter paper after filtration of acetone.

That is, the hydrocarbon slurry immediately after the hydrothermal carbonization reaction can remove the viscosity of the carbide through acetone washing, and remove the tar component in the slurry, which is the main cause of the viscosity.

In the filter press process, it is determined that the tar component can be processed using acetone to prevent difficulty in separating carbides. However, acetone is difficult to apply in the field due to the explosion problem, so it can be replaced with ethanol-based or vegetable organic solvents.

Experimental Example 6. Evaluation of fertilizer application after hydrothermal carbonization of food waste

The components of the carbonized slurry were analyzed immediately after the hydrothermal carbonization reaction of Example 8. And, it is shown in Table 3 below, was evaluated for fertilizer application.

number Item unit Fertilizer process
standard Analysis value Remark One arsenic mg / kg 45 2.78 fitness 2 cadmium mg / kg 5 0.15 fitness 3 Mercury mg / kg 2 Non-detection fitness 4 lead mg / kg 130 Non-detection fitness 5 chrome mg / kg 200 4.6 fitness 6 Copper mg / kg 360 3.1 fitness 7 nickel mg / kg 45 1.2 fitness 8 zinc mg / kg 900 Non-detection fitness 9 Organic matter weight % 30 or more 95.5 fitness 10 salt weight % 2 1.65 fitness 11 moisture weight % 55 2 fitness 12 Hydrochloric acid insoluble matter weight % 25 0.2 fitness 13 Maturity - Comeback fitness fitness Seed germination 14 Organic matter % 50 26.63
(Organic: 94.28, Nitrogen: 3.54) fitness * Fertilizer standard "Fair fertilizer process standard setting and designation, Rural Development Administration Notification No. 2017-18"

As a result, the nitrogen content of organic matter is 3.54%, which is higher than the average content of about 2% of livestock manure.

Immediately after the hydrothermal carbonization reaction of Example 8, the carbonization slurry is judged to meet the conditions of the organic fertilizer in " Set fertilizer process standard and designation Schedule 3 ".

So far, the present invention has been focused on the preferred embodiments. Those skilled in the art to which the present invention pertains will appreciate that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered in terms of explanation, not limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent range should be interpreted as being included in the present invention.

10: motor 11: drive shaft
12: flow path in the discharge member 20: discharge member inlet
30: outlet of outlet member
101: sludge storage tank 102: no supply
103a, 103b: auxiliary reactor 104: heating oil pump
105: chemical storage tank 106: chemical pump
107: reactor 108: heating oil heater
109: first heat exchanger 110: second heat exchanger
111: cooler 112: exhaust member
113a: reservoir or gas separator 113b: gas separator
114: exhaust purifier 115: solid / liquid separator

Claims (8)

Hydrocarbonization of food waste to produce carbonized slurry;
Separating the solid product and the liquid desorption solution from the prepared carbonized slurry; And
Forming a solid product to produce a solid fuel; It includes,
The step of manufacturing the carbonized slurry is a method of manufacturing solid fuel using food waste, characterized in that it is performed under conditions of a temperature of 180 to 230 ° C and a pressure of 10 to 40 bar and a reaction time of 1 to 6 hours.
According to claim 1,
A method of manufacturing solid fuel using food waste, characterized in that the water content of food waste supplied to hydrothermal carbonization is 70 to 90%.
According to claim 1,
The step of manufacturing the carbonized slurry is a solid fuel production method using food waste, characterized in that made for 2 to 5 hours.
According to claim 1,
In the step of producing hydrocarbon slurry by hydrothermal carbonization of food waste,
A method of manufacturing solid fuel using food waste, characterized in that the food waste is supplied to a hydrothermal carbonization reactor in a state preheated to a temperature of 50 to 150 ° C.
According to claim 1,
In the step of manufacturing the carbide slurry,
Method for producing solid fuel using food waste, characterized in that it comprises a process of adding 0.5 to 5% by weight of sulfuric acid relative to the total weight of food waste.
According to claim 1,
The step of manufacturing the carbonized slurry is performed in a hydrothermal carbonization reactor,
The method for producing solid fuel using food waste is characterized in that the produced carbonized slurry is discharged from the reactor in a depressurized state via a section that is sequentially or continuously decompressed along the flow direction of the fluid.
According to claim 1,
The manufactured solid fuel
Method for producing solid fuel using food waste, characterized in that the low calorific value is 7,000 kcal / kg or more.
According to claim 1,
The manufactured solid fuel,
The water content is 10% or less,
Chlorine (Cl ^-) content of the method for producing a solid fuel using a food waste, characterized in that not more than 0.5% by weight.

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