KR20220080504A - Anaerobic Digestion System for Circulation and Mixed Crossing Operation with High-Efficiency Pyrolysis Reactor for Treating High-Concentration Organic - Google Patents

Abstract

The present invention relates to an anaerobic digestion system equipped with a high-efficiency pyrolysis reactor for processing high-concentration organic matter, and more particularly, to an anaerobic digestion system with a circulating and mixed-stirring operation. By installing it so that the mixture can be heated quickly, dehydration is improved by cell membrane destruction in a high-temperature and high-pressure environment, and its appearance is changed to a low-molecular, water-soluble amino acid of a high molecular weight cow that contains a large amount of fibrous components that were difficult to decompose by anaerobic microorganisms. It relates to an anaerobic digestion system in which circulation and mixed cross agitation operation that can increase the decomposition efficiency for etc. are made.

Description

Anaerobic Digestion System for Circulation and Mixed Crossing Operation with High-Efficiency Pyrolysis Reactor for Treating High-Concentration Organic

The present invention relates to an anaerobic digestion system equipped with a high-efficiency pyrolysis reactor for processing high-concentration organic matter, and more particularly, to an anaerobic digestion system with a circulating and mixed-stirring operation. By installing it so that the mixture can be heated quickly, dehydration is improved by cell membrane destruction in a high-temperature and high-pressure environment, and its appearance is changed to a low-molecular, water-soluble amino acid of a high molecular weight cow that contains a large amount of fibrous components that were difficult to decompose by anaerobic microorganisms. It relates to an anaerobic digestion system in which circulation and mixed cross agitation operation that can increase the decomposition efficiency for etc. are made.

Livestock manure also contains high concentrations of organic substances before being used as nitrogen and phosphorus fertilizers, so it needs to be stabilized.

With the enforcement of the "Law on Livestock Manure Management and Use" in 2007, livestock manure has been used as a resource such as compost and liquid manure, which has been used as fertilizer in farmland. However, due to the limited agricultural land situation in Korea and the ever-increasing number of livestock breeding heads, interest in the use of livestock manure resources other than fertilizer is continuously increasing.

A method of recovering high-concentration organic matter from livestock manure as energy rather than simple disposal is being developed. At the center of this, a method of recovering biogas, that is, methane gas, through anaerobic digestion to be used for fuel or power generation is being sought.

However, most of the biogas technology for livestock manure is applied to pig manure, and there is almost no biogas technology grafting for cattle manure.

The cow manure has a relatively low moisture content in the manure itself and contains a lot of fibrous components that are difficult to biodegrade, and since the traditional cattle management method in Korea is in the form of a litter, the manure and litter are discharged together, which takes a considerable amount of time for anaerobic digestion as well as dehydrated cake It also has a disadvantage in that it takes a long time to dry due to its high moisture content.

Korean Patent Registration No. 10-2029117 (registered on September 30, 2019; hereinafter referred to as 'Prior Document 1') suggests a thermal hydrolysis anaerobic digestion system for organic waste treatment. In Prior Document 1, organic waste is treated by applying thermal hydrolysis, but steam generated in a waste heat boiler or waste heat recovered from a reactor is directly mixed with organic waste to perform preheating. It has a disadvantage in that it takes a long time to preheat and warm up because the moisture content is high, so that the processing efficiency is lowered.

Korean Patent Application Laid-Open No. 10-2020-0048220 (published on May 8, 2020; hereinafter referred to as 'Prior Document 2') proposes a thermal hydrolysis anaerobic digestion system for organic waste. The prior document 2 also performed a thermal hydrolysis process prior to anaerobic digestion to increase the amount of biogas generated, but as in Prior Document 1, because steam is directly mixed in the thermal hydrolysis process, the moisture content of the mixed solution is increased, so preheating and heating time This takes a long time and has a disadvantage in that the processing efficiency is lowered.

Therefore, the need for an anaerobic digestion system having a piping structure capable of maximizing thermal efficiency while rapidly heating the reaction tank for hydrolysis has emerged.

Korean Patent No. 10-2029117 (Registered on September 30, 2019): Thermal hydrolysis anaerobic digestion device for organic waste treatment Korean Patent Publication No. 10-2020-0048220 (published on May 8, 2020): Thermal hydrolysis anaerobic digestion system of organic waste

The circulation and mixed cross-stirring anaerobic digestion system of the present invention for solving the problems of the prior art as described above,

For the aerobic decomposition of barn-discharged manure and bedding mixed cows that are difficult to decompose, pyrolysis is performed as a pre-treatment to achieve anaerobic digestion, and the biogas generated from anaerobic digestion is driven by a steam boiler that supplies steam to the pyrolysis tank. It is to provide a system that can supply heat by itself without fuel supply.

In particular, the thermal decomposition tank can provide a structure that enables rapid heating by piping a spiral heating tube for moving steam and installing a stirrer in the inner space to facilitate heat transfer to the stored mixed solution.

In addition, the purpose of the digester is to provide a system capable of increasing the anaerobic digestion rate by increasing the mixing rate by performing agitation and gas mixing and agitation by the cutting-grinder pump together.

The circulation and mixed cross-stirring anaerobic digestion system of the present invention for solving the above problems,

In an anaerobic digestion system for circulation and mixed cross-stir operation equipped with a high-efficiency thermal decomposition tank for processing high-concentration organic matter, the anaerobic digestion system comprising: a pyrolysis device for converting high-concentration livestock manure raw materials into low-molecular ones by breaking high molecular chains of cell membranes and protein enzymes; a pulverizer for pulverizing the mixed solution discharged from the pyrolysis device; a dehydrator for solid-liquid separation from the mixed solution pulverized by the pulverizer; an anaerobic digestion tank for storing the liquid separated in the dehydrator and performing anaerobic digestion with anaerobic microorganisms; a steam boiler that is driven by the biogas produced in the anaerobic digester and supplies the generated high-temperature steam to the pyrolysis device to heat the mixed solution by heat exchange; a heat exchanger for exchanging the mixed liquid discharged from the pyrolysis device and supplied to the grinder and the condensed water supplied from the condensate tank to the steam boiler; A control unit for controlling various flows; may be configured to include.

In addition, the pyrolysis device includes: a preheating tank for preheating the supplied raw material, which is high-concentration livestock manure, using generator waste heat; It may consist of a pyrolysis reaction tank that receives the preheated raw material from the preheating tank, breaks the polymer ring at high temperature and high pressure, converts it to a low molecular weight, and pyrolyzes the cell membrane to release the water inside the cell.

In addition, a preheating tube wound in a spiral shape to transfer generator waste heat is piped inside the preheating tank, and a heating tube wound in a spiral shape to transport steam boiler steam is piped in the pyrolysis reaction tank, and the preheating tube and the heating tube A stirrer may be arranged in the inner space to stir the stored raw materials.

In addition, the thermal decomposition reaction tank may be pyrolyzed by setting the internal reaction temperature to 150 ~ 155 ℃.

In addition, the anaerobic digestion tank, by installing a pump device in the lower side to mix the stored liquid; The pump device includes: a suction pipe communicating with the anaerobic digestion tank to draw out the liquid; a pump installed at the end of the suction pipe and provided with a rotary cutting blade for cutting the solids contained in the sucked liquid while sucking the liquid; a discharge pipe for discharging the liquid that has passed through the pump to the anaerobic digestion tank; A gas supply pipe that connects the upper part of the anaerobic digestion tank with the middle point of the discharge pipe to collect the gas from the upper part of the anaerobic digestion tank and supply it to the discharge pipe to discharge the gas and liquid together through the discharge pipe; and is configured to include.

In addition, the pump device may be arranged at an angle of 2 to 4 at the lower side of the side, and discharged in a direction deflected from the center of the anaerobic digestion tank to one side to mix the stored liquid.

The circulation and mixed cross stirring operation narrow air fire extinguishing system of the present invention by the above solution means,

A spiral heating tube is piped inside and a stirrer is installed in the central space, so that the stirred mixture moves freely inside and outside the heating tube while increasing the contact area, enabling rapid heating by heat exchange.

In addition, in the anaerobic digestion tank, gas mixing and agitation is performed together when agitating by the cutting-grinder pump, thereby increasing the mixing rate and increasing the anaerobic digestion rate to provide a system that can increase the production of methane gas, a combustible gas.

1 is a schematic diagram showing an anaerobic digestion system according to a preferred embodiment of the present invention.
Figure 2 is a schematic diagram showing a pyrolysis reactor according to an embodiment of the present invention.
3a and 3b are vertical and horizontal cross-sectional views showing a pyrolysis reactor according to the present invention.
Figure 4a is a vertical sectional view showing an anaerobic digestion tank installed with a pump device according to the present invention.
Figure 4b is an operating state diagram of the pump device according to the present invention.
5 is a photograph showing the growth change of livestock manure sludge for each process of the present invention.
6 is a graph showing the flow rate of methane gas according to the stirring method of the anaerobic digestion tank.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and the present invention will be described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing each figure, like reference numerals have been used for like elements. In the accompanying drawings, the dimensions of the structures are enlarged or reduced than the actual size for clarity of the present invention.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprise", "comprising" or "have" are intended to designate that a feature, number, step, operation, element, or combination thereof described in the specification exists, and is one or the It should be understood that the existence or addition of the above other features or numbers, steps, operations, elements or combinations thereof is not precluded in advance.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those generally used and defined in the dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and are not to be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. .

1 is a schematic diagram showing an anaerobic digestion system according to a preferred embodiment of the present invention.

As referenced, the anaerobic digestion system 10 for circulation and mixing cross-stirring operation equipped with a high-efficiency pyrolysis reaction tank for processing high-concentration organic matter according to the present invention includes a pyrolysis device 20 for receiving high-concentration livestock manure as a raw material and preheating it. .

The thermal decomposition device 20 applies heat to the supplied raw material to break the high molecular chain of the cell membrane and the protein enzyme and convert it to a low molecular weight. In other words, by heating the raw material to create an environment of high temperature (150℃) and high pressure (15kg/cm2), it reacts with hydrogen ions and hydroxide ions of water to break the polymer ring and change the properties to low-molecular water-soluble amino acids, making the anaerobic microorganisms difficult to decompose. It is made possible to increase the digestibility of fibrous cellulose.

In addition, since the cell membrane is destroyed in this process and internal water can be discharged, the dehydration property is improved to reduce the weight, and the calorific value of the solid product can be increased, so that it can be used as a solid fuel. In addition, since pathogens in the sludge are removed by high-temperature treatment, the pyrolyzed solid can be used as compost, so the use can be expanded.

The mixed solution pyrolyzed in the pyrolysis device 20 is supplied to the pulverizer 30, and the remaining solids are pulverized in the pulverizer operating at 3500 to 4500 rpm to reduce the size of the solids.

The mixed solution passing through the grinder is supplied to the dehydrator 40 to separate solid-liquid. The separated solid is dried to be used as a solid fertilizer or solid fuel, and the liquid is supplied to the anaerobic digestion tank 50 .

In the anaerobic digestion tank 50, the supplied liquid is stored and anaerobic digestion is performed by anaerobic microorganisms to generate a large amount of biogas, so that the residue is used as liquid fertilizer.

The biogas generated in the anaerobic digester 50 is supplied to the steam boiler 60 to be used as fuel. The steam boiler 60 may allow water to be supplied directly from the outside or water may be supplied through the condensate tank 70 .

The steam generated in the steam boiler 60 is supplied to the pyrolysis device 20 to exchange heat with the raw material, and the steam on which the heat exchange has been completed changes its properties to condensed water and is collected in the condensate tank 70, and the steam boiler Circulation is supplied to the pyrolysis device through the

A discharge valve for discharging excess condensate may be formed before and after the condensate tank 70, and a water supply line for supplying insufficient moisture may be connected. Various traps 71 such as U traps are installed between the pyrolysis device and the condensate tank to prevent the condensate from flowing backward.

In addition, the mixed solution discharged from the pyrolysis device 20 and supplied to the grinder 30 exchanges heat with the condensed water supplied from the condensate tank 70 to the steam boiler 60 through the heat exchanger 80, so that the steam boiler By increasing the temperature of the condensed water supplied to (60), it is possible to reduce the energy consumption consumed for steam generation.

In addition, a control unit 90 may be installed in the anaerobic digestion system 10 to control the flow by intermittent valves of various lines, or to control temperature or pressure.

When the pyrolysis apparatus of the present invention is described with reference to FIGS. 2 and 3A and 3B , the pyrolysis apparatus 20 of the present invention is configured to be separated into a preheating tank 21 and a pyrolysis reaction tank 22 .

The preheating tank 21 stores the supplied raw materials, preheats them, and then transfers them to the pyrolysis tank 22. As a heat source for preheating, the preheating is performed using waste heat from a generator such as a thermal power plant or a simple power plant.

In addition, the thermal decomposition reaction tank 22 receives the steam generated from the steam boiler 60 as described above and heats the preheated raw material for thermal decomposition. That is, the supplied preheated raw material is converted into a low molecule by breaking high molecular chains such as cell membranes and protein enzymes under high temperature and high pressure, and pyrolysis is performed by destroying the cell membrane and discharging the water inside the cell.

The preheating tank 21 and the pyrolysis reaction tank 22 are provided with a preheating tube 211 and a heating tube 221 wound in a spiral shape close to the inner wall therein to transfer waste heat from the generator and steam from the steam boiler. That is, the preheating tube 211 spirally piped inside the preheating tank 21 receives the generator waste heat to move inside, and during the movement process, heat exchange with the raw material stored in the preheating tank 21 is performed to preheat the raw material. make it At this time, in order to promote heat exchange between the raw material and waste heat transferred to the preheating tube 211 , a stirrer 212 may be disposed in the inner space of the piped preheating tube 211 to stir the raw material. The preheating tank 21 is described as utilizing waste heat from the generator, but is not limited thereto. It receives steam from a steam boiler or receives steam discharged from a pyrolysis tank, passes it through a preheating tube, and then moves the condensate to condensate. can make this happen

Similarly, the heating tube 221 is spirally piped close to the inner wall of the pyrolysis reactor 22 as well, and a stirrer 222 is installed in the central space of the heating tube to achieve stirring, so that the amount of heat exchange between the stored raw material or mixed solution and the heating tube can be increased to enable rapid heat exchange.

The preheating tube 211 and the heating tube 221 are spaced apart from the inner walls of the preheating tank 21 and the thermal decomposition reaction tank 22 by a predetermined distance through a separate fixing means, thereby exchanging heat through the entire area of the preheating tube and the heating tube. can make this happen

The internal reaction temperature of the thermal decomposition reaction tank 22 is set to 150 ~ 155 ℃ so that the thermal decomposition is made. The dehydration performance of livestock dung sludge and high-concentration livestock manure, which are raw materials, is increased from 150°C due to the increase in viscosity due to the release of EPS (Extracellular Polymeric Substances) composed of amino acids, proteins, and nucleic acids caused by the destruction of flocs and cell walls of the sludge. The temperature suitable for dehydration is about 150°C. In addition, the reaction temperature inside the pyrolysis reactor is given a temperature increase time and a temperature decrease time, but the reaction time is maintained for about 30 minutes at the set temperature, for example, 25 to 40 minutes, so that the efficiency compared to the supplied energy can be increased.

As shown in Fig. 4a, a pump device 51 is installed in the anaerobic digestion tank 50 to mix the stored liquid.

The pump device 51 can mix liquids using various pumps, and typically uses a cutting-grind pump that provides suction by a rotating cutting blade therein to suck and discharge liquids. In the process, it is possible to increase the gas production efficiency by increasing the contact with anaerobic microorganisms by pulverizing the organic matter remaining in the liquid into small pieces.

The pump device 51 is provided with a suction pipe 52 that is installed in communication with the lower side of the anaerobic digestion tank to withdraw the liquid in the anaerobic digestion tank and transfer it to the outside of the anaerobic digestion tank. A shut-off valve may be installed in the suction pipe to open and close the internal flow path.

In addition, a pump 53 is installed at the end of the suction pipe located outside the anaerobic digestion tank. The pump is a part that rotates by driving a motor to generate suction force, and in the present invention, a cutting-grind pump that generates suction power by a rotating cutting blade is used.

One end of the discharge pipe 54 is communicated in the discharge direction of the pump. The discharge pipe may be installed so that the other end communicates with the anaerobic digestion tank to discharge the liquid discharged from the pump into the anaerobic digestion tank to cause mixing and circulation of the liquid. A shut-off valve may also be installed in the discharge pipe to regulate the internal flow path.

In the present invention, a gas supply pipe 55 for supplying the gas collected in the upper part of the anaerobic digestion tank 50 to the discharge pipe 54 and mixing it with the liquid to be transported is further installed. One end of the gas supply pipe 55 communicates with the upper part of the anaerobic digestion tank to introduce gas, and the other end communicates with the middle point of the discharge pipe 54 to supply the gas from the upper part of the anaerobic digestion tank to the discharge pipe.

Here, the discharge pipe 54 is piped in a straight line so that the liquid is discharged by going straight at high pressure, and the gas supply pipe 55 is vertically piped to the discharge pipe so that gas is sucked into the discharge pipe by the discharge pressure of the discharge pipe. and discharge occurs together. In this case, a check valve may be mounted on the gas supply pipe 55 to prevent a reverse flow of liquid water from the discharge pipe 54 to the gas supply pipe, or an angle between the gas supply pipe and the inlet portion of the discharge pipe may be formed at an acute angle.

In addition, a pump may be additionally mounted on the gas supply pipe to supply gas to the discharge pipe at high pressure to increase the gas mixture amount.

Two to four pump devices 51 installed in the anaerobic digestion tank 50 may be arranged at an equal angle.

Figure 4b shows that three pump devices 51 are installed at an equal angle to achieve internal agitation in the anaerobic digestion tank 50. The discharge direction of each pump device is deflected from the center of the anaerobic digestion tank to one side, so that the liquid in the anaerobic digestion tank is stirred while rotating in one direction.

1. Estimation of optimum operating temperature of pyrolysis reactor of pyrolysis device

1-1) Experimental conditions

As an experimental device, the anaerobic digestion system to which FIGS. 1 and 2 of the present invention was applied was applied. For example, a pyrolysis device having a preheating tank and a pyrolysis tank is provided, the preheating tank is supplied with waste heat of a generator to be preheated, and the pyrolysis tank is heated by supplying steam by a steam boiler. Moisture supplied to the steam boiler is provided from the condensate tank, and heat exchange is made with the mixed solution discharged from the pyrolysis reactor through a heat exchanger before supply. The mixed solution was passed through a grinder and supplied to a dehydrator to perform solid-liquid separation, and the separated liquid was supplied to an anaerobic digestion tank to achieve anaerobic digestion.

The TS of the livestock dung sludge mixture was 22% and the moisture content was 78%, and the TS of the high-concentration livestock manure was 8% and the moisture content was 92%.

In order to analyze the characteristics of the liquid product and desorbent generated after the experiment, water quality analysis was performed according to the water pollution process test standards.

In addition, elemental analysis was performed using an Elemental Analyzer (Flash EA 1112 series) to analyze the chemical composition of the solid product produced after the dehydration process.

In addition, in order to evaluate the value as a fuel, industrial analysis and calorific value were measured based on KS E3709 regulations.

In addition, in order to evaluate the environmental risk, the content of heavy metals was analyzed according to the water pollution process test standards.

In addition to the purpose of reducing moisture by improving the dehydration ability of livestock manure and sludge, the thermal decomposition reaction measures the calorific value of the solid product generated after the thermal decomposition reaction and is effective in converting energy that can be used as a solid fuel.

1-2) Component Analysis

In order to evaluate the characteristics of solid products and the possibility of turning them into fuels, ternary analysis, elemental analysis, and calorific value analysis were performed on livestock manure sludge dewatered cakes with a reaction temperature of 150°C or higher for dehydration. The results are presented in [Table 1-1] and It is shown in [Table 1-2].

[Table 1-1] is the analysis of the dewatered cake of livestock manure sludge, and [Table 1-2] shows the elemental analysis and the calorific value analysis of the dehydrated cake of livestock manure sludge.

[Table 1-1]

[Table 1-2]

As a result of the analysis, there was no significant difference in moisture content, ash content, elemental composition, and calorific value by reaction temperature. The moisture content was 47.8~49.2%, which was less than 50%, and the combustible content was 21.4~22.8%, and the ash content was 29.4~29.8%. In addition, as a result of elemental analysis, the carbon (C) content was analyzed to be more than 40% higher than other elements. Although the ash content is relatively high, the fuel conversion characteristics are not good, but when the reaction temperature is 150℃, the high calorific value is 2,665 kcal/kg and the low calorific value is 2,220 kcal/kg, which is judged to be sufficiently valuable as a fuel. Therefore, the solid content can be used as its own heat source for the pyrolysis facility after drying by using waste heat, and the utilization value can be increased by supplying it to the power generation facility.

[Table 1-] 3] and [Table 1-4].

The following [Table 1-3] is an industrial analysis of high-concentration livestock manure dehydrated cake, and [Table 1-4] shows the analysis of high-concentration livestock manure elements and calorific value.

[Table 1-3]

[Table 1-4]

As mentioned, the moisture content was less than 50%, the carbon content was high, and the low calorific value was 2,160 kcal/kg, similar to the dewatered cake of livestock manure sludge.

2. Estimation of optimal operating conditions according to pig manure and cow manure input

2-1) Experimental method

Experiments were conducted on the optimal pyrolysis reactor temperature, pressure conditions, reaction time, operation method, and temperature change of reactants according to pig manure and cattle manure input conditions.

Livestock manure and sludge were tested. Since the main components of livestock manure and cow manure are protein and hemicellulose, it can be decomposed at 150℃ or higher, and when the thermal decomposition temperature is 200℃ or higher, anaerobic digestion inhibitors are generated. Therefore, it is known that the generation of methane gas is reduced. Therefore, in this experiment, the operating temperature was changed from 130°C to 200°C.

The operating pressure increased to 12.72 ~ 22.20kg/cm2 as the set operating temperature increased. At this time, the pressure inside the reactor is higher than the saturated water vapor pressure of the corresponding temperature due to the increase in the volume of the sludge.

The total time required for operation was 60 minutes for temperature increase, 60 minutes for steam input, 30 minutes for operation (reaction) time, 60 minutes for temperature reduction/decompression time, a total of 210 minutes. According to the experiment, the optimal operating time for pyrolysis is 30 minutes, and if the operating time is longer, the pyrohydrolysis efficiency increases, but as the reaction time increases, the amount of energy input also increases. . Therefore, in consideration of economic feasibility, the optimum operation time was operated for 30 minutes.

In order to analyze the characteristics of the liquid product and desorbent generated after the experiment, water quality analysis was performed according to the water pollution process test standards.

2-2) Experiment result

5 is a photograph showing the process of change in the properties of livestock manure sludge. It was confirmed that a large amount of moisture was separated through the pyrolysis process.

As a result of water quality analysis of the liquid product produced after the thermal hydrolysis reaction of livestock manure sludge, it was confirmed that the solubilization rate increased as the operating (reaction) temperature increased. Solubilization is to change the solid material into a soluble material by destroying the cell wall of microorganisms in the sludge. In general, SCOD _Cr , NH4 ⁺ -N, and SCOD _Cr /TCOD _Cr ratio increase is used as a representative indicator to determine the solubilization characteristics.

The following [Table 2-1] shows the characteristics of the liquid product according to the reaction temperature of the livestock manure sludge treatment.

[Table 2-1]

In this experiment, as the reaction temperature increased, as shown in Table 2-1, it was confirmed that the concentrations of SCOD _Cr , NH4 ⁺ -N increased, and the ratio of NH4 ⁺ -N/TN also increased. As the thermal decomposition reaction proceeded, organic nitrogen It is thought to have been converted to ammonia nitrogen.

In addition, as the reaction temperature increased, it was confirmed that TS and TCOD _Cr increased and SS decreased.

[Table 2-2] shows the characteristics of liquid products according to the reaction temperature of high concentration livestock manure.

[Table 2-2]

Looking at [Table 2-2] showing the experimental results using high-concentration livestock manure sludge (TS 8%), it was confirmed that the treatment tendency was similar to that of [Table 2-1] using livestock manure sludge. That is, it was confirmed that the solubilization rate increased as the operating reaction temperature increased.

The following [Table 2-3] and [Table 2-4] show the characteristics of the desorbent according to the treatment reaction temperature of livestock manure sludge and high-concentration livestock manure sludge.

[Table 2-3]

[Table 2-4]

[Table 2-3] and [Table 2-4] are the results of water quality analysis of the desorbed liquid separated after dehydrating the liquid product generated after treatment of livestock manure sludge and high-concentration livestock manure with a dehydrator.

The SS of the desorbent having reaction temperatures of 170 °C and 180 °C is higher than other temperatures, because dehydration was not smooth. Thermal hydrolysis reaction is a method to increase dehydration by destroying flocs and cell walls of sludge, but at a reaction temperature of less than 190℃, EPS (Extracellular Polymeric Substances, supercytoplasmic) composed of amino acids, proteins, nucleic acids, etc. It seems that the dehydration performance is lowered due to the increase in viscosity due to the discharge of polymeric substances). The EPS material starts to be destroyed at 150 °C, and it is judged that most of the EPS material is destroyed from 180 °C.

Judging from the above results, it is considered that 150 ° C is the minimum temperature required for dehydration, and when the SCOD _Cr / TCOD _Cr ratio, which is an index indicating the solubilization rate, also converges to 1 from 150 ° C., thermal hydrolysis considering economic feasibility. The optimum reaction temperature is determined to be 150 °C.

In addition, the removal rate of solids (TS) after dehydration showed an average removal rate of 81% for livestock manure sludge, and it was found that the removal rate for high-concentration livestock manure was high with an average removal rate of 82%.

3. Selection of optimal anaerobic digestion using the method of cross-operation of cutting-grind pump circulation and gas mixing and agitation

The optimal stirring method was reviewed by inputting the raw material after the thermal hydrolysis reaction into the digester, collecting methane gas flow data generated during anaerobic digestion, and measuring the amount of methane gas generated by each stirring method.

1) Measurement method

The data on the flow rate of methane gas was measured according to each stirring method and measurement period as shown in [Table 3].

[Table 3]

The external pump circulation type agitation is a method in which a pump is installed on the outside of the digester to withdraw the liquid material from the inside and the bottom of the digester and discharge it back to the upper part.

Also, cutting grinder pump agitation is a method of cutting and stirring suspended sludge.

In addition, gas mixing is a method of mixing gas and sludge according to the venturi principle and discharging it through a nozzle.

In addition, the cutting grinder pump pump stirring + gas mixing stirring is a method of cross-operating the cutting grinder pump stirring and gas mixing stirring.

The stirring was measured using two anaerobic digestion tanks (R1, R2), respectively.

2) Measurement result

Since the data collection period is different for each method, the average flow rate for methane gas generation was reviewed.

The result of measuring the average flow rate of methane gas produced after anaerobic digestion is shown in FIG. 6 .

As referenced, 1-R1: 20.03㎥/hr, 1-R2: 19.96㎥/hr, 2-R1: 22.27㎥/hr, 2-R2: 21.68㎥/hr, 3-R1: 24.16㎥/hr, 3- R2: It was found to be 25.06 m3/hr.

It was found that the methane generation of the circulating agitation of the cutting grinder pump increased by more than 8% compared to the methane generation of the external pump circulation type agitation, and the methane generation amount of the cutting grinder pump circulation type + gas mixture stirring compared to the methane generation amount of the cutting grinder pump circulation type stirring showed an increase of more than 2%. In addition, compared to the amount of methane generated by external pump circulation type agitation, it was found that the methane generation amount of the cutting grinder pump circulation type + gas mixture stirring increased by more than 23%.

Comprehensively judging the above results, the cutting grinder pump circulation type + gas mixture stirring method was found to be the most effective.

3) Cutting grinder pump and gas mixing stirring effect

The cutting grinder pump and gas mixing and agitation can increase gas efficiency by finely pulverizing the organic mass and increasing the generated gas by increasing contact with anaerobic microorganisms.

In addition, the scum layer can be removed by continuously mixing and supplying through the upper methane gas.

In addition, since the pump is installed outside, maintenance and management are easy, and the use time can be increased because of its higher durability than other agitators.

In addition, stirring is possible even under conditions of 10% or more of TS, and there is an advantage that scum or precipitation does not occur or can be minimized.

10: anaerobic digestion system
20: pyrolysis device
21: preheating tank 22: pyrolysis reaction tank
211: preheating tube 212,222: agitator
221: heating tube
30: grinder
40: dehydrator
50: anaerobic digestion tank
51: pump device 52: suction pipe
53: pump 54: discharge pipe
55: gas supply pipe
60: steam boiler
70: condensate tank
71 : trap
80: heat exchanger
90: control unit

Claims (6)

In the anaerobic digestion system for circulation and mixed cross-stirring operation equipped with a high-efficiency pyrolysis tank for high-concentration organic matter treatment,
a thermal decomposition device 20 for receiving high-concentration livestock manure raw material and preheating it to break the high molecular chain between the cell membrane and the protein enzyme and convert it to a low molecular weight;
a pulverizer 30 for pulverizing the mixed solution discharged from the pyrolysis device;
a dehydrator 40 for solid-liquid separation from the mixed solution pulverized in the pulverizer;
an anaerobic digestion tank 50 for storing the liquid separated in the dehydrator and performing anaerobic digestion with anaerobic microorganisms;
a steam boiler 60 that is driven by biogas produced in the anaerobic digester and supplies the generated high-temperature steam to the pyrolysis device to heat the mixed solution by heat exchange;
a heat exchanger 80 for exchanging heat between the mixed liquid discharged from the pyrolysis device 20 and supplied to the grinder 30 and the condensed water supplied from the condensed water tank 70 to the steam boiler 60;
Anaerobic digestion system for circulation and mixed cross-stirring operation, characterized in that it includes; a control unit 90 for controlling various flows. According to claim 1,
The pyrolysis device 20,
a preheating tank 21 for preheating the supplied raw material, which is high-concentration livestock manure, using generator waste heat;
A pyrolysis reactor 22 that receives the preheated raw material from the preheating tank, breaks the polymer ring at high temperature and high pressure, converts it to a low molecular weight, and discharges the water inside the cell by breaking the cell membrane. Mixed cross agitation operation anaerobic digestion system. 3. The method of claim 2,
A preheating tube 211 is piped inside the preheating tank 21 to transfer waste heat from the generator wound in a spiral shape,
A heating tube 221 is piped inside the pyrolysis reaction tank 22, which is wound in a spiral shape to transport steam boiler steam,
Anaerobic digestion system for circulation and mixing cross-stirring operation, characterized in that by disposing agitators (212,222) in the inner space of the preheating tube (211) and the heating tube (221), the stored raw material is stirred. 3. The method of claim 2,
The pyrolysis reaction tank 22 is an anaerobic digestion system with circulation and mixed cross-stirring operation, characterized in that the internal reaction temperature is set to 150 ~ 155 ℃ so that the thermal decomposition is made. According to claim 1,
The anaerobic digestion tank 50, a pump device 51 is installed in the lower side to mix the stored liquid;
The pump device 51,
a suction pipe 52 communicating with the anaerobic digestion tank and withdrawing the liquid;
a pump 53 installed at the end of the suction pipe and provided with a rotary cutting blade for cutting the solids contained in the sucked liquid while sucking the liquid;
a discharge pipe 54 for discharging the liquid that has passed through the pump to the anaerobic digestion tank;
A gas supply pipe (55) that connects the upper part of the anaerobic digestion tank and the middle point of the discharge pipe to collect the gas at the upper part of the anaerobic digestion tank and supply it to the discharge pipe to discharge the gas and the liquid together through the discharge pipe; Anaerobic digestion system, characterized in that the circulation and mixed cross agitation operation. 6. The method of claim 5,
The pump device 51 is arranged at an angle of 2 to 4 in the lower side of the side, and discharged in a direction deflected from the center of the anaerobic digestion tank 50 to one side to mix the stored liquid. Circulation and Mixed cross agitation operation anaerobic digestion system.

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