Apparatus for anaerobic digestion with air injection device

Abstract

The present invention relates to an anaerobic digestion device equipped with an air injection facility, characterized by comprising: a substrate input unit that supplies a substrate in which organic waste resources have been pretreated; an anaerobic digestion unit that produces biogas; an air injection unit that injects micro-air into the anaerobic digestion unit; a gas analysis unit that analyzes the concentration of each substance contained in the biogas produced in the anaerobic digestion unit; a digestion liquid circulation unit that draws out the digestion liquid from the lower part of the anaerobic digester and introduces it to the upper part for circulation; and a sulfur precipitate removal unit that removes sulfur precipitates generated by oxidizing hydrogen sulfide contained in the biogas. By providing an air injection port that injects optimal micro-air into the digestion liquid of the anaerobic digester, the present invention provides the effect of achieving primary desulfurization of the hydrogen sulfide concentration in the biogas to 400 ppm or less by oxidizing the hydrogen sulfide contained in the biogas to sulfur through air injection by sulfur-oxidizing bacteria.

Description

Technology Field

[0001] The present invention relates to an anaerobic digestion device equipped with an air injection facility, and more specifically, to an anaerobic digestion device equipped with an air injection facility capable of desulfurizing by injecting optimal fine air into the digestion liquid of an anaerobic digester. Background Technology

[0002] With the enactment and implementation of the Biogas Act (Act on the Promotion of Production and Use of Biogas from Organic Waste Resources), the rapid proliferation of anaerobic digestion (biogasification) facilities targeting organic waste resources such as food waste, sewage sludge, human waste, and livestock manure is expected, and biogas produced in anaerobic digesters, which is mainly composed of methane (CH4), is receiving a lot of attention in terms of its utilization as an alternative fuel to LNG.

[0003] As of the end of 2023, there were 112 domestic biogasification facilities, and the annual amount of biogas generated from these facilities was 362,326 thousand cubic meters. Looking at the usage by purpose, it was found that 49,853 thousand cubic meters (13.8%) was used for power generation, 100,125 thousand cubic meters (27.6%) was supplied to external sources, and 113,638 thousand cubic meters (31.4%) was used for internal purposes. The amount of unused biogas that is simply incinerated amounts to 60,714 thousand cubic meters, which is 16.8% of the total generated amount.

[0004] In addition, looking at the composition of biogas, methane (CH4) accounts for 50–75 vol% and carbon dioxide (CO2) accounts for 25–45 vol%, making up the majority. In particular, hydrogen sulfide (H2S) 2,500–20,000 ppm is included as a key impurity that must be removed when utilizing biogas in power generation or boiler facilities.

[0005] The effects of hydrogen sulfide contained in biogas include the generation of corrosive sulfuric acid through reaction with water vapor, which causes corrosion (stress corrosion) in biogas utilization facilities and piping; the generation of foul odors due to atmospheric release of H2S during incomplete combustion; and the formation of sulfur oxides (SOx) by hydrogen sulfide when biogas containing hydrogen sulfide is burned, which can lead to not only atmospheric pollution but also corrosion of biogas utilization facilities; therefore, the removal of hydrogen sulfide from biogas is absolutely necessary for the energy conversion of biogas.

[0006] The primary desulfurization method for hydrogen sulfide in biogas (below 1,000 ppm) is generally a chemical method in which FeCl2 or FeCl3 is directly introduced into an anaerobic digester to react with hydrogen sulfide and remove hydrogen sulfide through the precipitation of sulfides (FeS).

[0007] However, operating costs increase due to the use of FeCl2 (or FeCl3), and if the amount of FeCl2 (or FeCl3) is excessive, the dewatered cake at the downstream end of the digester contains a large amount of sulfur (S), which may cause a problem where the sulfur content exceeds 2%, the fuel standard under the Waste Management Act, when producing dried products through the drying of the dewatered cake into fuel.

[0008] In addition, FeCl2 (or FeCl3) is a substance subject to management under the Chemical Substances Control Act, so it must be strictly maintained. However, as it is a corrosive chemical, it causes corrosion in pipes, pumps, etc., leading to increased operating costs and difficulties in maintenance.

[0009] In addition, as shown in Fig. 5, there is a method of injecting air into the headspace, which is an empty space above the upper water surface of the anaerobic digester, to oxidize hydrogen sulfide in the biogas into sulfur (S) by sulfur-oxidizing bacteria (SOB), or installing a carrier in the headspace to create habitat conditions for sulfur-oxidizing bacteria (SOB) and then injecting air to oxidize hydrogen sulfide in the biogas into sulfur by sulfur-oxidizing bacteria.

[0010] However, in the case of this method, elemental sulfur (S) precipitates upon air injection and adheres to the upper part of the anaerobic digester, which increases the likelihood of corrosion. Additionally, if a carrier is used, elemental sulfur adheres to the carrier, and the attached sulfur gradually increases, causing a problem where it cannot be removed until the anaerobic digester is emptied. Prior art literature

[0011] Republic of Korea Published Patent No. 10-2023-0012214 (January 26, 2023) Republic of Korea Registered Patent No. 10-1683629 (December 7, 2016) Republic of Korea Registered Patent No. 10-1386946 (April 18, 2014) The problem to be solved

[0012] The present invention was devised to resolve the aforementioned conventional problems, and aims to provide an anaerobic digestion device equipped with an air injection facility capable of achieving primary desulfurization of the hydrogen sulfide concentration in the biogas to 400 ppm or less by oxidizing the hydrogen sulfide contained in the biogas to sulfur by sulfur-oxidizing bacteria through air injection by providing an air injection port for injecting optimal micro-air into the digestion liquid of the anaerobic digester.

[0013] In addition, another objective of the present invention is to provide an anaerobic digestion device equipped with an air injection system that can reduce the cost of iron salt chemicals for primary desulfurization and reduce the operating costs of the facility, because it is not necessary to inject iron salt for primary desulfurization, and hydrogen sulfide can be oxidized to sulfur by sulfur-oxidizing bacteria through micro-air injection, thereby maintaining the hydrogen sulfide concentration in biogas at 400 ppm or less.

[0014] In addition, another objective of the present invention is to provide an anaerobic digestion device equipped with an air injection facility that minimizes maintenance personnel and reduces facility operating costs by implementing an unmanned automatic control operation system, wherein the substrate input section, anaerobic digestion section, air injection section, gas analysis section, digestion liquid circulation section, and sulfur precipitate removal section are all controlled by a PLC automatic control system. means of solving the problem

[0015] The present invention, for achieving the above-mentioned purpose, is an anaerobic digestion device for treating organic waste resources, comprising: a substrate input unit (100) that removes foreign substances through pretreatment by crushing and sorting organic waste resources according to each substrate, temporarily stores the pretreated substrate in an intermediate storage tank, and supplies the pretreated substrate; an anaerobic digestion unit (200) installed downstream of the substrate input unit (100), which produces biogas by decomposing the pretreated substrate, into which organic waste resources are pretreated according to substrate, by microorganisms; an air injection unit (300) installed on one side of the anaerobic digestion unit (200), which injects fine air into the anaerobic digestion unit (200) through an air nozzle; and a gas analysis unit (400) installed on the other side of the anaerobic digestion unit (200), which analyzes the concentration of each substance contained in the biogas produced in the anaerobic digestion unit (200). The apparatus is characterized by comprising: a digestion liquid circulation unit (500) installed at one downstream side of the anaerobic digestion unit (200) and circulating the digestion liquid by drawing it out from the lower part of the anaerobic digestion tank and introducing it into the upper part of the anaerobic digestion tank for up-and-down stirring in the anaerobic digestion tank of the anaerobic digestion unit (200); and a sulfur precipitate removal unit (600) installed at the other downstream side of the anaerobic digestion unit (200) and removing the sulfur precipitate generated by oxidizing hydrogen sulfide contained in the biogas inside the anaerobic digestion tank by fine air injected from the air injection unit (300).

[0016] The substrate input unit (100) of the present invention is characterized by comprising: an intermediate storage tank for storing each substrate of the pretreated organic waste resource; a substrate supply pump installed downstream of the intermediate storage tank for supplying the substrate stored in the intermediate storage tank to the anaerobic digestion unit (200); and a substrate supply electric valve installed downstream of the substrate supply pump for controlling the supply amount of the substrate.

[0017] The intermediate storage tank of the present invention is characterized by maintaining the internal temperature of the intermediate storage tank at a predetermined medium temperature through heating using hot water produced by utilizing the biogas produced in the anaerobic digester, thereby performing the function of an acid fermentation tank.

[0018] The anaerobic digestion unit (200) of the present invention is characterized by comprising: a cylindrical anaerobic digester having a plurality of air injection pipes spaced at equal intervals around the lower circumference so as to spray fine air evenly throughout the interior by stirring; and a vertical shaft type stirrer having an impeller integrally installed on the upper part of the anaerobic digester.

[0019] The air injection unit (300) of the present invention is characterized by comprising: an air blower for injecting external air; an air control valve installed downstream of the air blower for controlling the amount of air injected; and an air supply nozzle installed downstream of the air control valve for generating and supplying microbubbles to the injected air.

[0020] The air control valve of the present invention is characterized by controlling the amount of air injected to 0.5 to 1.5 mL / min. The air supply nozzle of the present invention is characterized by supplying fine air while maintaining the particle size of fine air at 30 to 100 μm.

[0021] The gas analysis unit (400) of the present invention is characterized by comprising: a biogas control valve that controls the transfer of biogas produced in the upper space of the anaerobic digester of the anaerobic digestion unit (200); and a gas analyzer installed downstream of the biogas control valve that analyzes gases of H2S, O2, CH4, and CO2 contained in the biogas transferred through the biogas control valve.

[0022] The digestion fluid circulation unit (500) of the present invention is characterized by comprising: a digestion fluid withdrawal electric valve connected to a digestion fluid withdrawal pipe installed at the bottom of the anaerobic digester of the anaerobic digestion unit (200) to control the amount of digestion fluid withdrawn; a digestion fluid circulation pump installed downstream of the digestion fluid withdrawal electric valve to supply digestion fluid withdrawn from the anaerobic digester to the top of the anaerobic digester to circulate digestion fluid; a digestion fluid inlet electric valve installed at the top of the anaerobic digester of the anaerobic digestion unit (200) to control the amount of digestion fluid inlet; a pH meter installed upstream of the digestion fluid inlet electric valve to measure the pH of the digestion fluid; and an ORP meter installed upstream of the digestion fluid inlet electric valve to measure the ORP (Oxidation Reduction Potential) of the digestion fluid.

[0023] The sulfur precipitate removal unit (600) of the present invention comprises: a precipitate removal valve installed at the lower part of the anaerobic digester of the anaerobic digestion unit (200) to control the discharge amount of sulfur precipitate generated in the anaerobic digester; a hydrocyclone supply pump installed downstream of the precipitate removal valve to pressurize the sulfur precipitate discharged from the anaerobic digester; a hydrocyclone installed downstream of the hydrocyclone supply pump to separate the supplied sulfur precipitate by centrifugal force and difference in specific gravity; a separated liquid inlet electric valve installed at one end downstream of the hydrocyclone to introduce the filtrate separated from the hydrocyclone into the upper part of the anaerobic digester; and a buffer tank installed at the other end downstream of the hydrocyclone to temporarily store the sulfur precipitate separated from the hydrocyclone. and a digestion sludge storage tank installed downstream of the buffer tank to remove sulfur precipitates transferred from the buffer tank; characterized by including

[0024] The air volume control of the air injection unit (300) of the present invention is characterized by being automatically controlled by an automatic control system of a PLC (Programmable logic controller) in a central control room.

[0025] The amount of air injected by the air injection unit (300) of the present invention is characterized by being automatically controlled in conjunction with the measured value of the digestive fluid measured by the digestive fluid circulation unit (500) and the concentration value of the gas analyzed by the gas analysis unit (400). Effects of the invention

[0026] As described above, the present invention provides the effect of achieving primary desulfurization of the hydrogen sulfide concentration in the biogas to 400 ppm or less by oxidizing the hydrogen sulfide contained in the biogas to sulfur by sulfur-oxidizing bacteria through air injection by providing an air inlet for injecting optimal micro-air into the digestion liquid of an anaerobic digester.

[0027] In addition, since it is not necessary to inject iron salt for primary desulfurization, hydrogen sulfide is oxidized to sulfur by sulfur-oxidizing bacteria through micro-air injection, allowing the hydrogen sulfide concentration in the biogas to be maintained at 400 ppm or less. This provides the effect of reducing the cost of iron salt chemicals for primary desulfurization and reducing the operating costs of the facility.

[0028] In addition, the substrate input section, anaerobic digestion section, air injection section, gas analysis section, digestion fluid circulation section, and sulfur precipitate removal section are all controlled by a PLC automatic control system, thereby enabling the implementation of an unmanned automatic control operation system that minimizes maintenance personnel and reduces facility operating costs. Brief explanation of the drawing

[0029] FIG. 1 is a schematic diagram showing an anaerobic digestion device equipped with an air injection facility according to one embodiment of the present invention. FIG. 2 is a detailed configuration diagram showing an anaerobic digestion device equipped with an air injection facility according to one embodiment of the present invention. FIG. 3 is a schematic diagram showing an air injection section of an anaerobic digestion device equipped with an air injection facility according to one embodiment of the present invention. FIG. 4 is a schematic diagram showing the anaerobic digestion section of an anaerobic digestion device equipped with an air injection facility according to one embodiment of the present invention. FIG. 5 is a schematic diagram showing a conventional anaerobic digestion device equipped with an air injection system. Specific details for implementing the invention

[0030] Hereinafter, a preferred embodiment of the present invention will be described in more detail with reference to the attached drawings.

[0031] FIG. 1 is a configuration diagram showing an anaerobic digestion device equipped with an air injection facility according to one embodiment of the present invention, FIG. 2 is a detailed configuration diagram showing an anaerobic digestion device equipped with an air injection facility according to one embodiment of the present invention, FIG. 3 is a configuration diagram showing an air injection section of an anaerobic digestion device equipped with an air injection facility according to one embodiment of the present invention, and FIG. 4 is a configuration diagram showing an anaerobic digestion section of an anaerobic digestion device equipped with an air injection facility according to one embodiment of the present invention.

[0032] As shown in FIGS. 1, 2 and 4, the anaerobic digestion device equipped with an air injection facility according to the present embodiment comprises a substrate input section (100), an anaerobic digestion section (200), an air injection section (300), a gas analysis section (400), a digestion liquid circulation section (500), and a sulfur precipitate removal section (600), and is an anaerobic digestion device for treating organic waste resources.

[0033] The substrate input unit (100) is a substrate input member that supplies pretreated substrates by removing foreign substances through pretreatment of crushing and sorting organic waste resources according to each substrate and temporarily storing them in an intermediate storage tank, and is composed of an intermediate storage tank (101), a substrate supply pump (102), and a substrate supply electric valve (103).

[0034] The intermediate storage tank (101) is a storage member for storing each substrate of pre-treated organic waste resources, and it is possible for the intermediate storage tank (101) to perform the function of an acid fermentation tank by maintaining the internal temperature of the intermediate storage tank at a predetermined medium temperature through heating using hot water produced by utilizing biogas produced in the anaerobic digestion tank (201).

[0035] In this intermediate storage tank (101), the substrates are temporarily stored before being fed into the anaerobic digestion tank (201) after pretreatment such as multi-stage crushing and sorting of organic waste resources, which removes more than 97% of foreign substances and reduces the particle size to 3 mm or less, which is the optimal condition for anaerobic digestion input for each substrate.

[0036] In addition, the intermediate storage tank (101) utilizes the biogas produced in the anaerobic digestion tank (201) and uses hot water produced in the co-firing boiler to heat the intermediate storage tank (101) to maintain a medium temperature condition of 36℃, thereby having the function of an acid fermentation tank.

[0037] After undergoing temporary storage and acid fermentation processes in the intermediate storage tank (101), it is transferred by the operation of the substrate supply pump (102), and a substrate supply electric valve (103) is installed in the upstream piping of the anaerobic digestion tank (201) to control the supply amount of the pretreated substrate.

[0038] In addition, the intermediate storage tank (101) is installed with a capacity that allows it to stay for 5 days, which is 5 times the daily intake amount, and the intermediate storage tank (101) simultaneously performs the roles of temporary storage of pre-treated substrate and acid fermentation tank.

[0039] A wall is installed in the center of the intermediate storage tank (101) to divide it into three storage zones, and the upper height of the wall is lowered by 30 cm below the water level so that the pre-treated substrate can move through the upper part of each storage zone, and it is possible to install a vertical shaft type agitator in each storage zone to achieve complete mixing.

[0040] In addition, when pouring concrete on the bottom surface of the intermediate storage tank (101), each corner of the bottom surface of the intermediate storage tank (101) is poured with a 1:1 slope by haunch treatment, and the height is made to be 30 cm or more, thereby preventing the occurrence of dead space during mixing.

[0041] The heating of the intermediate storage tank (101) is achieved by producing hot water from the biogas produced in the anaerobic digester in a co-firing boiler and maintaining the temperature inside the tank at 36°C through heat exchange in a double-pipe heat exchanger, and by installing a thermometer and a pH meter in each zone on the upper part of the intermediate storage tank (101), the function of the acid fermentation tank can be monitored.

[0042] The substrate supply pump (102) is a pump member installed downstream of the intermediate storage tank (101) to supply the substrate stored in the intermediate storage tank (101) to the anaerobic digestion unit (200), and it is obvious that this substrate supply pump (102) can be in the form of a mono pump capable of continuously and quantitatively transferring a high-concentration, high-viscosity liquid with a total solids (TS) concentration of 10% or less.

[0043] The substrate supply electric valve (103) is a valve member installed downstream of the substrate supply pump (102) to regulate the supply amount of substrate, and opens and closes the valve to regulate the supply amount of substrate.

[0044] The anaerobic digestion unit (200) is installed downstream of the substrate input unit (100) and is an anaerobic digestion unit that produces biogas by decomposing the pretreated substrate, into which organic waste resources are pretreated by substrate and input, by microorganisms, and is composed of an anaerobic digestion tank (201) and a stirrer (202).

[0045] The anaerobic digester (201) is an anaerobic digestion member having a plurality of air injection pipes spaced at equal intervals around the lower circumference so that fine air is evenly sprayed throughout the interior by stirring, and it is preferable that it be a cylindrical anaerobic digester.

[0046] The fine air introduced into the anaerobic digester is maintained evenly throughout the anaerobic digester through complete mixing and stirring, and plays an important role in oxidizing dissolved sulfides into sulfur by sulfur-oxidizing bacteria (SOB). The primary stirring method of the anaerobic digester includes a vertical shaft type stirrer in which an impeller-integrated stirrer is installed at the top of the anaerobic digester.

[0047] In addition, it is possible to install air injection pipes for injecting microbubbles into the anaerobic digester (201) at three locations at the bottom of the cylindrical anaerobic digester (201), that is, at 120-degree intervals at the bottom of the cylinder, so that microbubbles are evenly sprayed throughout the anaerobic digester (201) by stirring of the anaerobic digester (201).

[0048] The anaerobic digestion unit (200) is installed downstream of the intermediate storage tank (101), and the organic matter is decomposed through methane fermentation in the anaerobic digestion tank (201) in an oxygen-free state after the pre-treated single substrate or integrated substrate undergoes hydrolysis, acid fermentation, and acetic acid fermentation in the intermediate storage tank (101) which functions as an acid fermentation tank.

[0049] In particular, as a facility that produces biogas with methane as the main component as a byproduct, it is desirable to maintain the temperature of the anaerobic digester (201) at 36°C by producing hot water in a co-firing boiler, which is a biogas utilization facility, and heat exchanging it in a double-pipe heat exchanger.

[0050] In addition, the organic matter loading rate of the anaerobic digester (201) is 2.5 kg VS / m 3 ·d, and the air injection amount is automatically controlled based on 1 mL / min in conjunction with pH, ​​ORP (oxidation-reduction potential), biogas H2S concentration, and biogas O2 concentration measurements.

[0051] It goes without saying that the main measuring instruments and equipment installed in the anaerobic digester (201) can include three thermometers (upper, middle, and lower) and a pressure gauge for monitoring anaerobic digestion, a safety valve, and a flashback arrestor.

[0052] It is also possible to include a digester overflow induction device installed inside the anaerobic digester (201) to resolve the overflow phenomenon of the digester liquid overflowing into the biogas purification facility due to a rapid increase in pressure, and a scum removal device installed at the top of the anaerobic digester (201) to suppress the formation of scum.

[0053] The agitator (202) is a vertical shaft type stirring member in which an impeller is integrally installed on the upper part of the anaerobic digester (201), and it is preferable that the cylindrical anaerobic digester (201) and the vertical shaft type agitator are composed of a primary stirring device.

[0054] The air injection unit (300) is an air injection member installed on one side of the anaerobic digestion unit (200) to inject fine air into the anaerobic digestion unit (200) through an air nozzle, and is composed of an air blower (301), an air control valve (302), and an air supply nozzle (303).

[0055] The air blower (301) is an injection member for injecting external air, and through the air blower (301), external air passes through the air control valve (302) and generates microbubbles of 30 to 100 μm at the air supply nozzle (303) in the form of a jet nozzle, and supplies them to the anaerobic digester (201).

[0056] The air control valve (302) is an air control valve member installed downstream of the air blower (301) to control the amount of air injected, and it is preferable that the air control valve (302) controls the amount of air injected to 0.5 to 1.5 mL / min.

[0057] The air supply nozzle (303) is a nozzle member installed downstream of the air control valve (302) to generate and supply microbubbles to the injected air, and it is preferable that the air supply nozzle (303) supplies the air while maintaining the particle size of the microair at 30 to 100 μm.

[0058] In addition, it goes without saying that the air volume control of the air injection unit (300) can be automatically controlled by the automatic control system of the PLC (Programmable logic controller) of the central control room as shown in FIG. 3.

[0059] Of course, the amount of air injected by the air injection unit (300) can be automatically controlled in conjunction with the measured value of the digestion liquid measured by the digestion liquid circulation unit (500) and the concentration value of the gas analyzed by the gas analysis unit (400).

[0060] The supply of microair to the anaerobic digester is achieved by connecting an air supply nozzle (303) to the downstream piping of the substrate supply electric valve (103) to supply optimal microair with an air injection amount of 1 mL / min and a microair particle size of 30 to 100 μm to the anaerobic digester (201).

[0061] It is desirable to supply air to the anaerobic digester (201) at a rate of 1 mL / min, and to maintain the operating values ​​at this time within the range of pH 7 to 8, ORP (oxidation-reduction potential) -510 to -490 mV, biogas H2S concentration 300 to 400 ppm, and biogas O2 concentration 1 to 1.5%.

[0062] The operating condition for increasing the air injection amount to 1.5 mL / min is when the pH range measured in the digestion fluid circulation unit (500) is 8 or higher, the ORP range is -490 mV or higher, the H2S range measured in the gas analysis unit (400) is 400 ppm or higher, and the O2 range is 1% or lower.

[0063] In addition, the operating condition for reducing the air injection amount to 0.5 mL / min is when the pH range measured in the digestion fluid circulation unit (500) is 7 or less, the ORP range is -510 mV or less, the H2S range measured in the gas analysis unit (400) is 300 ppm or less, and the O2 range is 1.5% or more.

[0064] The gas analysis unit (400) is a gas analysis unit installed at the other side of the anaerobic digestion unit (200) to analyze the concentration of each substance contained in the biogas produced in the anaerobic digestion unit (200), and is composed of a biogas control valve (401) and a gas analyzer (402).

[0065] The biogas control valve (401) is a valve member that controls the transfer of biogas produced in the upper space of the anaerobic digester of the anaerobic digestion unit (200), and the biogas produced in the upper space above the water surface of the anaerobic digester (headspace) is transferred to a gas analyzer (402) through the biogas control valve to analyze H2S, O2, CH4, and CO2 in the biogas in real time.

[0066] The gas analyzer (402) is installed downstream of the biogas control valve (401) and is an analysis means for analyzing gases such as H2S, O2, CH4, and CO2 contained in the biogas transmitted through the biogas control valve (401). It is composed of a gas analyzer that analyzes various gases such as H2S, O2, CH4, and CO2 contained in the biogas.

[0067] The digestion fluid circulation unit (500) is installed on one side downstream of the anaerobic digestion unit (200) and is a digestion fluid circulation member that draws out digestion fluid from the lower part of the anaerobic digestion tank and introduces it into the upper part of the anaerobic digestion tank to circulate digestion fluid for up-and-down stirring in the anaerobic digestion tank of the anaerobic digestion unit (200), and is composed of a digestion fluid drawing electric valve (501), a digestion fluid circulation pump (502), a digestion fluid inlet electric valve (503), a pH meter (504), and an ORP meter (505).

[0068] The digestion liquid withdrawal electric valve (501) is a valve member connected to a digestion liquid withdrawal pipe installed at the bottom of the anaerobic digestion tank (201) of the anaerobic digestion unit (200) to control the amount of digestion liquid withdrawn, and controls the amount of digestion liquid withdrawn at the bottom of the anaerobic digestion tank (201).

[0069] The digestion liquid circulation pump (502) is a pump member installed downstream of the digestion liquid withdrawal electric valve (501) to draw digestion liquid withdrawn from the anaerobic digester (201) into the upper part of the anaerobic digester (201) and circulate the digestion liquid. It is preferable to have a digestion liquid circulation pump (502) with a circulation capacity of 3Q, which is three times the total capacity (Q).

[0070] The digestion liquid inlet electric valve (503) is a valve member installed at the top of the anaerobic digestion tank (201) of the anaerobic digestion unit (200) to control the amount of digestion liquid inlet, and controls the amount of digestion liquid inlet at the top of the anaerobic digestion tank (201).

[0071] The pH meter (504) is a pH measuring member installed upstream of the extinguishing liquid inlet motor valve (503) to measure the pH of the extinguishing liquid, and measures the pH of the extinguishing liquid circulated by the extinguishing liquid circulation pump (502).

[0072] The ORP measuring device (505) is an ORP measuring member installed upstream of the extinguishing liquid inlet motorized valve (503) to measure the ORP (Oxidation Reduction Potential) of the extinguishing liquid, and measures the ORP of the extinguishing liquid circulated by the extinguishing liquid circulation pump (502).

[0073] This digestion fluid circulation unit (500) transfers the digestion fluid within the anaerobic digestion tank (201) by operating the digestion fluid circulation pump (502) while the digestion fluid inlet electric valve (501), which is connected to the digestion fluid withdrawal pipe installed at the bottom of the anaerobic digestion tank (201), is open.

[0074] As the digestion liquid is circulated to the uppermost part of the anaerobic digestion tank (201) through the digestion liquid inlet electric valve (503) installed at the top of the anaerobic digestion tank (201), secondary stirring is carried out. Through the primary stirring by the vertical shaft type stirrer (202) installed in the anaerobic digestion unit (200) and the secondary stirring due to the circulation of the digestion liquid, complete mixing and stirring of the entire anaerobic digestion tank (201) is achieved, making it possible to maintain the upper and lower temperature difference of the anaerobic digestion tank (201) at 0.5℃ or less.

[0075] In addition, a pH meter (504) and an ORP meter (505) are installed in the intermediate piping of the digestion fluid circulation pump (502) and the digestion fluid inlet electric valve (503), so that the condition of the anaerobic digestion tank (201) can be monitored through real-time automatic measurement of the pH and ORP values ​​inside the anaerobic digestion tank (201), and it is possible to operate it in conjunction with the air injection amount.

[0076] The sulfur precipitate removal unit (600) is installed at the other side downstream of the anaerobic digestion unit (200) and maintains the concentration of hydrogen sulfide produced by oxidizing the hydrogen sulfide contained in the biogas inside the anaerobic digestion tank by fine air injected from the air injection unit (300) at 400 ppm or less, and is a sulfur precipitate removal member for removing sulfur precipitates, comprising a precipitate removal valve (601), a cyclone supply pump (602), a hydrocyclone (603), a separated liquid inlet electric valve (604), a buffer tank (605), and a digestion sludge storage tank (606).

[0077] The sediment removal valve (601) is a valve member installed at the bottom of the anaerobic digestion tank (201) of the anaerobic digestion unit (200) to control the discharge amount of sulfur sediment generated in the anaerobic digestion tank (201), thereby controlling the discharge amount of sulfur sediment generated in the anaerobic digestion tank (201).

[0078] The cyclone supply pump (602) is a pump member installed downstream of the sediment removal valve (601) to supply sulfur sediment discharged from the anaerobic digester (201) and to supply sulfur sediment discharged from the anaerobic digester (201).

[0079] The hydrocyclone (603) is a separating member installed downstream of the hydrocyclone supply pump (602) to separate sulfur precipitates supplied to the hydrocyclone (603) by centrifugal force and difference in specific gravity, and separates sulfur precipitates supplied to the hydrocyclone (603) by centrifugal force and difference in specific gravity.

[0080] The separated liquid inlet electric valve (604) is a valve member installed on one side downstream of the hydrocyclone (603) to introduce the liquid separated from the hydrocyclone (603) into the upper part of the anaerobic digester (201), thereby introducing the liquid containing organic matter and microorganisms separated from the hydrocyclone (603) into the upper part of the anaerobic digester (201) to maintain the hydrogen sulfide concentration at 400 ppm or less.

[0081] The buffer tank (605) is installed downstream of the hydrocyclone (603) and is a storage member for temporarily storing sulfur precipitates separated from the hydrocyclone (603), and temporarily stores sulfur precipitates separated from the hydrocyclone (603).

[0082] The digestion sludge storage tank (606) is installed downstream of the buffer tank (605) and is a storage member for removing sulfur precipitates transferred from the buffer tank (605), thereby removing sulfur precipitates transferred from the buffer tank (605).

[0083] Dissolved sulfides (HS) inside the anaerobic digester (201) according to the injection of micro-air into the anaerobic digester (201) - ) is precipitated as sulfur (S) by the action of sulfur-oxidizing bacteria (SOB).

[0084] In this sulfur precipitate removal section (600), the sulfur precipitate is moved to the lower part of the anaerobic digester (201) and transferred to the hydrocyclone (603) by operating the hydrocyclone supply pump (602) while the precipitate removal valve (601) is open through the lower sulfur precipitate pipe.

[0085] In the hydrocyclone (603), sulfur precipitates are transferred to the buffer tank (605) at the bottom of the hydrocyclone (603) by centrifugal force and difference in specific gravity, and then transferred to the digestion sludge storage tank (606) for separation, and the liquid containing organic matter and microorganisms is transferred to the anaerobic digestion tank (201) through the upper separation liquid inlet electric valve (604) of the anaerobic digestion tank (201).

[0086] As explained above, according to the present invention, by providing an air inlet for injecting optimal micro-air into the digestion liquid of an anaerobic digester, the hydrogen sulfide contained in the biogas is oxidized to sulfur by sulfur-oxidizing bacteria through air injection, thereby providing the effect of achieving primary desulfurization of the hydrogen sulfide concentration in the biogas to 400 ppm or less.

[0087] In addition, since it is not necessary to inject iron salt for primary desulfurization, hydrogen sulfide is oxidized to sulfur by sulfur-oxidizing bacteria through micro-air injection, allowing the hydrogen sulfide concentration in the biogas to be maintained at 400 ppm or less. This provides the effect of reducing the cost of iron salt chemicals for primary desulfurization and reducing the operating costs of the facility.

[0088] In addition, the substrate input section, anaerobic digestion section, air injection section, gas analysis section, digestion fluid circulation section, and sulfur precipitate removal section are all controlled by a PLC automatic control system, thereby enabling the implementation of an unmanned automatic control operation system that minimizes maintenance personnel and reduces facility operating costs.

[0089] The invention described above may be implemented in various other forms without departing from its technical concept or main features. Accordingly, the above embodiments are merely examples in all respects and should not be interpreted restrictively. Explanation of the symbols

[0090] 100: Substrate input section 200: Anaerobic digestion unit 300: Air inlet 400: Gas Analysis Department 500: Digestive fluid circulation unit 600: Sulfur precipitate removal unit 101: Intermediate storage tank 102: Substrate supply pump 103: Substrate supply electric valve 201: Anaerobic digester 301: Air blower 302: Air control valve 303: Air supply nozzle 401: Biogas control valve 402: Gas Analyzer 501: Electric valve for extinguishing fluid withdrawal 502: Digestive fluid circulation pump 503: Fire extinguishing fluid inlet electric valve 504: pH meter 505: ORP meter 601: Sediment removal valve 602: Hydrocyclone supply pump 603: Hydrocyclone 604: Separator inlet electric valve 605: Buffer tank 606: Digestive sludge retention tank

Claims

Claim 1 An anaerobic digestion device for processing organic waste resources, comprising: a substrate input unit (100) that removes foreign substances through pretreatment by crushing and sorting organic waste resources according to each substrate, and supplies the pretreated substrate by temporarily storing it in an intermediate storage tank; an anaerobic digestion unit (200) installed downstream of the substrate input unit (100), which produces biogas by decomposing the pretreated substrate, into which organic waste resources are pretreated according to substrate, by microorganisms; an air injection unit (300) installed on one side of the anaerobic digestion unit (200), which injects fine air into the anaerobic digestion unit (200) through an air nozzle; and a gas analysis unit (400) installed on the other side of the anaerobic digestion unit (200), which analyzes the concentration of each substance contained in the biogas produced in the anaerobic digestion unit (200). An anaerobic digestion device equipped with an air injection facility, characterized by comprising: a digestion liquid circulation unit (500) installed at one downstream side of the anaerobic digestion unit (200) and circulating the digestion liquid by drawing it from the lower part of the anaerobic digestion tank and introducing it into the upper part of the anaerobic digestion tank for up-and-down stirring in the anaerobic digestion tank of the anaerobic digestion unit (200); and a sulfur precipitate removal unit (600) installed at the other downstream side of the anaerobic digestion unit (200) and removing the sulfur precipitate generated by oxidizing hydrogen sulfide contained in the biogas inside the anaerobic digestion tank by fine air injected from the air injection unit (300). Claim 2 An anaerobic digestion device having an air injection facility, wherein the substrate input unit (100) comprises: an intermediate storage tank for storing each substrate of the pretreated organic waste resource; a substrate supply pump installed downstream of the intermediate storage tank for supplying the substrate stored in the intermediate storage tank to the anaerobic digestion unit (200); and a substrate supply electric valve installed downstream of the substrate supply pump for controlling the supply amount of the substrate. Claim 3 An anaerobic digestion device equipped with an air injection facility according to claim 2, wherein the intermediate storage tank performs the function of an acid fermentation tank by maintaining the internal temperature of the intermediate storage tank at a predetermined medium temperature through heating using hot water produced by utilizing biogas produced in the anaerobic digestion tank. Claim 4 An anaerobic digestion device having an air injection facility, wherein the anaerobic digestion unit (200) comprises: a cylindrical anaerobic digester having a plurality of air injection pipes spaced at equal intervals around the lower circumference so as to inject fine air evenly throughout the interior by stirring; and a vertical shaft type stirrer having an impeller integrally installed on the upper part of the anaerobic digester. Claim 5 An anaerobic digestion device having an air injection facility, wherein the air injection unit (300) comprises: an air blower for injecting external air; an air control valve installed downstream of the air blower for controlling the amount of air injected; and an air supply nozzle installed downstream of the air control valve for generating and supplying microbubbles to the injected air. Claim 6 In claim 5, the anaerobic digestion device equipped with an air injection facility, wherein the air control valve controls the amount of air injected to 0.5 to 1.5 mL / min. Claim 7 In claim 6, the anaerobic digestion device equipped with an air injection facility, wherein the air supply nozzle supplies air while maintaining the particle size of fine air at 30 to 100 μm. Claim 8 An anaerobic digestion device having an air injection facility, wherein the gas analysis unit (400) comprises: a biogas control valve for controlling the transfer of biogas produced in the upper space of the anaerobic digestion tank of the anaerobic digestion unit (200); and a gas analyzer installed downstream of the biogas control valve for analyzing gases of H2S, O2, CH4, and CO2 contained in the biogas transferred through the biogas control valve. Claim 9 In claim 1, the digestion liquid circulation unit (500) comprises: a digestion liquid withdrawal electric valve connected to a digestion liquid withdrawal pipe installed at the bottom of the anaerobic digestion tank of the anaerobic digestion unit (200) to control the amount of digestion liquid withdrawn; a digestion liquid circulation pump installed downstream of the digestion liquid withdrawal electric valve to supply digestion liquid withdrawn from the anaerobic digestion tank to the top of the anaerobic digestion tank to circulate the digestion liquid; a digestion liquid inlet electric valve installed at the top of the anaerobic digestion tank of the anaerobic digestion unit (200) to control the amount of digestion liquid inlet; a pH meter installed upstream of the digestion liquid inlet electric valve to measure the pH of the digestion liquid; and an ORP meter installed upstream of the digestion liquid inlet electric valve to measure the ORP (Oxidation Reduction Potential) of the digestion liquid; characterized in that the anaerobic digestion device equipped with an air injection facility. Claim 10 In claim 1, the sulfur precipitate removal unit (600) comprises: a precipitate removal valve installed at the bottom of the anaerobic digester of the anaerobic digestion unit (200) to control the discharge amount of sulfur precipitate generated in the anaerobic digester; a hydrocyclone supply pump installed downstream of the precipitate removal valve to pressurize the sulfur precipitate discharged from the anaerobic digester; a hydrocyclone installed downstream of the hydrocyclone supply pump to separate the supplied sulfur precipitate by centrifugal force and difference in specific gravity; a separated liquid inlet electric valve installed at one downstream of the hydrocyclone to introduce the filtrate separated from the hydrocyclone into the top of the anaerobic digester; and a buffer tank installed at the other downstream of the hydrocyclone to temporarily store the sulfur precipitate separated from the hydrocyclone. An anaerobic digestion device equipped with an air injection facility, characterized by including: a digestion sludge storage tank installed downstream of the buffer tank to remove sulfur precipitates transferred from the buffer tank. Claim 11 An anaerobic digestion device equipped with an air injection facility, wherein, in claim 1, the air volume control of the air injection unit (300) is automatically controlled by an automatic control system of a PLC (Programmable logic controller) in a central control room. Claim 12 An anaerobic digestion device having an air injection facility, wherein, in claim 1, the amount of air injected by the air injection unit (300) is automatically controlled in conjunction with the measured value of the digestion liquid measured by the digestion liquid circulation unit (500) and the concentration value of the gas analyzed by the gas analysis unit (400).

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