JP2012207901A - Storage facility and storage method for waste-derived solid fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage facility and a storage method for storing waste-derived solid fuel (for example, RDF or biomass waste-derived solid fuel) under physical conditions easily causing the fermentation thereof even in a hot-humid environment in which the fermentation may be further accelerated.SOLUTION: The waste-derived solid fuel is anaerobically fermented in a fermentation tank 52. A biogas that is evolved by the fermentation is made to flow into a primary storage tank 53 (biogas storage tank), then compressed and cooled, and stored in a secondary storage tank (biogas storage tank). The biogas stored in the secondary storage tank is sent to a boiler in a power generation part and used as fuel or n auxiliary fuel. A fermentation residue of the fuel is dehydrated and reused as a material of the fuel.

Description

  In the present invention, waste-derived solid fuel (for example, waste solidified fuel or biomass waste-derived solid fuel) having a property of being easily fermented or spoiled and generating malodor or flammable gas in the process is used for a long period of time. It relates to technology for storage.

  Municipal waste (hereinafter referred to as “MSW: Municipal Solid Waste”), generally called “garbage”, includes solid waste from ordinary households, private companies (office buildings, retail stores, wholesale trade, restaurants, etc.) ) And solid waste from public facilities (libraries, schools, hospitals, prisons, etc.). Conventionally, MSW is separately collected into combustible waste, recycled waste, metal waste, etc., of which combustible waste is incinerated. In recent years, from the viewpoint of environmental problems such as dioxins produced by combustion of garbage and effective utilization of garbage resources, MSW has started to use solid waste fuel (hereinafter referred to as “RDF; Refuse Derived Fuel ”) is being made. RDF is used as auxiliary fuel for power generation facilities, as hot water boiler fuel in the region, and as auxiliary fuel for heating sources such as heating furnaces used in various factories. RDF is generally classified into several types (seven types in ASTM) based on its shape and characteristics. Among them, those widely adopted are a fluffy RDF (hereinafter referred to as “Fluff RDF”) and a pelletized RDF (hereinafter referred to as “pellet RDF”).

FIG. 10A is a diagram showing a general manufacturing process of the pellet RDF. As shown in the figure, in the production of pellet RDF, the collected MSW is primarily crushed with a crusher, dried with a drying facility until the moisture content falls below a predetermined amount of water, non-combustible materials are sorted and removed, and secondary crushing is performed. The machine is further crushed to a size suitable for the molding process. During these steps, metals and other foreign matters that are not suitable as fuel are mixed and removed in the MSW. The MSW, which has been reduced to a size suitable for molding in this way, is a fermentation inhibitor mainly composed of an alkali compound (such as slaked lime) in order to prevent fermentation by microorganisms, heat generation, and methane gas generation accompanying fermentation during RDF storage. And compressed into pellets with a molding machine for higher specific gravity. The pellet RDF produced by the above process generally has a hard cylindrical shape with a diameter of 10 to 50 mm and a length of 10 to 100 mm, a bulk specific gravity of about 0.6 ton / m ³ , and a low calorific value of 4,500 kcal / It is about kg.

FIG. 10B is a diagram showing a general manufacturing process of the fluff RDF. As shown in the figure, in manufacturing the fluff RDF, the collected MSW is primarily crushed by a crusher, incombustibles and foreign substances are sorted and removed, and then secondarily crushed by a crusher until it reaches a specified size. . It should be noted that metals and other foreign matters that are not suitable as fuel are selected and removed during these steps. Moreover, when the moisture content of the collected MSW is excessive, a drying process is added upstream or downstream of the secondary crushing process. The fluff RDF produced by the above process generally has a planar shape of 50 to 150 mm square, and the bulk specific gravity varies depending on the amount of water contained, but is approximately 0.1 to 0.2 ton / m ^3. Is about 3,500 kcal / kg. In the manufacturing process of the fluff RDF, the drying process and the molding process are omitted from the manufacturing process of the pellet RDF. For this reason, the production of the fluff RDF does not require a drying furnace and its fuel, a fermentation inhibitor, and a molding machine and its power. As a result, the manufacturing cost of the fluff RDF is lower than that of the pellet RDF. However, since the fluff RDF is bulky, it is not suitable for long-distance transportation, and because it excludes moisture adjustment and anti-fermentation agent addition to prevent RDF fermentation during storage, it has a safety point of view during storage. It is an industry recommendation that storage for long periods (eg, over a week) should be avoided.

  FIG. 11 is a conceptual diagram of an overall RDF-fired power generation system from conventional MSW collection to RDF production and RDF-fired power generation. As shown in the figure, the collected MSW is carried into the RDF manufacturing facility 101, where RDF is manufactured from the MSW. The manufactured RDF is carried into the receiving facility 102 and is thrown into the boiler 61 of the power generation facility 103. In the power generation facility 103, RDF is burned as fuel or auxiliary fuel in the boiler 61, and power is generated by rotating the turbine of the steam turbine power generation facility 62 with high-temperature and high-pressure steam that recovers the combustion heat.

  In Europe, in addition to the relatively low average temperature and dry climate, strict separation of trash (garbage waste, food waste, etc.) and general combustible waste is strictly conducted. From the background, the main components of MSW are general combustible waste such as cloth, plastics and wood. Therefore, the moisture contained in the MSW used as the raw material for RDF is less than that of MSW in other regions where moss is mixed. Furthermore, the RDF manufacturing facility 101, the receiving facility 102, and the power generation facility 103 of the RDF-fired power generation system are adjacent or close to each other, and the manufactured RDF is immediately stored without being stored for a long period of time. Burned in. Therefore, long-distance transportation and long-term storage of RDF are not necessary. For these reasons, fluff RDF is adopted in these areas.

  In Europe as well, there may occur a situation where the fluff RDF must be stored in the receiving facility 102 for a long period of time for maintenance and inspection of the power generation facility 103. Since the fluff RDF has a small bulk specific gravity, a vast storage space is required to store it as it is. Therefore, by packing the fluff RDF while being compressed with a vinyl sheet or the like, the fluff RDF is stored in a state where the bulk specific gravity is slightly increased and is easily moved. However, in the packing vinyl sheet, contact between the RDF and the outside air is unavoidable, and organic substances in the RDF may be aerobically fermented inside the packing due to moisture contained in the RDF. Methane gas and ammonia produced by RDF fermentation cause fires and odors. By storing RDF packed in a large open site on a plane, it is possible to prevent methane gas and ammonia gas from staying, but the odor problem around the storage site is unavoidable.

  In Japan, separate collection of moss and general combustible waste is not performed in most areas. Therefore, the amount of moisture contained in the MSW used as the raw material for RDF is greater than that of the European MSW. In addition, the basic policy for MSF RDF conversion in Japan is that the MSWs of local governments scattered over a wide area will be converted to RDF and consolidated into one place, so that wastes can be processed at once and effective use of energy by heat recovery is planned. Is. For this reason, many RDF manufacturing facilities 101 and receiving facilities 102 are separated regardless of a short distance or a long distance, and transport of RDF is necessary. Further, a set of receiving facilities 102 and power generation facilities 103 are provided for a plurality of RDF manufacturing facilities 101, and RDF transported from the plurality of RDF manufacturing facilities 101 is stored for a long time by one receiving facility 102. A need arises. For these reasons, pellet RDF suitable for transportation and long-term storage is the mainstream in Japan.

  Pellet RDF is more suitable for long-term storage than fluff RDF, but is a fuel that easily ferments, and therefore requires a rigorous storage method to prevent RDF fermentation and ignition. Therefore, conventionally, techniques for storing the pellet RDF for a long period of time have been proposed (for example, Patent Documents 1, 2, and 3). In patent document 1, the solid fuel storage tank for storing the pellet RDF for a long term is shown. The solid fuel storage tank is configured to circulate air in the storage tank and also circulate solid fuel in order to suppress heat storage in the storage tank and prevent spontaneous ignition. Furthermore, this storage tank is provided with a carbon monoxide detector, a temperature detector, and a watering nozzle so as to detect spontaneous ignition and to extinguish immediately when it is ignited.

  Patent Document 2 shows a solid fuel cooling tower configured to fill a cooling chamber formed in a vertically long hopper shape with pellets RDF and to flow cooling gas so as to penetrate the RDF packed bed. Furthermore, in Patent Document 3, gas is sucked and collected from the gap of the RDF stored in the open pit, the generated gas is measured for its component and temperature, heat generation is detected, and nitrogen gas is injected into the heated portion. A solid waste fuel storage device configured as described above is shown.

JP 2003-206010 A JP 2002-69469 A JP 2007-16174 A

  In recent years, MSW treatment has become a major environmental problem in Far East Asia (Korea, China, etc. excluding Japan) and Southeast Asia. Some of these regions have already started plans for effective use of energy by converting MSW to RDF. These regions are common in that the collected MSW contains a large amount of moss that is not suitable for fluff RDF due to incomplete separation and collection, food ingredients and dietary habits, and that the weather conditions are high temperature and high humidity. To do. Even under such conditions, from the viewpoint of RDF production equipment and RDF production cost, there is a desire to establish a system that produces fluff RDF from recovered MSW and generates power using the RDF as fuel. However, the fluff RDF produced from MSW with a high water content and a large amount of easily fermented potatoes can be safely used in a high-temperature and high-humidity environment where fermentation is easily promoted without adding an alkaline compound that inhibits fermentation. No long-term storage method has been established. The above-mentioned method for storing and storing fluff RDF in Europe is established under careful monitoring in addition to the condition that the water content of fluff RDF is small and the climate is relatively dry. It has not been proved to be established under conditions where the amount is high and the climate is hot and humid. The RDF storage methods proposed in Patent Documents 1 to 3 are all directed to pellet RDF.

  A problem related to long-term storage similar to the fluff RDF is also present in biomass-based waste-derived solid fuel produced from biomass-based waste. Here, the “biomass waste-derived solid fuel” means a biomass waste made into a form suitable for the requirements of the combustion facility by removing foreign matter, crushing, cutting, or the like. Biomass waste also contains a large amount of water inside and contains many organic substances suitable for fermentation. The country that emits large amounts of biomass waste is the Southeast Asia region under high temperature and high humidity weather conditions. FIG.10 (c) is a figure which shows the general manufacturing process of biomass-type waste origin solid fuel. As shown in the figure, in the production of solid fuel derived from biomass waste, the collected biomass waste is sorted and removed from large incombustibles, primarily shredded by a crusher, and small incombustibles are sorted and removed. Secondary crushed to dimensions suitable for combustion. Among the solid fuels derived from biomass waste, oil palm biomass (oil palm trunk, leaves, oil palm empty bunch etc.), sugar cane biomass (sugar cane pomace), coconut biomass (coconut pomace), jatropha type Those produced from biomass-based waste such as biomass (jatropha leaves, empty bunches, etc.) are particularly easy to ferment and have a high fermentation rate because they contain a large amount of organic matter and moisture inside. Therefore, the problem of long-term storage similar to Fluff RDF also arises in power generation facilities using such biomass-derived solid fuel as fuel.

  The present invention has been made in order to solve the above-described problems, and waste-derived solid fuel (for example, RDF or biomass-based waste-derived solid fuel) that is physically fermentable is used. It is an object of the present invention to propose a storage facility and a storage method for enabling storage in a high-temperature and humid environment where fermentation is more easily promoted.

  The waste-derived solid fuel storage facility according to the present invention is a storage facility for storing a fermentable waste-derived solid fuel before combustion in the combustion facility, and the waste-derived solid fuel is anaerobically fermented. A fermenter to be stored, a biogas storage tank for storing biogas generated by anaerobic fermentation of the waste-derived solid fuel, a first flow path for sending the biogas from the fermenter to the biogas storage tank, and A supply path for supplying the biogas from a biogas storage tank to the fuel facility is provided.

  The method for storing waste-derived solid fuel according to the present invention is a method for storing waste-derived solid fuel that is easily fermented before combustion in a combustion facility, wherein the waste-derived solid fuel is stored in an anaerobic fermenter. And anaerobic fermentation step and a step of storing biogas produced by anaerobic fermentation of the waste-derived solid fuel in a biogas storage tank.

  According to the waste-derived solid fuel storage facility and storage method described above, waste-derived solid fuel that is easily fermented is stored in biogas and its fermentation residue in different forms. As the waste-derived solid fuel ferments, most of the organic matter in the waste-derived solid fuel changes its form as biogas, so the waste-derived solid fuel that has been put into the fermenter is solid as much as the fermented organic matter. The volume is reduced. That is, since the fermentation residue is reduced in volume compared to the original waste-derived solid fuel, the space for storing solids can be reduced. Furthermore, since most of the organic matter contained in the solid fuel derived from waste is converted into biogas by anaerobic fermentation in the fermenter, the residual amount of organic matter contained in the fermentation residue is reduced. Storage is easy compared to the waste-derived solid fuel itself. In addition, since biogas is a gas and does not change with time, it can be stored easily compared to the state of waste-derived solid fuel as it is. Further, the fuel storage facility and the fuel storage method can store solid fuel derived from waste that is easily fermented in a dry environment or a high temperature and humidity environment, and the solid fuel derived from waste regardless of the storage environment. Can be stored stably.

  In the waste-derived solid fuel storage facility, the biogas storage tank is connected by a primary storage tank through which the biogas is sent from the fermentation tank through the first flow path, and the primary storage tank and the second flow path. A secondary storage tank, the compressor compressing and sending the biogas from the primary storage tank to the secondary storage tank in the second flow path, and the compressor compressing the biogas in the second flow path And a cooler for cooling the biogas produced. Similarly, in the method for storing waste-derived solid fuel, the step of storing the biogas in the biogas storage tank includes the step of storing the biogas sent from the fermentation tank in a primary storage tank, and the primary storage tank. The step of reducing the volume of the biogas by compressing it from the storage tank to the secondary storage tank, sending the compressed biogas, the step of cooling the compressed biogas, and storing the compressed biogas in the secondary storage tank Preferably including the step of:

  Since the biogas is a gas, it can be reduced in volume by being compressed, unlike the solid fuel derived from waste. Therefore, according to the storage facility and storage method for waste-derived solid fuel, since the biogas is stored in a tank-shaped storage facility in a compressed state, the planar area required to store the biogas Can be reduced. Furthermore, by adjusting the pressure of the biogas, the size of the space necessary for storing the same amount of biogas can be changed.

  In the waste-derived solid fuel storage facility, moisture removal is performed to remove moisture that is a fermented residue of the waste-derived solid fuel discharged from the fermenter and moisture contained in the fermentation residue of the waste-derived solid fuel. Means may be provided. Similarly, in the method for storing waste-derived solid fuel, moisture that is a fermented residue of the waste-derived solid fuel discharged from the fermenter and moisture contained in the fermentation residue of the waste-derived solid fuel are removed. It is preferable to include the step to do.

  According to the above-mentioned waste-derived solid fuel storage facility and storage method, the fermentation residue is further reduced in volume by removing moisture, and therefore the space for storing the fermentation residue can be further reduced. Moreover, by removing moisture from the fermentation residue, the fermentation residue from which moisture has been removed can be reused as a raw material for waste-derived solid fuel.

  In the waste-derived solid fuel storage facility, an oxygen concentration detector for detecting the oxygen concentration of the effluent gas flowing out from the fermenter to the first flow path, and a methane concentration detector for detecting the methane concentration of the effluent gas. And, based on the detected oxygen concentration and methane concentration, the valve is opened when the mixing ratio of oxygen and methane gas in the effluent gas is outside the combustion range, and the first flow path and the biogas storage tank are communicated with each other. It is good to provide the 1st control valve to make it go. Similarly, in the method for storing waste-derived solid fuel, in the step of storing the biogas in a biogas storage tank, the oxygen concentration and methane concentration of the effluent gas flowing out from the fermentor containing the biogas are detected. Based on the detection result, it is preferable to store in the biogas storage tank the outflow gas whose oxygen / methane gas mixing ratio is outside the combustion range.

  According to the fuel storage facility or the fuel storage method, only the outflow gas from the fermenter that is suitable for compression is sent to the biogas storage tank as biogas, and the safety and biogas during biogas storage Safety during use can be improved.

  In the waste-derived solid fuel storage facility, based on the atmospheric diffusion path that communicates the inside of the fermenter with the atmosphere, the oxygen concentration detected by the oxygen concentration detector, and the methane concentration detected by the methane concentration detector In addition, it is preferable to provide an atmospheric diffusion valve that is opened when the mixing ratio of oxygen and methane gas in the effluent gas is within a combustion range and diffuses the effluent gas to the atmosphere through the atmospheric diffusion path. Alternatively, in the waste-derived solid fuel storage facility, a preliminary storage tank connected to the fermentation tank via a third flow path, an oxygen concentration detected by the oxygen concentration detector, and a methane concentration detector A second control valve that opens when the mixing ratio of oxygen and methane gas in the effluent gas is within a combustion range based on the detected methane concentration, and communicates the third flow path with the reserve storage tank; It is good to have.

  Similarly, in the method for storing waste-derived solid fuel, in the step of storing the biogas in a biogas storage tank, the oxygen and methane gas of the effluent gas based on the oxygen concentration and methane concentration of the effluent gas. It is preferable that the mixture ratio in the combustion range is released to the atmosphere. Alternatively, in the method of storing waste-derived solid fuel, in the step of storing the biogas in a biogas storage tank, based on the oxygen concentration and methane concentration of the effluent gas, the oxygen and methane gas of the effluent gas It is preferable to store the mixture in the combustion range in a preliminary storage tank different from the biogas storage tank.

  According to the fuel storage facility or the fuel storage method, out of the effluent gas from the fermenter, if there is a fire source, the one that may burn without receiving the supply of combustion oxygen from the outside is released to the atmosphere or Since it is accommodated in the pre-storage tank which is not compressed, the safety at the time of biogas storage and the safety at the time of biogas utilization can be improved.

  In the waste-derived solid fuel storage facility, the supply path has a path for supplying the biogas stored in the biogas storage tank to the combustion facility as a starting fuel for the combustion facility. It is good. Similarly, the waste-derived solid fuel storage method may further include a step of supplying the biogas stored in the biogas storage tank to the combustion facility as a starting fuel for the combustion facility. .

  According to the fuel storage facility or the fuel storage method, biogas can be effectively used as fuel or auxiliary fuel for combustion facilities.

  In the waste-derived solid fuel storage facility, the supply path uses the biogas stored in the biogas storage tank as at least one of a primary combustion air supply path and a secondary combustion air supply path of the combustion facility. It is preferable to have a route for supplying to one side. Here, the supply path is configured to supply the biogas so that the biogas supplied to the combustion facility is mixed with the primary combustion air or the secondary combustion air of the combustion facility at a mixing ratio outside the combustion range. It is preferable to provide an adjusting means for adjusting.

  Similarly, in the waste-derived solid fuel storage method, the biogas stored in the biogas storage tank is transferred to at least one of the primary combustion air supply path and the secondary combustion air supply path of the combustion facility. It may further include the step of providing. Here, it is preferable to adjust the supply amount of the biogas so that the biogas supplied to the combustion facility is mixed with the primary combustion air or the secondary combustion air of the combustion facility at a mixing ratio outside the combustion range. .

  According to the fuel storage facility or the fuel storage method, biogas can be effectively used as fuel.

  The waste-derived solid fuel may be a solid waste fuel produced from general waste. Alternatively, the waste-derived solid fuel may be a biomass waste-derived solid fuel produced from biomass-based waste.

  According to the present invention, the waste-derived solid fuel that is easy to ferment is changed into a biogas that can be reduced in volume by compression and a fermentation residue after the organic matter in the waste-derived solid fuel is gasified by fermentation. Will be stored. Biogas does not ferment further, and the amount of organic matter contained in the fermentation residue is greatly reduced compared to the state of the solid waste-derived solid fuel, so that the fermentation can be accelerated more quickly in a humid environment. But it can be stored. In this way, storage management becomes easier as compared with the case of storing the waste-derived solid fuel itself. Further, since the waste-derived solid fuel is fermented, the volume of the solid is reduced and the space required for storing the solid can be reduced.

1 is an overall conceptual diagram of an RDF-fired power generation system including a fuel storage facility according to an embodiment of the present invention. It is a conceptual diagram which shows the structure of a fuel manufacturing part. It is a conceptual diagram which shows the structure upstream from the primary storage tank of a fuel long-term storage part. It is a conceptual diagram which shows the structure of the downstream from the primary storage tank of a fuel long-term storage part. It is a block diagram which shows the control structure of a fuel long-term storage part. It is a figure explaining the combustion range of methane. It is a flowchart which shows the flow of control of the RDF injection | throwing-in initial stage of a fermenter control part. It is a conceptual diagram which shows the structure of the upstream from the primary storage tank of the fuel long-term storage part which concerns on a modification. It is a conceptual diagram which shows the structure of the downstream from the primary storage tank of the fuel long-term storage part which concerns on a modification. (A) is a figure which shows the general manufacturing process of pellet RDF, (b) is a figure which shows the general manufacturing process of fluff RDF, (c) is a general figure of biomass-type waste origin solid fuel It is a figure which shows a manufacturing process. It is a general conceptual diagram of an RDF-fired power generation system from conventional MSW collection to RDF production and RDF-fired power generation.

  The waste-derived solid fuel storage facility according to the present invention (hereinafter also simply referred to as “fuel storage facility”) is a waste-derived solid fuel that contains a large amount of organic matter produced from waste and is easy to ferment for a long time (for example, It is equipment for storage (from several weeks to several months). Hereinafter, an RDF-fired power generation system using a fuel storage facility according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall conceptual diagram of an RDF-fired power generation system including a fuel storage facility according to an embodiment of the present invention, and arrows in the figure indicate the flow of materials. Further, in the same figure, a description regarding a fine auxiliary device not directly related to the invention is omitted.

  As shown in FIG. 1, the RDF-fired power generation system 1 mainly includes a fuel production unit 3, a temporary fuel storage unit 4, a long-term fuel storage unit 5, and a power generation unit 6. This RDF-fired power generation system 1 is a waste solidified fuel (hereinafter referred to as “RDF”) referred to as “MSF (Municipal Solid Waste”), which is waste discharged from ordinary households. Is a system that generates electricity using heat generated by the combustion of RDF. In the RDF-fired power generation system 1, the temporary fuel storage unit 4 and the long-term fuel storage unit 5 are adjacent to the power generation unit 6. However, the fuel production unit 3 may be adjacent to or separated from the power generation unit 6. In addition, a plurality of fuel production units 3 may exist for one power generation unit 6. Next, each part constituting the RDF-fired power generation system 1 will be described in detail.

(Fuel Manufacturing Department 3)
The fuel manufacturing unit 3 includes equipment for manufacturing a fluff RDF (fluff-shaped RDF) from the MSW. FIG. 2 is a conceptual diagram of the fuel production unit 3, and the arrows in the figure indicate the flow of substances. As shown in the figure, the fuel production unit 3 mainly includes an MSW storage pit 31, a primary crusher 32, a sorter 33, and a secondary crusher 34. The MSW storage pit 31 is for temporarily storing the collected MSW. The MSW storage pit 31 has, for example, a capacity that can accommodate up to 5 days of MSW. The primary crusher 32 tears a plastic bag or a cloth-like substance in the MSW or crushes a large solid matter so that the sorting machine 33 can remove foreign matters and incombustibles. The sorter 33 is for sorting and removing incombustibles from the MSW. This incombustible material includes stones, concrete fragments, metals, and the like. The secondary crusher 34 is for further finely crushing the MSW from which incombustible materials and the like have been sorted and removed to a required size.

  In the fuel production unit 3 having the above-described configuration, the collected MSW is first carried into the MSW storage pit 31 and temporarily stored. Then, the MSW stored in the MSW storage pit 31 is sequentially put into the primary crusher 32 and roughly crushed. The MSW that has been primarily crushed is subjected to sorting and removal of non-combustible material by the sorter 33 and then fed into the secondary crusher 34. The MSW made of combustible material charged into the secondary crusher 34 is further finely crushed by the secondary crusher 34 to become a fluff RDF (fluff-like RDF). The RDF thus manufactured has a flat plate shape of 50 to 150 mm square.

(Temporary fuel storage 4)
The temporary fuel storage unit 4 includes a fuel storage 36 for storing RDF. The RDF manufactured by the fuel manufacturing unit 3 is carried into the fuel storage 36 and temporarily stored therein. The period during which the RDF is stored in the fuel storage 36 is generally several days or at most about seven days in consideration of the volume of the fuel storage 36 and the safety aspect during storage. The RDF stored in the fuel storage 36 is sent to the power generation unit 6 when the power generation unit 6 is in operation. Further, when the power generation unit 6 is not in operation or when the total heat amount of the manufactured RDF exceeds the heat amount of the optimum operation base of the power generation unit 6, it is stored for a period that can be stored in the fuel storage 36. When there is surplus RDF that must be stored, the RDF stored in the fuel storage 36 corresponding to the surplus RDF is sent to the long-term fuel storage unit 5.

(Power generation part 6)
The power generation unit 6 is a power generation facility group for generating power by burning RDF. The power generation unit 6 mainly includes a boiler 61 that is an RDF combustion facility, a steam turbine power generation facility 62 to which high-pressure and high-temperature steam is fed from the boiler 61, and harmful substances contained in exhaust gas from the boiler 61. And an exhaust gas treatment facility 63 to be removed. In addition, although the boiler 61 of the electric power generation part 6 which concerns on this Embodiment is a RDF fired boiler, it may replace with this and may be a coal fired boiler. In this case, RDF is used as an auxiliary fuel for a coal-fired boiler.

  RDF stored in the fuel storage 36 of the temporary fuel storage unit 4 is introduced into the combustion chamber 61 a of the boiler 61. The heat generated by the combustion of RDF in the combustion chamber 61a of the boiler 61 is recovered by heat recovery water flowing through the heat recovery device 61b and steam overheating. The heat recovery unit 61b and the steam turbine power generation facility 62 are connected to each other through a steam discharge path 68 configured by piping or the like. The steam that has recovered the combustion heat of the RDF and has become high temperature and high pressure is sent to the steam turbine power generation facility 62 through the steam discharge path 68. In the steam turbine power generation facility 62, power is generated by a generator that rotates the turbine with steam and converts this rotational force into electric power.

  A primary combustion air supply path 65, a secondary combustion air supply path 66, an activation fuel supply path 67, and an exhaust path 69 are connected to the combustion chamber 61 a of the boiler 61. The primary combustion air supply path 65 is configured by piping, a blower, and the like that connect the combustion chamber 61 a of the boiler 61 and the primary combustion air source (external), and the combustion of the boiler 61 from the primary combustion air source through the primary combustion air supply path 65. Primary combustion air for combustion is supplied to the chamber 61a. The secondary combustion air supply path 66 is composed of a pipe connecting the combustion chamber of the boiler 61 and the secondary combustion air source (external), a blower, and the like, and to the combustion chamber 61a of the boiler 61 through the secondary combustion air supply path 66. Secondary combustion air for combustion is supplied. The startup fuel supply path 67 is configured by piping or the like that connects the combustion chamber of the boiler 61 and the startup fuel source. When the boiler 61 is started up, the startup of the boiler to the combustion chamber 61a of the boiler 61 through the startup fuel supply path 67 is performed. Fuel is supplied. The exhaust passage 69 is configured by piping or the like that connects the combustion chamber 61 a of the boiler 61 and the exhaust gas treatment facility 63. Exhaust gas generated in the combustion chamber 61 a of the boiler 61 is sent to the exhaust gas processing facility 63 through the exhaust passage 69. In the exhaust gas treatment facility 63, harmful substances contained in the exhaust gas of the boiler 61 are removed and then discharged to the outside through the chimney.

(Fuel long-term storage 5)
Next, the fuel long-term storage unit 5 will be described in detail. The long-term fuel storage unit 5 is a facility group for storing RDF beyond the storage period in the temporary fuel storage unit 4. In the long-term fuel storage unit 5, RDF is stored in a reduced and reduced state of biogas and fermentation residue. FIG. 3 is a conceptual diagram showing a configuration upstream of the primary storage tank of the fuel long-term storage unit, and FIG. 4 is a conceptual diagram showing a configuration downstream of the primary storage tank of the fuel long-term storage unit. 3 and 4, the substance flow is indicated by arrows. FIG. 5 is a block diagram showing a control configuration of the long-term fuel storage unit 5. As shown in FIGS. 3 and 4, the fuel long-term storage unit 5 mainly includes a charging device 51, a fermenter 52, a primary storage tank 53, a secondary storage tank 54, a residue discharge device 55, and a compressor 57. And a biogas supply facility 59.

  The charging device 51 is for charging RDF from the fuel storage 36 of the temporary fuel storage unit 4 to the fermenter 52. The input device 51 includes a fuel input tank 11 provided between the fuel storage 36 and the input port 18 of the fermenter 52. Between the fuel storage 36 and the fuel charging tank 11 and between the fuel charging tank 11 and the fermenter 52 are connected via various conveyors or pipes. Between the fuel storage 36 and the fuel charging tank 11, a first charging valve 12 that partitions these spaces and restricts the movement of the RDF from the fuel storage 36 to the fuel charging tank 11 is provided. Between the fuel charging tank 11 and the fermenter 52, there is provided a second charging valve 13 that partitions these spaces and restricts the movement of the RDF from the fuel charging tank 11 to the fermentation tank 52. In addition, an inert gas supply path 15 for supplying an inert gas from an inert gas source 14 is connected to the fuel supply tank 11, and an assist gas supply valve 16 a is provided in the inert gas supply path 15. It has been. Further, the fuel input tank 11 is provided with an inert gas discharge path 11a for discharging an inert gas as an assist gas from the fuel input tank 11, and the assist gas is supplied to the inert gas discharge path 11a. A valve 16a is provided. As shown in FIG. 5, the opening / closing operations of the first closing valve 12, the second closing valve 13, the assist gas supply valve 16 a and the assist gas discharge valve 16 b are controlled by the closing device controller 17.

  Next, the operation of the charging device 51 configured as described above will be described. In response to an input instruction including an RDF input amount input via an operation panel (not shown), the input device control unit 17 opens the first input valve 12 for a time corresponding to the RDF input amount. Then, the RDF moves from the fuel storage 36 to the fuel input tank 11. Subsequently, the charging device controller 17 opens the second charging valve 13. Thereby, the RDF in the fuel charging tank 11 falls to the fermenter 52 by its own weight. Here, the input device control unit 17 opens the assist gas supply valve 16 a and the assist gas discharge valve 16 b, and converts the RDF into the fermenter 52 by the inert gas supplied to the fuel input tank 11 through the inert gas supply path 15. It can also be controlled to force the extrusion. When the charging of the RDF into the fermenter 52 is completed, the charging device controller 17 closes the second charging valve 13, the assist gas supply valve 16a, and the assist gas discharge valve 16b. By the operation of the charging device 51 described above, the instructed RDF amount of RDF is charged into the fermentation tank 52, and the fuel charging tank 11 after the RDF charging is almost sealed.

  The fermenter 52 is an anaerobic fermenter that anaerobically ferments RDF in an anaerobic atmosphere for about 15 to 20 days. The fermenter 52 is provided with a moving device 20 for moving the RDF from the charging side 52a with the charging port 18 to the discharging side 52b with the discharging port 19. The moving device 20 may be in any form as long as it can be moved from the input side 52a to the discharge side 52b, but FIG. 3 illustrates the moving device 20 provided with rotating blades. The moving device 20 includes a plurality of rotor blades arranged in the RDF transport direction from the input side 52a to the discharge side 52b, and a rotor blade drive unit that rotationally drives the rotor blades. When the rotor blades are rotated by driving the rotor blade drive unit, the RDF dropped to the charging side 52a of the fermenter 52 is sequentially sent out to the discharge side 52b by the rotating rotor blades. The moving speed and moving amount of RDF can be controlled by adjusting the rotating speed and rotating frequency of the rotor blades.

  In addition, a biogas discharge port 21 is opened above the discharge side 52 b of the fermenter 52. The biogas discharge port 21 is connected to the primary storage tank 53 via the biogas first flow path 22. In the biogas first flow path 22, a pressure detector 71 that detects the pressure of the biogas that passes through the biogas first flow path 22, an oxygen concentration detector 78 that also detects the oxygen concentration, and a methane concentration are also detected. A methane concentration detector 79 is provided. Furthermore, a first inflow control valve 23 for opening and closing the biogas first flow path 22 is provided downstream of the detectors 71, 78, and 79 in the biogas first flow path 22. By opening and closing the first inflow control valve 23, communication and blocking between the fermenter 52 and the primary storage tank 53 are switched.

  Atmospheric radiation that allows the inside of the fermenter 52 to communicate with the outside (atmosphere) on the downstream side of the detectors 71, 78, 79 of the biogas first flow path 22 and upstream of the first inflow control valve 23. The path 24 branches from the biogas first flow path 22. An air diffusion valve 25 is provided in the air diffusion path 24. By opening / closing the atmospheric diffusion valve 25 and opening / closing the first inflow control valve 23, communication between the inside and outside of the fermenter 52 through the atmospheric diffusion path 24 and switching are switched.

  An inert gas supply port 26 is provided on the charging side 52 a of the fermenter 52. The inert gas supply port 26 is connected to the inert gas source 14 via the inert gas supply path 15. An inert gas source valve 27 is provided in the inert gas supply path 15. This inert gas main valve 27 is opened together with the atmospheric diffusion valve 25 when the air in the fermenter 52 is replaced with an inert gas. As a result, the inert gas is supplied into the fermenter 52 through the inert gas supply port 26, and the air in the fermenter 52 is discharged through the atmospheric air diffusion path 24, so that the air in the fermenter 52 is inactivated. Replaced with active gas. Furthermore, a water supply device 29 for supplying water to the fermenter 52 is provided on the input side 52a of the fermenter 52 so that the water content of the RDF input to the fermenter 52 is suitable for anaerobic fermentation. Is provided. The water supply device 29 includes a water supply pipe 29b that connects the water source 29a and the fermentation tank 52, and a water supply adjustment valve 29c that is provided in the water supply pipe 29b and adjusts the amount of water supplied to the fermentation tank 52. Yes.

  The fermenter 52 and the ambient air release valve 25, the first inflow control valve 23, the inert gas source valve 27, and the movement device 20 provided in the vicinity thereof are operated by the fermenter controller 28 with detectors 71, 78, and 79. It is controlled based on the detection signal. In addition, the operation of the water supply adjustment valve 29c of the water supply device 29 is such that the RDF in the fermenter 52 is anaerobic based on the RDF-containing water content measured in the RDF manufacturing process and the RDF input amount from the fuel input tank 11. It is controlled by the fermenter controller 28 so that the water content is suitable for fermentative fermentation.

  In the fermenter 52 configured as described above, the RDF that has been input into the fermenter 52 through the input port 18 by the input device 51 falls to the input side 52 a of the moving device 20. The RDF in the fermenter 52 is sequentially transferred to the downstream by the moving device 20 and moves from the input side 52a to the discharge side 52b over a predetermined fermentation period (about 15 to 20 days in this case). During this movement, anaerobic fermentation of organic matter contained in RDF proceeds, biogas is generated, and RDF is reduced in volume and weight. The composition of biogas produced by RDF fermentation is approximately 60% methane gas and 40% carbon dioxide. However, the generation amount and composition of biogas vary depending on the amount and type of organic substances contained in RDF, and the generation amount also varies depending on the degree of fermentation.

  When the RDF moves to the discharge side 52b of the fermenter 52 while fermenting, most of the organic matter in the RDF is decomposed into biogas, and the rest is fermentation residue. This RDF fermentation residue is composed of an unfermented volatile component in the solid content of RDF and a non-fermented component of RDF, and includes organic residues, woody residues, and vinyl residues. In addition, when the fermentation period in the fermenter 52 is short, unfermented or RDF in the middle of fermentation may be mixed in the fermentation residue, and these are collectively referred to as the fermentation residue. The fermentation residue is sent out to the discharge port 19 by the moving device 20 and is discharged out of the fermentation tank 52 from the discharge port 19. The fermentation residue is greatly reduced in volume and reduced compared to the original RDF.

  The residue discharge device 55 is for recovering the fermentation residue in the fermenter 52 and dehydrating and removing the digestive juice and the digestive juice contained in the fermentation residue. The residue discharge device 55 mainly includes a residue storage tank 41 connected to the discharge port 19 of the fermentation tank 52, a digestion liquid dehydration removal device 43 connected to the residue storage tank 41 via a residue feed path 42, and a residue A drainage pit 46 for storing the digested liquid collected from the residue by the storage tank 41 and the digested liquid dehydration and removal device 43 is provided. Between the discharge port 19 of the fermenter 52 and the residue storage tank 41, a first residue discharge valve 44 is provided that partitions these and restricts the movement of the fermentation residue to the residue storage tank 41. Between the residue storage tank 41 and the residue supply path 42, a second residue discharge valve 45 is provided for partitioning these and regulating the movement of the fermentation residue to the residue supply path 42. The operations of the first residue discharge valve 44, the second residue discharge valve 45, and the digestive fluid dehydration removal apparatus 43 are controlled by a residue discharge apparatus control unit 47.

  The operation of the residue discharging apparatus 55 having the above configuration will be described. Residue discharge device control unit 47 receives fermentation residue discharge instruction input via a control panel (not shown), and opens first residue discharge valve 44 for a predetermined first discharge time. The first discharge time is set by the moving speed of the substance in the fermenter 52 by the moving device 20 and the amount of fermentation residue. When the first residue discharge valve 44 is opened, the fermentation residue in the fermentation tank 52 is introduced into the residue storage tank 41 through the discharge port 19 by the moving device 20. In the residue storage tank 41, the digested liquid is separated from the fermentation residue, and the digested liquid separated from the fermentation residue is drained to the drain pit 46. In this manner, the residue discharge device control unit 47 opens the second residue discharge valve 45 for a predetermined second discharge time in a state where the digested liquid of the fermentation residue is removed to some extent. The second discharge time is set by the amount of fermentation residue. When the second residue discharge valve 45 is opened, it is sent from the residue storage tank 41 to the digestive juice dehydration removal device 43 through the residue feed path 42. The fermentation residue sent to the digestive fluid dehydration and removal device 43 is further dehydrated here, and the digested fluid separated from the fermentation residue is drained to the drain pit 46. As described above, the fermentation residue whose volume has been reduced, reduced, and dehydrated by the residue discharge device 55 is transported from the digestive liquid dehydration removal device 43 to the MSW storage pit 31 of the fuel production unit 3 and reused as a raw material for RDF. When there are a plurality of fuel production units 3, the fermentation residue is conveyed to the MSW storage pit 31 of the fuel production unit 3 that is closest to the fuel long-term storage unit 5.

  Here, it returns to the flow of the biogas generated in the fermenter 52 and demonstrates. At the initial stage of RDF charging, many portions in the fermenter 52 are in an “empty” state, and the portions are filled with air. Therefore, the gas flowing out from the fermenter 52 to the biogas first flow path 22 in the initial stage of RDF charging becomes a mixed gas of the biogas generated by RDF fermentation and the air remaining in the fermenter 52. Methane gas, the main component of biogas generated by anaerobic fermentation, is a flammable gas. According to the mixing ratio of methane gas and oxygen in biogas, supply of combustion oxygen from the outside as long as biogas is the source of fire There is a risk of explosive combustion without exposure. Therefore, the fermenter control unit 28 detects the composition of the outflow gas flowing out from the fermenter 52 to the biogas first flow path 22 using the detectors 71, 78, and 79, and mixes oxygen and methane gas in the outflow gas. When the ratio is within the combustion range, it is determined to be “uncompressible”, and when it is outside the combustion range, it is determined to be “compressible”. Then, the fermenter control unit 28 opens the first inflow control valve 23 when the mixing ratio of oxygen and methane gas in the effluent gas from the fermenter 52 is outside the combustion range, and sends the effluent gas to the primary storage tank 53. Control to send. The phenomenon in which the mixing ratio of oxygen and methane gas in the effluent gas from the fermenter 52 falls within the combustion range is significant when RDF is started to be introduced into the fermenter 52. To avoid this phenomenon, RDF It is desirable to replace the air in the fermenter 52 with an inert gas before introducing the fermenter into the fermenter 52.

  FIG. 6A is a graph showing a combustion upper limit value and a combustion lower limit value of a mixed gas of natural gas and air, the vertical axis is the natural gas concentration in the air, and the horizontal axis is the pressure of the natural gas. As shown in the figure, the upper limit of combustion of natural gas at atmospheric pressure is 15.0 [volume% in air], and the lower limit of combustion is 5.0 [volume% in air]. That is, the combustion range of natural gas at atmospheric pressure is 5.0 to 15.0 [volume% in air]. FIG. 6 (b) is obtained by converting the combustion upper limit value and the combustion lower limit value of the mixed gas of natural gas and air shown in FIG. 6 (a) into the relationship between the oxygen concentration and the pressure of the natural gas. The main component of natural gas is methane (about 85-95%). On the other hand, the composition of biogas is approximately 60% methane and 40% carbon dioxide. Strictly speaking, natural gas is different from methane gas, but safety can be secured even if the value of the combustion range of natural gas is used as the value of the combustion range of methane gas in examining the combustion range of the outflow gas from the fermenter 52. . Therefore, in the following, in examining the combustion range of the effluent gas from the fermenter 52 (particularly, the lower limit of combustion), the natural gas in FIG. 6 (a) and FIG. The indicated data will be used.

  In examining the combustion range of the outflow gas from the fermenter 52, it is assumed that the discharge pressure of the compressor 57 described later is 5 MPa and the temperature of the compressed biogas is 300 ° C. Here, referring to FIG. 6B, the lower limit value of the oxygen concentration when the pressure of methane gas is 5 MPa and the temperature is 300 ° C. is 8 to 9%. Therefore, in consideration of the safety factor, if the outflow gas from the fermenter 52 is sent to the primary storage tank 53 as a biogas with an oxygen concentration of 8% or less, even if this biogas is compressed by the compressor 57 The mixing ratio of oxygen and methane gas is outside the combustion range. On the other hand, the upper limit of the oxygen concentration when the pressure of methane gas is 5 MPa and the temperature is 300 ° C. is approximately 20%. However, since the oxygen concentration in the air is about 21%, it is safe not to compress the outflow gas exceeding the upper limit value of the oxygen concentration in consideration of the safety factor. From the above, when the discharge pressure of the compressor 57 is 5 MPa and the temperature of the biogas after compression is 300 ° C., out of the outflow gas from the fermenter 52 based on the data in FIGS. Those having an oxygen concentration exceeding 8% are considered to be within the combustion range, and those having an oxygen concentration of 8% or less are considered to be outside the combustion range.

  FIG. 7 is a flowchart showing the flow of control of the fermenter control unit 28 at the initial stage of RDF charging. When the fermentation of the RDF newly introduced into the fermenter 52 is started, the first inflow control valve 23 and the air release valve 25 are closed, and the fermenter 52 is filled with initial air, so that it is in an aerobic state. It has become. Therefore, aerobic fermentation is performed in the fermenter 52 for a while after the start of fermentation, but as the aerobic fermentation proceeds, the oxygen in the fermenter 52 is consumed, thereby making the fermenter 52 anaerobic and anaerobic fermentation. Migrate to As shown in FIG. 7, the fermenter control unit 28 detects that biogas is generated based on the pressure in the fermenter 52 detected by the pressure detector 71 (YES in step S1), and the atmospheric emission valve. 25 is released (step S3). At the initial stage of RDF charging, the amount of biogas generated from RDF is small and the amount of air remaining in the fermenter 52 is large. Therefore, the effluent gas from the fermenter 52 is initially composed of a methane gas amount of 0% and an air amount of 100%, and the mixing ratio of oxygen and methane gas in the effluent gas is within the combustion range (here, less than the upper combustion limit). It is. By opening the atmospheric diffusion valve 25, outflow gas from the fermenter 52 that is unsuitable for compression (that is, a mixture ratio of oxygen and methane gas within the combustion range) is diffused to the atmosphere through the atmospheric diffusion path 24.

  With the introduction of RDF and the promotion of fermentation, the amount of generated biogas increases and the amount of remaining oxygen decreases, whereby the amount of methane gas in the effluent gas from the fermenter 52 increases and the amount of air (oxygen amount) decreases. Decrease. Eventually, the mixing ratio of oxygen and methane gas in the outflow gas from the fermenter 52 becomes out of the combustion range (here, the combustion upper limit value or more). Based on the detection values of the oxygen concentration detector 78, the methane concentration detector 79, and the pressure detector 71, the fermenter control unit 28 determines that the mixing ratio of oxygen and methane gas in the effluent gas from the fermenter 52 is outside the combustion range. If it is (YES in step S2), the atmospheric diffusion valve 25 is closed and the first inflow control valve 23 is opened (step S4). In this state, most of the outflow gas from the fermenter 52 is biogas. By opening the first inflow control valve 23, the fermenter 52 and the primary storage tank 53 communicate with each other via the biogas first flow path 22, and the biogas flows from the fermenter 52 into the primary storage tank 53.

  Of the outflow gas flowing out from the fermenter 52 to the biogas first flow path 22 by the control of the fermenter control unit 28, only the biogas having a compressible composition is sent to the primary storage tank 53 and is not suitable for compression. Those having such a composition are diffused into the atmosphere through the atmosphere diffusion path 24. In addition, in the said embodiment, although the atmospheric | air diffusion path 24 has branched from the biogas 1st flow path 22, you may be connected with the primary storage tank 53. FIG.

  The primary storage tank 53 is a biogas storage tank for storing biogas sent from the fermenter 52 via the biogas first flow path 22. The biogas sent from the fermenter 52 to the primary storage tank 53 varies depending on the amount of RDF input into the fermenter 52 and the fermentation state after input. The primary storage tank 53 is a buffer tank for storing the biogas flowing out from the fermenter 52 and preventing an abnormal increase in the pressure in the fermenter 52. The primary storage tank 53 is also a buffer tank that buffers an imbalance between the suction flow rate of the compressor 57 and the amount of biogas generated from the fermenter 52. Therefore, it is desirable that the primary storage tank 53 has a sufficient capacity.

  The primary storage tank 53 is connected to one or a plurality of secondary storage tanks 54 through piping that forms the biogas second flow path 56. The biogas second flow path 56 is provided with a compressor 57, a cooler 83, and a second inflow control valve 80 to the secondary storage tank 54 in order from the upstream side. Furthermore, on the upstream side of the compressor 57 in the primary storage tank 53 and the biogas second flow path 56, a pressure detector 72 for detecting the pressure in the primary storage tank 53, and the biogas in the primary storage tank 53 An oxygen concentration detector 73 for detecting the oxygen concentration is provided. The compressor control unit 60 receives detection signals from the pressure detector 72 and the oxygen concentration detector 73, and the biogas in the primary storage tank 53 is appropriately compressed by the compressor 57 and sent to the secondary storage tank 54. In addition, the compressor 57 and the second inflow control valve 80 are controlled so that the pressure in the primary storage tank 53 does not become negative. The oxygen concentration detector 73 detects the oxygen concentration in the biogas to be compressed, and the compressor control unit 60 determines whether the biogas can be compressed based on the detection result.

  In the present embodiment, the primary storage tank 53 is connected to two secondary storage tanks 54, but the number of secondary storage tanks 54 is not limited to this. The number, capacity and internal pressure of the secondary storage tank 54 are determined based on the amount of RDF to be processed and the amount of biogas generated during the storage period. However, from the viewpoint of the construction cost of the secondary storage tank 54 and the versatility of the compressor 57, the pressure of the biogas in the secondary storage tank 54 is preferably 2 to 5 MPa. When the pressure of the biogas is higher than this, it is preferable to increase the radix of the secondary storage tank 54. In addition, when the installation space of the secondary storage tank 54 has restrictions, the pressure of the biogas in the secondary storage tank 54 may be 2-5 MPa or more.

  As described above, the biogas generated along with the anaerobic fermentation of RDF is balanced with the pressure in the fermenter 52 in the primary storage tank 53, compressed by the compressor 57, cooled by the cooler 83, It is stored in the secondary storage tank 54. Since the biogas stored in the secondary storage tank 54 is reduced in volume by compression, the space for storing the biogas can be reduced. Furthermore, since biogas is a gas, it is easier to manage the state compared to storing RDF that is easily fermented as it is, and handling during storage is easy.

  The biogas stored in the secondary storage tank 54 is supplied to the boiler 61 of the power generation unit 6 by the biogas supply equipment 59. A biogas supply path 58 for supplying biogas to the boiler 61 is connected to the secondary storage tank 54. In the biogas supply path 58, a tank opening / closing valve 81, a methane concentration detector 75 for detecting the methane concentration of the biogas, and a biogas supply source valve 77 are provided in this order from the upstream side. The biogas supply path 58 branches in two directions on the downstream side of the methane concentration detector 75, and the downstream side from this bifurcated branch is a primary combustion air supply path 65 and a secondary combustion air supply path 66 to the boiler 61, respectively. It is connected. Between the bifurcated branch and the primary combustion air supply path 65 and the secondary combustion air supply path 66, flow rate adjusting valves 85 and 86 for adjusting the amount of biogas supplied to the supply paths 65 and 66 are provided. It has been. The biogas supply control unit 70 then detects the pressure detector 76 of the secondary storage tank 54, the detection signal of the methane concentration detector 75, the primary or secondary combustion air amount to the boiler 61, and the combustion of the boiler 61. Based on the load information, the operations of the tank opening / closing valve 81, the biogas supply source valve 77, and the flow rate adjusting valves 85, 86 are controlled.

  Depending on the structure of the boiler 61, it may be desirable to prioritize the mixing of the secondary combustion air and the biogas over the mixing of the primary combustion air and the biogas, so that the biogas stored in the secondary storage tank 54 is Usually, it is sent to the secondary combustion air supply passage 66 and supplied to the combustion chamber 61a of the boiler 61 instead of the secondary combustion air or as an air-fuel mixture with the secondary combustion air. For this purpose, the biogas supply control unit 70 opens the tank opening / closing valve 81 and the biogas supply source valve 77 and adjusts the flow rate of the biogas by the flow rate adjustment valve 86. When mixing biogas and secondary combustion air, the flow rate of the biogas is adjusted by the flow rate adjusting valve 86. Here, the flow rate of biogas is such that the mixing ratio of air and methane gas in the mixture of secondary combustion air and biogas is to prevent abnormal combustion in the air and biogas mixed gas supply channel. It adjusts so that it may become out of a combustion range (mixing ratio below the lower limit of combustion shown in Drawing 6 (a)). For this purpose, the biogas supply control unit 70 controls the opening and closing and the opening degree of the flow control valve 86 based on the amount of secondary combustion air to the boiler 61, the methane concentration of the biogas, and the combustion load information of the boiler 61. .

  As described above, normally, the biogas is sent exclusively to the secondary combustion air supply path 66. However, when a boiler load increase command is issued based on the combustion load information of the boiler 61, it is difficult to increase the amount of RDF input, and the amount of biogas mixed into the secondary combustion air is limited by the combustion lower limit value The biogas is also sent to the primary combustion air supply path 65. For this purpose, the biogas supply control unit 70 adjusts the opening degree of the flow rate adjustment valve 85. Again, in order to make the mixing ratio of air and methane gas in the mixture of primary combustion air and biogas out of the combustion range (mixing ratio below the lower combustion limit shown in FIG. 6 (a)), Based on the amount of primary combustion air, the methane concentration of the biogas, and the combustion load information of the boiler 61, the opening / closing and opening of the flow rate adjustment valve 85 are adjusted to adjust the amount of biogas supplied to the primary combustion air supply path 65. Is done.

  Further, when the calorie of the biogas stored in the secondary storage tank 54 is sufficiently high to be used as the startup fuel for the boiler 61, the biogas is used as the startup fuel for the boiler 61 or its auxiliary fuel. can do. In this case, as shown by a two-dot chain line in FIG. 4, a flow path connected to the startup fuel supply path 67 in parallel with the flow path connected to the primary combustion air supply path 65 and the secondary combustion air supply path 66 is provided. And a flow rate adjusting valve 87 is provided in this flow path. The biogas supply control unit 70 opens the tank opening / closing valve 81 and the biogas supply source valve 77 when starting the boiler 61 and adjusts the opening degree of the flow rate adjusting valve 87 to start the biogas from the boiler 61. The fuel is supplied to the fuel supply passage 67. When biogas is used as the starting fuel for the boiler 61, the pressure of the biogas in the secondary storage tank 54 can be maintained even after the boiler 61 is started, as required by the starting burner for the boiler 61. The pressure is desirable.

  Here, the flow from recovery of MSW to power generation using RDF fuel in the RDF-fired power generation system 1 having the above configuration will be described. First, RDF is manufactured from the MSW recovered by the fuel manufacturing unit 3. The manufactured RDF is primarily stored in the fuel storage 36 of the temporary fuel storage unit 4. When the boiler 61 of the power generation unit 6 is operating, the RDF stored in the fuel storage 36 is supplied to the boiler 61 as fuel. In the power generation unit 6, RDF is burned by the boiler 61, the heat is recovered to generate high-temperature and high-pressure steam, and power is generated by rotating the turbine of the steam turbine power generation facility 62. On the other hand, when the boiler 61 of the power generation unit 6 is stopped or when it is necessary to store the RDF for a long time (for example, one week or more), the RDF stored in the fuel storage 36 is first stored in the fuel storage 36. Are sequentially sent to the long-term fuel storage unit 5.

  In the fermenter 52 of the long-term fuel storage unit 5, RDF undergoes anaerobic fermentation to produce biogas and fermentation residues. The fermentation residue produced by the anaerobic fermentation of RDF is discharged from the fermenter 52 and the water is removed, and then transferred to the fuel production unit 3 and used as a raw material for RDF. On the other hand, the biogas generated by the anaerobic fermentation of RDF is sent to the primary storage tank 53, compressed by the compressor 57, cooled by the cooler 83, and then sent to the secondary storage tank 54 for storage. The biogas stored in the secondary storage tank 54 is supplied to the boiler 61 during operation of the power generation unit 6 and used as fuel or auxiliary fuel. For this reason, the boiler 61 immediately after starting becomes a mixed combustion operation of RDF and biogas. When all the RDF in the long-term fuel storage unit 5 is fermented and all the generated biogas is used up, the boiler 61 enters the RDF combustion operation.

  In the above, RDF is not sent from the temporary fuel storage unit 4 to the long-term fuel storage unit 5 when the power generation unit 6 is in operation, but RDF is also sent from the temporary fuel storage unit 4 to the long-term fuel storage unit 5 during operation of the power generation unit 6. It can also be sent. For example, the RDF is stored in the long-term fuel storage unit 5 while supplying the RDF from the temporary fuel storage unit 4 to the power generation unit 6 in order to balance the supply amount of RDF to the boiler 61 of the power generation unit 6 and the demand amount. can do. In this way, the space for RDF storage including the temporary fuel storage unit 4 and the long-term fuel storage unit 5 can be further reduced. Furthermore, it becomes possible to balance supply and demand between the RDF manufactured from the MSW and the RDF consumed by the boiler 61.

  As described above, in the RDF-fired power generation system 1, the surplus RDF is stored in the form of biogas and fermentation residue. Since biogas is a gas, it is easier to manage long-term storage and long-term storage in a sealed space than when solid RDF is stored in a conventional RDF storage. Moreover, the volume of the biogas which is a gas can be easily reduced by compression, and the storage space can be reduced by storing the biogas in a compressed state. In addition, since the fermentation residue is dehydrated, reduced in volume, and reduced in volume, the space for storing solid matter can be reduced as compared with the case of storing RDF, and management of storage is easy. That is, according to the long-term fuel storage unit 5 of the RDF-fired power generation system 1, it is possible to reduce the space for storing the RDF and to prevent the methane gas fire that occurs due to the aerobic fermentation during the long-term storage of the RDF. it can. Moreover, although the form of RDF is changed to biogas and fermentation residue, biogas is reused as fuel in the boiler 61, and the fermentation residue is used as a raw material for RDF, so the energy of RDF is fully utilized. . Furthermore, in the long-term fuel storage unit 5 of the RDF-fired power generation system 1, it is possible to store RDF that is easily fermented in a dry environment and a high-temperature and humid environment, and it is easy to ferment regardless of the storage environment. Can be stored stably.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. Is.

  For example, in the long-term fuel storage unit 5 according to the above embodiment, outflow gas from the fermenter 52 whose oxygen and methane gas mixing ratio is within the fuel range cannot be compressed and stored, but is thus released into the atmosphere. The effluent gas may be collected and used as energy without being compressed. FIG. 8 is a conceptual diagram showing a configuration upstream of the primary storage tank of the fuel long-term storage unit according to the modification, and FIG. 9 is a concept showing a configuration downstream of the primary storage tank of the fuel long-term storage unit according to the modification. FIG. The modified example of the fuel long-term storage unit 5 shown in these drawings is a reserve storage tank 92 connected to the fermenter 52 via the biogas third flow path 91 as compared with the fuel long-term storage unit 5 shown in FIG. It is different in that it is equipped with. The biogas third flow path 91 is provided with a third inflow control valve 93 that is controlled to be opened and closed by the fermenter controller 28. The auxiliary storage tank 92 is provided with an air diffusion path 24 and an air diffusion valve 25. The preliminary storage tank 92 is connected to the primary combustion air supply path 65 and the secondary combustion air supply path 66 of the boiler 61 through the second biogas supply path 95. The second biogas supply passage 95 has a low-pressure blower 96 for supplying the biogas in the auxiliary storage tank 92, a methane concentration detector 84, and biogas supplied to the combustion air supply paths 65 and 66. Flow rate adjusting valves 97 and 98 for adjusting the flow rate are provided. In the fuel long-term storage unit 5 configured as described above, the fermenter control unit 28 has a mixing ratio of oxygen and methane gas of the outflow gas from the fermenter 52 based on the detection values of the concentration detector 78 and the methane concentration detector 79. When it is within the combustion range, the third inflow control valve 93 is opened. Thereby, the mixing ratio of methane gas and oxygen is within the combustion range, and the outflow gas (mixed gas of biogas and air) unsuitable for compression is sent to the preliminary storage tank 92 and stored in the preliminary storage tank 92. . The biogas stored in the preliminary storage tank 92 without being compressed is stored in the primary combustion air supply path 65 and the secondary combustion air supply path 66 through the second biogas supply path 95 by the low pressure blower 96 when the power generation unit 6 is operated. It is pumped to at least one and used as fuel for the boiler 61.

  In addition, for example, the RDF-fired power generation system 1 according to the above-described embodiment is a system that generates power using RDF manufactured from MSW as fuel, and this is used as fuel for biomass-derived waste-derived solid fuel manufactured from biomass-based waste. It can also be applied to a power generation system. In this case, in the above embodiment, the present invention is applied to the RDF-fired power generation system 1 for biomass waste by replacing MSW with biomass waste and RDF with biomass waste-derived solid fuel. Can be explained.

  INDUSTRIAL APPLICABILITY The present invention is useful for storing a fermented waste-derived solid fuel such as fluff RDF or biomass-based waste-derived solid fuel in a stable state for a long period of time.

DESCRIPTION OF SYMBOLS 1 RDF-fired power generation system 3 Fuel production part 4 Fuel temporary storage part 5 Fuel long-term storage part 6 Power generation part 20 Conveyance device 22 Biogas 1st flow path 23 1st inflow control valve 25 Atmospheric release valve 31 MSW storage pit 36 Fuel storage 51 Input device 52 Fermenter 53 Primary storage tank (biogas storage tank)
54 Secondary storage tank (biogas storage tank)
55 Residue discharge device 56 Biogas second flow path 57 Compressor 58 Biogas supply path 59 Biogas supply equipment 61 Boiler 62 Steam turbine power generation equipment 63 Exhaust gas treatment equipment 65 Primary combustion air supply path 66 Secondary combustion air supply path 92 Spare storage tank

Claims (22)

A storage facility for storing solid fuel derived from waste that is easy to ferment before combustion in a combustion facility,
A fermentor for anaerobically fermenting the waste-derived solid fuel;
A biogas storage tank for storing biogas produced by anaerobic fermentation of the waste-derived solid fuel;
A first flow path for sending the biogas from the fermenter to the biogas storage tank;
A supply path for supplying the biogas from the biogas storage tank to the fuel facility;
Storage facility for waste-derived solid fuel. The biogas storage tank includes a primary storage tank to which the biogas is sent from the fermentation tank through the first flow path, and a secondary storage tank connected to the primary storage tank and the second flow path,
A compressor that compresses and sends the biogas from the primary storage tank to the secondary storage tank in the second flow path;
The waste-derived solid fuel storage facility according to claim 1, further comprising a cooler that cools the biogas compressed by the compressor in the second flow path.   The water removal means which removes the water | moisture content which is the fermented residue of the said waste origin solid fuel discharged | emitted from the said fermenter, and the water contained in the fermentation residue of the said waste origin solid fuel is provided. The waste-derived solid fuel storage facility described in 1. An oxygen concentration detector for detecting the oxygen concentration of the outflow gas flowing out from the fermenter to the first flow path;
A methane concentration detector for detecting the methane concentration of the effluent gas;
Based on the detected oxygen concentration and methane concentration, when the mixing ratio of oxygen and methane gas of the effluent gas is outside the combustion range, the valve is opened to communicate the first flow path with the biogas storage tank. The storage facility for waste-derived solid fuel according to any one of claims 1 to 3, comprising one control valve. An atmospheric passage for communicating the inside of the fermenter with the atmosphere;
Based on the oxygen concentration detected by the oxygen concentration detector and the methane concentration detected by the methane concentration detector, the valve is opened when the mixing ratio of oxygen and methane gas in the effluent gas is within the combustion range. The waste-derived solid fuel storage facility according to claim 4, further comprising: an atmospheric emission valve that diffuses the outflow gas to the atmosphere through an atmospheric emission path. A preliminary storage tank connected to the fermenter via a third flow path;
Based on the oxygen concentration detected by the oxygen concentration detector and the methane concentration detected by the methane concentration detector, the valve is opened when the mixing ratio of oxygen and methane gas in the effluent gas is within the combustion range. The waste-derived solid fuel storage facility according to claim 4, further comprising a second control valve that communicates the third flow path with the preliminary storage tank.   The said supply path has a path | route which supplies the said biogas stored by the said biogas storage tank to the said combustion equipment as a starting fuel of the said combustion equipment. Storage facility for waste-derived solid fuel.   2. The supply path has a path for supplying the biogas stored in the biogas storage tank to at least one of a primary combustion air supply path and a secondary combustion air supply path of the combustion facility. The storage facility for the waste-derived solid fuel according to any one of?   The supply path adjusts the supply amount of the biogas so that the biogas supplied to the combustion facility is mixed with the primary combustion air or the secondary combustion air of the combustion facility at a mixing ratio outside the combustion range. The waste-derived solid fuel storage facility according to claim 8, comprising adjusting means.   The waste-derived solid fuel storage facility according to any one of claims 1 to 9, wherein the waste-derived solid fuel is waste solidified fuel produced from general waste.   The waste-derived solid fuel storage facility according to any one of claims 1 to 9, wherein the waste-derived solid fuel is a biomass waste-derived solid fuel produced from biomass-based waste. A method for storing waste-derived solid fuel that is easily fermented before combustion in a combustion facility,
Anaerobic fermentation of the waste-derived solid fuel in an anaerobic fermentation tank;
Storing biogas produced by anaerobic fermentation of the waste-derived solid fuel in a biogas storage tank,
Storage method of solid fuel derived from waste. The step of storing the biogas in a biogas storage tank includes:
Storing the biogas sent from the fermenter in a primary storage tank;
Reducing the volume of the biogas by compressing it from the primary storage tank to the secondary storage tank and sending the biogas;
Cooling the compressed biogas;
The method for storing waste-derived solid fuel according to claim 12, comprising storing the compressed biogas in the secondary storage tank.   14. The method according to claim 12, further comprising a step of removing moisture that is a fermented residue of the waste-derived solid fuel discharged from the fermenter and moisture contained in the fermentation residue of the waste-derived solid fuel. Storage method for waste-derived solid fuel. In the step of storing the biogas in a biogas storage tank,
The oxygen concentration and methane concentration of the effluent gas flowing out from the fermentor containing the biogas are detected, and based on the detection result, the effluent gas having a mixture ratio of oxygen and methane gas outside the combustion range is detected. The storage method of the solid fuel derived from a waste as described in any one of Claims 12-14 stored in a biogas storage tank. In the step of storing the biogas in a biogas storage tank,
The waste-derived solid fuel storage method according to claim 15, wherein, based on the oxygen concentration and methane concentration of the effluent gas, the effluent gas having a mixing ratio of oxygen and methane gas within the combustion range is released into the atmosphere. . In the step of storing the biogas in a biogas storage tank,
16. Based on the oxygen concentration and methane concentration of the effluent gas, the effluent gas having a mixing ratio of oxygen and methane gas within a combustion range is stored in a spare storage tank different from the biogas storage tank. The method for storing waste-derived solid fuel according to claim 1.   The waste-derived material according to any one of claims 12 to 17, further comprising a step of supplying the biogas stored in the biogas storage tank to the combustion facility as a starting fuel for the combustion facility. Solid fuel storage method.   19. The method according to claim 12, further comprising a step of supplying the biogas stored in the biogas storage tank to at least one of a primary combustion air supply path and a secondary combustion air supply path of the combustion facility. The waste-derived solid fuel storage method according to claim 1.   The supply amount of the biogas is adjusted so that the biogas supplied to the combustion facility is mixed with the primary combustion air or the secondary combustion air of the combustion facility at a mixing ratio outside the combustion range. Storage method for waste-derived solid fuel.   The waste-derived solid fuel storage method according to any one of claims 12 to 20, wherein the waste-derived solid fuel is a solid waste fuel produced from general waste.   The waste-derived solid fuel storage method according to any one of claims 12 to 20, wherein the waste-derived solid fuel is a biomass-based waste-derived solid fuel produced from a biomass-based waste.

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