Waste treatment system and waste treatment method

Abstract

A waste treatment system (1) includes: at least one reformer (2) for hydrolyzing waste with steam; a microbial reactor (3) for microbially degrading a reformed material containing at least a solid of the waste hydrolyzed by the at least one reformer (2); and at least one steam generation device (4) for generating the steam by using only combustion energy of a gas produced in the microbial reactor (3). Fig. 1

Description

Waste treatment system and waste treatment method

[0001] This application claims priority to Japanese Patent Application No. 2020-162457, filed with the Japan Patent Office on September 28, 2020, the contents of which are incorporated herein by reference.

[0002] There is a need for effective utilization of unused biomass, such as urban waste discharged from households, food factories, etc., agricultural waste such as rice straw, wheat straw, and palm oil residue, livestock manure, and sewage sludge. For example, in the technology described in Patent Document 1, waste is hydrothermally treated (hydrolyzed) with steam in a reforming device, and solid fuel is produced from the solid phase of the reaction product obtained by this hydrolysis. Then, steam is generated using combustion energy produced by burning the solid fuel, and the hydrolysis is carried out using the generated steam.

[0003] Special Publication No. 2013-511386

[0004] However, in the technology described in Patent Document 1, steam is generated using the combustion energy produced by burning solid fuel, so the steam demand from the reformer cannot be met quickly, and there is a risk that the reformer will be put into standby mode.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a waste treatment system and a waste treatment method that can quickly meet the demand for steam from a reformer.

[0006] In order to achieve the above-mentioned object, the waste treatment system according to the present disclosure comprises at least one reforming device that hydrolyzes waste with steam, a microbial reaction device that uses microorganisms to reduce the molecular weight of the reformed product containing at least solids from the waste hydrolyzed in the at least one reforming device, and at least one steam generation device that generates the steam using only the combustion energy of the gas produced in the microbial reaction device.

[0007] In order to achieve the above-mentioned object, the waste treatment method according to the present disclosure comprises the steps of hydrolyzing waste with steam, converting a modified product containing at least solids from the hydrolyzed waste into smaller molecules using microorganisms, and generating the steam using only the combustion energy of the gas produced in the step of converting the modified product into smaller molecules using microorganisms.

[0008] According to the waste treatment system and waste treatment method of the present disclosure, the demand for steam from the reformer can be met quickly.

[0009] FIG. 1 is a schematic configuration diagram of a waste treatment system according to a first embodiment of the present disclosure. FIG. 2 is a schematic configuration diagram of a waste treatment system according to a second embodiment of the present disclosure. FIG. 3 is a schematic configuration diagram of a waste treatment system according to a third embodiment of the present disclosure. FIG. 4 is a schematic configuration diagram of a waste treatment system according to a fourth embodiment of the present disclosure. FIG. 5 is a schematic configuration diagram of a waste treatment system according to a fifth embodiment of the present disclosure. A part of the schematic configuration diagram of a waste treatment system according to an embodiment of the present disclosure, illustrating the peripheral configuration of a reformer. FIG. 6 is a graph showing the relationship between the amount of steam supplied to a first reformer according to an embodiment of the present disclosure and time. FIG. 7 is a graph showing the relationship between the amount of steam supplied to a second reformer according to an embodiment of the present disclosure and time. FIG. 8 is a flowchart of a waste treatment method according to an embodiment of the present disclosure.

[0010] A waste treatment system and a waste treatment method according to an embodiment of the present disclosure will be described below with reference to the drawings. The embodiment shows one aspect of the present disclosure, does not limit the present disclosure, and can be modified as desired within the scope of the technical concept of the present disclosure.

[0011] (Embodiment 1) <Configuration of waste treatment system according to embodiment 1> Fig. 1 is a schematic diagram of the configuration of a waste treatment system 1 according to embodiment 1 of the present disclosure. As shown in Fig. 1, the waste treatment system 1 according to embodiment 1 of the present disclosure includes a reformer 2, a microbial reaction device 3, and a steam generator 4.

[0012] The reformer 2 hydrolyzes waste with steam S1. The reformer 2 receives waste directly from a vehicle or a plant that collects waste, such as municipal solid waste, and hydrolyzes the waste batchwise with steam S1. Specifically, the reformer 2 is a batch-type reformer including a housing 10 having an inlet 11 through which the waste is introduced and an outlet 12 through which the hydrolyzed waste is discharged. The inlet 11 and the outlet 12 are each provided with an on-off valve (not shown), and the housing 10 can be sealed by closing the on-off valve. The hydrolysis of the waste in the reformer 2 may be wet hydrolysis, in which the steam S1 contacts the waste and heats it, or dry hydrolysis, in which the steam S1 does not contact the waste and indirectly heats it. In the case of dry hydrolysis, moisture in the waste within the housing 10 evaporates to form steam, which uniformly heats the waste within the housing 10. Furthermore, moisture is required for hydrolysis, and this moisture is supplied by the steam adhering to the surface of the waste. Although one reformer 2 is shown in FIG. 1, the configuration may be such that a plurality of reformers 2 are connected in series, a plurality of reformers 2 are connected in parallel, or a combination of a configuration in which the reformers are connected in series and a configuration in which the reformers are connected in parallel.

[0013] Municipal waste, cited as an example of waste, is primarily composed of food waste, paper waste, and plastic waste, with small amounts of metals. The waste treated by the waste treatment system 1 is not limited to municipal waste, and the waste treatment system 1 can also treat waste with a higher moisture content than municipal waste, such as sludge generated by treating wastewater from factories and agricultural waste.

[0014] The microbial reactor 3 uses microorganisms to reduce the molecular weight of the modified material X1, which contains at least solids from the waste hydrolyzed in the reformer 2. During this process, the microbial reactor 3 generates biogas G1. The microbial reactor 3 may have any configuration as long as it uses the modified material X1 as a raw material and generates biogas G1 using the biological action of microorganisms. For example, the microbial reactor 3 is a biogas fermenter that produces biogas G1, such as methane, as a valuable resource. However, the microbial reactor 3 is not limited to a biogas fermenter. For example, the microbial reactor 3 may be a saccharification tank that produces sugar as a valuable resource from carbohydrates such as starch and cellulose, or a composting device that produces compost by composting. Note that, according to the configuration illustrated in FIG. 1, the waste hydrolyzed in the reformer 2 can be reduced to reduce the molecular weight of the modified material X1 in the microbial reactor 3 to generate valuable resources without solid-liquid separation, allowing the waste treatment system 1 to treat even waste with a low moisture content at low cost.

[0015] The steam generator 4 generates steam S1 using only the combustion energy of the biogas G1 produced in the microbial reaction device 3. In other words, the steam generator 4 does not generate steam S1 using the combustion energy of any fuel other than the biogas G1 produced in the microbial reaction device 3. The reformer 2 then hydrolyzes the waste using the steam S1 generated by the steam generator 4. Such a steam generator 4 includes, for example, an exhaust gas boiler. The exhaust gas boiler generates steam S1 using the heat of the exhaust gas generated by the combustion of the biogas G1. Note that the steam generator 4 is not limited to an exhaust gas boiler. Instead of an exhaust gas boiler, the steam generator 4 may include a combustion boiler that generates steam S1 using the biogas G1 as fuel. Alternatively, the steam generator 4 may include both an exhaust gas boiler and a combustion boiler.

[0016] <Actions and Effects of Waste Treatment System According to Embodiment 1> The actions and effects of the waste treatment system 1 according to Embodiment 1 of the present disclosure will be described. Gaseous fuel burns faster than solid or liquid fuel. According to Embodiment 1, the reformer 2 performs hydrolysis with steam generated using only the combustion energy of the biogas G1 produced in the microbial reaction device 3. This allows the demand for steam S1 from the reformer 2 to be met quickly.

[0017] When the reformer 2 hydrolyzes waste with a low moisture content (e.g., municipal solid waste) to produce the reformed product X1, the amount of biogas G1 produced may be greater when the solids contained in the reformed product X1 are decomposed into smaller molecules by microorganisms than when only the liquid contained in the reformed product X1 is decomposed into smaller molecules by microorganisms. According to the first embodiment, the microbial reaction device 3 decomposes the reformed product X1, which contains at least the solids among the waste hydrolyzed in the reformer 2, into smaller molecules by microorganisms. This allows for an increase in the amount of biogas G1 produced.

[0018] (Embodiment 2) Next, a waste treatment system 1 according to embodiment 2 will be described. The waste treatment system 1 according to embodiment 2 is configured by adding a heat-retaining steam pipe 8 to embodiment 1. In embodiment 2, the same components as those in embodiment 1 are given the same reference numerals, and detailed description thereof will be omitted.

[0019] <Configuration of Waste Treatment System According to Embodiment 2> Fig. 2 is a schematic diagram of the configuration of a waste treatment system 1 according to Embodiment 2 of the present disclosure. As shown in Fig. 2, the waste treatment system 1 further includes a heat-retaining steam pipe 8 connecting the reformer 2 and the microbial reaction device 3.

[0020] Exhaust steam S2 discharged from the reformer 2 after the waste material is hydrolyzed in the reformer 2 flows through the heat-retaining steam pipe 8. The reformer 2 supplies the exhaust steam S2 to the microbial reaction device 3 via the heat-retaining steam pipe 8. The microbial reaction device 3 is kept warm by the heat of the exhaust steam S2 supplied from the reformer 2 so that the temperature falls within a predetermined temperature range of, for example, 30°C to 50°C.

[0021] <Functions and Effects of the Waste Treatment System According to the Second Embodiment> The microbial reaction device 3 is desirably kept warm within a predetermined temperature range to promote the degradation of the reformed product X1 by the microorganisms. According to the second embodiment, the exhaust steam S2 is used as a heat source for keeping the microbial reaction device 3 warm. This reduces the amount of fuel required to keep the microbial reaction device 3 warm, thereby reducing operating costs.

[0022] (Embodiment 3) Next, a waste treatment system 1 according to embodiment 3 will be described. The waste treatment system 1 according to embodiment 3 is obtained by adding a drying device 13 and a drying steam pipe 15 to embodiment 1. In embodiment 3, the same components as those in embodiment 1 are given the same reference numerals, and detailed description thereof will be omitted. A waste treatment system 1 according to another embodiment may be obtained by adding a drying device 13 and a drying steam pipe 15 to embodiment 2.

[0023] <Configuration of Waste Treatment System According to Embodiment 3> Fig. 3 is a schematic diagram of the configuration of a waste treatment system 1 according to Embodiment 3 of the present disclosure. As shown in Fig. 3, the waste treatment system 1 further includes a drying device 13 that dries a residue X2 obtained after the microbial reaction device 3 has used microorganisms to decompose the modified product X1 into smaller molecules, and a drying steam pipe 15 that connects the reformer 2 and the drying device 13.

[0024] 3, the waste treatment system 1 includes a dehydrator 14 that dehydrates a residue X2 (fermentation residue) that remains after the microbial reactor 3 decomposes the modified material X1 into smaller molecules using microorganisms. The residue X2 dehydrated by the dehydrator 14 is supplied to a dryer 13.

[0025] Exhaust steam S2 discharged from the reformer 2 after the waste material is hydrolyzed in the reformer 2 flows through the drying steam pipe 15. The reformer 2 supplies the exhaust steam S2 to the drying device 13 via this drying steam pipe 15. The drying device 13 dries the residue X2 dehydrated in the dehydration device 14 by using the heat of the exhaust steam S2 supplied from the reformer 2.

[0026] <Actions and Effects of the Waste Treatment System According to the Third Embodiment> As illustrated in Fig. 3, the waste treatment system 1 including the microbial reaction device 3 may include a drying device 13 that dries the residue X2 obtained from the microbial reaction device 3. According to the third embodiment, the exhaust steam S2 is used as a heat source for the drying device 13 to dry the residue X2. This makes it possible to reduce the amount of fuel prepared for drying the residue X2 in the drying device 13, thereby reducing operating costs.

[0027] (Embodiment 4) <Configuration of waste treatment system according to embodiment 4> Next, a waste treatment system 1 according to embodiment 4 will be described. The waste treatment system 1 according to embodiment 4 is configured by adding a separation device 16 to embodiment 1. In embodiment 4, the same components as those in embodiment 1 are given the same reference numerals, and detailed description thereof will be omitted. A waste treatment system 1 according to another embodiment may be configured by adding a separation device 16 to embodiment 2 or 3.

[0028] 4 is a schematic diagram of a waste treatment system 1 according to a fourth embodiment of the present disclosure. As shown in FIG. 4, the waste treatment system 1 further includes a separation device 16 provided between the reformer 2 and the microbial reaction device 3.

[0029] The separator 16 separates unsuitable materials for generating biogas G1 in the microbial reactor 3 from the modified material X1, which is waste hydrolyzed in the reformer 2. The separator 16 separates the modified material X1 into large particle size components and small particle size components smaller than the large particle size components. For example, the separator 16 is a screen with a given mesh size, which corresponds to the particle size at the boundary between the large particle size components and the small particle size components. The small particle size components are depolymerized in the microbial reactor 3 to generate valuable resources. The large particle size components are separated from the modified material X1 and are not supplied to the microbial reactor 3. This is because the main components of the large particle size components are relatively large even after hydrolysis in the reformer 2 and cannot be depolymerized in the microbial reactor 3, such as those derived from plastic waste or metals. In other words, the large particle size components and the small particle size components are unsuitable and suitable for microbial reaction, respectively.

[0030] In the embodiment illustrated in FIG. 4, the waste treatment system 1 includes the above-mentioned dehydration device 14, a reformate transfer line 22 that connects the reformer 2 and the separation device 16, and a water injection pipe 24 that connects the dehydration device 14 and the reformate transfer line 22.

[0031] The modified material transfer line 22 may be a pipe if the modified material X1 is in a slurry state, or may be a conveyor or the like if the modified material X1 is solid. Even if the modified material X1 is solid, the modified material transfer line 22 may be a pipe if it can be pumped by air or the like. The dehydration device 14 supplies water dehydrated from the residue X2 of the microbial reaction device 3 and boiler blowdown water to the modified material X1 in the modified material transfer line 22 via a water injection pipe 24. In other words, the water injection pipe 24 is configured as a moisture adjustment device that adjusts the moisture content of the modified material X1 between the reformer 2 and the microbial reaction device 3. In the embodiment illustrated in FIG. 5 , the water injection pipe 24 adjusts the moisture content of the modified material X1 upstream of the separation device 16, but the present disclosure is not limited to this embodiment. In another embodiment, the water injection pipe 24 adjusts the moisture content of the modified product X1 downstream of the separation device 16.

[0032] 4, the waste treatment system 1 further includes a moisture content acquisition device 30 that acquires the amount of moisture contained in the reformer 2. The moisture content acquisition device 30 acquires the amount of moisture contained in the reformer 2 based on statistical data of the raw material supplied to the reformer 2 (including waste property estimates based on images using machine learning, AI, etc.), weight, compaction torque, reformer temperature (inside, surface), the amount of steam S1 supplied to the reformer 2, the duration of time that steam S1 has been supplied to the reformer 2, and the amount of temperature change within the reformer 2. In other words, the moisture content acquisition device 30 includes a flow meter 30A that acquires the amount of steam S1 supplied to the reformer 2, a thermometer 30B that acquires the temperature within the reformer 2, a timer 30C, and a control device 30D. The control device 30D is electrically connected to each of the flow meter 30A, the thermometer 30B, and the timer 30C, and calculates (acquires) the amount of moisture contained in the reformer 2 based on the data acquired by each of the flow meter 30A, the thermometer 30B, and the timer 30C.

[0033] 4, as long as the moisture content acquisition device 30 acquires the amount of moisture contained in the reformer 2. For example, the moisture content acquisition device 30 may be a near-infrared type, a microwave type, or a capacitance type moisture meter.

[0034] The water injection pipe 24 (moisture adjusting device) adjusts the moisture content of the modified material X1 based on the moisture content acquired by the moisture content acquiring device 30. In the embodiment illustrated in Fig. 4, the water injection pipe 24 is provided with an adjusting valve 32 for adjusting the amount of water (water dehydrated from the residue X2 in the microbial reaction device 3 and boiler blow-down water) supplied from the dehydration device 14 to the modified material transfer line 22. The adjusting valve 32 is electrically connected to the control device 30D, and its opening is adjusted in accordance with instructions transmitted from the control device 30D.

[0035] In the example shown in Figure 4, the waste treatment system 1 includes a gas holder 18 that stores the biogas G1 generated in the microbial reaction device 3, a gas engine 20 that is driven using the biogas G1 stored in the gas holder 18 as fuel, an exhaust gas boiler 4A (4) that generates steam S1 using the heat of exhaust gas G4 from the gas engine 20, and a combustion boiler 4B (4) that generates steam S1 using the biogas G1 stored in the gas holder 18 as fuel.

[0036] The biogas G1 stored in the gas holder 18 is supplied to the gas engine 20. A generator main body (power generation device) (not shown) is connected to the gas engine 20. The generator main body generates electricity using combustion energy generated by burning the biogas G1. During this process, the gas engine 20 emits exhaust gas G4.

[0037] The exhaust gas G4 discharged from the gas engine 20 is supplied to an exhaust gas boiler 4A. The exhaust gas boiler 4A (first steam generator) is used to generate steam S1 to be supplied to the reformer 2. The exhaust gas boiler 4A generates steam S1 using only the combustion energy of the biogas G1, i.e., only the heat contained in the exhaust gas G4.

[0038] The biogas G1 stored in the gas holder 18 is also supplied to a combustion boiler 4B (second steam generator). The combustion boiler 4B is used to generate steam S1 to be supplied to the reformer 2. The combustion boiler 4B uses the biogas G1 as fuel and generates steam S1 using only the combustion energy of the biogas G1.

[0039] <Functions and Effects of the Waste Treatment System According to the Fourth Embodiment> According to the fourth embodiment, the separation device 16 is provided between the reformer 2 and the microbial reaction device 3, which reduces the amount of unsuitable materials supplied to the microbial reaction device 3. As a result, the risk of inhibiting the production of the biogas G1 in the microbial reaction device 3 is reduced, and the microbial reaction device 3 can efficiently produce the biogas G1.

[0040] Furthermore, according to the fourth embodiment, a water injection pipe 24 functioning as a moisture adjusting device is provided between the reformer 2 and the separator 16, so that the total solids concentration (TS) of the reformed material X1 hydrolyzed in the reformer 2 can be adjusted, thereby improving the efficiency of biogas G1 production by the microbial reaction device 3. Furthermore, since the water obtained by dehydrating the residue X2 in the microbial reaction device 3 contains ammonia, if the nitrogen content in the reformed material X1 is low, it is possible to replenish the reformed material X1 with a nitrogen-containing substance.

[0041] According to the findings of the present inventors, it has been found that the amount of moisture contained in the reformer 2 can be obtained with high accuracy from the amount of steam S1 supplied to the reformer 2, the time for which the state in which steam S1 is supplied to the reformer 2 continues, and the amount of temperature change within the reformer 2. According to the fourth embodiment, the waste treatment system 1 further includes a moisture amount obtaining device 30 that obtains the amount of moisture contained in the reformer 2, so that the amount of moisture contained in the reformer 2 can be obtained with high accuracy, and the efficiency of production of biogas G1 by the microbial reaction device 3 can be further improved.

[0042] According to the fourth embodiment, the total solids concentration (TS) of the reformed material X1 is adjusted based on the amount of moisture contained in the reformer 2 acquired by the moisture amount acquisition device 30 (calculated by the control device 30D), thereby further improving the efficiency of the production of biogas G1 by the microbial reaction device 3.

[0043] The exhaust gas boiler 4A and the combustion boiler 4B do not necessarily have to have the same capacity to generate steam S1. At least one of the exhaust gas boiler 4A and the combustion boiler 4B is configured to generate steam S1 according to the steam requirement of the reformer 2. The steam requirement of the reformer 2 is calculated based on, for example, the amount of waste input into the reformer 2 and the moisture content of the waste.

[0044] If the steam requirement of the reformer 2 can be met with the supply amount of steam S1 generated from one of the exhaust gas boiler 4A and the combustion boiler 4B, the other of the exhaust gas boiler 4A and the combustion boiler 4B can be put into a standby state or can generate steam other than that supplied to the reformer 2. Furthermore, if it is difficult to meet the steam requirement of the reformer 2 with only the supply amount of steam S1 generated from one of the exhaust gas boiler 4A and the combustion boiler 4B, the shortage can be made up for with the steam S1 generated by the other of the exhaust gas boiler 4A and the combustion boiler 4B. This makes it possible to realize efficient operation of the waste treatment system 1.

[0045] Although the method of operating the exhaust gas boiler 4A and the combustion boiler 4B is not particularly limited, an example of the operation method will be described below. The exhaust gas boiler 4A is always operated while the waste is being hydrolyzed in the reformer 2. The combustion boiler 4B is not operated while the hydrolysis conditions in the reformer 2 can be adjusted using only the steam S1 generated by the exhaust gas boiler 4A. When adjusting the hydrolysis conditions in accordance with the amount of waste input to the reformer 2 and the composition of the waste components, if the steam S1 generated by the exhaust gas boiler 4A alone is insufficient, the combustion boiler 4B is operated to supply not only the steam S1 generated by the exhaust gas boiler 4A but also the steam S1 generated by the combustion boiler 4B to the reformer 2. In this way, the adjustment range of the hydrolysis conditions in the reformer 2 can be broadened compared to when only the exhaust gas boiler 4A is provided. Furthermore, by providing two or more gas engines 20 and operating the number of gas engines 20 according to the amount of steam S1 generated in the exhaust gas boiler 4A, the range of adjustment of the hydrolysis conditions in the reformer 2 can be further expanded.

[0046] (Embodiment 5) <Configuration of a waste treatment system according to embodiment 5> Next, a waste treatment system 1 according to embodiment 5 will be described. The waste treatment system 1 according to embodiment 5 is limited to a case where multiple reforming devices 2 are provided, and in this respect it differs from the above-mentioned embodiments 1 to 4. In embodiment 5, the same components as those in embodiments 1 to 4 are given the same reference numerals, and detailed description thereof will be omitted.

[0047] Figure 5 is a schematic diagram of a waste treatment system 1 according to a fifth embodiment of the present disclosure. As shown in Figure 5, the waste treatment system 1 includes a first reformer 2A(2) and a second reformer 2B(2). In the configuration illustrated in Figure 5, the first reformer 2A(2) and the second reformer 2B(2) are connected in parallel to each other, allowing the waste input destination to be selected. The waste hydrolyzed in the first reformer 2A and the waste hydrolyzed in the second reformer 2B flow through a common reformed product transfer line 22 and are supplied to a separator 16.

[0048] The first reforming device 2A and the second reforming device 2B hydrolyze the waste with the steam S1 at different times. For example, the timing at which the steam S1 is supplied to the first reforming device 2A and the timing at which the steam S1 is supplied to the second reforming device 2B are shifted from each other.

[0049] The number of reformers 2 provided in the waste treatment system 1 is not particularly limited, but if the reformers 2 are batch-type reformers 2, the number of reformers 2 may be determined based on the batch time, which is the time from when waste is charged until the next charge of waste, and the heat-up time, which is the time it takes for the temperature inside the reformer 2 to rise to a preset temperature using steam S1. Specifically, the number of reformers 2 is determined by a natural number value obtained by dividing the batch time by the heat-up time. With this configuration, changes in the amount of steam required from the reformers 2 can be efficiently suppressed.

[0050] <Functions and Effects of the Waste Treatment System According to Embodiment 5> According to Embodiment 5, the total steam requirement required for the exhaust gas boiler 4A and the combustion boiler 4B can be reduced compared to when the first reformer 2A and the second reformer 2B perform hydrolysis at overlapping times, and a shortage of the amount of steam S1 supplied to the first reformer 2A and the second reformer 2B can be prevented. Furthermore, because the total steam requirement required for the exhaust gas boiler 4A and the combustion boiler 4B is reduced, the amount of biogas G1 used to generate steam S1 can be reduced. Therefore, this reduced amount of biogas G1 can be used for power generation in the gas engine 20, thereby increasing the amount of power generation.

[0051] Fig. 6 is a partial schematic diagram of the configuration of a waste treatment system 1 according to one embodiment of the present disclosure, illustrating the peripheral configuration of the reformer 2. In one embodiment, as shown in Fig. 6, the waste treatment system 1 further includes an exhaust steam distribution pipe 26 that connects the first reformer 2A and the second reformer 2B.

[0052] 6, the exhaust steam circulation pipe 26 includes a first exhaust steam circulation pipe 26A and a second exhaust steam circulation pipe 26B. The first exhaust steam circulation pipe 26A carries exhaust steam S21 (S2) exhausted from the first reformer 2A after the waste material is hydrolyzed in the first reformer 2A. The first reformer 2A supplies the exhaust steam S21 to the second reformer 2B via this first exhaust steam circulation pipe 26A. The second reformer 2B is heated by the heat contained in the exhaust steam S21 supplied from the first reformer 2A.

[0053] Similarly, the second exhaust steam distribution pipe 26B carries exhaust steam S22 (S2) discharged from the second reformer 2B after the waste material has been hydrolyzed in the second reformer 2B. The second reformer 2B supplies the exhaust steam S22 to the first reformer 2A via this second exhaust steam distribution pipe 26B. The first reformer 2A is heated by the heat of the exhaust steam S22 supplied from the second reformer 2B.

[0054] According to the configuration illustrated in Fig. 6, exhaust steam S2 generated by one reformer 2 after hydrolyzing waste material is used as a heat source for heating the other reformer 2. This reduces the amount of fuel required to heat the other reformer 2, thereby reducing operating costs. In the configuration illustrated in Fig. 6, the exhaust steam distribution pipe 26 includes the first exhaust steam distribution pipe 26A and the second exhaust steam distribution pipe 26B, but the present disclosure is not limited to this embodiment. The exhaust steam distribution pipe 26 may be configured to allow both the exhaust steam S21 and the exhaust steam S22 to flow through it. In other words, the first reformer 2A and the second reformer 2B may be configured to be able to supply exhaust steam S2 to each other via the common exhaust steam distribution pipe 26.

[0055] In one embodiment, if Tr is the heating time required to heat the temperature inside the reformer 2 with steam S1 to a preset temperature, and Tk is the maintenance time required to maintain the temperature inside the reformer 2 at the set temperature with steam S1, then Tr / Tk≧0.3 is satisfied.

[0056] If the temperature rise time Tr is short, the temperature inside the reformer 2 is quickly raised to the set temperature, which may cause the steam demand amount required by the reformer 2 to temporarily increase, making it difficult for the steam generator 4 to meet the demands of the reformer 2. In contrast, since Tr / Tk≧0.3 is satisfied, the steam demand amount required by the reformer 2 is prevented from temporarily increasing, and the steam generator 4 can meet the demands of the reformer 2.

[0057] In another embodiment, Tr / Tk ≥ 1.0 may be satisfied. According to this configuration, by making the temperature rise time Tr longer than the maintenance time Tk, it is possible to further suppress a temporary increase in the amount of steam required by the reformer 2, and to satisfy the requirements of the reformer 2.

[0058] 7A and 7B are graphs showing the relationship between time and the amount of steam S1 supplied to the first reformer 2A and the second reformer 2B according to an embodiment of the present invention. In both Figs. 7A and 7B, the horizontal axis represents time, and the vertical axis represents the amount of steam.

[0059] Referring to FIG. 7A, t1 is the timing at which the introduction of waste material into the first reformer 2A begins. t2 is the timing at which the supply of steam S1 to the first reformer 2A begins in order to raise the temperature inside the first reformer 2A to the set temperature. At t2, the introduction of waste material into the first reformer 2A has finished. t3 is the timing at which the supply of steam S1 to the first reformer 2A begins (at a small supply rate) in order to maintain the temperature inside the first reformer 2A at the set temperature. t4 is the timing at which the exhaust of steam S1 inside the first reformer 2A begins to be discharged to the outside. Hydrolysis of waste material in the first reformer 2A mainly takes place between t2 and t4. t5 is the timing at which the exhaust of steam S1 inside the first reformer 2A ends. After the exhaust of steam S1 ends, the first reformer 2A enters a standby state until the next introduction of waste material begins (the second t1).

[0060] Referring to FIG. 7B, t6 is the timing at which the introduction of waste material into the second reformer 2B begins. t7 is the timing at which the supply of steam S1 to the second reformer 2B begins in order to raise the temperature inside the second reformer 2B to the set temperature. At t7, the introduction of waste material into the second reformer 2B has finished. t8 is the timing at which the supply of steam S1 to the second reformer 2B begins (at a small supply rate) in order to maintain the temperature inside the second reformer 2B at the set temperature. t9 is the timing at which the exhaust of steam S1 from the second reformer 2B begins to be discharged to the outside. Hydrolysis of waste material in the second reformer 2B mainly takes place between t7 and t9. t10 is the timing at which the exhaust of steam S1 from the second reformer 2B ends. After the exhaust of steam S1 ends, the second reformer 2B enters a standby state until the next introduction of waste material begins (at t6 for the second time).

[0061] From t2 to t3, the amount of steam supplied to the first reformer 2A gradually increases. This is to prevent the first reformer 2A from dissipating heat and the temperature inside the first reformer 2A from decreasing by the amount of this heat dissipation. Similarly, from t7 to t8, the amount of steam supplied to the second reformer 2B gradually increases.

[0062] 7A and 7B, steam operation of the waste treatment system 1 according to one embodiment will be described.

[0063] A1 denotes a first period during which the temperature in the first reformer 2A is raised to a preset temperature using steam S1, and A2 denotes a second period during which the temperature in the second reformer 2B is raised to a preset temperature using steam S1. In other words, the first period A1 and the second period A2 correspond to the temperature rise time Tr described above. In one embodiment, as shown in Figures 7A and 7B, the first reformer 2A is raised to its temperature using steam S1, and the second reformer 2B is raised to its temperature using steam S1 so that the first period A1 and the second period A2 do not overlap. With this configuration, the total amount of steam required for the exhaust gas boiler 4A and the combustion boiler 4B can be reduced compared to when the first period A1 and the second period A2 overlap.

[0064] Furthermore, a third period A3 is defined as the period during which the temperature in the first reformer 2A is maintained at the set temperature using steam S1, and a fourth period A4 is defined as the period during which the temperature in the second reformer 2B is maintained at the set temperature using steam S1. In other words, the third period A3 and the fourth period A4 correspond to the maintenance time Tk described above. In one embodiment, the first reformer 2A is maintained at the set temperature using steam S1, and the second reformer 2B is heated up using steam S1 so that the third period A3 is included in the second period A2. The amount of steam S1 required to maintain the reformer 2 at the set temperature is much smaller than the amount of steam S1 required to heat the reformer 2 to the set temperature. In other words, even if steam operation is performed to maintain the first reformer 2A at the set temperature while the second reformer 2B is being heated up, there is little chance of a shortage of steam S1 supplied to the second reformer 2B. This allows the operating times of the first reformer 2A and the second reformer 2B to be increased. In another embodiment, the first reformer 2A may be heated with steam S1 and the second reformer 2B may be maintained at a set temperature with steam S1 so that the fourth period A4 is included within the next first period A1.

[0065] 8 is a flowchart of a waste treatment method 50 according to one embodiment of the present disclosure. As shown in FIG. 8, the waste treatment method 50 includes a step 52 of hydrolyzing waste with steam S1, a step 54 of microorganism-decomposing a modified product X1 containing at least solids from the waste hydrolyzed with steam S1 into smaller molecules, and a step 56 of generating steam S1 using only the combustion energy of biogas G1 produced in the step 54 of microorganism-decomposing the modified product X1. This method allows the demand for steam S1 for waste hydrolysis to be quickly met.

[0066] The contents described in each of the above embodiments can be understood, for example, as follows.

[0067] [1] A waste treatment system (1) according to the present disclosure includes at least one reformer (2) that hydrolyzes waste with steam (S1), a microbial reactor (3) that uses microorganisms to reduce the molecular weight of a reformate (X1) containing at least solids from the waste hydrolyzed in the at least one reformer, and at least one steam generator (4) that generates the steam using only the combustion energy of the gas produced in the microbial reactor.

[0068] Gaseous fuels burn faster than solid or liquid fuels. According to the configuration described in [1] above, the reformer hydrolyzes the gas produced in the microbial reactor using steam generated solely from the combustion energy of the gas. This allows the reformer to quickly meet its demand for steam.

[0069] [2] In some embodiments, the configuration described in [1] above further includes a heat-insulating steam pipe (8) connecting the reformer and the microbial reaction device, and the reformer supplies exhaust steam (S2) obtained after hydrolyzing the waste to the microbial reaction device via the heat-insulating steam pipe, and the microbial reaction device is kept warm by the heat of the exhaust steam supplied from the reformer so that it is within a predetermined temperature range.

[0070] The microbial reactor is preferably kept warm within a predetermined temperature range to promote the degradation of the reformed material by the microorganisms. According to the configuration described in [2] above, the exhaust steam generated after the reformer hydrolyzes the waste is used as a heat source to keep the microbial reactor warm. This reduces the amount of fuel required to keep the microbial reactor warm, thereby reducing operating costs.

[0071] [3] In some embodiments, the configuration described in [1] or [2] above further includes a drying device (13) that dries the residue (X2) obtained after the microbial reaction device has decomposed the modified material into smaller molecules using microorganisms, and a drying steam pipe (15) that connects the reforming device and the drying device, and the reforming device supplies exhaust steam obtained after hydrolyzing the waste to the drying device via the drying steam pipe, and the drying device dries the residue using the heat contained in the exhaust steam supplied from the reforming device.

[0072] The waste treatment system may include a drying device that dries the residue obtained from the microbial reactor. According to the configuration described in [3] above, the exhaust steam generated after the reformer hydrolyzes the waste is used as a heat source for the drying device to dry the residue. This reduces the amount of fuel required for the drying device to dry the residue, thereby reducing operating costs.

[0073] [4] In some embodiments, the configuration described in any one of [1] to [3] above further comprises a separator (16) provided between the at least one reformer and the microbial reactor, and the separator separates unsuitable materials from the waste hydrolyzed in the at least one reformer that are unsuitable for producing the gas in the microbial reactor.

[0074] According to the configuration described in [4] above, the amount of impurities supplied to the microbial reactor can be reduced, which reduces the risk of inhibiting gas production in the microbial reactor, allowing the microbial reactor to efficiently produce gas.

[0075] [5] In some embodiments, in the configuration described in any one of [1] to [4] above, the at least one steam generating device includes a first steam generating device (4A) and a second steam generating device (4B), and is configured to generate the steam from at least one of the first steam generating device and the second steam generating device in response to the steam demand of the reformer.

[0076] According to the configuration described in [5] above, if one of the first steam generator and the second steam generator can satisfy the steam demand of the reformer, the other steam generator can be put into a standby state or can generate steam other than that supplied to the reformer. Also, if it is difficult to satisfy the steam demand of the reformer with only one steam generator, the shortage can be made up for with the steam generated by the other steam generator. This allows for efficient operation of the waste treatment system.

[0077] [6] In some embodiments, in the configuration described in any one of [1] to [5] above, the at least one reformer includes a plurality of reformers, and at least two of the plurality of reformers are configured to perform hydrolysis at different times.

[0078] According to the configuration described in [6] above, compared to when at least two of the multiple reformers perform hydrolysis at overlapping times, the total amount of steam required from the steam generator can be reduced, and a shortage of steam supplied to the reformers can be prevented. Furthermore, each of the multiple reformers is supplied with steam generated using only the combustion energy of gas, rather than steam obtained by burning solid or liquid fuel. Therefore, the steam demand from the reformers can be met quickly.

[0079] [7] In some embodiments, in the configuration described in [6] above, the plurality of reformers include a first reformer (2A) and a second reformer (2B), and further include an exhaust steam circulation pipe (26) connecting the first reformer and the second reformer, and exhaust steam obtained after hydrolyzing the waste is supplied from the first reformer to the second reformer via the exhaust steam circulation pipe, and the second reformer is heated by the heat of the exhaust steam supplied from the first reformer.

[0080] According to the configuration described in [7] above, the exhaust steam from one reformer after hydrolyzing the waste material is used as a heat source to heat the other reformer, which reduces the amount of fuel required to heat the other reformer and reduces operating costs.

[0081] [8] In some embodiments, in the configuration described in any one of [1] to [7] above, when Tr is a temperature rise time for raising the temperature in the reformer to a preset temperature using the steam and Tk is a maintenance time for maintaining the temperature in the reformer at the preset temperature using the steam, Tr / Tk≧0.3 is satisfied.

[0082] If the temperature rise time is short, the temperature inside the reformer is quickly raised to the set temperature, which may cause a temporary increase in the amount of steam required by the reformer, making it difficult to meet the requirements of the reformer. In contrast, the configuration described in [8] above satisfies Tr / Tk≧0.3, thereby suppressing a temporary increase in the amount of steam required by the reformer and making it possible to meet the requirements of the reformer.

[0083] [9] In some embodiments, in the configuration described in [8] above, Tr / Tk≧1.0 is satisfied.

[0084] According to the configuration described in [9] above, by making the temperature rise time Tr longer than the maintenance time Tk, it is possible to further suppress a temporary increase in the amount of steam required from the reformer, and to meet the requirements of the reformer.

[0085]

[10] In some embodiments, in the configuration described in any one of [1] to [9] above, a moisture adjusting device (24) is further provided between the at least one reforming device and the microbial reaction device, for adjusting the moisture content of the waste hydrolyzed in the at least one reforming device.

[0086] According to the configuration described in

[10] above, the total solids concentration (TS) of the waste hydrolyzed in the reformer can be adjusted, thereby improving the efficiency of gas production by the microbial reaction device.

[0087]

[11] In some embodiments, the configuration described in

[10] above further includes a moisture content acquisition device (30) that acquires the moisture content contained in the reforming device, and the moisture adjustment device adjusts the moisture content of the waste hydrolyzed in the at least one reforming device based on the moisture content acquired by the moisture content acquisition device.

[0088] According to the configuration described in

[11] above, the total solids concentration (TS) of the waste hydrolyzed in the reformer is adjusted based on the amount of water contained in the reformer, thereby further improving the efficiency of gas production by the microbial reactor.

[0089]

[12] In some embodiments, in the configuration described in

[11] above, the moisture content acquisition device acquires the moisture content contained in the reformer based on the amount of steam supplied to the reformer, the duration for which the steam is supplied to the reformer, and the amount of temperature change within the reformer.

[0090] According to the findings of the present inventors, it has been found that the amount of moisture contained in the reformer can be obtained with high accuracy from the amount of steam supplied to the reformer, the duration of the state in which steam is supplied to the reformer, and the amount of temperature change within the reformer. According to the configuration described in

[12] above, the amount of moisture contained in the reformer can be obtained with high accuracy, and the efficiency of gas production by the microbial reaction device can be further improved.

[0091]

[13] A waste treatment method (50) according to the present disclosure includes a step (52) of hydrolyzing waste with steam, a step (54) of converting a modified product of the hydrolyzed waste, which contains at least solids, into smaller molecules using microorganisms, and a step (56) of generating the steam using only the combustion energy of the gas produced in the step of converting the modified product into smaller molecules using microorganisms.

[0092] According to the method described in

[13] above, the demand for steam for hydrolyzing waste can be quickly met.

[0093] REFERENCE SIGNS LIST 1 Waste treatment system 2 Reformer 2A First reformer 2B Second reformer 3 Microbial reaction device 4 Steam generator 4A Exhaust gas boiler (first steam generator) 4B Combustion boiler (second steam generator) 8 Heat-retaining steam pipe 13 Drying device 15 Drying steam pipe 16 Separator 24 Water injection pipe (moisture adjustment device) 26 Exhaust steam circulation pipe 30 Moisture content acquisition device 50 Waste treatment method A1 First period A2 Second period A3 Third period A4 Fourth period S1 Steam S2 Exhaust steam X1 Reformed product X2 Residue

Claims

1. A waste treatment system comprising: at least one reformer that hydrolyzes waste with steam; a microbial reactor that uses microorganisms to reduce the molecular weight of the reformed product, which contains at least solids from the waste hydrolyzed in the at least one reformer; and at least one steam generator that generates the steam using only the combustion energy of the gas produced in the microbial reactor.

2. The waste treatment system according to claim 1, further comprising an insulating steam pipe connecting the reformer and the microbial reaction device, wherein exhaust steam remaining after hydrolyzing the waste is supplied from the reformer to the microbial reaction device via the insulating steam pipe, and wherein the microbial reaction device is kept warm within a predetermined temperature range by the heat contained in the exhaust steam supplied from the reformer.

3. A waste treatment system as described in claim 1 or 2, further comprising: a drying device that dries the residue obtained after the microbial reaction device has converted the modified material into smaller molecules using microorganisms; and a drying steam pipe that connects the reforming device and the drying device, wherein exhaust steam remaining after hydrolyzing the waste is supplied from the reforming device to the drying device via the drying steam pipe, and the drying device dries the residue using the heat contained in the exhaust steam supplied from the reforming device.

4. The waste treatment system according to any one of claims 1 to 3, further comprising a separation device provided between the at least one reformer and the microbial reactor, the separation device separating unsuitable materials that are unsuitable for producing the gas in the microbial reactor from the waste hydrolyzed in the at least one reformer.

5. A waste treatment system as claimed in any one of claims 1 to 4, wherein the at least one steam generating device comprises a first steam generating device and a second steam generating device, and the steam is generated by at least one of the first steam generating device and the second steam generating device in response to a steam demand of the reformer.

6. The waste treatment system according to any one of claims 1 to 5, wherein the at least one reformer includes a plurality of reformers, and at least two of the plurality of reformers are configured to perform hydrolysis at different times from each other.

7. The waste treatment system according to claim 6, wherein the plurality of reformers include a first reformer and a second reformer, and further comprises an exhaust steam circulation pipe connecting the first reformer and the second reformer, wherein exhaust steam obtained after hydrolyzing the waste is supplied from the first reformer to the second reformer via the exhaust steam circulation pipe, and wherein the second reformer is heated by the heat of the exhaust steam supplied from the first reformer.

8. A waste treatment system according to any one of claims 1 to 7, wherein Tr is a temperature rise time required for the steam to raise the temperature inside the reformer to a preset temperature, and Tk is a maintenance time required for the steam to maintain the temperature inside the reformer at the preset temperature, and Tr / Tk ≥ 0.3 is satisfied.

9. The waste treatment system according to claim 8, wherein Tr / Tk≧1.0 is satisfied.

10. The waste treatment system according to any one of claims 1 to 9, further comprising a moisture adjusting device between the at least one reforming device and the microbial reaction device, for adjusting the moisture content of the waste hydrolyzed in the at least one reforming device.

11. The waste treatment system of claim 10, further comprising a moisture content acquisition device that acquires the amount of moisture contained in the reforming device, and the moisture adjustment device adjusts the moisture content of the waste hydrolyzed in the at least one reforming device based on the moisture content acquired by the moisture content acquisition device.

12. A waste treatment system as described in claim 11, wherein the moisture content acquisition device acquires the moisture content contained in the reformer based on the amount of steam supplied to the reformer, the duration for which the steam is supplied to the reformer, and the amount of temperature change within the reformer.

13. A waste treatment method comprising the steps of: hydrolyzing waste with steam; converting a modified product of the hydrolyzed waste, which contains at least solids, into smaller molecules using microorganisms; and generating the steam using only the combustion energy of the gas produced in the step of converting the modified product into smaller molecules using microorganisms.