JP2009034569A - Food waste, and system for recovering energy from sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy-recovering system which subjects solid sludge and food waste to methane fermentation to gain biogas at a high yield and shows a good energy balance as the whole. <P>SOLUTION: The energy-recovering system is provided with: a grinding machine 1 which grinds food waste and discharges it as slurry; a solubilizing device 2 which makes the sludge come into contact with high-temperature and high-pressure steam and discharges it as a solubilized material; a mixing tank 3 which mixes the slurry with the solubilized material and discharges it as the mixed slurry; a heat-retentive methane fermentation tank 4 which subjects the mixed slurry to methane fermentation to generate biogas and digested sludge and discharges them; a cogeneration engine 5 which uses the gained biogas as fuel to generate electricity and high-temperature and high-pressure steam; a dehydrator 6 which dehydrates the digested sludge and discharges it as the dehydrated sludge; and a drying device 7 which dries the dehydrated sludge with the high-temperature and high-pressure steam. The high-temperature and high-pressure steam generated by the cogeneration engine is fed to the solubilizing device 2, the drying device 7 and the methane fermentation tank 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention recovers energy from both food waste discarded at each stage of food production, distribution and consumption and sludge discharged from sewage treatment plants, industrial wastewater treatment plants, etc. The present invention relates to an energy recovery system for food waste and sludge produced as dry sludge that can be used as compost.

  Conventionally, most garbage and other food wastes discarded at each stage of food production, distribution and consumption have been disposed of in landfills after incineration. However, in May 2001, the “Law Concerning the Promotion of Recycling of Food Recycling Resources” (commonly called the Food Recycling Law) was enacted, and part of business-related garbage was required to be recycled. Efforts to build a recycling-oriented social system have been promoted.

  On the other hand, sludge generated from sewage treatment plants is increasing with the spread of sewerage, but most of these sludge such as sewage sludge was not used effectively and was disposed of in landfill after incineration. However, sludge is increasing year by year, and each local government spends a lot of money on its disposal, and the allowable amount at the final disposal site is decreasing and its location conditions are becoming severely restricted. The treatment of sludge has become a tight social problem.

  Therefore, with the aim of effectively recovering energy from food waste and sludge, reducing the amount, and contributing to the construction of a resource-recycling social system, studies are being conducted on biogas and composting of food waste and sludge. Has been done.

  For example, Japanese Patent Laid-Open No. 2002-326071 (Patent Document 1) pulverizes food waste into a slurry, concentrates organic sludge, mixes the slurry with a slurry tank, and circulates a slurry of food resources such as food waste. The circulated resource slurry such as food waste that has been adjusted is introduced into the bioreactor via a pulverizer, and methane fermentation is performed in the bioreactor to produce biogas and residual sludge. After desulfurizing the biogas, the gas engine Or, it is burned by a micro gas turbine to generate electric power and heat, and the residual sludge is pumped to a dehydrator at an organic waste liquid treatment facility to generate a dehydrated cake, which is discharged from a gas engine or a micro gas turbine. Discloses a recycling method and equipment for recycling food waste and other resources that are dried and reduced by heat.

  Also, there is a method of obtaining biogas by subjecting solid sludge having a low water content after dewatering treatment in a sewage treatment plant or the like (hereinafter referred to as “concentrated sludge” in this specification) to methane fermentation. For example, Japanese Patent Application Laid-Open No. 2003-103299 (Patent Document 2) discloses that a concentrated sludge is subjected to an explosion treatment, that is, a concentrated sludge is used to sufficiently ferment a concentrated sludge having a water content of 90% or less. A process of steaming in a pressure-resistant vessel for a short time with high-temperature and high-pressure steam and then suddenly releasing it under atmospheric pressure to adiabatic expansion, or supercritical water (water with a temperature of 374.1 ° C. or higher, pressure of 22.04 MPa or higher) or Concentrated sludge treatment method for methane fermentation after high-temperature and high-pressure treatment in a high-temperature and high-pressure region such as subcritical water (water at a temperature of 150 to 374 ° C. and a pressure of 2 to 22 MPa) and therefore It discloses an apparatus.

JP 2002-326071 A JP 2003-103299 A

  According to the method disclosed in Patent Document 1, energy can be recovered from both food waste and sludge that are currently incinerated in landfills, so the load on the final disposal site can be reduced, and resource circulation Can contribute to the construction of social networks. However, the solid lump concentrated sludge having a low water content after being dehydrated at a sewage treatment plant or the like is a solid lump, and the mixing step with the food waste slurry in the slurry tank and the resulting mixture Even the pulverization process in the pulverizer could not sufficiently destroy the cell walls of the microbial cells in the sludge. Therefore, the biogas conversion rate of sludge in the bioreactor is low, and there is a problem that the energy recovery rate from the sludge is not sufficient.

  On the other hand, according to the method disclosed in Patent Document 2, even if the concentrated sludge remains as a solid mass, it can be fermented with methane by blasting or treatment in a high-temperature and high-pressure region such as supercritical water or subcritical water. It is. However, this document does not describe anything about energy recovery from food waste such as garbage and the energy balance of the entire apparatus.

  Therefore, the object of the present invention is based on an energy recovery system that obtains biogas by methane fermentation using both food waste and sludge as raw materials, and is good even when concentrated sludge that is a solid lump is used as a raw material It is to provide an efficient energy recovery system that can achieve a high biogas conversion rate and exhibits a good energy balance as a whole system.

  The above-mentioned problems include a crusher that crushes food waste and discharges it as a waste slurry, a solubilizer that solubilizes sludge by contacting it with high-temperature and high-pressure steam and discharges it as a solubilizate, and the waste slurry A mixing tank that mixes the solubilized product and discharges it as a mixed slurry, a methane fermenter that is kept at a predetermined temperature that generates and discharges biogas and digested sludge by methane fermentation of the mixed slurry, and the methane fermenter A co-generation engine that generates electricity and high-temperature high-pressure steam using biogas discharged from the fuel, a dehydrator that dehydrates the digested sludge discharged from the methane fermentation tank and discharges it as dehydrated sludge, and the dehydrated sludge Equipped with a drying device that dries with high-temperature and high-pressure steam, and allows high-temperature and high-pressure steam discharged from the cogeneration engine. Food waste, characterized in that it is supplied to the saccharifier, dryer and methane fermenter and is used for the production of solubilized products, drying of dehydrated sludge, and heat retention of the methane fermenter, respectively. Achieved by energy recovery system from waste and sludge.

  In the above configuration, the high-temperature and high-pressure steam discharged from the cogeneration engine is supplied to the solubilizer, drying device, and methane fermentation tank. Used for heat insulation. Even if the sludge is supplied to the solubilizer by contacting the sludge with high-temperature and high-pressure steam in the solubilizer and releasing the treated product to atmospheric pressure, the stickiness in the concentrated sludge Since the cell walls of the substance and microbial cells are destroyed and the cytoplasm is leached, the sludge is solubilized and reduced in viscosity, and discharged from the solubilizer in a powder form. Therefore, when this powdery solubilized product and waste slurry are mixed in a mixing tank, a mixed slurry in which sludge is well dispersed is obtained, and the biogas conversion rate of sludge in the methane fermentation tank is improved. Also, by supplying high-temperature and high-pressure steam discharged from the cogeneration engine to the drying device, dewatered sludge is discharged as powdered dry sludge, and the amount of sludge can be greatly reduced. The dried sludge can be effectively used as compost. In the present invention, the high-temperature and high-pressure steam discharged from the cogeneration engine is also used for keeping the temperature of the methane fermentation tank. As a result, the temperature of the methane fermenter can be uniformly maintained at a temperature suitable for methane fermentation, so that the biogas conversion rate of food waste and sludge is increased.

  Therefore, according to the energy recovery system of the present invention, a sufficient biogas conversion rate can be achieved even when methane fermentation is performed using the concentrated sludge in a solid mass as a raw material, so that both food waste and sludge can be achieved. Thus, energy can be efficiently recovered, and an energy recovery system showing a good energy balance as a whole is constructed. According to the energy recovery system of the present invention, even if the devices included in the entire system are operated, surplus power and heat are still generated, so that surplus power and heat can be used for other purposes. In addition, the amount of sludge can be greatly reduced by drying the dewatered sludge, and the obtained dried sludge can be effectively used as compost.

  If the heat generated in the co-generation engine can be recovered as hot water in addition to high-temperature and high-pressure steam, high-temperature and high-pressure steam is supplied to the solubilizer and dryer, and hot water is supplied to the methane fermentation tank instead of steam. You may make it supply. By doing in this way, the heat generated in the cogeneration engine can be efficiently utilized in the energy recovery system of the present invention.

  On the other hand, some co-generation engines with relatively small amounts of power generation are difficult to recover the generated heat as water vapor and can only be recovered as hot water. In such a case, the energy recovery system of the present invention is further provided with an evaporator that heats the hot water discharged from the cogeneration engine and discharges it as high-temperature and high-pressure steam, and the high-temperature and high-pressure steam discharged from the evaporator Is supplied to the solubilization device and the drying device, and the hot water discharged from the co-generation engine is supplied to the methane fermentation tank, so that an efficient energy recovery system can be similarly constructed.

  The energy recovery system of the present invention is further provided with a steam boiler that generates high-temperature and high-pressure steam using a part of the biogas discharged from the methane fermentation tank as a fuel, and the remainder of the biogas is used as a fuel in the co-generation engine The water vapor discharged from the steam boiler and the water vapor discharged from the co-generation engine or the evaporation device may be combined and supplied to the solubilizer and / or the drying device. With this configuration, although the amount of power generated by the cogeneration engine is slightly reduced, high-temperature and high-pressure steam can be generated with high efficiency by the steam boiler, so efficient supply of high-temperature and high-pressure steam to the solubilizer and / or dryer Can be done well. In addition, you may make it supply the high temperature / high pressure steam obtained also to the methane fermentation tank.

  In the present invention, “high-temperature high-pressure steam” means a general co-generation engine that can be driven by methane fuel, such as a gas engine, a gas turbine, a micro gas turbine, and a methane-to-hydrogen reformer. Water vapor discharged from the fuel cell, and water vapor having a temperature and pressure equivalent to that of water vapor that can be discharged from a general steam boiler, the temperature of the “high temperature high pressure steam” is about 130 to 300 ° C., The pressure is about 0.2-5 MPa. The “predetermined temperature” at which the methane fermenter is kept warm means a temperature at which the internal methane bacterium exhibits good activity, and is about 35 to 37 ° C. when the medium temperature methane bacterium is used. When using bacteria, it is about 50-60 degreeC.

  In the energy recovery system of the present invention, the treatment in the solubilizer and / or the dryer is preferably performed under conditions of a temperature in the range of 160 to 250 ° C. and a pressure in the range of 1.5 to 3 MPa. It is preferable to continue the treatment for 5 to 1 hour. Under these conditions, a powdery solubilized product and a dried product are suitably formed.

  In the energy recovery system of the present invention, the steam discharged from the cogeneration engine or the evaporator, or the steam discharged from the cogeneration engine or the evaporator when there is a steam boiler, is discharged from the steam boiler. In addition, a temperature-rising and boosting device for raising and / or boosting the steam after the combined steam is provided, and the steam discharged from the temperature-rising and boosting device is supplied to the solubilization device and / or the drying device. Good. Fuel is required for the temperature booster, but the amount of fuel can be reduced because the water vapor introduced into the temperature booster already has a high temperature and pressure. With this configuration, it is possible to solubilize and lower the viscosity of sludge that has become a solid mass in the solubilizer, and to further promote the drying efficiency and speed of the dewatered sludge. Thus, it is possible to obtain dry sludge that is easy to use as powdery compost.

  In the configuration of the energy recovery system of the present invention, the solubilization apparatus that has completed the solubilization step can be used as a drying apparatus for drying the dewatered sludge by performing the sludge solubilization process by a batch method. That is, a single device can be switched and used as a solubilizing device and a drying device. With this configuration, the entire system can be constructed at low cost, and the operating time of one device can be increased, so that a more efficient energy recovery system can be constructed.

  According to the energy recovery system of the present invention, a sufficient biogas conversion rate can be achieved even when methane fermentation is performed using sludge in a solid mass as a raw material, and energy recovery from both food waste and sludge is achieved. The rate can be increased. In addition, the overall system exhibits a good energy balance, and it is possible to generate surplus power and heat even when the entire system of the present invention is operated.

  Hereinafter, embodiments of the energy recovery system of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

  FIG. 1 is a schematic diagram showing the configuration of a basic embodiment in the energy recovery system of the present invention.

  The system according to the present embodiment is provided with a crusher 1 for crushing and slurrying food waste and other food wastes discarded at each stage of production, distribution and consumption of food. As the crusher 1, a conventional one known to those skilled in the art can be used, and for example, a crushing / separating machine having a crushing part by a rotating blade or the like and a sorting part by a rotating screen or the like can be suitably used.

  On the other hand, for example, concentrated sludge having a water content of about 80% discharged from a sewage treatment plant is treated in the solubilizer 2. The solubilizer 2 includes a pressure-resistant container having a sludge inlet, a water vapor inlet, a solubilized product outlet after treatment, and a water vapor outlet after use. Concentrated sludge is introduced into the pressure vessel through the sludge inlet, and high-temperature and high-pressure steam supplied from a cogeneration engine, which will be described later, is introduced through the steam inlet, solubilizing the sludge by contact between the sludge and water vapor. Is going to progress. The sludge after the contact treatment with water vapor is released to the atmospheric pressure from the solubilizate discharge port and discharged as a solubilizate. On the other hand, the treated water vapor is released to atmospheric pressure from the water vapor outlet and is discharged as condensed water. The solubilizer may be a continuous device instead of the batch device as described above. The continuous system has a pressure barrel with a screw that moves the sludge from the inlet to the outlet according to a predetermined residence time. The sludge feeder supplies the concentrated sludge from the inlet to the pressure barrel. The sludge is moved to the outlet by the screw while supplying water vapor and coming into contact with the sludge, and the treated sludge is continuously released to atmospheric pressure from the continuous pressure release outlet.

  The energy recovery system according to the present embodiment further includes a mixing tank 3 for mixing the slurry of waste discharged from the crusher 1 and the solubilized product discharged from the solubilizer 2 into a mixed slurry. Have. As the mixing tank 3, a conventional tank known to those skilled in the art equipped with a stirrer can be used, and it is preferable that a dilution water supply port for adjusting the viscosity of the mixed slurry is provided.

  The mixed slurry formed in the mixing tank is processed in the methane fermentation tank 4 for a predetermined period. The methane fermentation tank 4 includes a fermentation chamber for mixing methane bacteria and a mixed slurry, and biogas after fermentation (methane: carbon dioxide = 6: 4) and digested sludge are discharged. The biogas generated by the methane fermentation is quickly taken out from the methane fermentation tank 4, processed by the desulfurizer 8, purified, and stored in the gas holder 9. The fermentation chamber preferably has a function for efficiently stirring a high-concentration reaction system. In the methane fermentation chamber, the activity of methane bacteria is maintained at a favorable temperature by high-temperature and high-pressure steam supplied from a co-generation engine described later. Mesophilic methane bacteria that are highly active in the medium temperature range have the advantage that they are more ammonia-resistant than the thermophilic methane bacteria that are highly active in the high temperature range and do not require dilution of food waste. When using fungi, the fermentation chamber is maintained at about 35-37 ° C. On the other hand, high-temperature methane bacteria have the advantage that the activity is high compared to medium-temperature methane bacteria and the fermentation chamber can be made small. When such a high-temperature methane bacterium is used, the fermentation chamber is about 50-60 ° C. Maintained.

  In the present embodiment, a co-generation engine 5 that drives biogas stored in a gas holder as fuel and converts it into electric power and heat (high-temperature high-pressure steam) is provided. As the cogeneration engine 5, a conventional engine known to those skilled in the art can be used. For example, a general gas engine, a gas turbine, a micro gas turbine, and a fuel equipped with a methane to hydrogen reformer. A battery powered engine can be used.

  On the other hand, the digested sludge discharged from the methane fermentation layer 4 is dehydrated by the dehydrator 6 and discharged as solid dehydrated sludge and desorbed liquid (water). As the dehydrator 6, a conventional dehydrator such as a centrifugal separation type, a belt press type, or a screw press type can be used. Further, the energy recovery system of the present embodiment has a drying device 7 for producing solid dehydrated sludge as powdered dry sludge. The configuration of the drying device 7 is basically the same as that of the solubilizing device 2 described above.

  The energy recovery system of the present embodiment having the above-described configuration operates as follows.

  Food waste such as garbage with a water content of about 80% is put into the crusher 1 to be slurried, separated from foreign matters such as plastic and plastic bags, and discharged as waste slurry. On the other hand, concentrated sludge having a water content of about 80%, such as a sewage treatment plant, is charged into the solubilizer 2 and mixed with high-temperature and high-pressure steam (solubilized steam) supplied from the cogeneration engine 5 in a pressure vessel. In the case of a batch method, it is processed at a predetermined temperature, preferably 160 to 250 ° C., and a predetermined pressure, preferably 1.5 to 3 MPa, for a predetermined time, preferably 0.5 to 1 hour, or a continuous method. It is processed by. During this time, sludge solubilization proceeds. The treated water vapor is released to atmospheric pressure and recovered as condensed water, and used as dilution water for adjusting the mixed slurry in the following mixing tank 3. The treated sludge is discharged as a powder solubilizate having a water content of about 55% and transferred to the mixing tank 3.

  In the mixing tank 3, the powdered lysate transferred from the solubilizer 2 is mixed with the waste slurry and dilution water discharged from the pulverizer 1 to form a mixed slurry having a water content of about 90%. . At this time, condensed water or desorbed liquid recovered from the above-described solubilizer 2, dehydrator 6, and dryer 7 is used as the dilution water.

  The mixed slurry is transferred to a methane fermentation tank 4 maintained at a predetermined temperature by high-temperature and high-pressure steam (heated steam) discharged from the co-generation engine 5, and in a fermentation chamber for a predetermined period, preferably 5 to 5 by the action of methane bacteria. Fermented for 15 days. The generated biogas is quickly recovered, temporarily stored in the gas holder 9 via the desulfurizer 8 and supplied as fuel for the cogeneration engine 5, and the heat from the cogeneration engine 5 in the form of electric power and high-temperature high-pressure steam. Is discharged. A part of the generated high-temperature and high-pressure steam is supplied to the solubilizer 2, the drying device 7, and the methane fermentation tank 3, and a part of the electric power drives each device included in the energy recovery system of the present embodiment. Supplied for.

  On the other hand, the digested sludge having a water content of about 96% discharged from the methane fermentation tank 4 is transferred to the dehydrator 6 and dehydrated, and discharged as a solid dehydrated sludge having a water content of about 80% and a desorbed liquid (water). Is done. Part of the detachment liquid is used as dilution water for preparing the mixed slurry, and the remainder is discharged into the sewer. The dewatered sludge is supplied to the drying device 7 and mixed with high-temperature and high-pressure steam (dry steam) supplied from the cogeneration engine 5 in a pressure-resistant container, and has a predetermined temperature, preferably 160 to 250 ° C., a predetermined pressure, 1 In the batch method, it is processed for a predetermined time, preferably 0.5 to 1 hour, under a condition of 0.5 to 3 MPa, or by a continuous method. During this time, the solid dewatered sludge changes its shape to a powder and is discharged as a dry sludge having a water content of about 20%. The treated water vapor is released to atmospheric pressure, recovered as condensed water, and used as dilution water for preparing the mixed slurry in the mixing tank 3.

  According to the energy recovery system of the present embodiment, it is possible to increase the energy recovery rate from both food waste and sludge, and to obtain a good energy balance as a whole system.

  FIG. 2 shows a configuration of a form obtained by modifying the above-described basic embodiment. Only different points will be described below.

  The energy recovery system of the embodiment shown in FIG. 2 is a steam boiler that generates high-temperature and high-pressure steam by using a part of biogas recovered from the methane fermentation tank 4 and stored in the gas holder 9 via the desulfurizer 8 as fuel. 10 This embodiment is used when the amount of high-temperature and high-pressure steam is insufficient. For example, the steam boiler 10 generates high-temperature and high-pressure steam having about twice as much heat as fuel by using the same amount of biogas as compared with a gas engine type engine used as the co-generation engine 5. In particular, it is used effectively.

  In the present embodiment, the high-temperature and high-pressure steam discharged from the steam boiler 10 is combined with the high-temperature and high-pressure steam discharged from the cogeneration engine 5 and further supplied to the solubilizer 2 and the drying device 7 before being supplied to the solubilizer 2 and the drying device 7. Is supplied to the temperature raising and boosting machine 11 for raising the temperature and / or raising the pressure. As the temperature raising and boosting device 11, a conventional one can be used, and for example, a once-through boiler can be used. By means of the temperature raising pressure booster 11, for example, 0.5 to 1.0 MPa of water vapor from the cogeneration engine 5 and the steam boiler 8 is boosted to a pressure suitable for solubilization and drying, for example, about 1.8 MPa. And supplied to the solubilizing device 2 or the drying device 7. With this configuration, the solubilization process and the drying process are further smoothly advanced.

  FIG. 3 shows a configuration of an embodiment in which further changes are added to the configuration shown in FIG. Only different points will be described below.

  By performing the sludge solubilization treatment by the batch method, the solubilization apparatus that has completed the solubilization step can be used as a drying apparatus for drying the dewatered sludge. The energy recovery system of the embodiment shown in FIG. 3 is configured to be usable as the solubilizer 2 or the drying device 7 by switching one device. The solubilizer 2 is used as the drying device 7 after discharging the solubilizate. With this configuration, an expensive device can be operated effectively.

  FIG. 4 shows a configuration of an embodiment using a different co-generation engine in the basic embodiment shown in FIG. Only different points will be described below.

  In the embodiment shown in FIG. 4, the co-generation engine in which the biogas recovered from the methane fermentation tank 4 and stored in the gas holder 9 via the desulfurizer 8 generates hot water in addition to electric power and high-temperature high-pressure steam. 5 is used as fuel. The discharged high-temperature and high-pressure steam is supplied to the solubilizer 2 and the drying device 7, and the discharged hot water is supplied to the methane fermentation tank 4 and used to keep the tank 4 warm. With this configuration, the heat generated from the cogeneration engine 5 is used efficiently.

  FIG. 5 shows a configuration of an embodiment in which another co-generation engine is used in the basic embodiment shown in FIG. Only different points will be described below.

  In the energy recovery system of the embodiment shown in FIG. 5, the biogas recovered from the methane fermentation tank 4 and stored in the gas holder 9 via the desulfurizer 8 generates electric power and hot water, and generates high-temperature and high-pressure steam. It is used as fuel in the cogeneration engine 5 that does not. Then, a part of the discharged hot water is supplied to the methane fermentation tank 4 and used to keep the tank 4 warm. On the other hand, the energy recovery system of this embodiment includes an evaporator 12 that warms the hot water discharged from the cogeneration engine 5 and generates high-temperature and high-pressure steam. The evaporator 12 is not particularly limited as long as it can heat hot water and convert it into high-temperature and high-pressure steam. For example, a once-through boiler can be used. In the present embodiment, the high-temperature and high-pressure steam discharged from the evaporator 12 is supplied to the solubilizer 2 and the drying device 7. With this configuration, the hot water generated from the cogeneration engine 5 is efficiently used.

  FIG. 6 shows an energy balance of the embodiment having the configuration shown in FIG. 3 except that a gas engine type engine 5 ′ is used as a co-generation engine. In addition, this invention is not limited to the following Examples, Numerical values, such as the processing amount of a food waste and a sewage sludge, the capacity | capacitance of a methane fermenter, are only an example to the last.

In the examples, raw waste with a water content of 80% is crushed at a rate of 17 t (tons) per day, and concentrated sludge with a water content of 80% at a sewage treatment plant is solubilized at a rate of 15 t per day, Fermented for 10 days in a methane fermenter. CODcr (COD measured with potassium dichromate) of raw garbage (water content 80%) is 320 kg / wet-t, garbage decomposition rate is 80%, CODcr of sewage sludge is 240 kg / wet-t, sludge decomposition rate is It was 70% (organic decomposition rate 80%). The solubilization of the concentrated sludge and the drying of the dewatered sludge were performed by supplying water vapor at 210 ° C. and 1.8 MPa and switching one apparatus. Biogas was obtained at a rate of 2890 m ³ N per day, and 2.9 t of dry sludge was collected per day. The dried sludge was effectively used as compost.

The amount of heat (high temperature and high pressure steam) generated from the steam boiler 8 and the gas engine type engine 5 ′ is 9.2 × 10 ⁶ kcal per day, and the amount of heat (high temperature and high pressure) for solubilization, drying, and methane fermenter. Water vapor) was 7.8 × 10 ⁶ kcal, and excess heat was recovered. On the other hand, a power of 150 kW per day was obtained from the gas engine type engine 5 ′, a part was used for driving the system, and the rest was sold.

  In addition, when the sewage sludge was directly charged into the mixing tank without using the solubilizer 2 and the mixed slurry was charged into the methane fermentation tank 4 through a pulverizer, the organic decomposition rate of the sludge was 40 to 50%. It was. It was found that effective energy recovery from sludge and reduction of digested sludge were achieved by the present invention.

It is the schematic which showed the fundamental embodiment structure in the energy recovery system of this invention. It is the schematic which showed the structure of another embodiment in the energy recovery system of this invention. It is the schematic which showed the structure of another form in the energy recovery system of this invention. It is the schematic which showed the structure of further another embodiment in the energy recovery system of this invention. It is the schematic which showed the structure of another form in the energy recovery system of this invention. It is the figure explaining the energy balance in the energy recovery system of the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crusher 1 'Crush fractionator 2 Solubilizer 3 Mixing tank 4 Methane fermentation tank 5 Co-generation engine 5' Gas engine type engine 6 Dehydrator 7 Dryer 8 Desulfurizer 9 Gas holder 10 Steam boiler 11 Temperature booster 12 Evaporator

Claims (9)

Crusher that crushes food waste and discharges it as waste slurry,
A solubilizer that solubilizes sludge by contacting it with high-temperature high-pressure steam and discharges it as a solubilizate,
A mixing tank for mixing the waste slurry and the solubilized product and discharging it as a mixed slurry;
A methane fermentation tank kept at a predetermined temperature for producing and discharging biogas and digested sludge by methane fermentation of the mixed slurry,
A co-generation engine that generates electric power and high-temperature and high-pressure steam using the biogas discharged from the methane fermentation tank as fuel,
A dehydrator for dewatering the digested sludge discharged from the methane fermentation tank and discharging it as dehydrated sludge; and
A drying device for drying the dewatered sludge with high-temperature and high-pressure steam;
And
The high-temperature and high-pressure steam discharged from the cogeneration engine is supplied to the solubilizer, dryer and methane fermenter, and used to generate solubilizate, dry dehydrated sludge, and keep the methane fermenter warm. An energy recovery system from food waste and sludge, characterized in that Crusher that crushes food waste and discharges it as waste slurry,
A solubilizer that solubilizes sludge by contacting it with high-temperature high-pressure steam and discharges it as a solubilizate,
A mixing tank for mixing the waste slurry and the solubilized product and discharging it as a mixed slurry;
A methane fermentation tank kept at a predetermined temperature for producing and discharging biogas and digested sludge by methane fermentation of the mixed slurry,
A co-generation engine that generates electricity, high-temperature and high-pressure steam, and hot water using the biogas discharged from the methane fermenter as fuel,
A dehydrator for dewatering the digested sludge discharged from the methane fermentation tank and discharging it as dehydrated sludge; and
A drying device for drying the dewatered sludge with high-temperature and high-pressure steam;
And
The high-temperature and high-pressure steam discharged from the co-generation engine is supplied to the solubilizer and dryer, and hot water is supplied to the methane fermentation tank, where the solubilized product is produced, the dehydrated sludge is dried, and the methane fermentation tank is kept warm. Energy recovery system from food waste and sludge, characterized in that it is used for Crusher that crushes food waste and discharges it as waste slurry,
A solubilizer that solubilizes sludge by contacting it with high-temperature high-pressure steam and discharges it as a solubilizate,
A mixing tank for mixing the waste slurry and the solubilized product and discharging it as a mixed slurry;
A methane fermentation tank kept at a predetermined temperature for producing and discharging biogas and digested sludge by methane fermentation of the mixed slurry,
A co-generation engine that generates electricity and hot water using the biogas discharged from the methane fermentation tank as fuel,
An evaporator that heats the hot water discharged from the co-generation engine and discharges it as high-temperature and high-pressure steam;
A dehydrator for dewatering the digested sludge discharged from the methane fermentation tank and discharging it as dehydrated sludge; and
A drying device for drying the dewatered sludge with high-temperature and high-pressure steam;
And
The high-temperature and high-pressure steam discharged from the evaporator is supplied to a solubilizer and a drying device, and the hot water discharged from the cogeneration engine is supplied to a methane fermentation tank. Energy recovery system from food waste and sludge, characterized in that it is intended to be used for drying and heat insulation of methane fermenters. The energy recovery system further includes a steam boiler that generates high-temperature and high-pressure steam by using a part of the biogas discharged from the methane fermentation tank as a fuel,
The remainder of the biogas is used as fuel in the cogeneration engine,
The steam discharged from the steam boiler and the steam discharged from the cogeneration engine or the evaporator are combined and supplied to the solubilizer and / or the drying device. 4. The energy recovery system according to any one of items 3. The steam recovered by the energy recovery system is further discharged from the co-generation engine or evaporator, or, if a steam boiler is present, the steam discharged from the steam boiler into the steam discharged from the co-generation engine or evaporator. Is equipped with a temperature raising and boosting device for raising and / or raising the pressure of water vapor after being combined,
The energy recovery system according to any one of claims 1 to 4, wherein water vapor discharged from the temperature raising pressure booster is supplied to a solubilizing device and / or a drying device.   The treatment in the solubilizer and / or the drying device is performed under conditions of a temperature in the range of 160 to 250 ° C and a pressure in the range of 1.5 to 3 MPa. The energy recovery system according to item.   The energy recovery system according to any one of claims 1 to 6, wherein the treatment in the solubilizing device and / or the drying device is performed for 0.5 to 1 hour.   The energy recovery system according to any one of claims 1 to 7, wherein one device is switched to be used as a solubilizer and a dryer.   The electricity discharged from the co-generation engine is used to grind, solubilize, mix tank, methane fermenter, dehydrator, dryer and, if present, evaporator, steam boiler, and temperature booster The energy recovery system according to claim 1, wherein the energy recovery system is driven.

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