JP2015131263A - Organic waste processor, dryer for use in organic waste processor, and processing method of organic waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic waste processor having reduced loss of effective energy, which heats a digestion tank with dry exhaust gas from drying of dehydrated sludge, without requiring a cyclone (separation of dried sludge from dry exhaust gas) or a dehumidifier (recovery of condensation heat of steam).SOLUTION: The processor includes: a digestion tank 1 which generates a digestion gas B through fermentation of an organic waste A by heating; a digestion gas power generator 2 which generates power by firing the digestion gas B; a dehydrator 3 which dehydrates a digestion sludge D discharged from the digestion tank 1; and a dryer 4 which dries a dehydrated sludge E from the dehydrator 3. The dryer 4 is an indirect heating type dryer which indirectly heats and dries the dehydrated sludge E with a combustion exhaust gas C generated by firing the digestion gas B at the digestion gas power generator 2. The organic waste A in the digestion tank 1 is heated with a dry exhaust gas H generated at the dryer 4.

Description

  The present invention is an organic waste treatment apparatus for dewatering and drying as digested sludge by heating and fermenting organic waste such as sewage sludge, food waste, dust, and manure in a digestion tank, The present invention relates to a dryer used in such an organic waste processing apparatus, and an organic waste processing method.

  As such an organic waste treatment apparatus, for example, in a sewage sludge treatment digestion facility, it is necessary to heat the organic waste to a certain temperature in order to ferment the organic waste in the digestion tank. The temperature at this time is most often moderately digested at 30 to 40 ° C. For this reason, it is necessary to apply heat from the input sludge and digestion tank heat to the digestion tank. Conventionally, a boiler for heating is installed and the digestion gas generated in the digestion tank is used as fuel. When the digester is heated by steam, or when digestion gas power generation equipment or incineration equipment is adjacent, the digestion tank is heated using the waste heat.

  However, fossil fuel and digestion gas, which are chemical energies, have high effective energy efficiency and should be converted into energy such as electric power with the same effective energy efficiency, and the boiler burns fossil fuel and digestion gas, It is not desirable from the viewpoint of energy efficiency to use the generated steam for heating a relatively low temperature digester. In addition, waste heat (exhaust gas) from digestion gas power generation equipment and incineration equipment is also high temperature, and it is desirable to use it as a heat source for drying sludge discharged from the digestion tank rather than heating the digestion tank. However, if the waste heat of the digestion gas power generation facility is used for both the drying heat source for such sludge and the heat source for heating the digestion tank, the amount of heat is insufficient.

  Therefore, in such an organic waste treatment apparatus and treatment method, for example, in Patent Document 1, as a treatment method for waste disposer wastewater, the waste disposer wastewater is introduced into the digestion tank together with the initial settling sludge and methane fermentation. Dehydrated sludge that has been treated and dehydrated digested sludge from the digester is dried with a dryer, and the dry exhaust gas from the dryer is used to heat the digester, and gas power is generated using the digested gas generated in the digester It has been proposed to use the waste heat generated by the gas power generation as a heat source for the dryer.

JP 2004-066094 A

  By the way, in the processing apparatus and the processing method described in Patent Document 1, as a dryer for drying dehydrated sludge, a crusher that dries a mixture of dehydrated sludge and circulating dry sludge while bringing it into contact with hot air while crushing the mixture. And a direct heating type air dryer equipped with an air current conveying line for drying the crushed dried sludge while bringing it in air current contact with hot air. The dried exhaust gas discharged from the air dryer is separated into dry sludge powder by a cyclone and supplied to the dehumidifier as dry exhaust air. The dehumidified air dehumidified by the dehumidifier is a generator that performs gas power generation. And also used as hot air for the above-mentioned air dryer, which is a heat source for the dryer as described above, after being heated and heated with the combustion exhaust gas generated by this gas power generation, Water vapor contained in the dry exhaust air and removed by dehumidification is used for heating the digester.

  However, in the organic waste processing apparatus and processing method described in Patent Document 1, a cyclone and a dehumidifier are required to use the dry exhaust gas discharged from the air dryer for heating the digestion tank. It becomes. In addition, in order to heat the digester efficiently, if dry exhaust air is supplied directly into the digester and the initial sludge or garbage disposer wastewater is heated, a lot of dehumidified air (dry gas) ) Is also inevitable to be supplied to the digestion tank, so the methane concentration of the digestion gas supplied to the gas generator will decrease, making it difficult to perform efficient power generation. Since the temperature of the generated combustion exhaust gas is also reduced, reliable drying of the dewatered sludge in the air dryer is hindered.

  The present invention has been made under such a background, reducing the loss of effective energy, and heating the digestion tank with dry exhaust gas obtained by drying dewatered sludge without requiring a cyclone or a dehumidifier. It is a first object of the present invention to provide a possible organic waste treatment apparatus, a dryer used in the organic waste treatment apparatus, and a method for treating organic waste, and thus the dried exhaust gas is used in the digester. Organic waste treatment equipment capable of efficient digestion gas power generation and reliable drying of dewatered sludge even when used for heating, dryers used in organic waste treatment equipment, and organic waste The second object is to provide a processing method.

  In order to solve such problems and achieve the first object, the organic waste processing apparatus of the present invention generates digestion gas by heating and fermenting the organic waste. Digestion tank, digestion gas generator that generates electricity by burning digestion gas generated in this digestion tank, dehydrator that dehydrates digested sludge discharged from the digestion tank, and dewatered sludge dehydrated in this dehydrator The dryer is an indirect heating type dryer that indirectly heats and dehydrates the dewatered sludge with combustion exhaust gas obtained by burning the digestion gas in the digestion gas generator, The organic waste is heated in the digestion tank by a dry exhaust gas generated by drying the dewatered sludge in the indirect heating dryer.

  The dryer of the present invention is a digester tank that generates digestion gas by heating and fermenting organic waste, and digestion gas power generation that generates power by burning the digestion gas generated in the digester tank. Used in an organic waste processing apparatus comprising: a dehydrator for dewatering the digested sludge discharged from the digestion tank; and a dryer for heating and drying the dewatered sludge dehydrated in the dehydrator A rotatable cylindrical body into which the dehydrated sludge is supplied, a heating path provided inside or outside the cylindrical body, and a carrier gas to the inside of the cylindrical body A carrier gas supply port, and a dry exhaust gas exhaust port for discharging the dry exhaust gas generated by drying the dewatered sludge inside the cylindrical body together with the carrier gas. The combustion exhaust gas combusted in the digestion gas is supplied, and the dehydrated sludge is indirectly heated and dried, and the dry exhaust gas discharge port is connected to the digestion tank and discharged together with the carrier gas. The organic waste is heated in the digester with dry exhaust gas.

  Furthermore, the organic waste processing method of the present invention generates digestion gas by heating and fermenting organic waste in a digestion tank, and generating power by burning the digestion gas in a digestion gas generator. In addition, the digested sludge discharged from the digester is dehydrated in a dehydrator, and the dehydrated sludge dehydrated in the dewaterer is indirectly heated by the combustion exhaust gas obtained by burning the digested gas in the digester gas generator. Indirect heating by a dryer, drying the dehydrated sludge in the indirectly heated dryer, supplying the exhaust gas generated to the digester and heating the organic waste It is characterized by.

  In such an organic waste processing apparatus and processing method, the digestion tank is heated by the latent heat of water vapor in the dry exhaust gas, so the amount of other heat sources such as fossil fuel used is reduced or unnecessary. be able to. Furthermore, the waste heat from the combustion exhaust gas from the digestion gas generator is first used as a drying heat source for the dryer, and then the waste heat from the drying exhaust gas from the dryer is used stepwise as a heating heat source for the digester. The effective energy can be efficiently used from the high temperature heat source to the low temperature heat source. In addition, since the high-temperature waste heat from the digestion gas generator is first used as the heat source of the dryer, an increase in the heat transfer area and residence time in the dryer can be suppressed.

  In the organic waste processing apparatus and processing method configured as described above, the dewatered sludge obtained by dewatering the digested sludge is not a direct heating dryer such as the air dryer described in Patent Document 1, but indirectly heated. It is heated indirectly by the combustion exhaust gas of the digestion gas generator and dried in the type dryer. As an indirect heating type dryer, a rotatable tubular body like the dryer of the present invention, a steam tube dryer in which a plurality of heating pipes are arranged as heating paths inside the tubular body, and the same rotatable A horizontal indirect heating dryer such as an external heat kiln having a cylindrical body and a casing that covers the outer periphery of the cylindrical body and forming a heating path through which a heating medium flows between the cylindrical body and the casing. In such an indirect heating type dryer, dry sludge powder is rarely mixed into the dry exhaust gas discharged from the dry exhaust gas outlet, and the dry sludge powder is separated like an air dryer. There is no need for a cyclone. Moreover, since most of the dry exhaust gas discharged from the indirect heating dryer is water vapor evaporated from dehydrated sludge, the dehumidifier can be adjusted by appropriately adjusting the amount of carrier gas supplied from the carrier gas supply port. It is no longer necessary to separate water vapor and air using the.

  Furthermore, since most of the dry exhaust gas discharged from the indirectly heated dryer is water vapor, even if this dry exhaust gas is blown directly into the digestion tank and the organic waste in the digestion tank is heated, the digestion gas There is no decrease in the methane concentration. Therefore, it is possible to perform efficient digestion gas power generation in the digestion gas generator, and the dehydrated sludge can be surely dried by the combustion exhaust gas generated by the digestion gas generator, and the second object is achieved. Can be achieved. Moreover, it is possible to prevent the odor components in the dry exhaust gas from being released to the outside by directly blowing the dry exhaust gas from the dehydrated sludge into the digestion tank. However, the organic waste may be indirectly heated by supplying it to a heat exchanger attached to the digestion tank without blowing directly into the dry exhaust gas. Further, if dehydrated sludge is heated with hot water generated in the digestion gas generator and supplied to the indirect heating dryer, more reliable drying can be performed.

  In the organic waste treatment method of the present invention, the solid waste concentration of the organic waste supplied to the digester is in the range of 2 wt% to 4 wt%, and the solid waste of the organic waste The digestion gas is generated with the organic substance concentration in the range of 80 wt% to 99 wt%, and the digestion gas is burned in the digestion gas generator having a power generation efficiency in the range of 20% to 35% and discharged from the digestion tank. The above-mentioned digested sludge is dehydrated in the dehydrator to a moisture content in the range of 60 wt% to 75 wt% and dried by the indirect heating dryer, so that external energy such as fossil fuel is required as in the balance example described later. Instead, drying in the dryer and heating of the digestion tank can be performed only with the digestion gas generated in the digestion tank.

  As described above, according to the present invention, without requiring a cyclone or a dehumidifier, dehydrated sludge is dried in an indirect heating dryer, and the organic waste in the digester is heated by the dried exhaust gas. And effective utilization of effective energy can be achieved. In addition, even if organic waste is heated by blowing dry exhaust gas directly into the digestion tank, the digestion gas methane concentration does not decrease, and efficient digestion gas power generation and reliable dewatering of sludge are performed. Can do.

It is the schematic which shows the 1st Embodiment of this invention. It is a figure which shows the 1st example of the heat balance in 1st Embodiment. It is a figure which shows the 2nd example of the heat balance in 1st Embodiment. It is a figure which shows the 3rd example of the heat balance in 1st Embodiment. It is the schematic which shows the 2nd Embodiment of this invention. It is the schematic which shows the 3rd Embodiment of this invention.

  FIG. 1 is a schematic view showing a first embodiment of the organic waste processing apparatus of the present invention. The organic waste of the present invention will be described below while explaining the processing apparatus of the first embodiment. An embodiment of this processing method will also be described. In the present embodiment, the concentrated sludge A discharged from the sewage treatment plant as the organic waste to be treated is supplied to the digestion tank 1, digested by methane fermentation while being heated in the digestion tank 1, and digested gas (Methane gas) B is generated.

  This digested gas B is supplied to the digested gas generator 2 and burned to generate power and generate a high-temperature combustion exhaust gas C of about 470 ° C to 600 ° C. For example, a gas engine or a gas turbine can be used as the digestion gas generator. Although it depends on the type of digestion gas generator 2, a generator having a power generation efficiency of 20% to 35% is preferable. If the power generation efficiency is higher than 35%, the exhaust gas temperature becomes low, and there is a possibility that a heat source necessary for the dryer cannot be secured. In addition, the generated power can be used as a power source for various devices of the processing apparatus such as a dehydrator and a dryer, which will be described below, and as a power source other than that. The digestion gas generator 2 also discharges hot water generated by the combustion of digestion gas B.

  The digestion tank 1 is supplied with the concentrated sludge A in which the solid matter concentration (TS) is adjusted to 2 wt% to 4 wt% and the organic content in the solid matter is adjusted to 80 wt% to 86 wt%. If the solid matter concentration is less than 2 wt%, the large digester 1 is required, so that the amount of heat release increases and a large amount of heat is required to maintain the digestion temperature. On the other hand, if the solid concentration is higher than 4 wt%, the viscosity of the concentrated sludge A becomes high, a large amount of power is required for stirring the concentrated sludge A, and an area where stirring cannot be performed occurs depending on the situation. In addition, biomass such as garbage can be mixed in the concentrated sludge A in advance, and the organic content concentration in the solid matter in this case may be adjusted to 80 wt% to 99 wt%. The concentrated sludge A supplied to the digester 1 is decomposed by anaerobic fermentation while being maintained at about 30 ° C. to 40 ° C., and generates digested gas B containing methane.

  Further, the digested sludge D extracted from the digester tank 1 as the digested residue of the concentrated sludge A is dehydrated by the dehydrator 3 to a moisture content of 60 wt% to 75 wt%, and dehydrated sludge E from which moisture has been removed to a certain extent. 4 is dried. As the dehydrator 3, a centrifugal dehydrator, a belt press, or the like can be used. In addition, in the digested sludge D extracted from the digestion tank 1, the organic substance of biodegradability may be contained undigested.

  As the dryer 4, an indirect heating type dryer such as a steam tube dryer or an external heat kiln in which the dehydrated sludge E that is an object to be dried and the heating medium are not in direct contact is used. Among these, the steam tube dryer is a hollow cylindrical body mainly having a cylindrical shape centered on the axis that is rotatably supported around a horizontal axis, and a heating path is arranged inside the cylindrical body. And a plurality of heating tubes provided. One end (left end in FIG. 1) of the cylindrical body is provided with a supply port for supplying dehydrated sludge E into the cylindrical body and a dry exhaust gas discharge port, and the other end (right end in FIG. 1). Are provided with a discharge port for dried sludge F obtained by drying dewatered sludge E and a carrier gas supply port. Further, the external heat kiln is composed of a hollow cylindrical body that is mainly cylindrical and centered on the axis that is supported so as to be rotatable around a horizontal axis, and a casing that covers the outer periphery of the cylindrical body. A heating path through which the heating medium flows is formed between the cylindrical body and the casing. Further, similarly to the steam tube dryer, a dehydrated sludge E supply port and a dry exhaust gas discharge port are provided at one end of the cylindrical body, and a dry sludge F discharge port and a carrier gas supply port are provided at the other end.

  Further, the dryer 4 is supplied with the combustion exhaust gas C discharged from the digestion gas generator 2 as the heating medium to the heating path to indirectly heat the dewatered sludge E supplied into the cylindrical body. And dry. Further, in order to discharge water vapor generated when the dewatered sludge E supplied to the dryer 4 is dried to the outside from the dryer 4, a carrier gas is supplied to the dryer 4 from the carrier gas supply port. As the carrier gas, various gases such as air, carbon dioxide, and nitrogen can be used, but it is preferable to use a gas having as little oxygen as possible, such as exhaust gas from combustion equipment such as an incinerator or a boiler. The dried sludge is discharged from the dryer 4 as a dried sludge F, and the combustion exhaust gas C heated from the dewatered sludge E is discharged from the dryer 4 for processing. The moisture content of the dried sludge F discharged from the indirectly heated dryer 4 is 1 wt% to 45 wt%. When it is 50 wt% or more, the dried sludge F adheres to the indirect heating type dryer 4 or is agglomerated, which makes handling difficult.

  On the other hand, from the dryer 4, the dried exhaust gas H mainly having a water vapor evaporated when the dewatered sludge E is dried is at least 100 ° C., preferably about 120 ° C. to 260 ° C., is discharged from the dried exhaust gas outlet. . This dry exhaust gas H contains the carrier gas supplied from the carrier gas supply port together with the water vapor. And this dry waste gas H is supplied to the said digestion tank 1, and is used for the heating of the concentrated sludge A hold | maintained in this digestion tank 1. FIG. Furthermore, in this embodiment, the concentrated sludge A in the digestion tank 1 is heated to about 30 ° C. to 40 ° C. by directly blowing this dry exhaust gas H into the digestion tank 1.

  Thus, in the organic waste processing apparatus, the dryer 4 and the organic waste processing method configured as described above, the high-temperature combustion exhaust gas C generated in the digestion gas generator 2 is dehydrated sludge E in the dryer 4. The dried exhaust gas H generated in the dryer 4 and having a temperature lower than the combustion exhaust gas C is used for heating the concentrated sludge (organic waste) A in the digestion tank 1. That is, since the heat source generated by burning the digestion gas B in the digestion gas generator 2 can be used step by step, the digest gas B can be efficiently used with less effective energy loss.

  For this reason, most or all of the amount of heat required for drying the dewatered sludge E in the dryer 4 and heating the concentrated sludge A in the digester 1 is covered by the waste heat of the combustion exhaust gas C generated in the digestion gas generator 2. Therefore, the amount of other heat sources such as fossil fuel used for drying and heating can be greatly reduced or eliminated. Moreover, since the waste heat of the high-temperature combustion exhaust gas C of the digestion gas generator 2 is first used as the heat source of the dryer 4, an increase in heat transfer area and residence time in the dryer 4 can also be suppressed.

Here, FIG. 2 shows the 1st example of the heat balance at the time of processing the concentrated sludge A using the processing apparatus and processing method of 1st Embodiment. All percentages (%) are weight% (wt%). In this first example, a solid matter concentration (TS) of 2.7 wt%, an organic content in the solid matter of 80 wt%, and a concentrated sludge A at a temperature of 20 ° C. are supplied to the digester 1 at 740 m ³ / day, By being heated and held, it is digested and methane-fermented, and digestion gas (methane gas) B having a methane concentration of 60% and a calorific value of 2180 kJ / sec is generated at 8800 m ³ N / day. The digested gas B is burned in the digested gas generator 2 to generate 600 kW of electric power and generate combustion exhaust gas C having a temperature of 510 ° C. and a calorific value of 1220 kJ / sec.

In addition, the digested sludge D having a concentration of 1.6 wt% is extracted from the digester 1 at 740 m ³ / day, dehydrated by the dehydrator 3, and dehydrated sludge E having a moisture content of 75 wt% is dried by indirect heating at 50 t / day. Supplied to the machine 4. In the dryer 4, the dewatered sludge E is dried using the combustion exhaust gas C as a heat medium, and is discharged at a rate of 20.7 t / day as a dry sludge F having a water content of 40 wt% and a temperature of about 100 ° C. C is cooled to a temperature of 80 ° C., discharged as exhaust gas G at 5920 kg / hour, and processed.

  On the other hand, the water evaporated by drying the dewatered sludge E in the dryer 4 is discharged at 1340 kg / hour as dry exhaust gas H mainly composed of water vapor at a temperature of 120 ° C. and a calorie of 920 kJ / sec and directly blown into the digester 1. The concentrated sludge A supplied and held in the digester 1 is heated. The heat required for heating the concentrated sludge A in the digestion tank 1 is 790 kJ / sec and can be covered by the heat of the dry exhaust gas H, so fossil fuel is required for heating in the digestion tank 1 and drying in the dryer 4. And never.

  Moreover, FIG. 3 shows the 2nd example of the heat balance at the time of processing concentrated sludge A using the processing apparatus and processing method of 1st Embodiment, and compared with a 1st example, in dehydrator 3 The case where the dewatering performance was made high and the water | moisture content and discharge | emission amount of dewatered sludge E were reduced is shown. In this second example, the heat balance, discharge amount (supply amount) of the concentrated sludge A, digestion gas B, combustion exhaust gas C, and digestion sludge D, and the power generation amount in the digestion gas generator 2 are the same as in the first example. It is.

  That is, in this second example, dehydrated sludge E having a water content of 70 wt% is supplied from the dehydrator 3 to the dryer 4 at 50 t / day, and is dried by the combustion exhaust gas C in this dryer 4. The dried sludge F at a temperature of about 100 ° C. is discharged at a reduced discharge amount of 13.3 t / day than the first example and is processed with the reduced 10 wt% moisture. Further, the combustion exhaust gas C is cooled and discharged with the same discharge amount as in the first example, and is processed.

  When the dewatering performance in the dehydrator 3 is increased and the moisture and discharge amount of the dewatered sludge E are thus reduced, the discharge amount of the dry exhaust gas H discharged from the dryer 4 is also reduced. Since there is a margin in the amount of heat, in this second example, the temperature of the dry exhaust gas H can be increased to cover the heating required heat amount 790 kJ / sec in the digestion tank 1. In the second example, the concentrated sludge A is heated by blowing dry exhaust gas H having a temperature of 240 ° C. and a heat quantity of 920 kJ / sec directly into the digestion tank 1 at 1220 kg / hour.

  Therefore, also in this 2nd example, the process of the concentrated sludge A can be performed, without requiring fossil fuel etc. for the heating of the digester 1, and the drying of the dryer 4 similarly to the 1st example. Moreover, since the water | moisture content and discharge | emission amount of the dry sludge F are reduced, the process can be made easy. Instead of improving the dewatering performance in the dehydrator 3, for example, as in a second embodiment described later, a preheater is provided between the dehydrator 3 and the dryer 4, and the digester gas generator 2 You may make it improve drying performance by utilizing the waste heat of the generated warm water.

Furthermore, FIG. 4 shows the 3rd example of the heat balance at the time of processing the concentrated sludge A using the processing apparatus and processing method of 1st Embodiment, and compared with a 1st example, it is in the digester 1 The case where the organic content of the supplied concentrated sludge A becomes high is shown. That is, in this third example, the concentration and the supply amount of the concentrated sludge A are the same as in the first example, but the organic content is as high as 85 wt%. Although the methane concentration is the same as that in the first example, the amount of heat is increased to 2320 kJ / sec and the generated amount is 9350 m ³ N / day.

  Therefore, by burning such digestion gas B, the combustion exhaust gas C supplied from the digestion gas generator 2 to the dryer also increases the heat amount 1290 kJ / sec and the supply amount 6283 kg / hour from the first example. Moreover, the power generation amount in the digestion gas generator 2 is 695 kW, which is larger than those in the first and second examples. On the other hand, the digested sludge D discharged from the digester 1 has a slightly reduced concentration of 1.55 wt% due to the higher organic content of the concentrated sludge A, and the dehydrated sludge E supplied from the dehydrator 3 to the dryer 4 is also It is slightly reduced to 46 t / day.

  For this reason, although the exhaust gas H discharged from the dryer 4 is slightly reduced to 1260 kg / hour, the supply of the dewatered sludge E to the dryer 4 is reduced and the amount of heat and supply of the combustion exhaust gas C is reduced. As the amount increases from the first example, a margin is generated in the amount of heat required for drying in the dryer 4 as in the second example, the temperature becomes as high as 230 ° C., and the required heat amount for heating in the digester 1 is 790 kJ / sec. We can cover it, and there is no need for fossil fuel. Also in this third example, the dried sludge F discharged from the dryer 4 has a discharge amount of 19.2 t / day, which is slightly smaller than that of the first example, and is easy to process. The exhaust gas G has a discharge amount of 6283 kg / hour and a heat amount of 190 kJ / sec, which are slightly higher than those in the first and second examples.

  That is, as explained in these first to third examples, the organic waste (concentrated sludge A) supplied to the digester 1 has a solid concentration in the range of 2 wt% to 4 wt%, and this organic The digestion gas B is generated by setting the organic substance concentration in the solid matter of the waste in the range of 80 wt% to 99 wt%, and the digest gas B is burned in the digest gas generator 2 having a power generation efficiency in the range of 20% to 35%. Digested sludge D discharged from the digestion tank 1 is dehydrated in a dehydrator 3 to a moisture content in the range of 60 wt% to 75 wt% and dried by an indirect heating drier 4, thereby requiring external energy such as fossil fuel. Instead, drying in the dryer 4 and heating of the digestion tank 1 can be performed only by the digestion gas B generated in the digestion tank 1.

  Further, in the organic waste processing apparatus, the dryer 4 and the organic waste processing method having the above-described configuration, the dryer 4 for drying the dewatered sludge E is supplied with the combustion exhaust gas supplied from the digestion gas generator 2. Since it is an indirect heating type dryer 4 that indirectly heats the dewatered sludge E by C, it is supplied to the digester 1 as compared with a direct heating type dryer such as an air dryer that dries the dewatered sludge with hot air. The dry exhaust gas H is less likely to be mixed with the fine powder of the dry sludge F, and no equipment such as a cyclone for removing such dry sludge powder is required.

  Moreover, in such an indirect heating type dryer 4, the air contained in the hot air as a heating medium is not included in the dry exhaust gas H obtained by drying the dewatered sludge E as in the direct heating type air flow dryer, Most of the dry exhaust gas H becomes water vapor evaporated from the dewatered sludge E. For this reason, the dehumidifier which separates air and water vapor | steam like the processing apparatus described in patent document 1 is not needed, and simplification of an apparatus structure is achieved in connection with the fact that a cyclone becomes unnecessary. Can do.

  And since most of the dry exhaust gas H is water vapor in this way, even if the dry exhaust gas H is blown directly into the digestion tank 1 and the concentrated sludge A is heated by the latent heat of water vapor as in the first embodiment. Although the digested sludge E increases due to the condensed water, the methane concentration of the digested gas B generated by methane fermentation does not decrease. For this reason, it is possible to efficiently heat the concentrated sludge A while suppressing the heat loss by directly blowing the dry exhaust gas H while maintaining the power generation amount in the digestion gas generator 2 and the heat amount of the combustion exhaust gas C. . Moreover, since the odor contained in the dry exhaust gas H obtained by drying the dewatered sludge E is also blown into the digestion tank 1 and combusted in the digestion gas generator 2 together with the digestion gas B, the odor of the dry exhaust gas H may leak outside. Absent.

  Next, FIG. 5 shows a second embodiment of the present invention, and this second embodiment and the third embodiment shown in FIG. 6 are common to the first embodiment shown in FIG. The same reference numerals are assigned to the parts to be described, and the description is omitted. In the second embodiment, a preheater 5 is provided between the dehydrator 3 and the dryer 4, and the dewatered sludge E discharged from the dehydrator 3 is heated by the preheater 5. After being pre-dried, it is supplied to the dryer 4 and dried to a predetermined moisture content. And the warm water I which generate | occur | produced in the digestion gas generator 2 is used as a heating medium which heats the dehydration sludge E in this preheating machine 5. FIG. Therefore, an indirect heating type dryer in which the heating medium (warm water I) does not come into contact with the dewatered sludge E is used as the preheating machine 5 so that the moisture of the dewatered sludge E does not increase.

  In the processing apparatus, the dryer 4, and the processing method of the second embodiment, the dehydrating performance of the dehydrator 3 is improved as in the second example of the heat balance of the first embodiment described above. Similarly, since the water content of the dewatered sludge E supplied to the dryer 4 is reduced, there is a surplus in the amount of heat required for drying in the dryer 4, and it is possible to supply the higher-temperature dry exhaust gas H to the digester 1. It becomes. For this reason, the waste heat of the hot water I generated in the digestion gas generator 2 can be used to heat the concentrated sludge A in the digestion tank 1 without requiring fossil fuel or the like as in the first embodiment. At the same time, the amount of dry sludge F discharged and moisture can be reduced to facilitate the treatment.

  In these first and second embodiments, the dried exhaust gas H generated in the dryer 4 is directly blown into the digester 1 to heat the concentrated sludge A, but the third implementation shown in FIG. The heat exchanger 6 may be attached to the digester 1 as in the form, and the concentrated sludge A may be indirectly heated through the heat exchanger 6. Further, instead of the heat exchanger 6, the concentrated sludge A may be indirectly heated by supplying the dry exhaust gas H into the jacket portion using the digester 1 as a jacket structure.

  In such 3rd Embodiment, since the dry waste gas H which mainly consists of water vapor | steam does not condense in the digestion tank 1, it can prevent that the water | moisture content of digested sludge D and dewatered sludge E increases, and it spins. The burden on the machine 3 and the dryer 4 can be reduced. In the third embodiment as well, the preheating machine 5 is provided between the dehydrator 3 and the dryer 4 as in the second embodiment, and the dewatered sludge is generated by the hot water I generated in the digestion gas generator 2. E may be heated and pre-dried.

  The configurations of the organic waste A, the digester 1, the dehydrator 3, the indirect heating dryer 4 and the like described in the above embodiments are merely examples, and the situation is within the scope of the present invention. It goes without saying that it can be changed according to the situation. Further, the flow of the combustion exhaust gas C and the digested sludge D described in each of the above embodiments is also an example, and it is needless to say that it can be changed depending on the situation without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Digestion tank 2 Digestion gas generator 3 Dehydrator 4 Dryer 5 Preheating machine 6 Heat exchanger A Concentrated sludge (organic waste)
B Digested gas C Combustion exhaust gas D Digested sludge E Dehydrated sludge F Dry sludge G Exhaust gas H Dry exhaust gas I Hot water

Claims (7)

  A digestion tank that generates digestion gas by heating and fermenting organic waste, a digestion gas generator that generates power by burning the digestion gas generated in the digestion tank, and the digestion tank A dehydrator for dewatering the digested sludge and a dryer for drying the dehydrated sludge dehydrated in the dehydrator, the dryer using the combustion exhaust gas obtained by burning the digestion gas in the digestion gas generator. An indirect heating dryer that indirectly heats and dries the organic waste in the digestion tank by drying exhaust gas generated by drying the dewatered sludge in the indirect heating dryer. An organic waste processing apparatus.   The organic waste treatment apparatus according to claim 1, wherein the dry waste gas is directly blown into the digestion tank to heat the organic waste in the digestion tank.   The organic waste treatment apparatus according to claim 1, wherein the dry waste gas is supplied to a heat exchanger attached to the digestion tank to indirectly heat the organic waste.   The organic property according to any one of claims 1 to 3, wherein the dewatered sludge is heated by hot water generated in the digestion gas generator and supplied to the indirect heating dryer. Waste treatment equipment. A digestion tank that generates digestion gas by heating and fermenting organic waste, a digestion gas generator that generates power by burning the digestion gas generated in the digestion tank, and the digestion tank A dehydrator for dewatering digested sludge, and a dryer for use in an organic waste treatment apparatus provided with a dryer for heating and drying the dewatered sludge dehydrated in the dehydrator,
A rotatable cylindrical body to which the dehydrated sludge is supplied, a heating path provided inside or outside the cylindrical body, and a carrier gas supply port for supplying a carrier gas to the inside of the cylindrical body And a dry exhaust gas discharge port for discharging dry exhaust gas generated by drying the dewatered sludge inside the cylindrical body together with the carrier gas,
Combustion exhaust gas obtained by burning the digestion gas in the digestion gas generator is supplied to the heating path, and the dehydrated sludge is indirectly heated and dried, and the dry exhaust gas outlet is connected to the digestion tank. And drying the organic waste in the digester by using the dry exhaust gas discharged together with the carrier gas.   Digestion gas is generated by heating and fermenting organic waste in the digestion tank, and power is generated by burning this digestion gas in the digestion gas generator, and the digested sludge discharged from the digestion tank is dehydrated. Dehydrated in the machine, dehydrated sludge dehydrated in the dewatering machine, indirectly heated by the indirect heating dryer with the combustion exhaust gas combusting the digested gas in the digestion gas generator, and dried, A method for treating organic waste, characterized in that a dry exhaust gas generated by drying the dehydrated sludge in the indirect heating dryer is supplied to the digestion tank to heat the organic waste.   The solid waste concentration of the organic waste supplied to the digestion tank is in the range of 2 wt% to 4 wt%, and the organic matter concentration in the solid waste of the organic waste is in the range of 80 wt% to 99 wt%. Gas is generated and the digestion gas is burned in the digestion gas generator having a power generation efficiency in the range of 20% to 35%. The digested sludge discharged from the digestion tank has a water content of 60 wt% to 60% in the dehydrator. The method for treating organic waste according to claim 6, wherein the organic waste is dehydrated to a range of 75 wt% and dried by the indirect heating dryer.

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