JP2005052706A - Waste treatment method and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the clogging of piping by preventing the adhesion of a soft foreign matter consisting of an organic matter to the inside of the piping. <P>SOLUTION: The waste treatment method has a hydrothermal reaction process for liquefying organic waste X held to a high-pressure/high-temperature state to obtain a treated liquid Y and a pressure reducing process for reducing the pressure of the treated liquid Y and also has a cooling process for directly mixing a cooling medium Z with the treated liquid Y before the pressure reducing process to cool the treated liquid Y. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a waste treatment method and apparatus.
[0002]
[Prior art]
In recent years, as a method for treating organic waste such as excess sludge, a treatment method using a subcritical hydrothermal reaction has been proposed. The organic waste treatment method utilizing hydrothermal reaction (hereinafter referred to as hydrothermal reaction method) is a method of treating organic waste in a liquid state by hydrothermal reaction treatment of subcritical high-pressure and high-temperature organic waste. The processed liquid is converted into a processed liquid, and the processed liquid is decompressed and then discharged to the outside.
A hydrothermal reaction device (waste treatment device) that employs such a hydrothermal reaction method is usually composed of a hydrothermal reactor for hydrothermal reaction treatment of organic waste at high pressure and high temperature, and the hydrothermal reactor. A preheater that cools the treated liquid by indirectly exchanging the discharged treated liquid and the organic waste and preheats the organic waste, and the treated liquid indirectly by a cooling medium such as cooling water A cooler for cooling and a pressure reducing valve for reducing the pressure of the treated liquid are provided.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-145860
[Problems to be solved by the invention]
However, it has been found that piping clogging occurs in the preheater and the cooler while the hydrothermal reactor is actually in operation. When these preheaters and coolers were disassembled, it was found that soft foreign substances made of organic matter adhered to the pipes. Since such a soft foreign substance adheres only in the preheater and the pipe of the cooler, it is considered that it is generated in the process of cooling the treated liquid.
[0005]
The present invention has been made in view of the above-described problems, and an object of the present invention is to prevent clogging of a pipe by preventing soft foreign substances made of organic matter from adhering to the inside of the pipe.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, as a first means related to a waste treatment method, a hydrothermal reaction step of liquefying organic waste under high pressure and high temperature to obtain a treated liquid, and the above treatment A waste treatment method having a decompression step of decompressing a spent liquid, comprising a cooling step of cooling the treated liquid by directly mixing a cooling medium with the treated liquid before the decompression step. Is adopted.
[0007]
As a second means related to the waste treatment method, in the first embodiment, a configuration is adopted in which, in the cooling step, the treated liquid is cooled to a saturated vapor temperature after the decompression step.
[0008]
As a third means related to the waste processing method, in the first or second means, the cooling step includes an inflow step of allowing the cooling medium to flow into the processed liquid, the processed liquid and the cooling medium. And a mixing step of mixing the two.
[0009]
As a fourth means related to the waste treatment method, in any one of the first to third means, in the hydrothermal reaction step, the organic waste is heated to 150 to 300 ° C. and heated. A configuration in which the pressure is increased to a value equal to or higher than the saturated water vapor pressure is adopted.
[0010]
As a fifth means related to the waste treatment method, a hydrothermal reaction step in which organic waste under high pressure and high temperature is liquefied to form a treated liquid, a cooling step for cooling the treated liquid, and cooling In the waste treatment method having a pressure reducing step for reducing the pressure of the treated liquid, a configuration is provided in which a cleaning process is provided for cleaning the inside of the flow path pipe through which the treated liquid flows by using water instead of the organic waste. adopt.
[0011]
As a sixth means related to the waste treatment method, in the fifth means, the cleaning step includes a pressurizing / heating step for increasing the pressure and temperature of the water, and a water depressurizing step for depressurizing the water. The structure of becoming is adopted.
[0012]
As a seventh means related to the waste treatment method, in the sixth means, in the pressurizing / warming step, the water is heated to 200 ° C. or higher and the saturated water vapor pressure at the heated temperature is set. A configuration in which pressure is applied is adopted.
[0013]
As a first means related to the waste treatment apparatus, a hydrothermal reactor that liquefies high-pressure and high-temperature organic waste and discharges it as a treated liquid, and a pressure-reducing valve that depressurizes and discharges the treated liquid are provided. The waste treatment apparatus has a configuration in which a cooling medium supply unit that directly flows the cooling medium into the treated liquid is provided in the preceding stage of the pressure reducing valve.
[0014]
As the second means related to the waste treatment apparatus, a configuration is adopted in which the first means includes a mixing unit for mixing the treated liquid and the cooling medium.
[0015]
As a third means related to the waste treatment apparatus, in the second means, the mixing section is a pipe having a length such that the treated liquid and the cooling medium are mixed. To do.
[0016]
As a fourth means related to the waste treatment apparatus, in any one of the first to third means, at least a part of the pipe through which the treated liquid flows, where the cooling medium flows into the treated liquid. A configuration in which polytetrafluoroethylene processing is applied is applied to the portion.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a waste treatment method and apparatus according to the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a schematic configuration diagram of a hydrothermal reaction apparatus (waste treatment apparatus) according to this embodiment. In this figure, reference numeral 1 is a hopper, 2 is a discharge pump, 3 is a pressurizing pump, 5 is a circulation pump for a hydrothermal reactor, 6 is a hydrothermal reactor, 7 is a cooling water supply unit (cooling medium supply unit), 8 Is a pressure reducing valve, 9 is a storage tank, X is excess sludge (organic waste), Y is a treated liquid, and Z is cooling water (cooling medium).
[0019]
The hopper 1 temporarily stores surplus sludge X supplied from the outside. The lower end of the hopper 1 is formed as an open end, and a discharge pump 2 is connected thereto. This discharge pump 2 regulates the discharge amount of the excess sludge X, and supplies the excess sludge X stored in the hopper 1 to the pressurizing pump 3 via the pipe a.
[0020]
The pressurizing pump 3 pressurizes the excess sludge X supplied from the dispensing pump 2 to a predetermined pressure and discharges it through the pipe b.
As shown in the drawing, a circulation path including a hydrothermal reactor circulation pump 5, a hydrothermal reactor 6, and a pipe c is disposed at the subsequent stage of the pressurizing pump 3.
The hydrothermal reactor 6 liquefies surplus sludge X supplied to itself by hydrothermal reaction treatment in a subcritical high pressure and high temperature state (150 to 300 ° C. and a pressure equal to or higher than the saturated water vapor pressure at that temperature). And discharged as processed liquid Y.
Further, the hydrothermal reactor circulation pump 5 circulates the treated liquid Y and the excess sludge X in a mixed state in the direction of the arrow through the pipe c.
[0021]
The cooling water supply unit 7 has processed the processed liquid Y discharged from the circulation path including the hydrothermal reactor circulation pump 5, the hydrothermal reactor 6, and the pipe c through the pipe d through the pipe e. Direct cooling water pressurized to the same degree as liquid Y flows in.
[0022]
FIG. 2 is an enlarged cross-sectional view of a connection portion between the pipe d and the pipe e. As shown in this figure, the pipe d and the pipe e are connected in a T-shape so that the flow of the treated liquid Y strikes the flow of the cooling water Z. And the coating by the polytetrafluoroethylene is given to the inner wall part of piping d and piping e near this connection part.
The length from the connecting portion between the pipe d and the pipe e to the pressure reducing valve 8 (mixing unit) is designed to have a length of about 1.5 m, for example, so that the treated liquid Y and the cooling water Z are sufficiently mixed. ing. Although it is conceivable to arrange a stirring device or the like for mixing the treated liquid Y and the cooling water Z in the pipe d, there is a possibility that the pipe will be clogged. It is better to design a sufficient length from the connection site with the pipe e to the pressure reducing valve 8.
[0023]
Returning to FIG. 1, the decompression valve 8 decompresses the waste water mixed with the treated liquid Y and the cooling water Z and discharges it through the pipe f.
A storage tank 9 that always stores the processed liquid Y at a height of, for example, 20 m is disposed behind the pressure reducing valve 8, and the pipe f is connected to the lower part of the storage tank 9. Therefore, the pressure in the pipe f is about 0.02 MPa depending on the weight of the processed liquid Y stored in the storage tank 9.
[0024]
The waste treatment apparatus according to the present embodiment configured as described above is connected to an organic matter decomposition apparatus including a biological reaction tank for decomposing and removing organic substances contained in the treated liquid Y, for example. And the processed liquid Y discharged | emitted from the storage tank 9 is supplied to such a biological reaction tank, for example.
The organic matter decomposition reaction apparatus is usually provided with a cooling tower that generates cooling water used in the organic substance decomposition reaction apparatus and circulates the organic substance decomposition reaction apparatus. Since this cooling tower is generally cooled by once vaporizing water, a part of the circulating cooling water is discharged to the outside in order to prevent deterioration of the cooling water quality. Therefore, a part of the cooling water discharged outside the cooling tower is pressurized by the cooling water supply unit 7 and flows into the treated liquid Y, so that the cooling water of the organic matter decomposing apparatus can be effectively used.
[0025]
Next, a waste processing method in the waste processing apparatus configured as described above will be described.
[0026]
The surplus sludge X supplied to the hopper 1 is temporarily stored by the hopper 1, and then a predetermined amount is continuously supplied to the subsequent pressurizing pump 3 through the pipe a by the discharge pump 2. The excess sludge X is pressurized to a predetermined pressure by the pressurizing pump 3 and further supplied to a circulation path including the hydrothermal reactor circulation pump 5, the hydrothermal reactor 6, and the pipe c via the pipe b. Is done.
[0027]
In this circulation path, the treated liquid Y that has been hydrothermally treated in advance by the hydrothermal reactor 6 is circulated by the hydrothermal reaction circulation pump 5. Excess sludge X is mixed with the treated liquid Y circulating in this circulation path and supplied to the hydrothermal reactor 6. The surplus sludge X is liquefied by being hydrothermally treated in a subcritical state in the hydrothermal reactor 6 and discharged from the hydrothermal reactor 6 as a treated liquid Y (hydrothermal reaction step).
[0028]
A part of the treated liquid Y discharged from the hydrothermal reactor 6 is discharged from the circulation path through the pipe d. As described above, the pipe d is connected to the pipe e through which the cooling water Z supplied from the cooling water supply unit 7 flows. Therefore, the cooling water Z flows into the treated liquid Y (inflow process). ).
Thereafter, the processed liquid Y is uniformly mixed by being sufficiently mixed between the connection portion between the pipe d and the pipe e and reaching the pressure reducing valve 8 (mixing step). Then, the treated liquid Y decompressed by the decompression valve 8 is supplied to the storage tank 9 through the pipe f, and then supplied to, for example, an external organic substance decomposition reaction apparatus.
Thus, by directly mixing the cooling water Z with the treated liquid Y, the temperature difference between the inner wall surface of the pipe and the treated liquid Y is reduced, and soft foreign substances made of organic matter are less likely to adhere to the pipe. .
Moreover, since the cooling water Z of arbitrary flow volume can be flowed into the processed liquid Y from the cooling water supply part 7, the temperature of the processed liquid Y is controlled irrespective of the fluctuation | variation of the soil coefficient etc. of the processed liquid Y. It becomes possible to do.
[0029]
In addition, since the soft foreign substance from the organic substance mentioned above tends to be generated as the temperature of the processed liquid Y becomes lower, the temperature of the processed liquid Y after being depressurized by the pressure reducing valve 8 is set as high as possible. It is preferable to do. Therefore, in this embodiment, the supply amount of the cooling water Z is adjusted so that the temperature of the treated liquid Y becomes 120 ° C.
This is because, as described above, the piping f in the rear stage of the pressure reducing valve 8 is connected to the lower part of the storage tank 9 in which the treated liquid Y is stored for about 20 m, so that the inside of the piping f is in a pressurized state of about 0.02 MPa. This is because 120 ° C. is the saturated water vapor temperature in the pipe f.
[0030]
Further, since the inner wall surface of the connection portion between the pipe d and the pipe e is coated with polytetrafluoroethylene as described above, the treated liquid Y is temporarily mixed with the cooling water Z. Even when soft foreign matter is generated from the organic matter when it is cooled, it is possible to prevent the soft foreign matter from adhering to the inner wall surfaces of the pipes d and e.
[0031]
As described above, according to the waste treatment method and apparatus according to the present invention, by mixing the cooling water Z directly with the treated liquid Y, it is possible to prevent soft foreign substances made of organic matter from adhering to the pipe. Therefore, it becomes possible to prevent clogging of piping.
[0032]
In addition, when the waste disposal apparatus shown in the above embodiment was actually operated continuously, it was confirmed that soft foreign substances made of organic matter do not adhere to the pipe, and the pipe clogging can be prevented.
[0033]
As described above, the cooling water Z is directly mixed with the treated liquid Y, and the inner wall surface of the pipe in the vicinity of the connection portion between the pipe d through which the treated liquid Y flows and the pipe e through which the cooling water Y flows is poly. Even when the coating with tetrafluoroethylene is applied, there is a possibility that soft foreign substances made of organic matter may gradually adhere to the pipe while the waste treatment apparatus is operated for a long time. is there.
[0034]
In such a case, it is possible to remove (clean) soft foreign substances made of organic matter by flowing high-temperature water into a pipe (flow path) through which the treated liquid Y flows (cleaning step). .
Specifically, the supply of the cooling water Z from the cooling water supply unit 7 is stopped, and water is supplied to the hopper 1 instead of the excess sludge X. The water flows in a high pressure / high temperature state by the pressurization pump 3 and the hydrothermal reactor 6 (pressurization / heating step). As a result, the high-pressure and high-temperature water flows in the vicinity of the connection portion between the pipe d and the pipe e, which may generate soft foreign substances made of organic matter, so that the soft substance made of organic matter attached to the inner wall surface of the pipe It is possible to remove the foreign matter.
Thereafter, the water is decompressed by the decompression valve 8 (water decompression step). In this case, since water is in a high pressure / high temperature state, the pressure is reduced by the pressure reducing valve 8 to generate a so-called flush. However, since this is water, there is no problem.
In addition, the temperature of the water for removing the soft foreign substances made of organic substances is preferably 200 ° C. or higher in a pressurized state. This is because a soft foreign substance made of an organic substance has not adhered to the pipe through which the treated liquid Y at 200 ° C. or higher flows. By performing such a cleaning process once a month, for example, it becomes possible to more reliably prevent piping clogging.
[0035]
In addition, even if a soft foreign substance made of organic matter adheres to the pipe and the pipe is clogged, the hydrothermal treatment apparatus according to this embodiment allows the cooling water Z to flow directly into the treated liquid Y. Since the treated liquid Y is rapidly cooled, the range to which soft foreign substances made of organic matter adhere becomes small. For this reason, the maintenance of the hydrothermal reactor becomes easy.
[0036]
The preferred embodiments of the waste treatment method and apparatus according to the present invention have been described above with reference to the accompanying drawings. Needless to say, the present invention is not limited to the above-described embodiments. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.
[0037]
For example, in the said embodiment, when the organic substance removal apparatus was connected to this waste disposal apparatus, it demonstrated that the cooling water produced | generated by the cooling tower could be used as a cooling medium. However, the present invention is not limited to this. For example, waste water discharged from the organic substance removing device or the like to the sea or the like may be used as the cooling medium.
[0038]
Moreover, in the said embodiment, the case where the inner wall surface of the pipe | tube of the vicinity of the connection site | part of the piping d through which the process liquid Y flows and the piping e through which the cooling water Y flows was coated with the polytetrafluoroethylene was demonstrated. . However, the present invention is not limited to this. For example, the pipes d and e may be configured as pipes made of polytetrafluoroethylene resin.
[0039]
Further, in the cleaning step in the above embodiment, water was supplied to the hopper 1 instead of the excess sludge X, and this water was increased in pressure and temperature to flow into the pipe. However, the present invention is not limited to this. For example, a configuration in which water flows through the pipe d and the pipe e by directly pressurizing high-pressure / high-temperature water into the middle part of the pipe d may be adopted. good.
[0040]
Moreover, in the said embodiment, you may employ | adopt the structure which reduces the burden of the hydrothermal reactor 6 by providing the preheater which consists of a heater etc. in the middle part of the piping b, and preheating the excess sludge X.
[0041]
【The invention's effect】
As described above, according to the present invention, a waste having a hydrothermal reaction step in which organic waste under high pressure and high temperature is liquefied to form a treated liquid, and a decompression step of depressurizing the treated liquid. Since it has a cooling process which cools the above-mentioned processed liquid by mixing a cooling medium with the above-mentioned processed liquid directly before the above-mentioned pressure reduction process, it is a processing method, and a soft foreign substance which consists of organic matter adheres in piping. By preventing this, it becomes possible to prevent clogging of piping.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a hydrothermal reaction apparatus (waste treatment apparatus) according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a connection portion between a pipe d and a pipe e according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Hopper 2 ... Discharge pump 3 ... Pressure pump 5 ... Circulation pump 6 for hydrothermal reactors 6 ... Hydrothermal reactor 7 ... Cooling water supply part (cooling medium supply part)
8 ... Pressure reducing valve 9 ... Storage tank X ... Surplus sludge (organic waste)
Y …… Processed liquid Z …… Cooling water (cooling medium)

Claims (11)

A waste treatment method comprising a hydrothermal reaction step for liquefying organic waste under high pressure and high temperature to form a treated liquid, and a decompression step for depressurizing the treated liquid,
A waste treatment method comprising a cooling step of cooling the treated liquid by directly mixing a cooling medium with the treated liquid before the depressurizing step. The waste treatment method according to claim 1, wherein in the cooling step, the treated liquid is cooled to a saturated vapor temperature after the decompression step. The disposal according to claim 1 or 2, wherein the cooling step includes an inflow step for allowing the cooling medium to flow into the treated liquid and a mixing step for mixing the treated liquid and the cooling medium. Material processing method. In the said hydrothermal reaction process, the said organic waste is heated to 150-300 degreeC, and is pressurized more than the saturated water vapor pressure in the heated temperature, The said any one of Claims 1-3 characterized by the above-mentioned. Waste disposal methods. A hydrothermal reaction step that liquefies organic waste under high pressure and high temperature to form a treated liquid; a cooling step that cools the treated liquid; and a decompression step that depressurizes the cooled treated liquid. In the waste disposal method,
A waste treatment method comprising a cleaning step of cleaning the inside of a flow path pipe through which the treated liquid flows by using water instead of the organic waste. 6. The waste processing method according to claim 5, wherein the cleaning step includes a pressurizing / heating step for increasing the pressure and temperature of the water and a water depressurizing step for depressurizing the water. The waste treatment method according to claim 6, wherein, in the pressurizing and warming step, the water is heated to 200 ° C. or more and pressurized to a saturated water vapor pressure at the warmed temperature. A waste heat treatment apparatus comprising a hydrothermal reactor that liquefies high-pressure, high-temperature organic waste and discharges it as a treated liquid, and a pressure reducing valve that discharges the treated liquid under reduced pressure,
A waste treatment apparatus comprising a cooling medium supply unit that directly flows a cooling medium into the treated liquid at a stage preceding the pressure reducing valve. The waste treatment apparatus according to claim 8, further comprising a mixing unit that mixes the treated liquid and the cooling medium. The waste treatment apparatus according to claim 9, wherein the mixing unit is a pipe having a length such that the treated liquid and the cooling medium are mixed. 9. The polytetrafluoroethylene processing is applied to at least a portion of the pipe through which the treated liquid flows corresponding to a portion where the cooling medium flows into the treated liquid. To 10. The waste treatment apparatus according to any one of 10 to 10.

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