JP2006068399A - Apparatus and method for hydrothermal decomposition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for hydrothermal decomposition capable of preventing drop of cooling efficiency while decomposing slurried materials. <P>SOLUTION: The apparatus comprises a primary reactor 100 for carrying out hydrothermal reaction, a pressurization pump for pressurizing each of process solutions supplied to the primary reactor, that is, PCB (polychlorobiphenyls) or a slurried material 101 containing PCB, water 104 and an NaOH solution 103, a secondary reactor 107 made by winding piping spirally, diverge passages 12-1 and 12-2 for dividing a decomposed liquid 117 from the secondary reactor 107 into two or more, an alkaline solution supply tube 13 for supplying a part of the NaOH solution 103 to the diverge passages, a decomposed liquid return tube 15 for returning a decomposed liquid 14 supplied with the NaOH solution 103 to the primary reactor, first and second coolers 108-1 and 108-2 respectively interposed within the diverge passages for cooling the decomposed liquid, a reducing valve 109 for reducing the pressure of the decomposed liquid, and a gas-liquid separator 110 for carrying out gas-liquid separation of the decomposed liquid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydrothermal decomposition apparatus and method for decomposing a harmful substance such as PCB.

  In recent years, PCBs (polychlorinated biphenyls) are strongly toxic, and their manufacture and import are prohibited. This PCB is one of the persistent organic pollutants, has the property that it is difficult to be decomposed in the environment, is fat-soluble, has a high bioconcentration rate, and is semivolatile and can be transferred via the atmosphere. In addition, it has been reported to remain in the environment such as water and living things. This PCB was designated as a specially managed waste based on the Waste Disposal, Waste Oil Containing PCB, and PCB Contaminant in 1997 (Heisei 4), and further in 1997 Wood waste and fiber waste were additionally designated as PCB contaminants. Electrical equipment to be processed PCBs includes high-voltage transformers, high-voltage capacitors, low-voltage transformers / condensers, and pole transformers. As waste PCBs, those used for the heat medium are those used as insulating oil. There are kerosene etc. used for cleaning, and as waste pressure sensitive paper, there are capsule oils used for carbonless paper, furthermore, use of these PCBs or replacement of heat medium, regeneration of insulating oil, purification of leakage, There are PCB pollutants such as activated carbon used in the treatment of PCB-containing materials, waste white clay, waste wastes, and work clothes. Currently, these are strictly stored, but immediate PCB processing is desired.

In recent years, various techniques for decomposing PCBs used in such transformers and capacitors have been developed, and the present applicant has previously proposed a hydrothermal decomposition apparatus (Patent Document 1).
An example of this hydrothermal decomposition treatment apparatus is shown in FIG.
As shown in FIG. 6, this hydrothermal decomposition treatment apparatus includes a cylindrical primary reaction tower 100, a slurry 101 containing PCB or PCB, an oil (or organic solvent) 102, a sodium hydroxide solution (NaOH) 103, and Pressurizing pumps 105a to 105d that pressurize each treatment liquid of water (H ₂ O) 104, a feed water heater 106 that uses the water 104 as water vapor, a secondary reaction tower 107 that has a configuration in which a pipe is spirally wound, , A cooler 108 and a pressure reducing valve 109. Further, a gas-liquid separator 110 and an activated carbon tank 111 are disposed downstream of the pressure reducing valve 109, exhaust gas (CO ₂ ) 112 is exhausted from the chimney 113, and drainage (H ₂ O, NaCl) 114 is It is stored in the discharge tank 115 and drained as necessary.

The treatment liquids 101, the slurry (101) containing PCB, the oil (or organic solvent) 102, the NaOH 103 and the water 104 are introduced from the treatment liquid tanks 120a to 120d through the pipes 121a to 121d and the ejector 122, respectively. Further, an oxidant such as oxygen (O ₂ ) 116 is supplied by the high-pressure oxygen supply facility 117, and the oxygen supply pipe 118 is directly connected to the primary reaction tower 100. The reason why the oil (or organic solvent) 102 is added is to promote the decomposition reaction and to raise the reaction temperature to the optimum temperature at the start of the decomposition. Alternatively, the PCB or the slurryed product 101 containing PCB, the sodium hydroxide solution 103 and the water 104 may be mixed and introduced into the primary reaction tower 100 as a treatment liquid.

In the apparatus, the pressure in the primary reaction tower 100 is increased to, for example, 26 MPa by pressurization by the pressurization pump 105. The feed water heater 106 preheats H ₂ O to about 300 ° C. In addition, oxygen is spouted into the primary reaction tower 100 and the temperature is raised to 380 ° C. to 400 ° C. by the internal reaction heat. By this stage, an oxidative decomposition reaction has occurred inside the primary reaction tower 100, and PCB has been decomposed into CO ₂ and H ₂ O. Next, in the cooler 108, the decomposition treatment liquid 117 from the secondary reaction tower 107 is cooled to about 100 ° C., and the pressure is reduced to atmospheric pressure by the subsequent pressure reducing valve 109. Then, CO ₂ and water vapor and the treatment liquid are separated by the gas-liquid separator 110, and the CO ₂ and water vapor are exhausted into the environment through the activated carbon layer 111 as the exhaust gas 112. Here, the slurry of the PCB or the slurry 101 containing PCB is a metal scrap, a piece of wood, a cloth or the like on which PCB is adhered or contained, and is formed into a slurry with a predetermined particle diameter by a slurrying device such as a mill. It means what was done.

JP 2002-248455 A

  By the way, the hydrothermal decomposition apparatus proposed in Patent Document 1 hydrolyzes not only PCBs but also slurries such as metal scraps, wood pieces, cloths, etc., and this treated decomposition liquid 116 is used as a secondary reaction tower. When cooled in the cooler 108 provided downstream of 107, for example, a scale composed of a compound mainly composed of Al, Si, Ni, Fe or the like may be deposited, resulting in a problem that cooling efficiency is lowered. is there.

  In particular, when water 104 to be supplied to the primary reactor is supplied to the cooler 108 and used as a regenerative heat exchanger that retains heat, if the scale adheres to the heat exchanger, the thermal efficiency decreases, and the reaction thereafter As a result, excessive power is supplied to the feed water heater 106 that heats up to a predetermined temperature, resulting in a problem that system efficiency decreases.

  This invention makes it a subject to provide the hydrothermal decomposition apparatus and method which prevent the fall of cooling efficiency in the case of decomposing | disassembling slurries especially in view of the said problem.

  The first invention of the present invention for solving the above-mentioned problems is a reaction tower that performs a hydrothermal reaction in a subcritical region, and each treatment liquid of harmful substances, oil, water, and alkali solution supplied to the reaction tower. A pressure pump for pressurization, a branch passage for branching the decomposition treatment liquid from the reaction tower into at least two, an alkali solution supply pipe for supplying a part of the alkaline solution to the branch passage, and the branch passage A cooler for cooling the decomposition treatment liquid, a decomposition treatment liquid return passage for returning the decomposition treatment liquid supplied with the alkaline solution to a primary reaction tower, a pressure reducing valve for depressurizing the decomposition treatment liquid, A hydrothermal decomposition apparatus comprising: a gas-liquid separation apparatus that performs gas-liquid separation of the decomposition treatment liquid.

  A second invention includes a reaction tower that performs a hydrothermal reaction in a subcritical region, a pressurizing pump that pressurizes treatment liquids of harmful substances, oil, water, and an alkali solution supplied to the reaction tower, and the reaction tower. An alkaline solution supply pipe for supplying a part of the alkaline solution to the decomposition treatment liquid passage, a cooler for cooling the decomposition treatment liquid supplied with the alkaline solution, a pressure reducing valve for depressurizing the decomposition treatment liquid, and the decomposition A hydrothermal decomposition apparatus comprising: a gas-liquid separation device that separates a treatment liquid into gas and liquid.

  According to a third aspect of the present invention, there is provided a reaction tower that performs a hydrothermal reaction in a subcritical region, a pressure pump that pressurizes treatment liquids of harmful substances, oil, water, and an alkaline solution supplied to the reaction tower, and the reaction tower. A dilution water supply pipe for supplying dilution water to the decomposition treatment liquid passage, a cooler for cooling the decomposition treatment liquid supplied with the dilution water, a pressure reducing valve for depressurizing the decomposition treatment liquid, and the decomposition treatment liquid The hydrothermal decomposition apparatus includes: a gas-liquid separation apparatus that separates gas and liquid; and a dilution water supply pipe that supplies dilution water to the decomposition treatment liquid.

  A fourth invention is the hydrothermal decomposition apparatus according to any one of the first to third inventions, wherein an ultrasonic generator or a vibration generator is provided in the cooler.

  A fifth invention is the hydrothermal decomposition according to any one of the first to fourth inventions, further comprising a heater for preheating the alkali solution and water supplied to the primary reaction tower to 250 to 350 ° C. In the device.

  A sixth invention is the hydrothermal decomposition apparatus according to any one of the first to fifth inventions, wherein an oxygen or ozone supply device for supplying oxygen or ozone to the primary reaction tower is provided.

  A seventh invention is the hydrothermal decomposition apparatus according to any one of the first to sixth inventions, wherein a subcritical state of the primary reaction tower is a temperature of 300 to 400 ° C. and a pressure of 10 to 40 MPa. .

  An eighth invention is the hydrothermal decomposition apparatus according to any one of the first to seventh inventions, wherein the harmful substance is PCB or a slurry containing PCB.

  A ninth invention is the hydrothermal decomposition apparatus according to any one of the first to seventh inventions, wherein the harmful substance is a pharmaceutical, an agrochemical, a chemical or a slurry containing them.

  According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the reaction tower is installed on the downstream side of the tubular primary reaction tower and the primary reaction tower, and the pipe is spirally wound. Or a cylindrical secondary reaction tower.

  The eleventh aspect of the invention is a hydrothermal decomposition method in which an alkali solution is supplied in a subcritical region to detoxify harmful substances, and when the decomposition treatment liquid after completion of hydrothermal decomposition is cooled, the alkali The hydrothermal decomposition method is characterized by preventing adhesion of scale that occurs during cooling using a solution.

  In a twelfth aspect according to the eleventh aspect, the decomposition treatment liquid is cooled by two or more coolers, the supply of the decomposition treatment liquid is stopped to the cooler to which the scale is attached, and the alkaline solution is supplied. The hydrothermal decomposition method is characterized by removing attached scale.

  A thirteenth invention is the hydrothermal decomposition method according to the eleventh or twelfth invention, wherein the decomposition treatment liquid containing an alkaline solution is returned to a reaction tower for performing a hydrothermal reaction.

  The fourteenth invention is a hydrothermal decomposition method in which an alkali solution is supplied in a subcritical region to cause detoxification of a harmful substance, and when the decomposition treatment liquid after completion of hydrothermal decomposition is cooled, The hydrothermal decomposition method is characterized in that the decomposition treatment liquid is diluted using a solution to prevent the scale from being deposited during cooling.

  According to the present invention, the scale adhered in the cooler can be removed with an alkaline solution. Moreover, scale adhesion can be suppressed by supplying an alkaline solution. Moreover, by supplying dilution water, the solubility of a scale component can be increased and scale precipitation can be prevented.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

A hydrothermal decomposition apparatus according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram illustrating a hydrothermal decomposition apparatus according to a first embodiment. FIG. 1 shows a main part of the hydrothermal decomposition apparatus, and its configuration is the same as that of FIG. As shown in FIG. 1, the hydrothermal decomposition apparatus according to the present embodiment includes a primary reaction tower 100 that performs a hydrothermal reaction in a cylindrical subcritical region, and an organic halide (PCB) that is supplied to the primary reaction tower. Alternatively, a slurry pump 101 containing PCB, water 104, and a pressure pump (not shown) that pressurizes each treatment solution of the sodium hydroxide solution 103 that is an alkaline solution, and two pipes that are spirally wound or cylindrical. A secondary reaction tower 107, branch passages 12-1 and 12-2 for branching the decomposition treatment liquid 117 from the secondary reaction tower 107 into at least two, and a part of the sodium hydroxide solution 103 are supplied to the branch passage. An alkaline solution supply pipe 13 to be supplied, a decomposition treatment liquid 14 supplied with the sodium hydroxide solution 103 to a primary reaction tower, a decomposition treatment liquid return passage 15 and a branched branch passage, respectively. First and second coolers 108-1 and 108-2 for cooling the treatment liquid, a pressure reducing valve 109 for reducing the pressure of the decomposition treatment liquid, and a gas-liquid separation device 110 for gas-liquid separation of the decomposition treatment liquid. It has. A pressure control valve 16 is interposed in the alkaline solution supply pipe 13 to adjust the supply amount of the sodium hydroxide solution 103. V1 to V4 are switching valves for switching each flow path. Here, the reaction conditions of the hydrothermal decomposition reaction are the same as those of the hydrothermal decomposition apparatus shown in FIG.
In the present example, the reaction tower is a tubular primary reaction tower 100 and the downstream side of the primary reaction tower, and the pipe is spirally wound or a tubular secondary reaction tower 107. However, the present invention is not limited to this, and may be a single-column reaction column in which the primary reaction column 100 and the secondary reaction column 107 are integrated, or the primary reaction column 100 and the secondary reaction column 107 may be combined. It is good also as a reaction tower more than the 3 tower type which made any one a plurality of towers.

Examples of the harmful substances that are decomposed by the hydrothermal decomposition apparatus include, for example, pharmaceuticals, agricultural chemicals, chemicals, or slurries containing these in addition to PCBs or PCB-containing slurries. Is not limited to these.
The following describes the case where the PCB-containing slurry is hydrothermally decomposed as a harmful substance.

  In the hydrothermal decomposition apparatus having the above configuration, for example, when the first cooler 108-1 is used, when the scale adheres and the cooling efficiency decreases, the switching valves V1 and V2 are closed and the switching valves V3 and V4 are closed. And the flow path of the decomposition treatment liquid 117 from the secondary reaction tower is switched by a switching device (not shown). And the decomposition processing liquid 117 is distribute | circulated to the 2nd cooler 108-2 side, and cooling is continued. Thereafter, the pressure regulating valve 16 is adjusted to supply a predetermined amount of the sodium hydroxide solution 103, which is an alkaline solution, to the first cooler 108-1 side.

  The supplied sodium hydroxide solution 103 dissolves the scale adhering in the first cooler 108-1 and removes it. Here, the alkali solution to be supplied uses the sodium hydroxide solution 103 used in the primary reaction tower 100, and the one heated by the feed water heater 106 is supplied. The decomposition treatment liquid 14 supplied with sodium hydroxide after the scale is dissolved is returned to the primary reaction tower 10 through the decomposition treatment liquid return passage 15.

  Here, the concentration of the alkaline solution is not particularly limited, but for example, the sodium hydroxide solution 103 of 5% by weight or more is preferable. Further, the temperature at which sodium hydroxide is supplied is 90 ° C. or higher, which is preferable from the viewpoint of dissolution cleaning.

  In the present embodiment, the decomposition treatment liquid 14 supplied with sodium hydroxide after scale removal is returned to the primary reaction tower 100 via the decomposition treatment liquid return passage 15, so that the decomposition treatment liquid from which scale has been removed is returned. It is not necessary to perform the treatment separately as treatment wastewater, and the increase in cost for the scale removal treatment can be suppressed.

  In this embodiment, the number of coolers is two, but the present invention is not limited to this and may be three or more.

  In addition, for example, an ultrasonic generator or a vibration generator may be provided in the cooler to further improve the scale removal efficiency. In the following embodiments, an ultrasonic generator or a vibration generator may be provided.

A hydrothermal decomposition apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a conceptual diagram illustrating a hydrothermal decomposition apparatus according to a second embodiment. In addition, about the same member as the apparatus of Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
In the present embodiment, when water supplied to the primary reaction tower 100 is heated, the water 104 and the sodium hydroxide solution 103 are supplied separately to the feed water heater 106, and then they are mixed and supplied individually. is doing.

In this embodiment, the concentration of the sodium hydroxide solution 103 supplied to the feed water heater 106 is 5% by weight, and the concentration of the sodium hydroxide supplied to the primary reaction tower 100 is adjusted using the water 104 that has passed through the feed water heater. For example, the concentration is adjusted to 2.5% by separately mixing in the mixing unit 18.
Then, the sodium hydroxide solution 103 having a concentration of 5% by weight heated by the feed water heater 106 is supplied to the coolers 108-1 and 108-2 through the alkaline solution supply pipe 13 in the same manner as in the first embodiment. The scale deposits are removed.

  Thereby, while maintaining the density | concentration of the alkaline solution for scale removal, the alkaline solution adjusted to the desired density | concentration can be supplied to the primary reaction tower 100 which performs a hydrothermal decomposition reaction.

A hydrothermal decomposition apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a conceptual diagram illustrating a hydrothermal decomposition apparatus according to a third embodiment. In addition, about the same member as the apparatus of Example 1 and Example 2, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
In this embodiment, as in the conventional hydrothermal apparatus shown in FIG. 6, the cooler 108 is arranged in one line, and the sodium hydroxide solution 103 is supplied between the secondary reaction tower 107 and the cooler 108. Yes.
Then, the decomposition solution containing the sodium hydroxide solution 103 is supplied to the gas-liquid separator 110 as it is without returning it to the primary reactor 100. For this reason, the waste water from the gas-liquid separator 110 is neutralized in the neutralization tank 17 and discharged after having a predetermined pH.

Here, in this embodiment, it is desirable that the pH after supplying the sodium hydroxide solution 103 is 13 or more. This is because when the pH is less than 13, precipitation of the aluminum compound that is the main component of the scale cannot be suppressed.
Therefore, when the sodium hydroxide solution 103 is supplied, the pH meter 19 is used to adjust the pH to be 13 or higher, thereby preventing scale precipitation.

  According to the present embodiment, the two coolers as in the first and second embodiments are not provided, so that the installation cost of the facility is low. In addition, since the sodium hydroxide solution 103 is supplied before the scale adheres, the amount of sodium hydroxide solution used is less than in the case where the scale is attached and then removed, which is economical.

A hydrothermal decomposition apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a conceptual diagram illustrating a hydrothermal decomposition apparatus according to a fourth embodiment. In addition, about the same member as the apparatus of Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
In this embodiment, unlike the embodiment described above, the dilution water 20 is supplied instead of supplying the sodium hydroxide solution.
The supply of the dilution water 20 increases the solubility of the scale components mainly composed of Al, Si, Ni, Fe, etc., thereby preventing the scale from being deposited.
Further, the measured value and deviation of the inlet / outlet differential pressure gauge 21 installed in the cooler 108 are monitored, and the dilution water 20 is supplied so as not to cause an increase in the differential pressure.

  In the present embodiment, a special chemical solution such as the alkaline solution according to the above-described embodiment is not used. Scale adhesion can be suppressed only by supplying water. The running cost can be reduced.

A hydrothermal decomposition apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a conceptual diagram illustrating a hydrothermal decomposition apparatus according to a fifth embodiment. The same members as those in the apparatus of the embodiment shown in FIG. 1 and the apparatus of the conventional example shown in FIG.
In this embodiment, the heat of the decomposition treatment liquid discharged from the secondary reaction tower 107 is used to reduce the apparatus scale of the feed water heater 106 for the water 104 supplied to the primary reaction tower 100.

  In the present embodiment, the first regenerative heat exchanger 31-1 and the second regenerative heat exchanger 31-2 are used, and the water 104 from the water tank 120d is preheated. The preheated water is supplied to the feed water heater 106, where it is converted into water vapor and sent to the primary reaction tower 100.

In the present embodiment, the first regenerative heat exchanger 31-1 and the second regenerative heat exchanger 31-2 are provided with an alkaline solution supply pipe 13 for supplying sodium hydroxide 103 in the same manner as in the first embodiment, so that the remaining heat is provided. The sodium hydroxide solution 103 is supplied for scale removal.
In the figure, V5 to V8 are switching valves for switching the flow path of the mixed liquid of water 104 and sodium hydroxide solution 103.

In the hydrothermal decomposition apparatus having the above configuration, for example, when the first regenerative heat exchanger 31-1 is used, when the scale adheres and the cooling efficiency decreases, the switching valves V1 and V2 are closed and the switching valve is closed. V3 and V4 are opened, and the flow path of the decomposition treatment liquid 117 from the secondary reaction tower is switched by a switching device (not shown). And the decomposition processing liquid 117 is distribute | circulated to the 2nd reproduction | regeneration heat exchanger 31-2 side, and cooling is continued. Thereafter, the pressure regulating valve 16 is adjusted to supply a predetermined amount of the sodium hydroxide solution 103, which is an alkaline solution, to the first cooler 108-1 side.
At the same time, the switching valves V5 and V6 are closed and the switching valves V7 and V8 are opened, and the flow path of the mixed solution of the water 104 and the sodium hydroxide solution 103 is switched by a switching device (not shown) to continue the remaining heat.

  According to the present embodiment, the scale attached to the heat exchanger can be efficiently removed, the heat exchange efficiency is not lowered, the power consumption in the feed water heater 106 is not increased, and the system efficiency is improved. .

  As described above, the hydrothermal decomposition apparatus according to the present invention efficiently removes the scale that precipitates when cooling the decomposition treatment liquid after the decomposition treatment, for example, in the case of absorbing and decomposing the slurry of harmful substances. It is suitable for use in hydrothermal decomposition treatment of harmful substances.

1 is a schematic diagram of a hydrothermal decomposition apparatus according to Example 1. FIG. 3 is a schematic diagram of a hydrothermal decomposition apparatus according to Example 2. FIG. 6 is a schematic view of a hydrothermal decomposition apparatus according to Example 3. FIG. 6 is a schematic view of a hydrothermal decomposition apparatus according to Example 4. FIG. 6 is a schematic view of a hydrothermal decomposition apparatus according to Example 5. FIG. It is the schematic of the hydrothermal decomposition apparatus concerning a prior art.

Explanation of symbols

12-1, 12-2 Branch passage 13 Alkaline solution supply pipe 14 Decomposition treatment liquid supplied with sodium hydroxide solution 15 Decomposition treatment liquid return passage 16 Pressure control valve 100 Primary reaction tower 101 Slurried product containing PCB or PCB 102 Oil DESCRIPTION OF SYMBOLS 103 Sodium hydroxide solution 104 Water 107 Secondary reaction column 116 Oxygen 116 Decomposition process liquid 108-1 1st cooler 108-2 2nd cooler 109 Pressure reducing valve 110 Gas-liquid separator V1-V8 switching valve

Claims (14)

A reaction tower for hydrothermal reaction in the subcritical region;
A pressurizing pump for pressurizing each treatment liquid of harmful substances, oil, water and alkaline solution supplied to the reaction tower;
A branch passage for branching the decomposition treatment liquid from the reaction tower into at least two or more;
An alkaline solution supply pipe for supplying a part of the alkaline solution to the branch passage;
A cooler that is interposed in the branched branch passage and cools the decomposition treatment liquid;
A decomposition treatment liquid return passage for returning the decomposition treatment liquid supplied with the alkaline solution to the primary reaction tower;
A pressure reducing valve for decompressing the decomposition treatment liquid;
A gas-liquid separation device for gas-liquid separation of the decomposition treatment liquid;
A hydrothermal decomposition apparatus comprising: A reaction tower for hydrothermal reaction in the subcritical region;
A pressurizing pump for pressurizing each treatment liquid of harmful substances, oil, water and alkaline solution supplied to the reaction tower;
An alkaline solution supply pipe for supplying a part of the alkaline solution to the decomposition treatment liquid passage from the reaction tower;
A cooler for cooling the decomposition treatment liquid supplied with the alkaline solution;
A pressure reducing valve for decompressing the decomposition treatment liquid;
A gas-liquid separation device for gas-liquid separation of the decomposition treatment liquid;
A hydrothermal decomposition apparatus comprising: A reaction tower for hydrothermal reaction in the subcritical region;
A pressurizing pump for pressurizing each treatment liquid of harmful substances, oil, water and alkaline solution supplied to the reaction tower;
A dilution water supply pipe for supplying dilution water to the decomposition treatment liquid passage from the reaction tower;
A cooler for cooling the decomposition treatment liquid supplied with the dilution water;
A pressure reducing valve for decompressing the decomposition treatment liquid;
A gas-liquid separation device for gas-liquid separation of the decomposition treatment liquid;
A hydrothermal decomposition apparatus comprising: a dilution water supply pipe for supplying dilution water to the decomposition treatment liquid. In any one of Claims 1 thru | or 3,
A hydrothermal decomposition apparatus, wherein an ultrasonic generator or a vibration generator is provided in the cooler. In any one of Claims 1 thru | or 4,
A hydrothermal decomposition apparatus provided with a heater for preheating the alkali solution and water supplied to the primary reaction tower to 250 to 350 ° C. In any one of Claims 1 thru | or 5,
A hydrothermal decomposition apparatus comprising an oxygen or ozone supply device for supplying oxygen or ozone to the primary reaction tower. In any one of Claims 1 thru | or 6,
The hydrothermal decomposition apparatus characterized in that the subcritical state of the primary reaction tower is a temperature of 300 to 400 ° C and a pressure of 10 to 40 MPa. In any one of Claims 1 thru | or 7,
The hydrothermal decomposition apparatus, wherein the harmful substance is PCB or a slurry containing PCB. In any one of Claims 1 thru | or 7,
The hydrothermal decomposition apparatus characterized in that the harmful substance is a pharmaceutical product, an agrochemical product, a chemical product, or a slurry containing these. In any one of Claims 1 thru | or 9,
The water is characterized in that the reaction tower comprises a cylindrical primary reaction tower and a secondary reaction tower which is installed on the downstream side of the primary reaction tower and in which a pipe is spirally wound or cylindrical. Pyrolysis device. In the hydrothermal decomposition method of detoxifying harmful substances by hydrothermal reaction while supplying an alkaline solution in the subcritical region,
When cooling the decomposition solution after hydrothermal decomposition,
A hydrothermal decomposition method characterized by preventing adhesion of scale that occurs during cooling using the alkaline solution. In claim 11,
Water for cooling the decomposition treatment liquid is cooled by two or more coolers, the supply of the decomposition treatment liquid to the cooler to which the scale is attached is stopped, and the attached scale is removed by supplying an alkaline solution. Thermal decomposition method. In claim 11 or 12,
A hydrothermal decomposition method comprising returning a decomposition treatment liquid containing an alkaline solution to a reaction tower for performing a hydrothermal reaction. In the hydrothermal decomposition method of detoxifying harmful substances by hydrothermal reaction while supplying an alkaline solution in the subcritical region,
When cooling the decomposition solution after hydrothermal decomposition,
A hydrothermal decomposition method comprising diluting a decomposition treatment solution with the water to prevent adhesion of scale that occurs during cooling.

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