JP2002058984A - Treating method by supercritical water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treating method by supercritical water which is capable of adequately treating various materials under the same treating condition. SOLUTION: In treating the materials by using the supercritical water, the materials are classified by the degrees of difficulty of the treatment by the supercritical water and are inclosed into a treating container in such a manner that the degrees of the difficulty of the treatment by the supercritical water are kept nearly constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for performing processing such as decomposition using supercritical water.

[0002]

2. Description of the Related Art Various polymer materials such as cross-linked polyethylene are used as covering materials for electric wires and cables. Since these are not easily decomposed in nature, their disposal after disposal has become a problem. In addition, such polymer materials are mixed with garbage and the like in household waste discharged from homes and the like, and there is a problem in the treatment thereof.

[0003] For this reason, various processing techniques and reuse techniques have been developed, such as a technique for thermally decomposing recovered polymer materials to oil and a technique for pulverizing and pulverizing the polymer materials to use as a filler for molding materials. Have been. However, these methods have problems such as high cost and limited types and uses of raw materials, and have not yet been widely used.

Under these circumstances, a method has recently been devised in which a polymer material is decomposed using water in a critical state or subcritical state as a reaction solvent. Attention has been paid to its ability to be recovered as a medium molecular compound.

[0005]

However, in the conventional processing technology using supercritical water, it is necessary to change the processing conditions each time the type of the object to be processed changes, and the efficiency is reduced. There was a problem of bad.

[0006] That is, appropriate treatment conditions with supercritical water differ depending on the type, properties, amount and the like of the material to be treated. Therefore, in order to perform proper processing, it is necessary to set processing conditions according to the material. However, conventionally, this point has not been particularly taken into consideration, and it has been necessary to change the processing conditions and perform the processing each time the workpiece changes.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a processing method using supercritical water, which can perform appropriate processing on various objects under a single processing condition. With the goal.

[0008]

Means for Solving the Problems In order to achieve the above object, the method for treating with supercritical water according to the present invention provides a method for treating an object to be treated with supercritical water as described in claim 1. The object to be treated is separated according to the difficulty of the treatment with supercritical water, and the treatment is performed by enclosing the treatment object in a treatment container in which the difficulty of the treatment with supercritical water is substantially constant.

The supercritical water referred to here is a supercritical water in a strict sense, that is, a critical temperature of 374 ° C. and a critical pressure of 22.
It does not mean only supercritical water exceeding 1 MPa, but includes so-called subcritical water.

In the method for treating with supercritical water according to the present invention, the objects to be treated are separated according to the difficulty of treatment with supercritical water, and sealed in a treatment vessel in which the difficulty of treatment with supercritical water is almost constant. Therefore, appropriate processing can always be performed under the same conditions even if the type of the object to be processed changes. That is, appropriate processing can be performed on a variety of workpieces under a single processing condition.

According to the present invention, as described in claim 2, the treatment of the object to be treated with supercritical water is performed by opening an inlet for introducing the object to be treated at the upper end and opening the inlet at the lower end. A preload chamber having an opening for discharging the processed material, and an upper end connected to the outlet of the preload chamber and opening an inlet for introducing the workpiece discharged from the outlet, A processing chamber having an opening at the lower end for discharging the object to be processed, and an inlet connected to an outlet of the processing chamber at the upper end for introducing the object discharged from the outlet. , A decompression chamber having an opening at the lower end for discharging the object to be treated, opening and closing means for selectively opening and closing each of the introduction port and each of the discharge ports, and a water supply to the precompression chamber. A pre-pressurizing chamber pressurizing means for pressurizing by means of It is particularly useful when applied to a method performed by a processing apparatus having a supercritical water region forming means for continuously forming a region and a decompression chamber pressurizing means for pressurizing the decompression chamber with water. .

That is, in such a method, the object to be treated is contacted with the supercritical water in the treatment chamber and treated, and the introduction of the object to the treatment chamber and the discharge from the treatment chamber are as follows. When an object to be treated is introduced or discharged, it is intermittently pressurized and depressurized, and is performed through a precompression chamber and a decompression chamber, so that a supercritical water region is always formed and maintained in the treatment chamber. This has the advantage that the object can be continuously and efficiently processed. However,
When the workpiece changes, the processing conditions must be changed,
This leads to a decrease in efficiency. By applying the present invention, there is no need to change such processing conditions, so that desired and efficient processing can be performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a processing apparatus using supercritical water used in the present embodiment.

In FIG. 1, reference numeral 10 denotes a cylindrical processing tower. The processing tower 10 has, in order from the top, inlets 21, 31, and 41 for introducing the object 11 to the upper end, respectively.
And a precompression chamber 20, a processing chamber 30, and a decompression chamber 40 having discharge ports 22, 32, 42 for discharging the workpiece 11 at the lower end. Outlet 22 of preload chamber 20
The inlet 31 of the processing chamber 30, the outlet 22 of the processing chamber 30, and the inlet 41 of the decompression chamber 40 are each provided with a common valve 5.
Valves 53 and 54 are connected to the inlet 21 of the preload chamber 20 and the outlet 42 of the decompression chamber 40, respectively. Below the processing tower 10, a receiver 50 is provided for receiving the object 11 to be processed and discharged from the discharge port 42 of the decompression chamber 40.

The processing chamber 30 is a processing chamber using supercritical water. The processing chamber 30 is vertically divided into approximately three equal parts, and a preheating region 33, a supercritical water region 34, and a cooling region 35 are formed in this order from the top. ing. That is, a heater 36 is disposed below the preheating region 33 and on the outer periphery of the supercritical water region 34, and a cooling pipe 37 is provided on the outer periphery of the cooling region 35. The cooling pipe 37 is connected to the processing chamber 30.
And a part of a pipe 60 for supplying pure water into the inside. The pure water passes through a cooling pipe 37 by a pump 62 from a pure water tank 61 containing the pure water, and is substantially in the preheating region 33. The water is supplied into the processing chamber 30 through a pure water supply port opened at an intermediate portion. Note that a preheater 38 for preheating the pure water is provided near the pure water supply port of the pipe 60.

The lower part of the processing chamber 30 includes a processing chamber 30.
A pipe 63 for discharging heated and pressurized pure water, gas and liquid generated by the processing, and the like is connected. That is, the other end of the pipe 63 is connected to the gas-liquid separator 65 via the cooler 64, and the heated and pressurized water discharged from the processing chamber 30 is cooled by the cooler 64 and condensed. Then, the gas component and the liquid component are separated by the gas-liquid separator 65, and are respectively discharged or collected to the outside. In the figure, 66 is a pressure reducing valve.

The precompression chamber 20 and the decompression chamber 40 are provided in the processing chamber 3
The object pressure is maintained at a normal temperature to a low temperature of about 40 ° C. to maintain the internal pressure of the object 11 when the object 11 is introduced and discharged. Pressurized and depressurized. That is, pipes 69a and 69b for supplying pure water from a pure water tank 67 containing pure water by a pump 68, and a pressure reducing valve 70a for discharging pure water are provided in the preload chamber 20 and the decompression chamber 40. , 70b are connected to pipes 71a, 71b. The preload chamber 20 is also supplied with pure water from a branch pipe 72 branched from the pipe 60.

Further, in this apparatus, the precompression chamber 20 and the three areas constituting the processing chamber 30 as described above, that is, a preheating area 33, a supercritical water area 34 and a cooling area 35, and a decompression chamber 40 Are provided with object holding means 73, 74, 75, 76, 77 for holding the object 11 in the chamber or the area for a required time. Among these, the preloading chamber 20, the cooling area 35 of the processing chamber 30, and the holding means 73, 7 located in the decompression chamber 40.
Reference numerals 6 and 77 also have a function of preventing the object 11 from being directly in contact with the valves 51, 52, and 54, thereby preventing the functions thereof from being impaired.

Next, the object A (crosslinked polyethylene sheet; 10 mm × 10 mm × 1 mm, weight about 0.1
g) and the object B (cross-linked polyethylene cylinder; outer diameter)
15 mm, length 100 mm, weight about 18 g) is decomposed into uncrosslinked polyethylene with supercritical water.

First, the valve 53 connected to the inlet 21 of the preload chamber 20 is opened, the other valves 51, 52 and 54 are closed, and the processing chamber 30 and the decompression chamber 40 are closed. Next, while the heater 36 is energized, the pump 62
To supply the pure water heated by the preheater 38 from the pure water tank 61 to the processing chamber 30, and into the processing chamber 30,
A preheating region (internal pressure 40 MPa, temperature 40 to 300 ° C.) 33, a supercritical water region (internal pressure 40 MPa, temperature 400 ° C.) 34 and a cooling region (internal pressure 40 MPa, temperature 400 to 40 ° C.) 35 are formed. In addition, the pump 68 is started to supply low-temperature pure water at room temperature to about 40 ° C. from the pure water tank 67 to increase the internal pressure of the decompression chamber 40 to 40 MPa which is the same as the internal pressure of the processing chamber 30.

In this state, the object A to be treated is
2 g of a filter (glass filter (6 mm) / silica gel (6 mm) / glass filter (6 m) having a three-layer structure as shown in FIG.
m)) A processing container 100A (outer diameter 32 mm, height 300 mm, inner volume about 137) having a structure in which the outside of a cylindrical stainless steel (1 mm thick) container 104 made of 103 is coated with a resin 105.
cm ³ , coating resin; polystyrene (2 mm thick)). The preload chamber 20 is at normal temperature and normal pressure.
The loaded workpiece A is held by the workpiece holding means 73 at a position in the preload chamber 20 that is separated from the valve 51.

After the object A is charged, the valve 53 is closed, the pump 68 is started, and the temperature of the pure water tank 67 is reduced to a range between room temperature and 40 ° C.
The internal pressure of the preload chamber 20 is increased by supplying pure water at a low temperature. When the internal pressure of the preload chamber 20 becomes substantially the same as the internal pressure of the processing chamber 30, the valve 51 is opened to release the holding by the processing object holding means 73.

The workpiece A falls from the preload chamber 20 into the processing chamber 30 by its own weight, is held in the preheating area 33 by the workpiece holding means 74, and is preheated (preheating time is 10 minutes).
Thereafter, when the holding by the processing object holding means 74 is released, the processing object A falls into the supercritical water region 34, is held by the processing object holding means 75, and is decomposed by the supercritical water (processing time). in 30 minutes). After the processing, the workpiece A is further released into the cooling area 35 by the release of the holding by the workpiece holding means 75, and is held by the workpiece holding means 76. When the valve 52 is opened and the holding by the processing object holding means 76 is released when the processing object A is cooled to a temperature close to the normal temperature in the cooling area 35, the processing object A is brought to the same pressure as the internal pressure of the processing chamber 30 in advance. It falls by its own weight into the depressurized chamber 40, which is being pressurized, and is held by the processing object holding means 77.

The object to be treated A is thus placed in the decompression chamber 40.
When it falls into the inside, the valve 52 is closed and the decompression chamber 40
Evacuate the pure water inside and reduce the pressure. When the internal pressure of the decompression chamber becomes normal pressure, the valve 54 is opened and the holding by the object holding means 77 is released, and the object A is processed by its own weight.
And fall into the receiver 50 to be collected.

The resin solid content thus recovered is about 20 g.
When the gel fraction and the melting point were measured, the gel fraction was 0% and the melting point was 110 ° C. From this, the crosslinked polyethylene sheet of the object to be treated A is modified into uncrosslinked polyethylene and collected (recovery rate of about 100%).
It is estimated that all the coating resin of A was decomposed and discharged from the processing chamber 30 through the pipe 63.

Similarly, the workpiece B is charged into the preload chamber 20 and processed under the same processing conditions as those for the workpiece A. However, the processing object B is a cylindrical processing container 100B (material: polyethylene, outer diameter 32 mm, height 300 mm, volume about 80 cm ³ , coating resin: polyethylene terephthalate (5 mm thick) as shown in FIG. ). This processing container 100B has the same configuration as the processing container 100A shown in FIG. 2A except that the type and thickness of the coating resin 105 outside the stainless steel container 104 are different.

The resin solid content recovered in the receiver 50 by this treatment was about 18 g, and its gel fraction and melting point were 0% and 110 ° C., respectively. From this, the crosslinked polyethylene columnar material of the processing object B is modified into an uncrosslinked polyethylene similar to the crosslinked polyethylene sheet of the processing object A and collected (recovery rate of about 100%), and the coating resin of the container 100B is recovered. Are all disassembled and the piping 6
It is estimated that they were discharged through No. 3.

As described above, according to the present embodiment, crosslinked polyethylene molded articles having different weights and shapes can be treated under the same conditions to be decomposed into desired uncrosslinked polyethylene.

The present invention is not limited to the above-described example. For example, in the above-described example, a container for enclosing an object to be processed is made of a material having the same outer shape but different material and volume. However, any processing container may be used as long as the degree of difficulty in treating the object to be treated with supercritical water is substantially constant, and is not particularly limited to the above.

The above example is an example in which the present invention is applied to the decomposition treatment of cross-linked polyethylene into uncross-linked polyethylene. Needless to say, it can be applied to various treatments using water.

[0032]

As described above, according to the present invention,
Separating the object to be treated according to the difficulty of the treatment with supercritical water,
Since the processing is performed by enclosing in a processing vessel where the difficulty of processing with supercritical water is almost constant, it is possible to perform appropriate processing on various workpieces under a single processing condition In addition, it is possible to improve the processing efficiency using supercritical water.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an example of a processing apparatus using supercritical water used in the present invention.

FIG. 2 is a sectional view showing an example of a processing container used in the present invention.

[Explanation of symbols]

 11: Workpiece 20: Preload chamber 21, 31, 41 ... Inlet 22, 32, 42 ... Discharge port 30 ... Processing chamber 33 ... Preheating area 34 ... Super Critical water area 35 Cooling area Heater 40 Decompression chamber 51, 52, 53, 54 Valve 61, 67 Pure water tank 62, 68 Pump 73 74, 75, 76, 77 ... object to be processed holding means 100A, 100B ... processing container

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B09B 3/00 304P (72) Inventor Kiyoji Furumura 1 Electric Power Research Laboratory, Chubu Electric Power Co., Inc. 2-1-1-1 Sakae Electric Wire & Cable Co., Ltd. F-term (reference) 4D004 AA01 AA06 AA07 AA46 AC04 CA22 CA39 CB04 CC03 DA02 DA06 DA07

Claims (2)

[Claims] In treating an object to be treated with supercritical water, the object to be treated is classified according to the difficulty of treatment with supercritical water so that the difficulty of treatment with supercritical water is substantially constant. A processing method using supercritical water, wherein the processing is performed by enclosing in a processing container. 2. The treatment of the object to be treated with supercritical water comprises: opening an inlet at an upper end for introducing the object to be treated;
A preload chamber having an outlet at the lower end thereof for discharging the workpiece, and an inlet connected to the outlet of the preload chamber at the upper end for introducing the workpiece discharged from the outlet. And a processing chamber having an opening at the lower end for discharging the object to be processed, and an upper end connected to an outlet of the processing chamber to introduce the object discharged from the discharging port. A decompression chamber that opens an inlet for discharging a discharge port for discharging the object to be processed at the lower end, and opening and closing means for selectively opening and closing each of the inlet and each outlet, A precompression chamber pressurizing unit for pressurizing the precompression chamber with water, a supercritical water region forming unit for continuously forming a supercritical water region in the processing chamber, and a unit for pressurizing the decompression chamber with water. The processing is performed by a processing apparatus having a decompression chamber pressurizing means. Processing method according to claim 1 object to be processed, wherein.