JP2001232381A - Supercritical water treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supercritical water treating apparatus for supercritically water-treating the liquid to be treated containing PCB and the like in high concentration, capable of stable operation for a long period. SOLUTION: The supercritical water treating apparatus has a reactor 12 provided with an outer cylindrical body 12a consisting of a vertically cylindrical pressure vessel bearing the pressure necessary for supercritical water treatment and a reaction cartridge 12b made of titanium or a titanium alloy and provided within the outer cylindrical body 12a as an inner cylindrical body mutually communicating with the inner part of the outer cylindrical body and introducing pressure balancing air from a pressure balancing air introducing tube 30 into an annular part 12c between the outer cylindrical body 12a and the reaction cartridge 12b. The reactor is provided with a tube-shaped electric resistance heat generating body 36 capable of holding the temperature of the reaction cartridge at 380 deg.C and a cable 38 connected to an emergency power source (not illustrated) capable of supplying power at all times and energizing the electric resistance heat generating body 36 as a heating means 35 for heating the reaction cartridge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercritical water treatment apparatus for treating an organic chlorine compound such as PCB, and more particularly, to a PC for producing high-concentration hydrochloric acid during supercritical water treatment.
The present invention relates to a supercritical water treatment apparatus capable of stably treating an organic chlorine compound with supercritical water without causing corrosion of the apparatus even if the organic chlorine compound such as B is used.

[0002]

2. Description of the Related Art With increasing awareness of environmental issues,
As one of application fields of a supercritical water treatment apparatus, attention has been paid to decomposition and detoxification of environmental pollutants. A supercritical water treatment device is a harmful hard-to-decompose organic substance, such as PCB (polychlorinated biphenyl), which is difficult to decompose in the prior art by a supercritical water reaction utilizing the properties of a reaction medium of supercritical water. ), A device that decomposes dioxins, organic chlorinated solvents, and the like and converts them into harmless products such as carbon dioxide, water, and inorganic salts.

[0003] Supercritical water refers to water that is in a supercritical state, that is, water that is beyond the critical point of water, and more specifically, has a critical temperature, that is, a temperature of 374.1 ° C or higher, and Of water under a critical pressure of 22.04 MPa or more. Supercritical water has a high ability to dissolve organic substances and can completely dissolve non-polar substances, which are abundant in organic compounds, but has a very low ability to dissolve inorganic substances such as metals and salts. The supercritical water can be mixed with a gas such as oxygen or nitrogen at an arbitrary ratio to form a single phase.

Referring to FIG. 8, a basic configuration of a conventional supercritical water treatment apparatus for treating a liquid to be treated containing an organic chlorine compound by a supercritical water reaction will be described. FIG.
Is a flow sheet showing the configuration of a conventional supercritical water treatment apparatus. Conventionally, the supercritical water treatment apparatus 80 is said to be the most suitable apparatus for oxidative decomposition of organic chlorine compound-based hardly decomposable organic substances such as salts that precipitate during supercritical water treatment. This is a so-called moder process type apparatus that includes a mold reactor 81 and sediments and separates salts that precipitate as solids in supercritical water at the lower part of the reaction vessel.

[0005] As shown in FIG. 8, a condition above the critical point of water, that is, a supercritical condition is maintained in the upper part of the reactor 81, and a supercritical water area 82 for retaining supercritical water is formed.
Reactor 81 via virtual interface 83 with supercritical water area 82
A subcritical water area 84 that is maintained at a temperature lower than the critical temperature of water and retains the subcritical water is formed at a lower part of the water.
An inflow pipe 85 is connected to the upper part of the reactor 81 so that the liquid to be treated and the oxidizing agent to be subjected to the supercritical water treatment flow into the supercritical water area 82. The inflow pipe 85 has a liquid to be treated line 86 for supplying a liquid to be treated having an organochlorine compound to be treated by the supercritical water reaction, an air line 87 for supplying air as an oxidizing agent for oxidizing organic substances, and , A supercritical water line 88 for feeding supercritical water or makeup water for generating supercritical water.

A neutralizing agent line 89 for supplying an alkali neutralizing agent for neutralizing hydrochloric acid generated by an organic chlorine compound in the liquid to be treated is connected to the liquid line 86 to be treated. The liquid to be treated and the neutralizing agent are supplied to the reactor 81 through the inflow pipe 85, atomized downward by air as the oxidizing agent, and sprayed into the supercritical water area 82 in the reactor 81. You. Organochlorine compounds and other organic substances in the sprayed liquid to be treated are instantaneously oxidized and decomposed in the supercritical water area 82. In the process of the supercritical water reaction, the chlorine of the organic chlorine compound contained in the liquid to be treated is neutralized with the alkali neutralizer to form a salt, and shifts from the supercritical water region to the subcritical water region.

A treatment liquid line 90 is further connected to the upper part of the reactor 81, and organic substances in the liquid to be treated are mainly converted into water and carbon dioxide by a supercritical water reaction, and a supercritical water area 82 is formed together with the treatment liquid. From the processing solution line 90. Although not shown, the processing liquid line 90 is provided with a cooler for cooling the processing liquid, a pressure control valve for controlling the pressure in the reactor 81, a gas-liquid separator, and the like. Note that, if necessary, an auxiliary fuel line for supplying auxiliary fuel to the supercritical water area may be connected to the inflow pipe 85.

On the other hand, a subcritical water line 91 and a subcritical drainage line 92 are connected to a lower portion of the reactor 81, and the subcritical water line 91 supplies subcritical water to a subcritical water area 84, The line 92 discharges the subcritical water in which the salt generated by the supercritical water reaction and the neutralization reaction is dissolved from the subcritical water area 84 as wastewater. Although not shown, the subcritical drain line 92 is provided with a cooler for lowering the temperature of the subcritical wastewater to a predetermined temperature, a decompression device for reducing the pressure to a predetermined pressure, and a gas-liquid separation / solid-liquid separation device.

[0009]

However, the following problems have been encountered when attempting to treat a liquid to be treated containing high-concentration PCB with supercritical water using the above-described conventional supercritical water treatment apparatus. First, as before, a reaction temperature close to the critical temperature of water (374.1 ° C.), ie, 450 ° C. to 5 ° C.
At a temperature in the range of 00 ° C., it was extremely difficult to reduce the PCB content of the processing solution to 3 ppb or less, which is allowed by the discharge standard. Conversely, it is expected that higher reaction temperatures will be required.

Second, there are two problems caused by a two-zone system in which a supercritical water area and a subcritical water area are formed in a reactor. One problem is that corrosion of the reactor wall, particularly near the boundary between the two regions, is remarkable. Normally, the neutralization reaction proceeds concurrently with the supercritical water reaction, so that no corrosion problem occurs. However, if the neutralization is incomplete, corrosion becomes a problem. In the conventional method, since a high-temperature supercritical water area and a low-temperature subcritical water area exist in the reactor, a severely corrosive area always exists, which is an obstacle to the practical use of PCB supercritical water treatment. Had become. Second, if the spraying of the liquid to be treated is not good in the conventional method, the PC
B or the like may enter the subcritical water area 84 without being completely decomposed. In this case, since the temperature of the subcritical water area is low, undecomposed substances mixed in the subcritical water area remain without being decomposed and are discharged as wastewater from the subcritical water area. There was a problem that the content exceeded the emission standard.

Third, when the concentration of organic chlorine in the liquid to be treated is high, as in the case of treating PCB, there are many unclear points in the mechanism of the neutralization reaction and salt formation separation, and the supercritical In the water treatment, the hydrochloric acid generated from the organic chlorine in the PCB is completely neutralized in the reactor as in the conventional method.
In practice, it was difficult and lacked certainty.

Therefore, a neutralization and quenching section for injecting an alkali aqueous solution into the treatment liquid and quenching and neutralizing the treatment liquid is provided at the outlet or downstream of the reactor, and an alkaline aqueous solution is injected outside the reactor to neutralize and quench the treatment liquid. Attempted. However, in this method, since the processing liquid flows out of the reactor and enters the neutralization quenching section, it is neutralized only after the process, and a large amount of hydrochloric acid generated by the supercritical water reaction is present in the reactor. for that reason,
Nickel alloys such as Inconel 625, which have been conventionally used as a corrosion-resistant material on the inner wall of a reactor, have a problem in that they are significantly corroded by hydrochloric acid and cannot be used. Further, even in the quenching neutralization section, there is a problem that the corrosion of the pipe is remarkable up to the point where the neutralization reaction between the alkaline aqueous solution and the processing solution is completed, and it is difficult to use the nickel alloy for the pipe for a long time. .

Further, attempts have been made to employ a pressure balanced reactor in combination with a neutralization and quenching section. As shown in FIG. 9, the pressure-balanced reactor 100 has an outer cylinder 101 formed as a pressure vessel and a reaction cartridge 102 provided as an inner cylinder communicating with each other inside the outer cylinder 101. It is formed as a heavy cylinder. From the inlet nozzle 103 connected to the inflow pipe 85 (see FIG. 8), the liquid to be treated and an oxygen-containing gas such as air as an oxidizing agent are caused to flow into the reaction zone 104 in the reaction cartridge 102, and are used for pressure balancing. Annular part 1 between outer cylinder 101 and reaction cartridge 102 from air inlet 105
At 06, for example, air is supplied as a pressure balancing gas. The pressure balancing air is supplied to the annular portion 1 through the upper gap 107 between the pressure vessel 101 and the reaction cartridge 102.
06 flows into the reaction zone 104 and is consumed as a part of the oxidizing agent.

The reaction zone 104 in the reaction cartridge 102
Is oxidized and decomposed by oxygen in the air in the supercritical water and flows out of the reactor outlet pipe 108. The neutralization quenching unit is provided on the inside or outside of the pressure vessel 102 downstream of the reaction cartridge 102. In the conventional pressure balanced type reactor, there is almost no pressure difference between the inside and the outside, so that the reaction cartridge 102 can be formed with a small thickness as a non-pressure vessel, so that the reaction cartridge 102 can be made of an expensive corrosion-resistant metal, for example, a nickel alloy such as Inconel 625. There is an advantage that the cost is not increased even if it is formed by using Also,
Since the annular portion 106 is not in a highly corrosive atmosphere, the outer cylinder 101 does not necessarily need to be formed of the same material as the reaction cartridge 102, and is usually formed of heat-resistant carbon steel or stainless steel. However, there is a problem that even a reaction cartridge formed of an expensive nickel alloy is significantly corroded by hydrochloric acid and must be replaced in a short time.

Accordingly, an object of the present invention is to provide a liquid to be treated containing a high concentration of PCB or the like at a discharge standard of 3 ppb.
An object of the present invention is to provide a supercritical water treatment apparatus having the following PCB concentration, which can be operated stably for a long period of time.

[0016]

In order to achieve the above object, the present inventor has set forth the following object. (1) The present inventors have determined that a liquid to be treated having a high organic chlorine concentration such as PCB is supercritical to a PCB concentration of 3 ppb, which is allowed on a discharge standard. It was considered necessary to establish a reaction temperature at which water treatment was possible, and (2) to establish a reactor material that could be used at that temperature.

[0017] First, the relationship between the decomposition rate of PCB and the reaction temperature of the supercritical water reaction was investigated in order to reduce the PCB content of the treatment liquid produced by treating PCB with supercritical water to 3 ppb or less. As a result, a reaction pressure of 23 MPa, and 2
Under the conditions of a reaction time of not less than 1 minute and not more than 4 minutes, when the reaction temperature is 500 ° C., the PCB concentration is not less than 3 ppb and cannot satisfy the discharge standard of 3 ppb, and the reaction temperature is 550 ° C. and 650 ° C. It was found that by setting the temperature to ° C, the PCB concentration could be reduced to 3 ppb or less. When the reaction temperature is 500 ° C., even if the reaction time is 4 minutes or longer, the PCB concentration is 3 p.
It was also found that it could not be less than pb.

That is, the reaction temperature is 550 ° C. or higher and 650 ° C.
By setting the temperature within the range of not more than 3 ° C., the PCB or P is adjusted so that the PCB concentration in the processing solution becomes 3 ppb or less.
A liquid to be treated containing an organic chlorine compound comprising a CB-like compound can be oxidatively decomposed by a supercritical water reaction. PC
The B-like compound is a compound having a chemical structure substantially similar to that of PCB, such as dioxins, chlorobenzene compounds, chlorophenols, and the like.

Next, in order to select a material having corrosion resistance to high-concentration hydrochloric acid at a temperature of 550 ° C. or higher, reactors are made of various materials, and the PCB is actually treated with supercritical water to obtain a material. A corrosion test was performed to evaluate the corrosion resistance. By the way, for example, when a PCB having a purity of 100% from trichloride to pentachloride is subjected to a supercritical water reaction treatment, the concentration of the generated hydrochloric acid is about 10% to 15% by mass. Therefore, in the first corrosion test, the conditions for treating the PCB with supercritical water were a pressure of 22 MPa and a reaction temperature of 6 MPa.
The rate of corrosion of various materials by an aqueous solution of hydrochloric acid having a hydrochloric acid concentration of 20% by mass was set at 00 ° C., and measured as follows.

First, autoclave-shaped reactors were prepared from the materials shown in Table 1, respectively, and an aqueous hydrochloric acid solution having a hydrochloric acid concentration of 20% by mass was accommodated in each reactor. C. and maintained at that temperature for 500 to 600 hours, and the corrosion rate of the vessel wall of each reactor was measured. When the corrosion rate of the vessel wall is less than 1 mm / year, the material is optimum, when the corrosion rate is 1 mm / year or more and 5 mm / year, the material is applicable, and when the corrosion rate exceeds 5 mm / year, the material is not applicable. According to the corrosion test criteria, based on the corrosion rate of the container wall,
The results shown in Table 1 below were obtained.

Table 1 Material Judgment Inconel 625 Not applicable Hastelloy 276 Not applicable Platinum Not applicable Titanium Optimum Tantalum Not applicable Alumina Not applicable (slow corrosion rate, but cracking)

Next, in the second corrosion test, the pressure was 22 MPa, and the temperature was lower than the condition of the first corrosion test.
The temperature was set to 00 ° C., and the corrosion rate by a hydrochloric acid aqueous solution having a hydrochloric acid concentration of 20% by mass was measured. Autoclave-shaped reactors were made from the same materials as in the first corrosion test, and the hydrochloric acid concentration was 2
A 0% by mass aqueous hydrochloric acid solution is accommodated in each reactor, and the aqueous hydrochloric acid solution in the reactor is heated to a temperature of 400 ° C. at a pressure of 22 MPa and maintained at that temperature for 500 to 600 hours. The corrosion rate of the wall was measured. According to the same corrosion test criteria as the first corrosion test, the results shown in the following Table 2 were obtained based on the corrosion rate of the container wall.

Table 2 Materials Judgment Inconel 625 Not applicable Hastelloy 276 Not applicable Platinum Not applicable Titanium Applicable Tantalum Optimum Alumina Not applicable (slow corrosion rate, but cracking)

Further, in the third corrosion test, the pressure and the temperature are each lower than the condition of the second corrosion test by 18 MPa.
a, and the corrosion rate with a hydrochloric acid aqueous solution having a hydrochloric acid concentration of 20% by mass at a temperature of 350 ° C. was measured. Autoclave-shaped reactors were each made of the same material as in the first corrosion test, and a hydrochloric acid aqueous solution having a hydrochloric acid concentration of 20% by mass was accommodated in each reactor.
The hydrochloric acid aqueous solution in the reactor is heated to 350 ° C. at a pressure of 18 MPa.
And the temperature was maintained for 500 to 600 hours, and the corrosion rate of the vessel wall of each reactor was measured. According to the same corrosion test criteria as the first corrosion test, the results shown in the following Table 3 were obtained based on the corrosion rate of the container wall.

Table 3 Materials Judgment Inconel 625 Not applicable Hastelloy 276 Not applicable Platinum Not applicable Titanium Not applicable Tantalum Optimum Alumina Not applicable (slow corrosion rate, but cracking) In order to examine in more detail, as a fourth corrosion test, 38
When the corrosion test was performed at 0 ° C., 450 ° C., and 500 ° C. in the same manner as the first to third corrosion tests, the results shown in Table 4 were obtained. In addition, a reactor made of a titanium alloy instead of titanium and a tantalum alloy instead of tantalum was manufactured, and the same first to fourth corrosion tests were performed. As a result, the same results as those of titanium and tantalum were obtained, respectively. Was completed.

The following conclusions can be obtained from the results of the first to fourth corrosion tests. (1) Titanium can be applied to a container wall that comes into contact with a concentrated hydrochloric acid aqueous solution having a temperature of 380 ° C. or higher, and there is no material which can be applied only to titanium at 500 ° C. or higher. However, at a temperature of 350 ° C. or less, the corrosion rate of titanium is so high that it cannot be applied. Titanium forms an oxide film, which serves as a protective film, and therefore has high corrosion resistance. In particular, at a temperature of 380 ° C. or more, the formation of an oxide film is good, and the corrosion resistance is further enhanced. Therefore, a reactor wall having a temperature of 380 ° C. or higher, for example, a reaction temperature of 55 ° C.
Titanium can be suitably applied to the reactor wall of the PCB treatment reactor at 0 ° C. (2) When forming the reaction cartridge from titanium,
When the temperature of the reaction cartridge is lower than 380 ° C., there is a possibility that the reaction cartridge is corroded by a corrosive fluid such as hydrochloric acid. It is necessary to maintain the reaction cartridge at least at 380 ° C. even when the reaction is stopped or when the operation of the apparatus is urgently stopped.

In order to achieve the above object, based on the above-mentioned findings, a supercritical water treatment apparatus according to the present invention is provided with an outer shell formed as a pressure vessel, and disposed in the outer shell to communicate with each other. A pressure-balanced reactor formed as a double cylinder with a reaction cartridge consisting of an inner shell, and a liquid to be treated containing an organochlorine compound is introduced into supercritical water in the reaction cartridge, and the temperature is 550 ° C. or higher. In a supercritical water treatment apparatus that oxidizes and decomposes with an oxidizing agent at a temperature of 650 ° C. or less and causes a treatment liquid having a lower concentration of an organic chlorine compound than a liquid to be treated to flow out of a reactor, at least the inner surface layer of the reaction cartridge has a titanium layer or a titanium layer. Formed of an alloy layer, and heated to 380 ° C. from outside the reaction cartridge
It is characterized by having a heating means for maintaining the above.

In the present invention, at least the inner surface layer of the reaction cartridge which comes into contact with a corrosive fluid such as hydrochloric acid may be formed of a titanium layer or a titanium alloy layer. Of course, the entire reaction cartridge may be formed of a titanium layer or a titanium alloy layer. In the present invention, the heating temperature of the reaction cartridge may be 380 ° C. or higher, but may be 380 ° C. in consideration of economy, and it is not necessary to exceed 380 ° C., for example, 500 ° C., which is too high. However, it is necessary that the temperature of the inner wall of the cartridge does not become lower than 380 ° C. due to heat exchange. There is no limitation on the heating means, and for example, a heating means of a known configuration using an electric heating method or a heating method using a heat medium can be used. It is also possible to cut off the annular portion (gap between the cartridge and the external pressure vessel) through which the reaction cartridge and the balance air flow. If the device is cut off, the corrosive fluid (not shown) inside the cartridge does not flow out to the annular portion outside the cartridge even when the device is stopped in an emergency, so that a heater such as a heating coil can be protected.

For example, in a preferred embodiment of the present invention, the heating means includes an electric resistance heating element provided along the outer peripheral wall of the reaction cartridge and a current supply means for supplying a current to the electric resistance heating element. I have. The heat generated by the electric resistance heating element is transferred to the reaction cartridge, whereby the reaction cartridge is constantly maintained at 380 ° C. or higher. The electric resistance heating element is, for example, an electric resistance heating element in which an electric resistance heating wire such as a Ni-Cr electric resistance wire is covered with an electric insulating layer such as MgO and further surrounded by a protective tube such as a metal tube. Alternatively, a strip-shaped or sheet-shaped electric resistance heating element having substantially the same structure can be used.

The heating means includes an induction coil wound along the outer peripheral wall of the reaction cartridge and a current supply means for supplying current to the induction coil, or a current supply means for supplying current to the reaction cartridge itself. A supply means is provided. An induction heating method may be applied in which an induction coil is wound along the outer peripheral wall of the reaction cartridge, an electric current is applied to the induction coil, an induction current is induced in the reaction cartridge, and heating is performed by resistance heating generated by the induction current. Further, a direct heating system may be used in which the reaction cartridge itself is energized, heat is generated by the electric resistance of the reaction cartridge itself, and the reaction cartridge is heated.

In another preferred embodiment of the present invention, the heating means includes a jacket provided outside the reaction cartridge or a coiled tube wound outside the reaction cartridge, and a heating medium supplied to the jacket or the tube. A heating medium supply means for supplying a heating medium having a temperature exceeding 380 ° C. to a jacket or a flexible tube, and heating the reaction cartridge to 380 ° C. or more by the heat of the heating medium. There is no limitation on the type of the heat medium, and for example, supercritical water having a temperature exceeding 380 ° C. or high-temperature air having a temperature exceeding 380 ° C. may be used. Further, as a heating means, a heater for heating air is provided, and high-temperature air exceeding 380 ° C. obtained by heating is supplied between the outer shell and the reaction cartridge as pressure balancing air. Is also good.

In a further preferred embodiment of the present invention, the neutralizing means is provided in the processing liquid pipe immediately downstream of the connection between the processing liquid pipe for discharging the processing liquid from the reactor and the reactor. This can prevent corrosion of equipment and piping downstream of the reactor due to an acidic compound such as hydrochloric acid.

[0033]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment 1 This embodiment is an example of an embodiment of a supercritical water treatment apparatus according to the present invention, and FIG. 1 is a flow sheet showing a configuration of a supercritical water treatment apparatus of this embodiment, and FIG. 2 is a cross-sectional view showing the configuration of the reactor. The supercritical water treatment apparatus 10 according to the present embodiment performs P
An apparatus for processing a liquid to be processed containing CB at a high concentration,
As shown in FIG. 1, as a reactor for performing a supercritical water reaction,
A vertical pressure-resistant closed type reactor 12 is provided.
A processing liquid pipe 14 for allowing the processing liquid to flow out of the processing liquid, a neutralization mixer 15, a cooler 16 for cooling the processing liquid to a predetermined temperature, a pressure control valve 18 for controlling the pressure in the reactor 12, and a processing liquid. Is provided with a gas-liquid separator 20 for separating gas into liquid and gas.

The supercritical water treatment apparatus 10 has a supply system for supplying a reactant to be used for the supercritical water reaction to the reactor 12.
A liquid pump 22 whose discharge amount can be adjusted by inverter control or stroke control;
The processing liquid containing PCB is fed into the reactor 12 through the liquid pipe 26 to be processed, and the air is processed as an oxidant through the air inlet pipe 28 and the liquid pipe 26. The solution is fed into the reactor 12. Further, the air compressor 24 is provided with a pressure-balancing air inlet pipe 3 branched from the air inlet pipe 28.
The pressure balancing air is fed into the reactor 12 through 0. The neutralization mixer 15 is a normal line mixing type mixer, and injects and mixes the NaOH aqueous solution supplied from the alkaline aqueous solution supply system 31 into the processing liquid to neutralize the processing liquid. Although not shown, supercritical water or make-up water for generating supercritical water may be replenished to the reactor 12 as necessary, and a heater for heating the make-up water to a desired temperature is provided. You can also.

The supercritical water treatment apparatus 10 includes a temperature control device 32 for controlling the reaction temperature in the reactor 12 to, for example, 550 ° C. by adjusting the flow rate of the liquid to be treated. The temperature control device 32 includes a thermometer 3 that measures the temperature inside the reactor 12, more precisely, inside the reaction cartridge 12a.
The reaction temperature is set within a range from 550 ° C. to 650 ° C. by adjusting the discharge rate of the liquid to be treated 22 based on the temperature of the thermometer 34 to adjust the flow rate of the liquid to be treated. , For example, at 550 ° C. Temperature control device 3
The configuration of 2 is not limited to this. For example, by adjusting the supply flow rate of supercritical water, or by adjusting the supply flow rate of make-up water for generating supercritical water, furthermore, the supply of make-up water By adjusting the temperature, the reaction temperature in the reactor 12 can be controlled in the range of 550 ° C. or more and 650 ° C. or less.

The reactor 12 has the same configuration as the conventional pressure-balanced reactor shown in FIG. 9 except that the reactor 12 is provided with a heating means for the reaction cartridge 12b (however,
For convenience, the reference numerals of the parts of the reactor are different from those in FIG. 9).
That is, as shown in FIG. 2, the reactor 12 is formed of a heat-resistant carbon steel or stainless steel vertical cylindrical pressure vessel having a pressure at the time of supercritical water treatment, for example, having a mechanical strength against 23 MPa. An outer cylindrical body 12a, and a reaction cartridge 12b made of titanium or a titanium alloy provided as an inner cylindrical body communicating with each other inside the outer cylindrical body 12a, and provided between the outer cylindrical body 12a and the reaction cartridge 12b. Annular part 12
Air for pressure balancing is introduced from c into the air supply pipe 30 for pressure balancing.

Further, the reactor 12 of the present embodiment comprises a tubular electric resistance heating element 36 capable of holding the reaction cartridge 12b at 380 ° C. or higher as a heating means 35 for heating the reaction cartridge 12b, A cable 38 connected to an emergency power supply (not shown) in an enabled state and energizing the electric resistance heating element 36; The cable 38 is connected to the electric resistance heating element 36 via the connector 40, and a penetrating portion through which the electric resistance heating element 36 penetrates the outer cylindrical body 12 a is sealed with a seal component 42.

The tubular electric resistance heating element 36 is made of Ni.
An electric resistance heating element in which the electric resistance heating wire such as a Cr electric resistance wire is surrounded by an electric insulating layer such as MgO and further surrounded by a protective tube such as a metal tube, for example, a product made by Sukekawa Electric Name micro heater can be used. The electric resistance heating element 36 and the reaction cartridge 12b
A heat transfer cement, such as Salmon Cement (trade name) manufactured by US Salmon Manufacturing Co., Ltd., is embedded in the gap between the electric resistance heating element 36 and the reaction cartridge 1.
2b can be improved.
Further, instead of the tubular electric resistance heating element 36, for example, a band-shaped or planar electric resistance heating element having a known configuration can be used.

With the above configuration, the electric resistance heating element 36
Transfers the generated heat to the reaction cartridge 12b, and always keeps the reaction cartridge 12b at 380 ° C. or higher. Therefore, even when the operation of the apparatus is stopped and the operation of the apparatus is stopped urgently, the reaction cartridge 12b
Does not drop below 380 ° C. Therefore,
The reaction cartridge 12b made of titanium does not corrode by corrosive fluid such as hydrochloric acid.

Modification of Embodiment 1 In a modification of Embodiment 1, as shown in FIGS. 3A and 3B, a tubular electric resistance heating element 36 is used instead.
The heating means 44 is configured such that a bare Ni.Cr electric resistance wire 48 not covered with an insulating layer is embedded in a heat-resistant heat insulating material layer 46 covering the outer peripheral wall of the reaction cartridge 12b. In yet another variant, the heating means 50
As shown in FIG. 3B, the reaction cartridge 12b
Is covered with a heat-resistant electric insulating film 52, and then the bare Ni.Cr electric resistance wire 5 not covered with the electric insulating layer.
4 and the outside thereof is further covered with a heat-resistant heat insulating material layer 56.

Modification of Embodiment 1 As shown in FIG. 4, the heating means 58 of this modification is an insulating layer along the outer peripheral wall of the reaction cartridge 12b instead of the tubular electric resistance heating element 36. The coated induction coil 60 is wound, an electric current is applied to the induction coil 60 from an emergency power supply via the cable 38, an induced current is induced in the reaction cartridge 12b, and heat is generated in the reaction cartridge 12b by an electric resistance to the induced current. And heat it. Furthermore, it is also possible to directly heat the reaction cartridge 12b, generate heat by the electric resistance of the reaction cartridge itself, and heat the reaction cartridge.

Embodiment 2 This embodiment is another example of the embodiment of the supercritical water treatment apparatus according to the present invention, and FIG. 5 is a sectional view showing the structure of a reactor. The supercritical water treatment apparatus of the present embodiment has the same configuration as the supercritical water treatment apparatus 10 of the first embodiment except that the heating means of the reaction cartridge 12b is different. As shown in FIG. 5, the heating means 62 of the reaction cartridge 12b of the present embodiment is wound around the outer peripheral wall of the reaction cartridge 12b, and is a coiled pipe 64 through which supercritical water flows.
And a supercritical water supply source (not shown) that constantly supplies supercritical water having a temperature exceeding 380 ° C. to the flexible tube 64.
A heat transfer cement such as Salmon Cement (trade name, manufactured by Salmon Manufacturing Co., Ltd., USA) is embedded in the gap between the flexible tube 64 and the reaction cartridge 12b to enhance the heat transfer between the flexible tube 64 and the reaction cartridge 12b. You can also do so.

With the above configuration, the flexible tube 64 transfers the heat of the supercritical water to the reaction cartridge 12b, and keeps the reaction cartridge 12b at 380 ° C. at all times. Therefore,
Even when the operation of the apparatus is stopped and the operation of the apparatus is stopped urgently, the temperature of the reaction cartridge
It does not drop below 0 ° C. Therefore, the reaction cartridge 12b made of titanium does not corrode by corrosive fluid such as hydrochloric acid.

Modification of Embodiment 2 The heating means 66 of this modification is different from that of the reaction cartridge 12b of Embodiment 2 in that, as shown in FIG. A jacket 68 provided along the outer peripheral wall, a supply pipe 70 for constantly supplying supercritical water having a temperature exceeding 380 ° C. to the jacket 68 from a supercritical water supply source (not shown), and discharging the supercritical water. The reaction cartridge 12b is maintained at a temperature of 380 ° C. or higher by always providing supercritical water having a temperature exceeding 380 ° C. in the jacket 68. FIG. 6 is a sectional view of a reactor according to a modification of the second embodiment.

In Embodiment 2 and its modifications,
Air heated to a temperature exceeding 380 ° C. can be used instead of supercritical water. In that case, it is preferable to provide a filter for removing impurities such as oil in the air before the heating furnace for heating the air.

Embodiment 3 This embodiment is still another example of the embodiment of the supercritical water treatment apparatus according to the present invention. FIG. 7 shows the configuration of the supercritical water treatment apparatus of this embodiment. It is a flow sheet shown. The supercritical water treatment device 74 according to the present embodiment is provided with the reaction cartridge 1
It has the same configuration as the supercritical water treatment apparatus 10 of Embodiment 1 except that the heating means 2b is different. That is, the supercritical water treatment device 74 includes an air heater 76 in the pressure-balancing air inlet pipe 30 as a heating means of the reaction cartridge 12b, and pressurizes air heated to a temperature exceeding 380 ° C. by the air heater 76. Reactor 12 as air for balance
The reaction cartridge 12b is heated to 380 ° C. or higher by air for pressure balancing.

Although the first to third embodiments and their modifications and modifications do not refer to the temperature control of the reaction cartridge 12a, the reaction cartridge 12a is provided with a thermometer and the thermometer indicates the temperature. The current supplied to the electric resistance heating element 36, the induction coil 60, or the like, or the flow rates of supercritical water and air supplied to the flexible tube 64 and the jacket 68 are controlled so that the temperature of the reaction cartridge 12a does not become lower than 380 ° C. A temperature controller for adjustment may be provided. Furthermore, in order to reduce heat energy consumption,
The outside of the electric resistance heating element 36, the induction coil 60, the flexible tube 64, the jacket 68 and the like may be insulated and kept warm with a heat-resistant heat insulating material.

[0048]

According to the present invention, the temperature of the reaction zone is set to 550.
C. or more and 650.degree. C. or less, and at least the inner surface layer of the reaction cartridge of the pressure balanced reactor is formed of a titanium layer or a titanium alloy layer, and the heating cartridge is heated from the outside of the reaction cartridge to 380.degree. , The problem of corrosion of the supercritical water treatment apparatus for treating the liquid to be treated containing a high-concentration organic chlorine compound such as PCB can be solved. Therefore, the present invention provides a PCB
Thus, a supercritical water treatment apparatus capable of stably treating a liquid to be treated containing a high-concentration organic chlorine compound such as that described above for a long time and satisfying a discharge standard of 3 ppb or less has been realized.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a configuration of a supercritical water treatment apparatus of a first embodiment.

FIG. 2 is a cross-sectional view illustrating a configuration of a reactor of the supercritical water treatment apparatus according to the first embodiment.

FIGS. 3A and 3B are conceptual diagrams each showing a configuration of a heating unit of a reaction cartridge according to a modified example of the first embodiment.

FIG. 4 is a sectional view of a reactor according to a modification of the first embodiment.

FIG. 5 is a cross-sectional view of a reactor of a supercritical water treatment apparatus according to a second embodiment.

FIG. 6 is a cross-sectional view of a reactor as a modified example of the supercritical water treatment apparatus of the second embodiment.

FIG. 7 is a flow sheet showing a configuration of a supercritical water treatment apparatus of a third embodiment.

FIG. 8 is a flow sheet showing a configuration of a conventional supercritical water treatment apparatus.

FIG. 9 is a cross-sectional view showing a configuration of a conventional pressure balanced reactor.

[Explanation of symbols]

Reference Signs List 10 supercritical water treatment apparatus of first embodiment 12 pressure-resistant sealed reactor 12a outer cylinder 12b reaction cartridge 14 treatment liquid tube 15 neutralization mixer 16 cooler 18 pressure control valve 20 gas-liquid separator 22 liquid-to-be-treated pump Reference Signs List 24 Air compressor 26 Liquid pipe to be treated 28 Air inlet pipe 30 Air inlet pipe for pressure balance 31 Alkaline aqueous solution supply system 32 Temperature controller 34 Thermometer 35 Heating means provided in the reaction cartridge of the reactor of the first embodiment 36 Electric Resistance Heating Element 38 Cable 40 Connector 42 Sealing Part 44 Heating Means of Modification of First Embodiment 46 Heat Resistant Insulating Material Layer 48 Ni / Cr Electric Resistance Wire 50 Heating Means of Another Modification of First Embodiment 52 Heat-resistant electric insulating film 54 Ni / Cr electric resistance wire 56 Heat-resistant heat insulating material layer 58 Heating means 60 as a modification of the first embodiment 60 Conducting coil 62 Heating means of the second embodiment 64 Serpentine pipe 66 Heating means of a modification of the second embodiment 68 Jacket 70 Supply pipe 72 Discharge pipe 74 Supercritical water treatment apparatus of the third embodiment 76 Air heater 80 Conventional super Critical water treatment apparatus 81 Pressure-resistant closed vertical reactor 82 Supercritical water area 83 Virtual interface 84 Subcritical water area 85 Inflow pipe 86 Liquid line to be treated 87 Air line 88 Supercritical water line 89 Neutralizer line 90 Treatment liquid line Reference Signs List 91 Subcritical water line 92 Subcritical drainage line 100 Conventional pressure balance type reactor 101 Outer cylinder 102 Reaction cartridge 103 Inlet nozzle 104 Reaction zone 105 Pressure balance air inlet 106 Annular part 107 Upper gap 108 Reactor outflow pipe

Continuation of the front page (72) Inventor Katsuo Yoda 1-8-2 Shinsuna, Koto-ku, Tokyo Organo Co., Ltd. (72) Inventor Noriyuki Yasou 1-2-8 Shinsuna, Koto-ku, Tokyo Organo Co., Ltd. F term (reference) 4D038 AA08 AB14 BA02 BA04 BA06 BB01 BB13 BB16 BB20 4D050 AA13 AB19 BB01 BC01 BC02 BD02 BD06 BD08 CA13 CA20

Claims (7)

[Claims] A pressure-balanced reactor formed as a double cylinder comprising an outer shell formed as a pressure vessel and a reaction cartridge disposed in the outer shell and comprising an inner shell communicating with each other. A liquid to be treated containing an organic chlorine compound is introduced into supercritical water in a reaction cartridge,
In a supercritical water treatment apparatus that oxidizes and decomposes with an oxidizing agent at a temperature of not less than 650 ° C. and causes a treatment liquid having a lower concentration of an organic chlorine compound than the liquid to be treated to flow out of the reactor, at least the inner surface layer of the reaction cartridge has a titanium layer or A supercritical water treatment apparatus comprising a heating means formed of a titanium alloy layer and heating the reaction cartridge from outside the reaction cartridge to maintain the temperature at 380 ° C. or higher. 2. The heating means comprises an electric resistance heating element provided along the outer peripheral wall of the reaction cartridge and a current supply means for supplying electric current to the electric resistance heating element. 3. The supercritical water treatment apparatus according to item 1. 3. The heating means includes an induction coil wound along the outer peripheral wall of the reaction cartridge and a current supply means for supplying current to the induction coil, or a current for supplying current to the reaction cartridge itself. The supercritical water treatment apparatus according to claim 1, further comprising a supply unit. 4. A heating means comprising: a jacket provided outside the reaction cartridge or a coiled tube wound around the reaction cartridge; and a heating medium supply means for supplying a heating medium having a temperature exceeding 380 ° C. to the jacket or the tube. The supercritical water treatment apparatus according to claim 1, comprising: 5. The supercritical water treatment apparatus according to claim 4, wherein the heat medium is supercritical water or air at a temperature exceeding 380 ° C. 6. A heating means comprising a heater for heating air, wherein air having a temperature exceeding 380 ° C. is fed as pressure balancing air between the outer shell and the reaction cartridge. Item 2. A supercritical water treatment apparatus according to item 1. 7. The processing liquid pipe according to claim 1, wherein the neutralizing means is provided in a processing liquid pipe immediately downstream of a connecting portion between the processing liquid pipe for discharging the processing liquid from the reactor and the reactor. The supercritical water treatment apparatus according to any one of the preceding claims.