JP2003245679A - Supercritical water oxidizing method and supercritical oxidation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supercritical water oxidizing method which, when a raw liquid containing organic substances, dissolved inorganic salts and/or solids is subjected to supercritical water oxidation treatment, is capable of supercritical water oxidation treatment by a reactor relatively simple in structure having no function for removing deposited inorganic salts and originally existing solids. <P>SOLUTION: The supercritical water oxidizing method for the raw liquid containing the organic substances, the dissolved inorganic salts, and/or the solids includes an evaporation process for evaporating the raw liquid and a supercritical water oxidizing process for the supercritical water oxidation treatment of condensed water obtained in the evaporation process. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a supercritical water oxidation method and a supercritical water oxidation apparatus for a liquid to be treated containing an organic substance, an inorganic salt and / or a solid substance.

[0002]

2. Description of the Related Art In the case of supercritical water oxidation of experimental waste liquids discharged from various research facilities or waste liquids containing organic substances and dissolved inorganic salts and / or solids such as waste liquids of chemical plants, etc. As a reactor for carrying out the reaction, it is necessary to use a modder type reactor (a vertical type reactor forming a subcritical water region in the lower part of the reactor) capable of removing inorganic salts and solids.

However, since the modder type reactor has a complicated structure, the manufacturing cost is high, and if the tube type reactor having a simple structure can be used, the manufacturing cost of the apparatus can be reduced. Further, when a large amount of solid matter is present in the waste liquid, it may be difficult to send the liquid to the reactor.

[0004]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to precipitate inorganic salts or to be originally present when a liquid to be treated containing an organic substance and a dissolved inorganic salt and / or a solid substance is subjected to supercritical water oxidation treatment. The present invention is to provide a supercritical water oxidation method and a supercritical water oxidation apparatus capable of performing a supercritical water oxidation treatment in a reactor having no function of removing solids. It is an object of the present invention to provide a supercritical water oxidation method and apparatus provided with a means for separating dissolved inorganic salts and / or solids having a very simple structure in the first stage.

[0005]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors, when the liquid to be treated containing organic substances and dissolved inorganic salts and / or solids is supercritically hydroxylated, the liquid to be treated is vaporized in advance. It was found that the above problems can be solved by treating to remove dissolved inorganic salts and / or solid matter, and completed the present invention.

That is, the present invention provides (1) a supercritical water oxidation method for a liquid to be treated containing an organic substance and dissolved inorganic salts and / or solids, which comprises an evaporation step of evaporating the liquid to be treated, and A supercritical water oxidation step in which the condensed water obtained in the evaporation step is subjected to a supercritical water oxidation step, and (2) an object to be treated containing organic matter and dissolved inorganic salts and / or solid matter A liquid supercritical water oxidation apparatus, comprising: evaporation means for evaporating the liquid to be treated; and supercritical water oxidation means for superconducting condensed water obtained by the evaporation means. (3) The supercritical water oxidation apparatus according to (2), wherein the supercritical water oxidation means has a tube reactor.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid to be treated containing an organic substance and a dissolved inorganic salt and / or a solid substance of the present invention includes an organic substance and a dissolved inorganic salt, an organic substance and a solid substance, or an organic substance, a dissolved inorganic salt and a solid substance. The liquid to be treated is, for example, an experimental waste liquid discharged from various research facilities, a waste liquid of a chemical factory, or the like.

The organic substance in the present invention is preferably an organic substance which can be vaporized, and examples thereof include various alcohols. Furthermore, organic substances that are difficult to oxidize and decompose with an oxidizing agent and / or ultraviolet rays, or hardly decomposable organic substances that are difficult to decompose by biological treatment can be exemplified, and examples thereof include trichloroethylene, tetrachloroethylene, and dichloromethane.

The dissolved inorganic salts in the present invention are alkali metals such as sodium chloride, sodium sulfate and potassium chloride which are dissolved in the liquid to be treated at a saturation concentration or less,
Examples thereof include chlorides or sulfates of alkaline earth metals.

The solid matter in the present invention means that the above-mentioned inorganic salts are present in the liquid to be treated because they are present in a saturated concentration or more, or the inorganic substances such as glass and the organic substances such as rubber and plastic which are originally insoluble in the liquid to be treated. In the method of the present invention, or a combination thereof, the liquid to be treated containing the organic substance and the dissolved inorganic salt and / or the solid substance is subjected to evaporation treatment in advance before the supercritical water oxidation treatment.

The evaporation treatment is performed by directly injecting heated steam into the liquid to be treated to boil the liquid to be treated, or by heating the outside of a container containing the liquid to be treated to boil the liquid to be treated. It is vaporized and can be performed under normal pressure or reduced pressure.

The evaporation means is a means that enables the evaporation process, and examples thereof include a dip type drum dryer and a batch type dryer. Preferably, a scraping surface type liquid film evaporator capable of continuously removing solid matter adhering to the heat transfer surface by scraping means.

By evaporating the liquid to be treated, the dissolved inorganic salts are precipitated in the liquid, and the solid matter is removed as it is as a solid residue. Since the organic matter moves to the condensed water side, the condensed water may be supercritically hydroxylated. Since the condensed water may be supercritically oxidized, a reactor having no function of removing inorganic salts and solids can be used. By treating in such a step, the treated water after supercritical water oxidation can be released, and a solid residue containing no organic matter can be obtained in the evaporation treatment step, so a large volume reduction should be achieved. And the subsequent treatment of the solid residue can be simplified.

The supercritical water oxidation treatment in the present invention is a method of oxidatively decomposing organic matter in the presence of supercritical water and an oxidizing agent. The supercritical water oxidation reaction is not particularly limited as long as it is a temperature and pressure condition that brings water into a supercritical state, but is, for example, a temperature of 374 ° C. or higher, preferably 500 to
650 ° C. and pressure 22 MPa or more, preferably 22 to
The condition may be 25 MPa.

Examples of the oxidizing agent include air, pure oxygen, and hydrogen peroxide. These oxidizing agents may be used in a stoichiometrically required amount or more.

Since condensed water containing no inorganic salts and / or solids may be supercritically hydroxylated, it is not necessary to use a reactor having a function of removing inorganic salts and solids such as a modder reactor. A tubular reactor having a simpler structure can also be used.

An embodiment of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a flow chart for explaining one embodiment of the method of the present invention.

First, the liquid to be treated containing dissolved inorganic salts and / or solid matter and organic matter is evaporated. By the evaporation treatment, a solid residue containing inorganic salts and the like are separated into condensed water. Organic matter in the liquid to be treated moves to the condensed water side, and by treating the condensed water in the supercritical water oxidation step (indicated as “SCWO step” in FIG. 1), the organic matter can be efficiently decomposed. it can. Condensed water that does not contain inorganic salts and solids will be treated by the supercritical water oxidation method, and a reactor without a function of removing inorganic salts and solids can be used.

By the treatment process according to the present invention, the treated water discharged from the supercritical water oxidation treatment process does not contain any organic matter and can be discharged. Also, only solid residue remains in the evaporation treatment process, resulting in a large volume reduction. The processing can be simplified, and the subsequent processing can be simplified. If the organic matter contained in the treated water can be evaporated, the amount of organic matter remaining in the solid residue will be extremely small and can be discharged as it is, and even if some organic matter remains, the subsequent treatment will be simplified. Can be achieved. Alternatively, if the remaining solid residue is evaporated again, water does not remain, so the liquid to be treated can be evaporated at a temperature higher than the temperature at which the liquid is evaporated, further reducing the organic matter in the residual solid. Is also possible.

Embodiment 2 FIG. 2 is a flow chart for explaining an embodiment of the device of the present invention.

A liquid to be treated containing an organic substance, a dissolved inorganic salt and / or a solid substance is supplied to an evaporation device 1 as an evaporation means and separated into a solid residue containing an inorganic salt and condensed water. Since the organic matter moves to the condensed water side, the condensed water is pressurized and supplied to the tube reactor 4 by the high-pressure pump 2 so that the water has a critical pressure. On the other hand, the oxidizing agent is pressurized and supplied to the tube reactor 4 by the pressure pump 3.

Near the inlet of the tube reactor 4 is a heat exchanger type preheater 5. Supercritical water, oxidizer,
Organic matter reacts in the tube reactor 4 and the supercritical water oxidation reaction proceeds. Organic matter is supercritically hydrolyzed into water and carbon dioxide. The reaction fluid containing carbon dioxide and water is cooled by a heat exchange type cooler 6 provided near the outlet of the tube reactor 4. The cooled reaction fluid is introduced into the gas-liquid separator 8 through the pressure adjusting valve 7 that adjusts the pressure of the reactor, and the gas-liquid separation is performed. Carbon dioxide separated from gas and liquid is
The water is discharged through a pressure adjusting valve 9 that adjusts the pressure of the gas-liquid separator, and the treated water is discharged through a liquid level control valve 10 that adjusts the liquid level in the gas-liquid separator.

Evaporation device 1 that can be used in the present invention
Is any structure that can condense water by evaporating the liquid to be treated containing the organic substance and the dissolved inorganic salts and / or solid substance to evaporate the organic substance and water and cool these vapors. Although any one can be used, a schematic view of a scratch type liquid film evaporator used as the evaporator 1 is shown in FIG.

That is, a heating means is provided outside the cylindrical tank 11, and a rotary blade 13 for scraping solids is provided inside the cylindrical tank 11 so as to communicate with the motor 12. The liquid to be treated is supplied from the upper portion of the cylindrical tank 11, and the liquid to be treated supplied to the cylindrical tank 11 is heated and vaporized in the cylinder.

The vapor containing the vaporized organic matter is discharged from the upper portion of the tank, cooled outside the tank, and recovered as condensed water containing the organic matter. The deposits deposited on the wall surface of the cylindrical tank 11 are scraped off by the rotary blades 13 and the evaporation residue 14 deposited in the liquid 14
In combination with this, it is discharged to a residue receiving tank (not shown) below the cylindrical tank 11.

As the evaporator 1, a vacuum distiller may be used in addition to the scraped surface liquid film evaporator shown in FIG. The vacuum distiller is a device for continuously evaporating the liquid to be treated by applying a vacuum to the system, and is composed of three combinations of a vacuum crystallizer, a solid-liquid separation equipment and a drier.

[0028]

INDUSTRIAL APPLICABILITY According to the present invention, by using a reactor having no function of separating solids containing precipitated inorganic salts, a liquid to be treated containing organic matter and dissolved inorganic salts and / or solids is supercritically hydrolyzed. Since it can be treated, a supercritical water reactor of a type advantageous in terms of treatment performance and cost can be used. Further, according to the present invention, the volume of waste liquid can be greatly reduced, and the processing of the obtained evaporation residue can be simplified. An inexpensive reactor can be used, and the decomposition treatment cost can be reduced.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of a method of the present invention.

FIG. 2 is a flowchart showing an embodiment of the device of the present invention.

FIG. 3 is a schematic diagram of a scratch surface type liquid film evaporator.

[Explanation of symbols]

1 Evaporator 2 high pressure pump 3 high pressure pump 4 tube reactor 5 Preheater 6 cooler 7 Pressure control valve 8 gas-liquid separator 9 Pressure control valve 10 Pressure control valve 11 cylindrical tank 12 motors 13 rotors 14 Evaporation residue

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Suzuki             Olga 1-2-8 Shinsuna, Koto-ku, Tokyo             Within the corporation F-term (reference) 4D034 AA11 CA17                 4D050 AA12 AA13 AB14 AB19 AB22                       AB31 BB01 BB09 BB20 BC01                       BC02 BD02 BD06 CA02                 4D076 AA14 AA16 AA22 AA24 BA15                       BA19 CD03 CD16 CD25 FA04                       FA12 HA06

Claims (3)

[Claims] 1. A method for supercritical water oxidation of a liquid to be treated containing an organic substance and dissolved inorganic salts and / or solids, which comprises an evaporation step of evaporating the liquid to be treated, and condensed water obtained in the evaporation step. A supercritical water oxidation step of subjecting the supercritical water oxidation process to a supercritical water oxidation step. 2. A supercritical water oxidation apparatus for a liquid to be treated containing an organic substance and dissolved inorganic salts and / or solids, comprising: evaporation means for evaporating the liquid to be treated; and condensed water obtained by the evaporation means. A supercritical water oxidation apparatus having a supercritical water oxidation means for supercritical water oxidation. 3. The supercritical water oxidation apparatus according to claim 2, wherein the supercritical water oxidation means has a tube reactor.