JPH10137775A - Supercritical water oxidation method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize treatment with the method by providing a reaction region of a tubular reactor with plural separate introduction points in the fluid flow direction, mixing and introducing the organic matter to be decomposed, supercritical water and oxidizing agent into the reactor at a first introduction point and further introducing the organic matter to be decomposed into the reactor at the following induction points, in the method for decomposing organic matter with an oxidizing agent in the presence of supercritical water. SOLUTION: In this method and the device for the method, a tubular reactor 1 is provided with three separate introduction points for introducing organic matter to be decomposed, i.e., first, second and third introduction points. At the first induction point positioned at the reactor end 2 on the upstream side of the reactor 1, supercritical water, an oxidizing agent and organic matter are mixed and introduced into the reactor 1 with a two-flow nozzle (e.g. one flow consists of a mixture of the supercritical water and oxidizing agent and the other consists of the organic matter). At the second introduction point 3 which is positioned downstream from the first injection point and at which decomposition of the organic matter introduced into the reactor 1 at the first introduction point is considered to be completed, the organic matter is introduced into the reactor 1. Similarly, at the third point 4 positioned downstream from the second introduction point 3, the organic matter is introduced into the reactor 1. The oxidative decomposition product is discharged from the reactor end 6 on the downstream side of the reactor 1 to a pipeline 7 of a discharge system. Thus, the introduction amount of supercritical water is remarkably reduced and deficient decomposition of the organic matter due to uneven distribution of the organic matter in the reactor 1, etc., can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for decomposing organic substances such as hardly decomposable wastes and effluents and harmful waste vehicles and effluents. Supercritical water oxidation method suitable for completely decomposing hardly decomposable substances and harmful organic substances including various sulfur compounds, nitrogen compounds, phosphorus compounds, etc., including organic chlorine compounds such as PCBs, trichloroethylene and tetrachloroethylene. And an apparatus.

[0002]

2. Description of the Related Art In the field of decomposing hardly decomposable organic substances and harmful organic substances, which is one of the objects of the present invention, the processing has recently become a major social problem. There is a problem of whether complete decomposition is possible.

As an example of this problem, the treatment of organic matter has been conventionally performed by a combustion method. However, in the conventional combustion method, the fact that a low-temperature portion may exist in the furnace cannot be ignored, and the combustion method cannot be ignored. Insufficient decomposition may result. In such a case, if a chlorine compound or the like is to be decomposed, there is a risk that a highly toxic substance such as dioxin may be generated. In addition, since the end product of the combustion method is usually diffused from the exhaust stack to the atmosphere, if the toxic substance is generated, the problem may be widened.

[0004] For these reasons, for example, PCBs which have been conventionally used in large quantities as various heat carriers or insulating oils, and which have been subsequently confirmed to be toxic and whose production and use are prohibited,
Despite the strong demand for treatment and disposal, the practice of the currently accepted combustion method has not progressed much. It is said that there is a potential danger that the combustion products described above contain harmful organic substances and diffuse into the atmosphere.

[0005] Against the background of the above, closed and complete decomposition treatment is required for hard-to-decompose and harmful wastes and waste liquids. The critical hydroxylation method has attracted attention. This supercritical water oxidation method is carried out under supercritical conditions (above 374 ° C., 2
(2MPa or more) is a method of completely decomposing organic matter into water and carbon dioxide by using water as a medium for the decomposition reaction. In the reaction, thermal decomposition, hydrolysis and oxidative decomposition proceed simultaneously, and the reaction is carried out in a closed system. It has been known that there is a characteristic that a complete decomposition can be carried out at the same time and an extremely large reaction rate can be achieved.

[0006] This supercritical water oxidation technology is disclosed in
JP-B-38532 discloses a basic principle of performing an oxidation reaction under a condition exceeding a critical point of water, and also shows a basic flow.

[0007] Briefly speaking, the basic flow consists of a reactor for supercritical water oxidation reaction, a supply system for supplying a predetermined substance containing a substance to be decomposed to the reactor, and a reactor formed from the reactor. Described in three parts of the discharge system that discharges
Among these, the supply system of the substance is configured such that the substance to be decomposed is pressurized by a feed pump, mixed with supercritical water by an ejector, heated, and then introduced into the reactor in the above publication proposal. The reactor is configured such that high-pressure air as an oxidizing agent is introduced from an air compressor to oxidatively decompose a decomposition target under supercritical water conditions. The product discharge system recirculates a part of the supercritical water after the oxidative decomposition to the ejector,
It is configured to use the remainder as an energy source for turning a turbine, for example, to perform energy recovery. However, in this gazette proposal, the specific configuration of the reactor is not described in detail,
It is only schematically described that tubular, cylindrical and fluidized bed types can be employed.

[0008] The structure of the reactor is a one-pass type pipe (pipe) in which an object to be decomposed, supercritical water, and an oxidizing agent are injected from the starting end of an elongated tube and decomposition products are discharged from the end. Type) A reactor is known as a typical one. Apart from this, a reactor having a vessel type structure is also disclosed in JP-A-3-5.
It is proposed in Japanese Patent Publication No. 00264.

Vessel type reactors have been proposed as being suitable for organic wastes containing inorganic salts or producing inorganic salts after the reaction, and are generally advantageous because of their simple structure. The problem to be solved in the tubular (pipe type) reactor considered as a vessel is solved. In other words, typical objects to be treated in the supercritical water oxidation technology are hardly decomposable organic substances and harmful organic substances, and in many cases, contain chlorine and sulfur, and also nitrogen and phosphorus. When these substances are subjected to supercritical water oxidation treatment, acids (hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid) are generated from the contained components, and are neutralized with alkali to protect the reactor materials and the like from these acids. As a result, an inorganic salt (typically, NaCl) is generated. However, it is generally known that this NaCl hardly dissolves in supercritical water. Therefore, when the above-mentioned pipe reactor is used, the problem of pipe clogging always occurs due to the NaCl salt generated by neutralization. Therefore, the above-mentioned Japanese Patent Application Laid-Open No. 3-500264
The reactor is designed so that the clogging problem does not occur due to the salt generated by the operation of acid neutralization. By forming a critical zone and forming a subcritical zone in the lower part of the vessel, the inorganic salt precipitated in the upper supercritical zone is moved downward with a density difference and dissolved in subcritical water in the subcritical zone, We proposed a Vessel type reactor in which the supercritical water and CO ₂ , which are the majority of the products produced in the critical hydroxylation reaction, and the salt that causes adhesion and blockage can be separated in the vessel. I have.

[0010]

In order to use the above-mentioned supercritical water oxidation reaction for decomposing organic substances, it is necessary to supply the organic substances to be decomposed at a high temperature and a high pressure to the reactor. However, in this case, if the temperature is increased in the middle of the path for supplying the decomposition target through the supply pipe or the high temperature decomposition target is supplied through the pipe, the decomposition target organic substance may cause a polymerization reaction or charring. This may cause blockage in the supply pipe. Further, when the organic substance is a hardly decomposable organic substance, it is changed to a more hardly decomposable substance by a polymerization reaction or the like, and there is a possibility that the decomposition rate may be reduced. Therefore, a method of raising the temperature of the organic matter to be decomposed immediately before supplying it to the reactor is considered.The water is heated to a supercritical state by a special preheater, and the preheated supercritical water and the substance to be decomposed are mixed in the reactor. A method has been proposed in which the temperature of an organic substance to be decomposed is raised by mixing immediately before (Japanese Patent Application Laid-Open No. H07-19783).
-275871).

However, in the case where the supercritical water oxidation treatment is carried out by immediately raising the temperature of the organic substance to be decomposed to a temperature higher than the critical temperature by the above-described method immediately before the supply to the reactor, the decomposition of the organic substance to be decomposed is difficult. The amount of supercritical water required for this is determined by the actual reaction temperature, the supply amount of the decomposition target to the reactor, the temperature at which the decomposition target is preheated and supplied, etc. If the amount of heat energy can be reduced, energy efficiency can be improved, and in particular, it is desired to devise a device for an industrial scale.

Although supercritical water has excellent solvent properties as a solvent for many water-insoluble organic substances, the organic substance and supercritical water are mixed immediately before the reactor as in the above method. In such a case, sufficient mixing with the organic substance to be decomposed and the oxidizing agent (typically, air) cannot be neglected due to the amount, time, structure of the reactor, and the structure of the mixing means. In some cases, it is not easy to uniformly mix with supercritical water in a short time. For this reason, there is a possibility that each of the substances is present in a partially separated state, which may cause a reduction in the decomposition rate. In particular, when harmful organic substances are targeted, it is strongly required to solve this problem.

Although this problem can be avoided by providing an additional facility for treating undecomposed or decomposed products, it is of course possible to avoid industrial problems for harmful organic substances requiring complete decomposition. It is not advantageous as a processing method or apparatus.

As described above, the supercritical water oxidation treatment, which has recently attracted attention as a method and an apparatus for decomposing organic substances to be decomposed, particularly hardly decomposable organic substances and harmful organic substances, is conceptually extremely excellent. At present, there are few concrete proposals for enabling this technology to be implemented stably and inexpensively on an industrial scale, and the present inventor aims to achieve such various technical problems. After extensive research, the present invention has been accomplished.

[0015]

The object of the present invention is attained by the inventions described in the claims.

According to the invention of a supercritical water oxidation method according to claim 1 of the present application, a fluid containing an organic substance to be decomposed is continuously supplied to a reaction zone under conditions where the temperature and pressure are equal to or higher than the critical point of water. A supercritical water oxidation method in which organic substances are oxidatively decomposed in the presence of supercritical water and the reaction product fluid is continuously discharged from the reaction area, and decomposed from a plurality of positions separated in the flow direction of the fluid in the reaction area The target organic substance is introduced, and at the first stage introduction position, the organic substance to be decomposed and supercritical water are mixed at the time of introduction or introduced immediately after mixing, and at the introduction position after the next stage, it is decomposed into the fluid generated by the reaction at the previous stage It is characterized in that the target organic matter is introduced again.

According to the present invention, water (supercritical water) generated by the oxidative decomposition of the organic substance introduced in the first stage among the unit amounts of the organic substance to be decomposed is used as a solvent for the organic substance to be decomposed introduced in the subsequent stages. Since it can be used and the organic substance can be preheated and heated to a temperature higher than the critical temperature by the heat, supply of supercritical water from outside is basically unnecessary. Therefore, the amount of organic substances to be decomposed introduced in the first stage can be reduced by that amount, and the total amount of supercritical water supplied to the reaction region can be reduced.

Also, since the amount of organic substances to be decomposed introduced in the first stage is small, the heat energy required for preheating and heating this organic substance by mixing with high-temperature supercritical water can be reduced, thereby reducing the amount of supercritical water and lowering the temperature. Alternatively, it is possible to reduce the preheating temperature of the organic substance to be decomposed or omit the preheating. To explain this point more specifically, as described above, in order to prevent polymerization and charring, a supercritical fluid separately manufactured as a means for raising the temperature of an organic substance to be decomposed to a critical temperature or higher at a stroke near (or inside) the reaction region at once. Considering a method of mixing water (or circulating supercritical water generated by oxidative decomposition) with the organic substance to be decomposed, it is necessary to raise the unit weight of the organic substance to be decomposed introduced into the reaction zone to a critical temperature (374 ° C.) or higher. FIG. 4 shows the result of calculating how many times the amount of high-temperature supercritical water is required by simulating organic matter with normal-temperature water (specific heat 1).

According to the graph of FIG. 4, when supercritical water at 400 ° C. is used, the temperature becomes higher than the critical temperature by about three times,
It can be seen that when the supercritical water at 00 ° C. and 600 ° C. is used, the temperature reaches the critical temperature or more in about twice the amount. here,
Assuming that the reaction temperature of supercritical water oxidation is 600 ° C., in the case where supercritical water at 400 ° C. is used in addition to the amount of heat for heating the temperature of the decomposition target itself to 600 ° C., the added amount is three times as much as Energy for further heating the critical water from 400 ° C. to 600 ° C. is required. Similarly, at 500 ° C., 2
Energy for heating twice the amount of supercritical water from 500 ° C. to 600 ° C. is added. On the other hand, if supercritical water at 600 ° C. is used, only the amount of heat required to heat the decomposition target itself to 600 ° C. is sufficient. Therefore, if the calorific value of the substance to be treated is sufficiently high, supercritical water at 400 ° C. can be used as a preheating source. However, if the calorific value of the substance to be treated is limited, such as a hydrated substance, 500 to 600 ° C. ℃ supercritical water is required. In any case, the creation of a supercritical water field in which the oxidation reaction proceeds rapidly requires the mixing of energetically significant amounts of supercritical water.

On the other hand, in the present invention in which the organic matter to be decomposed is divided and supplied (press-fitted) to the reaction zone, the amount of supercritical water introduced from the outside into the reaction zone can be greatly reduced as follows. That is, the relationship between the number of divisions of the introduction position of the decomposition target organic substance, the introduction amount (supply amount) of the decomposition target organic substance at each position, and the first stage supercritical water introduction amount is shown in Table 1 below (however, in this Table 1, the decomposition amount Twice the amount of supercritical water (SC)
W) was calculated).

[0021]

[Table 1]

As can be seen from this table, in the case of the conventional method in which the number of divisions is 1, that is, the entire amount is introduced (press-fitted) in the first stage,
The required amount of supercritical water is 2, whereas the number of divisions according to the present invention is 2, which is 0.8 or less, and the amount of supercritical water that must be introduced in the first stage decreases as the number of divisions increases. And
When the number of divisions is 5, it is 0.16, which is about 1/10 or less of the conventional method. Thus, it can be seen that the method of the present invention in which the decomposition target is divided and introduced into the reaction region is excellent in energy. In many cases, it is appropriate that the number of divisions is about 2 to 5 in an industrial apparatus, but the number of divisions is not limited to many. Further, the description of the distribution ratio in this table is model-like, and it is natural that the distribution ratio of the organic substance in the actual apparatus is not limited to this.

According to the invention, the amount of supercritical water to be introduced can be reduced, so that the total amount of fluid discharged from the reaction zone can be reduced, and the load on the discharge system can be reduced.
A system for supplying the organic substance to be decomposed to the reaction region while preventing the charging can be simply configured.

Further, since the organic substance to be decomposed is divided into reaction regions and introduced (press-fitted), the amount of introduction at each division position is small, and the mixture of the introduced organic substance and supercritical water can be satisfactorily given. It is effective for complete oxidative decomposition of water, and is particularly effective for oxidative decomposition of hardly decomposable organic substances and harmful organic substances.

In the above structure, the reaction zone in which the temperature and pressure are equal to or higher than the critical point of water is any reactor such as a tubular reactor or a Bessel reactor (vertical cylindrical reactor). It may be formed in the reactor, and is not limited to the type of the reactor. The term "fluid containing organic substances to be decomposed" refers to a fluid in which other substances (for example, an oxidizing agent) necessary for the supercritical water oxidation reaction are mixed in addition to the organic substances to be decomposed, or a fluid in which these substances are not mixed. Including both. In the case of fluids that do not mix, each fluid can be supplied by an independent supply system (consisting of piping, feeding means, pressurizing means, heating means, etc.). The substance supplied to the reaction zone together with the substance to be decomposed includes water (supercritical water) existing at a temperature higher than the critical point of water, that is, 374 ° C. or higher and 22 MPa or higher, a gaseous oxidizing agent such as oxygen, air, or the like. A liquid oxidizing agent such as aqueous hydrogen peroxide can be used. Further, when an acid such as hydrochloric acid is generated by a supercritical water oxidation reaction, an alkali (NaO) for neutralizing the acid is used.
H, KOH, Na ₂ CO ₃ , K ₂ CO _3, etc.).

In the case of introducing the organic matter to be decomposed and supercritical water into the first stage introduction position of the above-mentioned structure, “mixing at the time of introduction” means, for example, that these substances are introduced into the reaction region using a multi-tube nozzle such as a two-fluid nozzle. The term "introduce immediately after mixing" refers to mixing in a pipe or the like before sending it to the reaction zone, and then feeding. The term "immediately" means that the components are mixed as close as possible to the reaction region. However, the mixing can be carried out as long as there is no adverse effect of causing a polymerization reaction and a charring as a result of the temperature rise of the organic substance to be decomposed by the mixing.

According to a second aspect of the present invention, an organic substance is oxidatively decomposed in the presence of supercritical water in a tubular reactor having a reaction zone where the temperature and pressure are above the critical point of water. A supercritical water oxidation method, in which the organic substance to be decomposed and supercritical water are mixed at the time of introduction into the beginning of the tubular reactor, or introduced immediately after mixing to allow the oxidative decomposition reaction to take place,
The organic substance to be decomposed is reintroduced to a predetermined position in the fluid generated by the oxidative decomposition reaction of the organic substance introduced into the tubular reactor, and the oxidative decomposition reaction is continued by continuing the oxidative decomposition reaction. The operation is performed at at least one or two or more positions along the flow direction of the fluid in the reactor, which corresponds to the case where the invention of claim 1 is performed using a tubular reactor.

According to the present invention, the operation and effect of the first aspect of the present invention can be achieved by using a tubular reactor having a simple structure, and in particular, it is possible to preferably carry out a decomposition treatment of an organic substance having no acid generation. it can.

According to a third aspect of the present invention, a reaction zone under supercritical conditions in which the temperature and pressure are equal to or higher than the critical point of water is provided in the upper portion of the reactor, and a region under subcritical conditions is provided in the lower portion of the reactor. For a plurality of vertical cylindrical reactors (vessel-type reactors), a fluid continuously flows through the reaction area of each reactor, and in each reaction area, an ultra-oxidative decomposition of organic substances is performed in the presence of supercritical water. In the critical water oxidation method, the organic matter to be decomposed and supercritical water are mixed in the reaction zone of the first-stage reactor at the time of introduction, or are introduced immediately after mixing, and the oxidative decomposition reaction is carried out. It is characterized in that the fluid generated by the reaction at the preceding stage is flowed into the reaction zone of the vessel and the organic matter to be decomposed is introduced again, which corresponds to the case where the invention of claim 1 is carried out using a Bessel reactor.

According to the present invention, since the acid generated by oxidative decomposition can be dissolved in subcritical water from the subcritical region (subcritical region) and discharged, the region under supercritical conditions (supercritical region, ie, In the case where an organic substance which can achieve the function and effect of the invention of the above-mentioned claim 1 while avoiding problems such as clogging with a salt precipitated in the region), and which generates a salt by alkali neutralization, is used as an object to be decomposed. This is particularly useful for the treatment of supercritical hydroxylated decomposition of hardly decomposable organic substances and harmful organic substances, which are generally considered to generate salts by alkali neutralization.

In the above-described configuration, a plurality of “continuously flowing through the reaction regions of each reactor” means that the supercritical regions of the plurality of reactors are connected by piping or the like so that the transfer distance is as short as possible. Given.

In each of the above-mentioned inventions, not only general organic substances, but also particularly residual organic pollutants (POPs: Persiste
nt Organic Pollutants) or Persistent Toxic Bio-accumlatives (PTBs)
And the typical substances are
Examples include organic chlorine compounds such as PCBs, trichloroethylene, tetrachloroethylene, and waste pesticides, which are designated as harmful substances in environmental standards. In addition to chlorine, halides are generally hardly decomposable, and organic bromine compounds and the like can be treated. Furthermore, various sulfur compounds, nitrogen compounds, phosphorus compounds, and the like are emitted from production processes in various factories, and are particularly effectively used for treating organic substances that require complete decomposition thereof.

The conditions for the supercritical hydroxylation reaction of each invention are as follows:
The reaction temperature is generally 400 ° C. or higher, preferably 600 to
650 ° C. and the reaction pressure is 22-50 MPa,
Preferably it is 22 to 25 MPa. The reaction time is 1 to
10 minutes, preferably 1-2 minutes.

The organic substance to be decomposed introduced into the reaction zone of each of the above-mentioned inventions can be used so as to be heated to a critical temperature or higher by mixing with supercritical water without preheating. Can be sent to the vicinity of the reaction region in a state where it is preheated to a low temperature (for example, 100 to 350 ° C., preferably 200 to 300 ° C.) within a range where there is no fear of causing the above. The supercritical water to be mixed with the organic substance to be decomposed without preheating in this manner or preheated to a low temperature as described above is 500 to 650 ° C, preferably 550 ° C.
In many cases, it is appropriate to use one heated to about 600 ° C., and it is also possible to circulate the reaction product fluid discharged from the discharge system downstream of the reactor as the supercritical water. When the organic matter to be decomposed is introduced into the reaction zone without preheating, the structure of the equipment such as the piping of the supply system can be made simpler and the control becomes easy.

According to a seventh aspect of the present invention, in each of the above-mentioned inventions, an oxidizing agent required for oxidative decomposition of an organic substance is mixed with an organic substance to be decomposed or supercritical water and introduced into the reaction zone, or It is characterized in that it is mixed with these at the time of introduction. As the method of introducing the oxidizing agent, as in the invention of claim 8 of the present application, a method of introducing the entire amount of the oxidizing agent necessary for the oxidative decomposition of the organic substance to be decomposed into the first-stage reaction region, or a method of dividing and introducing each of the oxidizing agents. Any of the methods of dividing and introducing according to the introduction amount of the organic substance to be decomposed in the above step may be adopted.

According to a ninth aspect of the present invention, in each of the above-mentioned inventions, the alkali introduced to neutralize the acid generated by the supercritical hydroxylation reaction is selected from the group consisting of an organic substance to be decomposed, supercritical water, and an oxidizing agent. The mixture is introduced into the reaction region after being mixed with the crab, or mixed with the mixture when the mixture is introduced into the reaction region. As a method for introducing the alkali, as in the invention of claim 10 of the present application, a method of introducing the entire amount of alkali necessary for neutralizing the acid generated by the supercritical hydroxylation reaction into the first-stage reaction zone, or Any of the methods of introducing the organic matter to be decomposed into each position at each position in accordance with the amount of the organic substance to be decomposed introduced into each position may be adopted.

The supercritical water oxidation apparatus according to claim 11 of the present application provides a tubular reactor for forming conditions for a supercritical water oxidation reaction, and continuously feeds a fluid containing an organic substance to be decomposed into the reactor. A supply unit, and a discharge unit that continuously discharges the reaction product fluid from the reactor, wherein the supply unit is provided at a start end of the tubular reactor and at least one position on a downstream side along a flow of the fluid. It is provided so as to have a position for supplying the organic substance to be decomposed separately from the above positions, and the supply means to the starting end of the tubular reactor has a mixing means for mixing the organic substance to be decomposed and supercritical water It is characterized by.

According to the present invention, the organic matter to be decomposed is divided and supplied (introduced) separately from the starting end of the tubular reactor and from one or more positions downstream of the reactor. And at the downstream split feed position,
Supercritical water, which is a fluid that is supplied and oxidatively decomposed and generated in the previous stage, can be used as a solvent for organic substances to be decomposed and supplied downstream, and its heat also serves as a preheat source for the introduced organic substances. Supercritical water is not required to be supplied, so that the amount of supercritical water supplied together with the organic matter to be decomposed from the beginning of the reactor can be reduced corresponding to the amount divided downstream. This reduces the energy required for producing supercritical water and reduces the amount of discharged fluid, and also facilitates the polymerization reaction and charring of the organic substance in a pipe for supplying the organic substance to be decomposed to the reactor. It is possible to provide a supercritical water oxidation apparatus that can prevent the organic matter to be decomposed to a temperature higher than the critical temperature at a stretch with a small amount of energy by preventing it with a structure.

Further, since the amount of the organic substance to be decomposed to be supplied at each of the divided positions including the starting end of the reactor can be relatively reduced as compared with the conventional method in which the whole amount is supplied at the starting end, the organic substance and the supercritical Since the water can be mixed well, complete decomposition can be effectively achieved.

In the above configuration, the "tubular reactor" may be any of a linearly extending structure, a curvedly extending structure, a structure combining these, and the like. It is not limited by the structure or the like. Further, the position of the divisional introduction on the downstream side is set at a position where the oxidative decomposition reaction of the organic substance supplied (introduced) in the preceding stage is completed, but is not strict.

In the above configuration, the “supply means” is a pipe,
Known configurations such as a feeding means such as a feed pump, a pressurizing means such as a pressurizing pump, and a heating means such as a heat exchanger can be employed. As a supply system of the organic substance to be decomposed, generally, It is often appropriate to adopt a configuration in which a single system is introduced to the vicinity of the reactor and then distributed to each divided supply position in the vicinity of the reactor in order to simplify the apparatus configuration. The ratio of the distribution amount is determined according to the number of divisions as described in Table 1 described above. As the "discharge means", a known configuration such as a pipe, a feed means such as a feed pump, a pressure reducing means such as a pressure reducing valve, a cooling means such as a heat exchanger, etc. can be adopted. Appropriate means such as a two-fluid nozzle, a pressure spray nozzle, a spiral spray nozzle, and a static mixer can be used as the "mixing means", and a two-fluid nozzle is preferably employed as described later.

The invention of a supercritical water oxidation apparatus according to claim 12 of the present application is directed to a plurality of vertical tubes having a supercritical region for performing a supercritical water oxidation reaction in the upper part of the vessel and a subcritical region in the lower part of the vessel. A tubular reactor (Vessel reactor), a pipe that connects the supercritical regions of each reactor so that they are substantially continuous (connected to a series), and organic substances to be decomposed in the supercritical region of each reactor Supply means, a discharge means for discharging the reaction product fluid from the supercritical region of the last reactor, and a salt discharge means for discharging the subcritical water in which the salt is dissolved from the subcritical region of each reactor. A supercritical water oxidation apparatus configured to include: a supply unit that supplies the organic substance to be decomposed to the supercritical region of the first-stage reactor; a mixing unit that mixes the organic substance to be decomposed and supercritical water in the supercritical region. It is characterized by having.

According to the present invention, the organic matter to be decomposed is divided and supplied to the first stage of a plurality of Bessel reactors connected to the series and one or more reactors at the next stage and thereafter. In the second and subsequent reactors, supercritical water, which is a fluid generated by oxidative decomposition in the previous stage, becomes a solvent for the organic substance to be decomposed and supplied separately, and also serves as a preheating source. Therefore, the supply of supercritical water from the outside is unnecessary, whereby the amount of supercritical water supplied together with the organic matter to be decomposed in the first-stage reactor can be reduced in accordance with the number of divisions. This reduces supercritical water production energy, reduces discharge fluid, prevents polymerization reaction and charring in piping etc. that supply organic substances to be decomposed to the reactor, and reduces supplied organic substances at once with less energy. An efficient supercritical water oxidation apparatus capable of raising the temperature can be provided.

In the Vessel reactor of the present invention, the acid generated in the supercritical region in the upper part of the vessel is neutralized with alkali, dropped into the subcritical area in the lower part of the vessel, dissolved in subcritical water, and reacted. Since it can be discharged from the vessel, it can be used particularly suitably for decomposing organic substances containing substances that generate acids, such as hardly decomposable organic substances and harmful organic substances.

In the above configuration, "supply means",
"Ejecting means" and "mixing means" are the same as those in the above-mentioned claim 11.

According to a thirteenth aspect of the present invention, in each of the above-described apparatus inventions, the mixing means for mixing and introducing the organic matter to be decomposed and the supercritical water into the starting end of the tubular reactor or the first-stage vessel reactor. Is a two-fluid nozzle.

According to the present invention, it is possible to carry out a supercritical water oxidation treatment which realizes efficient complete decomposition. In other words, if the mixture of the introduced organic substance, supercritical water, and the oxidizing agent is insufficient, the decomposition target organic substance may pass through the reaction region without undergoing sufficient oxidative decomposition. However, a two-fluid nozzle is used. In this case, by adjusting the shape of the nozzle and the flow rate of the inner and outer tubes, it becomes possible to supply (introduce and press-fit) the organic matter to be decomposed in a predetermined size (particle size) into the reactor. Can be sufficiently eliminated. In particular, when a hardly decomposable organic substance or a harmful organic substance is decomposed by a device using a Bessel-type reactor, it is possible to prevent the problem that the undecomposed substance falls into the lower subcritical region. This is extremely effective in preventing emission. On the other hand, if the spray particle diameter from the nozzle is too small, the size of the precipitated salt becomes very small, and in the Bessel reactor, the salt does not fall into the subcritical region due to the density difference but dissolve, It is also conceivable that the reverse flow and upward flow of low reaction product fluids (supercritical water, carbon dioxide, nitrogen, etc.) are reversed, and that the precipitated salts are discharged from the upper discharge port to the discharge system. There is a risk that the salt adheres and the piping after the reactor and the heat exchanger are blocked, but such a problem can be effectively solved by using a two-fluid nozzle.

Further, when a tubular reactor is used, a sufficiently turbulent state (Reynolds number> 10) is required in order to increase the degree of mixing of the introduced organic matter, supercritical water and oxidizing agent inside the reactor. It is effective to use a reactor having a small diameter and a long reactor. However, such reactors are not always advantageous in industrial equipment. On the other hand, in the case where the introduced organic substance and the oxidizing agent are mixed by using a two-fluid nozzle, there is an advantage that the mixing is performed well and the degree of freedom in designing the reactor is increased.

The two-fluid nozzle used in this manner has an effect of atomization by shearing force due to a large relative speed difference between the decomposition target fluid having a low injection speed and the supercritical water and oxidizing fluid having a high injection speed. The external mixing type is particularly preferably employed. The external mixing type two-fluid nozzle has a fluid discharge port facing the reaction area,
This is a type in which mixing is performed while each fluid is discharged to the reaction area.

In the two-fluid nozzle having the above-mentioned structure, the organic substance is passed through the inner tube and other substances (for example, supercritical water, oxidizing agent or these substances) are passed through the inner tube in order to prevent polymerization reaction and charring of the organic substance to be decomposed. Is preferably used.

The invention according to claim 14 of the present application has an introducing means for introducing the organic substance to be decomposed at a downstream position excluding the starting end of the tubular reactor, and this introducing means mixes the organic substance to be decomposed with the oxidizing agent. It is a two-fluid nozzle.

According to the present invention, it is possible to effectively mix the oxidizing agent and the organic substance to be decomposed introduced from a downstream position excluding the starting end of the tubular reactor.

As a configuration in which the nozzle is incorporated in the middle of the tubular reactor, for example, when the tubular reactor is substantially a straight tube, it can be incorporated at an appropriate position as shown in FIG.
When the tubular reactors are turned 180 ° to each other to form a serpentine tube, an example of a structure in which the nozzle is directed to the downstream side at the portion forming the inverted curve can be exemplified. It is the same as the above that the external mixing type is preferably used as the two-fluid nozzle, and it is preferable that an organic substance is passed through the inner pipe and an oxidizing agent is passed through the outer pipe.

According to a fifteenth aspect of the present invention, in the supercritical water oxidation apparatus using a Bessel-type reactor, the organic matter to be decomposed and the reaction product fluid from the former reactor are mixed into the second and subsequent reactors. Introducing a two-fluid nozzle for mixing the organic matter to be decomposed and the reaction product fluid with each other. It is characterized in that an organic substance is passed through an inner tube and other substances (a reaction product fluid, an oxidizing agent or a mixture thereof) mixed with the decomposition target organic substance are passed through an outer tube.

According to these inventions, the mixture of the introduced organic matter and the oxidizing agent can be effectively given also in the second and subsequent vessel type reactors.

An external mixing type is preferably used as the two-fluid nozzle. An organic substance is passed through the inner tube, and other substances such as a generated fluid from the former reactor (a reaction product fluid, an oxidizing agent solution, or the like) are passed through the outer tube. Is the same as described above.

[0057]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings showing a flow sheet.

Embodiment 1 The present embodiment shown in FIG. 1 shows an example in which the present invention is applied to a tubular reactor.

In FIG. 1, reference numeral 1 denotes a tubular reactor. In this embodiment, the position of introduction of the organic substance to be decomposed is divided into three parts with respect to the reactor 1, that is, one of the three divided organic substances is reacted. From the beginning 2 of the reactor 1 through a two-fluid nozzle (not shown) together with supercritical water and an oxidant into the reactor 1;
The other one of the three divisions is to react via a two-fluid nozzle (also not shown) from a second position 3 on the downstream side where it is estimated that the oxidative decomposition of the organic matter introduced at the start end (first position) is completed. The other one is introduced into the reactor 1 from the third position 4 on the further downstream side through a two-fluid nozzle of the same structure, and finally the oxidative decomposition reaction product The figure shows an apparatus for discharging a fluid as a substance from the terminal end portion 6 of the reactor 1 to a pipe 7 of a discharge system. In the illustration of FIG. 1, the pipe 5 of the first supply system to the starting end 2 of the reactor 1
It is shown that the three fluids are mixed in the middle of the process, but this is for the sake of simplicity and does not necessarily indicate the actual configuration of the device.

As an industrially advantageous apparatus, a configuration is adopted in which each substance is supplied (introduced) into the reactor via a two-fluid nozzle (not shown) at the above-mentioned starting end portion 2, and more preferably through an inner pipe. A configuration is adopted in which organic matter to be decomposed is supplied and supercritical water mixed with an oxidant is supplied through an outer tube. Similarly, at the downstream positions 3 and 4 where the organic matter is introduced, a configuration is preferably adopted in which the organic matter to be decomposed is supplied through the inner pipe of a two-fluid nozzle (not shown) and the oxidant is supplied through the outer pipe.

The introduction of an organic substance through a two-fluid nozzle, in particular, the introduction of an organic substance to be decomposed by using an externally mixed two-fluid nozzle in which a plurality of substances are mixed immediately after being discharged from the nozzle discharge port, As described above, it is possible to obtain a preferable mixed state of the oxidant and the oxidizing agent (and supercritical water) without unevenness, and thus it is effective for complete decomposition of the introduced organic matter.

As the two-fluid nozzle used in this embodiment, a design suitable for each specific supercritical water oxidation apparatus is adopted, but in principle, a structure known as a two-fluid nozzle is used. Can be adopted. Examples of the two-fluid nozzle used in the reactor start portion 2 include a suitable one disclosed in, for example, Combustion Engineering 2nd Edition (by Yukio Mizutani: Morikita Publishing). Further, as the two-fluid nozzle used at the downstream positions 3 and 4, a structure is adopted in which the nozzle is fitted into the central portion from the side wall of the reactor and the introduced substance is ejected toward the downstream side. be able to. In addition, it is also possible to exemplify a configuration in which a discharge port is provided circumferentially on a wall surface of a pipe-shaped tubular reactor, and an organic substance is spouted obliquely from the outlet toward the center of the reactor, for example, a tube. .

As the tubular reactor 1 exemplified in this embodiment, a tubular reactor made of a heat-resistant and pressure-resistant material and having a pipe shape can be used. Are designed in consideration of the amount of decomposition processing, time, and the like. The discharge system can be usually formed by connecting a pipe having the same diameter as the reactor.

In the structure of this example, in order to make the inside of the reactor suitable for the supercritical water oxidation reaction, each of the above-mentioned feeds (introduced products) is subjected to predetermined conditions at the time of introduction into the reactor. To be put down. That is, the supply system of each substance is configured to have predetermined heating and pressurizing treatment means (not shown). Specifically, the pressure condition is such that the organic substance to be decomposed, supercritical water, and the oxidizing agent are respectively The water is pressurized to a pressure not lower than the critical pressure of water of 22 MPa or more by a pressurizing means such as a high-pressure pump (not shown). Regarding the temperature condition, the supercritical water is at a critical temperature of water of 374 ° C. or more, preferably 500 ° C. or more.
Heated to about 600 ° C., the organic matter to be decomposed is not preheated or is preheated to a temperature low enough not to cause polymerization or charring. The oxidizing agent is mixed with the supercritical water with or without heating as required.

Supply of each substance to each introduction position of the supercritical water oxidation apparatus having a tubular reactor provided so as to introduce the organic matter to be decomposed into three positions in this example shown in FIG. FIG. 2 shows an example of the relationship between the amount and the amount of the reaction product discharged from the reactor. Of the symbols and numerical values shown in FIG. 2, the symbol F indicates an organic substance, A indicates an oxidizing agent, and S indicates supercritical water, and the numerical values are necessary for an ideal reaction conceivable in a specific organic substance to be decomposed. The present invention is not limited to these values, because these values are exemplarily shown, and these numerical values differ depending on the substance to be decomposed.
Next, supercritical water oxidation performed in the apparatus of the present embodiment will be described. Organic substances to be decomposed that are not preheated or preheated to a low temperature are introduced (press-fitted) from the starting end 2 of the tubular reactor, and from the starting end. Immediately after being introduced into a reactor of a fixed length (hereinafter referred to as “first reaction zone 10”), 500 to 60
By mixing with supercritical water at 0 ° C., the temperature becomes higher than the critical point and a rapid oxidation reaction is started.

Then, in the first reaction zone 10, the temperature rises in a plug flow manner along the flow direction, and after reaching the maximum reaction temperature, the reaction is continued for a certain period of time to complete oxidative decomposition. Usually, the maximum reaction temperature is 550-650
° C. Here, the capacity of the first reaction zone is a volume sufficient to completely decompose the organic substance to be decomposed, and is usually 1 to 2 minutes in terms of the reaction time.

Next, when the product fluid (process fluid) completely oxidatively decomposed enters a range downstream of the position 3 in FIG. 1 (hereinafter referred to as “second reaction zone 11”), the flow rate of the decomposition target is adjusted again. The organic matter and the oxidant are introduced into the reactor 1 from the pipe 8 of the second supply system to the second position via a two-fluid nozzle that allows the organic matter to be decomposed to pass through the inner pipe and the oxidant through the outer pipe. The organic matter to be decomposed introduced here is in reaction zone 1
By mixing with the processing fluid completely decomposed at 0, the temperature becomes higher than the critical point and the oxidation reaction proceeds again.

Next, when the processing fluid completely oxidatively decomposed enters a range downstream of the position 4 in FIG. 1 (hereinafter referred to as a “third reaction zone 12”), the decomposition-targeted organic matter is adjusted again. And the oxidizing agent are introduced into the reactor 1 from the piping 9 of the third supply system to the third position 4 via a two-fluid nozzle that passes the organic matter to be decomposed through the inner tube and the oxidizing agent through the outer tube. Similarly to the second reaction zone 11, the introduced organic substance to be decomposed reaches a temperature higher than the critical point due to mixing with the processing fluid from the second reaction zone 11, and the oxidation reaction proceeds again. The treatment fluid that has finally undergone oxidative decomposition is
It is discharged from the reactor 1 through a discharge system pipe 7.

Although not shown, the processing fluid discharged from the reactor 1 is subjected to heat recovery, cooling and decompression, and is discharged under atmospheric pressure. It is preferable to perform the production (heating) of supercritical water for introduction because it is excellent in terms of heat balance.

According to the apparatus of the present embodiment configured as described above in a three-part system for organic substances, in the case described in Table 1, a part of the tubular reactor 1 is located at the start end (first position). The amount of supercritical water supplied together with the organic matter can be reduced to about one-fifth and the amount of the introduced organic matter can be reduced to about one-fifth as compared with a method in which the whole amount of the organic matter is supplied to the starting end. Also, the amount of the introduced organic matter at the third position where the amount to be divided and introduced is the largest is about half as compared with the total amount at the start end.

From these facts, the amount of supercritical water introduced into the reactor can be greatly reduced, and the amount of organic matter to be divided and introduced into each position is also small, so that the organic matter and the oxidizing agent are easily mixed. It is possible to eliminate or significantly reduce the possibility that undecomposed products pass through the reactor due to poor decomposition due to uneven distribution of organic substances.

The apparatus of this embodiment has a simple structure of a tubular reactor, so that it is relatively easy to industrially implement the apparatus and the equipment cost can be reduced. When the target is an organic substance that does not generate a salt by alkali neutralization because it does not produce an acid by oxidation, or when a salt is generated, it does not cause problems such as clogging due to adhesion to the wall of the reactor etc. Effectively used for critical hydroxylation treatment.

Embodiment 2 The present embodiment shown in FIG. 3 shows an example in which the present invention is applied to a Bessel type reactor.

In FIG. 3, a first reactor 101, a second reactor 102, and a third reactor 103 each represent a Bessel type reactor, for example, as described in JP-A-3-50026 described above.
As described in No. 4, a supercritical region is formed in the upper part of the vessel and a subcritical area is formed in the lower part of the vessel, and each fluid for supercritical water oxidation is supplied from the upper part of the vessel. At the same time, from the upper part of the vessel, a substance of low density generated by supercritical water oxidation (completely decomposed and substantially supercritical water, carbon dioxide)
Is configured to be discharged. Note that these three reactors 101 to 103 have different connections to the supply system and discharge system pipes, but have the same other structure, and are connected to the series by short connection pipes 104 and 105.

The first reactor 101 has a two-fluid nozzle (not shown) of an external mixing type facing inward from the upper part of the reactor. The organic matter to be decomposed, which is not preheated or preheated to a low temperature, is introduced through the inner tube, and supercritical water of, for example, 500 to 600 ° C. to which an oxidizing agent is added is introduced through the outer tube. In the lower part of the vessel, subcritical water is stored at a certain depth at a temperature lower than the critical temperature, and the subcritical water is discharged out of the vessel little by little through a subcritical water introduction pipe and a discharge pipe (not shown). It is configured to discharge salts dissolved in subcritical water out of the vessel. Moreover,
The connection pipe 104 is connected to the upper part of the vessel, and the processing fluid is introduced into the second reactor 102 through the inner pipe of a two-fluid nozzle provided at the upper part of the second reactor 102. I have.

The second reactor 102 introduces the organic matter to be decomposed from the supply system piping 108 through the inner pipe of the two-fluid nozzle provided at the upper part of the reactor, and the first reactor 101 through the outer pipe.
The first reactor is different from the first reactor in that a generated fluid (processing fluid) from the first reactor is introduced, but is otherwise the same as the first reactor 101. The processing fluid generated in the second reactor 102 is sent to the third reactor 103 via the connection pipe 105.

The third reactor 103 introduces the organic matter to be decomposed from the supply system piping 109 through the inner pipe of the two-fluid nozzle provided at the upper part of the reactor, and the second reactor 102 through the outer pipe.
The second reactor is different from the second reactor in that a generated fluid (processing fluid) from the reactor is introduced and a processing fluid is discharged to a discharge system through a discharge pipe connected to the upper part of the vessel. However, the rest is the same as the second reactor 102.

The two-fluid nozzle used in the reactor of this example has
The same one as used in the first embodiment is used.

Next, the supercritical water oxidation performed in the apparatus of the present embodiment will be described by taking as an example the case of oxidatively decomposing a hardly decomposable and harmful organic substance. In addition, since this organic matter produces an acid as a by-product of the oxidative decomposition, an alkali for neutralizing the acid is introduced. First, in the first reactor 101,
Organic matter and alkali to be decomposed, not preheated or preheated to a low temperature, are introduced (press-fit) from the pipe 107 of the first supply system into the first reactor 101 through the inner pipe of the two-fluid nozzle, and a predetermined amount of oxidation is supplied from the outer pipe. Supercritical water to which the agent has been added is introduced. In this example, the first to third reactors 101, 102,
The total amount of the oxidizing agent required for the oxidation reaction in 103 and the total amount of the alkali required for neutralizing the acid produced as a by-product
It is being introduced in.

Immediately after the introduction of each substance, 500 to 600
By mixing supercritical water and organic matter at a temperature of ° C., the temperature becomes higher than the critical point, and a rapid oxidation reaction is started. This oxidation reaction is continued for a certain period of time to complete oxidative decomposition. Usually, the maximum reaction temperature is 550-650 ° C. here,
The capacity of the first reactor is a volume sufficient to completely decompose the organic substance to be decomposed, and when converted to the reaction time, it is usually 1 to 2 minutes.
The liquid is sent to the second reactor 102 via the gas supply line 04. The by-produced acid is neutralized with the alkali and precipitates as a salt, which falls downward into the subcritical region and dissolves in the subcritical water. This dissolved salt is discharged as the subcritical water is discharged out of the vessel.

Next, the product fluid (process fluid) completely oxidized and decomposed in the first-stage reactor (first reactor 101) passes through the outer pipe of the two-fluid nozzle connected to the pipe 108 of the second supply system. After entering the reactor 102, the organic matter to be decomposed at a controlled flow rate is passed through the inner pipe of the nozzle.
2 is introduced. The organic matter to be decomposed introduced here is
The fluid is mixed with the processing fluid completely decomposed in the former reactor and reaches a temperature higher than the critical point, and the oxidation reaction proceeds again. The processing fluid generated by the oxidative decomposition is sent to the third reactor 103 via the connection pipe 105.

In the third reactor 103, the second reactor 1
Oxidative decomposition similar to 02 is performed. That is, the processing fluid from the former reactor (second reactor 102) is introduced through the outer pipe of the two-fluid nozzle connected to the pipe 109 of the third supply system, and at the same time, the organic matter to be decomposed is passed through the inner pipe of the nozzle. After being introduced, the temperature becomes higher than the critical point by mixing, and the oxidation reaction proceeds again. The treatment fluid that has been finally subjected to the oxidative decomposition treatment is discharged from the piping 106 of the discharge system.

According to the apparatus of the present example in which the above-mentioned organic substances are introduced into three vessel reactors connected in series in three parts, the first reactor 101 is used in the case described in Table 1 above. The amount of supercritical water supplied together with some organic matter can be reduced to about one-fifth and the amount of introduced organic matter can be reduced to about one-fifth as compared with a system in which the whole amount of organic matter is supplied to one vessel type reactor. Decrease. Also, in the third reactor 103 where the amount to be divided and introduced is the largest, the introduced amount of the organic substance is about half as compared with the whole amount system.

From these facts, the amount of supercritical water introduced into the reactor can be greatly reduced, and the amount of organic matter divided and introduced into each position is also small, so that the organic matter and the oxidizing agent can be easily mixed. It is possible to eliminate or significantly reduce the possibility that undecomposed products pass through the reactor due to poor decomposition due to uneven distribution of organic substances.

The apparatus of this embodiment uses a Bessel type reactor, and is suitable for oxidative decomposition of hardly decomposable organic substances and harmful organic substances, especially for decomposition of organic substances by which an acid is by-produced by the reaction. An industrially excellent apparatus capable of completely decomposing these organic substances in a closed system can be provided.

[0086]

As described above, according to the present invention, the following various excellent effects can be obtained.

The invention according to claim 1 of the present application, that is, a fluid containing an organic substance to be decomposed is continuously supplied to a reaction zone under conditions where the temperature and pressure are equal to or higher than the critical point of water, and the presence of supercritical water in the reaction zone. A supercritical water oxidation method that oxidizes and decomposes organic substances below and continuously discharges a reaction product fluid from the reaction area, and introduces decomposition target organic substances from a plurality of positions separated in a direction in which the fluid in the reaction area flows, At the first stage introduction position, the organic matter to be decomposed and supercritical water are mixed at the time of introduction or introduced immediately after mixing, and at the introduction position after the next stage, the organic matter to be decomposed is introduced again into the fluid generated by the reaction at the previous stage. According to the invention of the supercritical water oxidation method, it is possible to rapidly raise the temperature of the organic substance to be decomposed above the critical temperature by dividing and introducing (supplying) the organic substance to be decomposed, and to phase-shift the organic substance in a high temperature state. Or loose Polymerizing and charring of decomposed organic matter resulting from the heat can be prevented, complete degradation of the target organic matter can be achieved. Further, since the amount of supercritical water supplied to the reactor from the outside is small, it is advantageous in terms of energy, and the amount of fluid discharged from the reactor is also small. From these facts, miniaturization of the entire facility including the supercritical water oxidation apparatus and its supply system and discharge system can be realized.

According to the second aspect of the present invention, the effects of the present invention can be achieved by using a tubular reactor having a simple structure, and in particular, the decomposition treatment of an organic substance without acid generation can be suitably performed. According to the third aspect of the present invention, the acid generated by oxidative decomposition can be dissolved in subcritical water from the subcritical region and discharged, so that the problem of clogging with the salt precipitated in the supercritical region and the like can be avoided, The effects of the invention can be achieved, and in particular, a process can be suitably performed when an organic substance that forms a salt by alkali neutralization is used as a decomposition target.

Further, it is particularly useful for supercritical hydroxylation of hardly decomposable organic substances such as PCBs, trichlorethylene, tetrachloroethylene, organic chlorine compounds such as waste agricultural chemicals, and harmful organic substances, which are usually considered to generate salts by alkali neutralization. It is.

According to the fifth aspect of the present invention, the organic matter to be decomposed can be preheated to a low temperature or supplied to the reactor without preheating, so that polymerization, charring, etc. can be prevented. Can be omitted or simplified.

According to the invention of the supercritical water oxidation apparatus according to the eleventh aspect, the organic matter to be decomposed is divided into two parts: from the starting end of the tubular reactor and from one or more positions downstream of the reactor. In the split supply position on the downstream side, the generated fluid (supercritical water) from the previous stage is used as the solvent for the organic matter to be decomposed on the downstream side, and the heat also serves as a preheat source for the introduced organic matter. Supply of supercritical water becomes unnecessary. This can reduce the amount of supercritical water supplied to the reactor. Further, the reduction of the energy for producing supercritical water and the reduction of the amount of discharged fluid are realized, and the effect is obtained that the organic substance to be decomposed can be heated to a critical temperature or higher at a stretch with a small amount of energy.

Also, the amount of the organic substance to be decomposed supplied at each of the divided positions, including the starting end of the reactor, can be relatively reduced as compared with the conventional method in which the whole amount is supplied at the starting end, and the organic substance and the supercritical Since water can be mixed in a favorable state, complete decomposition of particularly difficult-to-decompose organic substances and harmful organic substances can be effectively realized.

According to the supercritical water oxidation apparatus of the twelfth aspect, since the organic matter to be decomposed is divided and supplied to the first stage reactor and one or more reactors after the second stage, the two stages are supplied.
In the reactors after the first stage, the fluid (supercritical water) generated in the previous stage becomes a solvent for the organic matter to be decomposed and also serves as a preheating source, so that external supply of supercritical water is not required, and the fluid is supplied to the first stage reactor. The amount of supercritical water can be reduced. This reduces supercritical water production energy, reduces discharge fluid, prevents polymerization reaction and charring in piping etc. that supply organic substances to be decomposed to the reactor, and raises the supplied organic substances at once with less energy. An efficient supercritical water oxidation apparatus that can be heated can be provided.

Since a vessel type reactor is used,
It can be used particularly preferably for decomposing organic substances containing substances that generate acids, such as hardly decomposable organic substances and harmful organic substances.

According to the invention of claim 13, the mixing means for mixing and introducing the organic substance to be decomposed and supercritical water into the starting end portion of the tubular reactor or the first-stage Bessel type reactor is a two-fluid nozzle. For example, by adjusting the shape of the nozzle and the flow rate of the inner and outer pipes, it becomes possible to supply the organic matter to be decomposed with a predetermined particle size into the reactor. realizable.

Further, the apparatus using the Bessel type reactor can prevent a problem that unresolved organic or harmful organic substances fall into the lower subcritical region and prevent harmful organic substances from being discharged to the outside. Above is very effective. Furthermore, by not making the particle size of the precipitated salt too small, it is possible to prevent the precipitated salt from being discharged from the last reactor to a discharge system downstream, and there is a possibility that pipes and heat exchangers and the like after the reactor may be blocked. Can be eliminated.

According to the fourteenth aspect of the present invention, an organic substance to be introduced into the downstream side of the tubular reactor or into the vessel reactor of the second and subsequent stages is efficiently mixed with the oxidizing agent by using a two-fluid nozzle. Therefore, there is an effect that the complete decomposition of the organic substance can be further reliably performed.

From these facts, the method and apparatus for supercritical water oxidation treatment of the present invention can provide a method and apparatus which are very technically and economically advantageous when the method is carried out industrially.

In particular, since the amount of the organic substance introduced at each position is small due to the divisional introduction, the mixture of the introduced organic substance, supercritical water, and the oxidizing agent can be satisfactorily given, and the amount of the hardly decomposable organic substance and the harmful organic substance An excellent effect of being extremely effective for complete oxidative decomposition is achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a supercritical water oxidation apparatus according to the present invention constituted by using a tubular reactor in a frozen state.

FIG. 2 is a view for explaining a relationship between supply amounts of organic substances, supercritical water and an oxidizing agent to each divided introduction position in the apparatus of FIG. 1, and discharge amounts to a discharge system.

FIG. 3 is a flow diagram showing another embodiment of the supercritical water oxidation apparatus according to the present invention constituted by using a Bessel type reactor.

FIG. 4 is a diagram for explaining temperature rise of a mixture when supercritical water is mixed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tubular reactor, 2 ... Start part, 3 ... Second position, 4 ... Third position, 5 ... First supply system piping, 6
... Terminal part, 7 ... Discharge system piping, 8 ... Second supply system piping, 9 ... Third supply system piping, 10 ... First reaction zone, 11 ... Second reaction zone, 12 ...
Third reaction zone. 101 ... first reactor, 102 ...
・ Second reactor, 103 ・ ・ ・ Third reactor, 104, 10
5 Connection pipe, 106 Pipe of discharge system, 107
... piping of the first supply system, 108 ... piping of the second supply system, 109 ... piping of the third supply system.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Noriyuki Ayo 1-4-9 Kawagishi, Toda City, Saitama Prefecture Organo Research Institute

Claims (18)

[Claims] 1. A fluid containing an organic substance to be decomposed is continuously supplied to a reaction zone under conditions where the temperature and pressure are equal to or higher than the critical point of water, and the organic substance is oxidatively decomposed in the reaction zone in the presence of supercritical water. A supercritical water oxidation method of continuously discharging a reaction product fluid from a reaction region, wherein organic substances to be decomposed are introduced from a plurality of positions separated in a direction in which the fluid in the reaction region flows, and at the first stage introduction position, The supercritical fluid is characterized in that the organic substance to be decomposed and supercritical water are mixed at the time of introduction or are introduced immediately after mixing, and the organic substance to be decomposed is introduced again into the fluid produced in the previous step at the next and subsequent introduction positions. Hydroxidation method. 2. A supercritical water oxidation method for oxidatively decomposing organic matter in the presence of supercritical water in a tubular reactor having a reaction zone under a condition in which the temperature and pressure are equal to or higher than the critical point of water. The organic substance to be decomposed and the supercritical water are mixed at the time of introduction into the beginning of the tubular reactor, or mixed immediately and then introduced immediately to carry out the oxidative decomposition reaction, and oxidize the organic substance introduced into the tubular reactor. The oxidative decomposition reaction is continued by re-introducing the organic substance to be decomposed to a predetermined position in the fluid generated by the decomposition reaction,
A supercritical water oxidation method characterized in that the re-introduction operation of the organic substance to be decomposed for continuing the oxidative decomposition reaction is performed at at least one or two or more positions along the flow direction of the fluid in the reactor. 3. A plurality of vertical cylindrical reactors having a reaction region under supercritical conditions in which the temperature and pressure are equal to or higher than a critical point of water in the upper part of the reactor and a subcritical region in the lower part of the reactor. In contrast, while the fluid continuously flows through the reaction area of each reactor,
A supercritical water oxidation method for oxidatively decomposing organic substances in the presence of supercritical water in each reaction zone.In the reaction zone of the first-stage reactor, an organic substance to be decomposed and supercritical water are mixed or mixed when introduced. Immediately after that, the oxidative decomposition reaction is performed,
A supercritical water oxidation method, characterized in that a fluid generated by a reaction in the preceding step is flowed into a reaction region of a reactor in a subsequent step and an organic substance to be decomposed is introduced again. 4. The method according to claim 1, wherein
A supercritical water oxidation method, wherein the organic substance to be decomposed is a hardly decomposable organic substance or a harmful organic substance. 5. The method according to claim 1, wherein
A supercritical water oxidation method, wherein the organic matter to be decomposed is preheated to a low temperature or mixed with supercritical water without preheating so as to reach a critical temperature or higher. 6. The supercritical water oxidation method according to claim 5, wherein the temperature of the supercritical water introduced into the reaction zone is 500 to 650 ° C. 7. The method according to claim 1, wherein
The oxidizing agent necessary for the oxidative decomposition of the organic substance to be decomposed is mixed with the organic substance to be decomposed or supercritical water and introduced into the reaction zone,
Alternatively, a supercritical water oxidation method characterized by mixing at the time of introduction into the reaction zone. 8. The decomposition method according to claim 7, wherein the whole amount of the oxidizing agent necessary for oxidative decomposition of the organic substance to be decomposed introduced into the reaction zone is introduced into the first reaction zone, or is divided and introduced into the reaction zone. A supercritical water oxidation method, wherein the target organic substance is introduced at each position in accordance with the amount of the organic substance introduced at each position. 9. The method according to claim 1, wherein
An alkali that neutralizes the acid generated by the supercritical water oxidation reaction is mixed with any of organic substances to be decomposed, supercritical water, or an oxidizing agent and introduced into the reaction zone, or mixed at the time of introduction into the reaction zone. A supercritical water oxidation method characterized by the above-mentioned. 10. The method according to claim 9, wherein the entire amount of alkali necessary for neutralizing the acid generated by the supercritical water oxidation reaction is introduced into the first-stage reaction zone, or is divided and introduced into the reaction zone. A supercritical water oxidation method characterized by dispensing each position of an organic substance to be decomposed in accordance with the introduced amount at each position. 11. A tubular reactor for forming conditions for a supercritical water oxidation reaction, supply means for continuously supplying a fluid containing an organic substance to be decomposed to the reactor, Discharge means for continuously discharging the organic matter to be decomposed by dividing into the starting end of the tubular reactor and at least one or more positions on the downstream side along the flow of the fluid. A supercritical water oxidation apparatus provided so as to have a position where the organic substance to be decomposed and the supercritical water are mixed with each other, and the supply means to the starting end of the tubular reactor is provided with mixing means. 12. A plurality of vertical tubular reactors having a supercritical region for performing a supercritical hydroxylation reaction in the upper part of the reactor and a subcritical region in a lower part of the reactor, and a supercritical reactor of each reactor. A pipe that is substantially continuous in the region, a supply unit that supplies the organic substance to be decomposed to the supercritical region of each reactor, a discharge unit that discharges a reaction product fluid from the supercritical region of the last reactor, A supercritical water oxidation apparatus configured to include a salt discharge unit that discharges subcritical water in which salts are dissolved from the subcritical region of the reactor, and supplies the organic matter to be decomposed to the supercritical region of the first-stage reactor. A supercritical water oxidation apparatus characterized in that the supplying means includes mixing means for mixing the organic matter to be decomposed and supercritical water. 13. A supercritical water oxidation apparatus according to claim 11, wherein the mixing means for mixing the organic matter to be decomposed and the supercritical water and introducing the mixture into the reactor is a two-fluid nozzle. 14. The two-fluid mixture according to claim 11, further comprising an introduction means for introducing the organic matter to be decomposed at a downstream position excluding the starting end of the tubular reactor, wherein the introduction means mixes the organic matter to be decomposed with the oxidizing agent. A supercritical water oxidation device characterized by being a nozzle. 15. The method according to claim 12, further comprising an introducing means for mixing and introducing the organic matter to be decomposed and the reaction product fluid from the preceding reactor into the second and subsequent reactors.
A supercritical water oxidation apparatus comprising a two-fluid nozzle for mixing an organic substance to be decomposed and the reaction product fluid. 16. The two-fluid nozzle according to claim 13, wherein the two-fluid nozzle passes the organic matter to be decomposed through the inner tube,
A supercritical water oxidation apparatus characterized in that another substance to be mixed with the organic substance to be decomposed is passed through an outer tube. 17. The supercritical water oxidation apparatus according to claim 16, wherein the oxidizing agent is introduced through an outer tube of the two-fluid nozzle. 18. The supercritical water oxidation apparatus according to claim 16, wherein the two-fluid nozzle is of an external mixing type.