JP2004000825A - Hydrothermal oxidation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrothermal oxidation method which enables the initiation of hydrothermal oxidation with safety and in a short time. <P>SOLUTION: The hydrothermal oxidation method comprises a preheating process of heating a reactor preliminarily before performing the hydrothermal oxidation of an object to be treated and a hydrothermal oxidation process of supplying the object to be treated to the reactor and performing the hydrothermal oxidation in a supercritical condition or a subcritical condition of water. Therein, in at least one part of the preheating process and in at least one part of the transition stage from the preheating process up to a steady state in the hydrothermal oxidation process, the heating is performed in such a manner that the pressure of the reaction system becomes a pressure lower than the pressure on the steady state of the hydrothermal oxidation process. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydrothermal oxidation reaction method in which a hydrothermal oxidation reaction used for decomposition of waste, energy generation, or production of chemical substances is performed in a supercritical or subcritical state of water.
[0002]
[Prior art]
The hydrothermal oxidation reaction treatment that treats waste, generates energy, and manufactures chemical substances by treating the object to be treated and performing oxidative decomposition and hydrolysis has been studied for more than 30 years, It's being used.
In particular, in recent years, in a supercritical or subcritical state of water, an oxidation reaction including combustion (hereinafter, sometimes simply referred to as a reaction) is performed by reacting an object to be treated with water containing an oxidizing agent in a reactor. Attention has been paid to a hydrothermal oxidation reaction treatment that causes the organic matter in the object to be treated to be almost completely decomposed in a short time.
[0003]
When such a hydrothermal oxidation reaction is performed, when the hydrothermal oxidation reaction is started, that is, when the hydrothermal oxidation reaction device is started, the reactor is usually heated to a predetermined temperature, and then the object to be treated is The hydrothermal oxidation reaction is performed when introduced.
For example, in Japanese Patent Application Laid-Open No. H10-156175, the temperature is raised at the same reaction pressure as during the steady-state reaction, and the material to be treated is supplied after the temperature required for the hydrothermal oxidation reaction is reached. At this time, supercritical water is used as a medium for raising the temperature, and is supplied to the reactor.
[0004]
Japanese Patent Application Laid-Open No. H11-244885 describes a method of performing a hydrothermal oxidation reaction after supplying a high-temperature and high-pressure fluid generated by burning a combustible fluid with a high-temperature fluid generation device to a reactor and preheating the reactor. ing.
However, in these conventional methods, when the object to be treated is introduced into the reactor and the hydrothermal oxidation reaction is started, or when the combustion is started in the high-temperature fluid generator, the oxidation reaction is started at once, so that the temperature is rapidly increased. The pressure may rise due to the rise and the accompanying shock. For this reason, there has been a need for a method for preventing the pressure from excessively rising and performing the reaction safely.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to propose a hydrothermal oxidation reaction method that can start a hydrothermal oxidation reaction safely and in a short time.
[0006]
[Means for Solving the Problems]
The present invention is the following hydrothermal oxidation reaction method.
(1) a preheating step of heating the reactor in advance before performing the hydrothermal oxidation reaction of the object;
A hydrothermal oxidation reaction step of supplying an object to be processed to a reactor and performing a hydrothermal oxidation reaction in a supercritical or subcritical state of water;
In a hydrothermal oxidation reaction method comprising:
At least a part of the preheating step, and at least a part of the process from the preheating step to a transition to the steady state in the hydrothermal oxidation reaction step, the pressure of the reaction system is increased during the steady state of the hydrothermal oxidation reaction step. Heat at a pressure lower than the pressure
Hydrothermal oxidation reaction method.
(2) In the preheating step, a method of supplying a high-temperature and high-pressure fluid to the reactor, a method of supplying a combustible organic substance to the reactor and performing a hydrothermal oxidation reaction in the presence of water and an oxidizing agent, or a combination of these methods (1) The hydrothermal oxidation reaction method according to the above (1).
(3) At least part of the preheating step and at least part of the process from the preheating step to the transition to the steady state in the hydrothermal oxidation reaction step, the pressure of the high-pressure fluid circulation part of the reaction system is increased by the hydrothermal oxidation reaction step. The hydrothermal oxidation reaction method according to the above (1) or (2), wherein the method is carried out in a state controlled by a pressure reducing means so as to be lower than the pressure in the steady state.
[0007]
In the present invention, at least a part of the preheating step, and at least a part of the process from the preheating step to the transition to the steady state in the hydrothermal oxidation reaction step, the pressure of the reaction system is the pressure in the steady state of the hydrothermal oxidation reaction step. Heating is performed at a lower pressure, preferably 0.5 to 8 MPa, more preferably 0.5 to 4 MPa lower than the pressure in a steady state. If the temperature is too low, the preheating step by the hydrothermal oxidation reaction will not be stable, the efficiency of preheating will decrease, or it will take a long time to shift to a steady state.
Here, the steady state means a state in which the supply amount of the object to be treated, the supply amount of the oxidizing agent, the reaction temperature and the reaction pressure are substantially constant, and the processing is continued while maintaining a stable reaction state.
[0008]
In the preheating step and the process up to the transition to the steady state, it is not necessary to maintain all of the processes or processes at a pressure lower than the steady state pressure. The pressure may be controlled to be lower than the time.
[0009]
The preheating step may be heated to a temperature at which the hydrothermal oxidation reaction of the object to be processed is started in the subsequent hydrothermal oxidation reaction step, and may be heated to the same temperature as that in the steady state or lower. However, it is usually preferable to heat to 550 to 700 ° C.
As the heating method, 1) a method of supplying a high-temperature and high-pressure fluid to a reactor (hereinafter, referred to as a first heating method), 2) a supply of a combustible organic substance to the reactor, and a water supply in the presence of water and an oxidizing agent. A method of performing a thermal oxidation reaction (hereinafter, referred to as a second heating method), 3) a method of using these methods in combination, or the like can be employed. When using together, the first heating method and the second heating method can be performed in parallel or sequentially.
[0010]
In the first heating method, a high-temperature and high-pressure fluid is supplied to a reactor and heated. The high-temperature and high-pressure fluid used at this time is generated by introducing a combustible fluid and an oxidant into a high-temperature fluid generator having a pressure-resistant container, a fuel introduction path, an oxidant introduction path, and a high-temperature fluid discharge part, and burning the same. (Japanese Unexamined Patent Publication No. 11-244885). An oxidizing reaction is started by supplying a flammable fluid to a high-temperature fluid generator that is provided with an ignition device and supplies an oxidizing agent (eg, air) at a high pressure, and the high-pressure high-temperature fluid is discharged from the high-temperature fluid discharge unit. Therefore, this high temperature and high pressure fluid is supplied to the reactor. When the oxidation reaction is started in this high-temperature fluid generation device, the pressure in the reaction system (system) that performs the hydrothermal oxidation reaction increases due to the rapid temperature rise of the high-pressure fluid. Therefore, in the process of starting the oxidation reaction in the high-temperature fluid generation device, pressure control is performed so that the pressure becomes lower than the pressure in the steady state. The pressure in the reaction system during the heating is controlled by a gas pressure reducing valve provided at the latter stage of the reaction system. This pressure reducing valve may measure the pressure of an appropriate portion in the reaction system that becomes high pressure, and control the pressure to be a set value. The set value of the pressure is controlled to a pressure lower than the pressure in a steady state, based on a portion of the reaction system that becomes a high pressure and having the least design pressure margin at the temperature during use. Generally, the temperature at the start of preheating is low in a portion where a high-temperature fluid flows, and there are many cases where there is a margin for the strength against the pressure. Therefore, it is preferable to control the temperature in a portion where the temperature is low even in a steady state.
[0011]
Examples of the flammable fluid used in the first heating method include heavy oil, light oil, kerosene, gasoline, natural gas, LPG, and the like. Air is preferred as the oxidizing agent, but oxygen, hydrogen peroxide, ozone, and other oxidizing substances can also be used. As a specific example of the high-temperature fluid generation device, a high-temperature fluid generation device as described in Japanese Patent Application Laid-Open No. H11-244885 is exemplified.
[0012]
At the stage where the temperature inside the reactor reaches a temperature sufficient for the hydrothermal oxidation reaction to be performed in a steady state by the first heating method, supply of the object to be treated is started. At this time, if a large amount of the material to be treated is added at once, there may be a problem that the temperature in the reactor decreases and unreacted material remains, so the material to be treated is supplied little by little at first. Preferably, the supply amount is gradually increased. When the reaction of the object to be processed progresses stably, the supply of the high-temperature and high-pressure fluid may be stopped, but the supply may be continued if necessary.
[0013]
In the second heating method, a combustible organic substance is supplied to a reactor, a hydrothermal oxidation reaction is caused in the presence of water and an oxidizing agent, and the reactor is heated by the reaction heat.
In the second heating method, as in the first heating method, when the hydrothermal oxidation reaction starts in the reactor, the reaction heat causes a rapid temperature rise of the high-pressure fluid, and the pressure in the reaction system rises. I do. Therefore, in the process of starting the hydrothermal oxidation reaction in the reactor, the pressure is controlled so as to be lower than the pressure in a steady state. The pressure in the reaction system during heating is controlled by a pressure reducing valve at the latter stage of the reaction system. This pressure reducing valve may measure the pressure of an appropriate portion in the reaction system that becomes high pressure, and control the pressure to be a set value. The set value of the pressure is controlled to a pressure lower than the pressure in a steady state, based on a portion of the reaction system that becomes a high pressure and having the least design pressure margin at the temperature during use. In the second preheating step, since the temperature of a portion that becomes high in a steady state is high, it is preferable to control the pressure based on the pressure of a portion (for example, a reactor) that has a high risk of increasing the pressure.
[0014]
As the above-mentioned flammable organic substances, those having high ignitability, high safety and low cost are preferable. Specifically, hydrocarbons such as kerosene and alcohols such as isopropyl alcohol are preferable.
Ignition is important to ensure that the hydrothermal oxidation reaction is initiated when flammable organics are fed into the preheated reactor. In the case of a substance with poor ignition, there is a concern that the hydrothermal oxidation reaction does not occur, and even if it proceeds, the unstable state becomes longer.
Also, at the beginning of the second heating method, the reactor temperature is considerably lower than in the steady state, and undecomposed substances may remain particularly immediately after the start of the hydrothermal oxidation reaction. Therefore, if there is a problem in the safety of itself and the undecomposed products, it becomes necessary to treat the waste liquid at the time of preheating again. Specifically, those containing a halogen, a hetero atom (N, P, S, etc.), a benzene ring, and the like may generate toxic substances, and thus are preferably not used as flammable organic substances.
[0015]
The oxidizing agent used in the second heating method includes air, oxygen, liquid oxygen, aqueous hydrogen peroxide, ozone, and other oxidizing substances. The oxidizing agent may be supplied as a mixture with the combustible organic substance, or may be supplied under pressure and separately from the combustible organic substance. As the oxidizing agent, high-pressure air used as an oxidizing agent for generating a high-temperature and high-pressure fluid can be supplied through a high-temperature fluid generating device.
[0016]
In the preheating step, the first and second heating methods can be used in combination. In this case, it is preferable that the reactor is heated by the first heating method and then further heated by the second heating method.
[0017]
When the first and second heating methods are used in combination, in the first heating method, the combustible organic substance is heated to a minimum temperature at which the hydrothermal oxidation reaction can occur, and then the second heating method is performed. It is preferred to heat with.
The minimum temperature at which the flammable organic substance can cause a hydrothermal oxidation reaction varies depending on the type and properties of the flammable organic substance used. For example, when kerosene is used as the flammable organic substance, it is 350 ° C. or higher. If this temperature is too low, a large amount of incompletely combusted products will be generated, and if it is too high, it will take time to raise the temperature, so an appropriate temperature is selected. Then, it heats further by the 2nd heating method and heats to 550-700 degreeC.
[0018]
Also, at the beginning of the second heating method, if the temperature is low, the hydrothermal oxidation reaction may be unstable, so the first heating method and the second heating method may be used until the hydrothermal oxidation reaction in the reactor is stabilized. It is preferable to use the above heating method in combination. Even when the first preheating step is stopped after the combined use, a pressure change accompanying a temperature change may occur, so that the pressure of the reaction system is preferably controlled to be lower than that in the steady state. Since the temperature of the reactor at this stage is usually the highest, the control is performed based on the pressure in the reactor. When it is difficult to measure the pressure in the reactor, the pressure can be controlled based on a pressure indication value of a portion showing a value close to the pressure in the reactor.
[0019]
In the preheating step, when the temperature in the reactor reaches a temperature sufficient to cause the hydrothermal oxidation reaction of the material to be treated, the process shifts to the hydrothermal oxidation reaction step, and the supply of the material to the reactor is started. Start. At this time, if a large amount of the material to be treated is added at one time, a problem such as a decrease in the temperature inside the reactor and unreacted material remains, so the material to be treated is supplied little by little at first, and gradually. A method of increasing the supply amount is preferable. At the start of the supply of the object, it is preferable to continue the heat treatment in the preheating step in order to maintain the temperature in the reactor, and it is preferable to end the preheating step when the flow rate of the object is stabilized. . Even during such a transition process, large temperature fluctuations occur in the process that starts or stops the supply of flammable organic substances, water, oxidizing agents, etc., or changes in the supply material and amount, which may cause pressure fluctuations There is. For this reason, it is preferable that the pressure of the reaction system is controlled to be lower than in the steady state in this process.
[0020]
The process of controlling the pressure of the reaction system to be lower than the set steady state pressure is preferably performed at the start of the oxidation reaction in the first heating method, at the start of the hydrothermal oxidation reaction in the second heating method, When the preheating step by the method is completed, and the process from the start of the supply of the material to be treated to the steady state, etc., a large pressure fluctuation does not occur depending on the structure of the reaction system apparatus or the type of the material to be treated. There are steps, and such steps do not require low pressure control. In addition, the pressure can be continuously controlled to be low until the process in which the pressure may fluctuate is completed. If the process has no problem of pressure fluctuation, the pressure of the reaction system may be returned to the set pressure in the steady state, and the operation may be continued.
[0021]
The location where the pressure is measured is not particularly limited, but is preferably a high-pressure fluid circulation part of the reaction system. For example, the inside of the reactor, a system downstream of the reactor, and the like can be mentioned. As a method of controlling the pressure, a method of adjusting the opening of a pressure regulating valve, for example, a pressure reducing means provided at the latter stage of the reactor, and the like can be mentioned.
[0022]
In the present invention, after the reactor is preheated by the above-described method, a hydrothermal oxidation reaction of the object is performed as a hydrothermal oxidation reaction step. In the hydrothermal oxidation reaction step, a substance to be subjected to the hydrothermal oxidation reaction, a substance to be reacted such as water or an oxide is supplied to the reactor, and the hydrothermal oxidation reaction is performed.
In the hydrothermal oxidation reaction step, a hydrothermal oxidation reaction can be performed in the same manner as in the related art. A well-known reactor can be used as the reactor. Examples of the object to be treated include a waste liquid containing an organic substance, and the organic substance can be oxidized and decomposed.
[0023]
Here, the hydrothermal oxidation reaction is a reaction in which an organic substance is oxidatively decomposed by an oxidation reaction in the presence of high-temperature and high-pressure water and an oxidizing agent in a supercritical or subcritical state. The supercritical state is a state of 374 ° C. or higher and 22 MPa or higher. The subcritical state refers to, for example, a state of 374 ° C. or more, 2.5 MPa or more and less than 22 MPa, or a state of 374 ° C. or less and 22 MPa or more.
[0024]
Such a hydrothermal oxidation reaction is performed in a reactor in a state where an organic substance is mixed with water and an oxidizing agent, and the mixture undergoes a hydrothermal oxidation reaction inside the reactor. As the oxidizing agent, air, oxygen, liquid oxygen, aqueous hydrogen peroxide, nitric acid, nitrous acid, nitrate, nitrite and the like can be used. The oxidizing agent may be supplied in a state of being mixed with the reactant, or may be supplied as a multi-layer flow by using a double tube nozzle as a supply port. Further, high-pressure air used as an oxidizing agent for generating a high-temperature and high-pressure fluid can be supplied from the high-temperature fluid generation device used in the preheating step.
[0025]
When the calorific value of the object to be treated is insufficient in the hydrothermal oxidation reaction, the reaction can be performed by supplying an auxiliary fuel to the reactor. Examples of the auxiliary fuel include kerosene, isopropyl alcohol, methanol, acetone, and the like. As the auxiliary fuel, the combustible organic substance used in the second heating method can be used. The auxiliary fuel does not need to be a pure substance, and may be, for example, a waste solvent containing another organic substance, inorganic substance, moisture, or the like.
[0026]
The reactor used in the present invention is formed from a heat-resistant, pressure-resistant material and a substantially vertical cylindrical reactor so as to perform a hydrothermal oxidation reaction in a supercritical or subcritical state. When the supercritical or subcritical state is not reached only by the heat of reaction, an external heating means can be provided. The shape of the reactor may be a cylinder, an ellipsoid, or a polygonal cylinder, and the lower end may have a cone shape. When a hydrothermal oxidation reaction is performed in a supercritical or subcritical state by such a reactor, organic substances are oxidized by an oxidizing agent and finally decomposed into water and carbon dioxide, or are decomposed into molecules by hydrolysis. Separates in solid or molten state. The reaction product as it is or after separating solids is separated into a gas, a liquid and a solid by operations such as cooling, decompression, and solid-liquid separation.
[0027]
As the above-mentioned reactor, those conventionally used for hydrothermal oxidation reactions can be used as they are, but as shown in JP-A-11-156186, a mixed reaction zone with a backflow in the upper part and a A mixed flow of the object to be treated and the oxidizing agent is supplied in a downward flow from a supply device provided at an upper portion to a substantially vertical reactor forming a plug-shaped flow reaction region, and the mixed flow is returned in an upper mixing reaction region. And a hydrothermal oxidation reaction is carried out by forming a mixed flow accompanied by the above, and a parallel downward plug flow is formed in the lower plug-like flow reaction zone to perform an additional hydrothermal oxidation reaction.
[0028]
The material of the reactor is not limited, but is preferably a corrosion-resistant material such as Hastelloy, Inconel or stainless steel. Preferably, the reactor is provided with a corrosion resistant liner. The corrosion-resistant liner is not particularly limited, and a corrosion-resistant liner having a gap between the corrosion-resistant liner and the pressure load wall as disclosed in JP-A-11-156186 can be used.
[0029]
The reactor may be provided with cooling means for cooling the reaction mixture before discharging it from the outlet. The cooling means is not particularly limited, but water can be introduced into the reactor to cool it, and the inorganic salt can be dissolved to promote its discharge. In addition, water containing an acid or an alkali can be introduced into the reactor and cooled to neutralize the alkali or the acid. If adhesion of solids into the reactor becomes a problem, a mechanical removal device for removing solids attached to the inner wall of the reactor can be provided. The mechanical removal device for removing solids is not particularly limited, but a substantially cylindrical scraper including a cutout window portion disclosed in Japanese Patent Application Laid-Open No. H11-156186 is preferred. Further, when the neutralized salt is deposited in the reactor as the hydrothermal oxidation reaction proceeds, a means for preventing the salt from being deposited in the reactor or a discharging means may be employed. As a specific method, means for dissolving and discharging a salt by providing an aqueous layer at the lower part of the reactor (Japanese Patent No. 2,726,293) and means for mechanically scraping the salt (US Pat. No. 5,100,560, JP-A-10-15566, Known methods can be employed, such as JP-A-11-253786, and means for preventing adhesion by ejecting a fluid from the reactor surface (JP-A-9-299966).
[0030]
Separation means for separating solids in the reaction fluid discharged from the reactor can be provided. In particular, since the inorganic salts are not dissolved but contained as a solid in the reaction fluid in a supercritical state, the reuse of the treated water is facilitated by separating the insolubilized inorganic substances. The solid matter separation means is not particularly limited, and includes a container having an inlet for introducing a reaction fluid from a reactor and an outlet for discharging a fluid from which solids have been removed, and a container provided in the container and included in the reaction fluid. And a means for removing and discharging the solid. In the steps of cooling and depressurization, means for gas-liquid separation or solid-liquid separation may be provided.
[0031]
Organic substances are decomposed by the hydrothermal oxidation reaction, and heat of reaction is generated. When a mixing reaction zone with a backflow is provided at the upper part of the reactor, the organic substance, the oxidizing agent, the contents of the reactor and the like are sufficiently mixed by the mixing action with the backflow, so that the temperature of the fluid rises. As a result, the supplied organic matter immediately starts a hydrothermal oxidation reaction, and a stable reaction is continued. The reaction fluid moves downward in the reactor, continuously reacts in the plug flow reaction zone, and is discharged from the outlet. The length: diameter ratio of the reactor is preferably from 1: 1 to 100: 1.
[0032]
The reaction fluid exiting the reactor is cooled as it is or after separating a solid, and then decompressed and subjected to gas-liquid separation. When a liquid is generated by cooling in the reactor, the liquid is separated together with the solid at the stage of leaving the reactor, and if necessary, further cooling, gas-liquid separation and solid-liquid separation can be performed. The finally generated water, gas, and solid are directly recovered for energy recovery, reused as a substance, or directly or additionally processed for disposal.
[0033]
In the present invention, until the steady state is reached, the pressure of the reaction system in the process in which the pressure fluctuation occurs is made lower than the pressure in the steady state, so that the hydrothermal oxidation reaction is started in the hydrothermal oxidation reaction step. Even if the temperature rises rapidly or the pressure rises, the design pressure of the reactor can be dealt with with a margin and is safe.
[0034]
【The invention's effect】
The hydrothermal oxidation reaction method of the present invention, at least a part of the preheating step, and at least a part of the process from the preheating step to the transition to the steady state in the hydrothermal oxidation reaction step, during the steady state of the hydrothermal oxidation reaction step Since the heating is performed at a pressure lower than the pressure of the hydrothermal oxidation reactor, it is possible to sufficiently cope with the pressure fluctuation at the time of starting the hydrothermal oxidation reaction apparatus, and therefore, the hydrothermal oxidation reaction can be performed safely and in a short time. You can start.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system diagram showing a hydrothermal oxidation reaction apparatus according to an embodiment for performing the hydrothermal oxidation reaction method of the present invention. In FIG. 1, 1 is a hydrothermal oxidation reactor, 2 is a reactor, 3 is a high-temperature fluid generator, 4 is an object tank, 5 is a water tank, 6 is a combustible substance tank, 7 is a pressure gauge, 8 is a control unit, 9 is a cooler, 10 is a gas-liquid separator.
[0036]
A supply device 12 is provided at an upper portion of the reactor 2, and a reactant supply passage 13 and a fluid supply passage 16 communicate with the supply device 12. The supply device 12 is configured so that the reactant supplied from the reactant supply passage 13 and the high-temperature and high-pressure fluid supplied from the fluid supply passage 16 can be mixed in the vicinity of an injection nozzle (not shown).
The high-temperature fluid generator 3 is connected to a fuel introduction path 14, an air introduction path 15, and a fluid supply path 16, and the fluid supply path 16 communicates with the supply device 12. The fuel introduction path 14 is provided with a high-pressure pump P1, and the air introduction path 15 is provided with an air compressor AC. The high-temperature fluid generation device 3 burns the fuel introduced from the fuel introduction passage 14 with air introduced from the air introduction passage 15 to generate a high-temperature and high-pressure fluid. It is configured to be supplied to the reactor 2 through the reactor.
[0037]
The details of the high-temperature fluid generator 3 are shown in FIG. Reference numeral 31 denotes a cylindrical pressure-resistant container, one end of which is closed and a fuel supply portion 32, the other end of which has a cone shape, and the end of which is open to constitute a high-temperature fluid discharge portion 33. A concentric cylindrical inner cylinder 34 is housed in the pressure-resistant container 31, and one end of the inner cylinder 34 is attached to the fuel supply unit 32, and the other end is open near the cone. The inner peripheral surface of the pressure-resistant container 31 and the outer peripheral surface of the inner cylinder 34 are kept at a constant distance, a heat insulating space 35 is formed, and a combustion space 36 is formed inside the inner cylinder 34. The heat insulation space 35 and the combustion space 36 communicate with the high temperature fluid discharge part 33.
[0038]
The fuel supply path 32 is connected to the fuel supply section 32 and communicates with the combustion space 36 so that the fuel and the oxidant can be supplied to the combustion space 36. . A high-pressure pump P1 is provided in the fuel introduction path 14, and an air compressor ACa is provided in the oxidant introduction path 15a. An ignition device 37 for igniting fuel is provided on the combustion space 36 side of the fuel supply unit 32. A glow plug or the like can be used as the ignition device 37. Further, the heat insulating fluid introduction path 15 b is connected to the fuel supply unit 32 and communicates with the heat insulating space 35. An air compressor ACb is provided in the adiabatic fluid introduction path 15b. The air compressors ACa and ACb constitute the air compressor AC of FIG. 1, and the oxidizing agent introduction passage 15a and the adiabatic fluid introduction passage 15b constitute the air introduction passage 15. A plurality of heat insulating fluid introduction paths 15b are provided in the circumferential direction.
[0039]
An article supply passage 18 communicates with the article supply passage 13 from the article tank 4 in FIG. The workpiece supply passage 18 is provided with a high-pressure pump P2.
A water supply path 19 communicates with the reactant supply path 13 from the water tank 5. The water supply path 19 is provided with a high-pressure pump P3.
A combustible material supply path 20 communicates with the reactant supply path 13 from the combustible substance tank 6. The combustible supply path 20 is provided with a high-pressure pump P4.
[0040]
In the reactor 2, a high-temperature and high-pressure fluid, an object to be treated, water, kerosene, and the like are mixed by a supply device 12 provided at an upper portion, and the mixed flow is supplied into the reactor 2 in a downward flow. . From the lower part of the reactor 2, a reaction fluid outlet passage 22 communicates with the cooler 9, and a system passage 23 from the cooler 9 communicates with the gas-liquid separator 10. A cooling water passage 24 is connected to the cooler 9.
[0041]
A gas discharge path 25 having a pressure control valve V1 is connected to an upper part of the gas-liquid separator 10. The pressure detected by the pressure gauge 7 is sent to the control device 8 as a pressure signal, and the control signal is sent from the control device 8 to the pressure control valve V1 to control the pressure in the reactor 2. Thereby, the pressure of the high-temperature and high-pressure fluid supplied to the reactor 2 can be controlled.
A liquid discharge path 26 having a liquid level control valve V2 for controlling the liquid level of the gas-liquid separator 10 is connected to a lower part of the gas-liquid separator 10. 27 is a liquid level gauge, 28 is a control device, which measures the liquid level with the liquid level meter 27, sends a measurement signal to the control device 28, and further sends a control signal from the control device 28 to the liquid level control valve V2. And the liquid level of the gas-liquid separator 10 is controlled.
[0042]
In order to perform the hydrothermal oxidation reaction with the apparatus of FIG. 1, when starting the operation of the hydrothermal oxidation reaction apparatus 1, first, as a preheating step, pressurized air pressurized by the air compressor ACb from the adiabatic fluid introduction passage 15b is heated to a high temperature. The pressurized air is sent to the fluid generator 3 and supplied to the reactor 2 from the high-temperature fluid discharge section 33 and the high-temperature and high-pressure fluid supply path 16 via the supply device 12 to pressurize the reactor 2. Thereafter, kerosene pressurized by the high-pressure pump P1 is introduced into the high-temperature fluid generation device 3 from the fuel introduction passage 14, and pressurized air pressurized by the air compressor ACb is introduced from the oxidant introduction passage 15a. The mixture is introduced into the combustion space 36 and ignited by the ignition device 37 to start combustion. The high-temperature and high-pressure fluid generated by the combustion is supplied to the reactor 2 from the high-temperature and high-pressure fluid supply path 16 through the high-temperature and high-pressure fluid supply path 16 through the supply device 12 to heat the reactor 2. When generating the high-temperature and high-pressure fluid, high-pressure air is introduced into the heat-insulating space 35 from the heat-insulating fluid introduction path 15b to prevent the temperature of the pressure-resistant container 31 constituting the high-temperature fluid generating device 3 from rising.
[0043]
In this manner, the reactor 2 is heated, and the pressure is detected by the pressure gauge 7, the pressure signal is sent to the control device 8, and the control signal is sent from the control device 8 to the pressure control valve V 1, and the pressure in the reaction system is reduced. By controlling the pressure, the pressure in the reactor 2 is adjusted to a lower pressure than in the steady state.
[0044]
At the stage when the temperature of the reactor 2 has risen to a temperature at which the hydrothermal oxidation reaction can be started by the above heating method, water 27 and kerosene 26 are supplied from the water tank 5 and the combustible substance tank 6 by the high-pressure pumps P3 and P4 to the reactor 2. And continue the preheating process. At this stage, the supply of the high-temperature and high-pressure fluid containing the oxidizing agent from the high-temperature fluid generator 3 is also performed in parallel. In the supply device 12, the high-temperature high-pressure fluid containing the oxidizing agent, water 27 and kerosene 26 are mixed, and the mixed flow is supplied to the reactor 2 in a downward flow.
[0045]
Since the inside of the reactor 2 is heated by the high-temperature and high-pressure fluid, the hydrothermal oxidation reaction of the kerosene 26 proceeds smoothly, and the reaction heat further heats the reactor 2. When the hydrothermal oxidation reaction has started to progress stably, the supply of fuel to the high-temperature fluid generator 3 is stopped. Even after the fuel introduction is stopped, the supply of pressurized air from the oxidizing agent introduction passage 15a or the adiabatic fluid introduction passage 15b is continuously performed, and the pressurized air is supplied to the reactor 2 from the fluid supply passage 16 to be subjected to hydrothermal oxidation. It is used as an oxidant necessary for the reaction.
[0046]
In this manner, the reactor 2 is heated, and the pressure is detected by the pressure gauge 7, the pressure signal is sent to the control device 8, and the control signal is sent from the control device 8 to the pressure control valve V 1, and the pressure in the reaction system is reduced. By controlling the pressure, the pressure in the reactor 2 is adjusted to a lower pressure than in the steady state.
[0047]
Under the condition that the reactor 2 reaches the steady-state reaction temperature and the pressure of the reactor 2 is lower than that in the steady state, the supply of the treatment object 28 is started, and the hydrothermal oxidation reaction step is started. The workpiece 28 in the workpiece tank 4 is sent from the workpiece supply path 18 to the supply device 12 through the workpiece supply path 13 by the high-pressure pump P3, and supplied from the supply apparatus 12 to the reactor 2.
In the supply device 12, the object to be treated 28, kerosene 26 and water 27 are mixed, the mixed flow is supplied to the reactor 2 in a downward flow, and a hydrothermal oxidation reaction is performed in a supercritical or subcritical state of water. In this case, kerosene 26 is supplied as auxiliary fuel. The oxidant necessary for the hydrothermal oxidation reaction is supplied by supplying pressurized air from the fluid supply path 16 via the supply device 12.
[0048]
When the treatment object 28 is supplied to the reactor 2 to start the hydrothermal oxidation reaction, a large temperature fluctuation occurs due to the type and amount of the organic substance in the treatment object 28, the presence or absence of bubbles, and the like. Pressure may occur, but the pressure at the start of the hydrothermal oxidation reaction is set low, so that even if the pressure in the reactor 2 rises sharply, it is possible to respond with a margin The reaction can be carried out.
After the reaction temperature of the hydrothermal oxidation reaction of the treatment object 28 is stabilized, the supply amounts of the kerosene 26 and the water 27 are adjusted to increase the pressure to a steady state pressure. Thereafter, by appropriately adjusting the supply amounts of the object to be treated, water, and the auxiliary fuel, the reaction conditions are led to the set value of the steady state, and the hydrothermal oxidation reaction is performed. Continue to do so.
[0049]
The reaction fluid of the reactor 2 is introduced into the cooler 9 from the reaction fluid extraction passage 22, cooled by cooling water supplied from the cooling water passage 24, and introduced into the gas-liquid separator 10 from the system passage 23 to separate gas and liquid. . The separated gas is reduced in pressure by the pressure control valve V1, and is discharged from the gas discharge path 25 as a processing gas. The separated liquid is depressurized and discharged through the liquid level control valve V2, and discharged from the liquid discharge path 26 as treated water.
[0050]
In FIG. 1, the heating by the high-temperature fluid generation device 3 and the heating by the hydrothermal oxidation reaction heat of the kerosene 26 are used in combination as the preheating step, but either one may be performed alone.
[0051]
【Example】
Next, examples of the present invention will be described.
[0052]
Example 1
A hydrothermal oxidation reaction treatment was performed using the apparatus shown in FIG. In the steady state, the pressure of the reactor 2 is set to 24 MPa, and the temperature is set to 630 ° C.
First, after the pressure of the reactor 2 is maintained at 21 MPa with the pressurized air introduced into the high-temperature fluid generator 3, the pressurized air and kerosene are introduced, and the ignition device 37 ignites and burns. Started and generated hot and high pressure air. This high-temperature and high-pressure air was supplied to the reactor 2 and preheated until the temperature inside the reactor 2 reached 350 ° C.
When kerosene 26 and water 27 are supplied into the reactor 2 in this state, a hydrothermal oxidation reaction is started in the reactor 2 and the temperature rises, and the pressure in the reactor 2 is reduced to about 2 MPa for a short time. Rose.
[0053]
The preheating is continued, the pressure of the reactor 2 is maintained at 21 MPa by the pressure control valve V1, and when the temperature in the reactor 2 reaches 630 ° C., the object (liquid non-water-soluble organic substance) 28 is treated. Supply started. Immediately after the start of the supply of the article to be treated 28, the temperature in the reactor 2 fluctuated by about ± 30 ° C., and the pressure also fluctuated by about 1 MPa, but it was about the pressure in a steady state. Thereafter, the pressure was set to 24 MPa, and the hydrothermal oxidation reaction of the processing object 28 was continued.
[0054]
Comparative Example 1
Preheating was performed under the same conditions as in Example 1 except that the pressure at startup was set to 24 MPa. Under these conditions, the object 28 was supplied to the reactor 2 to start the hydrothermal oxidation reaction. As a result, the pressure in the reactor 2 increased by about 2 MPa for a short time, and approached the design pressure of 27 MPa.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a hydrothermal oxidation reaction apparatus according to an embodiment for performing a hydrothermal oxidation reaction method of the present invention.
FIG. 2 is a vertical sectional view of the high-temperature fluid generation device in FIG.
[Explanation of symbols]
1 Hydrothermal oxidation reactor
2 reactor
3 High temperature fluid generator
4 Treatment object tank
5 aquarium
6 Combustible tank
7 Pressure gauge
8, 28 control device
9 Cooler
10 Gas-liquid separator
12 Supply device
13 Reactant supply path
14 Fuel introduction path
15 Air introduction path
15a Oxidizer introduction path
15b Insulating fluid introduction path
16 Fluid supply path
18 Workpiece supply path
19 Water supply channel
20 Combustible material supply path
22 Reaction fluid outlet
23 routes
24 cooling water channel
25 Gas discharge path
26 Liquid discharge path
27 Liquid level gauge
31 pressure vessel
32 Fuel supply unit
33 High-temperature fluid discharge section
34 inner cylinder
35 Insulated space
36 Combustion space
37 Ignition device

Claims (3)

Before performing the hydrothermal oxidation reaction of the object to be treated, a preheating step of heating the reactor in advance,
A hydrothermal oxidation reaction method comprising supplying a treatment object to a reactor and performing a hydrothermal oxidation reaction in a supercritical or subcritical state of water,
At least a part of the preheating step, and at least a part of the process from the preheating step to a transition to the steady state in the hydrothermal oxidation reaction step, the pressure of the reaction system is increased during the steady state of the hydrothermal oxidation reaction step. A hydrothermal oxidation method in which heating is performed at a pressure lower than the pressure. The preheating step is a method of supplying a high-temperature and high-pressure fluid to the reactor, a method of supplying a combustible organic substance to the reactor, and performing a hydrothermal oxidation reaction in the presence of water and an oxidizing agent, or a combination of these methods. The hydrothermal oxidation reaction method according to claim 1. At least a part of the preheating step, and at least a part of the process from the preheating step to the transition to the steady state in the hydrothermal oxidation reaction step, the pressure of the high-pressure fluid flowing part of the reaction system is changed to the steady state of the hydrothermal oxidation reaction step. 3. The hydrothermal oxidation reaction method according to claim 1, wherein the hydrothermal oxidation reaction is performed in a state controlled by a pressure reducing means so that the pressure is lower than the pressure at the time.

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