JP2001038190A - Hydrothermal reaction method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct an efficient hydrothermal reaction by easily removing a gas without discharging the gas to the outside when the gas is generated in a material to be reacted, and the supply of a liq. by a pump is disturbed. SOLUTION: A material to be reacted and an oxidizing agent are passed respectively through supply lines 2 and 12 from storage tanks 1 and 11, supplied by pumps 3 and 13, preheated by preheaters 7 and 17 and supplied to a reactor 8 to conduct a hydrothermal reaction in a supercritical or subcritical state. When a gas is generated in the lines 2 and 12 to disturb the liq. supply by the pumps 3 and 13, three-way valves 4 and 14 are switched to discharge the gas into the tanks 1 and 11 from discharge lines 5 and 15, and then the three- way valves 4 and 14 are switched to resume the liq. supply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for hydrothermal reaction for decomposing waste, producing energy or producing chemical substances, and more particularly to performing a hydrothermal reaction under supercritical or subcritical conditions of water. The present invention relates to a suitable hydrothermal reaction method and apparatus.

[0002] In a supercritical or subcritical state of water, a reactant is oxidized or hydrolyzed to decompose waste,
Hydrothermal treatments that produce energy and produce chemicals have been studied and used for over 30 years. In particular, in recent years, water that causes an oxidation reaction by reacting an oxidizing agent with a reactant containing organic matter in a supercritical or subcritical state of water, and almost completely decomposes the organic matter in the reactant in a short time. Heat treatment has attracted attention.

[0003] When the hydrothermal treatment is performed to oxidatively decompose the organic matter in the reactant, the reactant, the oxidizing agent, and water are pressurized.
The mixture is heated, supplied to the reaction vessel, and reacted. In this case, when the reactant contains an appropriate amount of water in advance, it is not necessary to supply water. As a result of the reaction, the organic matter is oxidatively decomposed to obtain a reaction product containing a high-temperature and high-pressure fluid composed of water and carbon dioxide and a solid such as ash and salts in a dry or slurry state. Among the reaction products, solids are separated by a solid separation device because they become obstacles for a pressure reducing valve, an energy recovery facility, and the like at the subsequent stage. The fluid from which the solids have been separated is recovered for energy, or cooled and decompressed, and separated into gas and liquid components.

[0004] In such a hydrothermal reaction process, a high-pressure pump is used to send an organic waste liquid to be decomposed or a solution such as aqueous hydrogen peroxide as an oxidizing agent. In this case, a gas such as oxygen may be generated in the solution due to the self-decomposition of hydrogen peroxide or the fermentation of organic substances in the organic waste liquid. If the high-pressure pump for sending these solutions contains these gases inside, it may not be possible to send them to the high-pressure reactor.

In such a case, the hydrothermal reaction does not proceed, so that the processing is interrupted. However, in order to stop the apparatus in the high-temperature and high-pressure state, it is necessary to wait until the temperature of the apparatus has dropped to near normal temperature. And processing efficiency is poor. Also, it is difficult to extract gas from these supply paths because these supply paths are connected to a high-temperature and high-pressure reactor, and the material to be treated and the oxidizing agent may contain harmful or dangerous substances. is there.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for discharging a gas to the environment without stopping a reaction when a gas is generated in a reactant and it becomes difficult to feed a solution by a pump. It is an object of the present invention to provide a hydrothermal reaction method and apparatus capable of efficiently performing a reaction by easily removing a gas without performing the reaction.

[0007]

The present invention is the following hydrothermal reaction method and apparatus. (1) A reactant supplying step of supplying a reactant from a reactant storage tank to a reactor by a reactant pump, and a reaction step of performing a hydrothermal reaction in a supercritical or subcritical state of water in the reactor. In the reactant supply step, when gas is contained in the reactant, the gas is discharged by switching from the discharge side of the reactant pump to the treatment tank, and the supply of the substance is performed after the gas is discharged. Hydrothermal reaction method to be restarted. (2) An oxidizing agent supply step of supplying the oxidizing agent from the oxidizing agent storage tank to the reactor by an oxidizing agent pump. The method according to (1), wherein the gas is discharged by switching the flow path to the agent storage tank, and the supply of the oxidant is restarted after the gas is discharged. (3) A reactor that performs a hydrothermal reaction in a supercritical or subcritical state of water, a reactant storage tank that stores the reactant, and an oxide that supplies the reactant from the reactant storage tank to the reactor A reactant supply passage including a pump, a gas discharge passage for discharging gas from a discharge side of the oxide pump to the reactant storage tank, and a reactant supply passage in which gas is contained in the reactant supply passage. ,
Switching means for switching a flow path on the discharge side of the oxidized pump from a reactant supply path to a gas discharge path. (4) An oxidizing agent storage tank for storing the oxidizing agent, an oxidizing agent supply path including an oxidizing agent pump for supplying the oxidizing agent from the oxidizing agent storage to the reactor, and discharging gas from the discharge side of the oxidizing agent pump to the oxidizing agent storage tank And a switching means for switching the flow path on the discharge side of the oxidant pump from the oxidant supply path to the gas discharge path when the oxidant contains gas in the oxidant supply path. 3) The apparatus according to the above.

In the present invention, the term "hydrothermal reaction" means that the reactant is oxidized in the presence of high-temperature, high-pressure water in a supercritical or subcritical state. Here, the supercritical state is 37
The temperature is 4 ° C. or higher and 22 MPa or higher. The subcritical state is, for example, 374 ° C. or more, 2.5 MPa or more and 22MPa.
a or less than 374 ° C., 22 MPa or more,
Alternatively, it refers to a high-temperature and high-pressure state close to the critical point even at 374 ° C. or less and less than 22 MPa.

The reactant contains a substance to be subjected to a hydrothermal reaction such as an oxidation reaction or a hydrolysis reaction in a supercritical or subcritical state of water. Specific examples of the reactant include organic matter in waste liquid discharged from factories and the like, and excess sludge from activated sludge. Such a reactant is introduced into the reactor in a state of being mixed with the oxidizing agent, and undergoes a hydrothermal reaction.
Examples of the oxidizing agent include a peroxide such as hydrogen peroxide and an oxygen-containing gas such as air.

When the reactants contain an organic substance and an oxidizing agent, these are supplied separately or mixed to a reactor to carry out a hydrothermal reaction. In such a hydrothermal reaction system, water is present in addition to the reactant, and if necessary, a catalyst and a neutralizing agent are added. These may be mixed with the reactant or supplied separately to the reactor. can do.

The reactor used in the present invention is formed of a heat-resistant and pressure-resistant vessel so as to carry out a hydrothermal reaction in a supercritical or subcritical state, and has heating and pressurizing means. When a hydrothermal reaction is performed in a supercritical or subcritical state in such a reactor, the organic substance to be reacted is oxidized by an oxidizing agent, or is decomposed into water and carbon dioxide by hydrolysis to be finally decomposed into water and carbon dioxide. , Energy is recovered. The reaction product is cooled and decompressed and separated into a gas component and a liquid component.

In order to supply a reactant and an oxidizing agent to such a reactor that performs a hydrothermal reaction in a supercritical or subcritical state, it is necessary to use a high-pressure pump from each storage tank. However, decomposition of organic substances contained in the object to be treated,
When gas is generated due to fermentation, decomposition of the oxidizing agent, or the like, these gases flow into the pump from the supply path, cause the pump to idle, and supply of the reactants and the oxidizing agent becomes impossible.

Although it is generally difficult to extract such a gas as described above, simply by switching the flow path from the discharge side of the pump to the storage tank side, the gas is discharged by the pumping action of the pump. I found out. That is, in this case, the pressure from the reactor is shut off by shutting off the flow channel to the reactor by switching the channel. Then, the discharge side of the pump is connected to each storage tank, whereby the pressure on the discharge side of the pump is released, and the gas in the flow path is discharged to the storage tank by the pumping action of the pump.

After the gas is discharged, the flow path on the discharge side of the pump is switched to the reactor side again to restart the hydrothermal reaction. Since the gas discharge is completed in a short time, there is no problem if the hydrothermal reaction in the reactor is continued during that time. In addition, the gas is discharged to the reactant storage tank or the oxidant storage tank and is not discharged to the outside of the system, and therefore does not pollute the environment.

The reactant supply passage and the oxidant supply passage communicating with the reactor from the reactant storage tank and the oxidant storage tank respectively have high pressure reactant so that the reactant and the oxidant can be supplied to the high pressure reactor. It is preferable to provide a flow path having a substance pump and an oxidant pump, and to provide a check valve so that back pressure is not applied from the reactor.

The gas discharge path is a branch flow path from the discharge side of the reactant pump and the oxidant pump of each supply path to the reactant storage tank and the oxidant storage tank. The switching means of these flow paths is configured by providing a three-way valve at a branch point of the flow path, or by providing a two-way valve in each flow path. In the latter case, the two-way valve for the reactant supply path and the oxidant supply path can also serve as a check valve.

In order to detect the generation and discharge of gas, a pressure gauge, a flow meter, or a pump is provided with a detecting means for checking the discharge amount or the like in each flow path to detect a decrease or an increase in pressure or flow rate. Thus, the flow path is switched, and the gas can be discharged by the liquid sending action of the pump. These flow paths may be a single flow path when the reactant and the oxidizing agent are supplied in a mixed state.

[0018]

According to the present invention, when a gas is contained in the reactant supply path or the oxidant supply path, the gas can be discharged to the reactant storage tank or the oxidant storage tank simply by switching the flow path. The gas can be easily removed and the hydrothermal reaction can be efficiently performed without stopping the reaction and without discharging the gas to the environment.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of the hydrothermal reactor of the embodiment.

In FIG. 1, reference numeral 1 denotes a reactant storage tank, which is connected to a reactor 8 via a reactant supply path 2 via a reactant pump 3, a three-way valve 4, a check valve 6, and a preheater 7. are doing. The reactor 8 is formed of a heat-resistant, pressure-resistant container so as to perform a hydrothermal reaction in a supercritical or subcritical state, and includes a heater 8a,
8b are provided adjacent to each other. Cooler 9 from reactor 8
A reactant discharge passage 18 having a pressure control valve 10 communicates with the outside of the system.

Reference numeral 11 denotes an oxidizing agent storage tank, which includes an oxidizing agent pump 13, a three-way valve 14, a check valve 16
And the reactor 8 via a preheater 17. Gas discharge paths 5 and 15 are connected to the reactant storage tank 1 and the oxidant storage tank 11 from three-way valves 4 and 14 provided on the discharge sides of the pumps 3 and 13, respectively. The control devices 3a and 13a of the pumps 3 and 13 detect the discharge amounts of the pumps 3 and 13, and are connected to switch the three-way valves 4 and 14 according to the change of the discharge amounts.

The hydrothermal reaction method using the above apparatus is performed as follows. First, the reactant storage tank 1 and the oxidant storage tank 1
The reactant and the oxidant are supplied from the reactant pump 3 and the oxidant pump 13 through the reactant supply passage 2 and the oxidant supply passage 12, respectively. , 16 and preheated by the preheaters 7 and 17 and supplied to the reactor 8.

In the reactor 8, heating is performed by the heaters 8a and 8b, and the pressure is adjusted by the pressure adjusting valve 9 to maintain the supercritical or subcritical state, thereby performing the hydrothermal reaction. By the reaction, organic substances and the like in the reactant are oxidized by the oxidizing agent. The reactant is taken out from the reactant take-out passage 18, cooled by the cooler 9, passed through the pressure regulating valve 10, and discharged under reduced pressure.

The reactant supply passage 2 or the oxidant supply passage 12
When the gas is contained in the pump 3 and the liquid cannot be sent by the pumps 3 and 13, the control devices 3 a and 13 a detect a decrease in the pump discharge amount, and connect the three-way valves 4 and 14 to the gas discharge passages 5 and 1.
Switch to 5 side. As a result, the flow path on the side of the reactor 8 is shut off, and the gas in the reactant supply path 2 and the oxidant supply path 12 is supplied by the pumps 3 and 13 to the gas discharge paths 5 and 1.
5 is discharged to the reactant storage tank 1 and the oxidant storage tank 11.

In this case, since the reactant storage tank 1 and the oxidant storage tank 11 are maintained substantially at atmospheric pressure, the pumps 3 and 13
Since no load is applied to the gas, gas can be discharged simply by switching the flow path. Pump 3 by discharging gas,
When the discharge amount of 13 increases, the control devices 3a and 13a detect this and switch the three-way valves 4 and 14. Thus, the supply of the reactant and the oxidant to the reactor 8 is restarted.

In the above example, since the flow path is switched by switching the three-way valves 4 and 14, the check valves 6 and 16 may be omitted, but it is preferable to provide them for safety. In addition, two-way valves may be provided in the gas discharge paths 5, 15 instead of the three-way valves 4, 14 as switching means, and the flow paths may be switched by opening and closing the two-way valves. In this case, the check valves 6 and 16 are necessary, but another three-way valve may be used.

According to the above-described hydrothermal reaction method and apparatus,
When a gas is contained in the reactant supply path or the oxidant supply path, the gas can be discharged to the reactant storage tank or the oxidant storage tank simply by switching the flow path, without stopping the reaction, and without removing the gas. The gas can be easily removed and the hydrothermal reaction can be efficiently performed without discharging to the environment.

[Brief description of the drawings]

FIG. 1 is a system diagram of a hydrothermal reactor of an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactant storage tank 2 Reactant supply path 3 Reactant pump 3a, 13a Control device 4, 14 Three-way valve 5, 15 Gas discharge path 6, 16 Check valve 7, 17 Preheater 8 Reactor 8a, 8b Heating Refrigerator 9 Cooler 10 Pressure control valve 11 Oxidant storage tank 12 Oxidant supply path 13 Oxidant pump

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[Procedure amendment]

[Submission date] November 17, 2000 (200.11.
17)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art In a supercritical or subcritical state of water, a hydrothermal treatment for oxidizing or hydrolyzing a reactant to decompose waste, generate energy, or produce a chemical substance is performed. It has been studied and used for over 30 years. In recent years, in particular, a reactant containing an organic substance in a supercritical or subcritical state of water causes an oxidation reaction by reacting the oxidizing agent, and the organic substance in the reactant is reduced in a short time.
Attention has been paid to hydrothermal treatment that almost completely decomposes.

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Claims (4)

[Claims] 1. A reactant supply step of supplying a reactant from a reactant storage tank to a reactor by a reactant pump, and a reaction step of performing a hydrothermal reaction in a supercritical or subcritical state of water in the reactor. In the reactant supply step, when gas is contained in the reactant, the gas is discharged by switching from the discharge side of the reactant pump to the treatment tank and discharging the gas after discharging the gas. A hydrothermal reaction method in which the supply is restarted. 2. An oxidizing agent supply step of supplying an oxidizing agent from an oxidizing agent storage tank to a reactor by an oxidizing agent pump, wherein when a gas is contained in the oxidizing agent in the oxidizing agent supplying step, a discharge side of the oxidizing agent pump is provided. 2. The method according to claim 1, wherein the gas is discharged by switching the flow path from the gas to the oxidant storage tank, and the supply of the oxidant is resumed after the gas is discharged. 3. A reactor for performing a hydrothermal reaction in a supercritical or subcritical state of water, a reactant storage tank for storing a reactant, and a reactant for supplying a reactant from the reactant storage tank to the reactor. A reactant supply path including an oxide pump; a gas discharge path for discharging gas from a discharge side of the oxide pump to a reactant storage tank; and a reactant supply gas in the reactant supply path. Switching means for switching a flow path on the discharge side of the oxidized pump from the reactant supply path to the gas discharge path. 4. An oxidizing agent storage tank for storing an oxidizing agent, an oxidizing agent supply path including an oxidizing agent pump for supplying an oxidizing agent from the oxidizing agent storage tank to the reactor, and an oxidizing agent storage tank for discharging gas from a discharge side of the oxidizing agent pump. And a switching means for switching the flow path on the discharge side of the oxidant pump from the oxidant supply path to the gas discharge path when the oxidant contains gas in the oxidant supply path. An apparatus according to claim 3.