JP3686778B2 - Operation method of supercritical water reactor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for operating a supercritical water reactor. More specifically, the supercritical water reactor is operated, and a plurality of kinds of liquids having different oxidation heat generation per unit volume are simultaneously introduced into the reactor. In addition, the present invention relates to a method for smoothly starting a supercritical water reactor and performing a stable operation when performing a supercritical water reaction in the presence of supercritical water.
[0002]
[Prior art]
With increasing awareness of environmental issues, attention has been paid to attempts to decompose and detoxify environmental pollutants using supercritical water reactions with high oxidation and decomposition capabilities of organic matter. That is, due to the supercritical water reaction utilizing the high reactivity of supercritical water, harmful and hardly decomposable organic substances that have been difficult to be decomposed by the prior art, such as PCB (polychlorinated biphenyl), dioxin, and organic chlorine It is an attempt to decompose solvents and convert them into harmless products such as carbon dioxide, nitrogen, water and inorganic salts.
[0003]
A supercritical water reactor is a device that decomposes organic substances using the high reactivity of supercritical water. For example, it decomposes harmful organic substances that are difficult to decompose and converts them into harmless carbon dioxide and water. In order to decompose difficult-to-decompose high-molecular compounds and convert them into useful low-molecular compounds, their practical application is currently being actively studied.
Supercritical water refers to water in a supercritical state, that is, water in a state exceeding the critical point of water, and more specifically, at a temperature of 374.1 ° C. or higher and a pressure of 22.04 MPa or higher. Says water in a certain state. Supercritical water has a high ability to dissolve organic substances, and can completely dissolve non-polar substances that are abundant in organic compounds. Conversely, the ability to dissolve inorganic substances such as metals and salts is extremely low. Supercritical water can be mixed with a gas such as oxygen or nitrogen at an arbitrary ratio to form a single phase.
[0004]
Here, the basic configuration of the supercritical water reactor will be described with reference to FIG. FIG. 3 is a flow sheet showing the basic configuration of the supercritical water reactor.
The supercritical water reaction apparatus 10 is an apparatus for treating a liquid to be treated containing harmful organic substances by supercritical water reaction in the presence of supercritical water, and performs a supercritical water reaction as shown in FIG. As a reactor, a vertical pressure-resistant sealed reactor 12 is provided, and a cooling liquid 16 for cooling the processing liquid and a pressure in the reactor 12 are sequentially controlled in a processing liquid pipe 14 for allowing the processing liquid to flow out from the reactor 12. A pressure control valve 18 and a gas-liquid separator 20 for separating the processing liquid into gas and liquid are provided.
The vertical reaction vessel is usually suitable for processing a liquid to be processed having a low solid content, and a pipe-shaped tube when processing a liquid to be processed having a high solid content. In many cases, a reactor is used.
[0005]
The supercritical water reactor 10 is provided with a liquid pump 24 to be processed and an air compressor 28 as a supply system for supplying a reactant to be supplied to the supercritical water reaction to the reactor 12, and receives a liquid to be processed containing organic matter. Air is fed into the reactor 12 together with the liquid to be treated together with the liquid to be treated through the air pipe 26 and the liquid pipe 22 to be treated.
[0006]
Further, the supercritical water reaction apparatus 10 supplies an auxiliary fuel pipe (see FIG. 5) for supplying auxiliary fuel to the reactor 12 as a heat energy source necessary for maintaining the supercritical water reaction in the reactor 12 as necessary. And an alkaline agent feeding pipe (not shown) for feeding an alkaline agent that neutralizes chlorine generated from organic substances in the treatment liquid by supercritical water reaction in the reactor 12 to the reactor 12. The processing liquid pipe 22 is merged.
[0007]
In addition, a heat exchanger (not shown) that heat-recovers the process liquid by heat-exchanging the process liquid and the process liquid and raising the temperature of the process liquid to recover the heat is disposed upstream of the cooler 16. 14 or a preheater for preheating the liquid to be treated may be provided in the liquid pipe 22 to be treated upstream of the reactor 12. Further, a supercritical water replenishment water pipe may be connected to the liquid pipe 22 to be treated.
Furthermore, a subcritical water region may be provided in the lower part of the reactor 12, and a mechanism may be provided for causing the inorganic salts generated in the reactor 12 to settle and remove in the subcritical water region.
[0008]
[Problems to be solved by the invention]
By the way, excellent points and effects of organic matter treatment by supercritical water reaction are being evaluated, and for example, a supercritical water reactor is installed at the source of the liquid to be treated, and the calorific values per unit volume are different from each other. A plurality of liquids to be treated containing the organic substances are simultaneously treated in a supercritical water reactor.
[0009]
For example, as shown in FIG. 2, the two types of supercritical water reactor 30 for processing liquid to be treated, the two treated liquid pump 24A, B are provided, the liquid to be treated through a treated liquid pipe 22 A pump 24A and the reactor 12 are connected to each other, and a liquid pipe 22B to be processed connected to the liquid pipe 22 to be processed is provided, which reacts with the liquid pump 2 4 B to be processed through the liquid pipe 22B and the liquid pipe 22 to be processed. The device 12 is connected.
Then, the liquid to be treated pump 24A and the liquid to be treated pump 24B, often simultaneously process the liquid to be treated A and the liquid to be treated B.
[0010]
However, in order to perform the supercritical water treatment of the liquid to be processed A and the liquid to be processed B, the liquid to be processed A and the liquid to be processed B are sent to the reactor when the supercritical water reactor is started up and during normal operation. However, there has been a problem that the temperature of the reactor fluctuates, in particular, the temperature of the reactor rises and it is difficult to carry out the treatment stably.
[0011]
Therefore, an object of the present invention is to smoothly start a supercritical water reactor when a plurality of types of liquids to be treated with different calorific values per unit volume are treated, particularly at the time of starting, and stably It is to provide a way to drive.
[0012]
[Means for Solving the Problems]
The present inventor sends a plurality of types of liquids containing different kinds of organic substances to the reactor, such as the liquids A and B to be processed as described above, and starts and operates the supercritical water reactor. At the same time, the cause of the rapid increase in the temperature of the reactor and the fluctuation of the pressure condition was investigated, and the following was found.
Normally, when the liquid to be treated is fed into the supercritical water reactor, the concentration of organic matter in the liquid to be treated, more specifically, the amount of oxidation heat generated by the organic matter per unit volume of the liquid to be treated is substantially constant. The liquid to be processed A and the liquid to be processed B are mixed and adjusted and sent to the reactor.
[0013]
By the way, for example, a treatment liquid B having a high organic substance concentration, that is, a treatment liquid B having a high oxidation calorific value per unit volume is fed, and then a treatment liquid A having a low organic substance concentration, that is, an oxidation calorific value per unit volume. When the liquid A to be processed is fed into the reactor, the apparent flow rate of the liquid A to be processed is added to the liquid B to be processed in the pipe from the mixing section to the reactor. A large amount of the processing liquid B flows into the reactor.
As a result, it was found that the calorific value per unit time increases in the reactor, and the temperature of the reactor rises.
[0014]
Therefore, a plurality of types of processing liquids containing different kinds of organic substances as described above at different concentrations, that is, a plurality of types of processing liquids having different oxidation heat generation amounts per unit volume, for example, the first processing liquid and the second processing liquid. When starting the supercritical water reactor for treating the liquid to be treated, first, the first liquid to be treated having a low oxidation calorific value per unit volume is sent to the reactor to be in a steady state, and then The present invention has been conceived to avoid the above-mentioned problems by sending a second liquid to be treated having a high oxidation calorific value per unit volume in addition to the liquid to be treated 1. It came to complete the method.
[0015]
In addition, during operation of the supercritical water reactor, in order to avoid occurrence of the above-described problem when the second liquid to be treated is fed into the reactor in addition to the first liquid to be treated, The oxidation heat generation amount per unit volume of the second treatment liquid is considered to be higher than the oxidation heat generation amount per unit volume of the first treatment liquid, and the method of the present invention is completed after the research. It reached.
[0016]
In order to achieve the above object, based on the above-mentioned knowledge, the operation method of the supercritical water reactor according to the present invention simultaneously uses a plurality of types of liquids to be treated with different oxidation calorific values per unit volume in the reactor. It is a method of operating a supercritical water reactor that introduces and performs a supercritical water reaction in the presence of supercritical water, and when starting the supercritical water reactor,
A first step of introducing air to increase the pressure in the reactor to a predetermined pressure;
A second step of flowing supercritical water into the reactor while continuing to feed air, and raising the temperature in the reactor to a first predetermined temperature;
A third step of introducing the first liquid to be treated into the reactor and starting the oxidation reaction while continuing the inflow of supercritical water;
A fourth step of supplying, in addition to the first liquid to be treated, a second liquid to be treated whose oxidation heat generation amount per unit volume is higher than that of the first liquid to be treated;
And a fifth step of stopping the inflow of supercritical water when the temperature of the reactor reaches the second predetermined temperature.
[0017]
In the method of the present invention, the first predetermined temperature is usually about 390 ° C. The second predetermined temperature is a temperature condition for the supercritical water reaction and is in the range of 500 ° C to 550 ° C.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described specifically and in detail with reference to FIG. 1 showing an embodiment.
Embodiment 1
The present embodiment is an example of an embodiment in which the operation method of the supercritical water reactor according to the present invention is applied to the startup of the supercritical water reactor 30.
In this embodiment, first, the air compressor 28 is started, high-pressure air is fed into the reactor 12, and the pressure in the reactor 12 is increased to a predetermined pressure.
Next, supercritical water is introduced through the supercritical water line 40 while continuing the high-pressure air feeding, and the temperature in the reactor 12 is raised to a predetermined temperature, for example, 390 ° C.
The supercritical water line 40 is provided with a heater 41 such as a heater or a heat exchanger, and the water is heated by the heater 41 to obtain supercritical water.
While continuing the inflow of supercritical water, the liquid pump 24A to be treated is started, and the liquid A to be treated having a low oxidation calorific value per unit volume of the liquid to be treated is introduced into the reactor 12, and the oxidation reaction To start.
[0019]
Next, in addition to the liquid A to be processed, the liquid pump 24B to be processed is started to supply the liquid B to be processed whose oxidation heat generation amount per unit volume is higher than that of the liquid A to be processed.
When the temperature of the reactor 12 rises, the amount of inflow of supercritical water is gradually reduced, and when the temperature of the reactor 12 reaches a predetermined temperature in the range of 500 ° C. to 550 ° C., the inflow of supercritical water And the supercritical water reaction is continued stably.
[0020]
In the present embodiment example, the oxidation heat generation amount per unit volume of the liquid to be processed A staying in the liquid tube 22 to be processed is lower than the oxidation heat generation amount per unit volume of the liquid B to be processed. The liquid to be treated having a high oxidation calorific value per unit volume that is retained in the feed pipe is pushed out into the liquid to be treated having a low oxidation calorific value per unit volume that is fed at a high flow rate. There will be no sudden rise in temperature.
[0022]
【The invention's effect】
According to the method of the present invention, in the operation of a supercritical water reactor that treats a plurality of types of liquids to be treated with different amounts of oxidation heat generated per unit volume, first, the amount of oxidation heat generated per unit volume is low when starting up. The first liquid to be treated is sent to the reactor to be in a steady state, and then the second liquid to be treated has a higher oxidation heat generation amount per unit volume than the first liquid to be treated in addition to the first liquid to be treated. Send in. Further, in the case of switching or additional feeding of the liquid to be treated, the first liquid to be treated is first fed, and then the second calorific value of oxidation per unit volume is higher than that of the first liquid to be treated. Feed the liquid to be processed.
Thus, as in the past, the liquid to be treated having a high oxidation calorific value per unit volume, which is retained in the feed pipe in the reactor, has a low oxidation calorific value per unit volume fed at a high flow rate. Since it is not pushed out by the treatment liquid and flows into the reactor in a large amount, stable temperature control can be performed without causing a rapid temperature rise in the reactor.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing the basic configuration of a supercritical water reactor.
FIG. 2 is a flow sheet showing the configuration of a conventional supercritical water reactor for treating two types of liquids to be treated.
3 is a full Roshito showing the configuration of a conventional supercritical water reactor for processing one type of liquid to be treated.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Supercritical water reactor 12 Reactor 14 Process liquid pipe 16 Cooler 18 Pressure control valve 20 Gas-liquid separator 22 Processed liquid pipe 22B Processed liquid pipe 24 Processed liquid pump 24A, B Processed liquid pump 26 Air supply Inlet pipe 28 Air compressor 30 Supercritical water reactor 40 for treating two kinds of liquids to be treated Supercritical water line 41 Heater

Claims (1)

A supercritical water reactor operating method in which multiple types of liquids with different oxidation heat generation per unit volume are introduced into the reactor at the same time and supercritical water reaction is performed in the presence of supercritical water. When starting the water reactor,
A first step of introducing air to increase the pressure in the reactor to a predetermined pressure;
A second step of flowing supercritical water into the reactor while continuing to feed air, and raising the temperature in the reactor to a first predetermined temperature;
A third step of introducing the first liquid to be treated into the reactor while continuing the inflow of supercritical water to start the oxidation reaction;
A fourth step of supplying, in addition to the first liquid to be treated, a second liquid to be treated whose oxidation heat generation amount per unit volume is higher than that of the first liquid to be treated;
And a fifth step of stopping the inflow of supercritical water when the temperature of the reactor reaches a second predetermined temperature.

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