JPH11173971A - Method and apparatus for detecting corrosion of high-pressure reaction vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method and an apparatus in which the corrosion state of a high-pressure reaction vessel is detected safely and surely by monitoring a change in a fluid for corrosion detection between the outer face of the reaction vessel and the inner face of a pressure-resistant vessel. SOLUTION: In order to detect the corrosion of a reaction vessel 1a, air as a fluid for corrosion detection is introduced into a pressure-resistant vessel 2 by a detecting- fluid supply line 6 via a flow control valve 10m a part of the fluid for corrosion detection is supplied to an analyzer 11 via a corrosion detecting fluid takeout line 8 and a flow control valve 9, and the concentration of O2 , CO2 and CO in the fluid for corrosion detection is monitored by the analyzer 11. When a pinhole is generated in the reaction vessel 1a, a fluid, to be treated, inside the reaction vessel 1a is leaked, the concentration of oxygen is lowered, and the concentration of carbon dioxide is raised. Consequently, when the composition of the fluid for corrosion detection is analyzed by the analyzer 11 so as to ne monitored, the generation of the pinhole is detected. In addition, as measures against the fracture of the reaction vessel 1a, a safety valve 12 is attached to the pressure-resistant vessel 2 so as to prevent a pressure inside the pressure-resistant vessel 2 from being raised suddenly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting corrosion of a high-pressure reactor.

[0002]

2. Description of the Related Art As a method for completely oxidatively decomposing a flame-retardant organic compound, a method of oxidatively decomposing an organic compound in supercritical water is known (Japanese Patent Publication No. 38532/1993, U.S. Pat. No. 4,113,446; No. 4,338,199, U.S. Pat. No. 4,543,190). Supercritical hydroxylation decomposition method
It is possible to completely oxidatively decompose flame-retardant organic substances in a short time, and the organic substances are decomposed into carbon dioxide and water. In order to bring water to a supercritical state, a temperature of 374 ° C. or more and a pressure of 22 MPa
Therefore, the pressure resistance of the reaction vessel is required regardless of the tube type or the vessel type.

However, when the organic matter to be treated contains halogen atoms and sulfur atoms, oxidative decomposition in supercritical water generates acidic ions such as chloride ions and sulfate ions, and the pH of the treatment fluid in the reactor increases. As a result, the reaction vessel corrodes. For this reason, a reaction vessel for supercritically hydrolyzing and decomposing an organic substance containing a halogen atom or a sulfur atom needs to have high pressure resistance and high corrosion resistance.

[0004] Even if the reaction vessel is made of a corrosion-resistant material,
It is unavoidable that the reaction vessel is gradually corroded. If a pinhole is generated in the reaction vessel, a high-pressure fluid rapidly flows out of the pinhole, and in some cases, the reaction vessel is destroyed, which is extremely dangerous.

[0005] As a method of monitoring the corrosion state of the reaction vessel, the concentration of an element used as a part of the material of the reaction vessel in the processing fluid discharged from the reaction vessel is measured.
There is a method to estimate the corrosion state.

[0006]

However, it is difficult to detect a local corrosion such as a pinhole by the method of estimating the corrosion state by measuring the concentration of the element in the processing fluid as described above. . Therefore, the only way to know the actual state of corrosion is to stop the apparatus and perform a nondestructive inspection of the reaction vessel, or to visually confirm that high-pressure fluid is leaking due to corrosion during operation. This visual method is particularly dangerous when the high pressure fluid is a harmful substance.

An object of the present invention is to provide a method and an apparatus for detecting a corrosion state of a high-pressure reaction vessel safely and reliably.

[0008]

According to the first aspect of the present invention, there is provided a reaction apparatus having a structure in which a reaction vessel is disposed in a pressure-resistant vessel, wherein a high-pressure reaction is performed in the reaction vessel. In addition, a corrosion detection fluid is supplied to a gap between the outer surface of the reaction vessel and the inner surface of the pressure-resistant vessel, the fluid for corrosion detection is taken out, and a change in the fluid for corrosion detection is monitored. It relates to a detection method.

The invention according to claim 2 for solving the above problem is characterized in that the corrosion detection fluid is a gas, and the change in the corrosion detection fluid is a change in the chemical composition of the fluid. is there.

According to a third aspect of the present invention, a fluid for detecting corrosion is a liquid, and the change in the fluid for detecting corrosion is a change in conductivity, pH, or ion concentration of the fluid. It is characterized by the following.

According to a fourth aspect of the present invention, there is provided a reaction apparatus having a structure in which a reaction vessel for performing a high-pressure reaction is disposed in a pressure-resistant vessel, wherein a gap between an outer surface of the reaction vessel and an inner surface of the pressure-resistant vessel is provided. The present invention relates to a method for detecting corrosion of a high-pressure reaction vessel, characterized in that a liquid or a gas is filled in a liquid and a pressure fluctuation of the gap is monitored.

According to a fifth aspect of the present invention, there is provided a reactor having a structure in which a reaction vessel for performing a high-pressure reaction is disposed in a pressure-resistant vessel, wherein a gap between an outer surface of the reaction vessel and an inner surface of the pressure-resistant vessel is provided. A high-pressure reaction vessel provided with fluid supply means for supplying a corrosion detection fluid to the fluid, fluid removal means for removing the corrosion detection fluid, and monitoring means for monitoring changes in the removed corrosion detection fluid. The present invention relates to a corrosion detection device.

According to a sixth aspect of the present invention, there is provided a reaction apparatus having a structure in which a reaction vessel for performing a high-pressure reaction is disposed in a pressure-resistant vessel, wherein a gap between an outer surface of the reaction vessel and an inner surface of the pressure-resistant vessel is provided. The present invention relates to an apparatus for detecting corrosion of a high-pressure reactor, provided with a monitoring means for monitoring a change in the pressure of a liquid or a gas filled in the vessel.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method and apparatus for detecting corrosion of a high-pressure reactor according to the present invention, the reactor has a structure in which a reaction vessel for performing a high-pressure reaction is covered with a pressure-resistant vessel and hermetically closed.

According to the present invention, in order to detect pinhole corrosion in a reaction vessel for performing a high-pressure reaction, a fluid for corrosion detection is supplied to a gap between the outer surface of the high-pressure reaction vessel and the inner surface of the pressure-resistant vessel, and the fluid for corrosion detection is supplied. It is characterized in that corrosion of the reaction vessel is detected by monitoring the change.

When pinhole corrosion occurs in the reaction vessel, compounds in the reaction vessel flow out and mix into the corrosion detection fluid, so that the chemical composition, pH, and conductivity of the corrosion detection fluid change. Therefore, the chemical composition of the detection fluid, pH,
By monitoring the change in conductivity, the occurrence of pinholes in the reaction vessel can be detected.

The detection fluid may be any fluid as long as it does not change its composition due to hydrolysis, thermal decomposition, or oxidative decomposition and has a different composition from that in the reactor that performs the high-pressure reaction. For example, air, nitrogen, oxygen, etc. Examples include liquids such as gas and water.

Further, in order to clarify the detection, a tracer may be mixed into the decomposition object. As the tracer to be used, a substance which is easy to measure and has no reactivity is preferable, and examples thereof include rare gases and ions.

As a means for monitoring changes in the chemical composition of a gas using a gas such as air as a fluid for detecting corrosion, zirconia, galvanic cells, a magnetic pressure type, a magnetic dumbbell type or a porous type oxygen meter are used. , An infrared absorption type carbon monoxide meter and a carbon dioxide meter.

For example, when a supercritical hydroxylation decomposition reaction is performed as a high-pressure reaction, the chemical composition in the high-pressure reaction vessel has a lower oxygen concentration and a higher carbon dioxide concentration than air, so that a pinhole is formed in the high-pressure reaction vessel. Occurs and the fluid in the high-pressure reaction vessel leaks, the oxygen concentration of the detection fluid decreases or the carbon dioxide concentration increases. Therefore, corrosion of the high-pressure reactor can be detected by using air as the corrosion detection fluid and monitoring its oxygen concentration and carbon dioxide concentration.

In the case where ions such as chloride ions are present in the reaction vessel, if water is used as the corrosion detection fluid instead of air, the ion concentration or pH of the water is monitored, and the reaction vessel is monitored. Pinholes can be detected.

When a liquid such as water is used as the detection fluid, the high-pressure reaction vessel is cooled, and the temperature of the reaction field in the high-pressure reaction vessel tends to decrease. Conversely, when it is desired to prevent the reaction field temperature from lowering, a high pressure reactor is preferably made of ceramics having excellent heat insulation and corrosion resistance.

A gap formed between the outer surface of the reaction vessel and the inner face of the pressure vessel is in fluid communication with the inside of the high-pressure reaction vessel, so that the pressure in the gap and the pressure in the reaction vessel become substantially the same. In the case of a reactor having a structure, the chemical composition of the void does not change due to the corrosion of a pinhole or the like generated in the reaction vessel. When significant corrosion occurs due to a large crack in the reaction vessel, the chemical composition of the void changes.

Further, by supplying a liquid or gas into the space between the outer surface of the reaction vessel and the inner surface of the pressure-resistant container without supplying the corrosion detection fluid, and monitoring the change in the pressure of the gas or liquid in the space. Can also detect corrosion of the reaction vessel. That is, when a pinhole occurs in the reaction vessel, if the pressure in the gap is higher than the pressure in the high-pressure reaction vessel, the pressure in the gap decreases, and the pressure in the gap is lower than the pressure in the high-pressure reaction vessel. In this case, the pressure in the gap increases. This method of monitoring the pressure change in the void is suitable when the change in the composition of the external fluid due to the ejection of the high-pressure fluid in the reaction vessel is poor or cannot be monitored.

In the present invention, since the reaction vessel for performing the high-pressure reaction is installed in the pressure-resistant vessel, even if a pinhole is generated in the reaction vessel and the high-pressure content in the reaction vessel leaks out of the system, It is safe because it does not leak.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
An embodiment will be described.

FIG. 1 is a flow chart showing one embodiment of a method for detecting corrosion of a supercritical hydroxylation decomposition apparatus. The coil-shaped reaction vessel 1a for performing the supercritical hydroxylation decomposition reaction includes a pressure-resistant vessel 2
It is arranged in a sealed state inside. The decomposition target 4 and the air 3 as the oxidizing agent are supplied to the reaction vessel 1a together with the supercritical water 5. In the reaction vessel 1a, the supercritical hydroxylation reaction proceeds under the supercritical condition of water, and the decomposition product is decomposed into water and carbon dioxide. Cool, depressurize and discharge outside the system.

In order to detect the corrosion of the reaction vessel 1a, air as a corrosion detection fluid is introduced into the pressure-resistant vessel 2 through the flow control valve 10 through the detection fluid supply line 6, and is taken out through the corrosion detection fluid take-out line 8, and A part of the corrosion detection fluid is supplied to the analyzer 11 via the control valve 9, and the analyzer 11 monitors the concentrations of O ₂ , CO ₂ , and CO in the corrosion detection fluid.

When a pinhole is generated in the reaction vessel 1a,
Since the processing fluid in the reaction vessel leaks, the oxygen concentration decreases and the carbon dioxide concentration increases. Therefore, by analyzing and monitoring the composition of the corrosion detection fluid with the analyzer 11, the occurrence of pinholes can be detected. The safety valve 12 may be attached to the pressure vessel 2 to prevent the pressure inside the pressure vessel from rapidly increasing in case the reaction vessel 1a is severely corroded and broken.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
An embodiment will be described.

FIG. 2 is a flow chart showing one embodiment of a method for detecting corrosion of a supercritical hydroxylation decomposition apparatus. The reaction vessel 1 b for performing the supercritical hydroxylation decomposition reaction is disposed in the pressure-resistant vessel 2. The vessel-type reaction vessel 1b is in fluid communication with the inside of the pressure-resistant vessel 2 via a circulation path 1c. First, the decomposition object 4 and the air 3 as the oxidizing agent are supplied to the reaction vessel 1b together with the supercritical water 5. In the reaction vessel 1b, water becomes supercritical, and the supercritical hydroxylation decomposition reaction proceeds.
The process fluid decomposed into water and carbon dioxide is taken out from the process fluid take-out line 7 at the upper part of the reaction vessel 1b, and then cooled, decompressed and discharged out of the system.

In order to detect the corrosion of the reaction vessel 1b, a part of the air used for the supercritical hydroxylation decomposition is bypassed and introduced into the gap between the inner surface of the pressure vessel 2 and the outer surface of the reaction vessel 1b.
Take out from the detection fluid take-out line 8 and flow control valve 9
Is supplied to the analyzer 11 through the
In step 1, the concentrations of O ₂ , CO ₂ , and CO in the corrosion detection fluid are monitored.

In the apparatus shown in FIG. 2, the inner reaction vessel 1b and the outer pressure vessel 2 are in fluid communication with each other through the flow path 1c, so that even if pinhole-like corrosion occurs in the reaction vessel 1b. The composition of the air of the detection fluid does not change significantly. When severe corrosion due to a large crack or the like occurs in the reaction vessel 1b, the composition of the air of the detection fluid changes greatly, and the corrosion can be detected.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
An embodiment will be described.

FIG. 3 is a flow chart showing one embodiment of a method for detecting corrosion of a supercritical hydroxylation decomposition apparatus. The coil-shaped reaction vessel 1a for performing the supercritical hydroxylation decomposition reaction includes a pressure-resistant vessel 2
It is arranged in a sealed state inside. The decomposition target 4 and the air 3 as the oxidizing agent are supplied to the reaction vessel 1a together with the supercritical water 5. In the reaction vessel 1a, the supercritical hydroxylation decomposition reaction proceeds, and the decomposition target is decomposed into water and carbon dioxide. After being taken out from the processing fluid take-out line 7, it is cooled, decompressed, and discharged out of the system.

In the third embodiment, the corrosion detecting fluid is not supplied to the pressure-resistant container 2 and the pressure in the gap is measured by the pressure gauge 1.
Monitor at 4. When a pinhole occurs in the reaction vessel 2,
When the pressure in the gap is higher than the pressure in the reaction vessel 2, the pressure in the gap decreases. When the pressure in the gap is lower than the pressure in the reaction vessel 2, the pressure in the gap increases. The corrosion of the reaction vessel can be detected by monitoring the fluctuation of the pressure in the section.

[0038]

EXAMPLE 1 A corrosion detection test was performed using a corrosion detection apparatus as shown in FIG. The reactor had an outer diameter of 10.5 mm and a thickness of 1.8.
A 5 mm x 10 m length Hastelloy C-276 coil reactor was used. The pressure vessel was 300 mm outer diameter x 6 mm thickness x
A cylinder made of SUS316 having a length of 0.5 m was used. Under the conditions shown in Table 1, a mixed aqueous solution (T) of trichloroethylene (hereinafter abbreviated as “TCE”) and isopropyl alcohol (hereinafter abbreviated as “IPA”)
(CE concentration: 0.5 wt%, IPA concentration: 20 wt%) was subjected to supercritical hydroxylation decomposition. The temperature and pressure in the reactor were 600 ° C. and 25 MPa, and the temperature and pressure in the air gap were 50 ° C.
° C and 0.5 MPa.

[0039]

[Table 1]

Air as a fluid for detecting corrosion was taken out from a take-out line, and 0.001 Nm ³ /
After adjusting to the flow rate of Hr, "CGT-70" manufactured by Shimadzu Corporation
00, the respective concentrations of O ₂ , CO ₂ , and CO were measured.
Table 2 shows the measurement results.

[0041]

[Table 2]

As is clear from the results shown in Table 2, when pinhole corrosion occurs in the coil-type reaction vessel, the chemical composition of the air supplied to the gap changes (O ₂ decreases, C
O ₂ increases), so that corrosion of the reaction vessel can be detected.

Example 2 A corrosion detection test was performed using a corrosion detection apparatus as shown in FIG. The reactor has an outer diameter of 200 mm x thickness of 6 mm x
A 1 m long Hastelloy C-276 vessel reactor was used. The pressure vessel (vessel type) had an outer diameter of 450 mm and a thickness of 5 mm.
The one made of sus316 having a length of 0 mm and a length of 1.5 m was used. Under the conditions shown in Table 3, a mixed aqueous solution of TCE and IPA (TCE concentration: 0.5 wt%, IPA concentration: 20
wt%) was subjected to supercritical hydroxylic decomposition. The temperature and pressure in the reactor were 600 ° C. and 25 MPa.

[0044]

[Table 3]

Air as a corrosion detection fluid is taken out from a detection fluid take-out line, and 1 Nm ³ is supplied to the pressure control valve.
/ Hr flow rate is adjusted to "CGT-7" manufactured by Shimadzu Corporation.
000 ", the respective concentrations of O ₂ , CO ₂ , and CO were measured. Table 4 shows the measurement results. The value of "corrosion" in Table 4 is an air composition when a vessel having a large crack is used in the vessel type reaction vessel.

[0046]

[Table 4]

As is clear from the results shown in Table 4, when a large corrosion such as a crack occurs in the reaction vessel, the chemical composition of the air supplied to the gap changes (O ₂ decreases and CO ₂ increases). And the corrosion of the reaction vessel can be detected.

[0048]

According to the present invention, the occurrence of pinhole corrosion in a reaction vessel for performing a high-pressure reaction can be detected safely and reliably. It is safe because it does not leak.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a first embodiment of the present invention.

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

FIG. 3 is a flowchart showing an example of a third embodiment of the present invention.

[Explanation of symbols]

 1a, 1b High-pressure reaction vessel 1c Distribution path 2 Pressure vessel 3 Air 4 Decomposition target 5 Supercritical water 6 Corrosion detection fluid supply line 7 Supercritical hydroxylation decomposition treatment fluid take-out line 8 Corrosion detection fluid take-out line 9 Pressure control valve Reference Signs List 10 flow control valve 11 analyzer 12 safety valve 13 air bypass 14 pressure gauge

Claims (6)

[Claims] In a reaction apparatus having a structure in which a reaction vessel is arranged in a pressure vessel, a high-pressure reaction is performed in the reaction vessel and a corrosion detection fluid is supplied to a gap between an outer surface of the reaction vessel and an inner face of the pressure vessel. A method for detecting corrosion of the high-pressure reaction vessel, wherein the method detects the corrosion detection fluid and monitors a change in the corrosion detection fluid. 2. The method for detecting corrosion of a high-pressure reaction vessel according to claim 1, wherein the corrosion detection fluid is a gas, and the change in the corrosion detection fluid is a change in the chemical composition of the fluid. 3. The high-pressure reactor according to claim 1, wherein the fluid for corrosion detection is a liquid, and the change in the fluid for corrosion detection is a change in conductivity, pH, or ion concentration of the fluid. Corrosion detection method. 4. A reactor having a structure in which a reaction vessel for performing a high-pressure reaction is arranged in a pressure-resistant vessel, wherein a gap between the outer surface of the reaction vessel and the inner face of the pressure-resistant vessel is filled with a liquid or a gas to reduce pressure fluctuation in the gap. A method for detecting corrosion of a high-pressure reactor, characterized by monitoring. 5. A reactor having a structure in which a reaction vessel for performing a high-pressure reaction is disposed in a pressure-resistant vessel, a fluid supply means for supplying a corrosion detection fluid to a gap between an outer surface of the reaction vessel and an inner surface of the pressure-resistant vessel; A corrosion detecting device for a high-pressure reactor, comprising: a fluid extracting means for extracting a corrosion detecting fluid; and a monitoring means for monitoring a change in the extracted corrosion detecting fluid. 6. A reaction apparatus having a structure in which a reaction vessel for performing a high-pressure reaction is disposed in a pressure-resistant vessel, and monitors a change in pressure of a liquid or a gas filled in a gap between an outer surface of the reaction vessel and an inner surface of the pressure-resistant vessel. An apparatus for detecting corrosion of a high-pressure reactor, comprising a monitoring means.