Oxidation and corrosion test device for high-temperature, high-pressure corrosive fluid containing impurities

Abstract

To provide an oxidation and corrosion test device that prevents oxidation and corrosion during a test in a test chamber that exposes a test piece to a corrosive fluid, and reduces the cost of the test device.SOLUTION: An oxidation and corrosion test device comprises: a syringe upper section 13 into which a syringe driving fluid is supplied via a high-pressure pump 19 and a syringe upper inlet valve 15, and from which the fluid is discharged via a syringe upper outlet valve 16; a syringe lower section 14 into which a corrosive fluid is supplied via a syringe lower inlet valve 17 and from which the fluid is discharged toward a tubular test piece 21 side via a syringe lower outlet valve 18; a syringe 11 which has the syringe upper section 13 and the syringe lower section 14; a plunger 12 which is driven along the inner cylinder of the syringe 11 to alternately increase and decrease the volumes of the syringe upper section 13 and the syringe lower section 14; and a tubular test piece 21 which makes the corrosive fluid discharged via the syringe lower outlet valve 18 flow to a hollow portion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an oxidation and corrosion test apparatus for high-temperature and high-pressure corrosive fluids containing impurities.

Background Art

[0002] In order to achieve carbon neutrality by 2050, it is essential to expand the use of renewable energy. Among them, supercritical geothermal power generation is a method of self-blowing geothermal fluid in a supercritical state at 400 to 500 °C and 25 MPa or more deep in the volcanic zone to the ground and rotating a steam turbine to generate electricity. It is a renewable energy that does not generate carbon dioxide, uses a fluid at a higher temperature and pressure than conventional geothermal power generation, can obtain an electric power output equivalent to that of large-scale thermal power and nuclear power generation, and enables base load power generation that does not depend on foreign resources, day and night, or weather, and has attracted attention.

[0003] The supercritical geothermal fluid used in supercritical geothermal power generation is "supercritical water" having properties different from both water vapor (gas) and hot water (liquid). Moreover, it has been clarified by exploratory surveys that it has an acidity with a hydrogen ion index (pH index) of about 2 and contains a large amount of solid impurities such as silicon oxide. Supercritical water has high solubility, and an acidic solution reacts with metals even at room temperature. It is expected that solid impurities will erode the oxidation-resistant protective film formed on the metal surface. Therefore, it is expected that the oxidation and corrosion of the metal material used for the inner frame (casing) of the production well for collecting supercritical geothermal fluid will progress rapidly and the life will be shortened.

[0004] In order to design and select a casing material for supercritical geothermal power generation, it is necessary to investigate the oxidation and corrosion behavior of materials by high-temperature corrosive fluids containing impurities under high pressure. However, JIS Z 2281 "Method for High-Temperature Continuous Oxidation Test of Metallic Materials" in Non-Patent Document 1 and JIS Z 2287 "Method for Steam Oxidation Test of Metallic Materials for Boiler Tubes" in Non-Patent Document 2 only show oxidation test methods in high-temperature air and high-temperature steam without impurities at atmospheric pressure. Also, JIS Z 2291 "Method for High-Temperature Gas Corrosion Test of Metallic Materials" in Non-Patent Document 3 only shows a corrosion test method by high-temperature corrosive gas without impurities at atmospheric pressure.

[0005] On the other hand, in Patent Document 1, a corrosion test apparatus has been proposed for observing the corrosion behavior of a test piece made of a metallic material for a hydrothermal reaction treatment apparatus in a high-temperature corrosion environment with sodium sulfate present in a hydrothermal oxidation reaction system in a supercritical state. In this test apparatus, when a corrosion phenomenon occurs in the reaction vessel, oxygen in the reaction vessel is consumed, so a supply line for diluted hydrogen peroxide water for supplying oxygen into the reaction vessel is provided. Also, in Patent Document 2, since a corrosion environment in a supercritical state is created inside a Hastelloy C-276 tube and a sample is exposed to corrosion, the Hastelloy C-276 tube corresponds to the reaction vessel in Patent Document 1.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0007]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in the apparatus of Patent Document 1, the reaction vessel itself that is exposed to the corrosive environment may corrode, and the corrosive environment inside the reaction vessel may change. Furthermore, if the corrosion of the reaction vessel progresses, there is a problem that it needs to be replaced at high cost. In addition, the test piece is exposed to a supercritical corrosive liquid with no flow inside the reaction vessel, and there is no description for the case of a corrosive fluid with flow. Also, in the apparatus of Patent Document 2, there is a problem that the corrosive environment inside the reaction vessel may change during the corrosion test, and it is costly to fabricate and maintain the apparatus. Furthermore, since the corrosive test solution is injected by a high-pressure pump, the part that is in contact with the corrosive test solution inside the high-pressure pump corrodes early, which greatly affects the operation of the high-pressure pump. To prevent the corrosion inside the high-pressure pump, it is necessary to configure all the parts that come into contact with the corrosive test solution of the high-pressure pump with highly corrosion-resistant materials, which is not realistic from the cost point of view.

[0009] As described above, when a high-temperature corrosive fluid is pressurized and impurities are added in a conventional oxidation / corrosion test apparatus, there is a problem that the pump for delivering the corrosive fluid and the test chamber itself that exposes the test piece to the corrosive fluid are significantly oxidized / corroded, and the test cannot be carried out safely and accurately. There is also a problem that if the pump and the test chamber are made of materials with high oxidation resistance and corrosion resistance and have a pressure-resistant structure, the apparatus becomes extremely expensive and is not practical.

[0010] The present invention solves the above problems of the prior art, and an object thereof is to provide an oxidation / corrosion test apparatus that can prevent oxidation / corrosion during the test in a test chamber that exposes a test piece to a corrosive fluid and can achieve a low cost for the test apparatus.

Means for Solving the Problems

[0011] 〔1〕As shown in FIG. 1, for example, in the oxidation and corrosion test apparatus of the present invention, a fluid for driving a syringe is supplied through a high-pressure pump 19 and an upper syringe inlet valve 15, and the fluid for driving the syringe is discharged through an upper syringe outlet valve 16. It includes an upper syringe part 13, a corrosive fluid is supplied through a lower syringe inlet valve 17, and the corrosive fluid is sent to the tubular test piece 21 side through a lower syringe outlet valve 18. A lower syringe part 14, a syringe 11 having an upper syringe part 13 and a lower syringe part 14, a plunger 12 that is driven along the inner cylinder of the syringe 11 and alternately increases and decreases the volumes of the upper syringe part 13 and the lower syringe part 14, and a tubular test piece 21 that allows the corrosive fluid sent through the lower syringe outlet valve 18 to flow into the hollow part.

[0012] 〔2〕In the oxidation and corrosion test apparatus 〔1〕 of the present invention, preferably, further, a heater 24 for heating the tubular test piece 21 installed around the tubular test piece 21, and a cooler 22 for cooling the corrosive fluid that has passed through the tubular test piece 21 to room temperature are provided, and it is preferably configured to discharge the corrosive fluid that has passed through the cooler 22. Here, the room temperature refers to, for example, the range of 20°C to 50°C. 〔3〕In the oxidation and corrosion test apparatus 〔2〕 of the present invention, preferably, the heater 24 is configured to heat the connecting pipe between the tubular test piece 21 and the lower syringe outlet valve 18 to increase the temperature of the corrosive fluid. 〔4〕In the oxidation and corrosion test apparatus 〔2〕 or 〔3〕 of the present invention, preferably, further, it has a back pressure valve 23 provided in a pipeline for discharging the corrosive fluid that has passed through the cooler 22 to the corrosive fluid discharge port (D) side, and while operating the high-pressure pump 19, the back pressure valve 23 is closed, and a valve opening degree regulator for controlling to keep the pressure of the corrosive fluid in the pipeline from the lower syringe part 13 to the back pressure valve 23 high is provided. 〔5〕In the oxidation and corrosion test apparatus [1] to [4] of the present invention, preferably, the corrosive fluid may correspond to a supercritical geothermal fluid inside the tubular test piece 21. The supercritical geothermal fluid is a high-temperature and high-pressure fluid at 400 to 500 °C and 25 MPa or more, is a strongly acidic fluid with a pH value of 4 or less, and contains solid impurities such as silicon oxide. 〔6〕In the oxidation and corrosion test apparatus [1] to [4] of the present invention, preferably, the corrosive fluid may be a strongly acidic fluid with a pH value of 4 or less.

Advantages of the Invention

[0013] According to the oxidation and corrosion test apparatus for a high-temperature and high-pressure corrosive fluid containing impurities of the present invention, a high-temperature corrosive fluid containing high-pressure impurities can be sent to the test piece without directly contacting the pump, reducing the possibility of changes in the corrosion environment inside the reaction vessel during the corrosion test, and it is expected that the test can be carried out safely and accurately. In addition, only the inside of the test piece is exposed to the high-temperature corrosive fluid containing high-pressure impurities, eliminating the need to install equipment corresponding to the test chamber in the conventional oxidation and corrosion test apparatus. With an inexpensive material and a simple configuration, there is an effect that the oxidation and corrosion behavior by the high-temperature corrosive fluid containing high-pressure impurities can be investigated safely and accurately. In particular, since supercritical water appears at a high temperature and high pressure of 374.15 °C or more and 22.12 MPa or more, the oxidation and corrosion behavior by acidic or alkaline supercritical water containing impurities can be investigated for the first time by the oxidation and corrosion test apparatus for a high-temperature and high-pressure corrosive fluid containing impurities of the present invention.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0015] The present invention will be described below with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of an oxidization and corrosion test apparatus of the present invention with respect to a high-temperature and high-pressure corrosive fluid, showing a state where a corrosive test solution is being press-fitted. In the figure, for the pump chamber 10 side of the oxidization and corrosion test apparatus of the present invention, there are provided a syringe 11, a plunger 12, an upper part 13 of the syringe, a lower part 14 of the syringe, an upper inlet valve 15 of the syringe, an upper outlet valve 16 of the syringe, a lower inlet valve 17 of the syringe, a lower outlet valve 18 of the syringe, and a high-pressure pump 19. The corrosive fluid supply port (A) is connected to the lower part 14 of the syringe via the lower inlet valve 17 of the syringe. The fluid supply port (B) for driving the syringe is connected to the upper part 13 of the syringe via the upper inlet valve 15 of the syringe and the high-pressure pump 19. The fluid discharge port (C) for driving the syringe is connected to the upper part 13 of the syringe via the upper outlet valve 16 of the syringe. The inside of the syringe 11 is divided into the upper part 13 of the syringe and the lower part 14 of the syringe by a plunger 12 that moves up and down. The corrosive fluid is not limited to vapor (gas), and also includes liquid and supercritical states.

[0016] The 20 side of the laboratory is equipped with a tubular test piece 21, a cooler 22, a back pressure valve 23, a heater 24, a thermometer 25, and a pressure gauge 26. The tubular test piece 21 is connected to the lower part 14 of the syringe via the lower outlet valve 18 of the syringe. The cooler 22 is a kind of heat exchanger, which cools and condenses the vapor of the high-pressure corrosive fluid after extracting work on the pump chamber 10 side, and cools it to a room-temperature high-pressure corrosive fluid. In the cooler 22, for example, it may be cooled by heat exchange between cooling water and the corrosive fluid, but it is not limited to this, and air cooling by a cooling fan or cooling by a thermoelectric element may also be used. The corrosive fluid after passing through the cooler 22 is typically in a liquid state. The back pressure valve 23 adjusts the pressure on the primary side, which is the pump chamber 10 side. When the set pressure is exceeded, the pressure exceeding the set pressure on the primary side is released to the secondary side, thereby keeping the pressure on the primary side constant. Therefore, the back pressure valve 23 can be controlled to keep the pressure of the corrosive fluid in the pipe from the lower part 13 of the syringe to the back pressure valve 23 high. The corrosive fluid discharge port (D) is connected to the 20 side of the laboratory via the cooler 22 and the back pressure valve 23. As the heater 24, an electric heater surrounding the circumferential surface of the tubular test piece 21 may be used, but a heat exchanger that performs heat exchange other than an electric heater may also be used. The thermometer 25 (TE) measures the temperature of the tubular test piece 21. For example, a thermocouple is used, but it is not limited to this. The pressure gauge 26 measures the pressure inside the tubular test piece 21. For example, a Bourdon tube pressure gauge that utilizes the change in the curvature of the Bourdon tube is used, but it is not limited to this. Note that for the pipe between the tubular test piece 21 and the cooler 22, a material that exhibits sufficient corrosion resistance to the corrosive fluid at the same temperature and pressure as the test conditions, for example, C-276 nickel alloy, may be used, but it is not limited to this. For parts other than the pipe between the tubular test piece 21 and the cooler 22, a material that exhibits sufficient corrosion resistance to the corrosive fluid at the same pressure as the test conditions, for example, SUS316, may be used, but it is not limited to this.

[0017] Next, the operation of the apparatus configured as described above will be explained. When the corrosion test solution shown in FIG. 1 is being pressed in, the valve regulator (not shown) closes the upper syringe inlet valve 15 and the lower syringe outlet valve 18, opens the upper syringe outlet valve 16 and the lower syringe inlet valve 17, and injects the corrosive fluid from the corrosive fluid supply port (A) through the lower syringe inlet valve 17 into the lower syringe 14. As the injection progresses, the plunger 12 moves upward, and the contents of the upper syringe 13 are discharged through the upper syringe outlet valve 16 to the syringe drive fluid discharge port (C). The upper syringe inlet valve 15, the upper syringe outlet valve 16, the lower syringe inlet valve 17, and the lower syringe outlet valve 18 are operated by a valve opening degree regulator (not shown) while synchronizing the opening and closing timings.

[0018] FIG. 2 shows the state where the injection of the corrosion test solution is completed. The plunger 12 moves to the uppermost position, and all the contents of the upper syringe 13 are discharged. Then, the valve regulator (not shown) closes the upper syringe outlet valve 16 and the lower syringe inlet valve 17.

[0019] FIG. 3 shows the state where the corrosion test solution is being discharged. The valve regulator (not shown) opens the upper syringe inlet valve 15 and the lower syringe outlet valve 18, and injects water or air from the syringe drive fluid supply port (B) into the upper syringe 13 through the upper syringe inlet valve 15 by the high-pressure pump 19. Then, due to the pressure at which the high-pressure pump 19 operates, the plunger 12 is pushed downward, and the corrosive fluid in the lower syringe 14 is sent to the tubular test piece 21 through the lower syringe outlet valve 18. Then, the corrosive fluid is discharged to the corrosive fluid discharge port (D) through the cooler 22 and the back pressure valve 23.

[0020] FIG. 4 shows the state where the discharge of the corrosion test solution is completed. When the discharge of the corrosion test solution in the lower syringe 14 is completed by the plunger 12, the valve regulator (not shown) closes the upper syringe inlet valve 15 and the lower syringe outlet valve 18, and then opens the upper syringe outlet valve 16 and the lower syringe inlet valve 17 to return to the state of FIG. 1.

[0021] Preferably, in the state of discharging the corrosion test solution shown in FIG. 3, if the back pressure valve 23 is closed while operating the high pressure pump 19, the pressure of the corrosive fluid in the pipe from the lower part 13 of the syringe to the back pressure valve 23 can be increased. For the linked operation of the high pressure pump 19 and the back pressure valve 23, for example, a regulator may be used. Furthermore, if the tubular test piece 21 is heated by the heater 24 installed around the tubular test piece 21 and cooled by the cooler 22, it is possible to expose only the inside around the tubular test piece 21 to the high-temperature corrosive fluid containing impurities under high pressure. For the control of the operations of the heater 24 and the cooler 22, a thermometer 25 (such as a thermistor) and a pressure gauge 26 for measuring the temperature and pressure of the corrosive fluid flowing through the hollow part of the tubular test piece 21 may be used, and for example, a regulator (not shown) may be used for control.

[0022] In the above embodiment, an example of the oxidation / corrosion test apparatus is shown, but the present invention is not limited thereto, and various design changes are possible within the scope obvious to those skilled in the art. For example, in order to make the corrosive fluid in a state corresponding to supercritical geothermal fluid, a heavy oil cooking burner may be used as a heater to supply the corrosive fluid in a supercritical geothermal fluid state to the tubular test piece.

Industrial Applicability

[0023] By using the oxidation / corrosion test apparatus for high-temperature and high-pressure corrosive fluids containing impurities of the present invention, it becomes possible to investigate the oxidation / corrosion behavior of materials by high-temperature acidic corrosive fluids containing impurities under high pressure, and it can contribute to the design and selection of casing materials for supercritical geothermal power generation, boilers and pressure vessels of power plants such as supercritical pressure thermal power generation, biomass power generation, and waste power generation, and high-temperature structural members of chemical plants.

Explanation of Reference Numerals

[0024] 10 Pump chamber 11 Syringe 12 Plunger 13 Upper part of syringe 14 Lower part of syringe 15 Upper syringe inlet valve 16 Upper syringe outlet valve 17 Lower syringe inlet valve 18 Lower syringe outlet valve 19 High-pressure pump 20 Laboratory 21 Tubular test piece 22 Cooler (condenser) 23 Back-pressure valve 24 Heater 25 Thermometer TE 26 Pressure gauge (A) Corrosive fluid supply port (B) Fluid supply port for syringe drive (C) Fluid discharge port for syringe drive (D) Corrosive fluid discharge port

Claims

1. The fluid for driving the syringe is supplied via a high-pressure pump and a syringe upper inlet valve, and discharged through a syringe upper outlet valve, The corrosive fluid is supplied through the lower inlet valve of the syringe and delivered to the tubular test piece side through the lower outlet valve of the syringe, A syringe having the upper part of the syringe and the lower part of the syringe, A plunger is driven along the inner cylinder of the syringe and alternately increases and decreases the volume of the upper and lower parts of the syringe. A tubular test piece having a hollow section through which the corrosive fluid delivered via the lower outlet valve of the syringe flows, An oxidation and corrosion testing apparatus equipped with the following features.

2. Furthermore, a heater is placed around the tubular test piece to heat the tubular test piece, A cooler for cooling the corrosive fluid that has passed through the tubular test piece to room temperature, The oxidation and corrosion testing apparatus according to claim 1, comprising a cooler configured to discharge the corrosive fluid that has passed through the cooler.

3. Furthermore, the oxidation and corrosion testing apparatus according to claim 2, wherein the heater is configured to heat the connecting pipe between the tubular test piece and the lower outlet valve of the syringe to raise the temperature of the corrosive fluid.

4. Furthermore, it has a back pressure valve provided in the pipeline that discharges the corrosive fluid that has passed through the cooler to the corrosive fluid outlet side, A valve opening controller that controls the pressure of the corrosive fluid in the piping from the bottom of the syringe to the back pressure valve by closing the back pressure valve while operating the high-pressure pump, The oxidation and corrosion testing apparatus according to claim 2 or 3, comprising the above.

5. The oxidation and corrosion testing apparatus according to any one of claims 1 to 3, wherein the corrosive fluid corresponds to a supercritical geothermal fluid within the tubular test specimen.

6. The oxidation and corrosion testing apparatus according to any one of claims 1 to 3, wherein the corrosive fluid is a strongly acidic fluid with a pH value of 4 or less.

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