Graphite sample holder, graphite furnace, graphite oxidation corrosion test bench

Abstract

The application discloses a graphite sample clamp, a graphite furnace and a graphite oxidation corrosion test bench, and relates to the technical field of graphite sample clamps. The graphite sample clamp comprises a first clamping piece and a second clamping piece. The first clamping piece comprises a first clamping piece body and a protruding part arranged on the first clamping piece body. A through hole is arranged on the graphite sample. The second clamping piece comprises a second clamping piece body and a recessed part arranged on the second clamping piece body. The protruding part of the first clamping piece passes through the through hole of the graphite sample and enters the recessed part of the second clamping piece to be detachably connected with the second clamping piece. The graphite sample is clamped between the first clamping piece body and the second clamping piece body.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of graphite oxidation corrosion and particularly relates to a graphite sample clamp, a graphite furnace and a graphite oxidation corrosion test bench. BACKGROUND

[0002] A high temperature gas cooled reactor uses nuclear graphite as the structural material and moderator material of the reactor core and helium as the coolant. Helium is an inert gas and cannot chemically react with graphite.

[0003] However, under high temperature conditions, oxygen can react with graphite material as follows:

[0004] 1 / 2O2+C=CO, ΔH=-110.5kJ / mol (1)

[0006] O2+C=CO2, ΔH=-393.5kJ / mol (2)

[0008] 1 / 2O2+CO=CO2, ΔH=-283.0kJ / mol (3)

[0010] The above chemical reactions can affect the performance of the graphite components of the reactor core, and further affect the service life of the graphite components and the safety of operation. Once an air inlet accident occurs, the graphite is easily corroded, causing rapid failure of the graphite components, which may lead to more serious consequences. Therefore, the test measurement of the corrosion rate of the graphite material in the reactor at high temperature plays an important role in evaluating the possible accident consequences of the reactor and improving the ability of the reactor to deal with sudden accidents.

[0011] The methods for measuring the oxidation corrosion reaction rate of nuclear graphite mainly include gas concentration method and thermogravimetric method. The basic principle of the gas concentration method for measuring the corrosion reaction rate of graphite is as follows: oxygen and helium (or other inert gases) are mixed in a certain proportion, introduced into a heating furnace containing a graphite sample, the heating furnace provides a high temperature environment, the oxygen reacts with the graphite, and the generated gas is discharged from the tubular graphite furnace and introduced into a measuring instrument for composition measurement. The consumption of oxygen before and after corrosion, or the mass of the generated gas products CO and CO2 can be measured, so as to calculate the oxidation corrosion reaction rate of graphite.

[0012] At present, the design of this type of bench at home and abroad can only realize high temperature corrosion reaction and reaction rate measurement under low flow rate conditions, or cannot guarantee the laminar flow and high temperature state of the fluid under higher flow rate. SUMMARY

[0013] The technical problem to be solved by the present application is to provide a graphite sample clamp, a graphite furnace and a graphite oxidation corrosion test bench, which can realize fluid heating under high flow rate conditions and ensure the environmental temperature required by the graphite oxidation corrosion reaction.

[0014] The technical solution adopted to solve the technical problem of the present application is to provide a graphite sample clamp, which comprises: a first clamping member and a second clamping member, the first clamping member comprises a first clamping member body and a protruding portion arranged on the first clamping member body, a through hole is arranged on a graphite sample, the second clamping member comprises a second clamping member body and a recess arranged on the second clamping member body, the protruding portion of the first clamping member passes through the through hole of the graphite sample and enters the recess of the second clamping member to be detachably connected with the recess, and the graphite sample is clamped between the first clamping member body and the second clamping member body.

[0015] Preferably, the protruding portion of the first clamping member and the recess of the second clamping member are connected through threads.

[0016] Preferably, the first clamping member is cylindrical, and the second clamping member is conical.

[0017] Preferably, the material of the graphite sample clamp is quartz or alumina.

[0018] The present application also provides a graphite furnace, which comprises: a furnace body, a furnace cover arranged on the furnace body, the above-mentioned graphite sample clamp located in the furnace body, and a connecting piece, one end of the connecting piece is connected with the first clamping member, the other end of the connecting piece is connected with the furnace cover, and a gap is left between the graphite sample clamp and the furnace hearth of the furnace body, which is used for gas flow.

[0019] Preferably, a groove is arranged on the first clamping member, and the connecting piece is connected with the groove on the first clamping member through threads.

[0020] Preferably, the graphite sample clamp is the above-mentioned graphite sample clamp, the furnace hearth comprises a first furnace hearth and a second furnace hearth, one end of the first furnace hearth is connected with the second furnace hearth, the first furnace hearth is cylindrical, the second furnace hearth is conical, a gas inlet is arranged at the tapered tip of the second furnace hearth, the second furnace hearth is used for gas flow guiding, a gas outlet is arranged at the other end of the first furnace hearth, the first clamping member is arranged in the first furnace hearth, the second clamping member is located in the second furnace hearth, and the shape of the furnace hearth is matched with the shape of the graphite sample clamp.

[0021] Preferably, the inner diameter of the furnace hearth is 26-41mm.

[0022] The diameter of the graphite sample is the same as the diameter of the graphite sample clamp, and the diameter of the graphite sample and the graphite sample clamp is 21-30mm.

[0023] The length of the graphite sample clamp is 100-300 mm;

[0024] The total length of the furnace hearth is 400-600 mm.

[0025] The application also provides a graphite oxidation corrosion test bench, comprising:

[0026] A helium storage tank for storing helium;

[0027] An oxygen storage tank for storing oxygen;

[0028] A mixing container connected with the helium storage tank and the oxygen storage tank respectively, the mixing container being used for mixing and preheating the helium and the oxygen;

[0029] A graphite furnace connected with the mixing container, the graphite furnace being used for heating materials therein, and the graphite being corroded by the oxygen in the graphite furnace to generate carbon monoxide and carbon dioxide;

[0030] A cooling device connected with the graphite furnace, the cooling device being used for cooling the materials flowing out of the graphite furnace;

[0031] A flow detection device connected with the cooling device, the flow detection device being used for detecting the flow of the gas at the outlet of the cooling device;

[0032] A gas detection device connected with the flow detection device, the gas detection device being used for measuring the proportion of the generated carbon monoxide and carbon dioxide corresponding to the flow, and calculating the mass of the graphite consumed per unit time and the oxidation corrosion reaction rate of the graphite according to the total flow and the proportion of the components.

[0033] Preferably, the graphite oxidation corrosion test bench further comprises:

[0034] A first mass flow controller arranged on a connecting pipeline between the helium storage tank and the mixing container, the first mass flow controller being used for controlling the mass flow of the helium into the mixing container and sending to a controller;

[0035] A second mass flow controller arranged on a connecting pipeline between the oxygen storage tank and the mixing container, the second mass flow controller being used for controlling the mass flow of the oxygen into the mixing container and sending to the controller;

[0036] A first temperature detection device arranged on the mixing container, the first temperature detection device being used for detecting the temperature in the mixing container and sending to the controller;

[0037] A first pressure detection device arranged on the mixing container, the first pressure detection device being used for detecting the pressure in the mixing container and sending to the controller;

[0038] A second temperature detection device is arranged on the graphite furnace, and the second temperature detection device is used for detecting the temperature in the graphite furnace and sending the temperature to the controller.

[0039] A second pressure detection device is arranged on the graphite furnace, and the second pressure detection device is used for detecting the pressure in the graphite furnace and sending the pressure to the controller.

[0040] The controller is connected with the gas detection device, the gas detection device detects the proportion of the generated product carbon monoxide and carbon dioxide under the corresponding flow rate and sends the proportion to the controller, and the controller calculates the mass of the graphite consumed in a unit time and obtains the graphite oxidation corrosion reaction rate through the total flow rate and the proportion of the components.

[0041] The graphite sample clamp, the graphite furnace and the graphite oxidation corrosion test bench in the application can realize fluid heating under high flow rate conditions through the design of the new heating container, ensure the environmental temperature required by the graphite oxidation corrosion reaction, and keep the high-speed fluid in a laminar flow state through the flow channel design, so as to reduce the influence of the instability factors of the fluid on the measurement of the corrosion kinetics parameters. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a structural schematic view of the graphite sample clamp in the embodiment 2 of the application;

[0043] Figure 2 is a structural schematic view of the graphite furnace in the embodiment 2 of the application;

[0044] Figure 3 is a structural schematic view of the graphite oxidation corrosion test bench in the embodiment 2 of the application.

[0045] In the figure, 1 is a first clamping part body, 2 is a convex part, 3 is a graphite sample, 4 is a second clamping part body, 5 is a concave part, 6 is a furnace cover, 7 is a connecting part, 8 is a first furnace body hearth, 9 is a second furnace body hearth, 10 is an air inlet, 11 is an air outlet, 12 is a helium storage tank, 13 is an oxygen storage tank, 14 is a mixing container, 15 is a graphite furnace, 16 is a cooling device, 17 is a flow detection device, 18 is a gas detection device, 19 is a first mass flow controller, 20 is a second mass flow controller, 21 is a first temperature detection device, 22 is a first pressure detection device, 23 is a second temperature detection device, 24 is a second pressure detection device, 25 is a controller, 26 is a computer, 27 is a pressure relief valve, 28 is a first pressure reducing valve, 29 is a first stop valve, 30 is a second stop valve, 31 is a second pressure reducing valve, 32 is a third stop valve, 33 is a fourth stop valve, 34 is a fifth stop valve, 35 is a tail gas treatment device, 36 is a sixth stop valve, 37 is a seventh stop valve, 38 is an eighth stop valve, and 39 is a groove. DETAILED DESCRIPTION

[0046] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in conjunction with the drawings and specific embodiments.

[0047] The embodiments of the present patent are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present patent, and cannot be understood as a limitation of the present patent.

[0048] In the description of the present patent, it needs to be understood that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present patent and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present patent.

[0049] In the description of the present patent, it needs to be understood that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "setting" should be understood broadly, for example, it can be fixedly connected, set, or it can be detachably connected, set, or integrally connected, set. For those skilled in the art, the specific meanings of the above terms in the present patent can be understood according to the specific circumstances.

[0050] Embodiment 1

[0051] The present embodiment provides a graphite sample clamp, comprising: a first clamping member, a second clamping member, the first clamping member comprising a first clamping member body, a protruding portion provided on the first clamping member body, a through hole being provided on the graphite sample, the second clamping member comprising a second clamping member body, a recessed portion provided on the second clamping member body, the protruding portion of the first clamping member passing through the through hole of the graphite sample and being detachably connected with the recessed portion of the second clamping member, and the graphite sample being clamped between the first clamping member body and the second clamping member body.

[0052] The present embodiment also provides a graphite furnace, comprising: a furnace body, a furnace cover provided on the furnace body, the above-mentioned graphite sample clamp located in the furnace body, and a connecting member, one end of the connecting member being connected with the first clamping member, and the other end of the connecting member being connected with the furnace cover, and the graphite sample clamp and the furnace hearth of the furnace body leaving a gap for gas flow.

[0053] The present embodiment also provides a graphite oxidation corrosion test bench, comprising:

[0054] A helium storage tank for storing helium;

[0055] Oxygen storage tanks are used to store oxygen.

[0056] A mixing container is connected to a helium storage tank and an oxygen storage tank, respectively. The mixing container is used to mix helium and oxygen and preheat them.

[0057] A graphite furnace is connected to a mixing container. The graphite furnace is used to heat the materials inside. Oxygen inside the graphite furnace is used to conduct a corrosion test on the graphite. The graphite reacts with oxygen to produce carbon monoxide and carbon dioxide.

[0058] A cooling device, connected to a graphite furnace, is used to cool the material flowing out of the graphite furnace.

[0059] A flow detection device, connected to the cooling device, is used to detect the flow rate of the gas at the outlet of the cooling device.

[0060] A gas detection device is connected to a flow detection device. The gas detection device is used to measure the proportion of carbon monoxide and carbon dioxide generated at the corresponding flow rate. By calculating the total flow rate and the proportion of components, the mass of graphite consumed per unit time is obtained, and the graphite oxidation and corrosion reaction rate is obtained.

[0061] In this embodiment, the graphite sample fixture, graphite furnace, and graphite oxidation corrosion test bench are designed with new heating containers and a new preheating container. This enables fluid heating under high flow rate conditions, ensuring the ambient temperature required for the graphite oxidation corrosion reaction. Furthermore, the flow channel design keeps the high-speed fluid in a laminar state, reducing the impact of fluid instability factors on the measurement of corrosion kinetic parameters.

[0062] Example 2

[0063] like Figure 1 As shown, this embodiment provides a graphite sample clamp, including: a first clamping member and a second clamping member. The first clamping member includes a first clamping member body 1 and a protrusion 2 disposed on the first clamping member body 1. A through hole is provided on the graphite sample 3. The second clamping member includes a second clamping member body 4 and a recess 5 disposed on the second clamping member body 4. The protrusion 2 of the first clamping member passes through the through hole of the graphite sample 3 and enters the recess 5 of the second clamping member for detachable connection. The graphite sample is clamped between the first clamping member body 1 and the second clamping member body 4. Specifically, in this embodiment, the protrusion 2 on the first clamping member body 1 is a tenon, and the recess 5 on the second clamping member body 4 is a mortise. Specifically, in this embodiment, the graphite sample 3 has a through hole along its central axis of symmetry.

[0064] Preferably, the protrusion 2 of the first clamping member and the recess 5 of the second clamping member are connected by threads.

[0065] Preferably, the first clamping member is cylindrical and the second clamping member is conical.

[0066] Preferably, the graphite sample holder is made of quartz or alumina.

[0067] like Figure 2 As shown, this embodiment also provides a graphite furnace 15, including: a furnace body, a furnace cover 6 disposed on the furnace body, the above-mentioned graphite sample clamp located in the furnace body, and a connector 7. One end of the connector 7 is connected to the first clamping member, and the other end of the connector 7 is connected to the furnace cover 6. A gap is left between the graphite sample clamp and the furnace chamber of the furnace body, and the gap is used for gas flow.

[0068] Specifically, in this embodiment, the connector 7 is a metal connecting rod.

[0069] Preferably, the first clamping member is provided with a groove 39, and the connecting member 7 is connected to the groove 39 on the first clamping member by a thread.

[0070] Preferably, the graphite sample holder is the graphite sample holder described above. The furnace body includes a first furnace body chamber 8 and a second furnace body chamber 9. One end of the first furnace body chamber 8 is connected to the second furnace body chamber 9. The first furnace body chamber 8 is cylindrical, and the second furnace body chamber 9 is conical. An air inlet 10 is provided at the conical tip of the second furnace body chamber 9. The second furnace body chamber 9 is used for gas guidance. An air outlet 11 is provided at the other end of the first furnace body chamber 8. A first clamping member is disposed in the first furnace body chamber 8, and a second clamping member is located in the second furnace body chamber 9. The shape of the furnace body chamber is adapted to the shape of the graphite sample holder.

[0071] Preferably, the inner diameter of the furnace body and furnace chamber is 26–41 mm;

[0072] The diameter of graphite sample 3 is the same as the diameter of graphite sample fixture, and the diameters of graphite sample 3 and graphite sample fixture are 21-30 mm.

[0073] The length of the graphite sample holder is 100–300 mm;

[0074] The total length of the furnace body and furnace chamber is 400-600 mm.

[0075] like Figure 3 The embodiment shown also provides a graphite oxidation corrosion test bench, including:

[0076] Helium storage tank 12, used for storing helium;

[0077] Oxygen storage tank 13 is used to store oxygen;

[0078] The mixing container 14 is connected to the helium storage tank 12 and the oxygen storage tank 13 respectively. The mixing container 14 is used to mix helium and oxygen and preheat them.

[0079] Graphite furnace 15 is connected to mixing container 14. The graphite furnace 15 is used to heat the materials inside. Oxygen in graphite furnace 15 is used to conduct a corrosion test on graphite. Graphite reacts with oxygen to produce carbon monoxide and carbon dioxide.

[0080] Cooling device 16 is connected to graphite furnace 15 and is used to cool the material flowing out of graphite furnace 15.

[0081] The flow detection device 17 is connected to the cooling device 16 and is used to detect the flow rate of the gas at the outlet of the cooling device 16; specifically, in this embodiment, the flow detection device 17 is a flow meter.

[0082] A gas detection device 18 is connected to a flow detection device 17. The gas detection device 18 is used to measure the proportion of carbon monoxide and carbon dioxide generated at a corresponding flow rate. By calculating the total flow rate and the proportion of components, the mass of graphite consumed per unit time is obtained, and the graphite oxidation and corrosion reaction rate is derived. Specifically, in this embodiment, the gas detection device 18 is a gas chromatograph.

[0083] Preferably, the graphite oxidation corrosion test rig further includes:

[0084] The first mass flow controller 19 is installed on the connecting pipe between the helium storage tank 12 and the mixing container 14. The first mass flow controller 19 is used to control the mass flow rate of the helium gas introduced into the mixing container 14 and send it to the controller 25.

[0085] The second mass flow controller 20 is installed on the connecting pipe between the oxygen storage tank 13 and the mixing container 14. The second mass flow controller 20 is used to control the mass flow rate of oxygen introduced into the mixing container 14 and send it to the controller 25.

[0086] A first temperature detection device 21 is disposed on the mixing container 14. The first temperature detection device 21 is used to detect the temperature inside the mixing container 14 and send it to the controller 25. Specifically, in this embodiment, the first temperature detection device 21 is a first thermocouple.

[0087] A first pressure detection device 22 is disposed on the mixing container 14. The first pressure detection device 22 is used to detect the pressure inside the mixing container 14 and send it to the controller 25. Specifically, in this embodiment, the first pressure detection device 22 is a first pressure sensor, and the second pressure detection device 24 is a second pressure sensor.

[0088] The second temperature detection device 23 is installed on the graphite furnace 15. The second temperature detection device 23 is used to detect the temperature inside the graphite furnace 15 and send it to the controller 25. Specifically, in this embodiment, the second temperature detection device 23 is a second thermocouple.

[0089] The second pressure detection device 24 is installed on the graphite furnace 15. The second pressure detection device 24 is used to detect the pressure inside the graphite furnace 15 and send it to the controller 25.

[0090] The controller 25 is connected to the gas detection device 18. The gas detection device 18 measures the proportion of carbon monoxide and carbon dioxide generated at the corresponding flow rate and sends this information to the controller 25. The controller 25 calculates the mass of graphite consumed per unit time based on the total flow rate and the component proportions, thus determining the graphite oxidation and corrosion reaction rate. Specifically, the controller 25 is a programmable logic controller (PLC), and ultimately controls the instruments and reads data through a computer terminal 26.

[0091] A pressure relief valve 27 is installed on the tubular graphite furnace 15.

[0092] Specifically, a first pressure-reducing valve 28, a first shut-off valve 29, and a second shut-off valve 30 are installed on the connecting pipeline between the helium storage tank 12 and the mixing container 14. There are two helium storage tanks 12, and the first pressure-reducing valve 28 and the first shut-off valve 29 are respectively installed on the helium branch pipelines.

[0093] The first shut-off valve 29 is located downstream of the first pressure reducing valve 28. The two helium branch pipelines are merged into a helium main pipeline. The second shut-off valve 30 is located on the helium main pipeline. The first mass flow controller 19 is located downstream of the first shut-off valve 29, and the second shut-off valve 30 is located upstream of the first mass flow controller 19.

[0094] Specifically, a second pressure-reducing valve 31, a third shut-off valve 32, and a fourth shut-off valve 33 are installed on the connecting pipeline between the oxygen storage tank 13 and the mixing container 14. There are two oxygen storage tanks 13, and the oxygen branch pipelines are respectively equipped with the second pressure-reducing valve 31 and the third shut-off valve 32.

[0095] The third shut-off valve 32 is located downstream of the second pressure reducing valve 31. The two oxygen branch pipelines are merged into an oxygen main pipe. The fourth shut-off valve 33 is located on the oxygen main pipe. The second mass flow controller 20 is located downstream of the fourth shut-off valve 33. The fourth shut-off valve 33 is located upstream of the second mass flow controller 20.

[0096] The helium header and oxygen header are combined into a main header, which is equipped with a fifth shut-off valve 34 and is connected to the mixing container 14.

[0097] The cooling device 16 is connected to the gas detection device 18 through the first pipe, and the cooling device 16 is connected to the exhaust gas treatment device 35 through the second pipe. The cooling device 16 is connected to the first pipe and the second pipe through the first main pipe. The first main pipe is equipped with a flow detection device 17 and a sixth shut-off valve 36. The sixth shut-off valve 36 is downstream of the flow detection device 17. The first pipe is equipped with a seventh shut-off valve 37, and the second pipe is equipped with an eighth shut-off valve 38.

[0098] Maintaining the fluid medium in a laminar flow and high-temperature state helps reduce experimental uncertainty and improve the accuracy of corrosion reaction rate fitting.

[0099] The graphite oxidation corrosion test rig in this embodiment relates to a test rig design for measuring the high-temperature oxidation corrosion reaction rate of nuclear graphite with oxygen based on the gas concentration method, and more particularly to a test rig design for measuring the high-temperature oxidation corrosion reaction rate of the test fluid medium in a laminar flow state at high flow rates (<7.5m / s).

[0100] To achieve high flow rates, the graphite oxidation corrosion test bench based on the gas concentration method in this embodiment needs to solve the following problems:

[0101] 1. The highest temperature required for the graphite oxidation and corrosion reaction can reach 1100℃, but it is difficult to ensure that the target temperature is reached under high flow rate conditions.

[0102] 2. At higher flow rates, the air-cooled flow within the heating container changes from laminar to turbulent, which can negatively impact the accuracy of corrosion reaction processes and corrosion kinetic simulations. Ideally, high-temperature, high-flow-rate graphite oxidation corrosion tests should be conducted in a laminar flow state. This patented solution, through the design of the heating container, enables high-temperature graphite oxidation corrosion tests to be conducted while maintaining a laminar flow state at flow rates <7.5 m / s.

[0103] 3. The heating container for graphite sample 3 in this design is a vertical graphite furnace 15, i.e., a vertical heating furnace. The traditional methods for fixing it are suspension or clamping at both ends. Suspension makes it difficult to ensure the sample's positional stability under high flow rates; clamping at both ends does not meet the fluid channel design requirements of the heating container in this patent design. Therefore, the positioning mechanism for graphite sample 3 in the tubular graphite furnace 15 needs to be redesigned.

[0104] This technical solution involves three aspects: overall design, design of the 15-chamber tubular graphite furnace, and compatibility design of the graphite sample clamp function.

[0105] (1) Overall Design

[0106] Graphite oxidation corrosion test bench (see) Figure 3The test bench includes two gas inlet passages: a He gas passage and an oxygen gas passage. The He gas passage and the oxygen gas passage are supplied with gas and pressure by two parallel He gas cylinders and two parallel oxygen cylinders, respectively. Pressure reducing valves are installed at the cylinder outlets to ensure stable gas pressure in the passages. Each of the two gas inlet passages is equipped with a mass flow controller 25 to control the flow rate of helium and oxygen.

[0107] Two air inlet passages converge and flow into the mixing container 14, which mixes multiple gases and provides gas preheating. The mixing container 14 is equipped with several thermocouples for temperature monitoring and a pressure sensor. The mixing container 14 can heat the gas to 700°C. The rear end of the mixing container 14 is connected to a vertical tubular graphite furnace 15. The pipeline between the mixing container 14 and the tubular graphite furnace 15 is insulated and heat-traced to limit heat loss during gas flow.

[0108] The tubular graphite furnace 15 is used to provide the oxidation and corrosion temperature environment for graphite samples. Several sets of thermocouples are installed for temperature monitoring, and a pressure relief valve 27 is installed to automatically release pressure when the pressure is too high to ensure the safety of the furnace. When the tubular graphite furnace 15 is introduced with a test medium gas at a flow rate of less than 7.5 m / s and a temperature of 600°C or higher, it can heat the sample to 1100°C.

[0109] After the tubular graphite furnace 15 is connected to the cooling device 16, flow meter, and other equipment in sequence at its rear end, one passage leads to the gas chromatograph and then discharges to the tail gas treatment device 35, while the other passage directly discharges the gas to the tail gas treatment device 35. The cooling device 16 is used to cool the high-temperature gas discharged from the tubular graphite furnace 15 to below 300°C to ensure the stable function of the flow meter.

[0110] The total flow rate of gas generated per unit time can be measured by a flow meter at the rear end of the tubular graphite furnace 15; the proportions of CO and CO2 generated at the corresponding flow rate can be measured by a gas chromatograph. Using the total flow rate and component proportions, the mass of graphite consumed per unit time can be calculated, thus determining the corrosion reaction rate.

[0111] In terms of the control system, the instrument control signals of the mixing container 14, the tubular graphite furnace 15, the mass flow controller 25, the thermocouple, the pressure sensor, the pressure relief valve 27, and the flow meter are all connected to the programmable logic controller 25, and finally the instruments are controlled and the data is read through the computer terminal 26.

[0112] (2) Temperature of high-velocity gas

[0113] Under high flow rate conditions, heat is dissipated quickly in the tube furnace, making it difficult to reach the target temperature using only the tube graphite furnace 15. Therefore, a mixing container 14 is added to preheat the fluid. The mixing container 14 heats the gas to 700°C. The mixing container 14 is connected to the tube graphite furnace 15 by a metal pipe, with insulation and heat tracing devices added to the outside of the metal pipe to limit temperature drop during gas flow. Finally, the high-temperature fluid is introduced into the tube graphite furnace 15 to react with the graphite sample 3 in a corrosion reaction.

[0114] This design enables the sample temperature in the corrosion reaction zone to reach over 1100℃ at a flow rate of <7.5m / s.

[0115] (3) Tubular graphite furnace 15 furnace chamber design

[0116] When fluid flows through the furnace chamber 15 of the tubular graphite furnace, once the flow velocity exceeds a critical value, the high-speed fluid will change from a laminar flow state to a turbulent flow state. The turbulent flow state is not conducive to the simulation of subsequent corrosion kinetics and the analysis of corrosion reaction rates. Therefore, the furnace chamber designed in this patent can ensure that a laminar flow state is maintained within the flow velocity range of <7.5m / s.

[0117] See the schematic diagram of the furnace structure. Figure 2 The inner diameter of the furnace body and furnace chamber is 26–41 mm, the diameter of graphite sample 3 and the graphite sample holder is 21–30 mm, and the length of the graphite sample holder is 100–300 mm; the total length of the furnace body and furnace chamber is 400–600 mm. The graphite sample holder is made of quartz or alumina. The lower part of the furnace body and furnace chamber has a conical air inlet channel, and the upper part has a cylindrical channel. The graphite sample holder is installed in the middle of the furnace chamber to fix the graphite sample 3. The graphite sample holder is made of alumina or other corrosion-resistant and high-temperature resistant ceramic material. The upper part of the graphite sample holder is cylindrical, and the lower part is a conical guide head. The conical guide head of the graphite sample holder cooperates with the conical air inlet channel in the lower part of the furnace chamber to ensure that the gas can be relatively uniformly distributed on the cylindrical surface formed by the graphite sample holder and graphite sample 3. Through demonstration, it has been determined that the furnace body and furnace chamber can ensure that the fluid is laminar in the flow velocity range of <7.5 m / s.

[0118] (4) Graphite sample fixture design

[0119] The design of the graphite sample holder must meet requirements such as being detachable and not affecting the air intake channel. See the part drawings for the graphite sample holder. Figure 1 To avoid affecting the airflow channels in the furnace chamber, connector 7 is a metal connecting rod. The graphite sample holder is fixed to the top of the furnace chamber by the upper metal connecting rod. The metal connecting rod is located in the non-heated zone at the top of the furnace chamber, where the temperature is lower, thus meeting the high-temperature resistance requirements of the metal. The upper part of the metal connecting rod is fixed to the top cover of the furnace chamber, and the lower part is threaded into the groove 39 on the top of the graphite sample holder, facilitating installation and disassembly.

[0120] The graphite sample holder is made of alumina and can be disassembled into two parts, upper and lower. Specifically, in this embodiment, the upper part has an integrally machined connecting tenon, which is threadedly connected to the tenon hole of the lower part. The cylindrical graphite sample 3 has a through hole along its central axis of symmetry. It is assembled with the connecting tenon through the through hole, and then the upper and lower parts are tightened together by screwing the tenon threads to fix the graphite sample 3.

[0121] After the graphite sample holder is assembled into one piece, the installation, fixing and removal of the graphite sample holder and the graphite sample 3 held therein can be completed by operating the top cover of the furnace body.

[0122] Effect

[0123] 1. A test bench for measuring the oxidation and corrosion reaction rate of graphite based on the gas concentration method was designed. The bench can realize the oxidation and corrosion reaction of graphite and oxygen at high temperature and high flow rate by controlling the flow rate and velocity of helium and oxygen and mixing and preheating. The corrosion reaction rate is measured by a flow meter and a gas chromatograph.

[0124] 2. Through the design of preheating the mixing container 14 and heat tracing the pipeline, the fluid temperature and sample temperature in the corrosion reaction zone can reach above 1100℃ when the flow rate is <7.5m / s.

[0125] 3. Through the new design of the furnace inlet 10, sample clamps and furnace dimensions, it can be ensured that the fluid in the flow velocity range of <7.5m / s is laminar.

[0126] 4. A completely new sample fixture design was completed, which ensures convenient installation and disassembly under the new furnace design. The sample fixture can be disassembled into two parts, upper and lower, which are connected and fixed by a threaded connection between a tenon and a mortise. The tenon can both install and fix the graphite sample 3 with the center hole, and also allow for the assembly of the upper and lower parts of the fixture.

[0127] In this embodiment, the graphite sample holder, graphite furnace 15, and graphite oxidation corrosion test bench are designed with new heating containers and a new preheating container. These features enable fluid heating under high flow rate conditions, ensuring the ambient temperature required for the graphite oxidation corrosion reaction. Furthermore, the flow channel design keeps the high-speed fluid in a laminar state, reducing the impact of fluid instability factors on the measurement of corrosion kinetic parameters.

[0128] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A graphite furnace, characterized in that, include: The furnace body, a furnace cover mounted on the furnace body, a graphite sample holder located inside the furnace body, and a connector. The graphite sample holder includes a first clamping member and a second clamping member. The first clamping member includes a first clamping member body and a protrusion on the first clamping member body. A through hole is provided on the graphite sample. The second clamping member includes a second clamping member body and a recess on the second clamping member body. The protrusion of the first clamping member passes through the through hole of the graphite sample and enters the recess of the second clamping member for detachable connection. The graphite sample is clamped between the first clamping member body and the second clamping member body. The first clamping member is cylindrical, and the second clamping member is conical. One end of the connector is connected to the first clamping member body. A clamping component is connected, and the other end of the connector is connected to the furnace cover. A gap is left between the graphite sample holder and the furnace body / chamber for gas flow. The furnace body / chamber includes a first furnace body / chamber and a second furnace body / chamber. One end of the first furnace body / chamber is connected to the second furnace body / chamber. The first furnace body / chamber is cylindrical, and the second furnace body / chamber is conical. An air inlet is provided at the conical tip of the second furnace body / chamber for gas guidance. An air outlet is provided at the other end of the first furnace body / chamber. The first clamping component is located inside the first furnace body / chamber, and the second clamping component is located inside the second furnace body / chamber. The shape of the furnace body / chamber is adapted to the shape of the graphite sample holder.

2. The graphite furnace according to claim 1, characterized in that, The first clamping member has a groove, and the connecting member is connected to the groove on the first clamping member by a thread.

3. The graphite furnace according to claim 1, characterized in that, The inner diameter of the furnace body and furnace chamber is 26~41mm; The diameter of the graphite sample is the same as the diameter of the graphite sample holder, and the diameter of the graphite sample and the graphite sample holder is 21~30mm. The length of the graphite sample holder is 100~300mm; The total length of the furnace body and furnace chamber is 400~600mm.

4. The graphite furnace according to claim 1, characterized in that, The protrusion of the first clamping member and the recess of the second clamping member are connected by threads.

5. The graphite furnace according to claim 1, characterized in that, The graphite sample holder is made of quartz or alumina.

6. A graphite oxidation corrosion test bench, characterized in that, include: Helium storage tanks are used to store helium. Oxygen storage tanks are used to store oxygen. A mixing container is connected to a helium storage tank and an oxygen storage tank, respectively. The mixing container is used to mix helium and oxygen and preheat them. A graphite furnace, as described in any one of claims 1 to 5, is connected to a mixing container. The graphite furnace is used to heat the materials inside. An oxygen corrosion test is conducted on the graphite inside the graphite furnace, and the graphite reacts with oxygen to generate carbon monoxide and carbon dioxide. A cooling device, connected to a graphite furnace, is used to cool the material flowing out of the graphite furnace. A flow detection device, connected to the cooling device, is used to detect the flow rate of the gas at the outlet of the cooling device. A gas detection device is connected to a flow detection device. The gas detection device is used to measure the proportion of carbon monoxide and carbon dioxide generated at the corresponding flow rate. By calculating the total flow rate and the proportion of components, the mass of graphite consumed per unit time is obtained, and the graphite oxidation and corrosion reaction rate is obtained.

7. The graphite oxidation corrosion test rig according to claim 6, characterized in that, Also includes: The first mass flow controller is installed on the connecting pipe between the helium storage tank and the mixing container. The first mass flow controller is used to control the mass flow rate of the helium gas introduced into the mixing container and send it to the controller. The second mass flow controller is installed on the connecting pipe between the oxygen storage tank and the mixing container. The second mass flow controller is used to control the mass flow rate of oxygen introduced into the mixing container and send it to the controller. A first temperature detection device is installed on the mixing container. The first temperature detection device is used to detect the temperature inside the mixing container and send it to the controller. A first pressure detection device is installed on the mixing container. The first pressure detection device is used to detect the pressure inside the mixing container and send it to the controller. The second temperature detection device is installed on the graphite furnace. The second temperature detection device is used to detect the temperature inside the graphite furnace and send it to the controller. The second pressure detection device is installed on the graphite furnace. The second pressure detection device is used to detect the pressure inside the graphite furnace and send it to the controller. The controller is connected to a gas detection device. The gas detection device measures the proportion of carbon monoxide and carbon dioxide generated at the corresponding flow rate and sends it to the controller. The controller calculates the mass of graphite consumed per unit time based on the total flow rate and the proportion of components, and thus obtains the graphite oxidation and corrosion reaction rate.

Images