CN116465819A - Graphite sample fixture, graphite furnace, graphite oxidation corrosion test bench - Google Patents

Abstract

The invention discloses a graphite sample fixture, a graphite furnace, and a graphite oxidation corrosion test bench. The graphite sample fixture includes: a first clamping part and a second clamping part. The first clamping part includes a first clamping part body and a convex part arranged on the first clamping part body. The graphite sample is provided with a through hole. The second clamping part includes a second clamping part body and a concave part arranged on the second clamping part body. Between the clip body and the second clip body. The present invention adopts a new design of a heating container and a newly added design of a pre-heating container, which can realize fluid heating under high flow rate conditions, ensure the ambient temperature required for graphite oxidation and corrosion reactions, and maintain the high-speed fluid in a laminar flow state through the flow channel design, so as to reduce the influence of fluid instability factors on the measurement of corrosion kinetic parameters.

Description

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

technical field

The invention belongs to the technical field of graphite oxidation corrosion, and in particular relates to a graphite sample fixture, a graphite furnace and a graphite oxidation corrosion test stand.

Background technique

High-temperature gas-cooled reactors use nuclear graphite as the structural material and moderator material of the core, and helium as the coolant. Helium is an inert gas and will not chemically react with graphite.

However, under high temperature conditions, oxygen will react with graphite materials as follows:

1/2O ₂ +C=CO, ΔΗ=-110.5kJ/mol

(1)

O ₂ +C=CO ₂ ,ΔΗ=-393.5kJ/mol

(2)

1/2O ₂ +CO=CO ₂ ,ΔΗ=-283.0kJ/mol

(3)

The above chemical reactions will affect the performance of graphite components in the core, and then affect the service life and operation safety of graphite components. Once an air intake accident occurs, graphite is easily corroded rapidly, resulting in rapid failure of graphite components, which may lead to more serious consequences. Therefore, the experimental measurement of the corrosion rate of graphite materials 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 respond to sudden accidents.

The methods for measuring the oxidation corrosion reaction rate of nuclear graphite mainly include gas concentration method and thermogravimetric method. The basic principle of measuring the corrosion reaction rate of graphite by the gas concentration method is: mix oxygen and helium (or other inert gases) in a certain proportion, and pass it into a heating furnace equipped with graphite samples. The heating furnace provides a high-temperature environment to make oxygen react with graphite. The generated gas is discharged from the tubular graphite furnace and then passed into the measuring instrument for composition measurement. The rate of graphite oxidation corrosion reaction can be calculated by measuring the consumption of oxygen before and after corrosion, or measuring the mass of CO and CO ₂ produced by gas.

At present, this type of bench design 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 at higher flow rates.

Contents of the invention

The technical problem to be solved by the present invention is to provide a graphite sample fixture, a graphite furnace, and a graphite oxidation corrosion test bench for the above-mentioned deficiencies in the prior art, which can realize fluid heating under high flow rate conditions and ensure the ambient temperature required for the graphite oxidation corrosion reaction.

The technical solution adopted to solve the technical problem of the present invention is to provide a graphite sample clamp, comprising: a first clamping piece, a second clamping piece, the first clamping piece includes a first clamping piece body, a convex portion arranged on the first clamping piece body, a through hole is arranged on the graphite sample, the second clamping piece includes a second clamping piece body, a concave portion arranged on the second clamping piece body, the convex portion of the first clamping piece passes through the through hole of the graphite sample and enters the concave portion of the second clamping piece to be detachably connected, and the graphite test is clamped between the first clamping piece body and the concave portion of the second clamping piece body. Between the second clamp body.

Preferably, the convex part of the first clamping part is connected with the concave part of the second clamping part through thread.

Preferably, the first clamping part is cylindrical, and the second clamping part is conical.

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

The present invention also provides a graphite furnace, comprising: a furnace body, a furnace cover arranged on the furnace body, the above-mentioned graphite sample fixture located in the furnace body, and a connecting piece, one end of the connecting piece is connected to the first clamping piece, the other end of the connecting piece is connected to the furnace cover, and there is a gap between the graphite sample fixture and the furnace hearth, and the gap is used for gas flow.

Preferably, a groove is provided on the first clamping piece, and the connecting piece is screwed into the groove on the first clamping piece.

Preferably, the graphite sample fixture is the above-mentioned graphite sample fixture, the furnace body furnace includes a first furnace body furnace hearth and a second furnace body furnace hearth, one end of the first furnace body furnace hearth is connected with the second furnace body furnace hearth, the first furnace body furnace hearth is cylindrical, the second furnace body furnace hearth is conical, the conical tip of the second furnace body furnace hearth is provided with an air inlet, the second furnace body furnace hearth is used for gas diversion, the other end of the first furnace body furnace hearth is provided with an air outlet, the first clamping piece is arranged in the first furnace body furnace hearth, the second The clamping piece is located in the hearth of the second furnace body, and the shape of the hearth of the furnace body matches the shape of the graphite sample holder.

Preferably, the inner diameter of the hearth of the furnace body is 26-41mm;

The diameter of the graphite sample is the same as that 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 fixture is 100-300mm;

The total length of the furnace body and hearth is 400-600mm.

The present invention also provides a graphite oxidation corrosion test bench, comprising:

Helium storage tanks for storing helium;

Oxygen storage tanks for storing oxygen;

The mixing container is connected to the helium storage tank and the oxygen storage tank respectively, and the mixing container is used for mixing helium and oxygen and preheating;

Graphite furnace, connected with the mixing container, is used to heat the material in the graphite furnace, and the oxygen in the graphite furnace conducts corrosion test on graphite, and graphite reacts with oxygen to generate carbon monoxide and carbon dioxide;

The cooling device is connected with the graphite furnace, and the cooling device is used to cool the material flowing out of the graphite furnace;

The flow detection device is connected with the cooling device, and the flow detection device is used to detect the flow rate of the gas at the outlet of the cooling device;

The gas detection device is connected to the flow detection device. The gas detection device is used to measure the proportion of carbon monoxide and carbon dioxide produced under the corresponding flow rate. Through the total flow rate and the proportion of components, the mass of graphite consumed per unit time is calculated, and the reaction rate of graphite oxidation and corrosion is obtained.

Preferably, the graphite oxidation corrosion test bench also includes:

The first mass flow controller is arranged on the connecting pipeline between the helium storage tank and the mixing container, and the first mass flow controller is used to control the mass flow of helium passing into the mixing container and send it to the controller;

The second mass flow controller is arranged on the connection pipeline between the oxygen storage tank and the mixing container, and the second mass flow controller is used to control the mass flow of oxygen passing into the mixing container and send it to the controller;

The first temperature detection device is arranged on the mixing container, and the first temperature detection device is used to detect the temperature in the mixing container and send it to the controller;

The first pressure detection device is arranged on the mixing container, and the first pressure detection device is used to detect the pressure in the mixing container and send it to the controller;

The second temperature detection device is arranged on the graphite furnace, and the second temperature detection device is used to detect the temperature in the graphite furnace and send it to the controller;

The second pressure detection device is arranged on the graphite furnace, and the second pressure detection device is used to detect the pressure in the graphite furnace and send it to the controller;

The controller and the gas detection device are connected to the controller. The gas detection device measures the proportion of carbon monoxide and carbon dioxide produced under the corresponding flow rate and sends it to the controller. The controller calculates the mass of graphite consumption per unit time through the total flow rate and the composition ratio, and obtains the graphite oxidation corrosion reaction rate.

The graphite sample fixture, graphite furnace, and graphite oxidation corrosion test bench in the present invention are designed with a new heating container and a new preheating container design, which can realize fluid heating under high flow rate conditions, ensure the ambient temperature required for graphite oxidation corrosion reaction, and maintain a laminar flow state for high-speed fluid through flow channel design, so as to reduce the influence of fluid instability factors on the measurement of corrosion kinetic parameters.

Description of drawings

Fig. 1 is the structural representation of the graphite sample fixture in the embodiment of the present invention 2;

Fig. 2 is the structural representation of the graphite furnace in the embodiment of the present invention 2;

3 is a schematic structural view of the graphite oxidation corrosion test bench in Example 2 of the present invention.

In the figure: 1-first clamp body; 2-convex part; 3-graphite sample; 4-second clamp body; 5-recess; 6-furnace cover; 7-connector; 8-first furnace hearth; -first mass flow controller; 20-second mass flow controller; 21-first temperature detection device; 22-first pressure detection device; 23-second temperature detection device; 24-second pressure detection device; 25-controller; 26-computer; 27-pressure relief valve; 28-first pressure reducing valve; The sixth shut-off valve; 37-the seventh shut-off valve; 38-the eighth shut-off valve; 39-groove.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiments of the present patent are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are only used for explaining the patent, and should not be construed as limiting the patent.

In the description of this patent, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and so on are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this patent and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as a limitation of this patent.

In the description of this patent, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", "connection" and "arrangement" should be understood in a broad sense, for example, it can be fixedly connected or arranged, or it can be detachably connected and arranged, or integrally connected and arranged. Those of ordinary skill in the art can understand the specific meanings of the above terms in this patent according to specific situations.

Example 1

This embodiment provides a graphite sample fixture, comprising: a first clamping piece and a second clamping piece. The first clamping piece includes a first clamping piece body and a convex portion arranged on the first clamping piece body. The graphite sample is provided with a through hole. The second clamping piece includes a second clamping piece body and a concave portion arranged on the second clamping piece body.

The present embodiment also provides a graphite furnace, comprising: a furnace body, a furnace cover arranged on the furnace body, the above-mentioned graphite sample fixture located in the furnace body, and a connecting piece, one end of the connecting piece is connected to the first clamping piece, the other end of the connecting piece is connected to the furnace cover, and there is a gap between the graphite sample fixture and the furnace hearth, and the gap is used for gas flow.

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

Helium storage tanks for storing helium;

Oxygen storage tanks for storing oxygen;

The mixing container is connected to the helium storage tank and the oxygen storage tank respectively, and the mixing container is used for mixing helium and oxygen and preheating;

Graphite furnace, connected with the mixing container, is used to heat the material in the graphite furnace, and the oxygen in the graphite furnace conducts corrosion test on graphite, and graphite reacts with oxygen to generate carbon monoxide and carbon dioxide;

The cooling device is connected with the graphite furnace, and the cooling device is used to cool the material flowing out of the graphite furnace;

The flow detection device is connected with the cooling device, and the flow detection device is used to detect the flow rate of the gas at the outlet of the cooling device;

The gas detection device is connected to the flow detection device. The gas detection device is used to measure the proportion of carbon monoxide and carbon dioxide produced under the corresponding flow rate. Through the total flow rate and the proportion of components, the mass of graphite consumed per unit time is calculated, and the reaction rate of graphite oxidation and corrosion is obtained.

The graphite sample fixture, graphite furnace, and graphite oxidation corrosion test bench in this embodiment are designed with a new heating container and a new preheating container design, which can realize fluid heating under high flow rate conditions, ensure the ambient temperature required for graphite oxidation corrosion reaction, and keep the high-speed fluid in a state of laminar flow through the design of the flow channel, so as to reduce the influence of fluid instability factors on the measurement of corrosion kinetic parameters.

Example 2

As shown in Figure 1, the present embodiment provides a graphite sample fixture, comprising: a first clamping piece, a second clamping piece, the first clamping piece includes a first clamping piece body 1, a convex portion 2 arranged on the first clamping piece body 1, a through hole is provided on the graphite sample 3, the second clamping piece includes a second clamping piece body 4, a concave portion 5 arranged on the second clamping piece body 4, the convex portion 2 of the first clamping piece passes through the through hole of the graphite sample 3 and enters the concave portion 5 of the second clamping piece, and is detachably connected to the first clamping piece. Between the clip body 1 and the second clip body 4 . Specifically, in this embodiment, the convex portion 2 on the first clamp body 1 is a tenon, and the concave portion 5 on the second clamp body 4 is a tenon hole. Specifically, the graphite sample 3 in this embodiment has a through hole along the central axis of symmetry.

Preferably, the convex part 2 of the first clamping part is connected with the concave part 5 of the second clamping part through threads.

Preferably, the first clamping part is cylindrical, and the second clamping part is conical.

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

As shown in Figure 2, the present embodiment also provides a kind of graphite furnace 15, comprises: furnace body, be arranged on the furnace cover 6 on the furnace body, be positioned at the above-mentioned graphite sample holder in the furnace body, connector 7, one end of connector 7 is connected with the first holder, the other end of connector 7 is connected with furnace cover 6, graphite sample holder and body of furnace hearth leave gap, and this gap is used for gas flow.

Specifically, the connecting piece 7 in this embodiment is a metal connecting rod.

Preferably, a groove 39 is provided on the first clamping piece, and the connecting piece 7 is screwed to the groove 39 on the first clamping piece.

Preferably, the graphite sample fixture is the above-mentioned graphite sample fixture, and the furnace body furnace includes a first furnace body furnace hearth 8 and a second furnace body furnace hearth 9. One end of the first furnace body furnace hearth 8 is connected with the second furnace body furnace hearth 9. The first furnace body furnace hearth 8 is cylindrical, the second furnace body furnace hearth 9 is conical, and the conical tip of the second furnace body furnace hearth 9 is provided with an air inlet 10. The second furnace body furnace hearth 9 is used for gas diversion. The clamping piece is arranged in the first furnace hearth 8, the second clamping piece is located in the second furnace hearth 9, and the shape of the furnace hearth matches the shape of the graphite sample holder.

Preferably, the inner diameter of the hearth of the furnace body is 26-41mm;

The diameter of the graphite sample 3 is the same as that of the graphite sample holder, and the diameters of the graphite sample 3 and the graphite sample holder are 21-30mm;

The length of the graphite sample fixture is 100-300mm;

The total length of the furnace body and hearth is 400-600mm.

As shown in Figure 3, the present embodiment also provides a graphite oxidation corrosion test bench, including:

Helium storage tank 12, used for storing helium;

Oxygen storage tank 13, used for storing oxygen;

Mixing container 14 is connected with helium storage tank 12 and oxygen storage tank 13 respectively, and mixing container 14 is used for mixing helium and oxygen and preheating;

Graphite furnace 15 is connected with mixing container 14, and is used for heating material in it in graphite furnace 15, and oxygen carries out corrosion test for graphite in graphite furnace 15, and graphite and oxygen reaction generate carbon monoxide, carbon dioxide;

Cooling device 16 is connected with graphite furnace 15, and cooling device 16 is used for cooling the material that graphite furnace 15 flows out;

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

The gas detection device 18 is connected with the flow detection device 17, and the gas detection device 18 is used to measure the ratio of the generated products carbon monoxide and carbon dioxide under the corresponding flow rate. Through the total flow rate and the composition ratio, the mass of graphite consumption per unit time is calculated, and the graphite oxidation corrosion reaction rate is obtained. Specifically, the gas detection device 18 in this embodiment is a gas chromatograph.

Preferably, the graphite oxidation corrosion test bench also includes:

The first mass flow controller 19 is arranged on the connection pipeline between the helium storage tank 12 and the mixing container 14, the first mass flow controller 19 is used to control the mass flow of helium passing into the mixing container 14 and sends it to the controller 25;

The second mass flow controller 20 is arranged on the connecting pipeline between the oxygen storage tank 13 and the mixing container 14, and the second mass flow controller 20 is used to control the mass flow of oxygen passing into the mixing container 14 and send it to the controller 25;

The first temperature detection device 21 is arranged on the mixing container 14, and the first temperature detection device 21 is used to detect the temperature in the mixing container 14 and send it to the controller 25; specifically, the first temperature detection device 21 in this embodiment is a first thermocouple.

The first pressure detection device 22 is arranged on the mixing container 14, and the first pressure detection device 22 is used to detect the pressure in the mixing container 14 and send it to the controller 25; specifically, the first pressure detection device 22 in this embodiment is a first pressure sensor, and the second pressure detection device 24 is a second pressure sensor

The second temperature detection device 23 is arranged on the graphite furnace 15, and the second temperature detection device 23 is used to detect the temperature in the graphite furnace 15 and sends it to the controller 25; specifically, the second temperature detection device 23 in the present embodiment is a second thermocouple.

The second pressure detection device 24 is arranged on the graphite furnace 15, and the second pressure detection device 24 is used to detect the pressure in the graphite furnace 15 and sends it to the controller 25;

The controller 25 and the gas detection device 18 are connected to the controller 25. The gas detection device 18 measures the ratio of the generated products carbon monoxide and carbon dioxide at the corresponding flow rate and sends it to the controller 25. The controller 25 calculates the mass of graphite consumed per unit time through the total flow rate and the composition ratio, and obtains the graphite oxidation corrosion reaction rate. Specifically, the controller 25 is a programmable logic controller, and finally controls the instrumentation and reads data through the terminal of the computer 26 .

The tubular graphite furnace 15 is provided with a pressure relief valve 27 .

Specifically, a first decompression valve 28 , a first shut-off valve 29 , and a second shut-off valve 30 are provided on the connecting pipeline between the helium storage tank 12 and the mixing container 14 . There are two helium gas storage tanks 12, and a first decompression valve 28 and a first shut-off valve 29 are respectively arranged on the helium gas branch pipeline.

The first stop valve 29 is arranged downstream of the first pressure reducing valve 28, the two helium branch pipelines are merged into a helium main pipe, the second stop valve 30 is arranged on the helium main pipe, the first mass flow controller 19 is arranged downstream of the first stop valve 29, and the second stop valve 30 is arranged upstream of the first mass flow controller 19.

Specifically, a second decompression valve 31 , a third cut-off valve 32 , and a fourth cut-off valve 33 are provided 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 provided with a second pressure reducing valve 31 and a third shut-off valve 32,

The third cut-off valve 32 is arranged downstream of the second decompression valve 31, and the two oxygen branch pipelines are merged into an oxygen main pipe. The fourth cut-off valve 33 is arranged on the oxygen main pipe.

The helium main pipe and the oxygen main pipe are merged into a main main pipe, on which a fifth cut-off valve 34 is arranged, and the main main pipe is connected with the mixing container 14 .

The cooling device 16 is connected to the gas detection device 18 through the first pipeline, the cooling device 16 is connected to the tail gas treatment device 35 through the second pipeline, and the cooling device 16 is respectively connected to the first pipeline and the second pipeline through the first main pipe. The first main pipe is provided with a flow detection device 17 and a sixth stop valve 36. The sixth stop valve 36 is downstream of the flow detection device 17. The first pipe is provided with a seventh stop valve 37, and the second pipe is provided with an eighth stop valve 38.

The fluid medium is kept in laminar flow and high temperature state, which is beneficial to reduce the uncertainty of the test and improve the accuracy of corrosion reaction rate fitting.

The graphite oxidation corrosion test bench in this embodiment relates to a test bench design for measuring the high temperature oxidation corrosion reaction rate of nuclear graphite and oxygen based on the gas concentration method, and in particular relates to a test bench design for measuring the high temperature oxidation corrosion reaction rate of a test fluid medium in a laminar flow state at a high flow rate (<7.5m/s).

In this embodiment, the graphite oxidation corrosion test bench based on the gas concentration method needs to solve the following problems in order to achieve a high flow rate:

1. The maximum temperature required for graphite oxidation and corrosion reaction can reach 1100°C, but it is difficult to ensure heating to the target temperature under high flow rate conditions.

2. At a higher flow rate, the air cooling will change from a laminar flow state to a turbulent flow state in the heating container, which will have a certain impact on the accuracy of the corrosion reaction process and corrosion kinetic simulation. Ideally, the graphite oxidation corrosion test at high temperature and high flow rate is completed in a laminar flow state. Through the design of the heating vessel, this patent solution realizes the high-temperature graphite oxidation corrosion test in which the fluid remains in a laminar flow state under the condition of flow velocity <7.5m/s.

3. The heating container where the graphite sample 3 is located in this scheme is a vertical graphite furnace 15, that is, a vertical heating furnace, and the traditional way of fixing it is a hanging type or a compression type at both ends. The hanging type is difficult to ensure the stable position of the sample under the condition of high flow rate; the way of pressing the upper and lower ends cannot meet the fluid channel design of the heating vessel in this patent solution. The graphite sample 3 positioning mechanism in the tubular graphite furnace 15 needs to be redesigned.

The technical proposal involves three aspects: the overall design, the furnace design of the tubular graphite furnace 15, and the compatibility design of the graphite sample fixture function.

(1) Overall design

The graphite oxidation corrosion test bench is shown in Figure 3. The gantry contains 2 air intake passages including a He gas passage and an oxygen passage. The He gas passage and the oxygen passage are respectively provided with gas source and pressure by two parallel He gas cylinders and oxygen cylinders, and a pressure reducing valve is installed at the outlet of the gas cylinder to ensure the stability of the passage gas pressure. A mass flow controller 25 is installed on each of the two intake passages for controlling the flow of helium and oxygen.

The two air intake passages merge into the mixing container 14, and the function of the mixing container 14 is to mix various gases and provide gas preheating. The mixing container 14 is provided with several sets of thermocouples for temperature monitoring, and a set of pressure sensors. The mixing vessel 14 can heat the gas to 700°C. The rear end of the mixing vessel 14 is connected to a vertical tubular graphite furnace 15, and the pipeline between the mixing vessel 14 and the tubular graphite furnace 15 is equipped with insulation and heat tracing to limit the heat loss during the gas flow.

The tubular graphite furnace 15 is used to provide an oxidation and corrosion temperature environment for graphite samples. Several sets of thermocouples are set for temperature monitoring, and a set of pressure relief valves 27 are set to automatically release pressure when the pressure is too high to ensure the safety of the furnace. The tubular graphite furnace 15 can heat the sample to 1100°C when the test medium gas with a flow rate of less than 7.5m/s and above 600°C is passed through.

After the back end of the tubular graphite furnace 15 is connected to the cooling device 16, flowmeter and other equipment in sequence, one path is connected to the gas chromatograph and then discharged to the tail gas treatment device 35, and the other path directly discharges the gas to the tail gas treatment device 35. The cooling device 16 is used to cool down the high-temperature gas discharged from the tubular graphite furnace 15 to within 300° C., so as to ensure the stable function of the flowmeter.

Through the flow meter at the back end of the tubular graphite furnace 15, the total flow rate of the generated gas per unit time can be measured; through the gas chromatograph, the proportion of the generated products CO and _CO under the corresponding flow rate can be measured. Through the total flow rate and composition ratio, the mass of graphite consumed per unit time can be calculated, that is, the corrosion reaction rate can be obtained.

In terms of the control system, the instrument control signals of the mixing vessel 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 instrument control and data reading are performed through the computer 26 terminal.

(2) Gas temperature at high flow rate

Under the condition of high flow rate, the heat in the tube furnace is exported quickly, and it is difficult to reach the target temperature by using the tube type graphite furnace 15 alone. The mixing vessel 14 is therefore added to preheat the fluid. The mixing vessel 14 heats the gas to 700°C. The mixing container 14 and the tubular graphite furnace 15 are connected by metal tubes, and thermal insulation and heat tracing devices are added outside the metal tubes to limit the temperature drop during gas circulation. Finally, the high-temperature fluid enters the tubular graphite furnace 15 to react with the graphite sample 3 for corrosion.

With this design, when the flow rate is <7.5m/s, the temperature of the sample in the corrosion reaction zone can reach above 1100°C

(3) 15 furnace design of tubular graphite furnace

When the fluid flows through the hearth of the tubular graphite furnace 15, when the flow velocity is higher than the critical value, the high-speed fluid will change from a laminar flow state to a turbulent flow state. The turbulent flow state of the fluid is not conducive to the simulation of the subsequent corrosion kinetic process and the analysis of the corrosion reaction rate. Therefore, the furnace designed by this patent can ensure that the laminar flow state can be maintained within the range of flow velocity <7.5m/s.

The schematic diagram of the furnace structure is shown in Figure 2. The inner diameter of the furnace body hearth is 26-41mm, the diameter of the graphite sample 3 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 hearth is 400-600mm. The graphite sample fixture is made of quartz or alumina material. The lower part of the furnace body is a conical air inlet channel, and the upper part is a cylindrical channel. A graphite sample fixture is installed in the middle of the furnace to fix the graphite sample 3, and the graphite sample fixture is made of alumina or other corrosion-resistant and high-temperature resistant ceramic materials. The upper part of the graphite sample fixture is a cylinder, and the lower part is a conical diversion head. The conical diversion head of the graphite sample holder cooperates with the conical air inlet channel at the lower part of the furnace to ensure that the gas can be relatively uniformly distributed on the surface of the cylinder formed by flowing through the graphite sample holder and the graphite sample 3 . It is determined by demonstration that the furnace chamber of the furnace body can ensure that the fluid in the range of flow velocity <7.5m/s is laminar flow.

(4) Graphite sample fixture design

The design of the graphite sample fixture needs to meet the requirements of being detachable and not affecting the air intake channel. The parts diagram of the graphite sample fixture is shown in Figure 1. In order not to affect the inlet flow path of the furnace body furnace, the connecting piece 7 is a metal connecting rod, and the graphite sample fixture is fixed on the top of the furnace body furnace by means of the upper metal connecting rod. The metal connecting rod is located in the non-heating area on the upper part of the furnace, and the temperature is relatively low, which can meet the high temperature resistance performance requirements of the metal. The upper part of the metal connecting rod is fixed with the top cover of the furnace body furnace, and the lower part is threadedly connected with the groove 39 on the top of the graphite sample fixture, which is convenient for installation and disassembly.

The graphite sample fixture is made of alumina material and can be split into upper and lower parts. Specifically, in this embodiment, the upper part has an integrally processed connecting tenon, and the tenon is connected with the screw thread of the tenon hole of the lower part. The cylindrical graphite sample 3 is provided with a through hole along the central symmetry axis, assembled with the connecting tenon through the through hole, and then the upper and lower parts are screwed through the tenon to realize the fixation of the graphite sample 3.

After the graphite sample fixture is assembled into one body, the installation, fixing and unloading of the graphite sample fixture and the graphite sample 3 held in the furnace can be completed by operating the top cover of the furnace body furnace.

Effect

1. A graphite oxidation corrosion reaction rate measurement test bench based on the gas concentration method is designed. The bench can realize the oxidation corrosion reaction of graphite and oxygen at high temperature and high flow rate through the flow rate and flow rate control and mixed preheating of helium and oxygen, and complete the measurement of the corrosion reaction rate by flowmeter and gas chromatograph.

2. Through the design of preheating of the mixing vessel 14 and pipeline insulation and heat tracing, when the flow rate is less than 7.5m/s, the temperature of the fluid in the corrosion reaction zone and the temperature of the sample can reach above 1100°C.

3. Through the new design of furnace air inlet 10, sample fixture and furnace size, it can ensure that the fluid in the range of flow velocity <7.5m/s is laminar.

4. Complete the design of a new sample fixture, which can ensure convenient installation and disassembly under the new furnace design. The sample fixture can be divided into upper and lower parts, and the two parts are fixed through the threaded connection between the tenon and the tenon hole. The tenon can realize the installation and fixation of the graphite sample 3 with a central hole, and can realize the assembly of the upper and lower parts of the fixture.

The graphite sample fixture, graphite furnace 15, and graphite oxidation corrosion test bench in this embodiment are designed with a new heating container and a new pre-heating container design, which can realize fluid heating under high flow rate conditions, ensure the ambient temperature required for graphite oxidation corrosion reaction, and maintain a laminar state of high-speed fluid through flow channel design, so as to reduce the influence of fluid instability factors on the measurement of corrosion kinetic parameters.

It can be understood that, the above embodiments are only exemplary embodiments adopted for illustrating the principle of the present invention, but 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 regarded as the protection scope of the present invention.

Claims (10)

1. A graphite sample fixture, it is characterized in that, comprising: the first clamping part, the second clamping part, the first clamping part comprises the first clamping part body, the convex part that is arranged on the first clamping part body, the graphite sample is provided with through hole, the second clamping part comprises the second clamping part body, the concave part that is arranged on the second clamping part body, the convex part of the first clamping part passes the through hole of the graphite sample and enters the concave part of the second clamping part to be detachably connected with it, and the graphite test is clamped between the first clamping part body and the second clamping part body . 2 . The graphite sample holder according to claim 1 , wherein the convex part of the first clamping part is connected with the concave part of the second clamping part through threads. 3. The graphite sample holder according to claim 1, wherein the first clamping part is cylindrical, and the second clamping part is conical. 4. The graphite sample holder according to claim 1, wherein the material of the graphite sample holder is quartz or alumina. 5. a graphite furnace, it is characterized in that, comprises: body of heater, be arranged on the furnace cover on the body of heater, be positioned at the graphite sample fixture described in any one of claim 1～4 in the body of heater, connector, one end of connector is connected with the first clamping part, the other end of connector is connected with furnace cover, graphite sample holder and body of furnace hearth leave gap, and this gap is used for gas flow. 6 . The graphite furnace according to claim 5 , wherein a groove is provided on the first clamping piece, and the connecting piece is connected to the groove on the first clamping piece through threads. 7. graphite furnace according to claim 5, it is characterized in that, graphite sample fixture is the graphite sample fixture in claim 3, body of furnace hearth comprises the first body of furnace hearth, the second body of furnace hearth, one end of body of furnace hearth of the first body of furnace is connected with the hearth of the second body of furnace, the first body of furnace hearth is cylindrical, the hearth of the second body of furnace is conical, the conical tip of the body of furnace hearth of the second body of furnace is provided with air inlet, the hearth of the second body of furnace is used for gas diversion, the other end of the body of furnace hearth is provided with gas outlet, The first clamping part is arranged in the hearth of the first furnace body, the second clamping part is located in the hearth of the second furnace body, and the shape of the hearth of the furnace body matches the shape of the graphite sample holder. 8. graphite furnace according to claim 7, characterized in that, The inner diameter of the furnace chamber is 26-41mm; The diameter of the graphite sample is the same as that 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 fixture is 100-300mm; The total length of the furnace body and hearth is 400-600mm. 9. A graphite oxidation corrosion test bench, is characterized in that, comprises: Helium storage tanks for storing helium; Oxygen storage tanks for storing oxygen; The mixing container is connected to the helium storage tank and the oxygen storage tank respectively, and the mixing container is used for mixing helium and oxygen and preheating; Graphite furnace, connected with the mixing container, is used to heat the material in the graphite furnace, and the oxygen in the graphite furnace conducts corrosion test on graphite, and graphite reacts with oxygen to generate carbon monoxide and carbon dioxide; The cooling device is connected with the graphite furnace, and the cooling device is used to cool the material flowing out of the graphite furnace; The flow detection device is connected with the cooling device, and the flow detection device is used to detect the flow rate of the gas at the outlet of the cooling device; The gas detection device is connected to the flow detection device. The gas detection device is used to measure the proportion of carbon monoxide and carbon dioxide produced under the corresponding flow rate. Through the total flow rate and the proportion of components, the mass of graphite consumed per unit time is calculated, and the reaction rate of graphite oxidation and corrosion is obtained. 10. graphite oxidation corrosion test bench according to claim 9, is characterized in that, also comprises: The first mass flow controller is arranged on the connecting pipeline between the helium storage tank and the mixing container, and the first mass flow controller is used to control the mass flow of helium passing into the mixing container and send it to the controller; The second mass flow controller is arranged on the connection pipeline between the oxygen storage tank and the mixing container, and the second mass flow controller is used to control the mass flow of oxygen passing into the mixing container and send it to the controller; The first temperature detection device is arranged on the mixing container, and the first temperature detection device is used to detect the temperature in the mixing container and send it to the controller; The first pressure detection device is arranged on the mixing container, and the first pressure detection device is used to detect the pressure in the mixing container and send it to the controller; The second temperature detection device is arranged on the graphite furnace, and the second temperature detection device is used to detect the temperature in the graphite furnace and send it to the controller; The second pressure detection device is arranged on the graphite furnace, and the second pressure detection device is used to detect the pressure in the graphite furnace and send it to the controller; The controller and the gas detection device are connected to the controller. The gas detection device measures the proportion of carbon monoxide and carbon dioxide produced under the corresponding flow rate and sends it to the controller. The controller calculates the mass of graphite consumption per unit time through the total flow rate and the composition ratio, and obtains the graphite oxidation corrosion reaction rate.