High-temperature atmosphere firing device for detecting ash content of high-purity graphite

Abstract

The invention provides a high-temperature atmosphere firing device for detecting the ash content of high-purity graphite. The high-temperature atmosphere firing device comprises a supporting frame, a heating furnace connected with the supporting frame, a dustproof hearth arranged in the heating furnace, a controllable exhaust chimney, a multi-point temperature detection module, a distributed gas supply module and a control system. Oxygen can be uniformly conveyed into the dustproof hearth from the bottom of the heating furnace through the distributed gas supply module, so that a high-purity graphite sample in the dustproof hearth is in a high-concentration oxygen atmosphere, and intermediate products in reaction are discharged in time through the controllable exhaust chimney, so that the inhibition effect of the intermediate products is reduced; the optimal ashing condition can be established by adjusting the temperature, the oxygen flow, the exhaust speed and the like, so that all the samples are in a rapid burning reaction state, the overall reaction efficiency is improved, the efficient and rapid burning effect is achieved, no-wind-feeling and high-flow oxygen supply of the distributed gas supply module can effectively avoid pollution among the samples, and the service life of the samples is prolonged. And the detection accuracy of the ash content of the high-purity graphite is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of ash content detection, and in particular to a high-temperature atmosphere burning device for detecting the ash content of high-purity graphite. Background Art

[0002] High-purity graphite has the characteristics of high purity, high chemical stability, high electrical conductivity, high thermal conductivity, wear resistance, high temperature resistance, self-lubrication, easy processing, etc. It is widely used in metallurgy, chemical industry, aerospace, electronics, machinery, nuclear energy, military and other industrial fields. In particular, large-scale and high-quality high-purity graphite, as an alternative material, has a broad application space in high-tech and new technology fields, has a broad application prospect, and plays an important role in the development of the national economy and modernization construction. It has become the forefront of scientific and technological research and an investment hotspot in the industry and financial circles.

[0003] High-purity graphite has a fixed carbon content of ≥99.9% and an ash content of ≤0.1%. Ash content is a key indicator for measuring the quality of high-purity graphite. At present, the standards for graphite ash content determination include GB / T 3521-2023 "Part 7 of Chemical Analysis Methods for Graphite", YB / T5146-2022 "Determination of Ash Content of High-Purity Graphite Products", JB / T 8133.17-2013 "Test Methods for Physical and Chemical Properties of Electric Carbon Products Part 17: Ash Content", YS / T 63.19-2012 "Part 19 of Test Methods for Carbon Materials for Aluminum: Determination of Ash Content", GB / T 1429-2009 "Determination Method for Ash Content of Carbon Materials", etc. These methods use the traditional muffle furnace burning method, the burning temperature is between 850℃ and 950℃, and the specified sample weight is between 3g and 100g.

[0004] In the process of determining ash content in a traditional muffle furnace, the supply of oxygen in the furnace and the discharge of gases such as CO2 can only be carried out by opening the furnace door. Due to the expansion of the gas in the furnace at high temperature, oxygen is prevented from entering to a certain extent, and the waste gas such as CO2 generated cannot be actively and quickly discharged, which inhibits the reaction rate. As the graphite in the muffle furnace continues to react with oxygen in the air at high temperature, the amount of oxygen consumed by the reaction is much greater than the amount of oxygen added to the muffle furnace, resulting in insufficient oxygen in the muffle furnace, which further prolongs the burning reaction time. Its reaction mechanism is: C first reacts with O2 to produce CO2; when CO2 reaches a certain concentration, CO2 and C gasify to produce CO; as the oxygen supply in the muffle furnace continues to decrease, the CO concentration continues to increase. When CO reaches a certain concentration, CO reacts with C to generate a ketone intermediate product, which is adsorbed on the graphite surface. Due to the high activation energy of ketone desorption, the reaction rate with O2 is very slow below 1200°C, thereby inhibiting the overall reaction rate of C and O2. This reaction rate directly affects the efficiency of determining the ash content of high-purity graphite in a traditional muffle furnace. Therefore, when using a traditional muffle furnace to detect the ash content of high-purity graphite, the burning time of high-purity graphite in the muffle furnace is extremely long (for example, a 50g high-purity graphite sample needs to be continuously burned at high temperature in the muffle furnace for 12 to 14 hours in an air atmosphere to be completely burned), which is difficult to meet the requirements of efficient, rapid and accurate detection of the ash content of high-purity graphite. In addition, the temperature control requirement for the traditional muffle furnace to determine the ash content of high-purity graphite is 950℃±20℃. Since it usually has only one temperature-controlling thermocouple, the temperature difference at different positions in the furnace is large, and the real-time monitoring of the burning temperature cannot be achieved, and there is a risk of deviation from the detection method. Therefore, it is urgent to develop a device that can meet the requirements of rapid burning of high-purity graphite to achieve efficient, rapid and accurate detection of the ash content of high-purity graphite.

[0005] Although the graphite ash content detection auxiliary device existing in the prior art can improve the accuracy of graphite ash content detection to a certain extent, it cannot solve the fundamental problem of long burning time of high-purity graphite samples under large sample weighing conditions, nor can it fundamentally improve the efficiency and accuracy of high-purity graphite ash content detection.

[0006] There are also schemes to improve the traditional muffle furnace in the existing coal detection technology, such as by setting a conveying mechanism, a heat-resistant plate and adding a chimney in the muffle furnace, or by combining a muffle furnace with a chimney and another independent furnace without a chimney in parallel, or by adding devices such as a wind shield, a positioning plate, a limiting plate and a guide plate to the traditional muffle furnace, etc. Since the molecular structure of graphite is stable and has good high-temperature oxidation resistance, only by setting a chimney and increasing gas circulation, although it can speed up the emission rate of waste gas generated after graphite burning to a certain extent, it does not solve the problem of insufficient oxygen concentration in the high-temperature burning process, and still cannot significantly improve the efficiency of high-purity graphite ash detection. It may even cause ash residue to escape due to excessively fast airflow, causing contamination between samples.

[0007] In addition, the prior art also has a series of automated, continuous, and efficient detection devices in the field of coal ash detection, which can realize the automated crushing, combustion, and measurement of coal, and can measure the coal ash without manual operation. The measurement speed is fast and very suitable for large-scale coal ash measurement. However, this type of ash detection device is only suitable for coal with high ash content (fixed carbon is usually around 60%, and ash content is usually 20% to 30%), and is more suitable for production process control, but not for ash determination of high-purity carbon materials (fixed carbon greater than 99.9%) such as high-purity graphite, which has extremely high precision requirements. Summary of the invention

[0008] The purpose of the present invention is to provide a burning device specially used for ash content detection of high-purity graphite in view of the deficiencies existing in the above-mentioned background technology, so as to realize efficient, rapid and accurate detection of ash content of high-purity graphite.

[0009] In order to achieve the above-mentioned object, the present invention provides a high-temperature atmosphere burning device for high-purity graphite ash content detection, a support frame, a heating furnace connected to the support frame, a dust-proof furnace chamber arranged in the heating furnace, a controllable exhaust chimney, a multi-point temperature detection module, a distributed air supply module, and a control system;

[0010] A furnace inlet is provided on the first side of the heating furnace, a heat preservation furnace door is provided at the position of the furnace inlet, a furnace exhaust port is provided on the second side of the heating furnace, the controllable exhaust chimney is connected with the furnace exhaust port, and is used to discharge the exhaust gas in the heating furnace, and the heating furnace is provided with a heater, and the heater is evenly distributed relative to the dustproof furnace;

[0011] The multi-point temperature detection module is used to detect the temperatures of multiple temperature zones in the dustproof furnace in real time;

[0012] The distributed gas supply module includes a plurality of gas pipes, an air intake valve and a gas flow meter, each of the gas pipes is connected to the heating furnace, and the gas pipes are evenly distributed at equal distances. The air intake valve and the gas flow meter are both arranged on the gas pipes, and are used to control the opening and closing degree of the gas pipes and detect the air intake flow, respectively;

[0013] The control system is used to analyze the detection data and control each module through a program.

[0014] Furthermore, the dustproof furnace is a square furnace cavity formed by splicing multiple pieces of quartz.

[0015] Furthermore, the dustproof furnace chamber includes a quartz support plate, an L-shaped porous quartz plate, and a U-shaped quartz cover. The quartz support plates are laid at equal intervals on the bottom of the dustproof furnace chamber, the L-shaped porous quartz plate covers the quartz support plate, and the bottom of the L-shaped porous quartz plate contacts the bottom of the dustproof furnace chamber, and the U-shaped quartz cover covers the quartz support plate and the L-shaped porous quartz plate.

[0016] Furthermore, an exhaust port is provided at the end of the controllable exhaust chimney, the exhaust port is arranged in an inverted cone shape, and the exhaust port is provided with an exhaust valve.

[0017] Furthermore, the exhaust port is also provided with an oxygen concentration detection sensor, and the oxygen concentration detection sensor is used to detect the oxygen concentration in the exhaust gas.

[0018] Furthermore, the multi-point temperature detection module includes a plurality of thermocouples extending into the dustproof furnace, and each of the thermocouples is located in a different area in the dustproof furnace.

[0019] Furthermore, the control system includes a PLC control module and a numerical control center; the numerical control center is used to analyze the detection data and can display and input data. The PLC control module is electrically connected to the numerical control center and is used to control each module.

[0020] Furthermore, the gas pipes are arranged in a group with multiple pipes in the longitudinal direction and in a staggered manner with the L-shaped porous quartz plate, and multiple groups are arranged in a horizontal direction with equal distances, and each group of the gas pipes is provided with a manual adjustment switch.

[0021] Furthermore, the thickness of the dustproof furnace is 3mm to 20mm; the inner diameter of the controllable exhaust chimney is 10mm to 40mm, the height is 15cm to 80cm, and the inner diameter range of the exhaust port is 30mm to 150mm; the thermocouple type of the multi-point temperature detection module is an armored K-type thermocouple with a diameter of 2mm to 10mm, the inner diameter of the gas pipe is 1mm to 5mm, and the gas flow meter is electronic with a range of 5L / min to 50L / min.

[0022] Furthermore, when some gas flow meters of the distributed gas supply module detect that the flow data is too large or too small, the corresponding air intake valve is adjusted to make the flow rate of oxygen delivered to each location uniform, thereby achieving a windless effect.

[0023] The above scheme of the present invention has the following beneficial effects:

[0024] The high-temperature atmosphere burning device for high-purity graphite ash content detection provided by the present invention can evenly transport oxygen from the bottom of the heating furnace to the dust-proof furnace through a distributed air supply module, so that all samples in the dust-proof furnace are in a high-concentration oxygen atmosphere, and the intermediate products in the reaction are discharged in time through a controllable exhaust chimney, thereby reducing the inhibitory effect of the intermediate products and establishing the best ashing conditions, so that all samples are in a fast burning reaction state, improving the overall reaction efficiency, and achieving an efficient and fast high-temperature atmosphere burning effect on high-purity graphite. Moreover, the high-flow oxygen supply without wind sense of the distributed air supply module can effectively avoid contamination between samples, thereby ensuring the accuracy of high-purity graphite ash content detection;

[0025] The present invention improves the uniformity of oxygen concentration during the atmosphere burning of batch high-purity graphite by setting a quartz dustproof furnace and combining it with a distributed gas supply module, thereby promoting uniform burning of different samples. The spliced ​​quartz dustproof furnace can significantly reduce the manufacturing cost, effectively avoid the cracking and damage of quartz caused by the difference in high-temperature thermal expansion coefficient, and improve the service life.

[0026] The present invention adopts surrounding distributed heaters and combines multi-point continuous temperature real-time monitoring, which can improve the temperature uniformity at different positions in the furnace and realize real-time monitoring of the burning temperature, effectively reducing the risk of deviation detection method;

[0027] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 It is a schematic diagram of the internal structure of the overall structure of the present invention (front view);

[0030] Figure 3 It is a schematic diagram of the internal structure of the overall structure of the present invention (side view);

[0031] Figure 4 Schematic diagram of the internal structure of the dustproof furnace of the present invention (front view);

[0032] Figure 5 The figure is a schematic diagram of the internal structure of the dustproof furnace of the present invention (side view);

[0033] Figure 6 This is a diagram of the high-purity graphite in the tubular atmosphere (oxygen) furnace of Case 3 of the present invention, where (a) is the oxygen delivery direction and flow rate, (b) is the ash content after high-temperature calcination at 850°C for 7 hours, and (c) is the ash content after high-temperature calcination at 850°C for 8 hours.

[0034] Description of reference numerals:

[0035] 10-support frame; 20-heating furnace; 21-furnace inlet; 22-furnace exhaust port; 23-heater; 30-dust-proof furnace; 31-quartz support plate; 32-L-shaped porous quartz plate; 33-U-shaped quartz cover; 40-controllable exhaust chimney; 41-exhaust port; 50-multi-point temperature detection module; 51-thermocouple; 60-distributed gas supply module; 61-gas pipeline; 62-intake valve; 63-gas flow meter; 64-manual adjustment switch; 70-PLC control module; 80-CNC center. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] like Figure 1-Figure 3As shown, an embodiment of the present invention provides a high-temperature atmosphere burning device for detecting the ash content of high-purity graphite, including a support frame 10, a heating furnace 20, a dust-proof furnace chamber 30 arranged in the heating furnace 20, a controllable exhaust chimney 40 connected to the heating furnace 20, a multi-point temperature detection module 50 for measuring the temperature of different areas in the heating furnace 20, and a distributed air supply module 60, a PLC control module 70, and a CNC center 80 (computer).

[0040] Among them, unlike the "front opening furnace door" of the traditional muffle furnace, the "side opening furnace door" and "front control" method are adopted in this embodiment, which can not only facilitate the arrangement of "left-right through" exhaust, but also reduce the depth of the equipment. Specifically, the upper and lower layers of the support frame 10 are respectively a high-temperature working area and a low-temperature working area. The heating furnace 20 is arranged in the high-temperature working area of ​​the upper layer of the support frame 10, and a furnace inlet 21 is arranged on the left side (or right side) of the heating furnace 20, and an insulation furnace door with a visual window is arranged at the position of the furnace inlet 21. The right side (or left side) of the heating furnace 20 is provided with a furnace exhaust port 22, and a controllable exhaust chimney 40 is arranged on the right side of the heating furnace 20 and communicated with the furnace exhaust port 22, for discharging the exhaust gas in the heating furnace 20. A heater 23 is arranged in the heating furnace 20, and a dustproof furnace 30 is also arranged in the heating furnace 20. As a preferred embodiment, the heater 23 is arranged around the dustproof furnace 30 to implement more sufficient and uniform heating in the dustproof furnace 30.

[0041] In this embodiment, the dustproof furnace 30 is a square furnace chamber formed by splicing multiple pieces of quartz. As a place for high-purity graphite to be burned in a high-temperature atmosphere, the dustproof furnace 30 can effectively prevent dust from falling and contaminating the sample. Figure 4 , Figure 5 As shown, in one specific embodiment, three quartz support plates 31 are laid at equal intervals at the bottom of the dustproof furnace 30, and an L-shaped porous quartz plate 32 is covered on the quartz support plate 31, and the L-shaped bottom contacts the entire bottom of the dustproof furnace 30, and finally a U-shaped quartz cover 33 is used to cover the quartz support plate 31 and the L-shaped porous quartz plate 32 (the bottom of the U-shaped quartz cover 33 also contacts the entire bottom of the dustproof furnace 30), together forming the dustproof furnace 30. Compared with the one-piece quartz furnace chamber, the square furnace chamber formed by splicing multiple pieces of quartz provided in this embodiment can not only significantly reduce the manufacturing cost, but also effectively avoid the cracking and damage of quartz caused by the difference in thermal expansion coefficient at high temperature, and improve the service life.

[0042] In this embodiment, an exhaust port 41 is provided at the end of the controllable exhaust chimney 40. The exhaust port is in an inverted cone shape, which can discharge the exhaust gas in the heating furnace 20, and adjust the airflow rate through the exhaust valve to avoid the escape of ash residue due to excessive airflow rate, and establish the best ashing conditions. Among them, the furnace exhaust port 22 is made of a stainless steel plate wrapped with a thermal insulation material, which is mainly used for heat insulation and support and connection of the controllable exhaust chimney 40. The controllable exhaust chimney 40 itself is made of stainless steel or high-temperature resistant metal round tubes. As a preferred embodiment, the exhaust port 41 can also be further provided with an oxygen concentration detection sensor, which can feedback control the amount of oxygen entering the heating furnace 20 by detecting the oxygen concentration in the exhaust gas.

[0043] In this embodiment, the multi-point temperature detection module 50 includes a plurality of thermocouples 51 extending from the upper portion of the heating furnace 20 to the dustproof furnace chamber, for example Figure 2 The left, middle and right three are shown to realize the real-time detection of the temperature of the left, middle and right three temperature zones of the dustproof furnace 30. Of course, more thermocouples 51 can be set in other embodiments to accurately obtain the temperature field in the dustproof furnace 30.

[0044] In the present embodiment, the distributed gas supply module 60 and the PLC control module 70 are arranged on the lower layer of the support frame 10, that is, below the heating furnace 20. Among them, the distributed gas supply module 60 includes a plurality of gas pipes 61 made of stainless steel or high-temperature resistant metal materials, and the gas pipes 61 are connected to the heating furnace 20 to ensure that oxygen is evenly distributed and delivered to the dustproof furnace 30 without wind. At the same time, the distributed gas supply module 60 also includes an intake valve 62 and a gas flow meter 63, which are both arranged on the gas pipe 61, and are respectively used to control the opening and closing degree of the gas pipe 61 and to count the intake flow. It is worth mentioning that the gas flow meter 63 is an electronic flow meter, which can not only realize the detection of the oxygen flow rate, but also is the key to electronically regulating and controlling the oxygen intake.

[0045] It should be noted that the gas flow meter 63, the thermocouple 51, the oxygen concentration detection sensor, etc. are electrically connected to the numerical control center 80, and the data such as the intake air flow, temperature, exhaust oxygen concentration, etc. detected by them are transmitted to the numerical control center 80 in real time. The PLC control module 70 is electrically connected to the heater 23, the exhaust valve, the intake valve 62, etc., and is electrically connected to the numerical control center 80. After the instruction of the numerical control center 80 is sent to the PLC control module 70, the heater 23, the exhaust valve (the exhaust valve can also be manually adjusted), the intake valve 62, etc. are controlled by the PLC control module 70, so as to regulate the entire high-temperature atmosphere burning process in the heating furnace 20.

[0046] It is worth mentioning that the gas delivery pipe 61 is evenly distributed at multiple points, and its end is installed between two adjacent quartz support plates 31, and is arranged in a "staggered hole manner" with the L-shaped porous quartz plate 32, so that the gas flow rate output by the gas delivery pipe 61 is hindered and slowed down to a certain extent, achieving the effect of no wind feeling. This method can also be better realized based on the solution of splicing multiple quartz pieces in this embodiment. For example, Figure 2 , Figure 3 The gas pipes 61 shown are arranged in groups of 4 in the longitudinal direction and 5 groups are arranged equidistantly in the transverse direction, and each group is further equipped with a manual adjustment switch 64 to meet the requirement of adjusting the oxygen supply distribution according to the number of samples. The numerical control center 80 can dynamically adjust the opening and closing degree of each intake valve 62 and the exhaust valve by the PLC control module 70 according to the data of the gas flow meter 63 and the oxygen concentration detection sensor. So that the oxygen concentration in the heating furnace 20 is appropriate and uniform. For example, when the oxygen concentration detection sensor at the position of the controllable exhaust chimney 40 detects that the oxygen concentration in the exhaust gas is too high, each intake valve 62 can be closed; when some of the gas flow meters 63 detect that the flow data is too large or too small, it indicates that the oxygen is not evenly delivered to the heating furnace 20, so the corresponding intake valve 62 can be adjusted to make the flow rate (pressure at each location) of oxygen delivered at each location uniform, ensuring the effect of no wind feeling.

[0047] Therefore, compared with the traditional muffle furnace and the means of only adding chimneys, wind shields and the like, the high-temperature atmosphere burning device for high-purity graphite ash content detection provided in this embodiment can monitor and actively control the atmosphere in the heating furnace 20 in real time, ensuring sufficient oxygen concentration during the high-temperature atmosphere burning process, thereby improving the efficiency and accuracy of high-purity graphite ash content detection.

[0048] As an optional implementation scheme of this embodiment, the thickness of the U-shaped quartz cover 33 of the dustproof furnace 30 is: 3mm~10mm (preferably 5mm), the thickness of the quartz support plate 31 is: 5mm~20mm (preferably 10mm), the thickness of the L-shaped porous quartz plate 32 is: 3mm~10mm (preferably 5mm), and the pore diameter is: 1mm~10mm (preferably 3mm).

[0049] As an optional implementation of this embodiment, the inner diameter of the metal circular tube of the controllable exhaust chimney 40 is: 10mm~40mm (preferably 25mm), the height is: 15cm~80cm (preferably 40cm), and the inner diameter range of the exhaust port 41 is: 30mm~150mm (preferably 100mm).

[0050] As an optional implementation of this embodiment, the type of the thermocouple 51 of the multi-point temperature detection module 50 is an armored K-type thermocouple 51, and the diameter of the thermocouple 51 is 2 mm to 10 mm (preferably 3 mm).

[0051] As an optional implementation of this embodiment, the inner diameter of the gas pipe 61 of the distributed gas supply module 60 is 1 mm to 5 mm (preferably 3 mm). The gas flow meter 63 is electronic and has a range of 5 L / min to 50 L / min (preferably 30 L / min).

[0052] The following is a specific example to further illustrate the effect of this device:

[0053] In Case 1, five high-purity graphite samples with different fixed carbon contents (sample 1, sample 2, sample 3, sample 4 and sample 5) were selected, and then the samples were divided into blocks of 50 to 100 g, and three parallel samples were prepared for each sample;

[0054] Take one parallel sample from each high-purity graphite sample, then accurately weigh the mass of the dry sample (accurate to 0.01 mg), record it as m0, and place it in a porcelain boat with constant weight (the mass of the porcelain boat is recorded as m1);

[0055] The porcelain ark containing the high-purity graphite sample is placed in the heating furnace 20, and the temperature is increased to 850°C at a heating rate of 10°C / min, and then kept warm. The oxygen flow rate during the heating process is: 1L / min, and the oxygen flow rate during the holding process is: 5L / min. The high-purity graphite sample is burned until there are no black spots, and the device is turned off, and the temperature is naturally lowered and the holding time is recorded;

[0056] Take out the porcelain ark, place it in a desiccator to cool to room temperature, weigh it, and repeat this process until the weight is constant, recorded as m2;

[0057] Calculate the mass fraction of high-purity graphite ash (w) according to the following calculation formula, unit: %:

[0058]

[0059] Table 1 is a comparison table of the results of high-purity graphite ash content detection in Case 1 and the traditional muffle furnace. It can be seen from Table 1 that the high-temperature atmosphere calcination device for high-purity graphite ash content detection provided by this embodiment can completely ash 75-82g of high-purity graphite sample within 5.5h at high temperature (850℃), which can meet the technical requirements of high-temperature calcination for high-purity graphite ash content detection and can be applied to the field of high-purity graphite ash content detection.

[0060] Case 2 is a comparative example using a traditional muffle furnace. From the five high-purity graphite samples in Case 1, select one parallel sample each, and accurately weigh the dry sample (accurate to 0.01 mg), record it as m0, and then place it in a porcelain ark with constant weight (the mass of the porcelain boat is recorded as m1); put the porcelain ark containing the high-purity graphite sample into the muffle furnace, and leave the furnace door half open to ensure that sufficient air flows into the muffle furnace, then heat it to 950°C at a heating rate of 15°C / min and keep it warm, burn the high-purity graphite sample until there are no black spots, turn off the muffle furnace, cool it naturally and record the insulation time; take out the porcelain ark, place it in a desiccator to cool it to room temperature, weigh it, and repeat this process until constant weight is reached, record it as m2; calculate the mass fraction of high-purity graphite ash (w) in the same way, unit: %.

[0061] As can be seen from Table 1, it takes 950°C for 16 hours to completely ablate a 75-82g high-purity graphite sample using a traditional muffle furnace, while the high-temperature atmosphere burning device for high-purity graphite ash detection provided in this embodiment only needs 850°C for 5.5 hours to completely ablate a 75-82g high-purity graphite sample. Therefore, the high-temperature atmosphere burning device for high-purity graphite ash detection provided in this embodiment has an ashing efficiency of about 3 times higher than that of the traditional muffle furnace, that is, the high-temperature burning time for high-purity graphite ash detection can be reduced to one-third of the original. In addition, it can be seen from Table 1 that the ash results of the five samples obtained by testing the high-temperature atmosphere burning device for high-purity graphite ash detection provided in this embodiment are consistent with the ash results of the five samples obtained by testing the muffle furnace, indicating that the high-purity graphite ash index can be accurately detected by using this embodiment, and the high-efficiency, rapid and accurate detection of the ash content of high-purity graphite is achieved.

[0062] Table 1 Comparison of the results of the embodiment of the present invention and the traditional muffle furnace in the detection of high purity graphite ash

[0063]

[0064] Case 3 is the use of tubular atmosphere (oxygen) furnace high temperature atmosphere burning. Figure 6It can be seen that under the same oxygen flow rate, after high-purity graphite is calcined at high temperature in a tubular atmosphere (oxygen) furnace for 8 hours, there are still residual samples. From the trend of oxygen in the figure, it can be clearly seen that samples 1 and 2, which are preferentially exposed to oxygen, have been completely ashed after 7 hours of high-temperature calcination, while samples 3, 4, and 5 have sample residues, and the sample residues gradually increase with the trend of oxygen; when the high-temperature calcination reaches 8 hours, samples 1, 2, and 3 have all been ashed, while samples 4 and 5 still have a small amount of sample residues, but the sample residues are significantly less than the 7-hour state. The reason for the analysis is that when the temperature is greater than 700℃, during the reaction of C and O2 in the high-purity graphite block, C first reacts with O2 to produce CO2, and then CO2 and C gasify to generate CO. CO will react with C to generate ketone intermediates adsorbed on the graphite surface. Because the activation energy of ketone desorption is high, the reaction rate with O2 is very slow below 1200℃, thereby inhibiting the overall reaction rate of C and O2. Samples 1 and 2 are exposed to oxygen first and have high oxygen concentrations, so the combustion reaction is promoted and the reaction rate is significantly higher than that of the following samples. However, due to the low oxygen concentration they are exposed to and the inhibition of intermediate products, the high-temperature reaction rates of samples 3, 4, and 5 are much lower than those of samples 1 and 2. However, as samples 1 and 2 gradually react completely, the high-concentration oxygen atmosphere gradually moves to samples 3, 4, and 5 in turn, and these three samples gradually enter a state of rapid combustion reaction.

[0065] To summarize, the high-temperature atmosphere burning device for ash content detection of high-purity graphite provided in this embodiment can evenly transport oxygen from the bottom of the heating furnace 20 to the dust-proof furnace 30 through the distributed air supply module 60, so that all samples in the dust-proof furnace 30 are in a high-concentration oxygen atmosphere, and the intermediate products in the reaction are discharged in time through the controllable exhaust chimney 40, thereby reducing their inhibitory effects and establishing optimal ashing conditions, so that all samples are in a rapid burning reaction state, thereby improving the overall reaction efficiency and achieving efficient and rapid high-temperature atmosphere burning effect on high-purity graphite; in addition, the windless high-flow oxygen supply of the distributed air supply module 60 can effectively avoid contamination between samples, thereby ensuring the accuracy of ash content detection of high-purity graphite.

[0066] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A high-temperature atmosphere burning device for high-purity graphite ash content detection, characterized in that: It includes a support frame, a heating furnace connected to the support frame, a dustproof furnace chamber arranged in the heating furnace, a controllable exhaust chimney, a multi-point temperature detection module, a distributed air supply module, and a control system; A furnace inlet is provided on the first side of the heating furnace, a heat preservation furnace door is provided at the position of the furnace inlet, a furnace exhaust port is provided on the second side of the heating furnace, the controllable exhaust chimney is connected with the furnace exhaust port, and is used to discharge the exhaust gas in the heating furnace, and the heating furnace is provided with a heater, and the heater is evenly distributed relative to the dustproof furnace; The multi-point temperature detection module is used to detect the temperatures of multiple temperature zones in the dustproof furnace in real time; The distributed gas supply module includes a plurality of gas pipes, an air intake valve and a gas flow meter, each of the gas pipes is connected to the heating furnace, and the gas pipes are evenly distributed at equal distances. The air intake valve and the gas flow meter are both arranged on the gas pipes, and are used to control the opening and closing degree of the gas pipes and detect the air intake flow, respectively; The control system is used to analyze the detection data and control each module through a program; The dustproof furnace is a square furnace cavity formed by splicing multiple pieces of quartz; The dustproof furnace chamber includes a quartz support plate, an L-shaped porous quartz plate, and a U-shaped quartz cover. Multiple quartz support plates are laid at equal intervals on the bottom of the dustproof furnace chamber. The L-shaped porous quartz plate covers the quartz support plate, and the bottom of the L-shaped porous quartz plate contacts the bottom of the dustproof furnace chamber. The U-shaped quartz cover covers the quartz support plate and the L-shaped porous quartz plate. The end of the gas pipe is installed between two adjacent quartz support plates and is arranged in a staggered manner with the L-shaped porous quartz plate.

2. A high-temperature atmosphere burning device for detecting ash content of high-purity graphite according to claim 1, characterized in that: An exhaust port is arranged at the end of the controllable exhaust chimney. The exhaust port is arranged in an inverted cone shape and an exhaust valve is arranged at the exhaust port.

3. A high-temperature atmosphere burning device for detecting ash content of high-purity graphite according to claim 2, characterized in that: The exhaust port is also provided with an oxygen concentration detection sensor, and the oxygen concentration detection sensor is used to detect the oxygen concentration in the exhaust gas.

4. A high-temperature atmosphere burning device for detecting ash content of high-purity graphite according to claim 1, characterized in that: The multi-point temperature detection module includes a plurality of thermocouples extending into the dustproof furnace, and each of the thermocouples is located in a different area in the dustproof furnace.

5. A high-temperature atmosphere burning device for detecting ash content of high-purity graphite according to claim 1, characterized in that: The control system includes a PLC control module and a numerical control center; the numerical control center is used to analyze the detection data and can display and input data. The PLC control module is electrically connected to the numerical control center and is used to control each module.

6. A high-temperature atmosphere burning device for detecting ash content of high-purity graphite according to claim 1, characterized in that: The gas pipes are arranged in groups with multiple pipes in the longitudinal direction and arranged in a staggered manner with the L-shaped porous quartz pad, and multiple groups are arranged at equal intervals in the transverse direction, and each group of the gas pipes is provided with a manual adjustment switch.

7. A high-temperature atmosphere burning device for detecting ash content of high-purity graphite according to any one of claims 1 to 6, characterized in that: The thickness of the dustproof furnace is 3mm~20mm; the inner diameter of the controllable exhaust chimney is 10mm~40mm, the height is 15cm~80cm, and the inner diameter range of the exhaust port is 30mm~150mm; the thermocouple type of the multi-point temperature detection module is an armored K-type thermocouple with a diameter of 2mm~10mm, the inner diameter of the gas pipe is 1mm~5mm, and the gas flow meter is electronic with a range of 5L / min~50L / min.

8. A high-temperature atmosphere burning device for detecting ash content of high-purity graphite according to any one of claims 1 to 6, characterized in that: When some gas flow meters of the distributed gas supply module detect that the flow data is too large or too small, the corresponding air intake valve is adjusted to make the flow rate of oxygen transported everywhere uniform, so as to achieve the effect of no wind feeling.

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