Ultra-high temperature and high heating rate solar thermogravimetric analyzer

Abstract

The present invention proposes an ultra-high temperature and high heating rate solar thermogravimetric analyzer, which includes a high-concentration solar unit, a thermogravimetric unit, an atmosphere control unit, and a control and recording unit. In indirect heating mode, the analyzer can achieve a heating temperature from room temperature to 1700°C and a heating rate of 1-200°C / min, and achieve temperature uniformity and controllability through a variety of control methods; in direct concentrating solar heating mode, it can achieve extreme test conditions with a maximum temperature of 2700°C and a maximum heating rate of 900°C / min. Both heating modes can achieve 0.1-10 5 The present invention overcomes the shortcomings of conventional thermogravimetric analyzers, such as their inability to achieve solar spectrum characteristics, extreme high temperatures and high heating rates, high humidity, and high vacuum environments. By utilizing a four-corner tangential air intake method and a dual balance system, the instrument achieves improvements in stability, weighing accuracy, and analytical performance, thus broadening its applicability.

Description

Technical Field

[0001] The present invention relates to the field of thermal analysis technology, in particular to an ultra-high temperature and high heating rate solar thermogravimetric analyzer. The analyzer is an ultra-high temperature, high heating rate, high vacuum and high humidity solar thermogravimetric analyzer. Background Art

[0002] Solar thermochemical methods can achieve high-density heat storage and clean fuel production, and are increasingly becoming a research hotspot in the field of renewable energy. Storing low-energy-density, discontinuous solar energy in the form of high-energy-storage-density chemical energy can improve the dispatchability of energy and power production. It can also utilize greenhouse gases such as CO2 in a resource-efficient manner while obtaining high-calorific-value clean fuels that are easy to store and transport. Reactions for solar thermochemical heat storage and thermochemical fuel production include metal hydride systems, metal oxide systems, metal nitride systems, inorganic hydroxide systems, and carbonate systems, as well as solar pyrolysis, gasification, and reforming of methane or carbonaceous materials. The kinetic properties of different reactive groups in solar thermochemical reactions directly determine the energy conversion efficiency and fuel production rate in the solar thermochemical cycle. In addition, the design cycle of high-temperature solar reactors is long and the process is cumbersome. Therefore, the preparation and screening of reactive groups and the study of reaction kinetics in the early reactor-free stage are crucial to improving the efficiency of solar energy conversion.

[0003] A thermogravimetric analyzer (TGA) can measure the mass of reactants as a function of reaction time at a specific temperature, analyze the gas production rate in real time, and obtain reaction kinetic parameters and properties. It is an important tool for evaluating the performance of thermochemical cycles. Compared to conventional thermochemical reactions, solar thermochemical fuel production and high-temperature heat storage reactions place even more stringent demands on spectral characteristics, reaction temperature, heating rate, vacuum, and water vapor atmosphere under solar radiation. However, commercial TGAs, which are electrically heated by metal wires, have a maximum temperature of 2300°C in a non-oxidizing atmosphere (1650°C in an oxidizing atmosphere) and a maximum heating rate of 50-100°C / min. This still falls short of the requirements of solar thermochemical reactions and fails to reflect the actual operating conditions of solar reactors. This hinders the study of radiation properties such as reactant absorptivity and reaction kinetics (e.g., the rapid gasification mechanism of carbonaceous particles under highly concentrated solar energy), thus hindering the design and application of solar thermochemical reactors. Furthermore, in other aerospace, nuclear power, and military applications, there is also a need for real-time quantitative material testing and performance research under extreme conditions such as ultra-high temperatures, high energy fluxes, extreme heating rates, and high light fluxes.

[0004] In response to the shortcomings of traditional thermogravimetric analyzers in special applications, such as heating rate and measurement accuracy, different patents and designs have been proposed to improve them. Chinese patent CN 106769606 A proposes a rapid heating thermogravimetric analyzer that uses a metal mesh reactor as a heating device. Direct contact with the particles greatly improves the heating rate. Chinese patent CN 109632879 A proposes a visual macroscopic thermogravimetric analyzer for briquette combustion, which measures and records the thermal weight loss and thermal conversion characteristics of large-mass particles and large-volume particle samples such as briquette, and simultaneously collects the dynamic changes in the combustion shape and combustion temperature of briquette during combustion. Chinese patent CN 205691449 U proposes an in-situ rapid sampling thermogravimetric analyzer that extracts gas products from the surface of the reactants through a sampling probe above the crucible, overcoming the measurement error problem caused by product gas diffusion or secondary reaction in existing combined thermogravimetric technologies and improving the authenticity and accuracy of the analysis results. Chinese patent CN108007809 A proposes a fast-heating, wide-range thermogravimetric analyzer with heating between multiple layers of metal mesh, resulting in minimal stacking effects and a stable electronic balance, close to actual operating conditions. Chinese patent CN208805441U proposes a device for obtaining soot samples with thermal and oxidative crushing characteristics. By introducing a Soxhlet extraction device, volatile organic compounds are removed from soot particles, thereby obtaining the soot samples required for thermal and oxidative crushing characteristics. Chinese patent CN208206717 U proposes a high-thermal-resistance balance sample support rod for thermogravimetric analyzers. The three-section structure effectively insulates heat and reduces the load on the support rod, thereby increasing the weighing range. Chinese patent CN 208635565 U proposes a heating device for thermogravimetric-infrared combined analysis, addressing the current problem of temperature stability when the gas overflowing from the thermogravimetric analyzer enters the pipeline through the connecting pipe during use.

[0005] In general, existing thermogravimetric analyzers and patents focus on improving the heating rate, range, and outlet gas detection equipment, but fail to take into account and meet the requirements of spectral characteristics, high light flux, ultra-high temperature, high heating rate, temperature uniformity, high vacuum, and water vapor atmosphere in solar thermochemical research. Summary of the Invention

[0006] The present invention addresses the shortcomings of existing thermogravimetric analyzers, which fail to meet the requirements for spectral characteristics, ultra-high temperatures, heating rates, high vacuum, and water vapor atmospheres in solar thermochemistry research. By designing a solar thermogravimetric analyzer with ultra-high temperatures and high heating rates, this instrument addresses multiple applications. It ensures excellent temperature uniformity and a stable heating rate in indirect heating mode, with a maximum heating rate of 200°C / min. In direct concentrated solar heating mode (where the sample is directly exposed to solar radiation), it can reach a maximum temperature of 2700°C and a heating rate of 900°C / min. Furthermore, solar thermogravimetric analysis can achieve a variety of controlled atmospheres, including oxidation, reduction, high vacuum, and high humidity. This provides a more quantitative and accurate research and testing platform for solar thermochemistry research and testing under extreme conditions in aerospace, nuclear power, and military applications. It also lays a solid foundation for the large-scale production of clean fuels from solar thermochemistry and the development of materials and equipment for special environments.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: the ultra-high temperature and high heating rate solar thermogravimetric analyzer of the present invention consists of four parts: a high-concentration solar energy unit, a thermogravimetric unit, an atmosphere control unit, and a control and recording unit.

[0008] The highly concentrated solar energy unit uses a short-arc xenon lamp and a compound parabolic (CPC) secondary concentrator to generate highly concentrated solar energy and project it onto the composite heat absorption plate (indirect heating) or sample (direct heating) of the thermogravimetric unit; the thermogravimetric unit uses a dual-balance structure to achieve real-time and accurate weighing of the sample weight, while combining auxiliary electric heating and flow channels to achieve temperature uniformity; the atmosphere control unit uses valves and vacuum pumps to obtain vacuum, high humidity, inert gas atmospheres, etc.; the control and recording unit uses a model predictive (MPC) controller to achieve precise control of temperature, heating rate, temperature uniformity and other functions of the thermogravimetric platform.

[0009] The high-concentration solar unit primarily consists of a power supply and adjustable bracket, a plane reflector, an ellipsoidal concentrator, and an adjustable iris. Three ellipsoidal concentrators are fixed to the adjustable bracket. Each ellipsoidal concentrator has a 7kWe short-arc xenon lamp at its focal point. An adjustable iris is positioned on the opening of each ellipsoidal concentrator. The aperture of the iris allows the size of the exit spot to be adjusted. The spot is then transformed from a horizontal projection to a vertical projection by the plane reflector.

[0010] The internal structure of the thermogravimetric unit is as follows: Figure 2As shown, it consists of a water-cooled quartz window, a CPC secondary concentrator, a composite heat absorbing plate, a thermogravimetric furnace body, a balance chamber and a lifting platform. The CPC secondary concentrator is fixedly connected to the lifting platform and is connected to the top of the thermogravimetric furnace body through a flange. The top of the CPC secondary concentrator is a water-cooled quartz window, and there are secondary air inlets arranged in a four-corner cut circle on the side, which not only cools and cleans the water-cooled quartz window, but also rotates the intake air downward to the thermogravimetric furnace body. A composite heat absorbing plate is placed at the bottom of the CPC secondary concentrator. During the placement of samples or sampling, the CPC secondary concentrator can be lifted and the composite heat absorbing plate can be removed to achieve direct heating mode. The upper half of the composite heat absorbing plate is a SiC foam ceramic structure, which is connected to the foam ceramic air duct in the thermogravimetric furnace body. The lower half of the composite heat absorbing plate is an airtight SiC flat plate structure.

[0011] At the center of the thermogravimetric furnace, there are parallel and adjacent sample balance arms and reference balance arms extending from the balance chamber, supporting the sample crucible and reference crucible, and thermocouple measuring points are arranged at the bottom of the crucible and the side of the thermogravimetric furnace. The sample balance arm and the reference balance arm are connected to the balance chamber, and comparative measurement is achieved through the photoelectric or electromagnetic test structure inside them. The innermost layer of the thermogravimetric furnace body below the height of the balance arm is an electric heating device, the middle layer is a foam ceramic air duct, and the outermost layer is an outer shell for insulation and support. The rotating airflow brought out from the heating cavity of the thermogravimetric furnace body and the heated airflow of the thermogravimetric furnace body discharged from the outlet of the foam ceramic air duct are cooled by a water cooling jacket, and then externally detected through the gas detection interface or extracted through the vacuum pump interface.

[0012] The control and recording unit consists of a pyrometer, thermocouple measuring points, a pressure transmitter, an MPC controller, and an output device. The pyrometer monitors sample temperature, the thermocouple measuring points and the pressure transmitter monitor the temperature and pressure inside the thermogravimetric furnace, respectively. The output device records and outputs test parameters. The MPC controller controls the aperture opening, xenon lamp power, number of xenon lamps, flowmeter, and auxiliary power to achieve test requirements such as temperature and heating rate, as well as temperature uniformity control.

[0013] The atmosphere control unit is composed of a gas detector interface, a gas detector, a vacuum pump interface, a vacuum pump, a valve, a water tank, an Ar gas tank, a water flow meter, an outlet gas flow meter, a purge gas flow meter, and a steam generator. The Ar gas tank is connected to the secondary air inlet via the outlet gas flow meter and the purge gas flow meter, and the gas rotary jet purge is used to cool and clean the water-cooled quartz window. Moreover, the gas from the Ar gas tank and the outlet gas flow meter can also be mixed with the water from the water tank and the water flow meter to enter the steam generator, obtaining water vapor of different humidity and temperature and entering the primary air inlet. In addition, the vacuum pump can realize thermogravimetric testing under different vacuum levels.

[0014] The working process of the ultra-high temperature and high heating rate solar thermogravimetric analyzer is as follows:

[0015] 1. Direct heating:

[0016] (1) Open the flange, lift the lifting platform, remove the composite heat absorbing plate, place the test sample flat in the crucible on the sample balance arm, lower the lifting platform, close the flange, and re-establish the airtight connection between the CPC secondary concentrator and the thermogravimetric furnace body.

[0017] (2) After turning on the power and setting the thermal reheating program, the MPC controller automatically sets the power supply and the number of short-arc xenon lamps and the power of the xenon lamps that need to be turned on in the adjustable bracket 3, and closes the adjustable diaphragm. After the xenon lamp power stabilizes, the adjustable diaphragm is opened. The light source generated by the short-arc xenon lamp passes through the ellipsoidal concentrator and is projected onto the plane reflector. The concentrated solar light spot is projected vertically through the water-cooled quartz window onto the sample surface to achieve direct heating.

[0018] (3) According to the set atmosphere and flow, the MPC controller sets the temperature of the steam generator, the flow of the water flow meter, the outlet gas flow meter, and the vacuum degree of the vacuum pump connected to the vacuum pump interface. At the same time, the MPC controller sets the purge gas flow entering the secondary air inlet and the cavity gas flow entering the primary air inlet from the outlet gas flow meter. The purge gas entering the secondary air inlet cools the water-cooled quartz window and then mixes with the gas entering the primary air inlet. Under the air inlet arrangement, both the primary and secondary air inlets exhibit a "four-corner cut-circle" rotating flow, which is more uniform at the same flow rate. Combined with the heating cavity structure of the thermogravimetric furnace, the flow in the central area is stable.

[0019] (4) During the test, the sample balance arm and the reference balance arm are each connected to a set of balances in the balance chamber. The output weight signal is the difference in weight between the sample arm and the reference arm. The thermal expansion and buoyancy effect of the balance arm are automatically deducted, and there is no need to measure a blank baseline for buoyancy correction. The thermogravimetric curve of the sample is directly obtained. The thermocouple measuring points in the sample arm and the reference arm measure the sample bottom temperature, the reference temperature, and the temperature difference between the two in real time to obtain the differential thermal curve (DTA curve); and combined with the calibration file of the standard sapphire plate (specific heat is known), the instrument operating software automatically calculates the heat flow curve (DSC curve). At the same time, the measured sample bottom temperature is fed back to the MPC controller, and parameters such as the number of arc xenon lamps, xenon lamp power, adjustable bracket height, and adjustable aperture opening are adjusted according to the set temperature rise program. In addition, the pyrometer measures the sample front temperature and feeds the temperature difference of the sample bottom temperature back to the MPC controller to adjust parameters such as the air inlet flow rate, thereby increasing the temperature uniformity of the heating chamber inside the thermogravimetric furnace.

[0020] (5) During the test, the thermocouple measuring point simultaneously monitors the edge temperature of the thermogravimetric furnace, and the pressure transmitter monitors the internal pressure of the thermogravimetric furnace. In an emergency, the adjustable aperture can be closed and the valve can be opened to release pressure to ensure the safety of the thermogravimetric furnace. The outlet gas of the thermogravimetric furnace can be further analyzed after flowing out through the gas detector interface.

[0021] 2. Indirect heating:

[0022] (1) Open the flange, lift the lifting platform, place the composite heat absorbing plate, and place the test sample flatly in the crucible on the sample balance arm. Lower the lifting platform, close the flange, and re-establish the airtight connection between the CPC secondary concentrator and the thermogravimetric furnace body.

[0023] (2) After turning on the power and setting the thermogravimetric heating program, the MPC controller automatically sets the power supply and the number of short-arc xenon lamps that need to be turned on in the adjustable bracket and the power of the xenon lamps. The light source generated by the short-arc xenon lamp passes through the ellipsoidal concentrator and is projected onto the plane reflector. The concentrated solar light spot is projected vertically through the water-cooled quartz window onto the upper surface of the composite heat absorbing plate to achieve indirect heating. The swirl purge gas entering the secondary air inlet from the Ar gas tank and the purge gas flow meter is further heated by the foam ceramic structure on the upper layer of the composite heat absorbing plate after cooling the water-cooled quartz window. It enters the foam ceramic air duct in the thermogravimetric furnace through the side flow channel and flows out through the foam ceramic air duct outlet, achieving indirect heating of the side and bottom surfaces of the sample. In addition, the electric heating device on the lower side of the thermogravimetric furnace is turned on to achieve indirect heating of the side and bottom surfaces of the sample. The nearly spherical thermogravimetric furnace heating cavity and the auxiliary heating equipment on the non-concentrating irradiation surface make the temperature uniformity better.

[0024] (3) Based on the set atmosphere and flow rate, the MPC controller sets the steam generator temperature, the water flow meter, the outlet gas flow meter flow rate, and the vacuum level of the vacuum pump connected via the vacuum pump interface. Under the primary air inlet arrangement, the air entering the primary air inlet from the outlet gas flow meter exhibits a "four-corner tangential circle" rotational flow, which is more uniform at the same flow rate. Combined with the heating chamber structure of the thermogravimetric furnace, the flow in the center area is stable.

[0025] (4) During the test, the sample balance arm and the reference balance arm are each connected to a set of balances in the balance chamber. The output weight signal is the weight difference between the sample arm and the reference arm. The thermal expansion and buoyancy effect of the balance arm are automatically deducted to directly obtain the thermogravimetric curve of the sample. Through the thermocouple measuring points in the sample arm and the reference arm, the temperature at the bottom of the sample, the reference temperature and the temperature difference between the two are measured in real time to obtain the differential thermal curve, and the heat flow curve is calculated in combination with the calibration file of the standard sapphire sheet. At the same time, the measured temperature at the bottom of the sample is fed back to the MPC controller, and the parameters such as the number of arc xenon lamps, xenon lamp power, adjustable bracket height, adjustable aperture opening, electric heating device power, outlet gas flow meter and purge gas flow meter are adjusted according to the set temperature rise program. In addition, the thermocouple measuring point automatically measures and records the edge temperature of the thermogravimetric furnace body, and the temperature difference at the bottom of the sample is fed back to the MPC controller to adjust the parameters such as the inlet flow rate and electric heating power to achieve uniform heating of the test sample inside the thermogravimetric furnace body.

[0026] (5) During the test, the thermocouple measuring point simultaneously monitors the edge temperature of the thermogravimetric furnace, and the pressure transmitter monitors the internal pressure of the thermogravimetric furnace. In an emergency, the adjustable iris, electric heating, and valve pressure relief can be closed to ensure the safety of the thermogravimetric furnace. The outlet gas of the thermogravimetric furnace can be further analyzed after flowing out through the gas detector interface.

[0027] The advantages of the present invention are:

[0028] (1) Taking into account both direct and indirect heating methods, it can achieve an ultra-high heating rate of 900℃ / min under the characteristics of the solar spectrum, and a heating rate of less than 200℃ / min with good temperature uniformity. In the indirect heating mode, the foam ceramic air duct, electric heating device and heating chamber structure arranged on the non-concentrating irradiation surface of the thermogravimetric furnace body increase temperature uniformity.

[0029] (2) The inlet air flow adopts a "four-corner tangential circle" rotational flow, with a small flow rate in the center area, which produces less resistance and disturbance to the sample plate and balance arm, and improves stability. The dual balance system automatically deducts the thermal expansion and buoyancy effects of the balance arm, eliminating the need for a separate blank baseline measurement for buoyancy correction. The mass measurement accuracy is high, and the DTA and DSC functions are simple to implement.

[0030] (3) A variety of temperature control methods are available (number of xenon lamps, xenon lamp power, adjustable bracket height, adjustable aperture opening, electric heating device power, primary and secondary air flow rates), and a high-precision temperature control and adjustment method is achieved by combining a database and a multi-parameter model predictive control algorithm.

[0031] (4) It can be used for thermal weighing in high pressure, vacuum and water vapor atmospheres, and is convenient for online exhaust gas detection, with a wide range of applications.

[0032] Based on the above advantages, the ultra-high temperature and high heating rate solar thermogravimetric analyzer involved in the present invention has significant application prospects in solar thermochemistry, medium and high temperature thermal utilization and other extreme condition testing fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of an ultra-high temperature and high heating rate solar thermogravimetric analyzer according to Example 1 of the present invention.

[0034] Figure 2 Schematic diagram of the internal structure of the thermogravimetric analyzer.

[0035] In the figure: 1 adjustable aperture, 2 ellipsoidal concentrator, 3 power supply and adjustable bracket, 4 pyrometer, 5 plane mirror, 6 water-cooled quartz window, 7 CPC secondary concentrator, 8 composite heat absorbing plate, 9 MPC controller, 10 output device, 11 thermogravimetric furnace, 12 gas detector, 13 vacuum pump, 14 valve, 15 balance chamber, 16 water tank, 17 Ar gas tank, 18 water flow meter, 19 outlet gas flow meter, 20 purge gas flow meter, 21 steam generator, 22 lifting platform; a housing, b foam ceramic air duct, c electric heating device, d thermocouple measuring point, e primary air inlet, f flange, g secondary air inlet, h foam ceramic air duct outlet, i water cooling jacket, j1 sample balance arm, j2 reference balance arm, k1 gas detector coupling interface, k2 vacuum pump interface, m pressure transmitter. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] Figure 1 The structure and working diagram of the ultra-high temperature and high heating rate solar thermogravimetric analyzer embodiment 1 of the present invention is shown in FIG. Figure 1 As shown, the solar thermogravimetric analyzer consists of four parts: a high-concentration solar energy unit, a thermogravimetric unit, an atmosphere control unit, and a control and recording unit.

[0038] The high-concentration solar energy unit primarily comprises a power supply and adjustable bracket 3, a plane reflector 5, an ellipsoidal concentrator 2, and an adjustable aperture 1. Three ellipsoidal concentrators 2 are fixed to the adjustable bracket. A 7kWe short-arc xenon lamp is positioned at the focal point of each ellipsoidal concentrator 2. The adjustable aperture 1 is positioned on the aperture of each ellipsoidal concentrator. The size of the exit spotlight can be controlled by continuously adjusting the aperture. The projected spot then transitions from horizontal to vertical projection via the 45° plane reflector 5.

[0039] The internal structure of the thermogravimetric unit is as follows: Figure 2As shown, it consists of a water-cooled quartz window 6, a CPC secondary concentrator 7, a composite heat absorbing plate 8, a thermogravimetric furnace body 11, a balance chamber 15 and a lifting platform 22. The CPC secondary concentrator 7 is fixedly connected to the lifting platform 22 and is connected to the top of the thermogravimetric furnace body 11 through a flange f. The top of the CPC secondary concentrator 7 is a water-cooled quartz window 6, and there are secondary air inlets g arranged in a four-corner cut circle on the side, which not only cools and cleans the water-cooled quartz window 6, but also rotates the intake air downward to the thermogravimetric furnace body 11. The composite heat absorbing plate 8 is placed at the bottom of the CPC secondary concentrator 7. During the placement of samples or sampling, the CPC secondary concentrator 7 can be lifted and the composite heat absorbing plate 8 can be removed to achieve a direct heating mode. The upper half of the composite heat absorbing plate 8 is a SiC foam ceramic structure and is connected to the foam ceramic air duct b in the thermogravimetric furnace body 11. The lower half of the composite heat absorbing plate 8 is an airtight SiC flat plate structure.

[0040] The center of the thermogravimetric furnace body 11 is provided with a sample balance arm j1 and a reference balance arm j2 extending parallel and adjacent from the balance chamber, supporting the sample crucible and the reference crucible, and thermocouple measuring points d are arranged at the bottom of the crucible and the inner side of the thermogravimetric furnace body. The sample balance arm j1 and the reference balance arm j2 are connected to the balance chamber 15, and comparative measurement is achieved through the photoelectric or electromagnetic testing structure inside them. The innermost layer of the thermogravimetric furnace body 11 below the height of the balance arm is an electric heating device c, the middle layer is a foam ceramic air duct b, and the outermost layer is a shell a for insulation and support. The rotating airflow brought out from the interior of the thermogravimetric furnace body 11 and the heated airflow discharged from the foam ceramic air duct outlet h are cooled by a water-cooling jacket i, and then externally detected through the gas detector interface k1 or extracted through the vacuum pump interface k2.

[0041] The control and recording unit consists of a pyrometer 4, a thermocouple measuring point d, an MPC controller 9, a pressure transmitter m, and an output device 10. The pyrometer 4 monitors sample temperature non-contact, the thermocouple measuring point d directly monitors the internal temperature of the thermogravimetric furnace 11, the pressure transmitter m, located at the bottom of the thermogravimetric furnace 11, monitors the internal pressure, and the output device 10 records and outputs test parameters. The MPC controller 9 controls the aperture opening, xenon lamp power, number of xenon lamps, flowmeter, and auxiliary power to achieve test requirements such as temperature and heating rate, as well as temperature uniformity control.

[0042] The atmosphere control unit consists of a gas detector interface k1, a gas detector 12, a vacuum pump interface k2, a vacuum pump 13, a valve 14, a water tank 16, an Ar gas tank 17, a water flowmeter 18, an outlet gas flowmeter 19, a purge gas flowmeter 20, and a steam generator 21. The Ar gas tank 17 is connected to the secondary air inlet g located on the CPC secondary concentrator 7 via the outlet gas flowmeter 19 and the purge gas flowmeter 20. The Ar gas rotating jet purge cools and cleans the water-cooled quartz window. Furthermore, the gas from the Ar gas tank 17 and the outlet gas flowmeter 19 can also be mixed with the water from the water tank 16 and the water flowmeter 18 and enter the steam generator 21, producing water vapor of varying humidity and temperature, which then enters the primary air inlet e located at the top of the thermogravimetric furnace 11. Furthermore, connecting the vacuum pump 13 via the vacuum pump interface k2 at the bottom of the thermogravimetric furnace 11 enables thermogravimetric testing under varying vacuum levels, and the gas detector 12 connected via the gas detector interface k1 allows for component analysis. A valve 14 is provided on the connection pipe between the vacuum pump interface k2 at the bottom of the thermogravimetric furnace body 11 and the vacuum pump 13. A gas detector connection interface k1 is provided at the bottom of the thermogravimetric furnace body 11.

[0043] The working process of the ultra-high temperature and high heating rate solar thermogravimetric analyzer is as follows:

[0044] 1. In direct heating mode:

[0045] (1) First, open the flange f, lift the lifting platform 22, remove the composite heat absorbing plate 8, and place the test sample flatly in the crucible on the sample balance arm j1. Lower the lifting platform 22, close the flange f, and re-establish the airtight connection between the CPC secondary concentrator 7 and the thermogravimetric furnace body 11.

[0046] (2) After turning on the power and setting the thermal reheating program, the MPC controller 9 automatically sets the power supply and the number of short-arc xenon lamps to be turned on and the power of the xenon lamps in the adjustable bracket 3, and closes the adjustable aperture 1. After the xenon lamp power stabilizes, the adjustable aperture 1 is opened. The light source generated by the short-arc xenon lamp passes through the ellipsoidal concentrator 2 and is projected onto the plane reflector 5. The concentrated solar light spot is vertically projected onto the sample surface through the water-cooled quartz window 6 to achieve direct heating.

[0047] (3) According to the set atmosphere and flow, the MPC controller 9 sets the temperature of the steam generator 21, the flow of the water flow meter 18, the outlet gas flow meter 19, and the vacuum degree of the vacuum pump connected via the vacuum pump interface k2. At the same time, the MPC controller 9 sets the purge gas flow rate from the purge gas flow meter 20 into the secondary air inlet g, and the cavity gas flow rate from the outlet gas flow meter 19 into the primary air inlet e. The purge gas entering the secondary air inlet g can be cooled by the water-cooled quartz window 6 and then mixed with the gas entering the primary air inlet e. Under the arrangement of the air inlets g and e, both the primary and secondary air inlets present a "four-corner tangential circle" rotating flow, and the flow in the central area is stable in conjunction with the heating cavity structure of the thermogravimetric furnace.

[0048] (4) During the test, the sample balance arm j1 and the reference balance arm j2 are each connected to a set of balances in the balance chamber 15. The output weight signal is the weight difference between the sample arm and the reference arm. The thermal expansion and buoyancy effect of the balance arm are automatically deducted to directly obtain the thermogravimetric curve of the sample. The thermocouple measuring point d in the sample arm and the reference arm measures the sample bottom temperature, the reference temperature and the temperature difference between the two in real time to obtain the differential thermal curve. The heat flow curve is automatically calculated by combining the calibration file of the standard sapphire sheet (specific heat is known). At the same time, the measured sample bottom temperature is fed back to the MPC controller 9, and the parameters such as the number of arc xenon lamps, the power of the xenon lamps, the height of the adjustable bracket and the opening of the adjustable aperture 1 are adjusted according to the set temperature rise program. In addition, the pyrometer 4 measures the sample front temperature and feeds back the temperature difference of the sample bottom temperature to the MPC controller 9 to adjust the parameters such as the air intake flow rate to increase the temperature uniformity inside the thermogravimetric furnace body 11.

[0049] (5) During the test, the thermocouple measuring point d simultaneously monitors the edge temperature of the thermogravimetric furnace, and the pressure transmitter m monitors the internal pressure of the thermogravimetric furnace. In an emergency, the adjustable aperture 1 can be closed and the valve 14 opened to release pressure to ensure the safety of the thermogravimetric furnace 11. The outlet gas of the thermogravimetric furnace 11 flows out through the gas detector interface k1 and can be further analyzed.

[0050] 2. In indirect heating mode:

[0051] (1) Open flange f, lift the lifting platform 22, place the composite heat absorbing plate 8, and place the test sample flatly in the crucible on the sample balance arm j1. Lower the lifting platform 22, close flange f, and re-establish the airtight connection between the CPC secondary concentrator 7 and the thermogravimetric furnace body 11.

[0052] (2) After turning on the power and setting the thermogravimetric heating program, the MPC controller 9 automatically sets the power supply and the number of short-arc xenon lamps to be turned on in the adjustable bracket 3 and the power of the xenon lamps. The light source generated by the short-arc xenon lamp passes through the ellipsoidal concentrator 2 and is projected onto the plane reflector 5. The concentrated solar light spot is projected vertically through the water-cooled quartz window 6 onto the upper surface of the composite heat-absorbing plate 8, achieving indirect heating. The composite heat-absorbing plate 8 is divided into two layers, the upper layer is a foam ceramic structure silicon carbide, and the lower layer is a flat plate structure silicon carbide. The swirl purge gas entering the secondary air inlet g from the Ar gas tank 17 and the purge gas flowmeter 20 cools the water-cooled quartz window, and then passes through the foam ceramic structure silicon carbide on the upper layer of the composite heat-absorbing plate 8 to be further heated. It enters the foam ceramic air duct b in the thermogravimetric furnace body 11 through the side flow channel and flows out through the foam ceramic air duct outlet h, achieving indirect heating of the side and bottom surfaces of the sample. In addition, the electric heating device c on the lower side of the thermogravimetric furnace body 11 is turned on, also achieving indirect heating of the side and bottom surfaces of the sample.

[0053] (3) Based on the set atmosphere and flow rate, MPC controller 9 sets the temperature of steam generator 21, the flow rates of water flowmeter 18 and outlet gas flowmeter 19, and the vacuum level of the vacuum pump connected via vacuum pump interface k2. With the primary air inlet e positioned, the air entering the primary air inlet e from outlet gas flowmeter 19 exhibits a "four-corner tangential circle" rotational flow, resulting in a stable flow in the center region and improved system stability.

[0054] (4) During the test, the sample balance arm j1 and the reference balance arm j2 are each connected to a set of balances in the balance chamber 15. The output weight signal is the weight difference between the sample arm and the reference arm. The thermal expansion and buoyancy effect of the balance arm are automatically deducted to directly obtain the thermogravimetric curve of the sample. The temperature at the bottom of the sample, the reference temperature, and the temperature difference between the two are measured through the thermocouple measuring point d in the sample arm and the reference arm to obtain the differential thermal curve, and the heat flow curve is calculated in combination with the standard calibration file. At the same time, the measured temperature at the bottom of the sample is fed back to the MPC controller 9, and the parameters such as the number of arc xenon lamps, the power of the xenon lamps, the height of the adjustable bracket, the opening of the adjustable aperture 1, the power of the electric heating device c, the outlet gas flowmeter 19, and the purge gas flowmeter 20 are adjusted according to the set temperature rise program. In addition, the thermocouple measuring point d automatically measures and records the edge temperature of the thermogravimetric furnace body 11, and feeds back the temperature difference of the sample bottom temperature to the MPC controller 9 to adjust the parameters such as the inlet flow rate and the electric heating power to achieve uniform heating of the test sample inside the thermogravimetric furnace body 11.

[0055] (5) During the test, the thermocouple measuring point d simultaneously monitors the edge temperature of the thermogravimetric furnace 11, and the pressure transmitter m monitors the internal pressure of the thermogravimetric furnace 11. In an emergency, the adjustable aperture 1, the electric heating, and the valve 14 can be closed to release pressure to ensure the safety of the thermogravimetric furnace 11. The outlet gas of the thermogravimetric furnace 11 flows out through the gas detector interface k1 and can be further analyzed.

[0056] The present invention does not describe in detail parts that belong to the common knowledge of those skilled in the art. The above-described embodiments are merely descriptions of preferred embodiments of the present invention. The preferred embodiments do not describe all details in detail, nor do they limit the invention to the specific embodiments described. Without departing from the spirit of the present invention, various modifications and improvements made by those skilled in the art to the technical solution of the present invention should fall within the scope of protection defined by the claims of the present invention.

Claims

1. An ultra-high temperature and high heating rate solar thermogravimetric analyzer, characterized in that: The thermogravimetric analyzer is composed of a high-concentration solar energy unit, a thermogravimetric unit, an atmosphere control unit, and a control and recording unit; The high-concentration solar energy unit mainly comprises a power supply and an adjustable bracket (3), a plane reflector (5), an ellipsoidal concentrator (2) and an adjustable aperture (1); wherein the ellipsoidal concentrator (2) is fixed on the power supply and the adjustable bracket (3) and an adjustable aperture (1) is arranged on the opening surface; the high-concentration solar energy unit uses a short arc xenon lamp and a compound parabolic (CPC) secondary concentrator (7) to generate high-concentration solar energy and projects it onto a composite heat absorbing plate (8) for indirect heating or onto a sample for direct heating; The thermogravimetric unit is composed of a water-cooled quartz window (6), a CPC secondary concentrator (7), a composite heat absorbing plate (8), a thermogravimetric furnace body (11), a balance chamber (15) and a lifting platform (22); wherein the CPC secondary concentrator (7) is fixed to the lifting platform (22) and is connected to the top of the thermogravimetric furnace body (11) through a flange (f); the top of the CPC secondary concentrator (7) is a water-cooled quartz window (6), and the side has a secondary air inlet (g) arranged in a square-cornered circle; the bottom of the CPC secondary concentrator (7) is placed with a composite heat absorbing plate (8); wherein the upper half of the composite heat absorbing plate (8) is a SiC foam ceramic structure and is connected to the thermogravimetric furnace body (11) through a flange (f) The furnace body (11) is connected to the foam ceramic air duct (b), and the lower half of the composite heat absorbing plate (8) is an airtight SiC flat plate structure; a sample balance arm (j1) and a reference balance arm (j2) are arranged at the center of the thermogravimetric furnace body (11), and comparative measurement is achieved through a photoelectric or electromagnetic test structure in the balance chamber (15); the innermost layer of the thermogravimetric furnace body (11) below the height of the balance arm is an electric heating device (c), the middle layer is the foam ceramic air duct (b), and the outermost layer is a shell (a) for heat preservation and support; the thermogravimetric unit realizes real-time weighing of the sample weight through a double balance structure, and simultaneously realizes temperature uniformity by combining auxiliary electric heating and flow channels; The control and recording unit is composed of a pyrometer (4), a thermocouple measuring point (d), a pressure transmitter (m), a model prediction (MPC) controller (9) and an output device (10); wherein the pyrometer (4) monitors the sample temperature in a non-contact manner, the thermocouple measuring point (d) directly monitors the internal temperature of the thermogravimetric furnace (11), the pressure transmitter (m) is located at the bottom of the thermogravimetric furnace (11) and monitors the internal pressure of the thermogravimetric furnace (11), and the output device (10) records and outputs the test parameters; the control and recording unit controls the aperture opening, the xenon lamp power, the number of xenon lamps, the flow meter and the auxiliary electric power through the MPC controller (9) to achieve control of the temperature, heating rate, temperature uniformity and the thermogravimetric platform test process; The atmosphere control unit is composed of a gas detector interface (k1), a gas detector (12), a vacuum pump interface (k2), a vacuum pump (13), a valve (14), a water tank (16), an Ar gas tank (17), a water flow meter (18), an outlet gas flow meter (19), a purge gas flow meter (20) and a steam generator (21); wherein the Ar gas tank (17) is connected to the secondary air inlet (g) through the outlet gas flow meter (19) and the purge gas flow meter (20), and the water-cooled quartz window (6) is cooled and cleaned by the air intake rotating jet purge; the bottom of the thermogravimetric furnace body (11) is respectively provided with a gas detector interface (k1) and a vacuum pump interface (k2); at the vacuum pump interface (k2 ) is provided with a valve (14) on the connecting pipeline between the Ar gas tank (17) and the outlet gas flowmeter (19); the gas from the Ar gas tank (17) and the outlet gas flowmeter (19) can also be mixed with the water from the water tank (16) and the water flowmeter (18) to enter the steam generator (21), thereby obtaining water vapor of different humidity and temperature and entering the primary air inlet (e) located at the top of the thermogravimetric furnace body (11); thermogravimetric testing under different vacuum degrees can be achieved by connecting the vacuum pump (13) via the vacuum pump interface (k2) at the bottom of the thermogravimetric furnace body (11), and component analysis can be performed by connecting the gas detector (12) via the gas detector coupling interface (k1); the atmosphere control unit realizes the acquisition of vacuum, 0-95% relative humidity, and inert gas atmosphere through the valve and vacuum pump.

2. The thermogravimetric analyzer according to claim 1, characterized in that: The working process of the thermogravimetric analyzer is a direct heating mode and an indirect heating mode.

3. The thermogravimetric analyzer according to claim 2, characterized in that: In the direct heating mode, the flange (f) is first opened, the lifting platform (22) is raised, the composite heat absorbing plate (8) is removed, the test sample is placed flat in the crucible on the sample balance arm (j1), the lifting platform (22) is lowered, and the flange (f) is closed to achieve a sealed connection between the CPC secondary concentrator (7) and the thermogravimetric furnace body (11); after that, the power is turned on and the thermogravimetric heating program is set, the MPC controller (9) automatically sets the power supply and the number of short arc xenon lamps to be turned on in the adjustable bracket (3), the xenon lamp power and the opening of the adjustable aperture (1), the light source generated by the xenon lamp passes through the ellipsoidal concentrator (2) and is projected onto the plane reflector (5), and the concentrated solar light spot is vertically projected onto the sample surface through the water-cooled quartz window (6) to achieve direct heating; According to the set atmosphere and flow rate, the MPC controller (9) sets the temperature of the steam generator (21), the flow rate of the water flow meter (18), the outlet gas flow meter (19), and the vacuum degree of the vacuum pump connected via the vacuum pump interface (k2); under the arrangement of the secondary air inlet (g) and the primary air inlet (e), the air intake presents a "four-corner tangential circle" rotating flow, and the heating chamber structure of the thermogravimetric furnace body makes the flow in the central area stable; During the test, the sample balance arm (j1) and the reference balance arm (j2) are each connected to a balance in a balance chamber (15), and the output weight signal is the weight difference between the sample arm and the reference arm, thereby directly obtaining the thermogravimetric curve of the sample and eliminating the thermal expansion and buoyancy effects of the balance arm; through the thermocouple measuring points (d) in the sample arm and the reference arm, the temperature of the bottom of the sample, the reference temperature, and the temperature difference between the two are measured in real time to obtain a differential thermal curve, and the heat flow curve is automatically calculated in combination with the standard calibration file; at the same time, the measured temperature of the bottom of the sample is fed back to the MPC controller (9), and the number of xenon lamps, the power of the xenon lamps, and the opening parameters of the adjustable aperture (1) are adjusted according to the set temperature rise program; The pyrometer (4) measures the temperature of the front surface of the sample and feeds back the temperature difference of the bottom temperature of the sample to the MPC controller (9) to adjust the air inlet flow rate; thereby increasing the temperature uniformity inside the thermogravimetric furnace (11); during the test, the thermocouple measuring point (d) simultaneously monitors the edge temperature of the thermogravimetric furnace, and the pressure transmitter (m) monitors the internal pressure of the thermogravimetric furnace. In an emergency, the adjustable aperture (1) can be closed and the valve (14) opened to release the pressure to ensure the safety of the thermogravimetric furnace (11); the outlet gas in the thermogravimetric furnace (11) can be further analyzed after flowing out through the gas detector interface (k1).

4. The thermogravimetric analyzer according to claim 2, characterized in that: In the indirect heating mode, first open the flange (f), lift the lifting platform (22), place the composite heat absorbing plate (8), place the test sample flat in the crucible on the sample balance arm (j1), lower the lifting platform (22), and close the flange (f); then turn on the power and set the thermal reheating program, the MPC controller (9) automatically sets the power supply and the number of short arc xenon lamps and the power of the xenon lamps to be turned on in the adjustable bracket (3), the light source generated by the short arc xenon lamp passes through the ellipsoidal concentrator (2) and is projected onto the plane reflector (5), and the concentrated solar light spot is vertically projected onto the composite absorber through the water-cooled quartz window (6). The upper surface of the hot plate (8) is indirectly heated; the swirl purge gas entering the secondary air inlet (g) from the Ar gas tank (17) and the purge gas flow meter (20) cools the water-cooled quartz window (6) and is further heated by the foam ceramic structure on the upper layer of the composite heat absorbing plate (8), enters the foam ceramic air duct (b) in the thermogravimetric furnace body (11) through the side flow channel, and flows out through the foam ceramic air duct outlet (h), indirectly heating the side and bottom surfaces of the sample; the electric heating device (c) on the lower side of the thermogravimetric furnace body (11) is turned on, and also indirectly heating the side and bottom surfaces of the sample; According to the set atmosphere and flow rate, the MPC controller (9) sets the temperature of the steam generator (21), the flow rate of the water flow meter (18), the outlet gas flow meter (19), and the vacuum degree of the vacuum pump connected through the vacuum pump interface (k2); under the arrangement of the primary air inlet (e), the air intake presents a "four-corner tangential circle" rotating flow, making the flow in the center area stable and the system stability better; During the test, the sample balance arm (j1) and the reference balance arm (j2) are each connected to a balance in a balance chamber (15), and the output weight signal is the weight difference between the sample arm and the reference arm, so as to directly obtain the thermogravimetric curve of the sample and eliminate the thermal expansion and buoyancy effect of the balance arm; by embedding thermocouple measuring points (d) in the sample arm and the reference arm, the temperature of the bottom of the sample, the reference temperature and the temperature difference between the two are measured in real time to obtain a differential thermal curve, and the heat flow curve is calculated by combining the calibration file; at the same time, the measured temperature of the bottom of the sample is fed back to the MPC controller (9), and the number of arc xenon lamps, the power of the xenon lamps, the height of the adjustable bracket, the opening of the adjustable diaphragm (1), and the electric current are adjusted according to the set temperature rise program. The power of the heating device (c), the parameters of the outlet gas flow meter (19) and the purge gas flow meter (20); the thermocouple measuring point (d) automatically measures and records the edge temperature of the thermogravimetric furnace (11), and feeds back the temperature difference of the bottom temperature of the sample to the MPC controller (9) to adjust the inlet flow rate and the electric heating power parameters, so as to achieve uniform heating of the test sample inside the thermogravimetric furnace (11); during the test, the thermocouple measuring point (d) simultaneously monitors the edge temperature of the thermogravimetric furnace (11), and the pressure transmitter (m) monitors the internal pressure of the thermogravimetric furnace (11). In an emergency, the adjustable aperture (1), the electric heating, and the valve (14) can be closed to release pressure to ensure the safety of the thermogravimetric furnace (11).

5. The thermogravimetric analyzer according to claim 1, characterized in that: An ellipsoidal condenser is arranged with a short-arc xenon lamp at the focal position.

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