Equipment for secondary thermal desorption and application
By adding thermally conductive liquid chambers and temperature-sensitive gas tubes in the cold trap device of the secondary thermal desorption equipment, the problem of decreasing refrigeration efficiency and aging caused by high-temperature heat conduction of semiconductor refrigeration sheets is solved, and higher refrigeration efficiency and longer service life are achieved, reducing maintenance costs.
Patent Information
- Application Number
- CN202510366821.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-06-20
AI Technical Summary
During the continuous operation of existing secondary thermal desorption equipment, the semiconductor refrigeration sheet at the cold trap excitation tube part decreases in refrigeration efficiency due to high temperature heat conduction, and accelerates the aging of thermoelectric materials, increasing the maintenance cost of the equipment.
A device for secondary thermal desorption is designed, and a thermally conductive liquid cavity is added in the cold trap device, and a temperature-sensitive gas tube is added next to the excitation tube. The change in the volume of the temperature-sensitive gas pushes the piston to move, changing the liquid level height of the thermally conductive liquid, thereby affecting the heat conduction state between the semiconductor cooling sheet and the metal excitation tube.
It improves the refrigeration efficiency, extends the aging cycle of thermoelectric materials, reduces the damage rate of semiconductor refrigeration sheets, and saves the use and maintenance costs of equipment.
Smart Images
Figure CN120177690A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of secondary thermal desorption, and specifically to an apparatus and application for secondary thermal desorption. Background Art
[0002] After the secondary thermal desorption apparatus performs primary thermal desorption on a TVOC (Total Volatile Organic Compounds) sample, the released organic compounds enter the pipeline and switching valve with the carrier gas, and are further enriched and concentrated at the excitation tube part of the cold trap (also called the focusing trap). Subsequently, through secondary heating of the cold trap excitation tube, the enriched organic compounds are released at a higher concentration and are transmitted with the carrier gas to the injection port of a gas chromatograph (GC) or a gas chromatograph-mass spectrometer (GC-MS) to complete the detection.
[0003] However, in the continuous working process of the existing secondary thermal desorption apparatus, the following situations exist at the excitation tube part of the cold trap during continuous low-temperature enrichment and high-temperature desorption of TVOC samples: Since the method of normal-temperature enrichment is adopted, low-melting-point substances in the cold trap excitation tube are prone to penetration. Therefore, generally, a semiconductor refrigerating sheet is installed at the cold trap part to accelerate the enrichment rate of TVOC in the excitation tube. After the apparatus completes the cooling and enrichment of TVOC, in order to release the enriched TVOC at a higher concentration, the excitation tube at the cold trap part also needs to be heated. During the heating process of the excitation tube, the high-temperature heat will be conducted to the semiconductor refrigerating sheet at the cold trap part. Since high temperature will cause the Seebeck coefficient and conductivity of the thermoelectric material to decrease, the refrigeration efficiency of the refrigerating sheet will be reduced; moreover, high temperature will also accelerate the aging process of the thermoelectric material, resulting in gradual degradation of its performance, which directly affects the service life of the semiconductor refrigerating sheet. Therefore, in practical applications, the damage rate of the semiconductor refrigerating sheet installed at the cold trap part is extremely high and needs to be replaced frequently, which greatly increases the use and maintenance costs of the apparatus.
[0004] Based on this, the present invention provides an apparatus and application for secondary thermal desorption to solve the above-mentioned technical problems. Summary of the Invention
[0005] The purpose of the present invention is to provide an apparatus and application for secondary thermal desorption to solve the problems raised in the above background art.
[0006] To achieve the above purpose, the present invention provides the following technical solutions:
[0007] The present invention provides an apparatus for secondary thermal desorption, comprising:
[0008] A cold trap device body, the cold trap device body is arranged on a cold trap heat dissipation seat, a fixed bracket is fixedly installed on the outside of the cold trap heat dissipation seat, a support plate is welded on the top of the fixed bracket, and the upper cold trap device body is arranged on the upper surface of the support plate;
[0009] Cold trap heat dissipation seat, the cold trap heat dissipation seat is composed of a heat dissipation body and a heat dissipation fan. A cavity is provided inside the cold trap device body, and a heat-conducting liquid is filled in the cavity. The cavity is connected to a liquid storage tank containing the heat-conducting liquid through pipeline 1, and the cavity is connected to a temperature-sensitive gas pipe through pipeline 2. A movable piston is provided inside pipeline 2, and the piston can be pushed by the temperature-sensitive gas expanding inside the temperature-sensitive gas pipe to change the liquid level height of the heat-conducting liquid in the cavity of the cold trap device body.
[0010] On both sides of the top of the cold trap device body, a metal excitation tube, a temperature-sensitive gas pipe and a temperature sensor are installed respectively. A heating electric wire is wound around the metal excitation tube.
[0011] Preferably, at the end of one of the metal excitation tubes, there is a metal excitation tube port 1, and the metal excitation tube port 1 is connected to the first thermal desorption inlet gas pipeline of the TVOC sample or the carrier gas pipeline of the detection device through a switching valve.
[0012] At the end of the other metal excitation tube, there is a metal excitation tube port 2, and the metal excitation tube port 2 is connected to the outlet gas pipeline or another carrier gas pipeline of the detection device through a switching valve.
[0013] Preferably, the temperature-sensitive gas is sealed inside the temperature-sensitive gas pipe, and the temperature-sensitive gas pipe is connected to the pipeline with a piston through conduit 2. A pressure sensor is installed on the temperature-sensitive gas pipe.
[0014] Preferably, a semiconductor refrigeration chip is installed at the lower part of the cold trap device body, and the semiconductor refrigeration chip is connected to the heat dissipation body through a fixing bracket.
[0015] Preferably, the pressure sensor is electrically connected to the PLC control unit, the temperature sensor is electrically connected to the PLC control unit, and the semiconductor refrigeration chip is electrically connected to the PLC control unit.
[0016] Application of the equipment for secondary thermal desorption in the preparation of TVOC samples by low-temperature enrichment and high-temperature desorption.
[0017] Compared with the prior art, the beneficial effects of the present invention are:
[0018] In the cold trap device of the secondary thermal desorption equipment of the present invention, a design of a heat-conducting liquid cavity is added inside the cold trap device, and a temperature-sensing gas pipe is additionally installed beside the excitation tube for enriching TVOC. There is a temperature-sensing gas inside the temperature-sensing gas pipe that can expand and contract with temperature. The change in the volume of the temperature-sensing gas will push the piston of the pipeline connected thereto to move, thereby changing the liquid level height of the heat-conducting liquid in the cavity of the cold trap device body, thus affecting the heat conduction state between the semiconductor cooling sheet and the metal excitation tube. While the refrigeration efficiency is higher, the aging cycle of the thermoelectric material is effectively reduced, and the damage rate of the semiconductor refrigeration sheet installed in the cold trap part is greatly reduced, saving the use and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 is a schematic structural diagram of the equipment for secondary thermal desorption of the present invention;
[0020] Figure 2 is a sectional view of the equipment structure for secondary thermal desorption of the present invention.
[0021] In the figure: 1. Heat dissipation body; 2. Cold trap heat dissipation seat; 3. Pipeline 1; 4. Liquid storage tank; 5. Support plate; 6. Metal excitation tube port 1; 7. Temperature-sensing gas pipe; 8. Pipeline 2; 9. Cold trap device body; 10. Electric heating wire; 11. Pressure sensor; 12. Metal excitation tube; 13. Metal excitation tube port 2; 14. Cavity; 15. Heat dissipation fan; 16. Semiconductor refrigeration sheet; 17. Fixed bracket; 18. Temperature-sensing gas; 19. Piston; 20. Temperature sensor; 21. Heat-conducting liquid. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.
[0023] Embodiment, please refer to Figures 1 to 2 , the present invention proposes an equipment for secondary thermal desorption, including:
[0024] The cold trap device body 9 is arranged on the cold trap heat dissipation seat 2. A fixed bracket 17 is fixedly installed on the outside of the cold trap heat dissipation seat 2. A support plate 5 is welded to the top of the fixed bracket 17. The upper cold trap device body 9 is arranged on the upper surface of the support plate 5. The cold trap device body 9 forms a three-level support through the heat dissipation seat 2, the bracket 17, and the support plate 5. The key welds adopt the argon arc welding process. The modular design facilitates rapid disassembly and assembly in a low-temperature environment. The argon arc welding process reduces the risk of false welding and ensures the improvement of the structural stability under the working condition of -60°C;
[0025] Cold trap heat dissipation seat 2, the cold trap heat dissipation seat 2 is composed of a heat dissipation body 1 and a heat dissipation fan 15. There is a cavity 14 inside the cold trap device body 9, and a heat-conducting liquid 21 is filled in the cavity 14. The cavity 14 is connected to a liquid storage tank 4 containing heat-conducting liquid through a pipeline 1 3, and the cavity 14 is connected to a temperature-sensitive gas pipe 7 through a pipeline 2 8. And a movable piston 19 is provided inside the pipeline 2 8. The piston 19 can be pushed by the temperature-sensitive gas expanding inside the temperature-sensitive gas pipe 7 to change the liquid level height of the heat-conducting liquid 21 in the cavity 14 of the cold trap device body. The cavity 14 adopts a double-helix flow channel design, and the heat-conducting liquid 21 is selected as a silicone-based nanofluid. The liquid storage tank 4 is equipped with a magnetic float level gauge. The thermal conductivity of the nanofluid is improved, and the heat exchange path is extended in cooperation with the double-helix flow channel, reducing the temperature gradient and significantly improving the uniformity of TVOC capture.
[0026] On both sides of the top of the cold trap device body 9, a metal excitation tube 12, a temperature-sensitive gas pipe 7 and a temperature sensor 20 are installed respectively. A heating electric wire 10 is wound around the metal excitation tube 12. The temperature-sensitive gas pipe 7 adopts a capillary array structure. The surface of the piston 19 is coated with a polytetrafluoroethylene lubricating layer, so that the stroke can be extended. The capillary array enhances the temperature-sensitive response rate, and the polytetrafluoroethylene lubricating layer ensures that the piston moves without jamming at low temperatures, and the liquid level adjustment accuracy is higher.
[0027] In this embodiment, it should also be noted that a metal excitation tube port 1 6 is provided at the end of one side of the metal excitation tube 12. The metal excitation tube port 1 6 is connected to the first thermal desorption inlet pipeline of the TVOC sample or the carrier gas pipeline of the detection device through a switching valve. The metal excitation tube 12 adopts a variable diameter setting from φ6 to φ3mm. The electric heating wire 10 adopts a segmented power layout, with a higher surface load density. The variable diameter tube structure enhances the air flow disturbance and improves the heating efficiency. And the segmented power layout avoids local overheating, and realizes precise desorption in cooperation with PID control.
[0028] A metal excitation tube port 2 13 is provided at the end of the other side of the metal excitation tube 12. The metal excitation tube port 2 13 is connected to the outlet pipeline or another carrier gas pipeline of the detection device through a switching valve. Among them, the switching valve integrates a Hall position sensor, and the key flow path adopts a double ferrule joint to realize real-time feedback of the valve state through the Hall sensor. The electrochemically polished flow path reduces sample adsorption and has a lower cross-contamination rate.
[0029] In this embodiment, it should also be noted that a temperature-sensitive gas 18 is sealed inside the temperature-sensitive gas pipe 7, and the temperature-sensitive gas pipe 7 is connected to the pipeline with the piston 19 through a conduit 2. A pressure sensor 11 is installed on the temperature-sensitive gas pipe 7.
[0030] In this embodiment, it should also be noted that a semiconductor refrigeration sheet 16 is installed at the lower part of the cold trap device body 9. The semiconductor refrigeration sheet 16 is connected to the heat dissipation body 1 through a fixing bracket 17.
[0031] In this embodiment, it should also be noted that the pressure sensor 11 is electrically connected to the PLC control unit, the temperature sensor 20 is electrically connected to the PLC control unit, and the semiconductor refrigeration sheet 16 is electrically connected to the PLC control unit, which improves the system reliability, makes the temperature control accuracy higher, and the pressure fluctuation smaller.
[0032] The application of the equipment of the present invention for secondary thermal desorption in the scenarios of low-temperature enrichment and high-temperature desorption of TVOC sample preparation. Through the thermal expansion and contraction of the gas inside the temperature-sensitive gas tube 7 fixed on the cold trap device body, the position of the piston 19 in the pipeline is changed, thereby affecting the height of the heat-conducting liquid in the cavity 14 of the cold trap device body, and further changing the heat conduction state between the semiconductor cooling sheet and the metal excitation tube 12;
[0033] In summary, in the cold trap device of the cold trap part of the secondary thermal desorption equipment of the present invention, a design of adding a heat-conducting liquid cavity is adopted. At the same time, a temperature-sensitive gas tube is added beside the excitation tube for enriching TVOC. There is a temperature-sensitive gas inside the temperature-sensitive gas tube that can expand and contract with temperature. The change in the volume of the temperature-sensitive gas will push the piston of the pipeline connected thereto to move, thereby changing the liquid level height of the heat-conducting liquid in the cavity of the cold trap device body, and further affecting the heat conduction state between the semiconductor cooling sheet and the metal excitation tube. The refrigeration efficiency is higher, and at the same time, the aging cycle of the thermoelectric material is effectively reduced. The damage rate of the semiconductor refrigeration sheet installed in the cold trap part is greatly reduced, saving the use and maintenance costs.
[0034] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.
[0035] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. The present specification selects and specifically describes these embodiments to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.
Claims
1. A device for secondary thermal desorption, characterized in that: include: A cold trap device body (9), the cold trap device body (9) being arranged on a cold trap heat sink (2), a fixing bracket (17) being fixedly mounted on the outside of the cold trap heat sink (2), a support plate (5) being welded on the top of the fixing bracket (17), and the upper cold trap device body (9) being arranged on the upper surface of the support plate (5); A cold trap heat sink (2), the cold trap heat sink (2) comprising a heat sink (1) and a heat dissipation fan (15), a cavity (14) being provided inside the cold trap device body (9), and a heat-conducting liquid (21) being filled in the cavity (14), the cavity (14) being connected to a liquid storage tank (4) containing the heat-conducting liquid through a first pipeline (3), the cavity (14) being connected to a temperature-sensitive gas pipe (7) through a second pipeline (8), and a movable piston (19) being provided inside the second pipeline (8), the piston (19) being capable of being pushed by the temperature-sensitive gas expanded inside the temperature-sensitive gas pipe (7), and being used for changing the liquid level height of the heat-conducting liquid (21) in the cavity (14) of the cold trap device body. A metal excitation tube (12), a temperature-sensitive gas tube (7) and a temperature sensor (20) are installed on both sides of the top of the cold trap device body (9), and a heating wire (10) is wound around the metal excitation tube (12).
2. The device for secondary thermal desorption according to claim 1, characterized in that: A metal excitation tube port one (6) is provided at the end of the metal excitation tube (12) on one side, and the metal excitation tube port one (6) is connected to the first thermal desorption air inlet pipeline of the TVOC sample or the carrier gas pipeline of the detection equipment through a conversion valve. A second metal excitation tube port (13) is provided at the end of the other side metal excitation tube (12), and the second metal excitation tube port (13) is connected to an air outlet pipeline or another carrier gas pipeline of the detection device through a conversion valve.
3. The device for secondary thermal desorption according to claim 2, characterized in that: The temperature-sensitive gas pipe (7) has a temperature-sensitive gas (18) sealed inside it, and the temperature-sensitive gas pipe (7) is connected to a pipeline with a piston (19) through a second conduit, and a pressure sensor (11) is installed on the temperature-sensitive gas pipe (7).
4. The device for secondary thermal desorption according to claim 3, characterized in that: A semiconductor refrigeration sheet (16) is installed at the lower part of the cold trap device body (9), and the semiconductor refrigeration sheet (16) is connected to the heat sink (1) via a fixing bracket (17).
5. The device for secondary thermal desorption according to claim 4, characterized in that: The pressure sensor (11) is electrically connected to the PLC control unit, the temperature sensor (20) is electrically connected to the PLC control unit, and the semiconductor refrigeration sheet (16) is electrically connected to the PLC control unit.
6. Use of the device for secondary thermal desorption as claimed in any one of claims 1 to 5 in low-temperature enrichment and high-temperature desorption TVOC sample preparation.