Aerosol thermal desorption device, aerosol thermal desorption system and method

Abstract

The aerosol thermal desorption device comprises a porous pipeline, a heating part, an inner shell, an adsorbent and an outer shell which are sequentially distributed from inside to outside, the porous pipeline is used for receiving aerosol, and the inner shell is provided with a channel for aerosol volatile matter to pass through. The invention further relates to an aerosol thermal desorption system and method. According to the aerosol thermal desorption device, heating and adsorption are integrated, the heating component is arranged on the outer side of the porous pipeline, so that the whole aerosol thermal desorption device forms a temperature gradient from inside to outside when the heating component is heated, the temperature gradient enables aerosol conveyed by the porous pipeline to form an organic steam gradient, rapid evaporation is achieved, and the thermal desorption efficiency is improved. Therefore, rapid condensation can be realized only by matching with heat dissipation equipment for heat dissipation, and the adsorption efficiency of the adsorbent is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pre-processing of aerosol detection, and in particular to an aerosol thermal desorption device, an aerosol thermal desorption system and a method. Background Art

[0002] Thermal desorption technology is widely used in many industries, such as in atmospheric physics and chemistry for basic research on the volatility of organic aerosols. The principle of this technology is to use the characteristics of different organic substances that evaporate rapidly at characteristic temperatures related to vapor pressure. By heating the atmospheric aerosol to a certain temperature, organic matter with higher saturated vapor pressure preferentially enters the gas phase and is removed by the adsorbent, while organic matter with lower saturated vapor pressure remains in the particle phase. A detection instrument is placed after the heating device and the adsorption device, and by controlling the temperature change, the physical and chemical properties of the volatile residues at different temperatures can be obtained.

[0003] Currently, commercial thermal desorbers have an adsorption tube behind the heating tube. There is a certain distance between the heating tube and the adsorption tube. Due to heat loss, the temperature of the aerosol sample in the adsorption tube drops, causing some of the volatilized organic matter to re-condense into the particle phase, resulting in significant deviations in the measurement results. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide an aerosol thermal desorption device to solve the problem that there is a certain distance between the heating tube and the adsorption tube, the temperature of the aerosol sample gas in the adsorption tube drops due to heat loss, causing some of the volatilized organic matter to re-condense into the particle phase, thereby causing significant deviations in the measurement results.

[0005] Another object of the present invention is to provide an aerosol thermal desorption system to achieve integration of aerosol heating and adsorption, improve desorption efficiency, and improve the accuracy of measurement results.

[0006] Another object of the present invention is to provide an aerosol thermal desorption method to achieve integration of aerosol heating and adsorption, improve desorption efficiency, and improve the accuracy of measurement results.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: An aerosol thermal desorption device comprises a porous pipe, a heating component, an inner shell, an adsorbent and an outer shell which are sequentially distributed from the inside to the outside. The porous pipe is used to receive the aerosol, and the inner shell has a channel for aerosol volatiles to pass through.

[0008] As a preference, the porous pipe, the heating component, the inner shell, the adsorbent and the outer shell are all coaxially arranged.

[0009] As a preferred embodiment, the heating component includes a heating coil and a lead wire. The heating coil is wrapped around the outer wall of the porous pipe, the heating coil is in contact with the outer wall of the porous pipe, the heating coil is fixedly connected to the outer shell, one end of the heating coil is connected to the lead wire, and the lead wire is used to connect to a relay and a 220V AC power supply respectively.

[0010] An aerosol thermal desorption system comprises a heat dissipation unit, a power supply unit and an aerosol thermal desorption device; a porous pipe is used to receive aerosol; The heating component heats the aerosol thermal desorption device so that a coaxial temperature gradient centered on the porous pipe is generated, and the aerosol is volatilized by the coaxial temperature gradient to form an organic vapor gradient; The heat dissipation unit can dissipate heat for the aerosol thermal desorption device, so as to condense the organic vapor located in the adsorbent; and the power supply unit supplies power to the heat dissipation unit and the heating component respectively.

[0011] As a preferred embodiment, the aerosol thermal desorption system is characterized by: further comprising a box, wherein the heat dissipation unit, the power supply unit and the aerosol thermal desorption device are all arranged in the box; The heat dissipation unit includes a blowing unit and an exhaust unit, which are symmetrically distributed in the box; the blowing unit can draw air outside the box and blow it toward the aerosol thermal desorption device, and the exhaust unit can draw air inside the box and blow it outside the box. Both the blowing unit and the exhaust unit are connected to the power supply unit.

[0012] As a preference, the system also includes a first switching unit, one end of which is connected to one end of the porous pipe, the first switching unit is used to receive the aerosol sampled by the sampling head and transmit the aerosol to the porous pipe or to the detection instrument, and the first switching unit is connected to the power supply unit.

[0013] As a preference, the system also includes a second switching unit, which is respectively connected to the other end of the porous pipe and the first switching unit, and is used to receive the aerosol after thermal desorption transmitted by the porous pipe and the ambient state aerosol transmitted by the first switching unit. The second switching unit can switch and transmit the aerosol after thermal desorption and the ambient state aerosol to the detection instrument, and the second switching unit is connected to the power supply unit.

[0014] As a preferred embodiment, the system further comprises a temperature sensor, the outer shell and the porous pipe are both provided with mounting holes, and the detection end of the temperature sensor is inserted from the mounting hole of the outer shell into the mounting hole of the porous pipe.

[0015] As a preference, the system also includes a control unit, which is respectively connected to the heating component, the power supply unit, the heat dissipation unit and the temperature sensor. The control unit controls the heating component and the heat dissipation unit to adjust the temperature of the aerosol thermal desorption device according to the sample gas temperature detected by the temperature sensor.

[0016] An aerosol thermal desorption method, using an aerosol thermal desorption device, the method comprises the following steps: S1: Collect ambient aerosols through the aerosol sampling head; S2: transport of ambient aerosol to the porous pipe; S3: heating by a heating component to form a coaxial temperature gradient between the porous pipe and the shell, and the coaxial temperature gradient causes the aerosol transmitted by the porous pipe to evaporate gradiently to form an organic vapor gradient; S4: adsorbent absorbs organic vapor; S5: The aerosol thermal desorption device is cooled by a heat dissipation unit, so that the organic vapor absorbed by the adsorbent is condensed, thereby completing the thermal desorption process of the aerosol.

[0017] In general, the present invention has the following advantages: 1. The aerosol thermal desorption device of the present invention realizes the integration of heating and adsorption. By arranging the heating component on the outside of the porous pipe, the entire aerosol thermal desorption device forms a temperature gradient from the inside to the outside when the heating component is heated. The temperature gradient causes the aerosol transmitted by the porous pipe to form an organic vapor gradient, thereby realizing rapid evaporation of the aerosol. The adsorbent adsorbs organic matter with a high saturated vapor pressure. Therefore, rapid condensation can be achieved by simply cooperating with an external heat dissipation device to dissipate heat, thereby improving the adsorption efficiency of the adsorbent.

[0018] 2. The aerosol thermal desorption system of the present invention realizes the integration of heating and adsorption. The heating component of the aerosol thermal desorption device is used for heating, so that the entire aerosol thermal desorption device forms a temperature gradient from the inside to the outside when the heating component is heated. The temperature gradient causes the aerosol transmitted by the porous pipe to form an organic vapor gradient, thereby realizing rapid evaporation. The heat dissipation unit cooperates with the outer shell to dissipate heat, thereby realizing rapid condensation and high desorption efficiency.

[0019] 3. The aerosol thermal desorption system of the present invention realizes precise temperature monitoring and control. By arranging the heating component and the heat dissipation unit in the box, the heat is not easily dissipated, thereby realizing a rapid response to heating and cooling needs; through the cooperation of the heating component, the heat dissipation unit, the control unit and the temperature sensor, the temperature of the aerosol thermal desorption device is monitored and controlled in real time and precisely, thereby realizing the purpose of automatically heating the sample gas in the aerosol thermal desorption device to a preset temperature value.

[0020] 4. The aerosol thermal desorption system of the present invention realizes aerosol measurement in an ambient state and a thermal desorption state through a first switching unit and a second switching unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the structural schematic diagram of the aerosol thermal desorption system; Figure 2is a cross-sectional view of an aerosol thermal desorption device; Figure 3 It is a top view of the aerosol thermal desorption device; Figure 4 Schematic diagram of the top cover and bottom cover of the housing; Among them, 1 is the first Y-shaped tube, 2 is the first solenoid valve, 3 is the second solenoid valve, 4 is the heating coil, 5 is the first fan, 6 is the second fan, 7 is the supporting ring, 8 is the 24V DC power supply, 9 is the 220V AC power supply, 10 is the temperature sensor, 11 is the relay, 12 is the control circuit board, 13 is the data acquisition unit, 14 is the aerosol thermal desorption device, 15 is the third fan, 16 is the control and display unit, 17 is the fourth fan, 18 is the supporting beam, 19 is the second Y-shaped tube, 20 is the porous pipe, 21 is the top cover, 22 is the outer shell, 23 is the adsorbent, 24 is the inner shell, and 25 is the bottom cover. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below in conjunction with specific implementation methods.

[0023] Embodiment 1 This example provides an aerosol thermal desorption device 14, the internal structure and function of the aerosol thermal desorption device 14 are as follows: Figure 2-4 As shown, the aerosol thermal desorption device 14 includes a porous pipe 20, a heating component, an inner shell 24, an adsorbent 23 and an outer shell 22, which are sequentially arranged from the inside to the outside. The outer shell 22 includes a cylindrical shell, a top cover 21 and a bottom cover 25. The top cover 21 and the bottom cover 25 are both disc-shaped. The outer shell 22, the top cover 21 and the bottom cover 25 form a sealed assembly through threaded engagement to ensure that the heat generated by the heating coil 4 is not easily dissipated and the internal gas is not leaked; the top cover 21 and the bottom cover 25 are both made of stainless steel, and their structure is as shown in FIG. Figure 4As shown; the top cover 21 is provided with two threaded openings, through which the lead wires of the heating coil 4 and the upper end of the porous pipe 20 are fixed, and a convex shell slightly smaller than the inner diameter of the inner shell 24 is provided on the inner side for fixing the upper end of the inner shell 24; the bottom cover 25 is provided with a threaded opening, through which the lower end of the porous pipe 20 is fixed, and a convex shell slightly smaller than the inner diameter of the inner shell 24 is provided on the inner side for fixing the lower end of the inner shell 24. The two ends of the porous pipe 20 are fixed to the top cover 21 and the bottom cover 25 respectively through joints. The porous pipe 20 is made of stainless steel with a diameter of 3 / 4 inches to ensure that the sample gas (aerosol, obtained by sampling with an aerosol sampling head) stays for a long enough time. Many circular holes are evenly opened on the pipe wall from the top cover 21 to the bottom cover 25. The diameter of the circular holes is 1 cm to ensure that the volatilized substances can leave the sample gas in the direction of the concentration gradient; the heating component is a heating coil 4, which fits around the outer wall of the porous pipe 20 so that the heating coil 4 is coaxial with the porous pipe to ensure that the heat generated by the heating coil 4 can be transferred in time and heat the sample gas; the heating coil 4 It is a spring heating coil, and the upper end of the spring heating coil has a lead, which is fixed to the top cover 21 through a joint, and the lead is used to connect to the relay 11 and the 220V AC power supply 9 respectively; by arranging the heating component in this way, the heating component is coaxial with the porous pipe 20, and the porous pipe 20 is fully heated. When the heating component is heated, the entire aerosol thermal desorption device 14 forms a temperature gradient from the inside to the outside. The temperature gradient makes the aerosol transmitted by the porous pipe 20 form an organic vapor gradient, realizing rapid evaporation. It only needs to cooperate with the heat dissipation device and the heat dissipation adsorbent to realize rapid condensation adsorption, thereby improving the adsorption efficiency of the adsorbent 23, that is, improving the aerosol thermal desorption efficiency.

[0024] The inner shell 24 is located outside the porous pipe 20 and the heating coil 4, and the annular gap between the porous pipe 20 and the inner shell 24 is defined as a heating layer; a convex shell slightly smaller than the inner diameter of the inner shell 24 is provided on the inner side of the top cover 21 and the bottom cover 25, and the two ends of the inner shell 24 are respectively fixed on the convex shells of the top cover 21 and the bottom cover 25; the inner shell 24 is made of stainless steel to form a cylindrical grid, and the mesh of the grid is a channel for aerosol volatiles to pass through, and the mesh diameter is 4mm; the outer shell 22 is located outside the inner shell 24, and the annular gap between the inner shell 24 and the outer shell 22 is defined as an adsorption layer, which is used to place a columnar activated carbon adsorbent 23 (adsorbent 23) with a diameter of 6mm. The aerosol in the porous pipe 20 is heated and evaporated by the heating coil 4. When the volatiles leave the sample gas in the direction of the concentration gradient, they pass through the heating layer and enter the adsorption layer and are absorbed by the activated carbon adsorbent 23.

[0025] The porous pipe 20 of the present embodiment can obtain environmental aerosols through an external aerosol sampling head, and the aerosol sampling head can be a PM10 / PM2.5 / PM1 sampling head / TSP cutting head.

[0026] In some embodiments, the porous pipe 20, the heating component, the inner shell 24, the adsorbent 23 and the outer shell 22 are all coaxially arranged. By coaxially arranging the porous pipe 20, the heating component, the inner shell 24, the adsorbent 23 and the outer shell 22, the aerosol thermal desorption device 14 heats the aerosol in the central area, and the aerosol volatilizes to produce a coaxial organic vapor gradient from the inside to the outside, and the heat generated by the heating component forms a temperature gradient. When the above-mentioned components are in a non-coaxial state, a temperature gradient extending from the heating component to the surrounding area will be formed, and the aerosol volatilizes to produce an organic vapor gradient centered on the heating component, causing the adsorbent 23 to absorb volatiles unevenly, and the aerosol thermal desorption effect will be slightly reduced. Therefore, by coaxially arranging the above-mentioned components, the aerosol thermal desorption efficiency is the highest.

[0027] In summary, the aerosol thermal desorption device 14 in this embodiment sets the heating component on the outside of the porous pipe 20, so that the entire aerosol thermal desorption device 14 forms a temperature gradient from the inside to the outside when the heating component is heated. The temperature gradient causes the aerosol transmitted by the porous pipe 20 to form an organic vapor gradient, thereby realizing rapid evaporation of the aerosol. The adsorbent 23 adsorbs organic matter with a higher saturated vapor pressure. Therefore, rapid condensation can be achieved by simply cooperating with an external heat dissipation device to dissipate heat, thereby improving the adsorption efficiency of the adsorbent 23.

[0028] Embodiment 2 like Figure 1 As shown, this example provides an aerosol thermal desorption system, including a box, an aerosol thermal desorption device 14, a first switching unit, a second switching unit, a heat dissipation unit, a temperature sensor 10, a data acquisition unit 13, a control circuit board 12, a control and display unit 16, and a power supply unit; wherein the control circuit board 12, the data acquisition unit 13 and the control and display unit 16 constitute a control unit, the aerosol thermal desorption device 14 is used to heat the sample gas to a set temperature and adsorb the volatile organic matter; the first switching unit and the second switching unit are used to perform thermal desorption state and environmental state. Switching, the heat dissipation unit is used to cool down the aerosol thermal desorption device 14 to reach the target temperature; the temperature sensor 10 is used to measure the temperature data in the aerosol thermal desorption device 14, for example, the temperature sensor 10 is used to monitor the sample gas temperature in the aerosol thermal desorption device 14 in real time, the data acquisition unit 13 is used for data conversion, converting the data detected by the temperature sensor 10 and sending it to the control and display unit; the control and display unit 16 is used to control the operation of the entire system, receive user input information and display the operating status; the power supply unit is used to meet the power requirements of the electronic components in the device and control the on and off of the circuit.

[0029] The box body is made of stainless steel; the box body is provided with a movable door, and the control and display unit 16 is fixed on the outer side of the movable door of the box body.

[0030] The power supply unit includes a 24V DC power supply 8, a 220V AC power supply 9, and a relay 11. The 24V DC power supply 8 and the 220V AC power supply 9 are arranged on the inner wall of the box, and the relay 11 is arranged on the side of the box. The neutral line, live line, and ground line of the 24V DC power supply 8 are electrically connected to the 220V AC power supply 9 to supply 24V DC power to the main electrical appliances. The relay 11 is electrically connected to the 220V AC power supply 9, and the heating power of the heating coil 4 is controlled by controlling the on and off of the channel circuit of the control circuit board 12.

[0031] The aerosol thermal desorption device 14 is fixed to the inner wall of the box body through the support ring 7 and the support beam 18. The relay 11 is electrically connected to the control circuit board 12, the control circuit board 12 is electrically connected to the control and display unit 16, the data acquisition unit 13 receives the temperature monitoring data sent by the temperature sensor, the control and display unit 16 calculates the heating time of the heating coil 4 according to the temperature data obtained by the temperature data acquisition unit 13, and the control circuit board 12 changes the heating power of the heating coil 4 by controlling the on and off of the relay 11 to achieve the set temperature.

[0032] A mounting hole corresponding to the diameter of the temperature sensor 10 is provided in the center of the side wall of the housing 22 and in the center of the porous pipe 20 for fixing the temperature sensor 10 .

[0033] The heating coil 4 is connected to leads, which are electrically connected to the relay 11 and the 220V AC power supply respectively. The relay 11 is electrically connected to the control circuit board 12, and the control circuit board 12 is electrically connected to the control and display unit 16. The control and display unit 16 calculates the heating time of the heating coil 4 according to the temperature data obtained by the data acquisition unit 13. The control circuit board 12 changes the heating power of the heating coil 4 by controlling the on and off of the relay 11 to achieve the set temperature.

[0034] The first switching unit includes a first Y-shaped tube 1, a first solenoid valve 2, and a second solenoid valve 3, and the second switching unit includes a second Y-shaped tube 19. The first Y-shaped tube 1 is connected to the first solenoid valve 2 and the second solenoid valve 3 respectively through steel pipes, the first solenoid valve 2 is connected to the inlet of the porous pipe 20 in the aerosol thermal desorption device 14 through a steel pipe, the outlet of the porous pipe 20 in the aerosol thermal desorption device 14 is connected to the second Y-shaped tube 19 through a steel pipe, the second solenoid valve 3 is connected to the second Y-shaped tube 19 through a steel pipe, and the two airflows are combined into one through the second Y-shaped tube 19; the first solenoid valve 2 is connected to the second solenoid valve 20 through a steel pipe, and the two airflows are combined into one through the second Y-shaped tube 19; The magnetic valve 2 and the second solenoid valve 3 are fixed to the inner side of the box body through a support frame; both solenoid valves are electrically connected to the control circuit board 12, the control circuit board 12 is electrically connected to the control and display unit 16, and the control circuit board 12 is fixed to the inner wall of the box body through screws, nuts and other components; by controlling the opening and closing of the two solenoid valves, the two air paths are opened alternately and cyclically, when one air path is opened, the other air path is in a closed state, that is, the switching of the environmental state and the state of the aerosol thermal desorption device 14 is realized, and the opening and closing states of the two solenoid valves are displayed on the control and display unit 16.

[0035] The heat dissipation unit includes a first fan 5, a second fan 6, a third fan 15 and a fourth fan 17. Two circular holes with the same size as the fans are symmetrically arranged on both sides of the box. The fans are arranged on both sides of the box by screws and nuts. The first fan 5, the second fan 6, the third fan 15 and the fourth fan 17 blow in the same direction, which can take away the heat in the box in time, further improving the heat dissipation efficiency of the cooling and heat dissipation unit. The first fan 5, the second fan 6, the third fan 15 and the fourth fan 17 are all electrically connected to the control circuit board 12, and the control circuit board 12 is electrically connected to the control and display unit 16. The control and display unit 16 calculates the wind speed of the four fans (the first fan 5, the second fan 6, the third fan 15 and the fourth fan 17) according to the temperature data obtained by the temperature data acquisition unit 13. The control circuit board 12 controls the wind speed of the four fans and cooperates with the heating coil 4 to control the temperature in the aerosol thermal desorption device 14 to reach the set temperature. When the temperature in the aerosol thermal desorption device 14 is higher than the set temperature, the control and display unit 16 increases the speed of the four fans and reduces the heating power of the heating coil 4. When the temperature in the aerosol thermal desorption device 14 is lower than the set temperature, the control and display unit 16 reduces the speed of the four fans and increases the heating power of the heating coil 4. Through this method, the heating capacity and cooling capacity in the aerosol thermal desorption device 14 are dynamically balanced to achieve a rapid response to changes in the set temperature.

[0036] The temperature sensor 10 is used in conjunction with the data acquisition unit. The temperature sensor 10 is arranged on the aerosol thermal desorption device 14. The temperature sensor 10 is fixed to the outer shell 22 by a sealant so that the detection head of the temperature sensor 10 is located at the center of the circular section of the porous pipe 20 to obtain the temperature of the sample gas in the middle of the cross section of the porous pipe 20. The temperature data acquisition unit 13 is fixed to the inner wall of the box by screws, nuts and other components. The temperature data acquisition unit 13 is electrically connected to the end lead of the temperature sensor 10. The temperature data acquisition unit 13 is electrically connected to the control and display unit 16 and the 24V DC power supply. In this example, the temperature sensor 10 is used to measure the sample gas temperature. The control and display unit 16 reads the data of the temperature data acquisition unit 13, adjusts the heating power of the heating coil 4 and the speed of the four fans, and can make the temperature in the aerosol thermal desorption device 14 automatically reach the preset value.

[0037] The aerosol thermal desorption system provided in this embodiment includes two gas paths and three types of circuits, as follows: Gas circuit 1: first Y-shaped tube 1—first solenoid valve 2—aerosol thermal desorption device 14—first Y-shaped tube 1. Used for heating and adsorption post-processing of sample gas.

[0038] Gas circuit 2: first Y-shaped tube 1—second solenoid valve 3—first Y-shaped tube 1. Used to obtain environmental sample gas.

[0039] Circuit 1 is used for converting 220V AC power into 24V DC power, and comprises a 220V AC power supply 9 and a 24V DC power supply 8.

[0040] Circuit 2 is used to power 24V DC electrical appliances, including: 24V DC power supply 8—control and display unit 16, 24V DC power supply 8—control circuit board 12—first solenoid valve 2, second solenoid valve 3, 24V DC power supply 8—control circuit board 12—first fan 5, second fan 6, third fan 15 and fourth fan 17, 24V DC power supply 8—control circuit board 12—relay 11, 24V DC power supply 8—temperature data acquisition unit 13—temperature sensor 10.

[0041] Circuit three supplies power to 220V AC electrical appliances, including: 220V AC power supply 9—relay 11—heating coil 4.

[0042] In this embodiment, the heating coil 4 is electrically connected to the relay 11 and the 220V AC power supply 9 through wires; the relay 11 is electrically connected to the control circuit board 12 through wires; the first solenoid valve 2 and the second solenoid valve 3 are electrically connected to the control circuit board 12 through wires; the four fans are electrically connected to the control circuit board 12 through wires; the control circuit board 12 is electrically connected to the control and display unit 16 through data lines; the temperature sensor 10 is electrically connected to the temperature data acquisition unit 13 through data lines; the temperature data acquisition unit 13 is electrically connected to the control and display unit 16 through data lines. The control and display unit 16 controls the opening and closing states of the first solenoid valve 2 and the second solenoid valve 3, reads the temperature data of the temperature data acquisition unit 13, and realizes accurate monitoring and control of the gas temperature in the aerosol thermal desorption device 14 by adjusting the heating power of the heating coil 4 and the rotation speed of the four fans, and displays and records the operating state of the device and the temperature in the aerosol thermal desorption device 14.

[0043] The parts not mentioned in this embodiment are the same as those in the first embodiment.

[0044] Embodiment 3 This embodiment provides an aerosol thermal desorption method, using an aerosol thermal desorption device 14, and the method includes the following steps: S1: Collecting ambient aerosols through an aerosol sampling head. The aerosol sampling head may be a PM10, PM2.5, PM1 sampling head or a TSP cutting head. The ambient aerosols are collected through the aerosol sampling head and then transmitted to the porous pipe 20 of the aerosol thermal desorption device 14; S2: transmitting the ambient aerosol to the porous pipe 20; S3: A coaxial temperature gradient is formed between the porous pipe 20 and the outer shell 22 by heating through a heating component. The coaxial temperature gradient causes the aerosol gradient evaporated by the porous pipe 20 to form an organic vapor gradient. The heating component can also be other heating products surrounding the outer wall of the porous pipe 20. It is only necessary to heat the porous pipe 20 in the axial direction without affecting the aerosol in the porous pipe 20 to pass through the through hole connecting the porous pipe 20 to the outside after being heated and volatilized.

[0045] S4: the adsorbent 23 absorbs the organic vapor, and the aerosol moves from the porous pipe 20 to the inner shell 24 after being heated and volatilized, and then moves from the inner shell 24 to the adsorbent 23 to be adsorbed; S5: The aerosol thermal desorption device 14 is cooled by the heat dissipation unit, so that the organic vapor absorbed by the adsorbent 23 is condensed, and the thermal desorption process of the aerosol is completed. Specifically, the heat dissipation unit controls the temperature of the shell 22 and the adsorbent 23 by blowing air to the shell 22 of the aerosol thermal desorption device 14, thereby reducing the temperature at the adsorbent 23, so that the volatile matter of the aerosol is adsorbed by the adsorbent 23.

[0046] Through the method of this embodiment, the integration of aerosol heating and adsorption is achieved, the desorption efficiency is improved, and the accuracy of the measurement results is improved.

[0047] The parts not mentioned in this embodiment are the same as those in the first embodiment.

[0048] The first Y-tube and the second Y-tube in the above embodiment are existing three-way tubes, the first fan, the second fan, the third fan and the fourth fan are existing fan products, and the fan power can be selected according to needs; the first solenoid valve and the second solenoid valve are existing solenoid valve products, and the solenoid valves with corresponding opening accuracy can be selected according to needs; the relay, the control circuit board, the temperature sensor, the data acquisition unit and the control and display unit are all existing electronic components, which will not be elaborated here.

[0049] The principle of the above embodiment is: a temperature gradient is formed by heating in the central area (i.e., the porous pipe 20 of the aerosol thermal desorption device 14), and the temperature gradient heats the aerosol, causing the aerosol to volatilize and produce a coaxial organic vapor gradient from the inside to the outside; since the temperature is high inside and low outside, it is very conducive to the internal volatilization and external condensation of the aerosol, thereby generating a continuous organic vapor flow, realizing rapid evaporation and condensation of the aerosol, that is, the integration of heating and complete desorption; the heating coil 4 of the above embodiment is on the outer wall of the porous pipe 20 (i.e., the central area of ​​the aerosol thermal desorption device 14), and a unique heating structure that is permeable to organic vapor is realized through the high-density hole structure of the heating coil 4 and the internal steel pipe (porous pipe 20), thereby truly realizing that the organic vapor and temperature form a gradient from the inside to the outside, promoting the evaporation of the organic components to form an organic vapor gradient, while promoting the condensation of the organic vapor in the outermost desorption layer.

[0050] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. Aerosol thermal desorption device, characterized in that: The invention comprises a porous pipe, a heating component, an inner shell, an adsorbent and an outer shell which are sequentially distributed from the inside to the outside. The porous pipe is used for receiving aerosol, and the inner shell has a channel for aerosol volatiles to pass through.

2. The aerosol thermal desorption device according to claim 1, characterized in that: The porous pipe, the heating element, the inner shell, the adsorbent and the outer shell are all coaxially arranged.

3. The aerosol thermal desorption device according to claim 1, characterized in that: The heating component includes a heating coil and a lead wire. The heating coil surrounds the outer wall of the porous pipe, fits the outer wall of the porous pipe, is fixedly connected to the outer shell, and one end of the heating coil is connected to the lead wire, which is used to connect to a relay and a 220V AC power supply respectively.

4. Aerosol thermal desorption system, characterized by: It comprises a heat dissipation unit, a power supply unit and the aerosol thermal desorption device according to any one of claims 1 to 3; the porous pipe is used to receive the aerosol; The heating component heats the aerosol thermal desorption device so that a coaxial temperature gradient centered on the porous pipe is generated, and the aerosol is volatilized by the coaxial temperature gradient to form an organic vapor gradient; The heat dissipation unit can dissipate heat for the aerosol thermal desorption device, so as to condense the organic vapor located in the adsorbent; and the power supply unit supplies power to the heat dissipation unit and the heating component respectively.

5. The aerosol thermal desorption system according to claim 4, characterized in that: It also includes a box body, in which the heat dissipation unit, the power supply unit and the aerosol thermal desorption device are all arranged; The heat dissipation unit includes a blowing unit and an exhaust unit, which are symmetrically distributed in the box; the blowing unit can draw air outside the box and blow it toward the aerosol thermal desorption device, and the exhaust unit can draw air inside the box and blow it outside the box. Both the blowing unit and the exhaust unit are connected to the power supply unit.

6. The aerosol thermal desorption system according to claim 4, characterized in that: It also includes a first switching unit, one end of which is connected to one end of the porous pipe. The first switching unit is used to receive the aerosol sampled by the sampling head and transmit the aerosol to the porous pipe or to the detection instrument. The first switching unit is connected to the power supply unit.

7. The aerosol thermal desorption system according to claim 6, characterized in that: It also includes a second switching unit, which is respectively connected to the other end of the porous pipe and the first switching unit. The second switching unit is used to receive the aerosol after thermal desorption transmitted by the porous pipe and the ambient state aerosol transmitted by the first switching unit. The second switching unit can switch the transmission of the aerosol after thermal desorption and the ambient state aerosol to the detection instrument. The second switching unit is connected to the power supply unit.

8. The aerosol thermal desorption system according to claim 4, characterized in that: The invention also comprises a temperature sensor. The outer shell and the porous pipe are both provided with mounting holes. The detection end of the temperature sensor is inserted from the mounting hole of the outer shell into the mounting hole of the porous pipe.

9. The aerosol thermal desorption system according to claim 8, characterized in that: It also includes a control unit, which is respectively connected to the heating component, the power supply unit, the heat dissipation unit and the temperature sensor. The control unit controls the heating component and the heat dissipation unit to adjust the temperature of the aerosol thermal desorption device according to the sample gas temperature detected by the temperature sensor.

10. Aerosol thermal desorption method, characterized in that: Using the aerosol thermal desorption device according to any one of claims 1 to 3, the method comprises the following steps: S1: Collect ambient aerosols through the aerosol sampling head; S2: transport of ambient aerosol to the porous pipe; S3: heating by a heating component to form a coaxial temperature gradient between the porous pipe and the shell, and the coaxial temperature gradient causes the aerosol transmitted by the porous pipe to evaporate gradiently to form an organic vapor gradient; S4: adsorbent absorbs organic vapor; S5: The aerosol thermal desorption device is cooled by a heat dissipation unit, so that the organic vapor absorbed by the adsorbent is condensed, thereby completing the thermal desorption process of the aerosol.

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