A multi-point VOCs sampling and analysis system with high spatio-temporal resolution

Abstract

The present invention discloses a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, belonging to the technical field of waste gas treatment. The system includes a drainage pump, a plurality of sampling units, a sample retention device, an analytical instrument, and a purge gas storage device; the sampling unit includes a sampling head; the drainage pump is connected to the sampling head of each sampling unit through a plurality of pipelines; a sampling three-way valve is provided on the pipeline connecting each sampling head to the drainage pump; a plurality of sampling three-way valves are all connected to the sample retention device through pipelines; the sample retention device is connected to the analytical instrument through a pipeline; an analytical purge three-way valve is provided on the pipeline connecting the sample retention device to the analytical instrument; the analytical purge three-way valve is connected to the purge gas storage device through a pipeline; a front short-circuit three-way valve and a rear short-circuit three-way valve are respectively provided at the front and rear ends of the sample retention device, and the front short-circuit three-way valve and the rear short-circuit three-way valve are connected through a pipeline. The present invention has the advantages of high accuracy, high efficiency, convenience, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste gas treatment, relates to a sampling and analysis system, and particularly relates to a multi-point VOCs sampling and analysis system with high spatio-temporal resolution. Background Art

[0002] At present, the VOCs sampling and analysis system mainly uses multiple pipeline electric control switches, a communication structure and a sampling power unit connected in sequence through pipelines. By switching the electric control switches, multi-sampling point sampling detection and analysis can be realized, and multi-sampling point control switching can be carried out. After the detection and analysis of one sampling point are completed, it can immediately switch to the sampling detection and analysis of the next sampling point. However, the existing system has the following problems: a filter device needs to be installed in the middle of the sampling system; after collecting a high-concentration gas sample, the analysis instrument 4 cannot be purged to eliminate contamination; the sampling pipeline cannot be purged to eliminate sampling system contamination; the high-concentration gas sample cannot be retained; and the detection of the sample takes too long. Summary of the Invention

[0003] The present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution to overcome the defects of the prior art.

[0004] To achieve the above object, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, having the following features: including a drainage pump, a plurality of sampling units, a sample retention device, an analysis instrument and a purge gas storage device; the sampling unit includes a sampling head; the drainage pump is connected to the sampling head of each sampling unit through a plurality of pipelines; a sampling three-way valve is provided on the pipeline connecting each sampling head to the drainage pump; a plurality of sampling three-way valves are all connected to the sample retention device through pipelines; the sample retention device is connected to the analysis instrument through a pipeline; during sampling, the sampling head samples through the pumping of the drainage pump, and at the same time, through the suction of the analysis instrument, the gas sample flows through the sample retention device and is detected by the analysis instrument; an analysis purge three-way valve is provided on the pipeline connecting the sample retention device to the analysis instrument; the analysis purge three-way valve is connected to the purge gas storage device through a pipeline; a front short-circuit three-way valve and a rear short-circuit three-way valve are respectively provided at the front and rear ends of the sample retention device, and the front short-circuit three-way valve and the rear short-circuit three-way valve are connected through a pipeline; when the concentration of VOCs measured by the analysis instrument is higher than the set value, the sample retention device retains the sample; at the same time, the front short-circuit three-way valve and the rear short-circuit three-way valve short-circuit the sample retention device, and the purge gas in the purge gas storage device is shunted through the analysis purge three-way valve, a part of which flows into the analysis instrument to purge it, and the other part flows through the front short-circuit three-way valve, the rear short-circuit three-way valve and the pipeline therebetween and then flows to the sampling three-way valve, and finally is discharged by the drainage pump; there are multiple sample retention gas bags in the sample retention device, and the switching between the multiple sample retention gas bags is connected to the inlet and outlet of the sample retention device, and the sample retention is completed after the switching.

[0005] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: wherein, multi-way sealing valves are provided at both the inlet and outlet of the sample retention device; the multi-way sealing valve has a first air hole and a plurality of second air holes; the first air hole of the multi-way sealing valve provided at the inlet is the inlet of the sample retention device, and the first air hole of the multi-way sealing valve provided at the outlet is the outlet of the sample retention device; the first air hole is selectively connected to the plurality of second air holes; the plurality of second air holes of the two multi-way sealing valves correspond one by one and are respectively corresponding to a plurality of sample retention air bags; two interfaces of each sample retention air bag are respectively connected to the second air holes of the two corresponding multi-way sealing valves; when a certain sample retention air bag is communicated with the system through the second air hole, and when the first air hole is switched to be communicated with the next second air hole, the sample retention air bag is disconnected from the system, and the sample retention is completed.

[0006] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: wherein, the multi-way sealing valve includes a valve body, a rotary valve core and a servo motor; the valve body has a hemispherical groove, and a through hole is provided at the bottom of the groove; the rotary valve core has a hemispherical portion, and a rotary portion and an air hole extension portion are respectively provided on both sides of the hemispherical portion; the hemispherical portion of the rotary valve core is arranged in the groove of the valve body through a flange; the air hole extension portion extends out from the flange; the rotary portion extends out from the through hole and is connected to the output shaft of the servo motor, and the servo motor can drive the rotary valve core to rotate; the plurality of second air holes are provided in the valve body, one end of the second air hole is opened on the outer surface of the valve body, and the other end is opened on the surface of the groove; the first air hole is provided in the rotary valve core, one end of the first air hole is opened on the surface of the hemispherical portion, and the other end is opened at the end of the air hole extension portion; the orifice of the first air hole opened on the surface of the hemispherical portion corresponds to the orifice of the second air hole opened on the surface of the groove, and through the rotation of the rotary valve core, the first air hole is sequentially switched to be communicated with the plurality of second air holes; the servo motors of the two multi-way sealing valves rotate synchronously to complete the sample retention of one sample retention air bag.

[0007] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: wherein, a first sealing ring is provided on the contact surface between the rotary valve core and the flange, and a second sealing ring is provided at the orifice where the rotary valve core contacts the valve body.

[0008] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: wherein, the system further includes a standard gas storage device; a purge calibration three-way valve is provided on the pipeline between the analysis purge three-way valve and the purge gas storage device, and the purge calibration three-way valve is connected to the standard gas storage device through a pipeline; during calibration, the standard gas in the standard gas storage device flows into the analysis instrument through the purge calibration three-way valve and the analysis purge three-way valve to calibrate the analysis instrument.

[0009] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: A purge calibration flow controller is provided on the pipeline between the analysis purge three-way valve and the purge calibration three-way valve to control the flow rate of the purge gas or standard gas in the pipeline; an analysis pre-three-way valve is also provided on the pipeline between the analysis purge three-way valve and the analytical instrument; during purging and calibration, the analysis pre-three-way valve is in a semi-open state, and the excess gas that does not enter the analytical instrument is discharged by the analysis pre-three-way valve.

[0010] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: The sampling unit further includes a sampling flow controller; the sampling flow controller is arranged on the pipeline connecting the sampling head and the drainage pump to control the flow rate of the sample gas in the corresponding pipeline to be equal to the sampling flow rate of the analytical instrument.

[0011] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: The sampling unit further includes a sensor; the sensor is arranged on the pipeline connecting the sampling head and the drainage pump to detect the temperature and pressure of the sample gas in the corresponding pipeline.

[0012] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: The system further includes a control and display unit; the control and display unit includes a controller and a display; the controller is connected to the analytical instrument to control the sampling time of the sample by the analytical instrument, as well as the qualitative and quantitative analysis and data storage of the sample; the controller is connected to the sensor to receive the detection data of the sensor; the controller is connected to and controls the sampling three-way valve, the sampling flow controller, the front short-circuit three-way valve, the rear short-circuit three-way valve, the analysis purge three-way valve, the purge calibration three-way valve, the purge calibration flow controller, and the analysis pre-three-way valve; the display screen is connected to the controller, and the controller controls the display screen to display the states of the sensor, the sampling three-way valve, and the sampling flow controller; at the same time, the controller also draws a time curve of the pollutant concentration at each point based on the detection results of the analytical instrument and displays it through the display.

[0013] Furthermore, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, which may further have the following features: The sampling head is a sampling with a cyclone cutting device.

[0014] The beneficial effects of the present invention are as follows: The present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution. A cyclone device is designed at the sampling port, which can reduce the failure rate of the device; the sampling system has a purging function, and dry and clean gas is used to purge the sampling pipeline, which can reduce the impact of high-concentration sample gas on the sampling system and the instrument, and improve the accuracy of data analysis; a sample retention device is provided in the sampling system, which can retain high-concentration sample gas and leave evidence for environmental law enforcement; advanced analytical instruments are used, which can quickly and efficiently give the composition and content information of the sample gas; by using the linkage of multiple solenoid valves, one analytical instrument can be used to analyze the VOCs information of multiple points, saving human resources, reducing the analysis cost, and realizing the collection and analysis of gas samples with high spatio-temporal resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of a multi-point VOCs sampling and analysis system with high spatio-temporal resolution;

[0016] Figure 2 is a schematic structural diagram of a multi-way sealing valve;

[0017] Figure 3 is a sectional view of the multi-way sealing valve. DETAILED DESCRIPTION OF THE INVENTION

[0018] The following describes the specific embodiments of the present invention with reference to the accompanying drawings.

[0019] As Figure 1 shown, the present invention provides a multi-point VOCs sampling and analysis system with high spatio-temporal resolution, including a drainage pump 1, a plurality of sampling units 2, a sample retention device 3, an analytical instrument 4, a purge gas storage device 5, a standard gas storage device 6, and a control and display unit 7.

[0020] The sampling unit 2 includes a sampling head 21. Preferably, the sampling head 21 is a sampling with a cyclone cutting device, which can reduce the failure rate of the device. The drainage pump 1 is connected to the sampling head 21 of each sampling unit 2 through a plurality of pipelines. A sampling three-way valve 22 is provided on the pipeline connecting each sampling head 21 to the drainage pump 1. A plurality of sampling three-way valves 22 are all connected to the sample retention device 3 through pipelines. The sample retention device 3 is connected to the analytical instrument 4 through a pipeline. The analytical instrument 4 is a high-resolution mass spectrometer.

[0021] During sampling, the sampling head 21 samples through the pumping of the drainage pump 1. At the same time, through the pumping of the analytical instrument 4, the gas sample flows through the sample retention device 3 and is detected by the analytical instrument 4. The sampling three-way valve 22 is used to control the flow direction of the sample gas. The analytical instrument 4 analyzes one-way sample gas at a time. After reaching the specified time, the controller 71 controls the three-way valve to switch to the next-way sample gas.

[0022] Preferably, the sampling unit 2 further includes a sampling flow controller 23. The sampling flow controller 23 is arranged on the pipeline connecting the sampling head 21 and the drainage pump 1 to control the flow rate of the sampled gas in the corresponding pipeline to be equal to the sampling flow rate of the analytical instrument 4, so as to ensure the stability of the sampling data of the system.

[0023] The sampling unit 2 further includes a sensor 24. The sensor 24 is arranged on the pipeline connecting the sampling head 21 and the drainage pump 1 to detect the temperature and pressure of the sampled gas in the corresponding pipeline.

[0024] An analytical purge three-way valve 51 is provided on the pipeline connecting the sample storage device 3 and the analytical instrument 4. The analytical purge three-way valve 51 is connected to the purge gas storage device 5 through a pipeline. A front short-circuit three-way valve 31 and a rear short-circuit three-way valve 32 are respectively provided at the front and rear ends of the sample storage device 3, and the front short-circuit three-way valve 31 and the rear short-circuit three-way valve 32 are connected through a pipeline.

[0025] When the concentration of VOCs measured by the analytical instrument 4 is higher than the set value, the sample storage device 3 conducts sampling. At the same time, the front short-circuit three-way valve 31 and the rear short-circuit three-way valve 32 short-circuit the sample storage device 3. The purge gas in the purge gas storage device 5 is shunted by the analytical purge three-way valve 51. A part of the purge gas flows into the analytical instrument 4 for purging, and the other part flows through the front short-circuit three-way valve 31, the rear short-circuit three-way valve 32 and the pipeline therebetween and then flows to the sampling three-way valve 22 to purge the entire sampling gas path, and finally is discharged by the drainage pump 1. That is, at this time, the analytical purge three-way valve 51 in the gas path is in a semi-open state, playing a role of gas flow shunting.

[0026] There are multiple sample storage gas bags in the sample storage device 3. The switching between the multiple sample storage gas bags is connected to the inlet and outlet of the sample storage device 3, and sampling is completed after switching.

[0027] Specifically, as Figure 2 and 3 shown, multi-way seal valves 33 are provided at both the inlet and outlet of the sample storage device 3. The multi-way seal valve 33 has a first air hole 331 and multiple second air holes 332. The first air hole 331 of the multi-way seal valve 33 arranged at the inlet is the inlet of the sample storage device 3, and the first air hole 331 of the multi-way seal valve 33 arranged at the outlet is the outlet of the sample storage device 3. The first air hole 331 is respectively connected to the multiple second air holes 332 in a switching manner. The multiple second air holes 332 of the two multi-way seal valves 33 correspond one by one and correspond to the multiple sample storage gas bags one by one. Two interfaces of each sample storage gas bag are respectively connected to the second air holes 332 of the two corresponding multi-way seal valves 33. When a certain sample storage gas bag is communicated with the first air hole 331 through the second air hole 332, the sample storage gas bag is communicated with the system. When the first air hole 331 is switched to be communicated with the next second air hole 332, the sample storage gas bag is disconnected from the system, and sampling is completed.

[0028] More specifically, the multi-way sealing valve 33 includes a valve body 333, a rotary valve core 334, and a servo motor 335. The valve body 333 has a hemispherical groove, and a through hole is provided at the bottom of the groove. The rotary valve core 334 has a hemispherical portion, and a rotary portion and a gas hole extension portion are respectively provided on both sides of the hemispherical portion. The hemispherical portion of the rotary valve core 334 is arranged in the groove of the valve body 333 through a flange 336; the gas hole extension portion extends out of the flange 336; the rotary portion extends out of the through hole and is connected to the output shaft of the servo motor 335, and the servo motor 335 can drive the rotary valve core 334 to rotate. A plurality of second gas holes 332 are provided in the valve body 333. One end of the second gas hole 332 is opened on the outer surface of the valve body 333, and the other end is opened on the surface of the groove. The first gas hole 331 is provided in the rotary valve core 334. One end of the first gas hole 331 is opened on the surface of the hemispherical portion, and the other end is opened at the end of the gas hole extension portion. The orifice of the first gas hole 331 opened on the surface of the hemispherical portion corresponds to the orifice of the second gas hole 332 opened on the surface of the groove. By rotating the rotary valve core 334, the first gas hole 331 is sequentially switched to communicate with a plurality of second gas holes 332. The rotary valve core 334 provided with the first gas hole 331 is connected to the pipeline connected to the sampling device 3 through an O-ring and a straight-through connection. The servo motors 335 of the two multi-way sealing valves 33 rotate synchronously to complete the sampling of one sampling air bag.

[0029] The sample gas flows into the second gas hole 332 on the valve body 333 through the first gas hole 331 on the rotary valve core 334 at the inlet of the sampling device 3, then flows through the sampling air bag, flows out from another interface of the sampling air bag to the corresponding second gas hole 332 on the valve body 333 at the outlet of the sampling device 3, and finally flows out from the first gas hole 331 on the rotary valve body 333 to the subsequent analytical instrument 4. The two servo motors 335 in the sampling device 3 operate synchronously. When the system samples, the two servo motors 335 rotate synchronously to switch to the next sampling air bag, so that the sample gas is retained in the previous sampling air bag.

[0030] Preferably, a first sealing ring 337 is provided on the contact surface between the rotary valve core 334 and the flange, and a second sealing ring 338 is provided at the orifice where the rotary valve core 334 contacts the valve body 333 to ensure the sealing of the multi-way sealing valve 33.

[0031] A purge calibration three-way valve 61 is provided on the pipeline between the analytical purge three-way valve 51 and the purge gas storage device 5. The purge calibration three-way valve 61 is connected to the standard gas storage device 6 through a pipeline. During calibration, the standard gas in the standard gas storage device 6 flows into the analytical instrument 4 through the purge calibration three-way valve 61 and the analytical purge three-way valve 51 to calibrate the analytical instrument 4. At this time, the sampling three-way valves 22 in each sampling unit 2 are in a straight-through state.

[0032] A purge calibration flow controller 52 is provided on the pipeline between the analysis purge three-way valve 51 and the purge calibration three-way valve 61 to control the flow rate of the purge gas or standard gas in the pipeline.

[0033] An analysis pre-three-way valve 41 is also provided on the pipeline between the analysis purge three-way valve 51 and the analytical instrument 4. During purging and calibration, the analysis pre-three-way valve 41 is in a semi-open state, and the excess gas that does not enter the analytical instrument 4 is discharged by the analysis pre-three-way valve 41.

[0034] The control display unit 7 includes a controller 71 and a display 72.

[0035] The controller 71 is connected to the analytical instrument 4 to control the sampling time of the sample by the analytical instrument 4, as well as the qualitative and quantitative analysis of the sample and data storage. The controller 71 is connected to the sensor 24 to receive the detection data of the sensor 24. The controller 71 is connected to and controls the sampling three-way valve 22, the sampling flow controller 23, the front short-circuit three-way valve 31, the rear short-circuit three-way valve 32, the analysis purge three-way valve 51, the purge calibration three-way valve 61, the purge calibration flow controller 52, and the analysis pre-three-way valve 41.

[0036] The display screen is connected to the controller 71, and the controller 71 controls the display screen to display the states of the sensor 24, the sampling three-way valve 22, and the sampling flow controller 23. At the same time, the controller 71 also draws the time curve of the pollutant concentration at each point based on the detection results of the analytical instrument 4 and displays it through the display 72.

[0037] The controller 71 also controls the synchronous operation of the two servo motors 335 in the sample retention device 3.

[0038] During operation, the drainage pump 1 starts to pump the sampled gas into the pipeline from the sampling head 21, and then through the sensor 24, the sampling three-way valve 22, and the sampling flow controller 23. Under the control of the first controller 71, the flow rate of the sampled gas in the pipeline is equal to the sampling flow rate of the analytical instrument 4. At this time, the standard gas passes through the purge calibration three-way valve 61, the purge calibration flow controller 52, the analysis purge three-way valve 51, and the analysis pre-three-way valve 41, and finally enters the analytical instrument 4 to calibrate the analytical instrument 4. The front short-circuit three-way valve 31 and the rear short-circuit three-way valve 32 are in a direct connection state.

[0039] When the system reaches stability and the analytical instrument 4 is calibrated, sampling begins. There is a sampling three-way valve 22 in the sampling pipeline for switching, so that the sample gas flows through the front short-circuit three-way valve 31, the sample retention device 3, the rear short-circuit three-way valve 32, the analytical purge three-way valve 51, and the analytical pre-three-way valve 41 in sequence, and finally enters the analytical instrument 4. The sampling time of the sample, the qualitative and quantitative analysis of the sample, and the data storage are controlled by the controller 71. The display 72 shows the time curve of the point pollutant concentration. After analyzing one-way sample gas, the sampling three-way valve 22 of another sampling unit 2 is switched, and the current sampling three-way valve 22 is switched to the previous state.

[0040] When the concentration of VOCs measured by the analytical instrument 4 is higher than a certain concentration, the sample retention device 3 will retain the gas sample. Multiple sample retention gas bags are set in the sample retention device 3, and the sample is retained by switching to the next sample retention gas bag. Specifically, the two servo motors 335 are synchronously rotated under the control of the controller 71 to achieve the switching of the sample retention gas bags. At the same time, the front short-circuit three-way valve 31 and the rear short-circuit three-way valve 32 short-circuit the sample retention device 3, and zero air (purge gas) passes through the purge calibration three-way valve 61, the purge calibration flow controller 52, the analytical purge three-way valve 51, the analytical pre-three-way valve 41, the rear short-circuit three-way valve 32, and the front short-circuit three-way valve 31 in sequence to purge the entire sampling gas path and the analytical instrument 4. At this time, the analytical purge three-way valve 51 in the gas path is in a semi-open state, playing a role in air flow diversion. After purging the pipeline, the analytical purge three-way valve 51, the analytical pre-three-way valve 41, the rear short-circuit three-way valve 32, the front short-circuit three-way valve 31 in the pipeline, and the sampling three-way valve 22 on the sampling pipe are switched, so that another sampling gas passes through the sample retention device 3 and enters the analytical instrument 4 for analysis and detection.

[0041] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art.

[0042] It should be noted that the terms such as "upper", "lower", "left", "right", "front", and "rear" cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.

[0043] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-point VOCs sampling and analysis system with high spatio-temporal resolution, characterized in that: it includes a drainage pump, several sampling units, a sample retention device, an analytical instrument, and a purge gas storage device; the sampling unit includes a sampling head; the drainage pump is connected to the sampling head of each sampling unit through several pipelines; a sampling three-way valve is provided on the pipeline connecting each sampling head to the drainage pump; several sampling three-way valves are all connected to the sample retention device through pipelines; the sample retention device is connected to the analytical instrument through a pipeline; during sampling, the sampling head samples through the pumping of the drainage pump, and at the same time, through the suction of the analytical instrument, the gas sample flows through the sample retention device and is detected by the analytical instrument; an analytical purge three-way valve is provided on the pipeline connecting the sample retention device to the analytical instrument; the analytical purge three-way valve is connected to the purge gas storage device through a pipeline; a front short-circuit three-way valve and a rear short-circuit three-way valve are respectively provided at the front and rear ends of the sample retention device, and the front short-circuit three-way valve and the rear short-circuit three-way valve are connected through a pipeline; when the concentration of VOCs measured by the analytical instrument is higher than the set value, the sample retention device retains the sample; at the same time, the front short-circuit three-way valve and the rear short-circuit three-way valve short-circuit the sample retention device, and the purge gas in the purge gas storage device is shunted through the analytical purge three-way valve. One part flows into the analytical instrument to purge it, and the other part flows through the front short-circuit three-way valve, the rear short-circuit three-way valve, and the pipeline therebetween and then flows to the sampling three-way valve, and finally is discharged by the drainage pump; there are multiple sample retention gas bags in the sample retention device, and the connection between the multiple sample retention gas bags and the inlet and outlet of the sample retention device is switched, and the sample retention is completed after the switching; multi-way sealing valves are provided at both the inlet and outlet of the sample retention device; the multi-way sealing valve has a first air hole and multiple second air holes; the first air hole of the multi-way sealing valve provided at the inlet is the inlet of the sample retention device, and the first air hole of the multi-way sealing valve provided at the outlet is the outlet of the sample retention device; the first air hole is respectively switched and connected to the multiple second air holes; the multiple second air holes of the two multi-way sealing valves correspond one by one and correspond to the multiple sample retention gas bags one by one; the two interfaces of each sample retention gas bag are respectively connected to the second air holes of the two multi-way sealing valves corresponding to it; when a certain sample retention gas bag is connected to the system through the second air hole, and the first air hole is switched to be connected to the next second air hole, the sample retention gas bag is disconnected from the system, and the sample retention is completed; The multi-way sealing valve includes a valve body, a rotary spool and a servo motor; the valve body has a hemispherical groove, and a through hole is provided at the bottom of the groove; the rotary spool has a hemispherical portion, and a rotary portion and a gas hole extension portion are respectively provided on both sides of the hemispherical portion; the hemispherical portion of the rotary spool is arranged in the groove of the valve body through a flange; the gas hole extension portion extends out of the flange; the rotary portion extends out of the through hole and is connected to the output shaft of the servo motor, and the servo motor can drive the rotary spool to rotate; the plurality of second gas holes are arranged in the valve body, one end of the second gas hole is opened on the outer surface of the valve body, and the other end is opened on the surface of the groove; the first gas hole is arranged in the rotary spool, one end of the first gas hole is opened on the surface of the hemispherical portion, and the other end is opened at the end of the gas hole extension portion; the orifice of the first gas hole opened on the surface of the hemispherical portion corresponds to the orifice of the second gas hole opened on the surface of the groove, and by rotating the rotary spool, the first gas hole is sequentially switched to communicate with the plurality of second gas holes; the servo motors of the two multi-way sealing valves rotate synchronously to complete the sampling of a sample gas bag.

2. The high spatio-temporal resolution multi-point VOCs sampling and analysis system according to claim 1, wherein: Wherein, A first sealing ring is provided on the contact surface between the rotary spool and the flange, and a second sealing ring is provided at the orifice where the rotary spool contacts the valve body.

3. The high spatio-temporal resolution multi-point VOCs sampling and analysis system according to claim 1, wherein: Wherein, The system further includes a standard gas storage device; A purge calibration three-way valve is provided on the pipeline between the analysis purge three-way valve and the purge gas storage device, and the purge calibration three-way valve is connected to the standard gas storage device through a pipeline; During calibration, the standard gas in the standard gas storage device flows into the analytical instrument through the purge calibration three-way valve and the analysis purge three-way valve to calibrate the analytical instrument.

4. The high spatio-temporal resolution multi-point VOCs sampling and analysis system according to claim 3, wherein: Wherein, A purge calibration flow controller is provided on the pipeline between the analysis purge three-way valve and the purge calibration three-way valve to control the flow rate of the purge gas or the standard gas in the pipeline; An analysis pre-three-way valve is further provided on the pipeline between the analysis purge three-way valve and the analytical instrument; during purging and calibration, the analysis pre-three-way valve is in a semi-open state, and the excess gas that does not enter the analytical instrument is discharged by the analysis pre-three-way valve.

5. The high spatio-temporal resolution multi-point VOCs sampling and analysis system according to claim 4, wherein: Wherein, The sampling unit further includes a sampling flow controller; the sampling flow controller is arranged on the pipeline connecting the sampling head and the drainage pump to control the flow rate of the sample gas in the corresponding pipeline to be equal to the sampling flow rate of the analytical instrument.

6. The high spatio-temporal resolution multi-point VOCs sampling and analysis system according to claim 5, wherein: Wherein, The sampling unit further includes a sensor; the sensor is arranged on the pipeline connecting the sampling head and the drainage pump to detect the temperature and pressure of the sample gas in the corresponding pipeline.

7. The high spatio-temporal resolution multi-point VOCs sampling and analysis system according to claim 6 ， wherein: Wherein, The system further includes a control and display unit; the control and display unit includes a controller and a display; The controller is connected to the analytical instrument, and controls the sampling time of the analytical instrument for the sample, as well as the qualitative and quantitative analysis and data storage of the sample; The controller is connected to the sensor and receives the detection data of the sensor; The controller is connected to the sampling three-way valve, sampling flow controller, front short-circuit three-way valve, rear short-circuit three-way valve, analytical purge three-way valve, purge calibration three-way valve, purge calibration flow controller, and analytical pre-three-way valve and controls them; The display screen is connected to the controller, and the controller controls the display screen to display the states of the sensor, sampling three-way valve, and sampling flow controller; meanwhile, the controller also draws a time curve of the pollutant concentration at each point based on the detection results of the analytical instrument and displays it through the display.

8. The high spatio-temporal resolution multi-point VOCs sampling and analysis system according to claim 1, wherein: Wherein, The sampling head is a sampling with a cyclone cutting device.

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