Enrichment equipment, VOCs analysis system and method for VOCs online monitoring

Abstract

The present invention provides an enrichment device for VOCs online monitoring, a VOCs analysis system and method, which relates to air quality detection. The enrichment device is applied to a VOCs analyzer, and includes: a dehydration device, an enrichment device, a flow control device and a high-temperature valve box; the input end of the flow control device is respectively connected to the sample gas inlet, the high-temperature valve box and the activated gas inlet; the output end of the flow control device is connected to the dehydration device, the sample gas outlet and the high-temperature valve box; the two ends of the enrichment device are respectively connected to the high-temperature valve box. The gas to be detected is pre-treated by the dehydration device and the enrichment device in the enrichment device, and is finally input into the VOCs analyzer through the flow control device and the high-temperature valve box to complete the detection, which effectively improves the detection limit of the target pollutants in the gas to be detected and improves the analysis accuracy.

Description

Technical Field

[0001] The present invention relates to the field of air quality detection, and in particular to an enrichment device for VOCs online monitoring, a VOCs analysis system and a method. Background Art

[0002] VOCs (Volatile Organic Compounds) have a great impact on environmental safety and are harmful to human health, so it is necessary to detect and treat VOCs generated in industrial activities and daily life. The sample matrix composition collected during existing VOCs monitoring is complex, the concentration of target pollutants is generally low, and they are directly analyzed without any pre-treatment, resulting in large errors in the analysis results. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide an enrichment device, a VOCs analysis system and a method for online monitoring of VOCs, wherein the gas to be detected is pretreated by a dehydration device and an enrichment device in the enrichment device, and finally input into a VOCs analyzer through a high-temperature valve box to complete the detection. For the gas to be detected with a low concentration of target pollutants, the process from low-temperature enrichment to thermal desorption is completed through the dehydration device, the enrichment device and the high-temperature valve box, thereby effectively improving the detection limit of the target pollutants in the gas to be detected and improving the analysis accuracy.

[0004] In a first aspect, an embodiment of the present invention provides an enrichment device for online monitoring of VOCs, the enrichment device being applied to a VOCs analyzer, comprising: a water removal device, an enrichment device, a flow control device, and a high-temperature valve box;

[0005] The input end of the flow control device is connected to the sample gas inlet, the high-temperature valve box and the activation gas inlet respectively; the output end of the flow control device is connected to the water removal device, the sample gas outlet and the high-temperature valve box; the two ends of the enrichment device are connected to the high-temperature valve box respectively;

[0006] A flow control device for controlling the initial sample gas transmitted to the water removal device through the sample gas inlet and controlling the gas flow rate flowing from the activated gas inlet into the enrichment device;

[0007] A dehydration device is used to remove water vapor from the initial sample gas to obtain a first sample gas containing CO2 and VOCs components, and transmit the first sample gas to an enrichment device;

[0008] An enrichment device, used for enriching and removing the first gas, and removing carbon dioxide in the first gas to obtain a second gas;

[0009] The high temperature valve box is used to heat the second sample gas so as to transmit the heated second sample gas to the VOCs analyzer for detection.

[0010] In some embodiments, the flow control device includes: at least one steady flow valve and at least one electronic flow sensor; wherein the steady flow valve is arranged at the sample gas inlet and the activation gas inlet; and the electronic flow sensor is arranged at the sample gas outlet.

[0011] In some embodiments, a cold trap tube filled with glass beads is provided in the water removal device; the refrigeration temperature range of the cold trap tube is: 0 to minus 30 degrees Celsius.

[0012] In some embodiments, a cold trap tube containing multiple adsorbents is provided in the enrichment device.

[0013] In some embodiments, the high temperature valve box contains a plurality of multi-way valves, each of which is used to switch the working state of the enrichment device;

[0014] A heating plate is provided at the bottom of the high-temperature valve box, and the heating plate is used to heat the second sample gas contained in the multi-way valve located at the heating plate.

[0015] In some embodiments, when the communication mode of the multiple multi-way valves is a sample gas enrichment mode, the input end of the enrichment device is connected to the sample gas inlet through the multiple multi-way valves, and the output end of the enrichment device is connected to the sample gas outlet through the multiple multi-way valves;

[0016] When the connection mode of the multiple multi-way valves is the flash evaporation and desorption mode, the input end of the enrichment device is connected to the chromatographic inlet through the multiple multi-way valves, and the output end of the enrichment device is connected to the chromatographic carrier gas outlet through the multiple multi-way valves;

[0017] When the connection mode of the multiple multi-way valves is the activation and spacing mode, the input end of the enrichment device is connected to the tail gas outlet through the multiple multi-way valves, and the output end of the enrichment device is connected to the activation gas inlet through the multiple multi-way valves.

[0018] In some embodiments, the above-mentioned multiple multi-way valves include: 1 six-way valve and 3 three-way valves; wherein the first three-way valve and the second three-way valve among the three-way valves are located at the bottom of the high-temperature valve box; the six-way valve and the third three-way valve are located at the top of the high-temperature valve box.

[0019] In some embodiments, the working state of the above-mentioned enrichment device includes a sample gas enrichment mode, a flash desorption mode, and an activation interval mode;

[0020] Wherein, in the sample gas enrichment mode, the chromatographic inlet and the chromatographic carrier gas outlet are connected through the second three-way valve; the first sample gas enters the enrichment device through the six-way valve;

[0021] In the flash desorption mode, the chromatographic inlet and the chromatographic carrier gas outlet are connected in sequence through the third three-way valve, the six-way valve, the enrichment device, the first three-way valve and the second three-way valve; the enrichment device heats the second sample gas, and the heated second sample gas is reversely input into the chromatographic inlet for VOCs analysis;

[0022] In the activation interval mode, the activation gas inlet and the tail gas outlet are connected in sequence through the first three-way valve, the six-way valve, the enrichment device and the third three-way valve; the chromatographic inlet and the chromatographic carrier gas outlet are connected through the second three-way valve.

[0023] In a second aspect, an embodiment of the present invention provides a VOCs analysis system, the system comprising: an enrichment device for online monitoring of VOCs and a VOCs analyzer as mentioned in the first aspect;

[0024] The enrichment equipment is used to enrich the sample gas containing VOCs components;

[0025] The VOCs analyzer is used to analyze the enriched sample gas to obtain the VOCs analysis results of the sample gas.

[0026] In a third aspect, an embodiment of the present invention further provides a VOCs analysis method, which is applied to the VOCs analysis system mentioned in the second aspect, and the method includes:

[0027] Inputting the sample gas containing VOCs components into the enrichment device; wherein the enrichment device is the enrichment device for VOCs online monitoring mentioned in the first aspect;

[0028] According to the working mode of the enrichment equipment, the VOCs sample gas is enriched and concentrated; wherein the working mode includes sample gas enrichment mode, flash desorption mode and activation interval mode;

[0029] The VOCs sample gas after enrichment and concentration is input into the VOCs analyzer for analysis to obtain the VOCs analysis results.

[0030] The embodiments of the present invention bring the following beneficial effects:

[0031] The present invention provides an enrichment device for online monitoring of VOCs, a VOCs analysis system and a method. The enrichment device is applied to a VOCs analyzer and includes: a dehydration device, an enrichment device, a flow control device and a high-temperature valve box; the input end of the flow control device is respectively connected to the sample gas inlet, the high-temperature valve box and the activated gas inlet; the output end of the flow control device is connected to the dehydration device, the sample gas outlet and the high-temperature valve box; the two ends of the enrichment device are respectively connected to the high-temperature valve box; the flow control device is used to control the initial sample gas transmitted to the dehydration device through the sample gas inlet, and to control the gas flow rate of the activated gas inlet flowing into the enrichment device. The dehydration device is used to remove water vapor in the initial sample gas to obtain a first sample gas containing CO2 and VOCs components, and transmit the first sample gas to the enrichment device; the enrichment device is used to enrich and remove the first sample gas, and remove carbon dioxide in the first sample gas to obtain a second sample gas; the high-temperature valve box is used to heat the second sample gas to transmit the heated second sample gas to the VOCs analyzer for detection. The gas to be detected is pretreated by the dehydration device and enrichment device in the enrichment equipment, and finally input into the VOCs analyzer through the high-temperature valve box to complete the detection. For the gas to be detected with a low concentration of target pollutants, the process from low-temperature enrichment to heat absorption is completed through the dehydration device, enrichment device and high-temperature valve box, which effectively improves the detection limit of the target pollutants in the gas to be detected and improves the analysis accuracy.

[0032] Other features and advantages of the present invention will be set forth in the following description, or some features and advantages may be inferred or unambiguously determined from the description, or may be learned by implementing the above-mentioned technology of the present invention.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic diagram of the structure of an enrichment device for online monitoring of VOCs provided in an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of the structure of another enrichment device for online monitoring of VOCs provided in an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of the structure of an enrichment device in a flash desorption mode provided in an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the structure of an enrichment device in an activation interval mode provided by an embodiment of the present invention;

[0039] Figure 5 A schematic diagram of the structure of a VOCs analysis system provided by an embodiment of the present invention;

[0040] Figure 6 A flow chart of a VOCs analysis method provided in an embodiment of the present invention.

[0041] icon:

[0042] 10-dewatering device; 20-enrichment device; 30-flow control equipment; 40-high temperature valve box; 31-first steady flow valve; 32-second steady flow valve; 33-electronic flow sensor; 41-first three-way valve; 42-second three-way valve; 43-third three-way valve; 44-six-way valve; 51-sample gas inlet; 52-sample gas outlet; 53-activated gas inlet; 54-tail gas outlet; 55-chromatographic inlet; 56-chromatographic carrier gas outlet; 100-enrichment equipment; 200-VOCs analyzer. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] With the acceleration of urbanization and industrialization, energy consumption and the output of industrial by-products have increased rapidly. High-intensity industrial activities and extensive production methods have led to large-scale emissions of VOCs. Many VOCs are highly toxic and carcinogenic, which directly endanger human health; VOCs react with NOx under ultraviolet irradiation to generate O3, which enhances the oxidizing property of the atmosphere; VOCs are also one of the important prerequisites for secondary organic aerosols. Aromatic hydrocarbon compounds are the main substances for the generation of secondary aerosols. The O3 generated by VOCs conversion participates in atmospheric chemical reactions again to generate sulfates and nitrates, further promoting the generation of secondary organic aerosols, destroying the atmospheric environment, and endangering human health. Therefore, in order to improve the quality of ambient air, VOCs have been analyzed and processed in the prior art. However, in the specific implementation process, due to the complex composition of the sample matrix collected during the monitoring of existing VOCs, the concentration of the target pollutants is generally low, and the analysis is directly performed without any pre-treatment, resulting in large errors in the analysis results.

[0045] Based on this, the embodiments of the present invention provide an enrichment device, a VOCs analysis system and a method for online monitoring of VOCs. The gas to be detected can be pre-treated by a dehydration device and an enrichment device in the enrichment device, and finally input into a VOCs analyzer through a high-temperature valve box to complete the detection. For the gas to be detected with a low concentration of target pollutants, the process from low-temperature enrichment to heat absorption is completed through the dehydration device, the enrichment device and the high-temperature valve box, thereby effectively improving the detection limit of the target pollutants in the gas to be detected and improving the analysis accuracy.

[0046] To facilitate understanding of this embodiment, first, an enrichment device for online monitoring of VOCs disclosed in an embodiment of the present invention is introduced in detail.

[0047] See also Figure 1 An enrichment device for VOCs online monitoring is shown, which is applied to a VOCs analyzer and includes: a water removal device 10, an enrichment device 20, a flow control device 30 and a high-temperature valve box 40.

[0048] The input end of the flow control device 30 is respectively connected to the sample gas inlet 51, the high-temperature valve box 40 and the activated gas inlet 53; the output end of the flow control device 30 is connected to the water removal device 10, the sample gas outlet 52 and the high-temperature valve box 40; the two ends of the enrichment device 20 are respectively connected to the high-temperature valve box 40.

[0049] The sample gas inlet 51 is the air inlet channel for the initial sample gas. The entire analysis process begins after the initial sample gas to be detected and analyzed passes through the sample gas inlet 51; the sample gas outlet 52 is the exhaust channel for removing the sample gas; the activation gas inlet 53 is the air inlet channel during activation, and the activation gas provides activation for VOCs analysis through the activation gas inlet 53.

[0050] The flow control device 30 is used to control the initial sample gas transmitted to the water removal device 10 through the sample gas inlet 51 and to control the gas flow rate flowing from the activated gas inlet 53 into the enrichment device 20 .

[0051] The dehydration device 10 is used to remove water vapor from the initial sample gas to obtain a first sample gas containing CO2 and VOCs components, and transmit the first sample gas to the enrichment device 20. It can be seen that the first sample gas is the initial sample gas with water vapor removed.

[0052] The enrichment device 20 is used to enrich and remove the first gas, and remove carbon dioxide from the first gas to obtain a second gas. The second gas is the first gas from which carbon dioxide has been removed.

[0053] The high temperature valve box 40 is used to heat the second sample gas to transmit the heated second sample gas to the VOCs analyzer for detection. The heated second sample gas enters the chromatographic device of the VOCs analyzer through the chromatographic inlet 55 for chromatographic analysis to obtain the analysis result of VOCs; in this process, the chromatographic carrier gas outlet 56 is required to provide carrier gas to push the initial sample gas to be tested to finally flow into the chromatographic inlet 55, and the related tail gas is discharged through the tail gas outlet 54.

[0054] From the enrichment device for VOCs online monitoring mentioned in this embodiment, it can be known that the enrichment device can pre-treat the gas to be detected through the built-in dehydration device and enrichment device, and finally input it into the VOCs analyzer through the flow control device and the high-temperature valve box to complete the detection. For the gas to be detected with a low concentration of target pollutants, the process from low-temperature enrichment to heat absorption can be completed through the dehydration device, enrichment device and high-temperature valve box, effectively improving the detection limit of the target pollutants in the gas to be detected and improving the analysis accuracy.

[0055] In some embodiments, the flow control device includes: at least one steady flow valve and at least one electronic flow sensor; wherein the steady flow valve is arranged at the sample gas inlet and the activated gas inlet; and the electronic flow sensor is arranged at the sample gas outlet. The steady flow valve and the electronic flow sensor are controlled by embedded software, and the flow control of the sample gas path is performed by connecting the steady flow valve and the electronic flow sensor in series. The dual control improves the stability of the sample gas flow, and the steady flow valve is used to control the flow of the activated gas path, so that the activated gas flow stably passes through the enrichment device in the reverse direction to clean the enrichment device.

[0056] In some embodiments, a cold trap tube filled with glass beads is provided in the water removal device; the refrigeration temperature range of the cold trap tube is: 0 to minus 30 degrees Celsius.

[0057] In some embodiments, a cold trap tube containing multiple adsorbents is provided in the enrichment device.

[0058] In some embodiments, the interior of the high-temperature valve box contains multiple multi-way valves, each of which is used to switch the working state of the enrichment device; a heating plate is provided at the bottom of the high-temperature valve box, and the heating plate is used to heat the second sample gas contained in the multi-way valve located at the heating plate.

[0059] In some embodiments, when the communication mode of the multiple multi-way valves is a sample gas enrichment mode, the input end of the enrichment device is connected to the sample gas inlet through the multiple multi-way valves, and the output end of the enrichment device is connected to the sample gas outlet through the multiple multi-way valves;

[0060] When the connection mode of the multiple multi-way valves is the flash evaporation and desorption mode, the input end of the enrichment device is connected to the chromatographic inlet through the multiple multi-way valves, and the output end of the enrichment device is connected to the chromatographic carrier gas outlet through the multiple multi-way valves;

[0061] When the connection mode of the multiple multi-way valves is the activation and spacing mode, the input end of the enrichment device is connected to the tail gas outlet through the multiple multi-way valves, and the output end of the enrichment device is connected to the activation gas inlet through the multiple multi-way valves.

[0062] Combine the following Figure 2 Another enrichment device for online monitoring of VOCs is shown to describe the enrichment device in the above embodiment. Figure 2 The multiple multi-way valves of the enrichment device shown in the figure include: 1 six-way valve and 3 three-way valves; wherein, the first three-way valve 41 and the second three-way valve 42 of the three-way valves are located at the bottom of the high-temperature valve box 40; the six-way valve 44 and the third three-way valve 43 are located at the top of the high-temperature valve box 40.

[0063] The dewatering device is provided with a three-stage cooling plate; wherein the dewatering module is provided with a cold trap tube filled with glass beads, and the size of the cold trap tube is The refrigeration temperature range of the refrigeration plate is: 0 to minus 30 degrees Celsius. The water vapor in the initial sample gas is enriched in the dehydration device through low temperature.

[0064] A heating plate is provided at the bottom of the high-temperature valve box, which is used to heat the second sample gas contained in the multi-way valve located at the heating plate. The heating plate can be heated to 120°C to ensure that the "flash evaporated" sample gas passes through various gas paths in the valve box in the high-temperature box.

[0065] The enrichment device is cooled by a three-stage refrigeration sheet, which can reduce the temperature inside the device to minus 30°C. The cold trap tube is filled with 13mm Carbopack C, 25mm Carbopack B and 13mm Carboxen 1000; the device is kept at minus 30℃ to enrich the sample gas. After the enrichment is completed, the enriched sample gas is instantly vaporized at a heating rate of 100℃ / s, and driven by the carrier gas, it is brought to the inlet of the analytical instrument for sample gas analysis.

[0066] The flow control device includes: two steady flow valves and an electronic flow sensor; wherein the first steady flow valve 31 is arranged at the sample gas inlet 51, the second steady flow valve 32 is arranged at the activation gas inlet 53; the electronic flow sensor 33 is arranged at the sample gas outlet 52. The first steady flow valve 31, the second steady flow valve 32 and the electronic flow sensor 33 are connected to the multi-way valve, and the specific connection process with the multi-way valve is controlled by the embedded software according to the working state of the enrichment device.

[0067] Specifically, the working states of the enrichment device include sample gas enrichment mode, flash desorption mode and activation interval mode.

[0068] Figure 2 The enrichment device shown is a sample gas enrichment mode, and the chromatographic inlet 55 and the chromatographic carrier gas outlet 56 are connected through the second three-way valve 42. At this time, the sample gas of the sample gas inlet 51 passes through the first steady flow valve 31 and the water removal device in sequence and enters the six-way valve 44, and then completes the enrichment through the enrichment device 20. The enriched gas passes through the six-way valve 44 and is discharged through the sample gas outlet 52. At this time, the gas paths where the activated gas inlet 53, the tail gas outlet 54, the chromatographic inlet 55 and the chromatographic carrier gas outlet 56 are located are not connected.

[0069] In the sample gas enrichment mode, the chromatographic inlet and the chromatographic carrier gas outlet are connected through the second three-way valve 42; the first sample gas enters the enrichment device 20 through the six-way valve 44. The sample gas passes through the first steady flow valve 31 for flow control and enters the dehydration device 10 at a constant flow rate. The dehydration device 10 enriches water vapor in a solid form at low temperature, while the VOCs component is not affected and enters the high-temperature valve box 40 through the dehydration device 10, and then enters the enrichment device 20 through the six-way valve 44. The enrichment device 20 enriches the sample gas at low temperature; at this time, the carrier gas controlled by EPC in the chromatograph returns to the chromatograph after passing through this system, and the activation gas path is not opened at this time.

[0070] For details on the connection relationship between the multi-port valves in the sample gas enrichment mode, see Figure 2 The channels in the six-way valve are represented by 1, 2, 3, 4, 5, and 6 respectively; the channels in the three-way valve are represented by 1, 2, and 3 respectively.

[0071] Figure 3 The working mode of the enrichment equipment shown is a flash desorption mode. In the flash desorption mode, the chromatographic inlet and the chromatographic carrier gas outlet are connected in sequence through the third three-way valve 43, the six-way valve 44, the enrichment device 20, the first three-way valve 41 and the second three-way valve 42; the enrichment device 20 heats the second sample gas, and the heated second sample gas is reversely input into the chromatographic inlet 55 for VOCs analysis.

[0072] In the flash desorption mode, the water removal device 10 is heated to room temperature, and the enriched solid water vapor is converted into gas and carried out of the water removal device 10 by the sample gas; the enrichment device 20 is rapidly heated to 300°C at a heating rate of 100°C / s, and the enriched VOCs are "flashed" out of the enrichment tube, and the flash evaporation temperature is maintained for continuous desorption, and the desorbed sample gas is reversely carried into the analytical instrument by the chromatographic carrier gas for analysis; at this time, the activation gas path is not opened.

[0073] The connection relationship between the multi-way valves in the flash desorption mode is detailed in Figure 3 ,and Figure 2 Similarly, the channels in the six-way valve are represented by 1, 2, 3, 4, 5, and 6 respectively; the channels in the three-way valve are represented by 1, 2, and 3 respectively, and the connection relationship is not repeated again.

[0074] Figure 4 The working mode of the enrichment device shown is the activation interval mode. In the activation interval mode, the activation gas inlet 53 and the tail gas outlet 54 are connected in sequence through the first three-way valve 41, the six-way valve 44, the enrichment device 20 and the third three-way valve 43; the chromatographic inlet 55 and the chromatographic carrier gas outlet 56 are connected through the second three-way valve 42.

[0075] In the activation mode, the sample gas continues to pass through the water removal device 10 at room temperature and then is emptied. At this time, the activated gas path is introduced into the enrichment device, and the enrichment tube of the enrichment device 20 is reversely purged while maintaining the desorption temperature, and the purged tail gas is emptied. At this time, the chromatographic carrier gas returns to the chromatograph after passing through the enrichment device.

[0076] In the interval mode, the gas path system at this time is consistent with that in the activation mode. In the interval mode, the sample gas is no longer sent to the enrichment device 20. At the same time, the dehydration device 10 and the enrichment device 20 are cooled to the pre-concentration temperature set for each part, waiting for the start of the next enrichment.

[0077] The connection relationship between the multi-way valves in the activation interval mode is detailed in Figure 4 ,and Figure 2 , Figure 3 Similarly, the channels in the six-way valve are represented by 1, 2, 3, 4, 5, and 6 respectively; the channels in the three-way valve are represented by 1, 2, and 3 respectively, and the connection relationship is not repeated again.

[0078] Semiconductor refrigeration technology is used to cool down the enrichment device 20 during the cooling process; the cooling plate is small in size, requires little space, is easy to install, and can be temperature controlled by an embedded program. The working principle of the semiconductor refrigeration device is based on the Peltier principle, that is, when a circuit composed of two different conductors A and B is passed through a direct current, in addition to Joule heat, some other heat will be released at the joint, while the other joint absorbs heat, and this phenomenon caused by the Peltier effect is reversible. When the direction of the current is changed, the joints that release heat and absorb heat will also change accordingly.

[0079] In the low-temperature enrichment process, the adsorption properties of activated carbon were utilized, and a combination of Carbopack C, Carbopack B, and Carboxen 1000 was used to enrich C2-C18 compounds at low temperature. The samples were enriched and concentrated at an enrichment temperature of minus 30°C, thereby improving the detection limit without modifying the analytical device.

[0080] In a second aspect, an embodiment of the present invention provides a VOCs analysis system, the structural diagram of which is as follows: Figure 5 As shown, the system includes: the enrichment device 100 for VOCs online monitoring and the VOCs analyzer 200 as mentioned in the first aspect;

[0081] The enrichment device 100 is used to enrich the sample gas containing VOCs components; the relevant technical parameters of the enrichment device 100 are as follows:

[0082] Dewatering device temperature: 0℃;

[0083] Enrichment device temperature: -30°C;

[0084] High temperature valve box temperature: 120℃;

[0085] Chromatographic injection line temperature: 120°C;

[0086] Heating rate of enrichment device: ≥100℃ / s;

[0087] Refrigeration technology: semiconductor refrigeration.

[0088] The VOCs analyzer 200 is used to analyze the enriched sample gas to obtain the VOCs analysis result of the sample gas.

[0089] The enrichment device for online monitoring of VOCs in this embodiment has the same technical features as the enrichment device for online monitoring of VOCs provided in the above method embodiment, so it can also solve the same technical problems and achieve the same technical effects. For the sake of brief description, for matters not mentioned in the embodiment part, reference can be made to the corresponding contents in the above method embodiment.

[0090] In a third aspect, an embodiment of the present invention further provides a VOCs analysis method, which is applied to the VOCs analysis system mentioned in the second aspect, such as Figure 6 As shown, the method includes:

[0091] Step S601, inputting the sample gas containing VOCs components into the enrichment equipment.

[0092] The enrichment device is the enrichment device for online monitoring of VOCs mentioned in the above embodiment. The sample gas is input into the enrichment device through the sample gas inlet, the flow stabilizing valve and the water removal device in sequence.

[0093] Step S602, enriching and concentrating the VOCs sample gas according to the working mode of the enrichment equipment; wherein the working mode includes a sample gas enrichment mode, a flash desorption mode and an activation interval mode.

[0094] The dehydration device is cooled to the pre-concentration temperature through the above three modes in sequence, and the atmospheric sample enters the dehydration device at a constant flow rate under mass flow control. The cold trap in the dehydration device is filled with glass beads, and the water vapor is enriched in the dehydration device in a solid state, while most of the VOCs components pass through without being affected (frozen to 0°C to remove water vapor).

[0095] The enrichment device is cooled down to the pre-concentration temperature, and the gas passing through the dehydration device enters the enrichment device. The enrichment device contains a three-combination adsorbent of Carbopack B, Carbopack C, and Carboxen 1000, which completely adsorb the VOCs components. At this time, the gaseous CO2 is taken out of the system, thereby removing CO2.

[0096] The enrichment device is quickly heated to 300°C, and the captured compounds are instantly vaporized and transferred to the analytical instrument for analysis by "flash evaporation".

[0097] Step S603, the VOCs sample gas after enrichment and concentration is input into a VOCs analyzer for analysis to obtain the VOCs analysis result.

[0098] After low-temperature enrichment-thermal desorption, samples with low concentrations of target pollutants can effectively improve the detection limit of target pollutants and eliminate the interference of the matrix on the determination. Without changing the analyzer, the detection limit of the target compound can be effectively improved by pre-treating the sample gas.

[0099] The VOCs analysis system in this embodiment has the same technical features as the VOCs analysis system provided in the above method embodiment, so it can also solve the same technical problems and achieve the same technical effects. For the sake of brief description, for matters not mentioned in the embodiment part, reference can be made to the corresponding contents in the above method embodiment.

[0100] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0101] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0102] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0103] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present invention can essentially or in other words, the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0104] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An enrichment device for VOCs online monitoring, the enrichment device is applied to a VOCs analyzer, characterized in that: The enrichment equipment includes: a water removal device, an enrichment device, a flow control device and a high-temperature valve box; The input end of the flow control device is connected to the sample gas inlet, the high-temperature valve box and the activation gas inlet respectively; the output end of the flow control device is connected to the water removal device, the sample gas outlet and the high-temperature valve box; the two ends of the enrichment device are connected to the high-temperature valve box respectively; The flow control device is used to control the initial sample gas transmitted to the water removal device through the sample gas inlet, and to control the gas flow rate flowing from the activated gas inlet into the enrichment device; The dehydration device is used to remove water vapor from the initial sample gas to obtain a first sample gas containing CO2 and VOCs components, and transmit the first sample gas to the enrichment device; The enrichment device is used to enrich and remove the first sample gas, and remove carbon dioxide in the first sample gas to obtain a second sample gas; The high temperature valve box is used to heat the second sample gas to transmit the heated second sample gas to the VOCs analyzer for detection; A cold trap tube containing a plurality of adsorbents is arranged in the enrichment device; The high temperature valve box contains a plurality of multi-way valves, each of which is used to switch the working state of the enrichment device; A heating plate is provided at the bottom of the high-temperature valve box, and the heating plate is used to heat the second sample gas contained in the multi-way valve located at the heating plate; When the connection mode of the multiple multi-way valves is a sample gas enrichment mode, the input end of the enrichment device is connected to the sample gas inlet through the multiple multi-way valves, and the output end of the enrichment device is connected to the sample gas outlet through the multiple multi-way valves; When the connection mode of the multiple multi-way valves is the flash evaporation and desorption mode, the input end of the enrichment device is connected to the chromatographic inlet through the multiple multi-way valves, and the output end of the enrichment device is connected to the chromatographic carrier gas outlet through the multiple multi-way valves; When the communication mode of the plurality of multi-way valves is the activation and spacing mode, the input end of the enrichment device is connected to the tail gas outlet through the plurality of multi-way valves, and the output end of the enrichment device is connected to the activation gas inlet through the plurality of multi-way valves; The multiple multi-way valves include: 1 six-way valve and 3 three-way valves; wherein the first three-way valve and the second three-way valve of the three-way valve are located at the bottom of the high-temperature valve box; the six-way valve and the third three-way valve are located at the top of the high-temperature valve box; The working state of the enrichment device includes a sample gas enrichment mode, a flash desorption mode and an activation interval mode; Wherein, in the sample gas enrichment mode, the chromatographic inlet and the chromatographic carrier gas outlet are connected via the second three-way valve; the first sample gas enters the enrichment device via the six-way valve; In the flash desorption mode, the chromatographic inlet and the chromatographic carrier gas outlet are connected in sequence through the third three-way valve, the six-way valve, the enrichment device, the first three-way valve and the second three-way valve; the enrichment device heats the second sample gas, and the heated second sample gas is reversely input into the chromatographic inlet for VOCs analysis; In the activation interval mode, the activation gas inlet and the tail gas outlet are connected in sequence through the first three-way valve, the six-way valve, the enrichment device and the third three-way valve; the chromatographic inlet and the chromatographic carrier gas outlet are connected through the second three-way valve.

2. The enrichment device according to claim 1, characterized in that The flow control device comprises: at least one steady flow valve and at least one electronic flow sensor; wherein the steady flow valve is arranged at the sample gas inlet and the activation gas inlet; and the electronic flow sensor is arranged at the sample gas outlet.

3. The enrichment device according to claim 1, characterized in that A cold trap tube filled with glass beads is arranged in the water removal device; the refrigeration temperature range of the cold trap tube is: 0 to minus 30 degrees Celsius.

4. A VOCs analysis system, characterized in that: The system comprises: an enrichment device for online monitoring of VOCs and a VOCs analyzer as described in any one of claims 1 to 2; The enrichment device is used to enrich the sample gas containing VOCs components; The VOCs analyzer is used to analyze the enriched sample gas to obtain a VOCs analysis result of the sample gas.

5. A VOCs analysis method, characterized in that: The method is applied to the VOCs analysis system mentioned in claim 4, and the method comprises: Inputting a sample gas containing VOCs components into an enrichment device; wherein the enrichment device is an enrichment device for online monitoring of VOCs according to any one of claims 1 to 2; According to the working mode of the enrichment device, the VOCs sample gas is enriched and concentrated; wherein the working mode includes a sample gas enrichment mode, a flash desorption mode and an activation interval mode; The VOCs sample gas after enrichment and concentration is input into a VOCs analyzer for analysis to obtain the VOCs analysis result.

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