Ion mobility spectrometry capable of automatically draining and dehumidifying

Abstract

The utility model relates to an automatic drainage and dehumidification ion mobility spectrometry, which comprises an ion migration tube, a semiconductor refrigeration and dehumidification device, a first mass flow meter, an air exhaust sampling pump, a second mass flow meter, a dehumidification filter, a three-way connector and a data acquisition system, the semiconductor refrigeration dehumidifier is a closed cavity, a semiconductor refrigeration piece for cooling and an electric heating element for heating are arranged on the opposite side wall faces of the cavity respectively, in the sampling-sample injection detection process, the semiconductor refrigeration piece in the semiconductor refrigeration dehumidifier starts to work, sample gas is subjected to dehumidification and drainage stages, and the sample gas is cooled by the electric heating element. When the sample gas is detected, an electric heating element in the semiconductor refrigeration dehumidifier starts to heat, residual liquid water in the semiconductor refrigeration dehumidifier is converted into vaporous water through heating, and the ion mobility spectrometry is refrigerated and dehumidified through the semiconductor, so that the influence of high water vapor humidity in the environment on the sample gas detection is effectively eliminated, and a complicated sample pretreatment process is not needed.

Description

Technical Field

[0001] The utility model belongs to the field of analytical chemical instruments, and in particular relates to an ion mobility spectrometer with automatic drainage and dehumidification. Background Art

[0002] Hydrogen sulfide (H2S), also known as sewer gas, deep well gas, biogas, and manure gas, is a toxic and highly corrosive gas that is often produced in confined spaces such as sewer systems. If released into the atmosphere in large quantities, it poses a serious threat to human health and life. H2S concentrations above 20 ppb can cause discomfort. The U.S. Occupational Safety and Health Administration has established 10 ppm as the limit for human exposure for eight hours. It is currently the second leading cause of mortality from inhaled toxic gases in public settings. Furthermore, when H2S is present in large quantities in sewer systems, its acidic properties and the associated microorganisms it induces can corrode and damage sewer system structures, leading to expensive additional maintenance and replacement costs. Therefore, real-time monitoring of H2S levels in sewer systems is crucial for public health and safety, as well as for sewer system maintenance. Currently, numerous methods have been proposed and applied for the detection of environmental H2S. Gas chromatography (GC)-based methods offer excellent sensitivity and accuracy, and are recognized as the gold standard. However, these methods often involve complex sample pretreatment and analysis steps, and the detection instruments are bulky, making them unsuitable for real-time, on-site monitoring. Methods based on chemical sensors offer advantages such as high sensitivity, low cost, and simplified sample pretreatment. However, they also have significant drawbacks, such as long response times, poor selectivity, and susceptibility to environmental influences such as matrix, temperature, and humidity. Therefore, developing rapid, sensitive, and environmentally resistant methods is of practical value for real-time monitoring of H2S in sewage systems.

[0003] As a technique based on the difference in ion mobility of atmospheric pressure gaseous ion separation, ion mobility spectrometry (IMS) has a special significance in environmental analysis. Its advantages are ease of use, high sensitivity, strong analytical flexibility and rapid analysis. Its advantageous features are low power consumption, good portability, high speed and suitability for on-site analysis. Conventional ionization sources are radioactive 63 Ni ionization source is not suitable for widespread use. Although non-radioactive ionization source UV-IMS has been used in environmental monitoring and analysis, it is easily affected by other sulfur interferences and moisture. When using photoionization, when the humidity in the sample gradually increases, the signal intensity decreases to almost zero. There are two main reasons for signal attenuation. First, as the humidity gradually increases to 95%, the RIP signal intensity attenuates severely; second, when the humidity in the reaction area is higher than the CO2 content in the air, O2 - (H2O)n Become the main reagent ion, among which O2 - Cluster reactions with H2O further weaken the RIP signal intensity and the efficiency of H2S adsorption and ionization, leading to a decrease in H2S detection sensitivity. Therefore, humidity is an issue that must be addressed when detecting H2S in the environment.

[0004] Cooling enrichment has been widely used in sulfide detection. Earlier, liquefied gases such as nitrogen and argon were used to cool the enrichment trap. For example, Wardencki et al. used liquid nitrogen to cool the trap to -196°C. Alternatively, some researchers have employed the Peltier effect to cool the enrichment trap. Compared to liquefied gas cooling, this method is easier to implement and offers advantages such as minimal interference with detection. Peltier cooling can separate target substances from complex matrices based on differences in their liquefaction temperatures or freezing points. Utility Model Content

[0005] To address the existing problem of ambient humidity interfering with hydrogen sulfide detection, this utility model utilizes the Peltier cooling effect of semiconductor materials to design a semiconductor cooling sampling device. This device removes high levels of water vapor from actual samples, such as exhaled breath or sewage gas, during the sampling process. Combined with reagent-assisted negative ion photoionization ion mobility spectrometry in unidirectional airflow mode, it enables the detection of NO in exhaled breath and the online monitoring of H2S in sewage.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] An ion mobility spectrometer with automatic drainage and dehumidification, comprising an ion mobility spectrometer, a semiconductor refrigeration and dehumidification device, a first mass flow meter, an air extraction sampling pump, a second mass flow meter, a dehumidification filter three-way connector, and a data acquisition system;

[0008] The semiconductor refrigeration and dehumidification device includes a semiconductor refrigeration and dehumidifier, a first three-way solenoid valve, a two-way solenoid valve, a second three-way solenoid valve, and an air pump;

[0009] The semiconductor refrigeration dehumidifier is a closed cavity. On the opposite side walls of the cavity, there are respectively provided with a semiconductor refrigeration plate for cooling and an electric heating element for heating. An air inlet and an air outlet of the semiconductor refrigeration dehumidifier are respectively provided at two diagonally opposite positions on the upper bottom surface of the cavity. The air outlet of the semiconductor refrigeration dehumidifier is connected to the ion transfer tube via a second three-way solenoid valve.

[0010] An upper baffle parallel to the left and right side walls is vertically downwardly arranged on the upper bottom surface of the closed cavity, and an air flow channel is formed between the top of the upper baffle and the lower bottom surface of the cavity. A lower baffle parallel to the upper baffle is vertically upwardly arranged on the lower bottom surface of the cavity body, and the lower baffles are alternately arranged with the upper baffles. An air flow channel is formed between the top of the lower baffle and the upper bottom surface of the cavity. A gas cooling channel is formed by the upper bottom surface, side walls, upper baffles, lower baffles and lower bottom surface of the cavity. The interior of the lower bottom surface of the cavity is a hollow structure to form a water storage tank. Drain holes pointing vertically downward are evenly arranged on the lower bottom surface of the cavity between the left and right side walls of the cavity and the lower baffles or between adjacent lower baffles. The drainage holes open at the top of the water storage tank, and the bottom surface of the water storage tank is inclined at 10-30 degrees to the horizontal plane to form a drainage outlet on the side wall of the cavity.

[0011] The air inlet of the semiconductor refrigeration dehumidifier is connected to the outlet of the first three-way solenoid valve, the first inlet of the first three-way solenoid valve is connected to the sample gas source, and the second inlet of the first three-way solenoid valve is connected to the purge gas source; the air outlet of the semiconductor refrigeration dehumidifier is connected to the inlet of a three-way joint, the two outlets of the three-way joint are respectively connected to the first inlet of the second three-way solenoid valve and the inlet of the two-way solenoid valve, the outlet of the second three-way solenoid valve is connected to the air inlet of the ion mobility spectrometer, the second inlet of the second three-way solenoid valve is connected to the purge gas source, and the outlet of the two-way solenoid valve is connected to the vacuum pump.

[0012] The ion transfer tube includes a photoionization source and a Faraday plate, which are arranged opposite each other at the left and right ends, respectively, and an ion gate located between the photoionization source and the Faraday plate. The area between the photoionization source and the ion gate is the ion molecule reaction area, and the area between the ion gate and the Faraday plate is the migration area. The Faraday plate is connected to the data acquisition device through an amplifier.

[0013] An ion transfer tube air inlet is provided on the upper wall of the ion transfer tube reaction zone near the ion gate, and the ion transfer tube air inlet is connected to the semiconductor refrigeration dehumidifier air outlet through a second three-way solenoid valve;

[0014] An ion transfer tube gas outlet is provided on the upper wall of the ion transfer tube reaction zone near the photoionization source, and the ion transfer tube gas outlet is connected to the inlet of the gas sampling pump through a first mass flow meter;

[0015] A floating gas inlet is provided above the Faraday disk at the right end of the ion transfer tube. The floating gas inlet is connected to the outlet of the air sampling pump through a pipeline, a second mass flow meter, a three-way joint, and a dehumidification filter.

[0016] Furthermore, the upper partition and the lower partition are made of stainless steel or aluminum, and the distance between adjacent upper partitions and lower partitions is 4-8 cm.

[0017] Furthermore, the ion mobility spectrometry is photoionization ion mobility spectrometry; and the photoionization source is a vacuum ultraviolet lamp.

[0018] Furthermore, the semiconductor refrigeration dehumidifier has a refrigeration temperature range of 10°C to -6°C.

[0019] Furthermore, the electric heating element used in the semiconductor refrigeration dehumidifier is a heating rod, and the heating temperature range is 100-180°C.

[0020] Furthermore, the dehumidification filter is filled with a molecular sieve, which is aluminum oxide and / or silicon dioxide, and is used to remove H2O, CO2 and hydrocarbons in the adsorbed gas flowing through.

[0021] During the sampling-injection test, the semiconductor refrigeration plate in the semiconductor refrigeration dehumidifier starts to work. Under the action of the air extraction sampling pump, the sample gas enters the semiconductor refrigeration dehumidifier through the first three-way solenoid valve for dehumidification. The water vapor is cooled into liquid water at low temperature. The liquid water enters the water storage tank through the drainage hole and is discharged from the semiconductor refrigeration dehumidifier through the drainage slope and the drainage port. The sample gas after dehydration enters the ion transfer tube for detection. The detected gas passes through the dehumidification filter and the second mass flow meter and enters the migration zone of the ion transfer tube through the floating gas inlet in the form of floating gas.

[0022] During the drainage phase, the semiconductor cooling chip stops working, and the electric heating element in the semiconductor cooling dehumidifier begins to heat up. The three solenoid valves automatically switch, and the remaining liquid water in the semiconductor cooling dehumidifier is heated to convert into gaseous water. The vacuum pump is turned on, and purge gas enters the semiconductor cooling dehumidifier through the first three-way solenoid valve. The gaseous water is then discharged through the two-way solenoid valve under the purge action of the purge gas. At the same time, another clean purge gas is introduced into the IMS through the second three-way solenoid valve to ensure the cleanliness of the migration tube.

[0023] The purge gas is compressed air treated with silica gel, activated carbon, and molecular sieves. During the sampling and injection process, the electric field strength of the ion migration tube is 300-500 V / cm, the temperature of the migration tube is 50-200°C, and the flow rate of the ion mobility spectrometer sampling pump is 100-500 mL / min. The flow rate of the first mass flowmeter is 500-1000 mL / min, and the flow rate of the second mass flowmeter is set at 400-700 mL / min.

[0024] Compared with the prior art, the advantages of the present invention are: through semiconductor refrigeration and dehumidification, the influence of high water vapor humidity in the environment is effectively eliminated, and no complicated sample pre-treatment process is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1This is a structural schematic diagram of an ion mobility spectrometer with automatic drainage and dehumidification of the utility model; wherein 1 is a photoionization source, 2 is an ion molecule reaction zone, 3 is an ion gate, 4 is a migration zone, 5 is a heat preservation and heating jacket, 6 is a Faraday disk, 7 is an amplifier, 8 is a data acquisition device, 9 is a drift gas inlet, 10 is a second mass flow meter, 11 is a three-way connector, 16 is a semiconductor refrigeration and dehumidification device, 17 is an ion migration tube air inlet, 18 is an ion migration tube air outlet, 19 is a first mass flow meter, 20 is an air extraction sampling pump, and 21 is a dehumidification filter.

[0026] Figure 2 Schematic diagram of the structure of a semiconductor refrigeration and dehumidification device, wherein 101 is a semiconductor refrigeration and dehumidifier, 102 is a first three-way solenoid valve, 103 is a two-way solenoid valve, 104 is a second three-way solenoid valve, 105 is a first port of the first three-way solenoid valve, 106 is an outlet of the first three-way solenoid valve, 107 is an air inlet of the conductor refrigeration and dehumidifier, 108 is an air outlet of the semiconductor refrigeration and dehumidifier, 109 is a first inlet of the second three-way solenoid valve, 110 is an outlet of the second three-way solenoid valve, 111 is purge gas, 112 is a second inlet of the first three-way solenoid valve, 113 is a second inlet of the second three-way solenoid valve, 114 is an inlet of the two-way solenoid valve, 115 is an outlet of the two-way solenoid valve, and 116 is an air pump.

[0027] Figure 3 Schematic diagram of the internal structure of a semiconductor refrigerator, where 201 is the upper partition, 202 is the lower partition, 203 is the drainage hole, 204 is the water storage tank, 205 is the drainage port, 206 is the air flow channel, 207 is the semiconductor cooling plate, 208 is the electric heating element, 107 is the air inlet of the conductor cooling dehumidifier, and 108 is the air outlet of the semiconductor cooling dehumidifier. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1 、 Figure 2 、 Figure 3 As shown, the utility model provides an ion mobility spectrometer with automatic drainage and dehumidification, including an ion migration tube, a semiconductor refrigeration and dehumidification device 16, a first mass flow meter 19, an air sampling pump 20, a second mass flow meter 10, a dehumidification filter 21, a three-way connector 11, and a data acquisition system 8;

[0030] The semiconductor refrigeration and dehumidification device includes a semiconductor refrigeration and dehumidifier 101, a first three-way solenoid valve 102, a two-way solenoid valve 103, a second three-way solenoid valve 104 and an air pump 116.

[0031] The semiconductor refrigeration dehumidifier 101 is a rectangular closed cavity with an internal length of 80 cm, a width of 65 cm, and a height of 65 cm. A semiconductor refrigeration plate 207 for cooling and an electric heating element 208 for heating are provided on the longer opposite side walls of the cavity. A semiconductor refrigeration dehumidifier air inlet 107 and a semiconductor refrigeration dehumidifier air outlet 108 are respectively provided at two diagonally opposite positions on the upper bottom surface of the cavity. The semiconductor refrigeration dehumidifier air outlet 108 is connected to the ion transfer tube via a second three-way solenoid valve.

[0032] An upper partition 201 parallel to the left and right side walls is vertically downwardly arranged on the upper bottom surface inside the closed cavity, and an air flow channel 206 is formed between the top of the upper partition and the lower bottom surface of the cavity. A lower partition 202 parallel to the upper partition is vertically upwardly arranged on the lower bottom surface inside the cavity. The lower partitions and the upper partitions are alternately arranged, and an air flow channel 206 is formed between the top of the lower partition and the upper bottom surface of the cavity. The interior of the lower bottom surface of the cavity is a hollow structure to form a water storage tank 204. Drain holes 203 facing vertically downward are evenly arranged on the lower bottom surface of the cavity between the left and right side walls of the cavity and the lower partition or between adjacent lower partitions. The drainage holes 203 are opened at the top of the water storage tank. The bottom surface of the water storage tank 204 is inclined at 10-30 degrees to the horizontal plane to form a drainage slope, and a drainage port 205 is opened on the side wall of the cavity.

[0033] The air inlet of the semiconductor refrigeration dehumidifier is connected to the outlet 106 of the first three-way solenoid valve, the first inlet 105 of the first three-way solenoid valve is connected to the sample gas source, and the second inlet 112 of the first three-way solenoid valve is connected to the purge gas source; the air outlet 108 of the semiconductor refrigeration dehumidifier is connected to the inlet of a three-way joint, the two outlets of the three-way joint are respectively connected to the first inlet 109 of the second three-way solenoid valve and the inlet 114 of the two-way solenoid valve, the outlet 110 of the second three-way solenoid valve is connected to the air inlet of the ion migration spectrometer, the second inlet 113 of the second three-way solenoid valve is connected to the purge gas source, and the outlet 115 of the two-way solenoid valve is connected to the vacuum pump 116.

[0034] The ion transfer tube includes a photoionization source 1 and a Faraday plate 6 disposed opposite each other at the left and right ends, respectively, and an ion gate 3 located between the photoionization source and the Faraday plate. The region between the photoionization source and the ion gate is the ion molecule reaction region 2, and the region between the ion gate and the Faraday plate is the migration region 4. The Faraday plate is connected to a data acquisition device 8 via an amplifier 7.

[0035] An ion transfer tube air inlet 17 is provided on the upper wall of the ion transfer tube reaction zone near the ion gate. The ion transfer tube air inlet is connected to the semiconductor refrigeration dehumidifier air outlet 108 through the outlet 110 of the second three-way solenoid valve.

[0036] An ion transfer tube gas outlet 18 is provided on the upper wall of the ion transfer tube reaction zone near the photoionization source. The ion transfer tube gas outlet 18 is connected to the inlet of the gas sampling pump 20 through a first mass flow meter 19.

[0037] A drift gas inlet 9 is provided above the Faraday disk at the right end of the ion transfer tube. The drift gas inlet 9 is connected to the outlet of the air sampling pump 20 through a pipeline, a second mass flow meter 10, a three-way joint 11, and a dehumidification filter 21.

[0038] The photoionization source is a vacuum ultraviolet lamp, the upper and lower partitions are made of stainless steel, are parallel to the longer side wall, and the distance between adjacent upper and lower partitions is 5 cm; the dehumidification filter is filled with aluminum oxide and / or silicon dioxide molecular sieve.

[0039] In the sampling-injection test, the semiconductor refrigeration chip in the semiconductor refrigeration dehumidifier starts to work. The sample gas enters the semiconductor refrigeration dehumidifier through the first three-way solenoid valve under the action of the air sampling pump 20 to remove water. The water vapor is cooled into liquid water at low temperature. The liquid water enters the water storage tank through the drainage hole and is discharged from the semiconductor refrigeration dehumidifier through the drainage channel and the drain port. The sample gas after dehydration enters the ion transfer tube for detection. Figure 2 As shown by the solid line in (a), the detected gas passes through the dehumidification filter and the second mass flow meter and enters the migration zone of the ion transfer tube through the drift gas inlet in the form of drift gas.

[0040] During the drainage phase, the semiconductor refrigeration chip stops working, the electric heating element in the semiconductor refrigeration dehumidifier starts to heat up, and the three solenoid valves automatically switch. The remaining liquid water in the semiconductor refrigeration dehumidifier is heated and converted into gaseous water. The vacuum pump is turned on, and the purge gas enters the semiconductor refrigeration dehumidifier through the first three-way solenoid valve. The gaseous water is discharged through the two-way solenoid valve under the purge effect of the purge gas. At the same time, another clean purge gas is introduced into the IMS through the second three-way solenoid valve to ensure the cleanliness of the migration tube. Figure 2 (b) is shown by the solid line.

[0041] The purge gas is compressed air treated with silica gel, activated carbon and molecular sieve.

Claims

1. An ion mobility spectrometer with automatic drainage and dehumidification, characterized by: The ion mobility spectrometer includes an ion transfer tube, a semiconductor refrigeration and dehumidification device, a first mass flow meter, an air extraction sampling pump, a second mass flow meter, a dehumidification filter, a three-way connector, and a data acquisition system; The semiconductor refrigeration and dehumidification device includes a semiconductor refrigeration and dehumidifier, a first three-way solenoid valve, a two-way solenoid valve, a second three-way solenoid valve, and an air pump; The semiconductor refrigeration dehumidifier is a closed cavity, with semiconductor refrigeration plates for cooling and electric heating elements for heating respectively provided on opposite side walls of the cavity. An air inlet and an air outlet of the semiconductor refrigeration dehumidifier are respectively provided at two diagonally opposite positions on the upper bottom surface of the cavity. The air outlets of the semiconductor refrigeration dehumidifier are connected to the ion transfer tube. An upper baffle parallel to the left and right side walls is vertically downwardly arranged on the upper bottom surface of the closed cavity, forming an airflow channel between the top of the upper baffle and the lower bottom surface of the cavity. A lower baffle parallel to the upper baffle is vertically upwardly arranged on the lower bottom surface of the cavity, and the lower baffles are alternately arranged with the upper baffles. An airflow channel is formed between the top of the lower baffle and the upper bottom surface of the cavity. A gas cooling channel is formed by the upper bottom surface, side walls, upper baffles, lower baffles and lower bottom surface of the cavity. The interior of the lower bottom surface of the cavity is a hollow structure forming a water storage tank. Drain holes pointing vertically downward are evenly arranged on the lower bottom surface of the cavity between the left and right side walls of the cavity and the lower baffle, or on the lower bottom surface of the cavity between adjacent lower baffles. The drainage holes open at the top of the water storage tank, and the bottom surface of the water storage tank is inclined at 10-30 degrees to the horizontal plane to form a drainage outlet on the side wall of the cavity. The air inlet of the semiconductor refrigeration dehumidifier is connected to the outlet of the first three-way solenoid valve, the first inlet of the first three-way solenoid valve is connected to the sample gas source, and the second inlet of the first three-way solenoid valve is connected to the purge gas source; the air outlet of the semiconductor refrigeration dehumidifier is connected to the inlet of a three-way joint, the two outlets of the three-way joint are respectively connected to the first inlet of the second three-way solenoid valve and the inlet of the two-way solenoid valve, the outlet of the second three-way solenoid valve is connected to the air inlet of the ion mobility spectrometer, the second inlet of the second three-way solenoid valve is connected to the purge gas source, and the outlet of the two-way solenoid valve is connected to the vacuum pump.

2. The ion mobility spectrometer according to claim 1, characterized in that The ion transfer tube includes a photoionization source and a Faraday plate, which are arranged opposite each other at the left and right ends, respectively, and an ion gate located between the photoionization source and the Faraday plate. The area between the photoionization source and the ion gate is the ion molecule reaction area, and the area between the ion gate and the Faraday plate is the migration area. The Faraday plate is connected to the data acquisition device through an amplifier. An ion transfer tube air inlet is provided on the upper wall of the ion transfer tube reaction zone near the ion gate, and the ion transfer tube air inlet is connected to the semiconductor refrigeration dehumidifier air outlet through a second three-way solenoid valve; An ion transfer tube gas outlet is provided on the upper wall of the ion transfer tube reaction zone near the photoionization source, and the ion transfer tube gas outlet is connected to the inlet of the gas sampling pump through a first mass flow meter; A floating gas inlet is provided above the Faraday disk at the right end of the ion transfer tube. The floating gas inlet is connected to the outlet of the air sampling pump through a pipeline, a second mass flow meter, a three-way joint, and a dehumidification filter.

3. The ion mobility spectrometer according to claim 1, characterized in that The upper partition and the lower partition are made of stainless steel or aluminum, and the distance between adjacent upper partitions and lower partitions is 4-8 cm.

4. The ion mobility spectrometer according to claim 1, characterized in that The ion mobility spectrometry is photoionization ion mobility spectrometry.

5. The ion mobility spectrometer according to claim 2, characterized in that The photoionization source is a vacuum ultraviolet lamp.

6. The ion mobility spectrometer according to claim 1, characterized in that The temperature range of the semiconductor refrigeration dehumidifier is 10°C to -6°C.

7. The ion mobility spectrometer according to claim 1, characterized in that The electric heating element used in the semiconductor refrigeration dehumidifier is a heating rod, and the heating temperature range is 100-180°C.

8. The ion mobility spectrometer according to claim 1, characterized in that The dehumidification filter is filled with molecular sieves, which are aluminum oxide and / or silicon dioxide.

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