Low-temperature series valve isolation water removal device for a fully automatic purge and trap instrument

Abstract

The present invention relates to the technical field of purge and trap instruments, especially a low-temperature series valve isolation and water removal device for a fully automatic purge and trap instrument, which includes: a water removal pipe, a high-temperature six-way valve, a chromatographic carrier gas device, a GC injection port, a low-temperature trap tube, and a sample outlet. The six valve ports of the high-temperature six-way valve are sequentially numbered as port 1, port 2, port 3, port 4, port 5, and port 6. The port 2 is connected to the chromatographic carrier gas device, the port 3 is connected to the GC injection port, the port 5 is connected to the water removal pipe, the port 6 is connected to the sample outlet, and the two ends of the low-temperature trap tube are respectively connected to the port 1 and the port 4; both the water removal pipe and the low-temperature trap tube are sleeved with temperature-variable devices, and the low-temperature trap tube is filled with a composite VOCs adsorbent. The present invention can achieve low-temperature trapping at a minimum of -40°C and rapid heating with a heating rate of about 3000°C / min, without causing interference and discrimination effects on the measured VOCS components, and can quickly remove residual moisture.

Description

Technical Field

[0001] The present invention relates to the technical field of purge and trap instruments, and particularly to a low-temperature series valve isolation water removal device for a fully automatic purge and trap instrument. Background Art

[0002] The fully automatic purge and trap instrument is a dedicated sampling device for testing volatile organic compounds (VOCs) in water or soil in domestic and foreign soil environment standards. It is used for continuous fully automatic sampling and analysis of sample bottles, and is linked with peripheral gas chromatography and mass spectrometry to achieve unattended fully automatic analysis. The working principle of the fully automatic purge and trap instrument is as follows: Using the purge and trap technology, gas continuously passes through the sample, and the volatile components are extracted and trapped in an adsorbent or cold trap, and then analyzed and measured after the switching of the desorption valve; in this process, a water removal trap is often required.

[0003] Currently, the water removal traps on the market mainly include: adsorbent water removal traps and cyclone water cooling water removal traps. Their main influence is that the water removal efficiency is not high. The adsorbent will affect the adsorption efficiency of VOCs, bring discrimination effects to different VOCs, and easily cause cross-component interference to the sample.

[0004] The specific defects of the current water removal traps on the market are as follows:

[0005] (1) Interference of water

[0006] Excessive water in the trap tube is a common problem in the purge and trap method. The excessive presence of water will cause signal distortion. The interference of water causes abnormal peak shapes, low recovery rates of the compounds purged in the early stage, and also shortens the life of the detector; therefore, whether the influence of water vapor on the analysis and detection can be reduced is the primary issue to be considered when selecting the trap tube.

[0007] (2) Cross-contamination

[0008] Cross-contamination is caused by incomplete cold point concentration or desorption of the sample in the trap tube, resulting in a small amount of sample residue. This situation often stems from the overloaded operation of the system with moisture. Summary of the Invention

[0009] To solve the above problems, the main object of the present invention is to provide a low-temperature series valve isolation water removal device for a fully automatic purge and trap instrument, which has a compact structure, can achieve low-temperature trapping as low as -40°C and rapid heating with a heating rate of about 3000°C / min, and does not cause interference and discrimination effects to the measured VOCS components.

[0010] Another object of the present invention is to provide a low-temperature series valve isolation water removal device for a fully automatic purge and trap instrument, which can quickly remove the residual moisture, eliminate the pipeline blockage and pollution caused by moisture overload, and will not affect the next test.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A low-temperature series valve isolation and water removal device for a fully automatic purge and trap instrument, comprising: a water removal pipe, a high-temperature six-way valve, a chromatographic carrier gas device, a GC injection port, a low-temperature trap tube, and a sample outlet.

[0013] The six valve ports of the high-temperature six-way valve are sequentially the No. 1 port, the No. 2 port, the No. 3 port, the No. 4 port, the No. 5 port, and the No. 6 port in order. The No. 2 port is communicated with the chromatographic carrier gas device, the No. 3 port is communicated with the GC injection port, the No. 5 port is communicated with the water removal pipe, the No. 6 port is communicated with the sample outlet, and the two ends of the low-temperature trap tube are respectively communicated with the No. 1 port and the No. 4 port.

[0014] The water removal pipe and the low-temperature trap tube are both sleeved with a temperature-changing device. The temperature-changing device is a dual-channel low-temperature trap and rapid heating device, and the low-temperature trap tube is filled with a composite VOCs adsorbent.

[0015] The low-temperature series valve isolation and water removal device for a fully automatic purge and trap instrument further comprises: a first purge gas system and a second purge gas system. The first purge gas system is used to introduce purge gas into the water removal pipe, and the second purge gas system is used to introduce back purge gas into the sample outlet.

[0016] Further, the high-temperature six-way valve has two states, which are respectively:

[0017] State 1: The No. 1 port is communicated with the No. 6 port, the No. 2 port is communicated with the No. 3 port, and the No. 4 port is communicated with the No. 5 port.

[0018] State 2: The No. 1 port is communicated with the No. 2 port, the No. 3 port is communicated with the No. 4 port, and the No. 5 port is communicated with the No. 6 port.

[0019] Further, during the water removal and VOCs adsorption process, the high-temperature six-way valve is switched to State 1, and the temperature is set in the range of -35°C to -350°C through the temperature-changing device. The purge gas rich in water vapor and VOCs is blown into the water removal pipe, and then the purge gas sequentially passes through the water removal pipe, the high-temperature six-way valve, the low-temperature trap tube, the high-temperature six-way valve and flows out from the sample outlet. Finally, the water vapor condenses in the water removal pipe, and the VOCs are enriched in the low-temperature trap tube.

[0020] Further, during the desorption and injection process, the high-temperature six-way valve is switched to State 2, and the temperature in the low-temperature trap tube is rapidly increased through the temperature-changing device, so that the VOCs enriched in the low-temperature trap tube volatilize, and the VOCs are brought to the GC injection port by the chromatographic carrier gas for analysis and detection.

[0021] Further, during the backflush and activation processes, switch the high-temperature six-way valve to State 1, set the temperature within the range of 50°C to 400°C through the temperature-varying device, and introduce the backflush gas into the sample outlet, thereby discharging the VOCs remaining in the low-temperature trap tube and the moisture in the water removal tube.

[0022] The beneficial effects of the present invention are as follows:

[0023] The present invention employs a water removal tube, a high-temperature six-way valve, a chromatographic carrier gas device, a GC injection port, and a low-temperature trap tube, featuring a compact structure. It can achieve low-temperature trapping as low as -40°C, effectively condensing water vapor in the water removal tube and eliminating the interference of water.

[0024] The present invention adopts a dual-channel low-temperature trapping and rapid heating device, which can achieve rapid heating with a heating rate of approximately 3000°C / min, improving work efficiency.

[0025] Therefore, the present invention does not cause interference and discrimination effects on the measured VOCS components.

[0026] The present invention quickly removes the residual moisture by the back gas and heating the water removal tube, eliminating the blockage and contamination of the pipeline caused by water overload and not affecting the next test. Description of the Drawings

[0027] Figure 1 is a schematic diagram of the present invention in the trapping state.

[0028] Figure 2 is a schematic diagram of the present invention in the desorption and injection states.

[0029] Explanation of the reference numerals in the drawings: 1. Chromatographic carrier gas device; 2. High-temperature six-way valve; 3. GC injection port; 4. Low-temperature trap tube; 5. Water removal tube; 6. Sample outlet. Detailed Embodiments

[0030] Please refer to Figure 1 As shown, the present invention relates to a low-temperature series valve isolation water removal device for a fully automatic purge and trap instrument, comprising: a water removal tube 5, a high-temperature six-way valve 2, a chromatographic carrier gas device 1, a GC injection port 3, a low-temperature trap tube 4, and a sample outlet 6.

[0031] The six valve ports of the high-temperature six-way valve 2 are sequentially the 1st port, the 2nd port, the 3rd port, the 4th port, the 5th port, and the 6th port. The 2nd port is connected to the chromatographic carrier gas device 1, the 3rd port is connected to the GC injection port 3, the 5th port is connected to the water removal tube 5, the 6th port is connected to the sample outlet 6, and the two ends of the low-temperature trap tube 4 are respectively connected to the 1st port and the 4th port.

[0032] Both the water removal pipe 5 and the low-temperature trapping pipe 4 are sleeved with a temperature-changing device, which is a dual-channel low-temperature trapping and rapid heating device (please refer to the patent application number CN201922024498.6). This dual-channel low-temperature trapping and rapid heating device can achieve low-temperature trapping at a minimum of -40°C and rapid heating with a heating rate of about 3000°C / min, and no condensed water is precipitated;

[0033] The low-temperature trapping pipe 4 is filled with a composite VOCs adsorbent;

[0034] The low-temperature series valve isolation water removal device of the automatic purge and trap analyzer further includes: a first purge gas system and a second purge gas system. The first purge gas system is used to introduce purge gas into the water removal pipe 5, and the second purge gas system is used to introduce reverse purge gas into the sample outlet 6; it should be noted that both the purge gas and the reverse purge gas are inert gases (nitrogen), and among them, the purge gas also contains a large amount of water vapor and VOCs.

[0035] Furthermore, the high-temperature six-way valve 2 has two states, namely:

[0036] State 1: The port 1 is connected to the port 6, the port 2 is connected to the port 3, and the port 4 is connected to the port 5;

[0037] State 2: The port 1 is connected to the port 2, the port 3 is connected to the port 4, and the port 5 is connected to the port 6.

[0038] During the water removal and VOCs adsorption process, the high-temperature six-way valve 2 is switched to State 1, and the temperature is set in the range of -35°C to -350°C through the temperature-changing device. The purge gas rich in water vapor and VOCs is blown into the water removal pipe 5, then the purge gas sequentially passes through the water removal pipe 5, the high-temperature six-way valve 2, the low-temperature trapping pipe 4, the high-temperature six-way valve 2 and flows out from the sample outlet 6; finally, the water vapor condenses in the water removal pipe 5, the VOCs are enriched in the low-temperature trapping pipe 4, and the inert gas flows out from the sample outlet 6;

[0039] It should be noted that the water removal pipe 5 is an empty pipe. In the low-temperature state, the water removal pipe 5 can condense the moisture in the purge gas. Because the condensation point of VOCs is much lower than the temperature of the moisture, it can quickly pass through the water removal pipe 5. The low-temperature trapping pipe 4 is filled with a composite VOCs adsorbent, and the VOCs in the purge gas are enriched in the low-temperature trapping pipe 4, and inert gases such as nitrogen flow out from the outlet.

[0040] During the desorption and sample injection process (please refer to Figure 2As shown, switch the high-temperature six-way valve 2 to state two, and rapidly increase the temperature in the low-temperature trap 4 through the temperature-changing device, so that the VOCs enriched in the low-temperature trap 4 volatilize, and the VOCs are carried to the GC injection port 3 by the chromatographic carrier gas for analysis and detection;

[0041] In the above solution, by rapidly heating up according to the set desorption temperature program, three-stage temperature desorption injection can be achieved. The VOCs enriched in the low-temperature trap 4 volatilize due to the high temperature and become gaseous, and are carried to the GC injection port 3 by the chromatographic carrier gas for analysis and detection.

[0042] During the backflush and activation process, switch the high-temperature six-way valve 2 to state one, set the temperature in the range of 50°C to 400°C through the temperature-changing device, and introduce the backflush gas into the sample outlet 6, so as to carry out the VOCs remaining in the low-temperature trap 4 and the moisture in the water removal tube 5 out;

[0043] In the above solution, by the back gas and heating the water removal tube 5, the remaining moisture is rapidly removed, and the blockage and pollution of the pipeline caused by moisture overload are eliminated, without affecting the next test.

[0044] The above embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary engineering and technical personnel in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A low-temperature series valve isolation water removal device for a fully automatic purge and trap instrument, characterized in that, It includes: a water removal pipe, a high-temperature six-way valve, a chromatographic carrier gas device, a GC injection port, a low-temperature trap tube, and a sample outlet. The six valve ports of the high-temperature six-way valve are sequentially the No. 1 port, the No. 2 port, the No. 3 port, the No. 4 port, the No. 5 port, and the No. 6 port. The No. 2 port is connected to the chromatographic carrier gas device, the No. 3 port is connected to the GC injection port, the No. 5 port is connected to the water removal pipe, the No. 6 port is connected to the sample outlet, and the two ends of the low-temperature trap tube are respectively connected to the No. 1 port and the No. 4 port. Both the water removal pipe and the low-temperature trap tube are sleeved with a temperature-variable device. The temperature-variable device is a dual-channel low-temperature trap and rapid heating device, and the low-temperature trap tube is filled with a composite VOCs adsorbent. The low-temperature series valve water removal device of the fully automatic purge and trap instrument further includes: a first purge gas system and a second purge gas system. The first purge gas system is used to introduce purge gas into the water removal pipe, and the second purge gas system is used to introduce reverse purge gas into the sample outlet. State 1: The No. 1 port is connected to the No. 6 port, the No. 2 port is connected to the No. 3 port, and the No. 4 port is connected to the No. 5 port. State 2: The No. 1 port is connected to the No. 2 port, the No. 3 port is connected to the No. 4 port, and the No. 5 port is connected to the No. 6 port.

2. The low-temperature series valve isolation and water removal device of a fully automatic purge and trap instrument according to claim 1, wherein During the water removal and VOCs adsorption process, the high-temperature six-way valve is switched to State 1, the temperature is set in the range of -35°C to -350°C through the temperature-variable device, and the purge gas rich in water vapor and VOCs is blown into the water removal pipe. Then the purge gas sequentially passes through the water removal pipe, the high-temperature six-way valve, the low-temperature trap tube, the high-temperature six-way valve and flows out from the sample outlet. Finally, the water vapor condenses in the water removal pipe, and the VOCs are enriched in the low-temperature trap tube.

3. The low-temperature series valve isolation and water removal device of a fully automatic purge and trap instrument according to claim 2, characterized in that, During the desorption and injection process, the high-temperature six-way valve is switched to State 2, the temperature in the low-temperature trap tube is rapidly increased through the temperature-variable device, so that the VOCs enriched in the low-temperature trap tube volatilize, and the VOCs are carried to the GC injection port by the chromatographic carrier gas for analysis and detection.

4. The low-temperature series valve isolation and water removal device of a fully automatic purge and trap instrument according to claim 3, characterized in that, During the backflushing and activation process, the high-temperature six-way valve is switched to State 1, the temperature is set in the range of 50°C to 400°C through the temperature-variable device, and the reverse purge gas is introduced into the sample outlet, so as to carry out the residual VOCs in the low-temperature trap tube and the moisture in the water removal pipe out.

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