Purging and trapping device
By installing a mass flow controller and pressure gauge in the purge and trap device, combined with a sampling pump and a multi-way valve, gas path balance is achieved, solving the problem of low efficiency in traditional purge methods and improving sample recovery rate and accuracy of detection results.
Patent Information
- Application Number
- CN202423004285.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-06
AI Technical Summary
Traditional purging methods have low recovery efficiency, leading to sample loss during VOCs analysis in water, affecting the detection limit and extending the analysis cycle.
By installing a mass flow controller and pressure gauge in the purge and trap device, the purge gas flow rate is controlled and the real-time pressure value is monitored. Combined with a sampling pump and a multi-way valve, gas path balance is achieved to prevent gas leakage. The gas is then adsorbed, concentrated, and desorbed through the trap, thereby improving the purge efficiency.
It improves the efficiency of the purge and trap process, prevents gas leakage, ensures that the sample enters the equipment completely, shortens the analysis cycle, and improves the accuracy and consistency of the test results.
Smart Images
Figure CN223623956U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of gas detection technology, and in particular to a purging and collection device. Background Technology
[0002] The purge-and-trap device collects VOCs-containing water samples into a flow-through cell. An inert gas at a constant flow rate is continuously purged into the water sample for a defined time, causing the VOCs to escape. These VOCs are then adsorbed and concentrated in a trap filled with a specific adsorption material. After adsorption, the trap is rapidly heated to desorb the analytes. Finally, a carrier gas transports the analytes desorbed from the trap packing material to the detector. In online VOCs monitoring in water, to ensure sample representativeness, the flow-through cell is typically large. However, traditional purge methods have low recovery efficiency, leading to ineffective capture of target substances during analysis, sample loss, reduced detection limits, and extended analysis cycles. Utility Model Content
[0003] To solve the above problems, this utility model provides the following technical solution:
[0004] This utility model provides a purge and trap device, including a mass flow controller, a pressure gauge, a flow cell, a trap, a dewatering trap, a sampling pump, a multi-way valve, and a detector. A mass flow controller is installed at the purge gas inlet, connected to the pressure gauge. The pressure gauge is connected to the flow cell via a three-way valve. The flow cell is connected to the multi-way valve. The first port of the multi-way valve is connected to the dewatering trap, which is connected to the trap. The trap is connected to the second port of the multi-way valve. The multi-way valve is connected to a three-way valve and the sampling pump via a three-way valve. The sampling pump is connected to the outlet. The third port of the multi-way valve is connected to the carrier gas inlet. The fourth valve is connected to the detector. The purge gas flow rate is controlled by a mass flow controller, and the real-time pressure value is monitored by a pressure gauge to purge the sample. Components in the flow cell are purged by the purge gas, enter the dehydration trap for dehydration, and finally enter the collection trap for enrichment. During the purging and enrichment process, the sampling pump is turned on to balance the gas pressure in the pipeline with the atmospheric pressure and prevent purge gas from overflowing. After low-temperature enrichment is completed, the collection trap is heated for desorption, and the multi-port valve switches to send the desorbed sample into the detector. By setting up a sampling pump and pressure gauge in the flow path, the headspace pressure of the flow cell is balanced during the purging and collection process, so that all the purge gas enters the device without overflowing, thereby improving the purging and collection efficiency.
[0005] Furthermore, the sampling flow rate of the sampling pump is set to be the same as the purging flow rate of the purging gas.
[0006] Furthermore, a purge valve is also provided between the tee and the flow pool.
[0007] Furthermore, an injection valve is provided between the flow cell and the multi-way valve. By providing a multi-way valve, a three-way valve, a purge valve, and an injection valve, and by controlling the opening and closing of the valve ports of the multi-way valve, the three-way valve, the purge valve, and the injection valve, the flow path can automatically perform airtightness detection, which helps to prevent gas leakage.
[0008] Furthermore, the three-way valve is a three-way solenoid valve.
[0009] Furthermore, the trap includes a trapping tube, a heat-conducting layer, and a heating wire. The heat-conducting layer is sleeved on the trapping tube, and the heating wire is wound around the surface of the heat-conducting layer. Compared to directly winding the heat-conducting layer and the heating wire onto the trapping tube, the combination of the heat-conducting layer and the heating wire can be directly removed from the trapping tube, making disassembly convenient. At the same time, it is not necessary to repeatedly wind the heating wire during disassembly and assembly, thus avoiding damage to the heating wire.
[0010] Furthermore, the heat-conducting layer is a cylindrical sleeve.
[0011] Furthermore, the heating wire includes a resistance wire and an insulating layer, with the insulating layer wrapping around the resistance wire. The presence of multiple resistance wires connected in parallel increases the heating area and results in more uniform heat generation. Additionally, the multi-strand heating wire design promotes uniform heating of the trap and improves temperature control accuracy.
[0012] Preferably, the flow rate of the mass flow controller is set to 70-80 ml / min.
[0013] Furthermore, the purging and trapping device also includes a temperature control device configured to collect and monitor the temperature of the trap in real time. The temperature control device includes a temperature control circuit and a temperature sensor. The temperature sensor is installed on the trap, and the temperature control circuit is connected to the temperature sensor. When a heating command is issued, the temperature control circuit controls the voltage output using a PID algorithm to achieve precise temperature control of the trap. When the temperature sensor reads a temperature exceeding a certain set range, it indicates a temperature abnormality and stops voltage output.
[0014] Furthermore, the pressure gauge is configured to control the mass flow controller based on pressure feedback.
[0015] The purging process is as follows: A water sample containing VOCs is collected into a flow cell. Inert gas is used as the purging gas and enters from the purging gas inlet. The flow rate is controlled by a mass flow controller to keep the flow rate constant for a certain period of time to continuously purge the interior of the water sample, causing the VOCs components in the water sample to escape. After passing through a water removal trap to remove water, the sample enters a trap for adsorption and concentration. At the same time, the sampling flow rate of the sampling pump connected to the end of the trap is kept the same as the purging flow rate. Finally, the adsorbed gas is discharged from the outlet.
[0016] The automatic airtightness detection process is as follows:
[0017] With the three-way valve closed, it connects the multi-way valve and the three-way valve; with the purge valve closed, it connects the three-way valve and the injection valve; with the injection valve closed, it connects the purge valve and the multi-way valve. The purge gas enters through the purge gas inlet, passes through the mass flow controller, through the three-way valve, and flows through the purge valve, injection valve, multi-way valve, water trap, trap, multi-way valve, and three-way valve, finally returning to the three-way valve. After the purge gas has been introduced for a period of time, the mass flow controller is set to 0. At this point, the above flow path forms a closed loop. The pressure gauge records the pressure and monitors pressure changes to determine the airtightness of the gas path.
[0018] This utility model has the following beneficial effects:
[0019] (1) In this utility model, the purge gas flow rate is controlled by a mass flow controller and the real-time pressure value is monitored by a pressure gauge. The sample is purged and the purge flow rate is adjusted by pressure change feedback. The components in the flow cell are blown out by the purge gas and enter the dehydration trap for dehydration before finally entering the trap for enrichment. During the purging and enrichment process, the sampling pump is turned on to balance the gas pressure in the pipeline with the atmospheric pressure and prevent the purge gas from overflowing. After the low-temperature enrichment is completed, the trap is heated to decompose, and the multi-port valve switches to send the decomposed sample into the detector. By setting the sampling pump and pressure gauge in the flow path, the headspace pressure of the flow cell is balanced during the purging and trapping process, so that the purge gas just enters the device without overflowing, thereby improving the purging and trapping efficiency.
[0020] (2) By controlling the opening and closing of the valve ports of the multi-way valve, the three-way valve, the purge valve and the injection valve, the flow path can be automatically tested for air tightness, which helps to prevent gas leakage. Attached Figure Description
[0021] Figure 1 This is the flow diagram of this utility model.
[0022] Figure 2 This is a comparison chart of the purging efficiency of this utility model and existing technologies.
[0023] Figure 3 This is a schematic diagram of the trap structure in this utility model.
[0024] Figure 4 This is a schematic diagram of the heating wire in this utility model.
[0025] Figure 5 This is a graph showing the temperature rise of the trap of this utility model at room temperature.
[0026] Figure 6 This is a comparison chart of the temperature rise curves of three traps of this utility model at room temperature. Detailed Implementation
[0027] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings. It should be noted that the embodiments are only specific descriptions of the utility model and should not be regarded as limitations on the utility model. The purpose of the embodiments is to enable those skilled in the art to better understand and reproduce the technical solution of this utility model. The protection scope of this utility model should still be determined by the scope defined in the claims.
[0028] like Figure 1 As shown, this utility model provides a purge and trap device, including a mass flow controller 1, a pressure gauge 2, a flow cell 3, a trap 4, a dewatering trap 5, a sampling pump 6, a multi-way valve 7, and a detector 8. The mass flow controller 1 is installed at the purge gas inlet 9. The mass flow controller 1 is connected to the pressure gauge 2. The pressure gauge 2 is connected to the flow cell 3 via a three-way valve 10. The flow cell 3 is connected to the multi-way valve 7. The first valve port 71 of the multi-way valve 7 is connected to the dewatering trap 5. The dewatering trap 5 is connected to the trap 4. The trap 4 is connected to the second valve port 72 of the multi-way valve 7. The multi-way valve 7 is connected to the three-way valve 10 and the sampling pump 6 via a three-way valve 11. The sampling pump 6 is connected to the outlet 12. The third valve port 73 of the multi-way valve 7 is connected to the carrier gas inlet 13. The fourth valve port 74 of the multi-way valve 7 is connected to the detector 8. The purge gas flow is controlled by the mass flow controller 1. The pressure gauge 2 is configured to control the mass flow controller 1 based on pressure feedback. The sample is purged by monitoring the real-time pressure value using pressure gauge 1. Components in the flow cell 3 are purged by the purge gas, enter the dehydration trap 5 for dehydration, and finally enter the collection trap 4 for enrichment. During purging and enrichment, sampling pump 6 is activated to balance the gas pressure in the pipeline with atmospheric pressure, preventing purge gas leakage. After low-temperature enrichment, the collection trap 4 is heated for desorption, and multi-port valve 7 switches to send the desorbed sample into the detector. By setting sampling pump 6 and pressure gauge 2 in the flow path, the headspace pressure of the flow cell 3 is balanced during the purging and collection process, ensuring that all the purge gas enters the device without overflowing, thus improving the purging efficiency. Compared to existing technologies that do not balance the headspace pressure of the flow cell, this application has better purging efficiency for various purge gases (inert gases), such as... Figure 2 As shown.
[0029] The sampling flow rate of the sampling pump 6 is set to be the same as the purging flow rate of the purging gas.
[0030] A purge valve 14 is also provided between the three-way valve 10 and the flow cell 3. A sample inlet valve 15 is also provided between the flow cell 3 and the multi-way valve 7. By providing the multi-way valve 7, three-way valve 10, three-way valve 11, purge valve 14 and sample inlet valve 15, and by controlling the closing and opening of the valve ports of the multi-way valve 7, three-way valve 10, three-way valve 11, purge valve 14 and sample inlet valve 15, the flow path can automatically perform air tightness detection, which helps to prevent gas leakage.
[0031] Preferably, the three-way valve 11 is a three-way solenoid valve.
[0032] like Figure 3-4 As shown, the trap 4 includes a trapping tube 41, a heat-conducting layer 42, and a heating wire 43. The heat-conducting layer 42 is sleeved on the trapping tube 41, and the heating wire 43 is wound around the surface of the heat-conducting layer 42. Compared to directly winding it onto the trapping tube, the combination of the heat-conducting layer 42 and the heating wire 43 can be directly detached from the trapping tube 41, making disassembly convenient. Furthermore, it avoids repeatedly winding the heating wire 43 during disassembly, preventing damage to the heating wire. The heat-conducting layer is a cylindrical sleeve. The heating wire 43 includes a resistance wire 431 and an insulating layer 432, with the insulating layer 432 wrapping around the outside of the resistance wire 431. The multiple strands of resistance wire 431 connected in parallel increase the heating area and produce more uniform heat. Additionally, the design of multiple heating wires 431 helps to ensure uniform heating of the trap 4 and improves temperature control accuracy.
[0033] like Figure 5 As shown, under room temperature conditions, the temperature rise rate of the trap 4 in this scheme reaches 25℃ / s, and the temperature control accuracy is high with no obvious high temperature overshoot. Compared with traditional heating devices, the temperature rise rate is faster, which is beneficial to extending the service life of the trap.
[0034] like Figure 6 As shown, under room temperature conditions, three sets of trap temperature curves were continuously tested. After stabilization, the temperature fluctuation of each component was ≤±3℃, with no obvious high-temperature overshoot phenomenon, which improved the consistency of the test results.
[0035] Preferably, the purging and trapping device further includes a temperature control device configured to collect and monitor the temperature of the trapping trap 4 in real time. The temperature control device includes a temperature control circuit and a temperature sensor. The temperature sensor is installed on the trapping trap, and the temperature control circuit is connected to the temperature sensor. When a heating command is issued, the temperature control circuit controls the voltage output through a PID algorithm to achieve precise temperature control of the trapping trap 4. When the temperature sensor reads a temperature exceeding a certain set temperature range, it indicates a temperature abnormality and stops voltage output.
[0036] The purging process is as follows: A water sample containing VOCs is collected into the flow cell 3. Inert gas is used as the purging gas and enters from the purging gas inlet. The flow rate is controlled by the mass flow controller 1 to keep the flow rate constant and continuously purge the interior of the water sample for a certain period of time, causing the VOCs components in the water sample to escape. After passing through the water removal trap 5 to remove water, the sample enters the trap 4 for adsorption and concentration. At the same time, the sampling flow rate of the sampling pump 6 connected to the end of the trap 4 is kept the same as the purging flow rate. Finally, the adsorbed gas is discharged from the outlet 12.
[0037] Connect sampling pump 6 to the back end of the flow path. The sampling pumping speed was tested at approximately 40 mL / min. Based on the pumping speed test results, different purging flow rates within the range of 40–120 mL / min were set and run continuously for 5 minutes. The appropriate purging flow rate was selected according to the liquid level in the inner cup at the end of the operation and the overflow of bubbles during the operation. The test results are shown in Table 1 below:
[0038] Table 1
[0039]
[0040] As can be clearly seen from Table 1, when the purge flow rate is controlled within the range of 70-80 mL / min, the purge volume can be kept relatively fixed, with no obvious gas overflow, which can improve the sample recovery rate.
[0041] The automatic airtightness detection process is as follows:
[0042] Three-way valve 11 is closed, connecting multi-way valve 7 and three-way valve 10; purge valve 14 is closed, connecting three-way valve 10 and injection valve 15; injection valve 15 is closed, connecting purge valve and multi-way valve 7. Purge gas enters through the purge gas inlet, passes through mass flow controller 1, through three-way valve 10, through purge valve 14, injection valve 15, multi-way valve 7, water removal trap 5, collection trap 4, and multi-way valve 7, finally returning to three-way valve 10. After purge gas has been introduced for a period of time, mass flow controller 1 is set to 0. At this time, the above flow path forms a closed loop. The pressure gauge records the pressure and monitors pressure changes to determine the airtightness of the gas path.
[0043] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.
[0044] It should be noted that any technical features not described in detail in this utility model can be implemented by any existing technology.
Claims
1. A purge and capture device, characterized in that, The system includes a mass flow controller, a pressure gauge, a flow cell, a trap, a dewatering trap, a sampling pump, a multi-way valve, and a detector. A mass flow controller is installed at the purge gas inlet. The mass flow controller is connected to the pressure gauge, which is connected to the flow cell via a three-way valve. The flow cell is connected to the multi-way valve. The first port of the multi-way valve is connected to the dewatering trap, which is connected to the trap. The trap is connected to the second port of the multi-way valve. The multi-way valve is connected to a three-way valve and the sampling pump via a three-way valve. The sampling pump is connected to the outlet. The third port of the multi-way valve is connected to the carrier gas inlet. The fourth port of the multi-way valve is connected to the detector.
2. The purging and collecting device according to claim 1, characterized in that, The sampling flow rate of the sampling pump is set to be the same as the purging flow rate of the purging gas.
3. The purging and collecting device according to claim 1, characterized in that, A purge valve is also provided between the tee and the flow pool.
4. The purging and collecting device according to claim 1, characterized in that, An injection valve is also provided between the flow cell and the multi-way valve.
5. The purging and trapping device according to claim 1, characterized in that, The three-way valve is a three-way solenoid valve.
6. The purge and collection device according to claim 1, characterized in that, The trap includes a trapping tube, a heat-conducting layer, and a heating wire. The heat-conducting layer is sleeved on the trapping tube, and the heating wire is wound around the surface of the heat-conducting layer.
7. A purging and trapping device according to claim 6, characterized in that, The heat-conducting layer is a cylindrical sleeve.
8. A purging and trapping device according to claim 6, characterized in that, The heating wire includes a resistance wire and an insulating layer, with the insulating layer wrapped around the outside of the resistance wire.
9. The purging and collecting device according to claim 1, characterized in that, The purging and trapping device also includes a temperature control device, which is configured to collect the temperature of the trap in real time and monitor the temperature of the trap.
10. A purge and capture device according to claim 1, characterized in that, The pressure gauge is configured to control the mass flow controller based on pressure feedback.