A method and apparatus for purging and capturing high efficiency defoaming device

Abstract

The application discloses a high-efficiency defoaming device for blowing and trapping. The defoaming device comprises a blowing pipe, a quartz sieve plate, a gold-plated sieve net, a heating device, a foam sensor, a fixed metal nut and a ceramic sand core. The blowing pipe is connected with the heating device. The fixed metal nut and the foam sensor are arranged on the heating device. The heating device is additionally provided with a liquid inlet and a liquid outlet at the top. The quartz sieve plate is arranged at the connection position of the heating device and the blowing pipe. The gold-plated sieve net is arranged in the heating device. The liquid outlet is connected with a liquid outlet pipe. The liquid inlet is connected with a liquid inlet pipe. The ceramic sand core is arranged in the blowing pipe. The gold-plated sieve net is used to destroy the gas-liquid interface of the foam, so that the foam generated in the blowing process is prevented from entering the trapping pipe and the transmission line.

Description

TECHNICAL FIELD

[0001] The present application relates to a defoaming device and method, in particular to a high-efficiency defoaming device and method for purging and trapping. BACKGROUND

[0002] Purge and trap method: a commonly used method for detecting volatile and semi-volatile organic compounds in water. Through the purge tube, the organic compounds in the water sample are blown off by nitrogen, and then trapped by the trap tube. After the organic compounds in the water sample are completely blown off, stop purging, and quickly heat the trap tube, backflush desorption, and blow the desorbed organic compounds into the gas chromatograph or gas chromatograph-mass spectrometer for detection and analysis.

[0003] Purge and trap equipment has been widely used to extract volatile organic compounds (VOCs) from solid or liquid sample matrices for introduction into analytical systems for separation and identification. In many cases, VOCs are concentrated into absorbent trap traps, and then thermally desorbed into a gas chromatograph. The range of sample matrices includes soil, plastic, food, spice, perfume, emulsion and water. Purge and trap sample concentration has developed into a standardized protocol for analyzing environmental samples (i.e. soil, water, etc.).

[0004] Inert gas (purge gas) such as helium or nitrogen is purged at a certain flow rate to the aqueous sample. Usually, the purge gas flow passes through a frit placed at the bottom of the sample part of the purge tube, and the frit disperses the gas into many fine streams to increase the surface contact of the gas with the sample to extract VOCs. However, for samples prone to foaming, using conventional purging can easily generate a large amount of bubbles, which, if left unchecked, can contaminate the trap and the transfer line, and even cause the entire instrument to be scrapped. Today, most purge and trap concentrators have a foam detection sensor that will shut off the purge gas and stop the sampling process when foam is detected, or continue in "safe mode" to prevent costly repairs. However, this operation will result in the sample being wasted and considered unusable, and the laboratory will have to re-run the sample (if available) or contact the customer to send a new sample. In order to solve the above problems, patent US10 / 348035 uses a defoaming agent (such as Dow Corning organic silicon RID emulsion) to pretreat the sample prone to foaming, which reduces its surface tension, however, this treatment may cause concerns about the integrity of the sample, causing experimental data distortion. Patent US12 / 861007 uses the following scheme: after detecting the foaming sample, the purge gas is redirected to a second inlet of the purge tube, and the generated foam is prevented from entering the trap and the transfer line by means of a counterflow, thereby achieving an uninterrupted purging process. However, this method dilutes the target components of the purge, reducing the sensitivity of the target components, and due to the significant increase in gas flow into the trap, some low-carbon components penetrate the filler, reducing their recovery rate, which is not conducive to further reducing the detection limit of the instrument.

[0005] Applicants summarize that the prior art has the following problems:

[0006] 1. In the process of purging and trapping water samples, due to the huge difference in sample properties, when the sample contains surfactants or detergents, the purging and trapping method often occurs foaming phenomenon. Sample foaming not only easily damages the trapping tube, causes irreversible contamination of the transfer line, and in extreme cases, also affects the separation and analysis efficiency of the chromatographic column and detector, resulting in the whole instrument being scrapped;

[0007] 2. For samples prone to foaming, the common practice in the industry is to add a chemical defoamer, which can effectively solve the problem of sample foaming, but adding an additional defoamer to the sample may change the properties of the sample, leading to distorted test results;

[0008] 3. For another physical defoaming method, by introducing an additional gas into the purge tube, preventing bubbles from entering the trapping trap and the transfer line, not only dilutes the sample, reduces the sensitivity of the target component, and significantly increases the purge gas entering the trapping tube, resulting in a breakthrough effect of low carbon components on the packing, which is not conducive to reducing the instrument detection limit of low carbon components. SUMMARY

[0009] To solve the problems caused by sample foaming, and to overcome the drawbacks of the current defoaming scheme, the present patent proposes a high-efficiency defoaming scheme for purging and trapping. The present invention uses a high-temperature gold-plated screen to break the gas-liquid interface of the foam, preventing the foam generated during purging from entering the trapping tube and the transfer line.

[0010] A high-efficiency defoaming device for purging and trapping, the defoaming device comprises a purge tube, a quartz sieve plate, a gold-plated screen, a heating device, a foam sensor, a fixed metal nut, and a ceramic sand core; the purge tube is connected with the heating device, the heating device is provided with a fixed metal nut and a foam sensor; the top of the heating device is also provided with a liquid inlet and a liquid outlet; the heating device is provided with a quartz sieve plate at the connection with the purge tube; the heating device is provided with a gold-plated screen inside; the liquid outlet is connected with a liquid outlet pipe; the liquid inlet is connected with a liquid inlet pipe; the purge tube is provided with a ceramic sand core inside.

[0011] Further, the sealing gasket between the purge tube and the fixed metal nut is made of PTFE material, and the pipes connected to the liquid inlet and the liquid outlet are both 1 / 16 stainless steel inert pipes, wherein the end of the liquid inlet pipe extends below the quartz sieve plate.

[0012] Further, the gold-plated screen is a circular screen with a diameter of 10 mm, made of stainless steel screen with a wire diameter of 0.1 mm and a pore size of 0.32 mm, and plated with gold, with a gold layer thickness of 1-1.5 um.

[0013] Further, the quartz sieve plate is a round hole type sieve plate, the hole size is 2-3 mm, which is fixed in the purge pipe by sintering process, and its main function is to prevent the gold-plated sieve mesh from leaking into the liquid area of the purge pipe. The round hole is used for the metal pipeline passing through the liquid inlet and the liquid outlet.

[0014] Further, the heating device is a heating block with a heating rod and a PT100 temperature measuring element, which wraps the spherical part of the purge pipe inside, heats the gold-plated sieve mesh inside, and controls the temperature of the heating block by adjusting the duty cycle and PID parameters. The highest heating temperature is 200℃.

[0015] Further, the foam sensor is placed between the heating device of the purge pipe and the fixed metal nut. For the part of the bubbles that do not break after passing through the high-temperature gold-plated sieve mesh, the foam sensor monitors the foam, then triggers the stop purge command, and at the same time, the temperature of the heating device is increased (20℃ higher than the existing heating device). After the temperature is stable, the purge command is restarted. If the foam is still monitored, the above command is repeated. But the highest temperature of the heating device cannot exceed 200℃ (above 200℃, PTFE material may release other components, affecting the test). If the foam sensor still monitors the foam during the purge process after reaching 200℃, stop this purge, and discharge the analysis sample.

[0016] Further, the foam sensor uses an optical sensor, which consists of a flat optical fiber and a fiber amplifier, and uses a 200mm diffuse reflection. When the sample produces bubbles, the rising bubbles will interrupt the light signal transmission between the transmitter and the detector.

[0017] Further, the signal transmitted to the mainboard by the foam sensor after detecting the foam is a high-frequency signal.

[0018] The use method of the device includes the following steps:

[0019] 1) In the initial state, ensure that the liquid inlet pipe and the liquid outlet pipe are below the quartz sieve plate, and the bottom end of the liquid outlet pipe needs to contact the ceramic sand core. The spherical part of the purge pipe needs to be filled with not less than 10 pieces of gold-plated sieve mesh, and the temperature of the spherical part heating device is set at 150℃.

[0020] 2) Inject 1-5ml of liquid into the purge pipe from the liquid inlet, set the purge flow rate to 40-60ml / min, and purge the liquid in the purge pipe.

[0021] 3) In the purging process, when the foam sensor detects foam, the foam sensor will send a high-frequency signal to the mainboard at this time, set the purging flow to 0ml / min, then set the ball-shaped part heating device temperature to 170℃, and after the temperature is stable, purging is carried out according to the time point when the last purging is stopped;

[0022] 4) After the ball-shaped part heating device temperature is increased to 170℃, if no foam is monitored in the subsequent purging, the heating temperature is continued until the end of the current purging process; when the foam is monitored again in the subsequent purging process, step 3 is repeated, the mainboard receives the high-frequency signal of the foam sensor, the purging flow is set to 0ml / min, and the ball-shaped part heating device temperature is set to 190℃, and after the temperature is stable, purging is carried out according to the time point when the last purging is stopped;

[0023] 5) After the ball-shaped part heating device temperature is increased to 190℃, if no foam is monitored in the subsequent purging, the heating temperature is continued until the end of the current purging process; when the foam is monitored again in the subsequent purging process, the mainboard receives the third high-frequency signal of the foam sensor, then the current purging is stopped, the liquid in the purging tube is discharged, and the purging tube is cleaned twice with 90℃ deionized water.

[0024] Compared with the prior art, the advantages of the present application are:

[0025] 1) The defoaming device provided by the present application adopts high-temperature defoaming technology, does not add defoaming agent to the sample, and does not change the nature of the sample itself;

[0026] 2) The defoaming device provided by the present application does not need to introduce an additional gas into the purging tube, which overcomes the problems of sample dilution and low carbon components penetrating the filler. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The present application is used for purging and trapping efficient defoaming device;

[0028] Figure 2 The present application is used for purging and trapping efficient defoaming device; Figure 1 The present application is used for purging and trapping efficient defoaming device;

[0029] Figure 3 The present application is used for purging and trapping efficient defoaming device;

[0030] The components in the figure are as follows:

[0031] The liquid outlet 100, the liquid inlet 101, the quartz sieve plate 102, the gold-plated sieve 103, the heating device 104, the foam sensor 105, the ceramic sand core 106, the liquid discharge pipe 107, the liquid inlet pipe 108, the fixed metal nut 109, and the purging pipe 110. DETAILED DESCRIPTION

[0032] The application will be further described in greater detail by way of specific embodiments, but the embodiments of the application are not limited thereto, and for the process parameters not particularly mentioned, conventional techniques can be referred to.

[0033] Example 1

[0034] As Figures 1-3As shown, a high-efficiency defoaming device for purging and trapping, the defoaming device comprising a purge tube 110, a quartz sieve plate 102, a gold-plated sieve 103, a heating device 104, a foam sensor 105, a fixed metal nut 109 and a ceramic sand core 106; the purge tube 110 is connected with the heating device 104, the heating device 104 is provided with the fixed metal nut 109 and the foam sensor 105; the top of the heating device 104 is further provided with a liquid inlet 101 and a liquid outlet 100; the heating device 104 is provided with the quartz sieve plate 102 at the connection with the purge tube 110; the heating device 104 is provided with the gold-plated sieve 103 inside; the liquid outlet 100 is connected with a liquid outlet pipe 107; the liquid inlet 101 is connected with a liquid inlet pipe 108; the purge tube 110 is provided with the ceramic sand core 106 inside. The sealing gasket between the purge tube and the fixed metal nut is made of PTFE material, and the pipes connected with the liquid inlet and the liquid outlet are all 1 / 16 stainless steel inert pipes, wherein the end of the liquid inlet pipe of the liquid inlet 101 extends below the quartz sieve plate 102. The gold-plated sieve 103 is a circular sieve with a diameter of 10 mm, which is made of stainless steel sieve with a wire diameter of 0.1 mm and a hole diameter of 0.32 mm and plated with gold, and the thickness of the gold layer is 1-1.5 um. The quartz sieve plate 102 is a circular hole type sieve plate with a hole size of 2-3 mm, which is fixed in the purge tube by sintering process, and its main function is to prevent the gold-plated sieve from leaking into the liquid area of the purge tube, and the circular hole is used for the metal pipes passing through the liquid inlet and the liquid outlet. The heating device 104 is a heating block with a heating rod and a PT100 temperature measuring element, which wraps the spherical part of the purge tube inside, heats the gold-plated sieve inside, and controls the temperature of the heating block by adjusting the duty cycle and PID parameters, and the maximum heating temperature is 200℃. The foam sensor 105 is placed between the heating device 104 of the purge tube and the fixed metal nut 109, and for the part of the bubbles that do not break after passing through the high-temperature gold-plated sieve 103, the foam sensor 105 monitors the foam, then triggers the stop purging command, and at the same time increases the temperature of the heating device 104, and after the temperature is stable, the purging command is restarted, if the foam is still monitored, the above command is repeated; but the maximum temperature of the heating device 104 cannot exceed 200℃, if it reaches 200℃, the foam sensor 105 still monitors the foam during purging, then stops this time of purging, and discharges the analysis sample. The foam sensor 105 adopts an optical sensor, which is composed of a flat plate optical fiber and an optical fiber amplifier, adopts a 200mm diffuse reflection, and when the sample produces bubbles, the rising bubbles will interrupt the light signal transmitted between the emitter and the detector. After the foam sensor 105 detects the foam, the signal transmitted to the mainboard is a high-frequency signal.

[0035] Example 2

[0036] The high-efficiency defoaming device for purging and trapping in the embodiment is the same as that described in Embodiment 1.

[0037] 1. In the initial state, the liquid inlet pipe 108 and the liquid outlet pipe 107 are placed in the designated positions of the purging pipe, wherein the bottom end of the liquid outlet pipe 107 needs to contact the ceramic sand core 106, the bottom end of the liquid inlet pipe 108 needs to extend below the quartz sieve plate 102, 15 pieces of gold-plated sieve mesh 103 are filled into the spherical part of the purging pipe, and the temperature of the spherical part heating device 104 is set to 150°C.

[0038] 2. 5ml of liquid (more prone to foaming) is injected into the purging pipe from the liquid inlet 101, the purging flow is set to 40ml / min, the purging time is 11min, and the liquid in the purging pipe is purged.

[0039] 3. When the foam sensor 105 detects foam at 5min of purging, the foam sensor 105 will send a high-frequency signal to the mainboard, the purging flow is set to 0ml / min to avoid blowing the foam in the purging pipeline and polluting the pipeline, then the temperature of the spherical part heating device 104 is set to 170°C, after waiting for 5min, the foam in the spherical part of the purging pipe 110 is broken, the purging is carried out according to the time point (5min) of the last stop purging, the purging flow is restored to 40ml / min, and the subsequent purging process is continued for 6min (no foam is monitored in the subsequent purging process), until the purging time sequence ends normally.

[0040] Embodiment 3

[0041] The high-efficiency defoaming device for purging and trapping in the embodiment is the same as that described in Embodiment 1.

[0042] 1. In the initial state, the liquid inlet pipe 108 and the liquid outlet pipe 107 are placed in the designated positions of the purging pipe, wherein the bottom end of the liquid outlet pipe 107 needs to contact the ceramic sand core 106, the bottom end of the liquid inlet pipe 108 needs to extend below the quartz sieve plate 102, 15 pieces of gold-plated sieve mesh 103 are filled into the spherical part of the purging pipe, and the temperature of the spherical part heating device 104 is set to 150°C.

[0043] 2. 5ml of liquid (more prone to foaming) is injected into the purging pipe from the liquid inlet 101, the purging flow is set to 40ml / min, the purging time is 11min, and the liquid in the purging pipe is purged.

[0044] 3. When the foam sensor 105 detects foam at 3 min, the foam sensor 105 sends a high frequency signal to the main board, sets the purge flow to 0 ml / min to avoid blowing foam into the purge line and polluting the line, then sets the temperature of the ball-shaped part of the heating device 104 to 170°C, waits for 5 min, and after the foam in the ball-shaped part of the purge tube 110 is broken, purges according to the last stop time point (3 min), restores the purge flow to 40 ml / min, and continues to purge for another 8 min according to the set program;

[0045] 3. When the foam sensor 105 detects foam again at 6 min, the foam sensor 105 sends a high frequency signal to the main board, sets the purge flow to 0 ml / min to avoid blowing foam into the purge line and polluting the line, then sets the temperature of the ball-shaped part of the heating device 104 to 190°C, waits for 5 min, and after the foam in the ball-shaped part of the purge tube 110 is broken, purges according to the last stop time point (6 min), restores the purge flow to 40 ml / min, and continues to purge for another 5 min according to the set program;

[0046] 4. When the foam sensor 105 detects foam again at 9 min, the foam sensor 105 sends a high frequency signal to the main board, sets the purge flow to 0 ml / min to avoid blowing foam into the purge line and polluting the line, then sets the temperature of the ball-shaped part of the heating device 104 to 210°C, which may cause some VOC components to be emitted from the PTFE seal and interfere with subsequent testing, at this time the main board will terminate the purge sequence and discharge the liquid in the purge tube, ending this analysis.

Claims

1. A high-efficiency defoaming device for purge and capture, characterized in that, The device includes a purge pipe (110), a quartz sieve plate (102), a gold-plated screen (103), a heating device (104), a foam sensor (105), a fixing metal nut (109), and a ceramic sand core (106). The purge pipe (110) is connected to the heating device (104), and the heating device (104) is equipped with a fixing metal nut (109) and a foam sensor (105). The top of the heating device (104) is also equipped with a liquid inlet (101) and a liquid outlet (100). A quartz sieve plate (102) is provided at the connection between the heating device (104) and the purge pipe (110). A gold-plated screen (103) is provided inside the heating device (104). A liquid outlet (100) is connected to a liquid outlet pipe (107). A liquid inlet pipe (108) is connected to the liquid inlet (101). The purge pipe (110) is connected to the heating device (104). The internal structure is equipped with a ceramic sand core (106); the gold-plated screen (103) is a circular screen with a diameter of 10mm, made of 60-mesh stainless steel screen with a wire diameter of 0.1mm and an aperture of 0.32mm, and the gold layer thickness is 1-1.5μm; the quartz screen plate (102) is a circular hole screen plate with a hole size of 2-3mm, which is fixed inside the purge tube by sintering process; the heating device (104) is a heating block with a built-in heating rod and PT100 temperature measuring element, which wraps the spherical part of the purge tube inside, and the temperature of the heating block is controlled by adjusting the duty cycle and PID parameters, with a maximum heating temperature of 200℃; the foam sensor (105) is an optical sensor, which consists of a flat optical fiber and an optical fiber amplifier, and uses 200mm diffuse reflection; the gold-plated screen (103) is irregularly arranged in the spherical part.

2. The high-efficiency defoaming device for purging and trapping as described in claim 1, characterized in that, The sealing gasket between the purge pipe and the fixed metal nut is made of PTFE. The pipes connecting the inlet and outlet are 1 / 16 stainless steel inert pipes. The end of the inlet pipe (101) extends below the quartz sieve plate (102).

3. The high-efficiency defoaming device for purge and trapping as described in claim 1, characterized in that, The foam sensor (105) is positioned between the purge tube heating device (104) and the fixing metal nut (109). If some bubbles do not break after passing through the high-temperature gold-plated screen (103), the foam sensor (105) will trigger a stop purging command after detecting the foam. At the same time, the temperature of the heating device (104) will be increased. After the temperature stabilizes, the purging command will be restarted. If foam is still detected, the above command will be repeated. However, the maximum temperature of the heating device (104) cannot exceed 200°C. If the foam sensor (105) still detects foam during the purging process after reaching 200°C, the purging will be stopped and the analytical sample will be discharged.

4. The high-efficiency defoaming device for purging and trapping as described in claim 1, characterized in that, After the foam sensor (105) detects foam, it transmits a high-frequency signal to the motherboard.

5. A method of using the device according to any one of claims 1-4, comprising the following steps: In the initial state, ensure that the inlet pipe (108) and outlet pipe (107) are below the quartz sieve plate (102), and that the bottom end of the outlet pipe (107) is in contact with the ceramic sand core (106). The spherical part of the purge pipe is filled with no less than 10 gold-plated screens (103), and the temperature of the heating device (104) in the spherical part is set at 150°C. Inject 1-5 ml of liquid into the purge tube through the inlet (101), set the purge flow rate to 40-60 ml / min, and purge the liquid in the purge tube. During the purging process, when the foam sensor (105) detects foam, the foam sensor (105) will send a high frequency signal to the main board to set the purging flow rate to 0 ml / min. Then, the temperature of the spherical heating device (104) is set to 170°C. After the temperature stabilizes, purging is carried out according to the last time when purging was stopped. After the temperature of the spherical heating device (104) is raised to 170°C, if no foam is detected during subsequent purging, the heating temperature is maintained until the end of the current purging process. When foam is detected again during subsequent purging, step 3 is repeated. After the main board receives the high frequency signal from the foam sensor (105), the purging flow rate is set to 0 ml / min, and the temperature of the spherical heating device (104) is set to 190°C. After the temperature stabilizes, purging is performed according to the time point when purging was stopped last time. After the temperature of the spherical heating device is raised to 190°C, if no foam is detected during subsequent purging, the heating temperature is maintained until the end of the current purging process. When foam is detected again during subsequent purging, the main board receives the third high-frequency signal from the foam sensor, stops the current purging, and begins to execute the drain command to drain the liquid in the purging tube and clean the purging tube twice with 90°C deionized water.

6. The method according to claim 5, characterized in that, In step 2), the purging flow rate is 40~60 ml / min.

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